Mite (Acari; Arachnida) diversity of two native plants in fragments of a semideciduous seasonal forest in Brazil

Studies to determine mite species richness in natural environments are still scarce, and have been conducted mainly in tropical ecosystems. The aim of this study was to determine the species richness of mites on two common native plants in fragments of the semideciduous seasonal forest in the Northwest of São Paulo State, Brazil. In each of eight fragments, 10 specimens of Actinostemon communis (Euphorbiaceae) and 10 of Trichilia casaretti (Meliaceae) were selected and marked. In total, 124 species of mites belonging to 21 families were found on the two plants. Tarsonemidae had the highest diversity (34 species), followed by Phytoseiidae (31), Tetranychidae (9) and Tenuipalpidae (8). Species accumulation curves for the two sampled plants did not reach an asymptote, even with the large sampling effort. Hence, it is estimated that a greater sampling effort may lead to an increase in species richness compared with what was found in this study. The richness of this mite fauna suggests that preservation of these plant species is important to maintain the mite diversity in these forest fragments.     

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.     

A new microinvertebrate with features of mites and tardigrades in Dominican amber

From time to time, small, fragile, previously unknown fossil invertebrates are found in specialized habitats. Occasionally, as in the present case, a fragment of the original habitat that existed millions of years ago is also preserved. The present article describes a previously unknown microinvertebrate in Dominican amber that cannot be placed in any group of extant invertebrates. Placed in a new family, genus, and species, the fossil shares characters with both tardigrades and mites, but clearly belongs to neither group. The several hundred fossil individuals preserved in the amber shared their moist, warm habitat with pseudoscorpions, nematodes, fungi, and protozoa. The large number of fossils provided additional evidence of their biology, including their reproductive behavior, developmental stages, and food. While there is no extant group that can accommodate these fossils, and we have no knowledge of any extant descendants, this discovery shows that unique lineages of minute invertebrates were surviving in the mid‐Tertiary.     

Phylogeography of lethal male fighting in a social spider mite

When males fight for access to females, such conflict rarely escalates into lethal fight because the risks and costs involved, that is, severe injury or death, are too high. The social spider mite, Stigmaeopsis miscanthi, does exhibit lethal male fights, and this male–male aggressiveness varies among populations. To understand the evolution of lethal fighting, we investigated aggressiveness in 42 populations and phylogenetic relationships in 47 populations along the Japanese archipelago. By analysis of the male weapon morph, a proxy for aggressiveness, we confirmed the existence of a mildly aggressive (ML) form, besides the low aggression (LW) and high aggression (HG) forms reported earlier. To evaluate demographic history of these three forms, we employed the approximate Bayesian computation approach using mtCOI sequences and taking into consideration the postlast glacial expansion history of the host plant, Miscanthus sinensis. As results, hierarchical split models are more likely to explain the observed genetic pattern than admixture models, and the ML form in the subtropical region was considered the ancestral group. The inferred demographic history was consistent with the one reconstructed for the host plant in a previous study. The LW form was split from the ML form during the last glacial period (20,000–40,000 years BP), and subsequently, the HG form was split from the ML form at the end of or after the last glacial period (5,494–10,988 years BP). The results also suggest that the mite invaded Japan more than once, resulting in the present parapatric distribution of LW and HG forms in eastern Japan.     

Effect of coupled reduced irrigation and nitrogen fertilizer on soil mite community composition in a wheat field

Groundwater and nitrogen fertilizer overuse severely threatens crop productions; thus, current ecological agriculture requires low irrigation and nitrogen fertilizer inputs. The effects of combined reduced irrigation and nitrogen fertilizer addition on soil organism (e.g., mite) community and biodiversity remain poorly understood. We analyzed soil mite community composition, wheat grain yield, and soil characteristics in a 10‐year manipulation experiment with two levels of irrigation (reduced and conventional irrigation) and five nitrogen fertilizer levels (0, 70, 140, 210, and 280 kg N/ha). Reduced irrigation (20% reduction, from 280 to 220 mm) and nitrogen fertilizer (25% reduction, from 280 to 210 kg N/ha) addition did not significantly influence soil mite community and wheat yield. The relative abundances of fungivores and predators showed negative quadratic relationships with wheat yield, while that of plant parasites showed a positive relationship. The relationships between soil mite trophic groups and wheat yield revealed that we can evaluate the impacts of reduced irrigation and nitrogen fertilizer addition from the perspective of soil fauna. Soil mite community composition was altered by soil abiotic factors prior to reduced irrigation and nitrogen fertilizer addition. Overall, moderate reductions of irrigation and nitrogen fertilizer may not threaten to soil mite community and diversity or decrease crop production; in contrast, such reductions will benefit mite community development and the sustainable agriculture.