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Current Affairs

Role of viruses in survival of species

Date: 11 September 2020 Tags: Miscellaneous

Issue

New research shows viruses also play a key evolutionary role in mammals' ability to reproduce and survive.

 

Background

Scientists revealed two distinct and fundamental processes underlying germline transcriptomes. They also show that species-specific transcriptomes are fine-tuned by endogenous retroviruses in the mammalian germline.

 

Details

  • Germline transcriptomes include all the messenger RNA in germline cells, which contain either the male or female half of chromosomes passed on as inherited genetic material to offspring when species mate.

  • This means that germline transcriptomes define the unique character of sperm and egg to prepare for the next generation of life.

  • Scientists call them super-enhancers, which are robust and evolutionally conserved gene regulatory elements in the genome. They fuel a tightly regulated burst of essential germline genes as sperm start to form

  • Viruses, especially endogenous retroviruses (ERVs) that are an inherent part of mammalian biology, can dramatically influence gene expression. ERVs are molecular remnants of retroviruses that infect the body and over time incorporate into the genome.

  • The study combined biological testing of mouse models and human germline cells with computational biology, including genome-wide profiling of gene regulatory elements in germline cells.

  • Those tests revealed that the genome-wide reorganization of super-enhancers drives bursts of germline gene expression after germ cells enter meiosis, a specialized form of cell division that produces the haploid genome of germ cells.

  • The study further demonstrates the molecular process through which super-enhancer switching takes place in germ cells. 

  • Super-enhancers are regulated by two molecules that act as gene-burst control switches—the transcription factor A-MYB and SCML2, a critical silencing protein in sperm formation.