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Archive - Aug 17, 2019

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Oxygen-Sensing Mechanism Based on Small RNA (sRNA) Is Key to E. coli Locating Region of Colon in Which to Set Up Most Threatening Infections; Discovery May Ultimately Enable Avoidance of These Food-Borne Infections

A pair of University of Virginia (UVA) School of Medicine scientists has revealed how E. coli seeks out the most oxygen-free crevices of the colon to cause the worst infection possible. The discovery could one day let doctors prevent the infection by allowing E. coli to pass harmlessly through the body. The new discovery shows just how the food-borne pathogen knows where and when to begin colonizing the colon on its way to making you sick. By recognizing the low-oxygen environment of the large intestine, the dangerous bacterium gives itself the best odds of establishing a robust infection - one that is punishing for the host. "Bacterial pathogens typically colonize a specific tissue in the host. Therefore, as part of their infection strategies, bacterial pathogens precisely time deployment of proteins and toxins to these specific colonization niches in the human host. This allows the pathogens to save energy and avoid detection by our immune systems and ultimately cause disease," said researcher Melissa Kendall (left in photo), PhD, of UVA's Department of Microbiology, Immunology, and Cancer Biology. "By knowing how bacterial pathogens sense where they are in the body, we may one day be able to prevent E. coli, as well as other pathogens, from knowing where it is inside a human host and allow it (the E. coli) to pass through the body without causing an infection." The UVA research was published in the July 9, 2019 issue of PNAS. The article is titled “The sRNA DicF Integrates Oxygen Sensing to Enhance Enterohemorrhagic Escherichia coli Virulence via Distinctive RNA Control Mechanisms.” E. coli naturally lives in our colons, and most strains do us no harm. But there are several strains that can cause cramps, diarrhea, vomiting, even kidney failure and death. Children are at particular risk. As such, E.

From the Tiny Testes of Flies, Rockefeller Scientists Derive Insights into How New Genes Arise

In the battle of the sexes, males appear to have the innovative edge--from a genetic standpoint, at least. Scientists are finding that the testes are more than mere factories for sperm; these organs also serve as hotspots for the emergence of new genes, the raw material for the evolution of species. Using fruit flies, a Rockefeller University team has gained key insight into how nature's attempts at innovation play out during the development of sperm. In research published online on August 16, 2019 in eLife, they mapped the presence of mutations to DNA at the single-cell level, and the activity of new genes arising from such changes. The open-access article is titled “Testis Single-Cell RNA-Seq Reveals the Dynamics of De Novo Gene Transcription and Germline Mutational Bias in Drosophila.” "Our work offers an unprecedented perspective on a process that enables living things to adapt and evolve, and that ultimately contributes to the diversity of life on Earth," says Rockefeller Assistant Professor Li Zhao, PhD, who led the research. In recent years, studies in animals from flies to humans have turned up a number of young genes that originated in the testes. These and other discoveries suggest that the testes rank among the most productive sites in the body--male or female--for genetic innovation. This mass production of genetic novelties comes with significant risks, however. In humans, for example, a father's sperm acquires two to three times more new mutations than do a mother's eggs in the course of normal development, leaving the sperm riddled with genetic mistakes. In some cases, such mistakes may harm the faather’s offspring, or even derail the prospect of fatherhood altogether.