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81.
The morphology of male genitalia often suggests functions besidessperm transfer that may have evolved under natural or sexualselection. In several species of sexually cannibalistic spiders,males damage their paired genitalia during mating, limitingthem to one copulation per pedipalp. Using a triple-mating experiment,we tested if genital damage in the orb-web spider Argiope bruennichiincreases male fitness either through facilitating his escapefrom an aggressive female or by obstructing the female's inseminationducts against future copulation attempts from other males. Wefound no survival advantage for males damaging their pedipalps;however, copulations into a previously used insemination ductwere significantly shorter when the previous male had left partsof his genitalia inside the insemination duct. Because copulationduration determines paternity in this species, our result suggeststhat male genital damage in A. bruennichi is sexually selected.By breaking off parts of their intromittent organs inside avirgin female, males can reduce sperm competition and therebyincrease their paternity success. 相似文献
82.
The sea aster, Aster tripolium L., grows naturally in temperate regions, mainly in the salt meadows close to the coast. The species is also found in naturally and anthropogenically salt-contaminated inland habitats, such as potash mine dumps. The genetic relationships among populations from different habitats and correlations of the genotype with physiological and vegetational parameters were investigated. A. tripolium plants from five different sites close to the seashore on the North Sea island Baltrum, from five different potash mine dumps and, as an outgroup, from the seashore in Japan were probed. DNA was extracted from five plants from each of the 11 A. tripolium populations and analyzed for random amplified polymorphic DNA (RAPD). Altogether 35 polymorphic bands in 51 individuals and 45 different detectable genotypes could be identified. For evaluation of the genetic variation using RAPD bands, the neighbor-joining method, the principal coordinate analysis, and the analysis of molecular variance were applied, resulting in the classification into three genetic groups. A. tripolium plants from different ecological habitats on Baltrum were closely related while the plants growing at the deposit dumps showed a higher genetic diversity. The Japanese population was genetically very different from the German populations. Correlations between phytosociological and soil parameters and the respective genotype were not significant. The results argue for a conservation of anthropogenically salt-contaminated habitats to maintain genetic variability not only on the species level, but also within a species. 相似文献
83.
Thyroid hormone receptor α1 is a critical regulator for the expression of ion channels during final differentiation of outer hair cells 总被引:1,自引:1,他引:0
Winter H Braig C Zimmermann U Engel J Rohbock K Knipper M 《Histochemistry and cell biology》2007,128(1):65-75
Cochlear outer hair cells (OHCs) terminally differentiate prior to the onset of hearing. During this time period, thyroid
hormone (TH) dramatically influences inner ear development. It has been shown recently that TH enhances the expression of
the motor protein prestin via liganded TH receptor β (TRβ) while in contrast the expression of the potassium channel KCNQ4
is repressed by unliganded TRα1. These different mechanisms of TH regulation by TRα1 or TRβ prompted us to analyse other ion
channels that are required for the final differentiation of OHCs. We analysed the onset of expression of the Ca2+ channel CaV1.3, and the K+ channels SK2 and BK and correlated the results with the regulation via TRα1 or TRβ. The data support the hypothesis that
proteins expressed in rodents prior to or briefly after birth like CaV1.3 and prestin are either independent of TH (e.g. CaV1.3) or enhanced through TRβ (e.g. prestin). In contrast, proteins expressed in rodents later than P6 like KCNQ4 (∼P6), SK2
(∼P9) and BK (∼P11) are repressed through TRα1. We hypothesise that the precise regulation of expression of the latter genes
requires a critical local TH level to overcome the TRα1 repression.
Harald Winter and Claudia Braig contributed equally to this work. 相似文献
84.
Gregor J Zeller T Balzer A Haberzettl K Klug G 《Journal of molecular microbiology and biotechnology》2007,13(1-3):126-139
The formation of photosynthetic complexes in facultatively photosynthetic bacteria is controlled by the oxygen tension in the environment. In Rhodobacter capsulatus the two-component system RegB/RegA plays a major role in the redox control of photosynthesis genes but also controls other redox-dependent systems. The response regulator RegA is phosphorylated under low oxygen tension and activates the puf and puc operons, which encode pigment binding proteins, by binding to their promoter regions. Data from a yeast two-hybrid analysis as well as an in vitroanalysis indicate that RegA interacts with the NtrX protein, the response regulator of the NtrY/NtrX two-component system which is believed to be involved in regulation of nitrogen fixation genes. Our further analysis revealed that NtrX is indeed involved in the regulation of the puf and puc operons. Furthermore, we showed that an altered NtrX protein, which is predicted to adopt the conformation of phosphorylated NtrX protein, binds within the puf promoter region close to the RegA binding sites. We conclude that a direct interaction of two response regulators connects the regulatory systems for redox control and nitrogen control. 相似文献
85.
Christian M Kähler Jutta Wechselberger Wolfgang Hilbe Andreas Gschwendtner Daniela Colleselli Harald Niederegger Eva-Maria Boneberg Gilbert Spizzo Albrecht Wendel Eberhard Gunsilius Josef R Patsch Jürg Hamacher 《Respiratory research》2007,8(1):50-17
Background
Bone marrow-derived progenitors for both epithelial and endothelial cells have been observed in the lung. Besides mature endothelial cells (EC) that compose the adult vasculature, endothelial progenitor cells (EPC) are supposed to be released from the bone marrow into the peripheral blood after stimulation by distinct inflammatory injuries. Homing of ex vivo generated bone marrow-derived EPC into the injured lung has not been investigated so far. We therefore tested the hypothesis whether homing of EPC in damaged lung tissue occurs after intravenous administration.Methods
Ex vivo generated, characterized and cultivated rat bone marrow-derived EPC were investigated for proliferation and vasculogenic properties in vitro. EPC were tested for their homing in a left-sided rat lung transplant model mimicking a severe acute lung injury. EPC were transplanted into the host animal by peripheral administration into the femoral vein (106 cells). Rats were sacrificed 1, 4 or 9 days after lung transplantation and homing of EPC was evaluated by fluorescence microscopy. EPC were tested further for their involvement in vasculogenesis processes occurring in subcutaneously applied Matrigel in transplanted animals.Results
We demonstrate the integration of intravenously injected EPC into the tissue of the transplanted left lung suffering from acute lung injury. EPC were localized in vessel walls as well as in destructed lung tissue. Virtually no cells were found in the right lung or in other organs. However, few EPC were found in subcutaneous Matrigel in transplanted rats.Conclusion
Transplanted EPC may play an important role in reestablishing the endothelial integrity in vessels after severe injury or at inflamatory sites and might further contribute to vascular repair or wound healing processes in severely damaged tissue. Therapeutic applications of EPC transplantation may ensue. 相似文献86.
87.
Evidence-based programs (EBPs) are used in many health promotion efforts to ensure that the intended positive behavioral and health outcomes will be achieved. However, because EBPs are developed and tested in research settings, the contextual elements of real world implementation play an important role in their successful delivery in communities. As an intermediary charged with supporting the translation of research to practice for a statewide teen pregnancy prevention initiative, the ACT for Youth Center of Excellence conducted a mid-course evaluation to identify factors that contribute to the successful implementation of EBPs. The findings indicate that successful implementation involves systematic planning that addresses three critical contextual factors: community readiness, organizational capacity, and setting characteristics. By attending both to factors identified from local practice, and to theory and evidence identified through implementation science, practitioners can strengthen programming and enhance the quality of EBP delivery. 相似文献
88.
Synthetic peptides mimicking the binding site of human acetylcholinesterase for its inhibitor fasciculin 2 下载免费PDF全文
Uwe Kafurke Ariel Erijman Yonatan Aizner Julia M. Shifman Jutta Eichler 《Journal of peptide science》2015,21(9):723-730
Molecules capable of mimicking protein binding and/or functional sites present useful tools for a range of biomedical applications, including the inhibition of protein–ligand interactions. Such mimics of protein binding sites can currently be generated through structure‐based design and chemical synthesis. Computational protein design could be further used to optimize protein binding site mimetics through rationally designed mutations that improve intermolecular interactions or peptide stability. Here, as a model for the study, we chose an interaction between human acetylcholinesterase (hAChE) and its inhibitor fasciculin‐2 (Fas) because the structure and function of this complex is well understood. Structure‐based design of mimics of the hAChE binding site for Fas yielded a peptide that binds to Fas at micromolar concentrations. Replacement of hAChE residues known to be essential for its interaction with Fas with alanine, in this peptide, resulted in almost complete loss of binding to Fas. Computational optimization of the hAChE mimetic peptide yielded a variant with slightly improved affinity to Fas, indicating that more rounds of computational optimization will be required to obtain peptide variants with greatly improved affinity for Fas. CD spectra in the absence and presence of Fas point to conformational changes in the peptide upon binding to Fas. Furthermore, binding of the optimized hAChE mimetic peptide to Fas could be inhibited by hAChE, providing evidence for a hAChE‐specific peptide–Fas interaction. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
89.
Sulfurtransferases/rhodaneses (Str) comprise a group of enzymes widely distributed in all phyla which catalyze in vitro the
transfer of a sulfur atom from suitable sulfur donors to nucleophilic sulfur acceptors. The best characterized Str is bovine
rhodanese (EC 2.8.1.1) which catalyses in vitro the transfer of a sulfane sulfur atom from thiosulfate to cyanide, leading
to the formation of sulfite and thiocyanate. Plants as well as other organisms contain many proteins carrying a typical rhodanese
pattern or domain forming multi-protein families (MPF). Despite the presence of Str activities in many living organisms, the
physiological role of the members of this MPF has not been established unambiguously. While in mammals these proteins are
involved in the elimination of toxic cyanogenic compounds, their ubiquity suggests additional physiological functions. In
plants, Str are localized in the cytoplasm, mitochondria, plastids, and nucleus. Str probably also transfer reduced sulfur
onto substrates as large as peptides or proteins. Several studies in different organisms demonstrate a protein–protein interaction
with members of the thioredoxin MPF indicating a role of Str in maintenance of the cellular redox homeostasis. The increased
expression of several members of the Str MPF in various stress conditions could be a response to oxidative stress. In summary,
data indicate that Str are involved in various essential metabolic reactions. 相似文献
90.
Conrad C Wünsche A Tan TH Bulkescher J Sieckmann F Verissimo F Edelstein A Walter T Liebel U Pepperkok R Ellenberg J 《Nature methods》2011,8(3):246-249
Quantitative microscopy relies on imaging of large cell numbers but is often hampered by time-consuming manual selection of specific cells. The 'Micropilot' software automatically detects cells of interest and launches complex imaging experiments including three-dimensional multicolor time-lapse or fluorescence recovery after photobleaching in live cells. In three independent experimental setups this allowed us to statistically analyze biological processes in detail and is thus a powerful tool for systems biology. 相似文献