Nutrient signaling through TOR kinases controls gene expression and cellular differentiation in fungi.

The TOR kinases were first identified in Saccharomyces cerevisiae as the targets of the immunosuppressive drug rapamycin. Subsequent studies employing rapamycin as a tool in yeast have given us insight into the structure and function of the TOR kinases, as well as the biological role of the TOR signaling program in transmitting nutrient signals to promote cell growth. One of the major advances from this area has been in defining an unexpected role for TOR signaling in the regulation of transcription. The identification of target genes subject to regulation by TOR has provided a platform for the dissection of the signaling events downstream of the TOR kinases. Studies aimed at understanding TOR-regulated transcription have begun to shed light on how TOR signaling cooperates with other signaling programs. In addition, the TOR pathway regulates the developmental program of pseudohyphal differentiation in concert with highly conserved MAP kinase and PKA signaling programs. Remarkably, rapamycin also blocks filamentation in a number of important human and plant pathogens and the mechanism of rapamycin action is conserved in Candida albicans and Cryptococcus neoformans. The antimicrobial properties of less immunosuppressive analogs of rapamycin hold promise for the development of an effective antifungal therapy.

Multiple signals regulate GAL transcription in yeast.

Gal4p activates transcription of the Saccharomyces GAL genes in response to galactose and is phosphorylated during interaction with the RNA polymerase II (Pol II) holoenzyme. One phosphorylation at S699 is necessary for full GAL induction and is mediated by Srb10p/CDK8 of the RNA Pol II holoenzyme mediator subcomplex. Gal4p S699 phosphorylation is necessary for sensitive response to inducer, and its requirement for GAL induction can be abrogated by high concentrations of galactose in strains expressing wild-type GAL2 and GAL3. Gal4p S699 phosphorylation occurs independently of Gal3p and is responsible for the long-term adaptation response observed in gal3 yeast. SRB10 and GAL3 are shown to represent parallel mechanisms for GAL gene induction. These results demonstrate that Gal4p activity is controlled by two independent signals: one that acts through Gal3p-galactose and a second that is mediated by the holoenzyme-associated cyclin-dependent kinase Srb10p. Since Srb10p is regulated independently of galactose, our results suggest a function for CDK8 in coordinating responses to specific inducers with the environment through the phosphorylation of gene-specific activators.

The Yersinia enterocolitica pYV virulence plasmid contains multiple intrinsic DNA bends which melt at 37 degrees C.

Temperature has a pleiotropic effect on Yersinia enterocolitica gene expression. Temperature-dependent phenotypes include the switching between two type III protein secretion systems, flagellum biosynthesis (

Thermoregulation in Yersinia enterocolitica is coincident with changes in DNA supercoiling.

Yersinia enterocolitica is a facultative intracellular parasite, displaying the ability to grow saprophytically or invade and persist intracellularly in the mammalian reticuloendothelial system. The transition between such diverse environments requires the co-ordinated regulation of specific sets of genes on both the chromosome and virulence plasmid. Temperature has a profound pleiotropic effect on gene expression and phenotypically promotes alterations in cell morphology, outer-membrane protein synthesis, urease production, lipopolysaccharide synthesis, motility, and synthesis of genes involved in invasion of eukaryotic host cells. By examining thermoregulated flagella biosynthesis, we have determined that motility is repressed at 25 degrees C (permissive temperature) with subinhibitory concentrations of novobiocin. These conditions also induce virulence gene expression suggesting novobiocin addition simulates, at least partially, a high-temperature environment. Furthermore, temperature-shift experiments, using Y. enterocolitica containing pACYC184 as a reporter plasmid, indicate that thermo-induced alterations of DNA supercoiling coincide with temperature-induced phenotypic changes. A class of putative DNA gyrase mutant (novobiocin resistant) likewise demonstrates the 37 degrees C phenotype when cultured at 25 degrees C; it is non-motile, urease negative, calcium growth dependent, and positive for Yop expression. These results support a model implicating DNA topology as a contributing factor of Y. enterocolitica thermoregulation.

Ways of telling new parents about their child and his or her mental handicap: a comparison of doctors' and parents' views.

Views about ways of telling parents their child has a mental handicap were collected from a group of parents of children with mental handicaps and a group of doctors with some involvement in this field, using postal questionnaires. Four Likert-type scales were refined covering views about the fullness of information, how early parents should be told, whether parents should be protected from shock and unpleasant information, and who should take a primary role in decision-making. Results indicated that parents were more in favour of being given information about their children's handicaps at an early stage than doctors were, and that they saw themselves as the primary decision-makers in matters to do with their children, whilst doctors were more neutral about this. There were no differences in how parents and doctors felt about the fullness of explanations or about the explicit 'protection' of parents from shock and unpleasant information. The results support the findings of other studies which have stressed parents' wishes to be given as much information as early as possible and to be treated as the people primarily responsible for their child. In addition, a difference between what doctors believe to be the best approach and what parents believe to be the best approach is suggested, and the importance of doctors being given opportunities to learn directly from parents and people with mental handicaps themselves is emphasized.

A study of doctors' and parents' attitudes to people with mental handicaps.

The attitudes to people with mental handicaps held by a group of parents of children with mental handicaps and a group of doctors with some involvement in this area were compared using postal questionnaires. Doctors' estimates of how parents would respond were also compared with parents' responses and doctors' own responses. Four Likert-type scales were refined covering attitudes towards the effect on the family, the place in society of people with mental handicaps, their quality of life, and independence and autonomy. Results indicated that parents had more positive attitudes than doctors except with regard to independence and autonomy, to which doctors had the most positive attitudes. Doctors were aware that parents were likely to see the effect on the family in a more positive light, and independence less positively, than themselves. However, they underestimated the degree of positivity of parents about the place of people with mental handicaps in society, and their quality of life, to the extent that they expected parents to be significantly less positive about quality of life than they themselves were, whilst parents in fact proved significantly more positive. The differing perspectives and experiences of parents and doctors are discussed and some suggestions made of ways in which doctors' appreciation of the parental perspective could be developed in an attempt to facilitate sympathetic communication between them.

Patterns of use of a mental handicap register in its first 5 years.

After its first 5 years in full operation, the requests for information made to a mental handicap register were examined. It was found that the register had been used extensively by a large number of people requesting a variety of information, both statistical and personal, relating to groups and individuals, and used both to gain an increased understanding of the present situation and to plan for change. Questionnaires sent to those people who had used the register in the first 6 months of 1985 revealed a high level of satisfaction with the register's ability to provide the information they requested. The uses and limitations of the register are discussed.

Suicide in England and Wales: an analysis of 100 years, 1876-1975.

The variations in suicide mortality in England and Wales over a 100-year period (1876-1975) are explained by the development of a descriptive model. The model used in a stepwise linear regression using 5 variables including toxic gas production. The variables give a good description of the observed changes in suicide mortality. The limitations of the method and the data are discussed. Despite the limitations of the method, it can be concluded that toxic gas production affected total suicide mortality.