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11.
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Quantitative receptor autoradiography was used to examine the binding of [125I]-human CGRP in the dorsal horn of the L4 spinal segment of rats with a chronic constriction injury (CCI) of the sciatic nerve or unilateral dorsal rhizotomies of spinal segments L1–L6. At the times selected for study, we found no change in the amount of CGRP binding in any areas examined following CCI. In contrast, our results showed a temporally related increase in the amount of CGRP binding in areas within laminae I–II and in lateral lamina V of the dorsal horn ipsilateral to the rhizotomies. These results indicate that CGRP binding sites are regulated, most likely, by changes in the release of CGRP. Further, our results suggest that the release of CGRP from primary afferent neurons is unchanged in animals with a CCI. 相似文献
13.
Cloning and expression of a tylosin resistance gene from a tylosin-producing strain of Streptomyces fradiae 总被引:1,自引:0,他引:1
Virginia A. Birmingham Karen L. Cox Jeffrey L. Larson Scott E. Fishman Charles L. Hershberger Eugene T. Seno 《Molecular & general genetics : MGG》1986,204(3):532-539
Summary A gene conferring high-level resistance to tylosin in Streptomyces lividans and Streptomyces griseofuscus was cloned from a tylosin-producing strain of Streptomyces fradiae. The tylosin-resistance (Tylr) gene (tlrA) was isolated on five overlapping DNA fragments which contained a common 2.6 Kb KpnI fragment. The KpnI fragment contained all of the information required for the expression of the Tylr phenotype in S. lividans and S. griseofuscus. Southern hybridization indicated that the sequence conferring tylosin resistance was present on the same 5 kb SalI fragment in genomic DNA from S. fradiae and several tylosin-sensitive (Tyls) mutants. The cloned tlrA gene failed to restore tylosin resistance in two Tyls mutants derived by protoplast formation and regeneration, and it restored partial resistance in a Tyls mutant obtained by N-methyl-N-nitro-N-nitrosoguanidine (MNNG) mutagenesis. The tlrA gene conferred resistance to tylosin, carbomycin, niddamycin, vernamycin-B and, to some degree, lincomycin in S. griseofuscus, but it had no effect on sensitivity to streptomycin or spectinomycin, suggesting that the cloned gene is an MLS (macrolide, lincosamide, streptogramin-B)-resistance gene. Twenty-eight kb of S. fradiae DNA surrounding the tlrA gene was isolated from a genomic library in bacteriophage Charon 4. Introduction of these DNA sequence into S. fradiae mutants blocked at different steps in tylosin biosynthesis failed to restore tylosin production, suggesting that the cloned Tylr gene is not closely linked to tylosin biosynthetic genes. 相似文献
14.
Patricia Bedinger Eugenio L. de Hostos Patricia Leon Virginia Walbot 《Molecular & general genetics : MGG》1986,205(2):206-212
Summary A linear 2.3 kb DNA molecule found in maize mitochondria was cloned into pUC8. A natural deletion of this plasmid, found in cmsT and some N (fertile) types of maize plants, was mapped to one end of the plasmid. A minor sequence homology to S-2, another linear mitochondrial plasmid, was detected, as well as more significant sequence homology with chloroplast and maize nuclear DNA. Hybridization to teosinte mitochondrial DNA (mtDNA) revealed the presence of part of the maize plasmid in the high molecular weight mtDNA of the maize relatives. RNA dot hybridization indicates that the plasmid is transcribed in mitochondria. The termini of the 2.3 kb linear plasmid contain inverted repeated sequences; of the first 17 nucleotides of the termini, 16 are identical to the terminal inverted repeats of the linear S plasmids found in the mitochondria of cmsS maize plants. 相似文献
15.
Virginia K. Walker 《Biochemical genetics》1985,23(5-6):363-378
Minutes have been considered for some time to be mutant at the sites of synthesis of some components of the protein synthetic apparatus. To study the hypothetical relationship between Minutes and suboptimal translation, a group of abundant proteins, the yolk polypeptides, was assayed in outcrossed females bearing M(3)w, M(3)h
y
, or M(1)n mutations. Recently emerged Minute females contained a lower amount of yolk polypeptides, in both ovarian and nonovarian tissues, than their non-Minute sisters. This low level correlated with the lower abundance of cytoplasmic RNA in Minutes compared to control females. By 1 week of age, both M(3)w and their non-Minute sibs contained the same amount of yolk polypeptides and the corresponding mRNA. The double heterozygote, ap
4/+;M(3)w/+, did not differ in yolk polypeptide content from control flies. M(3)w females demonstrated reduced fecundity during the period of low yolk polypeptide content but gradually increased egg deposition as yolk polypeptide levels rose. These results suggest that the low protein levels are due to the slower maturation of M(3)w, and not to less efficient translation machinery.This work was supported by the NSERC (Canada) and a Queen's University ARC grant. 相似文献
16.
P E Gottschall D K Sarkar J Meites 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1986,181(1):78-86
The purpose of this study was to determine whether inhibition of tuberoinfundibular dopaminergic (TIDA) neuron function which occurs during chronic estrogen administration persists after removal of the estrogen. Ovariectomized (OVX) Fischer 344 (F344) rats were implanted for 4 weeks with a Silastic capsule containing estradiol-17 beta (E2) and controls with an empty capsule for 4 weeks. Other rats which received E2 for 4 weeks had the capsule removed and experiments performed 4 weeks later. At the end of 4 weeks of E2 treatment, anterior pituitary (AP) weight was increased sixfold, serum prolactin (PRL) 65-fold, and AP DNA content fivefold over OVX control rats. Four weeks after removal of E2, AP weight, serum PRL, and AP DNA content declined, but remained significantly above OVX control values. At the end of 4 weeks of E2 treatment and after E2 withdrawal, release of [3H]dopamine (DA) from median eminence (ME) tissue superfused in vitro was lower than from ME of OVX control rats although [3H]DA accumulation was not significantly different among the treatment groups. Administration of apomorphine (APO), a dopamine agonist, significantly reduced plasma prolactin levels in OVX control rats, in rats at the end of 4 weeks E2 treatment, and in rats after 4 weeks of E2 withdrawal. Injection of haloperidol (HALO) produced similar increases in plasma PRL/estimated PRL-cell DNA in OVX controls, at the end of E2 treatment or after E2 withdrawal. However, injection of morphine (MOR), a drug which increases the release of PRL by inhibiting hypothalamic dopaminergic activity, resulted in a rise in plasma PRL/estimated PRL-cell DNA in OVX control rats that was significantly greater compared to rats at the end of E2 treatment or after E2 withdrawal. Since rats treated with E2 released less [3H]DA from ME tissue in vitro, and were less responsive to MOR, it can be that animals treated for 4 weeks with E2 show a decreased ability to release DA from TIDA neurons which persists even after termination of E2 treatment. These results suggest that chronic high circulating E2 levels result in a depression of TIDA neuronal activity which is sustained after E2 is removed. 相似文献
17.
Plastids affected by either iojap or chloroplast mutator fail to green, and altered plastids are maternally transmitted to subsequent generations. The ultrastructure of iojap-affected plastids indicates that these plastids contain no ribosomes and are capable of supporting little internal membrane organization in either light or dark-grown plants. Chloroplast mutator-affected plastids of light-grown plants contain some organized internal membrane structures. In dark-grown plants, chloroplast mutator-aftected plastids contain a crystalline prolamellar body, numerous vesicles, and osmiophilic granules. The chloroplast mutator-affecled etioplasts display an abnormal distribution of lamellar membranes; these membranes, rather than radiating in a spokelike pattern from the prolamellar body, are condensed into a portion of the organelle. Light causes disruption of the prolamellar body in chloroplast mutator-affected plastids without promoting the organization of a normal thylakoid membrane system. The effects of iojap and chloroplast mutator are cell autonomous and apparently influence the individual plastid, as evidenced by the persistence of heteroplastidic cells containing normal and affected plastids. 相似文献
18.
EVIDENCE FOR THE OCCURRENCE AND DISTRIBUTION OF INORGANIC POLYPHOSPHATES IN VERTEBRATE TISSUES 总被引:1,自引:0,他引:1
Evidence for the occurrence of polyphosphates having apparent chain-lengths ranging from less than 10 to over 5000 orthophosphate units has been found in adult brain as well as in a number of other mammalian tissues which have been examined. There appears to be three times as much polyphosphate in rat brain as there is in rat liver. Adult rat brain appears to contain at least 15 μg of phosphorus as polyphosphate per g of fresh tissue. In addition, neural polyphosphate is extremely labile to catabolic degradation after death whereas hepatic polyphosphate is relatively more stable. The nature of this inorganic polymer was elucidated through use of the technique of 31P nuclear magnetic resonance spectroscopy. Further structural evidence was obtained by application of the isotopic dilution technique to 32P-labelled neural polyphosphate mixed with an abiotically prepared inorganic polyphosphate. The conditions and rates of hydrolysis of the biological polyphosphate and a non-biological polyphosphate were comparable. 相似文献
19.
20.
W. D. Alexander Virginia Evans A. MacAulay T. F. Gallagher J. Londono 《BMJ (Clinical research ed.)》1969,2(5652):290-291
Differences in the metabolic fate of antithyroid drugs influence the optimal frequency of administration and their therapeutic efficacy. 35S propylthiouracil differed from the 35S imidazoles (carbimazole and methimazole) in the more rapid absorption and excretion and the shorter biological half-life in the plasma of the former. Renal function may have a more important influence on the biological half-life of the drugs than thyroid status. Further work is required to determine the optimal frequency of administration for each compound. 相似文献