Detail of "3902-71-4"

Reference

Spectrofluorimetric determination of trioxsalen

Spectrofluorimetric determination of trioxsalen. Mohamed, M. E.; Loutfy, M. A. (Coll. Pharm., King Saud Univ., Riyadh, Saudi Arabia). Pharmazie, 39(10), 708-9 (English) 1984. CODEN: PHARAT. ISSN: 0031-7144. DOCUMENT TYPE: Journal CA Section: 64 (Pharmaceutical Analysis) Trioxsalen (I) [3902-71-4] was detd. by fluorometry with excitation at 295 nm and emission at 450 nm. Fluorescence was linearly related to I in the range 0.1-1.5 mg/mL. Recovery overaged 100.3%.

Psoralen-crosslinking of DNA as a probe for the structure of active nucleolar chromatin

Psoralen-crosslinking of DNA as a probe for the structure of active nucleolar chromatin. Sogo, J. M.; Ness, P. J.; Widmer, R. M.; Parish, R. W.; Koller, T. (Inst. Zellbiol., Eidg. Tech. Hochsch. Zurich, Zurich CH-8093, Switz.). J. Mol. Biol., 178(4), 897-919 (English) 1984. CODEN: JMOBAK. ISSN: 0022-2836. DOCUMENT TYPE: Journal CA Section: 3 (Biochemical Genetics) Trimethylpsoralen (I) [3902-71-4] was used to crosslink the extrachromosomal rRNA genes (rDNA) in nucleoli or nuclei of growing Dictyostelium discoideum cells. The DNA was extd. and examd. by spreading, under denaturing conditions, for electron microscopy. Intact 95,000-base rDNA mols. were seen that showed regularly spaced, single-stranded bubbles of ~200-400 bases. The bubbles were interrupted twice by 11,000-base heavily crosslinked stretches that correspond to the known positions of the coding regions. The bubbles on the nontranscribed regions indicate the presence of nucleosomes during crosslinking. The DNA was digested with restriction enzymes and examd. by gel electrophoresis in parallel with DNA not treated with I. Fragments from the noncoding region had the same mobility as untreated DNA, whereas those from the coding region had a markedly lower mobility, though not as low as that of crosslinked pure DNA. This shifting of the bands specific to the coding region, was also seen when whole cells were treated with I. Treatment of nucleoli with 2M NaCl (which is known to dissoc. histones) before addn. of I led to strong crosslinking all along the rDNA which resulted in a decreased electrophoretic mobility of bands from the noncoding region, but no further retardation of those from the coding region. In differentiating Dictyostelium slugs, in which rRNA synthesis is very much reduced, the extent of I-crosslinking in the coding region was reduced, but not completely to the level of that of the nontranscribed spacer. I-crosslinking did not lead to extensive disruption or distortion of the structure of either inactive or active chromatin. Thus, the extent of I-crosslinking in chromatin DNA is diagnostic for the structure of undistorted chromatin. Within the coding regions of these highly active ribosomal genes, nucleosomes are absent. The presence of nucleosomes precludes extensive crosslinking, within the coding region, crosslinking is extensive without apparent disruption of transcription complexes. Treatment of nucleoli with psoralen in the presence of 2M NaCl does not lead to addnl. crosslinking in the coding region of rDNA, in contrast to the nucleosome-contg. inactive chromatin.