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排序方式: 共有1397条查询结果,搜索用时 15 毫秒
1.
Concentrations of the elements C, N, Fe, Na, K, Ca and Mg were analysed by chromatography and atomic absorption spectrometry in the whaleworm Anisakis simplex sensu lato. Nearly all mean inorganic element concentrations measured were higher in adult worms than in larval forms. Similarly, adults contained significantly higher nitrogen (i.e. lower C/N ratio values) than either eggs or larvae. Evidence for the significance of the parasitic life cycle stage and the systematic position of their hosts on the element concentration variability is discussed. 相似文献
2.
The rate of hexose transport was approximately 60% lower for both the high- and the low-affinity components of hexose uptake
when a glucose-6-phosphate isomerase mutant ofSaccharomyces cerevisiae was preincubated with glucose, as compared with preincubation with water. Similarly theJ
max value of the high-affinity system of the mutant was 25–35 % of the correspondingJ
max value for normal cells incubated with glucose. Accumulation of glucose 6-phosphate or of some other metabolite, such as fructose
6-phosphate or trehalose, may be responsible for this striking inhibition. 相似文献
3.
Substrate-induced H+ extrusion was studied in dilute (0.04–0.5 mg dry mass per mL) unbuffered suspensions ofS. cerevisiae. Wild-type strains 196-2 and K and 196-2-derived mutants altered in hexose transport, glucosephosphate isomerase, mannosephosphate
isomerase, pyruvate kinase, and arho petite mutant were characterized as to growth, biochemical and H+-pumping properties. Their H+ extrusion differed, depending on strain, growth conditions, and the H+-efflux-inducing substrate; the efficiency of the process depended critically on the balance between substrate uptake, its
dissimilation, attendant mobilization of energy sources and build-up of acidity sources in the cell, and the energy supply
to H+excreting systems. 相似文献
4.
R W van der Heijden H Bunschoten V Pascual F G Uytdehaag D M Osterhaus J D Capra 《Journal of immunology (Baltimore, Md. : 1950)》1990,144(7):2835-2839
We previously described the isolation and characterization of a human monoclonal anti-idiotypic antibody (Ab2) isolated from EBV-transformed human PBL after immunization with rabies vaccine. The present study concerns the molecular characteristics of the Ab2 and the germ-line elements that gave rise to it. The H chain of this antibody derives from the small VHV family of human V region gene segments. Parallel studies on the germ-line VHV gene isolated from the same individual revealed that the expressed molecule contains 19 nucleotide differences in the VH gene segment. The D segment of Ab2 could have arisen by a D to D fusion; the J segment is a JH6. Extensive somatic variation evident in the H chain variable region of this naturally arising monoclonal anti-idiotypic antibody suggests that this Ab2, the product of a CD5+ B cells, was the consequence of an Ag-driven immune response. 相似文献
5.
R González-Cámpora C Otal-Salaverri P Panea Flores A Hevia-Vázquez A Gómez Pascual V San Martín Díez 《Acta cytologica》1992,36(2):152-158
Peripheral neuroepithelioma of soft tissue is a malignant primitive neuroectodermal tumor that appears both in children and adults and usually has a poor outcome. Fine needle aspiration on two patients with tumors in the lower limbs showed small round cells with unipolar processes and a tendency to form Homer-Wright rosettes. The cells had a round to oval nucleus with fine chromatin, up to four small, conspicuous nucleoli and vacuolated, periodic acid-Schiff-positive cytoplasm. The diagnosis was supported by electron microscopic study of the aspirate, which showed features of neuroblastic differentiation (i.e., neurosecretory granules), and by histologic, immunohistochemical and cytogenetic study of the resected tumors. 相似文献
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8.
Murielle Rinaldi-Carmona Francis Barth Michel Haulme David Shire Bernard Calandra Christian Congy Serge Martinez Jeanne Maruani Gervais Nliat Daniel Caput Pascual Ferrara Philippe Soubri Jean Claude Brelire Grard Le Fur 《FEBS letters》1994,350(2-3):240-244
SR141716A is the first selective and orally active antagonist of the brain cannabinoid receptor. This compound displays nanomolar affinity for the central cannabinoid receptor but is not active on the peripheral cannabinoid receptor. In vitro, SR141716A antagonises the inhibitory effects of cannabinoid receptor agonists on both mouse vas deferens contractions and adenylyl cyclase activity in rat brain membranes. After intraperitoneal or oral administration SR141716A antagonises classical pharmacological and behavioural effects of cannabinoid receptor agonists. This compound should prove to be a powerful tool for investigating the in vivo functions of the anandamide/cannabinoid system. 相似文献
9.
The invasion kinetics ofhobo transposable element in theDrosophila melanogaster genome was studied byin situ hybridization on the polytene chromosomes. Six independent lines ofDrosophila melanogaster flies that had been previously transformed by microinjection of the pHFL1 plasmid containing a completehobo element were followed over 50 generations. We observed thathobo elements were scattered on each of the chromosome arms, with more insertion sites on the 3R arm. The total number of insertion sites remains quite small, between four and six, at generation 52. On the 2R arm, a short inversion appeared once at generation 52. Most of the integration sites reported here were already described for several transposons but some of them appear to be hotspots forhobo elements. 相似文献
10.
司光伟 《生物化学与生物物理进展》2023,50(6):1243-1243
Acetylcholine, the first identified neurotransmitter, plays crucial roles in various brain functions. One well-known case is its involvement as an activating neurotransmitter in the regulation of locomotion. However, its inhibitory regulatory role, particularly in locomotion, remains poorly understood. In a study conducted by Polat et al., the authors investigated the inhibitory role of acetylcholine in locomotion in C. elegans. In this organism, the acetylcholine-gated chloride channel receptor consists of four subunits. The authors thoroughly examined the loss-of-function of each subunit in movement regulation. Interestingly, the mutant worms were still capable of performing various movements such as forward, backward crawling, and turning, suggesting that the overall movement was not significantly affected. However, quantitative behavior analysis revealed subtle yet significant differences in the timing and postures of the movement in these mutants. Furthermore, the authors employed optogenetics to stimulate a specific neuron involved in backward crawling and demonstrated that the loss-of-function of the receptors in individual neurons affects the transitioning between locomotion modes.
This work provides evidence for the inhibitory regulatory role of acetylcholine in locomotion. The loss-of-function of acetylcholine-gated chloride channel receptors likely disrupts the balance of neuronal and circuit physiology, thereby affecting the regulation of locomotion. Moreover, this study highlights the powerful role of quantitative behavior analysis in discovering and understanding more sophisticated functions of neural circuits. 相似文献