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1.
    
In September and October 2000, the remains of a number of apparently predated northern hairy-nosed wombats (Lasiorhinus krefftii) were discovered in Epping Forest National Park, the site of the only known population of this highly endangered species. Analysis of DNA recovered from six carcasses and a section of intestine found nearby was carried out using microsatellite and Y-specific primers. This identified seven individual wombats, the identity of three of which was inferred from a genotype database prepared from animals sampled during trapping programmes. Six victims were male and one female, suggesting that female-biased predation rates are unlikely to be the cause of the current male-biased population sex ratio. DNA isolated from four canid faeces found in the vicinity revealed three distinct canid microsatellite genotypes with very high probabilities of belonging to dingoes (Canis familiaris dingo). A wombat genotype matching that of one of the dead individuals was identified from scats of two of the dingoes. In addition, two macropod microsatellites were amplified from two dingo scats. These observations provided vital information regarding predation on northern hairy-nosed wombats, and prompted the permanent exclusion of dingoes from the park by the erection of a dingo-proof fence.  相似文献   

2.
    
On the basis of complete scanning through conformational space of dihedral angles, twelve structural genera were obtained. Subsequent energy minimization within these genera yielded a limited set of duplexes with stacking: right-handed B-form (Wilkins type), B2-form (Watson and Crick type) and left-handed Ll-form (Sasisekharan type) and the new L2-form. In the polymeric DNA only right-handed double-helices are possible, the left-handed helices are forbidden due to poor 1–5 interchain contacts. In contrast, for short fragments the left- and right-handed helicek have practically the same energies providing some physical ground for side-by-side form, which biologically is possible as recombination form and may be as replication form.  相似文献   

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Helicobacter pylori infection has been regarded as a major factor associated with the development of gastric diseases. The characterization of infected H. pylori in asymptomatic individuals is important for the prediction of the onset of such diseases. However, because of the difficulty in obtaining gastric biopsy samples, H. pylori in healthy subjects have not been studied sufficiently. Therefore, we tested a noninvasive method for the characterization of H. pylori using stool specimens. This method involved H. pylori antigen detection in stool specimens by immunochromatography; confirmation of H. pylori DNA by real-time PCR that involved the detection of its 16S rRNA gene in the DNA extracted from stool specimens; and nested PCR with genotype-specific primer pairs. A total of 80 samples obtained from asymptomatic subjects were assessed using this method. The results showed that the prevalence of H. pylori in asymptomatic Japanese individuals was 37.5%. The detection rate of the virulence factor gene cagA was 18.8%. Furthermore, all the detected cagA belonged to the highly virulent East-Asian type. These data suggest that the method used in this study is valuable for studying the molecular epidemiology of H. pylori infection in asymptomatic people.  相似文献   

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目的:研究正常人左、右侧的末梢神经传导特点及易损伤性,探讨生活习惯与末梢神经潜在性损伤的内在关联,提高电生理诊断准确率。方法:100名志愿者为对象,检测正中、尺、胫和腓神经的复合肌肉动作电位(CMAP)、F波,观察左、右侧的神经传导参数及左右差值与生活习惯之间的联系。结果:左侧尺、胫运动神经传导速度(MCV)慢于右侧(P值各为0.013、0.011)。MCV≤X-1S尺神经组的远端潜伏期(D Lat)、F波最短潜伏期(F-Lat)延长于MCV〉X-1S组(P值均为0.000)。MCV≤X-1S胫神经组的近端波幅(P Amp)低于MCV〉X-1S组(P=0.000)。右侧腓神经D Lat延长于左侧(P=0.007),D Lat≥X+1S腓神经组的MCV、F-Lat平均值慢或延长于D Lat〈X+1S组(P值各为0.041、0.000)。结论:左侧尺、胫神经MCV慢于右侧,右侧腓神经D Lat延长于左侧。推测神经传导左右差异是由日常生活中的频繁而反复的轻微外伤导致。  相似文献   

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8.
Embryonic morphogenesis occurs along three orthogonal axes. While the patterning of the anterior-posterior and dorsal-ventral axes has been increasingly well-characterized, the left-right (LR) axis has only relatively recently begun to be understood at the molecular level. The mechanisms that ensure invariant LR asymmetry of the heart, viscera, and brain involve fundamental aspects of cell biology, biophysics, and evolutionary biology, and are important not only for basic science but also for the biomedicine of a wide range of birth defects and human genetic syndromes. The LR axis links biomolecular chirality to embryonic development and ultimately to behavior and cognition, revealing feedback loops and conserved functional modules occurring as widely as plants and mammals. This review focuses on the unique and fascinating physiological aspects of LR patterning in a number of vertebrate and invertebrate species, discusses several profound mechanistic analogies between biological regulation in diverse systems (specifically proposing a nonciliary parallel between kidney cells and the LR axis based on subcellular regulation of ion transporter targeting), highlights the possible importance of early, highly-conserved intracellular events that are magnified to embryo-wide scales, and lays out the most important open questions about the function, evolutionary origin, and conservation of mechanisms underlying embryonic asymmetry.  相似文献   

9.
    
The matricellular protein osteopontin modulates cell–matrix interactions during tissue injury and healing. A complex multidomain structure of osteopontin enables it not only to bind diverse cell receptors but also to interact with various partners, including other extracellular matrix proteins, cytokines, and growth factors. Numerous studies have implicated osteopontin in the development and progression of myocardial remodeling in diverse cardiac diseases. Osteopontin influences myocardial remodeling by regulating extracellular matrix production, the activity of matrix metalloproteinases and various growth factors, inflammatory cell recruitment, myofibroblast differentiation, cardiomyocyte apoptosis, and myocardial vascularization. The exploitation of osteopontin loss- and gain-of-function approaches in rodent models provided an opportunity for assessment of the cell- and disease-specific contribution of osteopontin to myocardial remodeling. In this review, we summarize the recent knowledge on osteopontin regulation and its impact on various cardiac diseases, as well as delineate complex disease- and cell-specific roles of osteopontin in cardiac pathologies. We also discuss the current progress of therapeutics targeting osteopontin that may facilitate the development of a novel strategy for heart failure treatment.  相似文献   

10.
关于健康成人左右运动神经传导参数的比较   总被引:1,自引:0,他引:1  
目的:研究正常人左、右侧的末梢神经传导特点及易损伤性,探讨生活习惯与末梢神经潜在性损伤的内在关联,提高电生理诊断准确率。方法:100名志愿者为对象,检测正中、尺、胫和腓神经的复合肌肉动作电位(CMAP)、F波,观察左、右侧的神经传导参数及左右差值与生活习惯之间的联系。结果:左侧尺、胫运动神经传导速度(MCV)慢于右侧(P值各为0.013、0.011)。MCV≤X-1S尺神经组的远端潜伏期(D Lat)、F波最短潜伏期(F-Lat)延长于MCV>X-1S组(P值均为0.000)。MCV≤X-1S胫神经组的近端波幅(P Amp)低于MCV>X-1S组(P=0.000)。右侧腓神经D Lat延长于左侧(P=0.007),D Lat≥X+1S腓神经组的MCV、F-Lat平均值慢或延长于D Lat相似文献   

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  总被引:2,自引:0,他引:2  
The use of noninvasive genetic sampling (NGS) for surveying wild populations is increasing rapidly. Currently, only a limited number of studies have evaluated potential biases associated with NGS. This paper evaluates the potential errors associated with analysing mixed samples drawn from multiple animals. Most NGS studies assume that mixed samples will be identified and removed during the genotyping process. We evaluated this assumption by creating 128 mixed samples of extracted DNA from brown bear (Ursus arctos) hair samples. These mixed samples were genotyped and screened for errors at six microsatellite loci according to protocols consistent with those used in other NGS studies. Five mixed samples produced acceptable genotypes after the first screening. However, all mixed samples produced multiple alleles at one or more loci, amplified as only one of the source samples, or yielded inconsistent electropherograms by the final stage of the error-checking process. These processes could potentially reduce the number of individuals observed in NGS studies, but errors should be conservative within demographic estimates. Researchers should be aware of the potential for mixed samples and carefully design gel analysis criteria and error checking protocols to detect mixed samples.  相似文献   

13.
  总被引:2,自引:0,他引:2  
The present study examined the effects of exposure to Electromagnetic Radiation emitted by a standard GSM phone at 890 MHz on human cognitive functions. This study attempted to establish a connection between the exposure of a specific area of the brain and the cognitive functions associated with that area. A total of 36 healthy right-handed male subjects performed four distinct cognitive tasks: spatial item recognition, verbal item recognition, and two spatial compatibility tasks. Tasks were chosen according to the brain side they are assumed to activate. All subjects performed the tasks under three exposure conditions: right side, left side, and sham exposure. The phones were controlled by a base station simulator and operated at their full power. We have recorded the reaction times (RTs) and accuracy of the responses. The experiments consisted of two sections, of 1 h each, with a 5 min break in between. The tasks and the exposure regimes were counterbalanced. The results indicated that the exposure of the left side of the brain slows down the left-hand response time, in the second-later-part of the experiment. This effect was apparent in three of the four tasks, and was highly significant in only one of the tests. The exposure intensity and its duration exceeded the common exposure of cellular phone users.  相似文献   

14.
    
Pumas ( Puma concolor ) are an endangered species due to habitat loss and the ever-growing conflict with expanding human populations. We used genetic analysis of feces, a noninvasive study method, to determine the presence of pumas and their estimated minimum population in two protected areas in the northeast of São Paulo State, Brazil: Jataí Ecological Station and Vassununga State Park. We were able to identify the species that originally deposited the feces by means of amplification of a portion of the mitochondrial cytochrome b gene and comparison of this fragment with reference sequences from pumas and other carnivores present in the region. We used a panel containing four microsatellite loci to individualize each of the samples collected. Among the 20 fecal samples, we identified 10 as clearly belonging to pumas and two as belonging to ocelots ( Leopardus pardalis ), a species sympatric with P. concolor . By plotting the feces sampling points against a satellite image, we determined the presence of at least nine puma individuals in the region, three in the Jataí Ecological Station, four in the Vassununga State Park, and two in their surroundings. The identity probability was 0.0001 and the occurrence of allelic dropout was 10.6 percent. The presence of pumas, the estimate of their minimum population size, as well as their distribution, constitute an important tool for the implementation of management and conservation programs in the areas studied and their surroundings.  相似文献   

15.
Kelly Bulkeley 《Dreaming》2002,12(2):61-77
This pilot study focuses on the relationship of dream content and political ideology in a contemporary U.S. context. The study involved 56 people, 28 (14 male and 14 female) who identified themselves as members of the political right and 28 (14 male and 14 female) who identified themselves as members of the political left. Most recent dream reports from these subjects were analyzed using Hall and Van de Castle content analysis categories. Following that quantitative analysis, each dream was analyzed in terms of its narrative qualities (themes, images, emotional patterns, etc.). Although the small size of the study makes it impossible to offer definitive interpretations, the findings are suggestive: people on the political right had more nightmares, more dreams in which they lacked personal power, and a greater frequency of lifelike dreams; people on the political left had fewer nightmares, more dreams in which they had personal power, and a greater frequency of good fortunes and bizarre elements in their dreams. These findings have plausible correlations to certain features of the political ideologies of people on the left and the right, and merit future investigation in larger-scale studies.  相似文献   

16.
急性低氧下钙阻断剂对左,右心泵功能的影响   总被引:1,自引:0,他引:1  
周兆年  顾磊敏 《生理学报》1992,44(3):237-243
在20条麻醉开胸狗上,用RM-6000多道仪同步记录左心室内峰压(LVP)、左室压力变化率(L+dP/dt_(max))、右心室内峰压(RVP)、右室压力变化率(R±dp/dt_(max))、肺动脉压力(P_(Pa))、主动脉血流每搏峰值(Fa)、心率(HR)等各项生理指标,观察钙通道阻断剂Nife-dipine,Diltiazem和Verapamil对左、右心室功能影响。在钙通道阻断剂处理后,左室的LVP,L±dp/dt_(max)下降,而Fa增加;右室的RVF,R±dp/dt_(max)和P_(Pa)均有升高趋势,显示钙通道阻断剂对左、右心泵功能的影响不同。这可能提示左、右心室功能对钙离子的依赖程度不同。在急性低氧状态下,此三种钙阻断剂均使急性低氧引起LVP的增加反应消失,Fa增加明显,Verapamil和Diltiazem有减轻急性低氧引起的RVP和P_(Pa)的增压作用。从这些钙通道阻断剂对左右心泵功能影响的比较来看,Diltiazem比Verapamil和Nifedipine对急性低氧状态下的心泵功能有较好的作用。  相似文献   

17.
  总被引:6,自引:0,他引:6  
We used noninvasive methods to obtain genetic and demographic data on the wolf packs (Canis lupus), which are now recolonizing the Alps, a century after their eradication. DNA samples, extracted from presumed wolf scats collected in the western Italian Alps (Piemonte), were genotyped to determine species and sex by sequencing parts of the mitochondrial DNA (mtDNA) control-region and ZFX/ZFY genes. Individual genotypes were identified by multilocus microsatellite analyses using a multiple tubes polymerase chain reaction (PCR). The performance of the laboratory protocols was affected by the age of samples. The quality of excremental DNA extracts was higher in samples freshly collected on snow in winter than in samples that were older or collected during summer. Preliminary mtDNA screening of all samples allowed species identification and was a good predictor of further PCR performances. Wolf, and not prey, DNA targets were preferentially amplified. Allelic dropout occurred more frequently than false alleles, but the probability of false homozygote determinations was always < 0.001. A panel of six to nine microsatellites would allow identification of individual wolf genotypes, also whether related, with a probability of identity of < 0.015. Genealogical relationships among individuals could be determined reliably if the number of candidate parents was 6-8, and most of them had been sampled and correctly genotyped. Genetic data indicate that colonizing Alpine wolves originate exclusively from the Italian source population and retain a high proportion of its genetic diversity. Spatial and temporal locations of individual genotypes, and kinship analyses, suggest that two distinct packs of closely related wolves, plus some unrelated individuals, ranged in the study areas. This is in agreement with field observations.  相似文献   

18.
目的:考查左右视野中不同位置字母的辨别力。方法:采用探测刺激的方法对左右视野中字母位置的识别差异进行了研究。结果:通过SPSS15.0进行重复测量方差分析得出:①不同视野的错误率主效应显著(F=5.98,P<0.05);②探测位置的主效应非常显著(F=15.39,P<0.01);③不同视野与探测字母位置的交互作用非常显著(F=11.60,P<0.001)。结论:①位置错误多于字母错误,并且位置错误中所报告的字母更靠近中央凹。②左视野中的首字母有较差的辨别力,而右视野中的尾字母有较差的辨别力。③左视野中存在知觉系统的限制,而不是词汇识别策略中大脑左右半球的差异。④对词汇识别中大脑左半球平行加工、右半球系列加工的说法提出了质疑。  相似文献   

19.
The configurational behaviour of flexible helices of right handed B- and left handed Z-types have been analysed using statistical mechanical procedures. The configuration-dependent parameter, most importantly, the persistence length has been computed, using the heminucleotide scheme of treating polynucleotide chains under the approximation that perturbations in the backbone torsions produce sufficient flexibility in these helices. The values of persistence lengths obtained for Z-helices are very much higher than that of B-helices indicating that former is less flexible compared to the latter. These are in accordance with the results obtained recently on B- and Z-forms of poly(dG-dC). (dG-dC) using light scattering studies. Also the persistence lengths of BII-DNA helices characterised by a skew 3'-hemiucleotide (ε-270°), and also when they coexist with B-DNA have been computed and the values lie within the range of experimentally reported values on B-helices. It is argued that the decrease in the persistence length values of B-DNA at higher salt concentration is due to additional small fluctuations in sugar residue torsions induced due to neutralisation of electrostatic repulsions between adjacent phosphates of the nucleotide. Noteworthy is that these are correlated to winding angle variations and the consequent bending of the helix. Contribution No. 659.  相似文献   

20.
    
Abstract: Genetic profiling using fecal samples collected noninvasively in the wild can provide managers with an alternative to live-trapping. However, before embarking on a large-scale survey, feasibility of this methodology should be assessed for the focal species. Costs associated with fecal genotyping can be high because of the need for multiple amplifications to prevent and detect errors. Assessing the relative amount of target DNA before genotyping means samples can be eliminated where error rates will be high or amplification success will be low, thereby reducing costs. We collected fecal samples from an endangered population of swift fox (Vulpes velox) and employed target-DNA quantification and a screening protocol to assess sample quality before genetic profiling. Quantification was critical in identifying samples of low quality (68%, <0.2 ng/μL). Comparison of the amplification, from a subset of loci in 25 samples that did not meet the screening criteria, confirmed the effectiveness of this method. The protocol, however, used a considerable amount of DNA, and an assessment of the locus and sample variability allowed us to refine it for future population surveys. Although we did not use <50% of the samples we collected, the remaining samples provided 36 unique genotypes, which corresponded to approximately 70% of animals estimated to be present in the study area. Although obtaining fecal DNA from small carnivores is challenging, our protocol, including the quantification and qualification of DNA, the selection of markers, and the use of postgenotyping analyses, such as DROPOUT, CAPWIRE, and geographic information, provides a more cost-effective way to produce reliable results. The method we have developed is an informative approach that wildlife managers can use to conduct population surveys where the collection of feces is possible without the need for live-trapping.  相似文献   

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