TY - JOUR A1 - Plath, Martin A1 - Seggel, Uta A1 - Burmeister, Heike A1 - Heubel, Katja U. A1 - Schlupp, Ingo T1 - Choosy males from the underground : male mating preferences in surface- and cave-dwelling Atlantic mollies (Poecilia mexicana) N2 - Atlantic mollies (Poecilia mexicana) inhabit a variety of surface habitats, but they also occur in a sulfur cave in southern Mexico. We examined male mate choice relative to female body size in the cave population and in the most closely related surface-dwelling population from a nearby river. Males from both populations were either light- or dark-reared and could choose between two differently sized females either on the basis of visual cues in light or on the basis of solely nonvisual cues in darkness. Sexual preferences were estimated from the degree of association. Cave molly males always showed a preference for the larger female, both in light and in darkness. Among the surface males, only light-reared males showed a preference in the visual cues test, but not in darkness. In a control experiment, we demonstrated that male association preferences directly translate into actual mating preferences. Apparently, using visual cues for mate choice is the ancestral state in this system, and using nonvisual cues has evolved as a novel trait in the cave population. We discuss the evolution of nonvisual male mate choice in the context of changed environmental conditions, namely the absence of light, hypoxia, and toxic hydrogen sulfide in the cave Y1 - 2006 UR - http://www.springerlink.com/content/100479 U6 - https://doi.org/10.1007/s00114-005-0072-z ER - TY - JOUR A1 - Stalz, Holger A1 - Roth, Udo A1 - Schleuder, Detlev A1 - Macht, Marcus A1 - Haebel, Sophie A1 - Strupat, Kerstin A1 - Peter-Katalinic, Jasna A1 - Hanisch, Franz-Georg T1 - The Geodia cydonium galectin exhibits prototype and chimera-type characteristics and a unique sequence polymorphism within its carbohydrate recognition domain N2 - The ancestral galectin from the sponge Geodia cydonium (GCG) is classified on a structural basis to the prototype subfamily, whereas its carbohydrate-binding specificity is related to that of the mammalian chimera-type galectin-3. This dual coordination reveals GCG as a potential precursor of the later evolved galectin subfamilies, which is reflected in the primary structure of the protein. This study provides evidence that GCG is the LECT1 gene product, while neither a previously described LECT2 gene nor a functional LECT2 gene product was found in the specimen under investigation. The electrophoretically separated protein isomers with apparent molecular masses of 13, 15, and 16 kDa correspond to variants of the LECT1 protein-exhibiting peptide sequence polymorphisms that concern critical positions of the carbohydrate recognition domain (13 kDa: Leu51, Asn55, His130, Gly137; 15 kDa: Ser51, Asn55, Asn130, Gly137; 16 kDa: Ser51, Tyr55, Asn130, Glu137). Four residues, highly conserved in the galectin family, are substituted. None of the residues claimed to be involved in interactions with GalNAc alpha 1-3 moieties at an extended binding subsite of galectin-3 was identified in the corresponding positions of GCG. Apparently, the substitutions do not confer distinct binding characteristics to the GCG variants as evidenced by binding studies with a recombinantly expressed 15-kDa isoform. The natural isoforms as well as the recombinant 15-kDa isoform oligomerize by the formation of non-covalent heteromeric or homomeric complexes. A phosphorylation of the galectin was confirmed neither by mass spectrometry nor by alkaline phosphatase treatment combined with isoelectric focusing Y1 - 2006 UR - http://glycob.oxfordjournals.org/content/16/5/402.full U6 - https://doi.org/10.1093/glycob/cwj086 ER - TY - JOUR A1 - Sato, A A1 - Gambale, Franco A1 - Dreyer, Ingo A1 - Uozumi, N T1 - Posttranslational inodification affects K+ current of plant K+ channel Y1 - 2006 ER - TY - JOUR A1 - Schulz, Tim Julius A1 - Thierbach, Renè A1 - Voigt, Anja A1 - Drewes, Gunnar A1 - Mietzner, Brun A1 - Steinberg, Pablo A1 - Pfeiffer, Andreas F. H. A1 - Ristow, Michael T1 - Induction of oxidative metabolism by mitochondrial frataxin inhibits cancer growth : Otto Warburg revisited N2 - More than 80 years ago Otto Warburg suggested that cancer might be caused by a decrease in mitochondrial energy metabolism paralleled by an increase in glycolytic flux. In later years, it was shown that cancer cells exhibit multiple alterations in mitochondrial content, structure, function, and activity. We have stably overexpressed the Friedreich ataxia-associated protein frataxin in several colon cancer cell lines. These cells have increased oxidative metabolism, as shown by concurrent increases in aconitase activity, mitochondrial membrane potential, cellular respiration, and ATP content. Consistent with Warburg's hypothesis, we found that frataxin-overexpressing cells also have decreased growth rates and increased population doubling times, show inhibited colony formation capacity in soft agar assays, and exhibit a reduced capacity for tumor formation when injected into nude mice. Furthermore, overexpression of frataxin leads to an increased phosphorylation of the tumor suppressor p38 mitogen-activated protein kinase, as well as decreased phosphorylation of extracellular signal-regulated kinase. Taken together, these results support the view that an increase in oxidative metabolism induced by mitochondrial frataxin may inhibit cancer growth in mammals Y1 - 2006 UR - http://www.jbc.org/content/281/2/977.full.pdf+html U6 - https://doi.org/10.1074/jbc.M511064200 ER - TY - JOUR A1 - Wronski, Torsten A1 - Apio, Ann A1 - Wanker, R A1 - Plath, Martin T1 - Behavioural repertoire of the bushbuck (Tragelaphus scriptus): agonistic interactions, mating behaviour and parent-offspring relations N2 - A free-ranging bushbuck (Tragelaphus scriptus) population was observed over a period of 3 years, thereby enabling a detailed description of the behavioural repertoire of this widespread but barely investigated solitary African antelope species. Agonistic and submissive behaviour patterns are described, among them several hitherto un- described behaviour patterns - such as "escorting", where territorial males guide intruders to the periphery of their territory - and "push-up position", an extreme form of submissive behaviour. Furthermore, we report on behaviour patterns of males and females during mating as well as on behaviour patterns of parents directed towards their offspring. Again, we describe a hitherto unknown behaviour: the protection of calves by adult males, which may be a socio-positive behaviour directed towards their offspring led by kin selection Y1 - 2006 UR - http://www.springerlink.com/content/h4v41315l1717v87/ U6 - https://doi.org/10.1007/s10164-005-0186-y ER - TY - JOUR A1 - Yuryev, Ruslan A1 - Kasche, Volker A1 - Ignatova, Zoya A1 - Galunsky, Boris T1 - Improved A. faecalis penicillin amidase mutant retains the thermodynamic and pH stability of the wild type enzyme N2 - Penicillin amidase from Alacaligenes faecalis is an attractive biocatalyst for hydrolysis of penicillin G for production of 6-aminopenicillanic acid, which is used in the synthesis of semi-synthetic beta-lactam antibiotics. Recently a mutant of this enzyme with extended C-terminus of the A-chain comprising parts of the connecting linker peptide was constructed. Its turnover number for the hydrolysis of penicillin G was 140 s(-1), about twice of the value for the wild-type enzyme (80 s(-1)). At the same time the specificity constant was improved about three-fold. The wild- type and the mutant enzymes showed similar pH stability suggesting that the linker peptide fragment covalently attached to the A-chain does not alter the electrostatic interactions in the protein core. Although the global stability of A. faecalis wild-type enzyme and the T206GS213G variant does not differ, the presence of the linker fragment stabilizes the domains interface, as evidenced by the monophasic transition of the mutant enzyme from folded to unfolded state during urea-induced denaturation. The high stability and activity of the mutant enzyme provides a rationale to use it as a biocatalyst in the industrial processes, where the enzyme must be more robust to fluctuations in the operational conditions. Y1 - 2010 UR - http://springerlink.metapress.com/content/1573-4943/ U6 - https://doi.org/10.1007/s10930-010-9238-4 SN - 1572-3887 ER - TY - JOUR A1 - Liu, Songqin A1 - Wollenberger, Ursula A1 - Katterle, Martin A1 - Scheller, Frieder W. T1 - Ferroceneboronic acid-based amperometric biosensor for glycated hemoglobin N2 - An amperometric biosensor for the determination of glycated hemoglobin in human whole blood is proposed. The principle is based on the electrochemical measurement of ferroceneboronic acid (FcBA) that has been specifically bound to the glycated N-terminus. Hemoglobin is immobilized on a zirconium dioxide nanoparticle modified pyrolytic graphite electrode (PGE) in the presence of didodecyldimethylammonium bromide (DDAB). The incubation of this sensor in FcBA solution leads to the formation of an FcBA-modified surface due to the affinity interaction between boronate and the glycated sites of the hemoglobin. The binding of FcBA results in well-defined redox peaks with an E-0' of 0.299 V versus Ag/AgCl (1 M KCl). The square wave voltammetric response of the bound FcBA reflects the amount of glycated hemoglobin at the surface. This signal increases linearily with the degree of glycated hemoglobin from 6.8 to 14.0% of total immobilized hemoglobin. The scheme was applied to the determination of the fraction of glycated hemoglobin in whole blood samples. Y1 - 2006 UR - http://www.sciencedirect.com/science/journal/09254005 U6 - https://doi.org/10.1016/j.snb.2005.07.011 SN - 0925-4005 ER - TY - JOUR A1 - Reineking, Björn A1 - Schröder-Esselbach, Boris T1 - Constrain to perform : regularization of habitat models N2 - Predictive habitat models are an important tool for ecological research and conservation. A major cause of unreliable models is excessive model complexity, and regularization methods aim to improve the predictive performance by adequately constraining model complexity. We compare three regularization methods for logistic regression: variable selection, lasso, and ridge. They differ in the way model complexity is measured: variable selection uses the number of estimated parameters, the lasso uses the sum of the absolute values of the parameter estimates, and the ridge uses the sum of the squared values of the parameter estimates. We performed a simulation study with environmental data of a real landscape and artificial species occupancy data. We investigated the effect of three factors on relative model performance: (1) the number of parameters (16, 10, 6, 2) in the 'true' model that determined the distribution of the artificial species, (2) the prevalence, i.e. the proportion of sites occupied by the species, and (3) the sample size (measured in events per variable, EPV). Regularization improved model discrimination and calibration. However, no regularization method performed best under all circumstances: the ridge generally performed best in the 16-parameter scenario. The lasso generally performed best in the 10-parameter scenario. Variable selection with AIC was best at large sample sizes (EPV >= 10) when less than half of the variables influenced the species distribution. However, at low sample sizes (EPV < 10), ridge and lasso always performed best, regardless of the parameter scenario or prevalence. Overall, calibration was best in ridge models. Other methods showed overconfidence, particularly at low sample sizes. The percentage of correctly identified models was low for both lasso and variable selection. Variable selection should be used with caution. Although it can produce the best performing models under certain conditions, these situations are difficult to infer from the data. Ridge and lasso are risk-averse model strategies that can be expected to perform well under a wide range of underlying species-habitat relationships, particularly at small sample sizes. Y1 - 2006 UR - http://www.sciencedirect.com/science/journal/03043800 U6 - https://doi.org/10.1016/j.ecolmodel.2005.10.003 SN - 0304-3800 ER - TY - JOUR A1 - Rossmanith, Eva A1 - Grimm, Volker A1 - Blaum, Niels A1 - Jeltsch, Florian T1 - Behavioural flexibility in the mating system buffers population extinction: lessons from the Lesser Spotted Woodpecker (Picoides minor) N2 - In most stochastic models addressing the persistence of small populations, environmental noise is included by imposing a synchronized effect of the environment on all individuals. However, buffer mechanisms are likely to exist that may counteract this synchronization to some degree. We have studied whether the flexibility in the mating system, which has been observed in some bird species, is a potential mechanism counteracting the synchronization of environmental fluctuations. Our study organism is the lesser spotted woodpecker Picoides minor (Linnaeus), a generally monogamous species. However, facultative polyandry, where one female mates with two males with separate nests, was observed in years with male-biased sex ratio. We constructed an individual-based model from data and observations of a population in Taunus, Germany. We tested the impact of three behavioural scenarios on population persistence: (1) strict monogamy; (2) polyandry without costs; and (3) polyandry assuming costs in terms of lower survival and reproductive success for secondary males. We assumed that polyandry occurs only in years with male-biased sex ratio and only for females with favourable breeding conditions. Even low rates of polyandry had a strong positive effect on population persistence. The increase of persistence with carrying capacity was slower in the monogamous scenario, indicating strong environmental noise. In the polyandrous scenarios, the increase of persistence was stronger, indicating a buffer mechanism. In the polyandrous scenarios, populations had a higher mean population size, a lower variation in number of individuals, and recovered faster after a population breakdown. Presuming a realistic polyandry rate and costs for polyandry, there was still a strong effect of polyandry on persistence. The results show that polyandry and in general flexibility in mating systems is a buffer mechanism that can significantly reduce the impact of environmental and demographic noise in small populations. Consequently, we suggest that even behaviour that seems to be exceptional should be considered explicitly when predicting the persistence of populations Y1 - 2006 U6 - https://doi.org/10.1111/j.1365-2656.2006.01074.x ER - TY - JOUR A1 - Buscaglia, Marco A1 - Schuler, Benjamin A1 - Lapidus, Lisa J. A1 - Eaton, Wiliam A. A1 - Hofrichter, James T1 - Kinetics of intramolecular contact formation in a denatured protein N2 - Quenching of the triplet state of tryptophan by cysteine has provided a new tool for measuring the rate of forming a specific intramolecular contact in disordered polypeptides. Here, we use this technique to investigate contact formation in the denatured state of CspTm, a small cold-shock protein from Thermotoga maritima, engineered to contain a single tryptophan residue (W29) and a single cysteine residue at the C terminus (C67). At all concentrations of denaturant, the decay rate of the W29 triplet of the unfolded protein is more than tenfold faster than the rate observed for the native protein (not, vert, similar104 s;1). Experiments on the unfolded protein without the added C- terminal cysteine residue show that this faster rate results entirely from contact quenching by C67. The quenching rate in the unfolded state by C67 increases at concentrations of denaturant that favor folding, indicating a compaction of the unfolded protein as observed previously in single-molecule Foerster resonance energy transfer (FRET) experiments. Y1 - 2003 UR - http://www.sciencedirect.com/science/article/pii/S002228360300891X SN - 0022-2836 ER - TY - JOUR A1 - Moodley, Yoshan A1 - Bruford, Michael W. A1 - Bleidorn, Christoph A1 - Wronski, Torsten A1 - Apio, Ann A1 - Plath, Martin T1 - Analysis of mitochondrial DNA data reveals non-monophyly in the bushbuck (Tragelaphus scriptus) complex Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/16165047 U6 - https://doi.org/10.1016/j.mambio.2008.05.003 SN - 1616-5047 ER - TY - JOUR A1 - Nagel, Birgit A1 - Warsinke, Axel T1 - Towards separation-free electrochemical affinity sensors by using antibodies, aptamers and molecularly imprinted polymers : a review Y1 - 2006 U6 - https://doi.org/10.1080/00032710600853903 ER - TY - JOUR A1 - Nitsche, Andreas A1 - Kurth, Andreas A1 - Dunkhorst, Anna A1 - Pänke, Oliver A1 - Sielaff, Hendrik A1 - Junge, Wolfgang A1 - Muth, Doreen A1 - Scheller, Frieder W. A1 - Stöcklein, Walter F. M. A1 - Pauli, Georg A1 - Kage, Andreas T1 - One-step selection of vaccinia virus binding DNA-aptamers by MonoLEX Y1 - 2007 UR - http://www.biomedcentral.com/1472-6750/7 U6 - https://doi.org/10.1186/1472-6750-7-48 ER - TY - JOUR A1 - Fettke, Jörg A1 - Chia, Tansy A1 - Eckermann, Nora A1 - Smith, Alison M. A1 - Steup, Martin T1 - A transglucosidase necessary for starch degradation and maltose metabolism in leaves at night acts on cytosolic heteroglycans (SHG) N2 - The recently characterized cytosolic transglucosidase DPE2 (EC 2.4.1.25) is essential for the cytosolic metabolism of maltose, an intermediate on the pathway by which starch is converted to sucrose at night. In in vitro assays, the enzyme utilizes glycogen as a glucosyl acceptor but the in vivo acceptor molecules remained unknown. In this communication we present evidence that DPE2 acts on the recently identified cytosolic water-soluble heteroglycans (SHG) as does the cytosolic phosphorylase (EC 2.4.1.1) isoform. By using in vitro two-step C-14 labeling assays we demonstrate that the two transferases can utilize the same acceptor sites of the SHG. Cytosolic heteroglycans from a DPE2-deficient Arabidopsis mutant were characterized. Compared with the wild type the glucose content of the heteroglycans was increased. Most of the additional glucosyl residues were found in the outer chains of SHG that are released by an endo- alpha-arabinanase (EC 3.2.1.99). Additional starch-related mutants were characterized for further analysis of the increased glucosyl content. Based on these data, the cytosolic metabolism of starch-derived carbohydrates is discussed Y1 - 2006 UR - http://www3.interscience.wiley.com/cgi-bin/issn?DESCRIPTOR=PRINTISSN&VALUE=0960-7412 U6 - https://doi.org/10.1111/j.1365-313X.2006.02732.x SN - 0960-7412 ER - TY - JOUR A1 - Kapp, Andreas A1 - Beissenhirtz, Moritz Karl A1 - Geyer, F. A1 - Scheller, Frieder W. A1 - Viezzoli, Maria Silvia A1 - Lisdat, Fred T1 - Electrochemical and sensorial behaviour of SOD mutants immobilized on gold electrodes in aqueous / organic solvent mixtures Y1 - 2006 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/26571/ U6 - https://doi.org/10.1002/elan.200603620 SN - 1040-0397 ER - TY - JOUR A1 - Knösche, Rüdiger T1 - Organic sediment nutrient concentrations and their relationship with the hydrological connectivity of floodplain waters (River Havel, NE Germany) N2 - Investigations on large canalised rivers, for example the Danube, have shown that transported particulate matter, which is typically inorganic, is predominantly deposited in waters near the river's main channel. This investigation deals with the lower section of the River Havel (NE Germany), a canalised lowland river with a very flat floodplain. This river is highly polluted by nutrients from urban areas (Berlin) and a long chain of river lakes produces high concentrations of phytoplankton. Due to the high proportion of planktogenic detritus, it was hypothesised that greater quantities of nutrient-rich fine particulate organic matter (FPOM) would be deposited in floodplain waters located further from the main channel than has been reported for large rivers.The total nutrient, P-binding metal (Fe, Al, and Mn), organic and inorganic carbon (TOC, TIC) contents of the upper organic sediment layer (0 - 4 cm) were analysed in samples collected from 48 floodplain water and river sites. The sediment bulk density, calculated on the basis of dry mass content and loss on ignition, was used to characterize the waters according to the impact of the river current. The results showed that the variability of total phosphorus (TP) was best explained by the variability of total iron (TFe, R2 = 0.52). The floodplain water sediments could clearly be separated into two groups on the basis of the sediment particle size composition, and of the element ratios TOC:TP, TN:TP, primarily TFe:TP. The sediments from impounded river sections and from mouth sections of backwaters (approx. 100 - 200 m) were characterized by a high proportion particles from the 0.1 - 0.5 mm size fraction and by homogeneous, low TFe:TP, TOC:TP and TN:TP ratios. Sediments from distal sections of backwaters and of oxbow lakes tended to exhibit high element ratios with much higher variability. These results were interpreted as a spatially limited impact of the river on the floodplain water sediments. Contrary to expectation, the phosphorus bound in river seston was predominantly and very homogeneously deposited in the impounded river and mouth sections of backwaters. This implies that the inundation of the floodplain waters during spring floods seems to have no important material impact on the sediments in waters of low hydrologically connectivity with the River Havel. Y1 - 2006 ER - TY - JOUR A1 - Micheel, Burkhard T1 - Monoclonal Antibodies Y1 - 2006 SN - 978-3-540-44244-8 ER - TY - JOUR A1 - Spijkerman, Elly T1 - Is there really insufficient support for Tilman's R* concept? A comment on Miller et al Y1 - 2007 ER - TY - JOUR A1 - Gaedke, Ursula T1 - Spectral analysis unmasks synchronous and compensatory dynamics in plankton communities Y1 - 2007 ER - TY - JOUR A1 - Bell, Elanor M. A1 - Park, Tae-Gyu A1 - Pearce, Imojen A1 - Rublee, Parke A. A1 - Bolch, Christopher J. S. A1 - Hallegraeff, Gustaff M. T1 - Detection of a novel ecotype of Pfiesteria piscicida (Dinophyceae) in an Antarctic saline lake by real-time PCR Y1 - 2007 ER -