Dietary zinc potentiates thermal tolerance and cellular stress protection of Pangasius hypophthalmus reared under lead and thermal stress

Zinc micronutrient is the second most abundant trace element in the animal body, as it could not be stored in the body; hence, regular dietary zinc is required for animals. With this backdrops a 60 days feeding trial was conducted to study the effect of dietary zinc on the thermal tolerance and cellular metabolic stress of Pangasius hypophthalmus reared under Pb (1/21th of LC₅₀, 4 ppm) and elevated temperature (34°C). Three isocaloric and isonitrogenous diets with Zn‐0, 10 and 20 mg/kg were prepared. Two hundred seventy‐three fish were randomly distributed into seven treatments in triplicate in completely randomized forms. Dietary zinc supplementation had remarkable (p < .01) changes on thermal tolerance of P. hypophthalmus viz. CTmin (critical temperature minima) and LTmin (lethal temperature minima), CTmax (critical temperature maxima) and LTmax (lethal temperature maxima). The positive correlations were also observed between CTmin and LTmin (Y = ?0.707 + 6.59x, R², 0.875) and CTmax and LTmax (Y = ?0.923 + 2.45x, R², 0.960). The oxidative stress (catalase, superoxide dismutase and glutathione‐s‐transferase) and lipid peroxidation were significantly reduced and neurotransmitter enzyme (AChE) was significantly enhanced with zinc supplementation at the end of the thermal tolerance. The present study concluded that thermal tolerance of P. hypophthalmus enhanced by zinc supplementation through CTmax LTmax and CTmin LTmin and also by strengthening the antioxidative status along with neurotransmitter enzymes.     

Abundance of sulphur‐oxidizing bacteria in coastal aquaculture using soxB gene analyses

Molecular techniques based on sequencing of metagenomic clone libraries provide an insight into the diversity of microbial populations. Using nucleic acid‐based methods, the diversity of soxB genes was examined to detect and characterize sulphur‐oxidizing bacteria in Indian coastal aquaculture environments. Gene‐specific degenerate primers were used to amplify various fragments (710, 753, 483–503, 280 and 239 bp) of soxB genes. Metagenomic clone libraries were constructed for 753, 483–503 and 239 bp fragments of soxB genes. The abundance of soxB revealed the presence of sulphur‐oxidizing organisms. Amino acids in parts of the soxB‐encoded proteins were aligned to known conserved amino acid residues. The level of conservation ranged from 23% to 30%. A phylogenetic tree constructed from aligned amino acid sequences of SoxB revealed different clusters associated with the branches of phototrophic α‐ and γ‐proteobacteria. In general, soxB is widespread among the various phylogenetic groups, although this does not necessarily mean that the organism can use sulphur compounds. Our results suggest that the chemolithoautotrophy based on sulphur oxidation in coastal aquaculture is primarily sustained by the presence of sulphur oxidizers, which involve the soxB gene. This study aids identification of the phylogenetic characteristics related to sulphur bioremediation in poorly characterized coastal aquaculture environments.     

The snoRNA HBII-52 regulates alternative splicing of the serotonin receptor 2C

The Prader-Willi syndrome is a congenital disease that is caused by the loss of paternal gene expression from a maternally imprinted region on chromosome 15. This region contains a small nucleolar RNA (snoRNA), HBII-52, that exhibits sequence complementarity to the alternatively spliced exon Vb of the serotonin receptor 5-HT(2C)R. We found that HBII-52 regulates alternative splicing of 5-HT(2C)R by binding to a silencing element in exon Vb. Prader-Willi syndrome patients do not express HBII-52. They have different 5-HT(2C)R messenger RNA (mRNA) isoforms than healthy individuals. Our results show that a snoRNA regulates the processing of an mRNA expressed from a gene located on a different chromosome, and the results indicate that a defect in pre-mRNA processing contributes to the Prader-Willi syndrome.     

Genetic analysis of growth and wood variations in Leucaena leucocephala (Lam.) de Wit.

We selected 28 populations of Leucaena leucocephala from different geographical locations in the states of Andhra Pradesh, Tamil Nadu and Orissa of India on the basis of height and girth at breast height (GBH). We evaluated fiber length, optical density, wall thickness, vessel element length, vessel element diameter, specific gravity and lignin of these populations of L. leucocephala in different sites. Populations had significant variations for all growth, wood and paper parameters. Girth at breast height (GBH) and specific gravity were the most important parameters for heritability and genetic gain, respectively. The minimum heritability was reported for vessel element length and genetic gain for fiber length. The populations were grouped into six clusters, cluster II had maximum number of populations (14) and clusters IV and VI had one population each. GBH contributed maximum of 34.39 % towards total divergence followed by specific gravity (14.02%). An economic technique to produce quality seed by establishing seed orchards with genetically divergent parents was suggested. The hybridization among the populations selected from diverse clusters could produce greater heterosis needed for higher growth and suitable wood and paper manufacturing parameters.     

Seasonal effect on rooting behaviour of important bamboo species by culm cuttings

We investigated the influence of season on the rooting behaviour of eight important bamboo species viz., Bambusa balcooa, B.bambos, B. nutans, B. tulda, B. vulgaris, Dendrocalamus giganteus, D.hamiltonii and D. strictus. We collected 2 3 node culm cuttings in three growing seasons viz. spring (March), summer (June) and rainy (August)from superior candidate plus clumps (CPCs) centralized in the germ-plasm garden. Cuttings were placed horizontally in sand and were provided with intermittent misting at regular intervals. Bamboo species exhibited differential rhizogenesis behavior in different seasons. The study reveals significant variation in sprouting and rooting behaviour indifferent bamboo species. B. bambos had maximum rooting (78.89%),followed by B. vulgaris (74.44%). In general, the potential of different bamboo species for rooting was found to be in the order: B. bambos > B.vulgaris > B. balcooa > D. hamiltonii > B. tulda > D. strictus > D.giganteus >B. nutans. The maximum rooting was recorded in spring(56.67%), which was closely followed by summer (54.58%). In winter season, minimum rooting (36.67%) was observed. The interaction effect of species × season was also significant on sprouting and rooting parameters. In B. balcooa, B. nutans, B. vulgaris, D. hamiltonii and D.strictus, cuttings collected in summer season showed maximum sprouting and rooting, whereas, B. bambos, B. tulda and D. giganteus had maximum rooting in spring. The maximum number of roots developed per cutting was observed in B. tulda (43.8) during spring season.     

Fine mapping of <Emphasis Type="Italic">Rf3</Emphasis> and <Emphasis Type="Italic">Rf4</Emphasis> fertility restorer loci of WA-CMS of rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) and validation of the developed marker system for identification of restorer lines

The Wild Abortive (WA) system is the major cytoplasmic male sterility (CMS) source for hybrid rice production in indica rice and its fertility restoration is reported to be controlled by two major loci viz. Rf3 on chromosome 1 and Rf4 on chromosome 10. With the availability of the rice genome sequence, an attempt was made to fine map, develop candidate gene based markers for Rf3 and Rf4 and validate the developed marker system in a set of known restorer lines. Using polymorphic markers developed from microsatellite markers and candidate gene based markers from Rf3 and Rf4 loci, local linkage maps were constructed in two mapping populations of ~1,500 F₂ progeny from KRH2 (IR58025A/KMR3R) and DRRH2 (IR68897A/DR714-1-2R) hybrids. QTLs and their interactions for fertility restoration in Rf3 and Rf4 loci were identified. The identified QTL in both mapping populations together explained 66–72 % of the phenotypic variance of the trait suggesting their utility in developing a marker system for identification of fertility restorers for WA-CMS. Sequence comparison of the two candidate genes from the Rf3 and Rf4 regions in male sterile (A) and restorer (R) lines showed 2–3 bp indels and a few substitutions in the Rf3 region and indels of 327 and 106 bp in the Rf4 region respectively. The marker system identified in the present study was validated in 212 restorers and 34 maintainers along with earlier reported markers for fertility restoration of WA-CMS. Together DRCG-RF4-14 and DRCG-RF4-8 for the Rf4 locus and DRRM-RF3-5/DRRM-RF3-10 for the Rf3 locus showed a maximum efficiency of 92 % for identification of restorers.     

Biochemical Alterations in the Blood Plasma of Rats Associated with Hepatotoxicity Induced by Eupatorium adenophorum

Eupatorium adenophorum (Crofton weed), a native of Central America, has appeared as a major weed in several areas in different parts of the world. Horses that eat this plant are poisoned on prolonged exposure. Toxicity due to consumption of this plant by other grazing animals is not clear. Administration of freeze-dried leaf powder to mice results in hepatotoxicity. Earlier attempts to produce toxicity in rats using the leaves of this plant were not successful. In the present study, administration of oven-dried E. adenophorum leaves collected at the flowering stage elicited hepatotoxicity in rats. The affected animals had a marked increase in the concentration of plasma bilirubin and in the activities of 5-nucleotidase, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase. There were no significant differences in plasma creatinine, urea or total protein values in the affected animals compared to controls. The livers of the affected animals had focal areas of necrosis throughout the parenchyma and hepatocytes showed megalocytosis. The bile ducts were dilated and the epithelium showed degenerative to necrotic changes. The alterations in bilirubin, enzymes and histopathological changes imply cholestasis and liver injury.