A comparative study of the inhibitory effect of ethanol and substrates on the fermentation rate of parent and a respiratory-deficient mutant

The inhibitory effect of alcohol and substrates on the fermentation rate of one strain of Candida pseudotropicalis and of a respiratory-deficient mutant of this strain is investigated. For the parent strain maximum fermentative activity is identical in the presence of glucose or lactose. For a respiratory-deficient mutant, the fermentation rate is always higher than that of the parent strain. The inhibitory effect of alcohol and substrate is always less with the respiratory-deficient mutant than with the parent strain.     

Enzyme polymorphism inPreissia quadrata (Hepaticae, Marchantiaceae)

Preissia quadrata has a high habitat specificity and a reproductive system including frequent sexual reproduction and absence of specialized asexual propagules. Fertilization is aquatic. Colonies collected in Europe, Asia, eastern and western Canada show the species to be polymorphic at the eleven isozyme loci studied. Most often, thalli of the same colony appeared genetically identical. Partitioning of genetic variation was among rather than within colonies, suggesting a clonal structure of the colonies and a species structure consisting of a series of small populations reproductively isolated from each other. Little genetic exchange between colonies growing nearby was present, but the species does not appear to consist of regionally circumscribed genetically cohesive entities. Some European and Canadian colonies had identical electrophoretic patterns. The problem of understanding the phenomena holding liverwort species together, both morphologically and genetically, remains an open question. The genetic structure of the species might be due to its past history. It might have had a continuous distribution in the northern part of the Northern Hemisphere. If so, little subsequent genetic diversification, perhaps linked to its haploid-dominant life cycle, must be supposed.     

Somatic embryogenesis of Prunus subhirtella autumno rosa and regeneration of transgenic plants after Agrobacterium-mediated transformation

Embryogenic lines of Prunus subhirtella autumno rosa were established on a modified MS medium supplemented with 1 mg/l NAA, 0.06 mg/l IBA and 0.04 mg/l BA from petioles of axenically grown shoots of adult origin. To induce normal development of plantlets we compared a range of approaches on solid culture media as well as in suspension cultures including treatments with ABA, GA3, zeatin, darkness, and cold. A series of experiments were conducted to follow the temporal pattern of somatic embryo development.Separation of embryos at different stages of development was carried out by sieving the suspension cultures through nylon nets. While the embryogenic masses were used for further subcultures, well formed embryos were used for germination experiments.Transformed Prunus subhirtella plants were regenerated from somatic embryos by inoculating an embryogenic callus with Agrobacterium strain LBA 4404 containing the ß-glucuronidase (GUS) gene on plasmid pBinGUSint. Several putative transformed embryogenic calli were selected for continued proliferation on kanamycin containing media. Finally transgenic plants were regenerated on shoot multiplication medium containing kanamycin. Embryos and plants were shown to express the GUS gene by histochemical assays and northern blot analysis. With a yield of 110 transgenic lines from a single transformation experiment this approach appears ideal for the study of the influence on level of expression caused by different copy number, site of insertion etc. This will be helpful in establishing parameters according to which the best transgenic line for a chosen purpose should be selected.Abbreviations BA 6-benzylaminopurine - IBA 3-indolebutyric acid - GA₃ gibberellic acid - NAA 1-naphthylacetic acid - ABA abscisic acid - GUS ß-glucuronidase - NPTII neomycin phosphotransferase II - SDS sodium dodecyl sulphate - SSC standard saline citrate - PEM proembryogenic masses Dedicated to Franticek Novak     

Cyclic hexapeptide antagonists of the bradykinin B2 receptor: Receptor binding and solution backbone conformation

Summary Cyclic hexapeptide analogs of bradykinin, based on a folded receptor-bound model of bradykinin, were found to be able to antagonize the action of bradykinin at its B₂ bradykinin receptor. The best of these, cyclo(d-Lys(Arg)-Phe-Ser-d-Tic-Oic- Arg) [compound 17], has affinities at the human and rat B₂ bradykinin receptors of 230 and 8.5 nM, respectively. This potency is significant, since the analogs lack the C-terminal carboxylate group, residues 2–4 and the important interaction of Phe⁵. These constrained analogs may serve as tools for the determination of the receptor-bound conformation of antagonists at the bradykinin receptor and for the design of even smaller and more potent antagonist analogs.Abbreviations Arg(Me) N-methyl-l-arginine - Arg(Me)₂ N,N-dimethyl-l-arginine - Boc t-butoxycarbonyl - Oic (S,S,S)-octahydroindole-2-carboxylic acid - PAM phenylacetamidomethyl - PyBOP benzotriazole-l-yl-oxy-tris-pyrrolidino-phosphonium hexafluorophosphate - Thi -(2-thienyl)-l-alanine - Tic l-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid     

Reproductive Biology of the Monoecious Understory Palm Prestoea schultzeana in Amazonian Ecuador1

Prestoea schultzeana is a monoecious, protandrous palm in the forest understory of Amazonian Ecuador. We studied its leaf production, population density, sexual expression, phenology, pollination, and the specificity of the floral visitors. On average, 1.4 leaves and 0.9 inflorescences are produced per individual per year. The number of staminate flowers per inflorescence is relatively constant compared with the number of pistillate flowers which varies greatly. Flowering occurs in staminate and pistillate phases of approximately 19 and 0–7 days duration, respectively. Flowers open in the morning, and staminate flowers abscise in the afternoon of the same day whereas pistillate flowers last for two days. Flowers are whitish-yellow with a sweet odor and produce nectar. They were visited by Coleoptera (Chrysomelidae, Curculionidae, Nitidulidae, Ptiliidae, Staphylinidae), Hemiptera, Diptera (Drosophilidae, Syrphidae, Ceratopogonidae), Lepidoptera (Nymphalidae), and Hymenoptera (Formicidae, Halictidae). All examined individuals of the syrphid fly Copestylum sp. visiting pistillate flowers carried 100–500 grains of P. schultzeana pollen. Pollen occurred on all body parts, but especially on the legs, and this makes Copestylum sp. the most important pollinator. Most floral visitors were also frequent on the flowers of co-occurring plant species; notably the palm Hyospathe elegans shared most visitor species with P. schultzeana.     

Androgenic effects of the antiprogestagen RMI 12,936

RMI 12,936 (7alpha-methyl-17beta-hydroxy-androst-5-en-one) was tested for androgenic activity in mouse kidney and for antiprogestational activity in guinea-pig uterus. RMI 12,936 stimulated an increase in kidney weight and in the activity of the androgen-responsive renal enzymes, beta-glucuronidase, alcohol dehydrogenase and arginase. RMI 12,936 was bound by the renal androgen receptor with a relative affinity approximately one-third that of testosterone. Although RMI 12,936 did not stimulate glycogen accumulation in guinea-pig endometrium in vivo, it was active in endometrial organ culture. When RMI 12,936 was combined with progesterone, glycogen accumulation in vitro was partly inhibited. RMI 12,936 was bound by the guinea-pig uterine progesterone receptor with a relative affinity of less than 1%. It is concluded that RMI 12,936 is an androgenic steroid with antifertility actions and in-vitro antiglycogenic activity.     

Effect of Prophage W on the Propagation of Bacteriophages T2 and T4

Studies have been undertaken to determine whether the temperate phage ω present in Escherichia coli strain W is responsible for the inability of this strain to act as a host for T2 and T4. E. coli WS, cured of phage ω, was sensitive to T2 and T4. Lysogenation of E. coli C and WS with phage ω resulted in loss of ability to plate T2 and T4. However, E. coli K-12 lysogens still served as hosts for the T -even phage. Two of three WS lysogens studied resembled strain W at the biochemical level. They converted about 30% of infecting T2 deoxyribonucleic acid (DNA) to acid-soluble fragments and limited macromolecular synthesis to a few minutes after infection. The third lysogen did not degrade phage DNA, and nucleic acid and protein synthesis continued for some time, although no phage production occurred. It is concluded that phage ω plays a role in the restriction of virulent phage but that it is not the only factor involved. Since acid solubilization was not observed in all cases of phage ω-mediated restriction of T -even phage, a hypothesis for the restriction has been proposed which is based on an alteration in the cell envelope after lysogenation with phage ω.     

Biochemistry and Genetics of gangliosidoses

Summary The gangliosidoses comprise an-ever increasing number of biochemically and phenotypically variant diseases. In most of them an autosomal recessive inherited deficiency of a lysosomal hydrolase results in the fatal accumulation of glycolipids (predominantly in the nervous tissue) and of oligosaccharides.The structure, substrate specificity, immunological properties of and genetic studies on the relevant glycosidases, ganglioside G_M1 -galactosidase and -hexosaminidase isoenzymes, are reviewed in this paper. Contrary to general expectation, only a poor correlation is observed between the severity of the disease and residual activity of the defective enzyme when measured with synthetic or natural substrates in the presence of detergents. For the understanding of variant diseases and for their pre- and postnatal diagnosis, the necessity of studying the substrate specificity of normal and mutated enzymes under conditions similar to the in vivo situation, e.g., with natural substrates in the presence of appropriate activator proteins, is stressed. The possibility that detergents may have adverse affects on the substrate specificity of the enzymes is discussed for the -hexosaminidases. The significance of activator proteins for the proper interaction of lipid substrates and watersoluble hydrolases is illustrated by the fatal glycolipid storage resulting from an activator protein deficiency in the AB variant of G_M2-gangliosidosis. Recent somatic complementation studies have revealed the existence of a presumably post-translational modification factor necessary for the expression of ganglioside G_M1 -galactosidase activity. This factor is deficient in a group of variants of G_M1-gangliosidosis. Among the possible reasons for the variability of enzyme activity levels in heterozygotes and patients, allelic mutations, formation of hybrid enzymes, and the existence of patients as compound heterozygotes are discussed. All these may result in the production of mutant enzymes with an altered specificity for a variety of natural substrates.Abbreviations Cer ceramide - Gal D-galactose - GalNAc 2-acetamido-2-deoxy-D-galactopyranoside - Glc D-glucose - MUF 4-methylumbelliferone - MUF--Gal 4-methylumbelliferyl--D-galactopyranoside - MUF--GalNAc 4-methylumbelliferyl-2-acetamido-2-deoxy--D-galactopyranoside - MUF--GlcNAc 4-methylumbelliferyl-2-acetamido-2-deoxy--D-glucopyranoside - NeuAc N-acetylneuraminic acid - PNP--Gal p-nitrophenyl--D-galactopyranoside. Variant B of infantile G_M2-gangliosidosis, Tay-Sachs disease; Variant 0 of infantile G_M2-gangliosidosis, Sandhoff disease, Sandhoff-Jatzkewitz disease; Variant 0 of juvenile G_M2-gangliosidosis, juvenile Sandhoff disease; Variant AB, Variant AB of infantile G_M2-gangliosidosis.     

Expression of galactose genes in mammalian cells. I. Galactose enzymes in Chinese hamster ovary cell hybrids

Galactokinase and galactose 1-phosphate uridyl transferase activities have been studied in several Chinese hamster ovary clonal lines following hybridization of two glycine-requiring mutants. Initially, the hybrids have about twice the parental activity of both enzymes. However, with time, there is a further increase beyond this activity, especially for the transferase enzyme, followed by a decline and a leveling off. The final average kinase activity in the hybrids is about 1.2 times the parental kinase, while the final average transferase is about 1.9 times the parental amount. The cultures lose about 10% of their chromosomes during the period under study; however, there is no obvious correlation between gross chromosome loss and enzyme activity. Protein calculated on a per chromosome basis (to correct for chromosome loss) behaves in a manner similar to the enzyme activities. One possible interpretation of the results is that, following hybridization, there is a derepression of some activities followed by repression during which time new levels of cellular parameters become established. This investigation was aided in part by U.S. Public Health Service Grant 1RO1 GM18481-01. Paper no. 476 from the Department of Biophysics and Genetics, University of Colorado, Denver, Colorado.