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S D Harris

Publications and source records attributed to S D Harris.

28 records · Page 2Linked to original sources
PubMed1994

Identification and characterization of Aspergillus nidulans mutants defective in cytokinesis.

Filamentous fungi undergo cytokinesis by forming crosswalls termed septa. Here, we describe the genetic and physiological controls governing septation in Aspergillus nidulans. Germinating conidia do not form septa until the completion of their third nuclear division. The first septum is invariantly positioned at the basal end of the germ tube. Block-and-release experiments of nuclear division with benomyl or hydroxyurea, and analysis of various nuclear division mutants demonstrated that septum formation is dependent upon the third mitotic division. Block-and-release experiments with cytochalasin A and the localization of actin in germlings by indirect immunofluorescence showed that actin participated in septum formation. In addition to being concentrated at the growing hyphal tips, a band of actin was also apparent at the site of septum formation. Previous genetic analysis in A. nidulans identified four genes involved in septation (sepA-D). We have screened a new collection of temperature sensitive (ts) mutants of A. nidulans for strains that failed to form septa at the restrictive temperature but were able to complete early nuclear divisions. We identified five new genes designated sepE, G, H, I and J, along with one additional allele of a previously identified septation gene. On the basis of temperature shift experiments, nuclear counts and cell morphology, we sorted these cytokines mutants into three phenotypic classes. Interestingly, one class of mutants fails to form septa and fails to progress past the third nuclear division. This class of mutants suggests the existence of a regulatory mechanism in A. nidulans that ensures the continuation of nuclear division following the initiation of cytokinesis.

Alleles↗
PubMed1993

How coping mediates the effect of optimism on distress: a study of women with early stage breast cancer.

At diagnosis, 59 breast cancer patients reported on their overall optimism about life; 1 day presurgery, 10 days postsurgery, and at 3-, 6-, and 12-month follow-ups, they reported their recent coping responses and distress levels. Optimism related inversely to distress at each point, even controlling for prior distress. Acceptance, positive reframing, and use of religion were the most common coping reactions; denial and behavioral disengagement were the least common reactions. Acceptance and the use of humor prospectively predicted lower distress; denial and disengagement predicted more distress. Path analyses suggested that several coping reactions played mediating roles in the effect of optimism on distress. Discussion centers on the role of various coping reactions in the process of adjustment, the mechanisms by which dispositional optimism versus pessimism appears to operate, third variable issues, and applied implications.

Adaptation, Psychological↗
PubMed1992

Molecular analysis of Saccharomyces cerevisiae chromosome I. On the number of genes and the identification of essential genes using temperature-sensitive-lethal mutations.

Previous analyses of Saccharomyces cerevisiae chromosome I have suggested that the majority (greater than 75%) of single-copy essential genes on this chromosome are difficult or impossible to identify using temperature-sensitive (Ts-) lethal mutations. To investigate whether this situation reflects intrinsic difficulties in generating temperature-sensitive proteins or constraints on mutagenesis in yeast, we subjected three cloned essential genes from chromosome I to mutagenesis in an Escherichia coli mutator strain and screened for Ts- lethal mutations in yeast using the "plasmid-shuffle" technique. We failed to obtain Ts- lethal mutations in two of the genes (FUN12 and FUN20), while the third gene yielded such mutations, but only at a low frequency. DNA sequence analysis of these mutant alleles and of the corresponding wild-type region revealed that each mutation was a single substitution not in the previously identified gene FUN19, but in the adjacent, newly identified essential gene FUN53. FUN19 itself proved to be non-essential. These results suggest that many essential proteins encoded by genes on chromosome I cannot be rendered thermolabile by single mutations. However, the results obtained with FUN53 suggest that there may also be significant constraints on mutagenesis in yeast. The 5046 base-pair interval sequenced contains the complete FUN19, FUN53 and FUN20 coding regions, as well as a portion of the adjacent non-essential FUN21 coding region. In all, 68 to 75% of this interval is open reading frame. None of the four predicted products shows significant homologies to known proteins in the available databases.

Amino Acid Sequence↗
PubMed1992

Effects of mastectomy versus lumpectomy on emotional adjustment to breast cancer: a prospective study of the first year postsurgery.

PURPOSE: Procedure (mastectomy v lumpectomy) and choice of procedure were examined as predictors of adjustment to breast cancer in a prospective study of the experiences of the first year after surgery. PATIENTS AND METHODS: Breast cancer patients were interviewed the day before surgery, 10 days after surgery, and at the 3-month, 6-month, and 12-month follow-ups. Patients included 24 women who received mastectomy on strong recommendation, 24 who chose mastectomy for other reasons, and 15 who chose lumpectomy. Subjective well-being was assessed in terms of mood disturbance, perceived quality of life, life satisfaction, marital satisfaction, perceptions of social support, and self-rated adjustment. RESULTS: Surgical groups differed in well-being in only one respect: lumpectomy patients reported a higher-quality sex life at 6 and 12 months postsurgery than mastectomy patients. Choice of surgical procedure predicted higher levels of life satisfaction at 3 months. CONCLUSION: The lack of difference between surgical groups in areas other than sexual adjustment replicates previous findings, but extends them by (1) using a fully prospective design, (2) providing data on the period surrounding the surgery (as well as later periods), and (3) examining a broader range of indices of well-being than usual.

Adaptation, Psychological↗
PubMed1991

Genetic analysis of Saccharomyces cerevisiae chromosome I: on the role of mutagen specificity in delimiting the set of genes identifiable using temperature-sensitive-lethal mutations.

In a previous attempt to identify as many as possible of the essential genes on Saccharomyces cerevisiae chromosome I, temperature-sensitive (Ts-) lethal mutations that had been induced by ethyl methane-sulfonate or nitrosoguanidine were analyzed. Thirty-two independently isolated mutations that mapped to chromosome I identified only three complementation groups, all of which had been known previously. In contrast, molecular analyses of segments of the chromosome have suggested the presence of numerous additional essential genes. In order to assess the degree to which problems of mutagen specificity had limited the set of genes detected using Ts- lethal mutations, we isolated a new set of such mutations after mutagenesis with UV or nitrogen mustard. Surprisingly, of 21 independently isolated mutations that mapped to chromosome I, 17 were again in the same three complementation groups as identified previously, and two of the remaining four mutations were apparently in a known gene involved in cysteine biosynthesis. Of the remaining two mutations, one was in one of the essential genes identified in the molecular analyses, and the other was too leaky to be mapped. These results suggest that only a minority of the essential genes in yeast can be identified using Ts- lethal mutations, regardless of the mutagen used, and thus emphasize the need to use multiple genetic strategies in the investigation of cellular processes.

Chromosome Mapping↗
PubMed1989

PAs and HIV-antibody testing. The need for guidelines when the practitioner is at risk. Discussion.

The PA profession should establish guidelines for PAs at risk for infection with the human immunodeficiency virus (HIV) who wish to be tested for HIV antibody. Confidentiality and anonymity are critical factors, along with the employer's established policies. PAs working in emergency and surgical settings may be at greater professional risk of exposure to HIV; those with personal risk factors may consider being tested if their work exposes them to opportunistic infections. A clearinghouse for information should be established through the American Academy of Physician Assistants and state chapters.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Transport of yeast vacuolar trehalase to the vacuole.

We have tested yeast secretory mutants, which define different stages of the secretory pathway, for their levels of vacuolar trehalase activity. Mutations that cause accumulation of secretory proteins in the endoplasmic reticulum or in the Golgi body lead to diminished vacuolar trehalase activity. Mutations that cause accumulation of secretory vesicles have no effect on vacuolar trehalase activity. None of the mutations affects cytoplasmic trehalase activity. These results provide further evidence for the existence of a compartmentalized trehalase in yeast, and demonstrate that the enzyme enters the secretory pathway.

Biological Transport↗
PubMed1975

Specific human B lymphocyte alloantigens linked to HL-A.

Sera, previously found to react specifically with B lymphoid cultured cells, were tested on isolated T and B peripheral blood lymphocytes in a microcytotoxicity assay. Studies were performed on lymphocytes obtained from several large Amish families. The sera used in these studies were cytotoxic to peripheral blood, B lymphocytes, but not cytotoxic to T lymphocytes. The antigens detected followed the inheritance pattern of HL-A haplotypes. The strong linkage disequilibrium with HL-A antigens suggests that genes controlling the expression of B lymphocyte antigens are linked to genes controlling HL-A alloantigens.

B-Lymphocytes↗
PubMedDate not supplied

Concern about aspects of body image and adjustment to early stage breast cancer.

OBJECTIVE: Several authors have suggested that patients adjust more poorly to breast cancer if they are heavily invested in body image as a source of their sense of self-worth. This prospective study examined this possibility, looking at two aspects of concern about body image as predictors of several indices of adjustment over the first postoperative year. METHODS: At diagnosis (and again a year later) 66 women with early stage breast cancer reported how much they valued a) a sense of body integrity (or intactness) and b) a good physical appearance. The day before surgery, a week afterward, and at 3-month, 6-month, and 12-month follow ups, they reported on their mood. At presurgery and at follow ups they also rated their attractiveness and sexual desirability and reported on frequency of sexual interaction. At follow-ups they also indicated how much their illness and treatment were interfering with social and recreational activities. RESULTS: Initial investment in appearance was related to distress across the postsurgical year. In contrast, investment in appearance made women more resilient against deterioration in their perceptions of attractiveness. Concern about body integrity did not strongly predict emotional distress, but it related to adverse impact on social and recreational activities in the follow-up period, to deterioration in feelings of sexual desirability, and to feelings of alienation from the self (feeling "not like yourself anymore"). CONCLUSIONS: Body image is often thought of in terms of physical appearance, but there is also a body image pertaining to integrity, wholeness, and normal functioning. People who are greatly concerned about either aspect of their body image are vulnerable to poorer psychosocial adjustment when confronting treatment for breast cancer. The poorer adjustment takes a different form, however, depending on the nature of the patient's body-image concern.

Adaptation, Psychological↗