Influence of red pepper and capsaicin on body composition and lipogenesis in rats

Inclusion of red pepper or its active principle ‘capsaicin’ in the diet led to a lowering of total lipids, particularly triglycerides in the liver. The total body fat was lowered in animals fed red pepper or capsaicin but not in animals fed paprika powder which had negligible capsaicin content. Hyperlipogensis and hypertriglyceridemia caused by fructose feeding were significantly were decreased in capsaicin-fed animals. Activities of the key lipogenic enzymes were reduced as reflected by decreased lipogenesis.     

Isolation, macromolecular properties, and combining site of a chito-oligosaccharide-specific lectin from the exudate of ridge gourd (Luffa acutangula)

A lectin specific for chito-oligosaccharides from the exudate of ridge gourd (Luffa acutangula) fruits has been purified to homogeneity by affinity chromatography. The lectin has a molecular weight of 48,000, an S(0)20,w of 4.06 S and a Stokes radius of 2.9 nm. Upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a single band corresponding to Mr of 24,000 was observed both in the presence and absence of beta-mercaptoethanol. The subunits in this dimeric lectin are, therefore, held together solely by noncovalent interactions. The lectin is not a glycoprotein, and secondary structure analysis by CD measurements showed 31% alpha-helix. The hemagglutinating activity of L. acutangula agglutinin was not inhibited by any of the monosaccharides tested. Among the disaccharides only di-N-acetylchitobiose was inhibitory. The inhibitory potency of chito-oligosaccharides increased dramatically with their size up to penta-N-acetylchitopentaose. The lectin has two binding sites for saccharides. The affinity of chito-oligosaccharides for L. acutangula lectin, as monitored by titrating the changes in the near UV-CD spectra and intrinsic fluorescence, increased strikingly with the number of GlcNAc units in them. The values of delta G, delta H, and delta S for the binding process showed a pronounced dependence on the size of the chito-oligosaccharides, indicating that the binding of higher oligomers is progressively more favored thermodynamically than di-N-acetylchitobiose. The thermodynamic data are consistent with an extended binding site in this lectin, which accommodates a tetrasaccharide.     

Characterization of poly(ADP-ribosyl)ated domains of rat pachytene chromatin.

Poly(ADP-ribosyl)ation of nuclear proteins was several-fold higher in the pachytene spermatocytes than in the premeiotic germ cells of the rat. Among the histones of the pachytene nucleus, histone subtypes H2A, H1 and H3 were poly(ADP-ribosyl)ated. Based on the immunoaffinity fractionation procedure of Malik, Miwa, Sugimara & Smulson [(1983) Proc. Natl. Acad. Sci. U.S.A. 80, 2554-2558] we have fractionated DNAase-II-solubilized chromatin into poly(ADP-ribosyl)ated chromatin (PAC) and non-poly(ADP-ribosyl)ated chromatin (non-PAC) domains on an anti-[poly(ADP-ribose)] IgG affinity matrix. Approx. 2.5% of the pachytene chromatin represented the PAC domains. A significant amount of [alpha-32P]dATP-labelled pachytene chromatin (labelled in vitro) was bound to the affinity matrix. The DNA of pachytene PAC domains had internal strand breaks, significant length of gaps and ligatable ends, namely 5'-phosphoryl and 3'-hydroxyl termini. On the other hand, the PAC domains from 18 h regenerating liver had very few gaps, if any. The presence of gaps in the pachytene PAC DNA was also evident from thermal denaturation studies. Although many of the polypeptides were common to the PAC domains of both pachytene and regenerating liver, the DNA sequences associated with these domains were quite different. A 20 kDa protein and the testis-specific histone H1t were selectively enriched in the pachytene PAC domains. The pachytene PAC domains also contained approx. 10% of the messenger coding sequences present in the DNAase-II-solubilized chromatin. The pachytene PAC domains, therefore, may represent highly enriched DNA-repair domains of the pachytene nucleus.     

Hormonal sex reversal of wild-spawned tilapia in India

The effectiveness of methyltestosterone (MT) for sex reversal and growth promotion in Oreochromis mossambicus was studied in culture experiments in India. Wild-spawned fry were treated with 30 μg MT g⁻¹ diet for 30 or 60 days at two feeding levels (initially 20% or 10% of body weight daily). The fish were grown on for 66–96 days after the hormone treatment period in fertilized cement ponds without supplementary feeding. Tilapia treated with MT for 60 days attained an average weight of 29.0 g compared to 18.8 g for untreated fish reared under similar conditions. The percentage of males among the untreated tilapia was 58%, MT treatment for 30 days significantly increased this percentage at the higher feeding level (79% male), but not at the lower feeding level (51%). More than 90% of the tilapia in both 60 day MT treatment groups were male; 3% of all the fish reared showed an intersex condition. The experiments demonstrated that the anabolic and sex reversal effects of MT on tilapia are proportional to the duration of treatment and quantity of hormone administered. The possible application of monosex tilapia culture in tropical countries is noted.     

Prediction and comparison of the secondary structure of legume lectins

Secondary structure prediction for the 4 legume lectins: Concanavalin A, soybean agglutinin, favabean lectin and lentil lectin, was done by the method of Chou and Fasman. This prediction shows that these four lectins fall into a structurally distinct class of proteins, containing high amounts of β-sheet and β-turns. There is a notable similarity in the gross structure of these proteins; all four of them contain about 40–50% of β-sheet, 35–45 % β-turn and 0–10% of α-helix. When the secondary structure of corresponding residues in each pair of these lectins was compared, there was a striking similarity in the Concanavalin A-soybean agglutinin and favabean lectin-lentil lectin pairs, and considerably less similarity in the other pairs, suggesting that these legume lectins have probably evolved in a divergent manner from a common ancestor. A comparison of the predicted potential β-turn sites also supports the hypothesis of divergent evolution in this class of lectins.     

Biosynthesis of branched-chain amino acids in yeast: regulation of leucine biosynthesis in prototrophic and leucine auxotrophic strains

The first enzyme in the biosynthesis of leucine in yeast, alpha-isopropylmalate synthetase, is inhibited by l-leucine. In a mutant resistant to the analogue 5',5',5'-trifluoroleucine, the enzyme is markedly resistant to inhibition by l-leucine. Growth ing the presence of exogenous l-leucine results in repression of the second and third enzymes of the pathway. The first enzyme is not repressed unless both l-leucine and l-threonine are supplied in the medium. Comparison of levels of the remaining two enzymes in leucine auxotrophs grown under conditions of leucine excess and leucine limitation reveals deviations from the wild-type derepression pattern in some mutants. In some, repression of the synthetase by leucine alone was observed. In others, the repressibility of the dehydrogenase was lost. It is unlikely that these deviations were due to the same primary mutational event that caused leucine auxotrophy. No mutants were found in which an altered gene was recognized to be clearly responsible for the level of the leucine-forming enzymes.     

Neither delta- nor lambda-tris(phenanthroline)ruthenium(II) binds to DNA by classical intercalation.

Equilibrium binding studies and viscosity experiments are described that characterize the interaction of delta- and lambda-[Ru(o-phen)3]2+ with calf thymus DNA. The mode of binding of these compounds to DNA is a matter of controversy. Both isomers of [Ru(o-phen)3]2+ were found to bind but weakly to DNA, with binding constants of 4.9 (+/- 0.3) x 10(4) M-1 and 2.8 (+/- 0.2) x 10(4) M-1 determined for the delta and lambda isomers, respectively, at 20 degrees C in a solution containing 5 mM Tris-HCl (pH 7.1) and 10 mM NaCl. We determined that the quantity delta log K/delta log [Na+] equals 1.37 and 1.24 for the delta and lambda isomers, respectively. Application of polyelectrolyte theory allows us to use these values to show quantitatively that both the delta and lambda isomers are essentially electrostatically bound to DNA. Viscosity experiments show that binding the lambda isomer does not alter the relative viscosity of DNA to any appreciable extent, while binding of the delta isomer decreases the relative viscosity of DNA. From these viscosity results, we conclude that neither isomer of [Ru(o-phen)3]2+ binds to DNA by classical intercalation.     

Virulence determinants invA and spvC in salmonellae isolated from poultry products, wastewater, and human sources.

The presence of two virulence foci, invA and spvC, in Salmonella isolates obtained from poultry, wastewater, and human sources was determined. All isolates (n = 245) were positive for the invA gene sequence. Differences in degree of invasiveness were apparent with the Madin Darby canine kidney cell line, as only 79 of 159 randomly selected isolates (49.7%) tested were invasive at > 0.1% of the inoculum. 25% were invasive between 0.1 and 1.0% of the inoculum, and 24.5% were invasive at > 1.0% of the inoculum. There was a significant correlation between degree of invasion and source from which the isolate was recovered but no correlation between geographic origin of poultry isolates and degree of invasion. Only 37 of 245 isolates (15.1%) hybridized with the spvC DNA probe. All isolates that were recovered from a commercial egg production environment and chicken eggs and whose sequences exhibited homology with the spvC gene sequence were determined to be either Salmonella enteritidis PT 23 or PT 13. The sequences of few isolates from ceca and none from wastewater or humans demonstrated homology with the spvC gene.