Ethanol-sensitive mutants of Saccharomyces cerevisiae

Saccharomyces cerevisiae mutants unable to grow at ethanol concentrations at which the wild type strain S288C does grow, have been isolated. Some of them show additional phenotypic alterations in colony size, temperature sensitivity and viability in ethanol, which cosegregate with the growth sensitivity in ethanol. 21 selected monogenic ethanol-sensitive mutants define 20 complementation groups, denominated ETA1 to ETA20, which indicates that there is a high number of genes involved in the ethanol tolerance/sensitivity mechanism.Out of 21 selected monogenic mutants, 20 are not altered in the glycolytic pathway since, when maintained in glucosesupplemented medium, they can produce as much ethanol as the wild type and at about the same velocity. Nor do any of the mutants seem to be altered in the lipid biosynthetic pathway since, whether grown in the absence or in the presence of ethanol, their concentration of fatty acids and ergosterol is similar to that of the wild type under the same conditions. Therefore growth sensitivity to ethanol does not seem necessarily to be related to carbohydrate or lipid metabolism.Non-common abbreviations YP yeast extract peptone medium - YPD yeast extract peptone dextrose agar or medium - YPG yeast extract peptone glycerol agar - YPDE yeast extract peptone dextrose ethanol agar or medium - SD yeast nitrogen base dextrose agar - SPO yeast extract potassium acetate glucose agar - PD parental ditype - NPD non-parental ditype - TT tetratype     

Comparison of protein and lipid composition of the human platelet α-granule membranes and glycerol lysis membranes

Platelet glycerol lysis membranes and α-granule membranes were compared with respect to protein and lipid composition. Crossed immunoelectrophoresis using antibodies against whole platelets, and sodium dodecyl sulphate polyacrylamide gel electrophoresis, revealed the presence of the glycoproteins IIb and IIIa, myosin and an antigen termed G4 in both membrane fractions. The glycoproteins Ia, Ib and IIIb, in addition to β₂-microglobulin and actin, appeared specific for the glycerol lysis membranes, whereas two antigens, termed G8 and G18, were observed only in the α-granule membranes. The localization of glycoprotein IIa was inconclusive. Comparison with the surface-located proteins revealed that the glycerol lysis membranes represented a reasonable approximation to a plasma membrane preparation. Radioactively labelled immunoprecipitates obtained after crossed immunoelectrophoresis of ¹²⁵I-labelled platelets were cut out and applied to sodium dodecyl sulphate electrophoresis on polyacrylamide slab gels. Autoradiography of the dried gels revealed that antigen G4 represented a protein with an average molecular weight of 146 000 in its unreduced state and 132 000 in its reduced state. Antigen G18 represented a protein of molecular weight 130 000–135 000 in the reduced as well as unreduced state. Quantitation of protein and lipids showed that the α-granule membranes contained about one-third as much cholesterol and 2-times as much protein in relation to phospholipids as compared to the glycerol lysis membranes. No significant difference between the two membrane preparations was found as regards the composition of their phospholipids.     

Some characteristics of monolayers of 1-palmitoyl-2-oleoyl-phosphatidylglycerol with and without dipalmitoylphosphatidylcholine during dynamic compression and expansion

Some properties of monolayers of $\text{1-}\text{palmitoyl}\text{-2-}\text{oleoyl}\text{-sn-}\text{glycero}\text{-3-}\text{phospho}\text{-rac-}\text{glycerol}$ (POPG) alone or of POPG in mixtures with $\text{1,2-}\text{dipalmitoyl}\text{-sn-}\text{glycero}\text{-3-}\text{phosphocholine}$ (DPPC) have been measured near 35°C during dynamic compression and expansion at 3.6 cm²·s^?1. (2) The mean values of minimum surface tension (corresponding to maximum surface pressure) which could be obtained with pure POPG monolayers at high compression ranged from 15 to 18 mN·m^?1 in the presence of Na⁺, Ca²⁺ or low pH (2.0) in the subphase. (3) The presence of Ca²⁺ or low pH in the subphase increased the collapse plateau ratios obtained on cyclic compression. This might represent enhanced respreading into the monolayer of pure POPG from a collapsed form during reexpansion of the surface. (4) Monolayers containing 10% or 30% POPG and 90% or 70% DPPC could be compressed to surface tensions approaching zero. (5) In such mixed monolayers, 10% or 30% POPG did not appear to enhance respreading, as measured by collapse plateau ratios, in the presence of Na⁺ or Ca²⁺ in the subphase.     

Accumulation of phosphatidic acid in microsomes from propranolol-treated retinas during short-term incubations

Abstract: The pool size and synthesis of phosphatidic acid derived from [2-³H]glycerol were studied in bovine whole retinas and subcellular fractions. Microsomal preparations from retinas incubated with [2-³H]glycerol displayed the highest percentage labeling of phosphatidic acid at 5 min of incubation; labeling decreased rapidly thereafter. In drug-treated retinas,0.5 m M propranolol increased the endogenous content of phosphatidic acid and stimulated [2-³H]glycerol labeling in whole retina and microsomal and postmicrosomal supernatant fractions. This effect was observed during short-term incubations and was reversible. In pulse-chase experiments, 60 min of reincubation greatly reduced the labeling effect, although propranolol still enhanced phosphatidic acid labeling. At the same time, endogenous phosphatidic acid accumulated and reincubation without propranolol reversed the effect. During accumulation, the amount of palmitate increased and that of oleate decreased, whereas the relatively high level of docosahexaenoate in phosphatidic acid remained unchanged. It was concluded that this propranolol-induced effect is due to cationic amphiphilic drug activity in the endoplasmic reticulum that results in a partial inhibition of phosphatidic acid degradation and a stimulation of its de novo synthesis. Hence, net synthesis of phosphatidic acid can be assessed in the retina during short-term incubation with propranolol.     

Some variations in the composition of suberin from the cork layers of higher plants

The monomeric composition of the suberins from 16 species of higher plants was determined by chromatographic methods following depolymerization of the isolated extractive-free cork layers with sodium methoxide-methanol. 1-Alkanols (mainly C₁₈C₂₈), alkanoic (mainly C₁₆C₃₀), α,ω-alkanedioic (mainly C₁₆C24), ω-hydroxyalkanoic (mainly C₁₆C₂₁), dihydroxyhexadecanoic (mainly 10,16-dihydroxy- and 16-dihydroxyhexadecanoic), monohydroxyepoxyalkanoic (9,10-epoxy-18-hydroxyoctadecanoic), trihydroxyalkanoic (9,10, 18-trihydroxyoctadecanoic), epoxyalkanedioic (9,10-epoxyoctadecane-1,18-dioic) and dihydroxyalkanedioic (9,10-dihydroxyoctadecane-1 18-dioic) acids were detected in all species. The suberins differed from one another mainly in the relative proportions of these monomer classes and in the homologue content of their 1-alkanol, alkanoic, α,ω-alkanedioic and ω-hydroxyalkanoic acid fractions. C₁₈ epoxy and vic-diol monomers were major components (32–59%) of half of the suberins examined (Quercus robur, Q. ilex, Q. suber, Fagus sylvatica, Castanea sativa, Betula pendula, Acer griseum, Fraxinus excelsior) where as ω-hydroxyalkanoic and α,ω-alkanedioic acids predominated in those that contained smaller quantities of such polar C₁₈ monomers (Acer pseudoplatanus, Ribes nigrum, Euonymus alatus, Populus tremula, Solanum tuberosum, Sambucus nigra, Laburnum anagyroides, Cupressus leylandii). All species, however, contained substantial amounts (14–55 %) of ω-hydroxyalkanoic acids, the most common homologues being 18:1 (9) and 22: 0. The dominant α,ω-alkanedioic acid homologues were 16: 0 and 18: 1 (9) whereas 22: 0, 24: 0 and 26: 0, and 20: 0, 22: 0 and 24: 0 were usually the principal homologues in the 1-alkanol and alkanoic acid fractions, respectively. The most diagnostic feature of the suberins examined was the presence of monomers greater than C₁₈ in chain length; most of the C₁₆ and C₁₈ monomers identified in the suberins also occur in plant cutins emphasizing the close chemical similarity between the two anatomical groups of lipid biopolymer.     

Purification and characterization of maize ribulose-1,5-bisphosphate carboxylase

The ribulose-1,5-bisphosphate carboxylase/oxygenase purified from maize (a C₄ monocot) to homogeneity has a MW of532 000 and sedimentation coeffici     

Nutrition et élevage du prédateur polyphageMacrolophus caliginosus [Heteroptera,Miridae] sur milieux artificiels

La possibilité de nourrir la punaiseMacrolophus caliginosus Wagner à l'aide de milieux artificiels a été testée. En l'absence de végétal, les témoins nourris avec des ?ufs d'Ephestia kuehniella Zeller ont une survie médiocre et fournisent 33% d'adultes. Avec le meilleur milieu artificiel la survie est comparable à celle des témoins et 21 % d'adultes sont obtenus. Avec ce même milieu, mais en présence de feuille de géranium, la production d'adultes atteint 62%. Les compositions en acides aminés des punaises élevées avec le milieu montrent des écarts inférieurs à 20% par rapport aux témoins. Le développement complet deM. caliginosus nourri à l'aide de milieu artificiel a été obtenu. Le végétal joue un rôle important dans la biologie de ce prédateur.     

Fatty Acid Composition of the Peribacteroid Membrane and the ER in Nodules of Glycine max Varies after Infection by Different Strains of the Microsymbiont Bradyrhizobiumjaponicum

The fatty acid composition of ER, Golgi and peribacteroid membrane (PBM) from root nodules formed on Glycine max after infection with different strains of Bradyrhizobium japonicum has been analysed by gas chromatography. In each plant-microsymbiont combination the fatty acid composition (FAC) of the PBM is distinct from ER and Golgi. The similarity between ER and PBM fatty acid composition is significantly stronger than between Golgi and PBM. In addition the fatty acid composition of all membrane systems in nodules is affected by the microsymbiont strain. A comparison of four strains of Bradyrhizobium japonicum grown in agar surface culture and isolated as the symbiotic bacteroids reveals a decrease in oleic acid during bacteroid differentiation.     

水稻、小麦、油菜和烟草细胞质雄性不育系统中组分Ⅰ蛋白的比较分析

组分Ⅰ蛋白(RuBP羧化酶/加氧酶)的生物合成系由叶绿体基因和细胞核基因共同控制,所以,被作为研究细胞质遗传的标记。本实验用免疫化学和氨基酸成分分析等方法,对水稻(珍汕97)、小麦(繁7)、油菜(湘矮早)和烟草(G28)的细胞质雄性不育系及其保持系的组分Ⅰ蛋白作了比较,同时对不同作物的组分Ⅰ蛋白也作了免疫鉴定。结果表明,细胞质雄性不育系及其保持系的组分Ⅰ蛋白差异不大,但是,四种不同作物的组分Ⅰ蛋白之间有明显差异。     

Compositional statistics: An improvement of evolutionary parsimony and its application to deep branches in the tree of life

Summary We present compositional statistics, a new method of phylogenetic inference, which is an extension of evolutionary parsimony. Compositional statistics takes account of the base composition of the compared sequences by using nucleotide positions that evolutionary parsimony ignores. It shares with evolutionary parsimony the features of rate invariance and the fundamental distinction between transitions and transversions. Of the presently available methods of phylogenetic inference, compositional statistics is based on the fewest and mildest assumptions about the mode of DNA sequence evolution. It is therefore applicable to phylogenetic studies of the most distantly related organisms or molecules. This was illustrated by analyzing conservative positions in the DNA sequences of the large subunit of RNA polymerase from three archaebacterial groups, a eubacterium, a chloroplast, and the three eukaryotic polymerases. Internally consistent results, which are in accord with our knowledge of organelle origin and archaebacterial physiology, were achieved.