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1. We investigated the effects of riparian plant diversity (species number and identity) and temperature on microbially mediated leaf decomposition by assessing fungal biodiversity, fungal reproduction and leaf mass loss. 2. Leaves of five riparian plant species were first immersed in a stream to allow microbial colonisation and were then exposed, alone or in all possible combinations, at 16 or 24 °C in laboratory microcosms. 3. Fungal biodiversity was reduced by temperature but was not affected by litter diversity. Temperature altered fungal community composition with species of warmer climate, such as Lunulospora curvula, becoming dominant. 4. Fungal reproduction was affected by litter diversity, but not by temperature. Fungal reproduction in leaf mixtures did not differ or was lower than that expected from the weighted sum of fungal sporulation on individual leaf species. At the higher temperature, the negative effect of litter diversity on fungal reproduction decreased with the number of leaf species. 5. Leaf mass loss was affected by the identity of leaf mixtures (i.e. litter quality), but not by leaf species number. This was mainly explained by the negative correlation between leaf decomposition and initial lignin concentration of leaves. 6. At 24 °C, the negative effects of lignin on microbially mediated leaf decomposition diminished, suggesting that higher temperatures may weaken the effects of litter quality on plant litter decomposition in streams. 7. The reduction in the negative effects of lignin at the higher temperature resulted in an increased microbially mediated litter decomposition, which may favour invertebrate‐mediated litter decomposition leading to a depletion of litter stocks in streams.  相似文献   
33.
Korean barbel, Hemibarbus mylodon, is an endangered freshwater species endemic to Korea. In order to undertake a conservation program for this species in Korea, it is essential to evaluate its genetic diversity and population structure. For this purpose, we developed 10 polymorphic microsatellite markers and examined their allelic variation using a total of 60 wild individuals collected from three different localities. The number of alleles per locus ranged from three to 26. The expected and observed heterozygosities per locus ranged from 0.19 to 0.94 and from 0.20 to 0.98, respectively. Significant departures from Hardy–Weinberg equilibrium expectations occurred in four loci. These markers will be useful for the assessment of genetic diversity for this species.  相似文献   
34.
内源性NO在LPS和TNFα诱导离体兔肺动脉反应性变化中 …   总被引:2,自引:0,他引:2  
目的:探讨脂多糖(Lipopolysaccharide,LPS)和肿瘤坏死因子α(tumor necrosis factor alpha,TNFα)所致离体肺动脉反应性张力变化与肺动脉源性一氧化氮(nitric oxie,NO)的关系。方法:离体兔肺动脉环用LPS+TNFα、LPS或深剂孵育2h和6h,检测肺动脉对乙酰胆碱(ACh)、硝普钠(SNP)和苯肾上腺素(PE)的累积剂量反应,以及一氧化氮  相似文献   
35.
The genetic structure and morphometric differentiation of mangrove crab Perisesarma guttatum populations were examined among shelf connected locations along a latitudinal gradient on the East African coast. Over 2200 specimens were sampled from 23 mangrove sites for geometric morphometrics analysis. Population genetic analyses of mitochondrial cytochrome c oxidase subunit I (COI) DNA sequences were used to evaluate connectivity among populations. A total of 73 haplotypes were detected, and almost no haplotypes were found in common between two highly supported phylogeographic clades: southern Mozambique (Inhaca Island and Maputo Bay) and a northern clade that included north Mozambique, Tanzania and Kenya. These two clades were identified based on the species' populations pairwise genetic differentiation and geographical location. ΦST values were considerably high between the two clades, indicating the presence of significant population genetic structure between Kenya and South Mozambique. However, each clade was composed of genetically similar populations along the latitudinal gradient, and no significant population structure was found within each clade because the Φst values were not significant. The morphometric analysis corroborated the division into two clades (i.e. Inhaca Island/Maputo Bay and northern populations) and also detected less shape variation among populations that were few kilometres apart. The significant spatial genetic structuring between the southern and the northern populations of P. guttatum along the geographic gradient under study, combined with morphological differences, suggests that these populations may be considered as cryptic species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 28–46.  相似文献   
36.
目的:回顾性分析呼吸机辅助呼吸救治危重呼吸衰竭患者气管插管方式对于救治成功率的影响。方法:我科收治的各种呼吸衰竭患者94例,回顾分析插管方式对于救治成功率、引发心跳骤停及其对心肺复苏效果的影响。结果:经纤维支气管镜经口气管插管(35例)与经直接喉镜经口(59例)引发心跳骤停有明显统计学差异(X^2=11.5,v=1,t〈0.001)。经直接喉镜经口气管插管在术前用药与否对引发心跳骤停并无统计学意义,但是对于引发心跳骤停后心肺复苏成功率确有明显统计学意义。结论:经纤维支气管镜气管插管具有较高的安全性,在经直接喉镜气管插管是选择镇静药或浅麻醉药物应慎重,尽力避免心跳骤停和心肺复苏失败。  相似文献   
37.
The population decline of the Lesser Kestrel Falco naumanni has been the subject of studies across its Western Palaearctic breeding range, but little is known about its use of pre‐migratory areas or African wintering quarters. We used geolocators to describe the temporal and spatial patterns of Portuguese Lesser Kestrel migration and wintering behaviour. Data on the complete migration were obtained from four individuals and another three provided further information. Prior to southward migration, Lesser Kestrels showed two different behaviours: northward‐orientated movements to Spain and movements in the proximity of the breeding area. Autumn migration took place mostly in late September; spring departures occurred mainly in the first half of February. Wintering grounds included Senegal, Mauritania and Mali, with individuals overlapping considerably in Senegal. Movements registered within the wintering grounds suggest itinerant behaviour in relation to local flushes of prey. During spring migration, birds crossed the Sahara Desert through Mauritania, Western Sahara and Morocco before passing over the Mediterranean to reach Portugal. Autumn migration lasted 4.8 ± 1.1 days, and spring migration lasted 4.1 ± 0.3 days. The mean daily flight range varied between approximately 300 and 850 km for an entire journey of around 2500 km. Effective protection of roosting sites in both pre‐migratory and wintering areas and maintaining grasshopper populations in Sahelian wintering quarters appear crucial in preserving this threatened migratory raptor across its African–Eurasian flyway. There was no evidence of any deleterious effects of fitting birds with loggers.  相似文献   
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