Male germ cells regulate transcription of the cathepsin l gene by rat Sertoli cells.

It is well known that male germ cells regulate the steady state levels of numerous transcripts expressed by Sertoli cells. To date, however, there has been no direct test of whether this regulation reflects changes in gene transcription and/or transcript stability. This study used two experimental approaches to test the hypothesis that germ cells regulate transcription of the cathepsin L gene by rat Sertoli cells.

Induction of polynucleotide-protein cross-linkages by ultraviolet irradiation. Peculiarities of the high-intensity laser pulse irradiation.

The efficiency and specificity of RNA-protein cross-linking in the 30S subunit of Escherichia coli ribosomes, induced by low-intensity (10(15) photons cm-2 s-1, 254 nm) and high-intensity [(1.6-6.8) X 10(24) photons cm-2 s-1, 266 nm, pulse duration 10(-8) s] ultraviolet radiation, are studied.

Footprinting of DNA secondary structure by high-intensity (laser) ultraviolet irradiation.

The action of high-intensity ultraviolet pulse laser radiation on a 161 bp fragment of pBR 322 DNA (EcoRI-MspI fragment) was studied. At doses up to 5 X 10(18) photons/cm2 the N-glycosidic bond splitting is negligible. The action of hot piperidine on irradiated DNA leads to chain splitting at the residues, modified via biphotonic processes.

[Products of laser photolysis of thymine and their transformation in chemical hydrolysis of polynucleotides to the bases].

Some main products of laser photolysis and gamma-radiolysis of thymine were shown to undergo subsequent transformations during DNA hydrolysis by formic acid to the bases. The method has been developed for the quantitative determination of the character and the degree of thymine transformations under the effect of laser- and gamma-radiations with a reference to the end-products of the irradiated thymine hydrolysis.

The photochemistry of purine components of nucleic acids. II. Photolysis of deoxyguanosine.

UV-irradiation (lambda = 254 nm) of liquid aqueous solutions of deoxyguanosine in the presence of oxygen at pH less than 7 causes an intensive degradation of nucleoside. The quantum yield estimated from A254 decrease for the reaction mixture was found to be 1.5X10(-4) at doses to 150 E/mole.

Induced formation of covalent bonds between nucleoprotein components. V. UV or bisulfite induced polynucleotide-protein crosslinkage in bacteriophage MS2.

UV (lambda = 254 nm) irradiation of bacteriophage MS2 or its treatment with bisulfite induce covalent crosslinkage of the RNA to the coat protein. epilsonN-(2-oxopyrimidyl-4)-lysine was found in the phage hydrolysates after either type of treatment. An equimolar mixture of 0-methylhydroxylamine and bisulfite causes complete disappearance of the cross-links.

Mechanism of the mutagenic action of hydroxylamine. IX. The UV-induced cleavage of the N-O bond in N4-hydroxy-and N4-methoxycytidine and N6-methoxyadenosine.

The principal UV-induced (lambda = 2546nm) reaction of N4-hydroxy- and N4methoxycytidines and N6-methoxyadenosine in neutral aqueous solutions is cleavage of the exocyclic N-O bond with the respective formation of cytidine and adenosine. Quantum yields are 2.8x10(-3) and 2.

The photochemistry of purine components of nucleic acids. I. The efficiency of photolysis of adenine and guanine derivatives in aqueous solution.

It has been shown that the quantum yield of the photochemical conversion of adenine and the corresponding nucleosides and nucleoside 5'-phosphates in liquid (pH 5.6 and 2.0) and frozen aqueous solutions do not exceed 10(-4).