Location and nucleotide sequence of a tobacco chlorophlast DNA segment capable of replication in yeast

Summary A 1.7 Kbp EcoRI fragment of Nicotiana tabacum chloroplast DNA cloned in YIp5, consisting of pBR322 and the yeast ura3 gene, possessed ars (autonomously replicating sequences) activity in Saccharomyces cerevisiae. This fragment was located in the small single copy region proximal to the 23S rRNA gene.Sequences responsible for potential ars activity were narrowed to about 350 base pairs, where clusters of nucleotides similar to a consensus sequence (11 bp) essential for several yeast ars (Broach et al. 1982), to the stem-and-loop structure typical of yeast ars3 (Feldmann et al. 1981), and regions surrounding the replication origin of mitochondrial DNAs of HeLa Cells (Crews et al. 1979) and yeast (de Zamaroczy et al. 1981) can be observed.Abbreviations ctDNA chloroplast DNA - Kbp kilobase pairs     

Evaluation of the severity of hypoxanthine-guanine phosphoribosyltransferase deficiency using viable T cells

Peripheral T cells from 3 Lesch-Nyhan patients, 3 normal subjects, and 3 brothers with hypoxanthine-guanine phosphoribosyltransferase (HGPRT) deficiency but without Lesch-Nyhan syndrome (so-called partial deficiency) have been analyzed. Although these brothers contained HGPRT activities neither in the hemolysates nor in the T cell extracts at levels detectable by the regular radioenzyme assay, the enzyme deficiency had not caused any typical neurological symptoms of the Lesch-Nyhan syndrome. Although the T cells from these brothers were at least 10-fold more resistant to 6-thioguanine than normal T cells, they were more than 30-fold less resistant than the T cells from 3 Lesch-Nyhan patients indicating that there is a clear difference in the severity of the enzyme deficiency between the brothers and the Lesch-Nyhan patients. These data indicate that the long-term T cell culture in the medium containing a purine analog whose toxicity depends on a salvaging enzyme is useful for evaluating the severity of the enzyme deficiency in viable cells.     

Dynamics of the fluorescence properties of pyrene residues appended to oligonucleotide hybridization probes.

The dynamic and static properties of the fluorescence of a pyrene-introduced oligonucleotide 16 mer and its hybrid with a target 32 mer. Their fluorescence quantum yields (< 1%) were much weaker than that of unsubstituted pyrene and their fluorescence lifetime of the major decay components were less than 1 ns. The rapid fluorescence quenching was due to the interaction between the fluorophore and bases in the oligonucleotides. The fluorescence of pyrene was quenched efficiently by TMP and slightly by AMP. The quenching by CMP and GMP were the intermediate case.     

A recessive mutant causing testicular/ovarian teratoma in rats (Tera strain)

A hereditary testicular/ovarian teratoma strain (Tera) of rats was developed from the Csk: Wistar-Imamichi strain. As the teratoma consisted of tridermic tissues such as bone, epithelium and neural tissue, it was diagnosed as triphyllomatous teratoma. The frequency of the teratoma was about 25% in either sex, with no sexual difference. Accordingly, the heredity of the teratoma appeared to be an autosomal single recessive trait (symbol, tera).     

In vitro effects of glycosylated insulin and glucagon in perfused liver of the rat.

Using perfused liver of the rat, the hepatic uptake of glycosylated insulin (GI) and glucagon (GG) and its effects on hepatic glucose output were investigated. Insulin and glucagon were glycosylated in ambient high glucose concentration, and GI80 or GG80 (insulin or glucagon incubated with 0.08% glucose), GI350 or GG350 (incubated with 0.35% glucose), and GI1000 or GG1000 (incubated with 1% glucose) were prepared. The liver was perfused with the medium containing 1000 microU/ml insulin and 200 pg/ml glucagon or 200 microU/ml insulin and 1000 pg/ml glucagon. The fractional uptake of insulin or glucagon by perfused liver was not significantly altered by the glycosylation. In the liver perfused with 1000 microU/ml insulin and 200 pg/ml glucagon, glucose output was not changed by the glycosylation of the hormones, while in the liver perfused with 200 microU/ml insulin and 1000 pg/ml glucagon, GI1000 reduced its biological activity, as reflected by insulin-mediated decrease in glucose output. These results suggest that in the liver insulin incubated with markedly high concentration of glucose reduces its biological activity at a physiological concentration in the presence of high concentration of glucagon.