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D L Beach

Publications and source records attributed to D L Beach.

12 recordsLinked to original sources
PubMed2001

ASH1 mRNA localization in three acts.

Novel green fluorescent protein (GFP) labeling techniques targeting specific mRNA transcripts reveal discrete phases of mRNA localization in yeast: packaging, transport, and docking. In budding yeast, ASH1 mRNA is translocated via actin and myosin to the tip of growing cells. A GFP-decorated reporter transcript containing the ASH1 3' untranslated region gRNA(ASH1) forms spots of fluorescence localized to a cortical domain at the bud tip, relocates to the mother-bud neck before cell separation, and finally migrates to the incipient bud site before the next budding cycle. The correct positioning of the mRNA requires at least six proteins: She1p-5p and Bud6p/Aip3p. gRNA(ASH1) localization in mutant strains identified three functional categories for the She proteins: mRNA particle formation (She2p and She4p), mRNA transport into the bud (She1p/Myo4p and She3p), and mRNA tethering at the bud tip (She5p/Bni1p and Bud6p/Aip3p). Because localization of the mRNA within the bud does not a priori restrict the translated protein, we examine the distribution of a mother-specific protein (Yta6p) translated from a mRNA directed into the bud. Yta6p remains associated with the mother cortex despite localization of the mRNA to the bud. This video essay traces the life history of a localized mRNA transcript, describes the roles of proteins required to polarize and anchor the mRNA, and demonstrates at least one instance where mRNA localization does not effect protein localization.

Biological Transport↗
PubMed2000

The role of the proteins Kar9 and Myo2 in orienting the mitotic spindle of budding yeast.

BACKGROUND: Two genetic 'pathways' contribute to the fidelity of nuclear segregation during the process of budding in the yeast Saccharomyces cerevisiae. An early pathway, involving Kar9p and other proteins, orients the mitotic spindle along the mother-bud axis. Upon the onset of anaphase, cytoplasmic dynein provides the motive force for nuclear movement into the bud. Loss of either pathway results in nuclear-migration defects; loss of both is lethal. Here, to visualize the functional steps leading to correct spindle orientation along the mother-bud axis, we imaged live yeast cells expressing Kar9p and dynein as green fluorescent protein fusions. RESULTS: Transport of Kar9p into the bud was found to require the myosin Myo2p. Kar9p interacted with microtubules through the microtubule-binding protein Bim1p and facilitated microtubule penetration into the bud. Once microtubules entered the bud, Kar9p provided a platform for microtubule capture at the bud cortex. Kar9p was also observed at sites of microtubule shortening in the bud, suggesting that Kar9p couples microtubule shortening to nuclear migration. CONCLUSIONS: Thus, Kar9p provides a key link between the actin cytoskeleton and microtubules early in the cell cycle. A cooperative mechanism between Kar9p and Myo2p facilitates the pre-anaphase orientation of the spindle. Later, Kar9p couples microtubule disassembly with nuclear migration.

Actins↗
PubMed1999

Localization and anchoring of mRNA in budding yeast.

BACKGROUND: Eukaryotic cells localize selected mRNAs to a region of the cell as a means to sequester proteins. Signals within the 3' untranslated region (3' UTR) facilitate mRNA localization by both actin and microtubule cytoskeletal systems. Recently, an mRNA in the yeast Saccharomyces cerevisiae, ASH1, was shown to coalesce into a discrete particle that is maintained at the bud tip. Mutations in five genes, SHE1-SHE5, cause defects in particle formation and/or localization of the ASH1 transcript. Factors at the destination of the mRNA transport remain to be identified. RESULTS: We have developed a system to label mRNA in living yeast with green fluorescent protein (GFP) and follow the dynamics of mRNA movement and localization. Constitutively expressing an ASH1 mRNA containing the bacteriophage MS2 coat-protein binding site adjacent to the ASH1 3' UTR allowed us to visualize ASH1 mRNA with an MS2-coat-protein-GFP fusion protein (together denoted 'gRNAASH1'). The gRNAASH1 was restricted to the bud tip in small to large budded cells, migrated to the bud neck prior to cell separation and then rapidly relocalized to the incipient site of bud growth. It also localized to regions of polarized growth during mating. In cells lacking Bud6p/Aip3p or Bnilp/She5p, which are involved in polarity establishment and actin organization, gRNAASH1 migrated to the bud but failed to remain at the bud tip. These studies reveal discrete transport and anchoring steps in mRNA localization. CONCLUSIONS: The ASH1 mRNA was maintained at sites of polarized growth throughout the vegetative and mating cell cycles. Bud6p/Aip3p and Bni1p/She5p are required to maintain the transcript at the cortical bud cap.

DNA-Binding Proteins↗
PubMed1999

mRNA localization: motile RNA, asymmetric anchors.

Techniques to label mRNA with green fluorescent protein (GFP) have provided the first real-time images of RNA motility in live yeast cells. Genetic screens for factors responsible for mRNA asymmetry (e. g. SHE genes) in yeast identified type V myosin among other proteins. Analysis of mRNA movement in various she mutants revealed the role of motor proteins in long-range transport, factors for particle formation, and cortical anchors for docking the mRNA.

Cytoskeleton↗
PubMed1998

Effects of 15-oxa-32-vinyl-lanost-8-ene-3 beta,32 diol on the expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase and low density lipoprotein receptor in rat liver.

The mechanisms by which oxylanosterols regulate expression of hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and lower serum cholesterol levels were examined by using a novel nonmetabolizable oxylanosterol mimic, 15-oxa-32-vinyl-lanost-8-ene-3 beta, 32 diol (DMP 565). This compound, unlike other nonmetabolizable oxylanosterols, is not a substrate for lanosterol 14 alpha-methyl demethylase. Feeding rats a diet supplemented with 0.02% DMP 565 markedly decreased HMG-CoA reductase immunoreactive protein and enzyme activity levels without affecting mRNA levels. The rate of reductase protein degradation was unaffected. However, the rate of translation was reduced to less than 20% of control. Thus, DMP 565 appears to regulate hepatic HMG-CoA reductase gene expression primarily at the level of translation. The pronounced inhibition of HMG-CoA reductase by DMP 565 resulted in a compensatory increase in the functioning of the hepatic low density lipoprotein (LDL) receptor, possibly by increased cycling, as evidenced by a marked increase in the rate of degradation of the LDL receptor. The half-life of the receptor was decreased from over 7 h to only 1 h in animals receiving DMP 565. This increase in the rate of degradation occurred without a change in the steady state level of the receptor. Addition of dietary cholesterol attenuated the increased turnover of the LDL receptor. These effects on the hepatic LDL receptor have also been observed with HMG-CoA reductase inhibitors (G. C. Ness et al., 1996, Arch. Biochem, Biophys. 325, 242-248). However, the effect of DMP 565 on the rate of degradation of the hepatic LDL receptor was of a greater magnitude when equal doses of the drugs were used. These regulatory actions of DMP 565 provide, in part, an explanation for the observed hypocholesterolemic action of this compound.

Administration, Oral↗
PubMed1997

Family caregiving: the positive impact on adolescent relationships.

Adult children are a significant contingent of elder care providers; a number of these individuals simultaneously care for children of their own while coping with caregiving commitments. Unfortunately, there is a paucity of information regarding the caregiving impact on these children and young adults. Moreover, the possible positive consequences of caring for an impaired elder are rarely mentioned. The current study was undertaken to examine the potential positive caregiving experiences of adolescents and their perceptions of relational enhancement as a result of caregiving. Twenty adolescents aged 14-18 were interviewed and asked a series of semistructured questions concerning satisfaction related to caregiving. To be included, respondents had to be a child, grandchild, or niece/nephew of an Alzheimer's (or Alzheimer's Type Dementia) patient cared for by the adolescent's immediate family. Employing features of content analysis methodology, all interviews were audiotaped and transcribed verbatim. The results merged into four primary categories: 1) increased sibling activity/sharing; 2) greater empathy for older adults; 3) significant mother-adolescent bonding and 4) peer relationship selection and maintenance. The implications for future research and practice are discussed.

Adaptation, Psychological↗
PubMed1995

Caregiver discourse: perceptions of illness-related dialogue.

Interacting with terminally-ill patients is significantly stressful for caregiving families. To date, few studies have examined how caregivers perceive their communication with dying family members. As such, the present investigation was undertaken. A sample of 10 family caregivers was utilized for the study; informants had to be the spouse or child of the patient, having provided the majority of care during the illness period. Semi-structured interviews were employed by the investigator to collect data on the communicative experiences of these caregivers; they were asked to describe their thoughts and interactional experiences with specific reference to the following: (1) the inevitability of the patient's death, (2) the patient's preferred courses of action, (3) levels of family interaction, (4) patient denial, (5) previous patterns of discourse, and (6) bereavement. All interviews were audio-recorded, transcribed verbatim, and analyzed using a two-tier system incorporating aspects of content analysis methodology. Results indicate that caregivers experience difficulty communicating with their patients and with other family members. Suggestions for developing effective, appropriate, and sensitive communication training programs for terminally-ill patients and their caregiving families are provided.

Aged↗
PubMed1994

Selective expression of cytochrome P450 CYP3A mRNAs in embryonic and adult human liver.

The human CYP3A P450 family, composed of at least four highly homologous genes, is expressed prominently in the liver. To investigate the expression of CYP3A family members individually, we prepared oligonucleotides specific for each CYP3A mRNA and used Northern blot analysis and/or polymerase chain reaction to examine RNA from adult and fetal liver for variation in expression of the CYP3A forms during development. We found that CYP3A4 (P450NF) mRNA, was only detectable by Northern blot postnatally, was highly variable (10-fold) among the adult samples, and, unlike its rat counterparts (CYP3A1/2), was not influenced by gender. In contrast, CYP3A7 (HFLa) mRNA, a form previously thought to be confined to fetal liver, was found in all tested samples of fetal liver as well as in seven of 13 adult livers (54%). CYP3A5 (HLp2), an mRNA also found in all the fetal samples, was detected in three of these 13 adults (23%) and two of these three co-expressed CYP3A7 mRNA. CYP3A5 and CYP3A7 are expressed at similar levels in fetal liver from either gender. Moreover, CYP3A7 expression in fetal liver appears less variable (< 2.5-fold) than CYP3A4 in adults. We conclude, that contrary to prevailing views, expression of CYP3A7 in the liver is not restricted to the fetus but rather represents a second CYP3A form selectively expressed in adults.

Adult↗
PubMed1993

Gerontological caregiving: analysis of family experience.

1. Regardless of gender, caregivers readily relinquish personal activities in order to perform caregiving tasks. 2. Caregivers seldom solicit assistance from other family members. 3. Caregivers experience difficulty balancing caregiving with outside employment and significantly reduce work hours or cease employment altogether.

Aged↗
PubMed1990

The effects of social demand on breast self-examination self-report.

The measurement of breast self-examination (BSE) adherence typically relies on verbal self-report. These studies systematically manipulated social demand within a face-to-face interview and examined the effects on self-reported BSE frequency. In Study 1, subjects (n = 37) received either a high-demand or a low-demand preface prior to being asked about BSE practice over the past year. Study 2 (n = 89) was a replication, with the addition of a no-preface (control) condition. Results from Study 1 indicated that although the conditions were comparable on demographic and breast cancer/BSE knowledge variables, the high-demand condition reported a significantly higher number of BSEs than the low-demand condition. An attenuation of this pattern was found in Study 2, with the control condition reporting a frequency between the low demand's and the high demand's reported frequencies. The implications for BSE intervention and prevalence research are discussed.

Adult↗
PubMedDate not supplied

The effects of co-worker-delivered prompts on breast self-examination frequency.

In this study, we evaluated the efficacy of co-worker-delivered reminders to perform breast self-examination (BSE). Before participating in a BSE training workshop, subjects (n = 36) were randomly assigned in pairs (of co-workers who registered together) to one of two experimental conditions: contract or control. Subjects in the contract condition, after discussing specific prompting strategies as part of a "buddy system" in their workshop, contracted to prompt their designated peers at least once a month for six months following the workshop. In addition, subjects in both conditions received mailed prompts monthly. We assessed BSE adherence and prompting behaviors in retrospective interviews. Results indicated that subjects in both conditions significantly increased BSE frequency above pre-workshop levels. However, the magnitude of this increase did not differ between conditions. A process evaluation indicated that the control group pairs were similar to the contract group pairs in their prompting behavior.

Adult↗