Genetic diversity in common carp stocks assayed by random-amplified polymorphic DNA markers

The common carp (Cyprinus carpio L.) is one of the major aquaculture species, contributing nearly 35% to the inland fish production in Karnataka, India. Stocks collected from Hungary (2), Indonesia and Vietnam were assessed alongside two local stocks in a series of culture performance trials with the objective of setting up a base population for developing a breeding programme. The present study deals with the genetic divergence and polymorphism in these six stocks using random‐amplified polymorphic DNA (RAPD) markers. A total of 180 decamer random primers were screened for polymerase chain reaction (PCR) amplification (OPA 1‐20, OPB1‐20, OPC1‐20, OPD1‐20, OPE1‐20, OPF1‐20, OPG1‐20, OPP1‐20 and OPM1‐20). Eight primers were selected for analysis of common carp genotypes (OPA‐7, OPA‐20, OPB‐17, OPF‐10, OP F‐9, OPG‐4, OPG‐9 and OPP‐16). Out of 492 bands recorded, 57.1% were polymorphic. Stepwise regression analysis was carried out to find best combination markers affecting body weight (P<0.001). The results demonstrate major differences in the genetic structures between different stocks. Dendrogram data showed grouping of individuals according to stocks and corresponding data variables revealed the per cent homology within the stock and also found markers correlating to the body weight.     

Inactivation of seed-treatment fungicides by Rhizobium

2-Methoxyethylmercury chloride (MEMC) applied to cowpea seeds with Rhizobium provided little or no control of seedling rot caused by Rhizoctonia solani; similar treatment, but without Rhizobium, gave >40% control of disease. Treating seeds with quintozene and then with Rhizobium rendered the fungicide completely ineffective against R. solani infections; disease control was >70% when seeds were treated with quintozene only, and >60% when seeds were coated first with Rhizobium and then with quintozene; treatment with quintozene+Rhizobium gave about 25% control. Simultaneous treatment with Rhizobium considerably reduced the efficacy of captafol, chloroneb, carbendazim and thiophanate-methyl. Disease control by carboxin, benomyl and thiabendazole remained unaltered in the presence of Rhizobium, but only thiabendazole gave good control. Seeds treated with MEMC and Rhizobium produced seedlings without root nodules; nodulation was also decreased by captafol and by carboxin but six other fungicides had no effect. The implications of Rhizobium-fungicides interactions are discussed in the context of fungicidal control of root diseases.     

Biodegradation of hexachlorocyclohexane-isomers in contaminated soils

Several sites that are contaminated with isomers of the chlorinated insecticide hexachlorocyclohexane (HCH) are present across the globe and cause toxicity. For their bioremediation, we studied the degradation of HCH-isomers in contaminated soils by an isolate Pseudomonas aeruginosa ITRC-5. The degradation is optimal at 2 mg technical-HCH (t-HCH)/g soil, 15% water content, pH 8.0, temperature 28 °C and inoculum density 10⁶ colony forming unit/g soil. Under these conditions, from 5 kg soil, >98% α- and γ-HCH, 17% β-HCH and 76% δ-HCH are degraded after 15 days of incubation, which is accompanied with the release of 600 μg chloride/mg t-HCH. Concomitant to the degradation, a four-fold reduction in the toxicity of HCH-isomers to earthworm, Eisenia foetida, is also observed. Addition of ITRC-5 enhanced the degradation of soil-applied HCH-isomers in ‘open field’ conditions as well, and 97%, 43%, 94% and 77% of α-, β-, γ- and δ-HCH, respectively, are degraded after 12 weeks of incubation. Thus, the bacterium causes microbial degradation and detoxification of HCH-isomers, and can be used for the bioremediation of contaminated soils.     

Allelopathic Potential of Shoot and Root Leachates of Certain Weed Species

The allelopathic potential of shoot and root leachates of seven weed species was assessed using sorghum and blackgram as test crops. Weeds differed significantly among themselves in their allelopathic effect. Shoot leachates of weeds, in general, showed more allelopathic effect than their root leachates. Phenolic content of weed leachates has positive association with the allelopathic potential of the weed species.     

Experimental Streptococcus equi infection in the horse: correlation with in vivo and in vitro immune responses

Fourteen young outbred horses, divided into 2 groups on the basis of 18- or 24-hour skin-test reactions to Streptococcus equi, were inoculated nasopharyngeally with virulent S equi. Animals (n = 6, group I) with evidence of previous exposure to S equi (positive dermal response and existing serum antibodies), with one exception, developed minimal or no signs of disease after inoculation. In contrast, S equi skin-test negative and seronegative horses (n = 8, group II) developed predictable and severe clinical signs of infection after their inoculation, including shedding of the organism from nasal discharges and ruptured mandibular lymph nodes. Results of the present study indicate that resistance to virulent S equi infection is correlated with existing humoral and cellular immune responses to streptococcal antigens. In susceptible horses, recovery from infection was accompanied by the appearance of humoral antibodies and the acquisition of a positive skin-test response to S equi antigens.     

Effect of endosulfan in female rats growing on low- and high-protein cereal diet

Endosulfan (α,β-1,2,3,4,7,7-hexachlorobicyclo(2,2,1)-heptene-(2)-bis-hydroxymethylene(5,6)sulfite) fed daily 0.5 and 100 ppm in the diet proved significantly toxic to female rats (initial weight 40–50 g) growing on a low-protein (5%) diet as compared to those growing on a high-protein (24%) diet. The toxic symptoms which developed exclusively in low-protein-fed rats included growth retardation, low blood counts, low RNA and protein levels in liver, and high glutathione levels in liver and blood. However, no changes in the activities of liver RNase, blood glucose-6-phosphate dehydrogenase, and glutathione reductase were observed. Liver glucose-6-phosphatase activity increased significantly. Endosulfan induced an increased accumulation of perirenal adipose in rats raised both on low- and high-protein diets. Endosulfan elicited cumulative toxic manifestations as evident from the relative degree of toxicity caused by 0.5 ppm and 18 weeks feeding. α-Endosulfan, β-endosulfan, and endosulfan sulfate were recovered from adipose tissue, the recovery being higher in adipose tissue of rats raised on a low-protein diet.     

Cloning and Sequence Analysis of the Gene Encoding LipL32 of <Emphasis Type="Italic">Leptospira interrogans</Emphasis> Serovar Sejroe

Leptospira, a member of the order Spirochaetales, is the causative agent of leptospirosis, an important zoonosis encountered worldwide. The Leptospira interrogans serovar Sejroe was grown in EMJH medium and its DNA was isolated using standard techniques. The LipL32 gene was amplified using the reported primer of Kirschneri of LipL32. The amplified product was found to comprise 756 base pairs. This amplified gene fragment of LipL32 lipoprotein was cloned in E. coli (DH5α) cells using pDrive plasmid as a vector. The recombinant cells were selected on LB agar medium containing ampicillin, X-gal and isopropyl-β-d-thiogalactopyranoside. Plasmid was extracted from the recombinant white colonies, and restriction endonuclease (RE) analysis was carried out using PstI and SalI. On partial sequence analysis, the product exhibited 756 base pairs, corresponding to 251 amino acids. The cloned gene could be further used for expression of recombinant protein for serodiagnosis of leptospirosis.     

Modeling and characterization of the moisture-dependent bilinear behavior of regenerated cellulose composites

In this study, we investigate the tensile mechanical properties of unidirectional Lyocell/epoxy composites under wet and dry conditions using a multi-scale analysis approach. Characterization of the samples shows a bilinear stress–strain behavior of the fibers and composites under tension loading. The bilinear elastic–plastic stress–strain response of the Lyocell fibers is incorporated into a p-version finite element model for presenting a methodology for structural analysis of this composite system. The proposed finite element models were successfully able to relate the micro to macro-mechanical behavior enabling an approach for determining the 3D orthotropic elastic–plastic constants of regenerated cellulose/epoxy composites.     

Deployment of wild relatives for genetic improvement in rice (Oryza sativa)

Rice is one of the most important crops in the world. The wild species of rice are expected to have novel beneficial alleles that have been lost from cultivated rice during the process of domestication. Therefore, wild species could be the potential source to induce lost genetic diversity in cultivated rice. Serving as an important reservoir of novel genes/QTLs, wild species, in general, are better adapted to different ecologies and can tolerate many biotic and abiotic stresses. Despite that, only a few wild species are studied and extensive characterization both at the molecular and morphological level is yet to be achieved. Several agronomically important genes/QTLs for improving biotic and abiotic stresses, resistance, productivity and grain quality traits were identified from AA genome donor wild species and were tagged with breeder friendly molecular markers for their transfer to elite genetic backgrounds. The present review provides information on the important wild rice species harbouring genes/QTLs for agriculturally important traits and their successful utilization in rice breeding programmes.