Mysterious respiratory disease is spreading among American dogs; eating nuts can improve men's sperm quality | Technology Weekly

Compiled by Zhou Shuyi

Mysterious respiratory disease spreading among U.S. dogs

A mysterious respiratory disease is spreading among dogs in the United States, CNN reported. Symptoms in dogs include coughing, sneezing, increased eye and nasal discharge, and lethargy. Veterinarians in Oregon have reported more than 200 cases of the disease since mid-August, with related cases also reported in Colorado, Illinois, and New Hampshire. Treaters said that although symptoms of respiratory infection appeared, diagnostic tests for common respiratory diseases were negative. In addition, the disease is often resistant to standard treatments. The Oregon Veterinary Medical Association said that canine infectious respiratory disease complex (CIRDC) may periodically break out in canine populations. "At least nine different bacteria and viruses can cause CIRDC, which are transmitted through respiratory droplets." (CNN)

First discovery of non-penetrative mating in mammals

A new study challenges the common belief that live-bearing mammals mate by genital penetration, showing that big brown bats (Eptesicus serotinus) deliver sperm by pressing their penis against the vulva, rather than inserting it, marking the first observation of non-penetrative sex in mammals.

Big brown bat | Photo credit: Alona Shulenko

The researchers noted that the erect penis of the male big brown bat is 16.4±0.9 mm long, about 22% of the body length, more than 7 times the length of the female big brown bat's vagina (2.3±0.2 mm); the end of the penis is heart-shaped and 7.5±0.6 mm wide, while the outer diameter of the vagina is only about 1.1 mm. It is unlikely that insertion can be completed with such a size mismatch. An email from a bat enthusiast initially confirmed this speculation: the email was attached to a mating video of a big brown bat in the attic of a church in the Netherlands. The authors further analyzed 93 bat mating events in the church and another 4 mating events at a bat rescue center in Ukraine. Records show that male big brown bats will hug the female from behind, bite her neck, and then pass the erect penis around the female's tail membrane and press it tightly against the vulva. Half of the recorded events lasted less than 53 minutes, and the longest lasted more than 12.7 hours. No penetration was observed during the entire process. After mating, the female's belly fur was wet, which the researchers believe indicates the presence of semen, but they still need to take samples for testing to confirm ejaculation. The relevant paper was published in Current Biology on November 20. (Nature News)

Antarctic ozone hole continues to grow over 20 years

A paper published in Nature Communications on November 21 pointed out that since 2004, the ozone content in the Antarctic stratosphere has continued to decrease significantly in October every year, and the ozone loss in the core area has reached 26%. This shows that the Antarctic ozone hole has continued to expand in the past 20 years, which is contrary to the previously reported trend of ozone layer recovery.

The Antarctic ozone hole recorded by NASA on October 3, 2022 | Image source: NASA Ozone Watch

In 1987, the Montreal Protocol listed a list of substances that deplete the ozone layer, and it is generally believed that the protocol has been successful in restoring the ozone layer. A research team from the University of Otago in New Zealand analyzed the overall changes in the ozone layer in the spring months of the Southern Hemisphere from September to November between 2001 and 2022. The study found that from 2004 to 2022, after late September, ozone in the middle and lower stratosphere south of 60° South latitude decreased at a rate of 0.03 ppmv per year, and the fastest rate could reach more than 0.10 ppmv per year. The ozone column component (PCO) in the core area of ​​the ozone hole (75° to 82° South latitude) decreased by a net of 26%, which is approximately equivalent to 30 DU of the total column ozone (TCO). The study believes that the causes of the expansion of the ozone hole are complex and may be driven by dynamic changes in the mesosphere. The researchers said that at the end of October this year, the area of ​​the ozone hole had exceeded 26 million square kilometers, almost twice the area of ​​Antarctica. (University of Otago)

Bacteria can store and pass on "memories"

A recent study found that Escherichia coli can use iron to store memory-like behavioral experiences, respond to external stimuli, and pass them on to offspring. Previous studies have found that bacteria with experience in swarming (a coordinated movement of bacterial groups) will be more "familiar" in subsequent swarming. The new study shows that this memory is based on the regulation of iron content.

E. coli | Image source: Wikipedia

Through more than 10,000 single-cell swarming experiments, the researchers found that bacteria with low iron content in the cells have better swarming ability, while bacteria with high iron content tend to form biofilms, adhering to each other to form a large number of bacterial aggregation complexes. This "iron memory" can last for at least four generations and disappear by the seventh generation. The researchers speculate that when iron content is low, "memory" can prompt bacteria to move around and look for iron in the environment. When iron content is high, it means that the environment is suitable for staying and forming biofilms. This research has potential application value in treating bacterial infections and combating drug resistance. The relevant paper was published in the Proceedings of the National Academy of Sciences (PNAS) on November 21. (The University of Texas at Austin)

Bacteria can directly act on nerve cells to cause itching

The latest research has found that a common bacterium, Staphylococcus aureus (S. aureus), can directly act on nerve cells and cause itching. Previously, it was generally believed that the itching of atopic dermatitis was caused by inflammation and was only indirectly related to bacteria. The new research broke this inherent cognition.

False color photo of Staphylococcus aureus | Image source: Wikipedia

The researchers colonized the skin of mice with Staphylococcus aureus. After a few days, the mice's itching intensified, and repeated scratching caused skin lesions, which spread beyond the original inoculation range. The infected area also showed symptoms similar to human alloknesis - the skin became abnormally sensitive, and slight stimulation would also cause itching. To confirm the itch-causing mechanism, the researchers tested a variety of genetically modified Staphylococcus aureus and locked in a substance called V8 protease among the 10 enzymes secreted by them. Studies have shown that V8 protease activates the PAR1 receptors of skin neurons and triggers itch signals. After the infected mice were treated with PAR1 antagonists, the itching symptoms improved rapidly. The researchers speculate that itching may give microorganisms a survival advantage, allowing them to expand the infection surface through scratching reactions and infect other healthy hosts. The related paper was published in Cell on November 22. (Harvard Medical School)

The Tasmanian Devil returns

Nicknamed the "Tasmanian Devil," the space explosion repeatedly flashed more than a dozen times over a period of several months, but its brilliance never faded, puzzling astronomers. Researchers from Cornell University in the United States published a paper in the journal Nature on November 15, reporting the fast blue optical transient (LFBOT) activity discovered in September 2022 at about 1 billion parsecs from Earth, formally named AT2022tsd.

LFBOT is a high-brightness flash phenomenon similar to a supernova explosion. Its wavelength is mainly concentrated in the blue spectrum, and its generation mechanism is still unclear. The brightness of LFBOT changes very quickly. AT2018cow, discovered in 2018, dimmed rapidly within a few days, while it takes weeks for a supernova explosion to dim. Starting in December 2022, the "Tasmanian Devil" came and went, flashing repeatedly. 14 such flashing events have been observed so far, each lasting only a few minutes. The researchers said that the new study supports the failed supernova theory, that is, a star with a mass of about 20 times that of the sun collapses in the early stages of a supernova to form a dense neutron star or stellar black hole. The poles of the neutron star or black hole emit powerful energy jets, which periodically point to the earth as the celestial body rotates, which can explain the repeated flashing of AT2022tsd. (Nature News)

Why do some people get drunk after two glasses of wine?

Some people get headaches after drinking a small amount of red wine. Generally speaking, after drinking one or two glasses of red wine, the drinker will have a flushed face, headache and nausea within half an hour to three hours. A new study believes that quercetin in red wine interferes with the normal metabolism of alcohol and is the culprit for causing headaches.

Quercetin is a plant-based flavonol, a flavonoid compound among polyphenols, and is widely found in fruits, vegetables and grains. The content of quercetin and its glycosides in red wine is much higher than that in other alcoholic beverages, including white wine. After alcohol is ingested by the human body, it is first converted into acetaldehyde by alcohol dehydrogenase (ADH) in the liver, and then acetaldehyde is converted into acetic acid by acetaldehyde dehydrogenase. The new study evaluated the inhibitory effect of phenolic and flavonoid compounds in wine on acetaldehyde dehydrogenase in vitro, and found that quercetin-3-glucuronide (a typical quercetin circulation metabolite) can inhibit the activity of mitochondrial acetaldehyde dehydrogenase (ALDH2), resulting in the rapid accumulation of toxic acetaldehyde and causing headaches. The relevant paper was published in Scientific Reports on November 20.

Eating nuts may improve sperm quality in men

A new study shows that eating nuts can improve male sperm quality and enhance fertility. The researchers meta-analyzed four nutrition studies, including two randomized clinical trials. The meta-analysis involved a total of 223 healthy men aged 18-35 years, all of whom adopted a Western diet. One trial provided 75 grams of whole-shell English walnuts per day for 12 weeks, and another trial provided 30 grams of walnuts, 15 grams of almonds and 15 grams of hazelnuts per day for 14 weeks. The control group did not consume nuts. The results showed that eating nuts can enhance sperm motility, improve vitality and morphology, but has no effect on sperm concentration. The researchers believe that nuts are rich in Omega-3 polyunsaturated fats, dietary fiber, vitamins, minerals and polyphenols, which can improve reproductive health; it is recommended to eat raw nuts or roasted nuts to avoid excessive sugar and salt additions that cause additional health problems. The relevant paper was published in Advances in Nutrition on November 17. (Monash University)

This article is supported by the Science Popularization China Starry Sky Project

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.

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