柑橘大实蝇精巢、精泵和精泵内骨骼的生长发育状况

【目的】柑橘大实蝇是一种严重为害柑橘类果实的经济害虫。研究其精巢、精泵以及精泵内骨骼生长发育状况,有助于提高柑橘大实蝇人工繁殖效率以及其田间防治效果,为柑橘大实蝇的预测预报及防治提供理论基础。【方法】基于光学显微镜测量恒温和室温条件下柑橘大实蝇雄虫的精巢、精泵以及精泵内骨骼的长度和宽度,并建立其长度、宽度和指数的函数模型,比较恒温和室温2种饲养条件下其雄虫器官发育状况差异。【结果】无论是在恒温还是室温条件下饲养,随着柑橘大实蝇雄成虫日龄的增加,其精巢、精泵以及精泵内骨骼的长度、宽度和指数变化趋势均符合幂函数增长模型。在恒温和室温条件下,其雄虫的精巢宽度、精泵的长度和宽度以及指数、精泵内骨骼宽度均无明显差异。在室温条件下饲养的雄虫的精巢长度[(4.00±0.14) mm]及指数(3.40±0.14)、精泵内骨骼长度[(1.65±0.03) mm]及指数(1.84±0.08)均分别显著高于在恒温条件下饲养的雄虫的精巢长度[(3.75±0.13) mm]及指数(3.19±0.14)、精泵内骨骼长度[(1.61±0.03) mm]及指数(1.77±0.08)。【结论】变温(室温)比恒温更有利于柑橘大实蝇雄虫的精巢和精泵内骨骼的发育,并推荐使用精泵长度推断其雄虫日龄的方法。     

Novel hepacivirus in Asian house shrew,China

<正>Dear Editor,Hepatitis C virus (HCV) is a leading global cause of various liver diseases, including chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. The genome of HCV is monopartite, single-stranded, positive RNA, about 10 kb in size.HCV is the prototype species of the Hepacivirus genus,which contains 14 species according to the update from the International Committee on Taxonomy of Viruses (Smith et al., 2016). Prior to 2005, humans were thought to be the only     

Definition of immunogenic carbohydrate epitopes

Carbohydrates are known as sources of immunological cross-reactivity of allergenic significance. In celery and in cypress pollen, the major allergens Api g 5 and Cup a 1 are recognised by antisera raised against anti-horseradish peroxidase and by patients' IgE which apparently bind carbohydrate epitopes; mass spectrometric analysis of the tryptic peptides and of their N-glycans showed the presence of oligosaccharides carrying both xylose and core alpha1,3-fucose residues. Core alpha1,3-fucose residues are also a feature of invertebrates: genetic and biochemical studies on the fruitfly Drosophila melanogaster, the parasitic trematode Schistosoma mansoni and the nematode worm Caenorhabditis elegans indicate that these organisms possess core alpha1,3-fucosyltransferases. Various experiments have shown that fucosyltransferases from both fly and worm are responsible in vivo and in vitro for the synthesis of N-glycans which cross-react with anti-horseradish peroxidase; thus, we can consider these enzymes as useful tools in generating standard compounds for testing cross-reactive carbohydrate epitopes of allergenic interest.     

Fucosylation enhances colonization of ticks by Anaplasma phagocytophilum

Fucosylated structures participate in a wide range of pathological processes in eukaryotes and prokaryotes. The impact of fucose on microbial pathogenesis, however, has been less appreciated in arthropods of medical relevance. Thus, we used the tick‐borne bacterium Anaplasma phagocytophilum– the agent of human granulocytic anaplasmosis to understand these processes. Here we show that A. phagocytophilum uses α1,3‐fucose to colonize ticks. We demonstrate that A. phagocytophilum modulates the expression of α1,3‐fucosyltransferases and gene silencing significantly reduces colonization of tick cells. Acquisition but not transmission of A. phagocytophilum was affected when α1,3‐fucosyltransferases were silenced during tick feeding. Our results uncover a novel mechanism of pathogen colonization in arthropods. Decoding mechanisms of pathogen invasion in ticks might expedite the development of new strategies to interfere with the life cycle of A. phagocytophilum.     

Divalent cation enhancement of the agglutinability by soyabean lectin of liposomes prepared from total lipid of erythrocytes and of erythrocyte membranes

CaCl₂ or MgCl₂ but not NaCl enhances the soyabean lectin-induced agglutination of liposomes prepared from total lipids of erythrocyte membranes. The addition of purified phosphatidylserine to the total lipids of erythrocyte membranes before the formation of liposomes inhibits lectin-induced agglutinability of the preparation in the absence of CaCl₂, but not in its presence. When preformed phosphatidylserine liposomes are added to liposomes of total lipids of erythrocyte ghosts, they do not inhibit agglutination, indicating that phosphatidylserine does not inhibit the lectin directly. CaCl₂ or MgCl₂ but not NaCl also stimulates the soyabean lectin-induced agglutination of human erythrocyte membranes.Electron micrographs indicate that the liposome preparations are multilamellar and separate even in the presence of CaCl₂. When such liposomes are treated with lectin with or without CaCl₂, the electron micrographs show significant agglutination without apparent fusion. The reversal of the agglutination of liposomes by specific sugars followed by turbidimetric and electron microscopic techniques supports the conclusion that CaCl₂ stimulated lectin-induced agglutination is unaccompanied by fusion.The stimulation by divalent cations of lectin-induced agglutination of erythrocyte ghosts or of our liposomes may be due to a decrease in apparent surface charge of these membrane systems.     

High-performance liquid chromatographic assay for pilocarpine in aqueous humor

A high-performance liquid chromatographic assay for pilocarpine has been developed for the determination of pilocarpine in aqueous humor. A structurally similar internal standard is used, and pilocarpine is separated from isopilocarpine under the chromatographic conditions used. A 100μl sample is mixed with an aliquot of internal standard at pH 8.3 and extracted with methylene chloride. The extract is evaporated to dryness and the alkaloids are quaternized with p-nitrobenzyl bromide. Following the quaternization, the sample is evaporated to dryness, washed and diluted with a mobile phase—triethylamine mixture and analyzed by high-performance liquid chromatography using a reversed-phase octadecylsilane column with detection at a wavelength of 254 nm. This is a highly sensitive, reproducible and selective assay for measuring pilocarpine at physiological levels in individual aqueous humor samples.     

Characterisation of class I and II α-mannosidases from Drosophila melanogaster

Homology searches indicated that up to five class I α-mannosidases (glycohydrolase family 47) and eight class II α-mannosidases (glycohydrolase family 38) are encoded by the fruitfly (Drosophila melanogaster) genome. Selected example mannosidases were expressed in secreted form using the yeast Pichia pastoris. A number of characteristics of these enzymes were determined with p-nitrophenyl-α-mannoside as substrate; particularly striking were the low optima (pH 5) of three class II mannosidases most closely related to known lysosomal mannosidases and the distinct Co(II)-requirement of a mannosidase previously named ManIIb. Some of the recombinant mannosidases were demonstrably active towards oligomannosidic glycans, specifically, the Co(II)-requiring ManIIb, two ‘acidic’ mannosidases and the class I mas-1 mannosidase. Other than previous characterisations of the well-known Golgi mannosidase II, this is the first study summarising various properties of recombinant mannosidases from the fruitfly.     

The effect of temperature on the agglutinability by lectins of liposomes prepared from total lipids of erythrocytes

Multilamellar liposomes prepared from total lipids of red blood cells are agglutinable by the addition of soybean lectin. At 5 °C the rate of agglutination is significantly slower than at 37 °C, in contrast to erythrocyte ghosts and ghosts sonicated to 1 μ vesicles. The slower lateral mobilities of the lectin glycolipid receptor in the lipid liposomes due to increased microviscosity of the bilayer at the lower temperature, might be one explanation of our agglutination results. However, the opposite temperature dependence seen with ghosts argues for a possible protein modulation of the agglutination reaction.     

Reconstitution in vitro of the GDP-fucose biosynthetic pathways of Caenorhabditis elegans and Drosophila melanogaster

The deoxyhexose sugar fucose has an important fine-tuning role in regulating the functions of glycoconjugates in disease and development in mammals. The two genetic model organisms Caenorhabditis elegans and Drosophila melanogaster also express a range of fucosylated glycans, and the nematode particularly has a number of novel forms. For the synthesis of such glycans, the formation of GDP-fucose, which is generated from GDP-mannose in three steps catalysed by two enzymes, is required. By homology we have identified and cloned cDNAs encoding these two proteins, GDP-mannose dehydratase (GMD; EC 4.2.1.47) and GDP-keto-6-deoxymannose 3,5-epimerase/4-reductase (GER or FX protein; EC 1.1.1.271), from both Caenorhabditis and Drosophila. Whereas the nematode has two genes encoding forms of GMD (gmd-1 and gmd-2) and one GER-encoding gene (ger-1), the insect has, like mammalian species, only one homologue of each (gmd and gmer). This compares to the presence of two forms of both enzymes in Arabidopsis thaliana. All corresponding cDNAs from Caenorhabditis and Drosophila, as well as the previously uncharacterized Arabidopsis GER2, were separately expressed, and the encoded proteins found to have the predicted activity. The biochemical characterization of these enzymes is complementary to strategies aimed at manipulating the expression of fucosylated glycans in these organisms.