New Discovery Explains Vampire Bats' Thirst for Blood

An article by Scientific American explains that a new study done by scientists in Germany have developed a possible explanation as to why vampire bats drink blood. Vampire bats are an interesting subset of bats because they only feed on blood, primarily mammals. While the species thrives on livestock blood, in other species, it is considered a poor diet. 

Blood, in general, is not rich in many nutrients because it does not contain any fat or carbohydrates, and contains little calories. In order to get enough nutrients to stay alive, the bats must drink 1.4 times their body weight during a single feeding, which is 1.68 oz of blood. These levels of blood are considered dangerous because the iron levels are so high, and can be dangerous to the digestive system. Scientists wanted an answer as to how these bats only live off of blood, and if genetics possibly play a role.

Michael Hiller and his colleagues at the LOEWE Center for Translational Biodiversity Genomics in Frankfurt, Germany used vampire bat genomes to study for any possible genes (or lack thereof) to provide an explanation into this phenomenon. It turns out it is the lack of certain genes that account for their ability to only consume blood. Hiller mentions that typically, seeing a deletion or mutation in genes are areas for concern, but in this case, it is actually beneficial. 13 "key" genes have been lost and range in functions, that altogether, create the perfect recipe for the vampire bats to keep thriving on their blood diet.

The loss of two genes specifically, REP15 and CYP39A1, aid significantly in keep the bats alive and healthy. REP15 is a gene that used to help keep iron out of the bats' stomachs and transfer it into their bloodstream. With that no longer a role in the vampire bats, the iron is able to move into the intestines. However, the researchers found that this might be a good thing, as the digestive cells have a small lifespan, so they can be continually shed and replaced to help excrete the iron-rich droppings instead of allowing it to absorb in the bloodstream. CYP39A1 is another helpful loss, as it used to degrade a by-product of cholesterol digestion. This gene deletion causes the metabolite to increase heavily, and other research in rodents has shown a correlation of increased levels of the metabolite and sociability and better memory, which helps the vampire bats. All in all, this genetic research provides an answer into why this species is able to thrive on something that is not considered a nutritious food.

This article really interested me because I was not very familiar with vampire bats. I was unaware that they only drink blood and I also had no idea about the lack of nutrition that comes with consuming blood. However, the scientists' research looking into what could be responsible for allowing the bats to consume the blood was fascinating. I would have never thought that it was actually the loss of genes that helped the bats thrive over the generations. This is a very unique species with a special diet that if any other animal were to eat solely, they would die. It is interesting that genetics (or lack of) plays a crucial role in the evolution of vampire bats.

Related Articles:

Inside the Vampire Bat Diet

Additional Research Into the Loss of Genes for Vampire Bats

Missing Genes and Autism

          Written in the article “Missing Genes May Be Tied to Development of Autism: Study,” a recent study conducted by researchers at the Mount Sinai School of Medicine in New York discovered gene deletions may be related to the development of autism.  More specifically, people with autism seem to have more gene deletions than people who don’t have autism.  Autism is a disorder marked by the impairment in social interaction and communication.  For those that don’t know, gene deletions are mutations that cause one and possibly more nucleotides to be removed from a DNA sequence.  Therefore, this can result in entire genes being deleted.  Leading researcher Joseph Buxbaum said that the gene deletions can possibly increase the risk of developing autism.  Also, he stated that the deletions may be responsible for the miswiring and changed activity of neurons in the brain.  In the study, Joseph Buxbaum and his associates analyzed the genes of 431 people with autism and 379 people without autism.  At the conclusion of the study, they discovered that there were 803 gene deletions in the group with autism and only 583 gene deletions in the group without autism.  The group without autism served as the control group of the study. 

From this study, the researchers also discovered those with autism probably have multiple gene deletions as well as the gene deletions being linked to autophagy.  Autophagy is a process that results in the destruction of worn out or damaged organelles in a cell.  This helps maintain homeostasis within the cell.  Buxbaum stated that during brain development, the brain produces too many synapses than it actually needs and so the extra synapses have to be removed.  However since the gene deletions can affect autophagy, the neurons end up having too many or too few synapses and this results in communication not working very well.  A final discovery from this study was that the gene deletions that occur within a person with autism are not likely from genetic inheritance.  Buxbaum said that some of the gene deletions seen in autism occur in the development of the egg or sperm.  Joseph Buxbaum and his associates continue to research with the hopes of further understanding this disorder.

I learned about autism in my abnormal psychology class last year.  Autism is a tragic disorder that is characterized by little social reciprocal interactions, very rare communicative eye contact, and generally seeming unaware of others.  The onset of autism is by the age of 3.  Also, people with autism have a narrow range of interests and activities and perform stereotypic movements such as hand flapping and rocking.  This recent article provides hope and a step in the right direction of understanding autism.  Hopefully one day, we will fully understand autism and possibly figure out how to prevent it or even cure it.  

Deletion of One Gene Causes Sex Reversal

Researchers from the Institute of Molecular Biology (IMB) in Mainz have discovered a gene that initiates the development of male sex organs. The researchers' finding uncovers a signaling device, which acts early in development to determine the gonads in males. This discovery sheds light on the genetic network that controls how embryos develop as males or females.

 

When testing on mice the researhers found that the deletion of one gene, Gadd45g, made the male's external genitalia match that of females. Then when they looked at the internal reproductive organs the male's also looked identical to the females. So the deletion of this one gene, Gadd45g, caused a complete sex reversal in the male mice. Christof Niehrs, Director Professor at IMB, said, "when breeding Gadd45g mutant mice we were puzzled why we got only females, until we discovered that some of these females actually carry a Y-chromosome." The scientist furthered showed that the Gadd45g gene controls the Sry gene by signaling it to work or not. The Sry gene is the know master regualtor of male sex expression. They think the Gadd45g gene regulates Sry by binding to p38, a key signaling protien, and activating the transcription factor Gata4. Once active, this factor binds to the Sry gene and ultimately turns it on. "This study both identifies a new role for Gadd45g and suggests a novel signaling pathway that could have important implications for research into disorders of sexual development."-Medical News Today.

I think this article is interesting because it shows how perfect DNA copying has to be, becuase the deletion of just one gene could have a huge effect. It makes me wonder if the scientist's discovery could be applied to human sex determination though. I do think it's cool that their discovery also shows how narrow the timeframe is in an embryo for sex organs to develop correctly.