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Phylogeography and regional endemism of a passively dispersing zooplankter: mitochondrial DNA variation in rotifer resting egg banks. 总被引:13,自引:0,他引:13
A Gómez G R Carvalho D H Lunt 《Proceedings. Biological sciences / The Royal Society》2000,267(1458):2189-2197
We investigated the phylogeography of the salt water rotifer Brachionus plicatilis, a cyclical parthenogen with passive dispersal mechanisms, using resting eggs recovered from saline lake sediments. Individual resting eggs were obtained from a large selection of lakes which were representative of five endorheic basins and the chain of coastal ponds in the Iberian Peninsula. The novel use of resting eggs allows the integration of seasonal and annual variations as well as the impact of stochastic effects such as drift and local extinction. A 653 bp fragment of the mitochondrial cytochrome oxidase subunit I (COI) gene was sequenced from 98 eggs. Our results revealed a deep phylogeographical structure in this species, with a division into two main lineages with distinct geographical distributions, which probably diverged at the beginning of the Pleistocene period. Most of the mitochondrial DNA haplotypes were restricted to single lakes. Nested clade analysis supported Early Pleistocene fragmentation of populations, low gene flow and some long-distance colonization. These conclusions contrast strongly with previous ideas on rotifer biogeography and this pattern is consistent with a recolonization of the Iberian Peninsula from two glacial refugia. The results provide new insights into the processes responsible for the genetic diversification of passive dispersers, a life-history trait typical of zooplanktonic biotas. 相似文献
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Tracking elusive cargo: Illuminating spatio‐temporal Type 3 effector protein dynamics using reporters 下载免费PDF全文
Type 3 secretion systems form an integral part of the arsenal of many pathogenic bacteria. These injection machines, together with their cargo of subversive effector proteins, are capable of manipulating the cellular environment of the host in order to ensure persistence of the pathogen. In order to fully appreciate the functions of Type 3 effectors, it is necessary to gain spatio‐temporal knowledge of each effector during the process of infection. A number of genetic modifications have been exploited in order to reveal effector protein secretion, translocation and subsequent activity, and localisation within host cells. In this review, we will discuss the many available approaches for tracking effector protein dynamics and discuss the challenges faced to improve the current technologies and gain a clearer picture of effector protein function. 相似文献
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The specific binding of the muscarinic cholinergic ligand N-methylscopolamine to human foetal brain has been measured. A level of binding of 64 pmol/g protein was found with a dissociation constant, Kd of 0.27 nM. Values of 0.17 nM min?1 and 0.048 min?1 for the association rate constant, Kon, and the dissociation rate constant Koff respectively, were obtained. The pharmacological properties of the binding site were found to be very similar to those reported for muscarinic receptors from adult mammalian brain except that the binding of pirenzepine and the nicotinic antagonists d-tubocurarine and decamethonium shows differences from that seen in adult brain. 相似文献
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Gao Y Pagnon J Feng HC Konstantopolous N Jowett JB Walder K Collier GR 《Biochemical and biophysical research communications》2007,356(3):636-641
SEPS1 (also called selenoprotein S, SelS, Tanis or VIMP) is a selenoprotein, localized predominantly in the ER membrane and also on the cell surface. In this report, we demonstrate that SEPS1 protein is also secreted from hepatoma cells but not from five other types of cells examined. The secretion can be abolished by the ER-Golgi transport inhibitor Brefeldin A and by the protein synthesis inhibitor cycloheximide. Using a sandwich ELISA, SEPS1 was detected in the sera of 65 out of 209 human subjects (31.1%, average=15.7+/-1.1 ng/mL). Fractionation of human serum indicated that SEPS1 was associated with LDL and possibly with VLDL. The function of plasma SEPS1 is unclear but may be related to lipoprotein metabolism. 相似文献
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An E. coli expression system optimized for DELLA proteins 总被引:1,自引:0,他引:1
Sun X Frearson N Kirk C Jones WT Harvey D Rakonjac J Foster T Al-Samarrai T 《Protein expression and purification》2008,58(1):168-174
The DELLA proteins are involved in regulation of plant growth in response to phytohormonal signals such as GA, ethylene, and auxin. They have become one of most challenging and active area of research due to their fundamental roles in plant biology. Here, we describe the first successful expression of the N-terminal domains of DELLA proteins of Arabidopsis thaliana and Malus domestica in Escherichia coli system which will be used to produce monoclonal antibodies for profiling protein micro-arrays. Optimizations of the cloning, expression, and purification using specific tags have been discussed. 相似文献