AP Biology class blog for discussing current research in Biology

Author: brookioles

Blame your Parents for your Stress?

Epigenetics is the study of inheritable changes in gene expression not directly coded in our DNA. Scientists at Tel Aviv University have shown that stress, induced by traumatic events, can be passed on to offspring. The study refers to this stress as passing on “memories.” The study finds the exact way that the inheritance of environmental influences is turned “on” and “off.” RNA sequences that regulate gene expression are partially responsible for deciding when the inheritance is on or off.

Scientists found that C.elegans worms only passed on inheritable epigenetic responses for a few generations (using small RNAs that target green fluorescent protein). This led them to believe that epigenetic responses die out eventually. However, this did not account for the possibility that inheritance could be regulated.  Scientists discovered that in order to create new small RNAs that allow a response to be passed on to multiple generations, they needed RdRP enzymes. These amplify heritable RNAs for generations. Certain genes that they called “MOTEK” (Modified Transgenerational Epigenetic Kinetics) were involved in turning on and off epigenetic transmissions. They switched on and off the small RNAs that the worms use to regulate genes using a feedback interaction between gene-regulating small RNAs and MOTEK. This determines whether an epigenetic memory will be passed on, and for how many generations.

Even though this study was done on worms, these scientists have said that these basics can possibly lead to discovery of inheritance for all organisms. This small bit of research can lead to endless amounts of knowledge for similar mechanisms in humans.

Overview of Epigenetics:

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T Regulatory Cells Help Maintain Plasma Cells

Researchers at the University of Pennsylvania School of Veterinary Medicine, in February 2017, have discovered a trend in T regulatory cells and plasma cells, that explain why these “antibody-producing plasma cells” can last so long. They used a special microscope that shows “movement and interaction” of cells.  They found that regulatory T cells in the bone marrow support plasma cells, which disappear without the T cells.  Plasma cells are involved in the immune system, and can either be vital or detrimental. To learn more about plasma cells click here.  Scientists hope to use this new knowledge of the interaction between regulatory T cells and plasma cells to either increase the amount of plasma cells to fight off a virus, for example, or to decrease the amount in order to stop it from creating a disease.  This research also explains why vaccines can last so long. For example, the chicken pox vaccine is only given twice when the person is very young, but they will be protected against the disease even when they are much older. The regulatory T cells support the plasma cells in the bone marrow which create antibodies that fight off viruses, etc. Another article that explains this discovery can be found here. An article that describes more uses of regulatory T cells in the immune system can be found here.

With this discovery, scientists have more power to control, and have more insight into how plasma cells can be sustained over long periods of time.

Here is an image of an antibody that plasma cells create.

The Human Gut Microbiome and Autism Spectrum Disorders

Researchers of the human gut microbiome have made connections to the autism spectrum disorder.  A gut microbiome involves the digestive tract microbes.  To learn more general information click here.  Studies tested DNA of children with gastrointestinal complaints.  Researches compared children with Autism Spectrum Disorder, and mainstream children.  It was found that children with Autism Spectrum Disorder had too many Clostridium or Desulfovibrio clusters.  To learn more about these gene clusters click here. Developing fever, receiving oral antibiotics, or ingesting probiotics are all likely to alter the gut microflora.  When children with Autism Spectrum Disorder do the above, they have exhibited improvement in their gastrointestinal pains; however, there hasn’t been scientific research, as it has only been found anecdotally. Research has been limited due to the difficult culture-dependent techniques; however, metagenomic technology could be used to discover and reduce the effects of the gut microbiome as a part in Autism Spectrum Disorder.

A longitudinal study completed in May 2016 shows more progress that scientists have made in discovering different aspects of autism in relation to the microbiome.  For two weeks, stool samples were collected from patients with autism and their siblings without autism in order to be compared. Sarcina ventriculi, Barnesiella intestihominis, and Clostridium bartlettii are organisms that are related to autism. They were found in the stool samples of children with autism, but not their siblings. Gastrointestinal symptoms were reported on days 6-8 of the study for children with Autism Spectrum Disorder, where Haemophilus parainfluenzae was detected at the onset. These patients also exhibited behavioral challenges during these days.

Though scientists have not found a diagnosis for Autism Spectrum Disorder yet, it is clear that the gut microbiome plays a role in the development. Further research that is not merely based off of a handful of patients needs to be completed to learn more.

Photo of Gut Flora

Obesity Related to the Brain

Lauri Nummenmaa has done research the connects obesity to the brain.  This research shows that people struggling with obesity have a lower amount of μ-opioid receptors available for binding in the brain.  (To learn more about μ-opioid receptors click here.)  Due to evolution, our brains are still “wired” to search for food and nutrients.  Since eating gives off a sensation in the brain, related to the opioid receptors, people with fewer receptors that are able to bind will therefore eat more to make up for the loss in sensation.  This reaction is the same as a reaction to an addiction would be, causing more neurotransmitters to be secreted.  The next step that scientists are taking is to discover whether being obese causes a lack in opioid receptors, or if a lack in opioid receptors, caused by another source, is what causes obesity.  One test that scientists did was testing μ-opioid receptors in people that had bariatric surgery.  Bariatric surgery causes more receptors to work again, shown by the fact that scientists could not distinguish between the μ-opioid receptors or healthy people and the μ-opioid receptors of people who had the surgery.

Some body fat, however, is helpful to the brain.  This article describes that “fat tissue in the bodies of mice releases an extracellular form of nicotinamide phosphoribosyltransferase (eNAMPT), an enzyme that travels to the hypothalamus, and gives animals energy during fasting.”  (To learn more about eNAMPT click here.)

This photo shows how a neurotransmitter is sent from neuron to neuron generally.


(Link to Photo Page and Link to Licensing Page)

How Mesh in a Cell Can Cause Cancer

Warwick Press Release In July 2015 researchers at the University of Warwick discovered, accidentally, how the structure of a cell can cause cancer development.  The mesh that holds microtubules together also assists the mitotic spindles (made of microtubules) in cell division.  To learn more about cell division click here.  Mitotic spindles are responsible for making sure new cells have a complete genome: the correct number of chromosomes.  To learn more about spindle structures click here.  It has been known that a cell with too many or too little chromosomes, called aneuploidy, can cause diseases, including cancer.  Mesh gives structural support to mitotic spindles.  Too little or too much support from the mesh causes mitotic spindles to be too weak or too strong (cannot correct mistakes).  The discovery of the mesh occurred when Warwick researchers looked at microtubule structures in a 3D shape and saw that the bridges that hold microtubules together were not “single struts,” but “web-like structures.”  The next step in this research is to determine if it is possible to prevent mesh from giving not the right amount of support.  Could medicine ensure that the mesh supports the mitotic spindles just enough so that a  shared number of chromosomes is guaranteed during cell division?

Kinetochores on chromosomes attach to spindle fiber during cell division

Kinetochores on chromosomes attach to spindle fiber during cell division

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