Purine salvage as metabolite and energy saving mechanism in Camelus dromedarius: the recovery of guanine

The preservation of purine ring as purine bases appears to be a common feature of camel liver. Hepatic guanine appears to be actively converted into GMP in the camel rather than further degraded. The limiting step of guanine degradation appears to be the lack of hepatic guanase activity. Higher purine bases over uric acid ratios were found in camel urine with respect to those of zebu.     

The Isolation and Characterization of Glycosylated Phosphoproteins from Herring Fish Bones

Past studies of bone extracellular matrix phosphoproteins such as osteopontin and bone sialoprotein have yielded important biological information regarding their role in calcification and the regulation of cellular activity. Most of these studies have been limited to proteins extracted from mammalian and avian vertebrates and nonvertebrates. The present work describes the isolation and purification of two major highly glycosylated and phosphorylated extracellular matrix proteins of 70 and 22 kDa from herring fish bones. The 70-kDa phosphoprotein has some characteristics of osteopontin with respect to amino acid composition and susceptibility to thrombin cleavage. Unlike osteopontin, however, it was found to contain high levels of sialic acid similar to bone sialoprotein. The 22-kDa protein has very different properties such as very high content of phosphoserine (∼270 Ser(P) residues/1000 amino acid residues), Ala, and Asx residues. The N-terminal amino acid sequence analysis of both the 70-kDa (NPIMA(M)ETTS(M)DSKVNPLL) and the 22-kDa (NQDMAMEASSDPEAA) fish phosphoproteins indicate that these unique amino acid sequences are unlike any published in protein databases. An enzyme-linked immunosorbent assay revealed that the 70-kDa phosphoprotein was present principally in bone and in calcified scales, whereas the 22-kDa phosphoprotein was detected only in bone. Immunohistological analysis revealed diffusely positive immunostaining for both the 70- and 22-kDa phosphoproteins throughout the matrix of the bone. Overall, this work adds additional support to the concept that the mechanism of biological calcification has common evolutionary and fundamental bases throughout vertebrate species.     

Isolation and characterisation of nuv11, a mutation affecting meiotic and mitotic recombination in Aspergillus nidulans

A mutant of Aspergillus nidulans, designated nuv11, has been isolated as hypersensitive to the monofunctional alkylating agent MNNG and the quasi-UV-mimetic mutagen 4-NQO. The mutation was recessive, resulting from mutation of a single gene which mapped to chromosome IV, and was non-allelic to the previously characterised repair-deficient mutations uvsB and uvsH which are also located on this linkage group. The nuv11 mutation results in slow growth, deficient intragenic and intergenic meiotic recombination, increased spontaneous chromosome instability, and increased intragenic and intergenic mitotic recombination in homozygous diploids. By screening a wild-type gene bank of A nidulans, a clone (pNUV11A40) has been isolated which complements the nuv11 mutation, restoring wild-type responses to both MNNG and 4-NQO.     

Glycoalkaloids of Solanum Series Megistacrolobum and related potato cultigens

Glycoalkaloids were used as evidence of the affinities of nine taxa of Solanum Series Megistacrolobum and related potato cultigens from western Bolivia. S. boliviense, S. sanctae-rosae and S. toralapanum contain the commertetraose sugar moiety and appear to represent a relatively wild group within the Series. S. megistacrolobum, S. sogarandinum and S. raphanifolium show anomolous glycoalkaloid profiles that probably reflect hybridization associated with human disturbance. Primitive forms of the S. χ ajanhuiri cultigen are indistinguishable chemicaliy from conspecific weeds that were previously classified as S. megistacrolobum. Variation in total glycoalkaloid content within Series Megistacrolobum likely reflects direct selection by humans for reduced glycoalkaloid levels during the domestication process.     

Effects of aminoglutethimide on ovarian histology in the rat

Aminoglutethimide, a corticosteroid inhibitor, administered at a daily dose of 150 mg per kg body weight, showed a dramatic interference with ovarian histology in the rat. The drug caused thinning of the germinal epithelium and disruption of the layers of the follicular cells. It also resulted in the appearance of cytoplasmic vacuoles and distortion of follicle cell nuclei. In the corpus luteum, it caused shrinkage of the lutein cells, resulting in large spaces between the cords of cells. It also arrested immature follicles at various stages of their development. Our results indicate that aminoglutethimide, by modifying ovarian structure in the rat, interferes with the ovulation process.     

Differences in the chemical and catalytic characteristics of two crystallographically ''identical'' enzyme catalytic sites. Characterization of actinidin and papain by a combination of pH-dependent substrate catalysis kinetics and reactivity probe studies targeted on the catalytic-site thiol group and its immediate microenvironment.

The characteristics of actinidin (EC 3.4.22.14) and papain (EC 3.4.22.2), two cysteine proteinases whose catalytic-site regions appear to superimpose to a degree that approaches atomic co-ordinate accuracy of both crystal structures, were evaluated by determining (a) the pH-dependence in acid media of the acylation process of the catalytic act (k+2/Ks) using N alpha-benzoyl-L-arginine p-nitroanilide (L-Bz-Arg-Nan) as substrate and (b) the sensitivity of the reactivity of the catalytic-site thiol group and its pH-dependence to structural change in small, thiol-specific, two-protonic-state reactivity probes (2,2'-dipyridyl disulphide and methyl 2-pyridyl disulphide) where enzyme-probe contacts should be restricted to areas close to the catalytic site. Distortion of the catalytic sites of the two enzymes at pH less than 4 was evaluated over time-scales appropriate for both stopped-flow reactivity probe kinetics (less than or equal to 1-2 s) and steady-state substrate catalysis kinetics (3-5 min) by using the 2,2'-dipyridyl disulphide monocation as a titrant for non-distorted catalytic sites. This permitted a lower pH limit to be defined for valid kinetic analysis of both types. The behaviour of the enzymes at pH less than 4 requires a kinetic model in which the apparently biomolecular reaction of enzyme with probe reagent is separated from the process leading to loss of conformational integrity by a potentially reversible step. The acylation of actinidin with L-Bz-Arg-Nan in acidic media occurs in two protonic states, one produced by raising the pH across pKa less than 4 which probably characterizes the formation of -S-/-ImH+ ion pair (pKa approx. 3) and the other, of higher reactivity, produced by raising the pH across pKa 5.5, which may characterize rearrangement of catalytic-site geometry. The pH-dependence of the acylation of papain by L-Bz-Arg-Nan is quite different and is not influenced by protonic dissociation with pKa values in the range 5-6. The earlier conclusion that the acylation of papain depends on two protonic dissociations each with pKa approx. 4 was confirmed. This argument is now more firmly based because titration with 2,2'-dipyridyl disulphide permits the loss of conformational integrity to be taken into account in the analysis of the kinetic data at very low pH. Methyl 2-pyridyl disulphide was synthesized by reaction of pyridine-2-thione with methyl methanethiolsulphonate and its pKa at I = 0.1 was determined by spectral analysis at 307 nm to be 2.8.(ABSTRACT TRUNCATED AT 400 WORDS)     

Contributions of algalization to rice growth,yield, N attributes and incidence of infestation with the blast fungusPyricularia oryzae under different fungicidal treatments

Inoculation of the Japonica rice, Giza 171, with blue-green algae along with 36 kg N/ha or complete N fertilization by 108 kg N/ha were tested along with blast-controlling fungicides: Kitazin-17, Fuji-one and Beam. The algal inoculum, which containedAnabaena cylindrica, Anabaena oryzae, Nostoc muscorum and Tolypothrix tenuis, was applled as 100 kg soil-based inoculum (90% moisture)/ha 5 days after transplanting. Plant growth, yield, N content and fertilizer-N-use efficiency were increased and the incidence and severity of leaf and neck intection withPyricularia oryzae were decreased by treatment with the fungicides applied with the algae along with 36 kg N/ha inslead of 108 kg N/ha without algae.

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Résumé On a testé l'inoculation du riz Japonica, Giza 171 avec l'algue bleu-verte, simultanément avec la fertillisation azotée soit à 36 kg N/ha solt complète à 108 kg N/ha et simultanément avec les fongicides Kitazin-17, Fuji-1 et Beam. L'inoculum d'algues, qui contenaltAnabaena cylindrica, Anabaena oryzae, Nostoc muscorum etTolypothrix tenuis, étalt appliqué à raison de 100 kg humides à 90% d'inoculum à base de sol par ha, 5 jours aprés la transplantation. La croissance des plantes, leur rendement, leur contenu azoté ainsi que l'efficience de la fertillisation azotée ont augmenté tandis que l'incidence et la sévérité de l'infection des feullies et du col parPyricularia oryzae ont décru par le traitement aux fongicides appliqué simultanément avec les algues et 36 kg N/ha par rapport au traitement à 108 kg N/ha sans algues.

     

Growth and development of maxipak wheat as affected by soil salinity and moisture levels

The effect of soil salinity and soil moisture on the growth and yield of maxipak wheat (Triticum aestivum L.) was studied in a lath-house experiment in whih, chloride-sulphate salt mixtures were used to artificially salinize a sandy loam soil from Al-Jadyriah Baghdad. Five soil salinity levels of ECe's equal to 1.7 (Control) 4.2, 5.8, 8.1, 9.4 and 11.0dSm^–1 were prepared and used at 3 levels of available soil moisture depletion, namely, 25, 50, and 75% as determined by weight. Both growth (vegetative) and yield components were studied throughout the growing season.Results showed that increasing the soil salinity from 1.7 to 11.0 dSm^–1, and decreasing the available soil water from 75 to 25% resulted in independent and significant decreases in Mazipak wheat growth and yield components at different stages of plant development. Root growth showed more sensitivity to both available soil water and soil salinity level than other components. It has been concluded that at soil salinity levels of more than 8.0 dSm^–1, available soil water became a limiting factor on wheat growth and the maintenance of 75% of available soil water during the growth period is recommended to obtain satisfactory grain yield.     

Alginate Production by Plant-Pathogenic Pseudomonads

Eighteen plant-pathogenic and three non-plant-pathogenic pseudomonads were tested for the ability to produce alginic acid as an exopolysaccharide in vitro. Alginate production was demonstrated for 10 of 13 fluorescent plant-pathogenic pseudomonads tested with glucose or gluconate as the carbon source, but not for all 5 nonfluorescent plant pathogens and all 3 non-plant pathogens tested. With sucrose as the carbon source, some strains produced alginate while others produced both polyfructan (levan) and alginate. Alginates ranged from <1 to 28% guluronic acid, were acetylated, and had number-average molecular weights of 11.3 × 10³ to 47.1 × 10³. Polyfructans and alginates were not elicitors of the soybean phytoalexin glyceollin when applied to wounded cotyledon surfaces and did not induce prolonged water soaking of soybean leaf tissues. All or most pseudomonads in rRNA-DNA homology group I may be capable of synthesizing alginate as an exopolysaccharide.