North Eastern Hill University

About: North Eastern Hill University is a education organization based out in Shillong, Meghalaya, India. It is known for research contribution in the topics: Population & Ruthenium. The organization has 2318 authors who have published 4476 publications receiving 48894 citations.

Studies on Biosynthesis of Antimicrobial Silver Nanoparticles Using Endophytic Fungi Isolated from the Ethno-medicinal Plant Gloriosa superba L.

Abstract: Two endophytic fungi isolated from the ethno-medicinal plant Gloriosa superba L. were used for the in vitro biosynthesis of silver nanoparticles (AgNPs). The endophytic fungi were identified as Alternaria solani GS1 and Penicillium funiculosum GS2 based on their ITS regions of rRNA gene sequences. The silver nanoparticles obtained were characterized by UV–visible spectroscopy and transmission electron microscopy. Silver nanoparticles of the size 5–20 nm biosynthesized by A. solani GS1were found to be at peak at 415 nm whereas the AgNPs of the size 5–10 nm biosynthesized using P. funiculosum GS2 showed a maximum peak at 403 nm. An evident superiority of the antimicrobial potency, as denoted by the zone of inhibition by biosynthesized AgNPs using P. funiculosum GS2 compared to that by A. solani GS1, was observed when the nanoparticles were used against three different bacterial strains (Streptococcus pyogenes MTCC1925, Escherichia coli MTCC730 and Enterococcus faecalis MTCC2729) and a fungal strain (Candida albicans MTCC183). The present study elucidates the efficacy of the AgNPs synthesized by endophytic fungi against the three tested bacterial strains as well as the fungal strain C. albicans indicating their potency of bioprospection for medicinal usage.

Efficacy of RAPD, ISSR and DAMD markers in assessment of genetic variability and population structure of wild Musa acuminata colla

Abstract: North east India is considered as one of the major biodiversity hotspots worldwide and centre of origin of several plant species including Musa. Musa acuminata Colla is known to be one of the wild progenitors of cultivated bananas and plantains. Three single primer based DNA marker techniques viz., random amplified polymorphic DNA (RAPD), inter simple sequence repeat (ISSR) and directed amplification of minisatellites DNA (DAMD) were used for diversity diagnostics among 25 genotypes of wild M. acuminata collected from Meghalaya province of north east India. A total of 58 primers (26-RAPD, 21-ISSR, and11-DAMD) yielded 451 DNA fragments, of which 395 (87.58 %) were found to be polymorphic in nature. The polymorphic information content (PIC) values were almost identical for each marker system. The resolving power of the marker system was found to be highest in RAPD (3.96) whereas ISSR resolved highest marker index (16.39) in the study. Selected amplicon data obtained through single primer amplification reactions were utilized for determination of diversity within and among the populations of M. acuminata. Nei's genetic differentiation (Gst) value (0.451) indicated higher proportion of the genetic variation within the populations which is supported by the AMOVA analysis (88 %). The study provides insight into the efficacy of RAPD, ISSR and DAMD to analyse the genetic variation existing in the wild Musa germplasm, which can further be exploited for quality trait improvement and domestication of such important horticultural crops. The genetic diversity based population structure may shed light on the genetic basis of speciation and evolution of various species within the genus Musa.

Tetraalkylammonium ion induced micelle-to-vesicle transition in aqueous sodium dioctylsulfosuccinate solutions

Abstract: The aggregation behavior of sodium dioctylsulfosuccinate (AOT) in aqueous media containing tetraalkylammonium bromide (TAAB, where alkyl = ethyl (TEAB), propyl (TPAB) and butyl (TBAB)) was studied by surface tension, fluorescence (with pyrene as the probe), small-angle neutron scattering (SANS) and dynamic light scattering (DLS) measurements. A comparison of the critical micelle concentration (cmc) values of AOT in the presence of the salts showed the order TBAB < TPAB < TEAB < NH4Cl < NaCl. Synergism in the cmc occurs when the solution contains a mixture of sodium and tetraalkylammonium counterions. The counterion binding behavior was examined by applying the modified Corrin–Harkins (CH) equation which revealed that a special counterion binding behavior of AOT exists in aqueous solutions with tetraalkylammonium salts. The modified CH equation and DLS data indicate a change in the shape of the surfactant aggregates, which was confirmed by the SANS data. Dehydration of the head group and the counterion during their interaction appears to induce a micelle-to-vesicle transition in the aggregates.

A new species of Leptolalax (Anura: Megophryidae) from the sacred groves of Mawphlang, Meghalaya, north-eastern India

Abstract: A new species of megophryid frog of the genus Leptolalax is described from the sacred groves of Mawphlang, East Khasi Hills, north-eastern India. L. khasiorum new species, is compared with congeners from India and other parts of south-east Asia. The new species is diagnosable in showing the following combination of characters: SVL 24.5–27.3 (mean 25.63 ± 0.61 SE) mm in a sample of four adult males; 31.2–33.4 (mean 32.50 ± 0.67 SE) mm in a sample of three females; dorsum with fine scattered tubercles; eyelids with tubercles; tympanum and supratympanic fold distinct; macroglands, including preaxillary, pectorals and ventrolateral glands present; Finger I > II; toe tips not dilated, bearing dermal fringes; dorsum with dark blotches; flanks with large dark blotches; dark tympanic mask present; venter lacking dark blotches; labial bars present and limbs with dark cross-bars.