Plant virus infection development as affected by heavy metal stress

The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants.     

Extramedullary hematopoiesis in a case of benign mixed mammary tumor in a female dog: cytological and histopathological assessment

Backgroud  

Extramedullary hematopoiesis (EMH) is defined as the presence of hematopoietic stem cells such as erythroid and myeloid lineage plus megakaryocytes in extramedullary sites like liver, spleen and lymph nodes and is usually associated with either bone marrow or hematological disorders. Mammary EMH is a rare condition either in human and veterinary medicine and can be associated with benign mixed mammary tumors, similarly to that described in this case.     

Study of Mutagenic Activity of Fullerene and Some of Its Derivatives Using His+ Reversions of Salmonella typhimurium as an Example

The influence of three new derivatives of fullerene C₆₀ ([61]dimethoxyphosphoryl[61]carbethoxy-methano[60]fullerene, [61](dimethoxyphosphoryl[61]carbmethoxy-methanofullerene, and 1-methyl-2-(3,5-ditretbutyl-4-hydroxy-phenyl),3,4-fulleropyrrolidine) on the appearance of His+ reversions in the Salmonella typhimurium strain BA13 was studied. It was ascertained that the effect of fullerene derivatives on the occurrence of mutations depends on the type of the molecular group with which fullerene interacts. The biological effect is determined not only by the action of the group associated with fullerene. The dependence between the mutagenic effect and properties of the solvents was detected. Exposure to visible light of the culture treated with fullerene derivatives was found to have an antimutagenic effect in the case of [61]dimethoxyphosphoryl[61]carbethoxy-methanofullerene[60]. For two other derivatives, the differences between experimental and control variants were statistically nonsignificant.     

Water-soluble polyol-methanofullerenes as mitochondria-targeted antioxidants: Mechanism of action

The mechanism of an antioxidant action of water-soluble polyol – methanofullerenes C₆₀[C₉H₁₀O₄(OH)₄]₆ and C₆₀[C₁₃H₁₈O₄(OH)₄]₆ as the mild uncouplers of an oxidative phosphorylation and respiration is postulated. According to this mechanism, hydroxyl group of methanofullerenols can be protonated under excess of protons in the intermembrane space of hyperpolarized mitochondria. Protonation of fullerene derivatives is confirmed by the decrease in their negative Zeta potential in the pH below 5.4. Heavily protonated methanofullerenols become positively charged and move into the mitochondrial matrix. As a consequence, the proton gradient is dissipated, which causes a decrease in mitochondrial transmembrane potential (ΔΨ_m) and reduction in ROS production.     

Action of hexaamminecobalt on the activity of Serratia marcescens nuclease

Using CD spectroscopic and kinetic analysis, a refined mechanism of Co(NH₃) ₆ ³⁺ action on activity of Serratia marcescens nuclease was elucidated. The mechanism was identical with previously found mechanisms of Mg²⁺ and C₇H₅O₂Hg⁺. Similarly to Mg²⁺ and C₇H₅O₂Hg⁺, Co(NH₃) ₆ ³⁺ binding to the DNA substrate induced changes in the secondary structure which resulted in changes of the enzymatic activity of the S. marcescens nuclease. Upon binding of 0.03 Co(NH₃) ₆ ³⁺ per DNA phosphate, highly polymerized DNA displayed A-form characteristics. The DNA transition from B-form to A-form intermediate was followed by a decrease of the nuclease activity. The diminishing nuclease activity was consistent with diminishing values of Km and Kcat. Co(NH₃)₆ ³⁺ binding to the highly polymerized DNA caused a 1.7–2.8-fold decrease in Km, and 13.3–19.9 decrease in Vmax compared with Mg-DNA complex. A vast excess of Co(NH₃)₆ ³⁺ did not affect the activity of S. marcescens nuclease if the DNA in the assay mixture remained in its B-form conformation. Preincubation of S. marcescens nuclease with Co(NH₃)₆ ³⁺ did not influence the tertiary structure of the enzyme.     

Studies on the partial characterization of extracted glycosaminoglycans from fish waste and its potentiality in modulating obesity through in-vitro and in-vivo

Glycoconjugate Journal - Glycosaminoglycans (GAGs) are bioactive polysaccharides or glycoconjugates found in the fish waste having significant health impacts. In the present study it has been...     

Metal binding induces conversion of B- to the hybrid B-Z-form in natural DNA

Highly polymerized herring testis DNA of the random nucleotide sequence has been studied in solution by circular dichroism and ultra-violet absorption spectrometry under various experimental conditions. At low temperature upon addition of 0.05M NaCl or 1.15M MgSO(4) the DNA formed a helix that belonged to the B-family. As the temperature was increased a transition from the pure B- to the hybrid B-Z-form occurred in the presence of 1.15M MgSO(4). This transition occurred over a large range of temperatures and corresponded to a non-cooperative conformational change. A similar DNA transition was induced with 0.098mM Co(NH(3))(6)Cl(3). However, in the presence of 5.3M NaCl the DNA conformation was not similar to that observed in 1.15M MgSO(4) or 0.098mM Co(NH(3))(6)Cl(3) independently on the environmental temperature. In 5.3M NaCl the DNA is thought to undergo a transition from one to another right-handed conformation that could be intermediate partially dehydrated conformer arising on the first step in the sequential transition to the dehydration of the polynucleotide. Our results show that a realistic model of native DNA, bearing Z-tracts embedded in B-helixes, can be obtained upon binding of alkaline earth or transition metals.     

Study of the Mechanism of Action of p-Chloromercuribenzoate on Endonuclease from the Bacterium Serratia marcescens

The mechanism of action of p-chloromercuribenzoate (PCMB) on Serratia marcescens nuclease was investigated. The analysis showed that PCMB forms complexes with DNA. Binding of C₇H₅O₂Hg⁺ to DNA changes the secondary structure of the DNA. These changes alter the enzymatic activity of S. marcescens nuclease, which was previously found to be sensitive to the secondary structure of the substrates. The nuclease activity was either suppressed or stimulated in the presence of PCMB depending on the C₇H₅O₂Hg⁺ to nucleotide equivalent ratio. Binding of C₇H₅O₂Hg⁺ to DNA did not form an abortive enzyme–substrate complex. Binding of Mg²⁺ to the C₇H₅O₂Hg–DNA complex caused appropriate changes in secondary structure of the substrate. Since Mg²⁺ and C₇H₅O₂Hg⁺, though differing in the type of metal cation, are similar in their mechanisms of influence on enzymatic activity of S. marcescens nuclease, the identity of other metal-containing effectors in their mechanism of action on Serratia marcescens nuclease is assumed.     

Yield and quality of forage maize (<i>Zea mays</i> L.) with different levels of subsurface drip irrigation and plant density

The scarcity of water in arid and semiarid regions of the world is a problem that every day increases by climate change. The subsurface drip irrigation (SDI) and changes in population density of plants are alternatives that can be used to make a sustainable use of water. Therefore, the objectives of this study were to determine the combination that allows for an increased corn performance and efficient use of water without losing the quality of forage. Three different irrigation levels were applied through a system of a SDI at three different densities of forage maize plants in an arid region. The results demonstrated that by applying different levels of water, either enough or lack of soil moisture is created, which is directly reflected in crop yield, and its determining variables such as green forage and dry matter yield, and nutritional quality. The irrigation level to a 100% of potential evapotranspiration (PET), at a density of 80000 plants/ha, increased yield of green forage to 57664 kg/ha; crude protein was 8.59%, while the rest of the quality parameters decreased. This study allowed to conclude that the irrigation level was the major factor in the response of the crop.