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991.
Josephine D'Urban Jackson Natalie dos Remedios Kathryn H. Maher Sama Zefania Susan Haig Sara Oyler‐McCance Donald Blomqvist Terry Burke Michael W. Bruford Tamás Székely Clemens Küpper 《Evolution; international journal of organic evolution》2017,71(5):1313-1326
Sexual selection may act as a promotor of speciation since divergent mate choice and competition for mates can rapidly lead to reproductive isolation. Alternatively, sexual selection may also retard speciation since polygamous individuals can access additional mates by increased breeding dispersal. High breeding dispersal should hence increase gene flow and reduce diversification in polygamous species. Here, we test how polygamy predicts diversification in shorebirds using genetic differentiation and subspecies richness as proxies for population divergence. Examining microsatellite data from 79 populations in 10 plover species (Genus: Charadrius) we found that polygamous species display significantly less genetic structure and weaker isolation‐by‐distance effects than monogamous species. Consistent with this result, a comparative analysis including 136 shorebird species showed significantly fewer subspecies for polygamous than for monogamous species. By contrast, migratory behavior neither predicted genetic differentiation nor subspecies richness. Taken together, our results suggest that dispersal associated with polygamy may facilitate gene flow and limit population divergence. Therefore, intense sexual selection, as occurs in polygamous species, may act as a brake rather than an engine of speciation in shorebirds. We discuss alternative explanations for these results and call for further studies to understand the relationships between sexual selection, dispersal, and diversification. 相似文献
992.
Natalie dos Remedios Clemens Küpper Tamás Székely Neil Baker Wilferd Versfeld Patricia L. M. Lee 《Ibis》2017,159(4):792-802
The Chestnut‐banded Plover Charadrius pallidus is a Near‐Threatened shorebird species endemic to mainland Africa. We examined levels of genetic differentiation between its two morphologically and geographically distinct subspecies, C. p. pallidus in southern Africa (population size 11 000–16 000) and C. p. venustus in eastern Africa (population size 6500). In contrast to other plover species that maintain genetic connectivity over thousands of kilometres across continental Africa, we found profound genetic differences between remote sampling sites. Phylogenetic network analysis based on four nuclear and two mitochondrial gene regions, and population genetic structure analyses based on 11 microsatellite loci, indicated strong genetic divergence, with 2.36% mitochondrial sequence divergence between individuals sampled in Namibia (southern Africa) and those of Kenya and Tanzania (eastern Africa). This distinction between southern and eastern African populations was also supported by highly distinct genetic clusters based on microsatellite markers (global FST = 0.309, = 0.510, D = 0.182). Behavioural factors that may promote genetic differentiation in this species include habitat specialization, monogamous mating behaviour and sedentariness. Reliance on an extremely small number of saline lakes for breeding and limited dispersal between populations are likely to promote reproductive and genetic isolation between eastern and southern Africa. We suggest that the two Chestnut‐banded Plover subspecies may warrant elevation to full species status. To assess this distinction fully, additional sample collection will be needed, with analysis of genetic and phenotypic traits from across the species’ entire breeding range. 相似文献
993.
Disruption of genes involved in CORVET complex leads to enhanced secretion of heterologous carboxylesterase only in protease deficient Pichia pastoris
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Lukas Marsalek Clemens Gruber Friedrich Altmann Markus Aleschko Diethard Mattanovich Brigitte Gasser Verena Puxbaum 《Biotechnology journal》2017,12(5)
The methylotrophic yeast Pichia pastoris (Komagataella spp.) is a popular microbial host for the production of recombinant proteins. Previous studies have shown that mis‐sorting to the vacuole can be a bottleneck during production of recombinant secretory proteins in yeast, however, no information was available for P. pastoris. In this work the authors have therefore generated vps (vacuolar protein sorting) mutant strains disrupted in genes involved in the CORVET (class C core vacuole/endosome tethering) complex at the early stages of endosomal sorting. Both Δvps8 and Δvps21 strains contained lower extracellular amounts of heterologous carboxylesterase (CES) compared to the control strain, which could be attributed to a high proteolytic activity present in the supernatants of CORVET engineered strains due to rerouting of vacuolar proteases. Serine proteases were identified to be responsible for this proteolytic degradation by liquid chromatography‐mass spectrometry and protease inhibitor assays. Deletion of the major cellular serine protease Prb1 in Δvps8 and Δvps21 strains did not only rescue the extracellular CES levels, but even outperformed the parental CES strain (56 and 80% higher yields, respectively). Further deletion of Ybr139W, another serine protease, did not show a further increase in secretion levels. Higher extracellular CES activity and low proteolytic activity were detected also in fed batch cultivation of Δvps21Δprb1 strains, thus confirming that modifying early steps in the vacuolar pathway has a positive impact on heterologous protein secretion. 相似文献
994.
A robust feeding strategy to maintain set‐point glucose in mammalian fed‐batch cultures when input parameters have a large error
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Viktor Konakovsky Christoph Clemens Markus Michael Müller Jan Bechmann Christoph Herwig 《Biotechnology progress》2017,33(2):317-336
Industrial CHO cell cultures run under fed‐batch conditions are required to be controlled in particular ranges of glucose, while glucose is constantly consumed and must be replenished by a feed. The most appropriate feeding rate is ideally stoichiometric and adaptive in nature to balance the dynamically changing rate of glucose consumption. However, high errors in biomass and glucose estimation as well as limited knowledge of the true metabolic state challenge the control strategy. In this contribution, we take these errors into account and simulate the output with uncertainty trajectories in silico in order to control glucose concentration. Other than many control strategies, which require parameter estimation, our assumptions are founded on two pillars: (i) first principles and (ii) prior knowledge about the variability of fed‐batch CHO cell culture. The algorithm was exposed to an in‐silico Design of Experiments (DoE), in which variations of parameters were changed simultaneously, such as clone‐specific behavior, precision of equipment and desired control range used. The results demonstrate that our method achieved the target of holding the glucose concentration within an acceptable range. A robust and sufficient level of control could be demonstrated even with high errors for biomass or metabolic state estimation. In a time where blockbuster drugs are queuing up for time slots of their production, this transferable control strategy that is independent of tedious establishment runs may be a decisive advantage for rapid implementation during technology transfer and scale up and decrease in campaign change over time. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:317–336, 2017 相似文献
995.
Conservation status of freshwater mussels in Europe: state of the art and future challenges
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Manuel Lopes‐Lima David C. Aldridge Rafael Araujo Jakob Bergengren Yulia Bespalaya Erika Bódis Lyubov Burlakova Dirk Van Damme Karel Douda Elsa Froufe Dilian Georgiev Clemens Gumpinger Alexander Karatayev Ümit Kebapçi Ian Killeen Jasna Lajtner Bjørn M. Larsen Rosaria Lauceri Anastasios Legakis Sabela Lois Stefan Lundberg Evelyn Moorkens Gregory Motte Karl‐Otto Nagel Paz Ondina Adolfo Outeiro Momir Paunovic Vincent Prié Ted von Proschwitz Nicoletta Riccardi Mudīte Rudzīte Māris Rudzītis Christian Scheder Mary Seddon Hülya Şereflişan Vladica Simić Svetlana Sokolova Katharina Stoeckl Jouni Taskinen Amílcar Teixeira Frankie Thielen Teodora Trichkova Simone Varandas Heinrich Vicentini Katarzyna Zajac Tadeusz Zajac Stamatis Zogaris 《Biological reviews of the Cambridge Philosophical Society》2017,92(1):572-607
Freshwater mussels of the Order Unionida provide important ecosystem functions and services, yet many of their populations are in decline. We comprehensively review the status of the 16 currently recognized species in Europe, collating for the first time their life‐history traits, distribution, conservation status, habitat preferences, and main threats in order to suggest future management actions. In northern, central, and eastern Europe, a relatively homogeneous species composition is found in most basins. In southern Europe, despite the lower species richness, spatially restricted species make these basins a high conservation priority. Information on freshwater mussels in Europe is unevenly distributed with considerable differences in data quality and quantity among countries and species. To make conservation more effective in the future, we suggest greater international cooperation using standardized protocols and methods to monitor and manage European freshwater mussel diversity. Such an approach will not only help conserve this vulnerable group but also, through the protection of these important organisms, will offer wider benefits to freshwater ecosystems. 相似文献
996.
997.
Frederick A Tsigelny I Cohenour F Spiker C Krejci E Chatonnet A Bourgoin S Richards G Allen T Whitlock MH Pezzementi L 《The FEBS journal》2008,275(6):1309-1322
To learn more about the evolution of the cholinesterases (ChEs), acetylcholinesterase (AChE) and butyrylcholinesterase in the vertebrates, we investigated the AChE activity of a deuterostome invertebrate, the urochordate Ciona intestinalis, by expressing in vitro a synthetic recombinant cDNA for the enzyme in COS-7 cells. Evidence from kinetics, pharmacology, molecular biology, and molecular modeling confirms that the enzyme is AChE. Sequence analysis and molecular modeling also indicate that the cDNA codes for the AChE(T) subunit, which should be able to produce all three globular forms of AChE: monomers (G(1)), dimers (G(2)), and tetramers (G(4)), and assemble into asymmetric forms in association with the collagenic subunit collagen Q. Using velocity sedimentation on sucrose gradients, we found that all three of the globular forms are either expressed in cells or secreted into the medium. In cell extracts, amphiphilic monomers (G(1)(a)) and non-amphiphilic tetramers (G(4)(na)) are found. Amphiphilic dimers (G(2)(a)) and non-amphiphilic tetramers (G(4)(na)) are secreted into the medium. Co-expression of the catalytic subunit with Rattus norvegicus collagen Q produces the asymmetric A(12) form of the enzyme. Collagenase digestion of the A(12) AChE produces a lytic G(4) form. Notably, only globular forms are present in vivo. This is the first demonstration that an invertebrate AChE is capable of assembling into asymmetric forms. We also performed a phylogenetic analysis of the sequence. We discuss the relevance of our results with respect to the evolution of the ChEs in general, in deuterostome invertebrates, and in chordates including vertebrates. 相似文献
998.
Jones CE Schwerdt J Bretag TA Baumann U Brown AL 《Bioinformatics (Oxford, England)》2008,24(22):2628-2629
GOSLING is a web-based protein function annotator that uses a decision tree-derived rule set to quickly predict Gene Ontology terms for a protein. A score is assigned to each term prediction that is indicative of the accuracy of the prediction. Due to its speed and accuracy GOSLING is ideally suited for high-throughput annotation tasks. AVAILABILITY: https://www.sapac.edu.au/gosling 相似文献
999.
Scaffolds for osteochondral tissue engineering should provide mechanical stability, while offering specific signals for chondral and bone regeneration with a completely interconnected porous network for cell migration, attachment, and proliferation. Composites of polymers and ceramics are often considered to satisfy these requirements. As such methods largely rely on interfacial bonding between the ceramic and polymer phase, they may often compromise the use of the interface as an instrument to direct cell fate. Alternatively, here, we have designed hybrid 3D scaffolds using a novel concept based on biomaterial assembly, thereby omitting the drawbacks of interfacial bonding. Rapid prototyped ceramic particles were integrated into the pores of polymeric 3D fiber-deposited (3DF) matrices and infused with demineralized bone matrix (DBM) to obtain constructs that display the mechanical robustness of ceramics and the flexibility of polymers, mimicking bone tissue properties. Ostechondral scaffolds were then fabricated by directly depositing a 3DF structure optimized for cartilage regeneration adjacent to the bone scaffold. Stem cell seeded scaffolds regenerated both cartilage and bone in vivo. 相似文献
1000.
Alessandro Esposito Teresa Tiffert Jakob M. A. Mauritz Simon Schlachter Lawrence H. Bannister Clemens F. Kaminski Virgilio L. Lew 《PloS one》2008,3(11)