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81.
Mating behavior in seaweed flies (Coelopa frigida) 总被引:1,自引:0,他引:1
82.
Lock S 《BMJ (Clinical research ed.)》1990,301(6765):1348
83.
84.
G. M. Morris G. J. M. J. van den Aardweg R. Hamlet E. Whitehouse J. W. Hopewell H. Franke M. Loeffler 《Cell proliferation》1990,23(2):113-123
Abstract. The durations of the cell cycle and its component phases have been determined for the basal layer of the epidermis of the skin from the upper surface of the hind foot of the rat using single pulse [3 H]-thymidine labelling and the percent labelled mitosis (PLM) technique. Rats of three age groups were used, namely 7, 14 and 52 weeks. The duration of DNA synthesis (Ts ) and the G2 plus M phase (Tg2 ± m) were comparable in 7-week and 52-week-old rats ( P > 0–1). The major difference between 7-week and 52-week-old rats was in the duration of the G1 phase (Tg1 ). In 7-week-old rats Tg1 was 15.0 ± 0.8 h and in 52-week-old rats Tg1 was 31.2 ± 3.5 h. A consequence of this variation was that the overall duration of the cell cycle was longer in 52-week-old rats (53.9 ± 5.3 h) than in 7-week-old rats (30.1 ± 1.3 h).
Difficulties were found in fitting a simple curve to the PLM data for 14-week-old rats. This suggests that the proliferative cell population of the epidermis of rats of this age group may be heterogeneous. A satisfactory fit to the data was obtained using a computer model which assumed that the proliferative population of the epidermis of 14-week-old rats was a mixture of cells with cell cycle parameters the same as those of the 7-week and the 52-week-old rats. These two sub-populations of relatively slowly and rapidly proliferating cells were present in the ratio of 2:1. 相似文献
Difficulties were found in fitting a simple curve to the PLM data for 14-week-old rats. This suggests that the proliferative cell population of the epidermis of rats of this age group may be heterogeneous. A satisfactory fit to the data was obtained using a computer model which assumed that the proliferative population of the epidermis of 14-week-old rats was a mixture of cells with cell cycle parameters the same as those of the 7-week and the 52-week-old rats. These two sub-populations of relatively slowly and rapidly proliferating cells were present in the ratio of 2:1. 相似文献
85.
Buckle S 《Bioethics》1988,2(3):226-253
Buckle's article is one of three discussing the potentiality of the human embryo in this issue of Bioethics devoted to the subject of embryo research. (See also Michael Lockwood's "Warnock v. Powell (and Harradine): when does potentiality count?" and Richard M. Hare's "When does potentiality count? A comment on Lockwood.") In his essay, Buckle analyzes some of the distinct ways of arguing about potential, and the different senses of potential on which these arguments rely. He also examines some of the criticisms of the argument from the potential and replies to them, and shows why the argument's protagonists and critics are often at cross-purposes. 相似文献
86.
Evangelia G. Kranias Ramesh C. Gupta Gyorgyi Jakab Hae Won Kim Nancy A. E. Steenaart Stephen T. Rapundalo 《Molecular and cellular biochemistry》1988,82(1-2):37-44
Summary Canine cardiac sarcoplasmic reticulum is phosphorylated by adenosine 3,5-monophosphate (cAMP)-dependent and by calcium · calmodulin-dependent protein kinases on a 27 000 proteolipid, called phospholamban. Both types of phosphorylation are associated with an increase in the initial rates of Ca2+ transport by SR vesicles which reflects an increased turnover of elementary steps of the calcium ATPase reaction sequence. The stimulatory effects of the protein kinases on the calcium pump may be reversed by an endogenous protein phosphatase, which can dephosphorylate both the CAMP-dependent and the calcium · calmodulin-dependent sites on phospholamban. Thus, the calcium pump in cardiac sarcoplasmic reticulum appears to be under reversible regulation mediated by protein kinases and protein phosphatases. 相似文献
87.
Dori R. Germolec Robert R. Maronpot Michael F. Ackermann Stephen J. Vore Kathleen Dittrich Gary J. Rosenthal Michael I. Luster 《Cancer immunology, immunotherapy : CII》1988,27(2):121-127
Summary The relationship between immune function and chemically induced hepatocarcinogenesis was studied employing an in vivo murine model. Neonatal B6C3F1 mice were given a single carcinogenic dose of diethylnitrosamine (DEN) and the time-response kinetics for the early (foci of alteration) and late (adenomas/carcinomas) phases of hepatocellular carcinogenesis were compared to changes in hematopoiesis and immune functions associated with immune surveillance and natural resistance. Increases in hematopoiesis occurred just prior to or concurrent with the appearance of hepatocellular carcinomas, while increased macrophage and natural killer cell cytotoxicity and suppression of cell-mediated immunity occurred following tumor appearance and progressed with increasing tumor burden. Neither immunological nor hematopoietic changes were associated with early phases of hepatocarcinogenesis, as monitored by the appearance of altered hepatocellular foci. Although changes in hematopoiesis may represent an early indicator for hepatocarcinogenesis in the mouse tumor model, the data suggest that altered immune surveillance and natural resistance are not factors in the development of chemically induced hepatocellular tumors, and the changes in immune function are probably secondary to tumor development. 相似文献
88.
Michèle Ramsay Stephen T. Reeders Peter D. Thomson Lawrence S. Milner L. Lazarou Thomas M. Barratt Adrian Yau Ordan J. Lehmann Trefor Jenkins 《Human genetics》1988,79(1):73-75
Summary The autosomal dominant form of polycystic kidney disease (ADPKD) has been linked to the -globin gene locus on 16p. Linkage studies between the autosomal recessive type (ARPKD) and the 3 HVR of the -globin gene cluster showed that the ARPKD and ADPKD are not allelic. 相似文献
89.
Marijo G. Kent Robert N. Shoffner Allan Hunter Keith O. Elliston Wesley Schroder Elizabeth Tolley Stephen S. Wachtel 《Human genetics》1988,79(4):321-328
Summary An inherited genetic disorder causes XY embryos of the horse to develop as mares. On the basis of our study of 38 such mares, we have identified four grades or classes of XY sex reversal according to this scheme: class I, nearly normal female, of which some are fertile; class II, female with gonadal dysgenesis, normal mullerian development; calss III, intersex mare with gonadal dysgenesis, abnormal mullerian development, enlarged clitoris; class IV, virilized intersex characterized by high levels of testosterone. In general, class I and calss II mares were typed H-Y antigen-negative whereas class III and class IV mares were typed H-Y antigen-positive. 相似文献
90.
Stephen P. Arnerić Jong-Inn Woo Mary P. Meeley Donald J. Reis 《Neurochemical research》1988,13(5):423-428
We sought to determine in rat striatum whether the release of neurotransmitter amino acids aspartate (Asp), glutamate (Glu) and gamma-aminobutyric acid (GABA) were affected by local neurons. To do so, unilateral microinjections of ibotenic acid, an excitotoxin that destroys local neurons without affecting fibers of passage, were made into the striatum. Release of endogenous amino acids from lesioned and intact striatal slices were measured by HPLC one week later. The effectiveness and specificity of the lesion were confirmed by measuring the enzyme activity associated with extrinsic dopamine neurons (tyrosine hydroxylase; 111±14%), intrinsic GABA neurons (glutamic acid decarboxylase; 19±7%) and intrinsic acetylcholine neurons (choline acetyltransferase; 37±10%). Destruction of local striatal neurons markedly attenuated the release of GABA (41±12% of control) elicited by depolarization with K+ (35 mM), but did not significantly reduce the K+-evoked release of Asp (80±17%) and Glu (92±8%). However, spontaneous release of Asp and Glu was significantly greater than that observed in unlesioned tissue (159±18% and 209±27%, respectively), while the spontaneous release of GABA was not significantly reduced (75±43%). Although release of the neurotransmitter amino acids Asp, Glu and GABA were affected by the lesion, the release of the non-neurotransmitter amino acid tyrosine was unaffected. These data are consistent with the hypotheses that: 1) the predominant source of releasable stores of endogenous Asp and Glu in the striatum arises from extinsic neurons, and 2) that the spontaneous release of Asp and Glu from axon terminals in the striatum may be regulated, at least in part, by local inhibitory neurons. 相似文献