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Archive - Jul 28, 2019

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Certain Gut Bacteria (Clostridia) Prevent Obesity in Mice; Population of These Bacteria Influenced by Immune System; Possible Clues to Human Obesity

Researchers at University of Utah Health have identified a specific class of bacteria from the gut that prevents mice from becoming obese, suggesting these same microbes may similarly control weight in people. The beneficial bacteria, called Clostridia, are part of the microbiome – collectively, trillions of bacteria and other microorganisms that inhabit the intestine. Published in the July 26, 2019 issue of Science, the study shows that healthy mice have plenty of Clostridia -- a class of 20 to 30 bacteria -- but those mice with an impaired immune system lose these microbes from their gut as they age. Even when fed a healthy diet, the mice inevitably become obese. Giving this class of microbes back to these animals allowed them to stay slim. The Science article is titled “T Cell-Mediated Regulation of the Microbiota Protects Against Obesity.” June Round, PhD, an Associate Professor of Pathology at U of U Health, is the study's co-senior author along with U of U Health Research Assistant Professor W. Zac Stephens, PhD. Charisse Petersen, PhD, a graduate student at the time, led the research. "Now that we've found the minimal bacteria responsible for this slimming effect, we have the potential to really understand what the organisms are doing and whether they have therapeutic value," Dr. Round says. Results from this study are already pointing in that direction. Dr. Petersen and colleagues found that Clostridia prevents weight gain by blocking the intestine's ability to absorb fat. Mice experimentally treated so that Clostridia were the only bacteria living in their gut were leaner with less fat than mice that had no microbiome at all. They also had lower levels of a gene, CD36, that regulates the body's uptake of fatty acids. These insights could lead to a therapeutic approach, Dr.

Bacteria Separated by Billions of Years of Evolution and Employing Different Mechanisms of Photosynthesis Share Common Photosynthetic Sites; Results Suggest New View of Evolution of Photosynthesis

Structures inside rare bacteria are similar to those that power photosynthesis in plants today, suggesting the process is older than assumed. The finding could mean the evolution of photosynthesis needs a rethink, turning traditional ideas on their head. Photosynthesis is the ability to use the Sun's energy to produce sugars via chemical reactions. Plants, algae, and some bacteria today perform “oxygenic” photosynthesis, which splits water into oxygen and hydrogen to power the process, releasing oxygen as a waste product. Some bacteria instead perform “anoxygenic” photosynthesis, a version that uses molecules other than water to power the process and does not release oxygen. Scientists have always assumed that anoxygenic photosynthesis is more “primitive,” and that oxygenic photosynthesis evolved from it. Under this view, anoxygenic photosynthesis emerged about 3.5 billion years ago and oxygenic photosynthesis evolved a billion years later. However, by analysing structures inside an ancient type of bacteria, Imperial College London researchers have suggested that a key step in oxygenic photosynthesis may have already been possible a billion years before commonly thought. The new research was published online on July 24, 2019 in Trends in Plant Science. The article is titled “Evolution of Photochemical Research Centres: More Twists?” Lead author of the study, Dr. Tanai Cardona from the Department of Life Sciences at Imperial, said: "We're beginning to see that much of the established story about the evolution of photosynthesis is not supported by the real data we obtain about the structure and functioning of early bacterial photosynthesis systems." The bacteria they studied, Heliobacterium modesticaldum, is found around hot springs, soils, and waterlogged fields, where it performs anoxygenic photosynthesis.

Researchers Uncover New Evidence for Origin of RNA Splicing Within Human Genes; Strongest Evidence to Date That the Spliceosome Evolved from a Bacterial Group II Intron

Old-school Hollywood editors cut unwanted frames of film and patched in desired frames to make a movie. The human body does something similar--trillions of times per second--through a biochemical editing process called RNA splicing. Rather than cutting film, it edits the messenger RNA that is the blueprint for producing the many proteins found in cells. In their exploration of the evolutionary origins and history of RNA splicing and the human genome, UC San Diego biochemists Navtej Toor, PhD, and Daniel Haack, PhD, combined two-dimensional (2D) images of individual molecules to reconstruct a three-dimensional (3D) picture of a portion of RNA--what the scientists call group II introns. In so doing, they discovered a large-scale molecular movement associated with RNA catalysis that provides evidence for the origin of RNA splicing and its role in the diversity of life on Earth. Their breakthrough research is outlined in the July 25, 2019 issue of Cell. The article is titled “Cryo-EM Structures of a Group II Intron Reverse Splicing into DNA.” "We are trying to understand how the human genome has evolved starting from primitive ancestors. Every human gene has unwanted frames that are non-coding and must be removed before gene expression. This is the process of RNA splicing," stated Dr. Toor, an Associate Professor in the Department of Chemistry and Biochemistry, adding that 15 percent of human diseases are the result of defects in this process.