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51.
Mario Maggi Guido Fantoni Alessandro Peri Stefano Giannini Maria Luisa Brandi Claudio Orlando Mario Serio 《The Journal of steroid biochemistry and molecular biology》1991,40(4-6):481-491
Oxytocin (OT) and V1 vasopressin (VP) receptors are present simultaneously in several tissues, including the uterus. In myometrium these receptors mediate contractility, while in endometrium they mediate the release of other uterotonic substances as endothelin (ET). In rabbit myometrium, estrogens increase, while progesterone blunts neurohypophysial hormone receptors. However, the action of sex steroids on OT and V1 VP receptors differs in terms of the ED50 and maximal effect. Therefore, at parturition, only OT receptors show a dramatic rise, while V1 VP receptors do not change, suggesting a major role for OT in labor. ET is a potent stimulator of uterine activity acting through specific receptors present on myometrial cells. These receptors as well as the endometrial localization of ET are modulated by sex steroids, indicating that ET might represent a paracrine regulator of uterine activity. In humans, OT but not V1 VP receptors increase as pregnancy progresses, confirming the primary relevance of OT in timing delivery. 相似文献
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53.
Vittoria Nuti Ronchi Lucia Giorgetti Mariagrazia Tonelli Guido Martini 《Plant Cell, Tissue and Organ Culture》1992,30(2):107-114
Cytological analysis of different carrot cell lines in culture has shown various cytogenetic anomalies generating new levels of ploidy and novel chromosome numbers. Polyploidy may be considered a reservoir of variability that can be released in the form of distinct new segregants of different ploidy. Mechanisms alternative to mitosis (reductional grouping, prophase chromosome reduction) operate from a polyploid state (possibly reached by means of endopolyploidy, endomitosis, nuclear fusion, or restitution nuclei) to generate new levels of ploidy and novel chromosome numbers necessary for selection to operate in vitro. The segregational phenomena require chromosome recognition in haploid set complements and abnormal behaviour of mitoses; the resulting chromosome variability suggests that chromosomes are arranged, in the resting nuclei, in an orderly and predictable manner.The knowledge of the molecular events governing these mechanisms, and how to control them, would be of great help for future applications of plant cell culture. 相似文献
54.
Aren van Waarde Guido van den Thillart Fred Dobbe 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1982,147(1):53-59
Summary Changes in the concentrations of ammonia, glutamate, alanine, aspartate, -ketoglutarate, oxaloacetate and succinate were measured in freeze-clamped lateralred muscle, dorsal white muscle and liver, and in rapidly cooled blood of goldfish after 12 h of anoxia. Alanine accumulation, succinate accumulation and aspartate depletion are observed in all tissues examined; in the liver the concentrations of glutamate increase and those of ammonia decrease. The mass-action ratio of the glutamate-pyruvate transaminase-catalyzed reaction stays within one order of magnitude from thermodynamic equilibrium in the direction of alanine formation. The mass-action ratio of the glutamate-oxaloacetate transaminase reaction is far from equilibrium when measured oxaloacetate concentrations are used. When levels of free oxaloacetate are calculated from LDH and MDH equilibrium constants, the mass-action ratio of glutamate-oxaloacetate transamination is close to equilibrium in the direction of aspartate formation. Since neither alanine nor glutamate decreases, and since ammonia gradients suggest a continuous ammonia production in all tissues examined, anaerobic proteolysis is assumed. A possible coupling between amino acid catabolism and ethanol production is discussed.Abbreviations
ALA
alanine
-
ASP
aspartate
-
EDTA
ethylene diamine tetraacetate
-
FP
ox
oxidated flavoprotein
-
FP
red
reduced flavoprotein
-
FUM
fumarate
-
GLU
glutamate
-
GOT
glutamate oxaloacetate transaminase
-
GPT
glutamate pyruvate transaminase
-
IMP
inosine monophosphate
- KG
-ketoglutarate
-
LDH
lactate dehydrogenase
-
MAL
malate
-
MAR
mass action ratio
-
MDH
malate dehydrogenase
-
OAA
oxaloacetate
-
PYR
pyruvate
-
sAMP
adenylosuccinate
-
SDH
succinate dehydrogenase
-
SUCC
succinate 相似文献
55.
Guido Chelazzi Stefano Focardi 《Journal of experimental marine biology and ecology》1982,65(3):263-273
Zonal oscillations of Monodonta turbinata (Born) were monitored with an actographic device which precluded clustering behaviour. Unfed snails maintained their cyclic pattern of behaviour for up to 8 days under a light-dark cycle which simulated the natural one. Under constant conditions of light or dark, however, the snails ceased migration and occupied a zonal position typical of day and night, respectively. Experiments in diffuse light and with light from below the floor of the experimental tank showed that the downward migration of M. turbinata in the daytime depends on positive geotaxis combined with negative phototaxis whilst the upward migration at night depends on a negative geotaxis. This mechanism is similar to that described in other littoral molluscs. There was no evidence of an endogenous control of rhythmic zonal activity. 相似文献
56.
Herman L. De Pooter Patrick J. Dirinck Guido A. Willaert Niceas M. Schamp 《Phytochemistry》1981,20(9):2135-2138
The headspace of whole Golden Delicious apples treated with propionic acid vapour, was analysed by means of GC, after enrichment on Tenax GC, and its c 相似文献
57.
58.
59.
Wafa H. Cabrera Olga M. Ibanez Silvio L. Oliveira Osvaldo A. Sant'Anna Maria Siqueira Denise Mouton Guido Biozzi 《Immunogenetics》1982,16(6):583-592
The effect of the selective breeding of mice for high or low antibody production to complex immunogens is largely nonspecific, since it modifies the responsiveness of high (H) and low (L) lines to many antigens unrelated to the selection antigen. However, the nonspecific effect of the polygenic control operating in these lines is not a general feature. For example, the group of genes in selection IV, carried out for responsiveness to somatic antigen of Salmonella, does not modify the responses to sheep erythrocytes (SE). Despite equivalent responses in H and L mice of selection IV, a large variability was found in individual responses of F2 interline hybrids, which demonstrates the presence of alleles with high or low effect on responses to SE. A selective breeding (Selection IV-A) was therefore initiated from this F2 population for responsiveness to SE. A progressive interline divergence occurred during the first seven generations of selection; the interline separation was due to polygenic regulation (about four independent loci from a preliminary estimate).Equivalent responses to the s antigen of Salmonella are observed in the two lines. This constitutes additional evidence for distinct polygenic regulation of responses to SE and to somatic antigen. Moreover, the pattern of responses to several unrelated antigens (nonspecific effect) also differs between Selections IV and IV-A.Abbreviations H
high responder lines
- L
low responder lines
- s
somatic antigen of Salmonella
- f
flagellar antigen of Salmonella
- R
response to selection
- S
selection differential
- F0
foundation population
- h2
heritability (realized)
- RGG
rabbit gamma globulin
- CE
chicken erythrocyte
- HE
human erythrocyte
- PE
pigeon erythrocyte
- SE
sheep erythrocyte 相似文献
60.