Biological parameters of the endangered fish Chitala chitala (Osteoglossiformes: Notopteridae) from some Indian rivers

Age, growth and maturity data of the freshwater feather back Chitala chitala (Hamilton-Buchanan, 1822) were collected from ten different geographical locations. Out of ten populations, maximum 6+ ages were recorded from four river basins namely river Bhagirathi, Koshi, Saryu and Ganga and the back calculated lengths at 6+ ages ranged from 1033.36–1073.63 mm. In rest of the locations, however, only 3+ age classes were recorded. Specific rate of linear growth (C_l) and specific rate of weight increase (C_w) showed decreases except in two locations. The specific rate of linear growth (C_l) and the specific rate of weight increase (C_w) increased at 3+ age class in the river Bhagirathi. Among other growth parameters, three distinct life stages of C. chitala were observed based on analysis of growth constant data. Analysis of variance (ANOVA) of the back-calculated length data of 10 populations indicated a significant difference (p < 0.05). Out of ten populations studied, six showed significant variation of growth in 1+ age class and two showed significant variation in 2+ to 6+ age classes. Length-weight relationship of the species from all the population was calculated and the coefficient of correlation (r) was at the significant level where the value of ‘b’ was almost 3 for all the locations studied. Male C. chitala attained maturity earlier (2+ age) whereas females matured at age 3+. The percentages of mature individuals also varied between river basins. Based on this study strategies can be proposed for sustainable exploitation of the species from wild populations.     

Persistence and metabolism of imidacloprid in different soils of West Bengal

A laboratory experiment was performed to study the persistence of imidacloprid from two formulations (Confidor 200 g litre-1 SL and Gaucho 700 g kg-1 WS), and its metabolism in three different soils (Gangetic alluvial soil of Kalyani, lateritic soil of Jhargram and coastal alkaline soil of Canning) of West Bengal following application at 0.5 kg and 1.0 kg AIha-1. Dissipation of imidacloprid in soil followed first-order kinetics and DT50 values ranged from 28.7 to 47.8 days. The shortest half-lives (28.7 and 35.8 days) were observed in the lateritic soil of Jhargram for both liquid and powder formulations. The formation of two metabolites of imidacloprid, imidacloprid-urea and imidacloprid-olefin, was first detected on day 30 of degradation at 28 (+/- 1) degrees C in all three soils.     

A functional screen for the type III (Hrp) secretome of the plant pathogen Pseudomonas syringae

Type III secreted "effector" proteins of bacterial pathogens play central roles in virulence, yet are notoriously difficult to identify. We used an in vivo genetic screen to identify 13 effectors secreted by the type III apparatus (called Hrp, for "hypersensitive response and pathogenicity") of the plant pathogen Pseudomonas syringae. Although sharing little overall homology, the amino-terminal regions of these effectors had strikingly similar amino acid compositions. This feature facilitated the bioinformatic prediction of 38 P. syringae effectors, including 15 previously unknown proteins. The secretion of two of these putative effectors was shown to be type III--dependent. Effectors showed high interstrain variation, supporting a role for some effectors in adaptation to different hosts.     

Eastern Indian 3800-million-year-old crust and early mantle differentiation

Samarium-neodymium data for nine granitic and tonalite gneisses occurring as remnants within the Singhbhum granite batholith in eastern India define an isochron of age 3775 +/- 89 x 10(6) years with an initial (143)Nd/(144)Nd ratio of 0.50798 +/- 0.00007. This age contrasts with the rubidium-strontium age of 3200 x 10(6) years for the same suite of rocks. On the basis of the new samarium-neodynium data, field data, and petrologic data, a scheme of evolution is proposed for the Archean crust in eastern India. The isotopic data provide evidence that parts of the earth's mantle were already differentiated with respect to the chondritic samarium-neodymium ratio 3800 x l0(6) years ago.     

HIV-1 proviral DNA excision using an evolved recombinase

HIV-1 integrates into the host chromosome and persists as a provirus flanked by long terminal repeats (LTRs). To date, treatment regimens primarily target the virus enzymes or virus-cell fusion, but not the integrated provirus. We report here the substrate-linked protein evolution of a tailored recombinase that recognizes an asymmetric sequence within an HIV-1 LTR. This evolved recombinase efficiently excised integrated HIV proviral DNA from the genome of infected cells. Although a long way from use in the clinic, we speculate that this type of technology might be adapted in future antiretroviral therapies, among other possible uses.     

Genotype and hormonal effects on callus formation and regeneration in mulberry

Summary Twenty-five mulberry genotypes were studied for callus induction, to evaluate the effectiveness of hormones in promoting callus growth and to identify genotypes capable of regenerating plants. Fifteen genotypes showed callus initiation. Genotypic variation was also noted for longevity and rate of growth of callus cultures. Calli of different genotypes were maintained for more than one year. Frequency of callus initiation was high on Murashige & Skoog's modified medium incorporated with 2.0 mg/l 2,4-D, 100 mg/l casein acid hydrolysate and 150 ml/l coconut water. Regeneration through organogenesis was achieved in six genotypes indicating genotypic specificity.     

Recent advances in carp seed production and milt cryopreservation

The fish-seed production industry in India has recorded remarkable growth over the last three decades. The hypophysation technique was successfully introduced into India in 1957 and steady progress towards the refinement of the technique has been registered, which has revolutionized carp seed production in the Indian subcontinent. Advancement of carp maturity through brood stock management and multiple breeding has enabled spawn production well ahead of the monsoon and even beyond, ensuring seed availability throughout the year. The quality of seed is an important consideration for commercial aquaculturists. So, partial stock replenishment in carp hatcheries is practised to overcome the problem of inbreeding, which otherwise leads to poor growth of carps. Similarly, gametes of improved stock are cryopreserved and utilized for quality seed production as well as upgrading the brood stock of carps. The gamete cryopreservation protocol for carps is the focus of this review. An attempt has also been made to incorporate information on carp brood stock management, inducing agents, and seed production, including hatchery management.