A simple quantitative method for the estimation of free ecto-sulfhydryl groups of spermatozoa

A simple rapid quantitative method has been developed for the estimation of sperm ecto-SH groups on the basis of their high affinity binding to the mercurial: [203Hg]p-chloromercuriphenylsulfonic acid (PCMPS) used as a surface probe. The thiol reagent did not penetrate the sperm plasma membrane, as evidenced by the extremely rapid time course of the binding reaction and undetectable uptake of [203Hg]PCMPS by intact goat spermatozoa. The binding reaction was not due to contaminating broken or damaged cells, if any. The method consists of incubating of highly motile goat spermatozoa with PCMPS in a modified Ringer solution at 37 degrees C for 5 min, agglutination of the labelled cells with polyethyleneimine (100 micrograms/ml) and filtration and washing of the cell suspension through Whatman No. 1 filter discs under mild vacuum. The binding interaction is proportional to cell concentration, specific and saturable at 50 microM PCMPS. The method is capable of estimating free ecto-SH as low as 25 pmoles. Spermatozoa possess 286 +/- 61 pmoles of free ecto-SH groups/10(6) cells. Scatchard analysis showed the presence in goat spermatozoa of multiple classes of ecto-SH groups differing in their affinity for PCMPS.     

Morphological and Molecular Identification of Spirometra Tapeworms (Cestoda: Diphyllobothriidae) from Carnivorous Mammals in the Serengeti and Selous Ecosystems of Tanzania

Spirometra tapeworms (Cestoda: Diphyllobothriidae) collected from carnivorous mammals in Tanzania were identified by the DNA sequence analysis of the mitochondrial cytochrome c oxidase subunit 1 (cox1) and internal transcribed spacer 1 (ITS1), and by morphological characteristics. A total of 15 adult worms were collected from stool samples and carcasses of Panthera leo, Panthera pardus, and Crocuta crocuta in the Serengeti and Selous ecosystems of Tanzania. Three Spirometra species: S. theileri, S. ranarum and S. erinaceieuropaei were identified based on morphological features. Partial cox1 sequences (400 bp) of 10 specimens were revealed. Eight specimens showed 99.5% similarity with Spirometra theileri ({"type":"entrez-nucleotide","attrs":{"text":"MK955901","term_id":"1796114604","term_text":"MK955901"}}MK955901), 1 specimen showed 99.5% similarity with the Korean S. erinaceieuropaei and 1 specimen had 99.5% similarity with Myanmar S. ranarum. Sequence homology estimates for the ITS1 region of S. theileri were 89.8% with S. erinaceieuropaei, 82.5% with S. decipiens, and 78.3% with S. ranarum; and 94.4% homology was observed between S. decipiens and S. ranarum. Phylogenetic analyses were performed with 4 species of Spirometra and 2 species of Dibothriocephalus (=Diphyllobothrium). By both ML and BI methods, cox1 and ITS1 gave well supported, congruent trees topology of S. erinaceieuropaei and S. theileri with S. decipiens and S. ranarum forming a clade. The Dibothriocephalus species were sisters of each other and collectively forming successive outgroups. Our findings confirmed that 3 Spirometra species (S. theileri, S. ranarum, and S. erinaceieuropaei) are distributed in the Serengeti and Selous ecosystems of Tanzania.     

Partial Characterization of Small Plasmids fromCorynebacterium renale

A naphthalene-degrading strain of corynebacteria, Corynebacterium renale, harbors multiple small plasmids designated pCR1, pCR2, pCR3, and pCR4 with sizes of 1.4, 3.2, 4.4, and 5.7 kb, respectively. Plasmid pCR1 of 1.4 kb is the smallest plasmid reported in this group of bacteria and is present in high copy number. Attempts to clone whole pCR1 in Escherichia coli were unsuccessful but two of its fragments (750 and 650 bp) could be separately cloned in it. The 4.4-kb plasmid, pCR3, bears considerable restriction pattern similarity to a 4.4-kb plasmid belonging to the pBL1 group of cryptic plasmid of corynebacteria but has no sequence homology, suggesting that pCR3 represents a new member of the 4.4-kb group of corynebacterial plasmids.     

Prioritizing Tiger Conservation through Landscape Genetics and Habitat Linkages

Even with global support for tiger (Panthera tigris) conservation their survival is threatened by poaching, habitat loss and isolation. Currently about 3,000 wild tigers persist in small fragmented populations within seven percent of their historic range. Identifying and securing habitat linkages that connect source populations for maintaining landscape-level gene flow is an important long-term conservation strategy for endangered carnivores. However, habitat corridors that link regional tiger populations are often lost to development projects due to lack of objective evidence on their importance. Here, we use individual based genetic analysis in combination with landscape permeability models to identify and prioritize movement corridors across seven tiger populations within the Central Indian Landscape. By using a panel of 11 microsatellites we identified 169 individual tigers from 587 scat and 17 tissue samples. We detected four genetic clusters within Central India with limited gene flow among three of them. Bayesian and likelihood analyses identified 17 tigers as having recent immigrant ancestry. Spatially explicit tiger occupancy obtained from extensive landscape-scale surveys across 76,913 km² of forest habitat was found to be only 21,290 km². After accounting for detection bias, the covariates that best explained tiger occupancy were large, remote, dense forest patches; large ungulate abundance, and low human footprint. We used tiger occupancy probability to parameterize habitat permeability for modeling habitat linkages using least-cost and circuit theory pathway analyses. Pairwise genetic differences (F _ST) between populations were better explained by modeled linkage costs (r>0.5, p<0.05) compared to Euclidean distances, which was in consonance with observed habitat fragmentation. The results of our study highlight that many corridors may still be functional as there is evidence of contemporary migration. Conservation efforts should provide legal status to corridors, use smart green infrastructure to mitigate development impacts, and restore habitats where connectivity has been lost.     

Effect of cadmium on tissue glutathione and glutathione peroxidase in rats: influence of selenium supplementation.

Administration of cadmium (2.5 mg/kg, sc on alternate days for 3 weeks) to male albino rats led to significant accumulation of cadmium and metallothionein in the liver and kidneys. The activity of glutathione peroxidase was significantly decreased whereas, the concentration of glutathione was increased in these organs. Glycine-l-14C incorporation studies showed enhanced synthesis of glutathione in kidney but not in the liver. Selenium supplementation (1 mg/kg/day orally) failed to prevent these cadmium-induced changes, although it resulted in very high accumulation of selenium in these organs indicating the formation of cadmium-selenium complex.     

Effect of cyanophage N-1 infection on the synthesis and stability ofNostoc muscorum nitrate reductase

The control operative on the nitrate reductase enzyme system of host cyanobacteriumNostoc muscorum was studied after being infected with the cyanophage N-1. Phage infection lifted the host nitrate reductase activity level via accelerating the enzyme synthesis. It was found that the phage-mediated increase in the molybdenum cofactor synthesis was a major contributing factor for apparent elevated nitrate reductase level of the host. This process was inhibited in the presence of erythromycin and tungsten, the inhibitors of protein synthesis and new nitrate reductase synthesis respectively. While the preformed nitrate reductase of healthy cyanobacterium was inhibited by hydrogen peroxide, an oxidizing photosynthetic product, the same enzyme of infected cells remained virtually insensitive to this inhibitor. These data suggest involvement of new nitrate reductase synthesis and its resistance to oxidative inactivation as joint factors controlling the characteristic high enzyme level of host cyanobacterium.     

Bioenergetic consequences of protein overexpression in Saccharomyces cerevisiae

Summary Some bioenergetic consequences of overexpression of plasmid-encoded homologous (phosphoglycerate kinase), and heterologous (prochymosin), protein in S. cerevisiae strains grown in chemostat culture have been investigated. Both overexpressing strains were found to exhibit similar fermentation patterns despite a 10-fold difference in product expression levels. Biomass yields were lower than those for a control strain, and the onset of oxido-fermentative metabolism occurred at a lower dilution rate. A marked rise in cellular ATP content with increasing dilution rate during oxidative growth was observed in the strain overexpressing yeast phosphoglycerate kinase (PGK); this at present cannot be adequately explained. The inorganic phosphate content of the overexpressing strains was higher than that of the control and the phosphorylation potential of the prochymosin expressing strain was up to 10-fold lower than both the control and PGK overexpressing strains. It is proposed that expression of heterologous prochymosin imposes a greater energy drain on the host than overexpression of homologous PGK. This energetic drain may be a limiting factor in heterologous gene expression.