@article{SchneiderDobrindtMiddendorfetal.2011, author = {Schneider, Gy{\"o}rgy and Dobrindt, Ulrich and Middendorf, Barbara and Hochhut, Bianca and Szij{\´a}rt{\´o}, Valeria and Em{\´o}dy, Levente and Hacker, J{\"o}rg}, title = {Mobilisation and remobilisation of a large archetypal pathogenicity island of uropathogenic \(Escherichia\) \(coli\) \(in\) \(vitro\) support the role of conjugation for horizontal transfer of genomic islands}, series = {BMC Microbiology}, volume = {11}, journal = {BMC Microbiology}, doi = {10.1186/1471-2180-11-210}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-140975}, pages = {210}, year = {2011}, abstract = {Background: A substantial amount of data has been accumulated supporting the important role of genomic islands (GEIs) - including pathogenicity islands (PAIs) - in bacterial genome plasticity and the evolution of bacterial pathogens. Their instability and the high level sequence similarity of different (partial) islands suggest an exchange of PAIs between strains of the same or even different bacterial species by horizontal gene transfer (HGT). Transfer events of archetypal large genomic islands of enterobacteria which often lack genes required for mobilisation or transfer have been rarely investigated so far. Results: To study mobilisation of such large genomic regions in prototypic uropathogenic E. coli (UPEC) strain 536, PAI II(536) was supplemented with the mob(RP4) region, an origin of replication (oriV(R6K)), an origin of transfer (oriT(RP4)) and a chloramphenicol resistance selection marker. In the presence of helper plasmid RP4, conjugative transfer of the 107-kb PAI II(536) construct occured from strain 536 into an E. coli K-12 recipient. In transconjugants, PAI II(536) existed either as a cytoplasmic circular intermediate (CI) or integrated site-specifically into the recipient's chromosome at the leuX tRNA gene. This locus is the chromosomal integration site of PAI II(536) in UPEC strain 536. From the E. coli K-12 recipient, the chromosomal PAI II(536) construct as well as the CIs could be successfully remobilised and inserted into leuX in a PAI II(536) deletion mutant of E. coli 536. Conclusions: Our results corroborate that mobilisation and conjugal transfer may contribute to evolution of bacterial pathogens through horizontal transfer of large chromosomal regions such as PAIs. Stabilisation of these mobile genetic elements in the bacterial chromosome result from selective loss of mobilisation and transfer functions of genomic islands.}, language = {en} } @article{ArhondakisFrousiosIliopoulosetal.2011, author = {Arhondakis, Stilianos and Frousios, Kimon and Iliopoulos, Costas S. and Pissis, Solon P. and Tischler, German and Kossida, Sophia}, title = {Transcriptome map of mouse isochores}, series = {BMC Genomics}, volume = {12}, journal = {BMC Genomics}, number = {511}, doi = {10.1186/1471-2164-12-511}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-142773}, pages = {1-9}, year = {2011}, abstract = {Background: The availability of fully sequenced genomes and the implementation of transcriptome technologies have increased the studies investigating the expression profiles for a variety of tissues, conditions, and species. In this study, using RNA-seq data for three distinct tissues (brain, liver, and muscle), we investigate how base composition affects mammalian gene expression, an issue of prime practical and evolutionary interest. Results: We present the transcriptome map of the mouse isochores (DNA segments with a fairly homogeneous base composition) for the three different tissues and the effects of isochores' base composition on their expression activity. Our analyses also cover the relations between the genes' expression activity and their localization in the isochore families. Conclusions: This study is the first where next-generation sequencing data are used to associate the effects of both genomic and genic compositional properties to their corresponding expression activity. Our findings confirm previous results, and further support the existence of a relationship between isochores and gene expression. This relationship corroborates that isochores are primarily a product of evolutionary adaptation rather than a simple by-product of neutral evolutionary processes.}, language = {en} } @article{DrenckhahnBaumgartnerZonneveld2017, author = {Drenckhahn, Detlev and Baumgartner, Werner and Zonneveld, Ben}, title = {Different genome sizes of Western and Eastern Ficaria verna lineages shed light on steps of Ficaria evolution}, series = {Forum Geobotanicum}, volume = {7}, journal = {Forum Geobotanicum}, issn = {1867-9315}, doi = {10.3264/FG.2017.1122}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-155061}, pages = {27-33}, year = {2017}, abstract = {The genus Ficaria is now considered to comprize eight Eurasian species. The most widespread European species is the tetraploid F. verna Huds. The present study provides evidence for the existence of two main lineages of F. verna that differ considerably in their genomic size by about 3 pg. A Western F. verna lineage west of river Rhine displays a mean genome size (2C-value) of 34.2 pg and is almost precisely codistributed with the diploid F. ambigua Boreau (20 pg) north of the Mediterranean. The remaining part of Europe appears to be occupied by the Eastern F. verna lineage solely (mean genome size of 31.3 pg) which codistributes in South-Eastern Europe with the diploid F. calthifolia Rchb. (15 pg). There is little overlap at the boundary of Western and Eastern F. verna lineages with the occurrence of a separate intermediate group in the Netherlands (mean genomic size of 33.2 pg) that appears to result from hybridization of both lineages. On the basis of these observations and further considerations we propose development of F. ambigua and F. calthifolia south of the Alps with subsequent divergence to populate their current Western and Eastern European ranges, respectively. The Western F. verna lineage is proposed to originate from autotetraploidization of F. ambigua (precursor) with moderate genomic downsizing and the Eastern F. verna lineage from auto¬tetraploidization of F. calthifolia (precursor).}, subject = {Durchflusscytometrie}, language = {en} } @article{GrosHovestadtPoethke2006, author = {Gros, Andreas and Hovestadt, Thomas and Poethke, Hans Joachim}, title = {Evolution of local adaptions in dispersal strategies}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-45406}, year = {2006}, abstract = {The optimal probability and distance of dispersal largely depend on the risk to end up in unsuitable habitat. This risk is highest close to the habitat's edge and consequently, optimal dispersal probability and distance should decline towards the habitat's border. This selection should lead to the emergence of spatial gradients in dispersal strategies. However, gene flow caused by dispersal itself is counteracting local adaptation. Using an individual based model we investigate the evolution of local adaptations of dispersal probability and distance within a single, circular, habitat patch. We compare evolved dispersal probabilities and distances for six different dispersal kernels (two negative exponential kernels, two skewed kernels, nearest neighbour dispersal and global dispersal) in patches of different size. For all kernels a positive correlation between patch size and dispersal probability emerges. However, a minimum patch size is necessary to allow for local adaptation of dispersal strategies within patches. Beyond this minimum patch area the difference in mean dispersal distance between center and edge increases linearly with patch radius, but the intensity of local adaptation depends on the dispersal kernel. Except for global and nearest neighbour dispersal, the evolved spatial pattern are qualitatively similar for both, mean dispersal probability and distance. We conclude, that inspite of the gene-flow originating from dispersal local adaptation of dispersal strategies is possible if a habitat is of sufficient size. This presumably holds for any realistic type of dispersal kernel.}, subject = {Ausbreitung}, language = {en} } @article{MitesserWeisselStrohmetal.2007, author = {Mitesser, Oliver and Weissel, Norbert and Strohm, Erhard and Poethke, Hans-Joachim}, title = {Adaptive dynamic resource allocation in annual eusocial insects: Environmental variation will not necessarily promote graded control}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-45412}, year = {2007}, abstract = {Background: According to the classical model of Macevicz and Oster, annual eusocial insects should show a clear dichotomous "bang-bang" strategy of resource allocation; colony fitness is maximised when a period of pure colony growth (exclusive production of workers) is followed by a single reproductive period characterised by the exclusive production of sexuals. However, in several species graded investment strategies with a simultaneous production of workers and sexuals have been observed. Such deviations from the "bang-bang" strategy are usually interpreted as an adaptive (bet-hedging) response to environmental fluctuations such as variation in season length or food availability. To generate predictions about the optimal investment pattern of insect colonies in fluctuating environments, we slightly modified Macevicz and Oster's classical model of annual colony dynamics and used a dynamic programming approach nested into a recurrence procedure for the solution of the stochastic optimal control problem. Results: 1) The optimal switching time between pure colony growth and the exclusive production of sexuals decreases with increasing environmental variance. 2) Yet, for reasonable levels of environmental fluctuations no deviation from the typical bang-bang strategy is predicted. 3) Model calculations for the halictid bee Lasioglossum malachurum reveal that bet-hedging is not likely to be the reason for the graded allocation into sexuals versus workers observed in this species. 4) When environmental variance reaches a critical level our model predicts an abrupt change from dichotomous behaviour to graded allocation strategies, but the transition between colony growth and production of sexuals is not necessarily monotonic. Both, the critical level of environmental variance as well as the characteristic pattern of resource allocation strongly depend on the type of function used to describe environmental fluctuations. Conclusion: Up to now bet-hedging as an evolutionary response to variation in season length has been the main argument to explain field observations of graded resource allocation in annual eusocial insect species. However, our model shows that the effect of moderate fluctuations of environmental conditions does not select for deviation from the classical bang-bang strategy and that the evolution of graded allocation strategies can be triggered only by extreme fluctuations. Detailed quantitative observations on resource allocation in eusocial insects are needed to analyse the relevance of alternative explanations, e.g. logistic colony growth or reproductive conflict between queen and workers, for the evolution of graded allocation strategies.}, subject = {Insekten}, language = {en} } @article{PoethkeHovestadtMitesser2003, author = {Poethke, Hans-Joachim and Hovestadt, Thomas and Mitesser, Oliver}, title = {Local extinction and the evolution of dispersal rates: Causes and correlations}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-47718}, year = {2003}, abstract = {We present the results of individual-based simulation experiments on the evolution of dispersal rates of organisms living in metapopulations. We find conflicting results regarding the relationship between local extinction rate and evolutionarily stable (ES) dispersal rate depending on which principal mechanism causes extinction: if extinction is caused by environmental catastrophes eradicating local populations, we observe a positive correlation between extinction and ES dispersal rate; if extinction is a consequence of stochastic local dynamics and environmental fluctuations, the correlation becomes ambiguous; and in cases where extinction is caused by dispersal mortality, a negative correlation between local extinction rate and ES dispersal rate emerges. We conclude that extinction rate, which both affects and is affected by dispersal rates, is not an ideal predictor for optimal dispersal rates.}, subject = {Ausbreitung}, language = {en} } @article{HuebnerWissemann2004, author = {H{\"u}bner, Stefanie and Wissemann, Volker}, title = {Morphometrische Analysen zur Variabilit{\"a}t von Prunus spinosa L. - Populationen(Prunoideae, Rosaceae) im mittleren Saaletal, Th{\"u}ringen}, doi = {10.3264/FG.2004.1215}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-35207}, year = {2004}, abstract = {Prunus spinosa L. (Rosaceae) is one of the most widespread members of the genus Prunus in middle europe. Its morphological plasticity resulted in a number of described taxa at subspecific level. Since the early neolithic times, drupes of the plum family are recorded and exhibit already a remarkable diversity in size and form. Here we present a short historical account to the use of P. spinosa and an overview of the different taxonomic treatments. We examined distribution patterns in general and in particular in the central valley of the river Saale (Thuringia) with respect to ecological, edaphic and climatic factors. We assessed within 16 populations the variability of 22 metric and 10 qualitative morphological characters at 7 different locations. Population sites included forest-, way- and fieldsides, as well as lightish pine forests. Pollen fertility did not increase during the flowering period, all flowers were directly fully fertile from the beginning. In contrast, glucose content varied significantly depending of the status of fertilization. Epicuticular wax structure was without variation amongst the populations. P. spinosa leaves are covered with a smooth layer of slightly striated wax. Morphological characters were scored on 270 branches and 506 fruits. Most of the characters showed enormous variability among and within populations such as metrics of leaves, thorns and character states of flower morphology. The lowest variability among populations and therefore not dependend of modificatory factors was found in fruit characters. Since kernel morphology seems to be genetically rather than modificatory controlled, we applied the 3 taxonomical concepts of Werneck, K{\"u}hn and Scholz u. Scholz to identify evolutionary units at subspecific levels. However, population variability was still so high, that from our study here we can not support an infraspecific classification of Prunus spinosa L.}, subject = {Prunus}, language = {de} }