Summer mosquitoes love soapy smell of you
Some people say that when you take a bath in the summer, wipe some soap and let yourself be stained with soap, and then it is not easy to attract mosquitoes, because the soap fragrance will cover your body odor, mosquitoes can not smell you, of course, they will not bite you.
However, a new study suggests that the scent of soap may not only not help you hide yourself, but can make you a more attractive target, because mosquitoes seem to prefer volunteers who have been washed in most soap.
In the study, published in the journal iScience, the team of authors said mosquitoes may be attracted to soap because they supplement their sugar intake with plant nectar when they are not sucking blood.
Study leader Clément Vinauger, an experimental biologist at Virginia Tech, said: "We put those floral and fruity scents on ourselves, which means that now we smell like a person and a flower." For mosquitoes, this is very attractive to mosquitoes. ”
Of course, the effects of soap vary from person to person.
According to Winager, a person who is normally attractive to mosquitoes may become more attractive after using one soap, and after using another soap, it has a mosquito repellent effect. This may be due to the interaction between soap and each person's unique smell.
This phenomenon also helps explain why some people are born with mosquito physique, while others are not bitten by mosquitoes.
Wienag and his colleagues recruited four volunteers and asked them to wear specific fabrics without bathing and after bathing with soap, each of whom bathed with a different brand of soap.
By testing the fabric after wearing mosquitoes, they found that three soaps, including Dove, increased some, but not all, of the volunteers' mosquito attraction, while a fourth soap tended to repel mosquitoes. (The reason for using fabrics instead of exposing volunteers themselves was to exclude the effects of carbon dioxide exhaled by the human body)
The research team speculates that the soap's relative mosquito repellent effect may be related to its coconut smell, as there is evidence that coconut oil is a natural mosquito deterrent.
American Indian ancestors came from the northern coast of China
There is currently no complete and clear theory about where the ancestors of Native Americans came from and how they arrived in the Americas.
Early thought was that when the Bering Land Bridge connected modern Russia with Alaska in North America more than 20,000 years ago, ancient Siberians crossed the continent along the landing bridge and became the first and only Native American ancestors.
Beginning in the late 2000s, there was growing evidence that ancient humans traveled from different parts of Eurasia and possibly by ship along the Pacific coast of Asia, Bering Land Bridges and North America, and eventually landed in the Americas. To elucidate Native American origins, scientists sought for and analyzed mitochondrial DNA—transmitted only through the maternal line.
A recent study published in Cell Reports showed that Native American ancestors came from Siberia as well as ancient people from China's northern coastal region, who entered the Americas through at least two migrations.
The two major migrations apparently occurred during the period when the Bering Land Bridge was blocked by snow and ice and was impassable. Therefore, the researchers believe that ice age migrants may have traveled along the Pacific coast. The new paper states:
The first migration probably occurred between 26,000 and 19,500 years ago, the last peak ice age, the coldest period of the last ice age. At that time, the ice sheet covered most of the earth, and the inhabitants of northern China faced extremely difficult living conditions.
The second migration occurred between 19,000 and 11,500 years ago, when the ice sheet began to melt. Previous studies have shown that this climate change may have contributed to rapid population growth and population dispersal to other regions during this period.
It is worth mentioning that during the second migration, some people entered and settled in Japan from the northern coast. This may also explain the similarities between prehistoric arrowheads and spears found in the Americas, China and Japan.
The team of authors is from the Kunming Institute of Zoology, Chinese Academy of Sciences. They searched for the ancestral lineage D4h3a of the American Indian maternal lineage (i.e., mitochondrial DNA lineage) D4h3a for 10 years, combed through 100,000 modern and 15,000 ancient DNA samples from Eurasia, and successfully found 216 modern individuals and 39 ancient individuals from ancient lineages.
By analyzing mutations accumulated over time, looking at the geographic location of samples, and using carbon dating, they were able to reconstruct the history of D4h's origin and expansion, ultimately revealing these facts.
Polar microorganisms can break down plastics at low temperatures
In the Alps and the Arctic, scientists have found microbes that can digest plastic at low temperatures. They have the potential to be a valuable tool to help the plastics cycle.
In fact, we have found many microorganisms that have the ability to eat plastic, but they usually only work above 30 degrees Celsius. This means that their use requires heating, which is extremely expensive for industrial practice and does not meet the requirements of carbon neutrality.
According to the team at the Swiss Federal Institute for Forest, Snow and Landscape (WSL), the new microbial taxa obtained from "plastic balls" in alpine and arctic soils "break down biodegradable plastics at 15°C", according to the team at the Swiss Federal Institute for Forest, Snow and Landscape (WSL), according to its excavators, the new microbial taxa obtained from the "plastic balls" of alpine and Arctic soils, can help reduce the cost and environmental burden of the enzymatic recycling process of plastics. The groundbreaking work was recently published in the journal Frontiers in Microbiology.
Joel Rüthi, a microbiologist at WSL, and his colleagues collected 19 bacterial strains and 15 fungal strains from Greenland, Svalbard and Switzerland and had them grow as single-strain cultures on freely placed or deliberately buried plastic products (kept underground for a year).
The environment in which the microorganisms are located is a dark laboratory environment of 15°C. Ruti et al. tested the ability of each strain to break down different types of plastic.
The plastics tested included non-biodegradable polyethylene PE, biodegradable polyester polyurethane PUR, polybutylene terephthalate PBAT and biodegradable blends of polylactic acid PLA.
The 19 bacterial strains came from 13 genera of the phylum Actinomycetes and Proteobacteria, and 15 genera of fungi in the phylum Lyascomycetes and the phylum Mucormycetes.
The test results showed that after 126 days of culture, all strains could not digest PE, but 11 fungi and 8 bacteria could decompose PUR at 15°C, 14 fungi and 3 bacteria could digest the mixture of PBAT and PLA, and 2 fungi could eat all the test plastics except PE.
Ruti's colleague Beat Frey said: "Microbes have been shown to produce a variety of polymer-degrading enzymes. These enzymes are involved in the breakdown of plant cell walls. Especially plant pathogenic fungi – which scientists often find to biodegrade polyesters because they produce keratinase. Because plastic polymers are similar to plant polymers in keratin, they become targets for keratinase. ”
The next big challenge will be to identify plastic-degrading enzymes produced by microbial strains and optimize the process of acquiring large amounts of enzymes. In addition, further modifications to the enzyme may be required to optimize properties such as enzyme stability.
Source:
Soap can make humans more attractive to mosquitoes, study finds
Some of the first humans in the Americas came from China, study finds
Microbes discovered that can digest plastics at low temperatures
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