The aim of this study was to understand the mandible of the giant panda in morphometric terms to explore differences between the giant panda and other carnivores distributed in China, in terms of functional adaptation...
详细信息
The aim of this study was to understand the mandible of the giant panda in morphometric terms to explore differences between the giant panda and other carnivores distributed in China, in terms of functional adaptation. Twelve mandibular variables were studied using bivariate (allometry) and multivariate (principal components analysis, PCA, and discriminant functional analysis, DFA) tools. When deviations were produced from allometric baselines consisting of all the species studied, the giant panda displayed a much more developed mandibular structure than the bear, leopard, and tiger. This may be related to its specific dietary preference for bamboo, which has very strong fibers. Results also indicate that the mandibular structure among carnivores mainly reflects the differences in their dietary preferences and functional adaptation. Three groups were found referring to dispersal profiles expressed by the first two axes of PCA and DFA: (1) the two panda species - the herbivorous carnivores;(2) the black bear - the omnivorous carnivore;and (3) the tiger and leopard - the hypercarnivores. Nevertheless, a significant separation between the two panda species was also found with the profiles displayed by the first and third axes of DFA. In addition to no close evolutionary relationship and phylogenetic development, a noticeable separation between the two panda species found in DFA analysis may be associated with their variation in consuming different parts of the bamboo plant: the giant panda feeds on stems and the red panda feeds on leaves.
We developed a functional cell-based high-throughput screening (HTS) assay to identify modulators of the human neuromedin subtype 2 receptor. This assay utilized the signal transduction pathway of hNMU2R, which is pos...
详细信息
We developed a functional cell-based high-throughput screening (HTS) assay to identify modulators of the human neuromedin subtype 2 receptor. This assay utilized the signal transduction pathway of hNMU2R, which is positively coupled to adenylyl cyclase and downstream calcium signal pathways. We describe in detail a robust, sensitive, and functional assay for the hNMU2R G-protein-coupled receptor expressed in human embryonic kidney (HEK)-293 cells, whose activity was reflected by a luciferase reporter gene transcriptionally regulated by a 3-repeat serum response element (SRE)-3 repeat multiple response element (MRE)-3 repeat cyclic AMP (CAMP) response element (CRE)-VIP mini promoter. The HEK 293 clonal cell line, stably co-transfected with the 3 x SRE/3 x MRE/3 x CRE/VIP mini promoter-driven luciferase and pCDNA3.1-NMU2R plasmid, was selected by active geneticin sulfate and their ability to express luciferase with a forskolin challenge following hNMU plus forskolin, known to activate intracellular signal transduction. Then the cell density, incubation time, dimethyl sulfoxide (DMSO) concentration used to screen the hNMU receptor subtype 2 specific agonist were optimized, and whether intrinsic luminescent substance of extracts isolated from traditional Chinese herbs disturbs luminescence of luciferase expressed in HEK293 cells was considered. The optimal incubation time was found to be between 8 and 9 h, the cell density and DMSO concentrations were optimized from 3 x 104 to 6 x 104, and less than 2%, respectively. Our data show that hNMU2R luci-HEK293 cells and their assay exhibit a low background and ideal model for high-throughput screening. These results demonstrate that this reporter gene assay is useful for pharmacological analysis, and is amenable to HTS for human NMU2R agonists. (c) 2007 Elsevier B.V. All rights reserved.
The giant panda (Ailuropoda melanoleuca) is currently threatened by habitat loss, fragmentation, and human persecution. Its dietary specialization, habitat isolation, and reproductive constraints have led to a percept...
详细信息
The giant panda (Ailuropoda melanoleuca) is currently threatened by habitat loss, fragmentation, and human persecution. Its dietary specialization, habitat isolation, and reproductive constraints have led to a perception that this is a species at an "evolutionary dead end," destined for deterministic extinction in the modem world. Here we examine this perception by a comprehensive investigation of its genetic diversity, population structure, and demographic history across its geographic range. We present analysis of 655 base pairs of mitochondrial (mt) control region (CR) DNA and 10 microsatellite loci for samples from its 5 extant mountain populations (Qinling, Minshan, Qionglai, Liangshan, and Lesser Xiangling). Surprisingly, extant populations display average to high levels of CR and microsatellite diversity compared with other bear species. Genetic differentiation among populations was significant in most cases but was markedly higher between Qinling and the other mountain ranges, suggesting, minimally, that the Qinling population should comprise a separate management unit for conservation purposes. Recent demographic inference using in icrosate I lite markers demonstrated a clear genetic signature for population decline starting several thousands years ago or even futher back in the past, and being accelerated and enhanced by the expansion of human populations. Importantly, these data suggest that the panda is not a species at an evolutionary "dead end," but in common with other large carnivores, has suffered demographically at the hands of human pressure. Conservation strategies should therefore focus on the restoration arid protection of wild habitat and the maintenance of the currently substantial regional genetic diversity, through active management of disconnected populations.
We studied the denning ecology of giant pandas (Ailuropoda melanoleuca) in the Foping Nature Reserve, China. We identified 17 used and 21 unused cavities of appropriate size to accommodate denning and measured several...
详细信息
We studied the denning ecology of giant pandas (Ailuropoda melanoleuca) in the Foping Nature Reserve, China. We identified 17 used and 21 unused cavities of appropriate size to accommodate denning and measured several variables potentially affecting the suitability of these cavities for panda denning. Principal component analysis, combined with traditional univariate tests, indicated that maternal females preferred deeper cavities with a high interior-to-entrance ratio for height and width, suggesting a preference for narrow entrances and roomy chambers. Microhabitat features, including slope and distance to water, were also useful in predicting den use by maternal females. We believe that the availability of suitable dens may limit population size, especially in areas where tree dens have been eliminated by logging of old growth forests. Conservation managers in giant panda reserves can use our data to determine the number of suitable panda dens that are in an area, estimate whether there are enough for the adult female population to use as birthing dens, and-if needed-construct suitable artificial dens to increase the rate of reproduction.
It is significant to detect and analyze its mechanical property for the design of the artificial knee joint, especially for the design of an osseointegrated prosthetic limb. Since normal six-cornponent force sensors a...
详细信息
ISBN:
(纸本)9783540733188
It is significant to detect and analyze its mechanical property for the design of the artificial knee joint, especially for the design of an osseointegrated prosthetic limb. Since normal six-cornponent force sensors are unsuitable for detecting the mechanical property of the lower limb prosthesis, a novel sensor is presented in this paper. It can be easily fixed between the artificial knee joint and the stump of the patient to detect the load condition during walking. The mathematic model of the sensor is analyzed, and strength check, stiffness design and the linearity of the sensor were studied with FEA. Finally, the Transmission Matrix is calculated. This kind of sensor can help us to get academic foundations for the designment and the evaluation of the limb prosthesis and its performance.
An integrated electrooptical E-field sensor using a proton exchanged LiNbO3 Mach-Zehnder (M-Z) interferometer with a combined antenna and modulation electrode structure is designed and fabricated. The experimental res...
详细信息
暂无评论