[Differences in expression and functional organization of the rat tyrosine aminotransferase gene in two lines of Morris hepatoma, 8994 and 7777]. / Razlichiia v ékspressii, funktsional'no'i organizatsii gena tirozinaminotransferazy krys v dvukh liniiakh gepatom Morrisa 8994 i 7777.

Expression and structural organization of tyrosine aminotransferase (TAT) gene in Morris hepatoma cell line 7777 with active and glucocorticoid-inducible TAT gene and in hepatoma 8994, where TAT gene does not function were analysed. No differences in the number of receptor macromolecules, translocation and nuclear binding of hormone-receptor complexes in hormone sensitive (7777) and resistant (8994) cell lines were demonstrated. Dexamethasone increases TAT gene transcription in 7777 cell line but not 8994. Restriction analysis of TAT gene does not reveal any differences either in structural or in regulatory regions. Gel retardation assay with cloned TAT fragment (-400 b.p.) from normal hepatocytes showed identical shift of mobility in 7777 and 8994 cell lines. Moreover, 5'-flanking sequence (-890 b.p.) of TAT gene linked to the bacterial CAT gene is transiently expressed in both cell lines. We have shown that HpaII site (-105 b.p.) of TAT gene is methylated in those cells where TAT gene does not function (thymus, spleen, Zajdela ascites hepatoma) and is demethylated in TAT gene expressing hepatoma 7777 and normal rat hepatocytes. In hepatoma 8994 there are no DNAse I hypersensitive regions, typical to functioning TAT gene from hepatoma 7777 and normal hepatocytes.

[Insertion of (dA-dT)n sequences into the regulatory region of the pho5 gene inhibits its expression]. / Vstraivanie (dA-dT)n-blokov v reguliatornuiu oblast' gena pho5 narushaet ego ékspressiiu.

We have studied the effect of some regular sequences namely (dA-dT)n, (dA)n and (dG-dC)n on the Saccharomyces cerevisiae PHO5 gene expression. These sequences were inserted into the ClaI site, located between two phosphate-responsible upstream activating sequences (UAS's). A modified PHO5 gene cloned in vector plasmids was used to transform the pho3, pho5 yeast strain and the level of acid phosphatase expression in various conditions was measured. We show that the insertion of (dA-dT)n blocks, but not (dA)n or (dG-dC)n, leads to the dramatic decrease of PHO5 gene expression in a derepressed state. (dA-dT)n inserts also inhibit the expression of PHO5 gene which was put under the control of heterologous UASgal.

[Expression of human leukocyte interferon A gene in Saccharomyces cerevisiae under the control of regulatory yeast elements PHO5, GAL1 and GAL10]. / Ekspressiia gena leikotsitarnogo interferona A cheloveka v drozhzhakh Saccharomyces cerevisiae pod kontrolem reguliatornykh élementov drozhzhevykh genov PHO5, GAL1 i GAL10.

A chromosomal gene for human leucocyte interferon A is expressed in Saccharomyces cerevisiae yeasts due to interaction of 5'-nontranslating region of the cloned interferon gene with the regulatory elements of yeast genes PHO5, GAL1 and GAL10. Regulated systhesis of interferon was obtained in all cases. The level of interferon genes expression in case using GAL1 and GAL10 genes regulatory elements (5 X 10(5) and 5 X 10(6) u X l-1) correlated with the distances to their promoters. The highest yield of interferon (10(8) u X l-1) was obtained when the PHO5 gene regulatory elements were used.