Specific identification, biology and symptoms of whitefly species infesting sunflower in South India

Whitefly species related to sunflower was identified as Bemisia tabaci (Gennadius). Further the identified whitefly species was confirmed to be indigenous B. tabaci on molecular basis by using B-biotype specific SCARs and biological silver leaf assay on sensitive pumpkin (cv Big variety). None of the whitefly samples could positive for the presence of B biotype. The results of the study on the pest life cycle under the laboratory conditions showed that, B. tabaci passed through four nymphal instars before the adult stage. The mean duration values of these stages were 5.6, 4.2, 4.4 and 5.6 days respectively. The total duration of the life cycle of B. tabaci ranged from 23- 42 days at the temperature of 29±2°C with a mean of 34.5. The damage to sunflower crop caused by the whitefly species is discussed with a special emphasis on its ability to transmit leaf curl viral disease

Biological and molecular evidences on host range of leaf curl begomovirus disease of sunflower (Helianthus annuus L.)

The present study was conducted to identify the alternate hosts of new leaf curl virus disease of sunflower. In the present study several crops and weed hosts were cross inoculated with leaf curl virus of sunflower under laboratory through insect vector whitefly (Bemisia tabaci), further all inoculated samples were retested (3-4 weeks after inoculation) by molecular based Polymerse chain reaction diagnosis for the presence of virus. The results revealed that the causal virus of the disease was successfully transmitted from sunflower to sunflower (Helianthus annuus), tomato (Solanum lycopersicum) and tobacco (Nicotiana tabacum L) and weed hosts such as Acanthospermum hispidum, Amaranthus viridis and Parthenium hysterophorus in a short incubation period (2-3 weeks after inoculation), while on other hosts Chilli (Capsicum annuum L) and Datura stramonium, infection occurs in delayed incubation period. Further molecular analysis thorough polymerase chain reaction (PCR) diagnostic technique using virus specific primers also confirmed the presence of coat protein (CP) of leaf curl begomovirus invirus inoculated hosts viz., chilli, sunflower, tomato, and tobacco and weed hosts such as Acanthospermum hispidum, Amaranthus viridis, Datura stramonium and Parthenium hysterophorus. Thus, findings substantiate that the above hosts are major sources of the virus inoculum and served as potential alternate hosts of the disease during the off season

Disruption of KEX1 gene reduces the proteolytic degradation of secreted two-chain Insulin glargine in Pichia pastoris

Insulin glargine is a slow acting analog of insulin used in diabetes therapy. It is produced by recombinant DNA technology in different hosts namely E. coli and Pichia pastoris. In our previous study, we have described the secretion of fully folded two-chain Insulin glargine into the medium by over-expression of Kex2 protease. The enhanced levels of the Kex2 protease was responsible for the processing of the glargine precursor with in the host. Apart from the two-chain glargine product we observed a small proportion of arginine clipped species. This might be due to the clipping of arginine present at the C-terminus of the B-chain as it is exposed upon Kex2 cleavage. The carboxypeptidase precursor Kex1 is known to be responsible for clipping of C-terminal lysine or arginine of the proteins or peptides. In order to address this issue we created a Kex1 knock out in the host using Cre/loxP mechanism of targeted gene deletion. When two-chain glargine was expressed in the Kex1 knock out host of P. pastoris GS115 the C-terminal clipped species reduced by â¼80. This modification further improved the process by reducing the levels of product related impurities. © 2015 Elsevier Inc. Elsevier Inc. All rights reserved

ANTIBACTERIAL ACTIVITY OF SYNTHESIZED SILVER NANOPARTICLES BY SIMAROUBAGLAUCA AGAINST PATHOGENIC BACTERIA

Objective: The present study outline the plant-mediated synthesis of silver nanoparticles (AgNPs) using leaf extract Simaroubaglauca, which act as both reducing and stabilizing agent.Methods: Formation of silver nanoparticles was confirmed by primarily by Ultraviolet/visible spectroscopy. X-ray diffraction studies revealed the crystallinity of the nanoparticles. The scanning electron microscopy was carried out to determine the mean particle size, as well as the morphology of the NPs and the composition of elements, was studied with Energy Dispersive X-ray analysis (EDS).Results: The silver nanoparticles were spherical in shape with a mean size of 23 nm. The EDS showed strong optical absorption peak at 3keV and it was confirmed the formation of AgNPs. The synthesised AgNPs further utilized for the evaluation of antibacterial activity and shown significant antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Enterobacter and Klebsiella pneumonia at 50 µg/ml and 100µg/ml concentrations.Conclusion: The synthesised silver nanoparticles have been characterised by UV-vis, SEM-EDAX and XRD to determine the sizes and shapes of the silver nanoparticles

Enhancement in production of recombinant two-chain Insulin Glargine by over-expression of Kex2 protease in Pichia pastoris

Glargine is an analog of Insulin currently being produced by recombinant DNA technology using two different hosts namely Escherichia coli and Pichia pastoris. Production from E. coli involves the steps of extraction of inclusion bodies by cell lysis, refolding, proteolytic cleavage and purification. In P. pastoris, a single-chain precursor with appropriate disulfide bonding is secreted to the medium. Downstream processing currently involves use of trypsin which converts the precursor into two-chain final product. The use of trypsin in the process generates additional impurities due to presence of Lys and Arg residues in the Glargine molecule. In this study, we describe an alternate approach involving overexpression of endogenous Kex2 proprotein convertase, taking advantage of dibasic amino acid sequence (ArgArg) at the end of B-chain of Glargine. KEX2 gene overexpression in Pichia was accomplished by using promoters of varying strengths to ensure production of greater levels of fully functional two-chain Glargine product, confirmed by HPLC and mass analysis. In conclusion, this new production process involving Kex2 protease over-expression improves the downstream process efficiency, reduces the levels of impurities generated and decreases the use of raw material

Breeding banana (Musa spp.) for drought tolerance: A review

Drought is a major abiotic stress affecting banana production worldwide, leading to yield losses of up to 65%. Consequently, numerous efforts to understand and mitigate drought effects that include developing tolerant crop varieties are ongoing in several banana breeding programmes. The breeding efforts, however, have been greatly slowed down by inherent banana problems (polyploidy and male or female sterility) and complexity of drought tolerance (reportedly controlled by several genes). This review summarizes the pertinent research findings on water requirements of banana for its proper growth and productivity, symptoms of drought‐sensitive varieties and field management strategies to cope with drought stress. The coping strategies deployed by resistant cultivars include high assimilation rates and water retention capacity as well as minor losses in leaf area and gaseous exchange. Reduced bunch weight, leaf chlorosis, wilting and strangled birth are underlined to be directly associated with drought susceptibility. Integration of conventional, molecular breeding and biotechnological tools as well as exploitation of the existing banana genetic diversity presents a huge opportunity for successful banana improvement