Papers by Jesus Sebastian
Proceedings of The National Academy of Sciences, 1974
The activities of the nuclear RNA polymerases I and II have been investigated in cells of Sacchar... more The activities of the nuclear RNA polymerases I and II have been investigated in cells of Saccharomyces cerevisiae at GI, S, early G2, and late G2 stages of the cell cycle. The results show that the ratio of the activities of the two enzymes is different at these four stages, indicating that the two RNA polymerases are regulated independently during the cell cycle. The specific activity of the RNA polymerase I remains conrtant but that of RNA polymerase II increases sharply in cells at the beginning' of the G2 phase. These results are compatible with a pattern of continuous synthesis of the RNA polymerase I and step-wise synthesis of the RNA polymerase II during the yeast cell cycle.
Proceedings of The National Academy of Sciences, 1974
In vivo, ribosomal RNA of Saccharomyces cerevisiae is transcribed from the light strand of γ DNA.... more In vivo, ribosomal RNA of Saccharomyces cerevisiae is transcribed from the light strand of γ DNA. In vitro, γ DNA is transcribed with equal efficiency by both of the yeast nuclear RNA polymerases, polymerase I and polymerase II; however the RNA products synthesized by the two enzymes differ from each other both in size and in the relative composition of guanine and cytosine. RNA synthesized by polymerase I hybridizes preferentially to the light strand, while that synthesized by polymerase II hybridizes equally well to either strand. Selective transcription of the light strand of the ribosomal DNA also occurs when high-molecular-weight total nuclear DNA is used as template.
European Journal of Biochemistry, 1973
The activities of the enzymes ornithine transaminase in Saccharomyces cerevisiae andp-galactosida... more The activities of the enzymes ornithine transaminase in Saccharomyces cerevisiae andp-galactosidase in Saccharomyces lactis increase periodically once per cell cycle. This step synthesis of the enzymes is observed under either basal or induced conditions; however, when the cells are growing under non-induced conditions, addition of the inducer a t any stage of the cell cycle results in an enhancement of the enzyme activity for both enzymes. The amount of enzyme activity induced is constant for much of the cell cycle but doubles over a portion of the cycle, probably as a result of replication of the structural gene of these enzymes during the S phase. These results suggest that whereas t.here is periodic expression of structural genes during the cell cycle of yeasts grown in a constant environment,, these genes can, upon induction, be expressed a t any time during the cell cycle.
de los países centrales, a pesar de ser señalados como países endeudados. La explosión de la burb... more de los países centrales, a pesar de ser señalados como países endeudados. La explosión de la burbuja inmobiliaria y financiera ha evidenciado las conexiones entre la expansión financiera y el deterioro socioterritorial. Así pues, se puede afirmar que la geografía no ha muerto, y además que la geografía importa.
Uploads
Papers by Jesus Sebastian