Researchers from the Institute of Cytology of the Russian Academy of Sciences (Institute of Cytology of the Russian Academy of Sciences) and St. Petersburg State University have discovered a new species of amoeba (Thecamoeba vumurta) that lives in the lake of Izhevsk. The discovery allowed scientists to replenish our knowledge of amoeba diversity and to clarify ideas about the evolutionary relationships of various living creatures on our planet. The results of the study were published in a scientific journal European Journal of Protistology.
The amoebae are unicellular organisms of microscopic size (from 20 to 700 microns). These organisms inhabit almost all possible habitats – water, soil, tree surfaces, stones and other substrates. Some species of amoeba live in the intestines of humans and animals. There are amoebas that are dangerous pathogens, such as amoeba dysentery or some types of Acanthamoeba that cause a rare but dangerous disease called amoebic encephalitis.
“Although scientists have described a large number of amoeba species, there are many ‘white spots’ in the study of these microorganisms and almost every year some new information appears. “Our team is studying the diversity of pod-shaped amoebae, and during those studies, we found a new species, which we named Thecamoeba vumurta,” said Elisey Mezentsev, Junior Researcher at the Laboratory of Cytology of Unicellular Organisms at the Institute of Science. Centers of the Russian Academy of Sciences, Junior Researcher at the Department of Invertebrate Zoology at St. Petersburg State University.
Thecamoeba vumurta was found by researchers in a sample collected in a lake in Izhevsk. Initially, the scientists examined the general morphology (key features) using a light microscope. as well as the superstructure (most structure of the individual components of the cell) of this organism. The amoebae found turned out to be very similar to the long-described species Thecamoeba striata, whose cultures have been lost to international collections.
An integral part of the work of the study of modern diversity is the acquisition and comparison of sequences of individual genes in order to understand how closely related organisms are. Gene sequencing requires taking an amoeba DNA sample. To do this, scientists had to force tecamoeba to “starve” so that the food they ate was fully assimilated. Otherwise, a mixture of amoeba DNA and food items could be obtained. The scientists then performed an amplification of the entire DNA genome isolated from several “hungry” amoebae, as well as PCR and sequencing of the gene for the small rRNA subunit.
The resulting sequence is very different from all known tecamoeba sequences. At the same time, a sequence fragment of the lost species T. striata was found in the file data. Comparison of the collected data showed that T. vumurta is genetically close to T. striata. However, genes contain differences large enough to be recognized as a new species in science.
“The results of our study are important for understanding the diversity of the amoeba. In science, there is such a thing as “twin species”. These are species that are very similar in appearance, but have significant genetic differences. This is exactly the case we are facing now. And that means there is a whole group of thecamoeba species that researchers could have previously confused with one. Accordingly, it is necessary to be critical of all information about cases of discovery, distribution, ecological and biological characteristics, as the knowledge gathered could be related to different types of amoebas that are similar to each other. This knowledge is also necessary for further more specific research. For example, a direction related to the study of the role of amoebae as carriers of various pathogenic bacteria, which, among other things, can be dangerous to humans, is now being actively developed. Therefore, it is necessary to understand what species can be carriers of these bacteria, how amoebae are related to each other and how to identify them and identify them correctly in practical studies of diversity “, explains Elisey Mezentsev.
The scientific work is carried out with grants from the Russian Institute of Sciences (no. 20-14-00195) and RFBR (no. 19-34-90155) Year of Zoologyannounced at St. Petersburg University in 2022.
– amoeba Thecamoeba vumurta, enlarge;
Press Service of the Institute of Cytology of the Russian Academy of Sciences (INC RAS)