980 resultados para Guinea-pigs


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We examined protein polymorphism of 20 native pig breeds in China and 3 introduced pig breeds. Thirty loci have been investigated, among which six loci were found to be polymorphic. Especially, the polymorphism of malate dehydrogenase (MDH), adenylate kinase (AK), and two new alleles of adenosine deaminase (ADA) had not been reported in domestic pigs and wild pigs. The percentage of polymorphic loci (P), the mean heterozygosity (H), and the mean number of alleles (A) are 0.200, 0.065, and 1.300, respectively. The degree of genetic variability of Chinese pigs as a whole was higher than that of goats, lower than that of cattle and horses, and similar to that of sheep. Using the gene frequencies of the 30 loci, Nei's genetic distance among the 20 native breeds in China and 3 introduced pig breeds was calculated by the formula of Nei. The program NEIGHBOR in PHYLIP 3.5c was chosen to construct an UPGMA tree and a NJ tree. Our results show that, of the total genetic variation found in the native pig breeds in China, 31% (0.31) is ascribable to genetic differences among breeds. About 69% of the total genetic variation is found within breeds. Most breeds are in linkage disequilibrium. The patterns of genetic similarities between the Chinese native pig breeds were not in agreement with the proposed pig type classification.

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Background: Previously reported evidence indicates that pigs were independently domesticated in multiple places throughout the world. However, a detailed picture of the origin and dispersal of domestic pigs in East Asia has not yet been reported. Results:

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Mitochondrial DNA (mtDNA) of six breeds of native domestic pigs from Yunnan province, southwest China, and two wild boars obtained from Sichuan, China, and Vietnam was analyzed using 20 restriction endonucleases that recognize six nucleotides. Restriction maps were made by double-digestion methods and polymorphic sites were located on the map. According to their mtDNA restriction types, all the breeds were classified into six groups. Genetic distances among groups were calculated to define their phylogenetic relationships. The relationship between the Sichuan wild boar and domestic pigs is close, while the Vietnamese wild boar is relatively far from them, so the domestic pigs in southwest China are likely to have originated from a wild pig which distributed in west China. We compare our results with previous reports in literature and discuss the relationship among Chinese pigs, Japanese pigs, and European pigs. The mtDNA cleavage pattern of the Mingguang pig digested by EcoRV was identical to that of Duroc; mutations at the EcoRI site, detected in the mtDNA of two Dahe pigs, are the same as in the Vietnamese wild boar, suggesting that mutational hot spots exist in the mtDNA of pigs.

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A highly active cobra venom factor (CVF) was isolated from the venom of Naja kaouthia by sequential column chromatography. It displays strong anticomplementary activity, and has 1515 U of anti complementary activity per mg protein. A single dose of 0.1 mg/kg CVF given i.v. to rats completely abrogated complement activity for nearly 5 days. Given 0.02 mg/kg of CVF. the complement activity of rats was reduced by more than 96.5% in 6 It. In guinea pig-to-rat heart transplant model, rats treated with a single dose of 0.05 mg/kg CVF had significantly prolonged xenograft survival (56.12 +/- 6.27 h in CVF-treated rats vs. 0.19 +/- 0.07 h in control rats, P < 0.001). (C) 2003 Elsevier Ltd. All rights reserved.

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Deep ocean sediments off the west coast of Africa exhibit a peculiar undrained strength profile in the form of a crust, albeit of exceptionally high water content, overlying normally consolidated clay. Hot-oil pipelines are installed into these crustal sediments, so their origins and characteristics are of great interest to pipeline designers. This paper provides evidence for the presence of burrowing invertebrates in crust material, and for the way sediment properties are modified through their creation of burrows, and through the deposition of faecal pellets. A variety of imaging techniques are used to make these connections, including photography, scanning electron microscopy and X-ray computer tomography. However, the essential investigative technology is simply the wet-sieving of natural cores, which reveals that up to 60% by dry mass of the crustal material can consist of smooth, highly regular, sand-sized capsules that have been identified as the faecal pellets of invertebrates such as polychaetes. Mechanical tests reveal that these pellets are quite robust under effective stresses of the order of 10 kPa, acting like sand grains within a matrix of fines. Their abundance correlates closely with the measured strength of the crust. While this can easily be accepted in the context of a pellet fraction as high as 60%, the question arises how a smaller proportion of pellets, such as 20%, is apparently able to enhance significantly the strength of a sediment that otherwise appears to be normally consolidated. A hypothesis is suggested based on the composition of the matrix of fines around the pellets. These appear to consist of agglomerates of clay platelets, which may be the result of the breakdown of pellets by other organisms. Their continued degradation at depths in excess of 1 m is taken to explain the progressive loss of crustal strength thereafter.

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De acuerdo a la normativa de TFEs el repositorio no puede dar acceso a este trabajo. Para consultarlo póngase en contacto con el tutor del trabajo. Puede acceder al resumen del mismo pinchando en el pdf adjunto

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Dissertação apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Acção Humanitária, Cooperação e Desenvolvimento

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There are considerable efforts by governments, non-governmental organizations (NGOs), and academia to integrate marine conservation initiatives and customary practices, such as taboos that limit resource use. However, these efforts are often pursued without a fundamental understanding of customary institutions. This paper examines the operational rules in use and the presence of institutional design principles in long-enduring and dynamic customary fisheries management institutions in Papua New Guinea, Indonesia, and Mexico. Rather than a "blue print" for devising long-enduring institutions, this study relies on the design principles as a starting point to organize an inquiry into the institutional diversity found in customary governance regimes. Three important trends emerged from this comparative analysis: (1) despite it being notoriously difficult to define boundaries around marine resources, almost 3/4 of the cases in this study had clearly defined boundaries and membership; (2) all of the customary institutions were able to make and change rules, indicating a critical degree of flexibility and autonomy that may be necessary for adaptive management; (3) the customary institutions examined generally lacked key interactions with organizations operating at larger scales, suggesting that they may lack the institutional embeddedness required to confront some common pool resources (CPR) challenges from the broader socioeconomic, institutional and political settings in which they are embedded. Future research will be necessary to better understand how specific institutional designs are related to social and ecological outcomes in commons property institutions. © 2011 Elsevier Ltd.

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Four pigs, three with focal infarctions in the apical intraventricular septum (IVS) and/or left ventricular free wall (LVFW), were imaged with an intracardiac echocardiography (ICE) transducer. Custom beam sequences were used to excite the myocardium with focused acoustic radiation force (ARF) impulses and image the subsequent tissue response. Tissue displacement in response to the ARF excitation was calculated with a phase-based estimator, and transverse wave magnitude and velocity were each estimated at every depth. The excitation sequence was repeated rapidly, either in the same location to generate 40 Hz M-modes at a single steering angle, or with a modulated steering angle to synthesize 2-D displacement magnitude and shear wave velocity images at 17 points in the cardiac cycle. Both types of images were acquired from various views in the right and left ventricles, in and out of infarcted regions. In all animals, acoustic radiation force impulse (ARFI) and shear wave elasticity imaging (SWEI) estimates indicated diastolic relaxation and systolic contraction in noninfarcted tissues. The M-mode sequences showed high beat-to-beat spatio-temporal repeatability of the measurements for each imaging plane. In views of noninfarcted tissue in the diseased animals, no significant elastic remodeling was indicated when compared with the control. Where available, views of infarcted tissue were compared with similar views from the control animal. In views of the LVFW, the infarcted tissue presented as stiff and non-contractile compared with the control. In a view of the IVS, no significant difference was seen between infarcted and healthy tissue, whereas in another view, a heterogeneous infarction was seen to be presenting itself as non-contractile in systole.

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info:eu-repo/semantics/published

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A pedunculate barnacle, Leucolepas longa, occurs in densities over 1000 individuals m[minus sign]2 on the summit of a small seamount near New Ireland, Papua New Guinea. Most of the population grows on vesicomyid clams projecting from sulphide-rich sediments, or on their dead shells, but the barnacle also settles on rock and on tubes of a vestimentiferan. Collections of several hundred barnacles allowed comparison of population and reproductive characteristics. The barnacle is a suspension feeder with a lightly-armoured stalk that can grow to 40 cm above the bottom. Growth appears to be rapid and both reproduction and recruitment are continuous. The barnacles brood egg masses within the capitular chamber and 46% of one sample was brooding. Lecithotrophic nauplii released upon retrieval to the surface were cultivated for 45 days. Metamorphosis to Stage IV yielded an actively swimming larva about 1 mm long overall, which still contained lipid reserves, indicating capacity for wide dispersal