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991.
992.
Prashant P. Sharma Oscar A. Tarazona Davys H. Lopez Evelyn E. Schwager Martin J. Cohn Ward C. Wheeler Cassandra G. Extavour 《Proceedings. Biological sciences / The Royal Society》2015,282(1808)
The segmental architecture of the arthropod head is one of the most controversial topics in the evolutionary developmental biology of arthropods. The deutocerebral (second) segment of the head is putatively homologous across Arthropoda, as inferred from the segmental distribution of the tripartite brain and the absence of Hox gene expression of this anterior-most, appendage-bearing segment. While this homology statement implies a putative common mechanism for differentiation of deutocerebral appendages across arthropods, experimental data for deutocerebral appendage fate specification are limited to winged insects. Mandibulates (hexapods, crustaceans and myriapods) bear a characteristic pair of antennae on the deutocerebral segment, whereas chelicerates (e.g. spiders, scorpions, harvestmen) bear the eponymous chelicerae. In such hexapods as the fruit fly, Drosophila melanogaster, and the cricket, Gryllus bimaculatus, cephalic appendages are differentiated from the thoracic appendages (legs) by the activity of the appendage patterning gene homothorax (hth). Here we show that embryonic RNA interference against hth in the harvestman Phalangium opilio results in homeonotic chelicera-to-leg transformations, and also in some cases pedipalp-to-leg transformations. In more strongly affected embryos, adjacent appendages undergo fusion and/or truncation, and legs display proximal defects, suggesting conservation of additional functions of hth in patterning the antero-posterior and proximo-distal appendage axes. Expression signal of anterior Hox genes labial, proboscipedia and Deformed is diminished, but not absent, in hth RNAi embryos, consistent with results previously obtained with the insect G. bimaculatus. Our results substantiate a deep homology across arthropods of the mechanism whereby cephalic appendages are differentiated from locomotory appendages. 相似文献
993.
H. Charles J. Godfray Tjeerd Blacquière Linda M. Field Rosemary S. Hails Simon G. Potts Nigel E. Raine Adam J. Vanbergen Angela R. McLean 《Proceedings. Biological sciences / The Royal Society》2015,282(1818)
A summary is provided of recent advances in the natural science evidence base concerning the effects of neonicotinoid insecticides on insect pollinators in a format (a ‘restatement'') intended to be accessible to informed but not expert policymakers and stakeholders. Important new studies have been published since our recent review of this field (Godfray et al. 2014 Proc. R. Soc. B 281, 20140558. (doi:10.1098/rspb.2014.0558)) and the subject continues to be an area of very active research and high policy relevance. 相似文献
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Jo?lle Rosseels Jeff Van den Brande Marie Violet Dirk Jacobs Pierre Grognet Juan Lopez Isabelle Huvent Marina Caldara Erwin Swinnen Anthony Papegaey Rapha?lle Caillierez Valerie Buée-Scherrer Sebastiaan Engelborghs Guy Lippens Morvane Colin Luc Buée Marie-Christine Galas Eugeen Vanmechelen Joris Winderickx 《The Journal of biological chemistry》2015,290(7):4059-4074
A link between Tau phosphorylation and aggregation has been shown in different models for Alzheimer disease, including yeast. We used human Tau purified from yeast models to generate new monoclonal antibodies, of which three were further characterized. The first antibody, ADx201, binds the Tau proline-rich region independently of the phosphorylation status, whereas the second, ADx215, detects an epitope formed by the Tau N terminus when Tau is not phosphorylated at Tyr18. For the third antibody, ADx210, the binding site could not be determined because its epitope is probably conformational. All three antibodies stained tangle-like structures in different brain sections of THY-Tau22 transgenic mice and Alzheimer patients, and ADx201 and ADx210 also detected neuritic plaques in the cortex of the patient brains. In hippocampal homogenates from THY-Tau22 mice and cortex homogenates obtained from Alzheimer patients, ADx215 consistently stained specific low order Tau oligomers in diseased brain, which in size correspond to Tau dimers. ADx201 and ADx210 additionally reacted to higher order Tau oligomers and presumed prefibrillar structures in the patient samples. Our data further suggest that formation of the low order Tau oligomers marks an early disease stage that is initiated by Tau phosphorylation at N-terminal sites. Formation of higher order oligomers appears to require additional phosphorylation in the C terminus of Tau. When used to assess Tau levels in human cerebrospinal fluid, the antibodies permitted us to discriminate patients with Alzheimer disease or other dementia like vascular dementia, indicative that these antibodies hold promising diagnostic potential. 相似文献
997.
Fifty Ways To Inhibit Motility via Cyclic Di-GMP: the Emerging Pseudomonas aeruginosa Swarming Story
There are numerous ways by which cyclic dimeric GMP (c-di-GMP) inhibits motility. Kuchma et al. (S. L. Kuchma, N. J. Delalez, L. M. Filkins, E. A. Snavely, J. P. Armitage, and G. A. O''Toole, J. Bacteriol. 197:420–430, 2015, http://dx.doi.org/10.1128/JB.02130-14) offer a new, previously unseen way of swarming motility inhibition in Pseudomonas aeruginosa PA14. This bacterium possesses a single flagellum with one rotor and two sets of stators, only one of which can provide torque for swarming. The researchers discovered that elevated levels of c-di-GMP inhibit swarming by skewing stator selection in favor of the nonfunctional, “bad” stators. 相似文献
998.
Julian Brenig Susanne de Boor Philipp Knyphausen Nora Kuhlmann Sarah Wroblowski Linda Baldus Lukas Scislowski Oliver Artz Philip Trauschies Ulrich Baumann Ines Neundorf Michael Lammers 《The Journal of biological chemistry》2015,290(23):14314-14327
Diaphanous-related formins are eukaryotic actin nucleation factors regulated by an autoinhibitory interaction between the N-terminal RhoGTPase-binding domain (mDiaN) and the C-terminal Diaphanous-autoregulatory domain (DAD). Although the activation of formins by Rho proteins is well characterized, its inactivation is only marginally understood. Recently, liprin-α3 was shown to interact with mDia1. Overexpression of liprin-α3 resulted in a reduction of the cellular actin filament content. The molecular mechanisms of how liprin-α3 exerts this effect and counteracts mDia1 activation by RhoA are unknown. Here, we functionally and structurally define a minimal liprin-α3 core region, sufficient to recapitulate the liprin-α3 determined mDia1-respective cellular functions. We show that liprin-α3 alters the interaction kinetics and thermodynamics of mDiaN with RhoA·GTP and DAD. RhoA displaces liprin-α3 allosterically, whereas DAD competes with liprin-α3 for a highly overlapping binding site on mDiaN. Liprin-α3 regulates actin polymerization by lowering the regulatory potency of RhoA and DAD on mDiaN. We present a model of a mechanistically unexplored and new aspect of mDiaN regulation by liprin-α3. 相似文献
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