AP Biology class blog for discussing current research in Biology

Author: cellstine

Climate Concerns and Rising Sea Levels: Antarctic Edition

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   Climate change has been a recent concern as it affects all aspects of human life. More evidence to climate change and the rise of sea levels was expressed in a very recent study conducted by IMAS PhD student: Alessandro Silvano. By doing so, he ultimately found that this process quickens the rate that ice melts and sea levels rise.

The study was conducted using ocean measurements off the coast of east Antartica. The study showed that glaciers are freshening the ocean, as the glaciers do not consist of salt. This dilutes the natural salt content of the ocean. He found that the melted water from the glaciers causes the ocean’s surface layer less salty and more buoyant, which prevented deep mixing during the winter months. Therefore it allowed warm water to retain its heat and melt glaciers from below. This process allowed the water to exist in layers, similar to when one attempts to mix oil and water. The study found a positive feedback mechanism, in which glacial melt water caused further melting of ice shelves, leading to an increase in sea level.

In some areas around Antartica, the study also found fresh meltwater decreased the formation and sinking of dense water. This results in decreasing the rate of ocean circulation, which stores heat and carbon dioxide. Because the cold glacial melt waters cause a slowing of the currents, which then decrease the ocean’s ability to decrease carbon dioxide and heat from the atmosphere. These two processes feed off of each other and induce and speed up climate change.

I enjoyed reading this article because I am personally passionate about decreasing the rate of climate change and educating myself on global warming. Backing global climate change due to its concerning effect – only one of which is sea level – with scientific evidence is important for gaining support of our communities.

Secondary Source Article: The Washington Post: One of the most worrisome predictions about climate change may be coming true

CRISPR, A Cure to Heart Disease?

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     While CRISPR‘s full potential in the department of gene editing is still being researched, scientists have just successfully discovered CRISPR’s ability to correct a defective gene that causes a certain type of heart disease. Though scientists are unclear as to the type of gene corrected in order to cause this change, this discovery was made for the first time in the United States, by an experiment done on live human embryos. However the new information yielded from this experiment is extremely beneficial as it shows CRISPR’s potential in correcting genetic errors that cause disease, as well as in human embryos meant for pregnancy.

Another reason for which this study particularly stands out in its importance, is because it is much different from the other developments scientists have made in CRISPR’s abilities. Studies have been conducted worldwide using CRISPR to edit of somatic cell’s gnomes, however, this only affects individual people. This study (also done by researchers in China), has been done by editing germ line cells, which result in changes that are passed down through every following generation.

However since the changes made to cells do affect all generations that follow, scientists are unsure of the exact effects of this new technique. Although it seems that this technology will be very beneficial in stopping harmful genetic diseases, it can also be used for changing DNA to genetically determine the eye colors, height or even mental and physical abilities and intelligence. This new phenomenon is own as “designer babies”, and for many reasons, this is not something that the United States is trying to use CRISPR’s abilities for. For this reason, United States has recently created more severe guidelines regarding gene editing technology, as well as enforcing CRISPR’s use on embryos only for prevention of harmful genetic diseases, when other treatments were not successful – as a last resort – formed by the National Academies of Sciences, Engineering and Medicine.

In the study done, scientists edited out a mutant copy of MYBPC3, using CRISPR. MYBPC3 is a gene that encodes a protein that creates well maintained and structured heart muscles. Hypertrophic cardiomyopathy, known as HCM, are caused by mutations in that gene, and cause spontaneous cardiac arrest. This occurs in even the youngest and healthiest of athletes, affecting 1 in 500 humans.

In this study, the mother was carrying the normal version of a gene, while the father had the mutant gene. Using CRISPR, the scientists were able fix the mutant version, by cutting and replacing the DNA. Directly after they placed the fertilized egg in a petri dish, while introducing the genome editing parts at the same time. The results of this process proved to be very effective, as 75% of the embryos showed no mutant genome. Without the use of CRISPR when egg fertilization occurred, the chances of mutation would have been present in 50%!

From these results the researchers came to the conclusion that they have realized the potential for mosaicism. Mosaicism is when only some of the cells are edited and the rest are not affected, which results in some normal cells, as well as some mutant cells. The scientists have also gathered the effects of off-targets. Off targets are the CRISPR edited genes that appear to look like mutant genes, but are actually not. Within this study, one egg fertilized from 58 showed mosaicism, and there was no detection of effects from off-targets. Theseare very impressive results, due to the fact that both of these possible situations can cause limitations in effectiveness and safety.

Though researchers need to do over this experiment many times in order to soliditfy the effectiveness of this study for the future, if they want to use this on eggs intended for pregnancy, as the eggs fertilized in the study were not meant for pregnancy… However, the results have yielded nothing but good news for the future of CRISPR technology (besides, the risk in advancements in “designer babies”, which couldchange the future of conceiving, forever…). This article was extremely interesting for me to read, as I am very interested in studying Biology in the future, or even pursuing a track to medicine. Perhaps, I may get the chance to even experiment with CRISPR at some time in my life, as it becomes a growing presence throughout the science world!

Primary Source Article: U.S. researchershave used gene editing to combat heart disease in human embryos

Bacteria Not So “Bad”, After All?

Photo Link: Wild Garden of Gut Bacteria, By: Nicola Fawcett

Most of us are used to the common notion that bacteria may not be the most beneficial factor in maintaining your health.  Thats why the results of a recent research study conducted by scientists at Babraham Institute in collaboration with colleagues in Brazil and Italy, yielding evidence that in fact good bacteria in the gut can control gene expression in our cells, is game-changing!

The research team, led by Patrick Varga-Weisz, made this discovery by studying the gut bacterias found within various mice. Their attention was quickly drawn to the mice that had lost most of their gut bacteria. It became apparent that in the mice with a very low amount of the bacteria within their gut, contained increased amounts of the “HDAC2 protein”.  When investigating deeper into HDAC2, it was found that increased amounts of this particular protein are associated with increased risk of colorectal cancer.

This new research also resulted in the finding that the amount of chemical markers on our genes, are increased by short fatty acids. These specific chemical gene markers, known as “crotonylations”, were only recently discovered and are newly classified as genome “epigenetic markers”. The researchers then found that by shutting down the HDAC2 protein, short chain fatty acids increase the number of crotonylations.

Ingestion of fruits and vegetables into ones healthy diet are vital – ultimately determining how chemicals produced by gut bacteria, affect genes in the cells of the gut lining. In other words, the short fatty acids, which come from those dietary elements, have the ability to move from bacteria into our own cells, and from there cause changes in gene activity and cell behavior.

In the end, the scientists were strongly convinced that the ability to turn off and on genes, is determined by changes in crotonylation. This inferred that the existence of crotonylation in the genome of cells is vital to protect the body from cancer. Therefore, the pretense of good bacteria is very important for the prevention of disease and illness in the body!

As someone with a strong passion for the science, and also very influenced and intrigued by medicine, I very much enjoyed this study. As the boundary to curing cancer is still a hurtle doctors and scientists try to transcend everyday, studies like these, are both hopeful and fascinating, to me. Also, as someone curious about how the human diet ultimately affects the functions and inner workings of the body, this research again was very engaging and interesting!

Primary Source Article: How good bacteria controls your genes

Secondary Source: Wikipedia – Gut Flora (Gut Bacterias)


Humans and Our Fellow Fishy Friends – More Alike than We Suppose?

The origin of teeth in vertebrates, therefore including in humans, has been long wondered and debated. Scientists have questioned whether teeth descended as part of the origin of the jaw, or if they had their own unique formation. More clarification has just been released to this mysterious question of our anatomy, with new recent data leading scientists to believe that teeth in the animal kingdom evolved from the scales of ancient fish, due to the shared characteristic of neural crest cells. The scales are still present today, covering the bodies of fish such as sharks, skate and rays.

The specific linage of sea life possessing skeletons fully made of cartilage consists of sharks, rays and skates. These fish still have primitive characteristics, such as “dermal denticles”, which are embedded into their skin. Dermal denticles share an extremely similar appearance of jagged teeth, as they are small sharp scales.

Recently, research scientists at the University of Cambridge tracked the cell development in the embryo of a the cartilaginous skate fish, using have used fluorescent markers. Through this method, they uncovered the new linking piece of information: the thorny scales are created from “neural crest cells”, the same type of cells that make up vertebrate teeth! This information provides further support to the theory that evolution of jawed teeth found currently in the mouths 99% of sea and mammal vertebrates, evolved from the scales of these fish.

Though the scales found on fish currently appear very different from teeth, the scales of ancient fish were much more similar to the tooth like structure of today. The reason for this, in the words of Dr. Andrew Gillis from Cambridge’s Department of Zoology and the Marine Biological Laboratory in Woods Hole, is that the scales of most fish that live today, like the cartilaginous fishes of skate and shark, have only retained some lineages to the primitive scales. Researchers at Cambridge hypothesize that amour plates consisted of many different layers of foundation of bone, an outer layer of dentine and cells in unborn embryos. They propose that this composition underwent many reductions and modifications. Shark’s scales do however further support this theory, as the dermal denticles they are covered in, give them a much rougher feel, than other fish. It is very possible that this also is because the denticles found on these fishes are remnants of superficial amour plating, of the early ancient skeletons of vertebrates.

This article and data finding was very thought provoking to me. I was not aware that of the uncertainty of the origin of teeth, in the world of science. Also because I am extremely interested in evolution and the origination of our species, this finding specifically intrigued me, as this data may be useful for new advances in evolutionary theories. It is fascinating to me consider the possibility of such a key part of vertebrates, specifically of humans, being so closely linked to fish, as that is a species of animal than I have ever considered having ties to human descent before. I think this data is a gateway to future discoveries that will be beneficial to the science world.

(Be sure to check out the second secondary source article linked below, as it discusses even more data on specially teeth enamel evolving from fish scales!)

Primary Source – Original Article: Ancient fish scales and vertebrate teeth share an embryonic origin

Secondary Source Article: Fish scales to fangs: Surprising tale of how teeth got their bite

Secondary Source Article: Your Tooth Enamel Might Have Started As Fish Scales

Photo Article Link (Photo taken by: Albert Kok)

The Mysterious Linkage between Antidepressants & Weight Loss


Humans are constantly debating the extent of which we can control our belly fat. Common lifestyle trends include implementing more exercise, cutting foods or using supplements, as various ways in order to increase weight loss. As the risks and growing concerns associated with obesity increase, the answers to these questions become more significant to the fate of our health.

A new study yields data suggesting that weight is caused by immune cell inflammation, and there may be an unexpected cure. In a study of macrophages in belly fat, conducted by Yale school of medicine, it was discovered that these immune cells responsible for tracking and engulfing pathogens, may become inflamed with aging. To further test this finding, they separated young and old mice into two groups, and isolated their macrophages from their fat tissue. In proceeding to sequence the DNA of both groups of these cells, it was found that the genomes of the older mice macrophages showed more genes that lessen catecholamines. Catecholamines are a group of molecules that distribute signals across nerve cells. This is possible because of the blockage of neurotransmitters, caused by the genes that turn on enzymes. Therefore, the increased activation of these in the older group of immune cells, blocks messages that tell the body that fat is present and available for use, resulting in energy.

     So, what is the cure?

Evidence shows that the known antidepressant: Clorgyline, is commonly given for depressive symptoms and low catecholamine levels. When this drug was given to the mice, the older mice could successfully start-up belly fat burning again, as it blocked the enzyme found in older immune cells.

This study demonstrates that it is possible to decrease inflammation and change fat metabolism of animals by way of Clorgyline. Side-effects of both appetite decrease and increase have been recorded to have affected humans. But I believe it is still hopeful with more research similar results to that of the mice, can be attained in humans. 

I was interested in this article, because psychiatric disorders such as anxiety and depression are prevalent across all populations, including adolescents and adults. Common side effects of many of the drugs used to treat these disorders, include weight gain. It seems that weight gain could directly worsen these disorders, counteracting the positive effects of the medications. For this reason, the findings presented from this study seemed like a positive advance in science.

How do you think the findings of this study will effect future future depression medication research? Does it seem likely that results similar to the mice will occur in humans?

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Primary Source Article: Common antidepressant found to reduce belly fat in older mice 

Secondary Source Article: Treatment with the MAO-A inhibitor clorgyline elevates monoamine neurotransmitter levels and improves affective phenotypes in a mouse model of Huntington disease

Secondary Source Article: Effects of the monoamine oxidase inhibitors clorgyline and pargyline on the hyperphagia of obese mice.


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