Effect of Al and heavy metals on enzymes of nitrogen metabolism of fast and slow growing rhizobia under explanta conditions

Most of the legume crops are affected by metal stress present in the soil mainly due to contaminated agrochemicals and sewage sludge. The effect of aluminium, and heavy metals copper, iron and molybdenum on growth and activity of enzymes of fast and slow growing rhizobial sps. was studied. Sinorhizobium meliloti RMP₅ was found to be more tolerant to metal stress than Bradyrhizobium BMP₁. Both the strains were extremely sensitive to Al than other metals. Al was much more deleterious for the enzymatic activities (nitrate reduction, nitrite reduction, nitrogenase and uptake hydrogenase) of strain RMP₅ and BMP₁. Cu showed inhibitory effect on growth and enzyme activities of Bradyrhizobium strain at all concentrations. However, in S. meliloti RMP₅ all the tested enzymatic activities increased up to the concentration of 0.1 mM Cu. Fe enhanced the growth and enzyme activities of S. meliloti RMP₅ and Bradyrhizobium BMP₁ up to 100 mM concentration. Mo enhanced all the tested enzymatic activities of S. meliloti RMP₅ up to 1 mM. Nitrate and nitrite reduction activities of Bradyrhizobium BMP₁ increased up to 1 mM concentration. However, nitrogenase and hydrogenase activities of Bradyrhizobium BMP₁ got enhanced only up to 0.5 mM Mo. Both Fe and Mo are the key components of the enzyme nitrogenase and nitrate reductase and enhanced the growth and enzyme activities of both the sps. The study of physiology of nitrogen fixing ability of both fast and slow growing rhizobial strains reported that the supplementation of Mo and Fe in soils along with the biological formulations will enhance the process of symbiotic nitrogen fixation.     

Genetic diversity of <Emphasis Type="Italic">Macrophomina phaseolina</Emphasis> isolates from certain agro-climatic regions of India by using RAPD markers

Genetic diversity analysis of Macrophomina phaseolina isolates obtained from different host range and diverse geographical locations in India was carried out using RAPD fingerprinting. Of the thirteen 10-mer random primers used, primer OPB-08 gave the maximum polymorphism and the UPGMA clustering could separate 50 isolates in to ten groups at more than 65% similarity level. The ten clusters correlated well with the geographical locations with exceptions for isolates obtained from Eastern and Western Ghats. There was a segregation of isolates from these two geographical locations in to two clusters thus, distributing 10 genotypes in to eight geographical locations. All the isolates M. phaseolina irrespective of their host and geographical origin, exhibited two representative monomorphic bands at 250 bp and 1 kb, presence of these bands suggests that isolates might have evolved from a common ancestor but due to geographical isolation fallowed by natural selection and genetic drift might have segregated in to subpopulations. Genetic similarity in the pathogenic population reflects the dispersal of single lineage in all locations in India.     

Alginate-encapsulation of nodal segments for propagation, short-term conservation and germplasm exchange and distribution of Eclipta alba (L.)

Nodal segments obtained from in vitro proliferated shoots of Eclipta alba (L.) Hassk, were encapsulated in calcium alginate beads for large-scale clonal propagation, short-term conservation and germplasm exchange and distribution. The best gel complexation was achieved using 3% sodium alginate and 100 mM CaCl₂·2H₂O. Maximum percent response (100%) for conversion of encapsulated nodal segments into plantlets was obtained on 0.7% agar-solidified full-strength MS medium containing 0.88 μM BAP. Encapsulated nodal segments could be stored at low temperature (4°C) up to 60 days with a survival frequency of 51.2%. The well-developed plantlets regenerated from encapsulated nodal segments were hardened-off successfully with 90% survival frequency.     

Study on the effects of chloride depletion on photosystem II using different chloride depletion methods

Chloride is an indispensable factor for the functioning of oxygen evolving complex (OEC) and has protective and activating effects on photosystem II. In this study we have investigated mainly by EPR, the properties of chloride-sufficient, chloride-deficient and chloride-depleted thylakoid membranes and photosystem II enriched membranes from spinach. The results on the effects of different chloride depletion methods on the structural and functional aspects of photosystem II showed that chloride-depletion by treating PS II membranes with high pH is a relatively harsh way causing a significant and irreparable damage to the PS II donor side. Damage to the acceptor side of PS II was recovered almost fully in chloride-deficient as well as chloride-depleted PS II membranes.     

Genetic Polymorphism of the β-Lactoglobulin Gene in Native Sheep from India

The genetic polymorphism of the β-lactoglobulin (β-LG) gene was determined in 638 animals belonging to 15 native Indian sheep breeds reared in different agroecological regions for various production traits. Variants of β-LG were found using PCR–RFLP of genomic DNA. Rsa1 restriction enzyme digestion of a 120-bp PCR fragment of exon 2 of β-LG revealed two genetic variants, A (0.37) and B (0.63), and the three genotypes AA (0.175), AB (0.389), and BB (0.436). The differences in allelic frequency were not significant across the breeds, irrespective of their geographic origin and utility (χ² test, P > 0.05). The pattern of occurrence of allelic variants revealed that the B allele was more frequent in the majority of the Indian breeds than in breeds reported from countries of Southwest Asia, Eastern and Central Europe, and the Mediterranean. A higher level of heterozygosity (0.422) was discerned, despite the declining status of several of the Indian breeds. These findings revealed that Indian sheep are predominantly of the β-LG B type.     

Solid-phase synthesis of short α-helices stabilized by the hydrogen bond surrogate approach

Stabilized α-helices and nonpeptidic helix mimetics have emerged as powerful molecular scaffolds for the discovery of protein-protein interaction inhibitors. Protein-protein interactions often involve large contact areas, which are often difficult for small molecules to target with high specificity. The hypothesis behind the design of stabilized helices and helix mimetics is that these medium-sized molecules may pursue their targets with higher specificity because of a larger number of contacts. This protocol describes an optimized synthetic strategy for the preparation of stabilized α-helices that feature a carbon-carbon linkage in place of the characteristic N-terminal main-chain hydrogen bond of canonical helices. Formation of the carbon-carbon bond is enabled by a microwave-assisted ring-closing metathesis reaction between two terminal olefins on the peptide chain. The outlined strategy allows the synthesis and purification of a hydrogen bond surrogate (HBS) α-helix in ～ 1 week.     

Estimates of (co)variance components and genetic parameters for body weights and first greasy fleece weight in Bharat Merino sheep

(Co)variance components and genetic parameters of weight at birth (BWT), weaning (3WT), 6, 9 and 12 months of age (6WT, 9WT and 12WT, respectively) and first greasy fleece weight (GFW) of Bharat Merino sheep, maintained at Central Sheep and Wool Research Institute, Avikanagar, Rajasthan, India, were estimated by restricted maximum likelihood, fitting six animal models with various combinations of direct and maternal effects. Data were collected over a period of 10 years (1998 to 2007). A log-likelihood ratio test was used to select the most appropriate univariate model for each trait, which was subsequently used in bivariate analysis. Heritability estimates for BWT, 3WT, 6WT, 9WT and 12WT and first GFW were 0.05 ± 0.03, 0.04 ± 0.02, 0.00, 0.03 ± 0.03, 0.09 ± 0.05 and 0.05 ± 0.03, respectively. There was no evidence for the maternal genetic effect on the traits under study. Maternal permanent environmental effect contributed 19% for BWT and 6% to 11% from 3WT to 9WT and 11% for first GFW. Maternal permanent environmental effect on the post-3WT was a carryover effect of maternal influences during pre-weaning age. A low rate of genetic progress seems possible in the flock through selection. Direct genetic correlations between body weight traits were positive and ranged from 0.36 between BWT and 6WT to 0.94 between 3WT and 6WT and between 6WT and 12WT. Genetic correlations of 3WT with 6WT, 9WT and 12WT were high and positive (0.94, 0.93 and 0.93, respectively), suggesting that genetic gain in post-3WT will be maintained if selection age is reduced to 3 months. The genetic correlations of GFW with live weights were 0.01, 0.16, 0.18, 0.40 and 0.32 for BWT, 3WT, 6WT, 9WT and 12WT, respectively. Correlations of permanent environmental effects of the dam across different traits were high and positive for all the traits (0.45 to 0.98).