Information

What is this unusual structure inside this banana?


I was eating a banana, and I found this strange biological structure inside of it.

It was a bit tougher than the banana, and ran inside of the body through most of the length. To be clear, I peeled back banana with my fingers to reveal it; it was enveloped inside. It was accompanied by a small void.

No idea what this is, never seen anything like it. It didn't taste good. I'm thinking it might be a mutation. Anyone know what this is?


It looks like some species of Nigrospora genus took over the inside of that banana. According to Wikipedia, N. sphaerica was first isolated from bananas. The other species that you will find referenced online is N. oryzae. In the articles I cite below the colonies are grown in potato dextrose, though.

Here is a picture of the red fungus inside a banana (from the Canadian Food Inspection Agency):

Googling 'Nigrosporia banana' also returns lots of similar pictures.

To get a better answer, a sample could be taken from the banana and then cross-check what you see under the microscope with the oryzae morphology images seen in the researchgate article.


A phospholipid is made up of two fatty acid tails and a phosphate group head. Fatty acids are long chains that are mostly made up of hydrogen and carbon, while phosphate groups consist of a phosphorus molecule with four oxygen molecules attached. These two components of the phospholipid are connected via a third molecule, glycerol.

Phospholipids are able to form cell membranes because the phosphate group head is hydrophilic (water-loving) while the fatty acid tails are hydrophobic (water-hating). They automatically arrange themselves in a certain pattern in water because of these properties, and form cell membranes. To form membranes, phospholipids line up next to each other with their heads on the outside of the cell and their tails on the inside. A second layer of phospholipids also forms with heads facing the inside of the cell and tails facing away. In this way, a double layer is formed with phosphate group heads on the outside, and fatty acid tails on the inside. This double layer, called a lipid bilayer, forms the main part of the cell membrane. The nuclear envelope, a membrane surrounding a cell’s nucleus, is also made up of phospholipids arranged in a lipid bilayer, as is the membrane of mitochondria, the part of the cell that produces energy.

This figure depicts the lipid bilayer and the structure of a phospholipid:


Find the DNA in a Banana

Introduction
What do you have in common with a banana? Even though we might not look alike, all living things&mdashbananas and people included&mdashare made up of the same basic material.

Just like houses are made up of smaller units such as bricks, all living things are made up trillions of microscopic building blocks called cells. Within an organism, each cell contains a complete set of "blueprints". These directions determine the organism's characteristics.

Background
If we could zoom in on a single, tiny cell, we could see an even teenier "container" inside called a nucleus. It holds a stringy substance called DNA, which is like a set of blueprints, or instructions. DNA contains a code for how to build a life-form and put together the features that make that organism unique. Segments, or pieces, of DNA are called "genes". In living things, such as us, each gene determines something about our bodies&mdasha trait. In our DNA there are genes that are responsible for hair color, eye color, earlobe shape and so on. We get our DNA from our parents. Some characteristics, like eye color, are pretty much entirely determined by DNA. Some are determined both by DNA and by your environment as you grow up, like how tall you will be as an adult. And some traits are not very directly tied to DNA at all, like the kind of books you like to read.

Just like us, banana plants have genes and DNA in their cells, and just like us, their DNA determines their traits. Using only our eyes, we couldn't see a single cell or the DNA inside of it. If we remove DNA from millions of cells, however, we will be able to view it without a microscope. That is what we will do today!

Materials
&bull Ripe banana
&bull Half cup of water
&bull Teaspoon of salt
&bull Resealable zip-top bag
&bull Dishwashing soap or detergent
&bull Rubbing alcohol
&bull Coffee filter
&bull Narrow glass
&bull Narrow wooden stirrer

Preparation
&bull Place your bottle of rubbing alcohol into the refrigerator or freezer and let it chill for the duration of this experiment.
&bull Peel a banana.
&bull Put the peeled banana in a resealable zip-top bag and close the bag.
&bull On a hard surface like a tabletop or kitchen counter, mush the banana in the bag for about a minute until it has a fine, puddinglike consistency and until all lumps are gone. Do not slap the bag or mash the banana too close to the bag's zip seal. (This could cause the seal to open and the banana to squirt out and make a mess.)

Procedure
&bull Fill a measuring cup with a half cup of hot water and a teaspoon of salt.
&bull Pour this saltwater into the bag, and close the bag. Gently mix and slosh the saltwater and mashed banana together for 30 to 45 seconds.
&bull Add a half of a teaspoon of dishwashing detergent or dish soap into the bag. Again, mix around the contents gently. You do not want the mixture to become too foamy.
&bull Place the bottom half of a coffee filter in a clear glass cup. The top part of the filter should be folded over the rim of the glass to keep it in place.
&bull Carefully pour the contents of the bag into the filter and let it sit for several minutes until all of the liquid has dripped down into the cup. (You can now throw out the coffee filter and its contents.)
&bull Take the rubbing alcohol from the refrigerator. Tilt the glass and slowly pour the alcohol down the side of the cup until there is a layer that is 2.5 to five centimeters (one to two inches) thick. You want to keep the alcohol and the liquefied banana as separate as possible, so complete this step slowly.
&bull Let this two-layered mixture sit for eight minutes. During this time, what do you see happening between the alcohol and the banana liquid layer? It looks cloudy and may have some tiny bubbles in it. The longer you wait, the more defined this layer becomes. This is the DNA pieces clumping together.
&bull Stick the wooden stirrer into the cup. Spin it in place so that cloudy layer spools around it. Remove the stirrer. Can you capture some of the stringy middle layer on your stirrer and remove it from the cup? The substance that you see on the stirrer is DNA!

Read on for observations, results and more resources.

Observations and results
The stringy substance that you see is DNA! It has been removed from the millions and millions of cells that make up the banana. All living things have DNA. The more similar and closely related two living things are, the more similar their DNA is. Every human shares 99 percent of his or her DNA with every other person. Furthermore, human DNA is very similar to that of other species. We share most of our genes, which make up DNA, with fellow primates such as chimpanzees and with other mammals such as mice. We even have genes in common with the banana plant!

In this activity each material plays a specific role in helping to extract the DNA from the cells. For instance, the detergent or soap helps to break down the cell's outer membrane, and the salt helps to separate the DNA from other materials in the cell. And because the DNA doesn't dissolve in alcohol, this substance helps the DNA clump together in a separate layer.

Share your banana DNA observations and results! Leave a comment below or share your photos and feedback on Scientific American's Facebook page.

Cleanup
You can wash the bag and reuse it. Pour the banana liquid and alcohol down the drain and wash out the cup.

More to explore
"Can Science Save the Banana?" from Scientific American
"Bar Code of Life: DNA tags help classify animals" from Scientific American
DNA model activity from CSIRO's Double Helix Science Club
DNA Interactive site from Cold Spring Harbor Laboratory
My First Book about DNA by Katie Woodard, ages 9&ndash12
Have a Nice DNA by Frances R. Balkwill, ages 9&ndash12

Up next&hellip
For the Birds: Best-Adapted Beaks

What you'll need
&bull Tweezers
&bull Cotton swab
&bull Binder clip
&bull Several different kinds of seeds, grains or nuts that differ in size and shape. It is best if you have a wide range: some that are tiny (for instance, grass seeds or couscous), some that are medium-sized (black-eyed peas or lentils), and some that are larger (almonds, cashews, walnuts or hazelnuts).
&bull Timer with a second hand or clock
&bull Dish
&bull Paper
&bull Pen or pencil


Contents

The discovery of plant viruses causing disease is often accredited to A. Mayer (1886) working in the Netherlands demonstrated that the sap of mosaic obtained from tobacco leaves developed mosaic symptom when injected in healthy plants. However the infection of the sap was destroyed when it was boiled. He thought that the causal agent was the bacteria. However, after larger inoculation with a large number of bacteria, he failed to develop a mosaic symptom.

In 1898, Martinus Beijerinck, who was a Professor of Microbiology at the Technical University the Netherlands, put forth his concepts that viruses were small and determined that the "mosaic disease" remained infectious when passed through a Chamberland filter-candle. This was in contrast to bacteria microorganisms, which were retained by the filter. Beijerinck referred to the infectious filtrate as a "contagium vivum fluidum", thus the coinage of the modern term "virus".

After the initial discovery of the 'viral concept' there was need to classify any other known viral diseases based on the mode of transmission even though microscopic observation proved fruitless. In 1939 Holmes published a classification list of 129 plant viruses. This was expanded and in 1999 there were 977 officially recognized, and some provisional, plant virus species.

The purification (crystallization) of TMV was first performed by Wendell Stanley, who published his findings in 1935, although he did not determine that the RNA was the infectious material. However, he received the Nobel Prize in Chemistry in 1946. In the 1950s a discovery by two labs simultaneously proved that the purified RNA of the TMV was infectious which reinforced the argument. The RNA carries genetic information to code for the production of new infectious particles.

More recently virus research has been focused on understanding the genetics and molecular biology of plant virus genomes, with a particular interest in determining how the virus can replicate, move and infect plants. Understanding the virus genetics and protein functions has been used to explore the potential for commercial use by biotechnology companies. In particular, viral-derived sequences have been used to provide an understanding of novel forms of resistance. The recent boom in technology allowing humans to manipulate plant viruses may provide new strategies for production of value-added proteins in plants.

Viruses are extremely small and can only be observed under an electron microscope. The structure of a virus is given by its coat of proteins, which surround the viral genome. Assembly of viral particles takes place spontaneously.

Over 50% of known plant viruses are rod-shaped (flexuous or rigid). The length of the particle is normally dependent on the genome but it is usually between 300–500 nm with a diameter of 15–20 nm. Protein subunits can be placed around the circumference of a circle to form a disc. In the presence of the viral genome, the discs are stacked, then a tube is created with room for the nucleic acid genome in the middle. [5]

The second most common structure amongst plant viruses are isometric particles. They are 25–50 nm in diameter. In cases when there is only a single coat protein, the basic structure consists of 60 T subunits, where T is an integer. Some viruses may have 2 coat proteins that associate to form an icosahedral shaped particle.

There are three genera of Geminiviridae that consist of particles that are like two isometric particles stuck together.

A very small number of plant viruses have, in addition to their coat proteins, a lipid envelope. This is derived from the plant cell membrane as the virus particle buds off from the cell.

Through sap Edit

Viruses can be spread by direct transfer of sap by contact of a wounded plant with a healthy one. Such contact may occur during agricultural practices, as by damage caused by tools or hands, or naturally, as by an animal feeding on the plant. Generally TMV, potato viruses and cucumber mosaic viruses are transmitted via sap.

Insects Edit

Plant viruses need to be transmitted by a vector, most often insects such as leafhoppers. One class of viruses, the Rhabdoviridae, has been proposed to actually be insect viruses that have evolved to replicate in plants. The chosen insect vector of a plant virus will often be the determining factor in that virus's host range: it can only infect plants that the insect vector feeds upon. This was shown in part when the old world white fly made it to the United States, where it transferred many plant viruses into new hosts. Depending on the way they are transmitted, plant viruses are classified as non-persistent, semi-persistent and persistent. In non-persistent transmission, viruses become attached to the distal tip of the stylet of the insect and on the next plant it feeds on, it inoculates it with the virus. [6] Semi-persistent viral transmission involves the virus entering the foregut of the insect. Those viruses that manage to pass through the gut into the haemolymph and then to the salivary glands are known as persistent. There are two sub-classes of persistent viruses: propagative and circulative. Propagative viruses are able to replicate in both the plant and the insect (and may have originally been insect viruses), whereas circulative can not. Circulative viruses are protected inside aphids by the chaperone protein symbionin, produced by bacterial symbionts. Many plant viruses encode within their genome polypeptides with domains essential for transmission by insects. In non-persistent and semi-persistent viruses, these domains are in the coat protein and another protein known as the helper component. A bridging hypothesis has been proposed to explain how these proteins aid in insect-mediated viral transmission. The helper component will bind to the specific domain of the coat protein, and then the insect mouthparts – creating a bridge. In persistent propagative viruses, such as tomato spotted wilt virus (TSWV), there is often a lipid coat surrounding the proteins that is not seen in other classes of plant viruses. In the case of TSWV, 2 viral proteins are expressed in this lipid envelope. It has been proposed that the viruses bind via these proteins and are then taken into the insect cell by receptor-mediated endocytosis.

Nematodes Edit

Soil-borne nematodes also have been shown to transmit viruses. [7] They acquire and transmit them by feeding on infected roots. Viruses can be transmitted both non-persistently and persistently, but there is no evidence of viruses being able to replicate in nematodes. The virions attach to the stylet (feeding organ) or to the gut when they feed on an infected plant and can then detach during later feeding to infect other plants. Examples of viruses that can be transmitted by nematodes include tobacco ringspot virus and tobacco rattle virus.

Plasmodiophorids Edit

A number of virus genera are transmitted, both persistently and non-persistently, by soil borne zoosporic protozoa. These protozoa are not phytopathogenic themselves, but parasitic. Transmission of the virus takes place when they become associated with the plant roots. Examples include Polymyxa graminis, which has been shown to transmit plant viral diseases in cereal crops [8] and Polymyxa betae which transmits Beet necrotic yellow vein virus. Plasmodiophorids also create wounds in the plant's root through which other viruses can enter.

Seed and pollen borne viruses Edit

Plant virus transmission from generation to generation occurs in about 20% of plant viruses. When viruses are transmitted by seeds, the seed is infected in the generative cells and the virus is maintained in the germ cells and sometimes, but less often, in the seed coat. When the growth and development of plants is delayed because of situations like unfavorable weather, there is an increase in the amount of virus infections in seeds. There does not seem to be a correlation between the location of the seed on the plant and its chances of being infected. [5] Little is known about the mechanisms involved in the transmission of plant viruses via seeds, although it is known that it is environmentally influenced and that seed transmission occurs because of a direct invasion of the embryo via the ovule or by an indirect route with an attack on the embryo mediated by infected gametes. [5] [6] These processes can occur concurrently or separately depending on the host plant. It is unknown how the virus is able to directly invade and cross the embryo and boundary between the parental and progeny generations in the ovule. [6] Many plants species can be infected through seeds including but not limited to the families Leguminosae, Solanaceae, Compositae, Rosaceae, Cucurbitaceae, Gramineae. [5] Bean common mosaic virus is transmitted through seeds.

Direct plant-to-human transmission Edit

Researchers from the University of the Mediterranean in Marseille, France have found tenuous evidence that suggest a virus common to peppers, the Pepper Mild Mottle Virus (PMMoV) may have moved on to infect humans. [9] This is a very rare and highly unlikely event as, to enter a cell and replicate, a virus must "bind to a receptor on its surface, and a plant virus would be highly unlikely to recognize a receptor on a human cell. One possibility is that the virus does not infect human cells directly. Instead, the naked viral RNA may alter the function of the cells through a mechanism similar to RNA interference, in which the presence of certain RNA sequences can turn genes on and off," according to Virologist Robert Garry from the Tulane University in New Orleans, Louisiana. [10]

75% of plant viruses have genomes that consist of single stranded RNA (ssRNA). 65% of plant viruses have +ssRNA, meaning that they are in the same sense orientation as messenger RNA but 10% have -ssRNA, meaning they must be converted to +ssRNA before they can be translated. 5% are double stranded RNA and so can be immediately translated as +ssRNA viruses. 3% require a reverse transcriptase enzyme to convert between RNA and DNA. 17% of plant viruses are ssDNA and very few are dsDNA, in contrast a quarter of animal viruses are dsDNA and three-quarters of bacteriophage are dsDNA. [12] Viruses use the plant ribosomes to produce the 4-10 proteins encoded by their genome. However, since many of the proteins are encoded on a single strand (that is, they are polycistronic) this will mean that the ribosome will either only produce one protein, as it will terminate translation at the first stop codon, or that a polyprotein will be produced. Plant viruses have had to evolve special techniques to allow the production of viral proteins by plant cells.

5' Cap Edit

For translation to occur, eukaryotic mRNAs require a 5' Cap structure. This means that viruses must also have one. This normally consists of 7MeGpppN where N is normally adenine or guanine. The viruses encode a protein, normally a replicase, with a methyltransferase activity to allow this.

Some viruses are cap-snatchers. During this process, a 7m G-capped host mRNA is recruited by the viral transcriptase complex and subsequently cleaved by a virally encoded endonuclease. The resulting capped leader RNA is used to prime transcription on the viral genome. [13]

However some plant viruses do not use cap, yet translate efficiently due to cap-independent translation enhancers present in 5' and 3' untranslated regions of viral mRNA. [14]

Readthrough Edit

Some viruses (e.g. tobacco mosaic virus (TMV)) have RNA sequences that contain a "leaky" stop codon. In TMV 95% of the time the host ribosome will terminate the synthesis of the polypeptide at this codon but the rest of the time it continues past it. This means that 5% of the proteins produced are larger than and different from the others normally produced, which is a form of translational regulation. In TMV, this extra sequence of polypeptide is an RNA polymerase that replicates its genome.

Production of sub-genomic RNAs Edit

Some viruses use the production of subgenomic RNAs to ensure the translation of all proteins within their genomes. In this process the first protein encoded on the genome, and is the first to be translated, is a replicase. This protein will act on the rest of the genome producing negative strand sub-genomic RNAs then act upon these to form positive strand sub-genomic RNAs that are essentially mRNAs ready for translation.

Segmented genomes Edit

Some viral families, such as the Bromoviridae instead opt to have multipartite genomes, genomes split between multiple viral particles. For infection to occur, the plant must be infected with all particles across the genome. For instance Brome mosaic virus has a genome split between 3 viral particles, and all 3 particles with the different RNAs are required for infection to take place.

Polyprotein processing Edit

Polyprotein processing is adopted by 45% of plant viruses, such as the Potyviridae and Tymoviridae. [11] The ribosome translates a single protein from the viral genome. Within the polyprotein is an enzyme (or enzymes) with proteinase function that is able to cleave the polyprotein into the various single proteins or just cleave away the protease, which can then cleave other polypeptides producing the mature proteins.

Plant viruses can be used to engineer viral vectors, tools commonly used by molecular biologists to deliver genetic material into plant cells they are also sources of biomaterials and nanotechnology devices. [15] [16] Knowledge of plant viruses and their components has been instrumental for the development of modern plant biotechnology. The use of plant viruses to enhance the beauty of ornamental plants can be considered the first recorded application of plant viruses. Tulip breaking virus is famous for its dramatic effects on the color of the tulip perianth, an effect highly sought after during the 17th-century Dutch "tulip mania." Tobacco mosaic virus (TMV) and cauliflower mosaic virus (CaMV) are frequently used in plant molecular biology. Of special interest is the CaMV 35S promoter, which is a very strong promoter most frequently used in plant transformations. Viral vectors based on tobacco mosaic virus include those of the magnICON® and TRBO plant expression technologies. [16]


Extracting DNA in 10 Easy Steps

  1. Mush the banana in the resealable bag for about a minute until all the lumps are gone and it almost looks like pudding.
  2. Fill a cup with the hot water and salt.
  3. Pour the saltwater mix into the bag. Close the bag and very gently squeeze and move the saltwater and banana mush together. Do this for 30 to 45 seconds.
  4. Add the dishwashing soap into the bag and gently mix the contents. Try to avoid making too much foam.
  5. Place the coffee filter in a clear glass cup, securing the top of the filter around the lip of the cup.
  6. Pour the mix into the filter and let it sit until all of the liquid drips down into the cup.
  7. Remove and discard the used coffee filter.
  8. Tilt the glass and slowly add cold alcohol down the side of the cup. You want the alcohol to form a layer on top of the banana mix, staying separated, so be careful not to pour it too fast. Make a layer of alcohol that is 2.5-5cm (1-2in) thick.
  9. After the alcohol layer is set up, wait for eight minutes. You may see some bubbles and cloudy material moving around in the alcohol. This is the DNA pieces clumping together.
  10. Use the wooden stirrer to start poking the cloudy stuff in the alcohol layer. Spin the stirrer it in place to start gathering the cloudy stuff. When you are done, take a closer look at the stuff on the stirrer. You are looking at DNA!

(Teacher & student packet is available.)

What Happened?

You may understand that mashing a banana can break cells apart and help break apart cell walls, but why was all that other stuff added? And how did we get inside the cells and get the DNA to stick together?


Fats and Oils

Fats are a common and well-known form of lipids. They are made by bonding fatty acids to an alcohol.

The most common fat is triacylglycerol. Triacylglycerol is a fat made from three fatty acids bonded to an alcohol called ‘glycerol’. Glycerol is a three-carbon alcohol and each of the carbons bond to one fatty acid.

The structure of the fatty acids of a fat determines if a fat is saturated or unsaturated. Double bonds in one or more alkyl chains of the fatty acids create an unsaturated fat. A fat molecule with no double bonds in any of its alkyl chains is known as a saturated fat.

A double bond creates a bend in an alkyl chain. This reduces how tightly fat molecules can be packed together. Loosely packed fats have lower melting points which is why unsaturated fats, such as vegetable oils, are commonly liquid at room temperature. Saturated fats, on the other hand, have higher melting points and are more likely to be found as solids at room temperature.

The main function of fat is to store energy. They are most common in animals because they contain a very large amount of energy for their weight.

A fat molecule will hold far more energy than a carbohydrate molecule of the same weight. For mobile animals carrying extra weight is not ideal so storing energy in lightweight molecules is beneficial. Fats are stored in tissue known as ‘adipose tissue’ and in cells known as ‘adipose cells’.


Data structures

A is a group of data elements grouped together under one name. These data elements, known as members, can have different types and different lengths. Data structures can be declared in C++ using the following syntax:

struct type_name <
member_type1 member_name1
member_type2 member_name2
member_type3 member_name3
.
.
> object_names

Where type_name is a name for the structure type, object_name can be a set of valid identifiers for objects that have the type of this structure. Within braces <> , there is a list with the data members, each one is specified with a type and a valid identifier as its name.

This declares a structure type, called product , and defines it having two members: weight and price , each of a different fundamental type. This declaration creates a new type ( product ), which is then used to declare three objects (variables) of this type: apple , banana , and melon . Note how once product is declared, it is used just like any other type.

Right at the end of the struct definition, and before the ending semicolon ( ), the optional field object_names can be used to directly declare objects of the structure type. For example, the structure objects apple , banana , and melon can be declared at the moment the data structure type is defined:

In this case, where object_names are specified, the type name ( product ) becomes optional: struct requires either a type_name or at least one name in object_names , but not necessarily both.

It is important to clearly differentiate between what is the structure type name ( product ), and what is an object of this type ( apple , banana , and melon ). Many objects (such as apple , banana , and melon ) can be declared from a single structure type ( product ).

Once the three objects of a determined structure type are declared ( apple , banana , and melon ) its members can be accessed directly. The syntax for that is simply to insert a dot ( . ) between the object name and the member name. For example, we could operate with any of these elements as if they were standard variables of their respective types:

Each one of these has the data type corresponding to the member they refer to: apple.weight , banana.weight , and melon.weight are of type int , while apple.price , banana.price , and melon.price are of type double .

Here is a real example with structure types in action:

The example shows how the members of an object act just as regular variables. For example, the member yours.year is a valid variable of type int , and mine.title is a valid variable of type string .

But the objects mine and yours are also variables with a type (of type movies_t ). For example, both have been passed to function printmovie just as if they were simple variables. Therefore, one of the features of data structures is the ability to refer to both their members individually or to the entire structure as a whole. In both cases using the same identifier: the name of the structure.

Because structures are types, they can also be used as the type of arrays to construct tables or databases of them:

Pointers to structures

Like any other type, structures can be pointed to by its own type of pointers:

Here amovie is an object of structure type movies_t , and pmovie is a pointer to point to objects of structure type movies_t . Therefore, the following code would also be valid:

The value of the pointer pmovie would be assigned the address of object amovie .

Now, let's see another example that mixes pointers and structures, and will serve to introduce a new operator: the arrow operator ( -> ):

The arrow operator ( -> ) is a dereference operator that is used exclusively with pointers to objects that have members. This operator serves to access the member of an object directly from its address. For example, in the example above:

is, for all purposes, equivalent to:

Both expressions, pmovie->title and (*pmovie).title are valid, and both access the member title of the data structure pointed by a pointer called pmovie . It is definitely something different than:

which is rather equivalent to:

This would access the value pointed by a hypothetical pointer member called title of the structure object pmovie (which is not the case, since title is not a pointer type). The following panel summarizes possible combinations of the operators for pointers and for structure members:

ExpressionWhat is evaluatedEquivalent
a.b Member b of object a
a->b Member b of object pointed to by a (*a).b
*a.b Value pointed to by member b of object a *(a.b)

Nesting structures

Structures can also be nested in such a way that an element of a structure is itself another structure:

After the previous declarations, all of the following expressions would be valid:


Structure of a Toxic Matter Identified That Destroys the Nerves in the Brain, Causing Alzheimer’s and Parkinson’s Diseases

Alzheimer’s disease – also called dementia – where memory and cognitive functions gradually decline due to deformation and death of neurons, and Parkinson’s disease that causes tremors in hands and arms impeding normal movement are major neurodegenerative diseases. Recently, a research team at POSTECH has identified the structure of the agent that causes Alzheimer’s and Parkinson’s diseases to occur together.

A research team led by Professor Joon Won Park and Ph.D. candidate Eun Ji Shin of the Department of Chemistry at POSTECH investigated the surface structure of hetero-oligomers found in the overlap of Alzheimer’s disease and Parkinson’s disease, using an atomic force microscopy (AFM) to reveal their structural identity. This study was featured as the front cover paper in the latest issue of Nano Letters.

It is known that the pathological overlap of Alzheimer’s disease and Parkinson’s disease is associated with the formation of hetero-oligomers derived from amyloid-beta and alpha-synuclein. However, it was difficult to study the treatment due to technical limitations in observing their structure.

Schematic diagram of quadruple force mapping of hetero-oligomers derived from amyloid-beta and alpha-synuclein. Hetero-oligomers were characterized by the four types of AFM probes tethering an antibody recognizing each end of peptides. Credit: POSTECH

To this, the researchers used the AFM to observe the surface characteristic of the hetero-oligomer nano-aggregates derived from amyloid-beta, known as the biomarker of Alzheimer’s disease, and alpha-synuclein, known as the biomarker of Parkinson’s disease, at the single-molecule level.

Front cover of Nano Letters. Credit: POSTECH

When the research team investigated with four AFM tips immobilized with antibodies that recognize N-terminus or C-terminus of each peptide, it was confirmed that all aggregates were hetero-oligomers. In addition, in the case of hetero-oligomer, it was confirmed that the probability of recognizing the end of the peptide is higher than that of the homo-oligomer. [1]

This result indicates that the end of each peptide has a bigger tendency to be located on the surface of hetero-oligomers than homo-oligomers, or that the ends of the peptides located on the surface have more degrees of freedom. That is, it can be confirmed that the aggregation between peptides is more loosely packed in the hetero-oligomer than in the homo-oligomer.

This study is the first study to observe the structure of protein disordered nano-aggregates, which has never been identified before, using the quadruple mapping with four AFM tips. It serves as experimental grounds to verify the hypothesis of hetero-oligomer aggregation. It can also be used in studies related to the overlapping phenomena of various neurodegenerative diseases other than Alzheimer’s and Parkinson’s.

“Until now, there was no adequate method to analyze the nano-aggregates, making it impossible to elucidate the structural identity of heterogeneous aggregates,” explained Professor Joon Won Park. “As the analysis method developed in this study is applicable to other amyloid protein aggregates, it will help to identify the cause of diseases such as Alzheimer’s or the mad cow disease.”


For students who have prior knowledge of the structure and nature of DNA, the addition of cold ethanol at the end of the activity provides an impressive moment when the white goo of DNA appears so suddenly and in such quantity. As it contrasts starkly with the clear liquid extract from the cells, students may be pleased to be able to see for themselves this substance that they know to control life’s processes.

For students who have no prior knowledge of the nature of DNA prior to beginning the activity, their own preparation of DNA may serve as an intriguing lead-in to a more conceptual discussion about the structure and function of the genetic material.


What is this unusual structure inside this banana? - Biology

Tunicates, commonly called sea squirts, are a group of marine animals that spend most of their lives attached to docks, rocks or the undersides of boats. To most people they look like small, colored blobs. It often comes as a surprise to learn that they are actually more closely related to vertebrates like ourselves than to most other invertebrate animals.

Tunicates are part of the phylum Urochordata, closely related to the phylum Chordata that includes all vertebrates. Because of these close ties, many scientists are working hard to learn about their biochemistry, their developmental biology, and their genetic relationship to other invertebrate and vertebrate animals.

Are they really our cousins?
One clue that tunicates are related to vertebrates is found in the tunicate larva, or tadpole. It even looks like a tiny tadpole, and has a nerve cord down its back, similar to the nerve cord found inside the vertebrae of all vertebrates. The Cerebral Vesicle is equivalent to a vertebrate's brain. Sensory organs include an eyespot , to detect light, and an otolith , which helps the animal orient to the pull of gravity.

A tunicate is built like a barrel. The name, "tunicate" comes from the firm, but flexible body covering, called a tunic . Most tunicates live with the posterior, or lower end of the barrel attached firmly to a fixed object, and have two openings, or siphons , projecting from the other. Tunicates are plankton feeders. They live by drawing seawater through their bodies. Water enters the oral siphon, passes through a sieve-like structure, the branchial basket that traps food particles and oxygen, and is expelled through the atrial siphon .
The tail also has a semi-rigid rod called a notochord , which can be compared to the spine of true vertebrates.

Tunicate tadpoles mature extremely quickly, in a matter of just a few hours. Since the tadpoles do not feed at this stage of their lives, they have no mouths. Their sole job is to find a suitable place to live out their lives as adults. When ready to settle, a sticky secretion helps them attach head first to the spot they have chosen. They then reabsorb all the structures within their tail and recycle them to build new structures needed for their adult way of life.

Some kinds of tunicates live alone, and are called solitary tunicates. Others, including the two forms shown here, have the ability to bud off additional individuals from the first to arrive, and these grow into colonies. At first glance, these colonial tunicates look much like other encrusting marine animals, such as sponges. If you look closer, you can see that they have the same structures as solitary tunicates, only much tinier.

Still other members of this group never attach to objects, but live out their entire lives as planktonic drifters. These include thaliaceans , strange gelatinous animals that use their siphons to jet-propel themselves gently through the water. The two photos immediately below were taken of the same animal. Pyrosoma atlanticum. The the image on the left was filmed with artificial light, while the one on the right shows the light, or bioluminescence, produced by the animal itself.

Another planktonic group of Urocordates includes the larvaceans . These animals live inside intricate mucous "houses" and retain their larval tail throughout their lives. This tail drives a gentle current of water through the house, propelling the organism through the water. The photograph below shows the organism, Oikopleura vanhoeffeni , inside its house, creating a current by movements of its tail.

Acknowledgements to Dr. Euichi Hirose of University of Ruykyus, Japan, and to Dr. Alexander Bochdansky, Queens University, Canada, for the above pictures of thaliacean and larvacean Urochordates .

How will we recognize the non-native tunicate species, Ciona savignyi when it appears ? What do we know about this species? For more information, go to C. savignyi.


Where to Buy Banana Flowers

In areas where bananas grow, banana flowers are sold at farmers' markets, road stands, and some grocery stores. If you're not in a tropical locale resplendent with banana trees, you may find banana flowers at Asian or Indian food stores or specialty markets sometimes they're in the produce department, but you may be able to find them canned or in frozen foods section. If you do buy them frozen, they work well in cooked preparations where you want their flavor, but won't defrost well into for use in a salad or otherwise serve raw.

When shopping or otherwise presented with the opportunity to procure some flowers, choose ones that feel firm and whose leaves are tightly packed. Sometimes you may be able to purchase them wrapped in plastic, which helps retain both the color and moisture in the leaves.

If your climate allows, planting your own banana tree is a great way to create a predictable supply of banana flowers—and bananas, too.


Watch the video: Mysterious Black Thing Inside This Banana, What Is It? (January 2022).