Positive association between thrips and spider mites in seedling cotton

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Expression and characterization of chimeric spidroins from flagelliform-aciniform repetitive modules

Spiders can produce up to seven different types of silks or glues with different mechanical properties. Of these, flagelliform (Flag) silk is the most elastic, and aciniform (AcSp1) silk is the toughest. To produce a chimeric spider silk (spidroin) Flag_R-AcSp1_R, we fused one repetitive module of flagelliform silk from Araneus ventricosus and one repetitive module of aciniform silk from Argiope trifasciata. The recombinant protein expressed in E. coli formed silk-like fibers by manual-drawing. CD analysis showed that the secondary structure of Flag_R-AcSp1_R spidroin remained stable during the gradual reduction of pH from 7.0 to 5.5. The spectrum of FTIR indicated that the secondary structure of Flag_R-AcSp1_R changed from α-helix to β-sheet. The conformation change of Flag_R-AcSp1_R was similar to other spidroins in the fiber formation process. SEM analysis revealed that the mean diameter of the fibers was around 1 ~ 2 μm, and the surface was smooth and uniform. The chimeric fibers exhibited superior toughness (~33.1 MJ/m³) and tensile strength (~261.4 MPa). This study provides new insight into design of chimeric spider silks with high mechanical properties.     

Modelling and Bioinformatics Analysis of the Dimeric Structure of House Dust Mite Allergens from Families 5 and 21: Der f 5 Could Dimerize as Der p 5

Abstract

Allergy represents an increasing thread to public health in both developed and emerging countries and the dust mites Dermatophagoides pteronyssinus (Der p), Blomia tropicalis (Blo t), Dermatophagoides farinae (Der f), Lepidoglyphus destructor (Lep d) and Suidasia medanensis (Sui m) strongly contribute to this problem. Their allergens are classified in several families among which families 5 and 21 which are the subject of this work. Indeed, their biological function as well as the mechanism or epitopes by which they are contributing to the allergic response remain unknown and their tridimensional structures have not been resolved experimentally except for Blo t 5 and Der p 5. Blo t 5 is a monomeric three helical bundle, whereas Der p 5 shows a three helical bundle with a kinked N-terminal helix that assembles in an entangled dimeric structure with a large hydrophobic cavity. This cavity could be involved in the binding of hydrophobic ligands, which in turn could be responsible for the shift of the immune response from tolerance to allergic inflammation. We used molecular modelling approaches to bring out if other house dust mite allergens of families 5 and 21 (Der f 5, Sui m 5, Lep d 5, Der p 21 and Der f 21) could dimerize and form a large cavity in the same way as Der p 5. Monomeric models were first performed with MODELLER using the experimental structures of Der p 5 and Blo t 5 as templates. The ClusPro server processed the selected monomers in order to assess their capacity to form dimeric structures with a positive result for Der p 5 and Der f 5 only. The other allergens (Blo t 5, Sui m 5, Lep d 5, Der p 21 and Der f 21) did not present such a propensity. Moreover, we identified mutations that should destabilize and/or prevent the formation of the Der p 5 dimeric structure. The production of these mutated proteins could help us to understand the role of the dimerization process in the allergic response induced by Der p 5, and if Der p 5 and Der f 5 behave similarly.     

贵州梵净山自然保护区土壤甲螨群落的季节动态

2001年7月至2002年4月在不同的季节,对梵净山自然保护区属级水平上土壤甲螨结构的季节变化进行了调查.结果显示,土壤甲螨多度的四季变化为春季＞冬季＞秋季＞夏季.土壤甲螨多样性的四季变化为秋季＞夏季＞冬季＞春季.不同的季节土壤甲螨群落组成不同,但小奥甲螨属、小盾珠甲螨属、木单翼甲螨属3个属在每个季节均为绝对优势属.土壤甲螨主要分布在表层,但从夏季到冬季,土壤甲螨从表层向深层迁徙.     

Tunicamycin Inhibits Biosynthesis of Acid Mucopolysaccharides in Cultures of Chick Embryo Fibroblasts

Enterobacter cloacae KY 3074 grown in a medium containing xanthine, hypoxanthine, guanine, or their nucleosides and nucleotides produced xanthine oxidase. The purified enzyme preparation showed a major protein band and a few minor bands in acrylamide gel electrophoresis. Molecular oxygen was the most effective electron acceptor. Ferricyanide and 2,6-dichlorophenolindophenol also served as electron acceptors, but NAD and NADP did not. Xanthine and hypoxanthine were good substrates, and guanine was also an effective substrate. The activity was inhibited by Ag²⁺, Cu²⁺, PCMB, and ascorbate. The spectrum of the Enterobacter enzyme resembled that of some known xanthine oxidizing enzymes, and this suggests a similarity in the prosthetic groups of these enzymes. The molecular weight of the native enzyme and subunit was 128,000 and 69,000, respectively.     

Risky Courtship: Background Contrast,Ornamentation, and Display Behavior of Wolf Spiders Affect Visual Detection by Toad Predators

Males that search widely for females and perform conspicuous courtship displays run a high risk of being detected by their predators. Therefore, gains in reproductive success might be offset by increased mortality due to predation. Male brush‐legged wolf spiders (Schizocosa ocreata) with larger decorative traits (foreleg tufts) are preferred by females as mates, but are more readily detected by predators. However, predation risk may also be influenced by the interaction between components of signals and the environment in which signaling occurs. Courting male spiders were readily accepted as prey by a sympatric predator, the American toad (Anaxyrus americanus). We used video playback to tease apart the interactive effect between visual signals and the signaling environment on the ability of toads to detect courting spiders as a function of distance, background contrast, the presence or absence of male foreleg tufts, and behavioral activity. The response of toads to video sequences of male spiders was similar to their response to live male spiders. Toad response varied over distance toward spiders displayed against high contrast (sunny) vs. low contrast (shaded) backgrounds. Beyond 30 cm, more toads detected courting male spiders against light, ‘sunny’ backgrounds and detected them faster when compared to the same spider stimulus against darker, ‘shady’ backgrounds. In choice tests, toads oriented more often toward courting males with leg tufts than those without. Toad responses also varied with male spider behavior in that only videos of moving males were attacked. Latency to orient and detection by toads was significantly greater for walking males than courting males, and this effect was most evident at distances between 30 cm and 50 cm. Results supported that courting wolf spiders are at significant risk of predation by visually acute predators. Distance, background contrast, and the presence of foreleg decorations influence detection probability. Thus, the same complex visual signals that make males conspicuous and are preferred by females can make males more vulnerable as prey to toads.