@article{MassieRyabovBlasiusetal.2013, author = {Massie, Thomas Michael and Ryabov, Alexei and Blasius, Bernd and Weithoff, Guntram and Gaedke, Ursula}, title = {Complex transient dynamics of stage-structured populations in response to environmental changes}, series = {The American naturalist : a bi-monthly journal devoted to the advancement and correlation of the biological sciences}, volume = {182}, journal = {The American naturalist : a bi-monthly journal devoted to the advancement and correlation of the biological sciences}, number = {1}, publisher = {Univ. of Chicago Press}, address = {Chicago}, issn = {0003-0147}, doi = {10.1086/670590}, pages = {103 -- 119}, year = {2013}, abstract = {Stage structures of populations can have a profound influence on their dynamics. However, not much is known about the transient dynamics that follow a disturbance in such systems. Here we combined chemostat experiments with dynamical modeling to study the response of the phytoplankton species Chlorella vulgaris to press perturbations. From an initially stable steady state, we altered either the concentration or dilution rate of a growth-limiting resource. This disturbance induced a complex transient response-characterized by the possible onset of oscillations-before population numbers relaxed to a new steady state. Thus, cell numbers could initially change in the opposite direction of the long-term change. We present quantitative indexes to characterize the transients and to show that the dynamic response is dependent on the degree of synchronization among life stages, which itself depends on the state of the population before perturbation. That is, we show how identical future steady states can be approached via different transients depending on the initial population structure. Our experimental results are supported by a size-structured model that accounts for interplay between cell-cycle and population-level processes and that includes resource-dependent variability in cell size. Our results should be relevant to other populations with a stage structure including organisms of higher order.}, language = {en} } @article{PavesiKetmaier2013, author = {Pavesi, Laura and Ketmaier, Valerio}, title = {Patterns of genetics structuring and levels of differentiation in supralittoral talitrid amphipods - an overview}, series = {Crustaceana : international journal of crustacean research}, volume = {86}, journal = {Crustaceana : international journal of crustacean research}, number = {7-8}, publisher = {Brill}, address = {Leiden}, issn = {0011-216X}, doi = {10.1163/15685403-00003212}, pages = {890 -- 907}, year = {2013}, abstract = {Talitrids are the only family within the order Amphipoda to have colonised supralittoral and terrestrial environments. They live in a variety of settings, from sandy to rocky and pebble beaches, to river and lake banks, and to leaf litter and caves. A common feature is the absence of a planktonic larval stage to facilitate passive dispersal over long-distances. However, some species have broad distributions. Genetic studies over the past 25 years have tried to explain this apparent contradiction by assessing patterns of species genetic structuring on different geographical scales. Here, we review the molecular studies available to date and focus on the population genetics of talitrids. Most of these studies considered populations in the Mediterranean area, but also along the Atlantic coast and in Canary Island caves. From this review, the group emerges as a potential model to understand processes of dispersal and divergence in non-highly-vagile supralittoral organisms. At the same time, studies on these issues are still too restricted geographically: a worldwide scale including different regions would provide us with a better perspective on these problems.}, language = {en} } @article{ReimThammRolkeetal.2013, author = {Reim, Tina and Thamm, Markus and Rolke, Daniel and Blenau, Wolfgang and Scheiner, Ricarda}, title = {Suitability of three common reference genes for quantitative real-time PCR in honey bees}, series = {Apidologie : a quality journal in bee science}, volume = {44}, journal = {Apidologie : a quality journal in bee science}, number = {3}, publisher = {Springer}, address = {Paris}, issn = {0044-8435}, doi = {10.1007/s13592-012-0184-3}, pages = {342 -- 350}, year = {2013}, abstract = {Honey bees are important model organisms for neurobiology, because they display a large array of behaviors. To link behavior with individual gene function, quantitative polymerase chain reaction is frequently used. Comparing gene expression of different individuals requires data normalization using adequate reference genes. These should ideally be expressed stably throughout lifetime. Unfortunately, this is frequently not the case. We studied how well three commonly used reference genes are suited for this purpose and measured gene expression in the brains of honey bees differing in age and social role. Although rpl32 is used most frequently, it only remains stable in expression between newly emerged bees, nurse-aged bees, and pollen foragers but shows a peak at the age of 12 days. The genes gapdh and ef1 alpha-f1, in contrast, are expressed stably in the brain throughout all age groups except newly emerged bees. According to stability software, gapdh was expressed most stably, followed by rpl32 and ef1 alpha-f1.}, language = {en} } @article{WeisseMoserScheffeletal.2013, author = {Weisse, Thomas and Moser, Michael and Scheffel, Ulrike and Stadler, Peter and Berendonk, Thomas U. and Weithoff, Guntram and Berger, Helmut}, title = {Systematics and species-specific response to pH of Oxytricha acidotolerans sp nov and Urosomoida sp (Ciliophora, Hypotricha) from acid mining lakes}, series = {European journal of protistology}, volume = {49}, journal = {European journal of protistology}, number = {2}, publisher = {Elsevier}, address = {Jena}, issn = {0932-4739}, doi = {10.1016/j.ejop.2012.08.001}, pages = {255 -- 271}, year = {2013}, abstract = {We investigated the morphology, phylogeny of the 18S rDNA, and pH response of Oxytricha acidotolerans sp. nov. and Urosomoida sp. (Ciliophora, Hypotricha) isolated from two chemically similar acid mining lakes (pH similar to 2.6) located at Langau, Austria, and in Lusatia, Germany. Oxytricha acidotolerans sp. nov. from Langau has 18 frontal-ventral-transverse cirri but a very indistinct kinety 3 fragmentation so that the assignment to Oxytricha is uncertain. The somewhat smaller species from Lusatia has a highly variable cirral pattern and the dorsal kineties arranged in the Urosomoida pattern and is, therefore, preliminary designated as Urosomoida sp. The pH response was measured as ciliate growth rates in laboratory experiments at pH ranging from 2.5 to 7.0. Our hypothesis was that the shape of the pH reaction norm would not differ between these closely related (3\% difference in their SSU rDNA) species. Results revealed a broad pH niche for O. acidotolerans, with growth rates peaking at moderately acidic conditions (pH 5.2). Cyst formation was positively and linearly related to pH. Urosomoida sp. was more sensitive to pH and did not survive at circumneutral pH. Accordingly, we reject our hypothesis that similar habitats would harbour ciliate species with virtually identical pH reaction norm.}, language = {en} } @article{ThinesKummer2013, author = {Thines, Marco and Kummer, Volker}, title = {Diversity and species boundaries in floricolous downy mildews}, series = {Mycological progress : international journal of the German Mycological Society}, volume = {12}, journal = {Mycological progress : international journal of the German Mycological Society}, number = {2}, publisher = {Springer}, address = {Heidelberg}, issn = {1617-416X}, doi = {10.1007/s11557-012-0837-7}, pages = {321 -- 329}, year = {2013}, abstract = {Floricolous downy mildews are a monophyletic group of members of the genus Peronospora (Oomycota, Peronosporales). These downy mildews can be found on a variety of families of the Asteridae, including Asteraceae, Campanulaceae, Dipsacaceae, Lamiaceae, and Orobanchaceae. With the exception of Peronospora radii, which can also cause economically relevant losses, sporulation usually takes place only on floral parts of their hosts. However, only very few specimens of these mostly inconspicuous downy mildews have so far been included in molecular phylogenies. Focusing on Lamiaceae, we have investigated multiple specimens of floricolous downy mildews for elucidating species boundaries and host specificity in this group. Based on both mitochondrial and nuclear loci, it became apparent that phylogenetic lineages in the Lamiaceae seem to be host genus specific and significant sequence diversity could be found between lineages. Based on distinctiveness in both phylogenetic reconstructions and morphology, the downy mildew on flowers of Stachys palustris is introduced as a new species, Peronospora jagei sp. nov., which can be morphologically distinguished from Peronospora stigmaticola by broader and shorter conidiospores. The diversity of the floricolous down mildews might be higher than previously assumed, although specimens from a much broader set of samples will be needed to confirm this view.}, language = {en} } @article{MirhajBoitRazzaketal.2013, author = {Mirhaj, M. and Boit, Alice and Razzak, M. A. and Wahab, M. A.}, title = {Yield performance comparison between cultures of rice cum prawn (Macrobrachium rosenbergii) and rice cum fish (Cyprinus carpio, Oreochromis niloticus) in North-Eastern Bangladesh}, series = {Aquaculture : an international journal devoted to research on the exploration and improvement of all aquatic food resources, both floristic and faunistic, from freshwater, brackish and marine environment, related directly or indirectly to human consumption}, volume = {392}, journal = {Aquaculture : an international journal devoted to research on the exploration and improvement of all aquatic food resources, both floristic and faunistic, from freshwater, brackish and marine environment, related directly or indirectly to human consumption}, number = {5}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0044-8486}, doi = {10.1016/j.aquaculture.2013.01.038}, pages = {26 -- 33}, year = {2013}, abstract = {Integrated and concurrent cultures in rice fields are a promising approach to sustainable farming as the demand for aquacultural and agricultural products continues to grow while land and water resources become increasingly scarce. Prawn farming mainly takes place in coastal regions in improved extensive to semi-intensive aquacultures but a trend to shift the industry to inland regions has been noticed. This inland study in Northern Bangladesh used different input regimes such as fertilizer and additional feed to compare the performance of prawn and fish in flooded paddy fields in regard to water quality measurements. Maximal net yields and body weight gain with minimized negative impact on water quality were found when initial body weights of prawn were optimized. Regarding yield factors in reference to the reduction of costs due to the avoidance of expensive fertilizer/feed and effort, prawn performed better than integrated fish cultures considering a higher market value of prawn with net yields of up to 97 +/- 55 kg ha(-1) for unfed and 151 +/- 61 kg ha(-1) for fed treatments. Rice yields of up to 4.7 +/- 0.1 t ha(-1) for unfed and 4.4 +/- 0.1 t ha(-1) were achieved for fed treatments. The findings suggest that for small scale farmers, prawn cum rice cultures are an economically profitable and comparatively easily manageable alternative to rice cum fish cultures.}, language = {en} } @article{WeisseLaufensteinWeithoff2013, author = {Weisse, Thomas and Laufenstein, Nicole and Weithoff, Guntram}, title = {Multiple environmental stressors confine the ecological niche of the rotifer Cephalodella acidophila}, series = {Freshwater biology}, volume = {58}, journal = {Freshwater biology}, number = {5}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0046-5070}, doi = {10.1111/fwb.12104}, pages = {1008 -- 1015}, year = {2013}, abstract = {1The planktonic food web in extremely acidic mining lakes is restricted to a few species that are either acidophilic or acidotolerant. Common metazoans inhabiting acidic mining lakes with a pH below 3 include rotifers in the genera Cephalodella and Elosa. 2The life history response of Cephalodella acidophila to three environmental key factors, pH (2, 3.5, 5.0 and 7.0), temperature (10, 17.5 and 25 degrees C) and food concentration (10000, 35000 and 50000algal cells per mL), was investigated in a full factorial design using life-table experiments. 3The effect of each of the three environmental variables investigated on the rotifer life cycle parameters (life span, fecundity and population growth rate) differed. C.acidophila is a stenoecious species with a pH optimum in the range 34 and a comparably high food threshold. Combining the laboratory results with field data, we conclude that C.acidophila is severely growth limited in its natural habitat. However, low pH alone is not harmful as long as temperatures are moderate to warm and food is abundant. 4The population of C.acidophila in the field is maintained mainly due to release from competitors and predators.}, language = {en} } @article{KlausHoelzelBochetal.2013, author = {Klaus, Valentin H. and H{\"o}lzel, Norbert and Boch, Steffen and M{\"u}ller, Jorg and Socher, Stephanie A. and Prati, Daniel and Fischer, Markus and Kleinebecker, Till}, title = {Direct and indirect associations between plant species richness and productivity in grasslands regional differences preclude simple generalization of productivity-biodiversity relationships}, series = {Preslia : the journal of the Czech Botanical Society}, volume = {85}, journal = {Preslia : the journal of the Czech Botanical Society}, number = {2}, publisher = {Czech Botanical Soc.}, address = {Praha}, issn = {0032-7786}, pages = {97 -- 112}, year = {2013}, abstract = {Plant species richness of permanent grasslands has often been found to be significantly associated with productivity. Concentrations of nutrients in biomass can give further insight into these productivity-plant species richness relationships, e.g. by reflecting land use or soil characteristics. However, the consistency of such relationships across different regions has rarely been taken into account, which might significantly compromise our potential for generalization. We recorded plant species richness and measured above-ground biomass and concentrations of nutrients in biomass in 295 grasslands in three regions in Germany that differ in soil and climatic conditions. Structural equation modelling revealed that nutrient concentrations were mostly indirectly associated with plant species richness via biomass production. However, negative associations between the concentrations of different nutrients and biomass and plant species richness differed considerably among regions. While in two regions, more than 40\% of the variation in plant species richness could be attributed to variation in biomass, K, P. and to some degree also N concentrations, in the third region only 15\% of the variation could be explained in this way. Generally, highest plant species richness was recorded in grasslands where N and P were co-limiting plant growth, in contrast to N or K (co-) limitation. But again, this pattern was not recorded in the third region. While for two regions land-use intensity and especially the application of fertilizers are suggested to be the main drivers causing the observed negative associations with productivity, in the third region the little variance accounted for, low species richness and weak relationships implied that former intensive grassland management, ongoing mineralization of peat and fluctuating water levels in fen grasslands have overruled effects of current land-use intensity and productivity. Finally, we conclude that regional replication is of major importance for studies seeking general insights into productivity-diversity relationships.}, language = {en} } @article{EinarssonBahrkeSigurdssonetal.2013, author = {Einarsson, Jon M. and Bahrke, Sven and Sigurdsson, Bjarni Thor and Ng, Chuen-How and Petersen, Petur Henry and Sigurjonsson, Olafur E. and Jonsson, Halldor and Gislason, Johannes and Thormodsson, Finnbogi R. and Peter, Martin G.}, title = {Partially acetylated chitooligosaccharides bind to YKL-40 and stimulate growth of human osteoarthritic chondrocytes}, series = {Biochemical and biophysical research communications}, volume = {434}, journal = {Biochemical and biophysical research communications}, number = {2}, publisher = {Elsevier}, address = {San Diego}, issn = {0006-291X}, doi = {10.1016/j.bbrc.2013.02.122}, pages = {298 -- 304}, year = {2013}, abstract = {Recent evidences indicating that cellular kinase signaling cascades are triggered by oligomers of N-acetylglucosamine (ChOS) and that condrocytes of human osteoarthritic cartilage secrete the inflammation associated chitolectin YKL-40, prompted us to study the binding affinity of partially acetylated ChOS to YKL-40 and their effect on primary chondrocytes in culture. Extensive chitinase digestion and filtration of partially deacetylated chitin yielded a mixture of ChOS (Oligomin(TM)) and further ultrafiltration produced T-ChOS(TM), with substantially smaller fraction of the smallest sugars. YKL-40 binding affinity was determined for the different sized homologues, revealing micromolar affinities of the larger homologues to YKL-40. The response of osteoarthritic chondrocytes to Oligomin(TM) and T-ChOS(TM) was determined, revealing 2- to 3-fold increases in cell number. About 500 mu g/ml was needed for Oligomin(TM) and around five times lower concentration for T-ChOS(TM), higher concentrations abolished this effect for both products. Addition of chitotriose inhibited cellular responses mediated by larger oligosaccharides. These results, and the fact that the partially acetylated T-ChOS(TM) homologues should resist hydrolysis, point towards a new therapeutic concept for treating inflammatory joint diseases.}, language = {en} } @article{PedersenWatthanaKocyanetal.2013, author = {Pedersen, Henrik AE. and Watthana, Santi and Kocyan, Alexander and Srimuang, Kanok-orn}, title = {Pollination biology of Luisia curtisii (Orchidaceae) indications of a deceptive system operated by beetles}, series = {Plant systematics and evolution}, volume = {299}, journal = {Plant systematics and evolution}, number = {1}, publisher = {Springer}, address = {Wien}, issn = {0378-2697}, doi = {10.1007/s00606-012-0713-6}, pages = {177 -- 185}, year = {2013}, abstract = {A population of Luisia curtisii (Orchidaceae: Aeridinae) in northern Thailand was studied with regard to pollination biology. Although a high level of self-compatibility was demonstrated experimentally, the very low natural fruit set (1.4-1.9 \%) clearly indicated that the species depends on external agents for pollination. Our observations suggest that L. curtisii is pollinated by beetles, as Lema unicolor (Chrysomelidae) and Clinteria ducalis (Scarabaeidae) were the only flower visitors observed to carry pollinaria of this species. The hypothesis of specialised cantharophily is further supported by 2-methylbutyric acid and caproic acid being striking components of the floral scent. Judging from the lack of nectar and the behaviour of visiting beetles, the pollination system seems to rely on food or brood site deception. Retention of the anther on the pollinarium for some time after pollinarium removal probably reduces the frequency of insect-mediated autogamy and geitonogamy in Luisia curtisii-a possibility that was supported by comparative data on (1) the anther retention time and inflorescence visitation time of Lema unicolor and (2) stigma and anther length in the orchid. Existing reports of specialised beetle pollination in orchids are reviewed, and we conclude that there is accumulating evidence that specialised cantharophily is more common in the Orchidaceae than previously assumed.}, language = {en} }