AP Biology class blog for discussing current research in Biology

Author: deoxywybose

Alien Earthworms Invade! North American Ecosystems are Threatened

The invasion of non-native earth worms poses a complex ecological threat to North America. Earthworms are an integral part of agriculture, aerating and letting water and other nutrients penetrate the soil with the underground tunnels made, and fertilizer from their waste products.  Earthworms also produce net decrease of CO2. As a result of the services earthworms provide, people looking to capitalize off of them have brought earthworms from all over the world to North America.

Lumbricus rubellus HC1

The non-native species have successfully enhanced the agricultural economy in some places, however there are other cases where the alien earthworms have dramatic impacts on ecosystems. The alien earthworms are more likely to consume above ground leaf litter which harms the plants, amphibians, and insects.  “Leaf litter provides many nutrients for the plants and animals” on the lower ends of the food chain, like primary and secondary consumers.  These earthworms can also change the microbiomes of the soil, which can cause serious harm to the plants in the area and indirectly affect other animals.  Microbiome changes appear in pH shifts, nutrients, and even texture, all leading to poorer plant quality and health.  Without the main players, producers, functioning at peak performance, the ecosystem can begin to waver.

To make things even worse, some female alien earthworms can reproduce without fertilization from a male. Faster reproduction, independent of males, contributes to better ecological fitness.  Different species of earthworms exhibit varying levels of fitness. This is not due to their gym habits, but rather because they have evolved to survive and reproduce more effectively than others. Additionally, as a byproduct of climate change, there is new inhabitable land ripe for the alien earthworms to dig their way into.

“Despite all this, only a limited number of studies have documented alien earthworms’ spread, and none have covered colonization dynamics over a large spatial scale or a large number of species.” A new database using records from 1891 to 2021 of native vs. alien earthworms, was used in tandem with another database of U.S. border interceptions of alien earthworms between 1945 and 1975. The new technology powered by ‘machine learning’ aimed at finding the non-native earthworm introduction and spread. Researchers have found that in Canada the alien earth worm population is three times greater than the native population, and in the US and Mexico there are 2 native earthworms for every non-native earth worm.

In AP Biology, we have explored ecology, including concepts such as trophic levels, food webs, and ecological fitness. Trophic levels and food webs directly related to the Alien earthworm threat because a dip in low trophic levels, especially producers, have catastrophic effects on the ecosystem of a certain place.  For context, a trophic level of an organism is the number of steps away from producers it is, ex a primary consumer in NYC are crickets because they only eat grass a producer, and a food web consists of all the food chains of an ecosystem.  An important thing to note with food webs and trophic levels is each trophic level only can gain ten percent of the energy of the last trophic level.  So, if an ecosystem lost significant plant growth or biomass, the trophic levels above it would have less energy and the population sizes of the organisms living in the ecosystem would shrink.  The harmful alien earthworms damage ecosystems by targeting plant mass and soil nutrients which gives each trophic level less energy, effectively shrinking the entire ecosystem.

This topic intrigued me because of how closely related it is to what I have been learning in class.  I also enjoyed learning and writing about how such a seemingly small change in an ecosystem can have impacts much larger than themselves.  I also find human impacts on ecosystems interesting to learn about.  I found this one to be especially interesting because of course something like the industrial revolution had huge long term impacts on the ecology of the world, but you wouldn’t immediately think something trivial like earthworms would have much of an impact on anything, or be so different from one another that they can change the pH of the soil!  What do you think: are alien earthworms worth paying attention to? Is there anything to do against the spread of these alien earthworms? Why does Canada have so many more alien worms than the United States and Mexico?



Breaking the Resistance: Texas A&M’s groundbreaking Polymers kill Antibiotic-Resistant Bacteria

As the threat of antibiotic-resistant bacteria becomes a bigger threat, the production of new antibiotics is necessary. The Texas A&M-led collaboration, consisting of many different scientists and organizations, is doing just that. The group has created a polymer capable of “killing bacteria without inducing antibiotic resistance by disrupting the membrane of these microorganisms.” The polymers work in a way that does not allow bacteria to resist. The polymer was made by designing “a positively charged molecule that can be stitched many times to form a large molecule made of the same repeating charged motif using a carefully selected catalyst called AquaMet.” The catalyst AquaMet is quite a feat, as it has to withstand high concentrations of charges and remain water-soluble. After synthesizing the polymer, the team began testing it on human red blood cells and antibiotic-resistant bacteria, such as E. coli. The Texas A&M-led group of scientists believes testing human blood cells is pertinent to their discoveries, as many current antibiotics cannot differentiate between the bacteria being targeted and other cells. This inability to differentiate bacteria from other cells is the cause of gut health issues as a result of antibiotics, which is why the scientific collaboration wishes to find a balance between controlling the harmful bacteria and attacking other cells.

Single Polymer Chains AFM

Image of a single polymer chain:

In AP Biology, I have learned about polymers and catalysts. Polymers, composed of multiple monomers linked by covalent bonds, are the foundational long-chain molecules in organic compounds. Monomers are the most basic structures in organic compounds. For example, the monomer for carbohydrates is a monosaccharide, and the polymers for carbohydrates are disaccharides and polysaccharides. Secondly, catalysts are any substances that speed up the rate of reactions. Organically, catalysts are found as enzymes. Usually, they work by lowering the amount of activation energy required for a specific reaction. AquaMet, which is the key to creating the polymer, is a catalyst. Having a foundational understanding of polymers and catalysts made the discussed article much more comprehensive, as the antibiotic in trial is an artificial polymer created using a specific catalyst. The topic discussed is very appealing to me because of how important it is. New antibiotics that work against antibiotic-resistant bacteria are incredibly important to human safety. The idea of sickness caused by bacteria without an antibiotic to help you is a scary one, and I am happy to learn of the antibiotic frontier! 

What do you think? What role does the Catalyst specifically play in creating the polymer? Do you think this will lead to large scale production and eventually be used to treat antibiotic resistant bacterial infections?

The cause of Asymptomatic COVID-19 cases: A Gene Mutation

Novel Coronavirus SARS-CoV-2 (50047466123)

What is the cause of asymptomatic COVID-19 cases?

The study led by researchers at University of California San Francisco, published in Nature on July 19, 2023, provides the first evidence of a genetic basis for asymptomatic SARS-CoV-2 infection.  Individuals who contract COVID-19 but remain symptom-free are more than twice as likely to carry a specific gene variation. The genetic mutation, HLA-B15:01, common in about 10% of the study’s population, doesn’t prevent virus infection but remarkably prevents the development of symptoms. The research identifies the HLA-B15:01 variant as a key factor in solving the mystery of asymptomatic COVID-19 cases, with 20% of asymptomatic individuals carrying it compared to 9% with symptoms. The study, focusing on unvaccinated donors, finds that risk factors for severe COVID-19 don’t play a role in asymptomatic cases. The HLA-B*15:01 gene’s ability to recognize and respond to COVID-19, facilitated by T-cell memory, suggests potential targets for drug and vaccine development. The collaboration with La Trobe University delves into the concept of T-cell memory, highlighting the immune system’s ability to recognize SARS-CoV-2 due to exposure to similar peptides in seasonal coronaviruses. The research opens avenues for promoting immune protection against SARS-CoV-2 in future vaccine or drug development.

Recently in AP Biology, my class learned about the intricate mechanisms of the immune system.  This research directly connects to our learning of the immune system, more specifically memory cells which are highlighted in the article as a key piece of how the HLA-B15:01 gene functions.  T memory cells are cells which are responsible for recognizing and responding to all previous infections.  As previously mentioned, La Trobe University found that the HLA-B15:01 gene recognizes COVID-19 because of its similarity and to the more common coronaviruses people are regularly exposed to.  Once recognized the immune system has the capability to attack it with T-killer cells and potentially create and secrete antibodies through macrophages and plasma cells.

Since March 2020 I have been curious to the reasoning behind asymptomatic cases and I am happy to find a potential answer to this long unanswered question.  Why do you think this research has taken almost three years to find the answer to.  Comparatively, the COVID-19 vaccine was made in around 8 months from March of 2020. Of course there was significantly more incentive and money invested into the development of the vaccine, however the two findings are years apart and the vaccine is seemingly much harder to research and develop.

New “Mini-Organ” Discovered in Cells: The Exclusome

Eukayotic Cell (430x maginification)

A “mini-organ” which protects the genome from attack and potentially gives a glimpse into the evolutionary past of the Nucleus.

Eukaryotic cells, or any cells with a nucleus, contain almost all of the cells DNA in the nucleus, however some of the cell’s DNA exists in the cytoplasm, the fluid-filled body.  Foreign DNA from viruses and bacteria can also enter the cell.  These floating bits of genetic material are trapped by the newly discovered mini organ in cells named the “exclusome”.

Scientists have found that exclusomes lack nuclear pore complexes (mediates transport of macromolecules from nucleus to cytoplasm), but feature a double membrane and proteins, just like the nucleus. Ruth Kroschewski from the Institute of Biochemistry at ETH Zurich notes that “the exclusome envelope features gaps that can be seen in the nuclear envelope only in the early stages of its formation.” Inside the exlcusome the genetic material that codes for telomeres is found. Telomeres are the ends of chromosomes that protects them from being destroyed or damaged.  This shows that the exclusome envelope is much simpler.  DNA being held outside of the Nucleus is a rare discovery as very few organelles carry DNA.  “Perhaps the exclusome is a first attempt at producing a cell nucleus,” Kroschewski says.  Through cell division, they stay in existing cells but do not enter new ones. This mechanism might be “an evolutionary relic of cellular machinery.”

In AP Biology this year we have learned about the compartmentalization of cells and how organelles function in the cell.  The mitochondria and chloroplasts remind me of the exclusome because the mitochondria and chloroplasts have their own DNA, although I doubt they follow the endosymbiont theory as the DNA the exclusomes store is used in the chromosomes.  The exclusomes are also similar to lysosomes we studied, as they clean up the old cell parts like how the exlclusomes clean up floating bits of potentially harmful genetic material.  The exclusomes are an interesting discovery to learn about the history in the creation on the nucleus and eukaryotic cells as a whole.  Also to learn that there are still mini organs or potentially organelles still being discovered makes me want to participate in the discoveries in the future. Do you think the exclusome is an organelle, or a mini-organ, or just a structure in the cell?  What else do you think can be learned about the history of cells from the exclusome?


Powered by WordPress & Theme by Anders Norén

Skip to toolbar