New Data on Soft Sculpin Malacocottus zonurus (Psychrolutidae) from the Northwestern Bering Sea

Journal of Ichthyology - Biological features of soft sculpin Malacocottus zonurus (Psychrolutidae) are described based on the analysis of samples from bottom trawl catches in the northwestern...     

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.     

Induction and genetic identification of a callus‐like growth developed in the brown alga Fucus vesiculosus

Induction of an axenic filamentous‐like callus growth from the brown algae Fucus vesiculosus is described. Different treatments were investigated in various combinations to develop axenic cultures based on identification of surface symbionts via 18S ribosomal RNA. Moreover, viability was confirmed after such processes by 2,3,5‐triphenyl tetrazolium chloride assay that demonstrated an average viability of 29%, relative to nonsterilized explants. After six weeks of a phototrophic cultivation on artificial sea water‐12‐nitrilotriacetic acid (0.5% w/v agar), a filamentous‐like callus growth was observed, which was identified genetically through its mitochondrial DNA after subculturing. Achievement of confirmed marine callus cultures might enrich old previously established blue biotechnology techniques and open new chances for cultivation of brown algae for production of good manufacturing practice‐compliant bioproducts.     

The role of phosphate groups in the VS ribozyme-substrate interaction

The VS ribozyme trans-cleavage substrate interacts with the catalytic RNA via tertiary interactions. To study the role of phosphate groups in the ribozyme–substrate interaction, 18 modified substrates were synthesized, where an epimeric phosphorothioate replaces one of the phosphate diester linkages. Sites in the stem–loop substrate where phosphorothioate substitution impaired reaction cluster in two regions. The first site is the scissile phosphate diester linkage and nucleotides downstream of this and the second site is within the loop region. The addition of manganese ions caused recovery of the rate of reaction for phosphorothioate substitutions between A621 and A622 and U631 and C632, suggesting that these two phosphate groups may serve as ligands for two metal ions. In contrast, significant manganese rescue was not observed for the scissile phosphate diester linkage implying that electrophilic catalysis by metal ions is unlikely to contribute to VS ribozyme catalysis. In addition, an increase in the reaction rate of the unmodified VS ribozyme was observed when a mixture of magnesium and manganese ions acted as the cofactor. One possible explanation for this effect is that the cleavage reaction of the VS ribozyme is rate limited by a metal dependent docking of the substrate on the ribozyme.     

Pulmonary xanthine oxidase activity of rats exposed to prolonged immobilization stress

This study was designed to study xanthine oxidase (XO) and xanthine dehydrogenase (XD) activity in the lung of rats exposed to prolonged restraining immobilization stress. Immobilization caused more than twofold increase of xanthine oxidase activity in the rat lung. The activity of xanthine oxidase decreased in lung homogenates incubated at -20 degrees C for 24 h. The same incubation of homogenates from control rats caused a non-significant increase of the activity. No measurable NAD(+)-dependent xanthine dehydrogenase activity could be established in the lungs of both control rats and rats subjected to immobilization. All rats revealed methylene blue-dependent xanthine dehydrogenase activity which was more than two-times higher in the immobilized animals. Incubation at -20 degrees C for 24 h increased the methylene blue-dependent xanthine dehydrogenase activity in homogenates from control rats and decreased the enzyme activity in homogenates from immobilized rats. A working hypothesis was proposed for the sequence of events explaining the results obtained: XO-catalyzed generation of activated oxygen species may take place in the initiation of lipid peroxidation in the lung of rats immobilized for prolonged periods of time.     

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.     

Gestational choline deficiency causes global and Igf2 gene DNA hypermethylation by up-regulation of Dnmt1 expression

During gestation there is a high demand for the essential nutrient choline. Adult rats supplemented with choline during embryonic days (E) 11-17 have improved memory performance and do not exhibit age-related memory decline, whereas prenatally choline-deficient animals have memory deficits. Choline, via betaine, provides methyl groups for the production of S-adenosylmethionine, a substrate of DNA methyltransferases (DNMTs). We describe an apparently adaptive epigenomic response to varied gestational choline supply in rat fetal liver and brain. S-Adenosylmethionine levels increased in both organs of E17 fetuses whose mothers consumed a choline-supplemented diet. Surprisingly, global DNA methylation increased in choline-deficient animals, and this was accompanied by overexpression of Dnmt1 mRNA. Previous studies showed that the prenatal choline supply affects the expression of multiple genes, including insulin-like growth factor 2 (Igf2), whose expression is regulated in a DNA methylation-dependent manner. The differentially methylated region 2 of Igf2 was hypermethylated in the liver of E17 choline-deficient fetuses, and this as well as Igf2 mRNA levels correlated with the expression of Dnmt1 and with hypomethylation of a regulatory CpG within the Dnmt1 locus. Moreover, mRNA expression of brain and liver Dnmt3a and methyl CpG-binding domain 2 (Mbd2) protein as well as cerebral Dnmt3l was inversely correlated to the intake of choline. Thus, choline deficiency modulates fetal DNA methylation machinery in a complex fashion that includes hypomethylation of the regulatory CpGs within the Dnmt1 gene, leading to its overexpression and the resultant increased global and gene-specific (e.g. Igf2) DNA methylation. These epigenomic responses to gestational choline supply may initiate the long term developmental changes observed in rats exposed to varied choline intake in utero.     

Involvement of oxidative stress and caspase 2-mediated intrinsic pathway signaling in age-related increase in muscle cell apoptosis in mice

Apoptosis has been implicated as a mechanism of loss of muscle cells in normal aging and plays an important role in age-related sarcopenia. To test the hypothesis that caspase 2 and c-Jun NH₂-terminal kinase (JNK)-mediated intrinsic pathway signaling contribute to skeletal muscle cell apoptosis in aging, we compared activation of caspase 2 and JNK and the in vivo expression of 4-hydroxynonenal protein adducts (4-HNE), inducible nitric oxide synthase (iNOS), glucose-6-phosphate dehydrogenase (G6PDH), B-cell lymphoma-2 (BCL-2), BAX, and phospho-BCL-2 in gastrocnemius muscles of young (5 months old) and old (25 months old) mice. A distinct age-related increase in 4-HNE and iNOS expression was readily detected in mice. Increased oxidative stress and iNOS induction were further accompanied by a decrease in G6PDH expression, activation of caspase 2 and JNK, and inactivation of BCL-2 through phosphorylation at serine 70, and caspase 9 activation. Regression analysis further revealed that increased muscle cell death in aging was significantly correlated with changes in the levels of these molecules. Taken together, our data indicate that caspase 2 and JNK-mediated intrinsic pathway signaling is one of the mechanisms involved in age-related increase in muscle cell apoptosis.     

Differences between Ca2+ and Mg2+ in DNA binding and release by the SfiI restriction endonuclease: implications for DNA looping

Many enzymes acting on DNA require Mg²⁺ ions not only for catalysis but also to bind DNA. Binding studies often employ Ca²⁺ as a substitute for Mg²⁺, to promote DNA binding whilst disallowing catalysis. The SfiI endonuclease requires divalent metal ions to bind DNA but, in contrast to many systems where Ca²⁺ mimics Mg²⁺, Ca²⁺ causes SfiI to bind DNA almost irreversibly. Equilibrium binding by wild-type SfiI cannot be conducted with Mg²⁺ present as the DNA is cleaved so, to study the effect of Mg²⁺ on DNA binding, two catalytically-inactive mutants were constructed. The mutants bound DNA in the presence of either Ca²⁺ or Mg²⁺ but, unlike wild-type SfiI with Ca²⁺, the binding was reversible. With both mutants, dissociation was slow with Ca²⁺ but was in one case much faster with Mg²⁺. Hence, Ca²⁺ can affect DNA binding differently from Mg²⁺. Moreover, SfiI is an archetypal system for DNA looping; on DNA with two recognition sites, it binds to both sites and loops out the intervening DNA. While the dynamics of looping cannot be measured with wild-type SfiI and Ca²⁺, it becomes accessible with the mutant and Mg²⁺.     

Dye affinity chromatography for fast and simple purification of fucoidan from marine brown algae

Fucoidan is a sulfated polysaccharide with promising pharmacological applications. Due to its medicinal properties, there is a demand for a separation technique that yields a high purification grade. Here, we present a novel purification tool for recovering fucoidan from the marine brown macroalgae Fucus vesiculosus. The developed method is based on amino‐derivatized Sepabeads^® EC‐EA. The beads were modified with toluidine blue (TB), a thiazine derivative, to exploit the strong donor acceptor interactions between the cationic dye and the anionic polysaccharide. The adsorption kinetics and the binding capacity of the resin were analyzed. A Sips model was used to approximate the adsorption isotherm, resulting in a maximum capacity of 127.7 mg fucoidan per g adsorbent. Investigation of the effect of adsorption step's pH on purity and chemical structure was performed by TB and Fourier transform infra‐red spectroscopy assays. Results showed that adsorption at pH 1 and 6 had negligible effects on fucoidan's chemical structure. However, purity was actually improved by 1.55‐ and 1.69‐fold at pH 1 and 6, respectively, with an average yield of 5 g/100 g dried algae powder. In contrast, only a 1.46‐fold increment was observed in fucoidan purified by the traditional method at pH 2, with a yield of 7.5 g/100 g dried algae powder. Furthermore, fucoidan purified by this method at pH 6 complies with, or even exceeds the quality of the commercially available (≥95% pure) fucoidan (Sigma‐Aldrich^®) with respect to molecular weight and sulfur content. Therefore, dye affinity chromatography provides more advantages than the classically used techniques for fucoidan purification.