Bacteria and the Aging and Longevity of Caenorhabditis elegans

The molecular genetic analysis of longevity of Caenorhabditis elegans has yielded fundamental insights into evolutionarily conserved pathways and processes governing the physiology of aging. Recent studies suggest that interactions between C. elegans and its microbial environment may influence the aging and longevity of this simple host organism. Experimental evidence supports a role for bacteria in affecting longevity through distinct mechanisms—as a nutrient source, as a potential pathogen that induces double-edged innate immune and stress responses, and as a coevolved sensory stimulus that modulates neuronal signaling pathways regulating longevity. Motivating this review is the anticipation that the molecular genetic dissection of the integrated host immune, stress, and neuroendocrine responses to microbes in C. elegans will uncover basic insights into the cellular and organismal physiology that governs aging and longevity.National Institute of General Medical Sciences (U.S.)Ellison Medical Foundatio

Toward the development of a new multidimensional trust scale

This thesis comprises three main sections: a literature review, research report, and a critical appraisal of the research process. The literature reviewed is the existing research relating to trust as a construct. An attempt is made to clarify the conceptual confusion that exists in the area, by suggesting a comprehensive definition of what is meant by the term trust for the purposes of both the current study and future research. The importance of trust in relation to mental health and therapeutic relationships is discussed. Current measures of the construct are critically examined, and the ‘scientist’ versus ‘humanist’ divide is explored. It is concluded that a new multidimensional trust measure is required to further research efforts in the area. The aim of the research project was to develop a trust measure to form a part of a larger endeavour to operationalise the concept of mental health via key set of basic human emotions and responses. The research reported in Section 2 consists of a Pilot Test, Main Study, and follow up validation study of a new multidimensional measure of trust. Three bases of trust were hypothesised and tested. These were: self trust, interpersonal trust, and environmental trust (that is, trust in wider social, cultural, or political context). A new measure was constructed and validity tested using an inductive approach, and the relationship between trust and trait anxiety was also examined. The results supported the hypothesis that trust is a multidimensional construct, and demonstrated a strong relationship between trust and trait anxiety. It is hoped that this work will rekindle research interest in this important area. The final section is the researcher’s critical appraisal of the research process based on her personal research diary. It is a reflective piece that examines the impact of the research on the researcher (and vice versa) and the critical events in the research process.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Toward the development of a new multidimensional trust scale

This thesis comprises three main sections: a literature review, research report, and a critical appraisal of the research process. The literature reviewed is the existing research relating to trust as a construct. An attempt is made to clarify the conceptual confusion that exists in the area, by suggesting a comprehensive definition of what is meant by the term trust for the purposes of both the current study and future research. The importance of trust in relation to mental health and therapeutic relationships is discussed. Current measures of the construct are critically examined, and the ‘scientist’ versus ‘humanist’ divide is explored. It is concluded that a new multidimensional trust measure is required to further research efforts in the area. The aim of the research project was to develop a trust measure to form a part of a larger endeavour to operationalise the concept of mental health via key set of basic human emotions and responses. The research reported in Section 2 consists of a Pilot Test, Main Study, and follow up validation study of a new multidimensional measure of trust. Three bases of trust were hypothesised and tested. These were: self trust, interpersonal trust, and environmental trust (that is, trust in wider social, cultural, or political context). A new measure was constructed and validity tested using an inductive approach, and the relationship between trust and trait anxiety was also examined. The results supported the hypothesis that trust is a multidimensional construct, and demonstrated a strong relationship between trust and trait anxiety. It is hoped that this work will rekindle research interest in this important area. The final section is the researcher’s critical appraisal of the research process based on her personal research diary. It is a reflective piece that examines the impact of the research on the researcher (and vice versa) and the critical events in the research process.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Global Gene Expression of Prochlorococcus ecotypes in Response to Changes in Nitrogen Availability

Nitrogen (N) often limits biological productivity in the oceanic gyres where Prochlorococcus is the most abundant photosynthetic organism. The Prochlorococcus community is composed of strains, such as MED4 and MIT9313, that have different N utilization capabilities and that belong to ecotypes with different depth distributions. An interstrain comparison of how Prochlorococcus responds to changes in ambient nitrogen is thus central to understanding its ecology. We quantified changes in MED4 and MIT9313 global mRNA expression, chlorophyll fluorescence, and photosystem II photochemical efficiency (Fv/Fm) along a time series of increasing N starvation. In addition, the global expression of both strains growing in ammonium-replete medium was compared to expression during growth on alternative N sources. There were interstrain similarities in N regulation such as the activation of a putative NtcA regulon during N stress. There were also important differences between the strains such as in the expression patterns of carbon metabolism genes, suggesting that the two strains integrate N and C metabolism in fundamentally different ways

Cytogenetic analysis of posterior uveal melanoma

Cytogenetic analysis was performed on short-term cultures of primary tumor samples from seven patients with posterior uveal melanoma. Informative data were obtained from four patients, all of whom had a near-diploid chromosomal number and clonal chromosomal alterations. Analysis of one patient's tumor revealed monosomy 3 as the only cytogenetically distinguishable aberration. Trisomies of chromosome 8 and i(8)(q10) were detected in two other patients in combination with monosomy of chromosome 3. The fourth patient's karyotype displayed two different translocations. One translocation, der(6)t(6;8)(q12;q13.1), resulted in the over-representation of 8q13.1-->qter and a partial monosomy of 6q12-->qter; the other translocation, der(9)t(6;9)(p12;p23), produced a partial trisomy of 6p12-->pter and a partial monosomy of 9p23-->pter. These results support the view that the recurring pattern of chromosomal rearrangements in ocular melanoma is unique from that associated with cutaneous malignant melanoma. Furthermore, these results help confirm that chromosomes 3, 6, and 8 are nonrandomly altered in ocular melanoma.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30919/1/0000589.pd

On The Unusual Variability of 2MASS J06195260-2903592: A Long-Lived Disk around a Young Ultracool Dwarf

We present the characterization of the low-gravity M6 dwarf 2MASS J0619-2903 previously identified as an unusual field object based on its strong IR excess and variable near-IR spectrum. Multiple epochs of low-resolution (R~150) near-IR spectra show large-amplitude (~0.1-0.5 mag) continuum variations on timescales of days to 12 years, unlike the small-amplitude variability typical for field ultracool dwarfs. The variations between epochs are well-modeled as changes in the relative extinction ($\Delta{A_V}\approx2$ mag). Likewise, Pan-STARRS optical photometry varies on timescales as long as 11 years (and possibly as short as an hour) and implies similar amplitude $A_V$ changes. NEOWISE mid-IR light curves also suggest changes on 6-month timescales, with amplitudes consistent with the optical/near-IR extinction variations. However, near-IR spectra, near-IR photometry, and optical photometry obtained in the past year indicate the source can also be stable on hourly and monthly timescales. From comparison to objects of similar spectral type, the total extinction of 2MASS J0619-2903 seems to be $A_V\approx4-6$ mag, with perhaps epochs of lower extinction. Gaia EDR3 finds that 2MASS J0619-2903 has a wide-separation (1.2' = 10450 AU) stellar companion, with an isochronal age of $31^{+22}_{-10}$ Myr and a mass of $0.30^{+0.04}_{-0.03}$ Msun. Adopting this companion's age and EDR3 distance (145.2$\pm$0.6 pc), we estimate a mass of 0.11-0.17 Msun for 2MASS J0619-2903. Altogether, 2MASS J0619-2903 appears to possess an unusually long-lived primordial circumstellar disk, perhaps making it a more obscured analog to the "Peter Pan" disks found around a few M dwarfs in nearby young moving groups.Comment: AJ, in pres