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关键词： 微生物分析   定义   饲料   微生物   微生物学   食品   梭菌属   细菌计数方法  

标准号: ISO 7937-1997

关键词： 饲料   检测   抽样方法   食品   水平的   微生物分析   微生物   方法   验证   定义   试验媒体   介质   微生物学  

标准号: DIN EN ISO 11290-1-1997

关键词： 硕大利什曼原虫   PCR   扩增   动物   虫株  

摘要： 硕大利什曼原虫(***)的自然疫源地为都兰平原的广大地区,与保虫宿主大沙鼠(Rhombomys opimus)的分布是一致的。原认为在这种保虫宿主种群中传播的利什曼原虫就是硕大利什曼原虫,它对人有很大毒力和感染性,但近年来由于新技术的应用,发现

关键词： Embryonic Development   Genes   Mutation   Abnormalities   Animals   Embryonic Induction   Humans   Morphogenesis   Phenotype   Signal Transduction   Syndrome   Zebrafish  

摘要： In an accomplishment of historic proportions, reported as a group of 36 papers in the December issue of Development, scientists at the Max-Planck-Institut fuer Entwicklungsbiologie in Tuebingen and Massachusetts General Hospital in Boston have initiated a systematic genetic analysis of how the vertebrate embryo is formed. Led by Christiane Nuesslein-Volhard and Wolfang Driever, the groups have amassed and begun to analize a collection of more than 1800 developmental mutants representing defects in about 500 different genes that contribute to the form and function of the zebrafish (Danio rerio) embryo. The seminal insights garnered from a similar analysis of Drosophila embryogenesis were recognized last year by the Nobel committee, and we can expect that the current assault on the zebrafish embryo, which is unprecedented in its scale and method of approach in vertebrates, will have an equal impact on future research. The timing of the effort is superb, given the relatively recent appreciation of the degree to which both the molecules and the logic underpinning embryonic development are conserved throughout the vertebrates. As a result, the benefits to be accrued from analyses of these mutants are profound. We can anticipate that study of the zebrafish mutants will yield insights into the genes and mechanisms that coordinate normal vertebrate embryogenesis and that, when altered, result in a variety of inherited disorders in humans.

关键词： Morocco   upper Miocene   terrestrial environment   magnetostratigraphy   biostratigraphy   faunal provinces  

摘要： A magnetostratigraphic study has been carried out on a middle Miocene to upper Pliocene lacustrine sedimentary deposit in the central part of the Ait Kandoula basin, which contains micromammal faunas and is situated in the southern High Atlas (Morocco). In total, 113 samples were subjected to paleomagnetic analysis: 60 out of the 113 studied samples representing 52 different stratigraphic levels yielded a paleomagnetic direction and at least the polarity could be recognized in 42 specimens. Eleven specimens were submitted to AF demagnetization. The mean direction for normal-polarity samples was D = 349.4, I = 50.7 (N = 36, alpha(95) = 4.5, k = 27) and for reversed polarity samples D = 191.2, I = -53.4 (N = 16, alpha(95) = 12.32, k = 9). These results yielded a polarity sequence which we interpret as spanning from Chron C5n.2n to the beginning of Chron C3n.4n. This interpretation relies on biostratigraphic data previously proposed for a part of the continental fauna found in the basin. This result is in agreement with the 40Ar/39Ar dating previously carried out on a volcanic ash layer, which provided an age of 5.9 +/- 0.5 Ma [1] and which is shown here to be reversely magnetized. This layer is correlated here with the reverse polarity zone corresponding to Chron C3r. Biostratigraphic studies on the same section have shown that the micromammal levels extend here only from middle Vallesian to upper Turolian (upper Miocene). Four localities have yielded western European species of micromammals, indicating trans-Mediterranean terrestrial faunal exchanges between these two continents during the late Miocene. The European murid rodent Occitanomys is recorded for the first time in North Africa in level 8 of the Afoud section, an age younger than 5.32 Ma being assigned to this level by the present study. Level 1 of the same section yields the lagomorph Prolagus cf michauxi, with an age of 6.1 Ma. The magnetostratigraphic data suggest therefore that the beginning of terrestri

关键词： .Responding   Biological Significance   forward blocking  

摘要： Similarities between Pavlovian conditioning in nonhumans and causal judgment by humans suggest that similar processes operate in these situations. Notably absent among the similarities is backward blocking (i.e., retrospective devaluation of a signal due to increased valuation of another signal that was present during training), which has been observed in causal judgment by humans but not in Pavlovian responding by animals. The authors used rats to determine if this difference arises from the target cue being biologically significant in the Pavlovian case but not in causal judgment. They used a sensory preconditioning procedure in Experiments 1 and 2, in which the target cue retained low biological significance during the treatment, and obtained backward blocking. The authors found in Experiment 3 that forward blocking also requires the target cue to be of low biological significance. Thus, low biological significance is a necessary condition for a stimulus to be vulnerable to blocking.

关键词： AADC, Aromatic   l   -amino acid decarboxylase   ACh, Acetylcholine   ARC, Hypothalamic arcuate nucleus   COMT, Catechol-   O   -methyl transferase   CNS, Central nervous system   CVLM, Caudal ventrolateral medulla   l   -DOPA,   l   -3,4-Dihydroxyphenylalanine   DBH, Dopamine-β-hydroxylase   DOPAC, 3-4-Dihydroxyphenylacetic acid   DMV, Dorsal motor nucleus of the vagus   GABA, γ-Amino butyric acid   HPLC-ECD, High performance liquid chromatography with electrochemical detector   α-MPT, α-Methyl-   p   -tyrosine   NMDA,   N   -Methyl-   d   -aspartate   NSD-1015, 3-Hydroxybenzylhydrazine   NTS, Nucleus tractus solitarii   6-OHDA, 6-Hydroxydopamine   PEV, Hypothalamic periventricular nucleus   PHN, Posterior hypothalamic nucleus   RVLM, Rostral ventrolateral medulla   SHR, Spontaneously hypertensive rats   TH, Tyrosine hydroxylase   l   -threo-DOPS,   l   -threo-3,4-Dihydroxyphenylserine   TTX, Tetrodotoxin   WKY, Wistar Kyoto rats  

摘要： L-DOPA is proposed to be a neurotransmitter and/or neuromodulator in CNS. It is released probably From neurons, which may contain L-DOPA as an end-product, and/or from some compartment other than catecholamine-containing vesicles. The L-DOPA itself produces presynaptic and postsynaptic responses. All are stereoselective and most are antagonized by competitive antagonist. In striatum, L-DOPA is neuromodulator, mother of catecholamines, not only a precursor for dopamine but also a potentiator of children for presynaptic beta-adrenoceptors to facilitate dopamine release and postsynaptic D-2 receptors, and ACh release inhibitor. All may cooperate for Parkinson's disease. Meanwhile, supersensitization of increase in L-glutamate release to nanomolar levodopa was seen in Parkinson's model rats, which may relate to dyskinesia or ''on-off'' during chronic therapy. In lower brainstem, L-DOPA tonically activates postsynaptic depressor sires of NTS and CVLM and presser sites of RVLM. L-DOPA is probably a neurotransmitter of primary baroreceptor afferents terminating in NTS. GABA, the inhibitory neuromodulator for baroreflex in NTS, tonically Functions to inhibit, via GABA(A) receptors, L-DOPA release and depressor responses to levodopa. Levodopa inversely releases GABA, L-DOPAergic monosynaptic relay from NTS to CVLM and From PHN to RVLM is suggested. Tonic L-DOPAergic baroreceptor-aortic nerve-NTS-CVLM relay seems to carry baroreflex information. Disturbance of neuronal activity to release L-DOPA in NTS, loss of the activity in CVLM, enhancement of the activity with decreased decarboxylation and increase in sensitivity to levodopa in RVLM may be involved in maintenance of hypertension in SHR. This is a story of ''L-DOPAergic receptors'' with extremely high affinity and low density. Copyright (C) 1996 Elsevier Science Ltd.

关键词： Carnivore conservation, large   North America (Rocky Mountains)   Umbrella species   Wildlife preservation  

摘要： Large carnivores need large areas of relatively wild habitat, which makes their conservation challenging. These species play important ecological roles and in some cases may qualify as keystone species. Although the ability of carnivores to control prey numbers varies according to many factors and often is effective only in the short term, the indirect effects of carnivores on community structure and diversity can be great. perhaps just as important is the role of carnivores as umbrella species (i.e., species whose habitat area requirements encompass the habitats of many other species). Conservation areas large enough to support populations of large carnivores are likely to include many other species and natural communities, especially in regions such as the Rocky Mountains of Canada and the United States that have relatively low endemism. For example, a plan for recovery of grizzly bears (Ursus arctos) proposed by Shaffer (1992) covers, in part, 34% of the state of Idabo (compared to 8% covered by a U.S. Fish and Wildlife Service proposal) and would capture 10% or more of the statewide ranges of 71% of the mammal species, (67%) of the vegetation types in Idabo would have 10% or more of their statewide area included in the Shaffer plan. The U.S. Fish and Wildlife Service recovery zones provide a much poorer umbrella. The umbrella functions of large carnivores are expected to be poorer in regions with high endemism. The application of metapopulation concepts to large carnivore conservation has led to proposals for regional reserve networks composed of wilderness core areas, multiple-use buffer zones, and some form of connectivity. The exceptional vagility of most large carnivores makes such networks feasible in a region with low human population density, such as the Rocky Mountains, but mortality risks still need to be addressed. Roads are a major threat to carnivore recovery because of barrier effects, vehicle collisions, and increased accessibility of wild areas to

关键词： Pollinating insects   Trees   Phylogeny   Genera   Seeds   Pollen   Insect pollination   Biogeography