Biology subjects

Shankar, B. A.

Publications and source records attributed to Shankar, B. A..

4 recordsLinked to original sources

bioRxiv2021

Identification of Thermotolerant Rice Genotypes with Allele Coding at Seedling Stage

Rice-The most important plant in the world to ensure food security. Heat is one of the main factors that greatly limit rice production. With the increasing global warming, industrialization there is a great effect on climate change which requires us to see various alternatives for strains that are more tolerant to heat so that some techniques are developed to filter a large number of genotypes for high temperature tolerance. Here we report the standardization of Temperature Induction Response (TIR) technique to identify thermotolerant rice genotypes. The phenotypic characteristics of Rice due to high temperature is calculated with germination (%), growth of the seedling and molecular analysis is also considered. The heat stress is provided to the plants with the help of TIR protocol with the adjustment of temperature to lethal (55{degrees}C) and sub-lethal levels (38-55{degrees}C) in a TIR chamber with alterations in humidity. Of the 74 genotypes screened, 14 showed thermo tolerance caused by high temperatures. Both tolerant and sensitive genotypes were separated based on their survival percentages. The tolerant class are selected based on the growth and development of genotypes having high survival percentage and also their shoot and root lengths, fresh and dry weights are compared to the heat tolerant checks N22, Dular and Nipponbare. These genotypes have intrinsic heat tolerance and thus can be explored as a source of donors in breeding programs intended for global warming. The molecular markers which are identified to be linked with heat tolerant class through allele code are quite helpful and can be used in marker assisted breeding approach to attain heat tolerance in cultivated varieties.

molecular biology↗

bioRxiv2021

Genome sequencing and molecular characterisation of XDR Acinetobacter baumannii reveal complexities in resistance: Novel combination of Sulbactam-Durlobactam holds promise for therapeutic intervention

Acinetobacter baumannii is an emerging nosocomial strain expressing extensive drug resistance (XDR). Whole-genome sequencing and molecular characterisation analysis revealed the presence of carbapenemase in 92.86% of studied Indian isolates having blaOXA-51, blaOXA-23, blaOXA-58, and blaNDM genes, with a few evidences of dual carbapenemase genes. As per the MLST scheme, IC2Oxf/CC2Pas was the predominant clone, with 57.14% isolates belonging to this lineage. The presence of {beta}-lactamases has rendered sulbactam (SUL) resistance (MIC: 16-256{micro}g/ml) in all the studied isolates. The efficacy of novel durlobactam (DUR) in inhibiting {beta}-lactamases and PBP2 was assessed through in-silico inter-molecular interaction analysis. Several non-synonymous single nucleotide polymorphisms (nsSNPs) were identified in PBP2 (G264S, I108V, S259T) and PBP3 (A515V, T526S) sequences. Minimal variations were recorded in the protein-backbone dynamics in active-site motifs of wild-type (WT) and mutants (MT), which correlated with the negligible binding energy fluctuations for PBP3-SUL (-5.85{+/-}0.04Kcal/mol) and PBP2-DUR (-5.16{+/-}0.66Kcal/mol) complexes. Furthermore, stronger binding affinities and low inhibition constants were noted in DUR complexed with OXA23 (-7.36Kcal/mol; 4.01{micro}M), OXA58 (-6.44Kcal/mol; 19.07{micro}M) and NDM (-6.82Kcal/mol; 10.01{micro}M) when compared with conventional drugs avibactam and aztreonam. Stable interaction profiles of DUR, can possibly restore SUL activity against both PBP3WT and PBP3MTs. The study establishes the efficacy of novel SUL-DUR combination as a successful treatment strategy to combat emerging XDR strains.

microbiology↗

bioRxiv2021

Assessing the Effectiveness of Mycorrhizal Inoculation on the Biochemical Composition of the Different Species of Echinacea

The information regarding the effect of the mycorrhizal inoculation on different Echinacea species is not available in detail. Therefore, here we determined the changes in the biochemical composition of echinacea as a result of mycorrhizal inoculation. This experiment was undertaken to assess the effect of the mycorrhizal association on biochemical properties of different echinacea species (E. angustifolia,E. purpurea, E. pallida). Here various echinacea species were inoculated with mycorrhiza to examine the species richness in different traits. The results established that biological traits (plant dry matter, chlorophyll content, carotenoid, N content, P content, K content) and physiological and mycorrhization characteristics (Root essential oil, ABTS Antioxidant, Ferric-Reducing Antioxidant, Total phenolic, AM Spore No., AM Root Colonization) both are higher under mycorrhizal association than the control plants of different echinacea species. E. purpurea showed greater results than the E. angustifolia and E. pallida. Among biochemical properties chlorophyll content, carotenoid and N, P, K were significantly higher underE. Purpurea than the E. angustifolia and E.pallida. Total dry matter was higher under E. angustifolia (49.23 g) and minimum dry matter was found under E. pallida (40.07 g). Physiological and mycorrhizal traits were significantly higher under E. purpurea than the other species. E. purpurea showed higher AM Spore No., AM Root Colonization 231.30, 78.70% respectively. Lowest physiological and mycorrhization characteristics were found under E. pallida. The result of mycorrhizal association was very effective for plant growth and increased bio-physicochemical properties than the control plants.

plant biology↗

bioRxiv2021

Colistin resistance in Acinetobacter baumannii is driven by multiple genomic traits: Evaluating the role of ISAba1-driven eptA overexpression among Indian isolates

Colistin resistance in Acinetobacter baumannii is mediated by multiple mechanisms. Recently, mutations within pmrAB two component system and overexpression of eptA due to upstream insertion of ISAba1 play a major role.To characterize colistin resistance mechanisms among the clinical isolates of A. baumannii in India. A total of 224 clinical isolates of A. baumannii collected from 2016 to 2019 were included in this study. Mutations within lipid A biosynthesis and pmrAB genes were characterized by Whole Genome Shotgun sequencing. Twenty eight complete genomes were further characterized for insertional inactivation of lpx genes and the association of ISAba1-eptA using hybrid assembly approach. Non-sysnonymous mutations like M12I in pmrA, A138T and A444V in pmrB and E117K in lpxD were identified. Four of the five colistin resistant A.baumannii isolates had insertion of ISAba1 upstream eptA. No mcr genes were identified.Overall, the present study highlights the diversity of colistin resistance mechanisms in A. baumannii. ISAba1-driven eptA overexpression could be responsible for colistin resistance among Indian isolates of colistin resistant A. baumannii.

microbiology↗