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排序方式: 共有181条查询结果,搜索用时 15 毫秒
1.
Matthew Westover Jared Baxter Rick Baxter Casey Day Ryan Jensen Steve Petersen Randy Larsen 《PloS one》2016,11(5)
Greater sage-grouse populations have decreased steadily since European settlement in western North America. Reduced availability of brood-rearing habitat has been identified as a limiting factor for many populations. We used radio-telemetry to acquire locations of sage-grouse broods from 1998 to 2012 in Strawberry Valley, Utah. Using these locations and remotely-sensed NAIP (National Agricultural Imagery Program) imagery, we 1) determined which characteristics of brood-rearing habitat could be used in widely available, high resolution imagery 2) assessed the spatial extent at which sage-grouse selected brood-rearing habitat, and 3) created a predictive habitat model to identify areas of preferred brood-rearing habitat. We used AIC model selection to evaluate support for a list of variables derived from remotely-sensed imagery. We examined the relationship of these explanatory variables at three spatial extents (45, 200, and 795 meter radii). Our top model included 10 variables (percent shrub, percent grass, percent tree, percent paved road, percent riparian, meters of sage/tree edge, meters of riparian/tree edge, distance to tree, distance to transmission lines, and distance to permanent structures). Variables from each spatial extent were represented in our top model with the majority being associated with the larger (795 meter) spatial extent. When applied to our study area, our top model predicted 75% of naïve brood locations suggesting reasonable success using this method and widely available NAIP imagery. We encourage application of our methodology to other sage-grouse populations and species of conservation concern. 相似文献
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3.
Direct sequencing of the mitochondrial displacement loop (D-loop) of shrews
(genus Sorex) for the region between the tRNA(Pro) and the conserved
sequence block-F revealed variable numbers of 79-bp tandem repeats. These
repeats were found in all 19 individuals sequenced, representing three
subspecies and one closely related species of the masked shrew group (Sorex
cinereus cinereus, S. c. miscix, S. c. acadicus, and S. haydeni) and an
outgroup, the pygmy shrew (S. hoyi). Each specimen also possessed an
adjacent 76-bp imperfect copy of the tandem repeats. One individual was
heteroplasmic for length variants consisting of five and seven copies of
the 79-bp tandem repeat. The sequence of the repeats is conducive to the
formation of secondary structure. A termination-associated sequence is
present in each of the repeats and in a unique sequence region 5' to the
tandem array as well. Mean genetic distance between the masked shrew taxa
and the pygmy shrew was calculated separately for the unique sequence
region, one of the tandem repeats, the imperfect repeat, and these three
regions combined. The unique sequence region evolved more rapidly than the
tandem repeats or the imperfect repeat. The small genetic distance between
pairs of tandem repeats within an individual is consistent with a model of
concerted evolution. Repeats are apparently duplicated and lost at a high
rate, which tends to homogenize the tandem array. The rate of D- loop
sequence divergence between the masked and pygmy shrews is estimated to be
15%-20%/Myr, the highest rate observed in D-loops of mammals. Rapid
sequence evolution in shrews may be due either to their high metabolic rate
and short generation time or to the presence of variable numbers of tandem
repeats.
相似文献
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5.
大鼠胼胝体内神经肽Y免疫反应阳性纤维的发育 总被引:1,自引:0,他引:1
本实验用免疫组织化学ABC法研究了大鼠胼胝体内神经肽Y免疫反应阳性(NPY-IR)纤维的生后发育。结果发现,许多NPY-IR纤维在大鼠出生时便存在于胼胝体内。NPY-IR胼胝体纤维的密度在生后1周内继续逐渐增高,在第2周内达到最高峰。之后,NPY-IR胼胝体纤维的密度逐渐下降,至第3周末时接近成年时的水平,即仅有少量NPY-IR纤维存在于胼胝体内。这些结果提示在大鼠早期生后发育过程中许多NPY-IR胼胝体纤维是暂时性的,其作用可能与大脑皮质的机能发育有关。 相似文献
6.
7.
Colin Bonner Nina A. Sokolov Sally Erin Westover Michelle Ho Arthur E. Weis 《Ecology and evolution》2019,9(7):3770-3783
Gene flow between populations can allow the spread of beneficial alleles and genetic diversity between populations, with importance to conservation, invasion biology, and agriculture. Levels of gene flow between populations vary not only with distance, but also with divergence in reproductive phenology. Since phenology is often locally adapted, arriving migrants may be reproductively out of synch with residents, which can depress realized gene flow. In flowering plants, the potential impact of phenological divergence on hybridization between populations can be predicted from overlap in flowering schedules—the daily count of flowers capable of pollen exchange—between a resident and migrant population. The accuracy of this prospective hybridization estimate, based on parental phenotypes, rests upon the assumptions of unbiased pollen transfer between resident and migrant active flowers. We tested the impact of phenological divergence on resident–migrant mating frequencies in experiments that mimicked a single large gene flow event. We first prospectively estimated mating frequencies two lines of Brassica rapaselected or early and late flowering. We then estimated realized mating frequencies retrospectively through progeny testing. The two estimates strongly agreed in a greenhouse experiment, where procedures ensured saturating, unbiased pollination. Under natural pollination in the field, the rate of resident–migrant mating, was lower than estimated by phenological divergence alone, although prospective and retrospective estimates were correlated. In both experiments, differences between residents and migrants in flowering schedule shape led to asymmetric hybridization. Results suggest that a prospective estimate of hybridization based on mating schedules can be a useful, although imperfect, tool for evaluating potential gene flow. They also illustrate the impact of mating phenology on the magnitude and symmetry of reproductive isolation. 相似文献
8.
Zhang HC Ye H Conway BR Derian CK Addo MF Kuo GH Hecker LR Croll DR Li J Westover L Xu JZ Look R Demarest KT Andrade-Gordon P Damiano BP Maryanoff BE 《Bioorganic & medicinal chemistry letters》2004,14(12):3245-3250
A novel series of acyclic 3-(7-azaindolyl)-4-(aryl/heteroaryl)maleimides was synthesized and evaluated for activity against GSK-3beta and selectivity versus PKC-betaII, as well as a broad panel of protein kinases. Compounds 14 and 17c potently inhibited GSK-3beta (IC(50)=7 and 26 nM, respectively) and exhibited excellent selectivity over PKC-betaII (325 and >385-fold, respectively). Compound 17c was also highly selective against 68 other protein kinases. In a cell-based functional assay, both 14 and 17c effectively increased glycogen synthase activity by inhibiting GSK-3beta. 相似文献
9.
O'Neill DJ Shen L Prouty C Conway BR Westover L Xu JZ Zhang HC Maryanoff BE Murray WV Demarest KT Kuo GH 《Bioorganic & medicinal chemistry》2004,12(12):3167-3185
Two approaches were developed to synthesize the novel 7-azaindolyl-heteroarylmaleimides. The first approach was based upon the palladium-catalyzed Suzuki cross-coupling or Stille cross-coupling of 2-chloro-maleimide 5 with various arylboronic acids or arylstannanes. The second approach was based upon the condensation of ethyl 7-azaindolyl-3-glyoxylate 12 with various acetamides. The hydroxypropyl-substituted 7-azaindolylmaleimide template was first used to screen different heteroaryls attached to the maleimide. Replacement of hydroxypropyl with different chain lengths and different functional groups were studied next. Many compounds synthesized were demonstrated to have high potency at GSK-3beta, good GS activity in HEK293 cells and good to excellent metabolic stability in human liver microsomes. Three representative compounds (21, 33, and 34) were demonstrated to have good selectivity against a panel of 80 kinase assays. Among them, compound 33 exhibited very weak inhibitions at the other 79 kinase assays, and behaved as a highly selective GSK-3beta inhibitor. 相似文献
10.
Molecular evolution of viral fusion and matrix protein genes and phylogenetic relationships among the Paramyxoviridae 总被引:5,自引:0,他引:5
Phylogenetic relationships among the Paramyxoviridae, a broad family of viruses whose members cause devastating diseases of wildlife, livestock, and humans, were examined with both fusion (F) and matrix (M) protein-coding sequences. Neighbor-joining trees of F and M protein sequences showed that the Paramyxoviridae was divided into the two traditionally recognized subfamilies, the Paramyxovirinae and the Pneumovirinae. Within the Paramyxovirinae, the results also showed groups corresponding to three currently recognized genera: Respirovirus, Morbillivirus, and Rubulavirus. The relationships among the three genera of the Paramyxovirinae were resolved with M protein sequences and there was significant bootstrap support (100%) showing that members of the genus Respirovirus and the genus Morbillivirus were more closely related to each other than to members of the genus Rubulavirus. Both F and M phylogenies showed that Newcastle disease virus (NDV) was more closely related to the genus Rubulavirus than to the other two genera but were consistent with the proposal (B. S. Seal et al., 2000, Virus Res. 66, 1-11) that NDV be classified as a separate genus within the Paramyxovirinae. Both F and M phylogenies were also consistent with the proposal (L. Wang et al., 2000, J. Virol 74, 9972-9979) that Hendra virus be classified as a new genus closely related and basal to the genus Morbillivirus. Rinderpest was most closely related to measles and a more derived virus than to canine distemper virus, phocine distemper virus, or dolphin morbillivirus. 相似文献