Biochemical analysis and synergistic suppression of indoxacarb resistance in Plutella xylostella L.

Indoxacarb was treated to Plutella xylostella for 10 generations to develop a resistant strain and biochemical analysis of indoxacarb resistance in different tissues of P. xylostella was carried out. Biochemical analysis found maximum esterase activity in gut homogenates of indoxacarb resistant strains followed by whole body and cuticle homogenates. In gut homogenates of indoxacarb resistant strains, maximum increase in esterases was found as compared to the unselected strain. Acetylcholineesterase activity was higher in head homogenates of the resistant strain than in the unselected strain. Glutathione-S-transferase activity was highest in whole body homogenates. However, maximum increase was found in gut homogenates of indoxacarb resistant strains over the unselected. Induced resistance was suppressed using known synergists. Maximum synergism occurred using diethyl-maleate (DEM), followed by triphenyl phosphate (TPP).     

Genetic Correlations and Maternal Effect Coefficients Obtained from Offspring-Parent Regression

Additive genetic variances and covariances of quantitative characters are necessary to predict the evolutionary response of the mean phenotype vector in a population to natural or artificial selection. Standard formulas for estimating these parameters, from the resemblance between relatives in one or two characters at a time, are biased by natural selection on the parents and by maternal effects. We show how these biases can be removed using a multivariate analysis of offspring-parent regressions. A dynamic model of maternal effects demonstrates that, in addition to the phenotypic variance-covariance matrix of the characters, sufficient parameters for predicting the response of the mean phenotype vector to weak selection are the additive genetic variance-covariance matrix and a set of causal coefficients for maternal effects. These can be simultaneously estimated from offspring-parent regressions alone, in some cases just from the daughter-mother regressions, if all of the important selected and maternal characters have been measured and included in the analysis.     

Internal waves, primary production and the compensation depth of marine phytoplankton

Internal waves increase the average light intensity experiencedby phytoplankton and augment the compensation depth below whichno net photosynthesis occurs. These effects may be quite largein eutrophic waters with moderate or high light attenuationcoefficients. Data on internal waves and light attenuation canbe used to correct standard estimates of (new) primary productionin the lower euphotic zone based on uptake rates of carbon ornitrogen isotopes.     

Two-dimensional electrophoretic analysis of human erythrocyte cylindrin

In the absence of a peptidylproline substrate, the oxidative decarboxylation of 2-oxoglutarate by prolyl 4-hydroxylase (prolyl-glycyl-peptide,2-oxoglutarate:oxygen oxidoreductase (4-hydroxylating), EC 1.14.11.2) is stoicheiometrically coupled to the oxidation of ascorbate. The Km and Kd for O2 in this partial reaction are 1.5 mM, this value being one order of magnitude higher than the Km and Kd for O2 in the complete reaction in the presence of (Pro-Pro-Gly)5, indicating that in this case O2 can become enzyme-bound predominantly after the interaction of the peptide substrate with the enzyme. The Km values for 2-oxoglutarate in the partial and the complete reactions are the same. In the absence of both a peptide substrate and ascorbate 2 mol CO2 per mol enzyme are produced in the first 1-1.5 min, during which the enzyme becomes inactivated and, as shown earlier (De Jong , L., Albracht , S.P.J. and Kemp, A. (1982) Biochim. Biophys. Acta 704, 326-332) enzyme-bound Fe2+ becomes oxidized to Fe3+. The results are consistent with a mechanism in which a Fe2+O complex is the O-transferring intermediate involved in peptidylproline hydroxylation.     

The Influence of the Mating System on the Maintenance of Genetic Variability in Polygenic Characters

The traditional models of the effect of assortative mating and inbreeding on the genetic variance of polygenic characters (Fisher 1918; Wright 1921) presume that there is no natural selection or mutation. In a large population, the genetic variance determined by additive genes may then increase by up to a factor of two with local inbreeding, and even more with assortative mating. The classical models are still used to interpret data from natural populations. But contrary to their assumptions, most metrical characters in natural populations are usually thought to be under a type of selection which depletes polygenic variation. Mutation is then necessary to maintain genetic variation. The present models show that with the additional features of mutation and selection, in a large population, the mating system has no influence on the amount of genetic variability maintained by additive genes.     

Role of M2 muscarinic receptors in airway smooth muscle contraction

Airway smooth muscle expresses both M2 and M3 muscarinic receptors with the majority of the receptors of the M2 subtype. Activation of M3 receptors, which couple to Gq, initiates contraction of airway smooth muscle while activation of M2 receptors, which couple to Gi, inhibits beta-adrenergic mediated relaxation. Increased sensitivity to intracellular Ca2+ is an important mechanism for agonist-induced contraction of airway smooth muscle but the signal transduction pathways involved are uncertain. We studied Ca2+ sensitization by acetylcholine (ACh) and endothelin-1 (ET-1) in porcine tracheal smooth muscle by measuring contractions at constant [Ca2+] in strips permeabilized with Staphylococcal alpha-toxin. Both ACh and ET-1 contracted airway smooth muscle at constant [Ca2+]. Pretreatment with pertussis toxin for 18-20 hours reduced ACh contractions, but had no effect on those of ET-1 or GTPgammaS. We conclude that the M2 muscarinic receptor contributes to airway smooth muscle contraction at constant [Ca2+] via the heterotrimeric G-protein Gi.