Distribution and properties of glutathione S-transferase from T. infestans

Defense systems in developing Artemia franciscana nauplii and their modulation by probiotic bacteria offer protection against a Vibrio anguillarum challenge

The alterations of immune responses of Artemia franciscana nauplii as a function of culture time and after a challenge with the pathogen Vibrio anguillarum were studied. The effect of the administration of the probiotic bacteria Bacillus subtilis, Lactobacillus plantarum and Lactococcus lactis either alone or in combination with the pathogen was evaluated. The activity of the antioxidant enzymes superoxide dismutase (SOD), Glutathione reductase (GRed), Glutathione transferase (GST) and Phenoloxidase (PO) presented a significant increase as a function of culture time, appeared elevated following probiotic administration and were depleted 48 h following the experimental challenge. Lipid peroxidation reached peak levels at 48 h of culture, when nauplii start feeding and returned to lower values at 144 h, remaining however significantly higher than control (P < 0.05). The three probiotics significantly reduced lipid peroxidation in comparison with the corresponding control, while challenge with the pathogen resulted in its threefold increase. Survival of nauplii remained high throughout culture and was either increased or remained at control levels following the administration of the probiotics. The challenge with the pathogen resulted in a significantly decreased survival of 15.3% for the positive control, while in the probiotic treated series survival values were not significantly different from the negative control (P > 0.05). Following a combined administration of each probiotic and the pathogen the activities of all enzymes tested were significantly lower (P < 0.001) than the negative control (no treatment), but higher than the positive control (challenge, no probiotic). Lipid peroxidation was significantly lower in the probiotic treated series in comparison to the positive control (P < 0.001). The results of the present study provide evidence that major alterations take place as a function of culture time of Artemia nauplii. In addition the pathogen induces an oxidative stress response. The probiotics B. subtilis, L. plantarum and L. lactis protect Artemia against a V. anguillarum challenge by enhancing its immune responses thus contributing to reduced oxidative damage and increased survival.

Toxicological and biochemical analysis of the susceptibility of sylvatic Triatoma infestans from the Andean Valley of Bolivia to organophosphate insecticide

To increase our knowledge of the natural susceptibility of Triatoma infestans to an organophosphate insecticide, we performed toxicological and biochemical studies on three sylvatic populations from Bolivia and two populations from domestic dwellings from Bolivia and Argentina. Fifty-per-cent lethal doses (LD50) were determined based on the topical application of fenitrothion on first instar nymphs and mortality was assessed at 24 h. Both type of populations exhibited LD50ratios significantly higher than 1 with a range of the values (1.42-2.47); the maximum value were found in a sylvatic (-S) population, Veinte de Octubre-S. Samples were biochemically analysed using a glutathione S-transferase activity assay. The highest significant activity was obtained for Veinte de Octubre-S and the lowest activity was obtained for the reference population (102.69 and 54.23 pmol per minute per mg of protein respectively). Two out of the three sylvatic populations (Veinte de Octubre-S and Kirus Mayu-S) exhibited significantly higher glutathione S-transferase activity than that of the reference population. Based on this analysis of the natural susceptibility of this organism to organophosphate insecticides, continental and focal surveys of organophosphate susceptibility should be conducted to evaluate the evolution and distribution of this phenomenon.

Two glutathione S-transferase isoenzymes purified from Bulinus truncatus (Gastropoda: Planorbidae)

We purified and characterized two major glutathione S-transferase isoenzymes (GST2 and GST3) from snail Bulinus truncatus (Mollusca, Gastropoda, Planorbidae) tissue. The Km with respect to 1-chloro-2, 4-dinitrobenzene (CDNB) for both isoenzymes was increased as the pH decreased. Km of both isoenzymes with respect to glutathione (GSH) doubled when the pH was increased from 6.0 to 6.5. Acid inactivated GST2 and GST3 and the two enzymes were almost inactive at pH 3.5. However, they retain the full activity for at least 20 h when incubated at pH between 6.0 and 9.0. The optimum temperature was 45 degrees C for GST2 and 50 degrees C for GST3. The half lifetime at 50 degrees C was 70 min and 45 min for GST2 and GST3 isoenzymes, respectively. Addition of 5 mM GSH to the incubation buffer increased the half life of both isoenzymes more than fourfold. The activation energy for catalyzing the conjugation of CDNB was 1.826 and 3.435 kcal/mol for GST2 and GST3, respectively. I50 values for Cibacron blue, bromosulphophthalein, indocyanine green, hematin and ethacrynic acid were 0.76 microM, 47.9 microM, 7.59 microM, 0.03 microM and 0.79 microM for GST2, and 0.479 microM, 79.4 microM, 89.1 microM, 32.4 microM and 1.15 microM for GST3, respectively. Cibacron blue and indocyanine green were non-competitive inhibitors, while hematin was a mixed inhibitor. Bromosulphophthalein was found to be a competitive inhibitor for GST2 and a mixed inhibitor for GST3.

Glutathione S-transferase in the developmental stages of the insect Apis mellifera macedonica

We investigated the pattern of glutathione S-transferase (GST) activity in the course of the development of Apis mellifera macedonica. GST activity is present in all developmental stages of A. mellifera macedonica. The highest activity towards the substrate 1-chloro-2,4-dinitrobenzene (CDNB) is found in the adult stage and the lowest in the egg. The kinetic characteristics of the whole enzyme change as the insect develops. Significant changes are observed in substrate specificity, inhibitor sensitivity and V(max). The number of isoenzymes and their rate of expression vary as the insect develops. However, two main isoenzymes are present in all developmental stages, one in the alkaline area and the other in the acidic. While in the larval stage the acidic isoenzyme is expressed at a slightly higher rate (52.2% over 47.8% for the alkaline isoenzyme), in the adult stage, the rate is reversed dramatically (13.24% and 84.2%, respectively).

Allelochemical effects of eudesmane and eremophilane sesquiterpenes on Tribolium castaneum larvae

Eight eudesmane and eremophilane sesquiterpenes administered to Tribolium castaneum larvae caused different allelochemical effects. Topical application of 3-oxo-gamma-costic acid produced the greatest lengthening in the duration of the pupal stage. Morphological deformities were found, specifically when ilicic, costic, and gamma-costic acids and costic aldehyde were used. Ilicic acid exhibited the major toxicity 72 hr following topical application. All compounds were significantly toxic at the end point of the experiment (60 days). Treated surface toxicity was lower than when topical assays were carried out. Responses to tessaric acid in choice bioassays had the highest attractive effect. Maximum repellency was caused by the 3-oxo-gamma-costic acid. However, experimental series carried out using gamma-costic acid, eremophilan-1(10),2,11(13)-trien-12-oic acid, costic aldehyde, and ilicic aldehyde showed no clear response.

Degradation of malathion and phenthoate by glutathione reductase in wheat germ

Residual malathion in wheat was estimated at a lower value when analysis was performed by extraction with acetone after addition of water to swell the wheat, according to the Japanese Bulletin Method. The supernatant of the wheat homogenate showed degradation not only of malathion but also of phenthoate. Malathion and phenthoate were not degraded by the boiled supernatant of the wheat homogenate. It was presumed for this reason that glutathione reductase (GR; EC 1.6. 4.2) in the wheat degraded malathion. The following results were obtained: (1) GR originating in wheat could degrade malathion and phenthoate. (2) The degradation of malathion by the GR was inhibited by excessive GSSG. (3) There was a high correlation between GR activity and malathion degradation activity of the supernatant of wheat homogenates. It is likely that GR acted on the specific structure of malathion and phenthoate, the S=P-S bond, and the blanch structure bonding with the sulfur atom. Following the above, extraction with acetone after addition of water (the Japanese Bulletin Method) should be replaced by extraction with pure organic solvent and without addition of water for swelling.

The construction of a cDNA expression library for the sheep scab mite Psoroptes ovis

The need for alternative control strategies for sheep scab is critical. One approach is to develop vaccines based on 'concealed' antigens derived from Psoroptes ovis. This strategy requires the identification and characterisation of potential target antigens, which has been hampered by the problem of limited biological material for isolation of protein antigens. To aid the discovery of P. ovis antigens and to provide a resource for generating recombinant protein, we constructed a P. ovis cDNA expression library, using total RNA isolated from 250 mg of mixed-stage P. ovis and the Clontech SMART cDNA synthesis kit. The presence of P. ovis-specific sequences was confirmed using PCR amplification and sequencing of actin. The sequences of cDNA inserts from six random clones included one with high homology to the Dermatophagoides pteronyssinus (house dust mite) antigen p Dp15. This is a glutathione S-transferase known to be an important house dust mite antigen. We conclude that this library will be a useful tool for the identification of potential target antigens for the immunological control of P. ovis and to further our understanding of the pathology of sheep scab.

Induction of IgE antibody responses by glutathione S-transferase from the German cockroach (Blattella germanica)

We report that a major 23-kDa allergen from German cockroach (Blattella germanica) is a glutathione S-transferase (EC 2.5.1.18; GST). Natural B. germanica GST, purified from cockroach body extracts by glutathione affinity chromatography, and recombinant protein expressed in Escherichia coli using the pET21a vector, showed excellent IgE antibody binding activity. B. germanica GST caused positive immediate skin tests in cockroach-allergic patients using as little as 3 pg of recombinant protein. The NH2-terminal sequence of the natural protein and the deduced amino acid sequence from cDNA were identical except for one substitution (Phe9 --> Cys). Assignment of this protein to the GST superfamily was based on binding to glutathione and sequence identity (42-51%) to the GST-2 subfamily from insects, including Anopheles gambiae and Drosophila melanogaster. B. germanica GST contained 18 of the 26 invariable residues identified in mammalian GST by x-ray crystallography and exhibited enzymic activity against a GST substrate. Our results show that cockroach GST causes IgE antibody responses and is associated with asthma. The data strongly support the view that the immune response to GST plays an important role in allergic diseases.

Effect of GSH depletion mediated by l-BSO on the insecticidal activity of DDT and fenitrothion in Triatoma infestans (Hemiptera)

l-BSO injected at a sublethal dose in nymph V of Triatoma infestans produces a transient GSH depletion in the abdomen. A depletion of the total content of GSH was observed in nymph II fed with a sublethal concentration of l-BSO. Either ingestion or injection pretreatments of T. infestans nymph V with sublethal concentrations of l-BSO produced a slight synergism on the toxicity of fenitrothion. Feeding administration of a sublethal concentration of l-BSO to nymphs II of T. infestans resulted in a weak potentiation of the acute toxicity of DDT.