BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: Parasite

This Parasite Can Change Agriculture for the Better

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On October 27, 2021

In Student Post

When parasites take control of a host, it may seem like all is lost for the unfortunate animal. However, a newly discovered parasite uses a mechanism that actually slows down plant aging, and may offer new ways to protect crops that were once threatened by diseases. 

Prior to this discovery, very little was known on how this parasite functioned on both a molecular and mechanistic basis. The Hogenhout group at the John Innes Centre and collaborators published in Cell have identified a manipulation molecule produced by Phytoplasma bacteria, which hijacks the development of plants. This protein breaks down key growth regulators, which as a result causes abnormal growth.

According to an article published by FronteirsIn, phytoplasmas and their associated diseases cause severe yield loss globally. For example, Aster Yellows cause major yield losses in crops such as lettuce, carrots, and cereals. As stated in the article, “Phytoplasma diseases of vegetable crops are characterized by symptoms such as little leaves, phydolly, flower virescence, big buds, and witches’ brooms.” These effects ultimately cause the host plants to die over time. 

Phytoplasma Growing on a Plant

Professor Saskia Hogenhuot said that “Our findings cast new light on a molecular mechanism behind this extended phenotype in a way that could help solve a major problem for food production.” One of these findings includes the bacteria protein entitled SAP05, which manipulates the plant’s molecular structure. This manipulation targets the process of the proteasome, which breaks down obsolete proteins inside plant cells. SAP05 causes the plant proteins that are used for regulating growth and development to be thrown out. With the absence of the proteins, the plant’s development favors the bacteria, which in turn triggers vegetative growth and pauses the plant’s aging process.

Specifically, SAP05 directly binds to the plant developmental proteins and the proteasome. Proteasomes hold a very important role in the cell regarding the degradation of proteins, with Professor Gonzalez writing, “proteasomes perform crucial roles in many cellular pathways by degrading proteins to enforce quality control and regulate many cellular processes such as cell cycle progression, signal transduction, cell death, immune responses, metabolism, protein-quality control, and development.” Conversely, SAP05’s direct binding is a newly discovered method of degrading proteins, unlike the usual fashion of proteins degraded by proteasomes that are tagged with ubiquitin beforehand. 

To further study SAP05, the research team wanted to see if SAP05 affects the insects that carry the bacteria plant to plant. Turns out, SAP05 does not affect the insects due to the structure of the host proteins in animals differing enough from plants. This research also enabled the team to identify the two amino acids in the proteasome that interact with SAP05. If these two amino acids in the plant proteins were switched to the amino acids found in the insect protein, they would prevent abnormal growth. 

In a polypeptide chain, every amino acid is important to how the chain functions. Specifically, an amino acid’s unique side-chain gives it different characteristics, which plays a role in how the protein is structured and its function in the cell. In this case, these two amino acids from plant to insect proteins ultimately change the way SAP05 interacts with the polypeptide chain, which as a result changes the effect. 

Personally, I feel that this discovery is groundbreaking since it enables countless possibilities regarding the prevention of mass yield loss. How do you think this research will be utilized in the future? Let me know in the comments!

Zombie Apocalypse? Yes, it’s happening right now.

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On October 26, 2019

In Student Post

Most of us would think that a zombie apocalypse is simply a fantasy seen in scary movies. However, in Brazil, this freaky fantasy has rapidly turned into reality for some unfortunate carpenter ants. In the Brazilian rainforests, one could find carpenter ants whose jaws are forever locked onto a leaf, with a fungus growing right through the dead ant’s face. This is a result of the deadly zombie-like fungi that is brutally murdering ants, otherwise known as Ophiocordyceps unilateralis. 

Ophiocordyceps unilateralis initially infects its victims through spores that are launched from other zombie-ant fungi. The fungus initially penetrates the ant’s exoskeleton as singular cells, but eventually begins multiplying rapidly to form an inviolable fungal network.  This network engulfs the ant’s nervous system and muscles, and eventually the ant capitulates to the parasitic fungi. The ant slowly begins to deteriorate, beginning with simple actions like leaving its colony, to eventually losing full control of its body and dying. However, before the horrible death that the ant suffers, lots of actions take place within the ant’s body. After leaving its colony, the fungi commands the ant to move to a height of approximately 10 inches above the ground. This is done because it is the ideal height for the humidity that the fungi needs to proliferate and flourish inside the ant’s body. Next, the fungi commands the ant use its jaws to permanently form a death grip into a twig or leaf, so it will never move its body ever again. After inevitably killing the ant, the fungi proceeds to grow right through the face of the ant, where it will consequently release more spores to be spread to other ants. Over time, the fungi will spread quickly, and zombify entire colonies of ants.

It’s seriously wild to think that fungi in Brazilian jungles are brutally murdering and zombifying ants by taking over their entire bodies! Moreover, it is crazy that something as simple as a single celled fungi that enters an ant’s blood flow is powerful enough to expeditiously wipe away an ant’s entire life. With over 400 different species of this fungi in the wild, we can expect the ant zombie apocalypse to continue in the jungles of Brazil.

 

 

Carpenter ants that have fallen victim to Ophiocordyceps unilateralis. 

 

The Zombie Apocalypse is Coming! – Sort of…

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On October 10, 2018

In Student Post

Imagine a disease that, once it infects another organism, it completely takes control of their body and uses it for further infection and mutilation. This is exactly what is happening in the incredibly noisy (100 decibels to be exact) seasonal insects, named the periodical cicada (Magicicada sp.). However much you might like or absolutely hate these insects (like me), they unfortunately are suffering from a rampant parasitic fungus that is essentially taking control of these bugs and turning them into zombies. This zombie fungus is incredibly brutal to the cicadas, causing their almost-lifeless body to be driven around by this fungus, losing parts of their own body while gaining another cicadas head that becomes attached during forced copulation by the fungus to infect more cicadas. It is pretty much like “The Walking Dead” in the insect world, with cicadas being driven around by a parasite infecting others at a rapid speed with insect parts flying all over the place. 

This fungus, the Massospora cicadina, typically begins its infection on the insect when the cicada nymphs come to the surface after about 17 years of feeding off of plant roots underground. When the come up, about 3-5 percent of the cicadas are infected by spores, which are conidia or asexually reproducing cells, and multiply by the thousands within the bug while hoping to spread to more and more cicadas in the trees. This is known as the stage I infection. A stage II infection by this parasite consists of sexually produced spores whose goal is to end up in the soil and wait, withstanding all environments, until the next cicada arises. After the infection takes place of either type of spore, the cicada essentially falls apart as their abdomen enlarges with white-spores, losing their reproductive segments as well as several of their limbs. But the catch is that, of course, the cicada doesn’t realize and therefore it carries on with its barely lifeless self and performs the tasks of any normal cicada. Including more copulation.

Pictured here is a Cicada affected with this fungus, missing half of its abdomen.

Not only do the cicadas with stage I walk around constantly with their open wound and drag along spores while the cicadas with stage II fly around spreading spores from their abdomen, but this zombie parasite also tremendously manipulates the insects sexual behaviors. As stated in the original paper in Scientific Reports, “It is relatively common to find a healthy cicada with its genitalia plunged into the abdominal spore mass of an infected partner or to see healthy cicadas attached to fragments of abdomen or terminalia that have torn free from infected partners during attempted copulation.”. But that’s not all. These parasites also cause male cicadas to take up female mating behavior and flick their wings in response to other male cicadas. One thing leads to another, and now it has been concluded that this fungus is more present in male cicadas since these infected males are now more willing to mate with both female and male cicadas, spreading the infection to both. Although many scientists and researchers (including myself) thought that maybe this parasite simply caused a feminizing effect within the insects, this practice of male wing flicking only occurs in cicadas with a stage I infection. Therefore this disproves what was previously hypothesized, since if this feminizing effect was a case, it would occur in every infection, not just the first stage.

Either way, these spores have been researched to manipulate and control a cicada’s behavior, whether it be sexual or not. But, who knows what this parasite might mean for humans as we already know how brutal and sadistic it can be. Do you think that this topic should be more heavily researched for not only cicadas wellbeing but also ours?

But next time you see a cicada, be careful it doesn’t look to you to turn you into the next real life zombie!

To read more about this new parasite affecting cicadas in the original source, click here.

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