AP Biology class blog for discussing current research in Biology

Tag: Pathogen

“And Then There Were None.” Not An Agatha Christie Murder Mystery, but an Eye-Opening Story of Extinction


A Land Snail

George the Snail

On January 1st, while we were all blissfully celebrating the transition from 2018 to 2019, the last land snail of the species Achatinella apexfluva, which had thrived for many years on the Hawaiian island of Oahu, had gone extinct.

The name of the snail was George. It was given to him by researchers so that he may be remembered and not simply become an extinct species left unknown to most. Researcher Michael Hadfield notes “You anthropomorphize it [i.e. George the snail] and people pay attention.” More importantly, though, is George’s story. He was “…born in the early 2000’s to parents that had been captured in the mountains [by scientists] in an effort to protect them from predators.” Then, there was a sudden mass extinction event. What researchers believe to be some form of a pathogen annihilated the remains of George’s already endangered species. George was the lone survivor of this unfortunate phenomena.

George’s species is not the only one to face extinction on the Hawaiian Islands. “At one point there were more than 750 species of land snails identified…” George’s species, however, was the first. Unfortunately, Dr. Sischo, who directs the state-run Snail Extinction Prevention Program, mentions that estimates say that “more than half of those species are already extinct.” There were other factors, other than the elusive pathogen, that have afflicted the land snails over a much longer period of time: “…invasive predators like rats and wolfsnail, which eats other snials. They also face habitat destruction and the effects of climate change; drier conditions have reduced the inhabitable land on the islands,” Dr. Sischo says.

In 2017, researchers removed a two-millimeter section of his foot and have preserved it in a “deep-freeze container” according to the Department of Land and Natural Resources. “The hope is that someday soon, scientists will develop the technology to clone a snail.”

Seagrasses: Benefitting the Ecosystem

Seagrasses have been known to improve water quality greatly, however it was only recently that scientists discovered other major benefits of the plants that reside in the ocean. The name seagrasses is a misnomer, for they are actually plants that grow in shallow ocean water. Seagrasses are one of the largest stores of carbon in the ocean, and they also remove excess nitrogen and phosphorous from the water.

A few years however, ecologist Joleah Lamb’s colleagues fell ill with amoebic dysentery. This is an intestinal illness that they contracted while conducting research on coral reefs in Indonesia. The illness can be caused by the release of raw sewage into the ocean by a city, which leads to a drastic increase in the populations of shoreline bacteria. The water collected close to the shore had been compared to offshore tidal flats and coral reefs with seagrass beds. The two different sites were very close to one another, yet the water where the seagrass was had a significantly smaller amount of Enterococcus bacteria. The bacteria in areas with seagrass was only 1/3 of that in other areas that did not have the plants. This bacteria is not only dangerous for humans, but is harmful for fish and other species as well.

While at this moment it is uncertain how the seagrasses clean the water, we know that seagrasses trap small particulates and prevent them from flowing on in the ocean. It is believed that the plants would catch the bacteria in the same way, or that the leaves might emit antimicrobial compounds that directly kill the bacteria. Another possibility could be that seagrasses release oxygen made during photosynthesis, and the oxygen is toxic to pathogens. Also, it is noted that seagrass meadows often are located next to coral reefs, so some suggest that they work together to protect one another from bacteria and other possible dangers.


Further reading:

Can your Medications Hurt you More Than Help?

This is an image of the GI tract. This is the location of where the illness affects the body.

Patrick Schloss, a scientist studying the affects of antibiotics, constructed an experiment that tested the susceptibility of mice to Clostridium difficile (C. diff), which is a bacteria that affects humans and animals. Symptoms include diarrhea and severe inflation of the colon. It is known as an in imbalance of the beneficial bacteria in the gut and is very hard to treat. Fecal transplants can be used to treat Clostridium difficile but he thinks that there may be an easier way. This illness is not caused by any one microbe, but it occurs when lots of bacteria are removed from the GI tract usually due to some form of antibiotic, that is taken to treat another issue that the person is having. Wouldn’t it be be easier if there was a way to prevent this illness in the first place? We all get a common cold, most of us are on the road to recovery once our physician  prescribes us an antibiotic to knock out out our infection. We just need to make sure that it doesn’t take out our good bacteria as well.

In Schloss’s experiment, he first gave mice antibiotics and measured the type and amount of bacteria in the GI tracts. They then added a pathogen to the experiment,  that would almost insure that the mice would get C.diff. When they got the results, they found something that might be very helpful to humans in the medical field.

They found that the mice that had the bacteria of specific groups were much less likely to get C.diff.  Porphyromonadaceae, Lachnospiraceae, Lactobacillus, Alistipes, and Turicibacter are groups of bacteria that seemed to protect the mice from getting the illness. While other bacteria groups increased the likely hood of the mouse getting it, such as Escherichia or Streptococcus bacteria.

This information could be very helpful while treating and even preventing C. diff. If given access to these antibiotics, doctors could diagnose the patient based on whichever bacteria they are lacking. We can prevent Cdiff if we can drastically decrease our susceptibility to it, which can be possible in future. And we could also try not prescribe mediations that we know are harmful in terms of causing Cdiff. This information could really help many people that need to take antibiotics and also people who already have Cdiff.–diff/

Some other links to check out:

Clostridium Difficile Infection: What Nurses Need to Know


New Deadly Virus Discoved in Africa

Recently an article was released summarizing the discovery of a new disease in Africa. In 2009 a fifteen year old boy in a small village in the Democratic Republic of the Congo fell ill. The initial symptoms were malaise and a bloody nose, but quickly the boy developed an acute hemorrhagic fever. Within two days of the showing symptoms the boy died. Approximately eleven days later a thirteen year old girl who went to the same school as Patient One developed similar symptoms, and died three days later. At the local health center which both Patients One and Two visited, a thirty-two year old male nurse began to experience identical symptoms. He was moved to the hospital in Boma, Democratic Republic of the Congo, where the doctors drew blood and began to test for known viruses; they found nothing. However, very recently a research team used deep sequencing to determine the pathogen,which they dubbed “Bas-Congo Virus”, and posted their results in the Public Library of Science Journal. It was discovered that the virus belonged to the Rhabdoviridae family, best known for the Rabies virus. Interestingly enough, though, the Bas-Congo virus only shares 34% of the amino acids found in other Rhabdoviruses, meaning that it is very different. The discovery of this virus may end up being of great importance due to the possibility that the virus may return. In any case, we will have one less pathogen on this planet to identity lest there be another, more deadly, outbreak.

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