11.7: Roundworms - Biology

11.7: Roundworms - Biology

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When most people picture a worm, do they picture a roundworm?

Actually, they do not. Whereas flatworms are flat, roundworms obviously appear round. With over 80,000 species, there are plenty of different types of roundworms. But these are still not the types of worms most people picture when they think of worms.


Roundworms make up the phylum Nematoda. This is a very diverse animal phyla. It has more than 80,000 known species.

Structure and Function of Roundworms

Roundworms range in length from less than 1 millimeter to over 7 meters (23 feet) in length. As their name suggests, they have a round body. This is because they have a pseudocoelom. This is one way they differ from flatworms. Another way is their complete digestive system. It allows them to take in food, digest food, and eliminate wastes all at the same time.

Roundworms have a tough covering of cuticle on the surface of their body. It prevents their body from expanding. This allows the buildup of fluid pressure in the pseudocoelom. As a result, roundworms have a hydrostatic skeleton. This provides a counterforce for the contraction of muscles lining the pseudocoelom. This allows the worms to move efficiently along solid surfaces.

Roundworm Reproduction

Roundworms reproduce sexually. Sperm and eggs are produced by separate male and female adults. Fertilization takes place inside the female organism. Females lay huge numbers of eggs, sometimes as many as 100,000 per day! The eggs hatch into larvae, which develop into adults. Then the cycle repeats.

Ecology of Roundworms

Roundworms may be free-living or parasitic. Free-living worms are found mainly in freshwater habitats. Some live in soil. They generally feed on bacteria, fungi, protozoans, or decaying organic matter. By breaking down organic matter, they play an important role in the carbon cycle.

Parasitic roundworms may have plant, vertebrate, or invertebrate hosts. Several species have human hosts. For example, hookworms, like the one in Figure below, are human parasites. They infect the human intestine. They are named for the hooks they use to grab onto the host’s tissues. Hookworm larvae enter the host through the skin. They migrate to the intestine, where they mature into adults. Adults lay eggs, which pass out of the host in feces. Then the cycle repeats.

Hookworm Parasite. Hookworms like this one are common human parasites.

Tiny pinworms are the most common roundworm parasites of people in the U.S. In some areas, as many as one out of three children are infected. Humans become infected when they ingest the nearly microscopic pinworm eggs. The eggs hatch and develop into adults in the host’s digestive tract. Adults lay eggs that pass out of the host’s body to continue the cycle. Pinworms have a fairly simple life cycle with only one host.


  • Roundworms make up the phylum Nematoda.
  • Roundworms have a pseudocoelom and hydrostatic skeleton. Their body is covered with tough cuticle.
  • Free-living roundworms are found mainly in freshwater habitats.
  • Parasitic roundworms have a variety of hosts, including humans.


  1. How do free-living nematodes contribute to the carbon cycle?
  2. Apply what you know about pinworms to develop one or more recommendations for preventing pinworm infections in humans.
  3. Platyhelminthes and nematodes are both worms. Justify classifying them in different invertebrate phyla.


Viruses assigned to the genus have not yet been isolated or visualized by electron microscopy.

Nucleic acid

Alphanemrhavirus genomes consist of a single molecule of negative-sense, single-stranded RNA and range from approximately 11.5&ndash11.7 kb (Shi et al., 2016).


Alphanemrhavirus N, P, M, G and L proteins share sequence homology and/or structural characteristics with the cognate proteins of other rhabdoviruses. In Xinzhou nematode virus 4 (XzNV-4), ORF Mx overlaps the M ORF and encodes a putative 67 amino acid (7.6 kDa) protein of unknown function. This putative protein has not yet been identified in infected cells and it is not known if it is expressed.

Surprising details

While previous experiments on Arabidopsis had worked out some of the important genes and steps in making specialized cells, this new cell-by-cell data fills in additional details of development. The researchers found, for example, that cells might double-back on the developmental path they seemed to be following, and that it was also possible to jump ahead. They also noticed that there may be differences in the way new stem cells regulated transitions between cell types relative to old stem cells and whereas they had previously known of core steps in cell differentiation, they saw there were actually many small, seemingly continuous steps along the way.

One especially intriguing finding concerns a crucial gene, called SPEECHLESS, that plays a role in the formation of pores, called stomata, through which the plant exchanges gases and regulates water content. The Bergmann lab has studied SPEECHLESS extensively, but the new data hinted that it was expressed for a longer stretch of the developmental process than they expected. In a follow-up experiment, the researchers were able to selectively remove the gene after it completed its known role but sooner than the new data said it was done being expressed. Sure enough, the developmental programs went off track – and the researchers are now working to figure out why.

“It was a contradiction of what we thought we knew and it was really exciting,” Bergmann said. “It makes us want to dig in to other unexpected details – what might look like insignificant blips in the data – and see what we’ve missed.”

Bergmann credits Lopez-Anido and this work with inspiring several avenues of research, including reconsidering what it means to be a stem cell, reframing events that define final differentiation stages and reevaluating what it means to be born as a cell on the top versus bottom of a leaf.

11.7: Roundworms - Biology

Welcome Back!
Hope You Enjoy the Year in Biology! I look forward to being your instructor. The first couple of weeks will be largly introduction materials. Enjoy the year!

9/7 Wedsday: We will go over the Biology Syllabus and the Parent Contact Form (5 points) will be passed out to be collected Friday.
9/8 Thursday: We will take notes covering the major themes found in Biology as well as begin the scientific method. These notes and others for the first couple of weeks can be found in Chapter 1 Notes.
9/9 Friday: Parent Contact forms to be collected. Textbooks will be handed out. We will finish up the scientific method notes. In addition, we will observe how the scientific method is used in science writing, paying special notice to journal and thesis writing. If possible, we will view a video reviewing how the scientific method is used.

9/12 Monday:Collect Parent Contact Forms. Pass out textbooks and quia passwords. Continue notes from last week on themes in Biology.
9/15 Thursday: Chapter 1 Notes on the Scientific Method
9/15 Friday: Mythbuster Scientific Method Video aActivity

9/18 Monday: Chapter 1 Notes (Day 3): Graphing Notes This link is accessing an old file please see on the Chapter 1 Note on 9/8. The graphing notes can be found in their entirrty there.
9/19 Tuesday: Graphing Exercises and Scientific Method Worksheet 1 as well as Scientific Method Worksheet 2. All work is due tomorrow.
9/20 Wednesday: Collect work from yesterday. Go over the Lab Safety Form
9/21 Thursday: Review over metric conversions. The notes are found in Chapter 1 Notes from the previous week
9/22 Friday: Pill Bug Lab. Due at the end of the period

9/26 Monday: We will review over returned assignments and play a review game.
9/27 Tuesday:The Chapter 1 Review Guide and is due tomorrow.
9/28 Wednesday: Chapter 1 Exam. Review Guide due
9/29 Thursday: Chapter 15 Notes (Day1): Intro to Taxonomy
9/30 Friday: Chapter 15 Notes (Day 2): Dichotomous Keybr>

10/3 Monday:Continue notes on classification from Friday )
10/4 Tuesday: Chapter 15 Notes (Day 2): Dichotomous KeyDichotomous key activity and lab (no download
10/5 Wednesday: Chapter 15 (Day 3): Five Kingdom Chapter 1 Exams will be passed back and reviewed. .
10/6 Thursday: We will go outdoors for the Plant Classification Activity. Completed Data page is due Friday
10/7 Friday: Classification Worksheet Packet will be passed out. It is due Monday.

10/10 Monday: No School
10/11 Tuesday: Distribute graded exams and go over the correct answers. Use data from last Thursday to complete the tree classification activity. It is due tomorrow
10/12 Wednesday: Collect the tree classification activity. Finish Chapter 15 (Day 3) Notes: Cladistics and Evolutionary Systematics. Hand out the Review Guide Chapter 15 Review Guide 2011.
10/13 Thursday: Classification Video and Questionaire
10/14 Friday: Five Kingdom Survey Lab. Chapter 15 Exam on Monday.

10/17 Monday: Five Kingdom Lab
10/18 Tuesday: Review Guide is due. Chapter 15 Exam will be taken
10/19 Wednesday:Chapter 2 Notes (Day 1): History of Chemistry
10/20 Thursday: Chapter 2 Notes (Day 2): Atomic Structure
10/21 Friday: Students will work on Atomic Structure Activity Periodic Table. This assignment will be due Monday

10/23 Monday: Collect and go over atom drawings. BeginChapter 2 Notes (Day 3): Balancing Chemical Equations
10/24 Tuesday: Finish notes from yesterday and practice Blancing Equations. BeginChapter 2 Notes (Day 4): Properties of Water
10/25 Wednesday: Finish notes on water and solutions from previous day. Show a short video on the properties of water.
10/26 Thursday: Hand back and go over Taxonomy exams. Review over balancing equations
10/27 Friday: Water video and questionaire

10/31 Monday: Finish Day 4 Notes on Properties of Water and Solutions
11/1 Tuesday: PChapter 2 Notes (Day 5): pH Scale. Water Lab .
11/2 Wednesday:Chapter 2 Notes (Day 6): Organic Molecules
11/3 Thursday: Finish notes on Organic Molecules and Dehydration Synthesis. Give instructions on molecular modeling activity (link pending).
11/4 Friday: Work on Molecular Modeling Activity. Due Tuesday of Next Week.

11/7 Monday:Chapter 2 Notes (Day 7) Enzyme Action Biochem Review 2011 will be handed out.
11/8 Tuesday: Work on Review Guides. Molecular Models due tomorrow.
11/9 Wednesday: Biochemistry Exam postponed until Tuesday of next week.. Review Guides will be collected on Tuesday as well.

11/14 Monday: Finish notes on Enzymes. Review over Chapter. Skype Virtual Tutoring Session Tonight at 7:30. Make sure to get a free skype account in case you do not have on already. Make sure to email me your skype name.
11/15 Tuesday: Biochem Multiple Choice/Matching Exam. After exam, students will work on the Cell Theory Worksheet Which is due tomorrow
11/16 Wednesday: Biochem Review Guides due. Short Answer Biochem Exam distributed. Collect Cell Theory Worksheet.
11/17 Thursday: Chapter 3 Notes (Day 1): History of Cell Biology
11/18 Friday Chapter 3 Notes (Day 3): Bacteria Cell Structure Chapter 3 Notes (Day 2): Why Cells are Small

11/21 Monday: Hand back graded projects and exams. Gow over exams.
11/22 Tuesday: Finish notes on Bacteria cell structure. Show a video on bacteria cells.

11/29 Tuesday:Chapter 4 Notes (Day 4) Cellular Organelles
11/30 Wednesday:Chapter 3 Notes (Day 5): Cell Organelles
11/31 Thursday:Cell Poster Project Description
12/1 Friday: Work on Cell Posters. Bring Textbook. Due Tuesday.

12/5 Monday: Finish Chapter 3 Notes (Day 6): More Cell Structures
12/6 Tuesday: Poster Projects due at the begining of class. The Cell Review Guide will be passed out and some time will be given to work on it. Due day of exam.
12/7 Wednesday:Bacteria Cell Lab. Due tomorrow
12/8 Thursday: Cell and Electron Microscope Lab in the computer lab. Due Monday. Skype Tutoring tonight at 7:30-8:00. Make sure to go to to get a free skype name and get it to me by Thursday class. All those interested should let me know by the end of Thursday's class.
12/9 Friday: Review Guides and Cell Lab will be collected. Cell Exam will be given today.

12/12 Monday: Collect Virtual Cell and Electron Microscope Activity. Chapter 4 Notes (Day 1): Brownian Motion
12/13 Tuesday: Chapter 4 Notes (Day 2): Facilitated Diffusion
12/14 Wednesday: Preview Spectrophotometer Sunscreen Lab. Diffusion Demonstrations
12/15 Thursday: Spectrophotometer Sunscreen Lab ( due at the end of class)

12/19 Monday: Begin Chapter 4 Notes (Day 3): Cell Membrane Transport
12/20 Tuesday: Finish notes on Cell Membrane Transport
12/21 Wednesday: Pass out theChapter 4 Review Guide. Due Wednesday after break
12/22 Thursday: Watch a video that details material transport in cells. The test will be on the Wednesday after you return from break.
Have a Great Break!

1/3 Tuesday: Review over Chapter 4. Work on the Chapter 4 Review Guide
1/4 Wednesday: Chapter 4 Quiz. Chapter 5 Notes (Day 1): Cell Energy
1/5 Thursday: Chapter 5 Notes (Day 2): Light Reactions of Photosynthesis
1/6 Friday: Chapter 5 Notes (Day 3): The Calvin Cycle

1/9 Monday: Photosynthesis Video and Review of Light Reactions as well as the Calvin Cycle
1/10 Tuesday: Photosynthesis Bracelet Project will be explained and students will be given time to start it.
1/11 Wednesday: Time given to work on the Photosynthesis Review Guide. Students may then continue their Photosynthesis Bracelet Project
1/12 Thursday: Review chapter and provide time to work on project.
1/13 Friday: Photosynthesis review guide and Project due at beginning of period. Photosynthesis Test will be given

1/17 Tuesday: Pass out the Work on the plasmolysis lab. Results due at the end of the period.
1/18 Wednesday: Work on the 2011-2012 Midterm Review
1/19 Thursday: Work on the Midterm Review Guide

1/23 Monday: Midterm Short Answer Exam
1/24 Tuesday: Multiple Choice Midterm Exam. Review guide is due.
1/25 Wednesday: Chapter 5.2 Notes (Day 1) Cellular Respiration
1/26 Thursday: Chapter 5.2 Notes (Day 2): Anaerobic Respiration
1/27 Friday: Metabolism Video
2011-2012 Midterm Review

1/31 Tuesday: Revisit Chapter 5.2 Notes (Day 1): Cellular Respiration
2/1 Wednesday: Chapter 5.2 Notes (Day 2): Anaerobic Respiration
2/2 Thursday:Cellular Respiration Review Guide
2/3 Friday: Cellular Respiration Quiz. BeginChapter 6 Notes (Day 1): Introduction to Cellular Division

2/6 Monday: Chapter 6 Notes (Day 2) The Cell Cycle
2/7 Tuesday:Chapter 6 Notes (Day 3) Cell Cycle and Cancer
2/8 Wednesday: Online Mitosis Activity Due Friday
2/9 Thursday:Chapter 6 Notes (Day 4): Cell Cycle Control and Cancer 2/10 Friday: Collect online mitosis assignments (postponed). Go over the midterm exam

2/13 Monday: Online Mitosis Activity due Wednesday
2/14 Tuesday: Photosynthesis and Respiration Lab
2/15 Wednesday: Chapter 6 Notes (Day 4): Meiosis Collect Online Mitosis Lab
2/16 Thursday: Students will be given time to work on their Cell Cycle Project

2/21 Tuesday:Review over cancer and cyclins. Time given to work on project. Skype tutoring will take place from 7:30 to 8:00 tonight. Please let me know in advance if you are planning to attend and I need a skype name for each participant.
2/22 Wednesday:The Cell Cycle Review Guide will be handed out. Projects will be collected at the beginning of the period. Online assignment due next Friday.
2/23 Thursday: Cell Cycle Exam. Review Guide due
2/24 Friday: Go over how to write a science report. Science Report Form

2/27 Monday:Chapter 8 Notes (Day 1): Mendel
2/28 Tuesday: Chapter 8 Notes (Day 2): Mendel's Laws
2/29 Wednesday: Chapter 8 Notes (Day 3) Punnett Squares The Cartoon Cross Problems will be handed out. This assignment is due tomorrow.
3/1 Thursday: Collect and review over the cartoon cross problems. Begin Chapter 8 Notes (Day 4) Exceptions to Mendel's rules
3/1 Friday: Finish notes from yesterday. Pass back and go over the cell cycle exam.

3/5 Monday: Exceptions to Mendel's Rules notes. Check homework for period 3 only.
3/6 Tuesday: Chapter 8 Notes (Day 6) Inheritable Diseases
3/7 Wednesday:Pedigree Activity will be distributed and due tomorrow. Today is the deadline to take the cell cycle open note quiz on my website.
3/8 Thursday: Collect pedigree assignment. Begin Dragon Genetics Assignment.

3/13 Tuesday: Continue Dragon Genetics Lab (due Thursday). Collect Pedigree Activity. Skype tutoring tonight at 7:30 (postponed to Wed 5-5:30).
3/14 Wednesday: Cover the last topic for Chapter 8, Chapter 8 Notes (supplemental): Sickle-celled Anemia. Heredity Review Guide will be passed out. Skype tutoring 5:00-5:30 tonight. .
3/15 Thursday:
3/16 Friday: Collect Review Guide and Karyotype Activity. Heredity Exam

3/19 Monday: Bloodtyping Lab
3/20 Tuesday: Chapter 9 Notes (Day 1): History of DNA
3/21 Wednesday: Chapter 9 Notes (Day 2): DNA Structure
3/22 Thursday: Chapter 9 Notes (Day 3): DNA Replication
3/23 Friday: Begin DNA Replication Project

3/26 Monday: Chapter 9 Review Guide DNA Replication Project is due.
3/27 Tuesday: Strawberry DNA Extraction Lab
3/28 Wednesday: Chapter 9 Quiz. Pass back graded work.
3/29 Thursday: Chapter 10 Notes (Day 1): RNA Transcription
3/30 Friday: Chapter 10 Notes (Day 2): RNA Processing

4/2 Monday: Library Research on Cell Respiration and Enzymes. Overview or research resources and correctly referencing work.Documenting Research DocumentResearch Database Information
4/3 Tuesday:Chapter 10 Notes (Day 3): Protein Translation
4/4 Wednesday: Research in the Library

4/16 Monday:Chapter 10 Notes (Day 4): The lac Operon
4/17 Tuesday: Students will meet with their lab groups and develop a procedure and hypthesis for Friday's Lab on Cellular Respiration. Begin Chapter 10 Notes (Day 5) Mutations
4/18 Wednesday: Begin Molecular Genetics ProjectDue Monday.
4/19 Thursday: Chapter 10 Review Guide. Due Tuesday.
4/20 Friday: Cell Respiration Lab

Cell Respiration Lab Deadlines
Cellular Respiration Report Description
The rough draft of the report is due Wed., May 2nd for people attending the chorus and band trip.

4/23 Monday: Cell Respiration Lab. MolecularGenetics Project due. Skype Tutoring --> 7:30 tonight. Let me know in advance if you will be participating and I need your Skype name.
4/24 Tuesday: Cover information on Gene Technology Students participating on the chorus trip will take the Molecular Genetics Exam today and submit the completed review guide
4/25 Wednesday: Molecular Genetics Lab. Review Guides due.
4/26 Thursday:
Chapter 21 Notes (Day 1): Viruses and Bacteria
4/27 Friday: Electrophoresis Lab

4/30 Monday: The two copies of the rough draft are due for the Lab Report. We will spend the period editing the rough drafts.
5/1 Tuesday: Electrophoresis Lab
5/2 Wednesday: Chapter 21 Notes (Day 2) Bacteria Structure
5/3 Thursday: Chapter 21 Notes (Day 3): Bacterial Forms 5/4 Final Draft of Lab Report will be collected. Finish Bacteria Notes.

"Going to Work"
5/7 Monday: Hand back and go over the Molecular Genetics Exam. Finish notes on bacterial forms.
5/8 Tuesday: Chapter 21 Notes (Day 4): Types of Bacteria
5/9 Wednesday: Virus, Bacteria, Gene Tech Review Guide
5/10 Thursday: Ebola Video
5/11 Friday: Virus, Bacterai, and Gene Technology Quiz. Begin Chapter 22 Notes (Day 1): Introduction to Protists

5/14 Monday: Chapter 22 Notes (Day 1): Intro to Protists
5/15 Tuesday: Protist Video
5/16 Wednesday: Chapter 22 Notes (Day 2):Plant-like Protists
5/17 Thursday: Chapter 22 Notes (Day 3): Fungus-like Protists

5/21 Monday: Finish Protist Notes
5/22 Tuesday: Protist Review Guidebr>
5/23 Wednesday: BeginAnimal Kingdom Notes 1 (Sponges and Jellies) Cnidarian Notes
5/24 Thursday: Protist Quiz.Aniaml Notes 2 (Roundworms and Flatworms)

5/29 Tuesday: Animal Notes 3: Roundworms and Flatworms
5/30 Wednesday: Aniaml Notes 4: Molluscs
5/31 Thursday: Animal Notes 4: Segmented Worms and Animal Notes 6: Invertebrate Chordates
6/1 Friday: Sponge, Jelly, Flatworm and Roundwrorm Quiz Review Guide Chapter 29 Review Guide due Monday. Animal Notes 7: Intro to Vertebrates

6/4 Monday: Quiz today on sponges, jellies, and Worms. Review Guides due. Animal Notes 8: Fish Pass out Final Exam Review Guide 2012
6/5 Tuesday: Animal Notes 9: Amphibians
6/6 Wednesday: Aniaml Notes 10: ReptilesAnimal Notes 11: BirdsAnimal Notes 12: Mammals
6/7 Thursday: Work on Final Exam Review Guide
6/8 Friday: Work on Final Exam Review Guide Animal Notes on Arthropods

6/11 Monday: Short Answer Final Exam
6/12 Tuesday: Multiple Choice Final Exam. Final Exam Review Guide is due.
6/13 Wednesday: Frog Dissection
6/14 Thursday: Frog Dissection
6/15 Friday: Last Day of School. Enjoy your Summer!


This issue of AGE showcases a group of papers representing comparative or otherwise somewhat unconventional or alternative approaches and animal models for investigating basic aging processes. The inspiration for this special issue arose during the June 2007 meetings of the American Aging Association in San Antonio, Texas. Along with presentations by most of the contributors featured here, these meetings featured a debate on the evolution of aging between two respected authorities on very different aspects of aging: Daniel Promislow (comparative and evolutionary biology of aging) and Valter Longo (molecular biology of aging in the yeast Saccharomyces cerevisiae). Issues raised in this debate, as well as during a number of the other talks at this meeting, reflect the variety of ways in which biogerontologists representing different primary biological specialties frame hypotheses and develop research and experimental strategies for understanding organismal senescence.

Some of the key questions raised by this debate can be expressed as follows:

▪ How does an evolutionary or comparative approach contribute to our understanding of basic aging processes?

▪ How can we frame and test rigorous evolutionary hypotheses about organismal aging?

▪ Is aging “programmed” by natural selection?

▪ How can research on extremely long- or short-lived animal species contribute to our understanding of basic aging processes?

▪ Does aging occur differently in free-living, outbred organisms vs inbred laboratory animals maintained under controlled, disease-free conditions?

Historically, the biology of aging has benefited from a broad, interdisciplinary perspective. At its best, the aging research community encourages communication among scientists from a variety of intellectual backgrounds, and integrates state-of-the art approaches to understanding “ultimate” (evolutionary via comparative, and population-level studies), as well as “proximate” (molecular, biochemical, cellular or physiological) mechanisms responsible for organismal senescence, aging-related dysfunction and disease. Biogerontology currently represents a dynamic synthesis of diverse intellectual perspectives on aging patterns and mechanisms these include evolutionary theory, population biology and demography, comparative biology and bioenergetics, as well as developmental biology, molecular genetics and clinical biomedical sciences (see, for example, Finch 1990, 2007 Rose 1991 Kenyon et al. 1993 Kirkwood and Austad 2000 Tatar et al. 2003 Partridge et al. 2005 Speakman 2005a Austad and Masoro 2006).

At the same time, as a rule, biogerontologists currently employ a few indispensable, short-lived laboratory models: baker’s yeast (Saccharomyces cerevisiae), free-living nematodes (Caenorhabditis elegans), fruit flies (Drosophila melanogaster), and inbred laboratory mice (Mus musculus). For in vitro cellular studies, fibroblasts are the most commonly studied animal cell type, with most fibroblast studies using cells derived only from skin rather than a range of organs, and originating from humans or mice. There are now well developed molecular toolkits and transgenic technologies for these traditional models (Austad and Masoro 2006 Conn 2006). These standard model systems are characterized by conveniently short lifespans and highly genetically inbred (“isogenic”) lines of organisms maintained in immaculate, virtually disease- and parasite-free facilities. In the interest of rigorous experimental controls, animals in aging studies typically are maintained in a non-reproductive state, and are physically inactive, socially isolated, and exposed to as few natural stressors as possible (except, in the case of calorie restriction [CR] studies, energy stress).

In this special issue, we emphasize some powerful alternative aging research themes. The most prominent of these, the comparative approach, consists of a collection of inferential and statistical methods that now constitute mainstream practice for zoologists and evolutionary biologists, but remain much less familiar to many biogerontologists, despite a long-standing interest in comparing aging of diverse animal taxa (Harvey and Pagel 1991 Pagel 1992 Garland and Adolph 1994 Garland et al. 2005) (see also Furness and Speakman Hulbert Buffenstein et al. Gavrilova et al., this issue). In the broadest sense, this approach involves systematic comparison of aging-related phenomena among different strains, populations, species or other biologically meaningful groups. It is indispensable not only for testing hypotheses about the evolutionary processes giving rise to particular aging, developmental, and life history patterns, but is also very useful for identifying pertinent aging biomarkers, as well as putative cellular or molecular mechanisms for aging or its prevention. Just as experimental manipulations (e.g., CR) can provide a reliable way of investigating and intervening in the aging process, extremely short- or long-lived populations, mutants, or species can provide an invaluable window on the range of adaptations organisms have for promoting longevity, adaptive somatic maintenance and repair of molecular damage.

We also feature contributions from researchers examining aging processes in unconventional aging models𠅊nimal species or strains that are wild, exotic, outbred, or exceptionally long-lived for their taxa, body sizes or metabolic rates. These include wild mice (Ungvari et al.), naked mole-rats (Buffenstein et al.), monkeys (Sitzmann et al.), snakes (Bronikowksi), birds (Furness and Speakman) and bees (Remolina and Hughes). We also include several contributions from researchers that use non-traditional approaches—outbred laboratory mouse strains, along with wild-derived Mus musculus (Harper) and Peromyscus (Ungvari et al.), and studies of infectious disease CR (Kristan). As in the biology of aging as a whole, a common thread running through these contributions is a discussion of the free radical theory and oxidative damage hypotheses of aging (Harman 1956, 1972 Beckman and Ames 1998 Muller et al. 2007), which posit that aging processes are linked to ways in which animals produce, prevent, or repair oxidative damage to tissues, cells and molecules. Some researchers are now questioning whether this theory can adequately explain natural variation in organismal aging (see for example Buffenstein and Hulbert, this issue).

Much of what contributors to this issue have to say about aging-related phenomena in free-living, reproducing wild animals is clinically relevant to humans, and serves to emphasize how a comparative and evolutionary perspective can have important medical implications (Finch 2007 Stearns and Koella 2008). In this opening paper, we provide additional background and intellectual perspective on comparative and other alternative approaches and animal models for aging studies. In general, our aim in this special issue is to promote a wide range of “phenotypic variation” in the scientists who study aging, as well as in the research models they employ.

Outbreak of Cyclospora Infections Linked to Fresh Basil from Siga Logistics de RL de CV of Morelos, Mexico

This outbreak appears to be over. CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA) investigated a multistate outbreak of Cyclospora infections linked to fresh basil from Siga Logistics de RL de CV of Morelos, Mexico.

Take action if you have symptoms of a Cyclospora infection:

  • Talk to your healthcare provider.
  • Write down what you ate in the two weeks before you started to get sick.
  • Report your illness to the health department.
  • Assist public health investigators by answering questions about your illness.

Latest Outbreak Information

  • This outbreak appears to be over.
  • CDC, public health and regulatory officials in multiple states, and the U.S. Food and Drug Administration (FDA) investigated a multistate outbreak of Cyclospora cayetanensis infections.
  • As of September 27, 2019, 241 people with laboratory-confirmed Cyclospora infections and who reported eating fresh basil had been reported from 11 states exposures occurred in 5 states (Florida, Minnesota, New York, Ohio, and Wisconsin).
    • Illnesses started on dates ranging from June 10, 2019 to July 26, 2019.
    • Six people were hospitalized. No deaths attributed to Cyclospora were reported in this outbreak.
    • Reported laboratory-confirmed cases: 241
    • States: 11 exposures occurred in 5 states
    • Hospitalizations: 6
    • Deaths: 0
    • Recall: Yes external icon

    Investigation Details

    CDC, public health and regulatory officials in 11 states, and the U.S. Food and Drug Administration investigated a multistate outbreak of Cyclospora infections.

    As of September 27, 2019, a total of 241 people with laboratory-confirmed Cyclospora infections associated with this outbreak were reported from 11 states: CT (1), FL (62), GA (2), IA (2), MA (1), MN (33), NY (131), OH (3), RI (1), SC (1), and WI (4). Exposures were reported in 5 states (Florida, Minnesota, New York, Ohio, and Wisconsin).

    Illnesses started on dates ranging from June 10, 2019 to July 26, 2019. Ill people ranged in age from 15 to 98 years with a median age of 49 and 70% were female. Six (2%) people were hospitalized. No deaths attributed to Cyclospora were reported in this outbreak.

    Investigation of the Outbreak

    Epidemiologic evidence and product distribution information indicated that fresh basil exported by Siga Logistics de RL de CV of Morelos, Mexico, was a likely source of this outbreak.

    In interviews, ill people answered questions about the foods they ate and other exposures in the 2 weeks before they became ill. An illness cluster is defined as two or more people who do not live in the same household who report eating at the same restaurant location, attending a common event, or shopping at the same location of a grocery store in the week before becoming ill. Investigating illness clusters provides critical clues about the source of an outbreak. If several unrelated ill people ate or shopped at the same location of a restaurant or store within several days of each other, it suggests that the contaminated food item was served or sold there. In this fresh basil-associated cluster, there were several situations in which people reported eating at the same restaurants.

    The FDA and regulatory officials in several states collected records to determine the source of the fresh basil that ill people ate in the five affected states. Product distribution information indicated that the fresh basil that made people sick was exported by Siga Logistics de RL de CV of Morelos, Mexico.

    As of September 27, 2019, this outbreak appears to be over.

    Outbreak by the Numbers

    People infected with Cyclospora, and who reported eating basil by state of residence, as of September 27, 2019 (n=241). Data are preliminary and subject to change. Note that the Massachusetts and Connecticut case-patients were exposed in New York State the Iowa, Rhode Island, and two Wisconsin case-patients were exposed in Minnesota and the Georgia, South Carolina, one Wisconsin, and two Minnesota case-patients were exposed in Florida.

    *N=238. Data are current as of 9/27/19. Date of illness onset was not available for 3 cases.

    Onset Date Number of Cases
    6/10/2019 1
    6/11/2019 0
    6/12/2019 0
    6/13/2019 0
    6/14/2019 2
    6/15/2019 3
    6/16/2019 2
    6/17/2019 3
    6/18/2019 5
    6/19/2019 9
    6/20/2019 12
    6/21/2019 7
    6/22/2019 9
    6/23/2019 11
    6/24/2019 15
    6/25/2019 22
    6/26/2019 16
    6/27/2019 15
    6/28/2019 10
    6/29/2019 6
    6/30/2019 9
    7/1/2019 11
    7/2/2019 8
    7/3/2019 14
    7/4/2019 5
    7/5/2019 11
    7/6/2019 6
    7/7/2019 5
    7/8/2019 5
    7/9/2019 2
    7/10/2019 1
    7/11/2019 4
    7/12/2019 2
    7/13/2019 2
    7/14/2019 0
    7/15/2019 1
    7/16/2019 1
    7/17/2019 2
    7/18/2019 3
    7/19/2019 0
    7/20/2019 0
    7/21/2019 0
    7/22/2019 0
    7/23/2019 1
    7/24/2019 0
    7/25/2019 0
    7/26/2019 1
    7/27/2019 0
    7/28/2019 0
    7/29/2019 0
    7/30/2019 0
    7/31/2019 0
    8/1/2019 0
    8/2/2019 0
    8/3/2019 0
    8/4/2019 0
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    CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration are investigating a multistate outbreak of Cyclospora infections linked to consumption of fresh basil exported by Siga Logistics de RL de CV of Morelos, Mexico.

    As of August 15, 2019, a total of 205 people with laboratory-confirmed Cyclospora infections associated with this outbreak have been reported from 11 states: CT (1), FL (50), GA (2), IA (2), MA (1), MN (33), NY (107), OH (3), RI (1), SC (1), and WI (4). Exposures were reported in 5 states (Florida, Minnesota, New York, Ohio, and Wisconsin).

    Illnesses started on dates ranging from June 10, 2019 to July 18, 2019. Ill people ranged in age from 15 to 98 years with a median age of 51 and 70% were female. Five (2%) people have been hospitalized. No deaths attributed to Cyclospora have been reported.

    Illnesses might not yet be reported due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 4 to 6 weeks. Please see the Timeline for Reporting Cases of Cyclospora Infection for more details.

    There are typically multiple clusters of Cyclospora infections that occur during a given season. It is unknown at this time if other reported cases of Cyclospora infection in the United States this season are linked to fresh basil. This investigation is ongoing.

    Investigation of the Outbreak

    Epidemiologic evidence and early product distribution information indicate that fresh basil exported by Siga Logistics de RL de CV of Morelos, Mexico, is a likely source of this outbreak.

    In interviews, ill people answered questions about the foods they ate and other exposures in the week before they became ill. An illness cluster is defined as two or more people who do not live in the same household who report eating at the same restaurant location, attending a common event, or shopping at the same location of a grocery store in the week before becoming ill. Investigating illness clusters provides critical clues about the source of an outbreak. If several unrelated ill people ate or shopped at the same location of a restaurant or store within several days of each other, it suggests that the contaminated food item was served or sold there. In this fresh basil-associated cluster, there were several situations in which people reported eating at the same restaurants.

    The FDA and regulatory officials in several states are collecting records to determine the source of the fresh basil that ill people ate in the five affected states. Product distribution information available at this time indicates that the fresh basil that made people sick was exported by Siga Logistics de RL de CV of Morelos, Mexico. This traceback investigation is ongoing to determine the source of contamination. Additional illness clusters are currently under investigation to determine if they are linked to fresh basil exported by Siga Logistics de RL de CV of Morelos, Mexico.

    Consumers should not eat fresh basil exported by Siga Logistics de RL de CV of Morelos, Mexico, until we learn more about this outbreak. This investigation is ongoing, and CDC will provide updates when more information is available.

    Outbreak by the Numbers

    People infected with Cyclospora, and who reported eating basil by state of residence, as of August 15, 2019 (n=205). Data are preliminary and subject to change. Note that the Massachusetts and Connecticut case-patients were exposed in New York State the Iowa, Rhode Island, and two Wisconsin case-patients were exposed in Minnesota and the Georgia, South Carolina, one Wisconsin and two Minnesota case-patients were exposed in Florida.

    *N=202. Data are current as of 8/15/19. Date of illness onset was not available for 3 cases. Data are preliminary and subject to change. Illnesses that started after 7/4/2019 might not yet be reported due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 4 to 6 weeks


    Front End Innovation, Beiersdorf AG, Hamburg, Germany

    Nicholas Holzscheck, Cassandra Falckenhayn, Jörn Söhle, Boris Kristof, Ralf Siegner, Horst Wenck, Marc Winnefeld & Elke Grönniger

    Institute for Bioinformatics, University Medicine Greifswald, Greifswald, Germany

    Nicholas Holzscheck & Lars Kaderali

    Institute for Community Medicine, University Medicine Greifswald, Greifswald, Germany

    André Werner, Janka Schössow, Clemens Jürgens & Henry Völzke

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    L.K. conceived the original idea for the presented work. M.W. and H.W. provided funding for the experiments. B.K. planned and organized the skin sample collection with assistance of R.S., in close coordination with the SHIP study team. A.W., J.S., C.J., and H.V. coordinated and conducted the examinations and handled the data management. J.S. performed all wet lab work. N.H. designed and implemented the model and performed all computational work. N.H. wrote the manuscript with input of C.F., E.G., and L.K. All authors read and discussed the manuscript.

    Corresponding authors

    Phylum Rotifera

    Evolutionary Relationships

    The phylogenetic position of rotifers is still an open question. The current view suggests that rotifers are somehow related to the phylum Platyhelminthes, having been derived either from an ancestral flatworm or as a sister group to the flatworms. Another issue regarding the evolution of the Rotifera is the question of its relationship to the parasitic phylum Acanthocephala . The presence of the intracytoplasmic lamina (ICL) within a syncytial epidermis in both taxa, along with similarities in the ultrastructure of their spermatozoa, suggests that acanthocephalans and rotifers are closely related, even though acanthocephalans are 5–1500 times larger than the largest rotifer. Furthermore, detailed molecular analysis aligns acanthocephalans firmly with the rotifers, but exactly how they are related remains in doubt. Thus, some researchers argue that similarities in structure along with molecular evidence indicate that these two taxa are sufficiently related to be recognized as forming their own clade, the Syndermata ( Sørensen and Giribet, 2006 ). Within this clade, several possible permutations of rotifer phylogeny have been postulated, including the following: acanthocephalans are: (1) highly modified bdelloids (2) related to the group bdelloids + monogononts (3) related to the group seisonids + bdelloids or (4) a sister group to all rotifers.

    Nonetheless, for the present, taxonomists in both fields have retained the names Acanthocephala and Rotifera, ignoring the question of their phylogeny. Ultimately, integrative studies using total evidence (morphological and molecular data) should help to resolve issues of phylogenetic affinity. This goal is made more feasible perhaps by studies of the transcriptome of Brachionus plicatilis Müller, 1786 and discovery that the mitochondrial genome of this species is composed of two circular chromosomes of unequal copy number. Indeed, much remains to be accomplished, including a detailed analysis of a proposal to group a suite of small, jawed taxa—Gnathostomulida, Micrognathozoa, and Acanthocephala + Rotifera—into a superphylum Gnathifera (G., gnath, jaw and L., fera, bearing). Of course, to determine the phylogenetic relationships among these taxa, more molecular and morphological data, as well as a better sampling of taxa will be necessary.

    Evolution of bdelloids offers its own problems, but research has supplied some exciting new insights into these remarkable animals. Chief among the issues in bdelloid evolution are the following: How did asexuality arise in this group how did their ability to become anhydrobiotic appear and how are deleterious mutations eliminated from the population? Answers to these questions probably lie in the fact that bdelloids have undergone genome duplication, with the resulting gene copies evolving independent functions (i.e., they are degenerate tetraploids), as well as horizontal gene transfer, which has resulted in the acquisition of a diverse array of genes from viruses, bacteria, and other Metazoa ( Ramulu et al., 2012 ). Current thinking on the evolution of the bdelloids and monogononts is that these two groups separated at least 100 million years ago.

    Animal Diversity Web

    The range of African elephants ( Loxodonta africana ) is patchily distributed across central and southern Africa in the Ethiopian Region. Remnant populations exist as far northwest as Guinea-Bissau and as far northeast as Ethiopia. Disjunct populations exist southward into northern South Africa, and include contiguous populations in Gabon, Tanzania, Botswana, and Zambia. Once present in Burundi, Gambia, and Mauritania, they've now been extirpated from those countries. These elephants were extirpated from Swaziland, as well, but have been re-introduced here in recent years. (Blanc, 2008 Laursen and Bekoff, 1978 Thomas, et al., 2008)


    African elephants are found in many habitats of Africa such as savannas, rain forests, woodlands, scrub forests, occasionally deserts, and beaches. However, due to poaching threats protected sanctuaries are their main habitats. Within these sanctuaries, these elephants will inhabit areas that have sources of water and abundant vegetation for foraging. Across these habitats, the elevation level ranges from sea level (0 meters) to 4000 meters. (Duffy, et al., 2011 Harris, et al., 2008 Laursen and Bekoff, 1978 Mashintonio, et al., 2014)

    • Habitat Regions
    • tropical
    • terrestrial
    • Terrestrial Biomes
    • desert or dune
    • savanna or grassland
    • rainforest
    • scrub forest
    • Range elevation 0 to 4000 m 0.00 to 13123.36 ft

    Physical Description

    Currently, African elephants are the largest terrestrial organism. Female elephants can range from 2,000 to 3,500kg in mass and stand 2.2 to 2.6m at shoulder height. Male elephants are larger, ranging from 4,500 to 6,100kg in mass and standing 3.2 to 4m at shoulder height. Distinguishing characteristics between the sexes include head shape, width of forehead, saddle-back vs straight back, and tusk size. Males are broader with a curvy build. Both sexes have two thick, ivory tusks which are curved and can reach up to 350 cm in length. African elephants have muscular trunks that are able to grab objects and can be used for breathing purposes. They can grab objects due to the unique shape at the end of the trunk. Their sizable ears are triangular and can help keep them cool in the hot, summer months.

    African elephants have creased, gray skin covered with papillae. The thick (up to 30 mm), immobile skin covers the majority of the body, while bumpy skin covers areas that require a lot of movement. Smooth skin can be found on delicate areas of the body. Hair that varies in color, length, and thickness can be found along the body. Hair that grows along the back and tail is flattened dark hair that can grow to 0.80 m in length. Hair around the eyes is long in order to prevent foreign objects from entering the eyes. Calves have different hair coloring and texture. Their hair is softer with a lighter tone such as a red or brown.

    The dental formula for African elephants is i 1/0, c 0/0, p 3/3, m 3/3. At birth, calves do not have tusks but instead have temporary premaxillary incisors. These incisors are replaced at about a year of age with incisors that will ultimately form the tusks. Adult African elephants have lophodont dentition, with 6 molars that grow and move forward, like on a conveyor belt. They are worn down, lost, and replaced throughout their lives. Once the sixth set of molars is worn down, there are no additional teeth to replace them and the elephant is not able to process forage. (Laursen and Bekoff, 1978 Nowak, 1999)

    • Other Physical Features
    • endothermic
    • homoiothermic
    • bilateral symmetry
    • Sexual Dimorphism
    • male larger
    • ornamentation
    • Range mass 2000 to 6100 kg 4405.29 to 13436.12 lb
    • Range length 2.2 to 4 m 7.22 to 13.12 ft


    The estrus state is how bulls know if cows are ready to mate. This is done by a scent in female urine and genital area. During the courtship process, bulls approach females and attempts to use their trunk to stroke her. Bulls will put up a fight in order to mate, by chasing the females if they retreat. When females stop retreating, they will join the bulls in stroking each other with their trunks. The courtship continues by females surrendering their hindquarters to the males. Bulls then mount the females to begin mating. The males will thrust repeatedly into the females for up to 2 mins. While females are in an estrus state, they may mate with several different bulls, and are considered polygynandrous. They are cooperative breeders, in which females have help raising young by other members of the family or "clan." (Laursen and Bekoff, 1978 Poole, et al., 2007)

    African elephants are viviparous animals, meaning that they birth their young live. They breed year-round with no seasonal differences. The number of offspring is usually limited to one for each birthing period but in rare cases, twins may be born. They breed once every 3-9 years, and will give birth to an average of four calves in their lifetime. The gestation period is about 22 months but is strongly influenced by environmental factors. The gestation period may be shorter if the environmental factors are favorable for newborns survival. Newborn African elephants will weigh between 90-120 kg, with 100 kg being the average birth weight. Offspring are completely dependent on their mother's milk until they are weaned at four months, but continue to occasionally drink their mother's milk for up to three years. Young African elephants will gain their full independence around eight years of age. Sexual maturity occurs at different ages for males and females. Males will reach sexual maturity around 20 years of age, while females will reach sexual maturity around 11 years of age. (Hildebrandt, et al., 2006 Laursen and Bekoff, 1978 Poole, et al., 2007)

    • Key Reproductive Features
    • iteroparous
    • year-round breeding
    • gonochoric/gonochoristic/dioecious (sexes separate)
    • sexual
    • fertilization
    • viviparous
    • Breeding interval African elephants breed once every 3-9 years
    • Breeding season African elephants breed throughout the year
    • Range number of offspring 1 to 2
    • Average number of offspring 1
    • Average number of offspring 1 AnAge
    • Average gestation period 22 months
    • Average gestation period 670 days AnAge
    • Average weaning age 4 months
    • Average time to independence 8 years
    • Average age at sexual or reproductive maturity (female) 11 years
    • Average age at sexual or reproductive maturity (female)
      Sex: female 4018 days AnAge
    • Average age at sexual or reproductive maturity (male) 20 years
    • Average age at sexual or reproductive maturity (male)
      Sex: male 3650 days AnAge

    In African elephant herds, primarily the mother and other females assist in taking care of the young. When female elephants give birth, they will move away from the herd in order to allow space for the offspring. When they return, all members of the herd will inspect the new elephant thoroughly. Until young elephants are around 4 years of age, they will closely follow their mother. During this time, mothers will feed their young through breast milk and help them move around obstacles. Until young offspring are independent, around 8 years of age, they will depend on the rest of the herd to teach them how to use their trunks, forage for food, and move around tough obstacles. Maternal position only affects the young if the mother is the leader of the herd, in which case, the young will be the next leader of the herd. (Laursen and Bekoff, 1978 Miller and Andrews, 2013)

    • Parental Investment
    • female parental care
    • pre-hatching/birth
      • provisioning
        • female
        • provisioning
          • female
          • female
          • provisioning
            • female
            • female


            African elephants reportedly have been known to live up to a maximum of 65 years in captivity. However, unpublished reports have stated that African elephants may live up to 80 years in captivity. In the wild, African elephants live for an average of 60-70 years. (Carey and Judge, 2000 Nowak, 1999 Weigl, 2005 Wiese and Willis, 2004)

            • Range lifespan
              Status: captivity 65 (high) years
            • Average lifespan
              Status: wild 60-70 years
            • Average lifespan
              Status: wild 60.0 years Max Planck Institute for Demographic Research
            • Average lifespan
              Status: captivity 80.0 years Max Planck Institute for Demographic Research
            • Average lifespan
              Status: wild 70.0 years Max Planck Institute for Demographic Research


            African elephants generally are slow moving creatures. Their regular pace is 6 km/hour but, they can reach speeds of up to 24 km/hour when running. How much they travel each day depends on the amount of resources in close proximity that they require the average walking distance for African elephants is around 10 km a day. Before African elephant populations were constricted to large reservations for protection, they migrated hundreds of kilometers seasonally, from high to low altitudes and vice versa.

            African elephants are active animals for the majority of time in a 24-hour period, due to the amount of food they must consume each day. They are dormant in the early morning hours with an additional sleep midday for a total of 4 hours of sleep every day. During this time they scavenge for food and groom themselves. Grooming consist of African elephants using their trunks to cover themselves with mud or water, and the process helps them maintain hydration.

            Female African elephants are social animals that live in herds of 6 to 70 members. These herds have a matriarchal order, and consist of females (cows) and their young. The alpha elephant in these herds tends to be the biggest and most dominant. Male African elephants (bulls) tend to only live within a herd if they are not old enough to go out on their own or for mating purposes. Bulls will live a life in solitary or with a few other bulls. (Greco, et al., 2016 Laursen and Bekoff, 1978 Lee and Moss, 2012 Miller, et al., 2016 Thouless, 1996)

            • Key Behaviors
            • terricolous
            • diurnal
            • nocturnal
            • motile
            • nomadic
            • social
            • colonial
            • dominance hierarchies

            Home Range

            If enough essential resources are present African elephants will move as little as 1.5 Km a day. When resources are scarce, African elephants may travel as much as 40 km a day. Thouless (1996) reported that African elephants' home range can vary from 102 to 5527 km within a period of 25 months. (Miller, et al., 2016)

            Communication and Perception

            African elephants communicate acoustically with others of their species. Many of their calls are low frequency calls of ca. 20Hz. They can make a variety of calls including rumble, trumpet, snort, roar, bark, and grunt. Soltis (2010) reports 3 other calls made by these elephants. They include "rev, croak, and chuff." A trumpet, roar, or growl could show signs of aggression. A "soft chirp" shows submission or intimidation. Infant elephants will gurgle during play and squeal when frightened. The African elephants can hear one of these calls from over 2km away. They will make these calls to warn or gather others in their herd or to signal they are ready to mate. African elephants watch and listen to their surrounding environment for signs of something amiss. They communicate visually by using their trunks or ears to signal other herd members. Tactile communication is between a mother and her child or two elephants trying to mate. Forms of chemical communication along with scent marking among African elephants is done by males who are mating with the females in a clan. Around the clan the males will mark trees or bushes with their tusks or by secreting a substance onto the bush. (Laursen and Bekoff, 1978 O’Connell-Rodwell, et al., 2006 Soltis, 2010)

            • Communication Channels
            • visual
            • acoustic
            • chemical
            • Other Communication Modes
            • scent marks
            • Perception Channels
            • visual
            • tactile
            • acoustic
            • chemical

            Food Habits

            African elephants have a herbivorous diet consisting of tree foliage, fruits, herbs, grasses, and wood including roots, twigs, and bark. Their source of fiber comes from chewing on bark but not digesting the bark itself. In order to obtain bark or roots, African elephants will overturn a tree to for easier access. Using their trunks as a temporary container or holding, African elephants use their trunks to gather water and shoot it into their mouths. African elephants will feed continuously throughout the day, eating opportunistically. They must consume around 50 gallons of water everyday in order to stay hydrated.

            African elephants are both browsers and grazers. Depending on the season and location, herds may depend more on one or the other feeding technique. Typically during the wet seasons, African elephants are more particular about they consume. During this season, they are more likely to forage on grasses. However, during the dry seasons when food is less abundant, they will be more flexible with what they consume. During both seasons, African elephants tend to pick food sources that are high in nutritional content. (Archie, et al., 2006 Chafota and Owen-Smith, 2012 Codron, et al., 2006 Codron, et al., 2013 Laursen and Bekoff, 1978)

            • Primary Diet
            • herbivore
              • folivore
              • frugivore
              • lignivore
              • Plant Foods
              • leaves
              • roots and tubers
              • wood, bark, or stems
              • fruit


              Due to their size, African elephants are not easy prey for many predators. While lions (Panthera leo), wild dogs (Lycaon pictus), hyenas (Crocuta crocuta), and Nile crocodiles ( Crocodilus niloticus ) are predators of African elephants, the majority of these predators prey on the young elephants that lag behind the rest of their group. These predators will attempt to hunt elephants at night, due to the safety level decreasing because the herd cannot see well at night. However, these predators are not the problem for the African elephant population. Humans (Homo sapiens) hunt these creatures for their ivory tusks and leathery skin. (Joubert, 2006 Laursen and Bekoff, 1978)

              • Known Predators
                • lions (Panthera leo)
                • wild dogs (Lycaon pictus)
                • hyenas (Crocuta crocuta)
                • Nile crocodiles ( Crocodilus niloticus )
                • humans (Homo sapiens)

                Ecosystem Roles

                African elephants are thought to be a keystone species, because in small numbers, they have lasting impacts. They often are labelled as bioengineers. For example, their destruction or altering of trees positively influences herpetofaunal diversity, as they create more three-dimensional habitat diversity for these herps.

                There are many parasitic species that use African elephants as their host. There is a wide variety to the kind of parasites that infect African elephants such as flukes ( Protofasciola robusta ), ticks, blood sucking flies ( Anthomyidae ), roundworms ( Strongyloides papillosus , Haemonchus contortus, Trichostrongylus colubriformis , Murshidia , Oesophagostomum columbianum ), lice, botflies (Pharyngobolus africanus, Platycobboldia loxodontis , Rodhainomyia roverei , Ruttenia loxodontis, Neocuterebra squamosa>>), warble flies (Hypoderma), protozoan parasites ( Babesia , Eimeria bovis ), and hookworms (Ancylostoma duodenale). African elephants do have a mutualistic relationship with birds, as the birds will feed on the skin parasites of the elephants, providing them a meal while ridding the elephants of some parasites.

                White egrets Bubulcus ibis may have a mutualistic rlationship with African elephants. These species often are seen together, with the egret below or atop the elephant. The presumption is that the birds are feeding on parasites. (Baines, et al., 2015 Laursen and Bekoff, 1978 McLean, et al., 2012 Nasseri, et al., 2011 Zumpt and Wetzel, 1970)

                • warble flies (Hypoderma)
                • blood sucking flies ( Anthomyidae )
                • roundworms ( Murshidia )
                • roundworms ( Oesophagostomum columbianum )
                • roundworms ( Strongyloides papillosus )
                • roundworms (Haemonchus contortus)
                • roundworms ( Trichostrongylus colubriformis )
                • flukes ( Protofasciola robusta )
                • botflies (Pharyngobolus africanus)
                • botflies ( Platycobboldia loxodontis )
                • botflies ( Rodhainomyia roverei )
                • botflies (Ruttenia loxodontis)
                • botflies (Neocuterebra squamosa)
                • protozoan parasites ( Eimeria bovis )
                • protozoan parasites ( Babesia )
                • lice (Siphonaptera)
                • ticks ( Acari )

                Economic Importance for Humans: Positive

                African elephants are used for a variety of reasons that benefit humans, often involving the killing of these elephants. African elephants can simply be used as large sport hunting for trophies or they can be hunted for their tusks, ears, feet, and meat. Because their tusks are made of ivory, they have been used for numerous reasons such as billiard balls, dice, piano keys, and most commonly, decorative carvings. Ivory can be sold for a high price, allowing someone to live off the price of a few pounds. Their large ears are converted into leather to make purses. Their feet can be preserved and made into furniture. However, given the conservation status of African elephants, these uses of elephant parts are difficult to justify. (Laursen and Bekoff, 1978 Wittemyer, 2011 Gao and Clark, 2014 Laursen and Bekoff, 1978 Wittemyer, 2011)

                Economic Importance for Humans: Negative

                African elephants do not have many negative economic impacts on humans. African elephants destroy vegetation by using it as a food source or by knocking it down due to their massive size. If elephants are raiding crops for food and people come to stop them, the elephants might chase down the people and kill them. (Gadd, 2005 Laursen and Bekoff, 1978 Thomas, et al., 2008)

                Conservation Status

                According to the IUCN Red List, African elephants are listed as a "Vulnerable" species. CITES appendices list African elephants in both Appendix I and Appendix II. African elephants in Botswana, Namibia, South Africa, and Zimbabwe are listed in Appendix II, while African elephants in other countries are listed in Appendix I. Appendix I means the species is in danger of extinction. This Appendix protects the species by making international trade illegal when dealing with African elephants. Appendix II states that the species is not endangered, but could become so if poaching is not regulated. The US Federal List have listed African elephants as a "Threatened" species.

                The reason some elephant populations are in decline in certain countries is because hunting is legal in these countries. However, illegal poaching that is not prosecuted has the same negative impact. Elephants are sold and bought legally or illegally for their hides, fur, tusks, and meat. Despite an international ban on the sale of ivory since 1989, trade in illegal ivory doubled from 2007-2014. Organized crime combined with corrupt government officials makes it increasingly difficult to punish offenders.

                Another reason for the decline of African elephants is that they are losing their habitats due to human development and expansion.

                In order to combat further decline of African elephants, some populations have been moved to protected areas to prevent poaching. However, about 70% of the current range is unprotected lands. So, threats are on-going. Some management efforts have been successful at increasing local populations, so much so that contraception or trap-and-relocate programs had to be implemented to sustain the habitat. Another hardship is that herds are treated differently across political boundaries - the legality of hunting, the locals' attitudes towards elephants, and the permissability of or non-action to combat illegal poaching all affect the populations. Larger-scale conservation plans that cross country boundaries may address some of these issues. (Bennett, 2015 Blanc, 2008 Laursen and Bekoff, 1978)

                • IUCN Red List Vulnerable
                  More information
                • IUCN Red List Vulnerable
                  More information
                • US Federal ListThreatened
                • CITES Appendix I Appendix II
                • State of Michigan List No special status


                Meghan Howard (author), Radford University, Karen Powers (editor), Radford University, Alex Atwood (editor), Radford University, Marisa Dameron (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.


                living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

                uses sound to communicate

                having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

                uses smells or other chemicals to communicate

                used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

                helpers provide assistance in raising young that are not their own

                in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

                ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

                animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor the fossil record does not distinguish these possibilities. Convergent in birds.

                parental care is carried out by females

                union of egg and spermatozoan

                an animal that mainly eats leaves.

                A substance that provides both nutrients and energy to a living thing.

                an animal that mainly eats fruit

                An animal that eats mainly plants or parts of plants.

                offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

                a species whose presence or absence strongly affects populations of other species in that area such that the extirpation of the keystone species in an area will result in the ultimate extirpation of many more species in that area (Example: sea otter).

                having the capacity to move from one place to another.

                the area in which the animal is naturally found, the region in which it is endemic.

                generally wanders from place to place, usually within a well-defined range.

                the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

                rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

                communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

                scrub forests develop in areas that experience dry seasons.

                reproduction that includes combining the genetic contribution of two individuals, a male and a female

                one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.

                associates with others of its species forms social groups.

                uses touch to communicate

                The term is used in the 1994 IUCN Red List of Threatened Animals to refer collectively to species categorized as Endangered (E), Vulnerable (V), Rare (R), Indeterminate (I), or Insufficiently Known (K) and in the 1996 IUCN Red List of Threatened Animals to refer collectively to species categorized as Critically Endangered (CR), Endangered (EN), or Vulnerable (VU).

                the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

                A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

                A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

                A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

                uses sight to communicate

                reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

                breeding takes place throughout the year


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                The c-Jun N-terminal kinases consist of ten isoforms derived from three genes: JNK1 (four isoforms), JNK2 (four isoforms) and JNK3 (two isoforms). [2] Each gene is expressed as either 46 kDa or 55 kDa protein kinases, depending upon how the 3' coding region of the corresponding mRNA is processed. There have been no functional differences documented between the 46 kDa and the 55 kDa isoform, however, a second form of alternative splicing occurs within transcripts of JNK1 and JNK2, yielding JNK1-α, JNK2-α and JNK1-β and JNK2-β. Differences in interactions with protein substrates arise because of the mutually exclusive utilization of two exons within the kinase domain. [1]

                c-Jun N-terminal kinase isoforms have the following tissue distribution:

                  and JNK2 are found in all cells and tissues. [3] is found mainly in the brain, but is also found in the heart and the testes. [3]

                Inflammatory signals, changes in levels of reactive oxygen species, ultraviolet radiation, protein synthesis inhibitors, and a variety of stress stimuli can activate JNK. One way this activation may occur is through disruption of the conformation of sensitive protein phosphatase enzymes specific phosphatases normally inhibit the activity of JNK itself and the activity of proteins linked to JNK activation. [4]

                JNKs can associate with scaffold proteins JNK interacting proteins (JIP) as well as their upstream kinases JNKK1 and JNKK2 following their activation.

                JNK, by phosphorylation, modifies the activity of numerous proteins that reside at the mitochondria or act in the nucleus. Downstream molecules that are activated by JNK include c-Jun, ATF2, ELK1, SMAD4, p53 and HSF1. The downstream molecules that are inhibited by JNK activation include NFAT4, NFATC1 and STAT3. By activating and inhibiting other small molecules in this way, JNK activity regulates several important cellular functions including cell growth, differentiation, survival and apoptosis.

                JNK1 is involved in apoptosis, neurodegeneration, cell differentiation and proliferation, inflammatory conditions and cytokine production mediated by AP-1 (activation protein 1) such as RANTES, IL-8 and GM-CSF. [5]

                Recently, JNK1 has been found to regulate Jun protein turnover by phosphorylation and activation of the ubiquitin ligase Itch.

                Neurotrophin binding to p75NTR activates a JNK signaling pathway causing apoptosis of developing neurons. JNK, through a series of intermediates, activates p53 and p53 activates Bax which initiates apoptosis. TrkA can prevent p75NTR-mediated JNK pathway apoptosis. [6] JNK can directly phosphorylate Bim-EL, a splicing isoform of Bcl-2 interacting mediator of cell death (Bim), which activates Bim-EL apoptotic activity. JNK activation is required for apoptosis but c-jun, a protein involved in the JNK pathway, is not always required. [7]

                The packaging of eukaryotic DNA into chromatin presents a barrier to all DNA-based processes that require recruitment of enzymes to their sites of action. To allow repair of double-strand breaks in DNA, the chromatin must be remodeled. [8] Chromatin relaxation occurs rapidly at the site of a DNA damage. [9] In one of the earliest steps, JNK phosphorylates SIRT6 on serine 10 in response to double-strand breaks (DSBs) or other DNA damage, and this step is required for efficient repair of DSBs. [10] Phosphorylation of SIRT6 on S10 facilitates the mobilization of SIRT6 to DNA damage sites, where SIRT6 then recruits and mono-phosphorylates poly (ADP-ribose) polymerase 1 (PARP1) at DNA break sites. [10] Half maximum accumulation of PARP1 occurs within 1.6 seconds after the damage occurs. [11] The chromatin remodeler Alc1 quickly attaches to the product of PARP1 action, a poly-ADP ribose chain, [9] allowing half of the maximum chromatin relaxation, presumably due to action of Alc1, by 10 seconds. [9] This allows recruitment of the DNA repair enzyme MRE11, to initiate DNA repair, within 13 seconds. [11]

                Removal of UV-induced DNA photoproducts, during transcription coupled nucleotide excision repair (TC-NER), depends on JNK phosphorylation of DGCR8 on serine 153. [12] While DGCR8 is usually known to function in microRNA biogenesis, the microRNA-generating activity of DGCR8 is not required for DGCR8-dependent removal of UV-induced photoproducts. [12] Nucleotide excision repair is also needed for repair of oxidative DNA damage due to hydrogen peroxide ( H2O2 ), and DGCR8 depleted cells are sensitive to H2O2 . [12]

                In Drosophila, flies with mutations that augment JNK signaling accumulate less oxidative damage and live dramatically longer than wild-type flies. [13] [14]

                In the tiny roundworm Caenorhabditis elegans, loss-of-function mutants of JNK-1 have a decreased life span, while amplified expression of wild-type JNK-1 extends life span by 40%. [15] Worms with overexpressed JNK-1 also have significantly increased resistance to oxidative stress and other stresses. [15]

                Watch the video: Phylum Nematoda Part 1 Notes (September 2022).


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