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1.
中国微生物物种多样性研究进展   总被引:7,自引:0,他引:7  
郭良栋 《生物多样性》2012,20(5):572-580
微生物是分布最为广泛的生命形式,几乎分布到地球上的所有生境,具有丰富的物种多样性。我国地域辽阔,跨越热带至寒温带,气候条件多样,地理环境与生态系统类型复杂,是世界上生物多样性最丰富的国家之一。我国已开展了大量微生物多样性研究,并证实我国多样的生境蕴藏着丰富的微生物物种多样性。目前我国已报道真核微生物(菌物)约14,700种,其中包括真菌约14,060种、卵菌约300种、黏菌约340种,而真菌中有药用菌473种、食用菌966个分类单元。特别是近年来通过免培养的分子生物学技术发现我国存在丰富的原核微生物多样性。本文概述了传统方法和现代分子生物学技术在我国原核微生物(古菌、细菌)和真核微生物(真菌、卵菌、黏菌)物种多样性研究的最新进展。  相似文献   

2.
An in vivo experiment was performed with pigs to study the inhibitory effect of fermented feed on the bacterial population of the gastrointestinal tract. Results demonstrated a significant positive correlation between pH and lactobacilli in the stomach contents of pigs in dry feed as well as in the stomach contents of pigs fed fermented feed. Furthermore, a significant positive correlation between the pH and the numbers of bacteria in the family Enterobacteriaceae in the contents of the stomach of pigs fed dry feed was found. In the stomach contents of pigs fed fermented feed, a significant negative correlation was found between the concentration of the undissociated form of lactic acid and the numbers of Enterobacteriaceae. The numbers of Enterobacteriaceae in the contents of the stomach, ileum, cecum, colon, and rectum of pigs fed fermented feed were significantly lower compared with the contents of the stomach, ileum, caecum, colon, and rectum of pigs fed dry feed. The numbers of total lactobacilli were significantly higher in the stomach contents of pigs fed fermented feed and in the ileum contents of one pig group fed fermented feed compared with the contents of pigs fed dry feed. However, the influence of lactobacilli on numbers of Enterobacteriaceae could not be demonstrated. It was concluded that fermented feed influences the bacterial ecology of the gastrointestinal tract and reduces the levels of Enterobacteriaceae in the different parts of the gastrointestinal tract.  相似文献   

3.
There is a need for monitoring the status and trends of freshwater biodiversity in order to quantify the impacts of human actions on freshwater systems and to improve freshwater biodiversity conservation. Current projects carrying assessment of freshwater biodiversity focus mainly on leading-better-known groups such as fish, or identify keystone species and/or endemic freshwater systems for conservation purposes. Our purpose is to complete these existing projects by providing quantitative estimates of species number for all freshwater groups on each continent and/or major eco-regions. This article present the results of the first implementation phase carried out from September 2002 to June 2003 and which addressed only freshwater animal species. The project consisted of: (1) compiling existing data from literature, web sites and museum collections; (2) contacting scientific experts of each group to provide a ‘to the best of their knowledge, estimates of species numbers. In this study, we consider as true freshwater species, those that complete part or all of their life cycle in freshwater, and water-dependant species those that need freshwater for food or that permanently use freshwater habitats. The current order of magnitude for known freshwater animal species world wide is 100 000, of which half are insects. Among other groups, there are some 20 000 vertebrate species; 10 000 crustacean species and 5000 mollusc species that are either true freshwater or water-dependant species. The study highlighted gaps in the basic knowledge of species richness at continental and global scales: (1) Some groups such as Protozoa, nematodes or annelids have been less studied and data on their diversity and distribution is scarce. Because current richness estimates for these groups are greatly biased by knowledge availability, we can expect that real species numbers might be much higher. (2) Continents are not equal in the face of scientific studies: South America and Asia are especially lacking global estimates of species richness for many groups, even for some usually well-known ones such as molluscs or insects. The second phase of the project will address freshwater plants and algae. The present status should be considered as a first sketch of the global picture of freshwater biodiversity. We hope that this project will initiate interactive exchange of data to complete and update this first assessment.  相似文献   

4.
Sun  Yan  Yuan  Zhimin  Guo  Yuming  Qin  Yuanzhao  Ban  Yongtian  Niu  Hongxing  Bu  Yanzhen 《Annals of microbiology》2019,69(13):1407-1414
Previous studies have assessed the diversity of gastrointestinal bacteria in bats and reported that some of the strains are pathogenic to humans; therefore, bats are considered to be potential reservoirs of zoonotic pathogens. However, the bacterial diversity and types of pathogenic bacteria in the gastrointestinal tracts of Rhinolophus luctus and Murina leucogaster have not yet been determined. Humans frequently come into contact with these species; therefore, assessments of their gut microbiota, especially potential pathogens, are essential for public health. In the present study, MiSeq high-throughput sequencing was used to address this research gap, and the results were compared with those reported previously. The V3–V4 regions of the 16S rRNA gene were sequenced using the MiSeq high-throughput sequencing platform to determine the bacterial community of the stomach and the intestines of R. luctus and M. leucogaster. The bacteria in the gastrointestinal tracts of R. luctus and M. leucogaster were classified into three and four main bacterial phyla, respectively. In both R. luctus and M. leucogaster, the dominant phylum was Proteobacteria (stomach 86.07% and 95.79%, intestines 91.87% and 88.78%, respectively), followed by Firmicutes (stomach 13.84% and 4.19%, intestines 8.11% and 11.20%, respectively). In total, 18 and 20 bacterial genera occurred in a relative abundance of 0.01% or more in the gastrointestinal tracts of R. luctus and M. leucogaster, respectively. In R. luctus, the dominant genera were Lactococcus (10.11%) and Paeniclostridium (3.41%) in the stomach, and Undibacterium (28.56%) and Paeniclostridium (4.69%) in the intestines. In M. leucogaster, the dominant genera were Undibacterium (54.41%) and Burkholderia (5.28%) in the stomach, and Undibacterium (29.67%) and Enterococcus (7.19%) in the intestines. Among the detected gastrointestinal tract flora of R. luctus and M. leucogaster, 12 bacterial genera were pathogenic or opportunistic pathogens. A high number of human pathogens were detected in the gastrointestinal tracts of R. luctus and M. leucogaster, which demonstrates the urgency for increased efforts in the prevention and management of bat-to-human disease transmission from these species.  相似文献   

5.
1. Glycopeptides in the stomachs of eleven mammalian species, including human, rabbit, horse, cow, pig, goat, sheep, dog, cat, guinea pig and rat were assayed by determining the carbohydrate content of materials which remained after proteolysis. 2. The glycopeptide content was higher in the mucosa than in the muscular layer including serosa, especially in the porcine stomach and the fourth stomachs of the ruminants than in the stomachs of any other animals. 3. The glycopeptide, which was stained with both alcian blue and PAS, was absent or sparingly present in the mucosae of the human, rabbit, horse stomachs and in the mucosae of the first to third stomachs of the cow, goat and sheep, whereas in the mucosae of the pig, dog, cat, guinea pig and rat stomachs and in the mucosae of the fourth stomachs of the cow, goat and sheep, it was found in noticeable extents.  相似文献   

6.
Microbial degradation of oxalate in the gastrointestinal tracts of rats   总被引:1,自引:0,他引:1  
Rates of oxalate degradation by mixed bacterial populations in cecal contents from wild rats ranged from 2.5 to 20.6 mumol/g (dry weight) per h. The oxalate-degrading activity in cecal contents from three strains of laboratory rats (Long-Evans, Wistar, and Sprague-Dawley) from four commercial breeders was generally lower, ranging from 1.8 to 3.5 mumol/g (dry weight) of cecal contents per h. This activity did not increase when diets were supplemented with oxalate. When Sprague-Dawley rats from a fifth commercial breeder were fed an oxalate diet, rates of oxalate degradation in cecal contents increased from 2.0 to 23.1 mumol/g (dry weight) per h. Obligately anaerobic, oxalate-degrading bacteria, similar to ruminal strains of Oxalobacter formigenes, were isolated from the latter group of laboratory rats and from wild rats. Viable counts of these bacteria were as high as 10(8)/g (dry weight) of cecal contents, which was less than 0.1% of the total viable population. This report presents the first evidence for the presence of anaerobic oxalate-degrading bacteria in the cecal contents of rats and represents the first direct measurement of the concentration of these bacteria in the large bowel of monogastric animals. We propose that methods used for the maintenance of most commercial rat colonies often preclude the intestinal colonization of laboratory rats with anaerobic oxalate-degrading bacteria.  相似文献   

7.
The antigenic reactivities of the serum LDLs of several groups of animals (mammals, birds, snakes, and fish) have been compared by qualitative and quantitative immunological techniques. The cross-reactivities of the various LDLs were evaluated qualitatively by gel diffusion techniques and quantitatively by the precipitation and inhibition of precipitation tests. The degrees of cross-reaction between human and animal LDLs ranged from 80-88% in the Old World monkeys to 36-58% in the pig, 26-37% in the guinea pig, 1-10% in the chicken, and about 1% in the snakes and fish. These antigenic relationships are consistent with the taxonomic classification of these species, but are relatively closer than those observed for other serum proteins (e.g., albumin, transferrin, and hemoglobin). These results indicate a relatively high conservation of LDL structure through evolution, and are consistent with a common function for this lipoprotein in the transport and metabolism of cholesterol in the higher animals.  相似文献   

8.
The incidence of translocation of viable indigenous bacteria from the gastrointestinal tract to the mesenteric lymph node, spleen, liver, and kidney was compared in neonatally thymectomized mice and sham-thymectomized specific pathogen-free mice. The immunologic responses of the thymectomized mice to sheep erythrocytes were decreased compared to the responses of sham-thymectomized mice. Strictly anaerobic bacteria were isolated from only 1.8% of the organs from thymectomized mice and from none of the organs of shamthymectomized mice. Aerobic or facultatively anaerobic bacteria were cultured from 27.4% of the organs of thymectomized mice. Of the thymectomized mice, 70.7% contained viable aerobic or facultatively anaerobic bacteria in one or more of their organs tested, compared with only 10% of the sham-thymectomized mice.Escherichia coli was the predominant bacterial species isolated from these organs, althoughStaphylococcus aureus, Streptococcus, andCorynebacterium also were present.Bacteroides were the only strictly anaerobic bacteria cultured. Neonatal thymectomy promotes the translocation of certain indigenous bacteria from the gastrointestinal tract to the mesenteric lymph node, spleen, liver, and kidney.  相似文献   

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10.
Rates of oxalate degradation by mixed bacterial populations in cecal contents from wild rats ranged from 2.5 to 20.6 mumol/g (dry weight) per h. The oxalate-degrading activity in cecal contents from three strains of laboratory rats (Long-Evans, Wistar, and Sprague-Dawley) from four commercial breeders was generally lower, ranging from 1.8 to 3.5 mumol/g (dry weight) of cecal contents per h. This activity did not increase when diets were supplemented with oxalate. When Sprague-Dawley rats from a fifth commercial breeder were fed an oxalate diet, rates of oxalate degradation in cecal contents increased from 2.0 to 23.1 mumol/g (dry weight) per h. Obligately anaerobic, oxalate-degrading bacteria, similar to ruminal strains of Oxalobacter formigenes, were isolated from the latter group of laboratory rats and from wild rats. Viable counts of these bacteria were as high as 10(8)/g (dry weight) of cecal contents, which was less than 0.1% of the total viable population. This report presents the first evidence for the presence of anaerobic oxalate-degrading bacteria in the cecal contents of rats and represents the first direct measurement of the concentration of these bacteria in the large bowel of monogastric animals. We propose that methods used for the maintenance of most commercial rat colonies often preclude the intestinal colonization of laboratory rats with anaerobic oxalate-degrading bacteria.  相似文献   

11.
目的比较实验动物呼吸系统主要器官的组织学特征,为制定实验动物病理检测标准、以及毒理学、新药安全性评价提供依据。方法选取实验动物质量国家检测标准检测合格的恒河猴30只、昆明小鼠20只、SD大鼠20只、日本大耳白兔18只、比格犬16只、树鼩20只。除昆明小鼠采用颈椎脱臼致死外,其余动物麻醉后放血处死和病理解剖,对气管、肺脏进行病理大体检查和取材,常规病理制片,进行HE染色、特殊染色和免疫组化染色,显微镜下观察气管、肺脏的组织结构和细胞结构异同。结果 (1)实验动物气管上皮杯状细胞有差异:恒河猴、比格犬、日本大耳白兔杯状细胞较多,大鼠、小鼠、树鼩则较少或无。上皮分泌的黏液类型以中性黏液为主,比格犬杯状细胞分泌的黏液类型有中性黏液和酸性黏液。(2)实验动物黏膜下腺泡分布有差异:比格犬黏膜下层的腺泡最多,恒河猴、大鼠、小鼠、树鼩腺泡数量偏少,日本大耳白兔黏膜下层的混合腺泡最少。(3)实验动物的肺内支气管分支有差异:比格犬、恒河猴、日本大耳白兔由叶支气管、段支气管、小支气管、细支气管、终末细支气管和呼吸性细支气管组成,树鼩、大鼠、小鼠只由细支气管、终末细支气管和呼吸性细支气管组成。(4)实验动物细支气管组织结构有差异:恒河猴、比格犬的细支气管平滑肌为完整环形平滑肌层,没有缺失,而大鼠、小鼠、树鼩及日本大耳白兔的细支气管平滑肌薄或缺失。恒河猴、树鼩、大鼠细支气管有少量杯状细胞,其余实验动物均无杯状细胞。(5)实验动物Clara细胞形态有差异:比格犬Clara细胞呈立方形,其余动物呈柱状。结论实验动物呼吸系统组织结构的质是相同的,差异在于量的不同。研究人员在制定病理学检测标准、实验研究、药物安全性评价时应予充分考虑。  相似文献   

12.
1. The importance of species diversity for the stability of populations, communities and ecosystem functions is a central question in ecology. 2. Biodiversity experiments have shown that diversity can impact both the average and variability of stocks and rates at these levels of ecological organization in single trophic-level ecosystems. Whether these impacts hold in food webs and across trophic levels is still unclear. 3. We asked whether resource species diversity, community composition and consumer feeding selectivity in planktonic food webs impact the stability of resource or consumer populations, community biomass and ecosystem functions. We also tested the relative importance of resource diversity and community composition. 4. We found that resource diversity negatively affected resource population stability, but had no effect on consumer population stability, regardless of the consumer's feeding selectivity. Resource diversity had positive effects on most ecosystem functions and their stability, including primary production, resource biomass and particulate carbon, nitrogen and phosphorus concentrations. 5. Community composition, however, generally explained more variance in population, community and ecosystem properties than species diversity per se. This result points to the importance of the outcomes of particular species interactions and individual species' effect traits in determining food web properties and stability. 6. Among the stabilizing mechanisms tested, an increase in the average resource community biomass with increasing resource diversity had the greatest positive impact on stability. 7. Our results indicate that resource diversity and composition are generally important for the functioning and stability of whole food webs, but do not have straightforward impacts on consumer populations.  相似文献   

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微生物是地球上出现最早、分布最广、多样性最为丰富的生物类群。在地球演化三十多亿年的历史长河中,微生物不断适应和改变着不同时期的地球环境,与地球环境共进化。微生物微小的个体和长期的进化,使它们形成了极高的多样性,可以适应几乎任  相似文献   

16.
Thrombolites are unlaminated carbonate structures that form as a result of the metabolic interactions of complex microbial mat communities. Thrombolites have a long geological history; however, little is known regarding the microbes associated with modern structures. In this study, we use a barcoded 16S rRNA gene-pyrosequencing approach coupled with morphological analysis to assess the bacterial, cyanobacterial and archaeal diversity associated with actively forming thrombolites found in Highborne Cay, Bahamas. Analyses revealed four distinct microbial mat communities referred to as black, beige, pink and button mats on the surfaces of the thrombolites. At a coarse phylogenetic resolution, the domain bacterial sequence libraries from the four mats were similar, with Proteobacteria and Cyanobacteria being the most abundant. At the finer resolution of the rRNA gene sequences, significant differences in community structure were observed, with dramatically different cyanobacterial communities. Of the four mat types, the button mats contained the highest diversity of Cyanobacteria, and were dominated by two sequence clusters with high similarity to the genus Dichothrix, an organism associated with the deposition of carbonate. Archaeal diversity was low, but varied in all mat types, and the archaeal community was predominately composed of members of the Thaumarchaeota and Euryarchaeota. The morphological and genetic data support the hypothesis that the four mat types are distinctive thrombolitic mat communities.  相似文献   

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An immunocytochemical method using a recently produced monoclonal antibody (ASPM-29) with an antibody specificity to spermine (Spm) and spermidine (Spd) fixed in situ, was used to demonstrate an immunocytochemical localization of polyamine (PA) pools in the gastrointestinal tracts of rats and mice. High PA immunoreactivity was always found in the cytoplasm of cells not only at the cell proliferative zone or the precursor cell zone but also at the neighboring non-proliferative premature cell zone of the epithelium, and a gradient of decreasing PA levels was noticed from these cells to the fully mature differentiated gastric surface mucous cells and absorptive cells of the small and large intestines. Also, strong staining for PAs was seen in the cytoplasm of fully differentiated gastric chief cells and neurons of both the myenteric and submucous plexuses, whereas the nuclei of the cells remained virtually unstained. These results may suggest that PAs are closely associated with the high biosynthetic activity in the cells of the gastrointestinal mucosa of normal rats and mice. This seems to be consistent with the PA imunocytochemical results previously obtained for neoplastic cells and active protein- or peptide-secreting cells, including exocrine or endocrine cell types.  相似文献   

19.
Herbivorous beetles comprise a significant fraction of eukaryotic biodiversity and their plant-feeding adaptations make them notorious agricultural pests. Despite more than a century of research on their ecology and evolution, we know little about the diversity and function of their symbiotic microbial communities. Recent culture-independent molecular studies have shown that insects possess diverse gut microbial communities that appear critical for their survival. In this study, we combined culture-independent methods and high-throughput sequencing strategies to perform a comparative analysis of Longitarsus flea-beetles microbial community diversity (MCD). This genus of beetle herbivores contains host plant specialists and generalists that feed on a diverse array of toxic plants. Using a deep-sequencing approach, we characterized the MCD of eleven Longitarsus species across the genus, several of which represented independent shifts to the same host plant families. Database comparisons found that Longitarsus-associated microbes came from two habitat types: insect guts and the soil rhizosphere. Statistical clustering of the Longitarsus microbial communities found little correlation with the beetle phylogeny, and uncovered discrepancies between bacterial communities extracted directly from beetles and those from frass. A Principal Coordinates Analysis also found some correspondence between beetle MCD and host plant family. Collectively, our data suggest that environmental factors play a dominant role in shaping Longitarsus MCD and that the root-feeding beetle larvae of these insects are inoculated by soil rhizosphere microbes. Future studies will investigate MCD of select Longitarsus species across their geographic ranges and explore the connection between the soil rhizosphere and the beetle MCD.  相似文献   

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