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Articles by A.K. Sinha
Total Records ( 11 ) for A.K. Sinha
  A.Z. Bochev and A.K. Sinha
  We show examples of long period Pc5 magnetic field pulsations near field-aligned current (FAC) regions in the high-latitude magnetosphere, observed by INTERBALL-Au, and coordinated with POLAR, GOES-9 and ground-based observations during 11 January and 11 April 1997. Identification of corresponding magnetosphere regions and subregions is provided by electrons and protons in the energy-range of 0.01–100 keV measured onboard the spacecraft. The ULF Pc5 wave occurrence is observed in both upward and downward FACs. A fairly good correlation is demonstrated between these ULF Pc5 waves and the consecutive injection of magnetosheath low energy protons. The constancy of the observed frequency peak at 1.8 mHz during quite unsteady solar wind pressure conditions could be reconciled with the surface wave mode model. The 3.1 mHz peak location area probably resembles field-line fluctuations with an interesting appearance of poloidal mode oscillation. It is suggested that the 1.3 mHz wave and its harmonic 2.6 mHz represent global compressional oscillations.
  D. Kumar , J.P. Pandey , A.K. Sinha , S. Salaj , P.K. Mishra and B.C. Prasad
  The Antheraea mylitta produces tasar silk having massive demand in international market. Its rearing is carried out in outdoor conditions and during course of I to III instar rearing, a major proportion (20-30%) of larvae die due to vagaries of nature, pests and predators etc. which considerably affects the production and productivity. The solution to this major bottleneck of the silkworm rearing lies in evolving a suitable tasar silkworm feed (semi-synthetic diet) for young age tasar silkworm. In present study, comparative evaluation was done among semi-synthetic diet fed; fresh leaf fed indoor reared and fresh leaf fed in natural outdoor reared insects. Data revealed that young age survival and Effective Rate of Rearing (ERR) were higher when larvae were brushed on semi-synthetic diet in contrast to indoor rearing on fresh leaf and complete outdoor rearing. Semi-synthetic diet fed larvae showed greater body weight and their cocoon showed higher weight, shell weight and shell ratio than controls. Concentration of hemolymph protein was slightly higher in semi-synthetic diet fed than outdoor reared larvae whereas, significantly lower in case of indoor reared. Hemolymph protein SDS-PAGE analysis indicates that, the semi-synthetic diet fed larvae is closer to complete outdoor reared larvae than indoor reared. Comparative assessment of rearing, cocoon trait and biomolecular profile of A. mylitta it is assumed that tasar feed developed by our laboratory is novel. It will be helpful in minimizing impact of unfavorable condition during I crop rearing and maintenance of precious eco-races stocks to enhance productivity of tasar silk.
  B.C. Prasad , J.P. Pandey and A.K. Sinha
  Cocoonase which is secreted as a natural phenomenon has its direct utility in softening of cocoons for reeling without altering the very organic nature of tasar silk. In the present study, efforts have been made to comprehend and utilize cocoonase for its future use in cocoon cooking. The emerging moth gradually release cocoonase from galea of their mouth parts in anterior inner portion of the cocoon (peduncle region). After releasing adequate volume of enzyme (around 400-600 μL) for softening the peduncle region of cocoon, with the help of appendages emerging moth create outlet near the peduncle and escape from cocoon shell. Around 1000 mL cocoonase from 2000 eclosion stage A. mylitta have been collected and centrifuged in cold condition (4°C) at 10000 rpm to minimise the impurity. To maintain buffer conditions, cocoonase was collected in pre chilled Tris buffer pH 9.2 and stored at -4°C temperature for further use in cocoon cooking. When cocoons of A. mylitta (Daba ecorace) were subjected to initial water boiling at 100°C on leisurely flame for 30-40 min followed by cocoon soaking in cocoonase for 20-24 h at 37°C, the 80-90% softening of cocoon shell was found. Silk filament obtained from the cocoons cooked in cocoonase maintains natural tasar silk colour, softness and structure. The 50-52% silk recovery was observer in cocoonase cocoon cooking. By centrifuging used reaction mixture at 9000 rmp in cold condition to remove impurities and adding 10-15% volume of fresh cocoonase in reaction mixture left over enzyme solution can be reused once. More study is required to get better cocoonase cooking efficiency and consistent cooking with higher or comparable silk recovery than the ruling practices.
  J.P. Pandey , P.K. Mishra , Dinesh Kumar , A.K. Sinha , B.C. Prasad , B.M.K. Singh and T.K. Paul
  Generally, Antheraea mylitta cocoons cooking is carried out in alkaline condition by using soap, soda, H2O2, etc., which adversely affects the natural beautiful colour and softness of tasar silk. At eclosion stage, the emerging adults of tasar silkworm, A. mylitta exude a proteolytic enzyme ‘cocoonase’ which helps in softening anterior portion of cocoon shell and facilitates emergence of moths. Interestingly, cocoonase directly acts on the sericin protein without affecting the fibroin protein. It evidently indicates that, sericin is excellent natural substrate of cocoonase. This natural phenomenon engenders an idea to collect the cocoonase of A. mylitta and investigate its possible-efficacy in cocoon cooking. The SDS-PAGE analysis of freshly collected cocoonase (from emerging moths) showed molecular weight around 26 kDa. A simple technique for cocoonase collection from freshly pierced cocoons has been developed. Cooking of cocoon in cocoonase is concentration, pH, temperature and time dependent. Low concentration (1:15, 1:20, 1:25, 1:30 and 1:35) increases the cooking time and decreases the cooking efficiency. Higher concentration (1:5 dilutions) minimises the cocking time and increases the cooking efficiency. But cocoons were not fully reeled due to hardness in inner portion of the cocoons. Initial boiling of cocoon in water for 30 min followed by cooking in cocoonase (1:5) at 35-40°C temperature and 8.5 to 9.0 pH yielded comparatively better cooking efficiency with 50-55% silk recovery. Yarn obtained from the cocoons cooked in cocoonase preserve natural beautiful unique tasar silk colour, softness and lustre.
  K.N. Madhusudhan , G. Vinayarani , S.A. Deepak , S.R. Niranjana , H.S. Prakash , G.P. Singh , A.K. Sinha and B.C. Prasad
  The present study was aimed to investigate the effect of inducers viz., plant extracts, plant seed oils and salicylic acid on tobamoviruses in both indicator and host plant. Tobamoviruses are major hurdles in the production of tomato and bell pepper. Currently, different inducers derived from various origins are being used to reduce the virus concentration. Preliminary screening of the inducers against tobamoviruses was conducted by using the local lesion assay (Nicotiana glutinosa). The results showed that all the inducers used for screening were effective in reducing the number of local lesions formed by the challenge inoculation of tobamoviruses. Both spray and seed treatment of inducers against the tobamoviruses reduced the concentration of viruses in the seedlings as evident from the results of Indirect Enzyme linked immunosorbent assay. Among the inducers used for the induction of resistance against tobamoviruses, Bougainvillea spectabilis extract was found to be most effective. The inducer-treated seeds also showed enhancement of seed germination and seedling vigor.
  K.P. Kiran Kumar , A.K. Sinha , S.K. Gupta , K.N. Madhusudhan and B.C. Prasad
  Pebrine disease in tasar silkworm is considered to be most serious because of its chronic pathogenicity. Prophylactic method of mother moth examination proves to be the foolproof technique for pebrine identification. So, the study was conducted to investigate pebrine spores detection competency and evaluation of their quality in exhisting mother moth examinations. Four existing mother moth examination methods namely Prick and See, Conventional, Fuziwara and Delayed Mother Moth Examination (DMME) by Fuziwara were selected for the study. The maximum pebrine and hatching percentages were noticed in 4 days DMME with 23.2 and 93.1%, respectively. While, minimum values were observed in prick and see with 4.3% and 84.3, respectively. No significant variations in Cocoon weight, Shell weight and S.R% was observed in cocoons obtained from the different mother moth testing methods. Least percentage of effective rate of rearing (ERR) was observed in Prick and See method (58.75%) followed by Conventional method (61.25%) and Fuziwara (63.15%). High percentage of ERR was observed in DMME which ranged from 64.53% (1st day after egg laying) to 67.28% (4th day after egg laying). Least percentage of improvement of ERR% over Prick and See was observed in Conventional (2.50%) followed by Fuziwara (4.40%). High percentage of ERR over Prick and See was observed in DMME which ranged from 5.78% (1st day) to 8.53% (4th day). Consequently, among the tested mother moth examinations, DMME by Fuziwara after delaying four days from the egg laying has given best results. This method can be implemented in the research institutions for the maintenance of germplasm and breeders stock.
  J.P. Pandey , Dinesh Kumar , Sony K. Roy , P.K. Mishra , A.K. Sinha and B.C. Prasad
  Tropical tasar silkworm, Antheraea mylitta Drury DABA-ecorace is commercially exploited in India for tasar silk production. Generally, its cocoons used to preserve in outdoor and indoor conditions. But in recent past, due to global warming, tasar silk zone day time temperature (May-June) shoots up and it goes up to 35 to 45°C or even more. It cause adverse impact on the survival of tasar silkworm pupae and invite heavy loss to the tasar silk industry. In the present study, hemocyte and enzyme-based methods have been used to evaluate the impact of outdoor and indoor seed cocoon preservation on A. mylitta pupae. Interestingly, differences in Total Hemocyte Count (THC), hemocyte contour/morphology, protein concentration, fat body and hemolymph acid phosphatase (Acp) activity of outdoor and indoor preserved pupae have been observed. Marked variation in THC was observed among high, low and median weight pupae. Although, no significant variation was observed in THC of indoor and outdoor preserved female pupae but significant difference was found in male pupae of both the preservation conditions. Differential profile of hemocytes was differing in outdoor and indoor conditions with change in cell-contour. Elevation in immune cell “plasmatocytes (PLs)” numbers was recorded in indoor preserved cocoon. Acp activity in fat body of indoor preserved pupae was higher than outdoor but reverse trend was found in hemolymph. Activity profile Acp vary in male and female with higher, lower and median weight pupae. Protein concentration in hemolymph of outdoor preserved pupae was more in comparison to indoor but this trend was found usually reverse in fat body. In addition, less protein concentration was recorded in fat body and hemolymph of male pupae in contrast to female. It is expected that, based on hemocyte and enzyme-based method impact of cocoon preservation conditions on A. mylitta pupae can be evaluated/observed.
  Dinesh Kumar , J.P. Pandey , Ragini , A.K. Sinha and B.C. Prasad
  The tropical tasar silkworm, Antheraea mylitta Drury is sericigenous wild insect has own dictation on its life cycle stages. Being a poikilothermic organism, temperature decides the fate of A. mylitta during embryonic and postembryonic development. Silkworm eggs (seed) is very vital input of tasar silk industry but due to global warming elevation in temperature with less humidity during 1st crop grainage of A. mylitta negatively affects the quality and quantity of egg hatching. In the present study, impact of temperature stress on embryonic development and biochemical profile of A. mylitta eggs has been investigated. Data reveals that considerable alteration in temperature used to hamper the protein and carbohydrate profile which leads to affect the embryonic development and hatching of eggs. Fluctuation in temperature with low humidity causes delay in egg hatching and decrease in hatching percentage. But higher temperature with low humidity during embryonic development of eggs resulted in death of embryo during early age. The depressed eggs with fully formed dead larvae inside the eggs were found after high temperature stress. The concentration of the protein and carbohydrate steadily decreases during subsequent larval differentiation until hatching. Protein and carbohydrate profile also confirm the death of embryo during early stage. In un-hatched eggs, due to less metabolized utilization higher concentration of these nutrients are available. Our initial information indicates that protein and carbohydrate profile can be utilized as biochemical marker for testing appropriate embryonic development and hatchability of eggs.
  K.P. Kiran Kumar , G.P. Singh , A.K. Sinha , K.N. Madhusudhan and B.C. Prasad
  Among the diseases of tasar silkworm, virosis caused by Cytoplasmic Polyhedrosis Virus (CPV) is highly contagious and more prevalent. Thirteen antiviral plants were used to test their efficacy against Antherae mylitta cytoplasmic polyhedrosis virus (AmCPV) in tasar silkworm. The aqueous extracts of these plants in different concentrations were used for containment of virosis in virus-infected silkworm and mortality was recorded. The influence of best three phytoextracts which have shown good results in suppressing virosis were subjected for the study of cellular and biochemical changes. Two percent aqueous extracts of Aloe barbedensis (AKP 3), P. corylifolia (AKP13) and Bougainvillea spectabilis (AKP 9) were found more effective in suppressing the virosis and reduced the mortality due to virus infection of 66.17, 64.47 and 57.19%, respectively. The total hemocyte count increased up to 6th day of post inoculation in phytoextract treated batches while in the inoculated control the increase was within 3 days indicating the positive hemocyte mediated response in silkworm treated with phytoextract. The hemolymph protein in Aloe barbedensis treated silkworm (35.27 mg mL-1) was significantly higher than inoculated control (20.25 mg mL-1). The gradual increase of total hemolymph proteins from 1st day (16.31 mg mL-1) to 8th day (33.73 mg mL-1) was observed in healthy control where as in inoculated control increasing trend was observed from day 1 (16.26 mg mL-1) to day 3 (24.22 mg mL-1) there after decreasing trend was observed and finally reached to 20.25 mg mL-1 (8th day). The plant extract of Aloe barbedensis (AKP 3) is more effective in suppressing virosis based on the results of mortality reduction against virosis cellular and biochemical changes.
  K.P. Kiran Kumar , A.K. Sinha , G.P. Singh and K.N. Madhusudhan
  Penicillium citrinum causes white muscardine in tasar silkworm and significantly damage cocoon production at farmer’s field. Four systemic fungicides Bavistin, a carbandazim fungicide (AK 1), Bayleton, a triazole compound (AK 2), Dithane M-45, a mancozeb fungicide (AK 3) and Thiram, a dimethyl dithiocarbamate (AK 4) were tested for efficacy to control white muscardine in, Antheraea mylitta D. One and two percent of AK 1 and AK 3, 0.15 to 2% of AK 2 and 2% of AK 4 in aqueous solution were found to be effective in in vitro condition for the control of muscardine. These fungicides on feeding through the T. arjuna leaves continuously for two days in 5th instar larvae inoculated topically with conidia of Penicillium citrinum (4x106 conidia mL-1) resulted in reduction in mortality due to muscardine by 49-94% as against 100% mortality in inoculated control (control 6). AK 1 reduced the mortality by 93 and 94% in the final instar silkworm at 1 and 2%, respectively. AK 2 at 0.05 and 0.1% concentration reduced the mortality by 85 and 87%, respectively. In case of AK 3 and AK 4 at 1% concentration reduced the mortality by 88 and 69%, whereas at 2% reduced mortality by 90 and 75%, respectively. No mortality was noticed in the controls 1 to 4 which indicated the non toxicity at the particular concentrations. Bavistin (AK 1) and Dithane M-45 (AKP 3) at 1 and 2% concentrations were more effective among tested systemic fungicides in suppressing muscardine in tasar silkworm.
  G.P. Singh , A.K. Sinha , P.K. Kumar and B.C. Prasad
  Tropical tasar silkworm, Antheraea mylitta D., an economically important insect is affected by bacteriosis caused by bacteria, which accounts considerable loss of 10-15% to silk cocoon production. The aim of the present investigation was to isolation, characterization and identification of bacteria causing diseases in Indian tropical tasar silkworm, Antheraea mylitta D. Total 15 isolates of bacteria in two groups (8 from anal lip sealing diseased silkworms and 7 from rectal protrusion diseased worms) were isolated. The shape, size and colour of bacterial colony were recorded. The gram reaction of vegetative cells, its shape, size and pattern of reaction with different enzymes were observed for characterization of different bacterial isolates. Pathogenecity of these bacteria have shown that only two bacterial isolates coded SA3 and RP2 were responsible for anal lip sealing and rectal protrusion diseases, respectively in tasar silkworm. The bacterial isolates coded SA3 and RP2 on the basis of cultural, morphological and biochemical characters tentatively identified as Serratia sp. which were, close to Serratia nematodiphila and Serratia marcescens sub sp., respectively. The infection of anal lip sealing and rectal protrusion diseases in Indian tropical tasar silkworm caused by Serratia nematodiphila and Serratia marcescens was reported first time.
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