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21.
A highly active inhibitor of the binding of estrone and estradiol-17β to rat alpha-fetoprotein is demonstrated for the first time in embryo, immature and adult rat sera as well as in fetal and adult human sera. The competitive character and the narrow specificity of this inhibition effect is shown. The major compound responsible for this activity is isolated by successive column Sephadex LH20 and thin layer chromatography : it is characterized as a nonpolar, nonphenolic, dialysable and thermostable substance, unreactive towards anti-estrone and anti-estradiol-17β anti-bodies. The possible biological role of an endogenous non-estrogen ligand of rodent fetoproteins is discussed. 相似文献
22.
L. T. Chang E. L. McGrory R. P. Elander D. J. Hook 《Journal of industrial microbiology & biotechnology》1991,7(3):175-179
Summary Penicillin V (phenoxymethyl penicillin) is produced by industrial strains ofPenicillium chrysogenum in the presence of phenoxyacetic acid (POAc), a side-chain precursor for the penicillin V molecule. The wild-type strain ofP. chrysogenum produces an undesirable penicillin byproduct,para-hydroxypenicillin V (p-OH penicillin V), in addition to penicillin V, viapara-hydroxylation of POAc and subsequent incorporation of thep-OH phenoxyacetic acid into the penicillin molecule. Most of thep-OH penicillin V is produced late in cycle when the POAc concentration in the medium is nearly depleted. The level ofp-OH penicillin V produced by the control strain ranges up to 10–15% of the total penicillins produced. 3-Phenoxypropionic acid andp-bromophenylacetic acid partially inhibit the formation ofp-OH penicillin V with a minimal effect on penicillin V productivity. Mutants deficient in their ability to hydroxylate POAc were found to produce lower levels ofp-OH penicillin V. Multi-step mutation and screening, starting with the wild-type strain, have culminated in isolation of mutants which producep-OH penicillin V as 1% of the total penicillins with no adverse effect on penicillin V productivity. 相似文献
23.
Cloning of the ColE3-CA38 colicin and immunity genes and identification of a plasmid region which enhances colicin production 总被引:8,自引:0,他引:8
The colicin and immunity genes of plasmid ColE3-CA38 have been localized by characterization of bacteria carrying its cloned restriction fragments. They are within a 3.14-kb EcoRI segment, such that the immunity gene contains the KpnI site, and the colicin gene is adjacent to it within a 2.1-kb KpnI-HincII segment. The immunity gene and one end of the colicin gene are in the region of ColE3-CA38 which is not homologous to the closely related plasmid ColE2-P9. A 0.64-kb PvuI-EcoRI segment of the plasmid adjacent to that containing the colicin and immunity genes was found to augment colicin production on solid media, and also affected the morphology of clearing zones produced by the cells when used as indicators in overlays of stabs of colicin E2 or E7 producers. The 0.64-kb segment was required in its native orientation relative to the 3.14-kb EcoRI segment to cause its effects. 相似文献
24.
A rapid fluorogenic method for the demonstration of 5′-nucleotide phosphodiesterase in human serum has been developed. This method uses the substrate 4-methylumbelliferyl 5′-thymidylate impregnated in agarose gels or filter paper strips. Zymograms are developed in less than 30 min at 25°C, and the sensitivity of this method has been compared with that of the indigogenic method. 相似文献
25.
Dr. Dimitar R. Peev 《Plant Systematics and Evolution》1982,140(2-3):235-242
Flavonoid patterns of several provenances ofVeronica triloba, V. sublobata, andV. hederifolia s. str. have been investigated. 7-0-glucuronides of apigenin and luteolin as well as of 6-substituted (6-hydroxyluteolin
and hispidulin) and 3′-methylated (chrysoeriol) derivatives represent characteristic accumulation tendencies in theV. hederifolia group. The three species show slightly different flavonoid profiles.V. hederifolia exhibits a cumulative pattern of all compounds occurring either inV. triloba orV. sublobata, thus supporting the hypothesis of an allopolyploid origin ofV. hederifolia. 相似文献
26.
R. Vunsh D. Aviv E. Galun 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1982,64(1):51-58
Summary Protoplasts were derived from haploid and diploid Nicotiana sylvestris and N. tabacum. Exposure of the protoplasts to mutagenic doses of ultraviolet (U.V.) radiation prior to two selection rounds in the presence of 4 mM (or 5 mM) and 8 mM of valine, respectively, was required to obtain cell lines with persistent valine resistance. Such lines were obtained from haploid and diploid N. sylvestris protoplasts as well as from haploid protoplasts of N. tabacum but not from (1.8 × 107) diploid N. tabacum protoplasts. The ratio between number of verified valine-resistant cell lines and the initial number of U.V. exposed protoplasts enabled the estimation of the following order of mutation frequency: haploid N. sylvestris > haploid N. tabacum > diploid N. sylvestris. Plants which retained the valine resistance and transmitted it to their sexual progeny were derived from the resistant cell lines. 相似文献
27.
Plasma progesterone and LH concentrations around estrus were determined for both PMSG treated (experimental animals) and non-treated (control animals) dairy cows and heifers of the Holstein Friesian and Jersey breeds, and these hormone profiles were related to the embryo quality. Most experimental animals experienced an increase in progesterone concentrations following PMSG treatment and an abrupt decrease to values below 3 nmol/l after PG injection. The mean (+/-SE) intervals from prostaglandin treatment to estrus were 46.9+/-1.8 h and 64.5+/-4.8 h for experimental and control animals, respectively. At the onset of heat the progesterone concentration in experimental animals with optimal embryo quality (group I) was significantly lower (p<0.01) than in experimental animals which yielded unfertilized eggs (group II) (1.2+/-0.1 versus 3.9+/-0.8 nmol/l) and significantly higher than the level in the control group (0.6+/-0.1 nmol/l). Following estrus the progesterone profiles in all 3 groups were studied and the length of the superovulatory cycle was measured to 26.0+/-4.8 days. The preovulatory LH surge occurred sooner after prostaglandin injection in experimental (41 h) than in control animals (65 h). The LH surge in group I occurred within a narrow range and reached a higher average level than group II (24.2+/-2.2 ng/ml and 16.3+/-3.7 ng/ml, respectively). The control group attained an even higher LH surge (31.8+/-8.8 ng/ml) than did the experimental animals. The data presented in this experiment indicate that plasma levels of progesterone and LH in PMSG-PGF(2)alpha treated animals are related to embryo or egg quality. 相似文献
28.
Fred Lembeck Karl Folkers Josef Donnerer 《Biochemical and biophysical research communications》1981,103(4):1318-1321
[D-Pro2,D-Phe7,D-Trp9]-SP and [D-Pro2,D-Trp7,9]-SP havebeen shown to be antagonists of substance P. The hindlimb scratching syndrome of mice, known to be caused by substance P was absent when these peptides were injected into substance P-treated mice. Substance P shortens “tail withdrawal time” from hot water; the two peptides greatly prolonged tail withdrawal time. Antidromic stimulation of the saphenous nerve (rat), known to release substance P and to induce vasodilatation plasma extravasation, was also greatly inhibited by [D-Pro2,D-Phe7,D-Trp9]-SP. These peptides presumably cause anti-nociceptor effects (analgesia) by inhibition of substance P at receptors and favor the concept that substance P is a sensory neurotransmitter of nociceptive messages. 相似文献
29.
G L Hendrickson 《Experimental parasitology》1979,48(2):245-258
Migration of cercariae of the diplostomatid trematode, Ornithodiplostomum ptychocheilus, to the brain of the fathead minnow, Pimephales promelas, takes place via directed, nonrandom movement. Penetration of the fish epidermis is rapid and is essentially complete by 2 hr postinfection. Migration to the central nervous system occurs almost exclusively via the general body musculature and connective tissue, although a few cercariae gain direct access to the nervous system via the eyes. Cercariae enter either the neural canal and spinal cord, or the brain via the spinal or cranial nerves and their associated foramina, although cercariae appear to remain in (on) these peripheral nerves for only a short time. Cercariae associated with cranial nerves continue to the brain. Those becoming associated with spinal nerves travel up the neural canal and (or) spinal cord to the brain. Data suggest that most arrive at the brain via the neural canal and spinal cord. Within the brain, most developing metacercariae (neascus-type) occur in the optic lobes and cerebellum. Whether this is “selective localization” or merely the result of the larger space afforded by these brain regions could not be determined. 相似文献
30.
Veronica lycica
Lehm. is a distinct, diploid member of theVeronica cymbalaria group, endemic in Lycia (S.W. Anatolia). Closely related is the newV. stamatiadae
M. Fischer etW. Greuter which is also diploid and seems to be restricted to the small Greek island Ro close to the South coast of Lycia. The chromosome numbers for both species are reported for the first time (2n = 18).
Untersuchungen über den PolyploidkomplexVeronica cymbalaria agg., II. — Der erste Beitrag dieser Serie:Fischer (1975). 相似文献