Melatonin produced metabolic changes in testis and did not prevent indomethacin-induced testicular lipid peroxidation in adult rat

Melatonin was orally given to rats at the dosage of 0.75 mg/rat/day for 7 days and challenged on the day 7 with a single toxic dose of indomethacin (20 mg/kg, intramuscularly) to test either protection afforded by melatonin against indomethacin-induced oxidative tissue damage or effects of repeated administration of this hormone on some testicular metabolic parameters. The results showed increased lipid peroxidation, as evidenced by the formation of thiobarbituric acid reactive substances, accompanied by non-significantly decreased glutathione content in the testis of rats treated with indomethacin. However, prior administration of melatonin failed to prevent indomethacin-induced testicular lipid peroxidation. No change in the production of lipid peroxidation and glutathione was observed as well after treatment with melatonin alone. Meanwhile, exogenous melatonin inhibited testicular levels of total lipid, total protein, and activity of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase. All treated rats exhibited unchanged activity of both acid phosphatase and lactate dehydrogenase. The results indicated inability of oral administration of melatonin to prevent some of the oxidative damaging effects of indomethacin in the rat testis. In addition, the study provided an evidence that melatonin has an inhibitory action on the testicular metabolism in adult rats and thereby suggests a possible role of this hormone in modulating functions of rat testis.     

Inhibition of some hepatic glycosidases by the diseco nucleoside, 4-amino-3-(D-glucopentitol-1-yl)-5-mercapto-1,2,4-triazole and its 3-methyl analog

The in vivo and in vitro effects of 4-amino-3-(D-glucopentitol-1-yl)-5-mercapto-1,2,4-triazole and its 3-methyl analogue on alpha- and beta-glucosidases, beta-glucuronidase as well as alpha-amylase have been investigated. alpha-Glucosidase is the enzyme that is markedly affected in vivo and in vitro in a dose-dependent manner. The compounds showed a reversible inhibition of a competitive type for alpha-glucosidase. Moreover, they exert a relatively potent inhibition on alpha-glucosidase with a Ki magnitude of 3.6 x 10(-4), 9.5 x 10(-5) M.     

Time-resolved long-lived infrared emission from bacteriorhodopsin during its photocycle

The infrared emission observed below 2000 cm(-1) upon exciting retinal in bacteriorhodopsin (bR) is found to have a rise time in the submicrosecond time regime and to relax with two exponential components on the submillisecond to millisecond time scale. These time scales, together with the assignment of this emission to hot vibrations from the all-trans retinal (in bR) and the 13-cis retinal (in the K intermediate), support the recent assignment of the J-intermediate as an electronically excited species (Atkinson et al., J. Phys. Chem. A. 104:4130-4139, 2000) rather than a vibrationally hot K intermediate. A discussion of these time scales of the observed infrared emission is given in terms of the competition between radiative and nonradiative relaxation processes of the vibrational states involved.     

Analysis of a donor gene region for a variant surface glycoprotein and its expression site in African trypanosomes

African trypanosomes evade the immune response of their mammalian hosts by sequentially expressing genes for different variant surface glycoproteins (VSGs) from telomere-linked VSG expression sites. In the Trypanosoma brucei clone whose genome is being sequenced (GUTat 10.1), we show that the expressed VSG (VSG 10.1) is duplicated from a silent donor VSG located at another telomere-linked site. We have determined two 130 kb sequences representing the VSG 10.1 donor and expression sites. The telomere-linked donor VSG 10.1 resembles metacyclic VSG expression sites, and is preceded by a cluster of 35 or more tandem housekeeping genes, all of which are transcribed away from the telomere. The 45 kb telomere-linked VSG 10.1 expression site contains a promoter followed by seven expression site-associated genes (ESAGs), three pseudo ESAGs, two pseudo VSGs and VSG 10.1. The 80 kb preceding the expression site has few, if any, functional ORFs, but contains 50 bp repeats, INGI retrotransposon-like elements, and novel 4–12 kb repeats found near other telomeres. This analysis provides the first look over a 130 kb range of a telomere-linked donor VSG and its corresponding telomere-linked VSG expression site and forms the basis for studies on antigenic variation in the context of a completely sequenced genome.     

Flight and molecular modeling study on the response of codling moth, Cydia pomonella (Lepidoptera: Tortricidae) to (E,E)-8,10-dodecadien-1-ol and its geometrical isomers

In a previous study we have reported that both (E,Z)-8,10-dodecadienol (E,Z) and (Z,Z)-8,10-dodecadienol (Z,Z) isomers inhibit the attraction of male codling moth, Cydia pomonella L. when added to (E,E)-8,10-dodecadienol (E,E) while the (Z,E)-8,10-dodecadienol (Z,E) isomer induces slight increase in the number of males attracted to the pheromone source. In the present study, we have tested the behavioral activity of the individual geometrical isomers E,Z; Z,E and Z,Z. A few number of codling moth males flew to the Z,E-isomer while the other two isomers (i.e. E,Z and Z,Z) did not elicit any upwind orientation. Analysis of the flight behavior to the E,E- and Z,E-isomer showed significant differences in most of the flight parameters evaluated. Based on the biological observations and molecular modeling, we suggest that the behavioral activity of the Z,E-isomer is due to presence of specific receptors for this isomer on male antennae and not to its structural resemblance to the E,E-isomer. These results underline the importance of the Z,E-isomer in sex attraction of male codling moth.     

Improvement of Aspergillus oryzae NRRL 3484 by mutagenesis and optimization of culture conditions in solid-state fermentation for the hyper-production of extracellular cellulase

Spore suspensions of Aspergillus oryzae NRRL 3484 were subjected to mutagenesis using ultraviolet-irradiation followed by chemical treatments to improve the biosynthesis of cellulase. Ten mutant strains namely UEAC7, UEAR5, UNAC4, UNAC16, UNAR19, UNBC7, UNBR3, UNBR10, UNBR23 and UNBR25 were selected and their extracellular cellulase activities were assayed. Mutant UNAC4 gave the highest cellulase production [2,455 ± 28 U/g-dry substrate (ds) for filter paper-ase (FP-ase)] in a yield 4-fold exceeding that of the wild type strain (578 ± 5.0 U/g-ds for FP-ase). Rice straw (RS) was used as a sole carbon source for the enzyme production at a concentration of 10 % (w/v). Maximum cellulase production was achieved at initial medium pH 5.5, initial moisture content 77 % and an incubation temperature 28 °C on the fifth day of growth. NH₄Cl proved to be the suitable added nitrogen source for maximum enzyme production followed by peptone. These results clearly indicate the cost-effectiveness of solid state fermentation technology in the economic production of extracellular cellulase. The hyper-production of cellulase by mutant strain UNAC4 has potential for industrial processes that convert lignocellulosic material (e.g. RS) into products of commercial value such as glucose and biofuels.     

Microbial l-methioninase: production, molecular characterization, and therapeutic applications

l-Methioninase is ubiquitous in all organisms except in mammals. It mainly catalyzes the, α, γ-elimination of l-methionine to α-ketobutyrate, methanethiol, and ammonia. Unlike normal cells, methionine dependency was reported as a biochemical phenomenon among various types of cancer cells. Thus, l-methioninase is the universal protocol for triggering the majority of tumor cells. This review is an attempt to briefly describe the occurrence of the biochemical and molecular properties of l-methioninase by a comparative manner to the eukaryotic and prokaryotic source for the maximum exploitation in the therapeutic field. The combination of l-methioninase treatment, gene therapy, and chemotherapeutic drugs clearly explores the various therapeutic aspects of this enzyme. Finally, the perspectives for increasing the therapeutic efficacy of this enzyme were described.     

Effect of pH on growth and biochemical responses of <Emphasis Type="Italic">Dunaliella bardawil</Emphasis> and <Emphasis Type="Italic">Chlorella ellipsoidea</Emphasis>

The goal of the present investigation was to study the effect of pH on growth and biochemical responses of Dunaliella bardawil and Chlorella ellipsoidea when exposed to different pH values. The two tested microalgae could grow in a wide range of pH (4–9 for D. bardawil and 4–10 for C. ellipsoidea). The dry weight gain and the biochemical components of D. bardawil were greatly enhanced at pH 7.5. In contrast, dry weight and carbohydrate content of C. ellipsoidea attained their maximum values at the alkaline pH. On the other hand, the protein content of C. ellipsoidea recorded its highest value at pH 4, while the pigment content of the same alga was highest at pH 4, 6, and 7.5 and decreased at alkaline pH. Both pH 6 and pH 9 stimulated the accumulation of β-carotene, vitamin E and vitamin C in D. bardawil, with the highest values of the three compounds recorded at pH 9. In the case of C. ellipsoidea, β-carotene content increased at pH 6 and pH 10 as compared with the control, but the amount of β-carotene was much higher at pH 6 than at pH 10. Vitamin E content was higher in C. ellipsoidea cells at pH 10 than at pH 6. Both pH 6 and pH 10 caused a significant decline in vitamin C content of C. ellipsoidea.     

On modeling two immune effectors two strain antigen interaction

In this paper we consider the fractional order model with two immune effectors interacting with two strain antigen. The systems may explain the recurrence of some diseases e.g. tuberculosis (TB). The stability of equilibrium points are studied. Numerical solutions of this model are given. Using integer order system the system oscillates. Using fractional order system the system converges to a stable internal equilibrium. Ulam-Hyers stability of the system has been studied.     

The antimutagenicity of 2-substituted selenazolidine-4-(R)-carboxylic acids

Selenium can have cancer chemopreventive activity, although the mechanism of action has not been well defined. Selenazolidine-4-(R)-carboxylic acids (SCAs) were devised as prodrugs of L-selenocysteine, to provide selenium in a form and at a concentration commensurate with cancer chemopreventive activity. In the present study, a series of selenazolidines has been evaluated in the Salmonella typhimurium TA98 tester strain and all were found to possess antimutagenic activity. There was little difference between the seven selenazolidines in their effectiveness against either benzo[a]pyrene (B[a]P) or 3,6-bis(dimethylamino)acridine (acridine orange), agents which differ in their requirement for mammalian enzyme bioactivation for mutagenicity. Antimutagenic activity against acridine orange was dependent on selenazolidine concentration, and EC50 values were in the 5-10 microM range. At 25 microM, the concentration tested in common for the two mutagens, the selenazolidines were more effective antimutagens against acridine orange than against B[a]P, with reductions in mutant frequency ranging from 54 to 71% for B[a]P and 79 to 93% for acridine orange. Efficacy against B[a]P was not enhanced when the concentration was increased to 50 microM. The similarity in efficacy among the selenazolidines against B[a]P mutagenicity, contrasted with inter-compound differences in their ability to inhibit S9 CYP1A activity. The CYP1A Ki values ranged from a low of 63 microM (2-[2'-hydroxyphenyl]SCA) to a high of 1.1mM (2-cyclohexylSCA), but all were above the concentration required to inhibit mutagenicity by 50%. Thus, all the SCAs possess antimutagenic activity against both B[a]P and acridine orange, the efficacy varies little between the individual selenazolidines, and for B[a]P, the efficacy is not proportional to the inhibitory effect on the mutagen bioactivating enzyme.