Spectroscopic properties and continuous-wave deep-red laser operation of Eu-doped LiYF.

Eu-doped LiYF is reexamined as a laser material for the visible spectral region. Polarized absorption and emission cross sections as well as the fluorescence lifetime are determined. Branching ratios and radiative lifetime are calculated within the theory of 4f-4f transition intensities, which takes into account the influence of an excited configuration of the opposite parity 4f5d.

[Expression of the pro-opiomelanocortin gene in rats with inherited arterial hypertension].

Expression of pro-opiomelanocortin (POMC) gene in pituitary of rats from newly developed hypertensive strain (ISIAH strain) was studied by dot hybridization. The pUC8 plasmid containing 900 base pair (bp) segment or the human POMC gene corresponding to the major portion of the 3'-nontranslated mRNA region and 60 bp coding for the signal peptide, was used as a probe for hybridization. It was found that the expression of the POMC in pituitary of the hypertensive JSJAH rats was more than 3-fold gene lower as compared to normotensive Wistar strain.

[Data for the substantiation of the maximum permissible exposure level of armos fiber dust in the air of the work area].

The 'Armos' fibre dusts are characterized by low cytotoxicity, absence of fibrogenicity, display non-toxic properties in single exposures with no skin-irritating and sensibilizing effects. In repeated introduction into the stomach, the trachea, and if inhaled, these dusts displayed weak toxic properties. Dust concentrations at 10 mg/m3 are in proximity to the threshold one.

[Increased content of nucleotide sequences in transcriptionally active DNA and poly(A)+-mRNA of the rat liver and a rise in its translation activity as affected by inducers].

Cortisol and 3'-methyl-4-dimethyl-amino-azobenzene induce an increase in the content of repeated sequences (RS) in transcriptionally active (TA) DNA, while the content of respective RS in potentially active DNA fractions enriched with regulatory regions of the genome decreases. RS content in induced poly A+-mRNA also rises, as determined by the nature of hybridization of respective c DNA with total DNA. The translation of induced poly A+-mRNA rises essentially, with the qualitative distinctions in in vitro synthesized protein product spectrum being absent.

[Detection of DNA sequences sensitive to glucocorticoids in the thymus of AKR mice and their inactivation in thymoma].

A high increase in transcriptionally active DNA fraction (TA DNA) has been detected in the thymus of young AKR mice and in thymoma. Hybridization of TA DNA with [32P] cDNA synthesized on poly A+-mRNA of cortisol-induced animals has shown that TA DNA of young AKR mice contains 40 times as much cortisol-activated repeated sequences (RS) as that of thymoma. The decrease of cortisol-activated (RS) in AKR thymoma TA DNA was found to be the result of their transition into transcriptionally inactive (TI) DNA.

Histone crosslinking patterns indicate dynamic binding of histone H1 in chromatin.

Crosslinking of histone H1 molecules to each other and to the core histones with bifunctional reagents in mouse liver nuclei and chromatin was compared with that under the conditions of random 'contacts' between these molecules. The patterns of crosslinking of the H1 subfractions (H1A, H1B, and H10) to each other in nuclei, chromatin and in solution at different ionic strengths due to random collisions were essentially the same. Moreover, the contacts between the H1 molecules were qualitatively the same in nuclei, chromatin and in solution also at the level of the chymotryptic halves of the H1 molecules.

[Localization of histone H1 in chromatin. Cross-linking of the N- and C-terminal halves of the molecule with bifunctional reagents].

Mutual arrangement of histone H1 molecules was studied in calf thymus nuclei, extended chromatin and chromatin, isolated and kept in 8 M urea. Histone H1 dimers crosslinked with methyl 4-mercaptobutyrimidate were digested with chymotrypsin and crosslinked fragments obtained were analysed by diagonal gel electrophoresis. In all chromatins tested the N- and C-terminal parts of the H1 molecules were crosslinked in all possible combinations, i.

Purified glucocorticoid-receptor complexes from rat liver cytosol preferentially bind in vitro to a homologous DNA fraction whose transcription is activated by cortisol.

The in vitro binding of 2000-fold purified rat liver glucocorticoid-receptor complexes to functionally differing homologous DNA fractions has been studied. The effectiveness of receptor binding to the transcriptionally active DNA, isolated from rat liver 4 h after cortisol administration, increased by 1.6-1.

[Localization of histone H1 in chromatin. Cross-linking of central globular regions of H1 molecules with a bifunctional reagent].

Mutual arrangement of histone H1 molecules and central globular parts of H1 was studied by crosslinking with a reversible bifunctional reagent. The yields of histone H1 dimers and dimers of it's globular fragment in nuclei and isolated chromatin were similar. In the presence of 8 M urea the yield of the H1 dimers was approximately threefold decreased, dimers of globular fragment being practically absent.

Mutual arrangement of histone H1 molecules in extended chromatin. Chymotryptic digestion of cross-linked H1 histone dimers.

Mutual arrangement of histone H1 molecules in chromatin extended in low salt-EDTA buffer and additionally in the presence of urea was studied by means of reversible cross-linking combined with chymotryptic digestion. In the chromatins tested, the chymotryptic halves of H1 were cross-linked in all possible combinations; i.e.

Chemical crosslinking of histone H1o to histone neighbours in nuclei and chromatin.

Crosslinking of histones in mouse liver nuclei and extended chromatin with a bifunctional reagent leads to the formation of H1-H1o heterodimers as well as H1o-H1o homodimers. H1o can be also crosslinked to the core histones. Thus, the location of histone H1o within the basic repeating chromatin structure seems to be analogous to that of H1 histone.

[Cortisol-induced changes in methylation of repeating sequences of transcriptionally active DNA from rat liver].

The m5C content was determined in three functionally different fractions of rat liver DNA isolated by a modified phenol fractionation. The transcriptionally active DNA-I contains up to 12-14% of hybrid RNA not hydrolyzed by RNAase, is enriched with unique sequences and makes up to about 20% of total DNA. In its total nucleotide content (43 mol.