l-Alanine uptake in brush border membrane vesicles from the gill of a marine bivalve

Summary Brush border membrane vesicles were prepared from mussel gills using differential and sucrose density gradient centrifugation. These vesicles contained both the maximal Na⁺-dependent alanine transport activity found in the gradient and the maximal activities of -glutamyl transpeptidase and alkaline phosphatase. Electron micrographs showed closed vesicles of approximately 0.1–0.5 m diameter. Transport experiments using these vesicles demonstrated a transient 18-fold overshoot in intravesicular alanine concentration in the presence of an inwardly directed Na⁺ gradient, but not under Na⁺ equilibrium conditions. A reduced overshoot (10-fold) was seen with an inwardly directed K⁺ gradient. Further studies revealed a broad cation selectivity, with preference for Na⁺, which was characteristic of alanine transport but not glucose transport in these membranes. The apparent amino acid specificity of the uptake pathway(s) was similar to that of intact gills and supported the idea of at least four separate pathways for amino acid transport in mussel gill brush border membranes. The apparent Michaelis constant for alanine uptake was approximately 7m, consistent with values forK _t determined with intact tissue.     

Interaction of androgens and estrogens in the control of reproduction

Castrated male quail were injected with the synthetic oestrogen, diethylstylbestrol (DES) or the synthetic androgen, methyltrienolone (R 1881) or both compounds simultaneously. Both R 1881 and DES activated male sexual behaviour, inhibited LH and FSH secretion and increased hypothalamic aromatase activity. Additive effects between R 1881 and DES were observed for the induction of brain aromatase and for the inhibition of FSH secretion. As a consequence, mechanisms mediated by androgen and estrogen receptors must be involved in the control of these reproductive characteristics.     

Construction of an Unstable Ring-X Chromosome Bearing the Autosomal Dopa Decarboxylase Gene in Drosophila melanogaster and Analysis of Ddc Mosaics

An unstable Ring-X chromosome, Ddc⁺- Ring-X carrying a cloned Dopa decarboxylase (Ddc) encoding segment was constructed. The construction involved a double recombination event between the unstable Ring-X, R(1)w^vC and a Rod-X chromosome which contained a P-element mediated Ddc ⁺ insert. The resulting Ddc⁺-Ring-X chromosome behaves similarly to the parent chromosome with respect to somatic instability. The Ddc⁺-Ring-X chromosome was used to generate Ddc mosaics. Analyses of Ddc mosaics revealed that while there was no absolute requirement for the Ddc ⁺ expression in either the epidermis or the nervous system, very large mutant clones did affect the viability of the mosaic.     

Growth curves,morphology and ultrastructure of ten Paracoccidioides brasiliensis isolates

The yeast phase of ten P. brasiliensis isolates were studied to characterize their growth pattern, morphology and ultrastructure. Growth curves were determined after counts of total and viable fungi units (FU) during 20 days. Three growth patterns were observed: slow, reaching approximately 10–30× 10⁶ FU/tube (Pb 18, Pb 265 and PB 2); intermediate, reaching 60–150×10⁶ FU/tube (IVIC Pb 9, IVIC Pb 267, Pb SN, Pb Vitor and Pb Campo Grande) and fast, reaching 180–370×10⁶ FU/tube (Pb 2052 and Pb 192). The highest percentage of viable cells occurred on the 6th day of culture for Pb 192, Pb Campo Grande, Pb 2052 and IVIC Pb 9; on the 8th day for Pb Vitor, Pb SN, Pb 18 and IVIC Pb 267; on the 10th day for Pb 265 and on the 12th day of culture for Pb 2. Mean generation times varied from approximately 21.2 (Pb 2052) to 102.6 hours (Pb 265). The isolates showed similar morphology, except IVIC Pb 267 which did not present a typical yeast-phase at 35°C and the two fast-growing isolates (Pb 2052 and Pb 192) that presented smaller cell sizes and less tendency to clump. The ultrastructure of the isolates was similar: the cell walls presented a width of 0.1 to 0.2 °; the mitochondria presented few cristae and had equivalent patterns of distribution and morphology; the endoplasmic reticulum was scanty, presenting narrow cisternae; the vacuoles, empty or filled with electrondense material, were numerous and two to five nuclei with pores were constantly observed.     

Opportunistic zygomycotic infections

This is a literature review of 361 opportunistic fungal infections caused by the Zygomycetes. The clinical and laboratory diagnosis, pathogenesis, management, treatment, and outcome of infection are discussed. The Zygomycetes are a group of opportunistic fungi (orders Mucorales and Entomophthorales) which cause severe infections which may be fatal. Early clinical recognition, prompt diagnostic procedures, control of underlying disease and treatment with high doses of amphotericin B and aggressive surgery increases survival in an otherwise lethal infection.     

Performance of nymphal and adult Nezara viridula on selected alternate host plants

Laboratory studies with the southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae), feeding on seeds or fruits of some alternate host plants, demonstrated differences in nymphal survival and development time, and body weight at adult emergence. Lowest mortalities (25%) were observed for nymphs on fruits of dakota mustard [Brassica kaber (DC.)] and siberian motherwort (Leonurus sibiricus L.). On fruits of castor bean (Ricinus communis L.) nymph mortality was ca. 60%, and on mature seeds of L. sibiricus ca. 75%. Total development time from second instar to adult ranged from ca. 26 days on B. kaber to ca. 42 days on R. communis. Fresh body weight at adult emergence was greatest for nymphs on L. sibiricus and lowest on R. communis. Adult survival after 30 days and mean longevity was greater on L. sibiricus than on the remaining foods, being drastically reduced on R. communis. In general, reproductive performance on all foods was similar, except R. communis, on which no female reproduced. Female weight gain of N. viridula was generally greater on L. sibiricus On R. communis, adults lost weight during their first week and showed the lowest weight gain at the end of day 29. Field observations coupled with these laboratory studies suggest that in the Warta area (northern Paraná state, Brazil, 23° 11 S), L. sibiricus and B. kaber are important alternate food plants in the seasonal phenology of N. viridula. R. communis, however, is of poor nutritional quality, serving primarily as a refuge.

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Résumé L'alimentation au laboratoire de N. viridula avec les graines et les fruits de diverses plantes a entraîné différentes mortalités larvaires, différentes vitesses de développement et des différences dans les poids des adultes à l'émergence. Les mortalités les plus faibles (25%) on été observées avec les fruits de Brassica kaber DC. et de Leonurus sibiricus L.Avec les fruits de Ricinus communis L., la mortalité larvaire était de 60%; sur graines mûres de L. sibiricus, elle était de 75%. La durée du développement du second stade à l'adulte a varié de 26 jours sur B. kaber à 42 jours sur R. communis. Le poids frais des adultes à l'émergence était le plus élevé avec L. sibiricus et le plus faible avec de R. communis. La longévité des adultes au-delà de 30 jours était la plus élevée avec L. sibiricus, et était fortement réduite avec R. communis. Dans l'ensemble, la reproduction était de même importance avec les différents aliments, à l'exception de R. communis avec lequel les femelles ne se reproduisaient pas. Le gain de poids des femelles était généralement supérieur avec L. sibiricus; avec R. communis les adultes ont perdu du poids pendant la première semaine et ont présenté le plus faible gain à la fin du 29ème jour.Des observations dans la nature, associées à ces expériences de laboratoire, laissent supposer que dans la zone de Warta (au Nord de l'état de Paraná, 23° 11 S, au Bresil), L. sibiricus et B. kaber sont des plantes hôtes alternatives importantes dans la phénologie saisonnière de N. viridula. Cependant, R. communis, de faible valeur alimentaire, sert avant tout de refuge.

     

Isolation and characterization of phage F9-11 from a lysogenicDeleya halophila strain

Thirty-eight strains ofDeleya halophila species were examined for production of phage after mitomycin C induction. Thirty-two of them were able to inhibit growth of some other strains. Phage F9-11, isolated fromD. halophila strain F9-11, showed an isometric head and a noncontractile tail. The effects of salt concentrations variation on the stability and replication of this phage were established. Its replication was possible at a wide range of marine salt concentrations, from 2.5% to 15% (wt/vol). Stability seems to be influenced by osmolarity of medium rather than by NaCl level. The euryhaline character showed by F9-11 phage is evoked as an important factor for the survival of this phage in its environment.     

Industrial yeast strain improvement: construction of strains having the killer character and capable of utilizing starch

Summary A hybrid of Saccharomyces cerevisiae with the ability to utilize starch and to produce the killer toxin was constructed by the protoplast fusion technique. The hybrid was obtained in two steps. In the first, a wild killer strain was fused with a laboratory strain (S. cerevisiae STA2). A fusion product which carried the killer factor and the ability to grow on starch was selected. In the second step, this hybrid was fused with a baker's yeast.     

Frequency of the ΔF508 deletion and G551D,R553X and G542X mutations in Yugoslav CF patients

Summary A study was undertaken to find the frequency of the F508 deletion and those of the G551D, R553X and G524X mutations among the mainly Slavic population of Serbia, Bosnia, Herzegovina, and Montenegro and compare the frequencies determined with those in other European populations. The F508 mutation was found to account for about 70% of CF genes in central Jugoslavia, where its frequency is significantly higher than elsewhere in Southern European populations.