Cloning and functional identification of moricins from the diamondback moth, Plutella xylostella (L.).

Antimicrobial peptides (AMPs) are small-molecule peptides that play crucial roles in insect innate immune responses. To better understand the function of AMPs in Plutella xylostella, one of the main pests of cruciferous vegetables, three full-length cDNAs encoding moricins were cloned from Pl. xylostella. Two variants of the moricin named PxMor2 and PxMor3 were heterologously expressed and purified. A secondary structure analysis using circular dichroism demonstrated that the two peptides adopted an α-helical structure in the membrane-like environment, but in aqueous solution, they were present in random coiled conformation. Antimicrobial activity assays demonstrated that PxMor2 exhibited high activity against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli; however, PxMor3 only demonstrated high activity against E. coli. Scanning electron microscopy and confocal laser-scanning microscopy analyses suggest that PxMors can lead to the disruption of bacterial membrane, which might be the mechanism by which PxMors inhibit bacterial growth. This study contributes to the understanding of Pl. xylostella AMPs and immune responses, and also enriches the knowledge of insect moricin.

Purification of the insecticidal Cry2Ad protein from a Bt-isolated BRC-HZP10 strain and toxin assay to the diamondback moth, Plutella xylostella (L.).

The present study aims to characterize the Cry2Ad toxin protein isolated from a Bacillus thuringiensis strain, BRC-HZP10, which have a potential insecticidal activity against larvae of the diamondback moth, Plutella xylostella (L.). The crude Bt toxin proteins were isolated and purified by cation exchange chromatography, then equilibrated with 0.2 M NaOH buffer, pH 4.0, followed by ultraviolet detection at 280 nm and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A refined Cry2Ad toxin protein with 88.34% purity was eventually obtained and used for a bioassay by feeding it to P. xylostella. The results showed conspicuous insecticidal activity towards P. xylostella with 50% lethal concentration of 6.84 µg/mL and 95% confidence interval of 5.77-7.91 mg/mL. At a concentration of 16.38 µg/mL, the intake of Cry2Ad protein significantly shortened the oviposition period and larval developmental duration, but significantly reduced the fecundity and egg hatchability of the population compared to those of control (without treatment with Cry2Ad protein) (P < 0.05). These results indicate that the Cry2Ad protein plays an effective role in controlling the population of P. xylostella.

PsOr1, a potential target for RNA interference-based pest management.

Insect pests cause billions of dollars in agricultural losses, and attempts to kill them have resulted in growing threats from insecticide resistance, dietary pesticide pollution and environmental destruction. New approaches to control refractory insect pests are therefore needed. The host-plant preferences of insect pests rely on olfaction and are mediated via a seven transmembrane-domain odorant receptor (Or) family. The present study reports the cloning and characterization of PsOr1, the first candidate member of the Or gene family from Phyllotreta striolata, a devastating beetle pest that causes damage worldwide. PsOr1 is remarkably well conserved with respect to other insect orthologues, including DmOr83b from Drosophila melanogaster. These insect orthologues form an essential non-conventional Or sub-family and may play an important and generalized role in insect olfaction. We designed double-stranded (ds) RNA directly against the PsOr1 gene and exploited RNA interference (RNAi) to control P. striolata. The chemotactic behavioural measurements showed that adult beetles were unable to sense the attractant or repellent odour stimulus after microinjection of dsRNA against PsOr1. Reverse Transcription (RT)-PCR analysis showed specific down-regulation of mRNA transcript levels for this gene. Furthermore, host-plant preference experiments confirmed that silencing PsOr1 by RNAi treatment impaired the host-plant preferences of P. striolata for cruciferous vegetables. These results demonstrate that this insect control approach of using RNAi to target PsOr1 and its orthologues might be effective in blocking host-plant-seeking behaviours in diverse insect pests. The results also support the theory that this unique receptor type plays an essential general role in insect olfaction.

Endotoxemia in organ donors: graft function following liver transplantation.

Translocation of endotoxin (LPS) to the portal-venous system is produced by multiple factors. In the case of normal liver function, LPS is rapidly cleared from the portal blood by Kupffer cells; in impaired liver function, LPS can reach the systemic circulation. The objective of this study was to investigate whether elevated donor endotoxin levels affect graft function in the recipient. LPS levels in donor plasma were measured in 14 consecutive liver transplantations. Grafts with donor LPS levels < or = 12 pg/ml had a function probability of 100% after 600 days (n = 10). LPS concentrations of > 12 pg/ml in donor plasma led to loss of function in 75% of the liver grafts (n = 4; P = 0.003; Wilcoxon). Elevated LPS values in donor plasma seem to impair the prognosis of the grafts and could predict poor graft function as early as at the time of brain death.

Curvilinear relations between age and hemostatic parameters in Chinese.

The role of hemostatic factors in the pathogenesis of cardiovascular disease has gained much attention recently. Information about hemostatic factors, and their age patterns is sparse for orientals. With the data collected in the Cardiovascular Disease Risk Factor Two-township Study in Taiwan, this study shows that, in general, the older the age, the stronger the tendency toward thrombosis. With advancing age, prothrombin time, activated partial thromboplastin time, and antithrombin-III level decreased steadily; but mean values of fibrinogen, factor VIIc, and factor VIIIc increased. Gender differences in the age patterns of the above factors are carefully described. Curvilinear relations between hemostatic factors and age were demonstrated for adults aged 18 and above for all hemostatic factors studied. This curvilinearity should be taken into consideration when adjusting for the effect of age in data analysis to avoid residual confounding, particularly when the age range of the study subjects is wide.

New test system for identification of Aerococcus, Enterococcus, and Streptococcus species.

A total of 244 strains of Aerococcus, Enterococcus, and Streptococcus species were tested by the RapID STR system (Innovative Diagnostic Systems Inc., Atlanta, Ga.) for identification. Strains were identified without additional tests or with additional conventional tests suggested by the IDS compendium manual. Our data indicate that the RapID STR system identifies 89% of the beta-hemolytic Streptococcus species if serological procedures are used in conjunction with the rapid physiological procedures. Of the group D streptococci, 98% of the Enterococcus species and 100% of the group D non-Enterococcus species were correctly identified. Of the commonly occurring viridans group Streptococcus species, 93% were correctly identified, and 79% of the less frequently occurring viridans group Streptococcus species were correctly identified. All of the Streptococcus pneumoniae and Aerococcus strains tested were correctly identified.