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Tag: Russian Foundation for Basic Research

  • RUDN Ecologists Describe Strong Desertification in Northern Algeria

    RUDN Ecologists Describe Strong Desertification in Northern Algeria

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    Newswise — RUDN University ecologists and colleagues from Algeria, Greece, Egypt, and Russia have determined the scale and causes of desertification in northern Algeria. The analysis was carried out using satellite images in different ranges. Over six years, the area of usable land has decreased by 1.5-9 times. The results were published in The Egyptian Journal of Remote Sensing and Space Science.

    The loss of the biological function of land is called desertification. The composition of the soil changes, the sand content increases, and the vegetation becomes poorer. Such lands can no longer be cultivated; livestock cannot graze on them. There are several regions on Earth with a high risk of desertification. One of them is North Africa. Remote monitoring using satellite images helps track desertification. However, different soil types may be difficult to distinguish by satellite data if they have high sand content. It is important to interpret the images correctly. RUDN University ecologists and colleagues from Algeria, Greece, Egypt, and Russia determined which satellite data is best suited for determining soil composition.

    “There is a problem with the similarity of reflectivity between different soils with high sand content. These are, for example, sand, loamy sand and clay. Therefore, it is necessary to develop more accurate spectral indicators to distinguish soil structures easily,” said Dmitry Kucher, Ph.D., head of the Scientific Center for Research, Integrated Design and Development of Urban and Agricultural Development of the RUDN University.

    Ecologists conducted the study in the Nemamcha region in northern Algeria. This region has undergone rapid desertification. To trace spatiotemporal changes in the topsoil, RUDN University ecologists used satellite images from 2013 and 2019 and soil samples. Then they calculated the correlation between these data and analyzed the possible causes of desertification.

    It turned out that blue and near-infrared images are best suited for determining the proportion of sand and clay. Using them, RUDN University ecologists built a regression model determing the composition of the soil with sufficient accuracy—the coefficient of determination (an indicator of model quality) reached 89%.

    Changes in soil composition between 2013 and 2019 indicate noticable desertification: the share of land suitable for agriculture in the region fell from 31% in 2013 to 4% in 2019, and the grazing area fell from 21% to 13%. Ecologists also named the main cause of desertification in this area – aeolian processes, that is, wind erosion and the application of sand by the wind. They turn out to be strong, among other things, because of human activity – too intensive cattle breeding and agriculture.

    “We found a dominant role for aeolian processes, which are exacerbated by low topography, overgrazing, climate change, and over-intensive agriculture. We recommend investigating the protective role of dry grasslands and desert shrublands against erosion and restoring degraded lands. We urge legislators to implement remote monitoring strategies and restore vegetation to combat desertification,” said Dmitry Kucher, Ph.D., Head of the Scientific Center for Research, Integrated Design and Development of Urban and Agriculture at RUDN University.

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    Russian Foundation for Basic Research

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  • RUDN Biochemists Found How to Weaken Cancer Cells

    RUDN Biochemists Found How to Weaken Cancer Cells

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    Newswise — Biochemists from RUDN University described how to prevent cancer cells from becoming resistant to chemotherapy drugs. Having determined the resistance mechanism, biochemists selected a drug that can slow down it. The results were published in the International Journal of Molecular Sciences.

    Chemotherapy remains the mainstay of cancer treatment in most cases. One of the most common anticancer drugs is the platinum-containing cisplatin. It is effective in the fight against sarcomas and other types of malignant tumors. The disadvantage of this treatment is the gradually emerging resistance of tumor cells to the antitumor drug. Biochemists from RUDN have described a method that allows one to “cancel” resistance to cisplatin in vitro on ovarian cancer cells.

    “Platinum-based anticancer drugs, such as cisplatin, are established chemotherapeutic agents in the treatment of certain types of malignancies. However one of the main obstacles to effective chemotherapy is resistance to cisplatin. Drug resistance can develop through several mechanisms. Our goal was to understand these mechanisms and study possible ways to eliminate resistance,” said Elena Kalinina, Doctor of Biological Sciences, Professor of the Department of Biochemistry, RUDN University.

    Previously, RUDN biochemists discovered that cisplatin resistance in ovarian cancer cells is affected by overexpression of several genes. The authors also showed that quercetin (a compound from the group of flavonoids) helps reduce this effect. Therefore, biochemists have suggested that treating cells with quercetin first and then with cisplatin can help avoid resistance. Biochemists tested this assumption on cancer cells of the SKOV-3/CDDP lines.

    Preincubation of tumor cells with quercetin before exposure to cisplatin resulted in significantly improved outcomes. With 48 hours of preincubation at the optimal dose (60 micromoles), quercetin reduces the proportion of surviving cancer cells to approximately 25% if the action time of cisplatin is also 48 hours. Without prior exposure to quercetin, this proportion is about 80%.

    “Our in vitro data show that quercetin sensitizes cisplatin-resistant cells. To confirm that, further studies are needed with other cell lines that are resistant not only to cisplatin but also to other anticancer drugs. Future experiments will be aimed at confirming the effect of preincubation with quercetin in vivo. This will allow us to evaluate its potential for eliminating resistance to cisplatin in tumor cells,” said Elena Kalinina, Doctor of Biological Sciences, Professor of the Department of Biochemistry, RUDN University.

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  • New algorithm helped to find thousands of repeated elements in bacterial genome

    New algorithm helped to find thousands of repeated elements in bacterial genome

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    Newswise — Scientists from The Federal Research Centre “Fundamentals of Biotechnology” of the Russian Academy of Sciences (Research Center of Biotechnology RAS) elaborated mathematical algorithm that enabled to find dispersed repeated elements in genome with great accuracy. Authors tested this approach on genetic sequences of nine kinds of bacteria, and discovered early unknown repeats in all of them. Thus, for example, it turned out that almost 50% of genome of E. coli is presented by quite long repeats (400-600 pairs of nucleotides long). Such repeats represent a definite code, that is placed upon existing genes of bacteria over coding amino-acids. The found dispersed repeats can help to find new genetic targets, that are interesting from the point of view of biotechnology, for example, parts of DNA, impact on which will enable to increase productivity of bacterial strains. Results of the research are published in International Journal of Molecular Sciences.

    In genomes of many eucaryotic (multicellular) organisms – from yeast to human – there are repeated sequences of nucleotides that are a kind of letters, that compose DNA. Each such repeat is several hundreds of nucleotides long and they are spread all over the whole genome. In sum they form a family that can have significant number of separate copies. The amount of such families, and also position and number of repeats in each family differ in various species and so they can tell about evolution and origin of different living organisms. There are many mathematical algorithms for searching of dispersed repeats (those ones that are more or less equally spread in a genome), such algorithms that even enable to find out “corrupted” copies, those repeats, where some mutations took place and the sequences of which are different from others. However, in the process of evolution such changes can be so numerous, that it becomes impossible to find in genome two insufficiently similar sequences. In this connection scientists search new approaches for searching of dispersed repeats, spread in genomes of various organisms. It is significant to note that such families of repeats were earlier found only in genomes of eukaryotes (multicellular) organisms, whereas they were unknown in organisms of bacteria.

    Scientists from the Federal Research Centre “Fundamentals of Biotechnology” of the Russian Academy of Sciences (Research Center of Biotechnology RAS) suggested a new method of searching of dispersed repeated sequences. Principle of its work can be compared with search of mathematic matrix, consisting of columns and lines, that describes the family of repeats in the best way. The suggested approach is optimal as far as accuracy of finding “dispersed” repeats in the whole genome is concerned, because it takes into account the ability of changing nucleotides and their insertions and deletions, in other words, mutations.

    Researchers tested this algorithm on artificially generated sequences, that contained thousands of repeats each, a part of which contained mutations. A comparison with widely used in bioinformatics search systems showed that the suggested method enabled to find out repeats of one family with a greater number of mutations between them (up to the change of half of the nucleotides in a sequences) more precisely.

    Then authors of the research applied algorithm for search of repeats in genome of nine kinds of bacteria: Escherichia coli, Bacillus subtilis, Azotobacter vinelandii, Clostridium tetani, Methylococcus capsulatus, Mycobacterium tuberculosis, Shigella sonnei, Treponema pallidum and Yersinia pestis. Analysis enabled scientists for the first time to find out three families of repeats, 400-600 pairs of nucleotides long, in Escherichia coli, which in total take almost 50% of the whole genome of bacterium. Earlier in this microorganism there were known similar elements only of less length – up to 300 pairs of nucleotides – and in smaller numbers. In genetic sequences in other bacteria, they managed to find 1-2 families of repeats of the same length (400-600 nucleotides). By this less of them were found in Treponema pallidum, that can be connected with small size of a genome of this microorganism.

    “The found families of dispersed repeats are discovered in genes, and they represent a definite code placed on genes over triplet code, that provides coding of amino acid sequences by genes. By this it is not important on which DNA strand genes are situated. The obtained code can serve as a base for folding DNA in so called nucleoid, that in most degree defines expression of bacterial genes. It can be said that in bacterial DNA there is a code providing its folding into a nucleoid, and now we have obtained an ability to manage it. It opens great opportunities for creating new microorganisms, useful for people”, – tells about results of the research Eugine Korotkov, Doctor of Biological Sciences, head of the group of mathematical analysis of DNA sequences and proteins the Federal Research Centre “Fundamentals of Biotechnology” of the Russian Academy of Sciences (Research Center of Biotechnology RAS).

    The suggested approach can be used for analysis not only of bacterial genomes, but also genetic sequences of multicellular organisms, for example, animals or plants. It can help to understand evolution of genomes and their separate elements better, and also in the case of bacteria to find targets for creating new antibiotics or increasing productivity of strains that are important for biotechnology.

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  • Chemists create frameworks for the oxidation of hydrocarbons

    Chemists create frameworks for the oxidation of hydrocarbons

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    Newswise — RUDN University chemists have created new copper-containing metallasilsesquioxane frameworks. Some of them have proven to be effective catalysts for the oxidation of hydrocarbons. The results are published in Molecules.

    Silsesquioxanes are a large group of organosilicon compounds. They are composed of a silicon and oxygen backbone, with the silicon atom containing an organic substituent. It is important that silsesquioxanes can bind metals – play the role of ligands. Metal-containing derivatives of silsesquioxanes are used in industrial chemistry for catalysis. In particular, complexes of silsesquioxanes with metals catalyze the oxidation of hydrocarbons. A RUDN University chemist created a series of new silsesquioxane complexes with copper and additional organic ligands, 8-hydroxyquinolines. Some of them proved to be effective catalysts.

    “Silsesquioxane compounds are a kind of bridge between organics and inorganics. They consist of a purely inorganic main chain of silicon and oxygen, substituents at the silicon atom are responsible for the organic component. Silsesquioxanes are often considered as unique molecular models for surface studies and for catalysis. Structural features of silsesquioxanes are used to create organic-inorganic materials. Another important feature of them is the role of ligands for metal complexes . At the same time, in the composition of metal complexes silsesquioxanes can combine with additional organic ligands. Surprisingly, the ligands of the very popular 8-hydroxyquinoline family have never been used to design metallosilsesquioxane complexes. We investigated the synthesis of the first such compounds, studied their molecular and supramolecular structures, and also evaluated the properties of new compounds in the oxidation of hydrocarbons,” said Alexey Bilyachenko, Doctor of Sciences in Chemistry, Leading Researcher of the Joint Research Institute of Chemistry, RUDN University.

    Chemists synthesized a family of 11 compounds. All of them have a similar structure, a three-dimensional “skeleton” with two silsesquioxane and two 8-hydroxyquinoline ligands, coordinating copper and alkali metal atoms (lithium, sodium or potassium). The synthesis goes by self-assembly flow, when simple reagents are transformed into a complex structure. RUDN University chemists described in detail the structure of new compounds, and then tested their catalytic abilities using the example of hydrocarbon oxidation.

    One of the obtained compounds turned out to be an effective catalyst in the oxidation of hydrocarbons and alcohols using hydrogen peroxide. Chemists concluded that the key mechanism in oxidation is radical, involving hydroxyl fragments.

    «We showed the first examples of wireframe metallosilsesquioxanes containing 8-hydroxyquinoline ligands using a convenient self-assembly method. One of the frameworks showed high catalytic activity in the oxidation of hydrocarbons and alcohols. We came to the conclusion that oxidation proceeds with the participation of free hydroxyl radicals,” said Alexey Bilyachenko, Doctor of Sciences in Chemistry, Leading Researcher of the Joint Research Institute of Chemistry, RUDN University.

     

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