Effect of palladium and platinum salts on bacteriophage T4 and its isolated DNA]

The effect of palladium and platinum salts (K2PdCl4, K2PtCl4) on bacteriophage F4 and its isolated DNA in genetic transformation is investigated. Both compounds efficiently inactivated the phage and decreased the transforming activity of donor DNA. The palladium salt exhibited the higher activity. The palladium compounds inhibited the transforming activity of native donor DNA to a greater degree. No difference was observed in the degree of inactivation of the transforming activity of native and denatured DNA under the effect of platinum salt. It is suggested that the difference in the transforming activity of donor DNA treated with the tested compounds reflect the pattern of their interactions with nucleic acids.     

Slr4, a newly identified S-layer protein from marine Gammaproteobacteria,is a major biofilm matrix component

S-layers are paracrystalline proteinaceous lattices that surround prokaryotic cells, forming a critical interface between the cells and their extracellular environment. Here, we report the discovery of a novel S-layer protein present in the Gram-negative marine organism, Pseudoalteromonas tunicata D2. An uncharacterized protein (EAR28894) was identified as the most abundant protein in planktonic cultures and biofilms. Bioinformatic methods predicted a beta-helical structure for EAR28894 similar to the Caulobacter S-layer protein, RsaA, despite sharing less than 20% sequence identity. Transmission electron microscopy revealed that purified EAR28894 protein assembled into paracrystalline sheets with a unique square lattice symmetry and a unit cell spacing of ~9.1 nm. An S-layer was found surrounding the outer membrane in wild-type cells and completely removed from cells in an EAR28894 deletion mutant. S-layer material also appeared to be “shed” from wild-type cells and was highly abundant in the extracellular matrix where it is associated with outer membrane vesicles and other matrix components. EAR28894 and its homologs form a new family of S-layer proteins that are widely distributed in Gammaproteobacteria including species of Pseudoalteromonas and Vibrio, and found exclusively in marine metagenomes. We propose the name Slr4 for this novel protein family.     

Macroalgae and nutrients promote algal turf growth in the absence of herbivores

Coral Reefs - Closely cropped algal turfs are characteristic of healthy coral reefs, but unchecked growth can cause transitions into long sediment-laden turfs, which may be an alternative degraded...     

Sulfurtransferases and the content of cysteine, glutathione and sulfane sulfur in tissues of the frog Rana temporaria

L-cysteine desulfuration was examined in tissues of Rana temporaria, in October and January. The activities of 3-mercaptopyruvate sulfurtransferase (MPST), cystathionine gamma-lyase (CST) and rhodanese were primarily concentrated in frog liver and kidney. The values of CST and rhodanese activity, as well as sulfane sulfur compounds levels fell in the range characteristic of rat. For each of the investigated tissues changes noted in the enzymatic activities and in the level of glutathione (GSH), protein-bound cysteine (PbCys) and sulfane sulfur compounds were dependent on the month in which the determination was performed, and on the character of the tissue. In such tissues as the liver or gonads, high GSH levels and high activities of MPST (in the liver) or MPST and rhodanese (in the gonads) seemed to accompany protein biosynthesis during hibernation. PbCys, the level of which was consequently diminished in all tissues in January, compensated the absence of exogenous cysteine. A significantly reduced GSH level in the brain in January seemed to be correlated with decreased requirements of the tissue for this important natural antioxidant at diminished thyroid hormones levels in the serum and minimal oxygen consumption during the hibernation. In the kidney, the possible participation of sulfane sulfur compounds in detoxification processes requires elucidation, similarly as in protection against cellular oxidative stress at extremely low levels of GSH.     

Effect of mercury ions on cysteine metabolism in Xenopus laevis tissues

The effect of mercury ions on the level of cysteine, glutathione, sulfane sulfur, and on the activity of rhodanese, 3-mercaptopyruvate sulfurtransferase (MPST) and γ-cystathionase in brain, heart muscle, liver, kidneys, testes and skeletal muscle of adult Xenopus laevis was investigated. Frogs of both sexes were exposed for 7 or 14 days to 1.353mgL(-1) (ppm) of mercury chloride (HgCl(2)) dissolved in water. The activity of the investigated enzymes participating in cysteine metabolism depends on cysteine in their active sites. Mercury ions can bind to -SH groups and, therefore, lower the activity of enzymes and change the level of sulfane sulfur, a product of l-cysteine desulfuration. The effect of mercury was found to depend on the time of exposure and the kind of tissue. In the liver, the main site of glutathione biosynthesis, the ratio of GSH to GSSG was essentially unchanged. The total glutathione level was decreased after 7 days of exposure to mercury, similarly as the activity of rhodanese. Sulfane sulfur levels were significantly increased after a shorter duration, while they decreased after a longer time of exposure. The kidney, brain and testes were able to enhance the level of GSH, probably thanks to high γ-glutamyltranspeptidase activity. These tissues showed an increased value of GSH/GSSG ratio during the shorter exposure to mercury. The activity of sulfurtransferases was decreased, especially after the longer exposure to mercury. In the heart and skeletal muscle, the level of GSH, sulfane sulfur, and the activity of the investigated sulfurtransferases was diminished after 14 days of exposure to Hg. It can be concluded that the main mechanism of toxic Hg activity is generation of reactive oxygen species in cells due to depleted GSH level, and a decreased sulfurtransferases activity either by blocking or oxidation of their -SH groups, what in consequence results in a diminished sulfane sulfur levels in tissues, especially the heart and testes.     

Description of a new species of the genus Awaous Valenciennes, 1837 (Gobiiformes: Oxudercidae) from the middle stretch of the Mahanadi River,Odisha, India,with comments on the Awaous species from India

A new species of the genus Awaous (Oxudercidae), Awaous motla sp. nov., is described based on 18 specimens collected from the Mahanadi River near Sonepur, Subarnapur District, and 3 specimens from the same river near Boudh bridge, Boudh District of Odisha, India. This species is distinct from its congeners by having a combination of characteristics: relatively small eyes, diameter of 6.6–8.4 in head length (LH); robust and long snout, 2.0–2.6 in LH; eye diameter 2.7–4.1 in snout length; cephalic sensory pore system interrupted with eight pores; predorsal scales 13–15; longitudinal scale series 55–58; gill rakers 2 + 1 + (6–7) on the first gill arch; teeth small, conical, and in a single row on the upper jaw and multiserial (2–3) on the lower jaw. This species is also differentiated from some of its congeners in the nucleotide composition of the cytochrome c oxidase I gene by 8.3%–13.8% Kimura two-parameter (K2P) distance and belongs to a separate cluster in the maximum likelihood tree analysis. This finding is also supported by the species delimitation analysis based on Assemble Species by Automatic Partitioning. The new species holds high commercial value in its locality and needs special conservation attention for sustainable utilization.     

A novel series of pyrazole-platinum(II) complexes as potential anti-cancer agents that induce cell cycle arrest and apoptosis in breast cancer cells

Six novel compounds of platinum(II) with pyrazole derivatives PtPz1–PtPz6 were synthesised and characterised (PtPz1 - [Pt₂N-hydroksymethyl-3,5-dimethylpyrazole₄(berenil)₂]Cl₄; PtPz2 - [Pt₂3,5-dimethylpyrazole₄(berenil)₂]Cl₄; PtPz3 - [Pt₂3,4-dimethylpyrazole₄(berenil)₂]Cl₄; PtPz4 - [Pt₂pyrazole₄(berenil)₂]Cl₄; PtPz5- [Pt₂5-methylpyrazole₄(berenil)₂]Cl₄; PtPz6 - [Pt₂N-ethylpyrazole₄(berenil)₂]Cl₄). The cytotoxic activity of these complexes against MCF-7 and MDA-MB-231 breast cancer cell lines was determined using the MTT assay. Evaluation of apoptosis induction was done with the Annexin V-fluorescein isothiocyanate/propidium iodide assay. In addition, using a flow cytometer, we determined the influence of test compounds on the cell cycle and caspase-3, -8, and -9 activity. The obtained results of caspase activity were confirmed by cell imaging. Moreover, using the flow cytometer, the effects of the test compounds on mitochondrial potential change were assessed. The test results showed that novel pyrazole-platinum(II) complexes exhibited stronger anti-proliferative activity against two breast cancer cell lines than reference cisplatin. Compounds PtPz1, PtPz2, and PtPz3 with methyl substituents at the pyrazole ring showed stronger activity than pyrazole or ethylpyrazole containing complexes. Studies have shown that inhibition of cell survival occurs by arresting the G1 cell cycle and inducing apoptosis. Our analysis associated with the response of MCF-7 and MDA-MB-231 cells to treatment with PtPz1–PtPz6 showed that it leads the cells through the external and intrinsic (mitochondrial) apoptotic pathway via indirect DNA damage.