Effects of female sex steroids on concanavalin A-mediated agglutination of hepatocytes from nonregenerating and regenerating rat liver and hepatic tumor marker enzymes

Effect of treatment of female rats with an oral contraceptive agent (OCA), Ovulen-50, for 7 weeks on agglutination of hepatocytes with concanavalin A (con A) and activities of certain tumor marker enzymes were examined to find out if OCA treatment is related to preneoplastic or neoplastic processes. Hepatocytes from regenerating and nonregenerating livers of control female rats showed negligible agglutination with Con A, whereas hepatocytes from non regenerating but not from the regenerating livers of female rats treated with a combination of 5 micrograms ethinyl estradiol and 100 micrograms ethynodiol diacetate showed agglutination. Of the tumor marker enzymes such as hepatic glucose 6-phosphatase, gamma-glutamyl transpeptidase (gamma-GT), and arginase examined in the liver, only gamma-glutamyl transpeptidase showed a significant increase in activity in the steroid-treated rats. Plasma alkaline phosphatase activity was also higher in the treated animals. However, the magnitude of the changes observed was relatively small and perhaps unrelated to the neoplastic process.     

Next‐generation sequencing for identification of candidate genes for Fusarium wilt and sterility mosaic disease in pigeonpea (Cajanus cajan)

To map resistance genes for Fusarium wilt (FW) and sterility mosaic disease (SMD) in pigeonpea, sequencing‐based bulked segregant analysis (Seq‐BSA) was used. Resistant (R) and susceptible (S) bulks from the extreme recombinant inbred lines of ICPL 20096 × ICPL 332 were sequenced. Subsequently, SNP index was calculated between R‐ and S‐bulks with the help of draft genome sequence and reference‐guided assembly of ICPL 20096 (resistant parent). Seq‐BSA has provided seven candidate SNPs for FW and SMD resistance in pigeonpea. In parallel, four additional genotypes were re‐sequenced and their combined analysis with R‐ and S‐bulks has provided a total of 8362 nonsynonymous (ns) SNPs. Of 8362 nsSNPs, 60 were found within the 2‐Mb flanking regions of seven candidate SNPs identified through Seq‐BSA. Haplotype analysis narrowed down to eight nsSNPs in seven genes. These eight nsSNPs were further validated by re‐sequencing 11 genotypes that are resistant and susceptible to FW and SMD. This analysis revealed association of four candidate nsSNPs in four genes with FW resistance and four candidate nsSNPs in three genes with SMD resistance. Further, In silico protein analysis and expression profiling identified two most promising candidate genes namely C.cajan_01839 for SMD resistance and C.cajan_03203 for FW resistance. Identified candidate genomic regions/SNPs will be useful for genomics‐assisted breeding in pigeonpea.     

Equilibrium binding constants and facile dissociation of novel serum albumin-dicyanoaurate(I) complexes

 Dicyanoaurate(I), Au(CN)₂ ^–, an important metabolite of chrysotherapy agents (anti-arthritic gold drugs), contains two tightly bound cyanide ligands which render it relatively unreactive toward ligand exchange reactions with potential gold-binding ligands. The extent and nature of its binding to bovine serum albumin (BSA), which may modulare the in vivo activity of Au(CN)₂ ^–, were investigated to determine whether Au(CN)₂ ^– might be more bioavailable than other gold complexes. ¹³C NMR spectroscopy, radioisotope tracers, chromatography, ultrafiltration, and atomic spectroscopy, employing Au(¹³CN)₂ ^– or Au(¹⁴CN)₂ ^– as appropriate, revealed two distinct binding mechanisms. The dominant reaction is reversible association (non-specific binding) of intact Au(CN)₂ ^– ions to form BSA·[Au(CN)₂ ^–] _n adducts. Approximately one equivalent binds with an equilibrium binding constant (pH 7.4, 25  °C) of K ₁=5.5 (±1.1)×10⁴, and three additional equivalents bind with a constant of 7.0 (±0.1)×10³. Au(¹³CN)₂ ^– associated with albumin is characterized by a broad ¹³C NMR resonance at δ_C=154.7 ppm compared to the sharp resonance of the free complex at 156.4 ppm. The BSA·[Au(CN)₂ ^–] _n adducts readily dissociate during gel exclusion chromatography and are therefore underestimated, but are retained and accurately quantitated by ultrafiltration methods. The second binding mechanism is a ligand exchange reaction at Cys-34, to form AlbSAuCN, which accounts for only a small fraction (≤11%) of the bound gold. The small extent of the latter interaction differentiates Au(CN)₂ ^– from the gold drugs such as auranofin, aurothiomalate (Myochrysin) and aurothioglucose (Solganol), which undergo ligand exchange at Cys-34 of albumin to form tightly bound gold-protein complexes. The weak interaction at Cys-34 and the facile dissociation of bound, intact Au(CN)₂ ^– are consistent with its putative role as a gold metabolite that can be accumulated intracellularly. Received: 2 July 1997 / Accepted: 24 September 1997     

Degradation of Sulphonated Azo Dye Red HE7B by Bacillus sp. and Elucidation of Degradative Pathways

Bacteria capable of degrading the sulfonated azo dye Red HE7B were isolated from textile mill effluent contaminated soil. The most efficient isolate was identified as Bacillus sp. Azo1 and the isolate could successfully decolorize up to 89 % of the dye. The decolorized cultural extract analyzed by HPLC confirmed degradation. Enzymatic analysis showed twofold and fourfold increase in the activity of azoreductase and laccase enzymes, respectively, indicating involvement of both reductive and oxidative enzymes in biodegradation of Red HE7B. Degraded products which were identified by GC/MS analysis included various metabolites like 8-nitroso 1-naphthol, 2-diazonium naphthalene. Mono azo dye intermediate was initially generated from the parent molecule. This mono azo dye was further degraded by the organism, into additional products, depending on the site of cleavage of R–N=N–R molecule. Based on the degradation products identified, three different pathways have been proposed. The mechanism of degradation in two of these pathways is different from that of the previously reported pathway for azo dye degradation. This is the first report of a microbial isolate following multiple pathways for azo dye degradation. Azo dye Red HE7B was observed to be phytotoxic, leading to decrease in root development, shoot length and seedling fresh weight. However, after biotreatment the resulting degradation products were non-phytotoxic.     

A chromosomal genomics approach to assess and validate the desi and kabuli draft chickpea genome assemblies

With the expansion of next‐generation sequencing technology and advanced bioinformatics, there has been a rapid growth of genome sequencing projects. However, while this technology enables the rapid and cost‐effective assembly of draft genomes, the quality of these assemblies usually falls short of gold standard genome assemblies produced using the more traditional BAC by BAC and Sanger sequencing approaches. Assembly validation is often performed by the physical anchoring of genetically mapped markers, but this is prone to errors and the resolution is usually low, especially towards centromeric regions where recombination is limited. New approaches are required to validate reference genome assemblies. The ability to isolate individual chromosomes combined with next‐generation sequencing permits the validation of genome assemblies at the chromosome level. We demonstrate this approach by the assessment of the recently published chickpea kabuli and desi genomes. While previous genetic analysis suggests that these genomes should be very similar, a comparison of their chromosome sizes and published assemblies highlights significant differences. Our chromosomal genomics analysis highlights short defined regions that appear to have been misassembled in the kabuli genome and identifies large‐scale misassembly in the draft desi genome. The integration of chromosomal genomics tools within genome sequencing projects has the potential to significantly improve the construction and validation of genome assemblies. The approach could be applied both for new genome assemblies as well as published assemblies, and complements currently applied genome assembly strategies.     

Biological sulfide oxidation using autotrophic Thiobacillus sp.: evaluation of different immobilization methods and bioreactors

Aims:  Evaluation of various immobilization methods and bioreactors for sulfide oxidation using Thiobacillus sp. was studied.
Methods and Results:  Ca-alginate, K-carrageenan and agar gel matrices (entrapment) and polyurethane foam and granular activated carbon (adsorption) efficacy was tested for the sulfide oxidation and biomass leakage using immobilized Thiobacillus sp. Maximum sulfide oxidation of 96% was achieved with alginate matrix followed by K-carrageenan (88%). Different parameters viz. alginate concentration (1%, 2%, 3%, 4% and 5%), CaCl₂ concentration (1%, 2%, 3%, 4% and 5%), bead diameter (1, 2, 3, 4 and 5 mm), and curing time (1, 3, 6, 12 and 18 h) were studied for optimal immobilization conditions. Repeated batch experiments were carried out to test reusability of Ca-alginate immobilized beads for sulfide oxidation in stirred tank reactor and fluidized bed reactor (FBR) at different sulfide concentrations.
Conclusions:  The results proved to be promising for sulfide oxidation using Ca-alginate gel matrix immobilized Thiobacillus sp. for better sulfide oxidation with less biomass leakage.
Significance and Impact of the Study:  Biological sulfide oxidation is gaining more importance because of its simple operation. Present investigations will help in successful design and operation of pilot and industrial level FBR for sulfide oxidation.     

Innate immunity against HIV: a priority target for HIV prevention research

The xenotropic/polytropic subgroup of mouse leukemia viruses (MLVs) all rely on the XPR1 receptor for entry, but these viruses vary in tropism, distribution among wild and laboratory mice, pathogenicity, strategies used for transmission, and sensitivity to host restriction factors. Most, but not all, isolates have typical xenotropic or polytropic host range, and these two MLV tropism types have now been detected in humans as viral sequences or as infectious virus, termed XMRV, or xenotropic murine leukemia virus-related virus. The mouse xenotropic MLVs (X-MLVs) were originally defined by their inability to infect cells of their natural mouse hosts. It is now clear, however, that X-MLVs actually have the broadest host range of the MLVs. Nearly all nonrodent mammals are susceptible to X-MLVs, and all species of wild mice and several common strains of laboratory mice are X-MLV susceptible. The polytropic MLVs, named for their apparent broad host range, show a more limited host range than the X-MLVs in that they fail to infect cells of many mouse species as well as many nonrodent mammals. The co-evolution of these viruses with their receptor and other host factors that affect their replication has produced a heterogeneous group of viruses capable of inducing various diseases, as well as endogenized viral genomes, some of which have been domesticated by their hosts to serve in antiviral defense.