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The slow rate of mtDNA evolution in turtles poses a limitation on the levels of intraspecific variation detectable by conventional restriction fragment surveys. We examined mtDNA variation in the gopher tortoise (Gopherus polyphemus) using an alternative restriction assay, one in which PCR-amplified segments of the mitochondrial genome were digested with tetranucleotide-site endonucleases. Restriction fragment polymorphisms representing four amplified regions were analysed to evaluate population genetic structure among 112 tortoises throughout the species' range. Thirty-six haplotypes were identified, and three major geographical assemblages (Eastern, Western, and Mid-Florida) were resolved by UPGMA and parsimony analyses. Eastern and Western assemblages abut near the Apalachicola drainage, whereas the Mid-Florida assemblage appears restricted to the Brooksville Ridge. The Eastern/Western assemblage boundary is remarkably congruent with phylogeographic profiles for eight additional species from the southeastern U.S., representing both freshwater and terrestrial realms.  相似文献   
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The newly described molossid bat, Chaerephon atsinanana Goodman et al., 2010, endemic to eastern Madagascar, shows notably high levels of phylogeographic and genetic structure compared with allopatric Chaerephon leucogaster Grandidier, 1869 from western Madagascar. Such highly significant structuring of haplotypes among altitudinally and latitudinally stratified population groups is contrary to the expected panmixia in strong flying bats. The null model of concordance in historical demographic patterns across these two Chaerephon species was not supported. Mismatch and Bayesian skyline analyses indicated ancient stable C. atsinanana populations of constant size during the last two major Pleistocene glacial periods, making retreat into and expansion from glacial refugia an unlikely explanation for such high levels of structure, in accordance with expectations for tropical bats. Analyses were consistent with post‐refugial population expansion in the less diverse and structured C. leucogaster during the end of the last Pleistocene glacial period. We hypothesise that the pronounced genetic structuring in C. atsinanana may result from female philopatry. Furthermore, differing demographic histories of the two species may have been shaped by differing climate or habitat preferences, consistent with evidence from MaxEnt ecological niche modelling, which shows differences in variables influencing the current predicted distributions. Fossil Quaternary pollen deposits further indicate greater stability in past climatic patterns in eastern versus western Madagascar. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 18–40.  相似文献   
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Trace elements in the Upper Fly River, Papua New Guinea   总被引:1,自引:0,他引:1  
SUMMARY. Measurements were made of calcium, magnesium and eight trace elements (Cu, Zn, Fe, Mn, Ni, Pb, Cd, Co) in waters, sediment and biota at eight sites in the Upper Fly River, Papua New Guinea. Determinations from streams draining an area rich in copper ore showed relatively low values for soluble copper and this was attributed to the small amount of ore exposed to weathering, heavy rainfall and high pH of water associated with the limestone bedrock. More iron was transported in a soluble form down a headwater tributary (Alice River) than in the Fly River but higher iron concentrations were associated with particulate matter in the Fly than in the Alice. The geochemistry of the catchment and the distance from the headwaters were important influences on the amount of particulate iron and its distribution between soluble and particulate forms.
Levels of metals in the biota generally reflected the background concentrations of metals encountered at each site. Concentrations of Cu, Cd, and Zn were lower in starved invertebrates compared with unstarved individuals but no consistent changes were observed in Fe or Mn content.  相似文献   
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Fine needle aspirates (FNA) from 31 invasive carcinomas of tubular type and 22 radial scar/complex sclerosing lesions (RS/CSL), diagnosed in Edinburgh between 1986 and 1991, were reviewed. the lesions in this study varied in size and palpability at presentation, but are of increasing interest in the differential diagnosis of non-palpable areas of increased mammographic density. In agreement with previously published information1'5'8, it was found that the tubular cancers were usually selected for biopsy following aspiration, but less often definitively diagnosed as malignant. Nearly 50% of the RS/CSL group were correctly reported benign on cytology, but in 40%, biopsy was recommended to exclude malignancy. In addition, cytological features helpful in suggesting malignancy in aspirates from tubular cancers, also raised suspicion in aspirates from the RS/CSL group, with a risk of overdiagnosis of cancer.  相似文献   
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In the light of improved means of combating infection, better and safer anesthesia, the ready availability of blood transfusion, and less traumatic delivery, reasons formerly advanced in opposition to operations at the time of parturition for repair of preexisting lesions of the pelvic floor are now less formidable than they were in the past. Such operations now can be carried out quickly and safely with considerable benefit in terms of immediate comfort and well-being of the patient, prevention of later development of more serious lesions, and savings in cost of hospitalization. In a series of more than 300 patients so operated upon-the technique used is described herein-none died, and in a review of the records many advantages of operation immediately after delivery, as compared with long delay of needed repair, were noted.  相似文献   
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Elicitors and defence gene activation   总被引:3,自引:1,他引:2  
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Endometriosis     
The cause of endometriosis is not known. The incidence of the disease is greater than was previously suspected and it probably is increasing. Nulliparous women are more likely to have endometriosis than are women who have had children. The commonest symptoms are lower abdominal pain, disturbance of menstruation, and dysmenorrhea, most often of the increasing or acquired type. Relative and absolute sterility are common partners of endometriosis.A better percentage of correct preoperative diagnoses should be obtained in view of present knowledge.Radical operation on women in the premenopausal age groups with endometriosis is resorted to in far too high a percentage of cases. The good results which can be attained with conservative therapy, including surgical and hormone therapy, should be stressed. There is some evidence that endocrine therapy may control endometriosis. The dangers attending these methods have not as yet been determined.  相似文献   
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