Home About us Contact
|
Home About us Contact | ||
|
|
||
Model Group (model + group)
Selected AbstractsChanges of traditional agrarian landscapes and their conservation implications: a case study of butterflies in RomaniaDIVERSITY AND DISTRIBUTIONS, Issue 6 2007Thomas Schmitt ABSTRACT Global biodiversity is decreasing as a result of human activities. In many parts of the world, this decrease is due to the destruction of natural habitats. The European perspective is different. Here, traditional agricultural landscapes developed into species-rich habitats. However, the European biodiversity heritage is strongly endangered. One of the countries where this biodiversity is best preserved is Romania. We analyse the possible changes in Romania's land-use patterns and their possible benefits and hazards with respect to biodiversity. As model group, we used butterflies, whose habitat requirements are well understood. We determined the ecological importance of different land-use types for the conservation of butterflies, underlining the special importance of Romania's semi-natural grasslands for nature conservation. We found that increasing modern agriculture and abandonment of less productive sites both affect biodiversity negatively , the former immediately and the latter after a lag phase of several years. These perspectives are discussed in the light of the integration of Romania into the European Union. [source] ORIGINAL ARTICLE: Freshwater paths across the ocean: molecular phylogeny of the frog Ptychadena newtoni gives insights into amphibian colonization of oceanic islandsJOURNAL OF BIOGEOGRAPHY, Issue 1 2007G. John Measey Abstract Aim, Amphibians are a model group for studies of the biogeographical origins of salt-intolerant taxa on oceanic islands. We used the Gulf of Guinea islands to explore the biogeographical origins of island endemism of one species of frog, and used this to gain insights into potential colonization mechanisms. Location, São Tomé and Príncipe, two of the four major islands in the Gulf of Guinea, West Africa, are truly oceanic and have an exceptionally high biodiversity. Methods, Mitochondrial DNA is used to test the endemic status of a frog from São Tomé and compare it with congeneric taxa from tropical Africa. Existing data on surface currents, surface salinity, atmospheric circulation and bird migration in the Gulf of Guinea are summarized to address hypotheses concerning colonization mechanisms. Results, The endemic status of Ptychadena newtoni (Bocage) is supported here by mitochondrial DNA sequences, and analysis of this and other molecular data indicates that an East African species close to Ptychadena mascareniensis (Duméril and Bibron) is its nearest relative. We refute the possibility that this population was anthropogenically introduced, in favour of a natural dispersal mechanism. Main conclusions, With six endemic frogs and one caecilian, the Gulf of Guinea islands harbour a diverse amphibian fauna. Five of these species appear to have their closest relatives in East Africa. Insufficient evidence exists for transportation by storms, birds or rafts alone. However, we propose a synergy of rafting, favourable surface currents and a reduction in salinity of surface waters. Catastrophic events, or wet periods in climatic history, could allow freshwater paths to open far enough to enable continental flora and fauna to reach these and other isolated oceanic islands. [source] Abnormal expression of Smurf2 during the process of rat liver fibrosisJOURNAL OF DIGESTIVE DISEASES, Issue 4 2006Yu CAI OBJECTIVE: Liver fibrosis is a prelude of liver cirrhosis. Currently the molecular mechanism of liver fibrosis is not clear. The purpose of this study is to screen the abnormally expressed genes of liver fibrosis and to illustrate the changes of Smurf2 expression in the process of liver fibrosis. METHODS: A liver fibrosis model was established in rats by injection of tetrachlormethane (CCl4). A cDNA microarray analysis was performed on the liver at mid-stage of fibrosis. Thereafter, a semi-quantitative RT-PCR, Western blot analysis and immunohistochemistry test were performed for determining Smurf2, Smad2 and SnoN at week 1, 2, 4 and 8 of establishing the liver fibrosis model. RESULTS: Smurf2, FGG, PTAFR, CYP2D6, among others, increased in the fibrosis liver and a semi-quantitative RT-PCR confirmed the reliability of the cDNA microarray analysis. Smurf2 in the liver fibrosis model group was at the same level as that of control group at week 1, but decreased at week 2 and 8 and increased at the week 4. Smad2 increased at week 2 and 8 but increased at week 4. However, Smad2 mRNA increased to the same level at week 4 as that at week 2 and 8. The decrease of Smad2 at week 4 may be due to the enhancement of ubiquitination and proteolytic degradation of Smad2 by the increase of Smurf2. SnoN decreased at week 4 and 8 because of the ubiquitination and degradation caused by Smurf2. The decrease of SnoN may explain the progress of liver fibrosis in spite of the decrease of Smad2 at week 4. CONCLUSION: This study screened the abnormally expressed genes of liver fibrosis and illustrated the changes of Smurf2, Smad2 and SnoN during the process of liver fibrosis. [source] Changes in perceived effect of practice guidelines among primary care doctorsJOURNAL OF EVALUATION IN CLINICAL PRACTICE, Issue 4 2007Lee Cheng MD MSc Abstract Rationale, aims and objectives, Evidence suggests that when doctors use systematically developed clinical practice guidelines they have the potential to improve the safety, quality and value of health care. The purpose of this study was to evaluate recent changes in the perceptions of practice guidelines among US primary care doctors. Methods, Data were collected from the Community Tracking Survey 1996,97 and 2000,01. All results were weighted and adjusted to reflect the complex survey design. Results, Over the 5 years, the proportion of primary care doctors who said that practice guidelines had at least a moderate effect on their practice of medicine increased from 45.8% to 60.7%. This increase was nearly equal among primary care doctors of family medicine, internal medicine and paediatrics. In the 2001 survey, a higher perceived effect of practice guidelines was described by female doctors (OR = 1.39, 95% CI 1.19,1.63) and doctors who were practising in a large model group (OR = 1.73; 95% CI 1.04,2.89). Doctors who graduated from medical school within 10 years of the survey were more likely to report that practice guidelines had a positive effect on their practice of medicine than doctors who graduated 10 or more years before the survey. Conclusion, The perceived effect of practice guidelines on primary care doctors increased over time. Improved dissemination of guidelines and curriculum changes may have led recent primary care graduates to view practice guidelines as more important. [source] A test of Rensch's rule in varanid lizardsBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2010PETRA FRÝDLOVÁ In a model group of giant reptiles, we explored the allometric relationships between male and female body size and compared the effects of sexual and fecundity selection, as well as some proximate causes, on macroevolutionary patterns of sexual size dimorphism (SSD). Monitor lizards are a morphologically homogeneous group that has been affected by extreme changes in body size during their evolutionary history, resulting in 14-fold differences among the body sizes of recent species. Here, we analysed data concerning the maximum and/or mean male and female snout,vent lengths in 42 species of monitor lizard from literary sources and supplemented these data with measurements made in zoos. There was a wide scale of SSD from nearly monomorphic species belonging mostly to the subgenus Odatria and Prasinus group of the Euprepriosaurus to apparently male-larger taxa. The variable best explaining SSD was the body size itself; the larger the species, the higher the SSD. This pattern agrees with the currently discussed Rensch's rule, claiming that the relationship between male and female body size is hyperallometric, i.e. the allometric exponent of this relationship exceeds unity and thus SSD increases with body size in the case of male-larger taxa. All our estimates of the reduced major axis regression slopes of this relationship ranged from 1.132 to 1.155. These estimates are significantly higher than unity, and thus unequivocally corroborate the validity of Rensch's rule in this reptilian group. In spite of our expectation that the variation in SSD can be alternatively explained by variables reflecting the strength of sexual selection (presence of male combat), fecundity selection (e.g. clutch size and mass) and/or proximate ecological factors (habitat type), none of these variables had consistent effects on SSD, especially when the data were adjusted to phylogenetic dependence and/or body size. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 293,306. [source] | |||||||||||||