BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: roundworms

Did You Inherit Stress From Your Mother?

Have you ever wondered why you are so stressed? Maybe because of school, sports, or homework, but have you ever thought you could have inherited from your mother? I bet not. Biologists at the University of Iowa found that roundworm mothers subjected to heat stress passed the stress exposure to their offspring and their offspring’s children. 

C elegans maleStress2a

In a study last year researchers looked at how mother roundworms react when she senses danger, such as a change in temperature. Their results were that the mother ringworms release serotonin when she senses dangers by traveling from her nervous system to warn her unfertilized eggs.  The warning is there “stored”, and then passed to offspring. Genes have “memories” of past environmental conditions that affect their expression even after these conditions have changed. It is still unclear how this “memory” is established, how it persists past fertilization and after the embryo develops into adults because most organisms typically reset any changes that have been made to genes’ past activity. 

The research team turned to the roundworm, a creature regularly studied by scientists, for clues. They exposed mother roundworms to unexpected stresses and found the stress memory was ingrained in the mother’s eggs through the actions of a protein called the heat shock transcription factor, or HSF1. The HSF1 protein is present in all plants and animals and is activated by changes in temperature, salinity, and other stressors. Although protein can be found in both Prokaryotic and Eukaryotic cells, this particular protein is only found in Eukaryotic cells which means that it interacts with numerous things found in these types of cells. HSF1 interacts with mRNA processing, chromatin modification, transcriptional coactivators and corepressors, and DNA and RNA metabolism which are all an array of proteins with diverse cellular functions. As we learned in biology, proteins nearly have every task of cellular life, including receiving signals from outside of the cell and mobilizing intracellular response which explains why the HSF1 protein has many functions.

The team found that HSF1 recruits another protein, an enzyme called a histone 3 lysine 9 (H3K9) methyltransferase. This normally acts during embryogenesis to silence genes and erase the memory of their prior activity. However, the research team observed something else entirely. They found that HSF1 collaborates with the mechanisms that normally act to ‘reset’ the memory of gene expression during embryogenesis to, instead, establish this stress memory. One of these newly silenced genes encodes the insulin receptor, which is central to metabolic changes with diabetes in humans, and which, when silenced, alters an animal’s physiology, metabolism, and stress resilience. Because these silencing marks were found in offspring, their stress-response strategy was switched from one that depended on the ability to be highly responsive to stress, to relying instead on mechanisms that decreased stress responsiveness but provided long-term protection from stressful environments.

What the team concluded was that if the mother was exposed to stress for a short period of time, only its offspring would be subjected to stress in utero, but the offspring’s children would not. If the mothers were exposed to stress for a longer period of time, then the offsprings children would retain this “memory” of  stress.

 

“What Does Light Taste Like?” I Don’t Know, Ask A Nematode.

csiro_scienceimage_2818_group_of_nematodes

by Entomology on scienceimage.csiro.au

The vision of light is a beautiful blessing brought to us by our sight receptor cells. Since the sight of light is so great, the taste of it must be even better. Though we don’t know the taste of light, there may be a very tiny someone who does, the nematode. In the article Tasting Light: New type of photoreceptor is 50 times more efficient than the human eye, published on sciencedaily.com, it states that, at the University of Michigan, researchers have discovered a new photoreceptor amidst a bunch of taste receptor cells in nematodes and other invertebrates. This new receptor is called, LITE-1. Because of the receptor’s unusual location, it is believed that these animals have an ability to taste light. New studies have also shown that LITE-1 is no average photoreceptor.

LITR-1 was discovered in nematodes, which are eyeless roundworms only measuring about a millimeter in length. You might be thinking, “Nematodes don’t have eyes. So why would they need photoreceptors?” Shawn Xu, a senior study author who has a lab at University of Michigan Life Sciences Institute, where he is also a faculty member, demonstrated in his lab that even though nematodes are  eyeless, they still move away from flashes of light. The purpose of photoreceptors is to transform light into a signal that is usable for the body. This fact leads scientists to believe that it’s possible for that the roundworm uses this photoreceptor, located among its taste receptors, so that it can convert light into something that the worm can taste in order to perceive it. Xu also says that “LITE-1 actually comes from a family of taste receptor proteins first discovered in insects.”

Though these nematodes are extremely tiny, their peculiar LITE-1 photoreceptors are nothing to be looked over. Something that makes LITE-1 strange is that it has the astounding ability to absorb UVA and UVB light. Another unusual trait of LITE-1 is that it is unlike other photoreceptor proteins. Photoreceptors consist of two parts: a base protein and a chromophore. Breaking these two sections apart does not destroy all of their ability to function. However, LITE-1, when broken apart loses its ability to absorb light entirely.

LITE-1 also has a range possible future uses, such as being applied as a sunscreen that can absorb harmful rays or being used to promote the development light sensitivity in new types of cells. The future of LITE-1 shows great promise  and could open doors for the potential of other animals, besides invertebrates, to have a new and possibly delicious way of sensing light.

 

http://www.cell.com/cell/abstract/S0092-8674(16)31518-5

http://www.natureworldnews.com/articles/32317/20161119/animals-taste-light-new-type-photoreceptor-found-invertebrates.htm

 

 

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