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21.
The influence of landscape characteristics and home-range size on the quantification of landscape-genetics relationships 总被引:1,自引:1,他引:0
Tabitha A. Graves Tzeidle N. Wasserman Milton Cezar Ribeiro Erin L. Landguth Stephen F. Spear Niko Balkenhol Colleen B. Higgins Marie-Josée Fortin Samuel A. Cushman Lisette P. Waits 《Landscape Ecology》2012,27(2):253-266
A common approach used to estimate landscape resistance involves comparing correlations of ecological and genetic distances
calculated among individuals of a species. However, the location of sampled individuals may contain some degree of spatial
uncertainty due to the natural variation of animals moving through their home range or measurement error in plant or animal
locations. In this study, we evaluate the ways that spatial uncertainty, landscape characteristics, and genetic stochasticity
interact to influence the strength and variability of conclusions about landscape-genetics relationships. We used a neutral
landscape model to generate 45 landscapes composed of habitat and non-habitat, varying in percent habitat, aggregation, and
structural connectivity (patch cohesion). We created true and alternate locations for 500 individuals, calculated ecological
distances (least-cost paths), and simulated genetic distances among individuals. We compared correlations between ecological
distances for true and alternate locations. We then simulated genotypes at 15 neutral loci and investigated whether the same
influences could be detected in simple Mantel tests and while controlling for the effects of isolation-by-distance using the
partial Mantel test. Spatial uncertainty interacted with the percentage of habitat in the landscape, but led to only small
reductions in correlations. Furthermore, the strongest correlations occurred with low percent habitat, high aggregation, and
low to intermediate levels of cohesion. Overall genetic stochasticity was relatively low and was influenced by landscape characteristics. 相似文献
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23.
Effect of temperature on the ability of Gremmeniella abietina to survive and to colonize host tissue
Gremmeniella abietina was able to survive in vitro for four weeks at average temperatures less than 30° C. At higher temperatures, survival time was inversely proportional to temperature. The fungus survived for 23–28 months inside asymptomatic trees. Freezing, or freezing and thawing, of inoculated trees, may have promoted symptom development. 相似文献
24.
Linear arrays in lead isotope space for mid-ocean ridge basalts (MORBs) converge on a single end-member component that has intermediate lead, strontium, and neodymium isotope ratios compared with the total database for oceanic island basalts (OIBs) and MORBs. The MORB data are consistent with the presence of a common mantle source region for OIBs that is sampled by mantle plumes. 3He/4He ratios for MORBs show both positive and negative correlation with the 206Pb/204Pb ratios, depending on the MORB suite. These data suggest that the common mantle source is located in the transition zone region. This region contains recycled, oceanic crustal protoliths that incorporated some continental lead before their subduction during the past 300 to 2000 million years. 相似文献
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JMS Santos VG Menezes RS Barberino TJS Macedo TLB Lins BB Gouveia VRP Barros LP Santos RJS Gonçalves MHT Matos 《Reproduction in domestic animals》2014,49(3):522-528
Studies with sheep are important to improve our knowledge about the factors that control folliculogenesis in mammals and to explore possible physiological differences among species. The aims of this study were to characterize FGF‐2 protein expression in ovine ovaries and to verify the effect of FGF‐2 on the morphology, apoptosis and growth of ovine pre‐antral follicles cultured in vitro. After collection, one fragment of ovarian tissue was fixed for histological analysis and TUNEL analysis (fresh control). The remaining fragments were cultured for 7 days in control medium (α‐MEM+) alone or supplemented with FGF‐2 at different concentrations (1, 10, 50, 100 or 200 ng/ml). After culturing, ovarian tissue was destined to histology and TUNEL analysis, and oocyte and follicle diameters were measured. The immunostaining for FGF‐2 was observed in oocytes from primordial, primary and secondary follicles, as well as in granulosa cells of secondary and antral follicles. The percentage of normal follicles was similar among control medium, 1 and 10 ng/ml FGF‐2, and significantly higher than those observed in 50, 100 or 200 ng/ml FGF‐2. A significant increase in follicle diameter was observed when tissues were cultured in 10, 50, 100 or 200 ng/ml FGF‐2 compared with the fresh control and the other treatments. Similar results were observed for oocyte diameter in tissues cultured with 50, 100 or 200 ng/ml FGF‐2 (p < 0.05). However, the percentage of apoptotic cells only decreased (p < 0.05) in ovarian tissues cultured in 1 or 10 ng/ml FGF‐2 compared with the control medium and other FGF‐2 treatments. In conclusion, this study demonstrated the presence of FGF‐2 in ovine ovaries. Furthermore, 10 ng/ml FGF‐2 inhibits apoptosis and promotes ovine follicle growth. As the sheep ovary is more similar to that of humans, the culture system demonstrated in this work seems to be an appropriate tool for studies towards human folliculogenesis. 相似文献
27.
Prevalence of low automated platelet counts in cats: comparison with prevalence of thrombocytopenia based on blood smear estimation 总被引:2,自引:0,他引:2
Norman EJ Barron RC Nash AS Clampitt RB 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2001,30(3):137-140
Abstract: True thrombocytopenia is uncommon in cats; however, low platelet counts frequently are found using automated cell counters. Although this discrepancy is a well known problem, the prevalence of low automated platelet counts in feline blood samples has not been documented. We retrospectively compared the prevalence of low automated platelet counts with low blood smear-estimated platelet counts in feline blood samples. Results of blood sample analysis from 359 cats during a 1-year period at the University of Glasgow Veterinary Haematology Laboratory were examined. Smear estimates of platelet number were done in those cases in which records did not indicate adequate platelet numbers. Platelet counts obtained with an impedance counter (Minos Vet, Abx Hematologie) were <200×109 cells/L in 256 samples (71%) and <50×109 cells/L in 43 samples (12%). However, based on estimation of platelet numbers from blood smears, only 11 samples (3.1%) had platelet counts of <200×109 cells/L and 9 samples (2.5%) had counts of <50×109 cells/L. Four cats with thrombocytopenia estimated by blood smear evaluation had clinical signs of a bleeding disorder. Disorders associated with thrombocytopenia included neoplasia, cytotoxic chemotherapy, and infectious diseases. There was no evidence that delay due to mailing of samples was associated with lower automated platelet counts than would have been obtained on the day of sampling. The high prevalence of apparent thrombocytopenia in automated platelet counts was attributed to a combination of platelet aggregation and the impedance method of cell differentiation by size. Vigilance and careful examination of blood smears is required to identify the few cats with true thrombocytopenia. 相似文献
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29.
Use of protocatechuic acid as the sole antioxidant in the base medium for in vitro culture of ovine isolated secondary follicles
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VG Menezes JMS Santos TJS Macedo TLBG Lins RS Barberino BB Gouveia MÉS Bezerra AYP Cavalcante MAA Queiroz RC Palheta Jr MHT Matos 《Reproduction in domestic animals》2017,52(5):890-898
This study evaluated the effect of the protocatechuic acid (PCA) as the sole antioxidant in the base medium for in vitro culture of ovine secondary follicles. Secondary follicles (200‐230 μm) were isolated and cultured in α‐minimal essential medium supplemented with BSA, insulin, glutamine and hypoxanthine (α‐MEM: antioxidant‐free medium) or α‐MEM also added by transferrin, selenium and ascorbic acid (α‐MEM+: with antioxidant) or α‐MEM added by PCA (56.25; 112.5; 225; 450; or 900 μg/ml). Moreover, after culture, oocytes were matured and the chromatin configuration and DNA fragmentation were evaluated. After 12 days, the treatment containing 56.25 μg/ml PCA showed higher percentage of normal follicles than control medium or the other treatments (p < .05), except for 900 μg/ml PCA (p > .05). The antrum formation was significantly higher in treatments containing 56.25, 112.5 or 900 μg/ml PCA, compared to the α‐MEM and similar (p > .05) to the other treatments. The rates of fully grown oocytes (≥110 μm) were similar (p > .05) among all treatments containing PCA and α‐MEM+, and those were superior (p < .05) than α‐MEM, except for 450 μg/ml PCA (p > .05). GSH levels and mitochondrial activity were higher (p < .05) in α‐MEM+ than in α‐MEM and similar (p > .05) to all PCA treatments. The rates of meiotic resumption and DNA fragmentation were similar (p > .05) among α‐MEM+ and 56.25 μg/ml PCA. In conclusion, PCA at 56.25 μg/ml as the sole antioxidant added to the medium for ovine isolated secondary follicle culture maintains follicular survival, GSH and active mitochondria levels, meiotic developmental competence and DNA integrity of cultured oocytes. 相似文献
30.
In 2016, Russet Norkotah was the second most widely grown potato variety in the US; however, recent research has identified alternatives with excellent production economics. During 2011–2013, fresh market variety research was conducted in the Columbia Basin of central Washington, a long-season production region. Russet Norkotah was compared to five varieties–Classic Russet, Mountain Gem Russet, Russet Burbank, Targhee Russet, and Teton Russet–and four sub-clonal strains–CO-3, CO-8, TX-278, and TX-296–derived from Russet Norkotah. Each variety was evaluated for early- (104 days between planting and vine kill) and late- (150 days between planting and vine kill) harvest tuber size profile, grade, and yield, grower economic value, susceptibility to blackspot bruise and shatter bruise, emergence, stem and at-harvest tuber numbers, tuber length-to-width ratios, and quality. When harvested early, Classic Russet and Mountain Gem Russet produced 30% and 15% more gross revenue than Russet Norkotah, respectively. All other varieties and Russet Norkotah strains except CO-3 produced as much early-harvest gross revenue as Russet Norkotah. CO-3 early-harvest revenue was close to 50% lower than that of Russet Norkotah. All varieties and Russet Norkotah strains produced significantly greater late-harvest yields and gross returns than Russet Norkotah. Late-harvest gross revenue for Targhee Russet and Mountain Gem Russet was 38% and 34% higher than Russet Norkotah, respectively. Classic Russet, Mountain Gem Russet, Targhee Russet, and Teton Russet had significantly more shatter bruise following the late harvest than Russet Norkotah and all Russet Norkotah strains. Russet Burbank was among the most susceptible to blackspot and Targhee Russet the least, with 32% and 2.1%, respectively. If bruising is mitigated, Mountain Gem Russet, Classic Russet, and Teton Russet may be suitable alternatives to Russet Norkotah and Russet Norkotah strains for both early and late harvests. 相似文献