Tissue-specific expression of the rat glutathione S-transferases

Tissue-specific patterns of rat glutathione S-transferase expression have been demonstrated by in vitro translation of purified poly(A) RNAs and by protein purification. Poly(A) RNAs from six rat tissues including heart, kidney, liver, lung, spleen, and testis were used to program in vitro translation with the rabbit reticulocyte lysate system and [35S]methionine. The glutathione S-transferase subunits synthesized in vitro were purified from the translation products by affinity chromatography on S-hexylglutathione-linked Sepharose 6B columns. The affinity bound fractions were analyzed by Na dodecyl SO4-polyacrylamide gel electrophoresis and fluorography. A subunit of Mr = 22,000 detected in the in vitro translation products of poly(A) RNAs from heart, kidney, lung, spleen, and testis is missing from the translation products of liver poly(A) RNAs. This Mr = 22,000 subunit is present only in the anionic glutathione S-transferase fraction purified from rat heart, kidney, lung, spleen, and testis. Purified anionic glutathione S-transferase from rat liver does not contain this subunit. The relative specific activities toward a dozen different substrates also demonstrate the nonidentity between liver and kidney anionic glutathione S-transferases. In addition, among the glutathione S-transferase subunits expressed in the liver, some of them could not be detected in the other tissues investigated. Our results indicate that tissue-specific expression of rat glutathione S-transferases may occur pretranslationally.     

Hemodynamic significance of metabolic turn-over rate

Method in establishing mammalian hemodynamic similarity criteria via the classical allometric approach was examined. Metabolic rate (MR) per unit body weight (w), termed the metabolic turn-over rate (MTR), was found to be linearly related to mammalian resting heart rate (fh). The external ventricular work (EW) per unit body weight was found to be constant among mammalian species. The ratio of (EW/w)/(MTR/fh) is dimensionless, and is about 1/70. This latter qualifies as a new similarity principle. It states that the external ventricular work intensity during each cardiac cycle is directly proportional to the metabolic turn-over rate.     

A modified method of UDS detection in vitro suitable for screening the DNA-damaging effects of chemicals

The UDS induced in cultured FL cells by exposure to chemicals was measured as hydroxyurea-resistant incorporation of 3H-TdR in the acid-insoluble fraction of the 14C-TdR-prelabelled cells synchronized by the combination of arginine starvation and pretreatment with hydroxyurea. The level of UDS is represented by the ratios of 3H/14C radioactivities which are measures of specific activities of 3H. Two direct-acting alkylating agents, MMS and MNNG, a cross-linking agent, mitomycin C, and 3 procarcinogens, B(a)P, AFB1 and cyclophosphamide elicited UDS in the absence or presence of the liver-metabolizing system. Three chemicals of unknown carcinogenicity were also able to induce UDS in this assay system, i.e., bis-(O,O-diethylphosphinothioyl)-disulphide, 4-chlorophenoxy acetic acid (sodium salt) and caramelized malt sugar. With the exception of 4-chlorophenoxy acetic acid, they were also active in the Ames test.     

Preparation of [B23-D-alanine]des-(B25-B30)-hexapeptide-insulin by a combination of enzymic and non-enzymic synthesis.

Des-(B25-B30)-hexapeptide-insulin with B23-glycine replaced by D-alanine was prepared by a combination of enzymic and non-enzymic syntheses. The purified product was homogeneous in polyacrylamide-gel electrophoresis and could be crystallized. The biological activity in vivo of crystalline [B23-D-Ala]des-(B25-B30)-hexapeptide-insulin was determined as 58% of that of standard pig insulin (27 i.u./mg).     

Electron Microscope Study of Ribonucleic Acid of Myxoviruses

Intact ribonucleic acid (RNA) molecules in an extended form were extracted from purified influenza virus and observed in the electron microscope. For this study, the RNA extraction procedure and the Kleinschmidt protein monolayer technique were modified. The mean lengths of RNA from X7, X7-F1, and WSN strains of influenza virus were found to be 2.69, 2.55, and 2.37 mum, respectively. From these measurements, the corresponding estimated molecular weights would be 2.9, 2.8, and 2.5 x 10(6) daltons. X7 and WSN RNA preparations were exposed to pH 3 to disrupt intact molecules. Histograms of length measurements showed five peaks, which were interpreted to represent the five pieces of RNA reported to exist in the influenza virion. X7 RNA appeared to be more stable than WSN RNA when stored at 4 C. The profiles of histograms of incomplete virus RNA suggest that the high molecular-weight component is missing. In preliminary experiments on Newcastle disease virus RNA, molecules of various lengths were observed.     

Synthesis of a peptide with full somatostatin activity

A peptide has been synthesized according to the structure proposed for somatostatin by the solid phase method. The synthetic product was assayed and found to possess full somatostatin activity as compared with the natural material.