Occurrence of [copper, zinc]-cofactored Superoxide dismutase in Pasteurella haemolytica and its serotype distribution

Abstract Evidence was sought for the existence of an inducible acid tolerance response in Mycobacterium smegmatis . Exposure of M. smegmatis to a sub-lethal, adaptive acidic pH was found to confer a significant level of protection against subsequent exposure to a lethal pH, compared to unadapted cells. Adaptation was dependent on de novo protein synthesis.     

Cell shape and chromosome partition in prokaryotes or,why E. coli is rod-shaped and haploid

In the rod-shaped cells of E. coli, chromosome segregation takes place immediately after replication has been completed. A septum then forms between the two sister chromosomes. In the absence of certain membrane proteins, cells grow instead as large, multichromosomal spheres that divide successively in planes that are at right angles to one another. Although multichromosomal, the spherical cells cannot be maintained as heterozygotes. These observations imply that, in these mutants, each individual chromosome gives rise to a separate clone of descendant cells. This suggests a model in which sites for cell division form between pairs of sister chromosomes at the time of segregation, but are not used in spherical cells until further rounds of replication have taken place, thus ensuring clonal (‘hierarchical’) segregation of chromosomes into progeny cells. The role of the morphogenetic membrane proteins is to convert the basically spherical cell into a cylinder that is able to divide as soon as replication and segregation have been completed, and thus to maximise the number of viable cells per genome.     

Effects of chorda tympani nerve anesthesia on taste responses in the NST

Human clinical and psychophysical observations suggest that the taste system is able to compensate for losses in peripheral nerve input, since patients do not commonly report decrements in whole mouth taste following chorda tympani nerve damage or anesthesia. Indeed, neurophysiological data from the rat nucleus of the solitary tract (NST) suggests that a release of inhibition (disinhibition) may occur centrally following chorda tympani nerve anesthesia. Our purpose was to study this possibility further. We recorded from 59 multi- and single- unit taste-responsive sites in the rat NST before, during and after recovery from chorda tympani nerve anesthesia. During anesthesia, average anterior tongue responses were eliminated but no compensatory increases in palatal or posterior tongue responses were observed. However, six individual sites displayed increased taste responsiveness during anesthesia. The average increase was 32.9%. Therefore, disinhibition of taste responses was observed, but infrequently and to a small degree in the NST At a subset of sites, chorda tympani-mediated responses decreased while greater superficial petrosal-mediated responses remained the same during anesthesia. Since this effect was accompanied by a decrease in spontaneous activity, we propose that taste compensation may result in part by a change in signal-to-noise ratio at a subset of sites.