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951.
952.
R. M. Ridley H. F. Baker L. E. Annett S. B. Dunnett E. M. Torres A. Fine 《Molecular neurobiology》1994,9(1-3):207-223
The transplantation of neuronal tissue into the brains of patients with Parkinson's disease is already being assessed as an experimental treatment for the symptoms of this disease, and the possibility of using similar graft tissue to ameliorate the symptoms of other neurodegenerative diseases is being considered. In this context, a small number of transplant experiments have been carried out in monkeys with lesions of the central dopamine and cholinergic systems. These experiments make it possible to determine the optimum methods of transplantation in an animal whose brain is structurally more closely related to the human than that of the rat and to assess the behavioral consequences of transplantation on symptoms that either resemble very closely the symptoms seen in patients, or are of a complex cognitive nature and are therefore more difficult to measure in the rat. It is intended that these experiments will contribute to the development of better treatments for the neurodegenerative diseases, either by the use of transplantation as a clinical treatment, or by contributing to a better understanding of the mechanisms that normally maintain neuronal function and that fail in these diseases. 相似文献
953.
The mesothelial cells of the mouse omentum provide an in vivo model for the study of the mobilization of labile microvilli on the cell surface. These mesothelial cells are sparsely covered with microvilli and large pits 150--400 nm in diameter, termed vesiculated pits. On the unstimulated cell, the microvilli average 44/100 microns2 and pits, 30/100 microns 2 of surface and they are rapidly induced to increase in number by the intraperitoneal injection of isologous mouse serum. After 2 min, microvilli increase threefold, continue to sevenfold at 30 min, and decrease to fourfold at 90 min. Vesiculated pits increased with similar kinetics. Bovine serum albumin and gamma globulin also stimulate the microvilli and pits to form, but the response is a slow, gradual rise to five- or sixfold the normal value at 90 min. Evidence indicates that multiple factors, possibly including insulin and immunoglobulins, are involved in the effect of serum. The close physical and temporal relationship between microvilli and pits suggests that a correlation exists in their mobilization by the cell and it is hypothesized that microvilli function in the regulation of the cortical microfilament network in effecting this mobilization. 相似文献
954.
Summary Incubation of cells from a wild type strain ofE. coli with 0.3 mg/ml rifampicin for 15 minutes lead to a complete inhibition of RNA synthesis measured as the uracil incorporation into the trichloroacetic acid insoluble fraction. In these rifampicin-treated cells [14C]uracil incorporation tended to decrease during a further incubation at 37°. Addition of cyclic AMP increased the inactivation of the system responsible for [14C]uracil uptake. The cyclic nucleotide effect seems to be specific since ATP or 5AMP did not increase such inactivation.Dedicated to ProfessorLuis F. Leloir on the occasion of his 70th birthday. 相似文献
955.
Reactivated ciliated cortices from the oviduct of the lizard Anolis cristatellus show symplectic metachrony, and resemble reactivated sea urchin sperm flagella in several characteristics, such as pH optimum and Kmf, but differ in other, such as optimal ionic strength. Cilia isolated from the same source give similar results, but show a poorer reactivation. Purified ciliated cortices have adenylate kinase activity and an ATPase activity with a Km value identical with the Kmf, suggesting a tight coupling between ATP hydrolysis and movement in this system. 相似文献
956.
The genetic control of isozymes from Citrus and its near relatives was determined for three gene/enzyme systems: glutamate oxaloacetate transaminase, phosphoglucose isomerase and phosphoglucose mutase. These enzymes are controlled by four genes having 19 codominant alleles, 12 of which occur in Citrus subg Citrus. Formal genetic studies were carried out with F, biotypes and F1 populations of known origin. When biotypes were grouped into traditionally recognized species to examine genetic affinities within and between species, a remarkable pattern of uniformity of genotype combinations was found within a species, and every species had an unique combination. Because many economically important cultivars produce asexual(nucellar) as well as sexual(zygotic) embryos, a central problem of the breeder is to distinguish these when plants are young, long before fruiting. Isozyme markers can be used with varying degrees of efficiency, depending on the genotypes of the particular parents, to distinguish nucellar seedlings from those of zygotic origin. 相似文献
957.
I Gonzales R S Torres M F Gimeno A L Gimeno 《Archives internationales de physiologie et de biochimie》1976,84(2):213-227
The influence of metabolic substrates (glucose, fructose, lactate, pyruvate) on the spontaneous motility of uterine strips isolated from estrus or spayed rats was explored. The effects of substrate omission on tissue glycogen and triglycerides in both hormonal conditions were also studied. The results indicate an important role of glycolysis for rat uterine motility. It would appear also that the better contractile performance of strips from ovariectomized animals might be related to their capacity to metabolize readily triglyceride energy stores. 相似文献
958.
Three polyclonal antibodies raised against Paraurostyla sp. cyst wall polypeptides of molecular weight 110,000 (p110), 66,000 (p66) and 52,000 (p52) have been obtained. The specificity of the antisera was tested by immunoblotting. Anti-p110 antibody detected five bands of 300, 170, 135, 110 and 40 kDa, respectively. Antiserum obtained against p66 recognized only this protein. Anti-p52 antiserum showed reaction for two different bands of 52 and 44 kDa, respectively. The precise localization of these proteins in the cyst wall was assessed by light microscope immunocytochemistry. Anti-p110 antiserum produced a strong positive reaction in both the ectocyst and endocyst. Both anti-p66 and anti-p52 antibodies recognized the ectocyst. 相似文献
959.
The herbicides alachlor, atrazine, maleic hydrazide and paraquat were evaluated for genotoxicity in the Drosophila melanogaster wing spot test. Third-instar larvae trans-heterozygous for two recessive mutations of wing trichomes, multiple wing hairs (mwh) and flare (flr3), were treated by chronic feeding with different concentrations of the four herbicides. Feeding ended with pupation of the surviving larvae. The genotoxic effects were determined from the appearance of clones of cells with mwh, flr3 or mwh-flr3 phenotypes. Exposure to maleic hydrazide resulted in a significant increase in the frequency of the three categories of spots recorded (small single, large single and twin spots) in a dose-related fashion. Exposure to alachlor induced significant increases in both small and total spots at the four concentrations assayed and in the frequency of twin spots at the highest concentration tested (10 mM). Atrazine and paraquat also induced significant increases in both small and total spots at three of the four concentrations tested, without indication of a direct dose-effect relationship. 相似文献
960.
Identification of a domain involved in ATP-gated ionotropic receptor subunit assembly. 总被引:5,自引:0,他引:5
P2X receptors are ATP-gated ion channels found in a variety of tissues and cell types. Seven different subunits (P2X(1)-P2X(7)) have been molecularly cloned and are known to form homomeric, and in some cases heteromeric, channel complexes. However, the molecular determinants leading to the assembly of subunits into P2X receptors are unknown. To address this question we utilized a co-immunoprecipitation assay in which epitope-tagged deletion mutants and chimeric constructs were examined for their ability to co-associate with full-length P2X subunits. Deletion mutants of the P2X(2) receptor subunit were expressed individually and together with P2X(2) or P2X(3) receptor subunits in HEK 293 cells. Deletion of the amino terminus up to the first transmembrane domain (amino acid 28) and beyond (to amino acid 51) did not prevent subunit assembly. Analysis of the carboxyl terminus demonstrated that mutants missing the portion of the protein downstream of the second transmembrane domain could also still co-assemble. However, a mutant terminating 25 amino acids before the second transmembrane domain could not assemble with other subunits or itself, implicating the missing region of the protein in assembly. This finding was supported and extended by data utilizing a chimera strategy that indicated TMD2 is a critical determinant of P2X subunit assembly. 相似文献