Processes of plant colonization by Methylobacterium strains and some bacterial properties

The pink-pigmented facultative methylotrophic bacteria (PPFMB) of the genus Methylobacterium are indespensible inhabitants of the plant phyllosphere. Using maize Zea mays as a model, the ways of plant colonization by PPFMB and some properties of the latter that might be beneficial to plants were studied. A marked strain, Methylobacterium mesophilicum APR-8 (pULB113), was generated to facilitate the detection of the methylotrophic bacteria inoculated into the soil or applied to the maize leaves. Colonization of maize leaves by M. mesophilicum APR-8 (pULB113) occurred only after the bacteria were applied onto the leaf surface. In this case, the number of PPFMB cells on inoculated leaves increased with plant growth. During seed germination, no colonization of maize leaves with M. mesophilicum cells occurred immediately from the soil inoculated with the marked strain. Thus, under natural conditions, colonization of plant leaves with PPFMB seems to occur via soil particle transfer to the leaves by air. PPFMB monocultures were not antagonistic to phytopathogenic bacteria. However, mixed cultures of epiphytic bacteria containing Methylobacterium mesophilicum or M. extorquens did exhibit an antagonistic effect against the phytopathogenic bacteria studied (Xanthomonas camprestris, Pseudomonas syringae, Erwinia carotovora, Clavibacter michiganense, and Agrobacterium tumifaciens). Neither epiphytic and soil strains of Methylobacterium extorquens, M. organophillum, M. mesophilicum, and M. fujisawaense catalyzed ice nucleation. Hence, they cause no frost injury to plants. Thus, the results indicate that the strains of the genus Methylobacterium can protect plants against adverse environmental factors.     

Non-Hebbian Learning Implementation in Light-Controlled Resistive Memory Devices

Non-Hebbian learning is often encountered in different bio-organisms. In these processes, the strength of a synapse connecting two neurons is controlled not only by the signals exchanged between the neurons, but also by an additional factor external to the synaptic structure. Here we show the implementation of non-Hebbian learning in a single solid-state resistive memory device. The output of our device is controlled not only by the applied voltages, but also by the illumination conditions under which it operates. We demonstrate that our metal/oxide/semiconductor device learns more efficiently at higher applied voltages but also when light, an external parameter, is present during the information writing steps. Conversely, memory erasing is more efficiently at higher applied voltages and in the dark. Translating neuronal activity into simple solid-state devices could provide a deeper understanding of complex brain processes and give insight into non-binary computing possibilities.     

Alterations of the WNT7A Gene in Clear Cell Renal Cell Carcinomas

WNT7A (wingless-type MMTV integration site family, member 7A) is a known tumor suppressor gene of non-small cell lung carcinomas (NSCLC) and is frequently inactivated due to CpG-island hypermethylation in human cancers. The members of WNT family are involved in cell signaling and play crucial roles in cancer development. In the present work hypermethylation of the WNT7A gene was detected in 66% (29/44) of analyzed clear cell renal cell carcinomas (RCCs) using methyl-specific PCR (MSP). Moreover, bisulfite sequencing confirmed intensive hypermethylation of the 5′-CpG island of the WNT7A gene. Methylation analysis revealed positive correlations between tumor stage, Fuhrman nuclear grade and WNT7A hypermethylation. Additionally, restoration of WNT7A gene expression in the A498 cell line by 5-aza-2′-deoxycytidine treatment confirmed a direct contribution of hypermethylation in silencing of the WNT7A gene. High frequency of loss of heterozygosity (LOH) was demonstrated on chromosome 3p25 in regions surrounding the WNT7A gene. The frequent down-regulation of WNT7A gene expression was detected in 88% (15/17) of clear cell RCCs. We have also shown that the WNT7A gene possesses tumor suppression function by colony-formation and cell proliferation assays in RCC cell lines. In summary, the WNT7A gene is inactivated by genetic/epigenetic alterations in clear cell RCC and demonstrates tumor suppressor properties.     

The approximate entropy of the electromyographic signals of tremor correlates with the osmotic fragility of human erythrocytes

Background  

The main problem of tremor is the damage caused to the quality of the life of patients, especially those at more advanced ages. There is not a consensus yet about the origins of this disorder, but it can be examined in the correlations between the biological signs of aging and the tremor characteristics.     

Evaluation of biological effects of cobalt-nanocomposites with the use of biochemical markers of bivalve mollusk Anodonta cygnea

Intensive implementation of nanomaterials requires development of novel methods for evaluation of their potential ecotoxicity. The aim of our study was to identify specific characteristics of the effect of cobalt-nanocomposite (Co-NC) on the molecular stress-responsive system in the digestive gland of bivalve mollusk Anodonta cygnea. Nanocomposite was synthesized by mixing alcohol solution of copolymer N-vinylpirrolidone, 5-(tret-butylperoxy)-5-methyl-1-hexene-3-yne and dimethylaminoethylmetacrylate and cobalt (II) chloride. After 14 days of the mollusk exposure in the presence of Co-NC, CoCl, or corresponding polymer substance it was shown that the Co-NC, in contrast to other agents, does not cause an oxidative stress due to the superoxide dismutase activity, metallotioneins (MTs) level, glutathione redox index and oxyradical production. Multivariate analysis confirmed specific features of the Co-NC's effect related to an enhanced expression of MTs, while CoCl2 activated lactate dehydrogenate and oxyradical production, and polymer substance enhanced glutathione transferase activity.     

Population-related peculiarities of molecular stress-responsive systems of bivalve mollusk under the effect of tetrazine pesticide

Tetrazine pesticides are widely used for the treatment of crops in most EU countries and USA. However, data about the effect of environmentally realistic concentrations of biocides on the molecular stress response system in non-target organisms are absent. The aim of our study was the comparison of adaptive capability of bivalve mollusk Anodonta cygnea from two populations under the effects of commercial pesticide Apollo in terms of biochemical parameters of the digestive gland. The differences between parameters of oxidative stress and glutathione transferase activity in specimens of control groups from clean (I group) and polluted (B group) areas have been shown. Under the effect of Apollo, the level of protein carbonyls and microsomal oxidation processes increased, and the level of metallothioneins and oxyradical formation decreased in the specimens from both populations. However, the treatment provoked the activation of antioxidant processes in the I group and their inhibition in B group. Potentially the injury of cellular thiols, glutathione and metallothioneins, seems to be key point of tetrazine pesticides toxicity.     

A calcium channel blocker nifedipine distorts the effects of nano-zinc oxide on metal metabolism in the marsh frog Pelophylax ridibundus

Global decline of amphibian populations causes particular concern about their vulnerability to novel environmental pollutants, including engineering nanomaterials and pharmaceutical products. We evaluated the bioavailability of nanoform of zinc oxide (n-ZnO) in frog Pelophylax ridibundus and determined whether co-exposure to a common pharmaceutical, a calcium-channel blocker nifedipine (Nfd) can affect this bioavailability. Male frogs were exposed for 14 days to the tap water (Control) and n-ZnO (3.1 μM), Zn²⁺ (3.1 μM, as a positive control for n-ZnO exposures), Nfd (10 μM), and combination of n-ZnO and Nfd (n-ZnO + Nfd) in environmentally-relevant concentration. Exposure to Zn²⁺ or n-ZnO led to up-regulation of metal-binding proteins, metallothioneins (MTs) in the liver and Zn-carrying vitellogenin-like proteins in the blood plasma. Notably, upregulation of MTs by Zn²⁺ or n-ZnO exposures combined with increased binding of Zn and Cu to MTs. This was associated with the more reducing conditions in the liver tissue indicated by elevated lactate to pyruvate ratio. Nfd suppressed the binding of Zn and Cu to MTs and led to a decrease in Lactate/Pyruvate ratio and elevated protein carbonylation indicating pro-oxidant conditions. Redox status parameters were not directly related to DNA fragmentation, nuclear abnormalities or suppression of cholinesterase activity indicating that factors other than oxidative stress are involved in cytotoxicity of different pollutants and their combinations. Furthermore, activity of Phase I biotransformation enzyme (CYP450 oxidase measured as EROD) was elevated in Nfd-containing exposures and in Zn²⁺ exposed frogs. Tyrosinase-like activity in the frog liver was strongly stimulated by Zn²⁺ but suppressed by n-ZnO, Nfd and n-ZnO + Nfd. These findings show that Nfd modulates homeostasis of essential metals in amphibians and emphasize that physiological consequences of combined n-ZnO and Nfd exposures are difficult to predict based on the mechanisms of single stressors.     

Metal-binding functions and antioxidant properties in human thyroid gland under iodine deficient nodular colloidal goiter

Copper and zinc levels in the tissue of thyroid gland (TG) and their metal-binding proteins metallothioneins (MT) as well as state of the antioxidant system in persons that had no thyroid disease and patients with endemic iodine deficiency nodular colloidal goiter has been investigated. In the patients with thyroid disease, oxidative damage was indicated despite elevated levels of MT-SH and glutathione, and elevated copper and decreased zinc concentration in TG tissue. MTs partly bound the excess of copper but its concentration in the unbound to MT form was two-fold compared to the control value.     

Effect of zinc ions, manganese and lead ions on the thermostable proteins of carp liver

Effect of comparatively low concentration of the zinc, manganese, lead ions (0.1, 0.13 and 0.01 mg/l respectively) on the thermostable proteins (TP) of the carp liver after fish incubation for 14 days was studied. It is revealed that about 30 of zinc, 40% of manganese and 6% of lead were bound in the TP solution. The results of chromatography on Sephadex G-75 show, that the metallothionein-like proteins (MT, M-6 kDa) were the primary metal-binding proteins among the TP for zinc and manganese, and the heavy fraction of TP (M-60 kDa)--for lead. Under the action of each of the metallions its content in the TP is significantly increased. The distribution of metals among TP compounds is similar to that in the control. The metals action causes specific changes of the heavy fraction properties (UV spectrum, SH-groups content). The properties of MT do not change significantly under the control value.