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Lokeshwari D.,Indian Institute of Horticultural Research | Hayat M.,Aligarh Muslim University | Kumar N.K.K.,Indian Council of Agriculture Research | Manjunatha H.,Kuvempu University | Venugopalan R.,Indian Institute of Horticultural Research
Florida Entomologist | Year: 2014

An aphid parasitoid, Aphelinus basilicus Fatima & Hayat (Aphelinidae: Aphelininae) is described from material collected in Bengaluru, Karnataka for the first time. It was found to parasitize apterous viviparous females of the cotton aphid, Aphis gossypii (Glover) infesting Gossypium hirsutum (Malvaceae), during Jul, 2013. Field data indicated that the parasitoid, Aphelinus basilicus parasitized dark green forms (88%) of A. gossypii more frequently than pale green (24%) and yellow forms (2%) suggesting that the body color strongly influenced the host preference for foraging. The 3 color forms were differentially susceptible to selection by the parasitoid. Statistical analysis revealed that the parasitoid had an inherent preference for dark green forms (P < 0.05). Information on the parasitoid's distribution, diagnostic characters, host range and host preference are presented to ease the identification as well as to understand the fundamentals of host selection behavior of this species. This is a new distributional record of Aphelinus basilicus parasitizing color forms of A. gossypii associated with G. hirsutum in Karnataka, India. Source

Lokeshwari D.,Indian Institute of Horticultural Research | Krishna Kumar N.K.,Indian Council of Agriculture Research | Manjunatha H.,Kuvempu University
Journal of Economic Entomology | Year: 2016

The melon aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is an important cosmopolitan and extremely polyphagous species capable of causing direct and indirect damage to various crops. Insecticide resistance in melon aphids is of particular concern. To determine the basis of resistance, organophosphate (OP)-resistant strains of A. gossypii were obtained by continuous selection with dimethoate in the laboratory, and resistance mechanisms were investigated along with susceptible strains. Three resistant strains LKR-1, LKR-2, and LKR-3 exhibiting 270-, 243-, and 210-fold resistance obtained after 30 generations of selection with dimethoate, respectively, were utilized in this study. The role of acetylcholinesterase (AChE), a target enzyme for OPs and carbamates (CMs), was investigated. AChE enzyme assay revealed that there was no significant change in the activities of AChE in resistant and susceptible strains. However, AChE inhibitory assay showed that 50% of the enzyme activity in resistant strains was inhibited at significantly higher concentration of dimethoate (131.87, 158.65, and 99.29 μmolL-1) as compared with susceptible strains (1.75 and 2.01 μmolL-1), indicating AChE insensitivity owing to altered AChE. Molecular diagnostic tool polymerase chain reaction-restriction fragment length polymorphism revealed the existence of two consistent non-synonymous point mutations, single-nucleotide polymorphism, viz., A302S (equivalent to A201 in Torpedo californica Ayres) and S431F (equivalent to F331 in T. californica), in the AChE gene Ace2 of resistant strains. Further, cloning and sequencing of a partial fragment of Ace2 (897 bp) gene from susceptible and resistant strains revealed an additional novel mutation G221A in resistant strains, LKR-1 and LKR-2. Susceptible Ace2 genes shared 99.6 and 98.9% identity at the nucleic acid and amino acid levels with resistant ones, respectively. Functional analysis of these point mutations was assessed by in silico docking studies using the modeled wild-type and naturally mutated AChE2. Computational analysis showed that the conformational changes in AChE2 active site due to structural gene substitutions (A302S, S431F, and G221A) significantly reduced the level of ligand (OP-dimethoate, omethoate, and CM-pirimicarb) binding, suggesting that they are potentially associated with resistance development. These results unambiguously suggested that multiple mutations located in the enzyme active site are responsible for AChE insensitivity to dimethoate and are likely the molecular basis for dimethoate resistance in these selected field populations of A. gossypii. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. Source

Lekshmy S.,Indian Agricultural Research Institute | Jain V.,Indian Agricultural Research Institute | Jain V.,Indian Council of Agriculture Research | Khetarpal S.,Indian Agricultural Research Institute | Pandey R.,Indian Agricultural Research Institute
Indian Journal of Plant Physiology | Year: 2013

Wheat (Triticum aestivum L.) cv PBW 343 was grown in Hoagland solution devoid of nitrogen (-N) under two CO2 levels viz. ambient (380 μL L-1, AC) and elevated (600 ± 50 μL L-1, EC) for 20 days in growth chambers. The rate of uptake, assimilation and accumulation of nitrate was compared. At lows nitrate concentration up to 0.5 mM, rate of nitrate uptake was higher in EC grown seedlings as compared to AC. Under non-limiting supply of external nitrate, the rate of uptake declined in EC grown seedlings. Nitrate reductase (NR) activity increased in EC grown seedlings at low external concentrations of nitrate. However, AC grown plants showed higher NR activity, but at very high concentrations of nitrate. EC grown plants showed low level of accumulation of nitrate in shoots under limited nitrate availability, indicating lower influx towards storage pool and more availability of nitrate in metabolic pool. Increasing nitrogen (N) fertilization therefore may not compensate for slower NO3}- assimilation rates under EC, as uptake and assimilation both decline under nitrate sufficient conditions. Effective management practices and changes in the pattern of fertigation may be required in response to rising atmospheric CO2 levels for wheat production. © 2013 Indian Society for Plant Physiology. Source

Marudhupandi T.,Annamalai University | Marudhupandi T.,Sathyabama University | Sathishkumar R.,Annamalai University | Kumar T.T.A.,Annamalai University | Kumar T.T.A.,Indian Council of Agriculture Research
Biotechnology Reports | Year: 2016

Response surface methodology (RSM) was used to enhance the biomass and lipid content in Nannochloropsis salina due to its economic importance. Preliminary screening results revealed that the heterotrophically cultivated N. salina with various carbon and nitrogen sources yielded higher biomass (0.91 ± 0.0035 g/L) and lipid content (37.1 ± 0.49 mg/L) than that of the photoautotrophical cultivation (0.21 ± 0.009 g/L and 22.16 ± 0.27 mg/L). Significant sources that greatly influenced on biomass and lipid content of the alga were optimized through RSM. The medium consisting of glucose (7.959 g/L), sodium acetate (1.46 g/L), peptone (7.6 g/L) and sodium thiosulphate (1.05 g/L) was found to be the optimal concentration for heterotrophic cultivation by response optimizer. Confirmation experiment results for the RSM optimized concentration yielded the biomass of 1.85 g/L and total lipid content of 48.6 mg/L. In this study, we provide with a strategy for enhancing the biomass and lipid content in N. salina. © 2016 Published by Elsevier B.V. Source

Marudhupandi T.,Annamalai University | Marudhupandi T.,Sathyabama University | Ajith Kumar T.T.,Annamalai University | Ajith Kumar T.T.,Indian Council of Agriculture Research
International Journal of Biological Macromolecules | Year: 2015

The present study was conducted to evaluate the anticancer activity of fucoidan isolated from brown seaweed Turbinaria conoides. Extracted fucoidan contained 53±0.69% of fucose and 38±0.42% of sulphate, respectively. Functional groups and structural characteristics of the fucoidan were analyzed by FT-IR and NMR. In vitro anticancer effect was studied on A549 cell line. Fucoidan inhibited the growth of cancer cells in a dose-dependent manner and potent anticancer activities were 24.9-73.5% in the concentrations of 31.25-500μg/ml. The CTC50 value against the cancer cell was found to be 45μg/ml and the CTC50 value of normal Vero cell line is 325μg/ml. This study suggests that the fucoidan from T. conoides could be significantly improved if the active component is further purified and tested for further investigation in various cancer cell lines. © 2014 Elsevier B.V. Source

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