Science Reporting

Vesta was hit by a big rock 4.5 billion years ago

Vesta is one of the space bodies included in the asteroid belt, one of the largest with an average diameter of 525 miles (it is the second most massive body after Ceres). Discovered by Heinrich Wilhelm Olbers in 1807, it is a quite interesting body also because it is the brightest asteroid visible from Earth.

A group of researchers from the Tokyo Institute of Technology and the National Institute for Polar Research and ETH Zurich discovered that this large asteroid suffered a massive hit-and-run collision 4.52 billion years ago that profoundly influenced its evolutionary history. Among other things, this same impact would help explain the asymmetrical shape of the asteroid.

In the study, published in Nature Geoscience, it is also stressed that this asteroid has an original structure with its crust, its mantle and its metal core, a structure quite similar to the Earth but unusual for the asteroids themselves.

Examining a rare mineral called zircon found in the mesosiderites, the team, with unprecedented precision, established that 4558.5 million years ago (with a margin of error of 2.1 million years) the crust had begun to form and that 4525.4 million years ago (with a margin of error of 850,000 years) there was a strong metal silicate mixing event.

These two events would testify to the impact with another asteroid that occurred in the northern hemisphere of Vesta, an impact that was probably the cause of the same formation of the thick crust that was then observed during the Dawn mission of NASA.

Science Reporting

Scientists investigate how to combat the spread of viruses from mosquitoes

A research group is testing a new method to combat the spread of viruses by mosquitoes. Mosquitoes can be responsible for the spread of serious diseases such as yellow fever, dengue fever and the Zika virus.

Research by Beth McGraw, professor of entomology at the State University of Pennsylvania, gives new hope of using a particular bacterium, called Wolbachia, which is present in about half of all insects, to block the replication of the virus within mosquitoes.

The article published in Virus Evolution describes in particular how this bacterium can be used to stop the spread of dengue fever and how the virus seems not to develop resistance to it, at least in laboratory experiments. Many mosquitoes carrying this virus, however, do not have this bacterium and some laboratory work is needed to place it inside the cells of these mosquitoes.

However, once this step was taken, the researchers realized that the dengue viruses grown with the Wolbachia bacterium were much less effective in infecting mosquito cells and had a reduced ability to replicate than viruses grown without the bacterium.

Since the mosquito populations are very large and these are only laboratory experiments on a few small numbers, it is possible that once this method is applied in nature the virus can quickly develop resistance to the bacterium.

In any case, the fact that there is a bacterium that almost completely blocks the dengue fever virus is very attractive information, also because this bacterium seems to spread very quickly and very efficiently among mosquitoes.

This is because it causes a curious effect on males: those containing this bacterium can no longer reproduce with females without the bacterium. This means that males with the bacterium inside their cells prevent females without the bacterium from reproducing and that each generation of mosquitoes has more and more specimens containing the bacterium.

Currently, several releases of Wolbachia are already underway in tropical and subtropical areas where the mosquito of the species Aedes aegypti, considered as the main vector of the dengue virus, is more present. These releases will help to understand whether the virus can actually develop resistance in nature.

A resistance that however has not been developed by the virus in the laboratory, something that gives hope, as McGraw herself reports: “I am constantly surprised by Wolbachia. I thought we would have dengue variants that would develop resistance: Wolbachia is doing a better job than I expected in controlling viral replication in cells.”

Science Reporting

Scientists find how cholera bacterium use a hooked appendix for various purposes

Vibrio cholerae is the bacterium that causes cholera: it infects the small intestine and causes diarrhoea and dehydration. This bacterium often lives on the shells of crustaceans, exoskeletons composed of a sugar polymer, called chitin, which the bacterium feeds on.

To hold on to the shells, but also to perform other tasks, these bacteria use an appendix as if it were a sort of grappling hook thanks to which the Vibrio cholerae, and several other species of bacteria, detect the surfaces and stick to them for feeding.

With regard to this particular characteristic of these bacteria, a group of researchers carried out research published in Nature Microbiology, a study that obtained important new information on how bacteria colonize surfaces and how they distinguish the individuals around them, considered fundamental biological issues.

With these “grappling hooks,” called type IV hairs, they can also take DNA from neighboring bacteria and perform other basic tasks for their survival including the recognition of other members of their own species. “The idea is that bacteria can throw these long ropes, hook onto something and rewind it to themselves,” reports David Adams, one of the researchers. How they work exactly and what else they are able to do, in addition to being able to stick to DNA, is still partly unknown.

Now, however, researchers have managed to directly observe the pili in live cholera bacteria using a technique called cysteine labeling. According to one of the researchers involved in the study, Melanie Blokesch, this is an “important milestone: even though we had established some time ago that these structures were there, seeing them moving in real time was something very special.”

They discovered that different strains of V. cholerae produce slightly different variants of the pili and that they naturally form a dense network of self-interacting pili that bind closely to the surface of the chitin and are necessary for the bacterium to remain attached during the flow of water.

Science Reporting

Site of the greatest meteorological impact in the United Kingdom analyzed

The site of what has already been defined as the largest meteor impact crater in the UK has been identified and analyzed and confirmed (it was already discovered in 2008) by a group of researchers from the universities of Oxford and Aberdeen. The traces related to the site, located near Ullapool, Scotland, were produced 1.2 billion years ago by a meteorite with an estimated width of one mile.

Although the precise point of impact, which is now in the sea about 20 km away from the Scottish coast, is still unknown today, there are many details and information that scientists have collected and then published in the Journal of the Geological Society. The identification of the crater itself, however, required various analyses and was quite difficult because the impact occurred at a point that was then covered by the sea over time. The main traces, therefore, are now found under the seawater of the Minch basin.

It is, in any case, an “exciting discovery,” as reported by Ken Amor, one of the authors of the study, because despite this various interesting traces have been preserved thanks to the fact that most of the meteorite ended up in an ancient valley where then the sediments have covered them and in a way preserved. According to the scientists, attending such an event “would have been a real spectacle,” as the debris scattered by the impact of the meteorite was mostly thrown into an arid landscape and a large area.

There were no witnesses, however: at that time (more than 1.2 billion years ago) there were still no living beings on Earth and life was still only in the sea. The territory that is now part of Scotland, moreover, at that time was located near the equator and was characterized by an arid environment and a “Martian” landscape. According to scientists, there is also the possibility that such an event may occur in the future since objects with a diameter of about one kilometer that impact on Earth arrive on average every 100,000-1 million years (estimates are quite variable).

Science Reporting

Dark matter could be made from ultra-light particles

Since dark matter has not yet been detected and it is not known whether it is made by known, theorized or completely unknown particles, several scientists are conducting innovative experiments to find it in previously unexplored intervals of particle mass and energy.

As far as we know, dark matter could also be composed of something that could not be categorized in the concept we have of particle. But it could also be composed of ultra-light theoretical particles, such as wave-shaped particles called assions. A new approach is that dark matter could be much lighter, that is, with a lower mass and a weaker energy level, than ever before terrorized.
This is the approach that Kathryn Zurek, a theoretical physics at Berkeley Lab, is using.

According to the scientist, there are some theoretical ideas about dark matter that have blossomed in recent years that are becoming “mainstream” with respect to more classic theories, such as those, for example, related to WIMP particles. We talk about low mass dark matter, a theory that according to the scientist herself is now spreading more and more.

Zurek himself is ready to focus on experiments to find particles of dark matter with a mass smaller than a proton, a subatomic particle inside the nucleus that weighs about 1850 times an electron.
This new effort, which will focus more on the search for characteristics related to mass, will have “the overall goal of finally understanding the nature of the dark matter of the universe.”

The scientist, together with her group, is now ready, thanks to a funding of 24 million dollars provided by the U.S. Department of Energy to his laboratory, to use the most modern accelerators available to his institute to detect any single galactic particles, which could compose dark matter, that have a mass up to about a trillion times less than that of a proton.

Such a possible “lightness” would also explain why dark matter has never been identified until now, basically because it is imperceptible with any instrument. Initially researchers will focus on helium crystals and gallium arsenide crystals which could present interactions between low mass dark matter particles.