The titres of lectins in the haemolymph of Lacanobia oleracea and the effects of parasitism by the ectoparasitoid wasp Eulophus pennicornis

Serum from larvae of Lacanobia oleracea L. (Lepidoptera; Noctuidae) parasitized by Eulophus pennicornis (Hymenoptera; Eulophidae) and from normal non‐parasitized larvae is capable of agglutinating rabbit, sheep, calf, goat, chicken, horse and human erythrocytes, but not yeast. Studies with a range of inhibitory carbohydrates showed that serum lectins(s) had specificity for sugars containing galactose and for rhamnose, and for the glycosubstances fetuin and asialofetuin. Lectin activity is heat‐labile and is not dependent on calcium. Parasitism by E. pennicornis caused an increase in the agglutination titre of the serum from larvae of L. oleracea but not an increase in specific activity (titre per mg protein per ml). However, when venom from the venom gland of female wasps was injected into L. oleracea larvae, both the agglutinating activity and the specific activity of the larval serum increased. The possible causes of this increase are discussed. It is suggested that venom contains antigenic components which, when injected into the haemocoel of the L. oleracea larva, may be increasing lectin synthesis and/or release into the serum.     

Enzymatic activities and functional characterization of a novel recombinant snake venom proteinase from Agkistrodon Acutus

Snake venom from Agkistrodon acutus consists of a number of compounds which may potentially be used as drugs. However, it is hard to obtain enough pure protein for drug development. Recently, we reported expression and purification of a novel recombinant fibrinogenase which was named rFII. Here we reported for the first time the enzymatic activities and functional characterization of rFII. Circular dichroism spectra showed the gross conformation of FIIa and rFII to be notably similar. It is an alkaline proteinase and the amino acid sequence exhibits a high degree of sequence identity with other snake venom metalloproteinases. rFII also exhibits amidase activity against N-(p-Tosyl)-Gly-Pro-Lys-p-nitroanilide, which is specified synthetic substrate for plasmin. Functional characterization showed that rFII possesses both fibronectin and type IV collagen cleaving activities. In addition, rFII preferentially cleaved the Aalpha-chain of fibrinogen, followed by the Bbeta-chain and finally, the gamma(γ) chain was affected. Furthermore, rFII was also capable of cleaving fibrin without plasminogen activation and suppressing ADP-induced platelet aggregation. The proteolytic activity of rFII was inhibited completely by PMSF and mostly by EDTA. The cations Ca²⁺, Mg²⁺, Na⁺, K⁺ didn't affect its proteolytic activity, while Cu²⁺ and Zn²⁺ slightly inhibited this activity. Study of hydrolysis of oxidized insulin B-chain reveals that rFII preferentially cleaved oxidized insulin B-chain at the site of Val¹²-Glu¹³, Leu¹⁵-Tyr¹⁶, and Phe²⁴-Phe²⁵.     

Pr-SNTX,a short-chain three-finger toxin from Papuan pigmy mulga snake,is an antagonist of muscle-type nicotinic acetylcholine receptor (α2βδε)

Three-finger toxins (3FTxs) are one of the major components in snake venoms. In this study, we isolated a cDNA encoding a short-chain 3FTx, Pr-SNTX, from Pseudechis rossignolii. The amino acid sequence of Pr-SNTX is nearly identical to that of its ortholog in Pseudechis australis. Pr-SNTX protein inhibited muscle-type (α₂βδε), but not neuronal α7 nicotinic acetylcholine receptor (nAChR) activity.     

Hyperalgesic and edematogenic effects of Secapin-2, a peptide isolated from Africanized honeybee (Apis mellifera) venom

Honeybee stings are a severe public health problem. Bee venom contains a series of active components, including enzymes, peptides, and biogenic amines. The local reactions observed after envenoming include a typical inflammatory response and pain. Honeybee venom contains some well-known polycationic peptides, such as Melittin, Apamin, MCD peptide, Cardiopep, and Tertiapin. Secapin in honeybee venom was described 38 years ago, yet almost nothing is known about its action. A novel, variant form of this peptide was isolated from the venom of Africanized honeybees (Apis mellifera). This novel peptide, named Secapin-2, is 25 amino acid residues long. Conformational analyses using circular dichroism and molecular dynamics simulations revealed a secondary structure rich in strands and turns, stabilized by an intramolecular disulfide bridge. Biological assays indicated that Secapin-2 did not induce hemolysis, mast cell degranulation or chemotactic activities. However, Secapin-2 caused potent dose-related hyperalgesic and edematogenic responses in experimental animals. To evaluate the roles of prostanoids and lipid mediators in the hyperalgesia and edema induced by this peptide, Indomethacin and Zileuton were used to inhibit the cyclooxygenase and lipoxygenase pathways, respectively. The results showed that Zileuton partially blocked the hyperalgesia induced by Secapin-2 and decreased the edematogenic response. In contrast, Indomethacin did not interfere with these phenomena. Zafirlukast, a leukotriene receptor antagonist, blocked the Secapin-2 induced hyperalgesia and edematogenic response. These results indicate that Secapin-2 induces inflammation and pain through the lipoxygenase pathway in both phenomena.     

Chelonus sp. near curvimaculatus venom proteins: Analysis of their potential role and processing during development of host Trichoplusia ni

The venom that Chelonus sp. near curvimaculatus injects into each parasitized Trichoplusia ni egg is entirely injected within the first 8 s of the 19-s oviposition period, before deposition of the parasitoid egg that is injected during the final 1-2 s of the oviposition. The parasitization factor, causing precocious metamorphosis of the host, is injected after the venom, but before the parasite egg. The venom by itself does not cause developmental redirection of the host. Chelonus venom proteins are very stable in the host egg during the first 2 days of egg development. Then, on the last day before hatching, they are rapidly degraded by the proteolytic enzymes appearing in 3-day-old T. ni eggs. Among those that degrade the venom proteins are serine-type proteinases, and at least one seems to be a trypsin-like enzyme.     

大胡蜂蜂毒中多肽和蛋白质结构和功能的多样性

为证明大胡蜂Vespa magnifica(Smith)蜂毒具有较大的药用开发价值,本研究采用超高效液相色谱-质谱和电泳技术对其多肽和蛋白质的分布进行分析,发现其蛋白质的相对分子质量主要分布在17~45kDa范围内。蜂毒多肽类物质的相对分子质量呈"单峰"式分布,61%在500~3000Da范围内,为大胡蜂蜂毒中多肽含量最为丰富的部分。通过牛津杯法对蜂毒的抑菌活性进行研究,且以HepG2人肝癌细胞及B16黑色素瘤细胞为研究对象,用MTT法检测蜂毒的细胞毒性活性,证明其具有良好的抑菌作用和细胞毒活性,其结果与已报道的其他蜂类既有相似性又存在具体差异,展示了大胡蜂蜂毒的分子多样性,为后续该毒素的物质基础研究及药用价值开发提供参考。     

Statistical analysis of the individual variability of 1D protein profiles as a tool in ecology: an application to parasitoid venom

Understanding the forces that shape eco‐evolutionary patterns often requires linking phenotypes to genotypes, allowing characterization of these patterns at the molecular level. DNA‐based markers are less informative in this aim compared to markers associated with gene expression and, more specifically, with protein quantities. The characterization of eco‐evolutionary patterns also usually requires the analysis of large sample sizes to accurately estimate interindividual variability. However, the methods used to characterize and compare protein samples are generally expensive and time‐consuming, which constrains the size of the produced data sets to few individuals. We present here a method that estimates the interindividual variability of protein quantities based on a global, semi‐automatic analysis of 1D electrophoretic profiles, opening the way to rapid analysis and comparison of hundreds of individuals. The main original features of the method are the in silico normalization of sample protein quantities using pictures of electrophoresis gels at different staining levels, as well as a new method of analysis of electrophoretic profiles based on a median profile. We demonstrate that this method can accurately discriminate between species and between geographically distant or close populations, based on interindividual variation in venom protein profiles from three endoparasitoid wasps of two different genera (Psyttalia concolor, Psyttalia lounsburyi and Leptopilina boulardi). Finally, we discuss the experimental designs that would benefit from the use of this method.     

Effects of persimmon tannin on survival and reproduction of Halyomorpha halys (Hemiptera: Pentatomidae)

Halyomorpha halys (Hemiptera: Pentatomidae) occurs in sweet persimmon orchards from late July to early September and its damage level is negligible before mid‐July. It rarely appears in persimmon orchards after mid‐September, but is easily found in soybean fields. From the phenological observation of H. halys, it is assumed that seasonal migration of H. halys to sweet persimmon orchards may be related to the content of soluble tannin in sweet persimmon fruits. The feeding preference of H. halys was evaluated on sweet and astringent persimmon fruits, and the effects of persimmon fruits and purified persimmon tannin were tested on the survival of H. halys. Numbers of visiting bugs and feeding spots on the fruits were significantly higher on sweet persimmon than those on astringent persimmon. There was no significant difference in survivorships of H. halys fed sweet persimmon and soybean. However, the number of eggs laid by sweet persimmon fed adult females was significantly lower than those fed soybean. The higher concentration of persimmon tannin caused higher mortality of H. halys. Male and female H. halys fed with 3% persimmon tannin showed the lowest survival. Longevities of male H. halys fed with 0, 0.01, 0.1 and 1% persimmon tannin were 14.9, 12.7, 14.5 and 16.3 days, respectively. However, males fed with 3% tannin lived only 6.4 days. The longevities of female H. halys were similar to those of male (10.1, 14.4, 13.8, 12.0 and 6.1 days for 0, 0.01, 0.1, 1 and 3% tannin concentration, respectively). These results suggest that H. halys invades sweet persimmon orchards during late July and early September when more suitable foods, e.g. soybean, are in short supply and sweet persimmon fruits become suitable for feeding (e.g. lower tannin content).