Vladimir V. Kuznetsov

Bio: Vladimir V. Kuznetsov is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Diaziridine & Heat transfer. The author has an hindex of 30, co-authored 465 publications receiving 4223 citations. Previous affiliations of Vladimir V. Kuznetsov include D. Mendeleev University of Chemical Technology of Russia & Novosibirsk State University.

Stress responses of tobacco cells to high temperature and salinity. Proline accumulation and phosphorylation of polypeptides

Abstract: Stress responses to high temperatures (35-48°C) and salinity (170-340 mM NaCl) and thermotolerance were investigated for the salt-sensitive wild type and the salt-tolerant N r E s -1 strain of Nicotiana sylvestris L. using suspension-cultured cells. Under saline conditions, N r E s -1 strain cells accumulated proline, polyamine (putrescine and spermidine) and betaine in contrast to wild-type cells. The simultaneous treatment of salt-tolerant cells with high temperature (40°C) and Nacl (170 or 340 mM) resulted in a transient overproduction of proline accompanied by an increase in their thermotolerance. At the high temperature, the synthesis of polypeptides and the accumulation of heat shock protein HSP70 mRNA were not affected by salinity. The higher thermotolerance of the NaCl-tolerant cells could not be related to osmoprotecting sugar-starch interconversions but could rather be associated with selective phosphorylation of several polypeptides (23-24, 27, 31-32, 47 kDa) prior to the accumulation of proline. The possible role of polyamines and polypeptide phosphorylation in this respect is discussed.

Polyamines and Stress Tolerance of Plants

Abstract: Polyamines are universal organic polycations implicated in a wide array of fundamental processes in plants ranging from triggering the cell cycle, genome expression, signaling, plant growth and development to plant adaptation toward abiotic stresses. Stress-induced ac-cumulation of polyamines often correlates with the improvement of plant tolerance that has been shown by modulation of the polyamine biosynthetic pathway in some transgenic plants. Genes for several key biosynthetic and catabolic enzymes have been cloned from various plant species. Polyamines can modulate functions of RNA, DNA, nucleotide triphosphates, and proteins and protect macromolecules under stress. Polyamines are also the modulators of stress-regulated gene expression and exhibit antioxidant properties. Taken together, these recent findings have promoted intense efforts to characterize in detail the mechanisms of polyamine homeostasis regulation and to elucidate realization of their multifunctional role in plants under environmental stress. However, molecular mechanisms underlying poly-amine participation in plant adaptation to stress are not completely understood. Plant adaptation to various abiotic stresses is a complex process involving numerous changes, including the increased expression of many stress-related genes responsible for the accumulation of compatible solutes, expression of antioxidant enzymes, and supression of energy-consuming pathways. Recent reviews did not summarize data concerning the correlation between polyamine functions and other adaptive mechanisms in plants. Therefore in this review, particular emphasis is placed on discussion on protective mechanisms used by polyamines during different stages of the adaptation process.

Non-stomatal limitation of photosynthesis by soil salinity

Abstract: Soil salinity is a major threat to agricultural sustainability and a global food security. Until now, most research has concentrated around stomatal limitation to photosynthesis, while non-stomatal...

Salinity tolerance in halophytes

Abstract: Halophytes, plants that survive to reproduce in environments where the salt concentration is around 200 mM NaCl or more, constitute about 1% of the worlds flora. Some halophytes show optimal growth in saline conditions; others grow optimally in the absence of salt. However, the tolerance of all halophytes to salinity relies on controlled uptake and compartmentalization of Na+, K+ and Cl- and the synthesis of organic compatible solutes, even where salt glands are operative. Although there is evidence that different species may utilize different transporters in their accumulation of Na+, in general little is known of the proteins and regulatory networks involved. Consequently, it is not yet possible to assign molecular mechanisms to apparent differences in rates of Na+ and Cl- uptake, in root-to-shoot transport (xylem loading and retrieval), or in net selectivity for K+ over Na+. At the cellular level, H+-ATPases in the plasma membrane and tonoplast, as well as the tonoplast H+-PPiase, provide the transmembrane proton motive force used by various secondary transporters. The widespread occurrence, taxonomically, of halophytes and the general paucity of information on the molecular regulation of tolerance mechanisms persuade us that research should be concentrated on a number of model species that are representative of the various mechanisms that might be involved in tolerance.

Oxidative stress: a concept in redox biology and medicine.

Abstract: “Oxidative stress” as a concept in redox biology and medicine has been formulated in 1985; at the beginning of 2015, approx. 138,000 PubMed entries show for this term. This concept has its merits and its pitfalls. Among the merits is the notion, elicited by the combined two terms of (i) aerobic metabolism as a steady-state redox balance and (ii) the associated potential strains in the balance as denoted by the term, stress, evoking biological stress responses. Current research on molecular redox switches governing oxidative stress responses is in full bloom. The fundamental importance of linking redox shifts to phosphorylation/dephosphorylation signaling is being more fully appreciated, thanks to major advances in methodology. Among the pitfalls is the fact that the underlying molecular details are to be worked out in each particular case, which is bvious for a global concept, but which is sometimes overlooked. This can lead to indiscriminate use of the term, oxidative stress, without clear relation to redox chemistry. The major role in antioxidant defense is fulfilled by antioxidant enzymes, not by small-molecule antioxidant compounds. The field of oxidative stress research embraces chemistry, biochemistry, cell biology, physiology and pathophysiology, all the way to medicine and health and disease research.

Mechanism of Salinity Tolerance in Plants: Physiological, Biochemical, and Molecular Characterization

Abstract: Salinity is a major abiotic stress limiting growth and productivity of plants in many areas of the world due to increasing use of poor quality of water for irrigation and soil salinization. Plant adaptation or tolerance to salinity stress involves complex physiological traits, metabolic pathways, and molecular or gene networks. A comprehensive understanding on how plants respond to salinity stress at different levels and an integrated approach of combining molecular tools with physiological and biochemical techniques are imperative for the development of salt-tolerant varieties of plants in salt-affected areas. Recent research has identified various adaptive responses to salinity stress at molecular, cellular, metabolic, and physiological levels, although mechanisms underlying salinity tolerance are far from being completely understood. This paper provides a comprehensive review of major research advances on biochemical, physiological, and molecular mechanisms regulating plant adaptation and tolerance to salinity stress.

Recoil-ion and electron momentum spectroscopy: reaction-microscopes

Abstract: Recoil-ion and electron momentum spectroscopy is a rapidly developing technique that allows one to measure the vector momenta of several ions and electrons resulting from atomic or molecular fragmentation. In a unique combination, large solid angles close to 4π and superior momentum resolutions around a few per cent of an atomic unit (a.u.) are typically reached in state-of-the art machines, so-called reaction-microscopes. Evolving from recoil-ion and cold target recoil-ion momentum spectroscopy (COLTRIMS), reaction-microscopes—the `bubble chambers of atomic physics'—mark the decisive step forward to investigate many-particle quantum-dynamics occurring when atomic and molecular systems or even surfaces and solids are exposed to time-dependent external electromagnetic fields. This paper concentrates on just these latest technical developments and on at least four new classes of fragmentation experiments that have emerged within about the last five years. First, multi-dimensional images in momentum space brought unprecedented information on the dynamics of single-photon induced fragmentation of fixed-in-space molecules and on their structure. Second, a break-through in the investigation of high-intensity short-pulse laser induced fragmentation of atoms and molecules has been achieved by using reaction-microscopes. Third, for electron and ion-impact, the investigation of two-electron reactions has matured to a state such that the first fully differential cross sections (FDCSs) are reported. Fourth, comprehensive sets of FDCSs for single ionization of atoms by ion-impact, the most basic atomic fragmentation reaction, brought new insight, a couple of surprises and unexpected challenges to theory at keV to GeV collision energies. In addition, a brief summary on the kinematics is provided at the beginning. Finally, the rich future potential of the method is briefly envisaged.