Guruswami Gurusubramanian

Brevibacillus as a biological tool: a short review.

The significance of Brevibacillus has been documented scientifically in the published literature and commercially in heterologous recombinant protein catalogs. Brevibacillus is one of the most widespread genera of Gram-positive bacteria, recorded from the diverse environmental habitats. The high growth rate, better transformation efficiency by electroporation, availability of shuttle vectors, production of negligible amount of extracellular protease, and the constitutive expression of heterologous proteins make some strains of this genus excellent laboratory models. Regarding biotechnological applications, this genus continues to be a source of various enzymes of great biotechnological interest due to their ability to biodegrade low density polyethylene, ability to act as a candidate bio-control agent, and more recently acknowledged as a tool for the overexpression. This article reviews the properties of Brevibacillus spp. as better biological tools with varied applications.

Development of resistance to endosulphan in populations of the tea mosquito bug Helopeltis theivora (Heteroptera: Miridae) from organic and conventional tea plantations in India

The tea mosquito bug Helopeltis theivora (Waterhouse) is an important economic pest of tea in India. The development of resistance in H. theivora populations obtained from a conventional plantation and an organic plantation was studied in the laboratory for five generations, and associated changes in life cycle traits were assessed. Selection using sub-lethal concentrations of endosulphan resulted in a 4.4-fold increase in insecticide resistance ratio from the F1 to the F5 generation in the H. theivora population from the conventional plantation. By the F5 generation, nymphal duration was higher and fecundity was lower in the endosulphan-selected strain than in the non-selected strain from a conventional plantation and the susceptible strain from an organic plantation. These findings have practical implications for insecticide resistance management of this important sucking pest of tea.

Expression of visfatin in alloxan-induced diabetic rat testis

Diabetes mellitus is a potential epidemic all over the world and causes dysfunction of reproductive activity. Visfatin, one of the adipokines, is present in various tissues including the testis. Our hypothesis was the level of testicular visfatin is affected in diabetic condition. The aim of the present study was to investigate the expression and localization of visfatin in the diabetic rat testis. No similar studies have been performed in diabetic rat testis with reference to visfatin. Overnight fasted adult male Wistar rats were made diabetic by the administration of alloxan (150 mg/kg i.p., in 0.9% saline). Blood glucose levels were tested on five days after alloxan treatment, rats with high blood glucose levels (>250 mg/dL) were considered as diabetic. Immunolocalization and Western blotting analysis of visfatin were performed. Correlation of visfatin expression was made in relation to body weight, testis weight, glucose concentration and serum testosterone level. Expression of visfatin was observed in Leydig cells, spermatocytes and sperm in control as well as in the diabetic group. Mild immunostaining of visfatin was observed in affected seminiferous tubules of alloxan-induced diabetic rat testis. Western blot analysis showed decreased expression of testicular visfatin in diabetic rats. The expression of visfatin showed a positive correlation with serum testosterone levels, body and testis weight, while a negative correlation was observed with blood glucose levels. This study showed involvement of visfatin in diabetic associated impairment of testicular activity.

ITS2 characterization and Anopheles species identification of the subgenus Cellia

In Mizoram, the origin and molecular nature of Anopheles species is poorly understood, despite the region having high malarial incidence and rich biodiversity. A diagnostic PCR assay for distinguishing the Cellia subgenera members of Anopheles species was developed based on the interspecific ITS2 variation. No intraspecific variation was found and the size (362-604bp) and GC content (48.8-58.9%) of the ITS2 were highly variable among Anophelines. The ITS2 of A. vagus is significantly longer than those of other Anopheles species. Significant relationship was observed among repeats, minimum free energy and RNA secondary structures. Different types of microsatellites were identified and among them dinucleotide, pentanucleotide and polynucleotide microsatellites were predominant. Variation in the length of the ITS2 between species was due to indels in simple repeats. Four domain types of RNA secondary structures were identified and the lowest free energy values were predicted using the computer software, RNAfold. Types I and II were observed only in Neocellia and Myzomyia series and Types III and IV were common in Neocellia and Pyretophorus series. ITS2-based PCR protocol provides a means for vector ecologists, malaria epidemiologists and control personnel to accurately identify members of the subgenera Cellia and a better understanding of their genomic status in Mizoram.

Characterization of Bacillus thuringiensis isolates and their differential toxicity against Helicoverpa armigera populations

Bacillus thuringiensis isolates were characterized in rhizospheric cotton soils by using acetate selection process from eight different locations in South India. The fact that B. thuringiensis indices were higher in proportion in soil samples taken from Tamil Nadu and Karnataka than from Andhra Pradesh, indicates the abundance of B. thuringiensis populations in the cotton rhizosphere. Biochemical typing of the isolates designated eight local isolates (BtNg13, BtCo1, BtHyb7, BtAm2, BtRm5, BtWr3, BtPl 4, BtN 9), which belong to subspecies kurstaki, the most prevalent subspecies. Toxicity assays on American boll worm larval (F1) populations collected from the Andhra Pradesh, Bangalore and Coimbatore regions, with a susceptible insect strain against different isolates of B. thuringiensis kurstaki spore‐crystal mix, revealed distinct susceptibility patterns and specificity. The highest susceptibility was observed in the F1 populations of Coimbatore, followed by Bangalore and Hyderabad populations, in comparison with the susceptible insect strain. Significant differences were observed (p < 0.0005 and CD = 5.3975) among Btk local isolates, H. armigera biotypes, Btk spore‐crystal mix concentration and their interactions, through the Multifactorial ANOVA analysis. The toxicity of local B. thuringiensis isolates was higher than that of HD‐1 (reference B.t.k strain). Indigenous Btk isolates have an enormous potential for the management of H. armigera in terms of development of resistance to HD‐1. The present study would serve as a baseline data for future resistance monitoring of B. thuringiensis strains in H. armigera in Southern India. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Protocol for Optimal Quality and Quantity Pollen DNA Isolation from Honey Samples

The present study illustrates an optimized sample preparation method for an efficient DNA isolation from low quantities of honey samples. A conventional PCR-based method was validated, which potentially enables characterization of plant species from as low as 3 ml bee-honey samples. In the present study, an anionic detergent was used to lyse the hard outer pollen shell, and DTT was used for isolation of thiolated DNA, as it might facilitate protein digestion and assists in releasing the DNA into solution, as well as reduce cross-links between DNA and other biomolecules. Optimization of both the quantity of honey sample and time duration for DNA isolation was done during development of this method. With the use of this method, chloroplast DNA was successfully PCR amplified and sequenced from honey DNA samples.

Complete mitochondrial genome of Chocolate Pansy, Junonia iphita (Lepidoptera: Nymphalidae: Nymphalinae).

Abstract The complete mitochondrial genome of Junonia iphita was determined to be 15,433 bp in length, including 37 typical mitochondrial genes and an AT-rich region. All the protein coding genes (PCGs) are initiated by typical ATN codons, except cox1 gene that is by CGA codon. Eight genes use complete termination codon (TAA), whereas the cox1, cox2 and nad5 genes end with single T; nad4 and nad1 ends with stop codon TA. All the tRNA show secondary cloverleaf structures except trnS1 (AGN). The A + T rich region is 546 bp in length containing ATAGA motif followed by a 18 bp poly-T stretch, two microsatellite-like (TA)9 elements and 8 bp poly-A stretch immediately upstream of trnM gene.

The near complete mitochondrial genome of the Giant honey bee, Apis dorsata (Hymenoptera: Apidae: Apinae) and its phylogenetic status

Abstract In this report, we sequenced and characterized the near complete mitochondrial genome of Apis dorsata collected from Mizoram, India. For sequencing of the complete mitochondrial genome, Illumina NextSeq500 platform was used. The near complete mitochondrial genome was assembled to be 15 076 bplong and contains the same gene order as the other honey bees. The assembly contains 13 protein coding genes, 21 transfer RNA, 2 ribosomal RNA and a partial control (A + T-rich) region estimated to be 75 bp. This is the first near complete sequenced mitochondrial genome from the giant honeybee A. dorsata which will benefit future genomics studies for understanding the phylogenetic relationship within the bee family.

Larvicidal activity of Ipomoea cairica (L.) Sweet and Ageratina adenophora (Spreng.) King & H. Rob. plant extracts against arboviral and filarial vector, Culex quinquefasciatus Say (Diptera: Culicidae).

Culex quinquefasciatus Say, an arboviral and filarial vector, is one of the most widespread mosquitoes in the world, and insecticide-resistant populations have been reported worldwide. Due to the emergence of resistance in C. quinquefasciatus plant based products or plant extracts may be alternative sources in integrated vector management program. The present study was carried out to establish the larvicidal activities of crude solvent extracts prepared from flowers and leaves of Ipomoea cairica and Ageratina adenophora against third instar larvae of C. quinquefasciatus as target species. The plant extracts were prepared with petroleum ether, chloroform and methanol solvents using sequential extraction method to determine the best extractant for subsequent isolation and characterization of active ingredient. The total yield of plant extract in the Soxhlet extraction ranged between 0.79% and 19.35%. The qualitative phytochemical study of the plant extracts from different solvents showed the presence of alkaloids, flavonoids, phenols, terpenes, saponins and tannins in different combinations. I. cairica and A. adenophora plant extracts were found to be effective against third instar larvae of C. quinquefasciatus causing 77-100% mortality at 48h. Highest mortality was observed at 500ppm and the order of larvicidal action was observed to be of methanol extract of I. cairica flower>petroleum ether extract of A. adenophora leaf>chloroform extract of I. cairica leaf. High mortality (100%) with low LC50 and LT50 were observed in methanolic flower extract (LC50 - 8.43ppm; LT50 - 2.51h at 48h) of I. cairica, and petroleum ether (LC50 - 133.56ppm; LT50 - 9.45h at 48h) leaf extract of A. adenophora. Lethal concentration (LC50 and LC90) values gradually decreased with the exposure periods, lethal time (LT50 and LT90) decreased with the concentration in bioassay experiment with the crude plant extracts. There was a significant correlation (three-way factorial ANOVA) was noticed among concentration of the plant extracts, exposure time and solvent extraction in relation to larval mortality (P<0.0001), which indicates that larval mortality is concentration dependent as well as time-dependent. Further in-depth study is needed to identify and characterize the active components present in the plant solvent extracts and implement the effective arboviral and filarial mosquito vector management program.

Anti-mite activities of Clerodendrum viscosum Ventenat (Verbenaceae) extracts on tea red spider mite, Oligonychus coffeae Nietner (Acarina: Tetranychidae)

Acaricidal and ovicidal activities of Clerodendrum viscosum Ventenat (Verbenaceae), a common weed of India, were investigated on tea red spider mite, Oligonychus coffeae Nietner (Acarina: Tetranychidae). Different solvent extracts (water, methanol, acetone and petroleum ether) of C. viscosum at different concentrations (1, 2, 4 and 8%) were used. These solvent extracts exhibited mortality of O. coffeae in the range of 40–90% in water, 67–97% in petroleum ether, 50–80% in acetone and 43–87% in methanol extract. Depending on LC50 values, the relative toxicity was found to be significantly highest against petroleum ether extracts and lowest in water extracts. Acetone extract of C.viscosum recorded maximum ovicidal activity followed by petroleum ether, methanol and the less by water extracts. In the field trials, mite population were significantly lower (P < 0.05) on plots sprayed with different of C. viscosum extracts than the control and at par with chemical acaricide and neem biopesticide. No phytotoxic effect (score, 0–5% and grade 1) was observed in the field from tea bushes sprayed with different doses of extracts of C. viscosum. Made tea samples were taint free. Organoleptic test revealed leaf infusions and liquor strength as good, scoring 6.5–7.0 on a 10-point scale. Availability and distribution of this weed (C. viscosum) in and around tea growing areas of sub-Himalayan region, along with its processing for the feasibility of including C.visosum extracts in the current IPM programme are discussed.