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991.
The appearance of G2-chalone in the cytoplasm of the intermediate cell layer and partly in the periderm of 17-day-old rat embryo epidermis has been demonstrated by the indirect method of Coons using a monospecific antiserum. G2-chalone was absent from the basal cell layer of 17--21-day-old embryos and of the newborn rats. It was found in all the epidermal layers in 2--5-day-old postnatal rats, while in 6--9-day-old animals it was primarily detected in the cytoplasm of spinous and basal cells. Thus the localization of epidermal G2-chalone typical for defined tissue becomes stabilized at the end of epidermis histogenesis. 相似文献
992.
993.
994.
Naturally occurring strains of Salmonella paratyphi B unable to form adhesive (type-1) fimbriae 总被引:1,自引:0,他引:1
D C Old 《Genetical research》1982,40(3):305-313
995.
996.
D. Higuet 《Genetica》1986,69(2):107-110
Under the hypothesis that heterosis may be due to a greater flexibility of heterozygotes, we have measured in a Drosophila melanogaster strain, polymorphic at the sepia locus, female productivity of the homozygotes and heterozygotes for this locus, in constant as well as in fluctuating temperature conditions. It was expected that the heterozygotes, being more flexible, would be better adapted to a fluctuating temperature than to a constant one. At none of the three temperature regimes (18°C; 28°C; 18–28°C) heterosis or rather overdominance was evident. However, fluctuating temperature results reveal a greater performance of all genotypes than constant-temperature ones do. 相似文献
997.
Robert C. Tait Byron E. Froman Debbie L. Laudencia-Chingcuanco Leslie D. Gottlieb 《Plant molecular biology》1988,11(4):381-388
Nuclear genes that appear to encode both cytosolic and plastid isozymes of phosphoglucose isomerase (PGI), an essential glycolytic enzyme, have been isolated from three diploid species of the annual wild flower genus Clarkia (Onagraceae). The genes do not contain introns and are expressed to varying degrees in Escherichia coli when cloned in either Charon 35 phage or pUC plasmid vectors. The PGI proteins synthesized in E. coli form dimers, are catalytically active, and their electrophoretic mobilities are similar to those of appropriate Clarkia PGIs. The nucleotide sequence of a gene encoding a plastid isozyme of C. unguiculata is described. 相似文献
998.
The rogue tomato differs from the normal plant in that it exhibitsa lesser degree of apical dominance. Grafting techniques andmeasurements of the endogenous levels of growth substances inthe two types have been used in order to establish whether thisdifference is due to an altered hormonal balance in the roguetype. The results suggest that root-produced cytokinins play no rolein the control of apical dominance in the tomato plant, andthat lateral bud out-growth is influenced by a balance betweenapically-produced auxin, abscisic acid produced at the sitesof bud development and cytokinins synthesized within the budsthemselves. Lycopersicon esculentum L., tomato, apical dominance, abscisic acid, auxins, cytokinins, growth regulation 相似文献
999.
An assay for phenolphthalein in biological fluids has been developed utilizing methods previously applied to the assay of bromosulphalein and to the deconjugation of steroidal compounds in urine. Intestinal perfusate, serum, and urine samples containing phenolphthalein are deproteinized with acidified acetone, the samples dried, and the phenolphthalein redissolved in ethanol. Color is developed with 0.5 m glycine buffer, pH 12, and the samples read at 550 nm after blanking the spectrophotometer with one of the replicates to which acidic glycine buffer is added. To measure conjugated phenolphthalein in urine, the sample is incubated overnight with β-glucuronidase/arylsulphatase prior to phenolphthalein determination as noted above. This method gives an accurate assay of phenolphthalein to 10?5m concentrations with coefficients of variation between 2 and 8% and with no resulting interference from hemoglobin or bilirubin. 相似文献
1000.
Factor 390 chromophores: phosphodiester between AMP or GMP and methanogen factor 420 总被引:9,自引:0,他引:9
Two chromophores with absorbance maxima at 390 nm (factors 390) have been isolated from oxidized cells of Methanobacterium thermoautotrophicum delta H. The isolation procedure included anion-exchange chromatography of the soluble cofactor pool followed by reverse-phase chromatography. The factor 390 species are novel derivatives of methanogen coenzyme factor 420 in which the 5-deazaflavin 8-hydroxy group is in a phosphodiester linkage to adenosine 5'-phosphate or guanosine 5'-phosphate. The structural assignments were based, in part, on the UV-visible and 1H NMR spectra. In addition, the results from amino acid analysis, phosphate determination, 31P NMR spectroscopy, and fast atom bombardment mass spectrometry were consistent with the proposed structures. Confirmation of the factor 390 structures was made following phosphodiesterase release of the nucleotide monophosphates from factor 420. The nucleotide monophosphates were identified as AMP and GMP by UV-visible spectra and based on elution position by using reverse-phase and anion-exchange high-performance liquid chromatography. The presence of AMP was further demonstrated by using adenylate-5'-phosphate kinase which induced a spectral shift during conversion of the sample to IMP. In addition, the presence of GMP was established by a specific enzymatic assay. 相似文献