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Biomedical subjects

J B Bell

Publications and source records attributed to J B Bell.

At least 91 records · Page 5Linked to original sources
PubMed1978

Multiple isoacceptor forms of several transfer ribonucleic acids in a mutant yeast strain.

By use of reverse phase 5 chromatography, a strain of Saccharomyces cerevisiae (XB 109-5B) has been shown to exhibit multiple isoaccepting forms for several of the transfer ribonucleic acids (tRNAs). This is in contrast with a standard wild-type strain where only one acceptor is found for each tRNA studied. Multiple peaks for tRNATyr, tRNAPhe, tRNASer, and tRNAVal have been detected for strain XB 109-5B. However, the observation of multiple isoacceptors cannot be extended to all tRNAs in this strain since tRNAAsp appears as a single form that is the same as in the wild type. The appearance of multiple peaks was found to depend on the growth conditions of the cells. The tRNA profiles of XB 109-5B that was grown rapidly with vigorous aeration differed the most from profiles of comparably grown wild-type yeast, whereas tRNA from this mutant, grown without shaking or supplementary aeration, appeared the same as the wild type. The minor nucleoside composition of the isoacceptors of tRNAPhe was obtained.

Amino Acyl-tRNA Synthetases↗
PubMed1978

Properties of rat adrenal zona reticularis cells: preparation by gravitational sedimentation.

An enriched fraction of zona reticularis cells was obtained by unit gravity sedimentation of decapsulated adrenal glands from female rats. From light microscopic and ultrastructural studies of the whole gland and the isolated cell fractions, the zona reticularis cells of the adrenal gland can be classified mainly on the bases of size, position and mitochondrial morphology. This cell population consists of two types of cell, the 'true' zoma reticularis cells (Type I, modal diameter 9 micrometer), which usually constitute 90% of the isolated reticularis fraction and 80% of the intact reticularis tissue, and cells (Type II, modal diameter 13 micrometer) with fasciculata-like properties (rich in lipid and spherical mitochondria with vesicular cristae). Staining of the cell preparation for 3beta-hydroxysteroid dehydrogenase activity also demonstrates the existence of two types of cell in the zona reticularis. The zona reticularis cell fraction, like the zona fasciculata cell fraction, was capable of producing the subsequent steroids from radioactive pregnenolone: corticosterone, deoxycorticosterone, 18-hydroxydeoxycorticosterone, 11-dehydrocorticosterone, progesterone and androstenedione. However, the pattern of steroid production differed markedly between the zona reticularis and zona fasciculata cells, particularly with respect to the production of deoxycorticosterone and corticosterone (and its correlated steroids, 11-dehydrocorticosterone and 18-hydroxydeoxycorticosterone). When R (the ratio of deoxycorticosterone : corticosterone plus 11-dehydrocorticosterone) for the purest preparation of reticularis cells was compared with R for the corresponding preparation of fasciculata cells, the normalized ratio was found to be 6.4, 16.4 and 20.1 in three experiments. The pattern of production of androstenedione per cell was similar in the reticularis and fasciculata cell fractions. The exact mechanism for the altered pattern of steroid metabolism remains to be elucidated. However, these results establish that the corticosteroids produced by the cells of the zona reticularis may be quantitatively, if not qualitatively, different from those produced by the zona fasciculata cells.

Adrenal Cortex↗
PubMed1977

A mutant of Saccharomyces cerevisiae that exhibits multiple isoacceptors for several of its transfer RNAs.

A strain of Saccharomyces cerevisiae, known to produce multiple isoaccepting forms of several tRNA's which differ from a standard wild type strain, has been studied genetically. The multiple isoaccepting tRNA phenotype behaves as if it is caused by a single recessive mutation. Five tetrads were analyzed and all showed a 2:2 segregation of mutant to wild type profiles for Phe-tRNA Phe. Furthermore, the multiple isoacceptors for the other tRNA's in the mutant strain are probably caused by the same mutation, since Tyr-tRNA Tyr and Val-tRNA Val also exhibit 2:2 segregation for mutant versus wild type tRNA profiles and the segregation pattern is the same as that for Phe-tRNA Phe.

Amino Acid Sequence↗
PubMed1977

Bacteriological investigation of alberta meat-packing plant wastes with emphasis on salmonella isolation.

The waste treatment facilities and final effluents of 11 meat-packing plants in the Province of Alberta were investigated primarily to determine the numbers of indicator bacteria and the presence of Salmonella. This was done to discover the efficiency of the treatment systems presently in operation in reducing bacterial numbers and to establish the need for disinfection and for bacterial standards for these effluents. Data obtained showed that the final effluents were of very poor quality bacteriologically, with numbers of indicator organisms comparable to those found in raw sewage. Primary treatment facilities were ineffective in reducing the numbers of these bacteria. The secondary treatment facility investigated achieved greater than a 99% reduction of indicator bacteria. Salmonella were isolated from the final effluents of 78% of the plants, including the plant using secondary treatment. In total, 21 Salmonella serotypes were isolated. Salmonella isolates were not antibiotic resistant, but certain coliform and fecal coliform isolates demonstrated resistance to chloramphenicol, tetracycline, and ampicillin.

Journal Article↗
PubMed1976

A nonspecific inhibitory effect of tRNA on the activity of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase from Saccharomyces cerevisiae.

The inhibitory effect of tRNA on yeast 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase (EC 4.1.2.15) has been reinvestigated. From earlier studies the inhibition by tRNAPhe appeared to be quite specific. This study shows that tRNAPhe is indeed a potent inhibitor but so is unfractionated tRNA, as well as ribosomal RNA and heparin. Complete digestion to mononucleotides relieves the inhibition. Since the enzyme requires a metal ion (Co2+) we suggest that the RNA and heparin are inhibitory by virtue of their capacity to chelate the Co2+.

3-Deoxy-7-Phosphoheptulonate Synthase↗
PubMed1975

Studies of in vitro steroid metabolism by testis tissue from 'complete' and 'incomplete' forms of testicular feminization.

The in vitro steroid metabolism of testicular tissue from seven cases of testicular feminization was studied. Using radioactive steroid substrates of both C21 and C19 configurations, kinetic studies of these tissues showed that the major pathway of testosterone production was via the delta5 pathway, i.e. pregnenolone leads to 17 alpha-hydroxypregnenolone leads to dehydroepiandrosterone leads to androstenedione and androstenediol leads to testosterone, with the accumulation of dehydroepiandrosterone and androstenediol. This accumulation of dehydroepiandrosterone and androstenediol does not occur in similar incubations of normal human testis tissue. The seven cases of testicular feminization were classified as 'complete' or 'incomplete' forms of the syndrome by reference to clinical data and the histology of the testicular tissue. It was concluded that the biochemical differences between the two forms of the syndrome were the greater production and accumulation of C21 and C19 delta 4 steroids from the C21 and C19 delta 5 steroid precursors indicating the relatively greater activity of the C21-3beta-hydroxysteroid dehydrogenase-isomerase enzyme in the 'incomplete' form.

17-alpha-Hydroxypregnenolone↗
PubMed1974

Comparison of autoclave and ethylene oxide-sterilized membrane filters used in water quality studies.

Autoclave and ethylene oxide-sterilized membrane filters manufactured by Gelman, Millipore, and Sartorius were field tested for their recovery of total coliforms, fecal coliforms, fecal streptococci, and heterotrophs. The data were analyzed by using split-plot analysis of variance and significance tests. Membranes were also tested for pH and toxicity using Escherichia coli. The mean data summaries indicated that Gelman membrane filters generally produced the highest counts during the field studies. Statistical analyses of the March data showed that there were significant differences between membrane filters at 1% level; however, statistical analyses of June data revealed no significant differences except in total coliform recoveries. Toxicity tests at 35 C indicated that Gelman and Millipore autoclaved membrane filters were able to recover 92% of the test organisms. Toxicity tests performed at 44.5 C revealed that no membranes were able to recover more than 40% of the test organisms. Since differences were found in the ability of the three brands of membrane filters to recover bacteria from natural and controlled sources, membrane filters from different manufacturers cannot be readily interchanged. There is a need for a standardized procedure for testing bacterial recovery by membrane filters.

Analysis of Variance↗