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51.
Hepatitis E virus (HEV) is a single-strand positive-sense RNA virus in the family Hepeviridae. The disease caused by HEV, hepatitis E, is an important public health problem in developing countries of Asia and Africa and is also endemic in many industrialized countries, including the United States. HEV has been identified from several other animal species in addition to humans, including the pig, chicken, mongoose, deer, rabbit, ferret, bat, and fish. Here we report the complete genome sequence of the first strain of HEV from rabbits in the United States. Sequence and phylogenetic analyses revealed that the U.S. rabbit HEV is a distant member of the zoonotic genotype 3 HEV, thus raising a concern for potential zoonotic human infection. A unique 90-nucleotide insertion within the X domain of the ORF1 was identified in the rabbit HEV, and this insertion may play a role in the species tropism of HEV.  相似文献   
52.
The in vitro determination of the effects of some pharmacological agents on the outer diameter and axial tension of human Fallopian tube ampullar segments showed that some drugs may act on the circular and longitudinal smooth muscle layers relatively separately. PGF2 alpha elicited an excitatory response in both muscle layers while norepinephrine and isoproterenol decreased the activity. Oxytocin and indomethacin had relatively limited effects on the spontaneous motility of the ampullar segments. The calcium antagonist verapamil inhibited the spontaneous periodic activity.  相似文献   
53.
A strain of 1,507 typised donors enables 15.97 average donors to be selected for a thrombocyte transfusion in one of 75 patients selected at random with HLA antibodies being previously determined (1 to 66 donors per patient). HLA compatible donors were found for 72 patients (97.33 per cent). More than 5 HLA compatible donors could be found for 58 patients. The high number of compatible donors is based on the fact that among 1,507 donors there were 156 HLA homozygotes and 556 donors with 3 HLA-A or B-antigens respectively. Compatibility in the ABO-system was not taken into account.  相似文献   
54.
Lateral membrane heterogeneity, in the form of lipid rafts and microdomains, is currently implicated in cell processes including signal transduction, endocytosis, and cholesterol trafficking. Various biophysical techniques have been used to detect and characterize lateral membrane domains. Among these, Förster resonance energy transfer (FRET) has the crucial advantage of being sensitive to domain sizes smaller than 50-100 nm, below the resolution of optical microscopy but, apparently, similar to those of rafts in cell membranes. In the last decade, several formalisms for the analysis of FRET in heterogeneous membrane systems have been derived and applied to the study of microdomains. They are critically described and illustrated here.  相似文献   
55.
A detailed picture of hydration and counterion location in the B-DNA duplex d(GCGAATTCG) is presented. Detailed data have been obtained by single crystal x-ray diffraction at atomic resolution (0.89 A) in the presence of Mg(2+). The latter is the highest resolution ever obtained for a B-DNA oligonucleotide. Minor groove hydration is compared with that found in the Na(+) and Ca(2+) crystal forms of the related dodecamer d(CGCGAATTCGCG). High resolution data (1.45 A) of the Ca(2+) form obtained in our laboratory are used for that purpose. The central GAATTC has a very stable hydration spine identical in all cases, independent of duplex length and crystallization conditions (counterions, space group). However, the organization of the water molecules (tertiary and quaternary layers) associated with the central spine vary in each case.  相似文献   
56.

Myrtaceae, Lauraceae and Fabaceae are regarded as essential floristic elements of Atlantic forests due to their outstanding species richness, endemism levels, and ecological functions. Nonetheless, Atlantic forests are being subjected to multiple human disturbances that compromise the conservation of their flora. This study, therefore, intended to address whether there exist potential areas for conservation with great richness of tree/shrub species of the aforementioned families in different forest types within the subtropical Atlantic Forest. For this, data collected systematically across?~?23% of the subtropical Brazilian Atlantic Forest were employed. The univariate Local Moran I statistic was used to search for clusters of sample plots with great richness of species of the studied families. Six clusters were found throughout the evergreen rainforest (ERF) and Araucaria forest (AF), and most of them contained more than half of all species of these families observed on the sample plots, besides many others belonging to different families. A cluster of Myrtaceae and a cluster of Lauraceae in the ERF were the only ones that overlapped protected areas. The clusters of Lauraceae in the AF, located in ecotone zones with the ERF, had?~?50% of native forest cover, whereas the clusters of Myrtaceae and Fabaceae had?~?10% of forest cover. Inasmuch as forests in the study area have been heavily exploited, the clusters have relevant conservation value. Protected areas could be expanded or converted into more restrictive conservation categories to enhance the conservation of populations of key elements of the Atlantic Forest. Yet, non-protected areas deserve attention regarding the management of forest resources and conservation-by-use strategies.

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57.
58.
Paleoecology allows construction of paleoenvironmental models, faunal changes and evolutionary trends of paleontological taxa using modern analogs. However, when linking modern analogs to paleontological taxa in paleoecological reconstruction, differential taxonomic preservation in the fossil record has to be taken into account. Paleontologists have known the biased nature of the fossil record since Efremov’s publication on taphonomy in 1940, yet many ecological models of habitats associated with hominins in paleontological and archaeological sites in Africa and elsewhere barely address the complexity of the fossil record. We use randomly sampled ungulates from modern biomes in a comparative taxonomic abundance to demonstrate how the combination of modern thanatocoenoses and taphocoenoses, when used in reference to habitat-specific biocoenosis, produce better inferences of past habitats in paleontological and archaeological sites than approaches currently used.  相似文献   
59.
Kitner  Miloslav  Poulícková  Aloisie 《Hydrobiologia》2003,506(1-3):519-524

The littoral zone of shallow water bodies in the Czech Republic has been studied quite consistently at several fishponds. The use of algae, especially diatoms, for the monitoring of the state of lotic freshwater also has a long tradition. The main objective of the presented paper is to validate the feasibility of the use of littoral periphyton comunities for the biomonitoring of standing waters. At the investigated sites, littoral periphytic diatoms were studied together with selected enviromental variables (pH, conductivity, nutrients – especially total phosphorus) on three types of natural substrates (epilithon, epiphyton, epipelon). The evaluation of the diatom community was performed on the basis of the checklists of algal indicator species published by authors from the Czech Republic, Austria and the Netherlands. The data were subjected to statistical software NCCS 2000 (GLM Anova and ``Ward's minimum'' variance cluster analysis). Littoral periphytic diatoms appear to be good indicators of the fishpond water quality. The selected substrates show non-significant differences therefore the average values from all substrates were used. The best indicatory system for evaluation of Czech fishponds was van Dam's index.

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60.
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