Dimer–monomer equilibrium of human thymidylate synthase monitored by fluorescence resonance energy transfer

An ad hoc bioconjugation/fluorescence resonance energy transfer (FRET) assay has been designed to spectroscopically monitor the quaternary state of human thymidylate synthase dimeric protein. The approach enables the chemoselective engineering of allosteric residues while preserving the native protein functions through reversible masking of residues within the catalytic site, and is therefore suitable for activity/oligomerization dual assay screenings. It is applied to tag the two subunits of human thymidylate synthase at cysteines 43 and 43′ with an excitation energy donor/acceptor pair. The dimer–monomer equilibrium of the enzyme is then characterized through steady‐state fluorescence determination of the intersubunit resonance energy transfer efficiency.     

A Modular Mind? A Test Using Individual Data from Seven Primate Species

It has long been debated whether the mind consists of specialized and independently evolving modules, or whether and to what extent a general factor accounts for the variance in performance across different cognitive domains. In this study, we used a hierarchical Bayesian model to re-analyse individual level data collected on seven primate species (chimpanzees, bonobos, orangutans, gorillas, spider monkeys, brown capuchin monkeys and long-tailed macaques) across 17 tasks within four domains (inhibition, memory, transposition and support). Our modelling approach evidenced the existence of both a domain-specific factor and a species factor, each accounting for the same amount (17%) of the observed variance. In contrast, inter-individual differences played a minimal role. These results support the hypothesis that the mind of primates is (at least partially) modular, with domain-specific cognitive skills undergoing different evolutionary pressures in different species in response to specific ecological and social demands.     

Species of the genus Quercus in Italy: Characterization by means of leaf surface observation

Abstract

We propose a study of the main species belonging to the genus Quercus in Italy, characterized and identified by means of leaf surface observation, with special attention devoted to waxes, trichomes and stomata. Comparing our results with the classification proposed by SCHWARZ (1984), we find that species belonging to Schwarz's subgenus Quercus are recognizable because their waxes are structured in vertical scales; the two other subgenera (Sclerophyllodrys and Cerris) present smooth wax structures, their distinctive feature being the shape of the stomatal rima, which is roundish in Sclerophyllodrys and elliptical in Cerris. The study characterizes Quercus pubescens Willd. and Quercus petraea Liebl. by analyzing some morphometric traits; but the authors feel that further research is needed on these critical taxonomic entities. Lastly, the study examines forms of was degeneration correlated to the phenomenon known as oak decline.     

Augmentation of c-fos mRNA expression by activators of protein kinase C in fresh, terminally differentiated resting macrophages.

Expression of c-fos mRNA was investigated in fresh, normal peritoneal macrophages (M phi), which are terminally differentiated, nonproliferating cells. The levels of c-fos mRNA were dramatically increased by stimulation with phorbol myristate acetate (PMA), calcium ionophore, or 1-oleoyl-2-acetoyl glycerol (OAG). Induction of c-fos mRNA by all the above agents followed similar kinetics, with a peak of mRNA 30 min after stimulation. These results demonstrate that c-fos mRNA can be augmented in fresh, terminally differentiated cells. Since the stimuli increasing c-fos mRNA are direct or indirect activators of protein kinase C, our data suggest that in M phi c-fos mRNA is controlled by protein kinase C activation. PMA, calcium ionophore, and OAG were biologically active in M phi. PMA and calcium ionophore induced respiratory burst and tumoricidal activity, respectively, whereas OAG and PMA were chemotactic for M phi. Interferons beta and gamma, potent M phi activators eliciting tumoricidal activity, did not alter the levels of c-fos mRNA. These results indicate that c-fos mRNA augmentation is a stimulus-specific rather than a function-specific response connected to activation of protein kinase C.     

Plasmid-encoded ropiness production inLactobacillus casei SSP.casei

Summary Genetic determinants of the Muc⁺ character were investigated in two ropy strains,Lactobacillus delbrueckii ssp.bulgaricus 201 andL. casei ssp.casei NCIB 4114, which secrete a large amount of slime in culture media. Plasmid DNA analysis revealed the presence of two plasmids (4.5 and 2.3 Mdal) inL. casei ssp.casei, whileL. delbrueckii ssp.bulgaricus was plasmid free, suggesting a chromosomal location of Muc⁺ character in this strain. Curing experiments carried out onL. casei ssp.casei NCIB 4114 indicated a correlation between the Muc⁺ phenotype and the 4.5 Mdal plasmid.     

The complete amino acid sequences of cytosolic and mitochondrial aspartate aminotransferases from horse heart,and inferences on evolution of the isoenzymes

Summary We report here the complete amino acid sequences of the cytosolic and mitochondrial aspartate aminotransferases from horse heart. The two sequences can be aligned so that 48.1% of the amino acid residues are identical. The sequences have been compared with those of the cytosolic isoenzymes from pig and chicken, the mitochondrial isoenzymes from pig, chicken, rat, and human, and the enzyme fromEscherichia coli. The results suggest that the mammalian cytosolic and mitochondrial isoenzymes have evolved at equal and constant rates whereas the isoenzymes from chicken may have evolved somewhat more slowly. Based on the rate of evolution of the mammalian isoenzymes, the geneduplication event that gave rise to cytosolic and mitochondrial aspartate aminotransferases is estimated to have occurred at least 10⁹ years ago. The cytosolic and mitochondrial isoenzymes are equally related to the enzyme fromE. coli; the prokaryotic and eukaryotic enzymes diverged from one another at least 1.3×10⁹ years ago.     

NMR studies in solution of poly-L-proline

The isomerization of poly-L -proline in different solvents has been studied by NMR spectroscopy. Different resonance signals for the CH_α protons have been obtained for the two different helical conformations of thus compound, namely form I and form II.