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101.
Zeitzer JM Buckmaster CL Lyons DM Mignot E 《American journal of physiology. Regulatory, integrative and comparative physiology》2007,293(4):R1736-R1742
The neuropeptides hypocretins (orexins), the loss of which results in the sleep disorder narcolepsy, are hypothesized to be involved in the consolidation of wakefulness and have been proposed to be part of the circadian-driven alertness signal. To elucidate the role of hypocretins in the consolidation of human wakefulness we examined the effect of wake extension on hypocretin-1 in squirrel monkeys, primates that consolidate wakefulness during the daytime as do humans. Wake was extended up to 7 h with hypocretin-1, cortisol, ghrelin, leptin, locomotion, and feeding, all being assayed. Hypocretin-1 (P < 0.01), cortisol (P < 0.001), and locomotion (P < 0.005) all increased with sleep deprivation, while ghrelin (P = 0.79) and leptin (P = 1.00) did not change with sleep deprivation. Using cross-correlation and multivariate modeling of these potential covariates along with homeostatic pressure (a measure of time awake/asleep), we found that time of day and homeostatic pressure together explained 44% of the variance in the hypocretin-1 data (P < 0.001), while cortisol did not significantly contribute to the overall hypocretin-1 variance. Locomotion during the daytime, but not during the nighttime, helped explain < 5% of the hypocretin-1 variance (P < 0.05). These data are consistent with earlier evidence indicating that in the squirrel monkey hypocretin-1 is mainly regulated by circadian inputs and homeostatic sleep pressure. Concomitants of wakefulness that affect hypocretin-1 in polyphasic species, such as locomotion, food intake, and food deprivation, likely have a more minor role in monophasic species, such as humans. 相似文献
102.
Biftu T Feng D Qian X Liang GB Kieczykowski G Eiermann G He H Leiting B Lyons K Petrov A Sinha-Roy R Zhang B Scapin G Patel S Gao YD Singh S Wu J Zhang X Thornberry NA Weber AE 《Bioorganic & medicinal chemistry letters》2007,17(1):49-52
Replacement of the triazolopiperazine ring of sitagliptin (DPP-4 IC(50)=18nM) with 3-(2,2,2-trifluoroethyl)-1,4-diazepan-2-one gave dipeptidyl peptidase IV (DPP-4) inhibitor 1 which is potent (DPP-4 IC(50)=2.6nM), selective, and efficacious in an oral glucose tolerance test in mice. It was selected for extensive preclinical development as a potential back-up candidate to sitagliptin. 相似文献
103.
Saltatory conduction in myelinated axons requires organization of the nodes of Ranvier, where voltage-gated sodium channels are prominently localized [1]. Previous results indicate that alphaII-spectrin, a component of the cortical cytoskeleton [2], is enriched at the paranodes [3, 4], which flank the node of Ranvier, but alphaII-spectrin's function has not been investigated. Starting with a genetic screen in zebrafish, we discovered in alphaII-spectrin (alphaII-spn) a mutation that disrupts nodal sodium-channel clusters in myelinated axons of the PNS and CNS. In alphaII-spn mutants, the nodal sodium-channel clusters are reduced in number and disrupted at early stages. Analysis of chimeric animals indicated that alphaII-spn functions autonomously in neurons. Ultrastructural studies show that myelin forms in the posterior lateral line nerve and in the ventral spinal cord in alphaII-spn mutants and that the node is abnormally long; these findings indicate that alphaII-spn is required for the assembly of a mature node of the correct length. We find that alphaII-spectrin is enriched in nodes and paranodes at early stages and that the nodal expression diminishes as nodes mature. Our results provide functional evidence that alphaII-spectrin in the axonal cytoskeleton is essential for stabilizing nascent sodium-channel clusters and assembling the mature node of Ranvier. 相似文献
104.
Kowalchick JE Leiting B Pryor KD Marsilio F Wu JK He H Lyons KA Eiermann GJ Petrov A Scapin G Patel RA Thornberry NA Weber AE Kim D 《Bioorganic & medicinal chemistry letters》2007,17(21):5934-5939
Various beta-amino amides containing triazolopiperazine heterocycles have been prepared and evaluated as potent, selective, orally active dipeptidyl peptidase IV (DPP-4) inhibitors. These compounds display excellent oral bioavailability and good overall pharmacokinetic profiles in preclinical species. Moreover, in vivo efficacy in an oral glucose tolerance test in lean mice is demonstrated. 相似文献
105.
Biftu T Scapin G Singh S Feng D Becker JW Eiermann G He H Lyons K Patel S Petrov A Sinha-Roy R Zhang B Wu J Zhang X Doss GA Thornberry NA Weber AE 《Bioorganic & medicinal chemistry letters》2007,17(12):3384-3387
Molecular modeling was used to design a rigid analog of sitagliptin 1. The X-ray crystal structure of sitagliptin bound to DPP-4 suggested that the central beta-amino butyl amide moiety could be replaced with a cyclohexylamine group. This was confirmed by structural analysis and the resulting analog 2a was synthesized and found to be a potent DPP-4 inhibitor (IC(50)=21 nM) with excellent in vivo activity and pharmacokinetic profile. 相似文献
106.
Mark T. Simmons Steve Windhager Paula Power Jason Lott Robert K. Lyons Carl Schwope 《Restoration Ecology》2007,15(4):662-669
Conservation of North American grasslands is hampered by the impact of invasive herbaceous species. Selective control of these plants, although desirable, is complicated by the shared physiology and phenology of the invader and the native components of the invaded plant community. Fortunately, there is evidence that some management practices, such as prescribed fire, herbicide, and mowing, can cause differential responses in native and invasive grassland species. However, timing of treatment is critical, and fire has been shown to increase rates of invasion when implemented during the dormant season. Bothriochloa ischaemum, an introduced C4 Eurasian grass is an increasing problem in grasslands, particularly in southern and central regions of North America. To date, there has been little success in effective selective control. Two invaded grassland sites representative of Blackland Prairie and Edwards Plateau ecoregions were subjected to two growing‐season prescribed fire treatments, single and double herbicide applications, and single and double mowing treatments. Mowing had no effect on either B. ischaemum or other dominant species at either site one‐year posttreatment. However, growing‐season fire and herbicide were both effective at reducing the abundance of B. ischaemum, with other codominant species responding either negatively to herbicide or neutrally or positively to fire. The vulnerability of B. ischaemum to growing‐season fire may be associated with the ecology of its native range. The negative growth response to growing‐season fire, combined with its lower implementation costs, indicates that this method warrants further investigation as a selective management tool for other problematic species in invaded grasslands. 相似文献
107.
Elizabeth D. Hughes Yun Yan Qu Suzanne J. Genik Robert H. Lyons Christopher D. Pacheco Andrew P. Lieberman Linda C. Samuelson Igor O. Nasonkin Sally A. Camper Margaret L. Van Keuren Thomas L. Saunders 《Mammalian genome》2007,18(8):549-558
Genetically modified mouse strains derived from embryonic stem (ES) cells are powerful tools for gene function analysis. ES
cells from the C57BL/6 mouse strain are not widely used to generate mouse models despite the advantage of a defined genetic
background. We assessed genetic variation in six such ES cell lines with 275 SSLP markers. Compared to C57BL/6, Bruce4 differed
at 34 SSLP markers and had significant heterozygosity on three chromosomes. BL/6#3 and Dale1 ES cell lines differed at only
3 SSLP makers. The C2 and WB6d ES cell lines differed at 6 SSLP markers. It is important to compare the efficiency of producing
mouse models with available C57BL/6 ES cells relative to standard 129 mouse strain ES cells. We assessed genetic stability
(the tendency of cells to become aneuploid) in 110 gene-targeted ES cell clones from the most widely used C57BL/6 ES cell
line, Bruce4, and 710 targeted 129 ES cell clones. Bruce4 clones were more likely to be aneuploid and unsuitable for ES cell-mouse
chimera production. Despite their tendency to aneuploidy and consequent inefficiency, use of Bruce4 ES cells can be valuable
for models requiring behavioral studies and other mouse models that benefit from a defined C57BL/6 background.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
108.
Growth rate of the Kuruma prawn, Marsupenaeus japonicus is an important economic trait, with larger animals commanding higher market prices. To identify gene markers associated
with growth, a genetic map of a full-sib F2 intercross family of M. japonicus has previously been generated and quantitative trait loci (QTL) influencing weight, total length, and carapace length were
identified. In this study, amplified fragment length polymorphism (AFLP) markers associated with the major QTL region, contributing
16% to phenotypic variation, were characterized. Flanking sequence has been obtained and allelic variants responsible for
segregation patterns of these markers have been identified. The genomic sequence surrounding the AFLP band 7.21a, residing
under the QTL peak, contains a gene sequence homologous to the elongation of very long chain fatty acids-like (ELOVL) protein family. A full-length mRNA (ELOVL-MJ) encoding this protein was isolated from M. japonicus, representing both the first ELOVL gene in crustacea and the first candidate gene identified via QTL studies in crustacea. 相似文献
109.
Esteban A. Terzo Shawn M. Lyons John S. Poulton Brenda R. S. Temple William F. Marzluff Robert J. Duronio 《Molecular biology of the cell》2015,26(8):1559-1574
Nuclear bodies (NBs) are structures that concentrate proteins, RNAs, and ribonucleoproteins that perform functions essential to gene expression. How NBs assemble is not well understood. We studied the Drosophila histone locus body (HLB), a NB that concentrates factors required for histone mRNA biosynthesis at the replication-dependent histone gene locus. We coupled biochemical analysis with confocal imaging of both fixed and live tissues to demonstrate that the Drosophila Multi Sex Combs (Mxc) protein contains multiple domains necessary for HLB assembly. An important feature of this assembly process is the self-interaction of Mxc via two conserved N-terminal domains: a LisH domain and a novel self-interaction facilitator (SIF) domain immediately downstream of the LisH domain. Molecular modeling suggests that the LisH and SIF domains directly interact, and mutation of either the LisH or the SIF domain severely impairs Mxc function in vivo, resulting in reduced histone mRNA accumulation. A region of Mxc between amino acids 721 and 1481 is also necessary for HLB assembly independent of the LisH and SIF domains. Finally, the C-terminal 195 amino acids of Mxc are required for recruiting FLASH, an essential histone mRNA-processing factor, to the HLB. We conclude that multiple domains of the Mxc protein promote HLB assembly in order to concentrate factors required for histone mRNA biosynthesis. 相似文献
110.