AP Biology class blog for discussing current research in Biology

Author: charwintheory

Why Do We Have Five Fingers?

Have you ever wondered why we have five fingers? Why not four or six? Researchers at the University of Montreal have recently made a discovery that brings us closer to answering these questions.


This summer, researchers found that the two genes, hoxa13 and hoxd13, that are responsible for the formation of fingers in humans are also responsible for the formation of fin rays, the bonny parts of a fin that resemble webbed fingers, in fish. This exciting discovery demonstrates the evolutionary link between fins and fingers. It has been established that the limbs of vertebrates have evolved from fish fins, but now we have a direct genetic link between fish fins and human fingers to prove the connection.


While this discovery filled in an important gap, there were still unanswered questions. Fossils indicate that our ancestors had more than five fingers, so how did humans evolve to only have five?

Using this new information, a research team from the University of Montreal discovered that during development, the hoxa11 and hoxa13 genes are activated together in overlapping domains in order to develop fins. Conversely, in human development, these genes are activated in separate domains, forming individual fingers. Following this discovery, the researchers performed an experiment on mice, in which they activated the hoxa11 and hoxa13 genes in overlapping domains, similar to the process that takes place in fish. As a result, the mice developed either six or seven fingers per paw, illustrating that the evolution of our hands did not occur from the acquisition of new genes, but the modification of how they are expressed.


While this discovery helps us move closer to figuring out the history and process of our evolution, it also helps us understand how mutations form. These findings further explain how malformations during fetal development occur not just from genetic mutations, but also mutations in regulatory sequences.

Possible Links Between Gut Microbes and Obesity, Cancer & Autism

While the bacteria in our gut play a vital role in the digestion process, recent findings have suggested that it could effect much more in our bodies. New studies have found possible links between the bacteria in our gut and obesity, cancer and autism.

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A study done by Cornell University and King’s College London revealed that Christensenellaceae minuta, a strain of gut bacteria, was found more often and in larger quantities in people with lower body masses. To investigate whether the bacteria is actually linked with obesity, researchers added the same bacteria into the guts of mice and compared their weight gain to mice lacking the bacteria. The research showed that the mice with Christensenellaceae minuta gained noticeably less weight than the mice lacking the bacteria. While research is still in its early stages, these results have made an exciting connection between bacteria in our gut and weight gain, which could dramatically impact the future of our health.

In addition to obesity, the bacteria in our gut has also been linked to cancer- in both beneficial and detrimental aspects. Researchers from the National Cancer Institute tested the effect of gut bacteria on chemotherapy in mice and found that the chemotherapy was significantly less effective in the mice lacking the bacteria. Similarly, another study found that cyclophosphamide, an antitumor drug, was less effective in mice with insufficient gut bacteria compared to those with normal levels. While these studies showed positive links between gut bacteria and cancer, other studies have found adverse effects of gut bacteria.

Unfortunately, a study published in The Journal of Cancer Research in 2012 has made a possible connection between Lactobacillus johnsonii, a strain of gut bacteria, and lymphoma, cancer of the white blood cells. The study claims that the presence of this specific strain of bacteria could lead to the development of lymphoma. Another study done in the UK in 2013 found that a specific gut bacterium, Helicobacter pylori, has the ability to deactivate the part of our immune system responsible for regulating inflammation. In effect, this could cause stomach cancer and ulcers.

While it may seem like a stretch, numerous studies have found a possible link to autism and the bacteria in our gut. A study done in 2013 by Arizona State University found that compared to children without autism, children suffering from autism had lower levels of Prevotella, Coprococcus and Veillonellaceae, three strains of gut bacteria. Even more surprisingly, another study revealed that the presence of Bacteroides fragilis in the gut reduced autism-like symptoms in mice. Research in this field is still in its primary stages, as researchers are trying to figure out if these connection are in fact related, and if so, how the bacteria directly effects these conditions.


Could drinking milk reverse the effects of Alzheimer’s?

While it may seem like a stretch, researchers have recently discovered a link between probiotics, or good bacteria, in our intestinal tracts and neurological function. A study done at Kashan University of Medical Sciences and Azad University in Iran has revealed that probiotics can improve cognition in those suffering with Alzheimer’s.

Many studies done in the past have shown that probiotics in mice have resulted in improved memory and learning as well as reduced depression, anxiety and OCD- related behaviors. These surprising findings have led scientists to be curious about weather or not humans would benefit in the same ways. Prior to this most recent study however, no research has been done on the effects of probiotics in human brains.


52 men and women between 60 and 95 years old with Alzheimer’s participated in this groundbreaking study. Half of the participants were randomly chosen to receive 200 ml of milk enriched with probiotic bacteria, while the other half were given untreated milk daily for 12 weeks. Prior to beginning the study, participants and were given a questionnaire testing cognitive function, which included tasks like repeating a phrase, giving the current date and naming objects. While these may seem like simple tasks to us, patients suffering with Alzheimer’s have great difficulty completing such actions.


Over the course of the 12-week study, the participants were repeatedly given the same questionnaire. The scores of the group who received the enriched milk increase significantly, averaging from an initial 8.7 increasing to 10.6 out of 30, while the scores of the group that received the un-enriched milk mostly remained the same or decreased.


While this area of research is still in its primary stages, the findings of this study helped us discover an important connection between the gastrointestinal tract and neurological function, as well as how probiotics have a direct effect on cognition. Researchers have hope that further study can reveal more about the affects of probiotic on Alzheimer’s and other neurological conditions.

Our Appetite Uncovered

Researchers in Korea have just taken a major step in the journey towards understanding the patterns of our eating behavior. Scientists at the Daegu Gyeongbuk Institute of Science and Technology have recently discovered the dynamics of the enzyme in our brains that controls our appetite.


Previous research has uncovered that the hypothalamus region in our brain detects levels of glucose and hormones in our blood in order to manage our food intake. To extend these findings, the recent research done in Korea has shown that having low amounts of glucose in the bloodstream activates an enzyme, called adenosine monophosphate-activated protein kinase (AMPK). This enzyme alters the properties of neuropeptides, small protein molecules used by neurons to communicate with each other, using autophagy.

Copyright Nevit Dilmen

Credit Nevit Dilmen

How it Works

When decreased amounts of glucose in the bloodstream are detected, AMPK is stimulated, which diminished the levels of two neurohormones in the brain, neuropeptide Y (NPY) and pro-opiomelanocortin-alpha (POMC). The levels of NPY and POMC are reduced by the process of autophagy, the natural self-destruction mechanism in the body. Decreased amounts of NPY and POMC have been strongly linked to an increase in food intake and obesity.


Research Methods

In orders to trace the complex pathways between the brain and the body to come to these conclusions, researchers conducted experiments using cell lines in vitro and mice. Using the cell lines, researchers were able to record the presence of autophagy under different levels of glucose and activated certain pathways to find the links between the brain and the body. In the mice, researchers injected a virus that eliminated AMPK in the mice’s brains. As a result, the mice ate significantly less than others not injected with the virus.


Combining the results from the cell and mice experiments confirmed that AMPK altered the levels of NPY and POMC, therefore affecting one’s appetite. While these findings are preliminary, they are a significant step in the direction towards completely understanding our eating behavior and may one day lead to solving the obesity epidemic we face today.


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