The characterization and description of representatives of 'G' bacteria from activated sludge plants

The name Tetracoccus cechii is proposed for two strains of the tetrad arranged cocci, previously known as 'G' bacteria, which were isolated from laboratory scale activated sludge plants in the Czech Republic and in Italy. They were morphologically, phenotypically and phylogenetically characterized and found to comprise a novel lineage in the alpha-3 group of the proteobacterial phylum in the domain Bacteria . The strains are Gram-negative and produce intracellular inclusions of poly-β-hydroxybutyrate. Although commonly seen in activated sludge mixed liquor as cocci 1–2 μm in diameter, arranged in tetrads, in pure culture they can also grow in amorphous aggregations and the cells are generally more variable in their size and shape with coccobacilli as well as cocci being present. They are not able to grow phototrophically, nor can they reduce nitrate beyond nitrite nor grow anaerobically. The closest phylogenetic neighbours of T. cechii are Rhodobacter sphaeroides and R. capsulatus which are 93% similar by 16S rDNA comparison. Tetracoccus cechii is oxidase- and catalase-positive, non-motile and has an optimal growth temperature between 25° and 35°C. The 16S rRNA of T. cechii has a 21 nucleotide deletion in the V9 region ( Escherichia coli positions 1258–1278) and this feature is a unique molecular synapomorphy in the alpha-3 group.     

Effect of pasteurization and storage on some components of pooled human milk

Pooled human milk was subjected to Holder pasteurization and storage at −20°C up to 90 days and examined for its content of fat and

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-lactate and for lipid composition. This treatment reduced fats by 6% and

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-lactate by at least 7%. In addition, pasteurization and storage induced triglyceride hydrolysis. The absolute amount of free fatty acids (FFAs) which was 0.5% after collection, doubled after pasteurization and rose even more after storage. Different FFA compositions were found by several authors using the same analytical method even for milk samples subjected to the same treatment. More detailed information on procedures must be given to explain the different results.     

Evolution: an axiomatic perspective.

In this paper we present an axiomatic theory of evolution which is inspired by the reading of a paper written by G.V. Schiaparelli in 1898. Schiaparelli was a famous astronomer, but he also studied the Darwinian ideas. We propose five axioms which can characterize the theory of evolution. We have also written these axioms using the language of the logic of predicates of first order with some constant monadic and dyadic predicates and appropriate functionals. But we can use other types of logic. So we can examine the concepts of species and of speciation. Then we introduce the interesting notion of generation distance. Moreover we give a theorem which establishes a geometrical model of our theory. If we analyze further the fourth axiom (which concerns the notion of generation distance) we can propose an elementary dynamical model by which we can represent possible evolutionary dynamics. These dynamics partially depend on random quantities.     

Conformational analysis of the Galpha(s) protein C-terminal region.

The C-terminal domain of the heterotrimeric G protein a-subunits plays a key role in selective activation of G proteins by their cognate receptors. Several C-terminal fragments of Galpha(s) (from 11 to 21 residues) were recently synthesized. The ability of these peptides to stimulate agonist binding was found to be related to their size. Galpha(s)(380-394) is a 15-mer peptide of intermediate length among those synthesized and tested that displays a biological activity surprisingly weak compared with that of the corresponding 21-mer peptide, shown to be the most active. In the present investigation, Galpha(s)(380-394) was subjected to a conformational NMR analysis in a fluorinated isotropic environment. An NMR structure, calculated on the basis of the data derived from conventional 1D and 2D homonuclear experiments, shows that the C-terminal residues of Galpha(s)(380-394) are involved in a helical arrangement whose length is comparable to that of the most active 21 -mer peptide. A comparative structural refinement of the NMR structures of Galpha(s)(380-394) and Galpha(s)(374-394)C379A was performed using molecular dynamics calculations. The results give structural elements to interpret the role played by both the backbone conformation and the side chain arrangement in determining the activity of the G protein C-terminal fragments. The orientation of the side chains allows the peptides to assume contacts crucial for the G protein/receptor interaction. In the 15-mer peptide the lack as well as the disorder of some N-terminal residues could explain the low biological activity observed.     

The influence of asymmetric carbon atoms of the side chains on the conformational properties of polypeptides: Comparison of diastereomeric homooligopeptides of L-isoleucine and D-alloisoleucine

The conventionally protected oligopeptides of the two homologous series Boc-(L -Ile)_n-OMe and Boc-(D -aIle)_n-OMe (n = 2–6) were synthesized in a standard stepwise fashion and their uv and CD spectra in 2,2,2-trifluoroethanol, and solid-state ir spectra were investigated. In addition, two oligomeric products derived from the NCAs of L -isoleucine and of D -allo-isoleucine and having a DP of 20 and 12, respectively, were studied in the solid state by x-ray and ir. No substantial differences between the properties of the diastereomeric oligomers in the solid state were noticed, a β-structure being very likely at least for the Boc-protected hexapeptides and the higher oligomers. In contrast, differences were observed between the spectroscopic properties of the diastereomeric oligopeptides, and especially of the hexapeptides, in trifluoroethanol solution. The different properties of the hexapeptides in solution were related to the existence, in the case of Boc-(L -Ile)₆-OMe, of soluble molecular aggregates in which the peptide chains assume the β-conformation. These results provide an additional example of the influence of the configuration of asymmetric carbon atoms of the side chains on the conformational properties of peptide molecules in solution.