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C Boone

Publications and source records attributed to C Boone.

At least 37 records · Page 2Linked to original sources
PubMed1997

Genetic analysis of default mating behavior in Saccharomyces cerevisiae.

Haploid Saccharomyces cerevisiae cells find each other during conjugation by orienting their growth toward each other along pheromone gradients (chemotropism). However, when their receptors are saturated for pheromone binding, yeast cells must select a mate by executing a default pathway in which they choose a mating partner at random. We previously demonstrated that this default pathway requires the SPA2 gene. In this report we show that the default mating pathway also requires the AXL1, FUS1, FUS2, FUS3, PEA2, RVS161, and BNI1 genes. These genes, including SPA2, are also important for efficient cell fusion during chemotropic mating. Cells containing null mutations in these genes display defects in cell fusion that subtly affect mating efficiency. In addition, we found that the defect in default mating caused by mutations in SPA2 is partially suppressed by multiple copies of two genes, FUS2 and MFA2. These findings uncover a molecular relationship between default mating and cell fusion. Moreover, because axl1 mutants secrete reduced levels of a-factor and are defective at both cell fusion and default mating, these results reveal an important role for a-factor in cell fusion and default mating. We suggest that default mating places a more stringent requirement on some aspects of cell fusion than does chemotropic mating.

DNA-Binding Proteins↗
PubMed1997

An anti-adipocyte monoclonal antibody is cytotoxic to porcine preadipocytes in vitro and depresses the development of pig adipose tissue.

A mouse monoclonal antibody of the IgG2b subclass was raised against porcine adipocyte plasma membranes. This antibody did not cross-react in immunocytofluorescence with any tested cell-type or tissue other than porcine adipocytes. Complement-mediated cytotoxicity was demonstrated in primary cultures of porcine stromal-vascular cells. When the antibody and complement were added to already differentiated cultures, the treatment resulted in elimination of lipid-filled preadipocytes, whereas an early treatment of cultures prevented the appearance of these cells. In vivo, injection of newborn pigs with 1 mg/kg of monoclonal antibody on d 2 and 5 of life produced a more than 20% reduction of subcutaneous and leaf fat lipids at 35 d of age, whereas the lipid content of the longissimus muscle remained unaffected. These results demonstrate that early systemic treatment of pigs with a specific anti-adipocyte antibody reduces the fat mass. In addition to their potential in vivo use, monoclonal antibodies directed against adipose determinants may be useful tools for studying adipocyte lineage.

Adipocytes↗
PubMed1996

Locus of control, sensation seeking, and stress.

We explored the relations among locus of control, sensation seeking, and stress (N = 68 students). Corroborating evidence was found that subjects with an external locus of control are more vulnerable to stress. Subjects scoring higher on the thrill and adventure seeking-dimension of sensation seeking reported less severe physical and psychological complaints thought to be associated with stress. These results suggest that high sensation seeking is associated with protective mechanisms against life-stress. Some possible intervening mechanisms are further discussed.

Adult↗
PubMed1996

Effects of acute or chronic administration of tumor necrosis factor on rat adipose tissue development.

Because tumor necrosis factor (TNF) inhibits adipose cell differentiation in vitro and affects lipid metabolism in vivo, we treated adult or newborn rats for 1 wk with daily intraperitoneal injections (100 U/g of body weight) or continuous intraperitoneal diffusion (3500 U/h) of human recombinant TNF. Three weeks after the end of treatment, the long-term effect of the cytokine was examined on adipose tissue development. Control and TNF-injected rats did not differ in growth or development of perirenal, retroperitoneal and epididymal adipose tissues. Nevertheless, the size distribution of epididymal adipocytes of adult injected rats presented a slight shift towards larger values in the cytokine group. When TNF was administered chronically, the cytokine exerted an anorectic effect, which was alleviated after the end of treatment. The weights of the excised adipose tissues were depressed (P < .025) by TNF administration. Part of this effect was due to the induced anorexia. The size distributions of the epididymal adipocytes of pair-fed and TNF-treated rats were both shifted to smaller (P < 0.01) values than for the controls. The ratio of triglycerides over total lipids was, however, reduced by TNF specifically, but only at the retroperitoneal (P < .05) and not the epididymal site. These results indicate that in contrast to acute treatment, chronic TNF treatment slightly inhibited adipose tissue development in vivo; however, most of this effect was attributable to the associated anorexia.

Adipocytes↗
PubMed1995

Role of yeast insulin-degrading enzyme homologs in propheromone processing and bud site selection.

The Saccharomyces cerevisiae AXL1 gene product Axl1p shares homology with the insulin-degrading enzyme family of endoproteases. Yeast axl1 mutants showed a defect in a-factor pheromone secretion, and a probable site of processing by Axl1p was identified within the a-factor precursor. In addition, Axl1p appears to function as a morphogenetic determinant for axial bud site selection. Amino acid substitutions within the presumptive active site of Axl1p caused defects in propheromone processing but failed to perturb bud site selection. Thus, Axl1p has been shown to participate in the dual regulation of distinct signaling pathways, and a member of the insulinase family has been implicated in propeptide processing.

Amino Acid Sequence↗
PubMed1993

Mutations that alter the third cytoplasmic loop of the a-factor receptor lead to a constitutive and hypersensitive phenotype.

The STE3 gene of Saccharomyces cerevisiae encodes a G protein-coupled receptor that is specific for the mating pheromone a-factor. The ste3L194Q mutation, which leads to the substitution of glutamine for leucine-194 within the third cytoplasmic loop of the receptor, resulted in a 20-fold increase in pheromone sensitivity and also caused partial constitutive activation of the response pathway. Moreover, other amino acid substitutions at the 194 position and several deletion mutations that collectively remove most of the third cytoplasmic loop resulted in hyperactive receptors. Therefore, we suggest that one role of the third cytoplasmic loop is to function as a negative regulatory domain involved in the maintenance of a nonsignaling state of the receptor. The constitutive activity and the pheromone hypersensitivity of ste3L194Q cells were recessive, suggesting that the wild-type receptor can antagonize the signal associated with the activated receptor. The ste3 delta 306 mutation, which results in truncation of most of the C-terminal domain of the receptor, led to a 20-fold increase in pheromone sensitivity, indicating that this domain also mediates negative regulation of the receptor. The ste3L194Q and ste3 delta 306 mutations appear to affect receptor activity independently, because the double mutant was associated with a 400-fold increase in pheromone sensitivity.

Alleles↗
PubMed1993

Restructuring military health care: the winds of change blow stronger.

The Military Health Services System is an enormously complex enterprise, consisting of more than 400,000 personnel in the active, reserve, and civilian workforce, operating 148 hospitals and over 800 medical and dental clinics worldwide, and serving nearly 9 million beneficiaries. Expenditures on military health care activities will exceed $15 billion in 1993. Yet many people in leadership positions in government--both inside and outside the Department of Defense--question whether the current organization of the Military Health Services System is appropriate to accomplish the Department's medical missions. Some insiders have observed that having three military medical services is having two too many--that a single "purple" medical service, or at least a single management structure such as a Defense Health Agency, would better meet military mission requirements as the Defense Department undergoes post-Cold War downsizing. One of the most pressing challenges facing military health care managers is how to best organize resources to provide timely access to quality care and achieve economies at a time when civilian health care is itself in turmoil. This article provides a long-awaited update on the spirited debate over the need to reorganize the Military Health Services System--and the prescriptions ordered so far to cure the system's perceived organizational ills.

Government Agencies↗
PubMed1992

Yeast KRE2 defines a new gene family encoding probable secretory proteins, and is required for the correct N-glycosylation of proteins.

We have cloned, sequenced and disrupted the KRE2 gene of Saccharomyces cerevisiae, identified by killer-resistant mutants with a defective cell wall receptor for the toxin. The KRE2 gene is close to PHO8 on chromosome 4, and encodes a predicted 49-kD protein, Kre2p, that probably enters the secretory pathway. Haploid cells carrying a disruption of the KRE2 locus grow more slowly than wild-type cells at 30 degrees, and fail to grow at 37 degrees. At 30 degrees, kre2 mutants showed altered N-linked glycosylation of proteins, as the average size of N-linked outer chains was reduced. We identified two other genes, YUR1 on chromosome 10, and KTR1 on chromosome 15, whose predicted products share 36% identity with Kre2p over more than 300 amino acid residues. Yur1p has an N-terminal signal sequence like Kre2p, while Ktr1p has a predicted topology consistent with a type 2 membrane protein. In all cases the conserved regions of these proteins appear to be on the lumenal side of secretory compartments, suggesting related function. KRE2, KTR1 and YUR1 define a new yeast gene family.

Amino Acid Sequence↗
PubMed1992

Stability of choice reaction time and synchronicity of peak EMG values during bimanual reactions.

18 volunteers of our Faculty participated in two quasi-identical experiments six months apart. Repeated measurements of reaction time and synchronicity of peak forearm EMG values during bimanual reactions are analyzed by means of analysis of variance with subjects and measurement period as factors. Using Ebel's formula, test-retest reliabilities derived from the analysis vary between .82 and .94 for reaction times on different tasks and conditions and between .75 and .92 for synchronicity of peak EMG values.

Adult↗
PubMed1992

Locus of control and cerebral asymmetry.

Data about the lack of synchronism of flexor carpi ulnaris peak EMG values of bimanual reactions during a semantic and during a visuospatial discrimination reaction time task are reported. The effects of type of task as well as the presence or absence of an unexpected stimulus preceding the reaction stimulus on lack of synchronism clearly depend upon the locus of control of the subjects, as measured on Rotter's I-E scale. On the basis of several arguments it is proposed that the measure of lack of synchronism reflects in an opposite sense the amount of dopaminergic activation or motor readiness in the sense in which Pribram and McGuinness in 1975 and Tucker and Williamson in 1984 have defined these concepts. The results for 15 women and 18 men show that more internally oriented subjects are more activated by a semantic task and by an unexpected preparatory stimulus in this type of task than more externally oriented subjects. The opposite appears to hold on the visuospatial task and unexpected preparatory stimuli therein. Together with earlier findings about reaction times and a number of relevant findings in the literature, the results are interpreted as indicative of basic differences in asymmetric tonic activation of the cerebral hemispheres between more internally and more externally oriented subjects. A model is proposed to explain phasic activating effects which ensue when tonically more left- or right-activated subjects perform left- or right-hemisphere tasks and when supplementary irrelevant stimuli are received.

Adult↗
PubMed1991

Isolation from Candida albicans of a functional homolog of the Saccharomyces cerevisiae KRE1 gene, which is involved in cell wall beta-glucan synthesis.

The KRE1 gene of Saccharomyces cerevisiae, sacKRE1, appears to be involved in the synthesis of cell wall beta-glucan. S. cerevisiae strains with mutations in the KRE1 gene produce a structurally altered cell wall (1----6)-beta-glucan, which results in resistance to K1 killer toxin. We isolated the canKRE1 gene from Candida albicans by its ability to complement a kre1 mutation in S. cerevisiae and confer sensitivity to killer toxin. Sequence analysis revealed that the predicted protein encoded by canKRE1 shares an overall structural similarity with that encoded by sacKRE1. The canKRE1 protein is composed of an N-terminal signal sequence, a central domain of 46% identity with the sacKRE1 protein, and a C-terminal hydrophobic tract. These structural and functional similarities imply that the canKRE1 gene carries out a function in C. albicans cell wall assembly similar to that observed for sacKRE1 in S. cerevisiae.

Amino Acid Sequence↗
PubMed1990

Genetic and molecular approaches to synthesis and action of the yeast killer toxin.

The K1 killer toxin of Saccharomyces cerevisiae is a secreted, virally-coded protein lethal to sensitive yeasts. Killer yeasts are immune to the toxin they produce. This killer system has been extensively examined from genetic and molecular perspectives. Here we review the biology of killer yeasts, and examine the synthesis and action of the protein toxin and the immunity component. We summarise the structure of the toxin precursor gene and its protein products, outline the proteolytic processing of the toxin subunits from the precursor, and their passage through the yeast secretory pathway. We then discuss the mode of action of the toxin, its lectin-like interaction with a cell wall glucan, and its probable role in forming channels in the yeast plasma membrane. In addition we describe models of how a toxin precursor species functions as the immunity component, probably by interfering with channel formation. We conclude with a review of the functional domains of the toxin structural gene as determined by site-directed mutagenesis. This work has identified regions associated with glucan binding, toxin activity, and immunity.

Cell Membrane↗
PubMed1990

Yeast KRE genes provide evidence for a pathway of cell wall beta-glucan assembly.

The Saccharomyces cerevisiae KRE1 gene encodes a Ser/Thr-rich protein, that is directed into the yeast secretory pathway, where it is highly modified, probably through addition of O-linked mannose residues. Gene disruption of the KRE1 locus leads to a 40% reduced level of cell wall (1----6)-beta-glucan. Structural analysis of the (1----6)-beta-glucan fraction, isolated from a strain with a krel disruption mutation, showed that it had an altered structure with a smaller average polymer size. Mutations in two other loci, KRE5 and KRE6 also lead to a defect in cell wall (1----6)-beta-glucan production and appear to be epistatic to KRE1. These findings outline a possible pathway of assembly of yeast cell wall (1----6)-beta-glucan.

Amino Acid Sequence↗
PubMed1990

Relationships among locus of control, type of task (visuospatial versus semantic), and arousal or activation by an unexpected preparatory signal.

In this experiment, which is partly a replication of two earlier ones, we tested the hypothesis that the brain self-regulates its own arousal and activation. According to the underlying paradigm, arousal effectuates slower reaction times and depressed EMG activity after an unexpected preparatory signal on a visuospatial choice-reaction task, whereas activation effectuates faster reaction times and elevated EMG activity after an unexpected preparatory signal on a semantic choice-reaction task. The results basically confirm the predictions. The relationship of locus of control scores of the subjects with tonic and phasic EMG activity was also explored. The results clearly and consistently show elevated tonic EMG activity in the left forearm for subjects with an external locus of control. Together the results suggest that the mechanisms involved are partly preconscious and probably related to central catecholaminergic activation systems.

Adult↗
PubMed1990

Relation of scores on Rotter's I-E scale to short-term and long-term control expectancies and fatalism.

The purpose of the present research was twofold. First, we analysed whether expectancies of personal control versus nonpersonal control could reliably be assessed by structured interviews recorded on videotape. Second, by means of factor analysis, we analysed the relation between the interview locus-of-control scores and the scores obtained by Rotter's I-E. scale. Analysis showed that the scores on Rotter's I-E scale are correlated with short-term expectancies but not with long-term expectancies or fatalism. Possible explanations for these findings are suggested.

Adult↗
PubMed1989

Chemoprevention and modern cancer prevention.

Chemoprevention is a new area of research emphasis in cancer control. The rationale is based on the accumulation of laboratory and epidemiological data indicating that various agents may halt or reverse cancer progression in animals and may reduce risks in humans. For planning purposes, research leads are submitted to a strategic system of staging with defined criteria and decision points. A research lead that enters an intervention stage must evolve through a series of phases of testing and evaluation. Human intervention clinical trials have begun to test the hypothesis that certain agents can lower cancer incidence.

Animals↗