Abstract--Different amylase enzymes were identified by analysis of digestive fluid and haemolymph in diapausing and nondiapausing strains of silkworm, Bombyx mori. The diapausing strain showed negligible digestive amylase activity at a pH range of 3-11, while the nondiapausing strain registered strikingly higher amylase activity at pH 9.2. Higher levels of undigested starch was found in the faecal matter of the diapausing strain, which is consistent with the negligible digestive amylase activity. Developmental specific expression of haemolymph amylase activity was seen in nondiapausing and diapausing strains. In the nondiapausing strain the digestive amylase activity was at its peak during intermoult and depressed during moult. PAGE analysis revealed the occurrence of only anodal digestive and haemolymph amylases in the diapausing strain, whereas both cathodal and anodal enzymes were seen in the digestive fluid and haemolymph of the nondiapausing strain.
Silkworm genetic resources that are being maintained in different countries are yet to be adequately tapped to develop elite varieties that are suited to different agro-eco-climatic conditions of countries like India. This is mostly due to unavailability of efficient protocols that could uncover usable genetic variability in silkworms. Molecular markers are known to provide unambiguous estimates of genetic variability of populations since they are independent of confounding effects of environment. The DNA fingerprinting assays, based on random amplified polymorphic DNA (RAPD) and banded krait minor satellite DNA (Bkm) 2(8) multilocus probes, which successfully characterise the diverse silkworm genotypes at their DNA level, are described. The use of these two DNA fingerprinting assays in estimation of within- and between-population genetic diversity is discussed.
Basement exploration in India has seen increased interest after the recent discovery of a field in the Cauvery Basin in southeastern India, with an average individual well production of 700 b/d from a fractured basement reservoir. The field is presently under development, with several development well locations identified for drilling. Optimized development of a fractured basement reservoir requires identification of areas with a permeable fracture network. To meet this objective, we adopted a comprehensive integrated workflow involving the use of common reflection angle migrated seismic data, fracture modeling, a 1D mechanical earth model (MEM), identification of critically stressed fractures in 3D space, fracture permeability/connectivity analysis, and sweet spot identification. The workflow yielded a robust discrete fracture network model based on 3D directional fracture intensity, a 1D MEM that gave regional stress gradients (pore pressure, overburden, Shmin, and SHmax), and rock strength and elastic properties. In addition, we generated a critically stressed 3D fracture model and performed sequential stratal surface restoration for predictive strain modeling that was calibrated at wells. Our fracture permeability and connectivity analysis showed that existing hydrocarbon-producing wells are located within areas that have a fracture cluster/swarm with associated good fracture connectivity. A 3D basement facies model constructed by integrating well data and a poststack inversion impedance volume showed that major flow zones occur in weathered basement associated with low impedance. This model, in combination with fracture intensity data, provides good indication of the location of basement sweet spots in the Cauvery Basin. The understanding gained on the controls of occurrence of basement fractures explains why some wells in the field are producers and others are dry. This led to greater confidence in optimizing the locations of previously proposed new development wells.
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