A new era for #glycotime, bioRxiv

All kinds of sugar are expressed on cell surface of all cells in nature. Yes, every single cell has it. The sugar coating is like an ID card for every cell to be recognized. We know sugars are grafted onto proteins and lipids through post-translational modification, but no one has anticipated sugar modification of RNA or DNA, until last week. A new study led by Ryan Flynn and Carolyn Bertozzi at Stanford University showed for the first time that certain RNAs, especially Y RNAs, are connected to carbohydrate structure through covalent bonding. However, the exact mechanism and function of the sugar modification are still unknown. 

RNA modification is not new. He Chuan, a biochemist at UChicago, has shown that methylation of RNA can drastically change the possibility of the RNA getting translated, elucidating that eukaryotic cells have complex biological mechanisms to regulate translation through chemical modification of RNA. 

It is rare for a preprint to catch a lot of attention in the scientific community. Apart from the groundbreaking results of this paper, Professor Bertozzi's twitter fame also helped the distribution of the paper. One of the most influencial chemists on twitter, she often tweet about mentorship, diversity and inclusiveness, and glycobiology papers with her iconic #glycotime tag. 

Filaments of hydrogen gas that feed distant galaxies spotted by astronomers, Science

According to the prevailing theory in cosmology, the universe is mostly made of dark matters, which only interact through gravity and cannot be observed in the same way we observe ordinary matter. When galaxies form, dark matters first coalesce into clumps, creating a vast “cosmic web”. Hydrogen gas will then be attracted by the clump of dark matter and flow towards it, feeding the growing galaxy with ordinary matter. Thus, the galaxies that we observe lie embedded in a vast network of filaments and sheets of hydrogen gas. Astronomers have already found that the distant galaxies seem to align slightly due to the distortion of image caused by the gravity of the web’s filaments. However, the faintness of the gas filaments made it very difficult for researchers to directly observe them.
Now, a team led by Hideki Umehata, an astronomer with the Japanese research agency RIKEN and the University of Tokyo, reported the detection of rest-frame ultraviolet Lyman-α radiation from multiple filaments of hydrogen gas in their recent paper published in Science. the team also proposed that the radiation occurred because the hydrogen gas was heated by intense star formation and supermassive black-hole activity happening inside the “cosmic web”.

How do squirrels stay hydrated for months without drinking water, Current Biology

As the weather cools, one species of squirrel, the 13-lined ground squirrel, in the U.S. Midwest is gearing up for one of the most intense naps in the animal kingdom. For up to 8 months, the tiny mammals won’t eat or drink anything at all. Their hibernation consists of prolonged periods of torpor, which are characterized by low body temperature and suppressed metabolism and can last up to 18 days. This torpidity is interspersed with short periods of arousal, lasting up to 48 h, during which squirrels temporarily return to an active-like state and lose small amounts of water to urination and evaporation.
To study how the squirrels manage to stay hydrated without drinking water, researchers divided dozens of squirrels into three groups-those that were still active, those that were in a sleep-of-the-dead hibernation state called torpor, and those that were still hibernating, but in a drowsy in-between state-and measured the blood fluid, or serum, of each group of squirrels. Generally, high serum concentration means more water is needed and makes animals, including humans, feel thirsty. However, the sleeping squirrels’ serum concentration was low, preventing them from waking up for a drink. Even when researchers roused the torpid squirrels, they wouldn’t drink a drop--until the team artificially increased the concentration of their blood serum. More surprisingly, instead of drinking a lot of water before hibernation, researchers found that the animals actually drink less water than they normally do.
The chemical test revealed that the squirrels regulate their blood concentration by removing electrolytes like sodium and other chemicals like glucose and urea and storing them elsewhere in the body (possibly in the bladder), as reported by researchers on a recent publication on Current Biology. During hibernation, osmolytes are depleted from the extracellular fluid. Then during the brief period of arousal, serum osmolality (a fancy word for concentration) levels are restored, preventing the kidney from producing urine, but thirst remains suppressed. This decoupling of thirst and diuresis enables water retention by the kidney while suppressing the drive to leave the safety of the underground burrow in search of water.

Video of the week: Watch AI basketball coaches outmaneuver the opposing team
ISP Sci. Rev. 34 (2019)
Editor: Shiwei Wang & Rossoneri
Integrated Science Program
Northwestern University

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