Effects of elimination of Wolbachia on oogenesis of the uzifly Exorista sorbillans,a parasitoid of the silkworm Bombyx mori

Maternally inherited bacteria of the genus Wolbachia are known to affect the physiology and reproduction of several arthropod and nematode hosts. This paper presents the effects of using tetracycline to eliminate Wolbachia on the oogenesis of its host uzifly Exorista sorbillans (Diptera: Tachinidae), a parasitoid of silkworm Bombyx mori L. Earlier we reported cytoplasmic incompatibility, nucleo‐cytoplasmic conflict, male biased sex ratio and reduction in fecundity upon curing of Wolbachia infection using an antibiotic. This paper presents the abnormal growth and proliferation of oocytes in the uninfected/cured uziflies. The anomalies include abnormal/arrested oocyte production with inhibition of normal functioning of nurse cell nuclei, malformation and agglutination in egg chambers, empty egg chambers due to arrested vitellogenesis and undeveloped ovarian tubules. These anomalies further lead to reduction in growth of the ovarian tubules, which resulted in a 20% reduction of fecundity. It is hypothesized that normal oocyte production in uzifly requires the infection of Wolbachia bacteria. Further, in the uzifly, infection is at transition stage from a facultative to an obligatory mode of symbiosis. In light of this, this paper discusses the relationship between Wolbachia and oocyte production.     

Studies on the stability of 125I-purified porcine zona antigen (PPZA) obtained by chloramine-T glucose oxidase with lactoperoxidase and N-bromosuccinimide lodination procedures

A purified pig zona antigen (PPZA) was labeled with ¹²⁵I by chloramine-T (CL-T), glucose oxidase with lactoperoxidase (GO-LP), and N-bromosuccinimide (N-BS) iodination procedures. The ¹²⁵I-PPZA fractions thus obtained were reconstituted to a concentration of 25,000 dpm/0.1 ml and tested at weekly intervals for binding capacity to a fixed dilution (1:400,000) of PPZA antibody. The ¹²⁵I-PPZA obtained by the N-BS procedure showed greater stability compared to that obtained by CL-T and GO-LP methods. The nonspecific binding levels for the N-BS and GO-LP methods were comparable and significantly lower than for the CL-T method.     

Protease-mediated prophenoloxidase activation in the haemolymph of American cockroach Periplaneta americana

Prophenoloxidase has been successfully obtained from the haemolymph of the cockroach Periplaneta americana using cane sugar saline solution. The proenzyme was activated by various exogenously added proteases such as chymotrypsin, trypsin, subtilisin and thermolysin. Thermolysin was found to be the greatest activator, followed by chymotrypsin and subtilisin. Chymotrypsin activation showed a lag period when compared with the other proteases tested, indicating that activation by chymotrypsin followed an indirect path, whereas, subtilisin and thermolysin activated the proenzyme directly.Exogenously added protease inhibitor showed inhibition towards protease-mediated prophenoloxidase activation. Benzamidine inhibited chymotrypsin and trypsin activation, whereas soybean trypsin inhibitor inhibited trypsin. In situ inhibitor isolated from the haemocytes of Periplaneta americana inhibited the prophenoloxidase activation and showed evidence for the presence of a built-in inhibition system for the release of the components of the prophenoloxidase activating system of P. americana. Electrophoretic localization of activated phenoloxidase showed two bands, suggesting the dimeric condition of high mol. wt prophenoloxidase.     

Latent larval cuticular phenoloxidase in the coconut pest,Oryctes rhinoceros

Cuticular phenoloxidase (Tyrosinase) in the larval stage of the coconut pest Oryctes rhinoceros has been extracted in the stable proform using cane sugar saline/borate buffer. The extracted prophenol oxidase can be activated by the addition of proteolytic enzymes such as trypsin, chymotrypsin, thermolysin, and subtilisin. Detergents such as SDS and Tween-80 also activated the enzyme. Electrophoretical analysis revealed dissociation of the enzyme into two molecular forms after its activation by proteolytic enzymes. The functional significance of the enzyme is suggested to involve the generation of quinone compounds in the wound healing process: most phenoloxidase inhibitors prevented melanization when applied topically to surgical wounds. © 1996 Wiley-Liss, Inc.     

QTL and QTL x environment effects on agronomic and nitrogen acquisition traits in rice

Agricultural environments deteriorate due to excess nitrogen application.Breeding for low nitrogen responsive genotypes can reduce soil nitrogen input.Rice genotypes respond variably to soil available nitrogen.The present study attempted quantification of genotype x nitrogen level interaction and mapping of quantitative trait loci (QTLs) associated with nitrogen use efficiency (NUE) and other associated agronomic traits.Twelve parameters were observed across a set of 82 double haploid (DH) lines derived from IR64/Azucena.Three nitrogen regimes namely,native (0 kg/ha; no nitrogen applied),optimum (100 kg/ha) and high (200 kg/ha) replicated thrice were the environments.The parents and DH lines were significantly varying for all traits under different nitrogen regimes.All traits except plant height recorded significant genotype x environment interaction.Individual plant yield was positively correlated with nitrogen use efficiency and nitrogen uptake.Sixteen QTLs were detected by composite interval mapping.Eleven QTLs showed significant QTL x environment interactions.On chromosome 3,seven QTLs were detected associated with nitrogen use,plant yield and associated traits.A QTL region between markers RZ678,RZ574 and RZ284 was associated with nitrogen use and yield.This chromosomal region was enriched with expressed gene sequences of known key nitrogen assimilation genes.     

Effect of cadmium and zinc on antioxidant enzyme activity in the gastropod, Achatina fulica

Heavy metal stress results in the production of O(2)(.-), H(2)O(2) and (.)OH, which affect various cellular processes, mostly the functioning of membrane systems. Cells are normally protected against free oxyradicals by the operation of intricate antioxidant systems. The aim of the present work is to examine the effect of CdCl(2) and ZnSO(4) on antioxidative enzyme activity in the gastropod, Achatina fulica. The concentrations of antioxidant enzymes--superoxide dismutase (SOD), catalase (Cat) and glutathione peroxidase (GPx)--and nonenzymatic antioxidants--glutathione and vitamin-C--were found to be decreased in both digestive gland and kidney of the gastropod, Achatina fulica treated with individual concentrations of 0.5 ppm and 1ppm of CdCl(2) and ZnSO(4), compared to that of control animals. Based on the above study, it is evident that Achatina fulica can be used as a bioindicator to monitor the environmental heavy metal pollution.     

Soluble cuticular phenoloxidase in the gypsy moth Lymantria dispar

The soluble enzyme phenoloxidase (tyrosinase) from the larval cuticle of Lymantria dispar has been partially purified using Ultrogel ACA 34, and the activity has been determined using phenolic substrates. The enzyme exhibited more activity toward O-diphenolic substrates and monophenolic substrates. The enzyme is inhibited by diethyl dithiocarbamate, phenylthiourea, and thiourea. The enzyme has been localized in the 7% slab and disc PAGE as an intense band. The enzyme is suggested to be involved in wound healing. © 1992 Wiley-Liss, Inc.