Possible repetitive DNA markers for Eusorghum and Parasorghum and their potential use in examining phylogenetic hypotheses on the origin of Sorghum species

Genomic structures of two major species in section Eusorghum (Sorghum), Sorghum bicolor and Sorghum halepense, and their phylogenetic relationships with a species in section Parasorghum, Sorghum versicolor, were studied by using cloned repetitive DNA sequences from the three species. Of the five repetitive DNA clones isolated from S. bicolor and S. halepense, four produced qualitatively similar hybridization patterns with detectable variations in copy numbers of some of the restriction fragments on the Southern blots of the two genomic DNAs. One clone was shown to be diagnostic for S. halepense. Molecular analysis at the DNA level indicates that S. bicolor and S. halepense have similar but not identical genomes, consonant with differences in karyotypes, meiotic chromosome behaviors, morphology, and physiology of the species. In addition to five repetitive clones isolated from S. bicolor and S. halepense, eight more sequences were cloned from S. versicolor. Nine clones were found to be specific for either S. bicolor and S. halepense or S. versicolor. The remaining four had a moderate to strong homology with sequences present in all Sorghum species studied. We speculate that the genome in the common ancestor of Sorghum has differentiated to give rise to genomes of at least three major chromosome sizes; large, medium, and small, as seen at present. Amplifications, eliminations, rearrangements, and new syntheses of repetitive sequences may have been involved in genome differentiation of these species. The results also suggest that the S. versicolor genome has strongly diverged from the genomes of the two species in section Eusorghum.     

Reversed-phase chromatographic method for specific determination of glutathione in cultured malignant cells

A chromatographic method for the specific determination of glutathione in malignant cell lines is described. The method is based on the ability of glutathione-S-transferase to specifically and quantitatively conjugate glutathione to 1-chloro-2,4-dinitrobenzene and chromatographic quantitation of the resultant conjugate, dinitrophenyl-S-glutathione, by reversed-phase liquid chromatography. The assay can be performed on 20 000 g supernatants of cell homogenates without acid extraction. 2-Mercaptoethanol, a sulfhydryl compound often used as a thiol-protective agent to preserve enzymatic activities of a number of enzymes, did not interfere with glutathione determination by this method. The dinitrophenyl-S-glutathione isolated from either standard glutathione samples or from cell homogenates was shown to be identical to authentic dinitrophenyl-S-glutathione using mass spectrometry. Recovery of glutathione in standard samples by the current method was identical to that determined using 5,5′-dithiobis(2-nitrobenzoic acid). Exogenous glutathione added to supernatants of cell homogenate in the presence or absence of 2-mercaptoethanol was also completely recovered.     

Preparation of a fluorescent derivative of benzoylecgonine, and preliminary studies of its application to the analysis of urine

A sensitive high-performance liquid chromatographic method using 3-bromomethyl-6,7-dimethoxy-1-methyl-2(1H)-quinoxalinone (Br-DMEQ) as a fluorescent labeling reagent is described for the determination of benzoylecgonine (BE) and ecgonine (EC). The Br-DMEQ derivatives of BE and EC were separated on a C₁₈ column and detected at 455 nm with excitation at 370 nm. The detection limits of the proposed method were 18.7 fmol for BE and 12.5 pmol for EC at a signal-to-noise ratio of 3. Relative standard deviations of five replicate measurements were 1.94% (10 pmol) and 2.98% (50 pmol) for BE and 6.3% (250 pmol) and 5.62% (1.25 pmol) for EC. This method was applied to the determination of BE in human urine. BE was extracted from urine by solvent extraction with chloroform—isopropyl alcohol (9:1, v/v) solution. Levels of 2.5 · 10⁻⁸ M BE in urine (25 pmol/ml) could be determined.     

Nucleotide sequence of the Yersinia pestis gene encoding F1 antigen and the primary structure of the protein. Putative T and B cell epitopes.

The plasmid-located gene caf1 encoding the capsular antigen fraction 1 (F1) of Yersinia pestis was cloned and sequenced. The gene codes for a 170 amino acid peptide with a deduced Mr of 17.6 kDa. The signal peptide sequence was highly homologous to the E. coli consensus signal sequence. The F1 was assumed to have beta-sheet structure for the most part. The region located between amino acids 100 and 150 was suggested to contain putative antigenic determinants and to stimulate T cells.     

Increased nucleophile reactivity of amino acid beta-naphthylamides in alpha-chymotrypsin-catalyzed peptide synthesis

Alpha-chymotrypsin-catalyzed acyl transfer from Boc-L-MetONp, Ac-L-TyrOEt, Bz-L-TyrOMe, Mal-L-PheOMe to the C-protected amino acids (L-AlaNH2, L-LeuNH2, L-ArgOMe and beta-naphthylamides of L-Arg, L-Leu, L-Ala and L-Glu) has been studied. Modification of the carboxylic groups with beta-naphthylamide was shown to increase the reactivity of nucleophiles in these reactions by a factor of more than 100 in comparison with amides and esters of the same amino acids. This effect can be accounted for by the effective formation of the nucleophile-acylenzyme complex due to hydrophobic interactions of the beta-naphthylamide moiety with the corresponding subsite of alpha-chymotrypsin. The reaction kinetics follows the scheme involving hydrolysis of the nucleophile-acylenzyme intermediate. The contribution of this pathway depends on the structures of both the acyl-group donor and the added nucleophile. The competitive inhibition by amino acid beta-naphthylamides is also observed. The results obtained show that modification of the COOH-group of added nucleophiles by beta-naphthylamide strongly affects the reactivity of these compounds in the alpha-chymotrypsin-catalyzed peptide synthesis.     

Electric field increases the phase transition temperature in the bilayer membrane of phosphatidic acid

The effect of the electric field on the phase transition temperature (Tc) of acidic 1,2-dipalmitoyl-sn-glycero-3-phosphate (DPPA) and 1,2-dipalmitoyl-sn-glycero-3-thionphosphate (thion-DPPA) and zwitterion, i.e. 1,2-dipalmitoyl-rac-3-phosphocholine and 1,2-distearoyl-rac-glycero-3-phosphocholine (DPPC and DSPC), lipids has been investigated. The phase transition was detected using the jump-like increase effect in the conductance of the planar bilayer membrane. A voltage increase to 150 mV has been shown to increase the phase transition temperature in a bilayer lipid membrane (BLM) of phosphatidic acids (DPPA and thion-DPPA) by 8-12 degrees C while the transition temperature in the bilayer of zwitterion lipids (DPPC and DSPC) increases insignificantly. The increasing of Tt in BLM of acidic lipids is attributed to the voltage-induced changes in the molecule packing density.     

A comparison of experimental and theoretical melting maps for replicative form of phi X174 DNA

A previously elaborated technique for fixing a chosen partially melted state of DNA with glyoxal was used in a study of the melting process of the replicative form (RF III) of phi X174 DNA. Electron-microscopic maps corresponding to five points of the melting curve of RF III were obtained and compared with the theoretical melting maps obtained in (4) and (6). This comparison clearly shows that only rigorous calculations (4) and not the ones proposed by Azbel (6,7) correctly predict the course of RF III melting.     

Inhibition of lysosomal enzyme liberation by indomethacin in vivo

The volume of the peritoneal exudate induced in the rat by iota carrageenan is reduced by subcutaneous administration of indomethacin while the concentrations of three lysosomial enzymes in the exudate are slightly increased or not modified. Thus, the total enzymatic activities of the exudate are reduced by indomethacin. The leucocyte accumulation remains unchanged in the indomethacin treated rats. During the development of the peritoneal exudate, the circulating plasma displays a high degree of lysosomial enzymes activity which is suppressed by indomethacin at the dose of 4 mg/kg.     

The effect of metals on isolated pea pyruvate decarboxylase

Pyruvate decarboxylase (PDC) was prepared from four-day-old pea seedlings by a procedure which involves extraction of plant material with a phosphate buffer, fractionation of the extract with ammonium sulphate, desalting by dialysis or gel filtration on Sephadex G-25 column, chromatography on DEAE cellulose and filtration on Sepharose 4B. The PDC preparation activity 10 000 U g^-1 protein was about 600 fold higher than that of the sodium phosphate buffer extract. According to the enzyme behaviour during the gel filtration on different carriers the molecular mass of pea PDS was estimated at about 10⁶. Magnesium ions and thiamine pyrophosphate were found to be coenzymes of PDC. Cofactors can be removed by 48 h dialysis followed by chromatography on DEAE cellulose. Apoenzym is activated optimally with the concentration of cofactors of 0.002 M. Magnesium ions can be replaced in their activation function by ions of Fe²⁺, Ni²⁺, Co²⁺, Zn²⁺ and Mn²⁺. Another ions,i.e. Ba²⁺, Ca²⁺, Cd²⁺, Hg²⁺ and Cu²⁺ are inactive. Assumption about the relation between the ion diameter and degree of activation is formulated.