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51.
1. Tadpoles of the bullfrog ( Rana catesbeiana ) collected in a coal ash deposition basin (contaminated with As, Cd, Cr, Cu, Se and other elements) and a downstream drainage swamp had a reduced number of labial teeth and deformations of labial papillae when compared with tadpoles from reference areas. Tadpoles from the coal ash-affected areas had 90% fewer teeth in anterior tooth row number 2 and 40% fewer teeth in posterior row number 1 than reference animals. In the deposition basins, drainage swamp and reference ponds, respectively, 96.2, 85.1 and 2.9% of tadpoles had oral deformities.
2. Tadpoles with deformities were less able to graze periphyton than were normal tadpoles, when tested in the laboratory. When presented with periphyton as a sole food source, tadpoles with deformed teeth had lower (negative) growth rates than those with normal teeth, which had slightly positive growth rates. When particulate food was also available, tadpoles grew well regardless of deformities.
3. It appears that the morphological deformities associated with this coal ash-polluted environment can have ecological ramifications for the affected organisms by limiting the type of food that can be consumed and the ability to grow when multiple food types are unavailable. 相似文献
2. Tadpoles with deformities were less able to graze periphyton than were normal tadpoles, when tested in the laboratory. When presented with periphyton as a sole food source, tadpoles with deformed teeth had lower (negative) growth rates than those with normal teeth, which had slightly positive growth rates. When particulate food was also available, tadpoles grew well regardless of deformities.
3. It appears that the morphological deformities associated with this coal ash-polluted environment can have ecological ramifications for the affected organisms by limiting the type of food that can be consumed and the ability to grow when multiple food types are unavailable. 相似文献
52.
The family Comasteridae is divided into four subfamilies on the basis of syzygy positions in the division series and proximal arm. Use of this character results in major differences in perceived relationships between genera compared with that obtained when traditional subfamilial characters are used. The primary character previously used to determine comasterid subfamilies, cirrus ornamentation, is rejected as unimportant in recognizing taxa any higher than species. Seventeen genera, including a new genus from the tropical western Atlantic, and 99 species are now recognized in the Comasteridae. Four of these genera and five species cannot be placed within the newly diagnosed subfamilies. Characters of generic importance are considered to be pinnule comb form, mouth position and, to a lesser extent, the characters traditionally used to distinguish genera. 相似文献
53.
Revision of some comasterid genera from Australia (Echinodermata: Crinoidea), with descriptions of two new genera and nine new species 总被引:2,自引:0,他引:2
F. W. E. ROWE A. K. HOGGETT R. A. BIRTLES† L. L. VAIL 《Zoological Journal of the Linnean Society》1986,86(3):197-277
Morphological characters used in comasterid taxonomy are reappraised. As a result, form and distribution of pinnule combs are newly promoted as primary characters of generic recognition. Form and arrangement of cirri and division series, as used by A. H. Clark (1931), are rejected as characters important in recognizing taxa higher than species. Five of 12 comasterid genera reported as occurring in Australian waters (H. L. Clark, 1946) are critically examined. Of these genera, Comantheria A. H. Clark, 1909b is referred to the synonymy of Comanthus A. H. Clark, 1908a, Comanlhoides A. H. Clark, 1931 is referred to the synonymy of Cenolia A. H. Clark, 1916b, and Comanthina A. H. Clark, 1909b is maintained. In addition, two new genera are described. These genera are related by the occurence of the first brachial syzygy at 3 + 4 on all arms. Twenty-six species within the five genera are now recognized in Australian waters. Nine new species are described, and the 17 existing species are rediagnosed and critically reappraised. The revision involves taxa distributed throughout the Indo-west Pacific region, as far west as S Africa. 相似文献
54.
The Iberian midwife toad Alytes cisternasii is an endemic species of the southwestern and central parts of the Iberian Peninsula. Allozyme analysis of Iberian midwife toads indicated no inter‐ or intrapopulation variation and a more sensitive method is required to quantify genetic differentiation and gene flow between populations of this species. We describe here the development of primers for the amplification by the polymerase chain reaction (PCR) of six polymorphic microsatellite loci in A. cisternasii. 相似文献
55.
JOHN HOWLAND ROWE 《American anthropologist》1972,74(1-2):154-156
56.
57.
One expected response to observed global warming is an upslope shift of species elevational ranges. Here, we document changes in the elevational distributions of the small mammals within the Ruby Mountains in northeastern Nevada over an 80‐year interval. We quantified range shifts by comparing distributional records from recent comprehensive field surveys (2006–2008) to earlier surveys (1927–1929) conducted at identical and nearby locations. Collector field notes from the historical surveys provided detailed trapping records and locality information, and museum specimens enabled confirmation of species' identifications. To ensure that observed shifts in range did not result from sampling bias, we employed a binomial likelihood model (introduced here) using likelihood ratios to calculate confidence intervals around observed range limits. Climate data indicate increases in both precipitation and summer maximum temperature between sampling periods. Increases in winter minimum temperatures were only evident at mid to high elevations. Consistent with predictions of change associated with climate warming, we document upslope range shifts for only two mesic‐adapted species. In contrast, no xeric‐adapted species expanded their ranges upslope. Rather, they showed either static distributions over time or downslope contraction or expansion. We attribute these unexpected findings to widespread land‐use driven habitat change at lower elevations. Failure to account for land‐use induced changes in both baseline assessments and in predicting shifts in species distributions may provide misleading objectives for conservation policies and management practices. 相似文献
58.
Elrasheid AH Kheirelseid Kah Hoong Chang John Newell Michael J Kerin Nicola Miller 《BMC molecular biology》2010,11(1):12
Background
Gene expression analysis has many applications in cancer diagnosis, prognosis and therapeutic care. Relative quantification is the most widely adopted approach whereby quantification of gene expression is normalised relative to an endogenously expressed control (EC) gene. Central to the reliable determination of gene expression is the choice of control gene. The purpose of this study was to evaluate a panel of candidate EC genes from which to identify the most stably expressed gene(s) to normalise RQ-PCR data derived from primary colorectal cancer tissue. 相似文献59.
Ashraf A Helmy Mostafa A Hamad Ahmed M Aly Tahra Sherif Mostafa Hashem Dalia AH El-Sers Mohammad Semieka 《Annals of surgical innovation and research》2011,5(1):1-9
Background
Biliary tract reconstruction continues to be a challenging surgical problem. Multiple experimental attempts have been reported to reconstruct biliary defects with different materials and variable outcome. Our aim was to evaluate a new method for biliary reconstruction using an isolated pedicled gastric tube in a live animal trial and also to present the first clinical case.Methods
Seven mongrel dogs underwent biliary reconstruction using gastric tube harvested, completely separated from the greater curvature, and based on a vascularized pedicle with the right gastroepiploic vessels. The tube was interposed between the common bile duct (CBD) and the duodenum. Postoperative mortality, morbidity, liver functions, gross and microscopic histological picture were assessed. The first clinical case was also presented where, in a patient with post-cholecystectomy biliary injury, an isolated pedicled gastric tube was interposed between the proximal and distal ends of the CBD.Results
One dog did not recover from anesthesia and another one died postoperatively from septic peritonitis. Five dogs survived the procedure and showed uneventful course and no cholestasis. The mean anastomotic circumference was 4.8 mm (range 4-6) for CBD anastomosis and 6.2 mm (range 5-7) for duodenal anastomosis. Histologically, anastomotic sites showed good evidence of healing. In the first clinical case, the patient showed clinical and biochemical improvement. Endoscopic retrograde cholangiography was feasible and assured patent biliary anastomoses.Conclusion
In mongrel dogs, biliary reconstruction using pedicled gastric tube interposition between CBD and duodenum is feasible with satisfactory clinical results, anastomotic circumference and histological evidence of healing. The technique is also feasible in human and seems to be promising. 相似文献60.
Jo Moore Stephen AC Hawkins Anthony R Austin Timm Konold Robert B Green Ian W Blamire Ian Dexter Michael J Stack Melanie J Chaplin Jan PM Langeveld Marion M Simmons Yvonne I Spencer Paul R Webb Michael Dawson Gerald AH Wells 《BMC research notes》2011,4(1):1-13