2016/11/22

Researchers map diet induced epigenetic inheritability

Researchers map diet induced epigenetic inheritability 


Excerpt: "A fundamental law of genetics states that progenies do not inherit epigenetically-based adaptive, pathological or neural features acquired in response to environmental conditions. However, recent studies seem to contradict this dogma.Now, two new studies in mice from University of Massachusetts and Beijing University, respectively, demonstrate how a father’s diet affects levels of specific small RNAs in his sperm, which in turn can affect gene regulation in offspring. The researchers state that these results add to the growing list of ways in which a male’s lifestyle can influence his offspring, including through the sperm epigenome, microbiome transfer and seminal fluid signalling.
The group state that their findings suggest that RNAs from sperm of HFD males contain the information to induce glucose intolerance, but not insulin resistance. Further investigation identified tRNAs fragments, containing about 30-34 nucleotides, as the class of small RNA that caused the glucose intolerance observed in HFD offspring. Results show that a genome-wide comparison between ND and HFD offspring found significantly less expression of genes involved with ketone, carbohydrate, and monosaccharide metabolism in the HFD group.
In the second study, a team of researchers from the University of Massachusetts tested whether the sperm of mice on a low protein (LP) diet experienced any changes in RNA levels. Results show that small RNAs from immature sperm in the testis did not correlate with dietary effects; yet, sequencing of small RNA in mature sperm in the epididymus revealed great expression of certain RNAs. The lab then isolated RNA in sperm from LP mice and controls, finding particularly high levels of a RNA, tRNA-Gly-GCC, in the LP group. Data findings show that tRNA-Gly-GCC suppresses a subset of genes, including a gene that contributes to the plasticity of mouse embryonic stem cells.
The researchers surmise that although tRNAs are best known for roles in protein synthesis, their fragments are turning up in other cellular situations.  They go on to add that both studies suggest that the RNA bits alter gene activity with the UMass team blocking one of the tRNA fragments inside embryonic stem cells to increase the activity of about 70 genes.  For the future, the groups state that they to investigate how permanent these changes are and how quickly they can be reversed by changing diet. They go on to conclude that the effects of the RNA fragments don’t have to be harmful and state that if a bad diet can influence a person, a healthy diet can do it in the same way."
My comment: These studies demonstrate how RNA in sperm can be affected by diet, and that this can cause changes in gene regulation of offspring. Several other studies have recently reported also that organisms are able to inherit some acquired traits through sperm RNAs:
http://qichen-lab.info/assets/2016_NRG_Chen_et.al.pdf
http://phys.org/news/2016-10-biologists-inheritance-gene-silencing-rna.html

Diet is the most significant factor causing alterations to organisms. But there are other energy associated factors 
such as climate, stress etc. affecting the epitranscriptome.   Random mutations are not the reason for rich and rapidly changing biodiversity. Changes and variation are based on designed and created mechanisms. Modern scientists understand this fact. Mechanisms for ecological adaptation and variation are soon well known. Large scale evolution has no mechanism. The evolutionary theory is a major lie.