Differential Expression of Glutathione s-Transferase Enzyme in Different Life Stages of Various Insecticide-Resistant Strains of Anopheles Stephensi: A Malaria Vector

Background & objectives: Interest in insect glutathione s-transferases (GSTs) has primarily focused on their role in insecticide resistance. These play an important role in biotransformation and detoxification of many different xenobiotic and endogenous substances including insecticides. The GST activity among 10 laboratory selected insecticide resistant and susceptible/control strains of Anopheles stephensi was compared using the substrates 1-chloro-2,4-dinitrobenzene (CDNB). The difference in the GST activities of different life stages of diverse insecticide resistant strains was compared and presented.Methods: About 100 larvae, pupae, adult males, adult females and eggs (100 μg in total weight) were collected and used for the experiment. The extracts were prepared from each of the insecticide-resistant strains and control. Protein contents of the enzyme homogenate and GST activities were determined.Results: Deltamethrin and cyfluthrin-resistant strains of An. stephensi showed significantly higher GST activity. Larvae and pupae of DDT-resistant strain showed peak GST activity followed by the propoxur-resistant strain. On contrary, the GST activity was found in reduced quantity in alphamethrin, bifenthrin, carbofuran and chloropyrifos resistant strains. Adults of either sexes showed higher GST activity in mosquito strain resistant to organophosphate group of insecticides namely, temephos and chloropyrifos. Interpretation & conclusion: The GST activity was closely associated with almost all of the insecticides used in the study, strengthening the fact that one of the mechanisms associated with resistance includes an increase of GST activity. This comparative data on GST activity in An. stephensi can be useful database to identify possible underlying mechanisms governing insecticide-resistance by GSTs

Symmetry Energy in the Equation of State of Asymmetric Nuclear Matte

The symmetry energy is an important quantity in the equation of state of isospin asymmetric nuclear matter. This currently unknown quantity is key to understanding the structure of systems as diverse as the neutron-rich nuclei and neutron stars. At TAMU, we have carried out studies, aimed at understanding the symmetry energy, in a variety of reactions such as, the multifragmentation of $^{40}$Ar, $^{40}$Ca + $^{58}$Fe, $^{58}$Ni and $^{58}$Ni, $^{58}$Fe + $^{58}$Ni, $^{58}$Fe reactions at 25 - 53 AMeV, and deep-inelastic reactions of $^{86}$Kr + $^{124,112}$Sn, $^{64,58}$Ni (25 AMeV), $^{64}$Ni + $^{64,58}$Ni, $^{112,124}$Sn, $^{232}$Th, $^{208}$Pb (25 AMeV) and $^{136}$Xe + $^{64,58}$Ni, $^{112,124}$Sn, $^{232}$Th, $^{197}$Au (20 AMeV). Here we present an overview of some of the results obtained from these studies. The results are analyzed within the framework of statistical and dynamical models, and have important implications for future experiments using beams of neutron-rich nuclei.Comment: 10 pages, 4 figures, talk presented at VI Latin American Symposium on Nuclear Physics and Application

Effective nucleon mass and the nuclear caloric curve

Assuming a schematic form of the nucleon effective mass as a function of nuclear excitation energy and mass, we provide a simple explanation for understanding the experimentally observed mass dependence of the nuclear caloric curve. It is observed that the excitation energy at which the caloric curve enters into a plateau region, could be sensitive to the nuclear mass evolution of the effective nucleon mass.Comment: 5 pages, 5 figures, Accepted for publication in Phys. Rev. C. Minor changes mad

Insecticide susceptibility status in three medically important species of mosquitoes, Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus, from Bruhat Bengaluru Mahanagara Palike, Karnataka, India

Background: Development of resistance among mosquito vectors of diseases is of growing concern in many countries of the subtropics, including much of India. The distributions of susceptibility/resistance to insecticides are scarcely recorded and are unknown in many parts of India. This manuscript reports the susceptibility status among strains of Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus collected from different geographical areas of Bruhat Bengaluru Mahanagara Palike (BBMP), Karnataka, to six conventionally used insecticides. Results: An. stephensi, Ae. aegypti and Cx. quinquefasciatus from different geographic areas showed susceptibility towards temephos. However, susceptibility was meagre for most of the other insecticides used in the study. Strong resistance to propoxur was reported in Ullala (RR90 = 467.1) and Bannerghatta (RR90 = 12 265) populations of An. stephensi and Ae. aegypti respectively. RR90 â 12 830 was recorded as higher in the Yelahanka (YLK) population of Cx. quinquefasciatus to neem. Significant differences at LC50 and LC90 concentrations were observed against various insecticides in different mosquito populations. Resistance was observed against some of the larvicides for the diagnostic dose recommended by WHO. Conclusion: The results form baseline data on the susceptibility status of three medically important mosquito vectors of diseases to commonly used insecticides in the field at present emphasise the importance of carrying out more effective and planned vector control measures. © 2012 Society of Chemical Industry

Glutathione S-Transferase activity and total thiol status in chronic alcohol abusers before and 30 days after alcohol abstinence

Background: Glutathione S Transferase (GST) has been involved in detoxification process in the liver and its activity has been shown to be increased in alcohol abusers. In the current work we measured the GST activity, total thiol status, AST, ALT, and direct bilirubin in chronic alcohol abusers before and 30 days after alcohol abstinence and lifestyle modification. Methods: Serum and urine GST activity and total thiol status were determined using spectrophotometric methods and serum transaminases were determined using clinical chemistry analyzer. Results: We found,significant increase in serum and urine GST (p<0.001), AST (p<0.001), ALT (p<0.001), and decrease in total thiol status (p<0.001) in chronic alcohol abusers. GST activity significantly decreased (p<0.001) and total thiol status were improved significantly (p<0.001) 30 days after alcohol abstinence and lifestyle modification. Conclusion: This study provides preliminary data to suggest the role of GST as prognostic indicator of alcohol abstinence with possible trend towards an improvement in liver function

Tracing the evolution of the symmetry energy of hot nuclear fragments from the compound nucleus towards multifragmentation

The evolution of the symmetry energy coefficient of the binding energy of hot fragments with increasing excitation is explored in multifragmentation processes following heavy-ion collisions below the Fermi energy. In this work, high-resolution mass spectrometric data on isotopic distributions of projectile-like fragments from collisions of 25 MeV/nucleon 86Kr and 64Ni beams on heavy neutron-rich targets are systematically compared to calculations involving the Statistical Multifragmentation Model. The study reveals a gradual decrease of the symmetry energy coefficient from 25 MeV at the compound nucleus regime (E*/A < 2 MeV) towards 15 MeV in the bulk multifragmentation regime (E*/A > 4 MeV). The ensuing isotopic distributions of the hot fragments are found to be very wide and extend towards the neutron drip-line. These findings may have important implications to the composition and evolution of hot astrophysical environments, such as core-collapse supernova.Comment: 5 pages, 4 figures, submitted to Phys. Rev.

The decay time scale for highly excited nuclei as seen from asymmetrical emission of particles

A novel method was developed for the extraction of short emission times of light particles from the projectile-like fragments in peripheral deep-inelastic collisions in the Fermi energy domain. We have taken an advantage of the fact that in the external Coulomb field particles are evaporated asymmetrically. It was possible to determine the emission times in the interval 50-500 fm/c using the backward emission anisotropy of alpha-particles relative to the largest residue, in the reaction 28Si + 112Sn at 50 MeV/nucleon. The extracted times are consistent with predictions based on the evaporation decay widths calculated with the statistical evaporation model generalized for the case of the Coulomb interaction with the target.Comment: 13 pages, 5 figures, submitted to Phys. Lett.

Timescale for equilibration of N/Z gradients in dinuclear systems

Equilibration of N/Z in binary breakup of an excited and transiently deformed projectile-like fragment (PLF*), produced in peripheral collisions of 64Zn + 27Al, 64Zn, 209Bi at E/A = 45 MeV, is examined. The composition of emitted light fragments (3<=Z<=6) changes with the decay angle of the PLF*. The most neutron-rich fragments observed are associated with a small rotation angle. A clear target dependence is observed with the largest initial N/Z correlated with the heavy, neutron-rich target. Using the rotation angle as a clock, we deduce that N/Z equilibration persists for times as long as 3-4 zs (1zs = 1 x 10^-21 s = 300 fm/c). The rate of N/Z equilibration is found to depend on the initial neutron gradient within the PLF*.Comment: 6 pages, 4 figure