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排序方式: 共有421条查询结果,搜索用时 15 毫秒
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Colin W. Rundel Michael B. Wunder Allison H. Alvarado Kristen C. Ruegg Ryan Harrigan Andrew Schuh Jeffrey F. Kelly Rodney B. Siegel David F. DeSante Thomas B. Smith John Novembre 《Molecular ecology》2013,22(16):4163-4176
Methods for determining patterns of migratory connectivity in animal ecology have historically been limited due to logistical challenges. Recent progress in studying migratory bird connectivity has been made using genetic and stable‐isotope markers to assign migratory individuals to their breeding grounds. Here, we present a novel Bayesian approach to jointly leverage genetic and isotopic markers and we test its utility on two migratory passerine bird species. Our approach represents a principled model‐based combination of genetic and isotope data from samples collected on the breeding grounds and is able to achieve levels of assignment accuracy that exceed those of either method alone. When applied at large scale the method can reveal specific migratory connectivity patterns. In Wilson's warblers (Wilsonia pusilla), we detect a subgroup of birds wintering in Baja that uniquely migrate preferentially from the coastal Pacific Northwest. Our approach is implemented in a way that is easily extended to accommodate additional sources of information (e.g. bi‐allelic markers, species distribution models, etc.) or adapted to other species or assignment problems. 相似文献
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To explore the possibility of using restriction enzymes in a synthetic biology based on artificially expanded genetic information systems (AEGIS), 24 type-II restriction endonucleases (REases) were challenged to digest DNA duplexes containing recognition sites where individual Cs and Gs were replaced by the AEGIS nucleotides Z and P [respectively, 6-amino-5-nitro-3-(1'-β-D-2'-deoxyribofuranosyl)-2(1H)-pyridone and 2-amino-8-(1'-β-D-2'-deoxyribofuranosyl)-imidazo[1,2-a]-1,3,5-triazin-4(8H)-one]. These AEGIS nucleotides implement complementary hydrogen bond donor-donor-acceptor and acceptor-acceptor-donor patterns. Results allowed us to classify type-II REases into five groups based on their performance, and to infer some specifics of their interactions with functional groups in the major and minor grooves of the target DNA. For three enzymes among these 24 where crystal structures are available (BcnI, EcoO109I and NotI), these interactions were modeled. Further, we applied a type-II REase to quantitate the fidelity polymerases challenged to maintain in a DNA duplex C:G, T:A and Z:P pairs through repetitive PCR cycles. This work thus adds tools that are able to manipulate this expanded genetic alphabet in vitro, provides some structural insights into the working of restriction enzymes, and offers some preliminary data needed to take the next step in synthetic biology to use an artificial genetic system inside of living bacterial cells. 相似文献
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The maintenance of organs and their regeneration in case of injury are crucial to the survival of all animals. High rates of tissue turnover and nearly unlimited regenerative capabilities make planarian flatworms an ideal system with which to investigate these important processes, yet little is known about the cell biology and anatomy of their organs. Here we focus on the planarian excretory system, which consists of internal protonephridial tubules. We find that these assemble into complex branching patterns with a stereotyped succession of cell types along their length. Organ regeneration is likely to originate from a precursor structure arising in the blastema, which undergoes extensive branching morphogenesis. In an RNAi screen of signaling molecules, we identified an EGF receptor (Smed-EGFR-5) as a crucial regulator of branching morphogenesis and maintenance. Overall, our characterization of the planarian protonephridial system establishes a new paradigm for regenerative organogenesis and provides a platform for exploring its functional and evolutionary homologies with vertebrate excretory systems. 相似文献
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Erin R. Aho Jing Wang Rocco D. Gogliotti Gregory C. Howard Jason Phan Pankaj Acharya Jonathan D. Macdonald Ken Cheng Shelly L. Lorey Bin Lu Sabine Wenzel Audra M. Foshage Joseph Alvarado Feng Wang J. Grace Shaw Bin Zhao April M. Weissmiller Lance R. Thomas William P. Tansey 《Cell reports》2019,26(11):2916-2928.e13
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Valerie M. Kramlinger Mónica Alvarado Rojas Tatsuyuki Kanamori F. Peter Guengerich 《The Journal of biological chemistry》2015,290(33):20200-20210
Morphine, first characterized in opium from the poppy Papaver somniferum, is one of the strongest known analgesics. Endogenous morphine has been identified in several mammalian cells and tissues. The synthetic pathway of morphine in the opium poppy has been elucidated. The presence of common intermediates in plants and mammals suggests that biosynthesis occurs through similar pathways (beginning with the amino acid l-tyrosine), and the pathway has been completely delineated in plants. Some of the enzymes in the mammalian pathway have been identified and characterized. Two of the latter steps in the morphine biosynthesis pathway are demethylation of thebaine at the O3- and the O6-positions, the latter of which has been difficult to demonstrate. The plant enzymes responsible for both the O3-demethylation and the O6-demethylation are members of the FeII/α-ketoglutarate-dependent dioxygenase family. Previous studies showed that human cytochrome P450 (P450) 2D6 can catalyze thebaine O3-demethylation. We report that demethylation of thebaine at the O6-position is selectively catalyzed by human P450s 3A4 and 3A5, with the latter being more efficient, and rat P450 3A2. Our results do not support O6-demethylation of thebaine by an FeII/α-ketoglutarate-dependent dioxygenase. In rat brain microsomes, O6-demethylation was inhibited by ketoconazole, but not sulfaphenazole, suggesting that P450 3A enzymes are responsible for this activity in the brain. An alternate pathway to morphine, oripavine O6-demethylation, was not detected. The major enzymatic steps in mammalian morphine synthesis have now been identified. 相似文献