Yersinia enterocolitica and related species isolated in the Pesaro and Urbino area (Italy) from 1981 to 1986

A total of 23 strains of yersinias, Y. enterocolitica (17), Y. frederiksenii (5) and Y. intermedia (1) characterized according to bio-serogroup and phage type, were isolated from human, animal and environmental samples during a 5-year period. It appears that in the Pesaro-Urbino area Yersinia spp. are infrequent and the strains of Y. enterocolitica belong to environmental and rarely to human pathogenic bioserogroups.     

Activation of chloroform and related trihalomethanes to free radical intermediates in isolated hepatocytes and in the rat in vivo as detected by the ESR-spin trapping technique

When hepatocytes isolated from phenobarbital-induced rats were incubated with chloroform and the spin trap phenyl-t-butyl nitrone (PBN) under anaerobic conditions, a free radical-spin trap adduct was detectable by ESR spectroscopy. A similar incubation of hepatocytes in the presence of air resulted in an ESR signal that was eight times less intense than that seen under anaerobic conditions; incubation mixtures exposed to pure oxygen had no detectable adduct signal. A significant reduction in the signal intensity was also produced by the addition of cytochrome P-450 inhibitors such as SKF-525A, metyrapone and carbon monoxide, indicating that free radical formation depended upon the reductive metabolism of chloroform mediated by the mixed oxidase system. The origin of the CHCl3-derived free radical has been confirmed by using [13C]CHCl3, while the comparison between the ESR spectra obtained in the presence of deuterated chloroform (CDCl3) and bromodichloro-methane (CHBrCl2) suggests that the free radical derived from CHCl3 may be CHCl2. Free radical intermediates were also detected during the aerobic and anaerobic incubation of isolated hepatocytes with bromoform (CHBr3), and iodoform (CHI3). The intensity of the ESR signal obtained with the various trihalomethanes increases in the order CHCl3 less than CHBrCl2 less than CHBr3 less than CHI3. The formation of PBN-free radical adducts has also been observed in phenobarbital-induced rats in vivo when intoxicated with chloroform, bromoform or iodoform, suggesting that the reductive metabolism of trihalomethanes might be of relevance to their established toxicity in the whole animal.     

Budding yeast Rif1 binds to replication origins and protects DNA at blocked replication forks

Despite its evolutionarily conserved function in controlling DNA replication, the chromosomal binding sites of the budding yeast Rif1 protein are not well understood. Here, we analyse genome‐wide binding of budding yeast Rif1 by chromatin immunoprecipitation, during G1 phase and in S phase with replication progressing normally or blocked by hydroxyurea. Rif1 associates strongly with telomeres through interaction with Rap1. By comparing genomic binding of wild‐type Rif1 and truncated Rif1 lacking the Rap1‐interaction domain, we identify hundreds of Rap1‐dependent and Rap1‐independent chromosome interaction sites. Rif1 binds to centromeres, highly transcribed genes and replication origins in a Rap1‐independent manner, associating with both early and late‐initiating origins. Interestingly, Rif1 also binds around activated origins when replication progression is blocked by hydroxyurea, suggesting association with blocked forks. Using nascent DNA labelling and DNA combing techniques, we find that in cells treated with hydroxyurea, yeast Rif1 stabilises recently synthesised DNA. Our results indicate that, in addition to controlling DNA replication initiation, budding yeast Rif1 plays an ongoing role after initiation and controls events at blocked replication forks.     

Evolution of eutherian cytochrome c oxidase subunit II: heterogeneous rates of protein evolution and altered interaction with cytochrome c

Cytochrome c oxidase subunit II (COII), encoded by the mitochondrial genome, exhibits one of the most heterogeneous rates of amino acid replacement among placental mammals. Moreover, it has been demonstrated that cytochrome c oxidase has undergone a structural change in higher primates which has altered its physical interaction with cytochrome c. We collected a large data set of COII sequences from several orders of mammals with emphasis on primates, rodents, and artiodactyls. Using phylogenetic hypotheses based on data independent of the COII gene, we demonstrated that an increased number of amino acid replacements are concentrated among higher primates. Incorporating approximate divergence dates derived from the fossil record, we find that most of the change occurred independently along the New World monkey lineage and in a rapid burst before apes and Old World monkeys diverged. There is some evidence that Old World monkeys have undergone a faster rate of nonsynonymous substitution than have apes. Rates of substitution at four-fold degenerate sites in primates are relatively homogeneous, indicating that the rate heterogeneity is restricted to nondegenerate sites. Excluding the rate acceleration mentioned above, primates, rodents, and artiodactyls have remarkably similar nonsynonymous replacement rates. A different pattern is observed for transversions at four-fold degenerate sites, for which rodents exhibit a higher rate of replacement than do primates and artiodactyls. Finally, we hypothesize specific amino acid replacements which may account for much of the structural difference in cytochrome c oxidase between higher primates and other mammals.      

Relationships among msx gene structure and function in zebrafish and other vertebrates

The zebrafish genome contains at least five msx homeobox genes, msxA, msxB, msxC, msxD, and the newly isolated msxE. Although these genes share structural features common to all Msx genes, phylogenetic analyses of protein sequences indicate that the msx genes from zebrafish are not orthologous to the Msx1 and Msx2 genes of mammals, birds, and amphibians. The zebrafish msxB and msxC are more closely related to each other and to the mouse Msx3. Similarly, although the combinatorial expression of the zebrafish msx genes in the embryonic dorsal neuroectoderm, visceral arches, fins, and sensory organs suggests functional similarities with the Msx genes of other vertebrates, differences in the expression patterns preclude precise assignment of orthological relationships. Distinct duplication events may have given rise to the msx genes of modern fish and other vertebrate lineages whereas many aspects of msx gene functions during embryonic development have been preserved.      

Respiratory effects of electric stimulation of pancreatic afferents in lightly anesthetized cats]

Electrical stimulation of the pancreatic anterior part produces a respiratory arrest followed by a short polypnea. In some cases (20%) the same effects are obtained by electrical stimulation of the afferent nerves. The afferent fibres involved in this phenomena are situated in the great splanchnic nerves.