The importance of an invasive tree fruit as a resource for mosquito larvae

Invasive plants are common and may provide resources through litter for container mosquito larvae. Invasive plant reproductive parts can make up a substantial part of litter but have mostly been ignored as a resource for mosquito larvae. We hypothesized that the reproductive fruits of the invasive eastern red cedar, Juniperus virginiana, provide high quality resources for the invasive, container mosquito Aedes albopictus at the western margin of its invasive range in North America. To test this hypothesis, we performed two laboratory experiments. The first examined the response of individual larvae of Ae. albopictus to different amounts of J. virginiana leaf (fresh and senesced) and J. virginiana fruit (ripe and unripe), as well as to a control leaf (Quercus virginiana, live oak). The second experiment examined the response of different densities of Ae. albopictus larvae to each litter type. We found significant differences in response by individual larvae to different amounts of litter and litter types. We also found J. virginiana litter components could support positive population growth rates as a function of initial larval density where the control leaf could not. We conclude that invasive plants may provide high quality resources, and that the reproductive parts (fruits, flowers, cones) may be an important and overlooked component in provisioning larval habitats. Therefore, the expansion of J. virginiana into grassland areas may contribute to the expansion of Ae. albopictus westward in North America.     

Host S-nitrosylation inhibits clostridial small molecule-activated glucosylating toxins

The global prevalence of severe Clostridium difficile infection highlights the profound clinical significance of clostridial glucosylating toxins. Virulence is dependent on the autoactivation of a toxin cysteine protease, which is promoted by the allosteric cofactor inositol hexakisphosphate (InsP(6)). Host mechanisms that protect against such exotoxins are poorly understood. It is increasingly appreciated that the pleiotropic functions attributed to nitric oxide (NO), including host immunity, are in large part mediated by S-nitrosylation of proteins. Here we show that C. difficile toxins are S-nitrosylated by the infected host and that S-nitrosylation attenuates virulence by inhibiting toxin self-cleavage and cell entry. Notably, InsP(6)- and inositol pyrophosphate (InsP(7))-induced conformational changes in the toxin enabled host S-nitrosothiols to transnitrosylate the toxin catalytic cysteine, which forms part of a structurally conserved nitrosylation motif. Moreover, treatment with exogenous InsP(6) enhanced the therapeutic actions of oral S-nitrosothiols in mouse models of C. difficile infection. Allostery in bacterial proteins has thus been successfully exploited in the evolutionary development of nitrosothiol-based innate immunity and may provide an avenue to new therapeutic approaches.     

Dot1 and histone H3K79 methylation in natural telomeric and HM silencing

The expression of genes residing near telomeres is attenuated through telomere position-effect variegation (TPEV). By using a URA3 reporter located at TEL-VII-L of Saccharomyces cerevisiae, it was proposed that the disruptor of telomeric silencing-1 (Dot1) regulates TPEV by catalyzing H3K79 methylation. URA3 reporter assays also indicated that H3K79 methylation is required for HM silencing. Surprisingly, a genome-wide expression analysis of H3K79 methylation-defective mutants identified only a few telomeric genes, such as COS12 at TEL-VII-L, to be subject to H3K79 methylation-dependent natural silencing. Consistently, loss of Dot1 did not globally alter Sir2 or Sir3 occupancy in subtelomeric regions, but only led to some telomere-specific changes. Furthermore, H3K79 methylation by Dot1 did not play a role in the maintenance of natural HML silencing. Therefore, commonly used URA3 reporter assays may not report on natural PEV, and therefore, studies concerning the epigenetic mechanism of silencing in yeast should also employ assays reporting on natural gene expression patterns.     

Studies on the antileishmanial properties of the antimicrobial peptides temporin A,B and 1Sa

Given the paucity and toxicity of available drugs for leishmaniasis, coupled with the advent of drug resistance, the discovery of new therapies for this neglected tropical disease is recognised as being of the utmost urgency. As such antimicrobial peptides (AMPs) have been proposed as promising compounds against the causative Leishmania species, insect vector‐borne protozoan parasites. Here the AMP temporins A, B and 1Sa have been synthesised and screened for activity against Leishmania mexicana insect stage promastigotes and mammalian stage amastigotes, a significant cause of human cutaneous disease. In contrast to previous studies with other species the activity of these AMPs against L. mexicana amastigotes was low. This suggests that amastigotes from different Leishmania species display varying susceptibility to peptides from the temporin family, perhaps indicating differences in their surface structure, the proposed target of these AMPs. In contrast, insect stage L. mexicana promastigotes were sensitive to two of the screened temporins which clearly demonstrates the importance of screening AMPs against both forms of the parasite. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.     

The diagnostic value of Western blot method in patients with cystic echinococcosis

Cystic echinococcosis (CE) is the larval cystic stage (called echinococcal cysts) of a small taeniid-type tapeworm (Echinococcus granulosus). Carnivores such as dogs are usually definitive hosts. Intermediate hosts are typically herbivores such as sheep and cattle. CE can be detected using various imaging techniques such as ultrasonography or radiology. Moreover the primary diagnosis has to be confirmed by serological tests since the clinical signs of the disease are non-specific. This study examined the antigenic band patterns useful for serologic diagnosis of hydatidosis. We also report on the post-operative evolution of patients treated for this disease and also determined the diagnostic performance of Western blot IgG kit. Twenty-five (16 females and 9 males) non-operated patients with hydatid cysts (NOP) and 33 (21 females and 12 males) operated patients with hydatid cysts (OP) were included as study group and 22 healthy individuals (14 females and 8 males) with no known chronic diseases were included as a control group. The ages of the patients and control group individuals were between 16-83 years. Patient and control groups were matched for age and sex. Cyst hydatid IgG antibodies were detected in the sera from all patient groups but no antibodies were found in the sera from the control group using ELISA IgG method. Twenty-three (92%) non-operated patients and 18 (54.5%) operated patients exhibited positive results when Western blot IgG kit was used. The P7 band pattern was detected in the sera from all operated and non-operated patients. Twenty-seven of these positive cases had p7 and (p7+p16/18), (p7+p24/26) or (p7+p16/18+p24/26). No antibodies against p7, p16/18 ve p24/26 band patterns were seen in sera from the control group A statistically significant difference was detected between operated and nonoperated patients for Western blot positivity.(p<0.01). p: 0.018- X2=5,604- OR: 0.176- 95% CI: 0.037- 0.841. The sensitivity, specificity, positive prediction and negative prediction values of Echinococcus granulosus Western blot kit for 25 cases with CE and 22 healthy controls were calculated as 92%, 100%, 100% and 91.7%, respectively. In conclusion, we suggest that monitoring p7 in all non-operated patients may be useful to determine the efficiacy of medical treatment and that monitoring p7 antibodies using serological and Western blot methods in operated patients may be useful for the screening of post-operative evolution in patients with hydatid cyst.     

SARS coronavirus 8b reduces viral replication by down-regulating E via an ubiquitin-independent proteasome pathway

The severe acute respiratory syndrome coronavirus (SARS-CoV) 8b protein, which is not expressed by other known coronaviruses, can down-regulate the envelope (E) protein via a proteasome-dependent pathway. Here, we showed that the down-regulation of E is not dependent on the lysine residues on 8b and the reduction of polyubiquitination of E mutants is not correlated with their down-regulation by 8b, suggesting an ubiquitin-independent proteasome pathway is involved. A time-course study revealed that 8b was expressed at late-stages of SARS-CoV infection. By using Vero E6 cells stably expressing green fluorescence protein-tagged 8b, ectopic expression of 8b was shown to significantly reduce the production of progeny virus and down-regulate E expression. Taken together, these results suggest that 8b negatively modulates virus replication by down-regulating E via an ubiquitin-independent proteasome pathway.     

Protease inhibitor from Moringa oleifera with potential for use as therapeutic drug and as seafood preservative

Protease inhibitors are well known to have several applications in medicine and biotechnology. Several plant sources are known to return potential protease inhibitors. In this study plants belonging to different families of Leguminosae, Malvaceae, Rutaceae, Graminae and Moringaceae were screened for the protease inhibitor. Among them Moringa oleifera, belonging to the family Moringaceae, recorded high level of protease inhibitor activity after ammonium sulfate fractionation. M. oleifera, which grows throughout most of the tropics and having several industrial and medicinal uses, was selected as a source of protease inhibitor since so far no reports were made on isolation of the protease inhibitor. Among the different parts of M. oleifera tested, the crude extract isolated from the mature leaves and seeds showed the highest level of inhibition against trypsin. Among the various extraction media evaluated, the crude extract prepared in phosphate buffer showed maximum recovery of the protease inhibitor. The protease inhibitor recorded high inhibitory activity toward the serine proteases thrombin, elastase, chymotrypsin and the cysteine proteases cathepsin B and papain which have more importance in pharmaceutical industry. The protease inhibitor also showed complete inhibition of activities of the commercially available proteases of Bacillus licheniformis and Aspergillus oryzae. However, inhibitory activities toward subtilisin, esperase, pronase E and proteinase K were negligible. Further, it was found that the protease inhibitor could prevent proteolysis in a commercially valuable shrimp Penaeus monodon during storage indicating the scope for its application as a seafood preservative. This is the first report on isolation of a protease inhibitor from M. oleifera.