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1.
The first case of severe acute respiratory syndrome(SARS)in Guangdong province was reported on2Jan2003,whileretrospective survey has datedthe first index case on16Nov2002.In months that followed,pandemic of SARS widelyspread over the world until July2003,infecting8454people and claiming908deathsin39countries andregions global-ly.On16Dec2003,a32years old photographerlivinginsuburban Guangzhou presented withsymptoms of SARSinfec-tion.There were3other ensuing cases betweenthe end of2003and…  相似文献   

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Zusammenfassung Alle Formen von Leben entstanden aus der primitiven Zelle, betrachtet eher als eine Art denn als ein Individuum, welches die Fähigkeit für ununterbrochene Selbst-Teilung besass. Fortgesetzte Vermehrung der Zellen mag eins von drei verschiedenen Verfahren folgen: 1. Die zwei Zellen von jeder Teilung hervorgehend, mögen sich vollständig von einander trennen; diese Linie der Entwicklung der primitiven Zelle rief die Protozoa hervor. 2. Während die Zellen sich teilen, mögen sie mehr oder weniger unregelmässig zusammen hängen. Diese Linie rief die Porifera (Schwämme) hervor. 3. Die sich teilenden Zellen mögen regelmässig zusammenhängen, eine Blastula und eine Gastrula bildend. Die Gastrula ist fähig eine unbestimmte Anzahl von Variationen hervorzubringen, und durch diese Variationen in der Gastrula entstanden alle Tier-Typen ausser der Protozoa und der Porifera.Diese Linien der Entwicklung von der einzelnen Zelle stellen alle die physischen und geometrischen entfaltungsfähigen Möglichkeiten, denkbar im Falle von Zellen, dar, die die Kraft besitzen sich durch Selbst-Teilung zu vermehren. Da diese entfaltungsfähigen Linien einfach mechanische Antworten auf die geometrischen und physischen Eigentümlichkeiten sind, eigen der Vermehrung der sich selbst teilenden Zellen, so gibt es keine Rechtfertigung für die Annahme einer bestimmten Ordnung in ihrem Vorkommen. Es ist logischer anzunehmen, dass die primitive Zelle gleich nach ihrem Erscheinen sich nach jeder möglichen Richtung gleichzeitig entwickelte, kurz, dass alle die Haupttypen des Tierlebens gleichzeitig erschienen.Es gibt keinen Beweis gegen diese Annahme, welche in Übereinstimmung mit dem geologischen Hintergrund des Lebens ist, wie wir es verstehen; mit der Fossilien-Urkunde, wie illustriert durch Fossilien von genau vergleichbaren Umgebungen; und mit der angenommenen Nötigkeit für ein System von Kontrolle und Ausgleich zwischen den verschiedenen Typen von Leben.
Résumé Toutes les formes de la vie proviennent d'une cellule primitive unique, considérée comme espèce plutôt que comme individu, possédant le pouvoir de se multiplier par bi-partition répétée. La propagation continue de cellules peut avoir lieu de trois façons différentes: 1. Les deux cellules, après la division, peuvent se séparer complètement l'une de l'autre; cette forme de propagation de la cellule primitive a donné lieu aux Protozoaires. 2. Les cellules, en se divisant, peuvent rester liées plus ou moins irrégulièrement; cette forme de propagation caractérise les Porifères (spongiées). 3. Les cellules, en se divisant, peuvent rester liées selon un arrangement régulier, en formant une blastula et une gastrula; la gastrula peut être formée selon un infinité de modalités, et c'est à ces différences de la formation de la gastrula que sont dues toutes les espèces animales exceptés les Protozoaires et les spongiées.Ces formes de propagation de la cellule unique représentent la somme des possibilités d'arrangement permises par les lois de la géométrie et de la physique. Du moment que ces procédés de propagation sont soumis à un arrangement mécanique gouverné par des lois physiques et géométriques, il n'y a pas lieu d'admettre qu'il y ait, dans leur succession, d'ordre déterminé. Il est plus logique de supposer qu'aussitôt parue la cellule primitive se soit propager simutanément dans toutes les directions concevables, en d'autres mots que toutes les phyla animales se soient différenciées au même moment.Aucune preuve ne démont cette hypothèse qui, d'ailleurs, concorde avec les prémises géologiques de la vie telles que nous les comprenons, avec les vestiges fossilisés de couches géologiques strictément comparable, et avec la théorie qui admet l'établissement de l'équilibre entre les différentes espèces animales au moyen d'un contrôle et de limitations mutuelles.
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3.
PraderWilli syndrome (PWS) occurs in about 1 in 15,000 individuals and is a contiguous gene disorder causing developmental disability, hyperphagia usually with obesity, and behavioral problems, including an increased incidence of psychiatric illness. The genomic imprinting that regulates allele-specific expression of PWS candidate genes, the fact that multiple genes are typically inactivated, and the presence of many genes that produce functional RNAs rather than proteins has complicated the identification of the underlying genetic pathophysiology of PWS. Over 30 genetically modified mouse strains that have been developed and characterized have been instrumental in elucidating the genetic and epigenetic mechanisms for the regulation of PWS genes and in discovering their physiological functions. In 2011, a PWS Animal Models Working Group (AMWG) was established to generate discussions and facilitate exchange of ideas regarding the best use of PWS animal models. Here, we summarize the goals of the AMWG, describe current animal models of PWS, and make recommendations for strategies to maximize the utility of animal models and for the development and use of new animal models of PWS.  相似文献   

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Schub T 《Lab animal》2001,30(6):39-42
There is evidence of a shortage of qualified laboratory animal veterinarians. Based on conversations with directors of animal care programs and heads of laboratory animal medicine training program, the author explores the problem of attracting veterinary school graduates to the field.  相似文献   

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Animals live in close association with microorganisms, mostly prokaryotes, living in or on them as commensals, mutualists or parasites, and profoundly affecting host fitness. Most animal–microbe studies focus on microbial community structure; for this project, allometry (scaling of animal attributes with animal size) was applied to animal–microbe relationships across a range of species spanning 12 orders of magnitude in animal mass, from nematodes to whales. Microbial abundances per individual animal were gleaned from published literature and also microscopically counted in three species. Abundance of prokaryotes/individual versus animal mass scales as a nearly linear power function (exponent = 1.07, R2 = 0.94). Combining this power function with allometry of animal abundance indicates that macrofauna have an outsized share of animal-associated microorganisms. The total number of animal-associated prokaryotes in Earth''s land animals was calculated to be 1.3–1.4 × 1025 cells and the total of marine animal-associated microbes was calculated to be 8.6–9.0 × 1024 cells. Animal-associated microbes thus total 2.1–2.3 × 1025 of the approximately 1030 prokaryotes on the Earth. Microbes associated with humans comprise 3.3–3.5% of Earth''s animal-associated microbes, and domestic animals harbour 14–20% of all animal-associated microbes, adding a new dimension to the scale of human impact on the biosphere. This novel allometric power function may reflect underlying mechanisms involving the transfer of energy and materials between microorganisms and their animal hosts. Microbial diversity indices of animal gut communities and gut microbial species richness for 60 mammals did not indicate significant scaling relationships with animal body mass; however, further research in this area is warranted.  相似文献   

9.
Glutamate-induced neurotoxicity plays an important role in neurological and psychiatric diseases. Thus, much attention has been given to the potential neuroprotective role of glutamate receptor antagonists, especially to those acting on the N-methyl-d-aspartate (NMDA) subtype. However, in addition to their neuroprotective potential, these compounds have also neurotoxic and psychotogenic properties. In the present study we used repeated injections of MK801 to examine if this non-competitive NMDA receptor antagonist could be used to produce schizophrenia-like alterations in behavior and brain metabolism in animals. Rats were given injections of MK801 (0.1 mg/kg) on six consecutive days, the last dose together with [1-(13)C]glucose and [1,2-(13)C]acetate, to probe neuronal and astrocytic metabolism, respectively. Analyses of extracts from parts of the frontal cortex plus cingulate and retrosplenial cortices and temporal lobes were performed using (13)C and (1)H magnetic resonance spectroscopy. Changes in glutamate and glutamine were restricted to the temporal lobe, in which amounts and labeling from [1-(13)C]glucose and [1,2-(13)C]acetate were increased compared to control. Locomotor activity was slightly higher in rats treated with MK801 compared to untreated animals. Metabolic changes did not resemble the alterations occurring in schizophrenia and those after repeated high dose (0.5 mg/kg) [Kondziella, D., Brenner, E., Eyjolfsson, E.M., Markinhuhta, K.R., Carlsson, M., Sonnewald, U., 2005. Glial-neuronal interactions are impaired in the schizophrenia model of repeated MK801 exposure. Neuropsychopharmacology, Epub ahead of print] but rather those caused by MK801 seen after a single high dose (0.5 mg/kg) [Brenner, E., Kondziella, D., Haberg, A., Sonnewald, U., 2005. Impaired glutamine metabolism in NMDA receptor hypofunction induced by MK801. J. Neurochem. 94, 1594-1603.].  相似文献   

10.
Many ecological studies rely heavily on chemical analysis of plant and animal tissues. Often, there is limited time and money to perform all the required analyses and this can result in less than ideal sampling schemes and poor levels of replication. Near infrared reflectance spectroscopy (NIRS) can relieve these constraints because it can provide quick, non-destructive and quantitative analyses of an enormous range of organic constituents of plant and animal tissues. Near infrared spectra depend on the number and type of CH, NH and OH bonds in the material being analyzed. The spectral features are then combined with reliable compositional or functional analyses of the material in a predictive statistical model. This model is then used to predict the composition of new or unknown samples. NIRS can be used to analyze some specific elements (indirectly – e.g., N as protein) or well-defined compounds (e.g., starch) or more complex, poorly defined attributes of substances (e.g., fiber, animal food intake) have also been successfully modeled with NIRS technology. The accuracy and precision of the reference values for the calibration data set in part determines the quality of the predictions made by NIRS. However, NIRS analyses are often more precise than standard laboratory assays. The use of NIRS is not restricted to the simple determination of quantities of known compounds, but can also be used to discriminate between complex mixtures and to identify important compounds affecting attributes of interest. Near infrared reflectance spectroscopy is widely accepted for compositional and functional analyses in agriculture and manufacturing but its utility has not yet been recognized by the majority of ecologists conducting similar analyses. This paper aims to stimulate interest in NIRS and to illustrate some of the enormous variety of uses to which it can be put. We emphasize that care must be taken in the calibration stage to prevent propagation of poor analytical work through NIRS, but, used properly, NIRS offers ecologists enormous analytical power. Received: 10 October 1997 / Accepted: 12 May 1998  相似文献   

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Mann MD  Prentice ED 《Lab animal》2004,33(1):26-31
Whether IACUCs should review animal research protocols for scientific merit is not addressed in the federal regulations, resulting in ongoing confusion on the subject. The authors examine this issue, discuss the pros and cons, suggest how IACUCs can go about reviewing protocols for scientific merit, and question what effect recent changes in regulations will have on this issue.  相似文献   

13.
Abstract  Interactions between plants and animals are analyzed starting from the advantages gained by animals and proceeding to those gained exclusively by plants. These interactions are essentially of five types: 1. predation of plants by animals; 2. benevolence of plants towards certain animals to prevent or reduce predation; 3. predation by plants (carnivorous plants); 4. symbiosis and mutualism; 5. seduction and deception of animals by plants for dispersal of plant reproductive structures. All types of plants are preyed on by animals, though from as far back in evolution as algae, certain plant molecules reduce or prevent predation. In the most primitive land plants, other types of interactions beneficial for plants are encountered. More evolved land plants (angiosperms) show all facets of the five types of interaction, whereas in prokaryotic and eukaryotic algae there is only predation and in some cases countermeasures to avoid it. An evolutionary path leading from predation, the original condition, to seduction, deception and carnivory, is also postulated. Keywords Plants, Animals, Predation, Benevolence, Symbiosis, Mutualism, Pollination, Seed dispersal Subject codes: Animal Ecology, Plant Ecology, Evolutionary Biology  相似文献   

14.
The credibility of scientific research has been seriously questioned by the widely claimed “reproducibility crisis”. In light of this crisis, there is a growing awareness that the rigorous standardisation of experimental conditions may contribute to poor reproducibility of animal studies. Instead, systematic heterogenisation has been proposed as a tool to enhance reproducibility, but a real-life test across multiple independent laboratories is still pending. The aim of this study was therefore to test whether heterogenisation of experimental conditions by using multiple experimenters improves the reproducibility of research findings compared to standardised conditions with only one experimenter. To this end, we replicated the same animal experiment in 3 independent laboratories, each employing both a heterogenised and a standardised design. Whereas in the standardised design, all animals were tested by a single experimenter; in the heterogenised design, 3 different experimenters were involved in testing the animals. In contrast to our expectation, the inclusion of multiple experimenters in the heterogenised design did not improve the reproducibility of the results across the 3 laboratories. Interestingly, however, a variance component analysis indicated that the variation introduced by the different experimenters was not as high as the variation introduced by the laboratories, probably explaining why this heterogenisation strategy did not bring the anticipated success. Even more interestingly, for the majority of outcome measures, the remaining residual variation was identified as an important source of variance accounting for 41% (CI95 [34%, 49%]) to 72% (CI95 [58%, 88%]) of the observed total variance. Despite some uncertainty surrounding the estimated numbers, these findings argue for systematically including biological variation rather than eliminating it in animal studies and call for future research on effective improvement strategies.

An experimenter heterogenisation was not sufficient to prevent idiosyncratic results in a multi-laboratory setting. Astonishingly, neither the experimenter nor the laboratory accounted for the main portion of the observed variation, but a high amount of residual variation in fact remained unexplained despite strict standardisation regimes.  相似文献   

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There is a remarkable similarity in the appearance of groups of animal species during periods of their embryonic development. This classic observation has long been viewed as an emphatic realization of the principle of common descent. Despite the importance of embryonic conservation as a unifying concept, models seeking to predict and explain different patterns of conservation have remained in contention. Here, we focus on early embryonic development and discuss several lines of evidence, from recent molecular data, through developmental networks to life-history strategies, that indicate that early animal embryos are not highly conserved. Bringing this evidence together, we argue that the nature of early development often reflects adaptation to diverse ecological niches. Finally, we synthesize old and new ideas to propose a model that accounts for the evolutionary process by which embryos have come to be conserved.  相似文献   

17.
Scale remains a foundational concept in ecology.Spatial scale,for instance,has become a central consideration in the way we understand landscape ecology and animal space use.Meanwhile,scale-dependent social processes can range from fine scale interactions to co-occurrence and overlapping home ranges.Furthermore,sociality can vary within and across seasons.Multilayer networks promise the explicit integration of the social,spatial,and temporal contexts.Given the complex interplay of sociality and animal space use in heterogeneous landscapes,there remains an important gap in our understanding of the influence of scale on animal social networks.Using an empirical case study,we discuss ways of considering social,spatial,and temporal scale in the context of multilayer caribou social networks.Effective integration of social and spatial processes,including biologically meaningful scales,within the context of animal social networks is an emerging area of research.We incorporate perspectives that link the social environment to spatial processes across scales in a multilayer context.  相似文献   

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A suspension of freeze-thawed mitochondria mixed with purple membranes from Halobacteria was illuminated with visible light. It was found that the light exposure prevented inhibition of succinate oxidation. The illumination also led to a decrease in inhibition of the rate of ferricyanide reduction by rat liver mitochondria in the presence of succinate. Both phenomena are explained by the fact that oxalacetate inhibition of succinate dehydrogenase is prevented by light-induced energization of mitochondrial membranes due to the contact with purple membranes.  相似文献   

20.
The nuclei of the rat liver, heart, thymus and of the mouse liver isolated in sucrose gradient reveal ATPase sensitive to bicarbonate, sulfite, azide and thiocyanate. The admixture of mitochondria and submitochondrial particles in the nuclear preparation was found negligible, which could not contribute to the anion ATPase in the nuclei. This was demonstrated by the calculation and by the introducing of mitochondria into the nuclear preparations.  相似文献   

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