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Neelesh Dahanukar Keerthi Krutha Mandar S. Paingankar Anand D. Padhye Nikhil Modak Sanjay Molur 《PloS one》2013,8(10)
The Western Ghats of India harbors a rich diversity of amphibians with more than 77% species endemic to this region. At least 42% of the endemic species are threatened due to several anthropogenic stressors. However, information on amphibian diseases and their impacts on amphibian populations in this region are scarce. We report the occurrence of Batrachochytridium dendrobatidis (Bd), an epidermal aquatic fungal pathogen that causes chytridiomycosis in amphibians, from the Western Ghats. In the current study we detected the occurrence of a native Asian Bd strain from three endemic and threatened species of anurans, Bombay Night Frog Nyctibatrachus humayuni, Leith''s Leaping Frog Indirana leithii and Bombay Bubble Nest Frog Raorchestes bombayensis, for the first time from the northern Western Ghats of India based on diagnostic nested PCR, quantitative PCR, DNA sequencing and histopathology. While, the Bd infected I. leithii and R. bombayensis did not show any external symptoms, N. humayuni showed lesions on the skin, browning of skin and sloughing. Sequencing of Bd 5.8S ribosomal RNA gene, and the ITS1 and ITS2 regions, revealed that the current Bd strain is related to a haplotype endemic to Asia. Our findings confirm the presence of Bd in northern Western Ghats and the affected amphibians may or may not show detectable clinical symptoms. We suggest that the significance of diseases as potential threat to amphibian populations of the Western Ghats needs to be highlighted from the conservation point of view. 相似文献
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有尾类是两栖动物三大类群中一个重要而特殊的类群,其四肢较弱,运动能力不强,分布地域性明显,开展有尾类分布现状和受危状况研究,对探讨有尾类动物系统进化和促进资源保护均具有重要的意义.作者通过广泛查阅国内外重要文献发现,中国有尾目现已记录50种及3亚种,隶属于3科15属,其中有中国特有种42种及3亚种,占中国有尾类物种总数的84.9%.对中国有尾类特有种的区系组成、分布特点、保护现状和受危状况进行了分析,并探讨了有尾类特有种的分布特征;针对有尾类种群数量下降的原因,提出了相应的保护对策. 相似文献
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Mating behaviour of four species of pill-millipedes under genus Arthrosphaera Pocock (Arthrosphaera dalyi Pocock and Arthrosphaera disticta Pocock, Arthrosphaera fumosa Pocock and Arthrosphaera magna Attems) endemic to the Western Ghats of Southern India was analyzed in mesocosms. Stridulation is a classical communication signal in males as well as females for mate selection. Conglobation (or volvation) is a mechanism of defence to protect from disturbance or avoid predation. If male touches female or vice versa they conglobate. To avoid disparity among individuals of the same species, volvating pill-millipedes evolved stridulation behaviour for communication. The male broadcasts appropriate signal to female through stridulation to advertise its interest in mating. The females test the male’s fitness by conglobation and suitable male uncoils the partner through stridulation signals. Male with its pygidium successfully uncoils the female and attains suitable orientation for courtship. Male pairs with female ventro–ventro contact in opposite direction to deposit sperm into the vulva of female. The duration of mating varies from species to species and usually a lapse from 3 to 30 min. Vibration generated by stridulation is species-specific and its perception mechanism in pill-millipedes is yet to be clearly understood. Present study emphasized the structure of stridulatory organs, mechanism of stridulation and pattern of mating behaviour in four species of pill-millipedes. 相似文献
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Epco Hasker Sangeeta Kansal Paritosh Malaviya Kamlesh Gidwani Albert Picado Rudra Pratap Singh Ankita Chourasia Abhishek Kumar Singh Ravi Shankar Joris Menten Mary Elizabeth Wilson Marleen Boelaert Shyam Sundar 《PLoS neglected tropical diseases》2013,7(2)
Introduction
Asymptomatic persons infected with the parasites causing visceral leishmaniasis (VL) usually outnumber clinically apparent cases by a ratio of 4–10 to 1. We describe patterns of markers of Leishmania donovani infection and clinical VL in relation to age in Bihar, India.Methods
We selected eleven villages highly endemic for Leishmania donovani. During a 1-year interval we conducted two house to house surveys during which we collected blood samples on filter paper from all consenting individuals aged 2 years and above. Samples were tested for anti-leishmania serology by Direct Agglutination Test (DAT) and rK39 ELISA. Data collected during the surveys included information on episodes of clinical VL among study participants.Results
We enrolled 13,163 persons; 6.2% were reactive to DAT and 5.9% to rK39. Agreement between the tests was weak (kappa = 0.30). Among those who were negative on both tests at baseline, 3.6% had converted to sero-positive on either of the two tests one year later. Proportions of sero-positives and sero-converters increased steadily with age. Clinical VL occurred mainly among children and young adults (median age 19 years).Discussion
Although infection with L. donovani is assumed to be permanent, serological markers revert to negative. Most VL cases occur at younger ages, yet we observed a steady increase with age in the frequency of sero-positivity and sero-conversion. Our findings can be explained by a boosting effect upon repeated exposure to the parasite or by intermittent release of parasites in infected subjects from safe target cells. A certain proportion of sero-negative subjects could have been infected but below the threshold of antibody abundance for our serologic testing. 相似文献6.
Distribution of biosurfactant-producing bacteria in undisturbed and contaminated arid Southwestern soils 总被引:15,自引:0,他引:15
Biosurfactants are a unique class of compounds that have been shown to have a variety of potential applications in the remediation of organic- and metal-contaminated sites, in the enhanced transport of bacteria, in enhanced oil recovery, as cosmetic additives, and in biological control. However, little is known about the distribution of biosurfactant-producing bacteria in the environment. The goal of this study was to determine how common culturable surfactant-producing bacteria are in undisturbed and contaminated sites. A series of 20 contaminated (i.e., with metals and/or hydrocarbons) and undisturbed soils were collected and plated on R(2)A agar. The 1,305 colonies obtained were screened for biosurfactant production in mineral salts medium containing 2% glucose. Forty-five of the isolates were positive for biosurfactant production, representing most of the soils tested. The 45 isolates were grouped by using repetitive extragenic palindromic (REP)-PCR analysis, which yielded 16 unique isolates. Phylogenetic relationships were determined by comparing the 16S rRNA gene sequence of each unique isolate with known sequences, revealing one new biosurfactant-producing microbe, a Flavobacterium sp. Sequencing results indicated only 10 unique isolates (in comparison to the REP analysis, which indicated 16 unique isolates). Surface tension results demonstrated that isolates that were similar according to sequence analysis but unique according to REP analysis in fact produced different surfactant mixtures under identical growth conditions. These results suggest that the 16S rRNA gene database commonly used for determining phylogenetic relationships may miss diversity in microbial products (e.g., biosurfactants and antibiotics) that are made by closely related isolates. In summary, biosurfactant-producing microorganisms were found in most soils even by using a relatively limited screening assay. Distribution was dependent on soil conditions, with gram-positive biosurfactant-producing isolates tending to be from heavy metal-contaminated or uncontaminated soils and gram-negative isolates tending to be from hydrocarbon-contaminated or cocontaminated soils. 相似文献
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Malcolm P. Francis 《Environmental Biology of Fishes》2006,75(3):295-306
Synopsis Halaelurus dawsoni has a restricted geographic range, occurring only in south-eastern New Zealand. It is primarily a demersal inhabitant of
the upper continental slope, plateaus, and ridges at 250–800 m depth. Halaelurus dawsoni is a voracious carnivore that feeds on a wide variety of crustaceans and fishes. Maximum recorded length is 418 mm total
length, and males and females grow to similar maximum lengths. Length at 50% maturity is about 340–350 mm for males and 330–360 mm
for females. The reproductive mode of H. dawsoni is single oviparity, with one leathery egg case being carried per uterus. It appears that most embryonic development occurs
after egg cases are deposited on the seabed. The reproductive mode of species of Halaelurus in the subgenus Halaelurus is multiple oviparity, whereas for those in the subgenus Bythaelurus it is single oviparity or aplacental viviparity. It has been suggested that single oviparity is a primitive reproductive
mode, and that aplacental viviparity evolved from it via the intermediate stage of multiple oviparity. However, the relationship
between reproductive mode and Halaelurus subgenus suggests that aplacental viviparity may have evolved directly from single oviparity in the subgenus Bythaelurus without passing through a multiple oviparous stage. 相似文献
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青海种子植物特有种及其生态地理分布 总被引:3,自引:0,他引:3
主要依据中国科学院西北高原生物研究所青藏高原生物标本馆内所存标本为基础,结合对相关资料的全面收集,整理出青海特有植物82种和37变种,隶属19科54属。文中除了分科、属列出每个种或种下类型在青海境内到县一级的产地、生境和海拔高度等以外,还列出了它们的原始文献和可供引证、查阅的标本号。是研究青海高原植物区系的组成、性质和特点以及发生和演变规律等方面问题的基础资料。 相似文献
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We studied the pattern of selenium accumulation inLycopersicum esculentumMill plants under conditions of selenium-enriched root and extraroot nutrition. Against the background of a general trend toward predominant selenium accumulation in the fruit skin, a higher level of accumulation of selenates (Se+6) than selenites (Se+4) was observed in the pulp. Application of Epin growth stimulant promoted selenium accumulation in the plants; its concentration in the pulp was comparable to the concentration after selenate application, while the level of the microelement accumulation in the fruit skin, leaves, and roots was 2.2, 2.4, and 1.4 times lower, respectively. Combined application of Epin and sodium selenate had virtually no effect on selenium accumulation in the pulp but increased the microelement content in the fruit skin and roots. Biological significance of the observed boundary effect of selenium as a manifestation of plant antioxidant protection is discussed. 相似文献
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Biology Bulletin - Awareness of the habitat needs of top predators is vital for viability of wildlife populations. During 2017–2018, 32 points of presence signs of the Persian leopard... 相似文献
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Panayiotis Trigas Spyros Tsiftsis Ioannis Tsiripidis Gregory Iatrou 《Folia Geobotanica》2012,47(4):421-439
An inventory of the endemic vascular plants of the Peloponnese (395 species and subspecies) has been created based on literature, herbarium and field data. Endemics?? distribution patterns, altitudinal distribution and habitat specificity were investigated. A rarity score for each endemic has been calculated based on its population size, geographic range and habitat specificity. The main mountainous areas of the Peloponnese are largely congruent to the hotspots of endemism. Altitudinal range and niche breadth of the endemics were positively correlated to their range size. The elevational gradient of the endemic species richness showed a hump-shaped pattern, in contrast to the monotonically decreasing pattern of total species richness. Endemic species were found to support boundary theory, while total species richness distribution followed the Rapoport??s elevational rule. The elevational distribution of the average rarity score and the average weighted threat of the endemics resulted in low values for mid-elevation intervals and increased values for low and high altitude areas, indicating that conservation efforts should focus on the two extremes of the elevational gradient. Area prioritization methods were applied using a rarity/complementarity based algorithm with two species weighting schemes. Their results were largely congruent confirming the significance of the main mountainous areas for the conservation of the endemics. Spatial overlap among selected grid cells using the rarity/complementarity analysis and Natura 2000 network was found to be low. Our results revealed the conservation importance of at least one new area located on Kythera Island. 相似文献
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翅茎草属(Pterygiella)是中国西南地区特有的半寄生植物.翅茎草属4种植物形态差异不显著,种的界定依据较模糊;此外,杜氏翅茎草2变种的划分依据也存在疑问.本研究选取了翅茎草属4种13个居群,通过数量性状的主成分分析和质量性状的非加权组平均法聚类分析;结合叶绿体4个片段(即atpB-rbcL、trnD-trnT、trnS-trnG和sbA-trnH)和核基因组的ITS片段研究,对该属下的种类划分作了重新界定.研究表明:翅茎草属应包括3种,即翅茎草、杜氏翅茎草和圆茎翅茎草;川滇翅茎木应作为圆茎翅茎草的变种.对杜氏翅茎草指定了后选模式,该种仅包括茎无毛的个体,而茎疏被毛的个体应归入翅茎草中.基于以上研究结果,本文提出了一个新的翅茎草属分种检索表,并做了分类修订. 相似文献
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Journal of Ichthyology - Etroplus suratensis (Bloch, 1790) is a highly exploited endemic cichlid fish species inhabiting the Cochin Estuary situated on the South-west coast of India. The study was... 相似文献
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The review summarizes data on the number, size and localization of serotoninergic neurons in cercariae of 16 trematode species, referring to 11 families. Presented diagrams show distribution patterns of serotoninergic neurons in cercariae of trematodes from different taxonomic, biological and morphological groups. Data analysis indicates that the number, disposition and size of these neurons vary in cercariae of different species. The data are discussed in relation with a functional significance of serotonin as a neurotransmitter in free-living larvae—trematode cercariae. 相似文献
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Sethuraman Nandini Thirunarayan M. A. Gopalakrishnan Ram Rudramurthy Shivaprakash Ramasubramanian V. Parameswaran Ashok 《Mycopathologia》2020,185(5):893-904
Mycopathologia - Talaromycosis is a disseminated disease caused by Talaromyces (Penicillium) marneffei, mainly seen in acquired immunodeficiency syndrome (AIDS) patients. Its distribution is... 相似文献