Free amino acids from pollens

Pollens from Pinus canariensis, P. nigra, P. pinaster, P. pinea, Castanea sativa, Magnolia grandiflora, Olea sativa cv frantoio, cv itrana, cv pisciottana were examined for their free amino acid composition. A large amount of proline was found in all species; pollens of Olea also contain a large amount of serine.     

Inhibition of cardiolipin synthesis by end-products and other complex lipids in membrane preparations of Micrococcus lysodeikticus.

Using membrane preparations of Micrococcus lysodeikticus, the end-products of cardiolipin synthesis, cardiolipin and glycerol, were shown to inhibit cardiolipin synthetase at several concentrations. Other phospholipids tested for inhibitory effects, phosphatidyl-ethanolamine, phosphatidylinositol, and phosphatidic acid were also shown to inhibit cardiolipin synthesis. Phosphatidic acid was considerably more inhibitory than cardiolipin, phosphatidylethanolamine was similar to cardiolipin, and phosphatidylinositol less inhibitory at the same concentrations. A non-phosphate-containing glycolipid was also inhibitory. In contrast, glycerophosphate had no effect on cardiolipin synthesis.     

Spectroscopic study of monosubstituted amides. II. Rotation isomers in amides substituted by aliphatic side-chain models

The influence of the substituents upon the Amide I and νNH frequencies has been analyzed for ten amides substituted by aliphatic side chains. By considering the aliphatic chain field effect, some data are obtained as to the conformation of the N? C_α bond. In two amides, the presence of an equilibrium between two conformers is shown and a semiquantitative estimation of the energies involved is obtained. The consequences for polypeptides conformation, especially for poly-L -valine, are discussed.     

Reaction mechanism of surfactant‐sensitized chemiluminescence of bis(2,4,6‐trichlorophyenyl) oxalate and hydrogen peroxide induced by gold nanoparticles

The chemiluminescence (CL) of bis(2,4,6‐trichlorophyenyl) oxalate with hydrogen peroxide in the present of cationic surfactant and gold nanoparticles was studied. The CL emission was obviously enhanced in the presence of surfactant at a suitable concentration, with a synergetic catalysis effect exhibited. Different sizes of gold nanoparticles (15 and 50 nm) showed different effects on CL intensity. Mechanisms of the CL reaction and sensitization effect are discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Influence of environment upon the life history of gudgeon, Gobio gobio (L.): a recent and successful colonizer of the Iberian Peninsula

The growth and the reproductive tactics of gudgeon, Gobio gobio (L.) were assessed in three contrasting streams of the Iberian Peninsula: the Rivers Moros and Ucero, tributaries of the R. Duero, and the R. MatarrańGa, a tributary of the R. Ebro. The R. Duero gudgeon have spread in the last 50 years while their presence in the lower tributaries of the R. Ebro followed the construction of reservoirs in the mid 1960s. The life histories of the Moros and MatarrańnGa gudgeon are very similar; rapid growth in spring, early reproduction (1 -year-old), high reproductive cost, short life-span and trend to semelparity. Both populations are strongly influenced by the severe summer droughts that result in (I) reduction in the condition coefficient, (2) reduction in the growth rate (particularly in the River MatarrańGa), (3) single spawning and (4) no gonad development in the summer. The gudgeon in the Ucero delay maturity, grow slower, are multi-spawners and have a longer life span. All the Duero populations come from the same genetic pool and they are actually connected through the populations living along this river basin, whereas the MatarrańGa population is not genetically linked, we hypothesize that the differences between these populations are environmentally induced.     

Pre‐copulation intervals,copulation frequencies,and initial progeny sex ratios in two biotypes of whitefly,Bemisia tabaci

The whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) is a species complex, and its systematic classification requires controlled crossing experiments among its genetic groups. Accurate information on pre‐copulation intervals, copulation frequencies, and initial frequency of egg fertilization of newly emerged adults is critical for designing procedures for collecting the virgin adults necessary for these experiments. In the literature, considerable variation is reported between B. tabaci populations, with respect to the length of the pre‐copulation interval and the initial frequency of egg fertilization. Here, we used a video‐recording method to observe continuously the copulation behaviour of the Mediterranean/Asia Minor/Africa (B biotype) and the Asia II (ZHJ1 biotype) groups of B. tabaci. We also recorded the initial frequency of egg fertilization, as determined by the sex of the progeny. When adults were caged in female–male pairs on leaves of cotton plants, the earliest copulation events occurred 2–6 h after emergence; at 12 h after emergence 56–84% of the females had copulated at least once, and nearly all (92–100%) had copulated at least once by 36 h after emergence. Both females and males copulated repeatedly. Approximately 80 and 20% of copulation events occurred during the photophase and scotophase, respectively. By 72 h post‐emergence, the females of the B and ZHJ1 biotypes had copulated on average 6.1 and 3.9 times, respectively. When adults were caged in groups on plants 1–13 h after emergence, 30–35% of the eggs deposited during this period were fertilized, and approximately 90% of females were fertilized by the end of the 13 h. Although timing of copulation differed in detail between the two genetic groups, the results demonstrate that B. tabaci adults can start to copulate as early as 2–6 h post‐emergence and the majority of females can become fertilized on the day that they emerge.     

Exopolysaccharide-producing strains of thermophilic lactic acid bacteria cluster into groups according to their EPS structure

AIMS: To compare galactose-negative strains of Streptococcus thermophilus and Lactobacillus delbrueckii subspecies bulgaricus isolated from fermented milk products and known to produce exopolysaccharides (EPSs). METHODS AND RESULTS: The structures of the EPSs were determined using nuclear magnetic resonance (NMR) and their genetic relationships determined using restriction endonuclease analysis (REA) and random amplification of polymorphic DNA (RAPD). Similar groupings were apparent by REA and RAPD, and each group produced an EPS with a particular subunit structure. CONCLUSION: Although none of the strains assimilated galactose, all inserted a high proportion of galactose into their EPS when grown in skimmed milk, and fell into three distinct groups. Significance and Impact of the Study: This information should help in an understanding of genetic exchanges in lactic acid bacteria.