AP Biology class blog for discussing current research in Biology

Author: jamesome

Researchers Discovered a Possible Antidote for the Most Deadly Mushroom

There is a reason why it is not advisable to eat wild mushrooms; Amanita Amanita phalloides 2011 G3phalloides, nicknamed death cap mushrooms, closely resemble edible mushroom variants—but are deadly if ingested. If a person chances upon one and happens to eat it, regardless of whether it is cooked, there is a high likelihood that they die.

A. phalloides are the most toxic of any mushroom species and are responsible for the majority of fatal mushroom poisonings. Notable victims of death cap mushroom poisoning include Roman Emperor Claudius, Pope Clement VII, and Holy Roman Emperor Charles VI. A. phalloides poisoning has always been difficult to diagnose and even more difficult to treat, as symptoms emerge after a long delay and there has been no known antidote to A. phalloides toxin—that is, until researchers utilized CRISPR-Cas9.

Death cap mushrooms contain the amatoxin alpha-amanitin. The amatoxins are a group of toxins that share the trait of inhibiting the enzyme RNA polymerase II. In our AP Biology class, we discussed DNA polymerases and their vital function in DNA replication. Similarly, RNA polymerases are a vital component of RNA transcription and synthesis. RNA polymerase II synthesizes mRNA, the template for protein synthesis. Upon the inhibition of RNA polymerase II, cell metabolism comes to a halt and apoptosis (cell self-destruction) ensues.

Alpha-amanitin is possibly the most deadly of the amatoxins. The particular human genes that are triggered by alpha-amanitin were previously unknown, but CRISPR recently revealed these genes, one of which produces the protein STT3B. STT3B is a required component of alpha-amanitin toxicity, therefore an inhibitor of STT3B would negate the effects of alpha-amanitin.

Researchers found just that—an inhibitor of STT3B, indocyanine green. Once the effectiveness of indocyanine green was confirmed in vitro, scientists experimented with a mouse model of alpha-amanitine poisoning and found that indocyanine green had a profound effect if given one to four hours after ingestion of the toxin. However, if eight to 12 hours had elapsed before the indocyanine green was introduced, its effectiveness was greatly reduced, possibly because irreversible organ damage had already occurred in the subject. This fact poses concern, as alpha-amanitine poisoning symptoms take at least six hours to occur after A. phalloides ingestion.

While more investigation needs to be undertaken before indocyanine green can be proposed as a treatment for death cap mushroom poisoning, these latest discoveries represent a significant advancement in our understanding of the process. Any thoughts regarding CRISPR or this topic as a whole are encouraged.

Cancer-Causing Free Radicals Are the Key to Tardigrade Survival

Tardigrade (50594282802)

Many may recognize the resilience of tardigrades, the microscopic water bears that can seemingly endure any and all conditions—researchers have found that tardigrades possess this attribute because of their ability to harness free radicals, the infamous matter that causes cancer in humans.

Tardigrades have survived all five mass extinction events on Earth, and are thought to have been around since before the current eon. They can live through extreme temperature and radiation, and even the vacuum of space. But how are they capable of this immense resilience?

Traditionally, free radicals have been known to promote cancer, causing genetic mutations that allow cells to multiply uncontrollably. First, in mitosis, the mutated cell divides, then its offspring divides, and before long a mass forms. That mass, or tumor, grows uncontrollably, consuming vital nutrients and mechanically interfering with the body’s internal function. If left unchecked, the tumor will eventually overwhelm the body’s ability to survive. However, there’s a flip side to free radicals.

The tardigrade has managed to harness the destructive power of free radicals in its quest for survival. For years, scientists have been baffled by the tardigrade’s ability to undergo drastic transformation in times of extreme stress. The organism’s transformations are a part of cryptobiosis, which consists of (but is not limited to) anhydrobiosis and cryobiosis. In anhydrobiosis, the tardigrade decreases its water content by 99% and its metabolic rate by 99.99%, and remains in a “tun” state for five years or more, only to rehydrate and flourish once environmental conditions are back to normal. In addition, via cryobiosis and other cryptobiosis processes, the tardigrade can survive extreme heat (304° F) and cold (-458° F). And the trigger for all of these survival mechanisms: free radicals, the same extra-electron atoms and molecules that cause human cells to mutate and multiply to form tumors.

Recent research suggests that tardigrades initiate cryptobiosis and protect themselves by releasing intracellular reactive oxygen species (free radicals) that in turn reversibly oxidize cysteine, an amino acid that acts as a sort of regulatory sensor for responses to stressors. The obvious question is: why isn’t the tardigrade harmed by the free radicals? The answer might hold the key to better understanding how to prevent cellular mutation, and cancer, in humans. Additional investigation is needed in this area.

So, what do you think? Are there similar discoveries that may be able to help us combat cancer?

From Individual to Environmental: COVID-19 Antigen Testing Expands

Until recently, testing for COVID-19 has focused on the individual rather than on the environment. However, newly introduced technology promises to expand the scope of COVID-19 detection. Researchers at Washington University in St. Louis have developed an apparatus to detect the presence of the covert virus in SARS-CoV-2 without backgroundenvironmental settings. Previous attempts at this technology have been limited by the volume of air tested. Without adequate air quantity, the sensitivity of the technology is negatively impacted. The current system, however, is capable of concentrating up to 1000 m³ of air per minute, compared to the two to eight cubic meters assessed in previous attempts. The result is a system that increases viral detection sensitivity while maintaining specificity.

The newly introduced apparatus functions by using centrifugal force to approximate viral particles to a liquid matrix adherent to the wall of the test chamber. Within the matrix are found nanobodies, bioengineered antibody fragments derived from llama antibodies. As we discussed in class, the human immune system is composed of humoral and self-mediated factors. Antibodies fall into the humoral category. While human antibodies consist of a light chain and a heavy chain, llama antibodies are composed of two heavy chains. By isolating heavy chain llama antibody fragments sensitized to the COVID-19 spike protein and then splicing multiple sensitized heavy chains together, researchers were able to amplify the viral signal, in a manner similar to PCR.

While the device has yet to be approved, cleared, or authorized by the FDA, it holds promise for meaningful real-world application. For example, prior to a large public event, indoor spaces could be screened for the presence of COVID-19. If the virus were detected, remediation could be performed and the environment retested prior to the public event. In doing so, countless potential COVID-19 infections could be avoided.

This novel technology diverges from current efforts at viral detection in that it does not rely on the existence of an infected individual but rather focuses on environmental detection thereby constituting primary prevention. In the future, the technology could be applied to prevention of other infectious diseases, both viral and bacterial. Further work is needed to explore the potential application of this method.

I urge readers to respond to the above and offer opinions.

The Great Disappearance of the Alaskan Snow Crab

Have you ever indulged in the scrumptious cuisine that is Alaskan Snow Crab? Any such meal is one to remember. However, there is a threat to this dish, and to the ChSnow crab legs and old bay seasoningionoecetes opilio species as a whole: the crabs are cannibalizing each other. Or so, scientists think.

The snow crab population was once rapidly expanding in the eastern Bering Sea, reaching its highest recorded abundance in 2018 at 11.7 billion. The population then rapidly declined to an all-time low of 940 million in 2021. At least 10.76 billion crabs disappeared within the course of 3 years. But where did they go? Chionoecetes opilio 31353372

Researchers have proposed various theories to account for the decline in population. The first obstacle was determining whether the crabs had died off, or merely relocated. After surveying the surrounding habitats and observing no significant influx of snow crabs, the researchers were able to conclude that the crabs had indeed passed on.

With the cause of the crab disappearance isolated, theories were proposed for the cause of death. Temperature, predation, fishery, disease, and cannibalism were all considered. As far as temperature, snow crabs typically exist in cold environments—hence their name. An increase of temperature in their habitats could potentially have accelerated the crabs’ metabolic rates, and consequently expended calories at a rapid rate. With regard to predation, snow crabs are a component of the Pacific cod diet. Relative changes in abundance and distribution of the cod species could have affected the rate of snow crab death. Fisheries provided yet another possibility, as trawling rates are dependent on consumer demand. Disease was also a consideration. Snow crabs are susceptible to Bitter Crab Syndrome, a disease caused by the dinoflagellate parasite Hematodinium perezi, a single-celled eukaryote. Single-celled eukaryotes are organisms comprised of a single cell, as discussed in class. Finally, cannibalism could have been at play. Large snow crabs have been observed to cannibalize smaller snow crabs as a source of food.

Researchers were able to rule out predation and fishery as potential causes of the snow crab population decline. Disease and cannibalism were also eliminated. Through the use of various models, researchers determined that environmental temperature and population density correlated positively with crab mortality, Global Warming In The Worldparticularly in mature crabs. Therefore, increased caloric expenditure as a result of increased environmental temperature was identified as the likely culprit of the crabs’ disappearance. Accordingly, a clear link exists between declines in snow crab population and climate change. Further work is necessary to clarify the exact association between the two phenomena.

I invite comments and potential solutions to this serious challenge.

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