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There is a lot going on in the sky. Not only birds, insects, pollen and airplanes make it, but also tiny particles from a desert or sea that have been blown away by the wind. These microscopic particles can travel long distances – and often have a special baggage even smaller than the means of transport: microbes that can be transported across continents and oceans.
Viruses in particular use this type of transport Weltenbummelns. But they have not been able to look too closely at science in their travel plans – because researchers are still a lot of puzzles regarding the so-called ecology of viruses. The focus is not on the pathogenic potential of microbes or the exact understanding of a mechanism of infection. It is rather an overview: how do viruses shape life on Earth? And how many are represented on the planet? "As a whole, viruses are the biggest unknowns in our habitat," writes German virologist Hans-Georg Kräusslich a few years ago
Collection basin for viruses
how many of these virus floating above our heads fall back into the countryside or into the water. A team led by Isabel Reche and Gaetano D'Orta of the Spanish University of Granada recently published the answer in the journal of the International Society for Microbial Ecology. According to this newspaper, up to 7 billion viruses a day fall on the earth – per square meter.
Researchers set up "virus catch basins" in mountainous Sierra Nevada. These sensors were able to know whether they were picking up dust particles or particles from the sea. Using chemical and physical methods as well as extrapolations, it was possible to determine the number of viruses bound to the particles captured by day and per square meter. It has also shown that most of the viruses contained in tiny sediment baggage are coming out of the sea, that a smaller portion is related to dry dust particles and that a fraction numerically as good as 45 a negligible fraction floats freely. Viruses are not the only microbes that use this route. Bacteria travel the same way, but to a lesser extent and less. Of them, up to 80 million per square meter a day have fallen, write the authors.
Those who think of viruses and bacteria mainly because of illness and danger, could easily shudder at these numbers. Do you even have a chance to stay healthy if billions of microbes fall to the ground every day? As comprehensible as this idea may be, it ignores the enormous diversity of germs.
A good 8% of the human genome is of viral origin.
Viruses are the largest group of microbes. They infiltrate all that lives: in animals and plants, but also as so-called phages in bacteria. And a virus called Sputnik infects even another virus, the unusually large mimivirus. Apart from their omnipresence, their independence is typical of viral microbes. Only they can not reproduce, only with the help of their host. Therefore, it is even debatable if a virus "lives" itself, because according to a common definition, it would need the ability of autonomous replication.
Influence on all the living
In order to multiply, viruses have far-reaching consequences because they introduce parts of their own genetic material into that of their host. Also, in the development of Homo sapiens, what happened today is what can be read about our genetic material. About 8% of the human genome is of viral origin. But what follows from it and the significance of viruses for humans – apart from their pathogenic potential – is still largely obscure. However, the influence does not seem to be negative. A study from the University of New York indicates that some viruses could help keep intestinal flora in equilibrium and pathogens at a distance.
Such information about the so-called virosphere does not change the opinion of many researchers that the ecology deserve more attention. In 2017, American scientists Matthew Sullivan, Joshua Weitz and Steven Wilhelm called and wrote: "Viruses influence the function and evolution of all living things. But to what extent, remains a mystery. "
It may also be because it is more difficult to enter the world of viruses than in bacteria.The former are smaller and therefore less easy to find, they can often not be grown in the laboratory , and they can genetically change very rapidly.
Students search for unknown phages in puddles
is the "virom" (the totality of all viral genes) in the oceans.There, they appear mainly as phages that infect bacteria.Every milliliter of seawater contains millions of viruses and every second 10 high-level viral infections in the oceans were written by Curtis Suttle's University of British Columbia in Vancouver a few years ago in the journal Nature Microbiology Reviews.Sutle also conducted the study which discovered the rate of virus descending every day
However, anyone who wants to discover new things in the world of viruses does not need to dive deep into the ocean and does not even need scientists to be. This is proven by the "phage hunter" projects in American universities. Here, students in street puddles looking for previously unknown phages. The results of one of these projects appeared in the magazine "PLOS One". The study lists 18 previously unknown viruses that infect the common and harmless bacterium Mycobacterium smegmatis. What the newly discovered microbes should be called was what students at the University of Washington in St. Louis were allowed to decide. And so in the world of viruses, there is now a Fruitloop, a Predator, an Angelica and an Uncle Howie.
(Tages-Anzeiger)
created: 03.07.2018, 18:15
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