人参连作根际土壤中酚酸物质对人参锈腐病菌的化感效应

采用高效液相色谱法对人参连作根际土壤中的酚酸物质进行了分离鉴定,检测发现人参根际土壤中含有没食子酸、水杨酸、3-苯基丙酸、苯甲酸和肉桂酸5种酚酸物质.采用外源添加法研究该5种酚酸物质对人参锈腐病菌的化感效应.结果表明: 5种酚酸对人参锈腐病菌的菌丝生长和孢子萌发都表现出高浓度抑制、低浓度促进的作用.没食子酸、水杨酸和苯甲酸在0.5 mmol·L^-1处理浓度下,3-苯基丙酸和肉桂酸在0.05 mmol·L^-1处理浓度下,均能够显著促进人参锈腐病菌菌丝生长和孢子萌发,并显著加重人参锈腐病病害严重度.     

Emerging infectious diseases associated with bat viruses

Bats play important roles as pollen disseminators and pest predators. However, recent interest has focused on their role as natural reservoirs of pathogens associated with emerging infectious diseases. Prior to the outbreak of severe acute respiratory syndrome (SARS), about 60 bat virus species had been reported. The number of identified bat viruses has dramatically increased since the initial SARS outbreak, and most are putative novel virus species or genotypes. Serious infectious diseases caused by previously identified bat viruses continue to emerge throughout in Asia, Australia, Africa and America. Intriguingly, bats infected by these different viruses seldom display clinical symptoms of illness. The pathogenesis and potential threat of bat-borne viruses to public health remains largely unknown. This review provides a brief overview of bat viruses associated with emerging human infectious diseases.     

Marburg virus infection detected in a common African bat

Marburg and Ebola viruses can cause large hemorrhagic fever (HF) outbreaks with high case fatality (80-90%) in human and great apes. Identification of the natural reservoir of these viruses is one of the most important topics in this field and a fundamental key to understanding their natural history. Despite the discovery of this virus family almost 40 years ago, the search for the natural reservoir of these lethal pathogens remains an enigma despite numerous ecological studies. Here, we report the discovery of Marburg virus in a common species of fruit bat (Rousettus aegyptiacus) in Gabon as shown by finding virus-specific RNA and IgG antibody in individual bats. These Marburg virus positive bats represent the first naturally infected non-primate animals identified. Furthermore, this is the first report of Marburg virus being present in this area of Africa, thus extending the known range of the virus. These data imply that more areas are at risk for MHF outbreaks than previously realized and correspond well with a recently published report in which three species of fruit bats were demonstrated to be likely reservoirs for Ebola virus.     

云杉腐烂病菌Cytospora piceae全基因组测序及比较基因组分析

【目的】壳囊孢属(Cytospora)真菌引起的林木腐烂病和枝枯病,是一类重要的、分布广泛的枝干病害,可引起重大经济损失和生态破坏。通过全基因组测序和比较基因组学分析,探究不同腐烂病菌的全基因组特征,分析其与寄主选择和致病性相关的基因或基因家族的差异性,将有助于进一步揭示腐烂病菌与寄主互作的分子机制,为腐烂病的有效防治提供基础资料。【方法】采用PacBio测序技术对云杉腐烂病菌Cytosporapiceae进行了全基因组测序和组装,并通过比较基因组学方法,从基因组水平探究引起腐烂病的4种腐烂病菌的基因组的差异,分析其共有的和特有的与致病相关的基因家族。【结果】C. piceae基因组大小为39.25 Mb,GC含量为51.79%。基于单拷贝直系同源基因构建的系统发育树显示,C. piceae与Cytospora chrysosperma的进化关系相近,Valsamali和Valsapyri则更相近。比较基因组学分析表明,4种腐烂病菌均具有重复诱导的点突变(RIP)活性,其中,C. piceae的RIP活性最强。与其他3种腐烂病菌相似,与木质素降解相关的AA3和AA7家族在C. piceae中显著扩张,但木质素降解关键酶AA5家族均缺失;C. piceae和C. chrysosperma基因组中果胶降解关键酶GH28和CE8家族基因的数量与V. mali和V. pyri相近。4种腐烂病菌都含有较多数量的MFS(major facilitator superfamily)超家族转运蛋白和较少的ABC(ATP-binding cassette transporter)超家族转运蛋白,但C. piceae含有更多DHA2、PDR和MDR类转运蛋白。4种腐烂病菌的分泌蛋白的GO分类分子功能主要集中在水解酶活性,其中V. mali含有最多数量的该类别基因;而生物学过程则集中在碳水化合物代谢过程、果胶分解过程和氧化还原过程。在次生代谢核心基因中,C.piceae的PKS基因明显少于V.mali和V.pyri;在C.piceae含有的4个特异性次生代谢基因中,3个为NRPS基因。【结论】4种腐烂病菌含有的碳水化合物活性酶的种类和数量相似,且都具有较强的果胶降解能力。不同腐烂病菌的膜转运蛋白中多药转运体的选择性扩增,以及次生代谢核心基因中NRPS类基因的特异性存在和缺失,表明它们作为重要的致病因子很可能在腐烂病菌寄主选择中发挥了重要的作用。     

Phylogenetic evaluation of Geomyces and allies reveals no close relatives of Pseudogymnoascus destructans, comb. nov., in bat hibernacula of eastern North America

White-nose syndrome (WNS)  of bats, caused by the fungus previously known as Geomyces destructans, has decimated populations of insectivorous bats in eastern North America. Recent work on fungi associated with bat hibernacula uncovered a large number of species of Geomyces and allies, far exceeding the number of described species. Communication about these species has been hindered by the lack of a modern taxonomic evaluation, and a phylogenetic framework of the group is needed to understand the origin of G. destructans and to target closely related species and their genomes for the purposes of understanding mechanisms of pathogenicity. We addressed these issues by generating DNA sequence data for the internal transcribed spacer (ITS) region, nuclear large subunit (LSU) rDNA, MCM7, RPB2, and TEF1 from a diverse array of Geomyces and allies that included isolates recovered from bat hibernacula as well as those that represent important type species. Phylogenetic analyses indicate Geomyces and allies should be classified in the family Pseudeurotiaceae, and the genera Geomyces, Gymnostellatospora, and Pseudogymnoascus should be recognized as distinct. True Geomyces are restricted to a basal lineage based on phylogenetic placement of the type species, Geomyces auratus. Thus, G. destructans is placed in genus Pseudogymnoascus. The closest relatives of Pseudogymnoascus destructans are members of the Pseudogymnoascus roseus species complex, however, the isolated and long branch of P. destructans indicates that none of the species included in this study are closely related, thus providing further support to the hypothesis that this pathogen is non-native and invasive in eastern North America. Several conidia-producing isolates from bat hibernacula previously identified as members of Pseudeurotium are determined to belong to the genus Leuconeurospora, which is widespread, especially in colder regions. Teberdinia hygrophila is transferred to Pseudeurotium as Pseudeurotium hygrophilum, comb. nov., in accordance with the one name per fungus system of classification, and two additional combinations are made in Pseudogymnoascus including Pseudogymnoascus carnis and Pseudogymnoascus pannorum. Additional sampling from other regions of the world is needed to better understand the evolution and biogeography of this important and diverse group of fungi.     

Serotypic characterization of group A rotaviruses associated with children's diarrhea in Slovakia

A total of 368 rotavirus RNA-positive (PAGE) stool samples collected continually during 1992-95 from infants and young children under five years of age hospitalized with acute gastroenteritis were serotyped using an enzyme immunoassay with VP7-specific monoclonal antibodies (ELISA with MAbs) for serotypes G1-G4. The serotype was identified in 106 stool samples (29%). Comparison of electropherotype and serotype profile in individual samples did not show any remarkable correlation. The members of three electropherotypes (A, C, K) belonged to all 4 serotypes. The representatives of two electropherotypes (E, G) and of mixed electropherotype did not react with any of the specific monoclonal antibodies used. The distribution of the serotypes was scored as 52, 13, 14 and 7.5% for G1 G4, respectively, whereas 13% of samples reacted with two or more type-specific monoclonal antibodies. The G1 serotype dominated during the period followed.     

Altered SOS induction associated with mutations in recF, recO and recR

The SOS system of Escherichia coli aids survival following damage to DNA by promoting DNA repair while cell division is delayed. Induction of the SOS response is dependent on RecA and also on the product of recF. We show that normal induction also requires the products of recO and recR. SOS induction was monitored using a sfiA-lacZ fusion strain. Induction was delayed to a similar degree by mutation in recF, recO or recR. A similar effect was observed following overexpression of RecR from a recombinant recR ⁺plasmid. We show that the overexpression of RecR also reduces the UV resistance of a recBC sbcBC strain and of a sfiA strain, but not of a rec ⁺ sfiA ⁺strain. The implications of these data for the kinetics of DNA repair are discussed.     

RAPD markers associated with quercetin accumulation in Psidium guajava

We used a random amplified polymorphic DNA (RAPD) amplification method to identify molecular markers associated with high quercetin accumulation in the leaves of Psidium guajava L. trees, selected from four different Mexican agronomic regions. We identified six polymorphic RAPD fragments of 620, 590, 370, 690, 480 and 460 bp among individuals of P. guajava. Genetic linkage disequilibrium analysis revealed that three RAPD profiles considered as DNA markers (620/590 bp, 370 bp and 480/460 bp) had a positive, direct association with quercetin content. These informative molecular markers can be used for selective identification of plants with the highest accumulation of flavonoids.     

Trophic niche changes associated with habitat fragmentation in a Neotropical bat species

Habitat fragmentation could alter ecological traits including species trophic habits. Here, we used carbon and nitrogen stable isotope ratios to establish differences in isotopic niche width and food resource use between forest fragments and the continuous forest for the phyllostomid frugivorous bat Artibeus lituratus. Using mist nests, we captured bats from two forest fragments and two sites in continuous forest, and sampled from each individual captured three body tissues with contrasting turnover rates (skin, muscle, and liver). Samples were collected between February and March (austral summer) and between August and September (austral winter). In addition, in each sampling site and season we collected potential food resources (fruits and insects) consumed by our A. lituratus. Our findings indicate that A. lituratus had a predominantly omnivorous diet, with high consumption of insects during summer in forest fragments. The increasing consumption of insects in these fragments seems to have led to a wider isotopic niche, in relation to the continuous forest. Because A. lituratus is typically a seed disperser, changes in trophic habits in the forest fragments from frugivory to insectivory may diminish their role in forest regeneration. Abstract in Portuguese is available with online material.     

Genetic structure and differentiation of Psathyrostachys huashanica populations detected with RAPD markers

Psathyrostachys huashanica Keng is a perennial grass and belongs to genus Psathyrostachys under Triticeae. sathyrostachys is found in the center of Middle Asia and the Caucasus Mountain, while P. huashanica, a species endemic to China, is only located in Mt. Hua in the Shaanxi province, China. At present, the population of this species is decreasing, and reaching the edge of extinction. Due to the limitation in distribution and the importance as breeding material for germplasm storage, it has been considered as first class among the national protected rare plants. For this reason, the present study is significant in probing plant flora, origin and evolution of Triticeae, and crop breeding. Randomly amplified polymorphic DNA (RAPD) markers were used to analyze the genetic structure and differentiation of P. huashanica populations sampled in three valleys (Huangpu, Xian, and Huashan Valleys) in Mt. Hua. One hundred and twenty-two RAPD fragments were obtained in all 266 individuals with 20 primers with a mean of 6.1 (2–10) fragments per primer. The percentage of polymorphic loci (PPB) was 60.66% in Huangpu Valley, 90.98% in Xian Valley, 95.08% in Huashan Valley, and the total PPB was 95.08%, which indicated a highly genetic variability of P. huashanica. The Shannon’s Information index and G _ST were 0.3306 and 0.3263, respectively, indicating that there were more genetic variations within the subpopulations than those among the subpopulations. The gene flow among the subpopulations of P. huashanica (Nm = 1.0322) was much less than that of the common anemophytes (Nm = 5.24). Mean genetic distance is 0.1 571 (range: 0.0022–0.2901). The highest value of genetic distance was found between the subpopulation (hp1) of Huangpu Valley and the highest altitude subpopulation (h8) of Huashan Valley. Correlation analysis detected significant correlation between genetic distance and vertical distance of altitude. Clustering analysis and principal coordinate analysis revealed the genetic differentiation among the populations of P. huashanica. Differentiation mainly occurred between the higher altitude subpopulations and the lower altitude subpopulations, suggesting that altitude might be the major factor that restricted the gene flow between different altitude subpopulations and resulted in differentiation of subpopulations. Translated from Acta Ecologica Sinica, 2005, 25(4): 719–726 [译自: 生态学报]     

Diverse archaeal community of a bat guano pile in Domica Cave (Slovak Karst,Slovakia)

The molecular diversity of Archaea in a bat guano pile in Cave Domica (Slovakia), temperate cave ecosystem with significant bat colony (about 1600 individuals), was examined. The guano pile was created mainly by an activity of the Mediterranean horseshoe bat (Rhinolophus euryale) and provides a source of organic carbon and other nutrients in the oligotrophic subsurface ecosystem. The upper and the basal parts of guano surface were sampled where the latter one had higher pH and higher admixture of limestone bedrock and increased colonization of invertebrates. The relative proportion of Archaea determined using CARD-FISH in both parts was 3.5–3.9 % (the basal and upper part, respectively). The archaeal community was dominated by non-thermophilic Crenarchaeota (99 % of clones). Phylogenetic analysis of 115 16S rDNA sequences revealed the presence of Crenarchaeota previously isolated from temperate surface soils (group 1.1b, 62 clones), deep subsurface acid waters (group 1.1a, 52 clones) and Euryarchaeota (1 clone). Four of the analyzed sequences were found to have little similarity to those in public databases. The composition of both archaeal communities differed, with respect to higher diversity of Archaea in the upper part of the bat guano pile. High diversity archaeal population is present in the bat guano deposit and consists of both soil- and subsurface-born Crenarchaeota.