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排序方式: 共有211条查询结果,搜索用时 15 毫秒
21.
22.
Schuler AM Westberry JM Parks VL Kuehl TJ Abee CR 《Journal of medical primatology》2007,36(2):113-117
The objective of this study was to test whether ultrasound-guided oocyte retrieval is an effective mechanism for collecting oocytes in squirrel monkeys. Although ultrasound-guided follicular aspiration has been described in Old World primates, oocyte retrieval in New World primates is typically performed via laparoscopy or laparotomy. However, these procedures, especially the first, can be invasive. Ultrasound has been used for pregnancy monitoring in multiple species of primates including Saimiri spp. Transabdominal ultrasound as a diagnostic tool is non-invasive. Transabdominal ultrasound was utilized to visualize ovarian follicles during aspiration under light anesthesia. This procedure resulted in collection of a total of 29 oocytes from six animals with minimal post-procedural pain. Manipulated animals were returned to the social group the same day. 相似文献
23.
Hansen DR Dastidar SG Cai Z Penaflor C Kuehl JV Boore JL Jansen RK 《Molecular phylogenetics and evolution》2007,45(2):547-563
We have determined the complete chloroplast genome sequences of four early-diverging lineages of angiosperms, Buxus (Buxaceae), Chloranthus (Chloranthaceae), Dioscorea (Dioscoreaceae), and Illicium (Schisandraceae), to examine the organization and evolution of plastid genomes and to estimate phylogenetic relationships among angiosperms. For the most part, the organization of these plastid genomes is quite similar to the ancestral angiosperm plastid genome with a few notable exceptions. Dioscorea has lost one protein-coding gene, rps16; this gene loss has also happened independently in four other land plant lineages, liverworts, conifers, Populus, and legumes. There has also been a small expansion of the inverted repeat (IR) in Dioscorea that has duplicated trnH-GUG. This event has also occurred multiple times in angiosperms, including in monocots, and in the two basal angiosperms Nuphar and Drimys. The Illicium chloroplast genome is unusual by having a 10 kb contraction of the IR. The four taxa sequenced represent key groups in resolving phylogenetic relationships among angiosperms. Illicium is one of the basal angiosperms in the Austrobaileyales, Chloranthus (Chloranthales) remains unplaced in angiosperm classifications, and Buxus and Dioscorea are early-diverging eudicots and monocots, respectively. We have used sequences for 61 shared protein-coding genes from these four genomes and combined them with sequences from 35 other genomes to estimate phylogenetic relationships using parsimony, likelihood, and Bayesian methods. There is strong congruence among the trees generated by the three methods, and most nodes have high levels of support. The results indicate that Amborella alone is sister to the remaining angiosperms; the Nymphaeales represent the next-diverging clade followed by Illicium; Chloranthus is sister to the magnoliids and together this group is sister to a large clade that includes eudicots and monocots; and Dioscorea represents an early-diverging lineage of monocots just internal to Acorus. 相似文献
24.
Beste DJ Hooper T Stewart G Bonde B Avignone-Rossa C Bushell ME Wheeler P Klamt S Kierzek AM McFadden J 《Genome biology》2007,8(5):R89
Background
An impediment to the rational development of novel drugs against tuberculosis (TB) is a general paucity of knowledge concerning the metabolism of Mycobacterium tuberculosis, particularly during infection. Constraint-based modeling provides a novel approach to investigating microbial metabolism but has not yet been applied to genome-scale modeling of M. tuberculosis. 相似文献25.
JI Priego AG Lucas-Cuevas I Aparicio JV Giménez JM Cortell-Tormo P Pérez-Soriano 《Biology of sport / Institute of Sport》2015,32(3):219-223
The use of graduated compression stockings (GCS) in sport has been increasing in the last years due to their potential positive effects for athletes. However, there is little evidence to support whether these types of garments actually improve cardiorespiratory performance. The aim of this study was to examine the cardiorespiratory responses of GCS during running after three weeks of regular use. Twenty recreational runners performed three tests on different days: test 1) – a 5-min maximal effort run in order to determine the participants’ maximal aerobic speed; and tests 2) and 3) – a fatigue running test of 30 minutes at 80% of their maximal aerobic speed with either GCS or PLACEBO stockings at random. Cardiorespiratory parameters (minute ventilation, heart rate, relative oxygen consumption, relative carbon dioxide production, ventilatory equivalents for oxygen and carbon dioxide, and oxygen pulse) were measured. Before each test in the laboratory, the participants trained with the randomly assigned stockings (GCS or PLACEBO) for three weeks. No significant differences between GCS and PLACEBO were found in any of the cardiorespiratory parameters. In conclusion, the present study provides evidence that running with GCS for three weeks does not influence cardiorespiratory parameters in recreational runners. 相似文献
26.
M Montenegro S Llambí G Castro N Barlocco A Vadell V Landi JV Delgado A Martínez 《Genetics and molecular biology》2015,38(1):48-54
In this study, we genetically characterized the Uruguayan pig breed Pampa Rocha.
Genetic variability was assessed by analyzing a panel of 25 microsatellite markers
from a sample of 39 individuals. Pampa Rocha pigs showed high genetic variability
with observed and expected heterozygosities of 0.583 and 0.603, respectively. The
mean number of alleles was 5.72. Twenty-four markers were polymorphic, with 95.8% of
them in Hardy Weinberg equilibrium. The level of endogamy was low (FIS =
0.0475). A factorial analysis of correspondence was used to assess the genetic
differences between Pampa Rocha and other pig breeds; genetic distances were
calculated, and a tree was designed to reflect the distance matrix. Individuals were
also allocated into clusters. This analysis showed that the Pampa Rocha breed was
separated from the other breeds along the first and second axes. The
neighbour-joining tree generated by the genetic distances DA showed
clustering of Pampa Rocha with the Meishan breed. The allocation of individuals to
clusters showed a clear separation of Pampa Rocha pigs. These results provide
insights into the genetic variability of Pampa Rocha pigs and indicate that this
breed is a well-defined genetic entity. 相似文献
27.
The Vibrios are a unique group of bacteria inhabiting a vast array of aquatic environments. Many Vibrio species are capable of infecting a wide assortment of hosts. Some of these species include V. parahaemolyticus, V. alginolyticus, V. vulnificus, V. anguillarum, and V. cholerae. The ability of these organisms to utilize iron is essential in establishing both an infection in their hosts as well as
surviving in the environment. Bacteria are able to sequester iron through the secretion of low molecular weight iron chelators
termed siderophores. The iron-siderophore complexes are bound by specific outer membrane receptors and are brought through
both the outer and inner membranes of the cell. The energy needed to drive this active transport is achieved through the TonB
energy transduction system. When first elucidated in E. coli, the TonB system was shown to be a three protein complex consisting of TonB, ExbB and ExbD. Most Vibrio species carry two TonB systems. The second TonB system includes a fourth protein; TtpC, which is essential for TonB2 mediated
iron transport. Some Vibrio species have been shown to carry a third TonB system that also includes a TtpC protein. 相似文献
28.
The presence of researchers, ecotourists or rangers inside protected areas is generally assumed to provide a protective effect for wildlife populations, mainly by reducing poaching pressure. However, this assumption has rarely been empirically tested. Here, we evaluate and quantify the conservation benefits of the presence of a long-term research area in Taï National Park, Côte d''Ivoire. A wildlife survey following 225 km of line transects revealed considerably higher primate and duiker encounter rates within the research area when compared with adjacent areas. This positive effect was particularly pronounced for threatened and over-harvested species, such as the endangered red colobus monkey (Procolobus badius). This pattern was clearly mirrored by a reversed gradient in signs of poaching, which decreased towards and inside the research area, a trend that was also supported with park-wide data. This study demonstrates that even relatively simple evidence-based analytical approaches can bridge the gap between conservation theory and practice. In addition, it emphasizes the value of establishing long-term research sites as an integral part of protected area management. 相似文献
29.
Identifying the basal angiosperm node in chloroplast genome phylogenies: sampling one's way out of the Felsenstein zone 总被引:11,自引:0,他引:11
Leebens-Mack J Raubeson LA Cui L Kuehl JV Fourcade MH Chumley TW Boore JL Jansen RK depamphilis CW 《Molecular biology and evolution》2005,22(10):1948-1963
While there has been strong support for Amborella and Nymphaeales (water lilies) as branching from basal-most nodes in the angiosperm phylogeny, this hypothesis has recently been challenged by phylogenetic analyses of 61 protein-coding genes extracted from the chloroplast genome sequences of Amborella, Nymphaea, and 12 other available land plant chloroplast genomes. These character-rich analyses placed the monocots, represented by three grasses (Poaceae), as sister to all other extant angiosperm lineages. We have extracted protein-coding regions from draft sequences for six additional chloroplast genomes to test whether this surprising result could be an artifact of long-branch attraction due to limited taxon sampling. The added taxa include three monocots (Acorus, Yucca, and Typha), a water lily (Nuphar), a ranunculid (Ranunculus), and a gymnosperm (Ginkgo). Phylogenetic analyses of the expanded DNA and protein data sets together with microstructural characters (indels) provided unambiguous support for Amborella and the Nymphaeales as branching from the basal-most nodes in the angiosperm phylogeny. However, their relative positions proved to be dependent on the method of analysis, with parsimony favoring Amborella as sister to all other angiosperms and maximum likelihood (ML) and neighbor-joining methods favoring an Amborella + Nymphaeales clade as sister. The ML phylogeny supported the later hypothesis, but the likelihood for the former hypothesis was not significantly different. Parametric bootstrap analysis, single-gene phylogenies, estimated divergence dates, and conflicting indel characters all help to illuminate the nature of the conflict in resolution of the most basal nodes in the angiosperm phylogeny. Molecular dating analyses provided median age estimates of 161 MYA for the most recent common ancestor (MRCA) of all extant angiosperms and 145 MYA for the MRCA of monocots, magnoliids, and eudicots. Whereas long sequences reduce variance in branch lengths and molecular dating estimates, the impact of improved taxon sampling on the rooting of the angiosperm phylogeny together with the results of parametric bootstrap analyses demonstrate how long-branch attraction might mislead genome-scale phylogenetic analyses. 相似文献
30.
Evidence for selection on synonymous mutations affecting stability of mRNA secondary structure in mammals
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