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1.
All of the 1070 strains of Salmonella weltevreden tested were lysogenic, temperate phage being demonstrable in 83.9% of the strains in broth culture, 6.4% in mixed culture and the remaining 9.7% after induction by UV-irradiation and MC treatment. A phage-typing scheme for Salmonella weltevreden based on the host range of temperate phages was developed. The strains could be classified into eight groups by means of the host range of their temperate phages on six indicator strains and a ninth group, the symbiotic phages of which failed to lyse any of the indicator strains.  相似文献   

2.
A phage-typing system ofSalmonella bareilly based on lysogeny is presented. In the present study which comprised 378 strains, fifteen different phage types named ‘a’ through ‘o’ were established. With this system 70.3% of the strains could be typed by using five indicator strains.  相似文献   

3.
Phage-typing ofSalmonella panama according to the method of Craigie and Yen   总被引:2,自引:0,他引:2  
A phage-typing scheme forSalmonella panama has been established. This was done according to the method of Craigie and Yen by means of phage preparations which are all derived from a single phage. So far, eight phage types and a restgroup Z could be demonstrated by means of phage 47 and seven adaptations derived from it.  相似文献   

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5.
基于39个地理分布信息和19个生物气候因子,利用BIOCLIM生态位模型对紫玉兰(Yulania liliiflora(Desr.) D. L. Fu)潜在适生区进行预测。结果显示,紫玉兰自然分布于云南、四川、贵州、湖北、甘肃、重庆、福建等地海拔300~1600 m的中低山区。当前气候条件下,贵州苗岭是其主要适生区;随着全球气候变暖(CO2浓度倍增情况下),紫玉兰的适生区有向高海拔地区收缩的趋势,而在分布区的东北界,其潜在分布范围将扩散至湖南中部和浙江东部地区。影响紫玉兰地理分布格局的重要因素是水热条件的综合效应。ROC曲线检验的AUC值(0.998)表明,采用BIOCLIM模型对紫玉兰潜在分布区的预测结果准确性较高。本研究在气候变暖的大环境下分析紫玉兰的适生性,可为紫玉兰种质资源的保护利用提供依据。  相似文献   

6.
Aim We explored the effects of prevalence, latitudinal range and spatial autocorrelation of species distribution patterns on the accuracy of bioclimate envelope models of butterflies. Location Finland, northern Europe. Methods The data of a national butterfly atlas survey (NAFI) carried out in 1991–2003 with a resolution of 10 × 10 km were used in the analyses. Generalized additive models (GAM) were constructed, for each of 98 species, to estimate the probability of occurrence as a function of climate variables. Model performance was measured using the area under the curve (AUC) of a receiver operating characteristic (ROC) plot. Observed differences in modelling accuracy among species were related to the species’ geographical attributes using multivariate GAM. Results Accuracies of the climate–butterfly models varied from low to very high (AUC values 0.59–0.99), with a mean of 0.79. The modelling performance was related negatively to the latitudinal range and prevalence, and positively to the spatial autocorrelation of the species distribution. These three factors accounted for 75.2% of the variation in the modelling accuracy. Species at the margin of their range or with low prevalence were better predicted than widespread species, and species with clumped distributions better than scattered dispersed species. Main conclusions The results from this study indicate that species’ geographical attributes highly influence the behaviour and uncertainty of species–climate models, which should be taken into account in biogeographical modelling studies and assessments of climate change impacts.  相似文献   

7.
The incidence of pseudocholinesterase (PCHE equals E.C. 3.1.1.8) variants in samples of 8 different population (total of 2218 individuals) is reported. Together with previously mentioned data from the literature, a general survey on the geographical distribution of PCHE isoenzymes is given. Possible reasons for present-day heterogeneity of their distribution are also discussed. Concerning the incidence of the C5 variant, it is pointed out that the validity of applying population genetic models depends upon the accuracy of the genetic basis.  相似文献   

8.
A bibliography is given for the genus Marenzelleria. All together, 236 publications were found dealing with M. viridis, M. wireni and M. jonesi and their synonyms. The contents of the publications are briefly reviewed in tabular form identifying the nomenclature used, the geographical distribution and the topic of the paper in each case.  相似文献   

9.
韩冰  王艳芳  杨劼  苏婧 《生态学杂志》2008,27(3):349-354
以分布于内蒙古的草甸草原(森林草原)、典型草原、荒漠草原上的7种针茅属植物为材料,利用聚合酶链反应-单链构象多态性(PCR-SSCP)方法,分析了水孔蛋白基因的外显子1和内含子1的遗传多态性.结果表明:外显子1有AA、BB和CC 3种基因型,内含子1有DD、EE、FF和GG 4种基因型;种间存在基因多态性,种内没有多态性,所有种均表现出遗传的单态性和100%的纯合度.从基因型地理分布看,AA基因型在草甸草原、森林草原、典型草原及荒漠草原区的针茅种上均有分布,BB、CC基因型只分布在荒漠草原区的针茅中;DD基因型分布于草甸草原、森林草原及典型草原区的针茅属植物中,荒漠草原区分布有EE、FF、GG等3种基因型.荒漠草原区的植物是旱生程度最强的一类草原群落,该区的3种针茅具有丰富的遗传多态性.  相似文献   

10.
Kiwifruit (Actinidia ssp.) is an economically and nutritionally important fruit crop with a remarkably high vitamin C content. Shaanxi Province, China, has the world's largest production base for kiwifruit; hence, it is necessary to accurately assess the potential geographic distribution of kiwifruit in this area for planting planning and government management. To perform this analysis, we selected three categories of environmental indices (climate, soil, and topographical) for a total of 18 ecological suitability assessment indices. Based on fuzzy mathematic theory, we built 18 membership functions to show the quantitative relationship between kiwifruit yield and these 18 assessment indices. Furthermore, an assessment model of kiwifruit suitability for cultivation was constructed using a combination of the weighted average method and GIS spatial analysis of the present land-use map of Shaanxi. The results show that 5860.1 km2 (14.0%) of arable land and orchard can be demarcated as highly suitable for kiwifruit cultivation, 7868.9 km2 (18.7%) suitable for rapeseed cultivation; 11,392.1 km2 (27.1%) marginally suitable for rapeseed cultivation; and 16,892.5 km2 (40.2%) as unsuitable for kiwifruit cultivation in this province. We provide a useful assessment system for ecological zoning of kiwifruit suitability and identify the highly suitable planting area of kiwifruit in Shaanxi Province. south Shannan and south Guanzhong. These results provide a reference tool for distribution rationalization and resource optimization of kiwifruit-planting areas.  相似文献   

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The taxonomy and geographical distribution ofEchinodorus grandiflorus (Cham. etSchlecht.)Mich. (Alismataceae) are stated. Former authors also included plants from southern Brazil and Argentina in this species, without the typical pellucid points on the blades; these belong to different species or to hybrids. The author further describes the hybrids ofE. grandiflorus with some other species of the same genus and two varieties.  相似文献   

13.
Background: Phenotypic variations have been observed in populations of west Cuban Pinguicula species. Such populations occur in patches under different ecological conditions associated with specialised habitats and separated by geographical and ecological barriers, which can lead to morphological differentiation.

Aims: To analyse morphological diversity among species and populations of Cuban Pinguicula; and to test if morphological variability is associated with geographical distribution and distance between populations.

Methods: We sampled a total of eight populations of P. albida, P. cubensis and P. filifolia and tested for morphometric differences among them by Principal Component Analysis (PCA) and analysis of variance (ANOVA) based on 31 quantitative traits. We also assessed the geographical isolation with respect to morphological distance.

Results: The studied species showed high morphological variability at both species and population level. Reproductive characteristics appeared to be more promissory than vegetative ones in distinguishing geographical groups since they clearly defined populations; nevertheless a strong component of individual variation was observed. According to the distance analysis, such morphological variations were correlated with fragmented populations and isolation and allowed the differentiation of two morphotypes of P. albida and two of P. filifolia.

Conclusions: We conclude that high phenotypic variation of the analysed species is related to geographical and ecological isolation which have led to the differentiation of morphotypes within species.  相似文献   


14.
15.
M. de Ridder 《Hydrobiologia》1981,85(3):209-225
In the course of investigations on the systematics and zoogeography of rotifers, the author found that 48% of all taxa treated showed a limited distribution (most were periphytic or benthic periphytic species from shallow waters). The following species were limited to the Palaearctic Region: Marine: Synchaeta triophtalma Lauterborn, S. vorax Rousselet, and S. curvata Lie-Pettersen. Brackish water: Colurella dicentra (Gosse), C. halophila Wulfert, and C. unicauda Eriksen. Among Holarctic species, Notholca psammarina Buchholz & Rühmann and the two semi-species N.(striata) bipalium (O. F. Müller) and N(striata) striata (O. F. Müller) are discussed. A series of warm-stenothermic species were found to be pantropical: Lecane leontina Turner, L. monostyla (Daday), L. harringi (Ahlstrom), Lepadella latusinus (Hilgendorf), Trichocerca chattoni (de Beauchamp), and Platyias leloupi Gillard, while Lecane plesia Myers and L. punctata (Murray) seemed to be confined to the Neotropical Region. The data collected also suggest that:
  1. i) Keratella wirketissi Kutikova, K. kamtchatica Kutikova, K. cruciformis (Thompson), and K. eichwaldi (Levander) might be good species.
  2. ii) Brachionus forficula Wierzejski, an Old World species, is a geographical vicariant of both B. havanaensis Rousselet and B. trahea Murray from the New World.
  3. iii) Cases of ecological vicariance are found in Testidinella elliptica (Ehrb.) and T. clypeata (O. F. Müller) from fresh and brackish water respectively; Keratella cruciformis (Thompson) and K. eichwaldi (Levander) from the sea and brackish water respectively; Keratella quadrata (O. F. Müller), K. valga (Ehrb.), and K. tropica (Apstein), dominant in arctic to cold-moderate, in warm-temperate, and in subtropical-tropical climates respectively.
Some rotifer species are presently in expansion: the cases of K. tropica and of Brachionus falcatus Zacharias in Europe are analysed. A related case is that of man-made faunas: the presence of Brachionus havanaensis in Sangchrist Lake, Ill., USA, and the Rotifer fauna of the River Loire (France) are discussed.  相似文献   

16.
Summary Following the discovery by Daiger et al. (1975) that the Gc proteins of human plasma act as the carriers of vitamin D, the authors have plotted on a world map all available data on the frequency of the allele Gc 2, and compared the distribution with that of sunlight. With some exceptions high frequencies of Gc 2 correspond to low levels of sunlight and vice versa. Similar comparisons within Ireland show no such relation. The results are discussed in relation to natural selection and the incidence of rickets, due to vitamin D deficiency.  相似文献   

17.
臭氧是氧气的同素异形体,在常温条件下它是一种有特殊臭味的淡蓝色气体。臭氧现已成为我国主要的一种环境污染物。臭氧的分布存在着明显的时间特异性和地区特异性,与气象条件、污染物的输送与扩散以及局地光化学反应强度等因素有着重要的关系。同时在人群流行病学和动物实验中发现了臭氧可以提高慢性阻塞性肺疾病、哮喘等呼吸系统疾病的发病率和病死率,同时提示了老年人、有呼吸系统疾病病史的人群和儿童都是易受臭氧影响的高危人群。国内外学者也对臭氧对机体损伤的机制进行了研究,主要集中在臭氧的致炎作用、氧化应激作用、造成机体气道高反应性和对细胞DNA的损伤等方面。本文主要就国内外对臭氧在时空分布、对机体呼吸系统影响和臭氧造成机体损伤的机制这3方面作一简要综述。  相似文献   

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基于MaxEnt模型的朱红毛斑蛾在我国的潜在地理分布   总被引:1,自引:0,他引:1       下载免费PDF全文
朱红毛斑蛾Phauda flammans Walker是榕树上的一种重要的寡食性食叶害虫,近年在我国南方部分省区逐步扩散,并在局部地区暴发成灾。本研究根据朱红毛斑蛾在全球的已知地理分布点,结合环境气候数据,运用MaxEnt模型对朱红毛斑蛾在当前和未来的潜在地理分布进行了预测。结果显示,朱红毛斑蛾潜在地理分布区主要在我国南部,占全国总面积的18.96%,其中高、中、低度适生区分别占全国总面积的3.89%、4.9%和10.17%。高度适生区主要分布于海南、广西、广东、香港、澳门、福建南部、台湾西北部、云南局部、江西局部和四川局部等地区。2050年RCP 8.5场景下,潜在地理分布区面积扩大至全国总面积的21.48%,适生程度也有所增加。因此,适生范围内的地区应开展监测预警工作,并有重点的实施预防控制措施,保护城市景观和生态安全。  相似文献   

20.
Plant distribution borders are key features to characterise the ecological niche of a species and to monitor effects of climate change. Here we focus on an evergreen small tree, Ilex aquifolium, which reaches its north-eastern range edge in Denmark. Our main objectives are to describe and to model the current distribution of the species, to identify the most important climatic and land use factors which shape this distribution pattern, and to analyse the species' habitat requirements. For this purpose we used data from a national mapping project, complemented by information from forest owners. The distribution and abundance of I. aquifolium in Denmark have markedly changed during the past 40 years. It is now found in almost all districts, although the centres of abundance still coincide with the historical records. Our model shows lower habitat suitability for the species in northern and eastern districts, where winters are more severe and spring precipitation is lower. To a lesser extent, land use influences I. aquifolium occurrence, but it is more common in areas with a high proportion of forests and/or urban sites. The analysis of habitat requirements supports these results, since I. aquifolium occurs mainly as a forest species in deciduous stands, on relatively nutrient-rich moist soils, and under moderately high light conditions. However, some records may be the product of seed dispersal from planted individuals nearby. The results suggest that the range edge of the species has moved at least 100 km east within half a century. Since I.aquifolium is sensitive to winter frost, this change in distribution may be due to increasingly mild winter temperatures.  相似文献   

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