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排序方式: 共有233条查询结果,搜索用时 15 毫秒
1.
Age,seasonal and diel variations of the uricolytic enzymatic system in the snailsXeropicta arenosa (Ziegler) andCernuella virgata (Da Costa) 总被引:1,自引:0,他引:1
M. Lazaridou-Dimitriadou M. Kaloyianni 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1989,159(1):115-121
Summary The nitrogen catabolism of two snail species,Xeropicta arenosa andCermuella virgata, living on coastal dunes, was studied at different seasons and times of the day and at different ages. All the nitrogenous metabolites of the uricolytic enzymatic system were found in body homogenates of the snails, although uric acid was most abundant. The highest levels of these catabolites were observed during the day when the snails were inactive, while the lowest levels occurred during the night when excretion probably took place. The levels of most of the nitrogenous catabolites and the activities of the enzymes were higher in juveniles than in adults.All the enzymes of the uricolytic pathway were shown to be present in bothX. arenosa andC. virgata. 相似文献
2.
作者采用简单的螺胚生长抑制法,证明软体动物细胞具有DNA复制后修复功能,并受咖啡碱抑制。在没有其他诱变剂的参与下,咖啡碱并不损伤DNA,但也没有保护作用。 相似文献
3.
Consequences of food-attraction conditioning in Helix: a behavioral and electrophysiological study 总被引:1,自引:0,他引:1
M. Peschel V. Straub T. Teyke 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1996,178(3):317-327
Food-attraction conditioning is a learning phenomenon by which adult Helix pomatia acquire the ability to locate food through exposure to that particular food. Food-conditioned snails can be distinguished from naive snails during their approach to food. Naive snails keep their tentacles upright — whereas food-conditioned animals bend the tentacles down-ward, in a horizontal orientation, pointed in the direction of the food.Tentacle musculature is innervated by two peritentacular nerves (PTn), each projecting to approximately one hemi-section of the tentacle wall. Stimulating the peritentacular nerves caused the tentacles to bend downward in a manner reflecting the full complement of tentacle movements performed by conditioned snails.The neural correlate of tentacle movements was investigated in isolated ganglion preparations with the posterior tentacles attached. PT nerve activity was recorded while the olfactory epithelia were stimulated with natural food odors. Preparations obtained from conditioned animals responded with a substantial increase in unit activity (mean increase 280%) to stimulation with odor of the conditioned food but not to other odors. Preparations from naive animals did not respond to food odor stimulation. The electrophysiological results demonstrated that plasticity due to conditioning the snails in vivo survived dissection and could be monitored in vitro.Abbreviations
ext PTn
external peritentacular nerve
-
int PTn
internal peritentacular nerve 相似文献
4.
S. Pedler C. J. Fuery P. C. Withers J. Flanigan M. Guppy 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1996,166(6):375-381
We have examined metabolic depression in the land snail (Helix aspersa) during estivation, and have developed a tissue model of metabolic depression using an in vitro mantle preparation. The metabolic
rate of H. aspersa is depressed by 84% in vivo within 4 weeks of onset of estivation, and this metabolic depression is accompanied by a decrease
in haemolymph PO2 and pH, and an increase in haemolymph PCO2. The in vitro mantle preparation has a stable O2 consumption and energy charge, and an energy charge similar to that of mantle in vivo. The in vitro mantle is an O2-conforming tissue, with VO2 varying curvilinearly with PO2. Consequently, we have developed a mathematical method of calculating tissue VO2 at any PO2. These calculations show that under appropriate incubation conditions of pH and PO2, the mantle from estivating animals shows a stable in vitro metabolic depression of 48% compared to mantle from control snails.
The extrinsic effects of PO2 and pH account for 70% of the total in vitro metabolic depression of mantle tissue; intrinsic effectors contribute a further
30%.
Accepted April 26, 1996 相似文献
5.
J. K. Krontiris-Litowitz E. T. Walters D. J. McAdoo 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1994,163(8):671-675
The effects of stress produced by noxious cutaneous stimulation on the concentration of 18 amino acids in the hemolymph of Aplysia californica were examined. The concentration of alanine and glutamate increased in response to stress and remained elevated for at least 6 h. The total amino acid concentration in the hemolymph did not change significantly in response to stress. It is concluded that stress evokes an increase in circulating alanine and glutamate levels. These factors may then act in a paracrine, endocrine, or neuroendocrine manner to modify stress-associated behaviors.Abbreviations AA
amino acids(s)
- bw
body weight
- SEM
standard error of the mean
- SW
sea water 相似文献
6.
In an attempt to identify the tissue sources of biochemically purified antigenic fractions of Fasciola hepatica and Schistosoma mansoni, antisera were tested against plastic-embedded sections of worms of various ages by an indirect fluorescent-antibody-labeling technique. Antibodies prepared against antigens purified by chromatography of F. hepatica whole worm extract through concanavalin A-Sepharose 4B labeled the parenchyma and tegument of adult F. hepatica strongly while antibodies developed against antigens purified by antibody-affinity chromatography against antibodies of S. mansoni labeled only the parenchyma. Antigens common to these two groups clearly originated from F. hepatica parenchyma. Certain of these common antigens are known to provide significant protection in mice to challenge with S. mansoni cercariae, and in the present study antisera against F. hepatica extracts cross-labeled S. mansoni adult male parenchyma. Reciprocal cross-reactions between antisera against S. mansoni and the parenchyma of adult F. hepatica were also noted. FhFIIb, an extract of F. hepatica which Tailliez described as not cross-reacting with S. mansoni, was found to contain no F. hepatica parenchymal antigens. Antigenic fractions of F. hepatica and S. mansoni collected from the surface of worms after incubation in nonionic detergent were unexpectedly found to contain much parenchymal antigen, suggesting leakage of internal components into the supernatant during preparation. Antisera to F. hepatica developed during a natural infection in rabbits labeled tegumental components and gut strongly but did not react with parenchymal tissue. Antisera against extracts of adult schistosomes labeled the parenchyma of male worms and the glycocalyx of the cercarial tegument, indicating the presence of common antigens in the adult and the cercarial stage. Reciprocal reactions between anticercarial sera and adult sections provided further evidence of shared antigenicity. Antisera against S. mansoni egg antigens strongly labeled sections of eggs in liver tissue and cross-reacted with cercarial glycocalyx, indicating the existence of common antigens between these two stages. The antisera also cross-reacted with what appeared to be non-membrane-bound protein in the tegument of F. hepatica. The soluble egg antigen extract shared antigenicity with the parenchyma of both S. mansoni and F. hepatica but circumoval precipitin had no cross-reactivity with this tissue. Thus S. mansoni eggs contain nondiffusable components sharing antigenic specificity with adult parenchymal tissue.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
7.
Christopher J. Bayne Patricia M. Buckley Peggy C. DeWan 《Experimental parasitology》1980,50(3):409-416
Sporocysts of Schistosoma mansoni (PR1 strain) survive and grow in Biomphalaria glabrata PR albino strain snails, whereas they are encapsulated and die in B. glabrata 10R2 strain snails. These processes also occur in an in vitro system in which the only living cells are those of sporocysts and snail hemolymph. Hemocytes of the susceptible snail are normally not effective in damaging sporocysts. However, when the encounter occurred in the presence of cell-free plasma from resistant snails, previously impotent hemocytes severely damaged sporocysts in 24 hr. The cytotoxic capacity of resistant strain hemocytes was not altered by plasma from susceptible snails. Furthermore, it was retained even when plasma was replaced by culture medium free of snail components. The nature of the plasma factor(s) which facilitated damage by otherwise impotent hemocytes is discussed, and evidence is evaluated for the hypothesis that snail resistance is dependent upon the specificity of cytophilic factors present both in the plasma and on the hemocyte plasma membranes. 相似文献
8.
9.
Summary A main yolk component in the oocytes of the pulmonate snailPlanorbarius corneus L. has been isolated and identified as the iron storage protein ferritin by its ultrastructure, iron content, immuunological properties and behaviour in disc electrophoresis. As judged from acrylamide electrophoresis data and ultrastructural observations, yolk ferritin is an exogenous protein which is synthesised in the hepatopancreas and taken up by the oocytes by endocytosis. 相似文献
10.
E S Loker 《Experimental parasitology》1978,45(1):65-73
Laboratory-reared Lymnaea catascopium snails (1–269 days old) were exposed individually to different numbers of Schistosomatium douthitti miracidia. Increasing the exposure dosage from 3 to 10 miracidia generally increased infection rates, in some age classes up to 100%. Successful re-exposure of snails not infected after a primary exposure was possible. Neonatal snails were least likely to become infected, primarily because miracidia were not attracted to them. Snails 12–55 days old were most susceptible to infection. Miracidia were readily attracted to these snails, and many were ingested and subsequently penetrated the host esophageal wall. Miracidial penetration of external snail surfaces was rare. Susceptibility of older snails (65–269 days) progressively declined with age. Many miracidia were entangled and immobilized in mucus produced by these snails, and fewer were ingested. No conspicuous host cellular responses to mother sporocysts were observed in any of the snails sectioned. A comparison of susceptibility of deliberately stunted snails and comparably aged controls of normal size indicated that the former were more susceptible. 相似文献