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961.
Extreme environmental situations are useful tools for the investigation of the general processes of adaptation. Among such situations, high altitude of more than 3000 m produces a set of pathological disorders that includes both cerebral (cAS) and respiratory (RAS) altitude symptoms. High altitude exposure further induces anxiety responses and behavioural disturbances. The authors report an investigation on anxiety responses, personality traits, and altitude symptoms (AS) in climbers participating in a 31-day period of confinement and gradual decompression in a hypobaric chamber equivalent to a climb from sea-level to Mount Everest (8848 m altitude). Personality traits, state-trait anxiety, and AS were assessed, using the Cattell 16 Personality Factor questionnaire (16PF), the Spielberger's State-Trait Anxiety Inventory (STAI), and the Lake Louise concensus questionnaire. Results show significant group effect for state-anxiety and AS; state-anxiety and AS increased as altitude increased. They also show that state-type anxiety shows a similar time-course to cAS, but not RAS. Alternatively, our results demonstrate a significant negative correlation between Factor M of the 16PF questionnaire, which is a personality trait that ranges from praxernia to autia. In contrast, no significant correlation was found between personality traits and AS. This suggests that AS could not be predicted using personality traits and further support that personality traits, such as praxernia (happening sensitivity), could play a major role in the occurrence of state-type anxiety responses in extreme environments. In addition, the general processes of coping and adaptation in individuals participating in extreme environmental experiments are discussed.  相似文献   
962.
963.
Abstract: We studied local patterns of Brown-headed Cowbird ( Molothrus ater ) abundance, parasitism rates, and nest success of a common host, the Plumbeous Vireo ( Vireo plumbeus ), in relation to the distribution of livestock grazing in an undeveloped region of northeastern New Mexico, 1992–1997. We predicted that both cowbird abundance and parasitism rates of vireo nests would decrease with increasing distance from active livestock grazing, and that the nesting success of vireos would increase. We measured cowbird abundance and host density and located and monitored vireo nests in pinyon-juniper and mixed-conifer habitats that ranged from actively grazed to isolated from livestock grazing by up to 12 km. Cowbird abundance declined with distance from active livestock grazing and was not related to host density or habitat type. Brood parasitism levels of vireo nests ( n = 182) decreased from> 80% in actively grazed habitats to 33% in habitats that were 8–12 km from active grazing but did not vary by habitat type or distance to forest edge. Vireo nesting success was higher in mixed-conifer habitat than in pinyon-juniper but was unrelated to distance from active livestock grazing. Nest losses due to parasitism declined with distance from active livestock grazing. Our results suggest that cowbird abundance and parasitism rates of hosts may be distributed as a declining gradient based on distance from cowbird feeding sites and that isolation from feeding sites can reduce the effects of parasitism on host populations. These findings provide support for management techniques that propose to reduce local cowbird numbers and parasitism levels by manipulating the distribution of cowbird feeding sites. The presence of parasitized nests> 8 km from active livestock grazing suggests that, in some regions, management efforts may need to occur at larger scales than previously realized.  相似文献   
964.
Clinical diagnostic laboratories are producing next-generation sequencing-based test results that are becoming increasingly incorporated into patient care. Whole genome and exome sequencing on fetal material derived from amniocytes, chorionic villi, or products of conception is starting to be offered clinically in specialized centers, but it has not yet become routine practice. The technical, interpretation, and ethical challenges are greatest in the area of prenatal medicine because the fetus has a limited health history, and the physical examination is only indirectly available via prenatal sonography. Here, we provide an overview of these challenges and highlight the clinical utility, reporting, and counseling issues associated with prenatal DNA sequencing. Future considerations are also discussed. © 2017 John Wiley & Sons, Ltd.  相似文献   
965.
In response to the Fukushima nuclear reactor accident, on March 20th, 2011, Natural Resources Canada conducted aerial radiation surveys over water just off the west coast of Vancouver Island. Dose-rate levels were found to be consistent with background radiation, however a clear signal due to 133Xe was observed. Methods to extract 133Xe count rates from the measured spectra, and to determine the corresponding 133Xe activity concentration, were developed. The measurements indicate that 133Xe concentrations on average lie in the range of 30-70 Bq/m3.  相似文献   
966.
L. B. Connell 《Marine Biology》2000,136(6):953-960
The internal transcribed spacer (ITS) region from 19 isolates of the algal genus Heterosigma (Chromophyta: Raphidophyceae) was amplified by polymerase chain-reaction (PCR) and sequenced. Isolates were obtained from both the Atlantic and Pacific basins, including Europe, eastern North America, western North America, Japan and New Zealand. This study presents evidence that all Heterosigma isolates in this study are representatives of one species (H. akashiwo). All 19 isolates, except one (LB 2005) had identical ITS sequence (98.31% similar by pairwise comparison); Isolate LB 2005 may represent a separate subspecies. Such high degree of ITS sequence identity implies that the organism has spread between oceanic regions in geologically recent times, possibly by human means. In addition to those from Heterosigma spp., the ITS regions from other marine Raphidophyceae (Chattonella antiqua, C. marina, C. subsalsa, Fibrocapsa japonica, and Olisthodiscus luteus) were amplified and sequenced using PCR. Total ITS lengths differed among the Raphidophyceae (C. antiqua, 577 base pairs (bp); C. marina, 577 bp;. C. subsalsa, 579 bp; F. japonica, 830 bp; H. akashiwo, 561 and 563 bp; O. luteus, 829 bp), but 5.8S rDNA sequences were similar in size (13 to 142 bp). The high ITS sequence identity between C. antiqua and C. marina (>99.9% by pairwise comparison) suggests the need for a taxonomic review of these species encompassing all morphological, genetic, physiological and biochemical information. Additionally, a number of cultures of Raphidophyceae were positively identified. In general, ITS comparisons among the Raphidophyceae may be most useful at the level of species determination rather than at the population level. Received: 12 July 1999 / Accepted: 16 March 2000  相似文献   
967.
 The variability of magnesium, strontium and calcium concentrations in the two skeleton types (sclerites and axis) of the red coral (Corallium rubrum) was assessed by using X-ray fluorescence spectroscopy and microprobe analysis as a prerequisite for their use as ecological indicators. Axis cross sections showed light and dark circular growth bands corresponding to fast and slow growth, respectively. Using microprobe analyses the Mg and Sr concentrations ranged from 2.8 to 3.0% and from 0.21 to 0.29%, respectively, in the sclerites and from 2.4 to 3.0% and from 0.1 to 0.28%, respectively, in the axis. Mg/Ca and Sr/Ca ratios varied within sclerites (average, 12% for both ratios) and within the axis of single colonies (average, 20% for Mg/Ca and 48% for Sr/Ca). Sr/Ca ratios in the axis were lower in fast-growing branch tips than in older, more basal parts of the colonies, whereas the Mg/Ca ratio did not differ significantly between colony regions. Mg/Ca and Sr/Ca ratios in the axis decreased significantly with depth, and we estimated an increase of the Mg/Ca ratio of 0.004–0.006 per degree Celsius. In all depth layers, Sr/Ca ratios showed a significant direct relationship with skeleton density in axis cross sections, whereas there was no significant relationship for Mg/Ca. Overall, our data indicate that temperature promotes the incorporation of Mg in C. rubrum as in other calcite skeletons, whereas Sr concentrations are inversely related to growth rate. This preliminary study suggests that Mg and Sr concentrations in the axis of the red coral have a strong potential as ecological indicator for temperature and growth rate. Received: 3 March 2000 / Accepted: 30 August 2000  相似文献   
968.
969.
Role of Genetic Background in the Success of Reintroduced Peregrine Falcons   总被引:2,自引:0,他引:2  
Abstract: Peregrine Falcons (    Falco peregrinus ) of seven subspecies from four continents were bred in captivity, and approximately 1173 of their progeny were released in the midwestern United States and adjacent regions of Ontario and Manitoba in an attempt to replace the original population that was extirpated by chlorinated hydrocarbon poisoning in the 1950s. We analyzed the success of individuals of the different subspecies introduced to the Midwest. Five of the seven subspecies released have contributed to the current breeding population. Subspecies of breeding Peregrine Falcons were equally represented when breeding birds of high productivity were compared with less prolific breeders. The subspecific makeup of the breeding population did not differ significantly from that of the released population, suggesting that adaptability in this species was sufficient to override genetic differences between subspecies. Peregrines of widely different genetic stocks have thrived after release, making substantial genetic contributions to the new population.  相似文献   
970.
Abstract: The endangered Hawaiian monk seal breeds at six locations in the northwestern Hawaiian Islands. To determine whether significant genetic differentiation exists among these sites, we used microsatellite loci to examine the monk seal population structure at the five largest breeding colonies. Of 27 loci isolated from other seal species, only 3 were polymorphic in an initial screening of one individual from each breeding site. Only two alleles were found at each of these 3 loci in samples of 46–108 individuals. This extremely low variation is consistent with other measures of genetic variability in this species and is probably the result of a recent severe population bottleneck, combined with a long-term history of small population sizes. Although the smallest monk seal subpopulation in this study ( Kure Atoll) showed some evidence of heterozygote deficit, possibly indicative of inbreeding, the next smallest ( Pearl and Hermes Reef) had an apparent excess of heterozygous individuals. Genetic differentiation was detected between the two subpopulations at extreme ends of the range ( Kure and French Frigate Shoals). This trend was significant only at the microsatellite locus for which we had the largest sample size ( Hg6.3: R ST = 0.206, p = 0.002; allelic goodness of fit G h = 15.412, p < 0.005). French Frigate Shoals is the source population for translocated animals that have been released primarily at Kure Atoll. Differentiation between these sites consisted of allele frequency differences (with the same allele predominant in each location at all three loci), rather than the preservation of alternative alleles. Although the translocations have had positive demographic effects, we recommend continued genetic monitoring of both the source and recipient populations because translocated individuals are now entering the breeding population.  相似文献   
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