In search for the ecological and toxicological relevance of sediment re-mobilisation and transport during flood events   总被引：3，自引：2，他引：1  

Jan Wölz  Catrina Cofalla  Sebastian Hudjetz  Sebastian Roger  Markus Brinkmann  Burkhard Schmidt  Andreas Schäffer  Ulrike Kammann  Gottfried Lennartz  Markus Hecker  Holger Schüttrumpf  Henner Hollert 《Journal of Soils and Sediments》2009,9(1):1-5

In response to increasing concerns about the potential toxicological impacts of (extreme) flood events, scientists from several disciplines have joined to form the interdisciplinary research project named FLOODSEARCH. FLOODSEARCH is one of the recent Pathfinder Projects supported by the German Excellence Initiative via the Exploratory Research Space at RWTH Aachen (ERS). FLOODSEARCH aims to combine methodologies of hydraulic engineering and ecotoxicology in a new interdisciplinary approach to assess the risks associated with the re-mobilisation of particulate bound contaminants often observed after severe flood events. Impacts of extreme flood events and aspects of re-mobilisation of sediment-bound toxic compounds will be characterised and evaluated in controlled experiments fusing flood simulation technologies with biological effects assessment. The overall goal is to establish a novel and more realistic approach towards flood event testing that can be applied to a number of different questions and species. Specifically, model aquatic species such as rainbow trout (Onchorhynchus mykiss) will be exposed to particle-bound contaminants in flood-like conditions in a specifically designed annular flume that permits monitoring of both physical/chemical and biological parameter. Ultimately, this approach will assist to further our understanding of the potential biological risks associated with increasingly frequent extreme flood events, e.g., as a consequence of climate change, by bridging the gap between the physical (re-)mobilisation of contaminants and resulting toxicological impacts on aquatic organisms. Thus, it is the objective of the project to derive relationships between the hydrodynamic parameters such as velocities and turbulences, the parameters associated to sediment transport such as sediment concentration and grain sizes and the biological parameters.  相似文献   

Horse breeding: genetic tests for the coat colors chestnut,bay and black. Results from a preliminary study in the Swiss Freiberger horse breed     

Henner J  Poncet PA  Aebi L  Hagger C  Stranzinger G  Rieder S 《Schweizer Archiv für Tierheilkunde》2002,144(8):405-412

Coat color played an important role during domestication and formation of breeds. Livestock breeders often had special preferences for particular color phenotypes because they believed them to be associated with performance or fitness traits. Socio-cultural reasons might have had an influence on color selection as well. Recently genetic tests on DNA level got available to genotype in any individual horse for basic horse coat colors (chestnut, bay, black). In particular, hidden carriers of the recessive chestnut and black allele are recognizable with these tests. A sample of 162 Franches-Montagnes horses from Switzerland was genotyped for the alleles for chestnut and black. The analysis of allele frequencies revealed a high prevalence of the chestnut allele and a low frequency of the black allele in this population. Rare colors are in demand on the market. The statistical analysis of 1369 offspring from five stallions indicate, that darker shades of basic color phenotypes (dark chestnut, dark bay) follow a recessive mode of inheritance in the Franches-Montagnes horse breed.  相似文献   

Genetic diversity studies in farm animals – a survey     

R. Baumung  H. Simianer  I. Hoffmann 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2004,121(6):361-373

During the past decade a large number of genetic diversity studies in domestic livestock based on microsatellite loci was carried out all over the world. A survey among research groups reveals that in 50% of 87 projects more than eight breeds are investigated. Breeds are chosen mainly because of their long history of isolation, unique phenotypic qualities or an evolution within a unique environment. In half of the projects the average planned sample size per breed is higher than 50. Small ruminants are investigated in the majority of projects. The most preferred type of sample is blood and the most preferred markers are microsatellite loci. To combine results from different diversity studies, the adherence to recommendations, e.g. which loci to genotype or required sample sizes per breed, is necessary. The so called International Society for Animal Genetics (ISAG)/FAO recommendations, which were developed for that purpose, are well known, but the use of recommended microsatellite loci varies between species. The highest acceptance was found in pig, and the lowest in chicken.  相似文献   

Volume index     

Georg Erhardt  Ignacy Misztal  Lawrence R Schaeffer  Henner Simianer  Julius Van Der Werf 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2004,121(6):no-no

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Using expected allele number as objective function to design between and within breed conservation of farm animal biodiversity   总被引：4，自引：0，他引：4  

H. Simianer 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2005,122(3):177-187

Conservation of genetic diversity in farm animal species can be achieved by preventing extinction of breeds and by reducing genetic drift within breeds. It is suggested to use the expected number of alleles segregating in the species after a given time period as objective function in the design of conservation strategies. A formal approach is presented to predict this quantity based on marker information, accounting for extinction probability of breeds and effective population size within breeds as the major component of genetic drift. Based on this model, relative efficiency of different strategies of diversity conservation can be quantified. Formulas are given to derive the marginal expected number of alleles with respect to genetic drift within population and extinction probability, respectively. The suggested approach is illustrated with an example of 13 European cattle breeds. With the assumed parameters, drift is shown to be the major force leading to loss of alleles, and different breeds are prioritized for activities to reduce risk of extinction and for measures to reduce genetic drift, respectively. Although different aspects of the model need to be further refined, the suggested methodology provides a general and flexible tool to derive the optimum conservation strategy in various scenarios.  相似文献   

Epistatic kinship a new measure of genetic diversity for short-term phylogenetic structures – theoretical investigations     

C. Flury  M. Tietze  & H. Simianer 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2006,123(3):159-171

The epistatic kinship describes the probability that chromosomal segments of length x in Morgan are identical by descent. It is an extension from the single locus consideration of the kinship coefficient to chromosomal segments. The parameter reflects the number of meioses separating individuals or populations. Hence it is suggested as a measure to quantify the genetic distance of subpopulations that have been separated only few generations ago. Algorithms for the epistatic kinship and the extension of the rules to set up the rectangular relationship matrix are presented. The properties of the epistatic kinship based on pedigree information were investigated theoretically. Pedigree data are often missing for small livestock populations. Therefore, an approach to estimate epistatic kinship based on molecular marker data are suggested. For the epistatic kinship based on marker information haplotypes are relevant. An easy and fast method that derives haplotypes and the respective frequencies without pedigree information was derived based on sampled full‐sib pairs. Different parameters of the sampling scheme were tested in a simulation study. The power of the method decreases with increasing segment length and with increasing number of segments genotyped. Further, it is shown that the efficiency of the approach is influenced by the number of animals genotyped and the polymorphism of the markers. It is discussed that the suggested method has a considerable potential to allow a phylogenetic differentiation between close populations, where small sample size can be balanced by the number, the length, and the degree of polymorphism of the chromosome segments considered.  相似文献   

Extension of the concept of kinship, relationship, and inbreeding to account for linked epistatic complexes     

Christine Flury  Helge Tubert  Henner Simianer 《Livestock Science》2006,103(1-2):131-140

Although epistatic effects are well defined and, in principle, can be exploited in quantitative-genetic selection theory, they often are ignored or even treated as nuisance parameters in practical applications. Traditionally, epistasis is considered as an interaction between genes at unspecified loci. Inspired by the observation that functional genes are often organised in physical clusters, we developed a model to combine additive effects and additive × additive interactions in linked gene clusters of defined length. Malécot's kinship concept is extended to identity by descent probabilities for chromosome segments of a given length in Morgan units, called epistatic kinship. Using the analogy of Malécot's kinship and Wright's relationship and inbreeding coefficients, epistatic relationship coefficients and epistatic inbreeding coefficients are defined. Simple rules are given to set up the epistatic numerator relationship matrix and its inverse directly from a pedigree list. The well-known single locus parameters and algorithms to set up the additive numerator relationship matrix and its inverse are a special case of the suggested methodology for a chromosome segment length of null Morgan. A proof of concept of the suggested method is given with a small simulation study. Assuming additive, linked epistatic and residual variance components, 100 replicated data sets for 1000 individuals are generated. From these data, residual maximum likelihood estimates of the variance components and of the chromosome segment size are obtained. Potential applications of the methodology are discussed. Given that a substantial variance component is attributed to this effect, the expected genetic gain can be increased on the short term if selection is on additive and epistatic effects, the latter comprising additive × additive interaction effect of loci in linkage disequilibrium. This extra benefit, however, will diminish through crossing over in subsequent generations. Despite some practical problems yet to be solved, the suggested model and algorithms open new perspectives to use a higher proportion of genetic variability in selection and breeding.  相似文献   

Acknowledgements to referees     

Asko Mäki-Tanila  Georg Erhardt  Ignacy Misztal  Larry Schaeffer  Henner Simianer  Julius van der Werf 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2007,124(6):390-390

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Variation in village chicken production systems among agro-ecological zones of Zimbabwe   总被引：1，自引：1，他引：0  

Muchadeyi FC  Wollny CB  Eding H  Weigend S  Makuza SM  Simianer H 《Tropical animal health and production》2007,39(6):453-461

The degree to which village chickens are integrated in the smallholder farming systems differs depending on the socio-economic, cultural and biological factors within each system. The objective of this study was to characterise the village chicken farming systems and identify possible threats to, and opportunities for, local chickens in the agro-ecological zones of Zimbabwe. A pre-tested questionnaire was administered to households randomly selected from five districts, Risitu (n = 97), Hurungwe (n = 56), Gutu (n = 77), Gokwe-South (n = 104) and Beitbridge (n = 37) in eco-zones I–V, respectively. Age of head of household averaged 47 years (SD = 14.3). Land holdings per household averaged 4.82 ha (SD = 3.6). Overall, 17.7 percent of the households ranked livestock as the major source of income compared to 70.8 percent who ranked crops as the main contributor. Chicken flock size averaged 16.7 (SD = 12.4), and the highest flock sizes were observed in eco-zones I and IV. Households owning cattle, goats and other livestock assigned less important ranks to chickens. Chickens were used mainly for the provision of meat and eggs whilst the use of chicken feathers and investment were uncommon practises. Results indicate that more support is necessary for village chickens in the non-cropping regions of the country.  相似文献   

    

Georg Henner 《Forstwissenschaftliches Centralblatt》1927,49(20):742-743

Ohne Zusammenfassung  相似文献