Phenomic and Genetic Controls of the Drought Stress Response in Sorghum

Drought, one of the most common abiotic stressors, is a result of the precipitation and temperature fluctuations influenced by climate change. As consistent weather patterns are crucial for the maintenance of crop yield, drought threatens food security through its impact on plant growth and development. It is essential to ensure the quality, availability, and affordability of grain-based products in the face of climate change due to expectations of population growth. Therefore, shedding light on the mechanisms associated with drought tolerance is integral to maintaining agricultural production under water-limited conditions. My dissertation work aimed to uncover the morphological, physiological, and genetic controls of drought resistance in Sorghum, a C4 grain crop grown for food, feed, and biofuel. In Chapter 3, two Sorghum bicolor accessions that differ in their pre-flowering responses to drought were evaluated following long-term drought exposure across juvenile and adult vegetative stages. Findings from this work emphasized accession-specific responses to drought, indicating that morphological/histological and physiological strategies both play roles in promoting hydraulic safety in response to drought, and these mechanisms may be mutually exclusive. Chapter 4 expanded upon the findings of Chapter 3 by uncovering the evolutionary origins of the morphological and physiological responses associated with drought exposure. Using quantitative trait loci (QTL) mapping in a Sorghum recombinant inbred line (RIL) population, eight QTL unique for drought exposure were detected. S. bicolor alleles controlled reductions in height and enhanced aboveground biomass, emphasizing the impact of grain Sorghum varieties (i.e. TX7000) on drought-responsive phenotypes. These biological impacts may be influenced by the candidate genes with these QTL, specifically those involved in reproductive processes. These gene products facilitate grain production and may promote early flowering, a common drought escape mechanism that influences the transition into reproduction before stress becomes too severe. Physiologically, S. bicolor alleles increased leaf temperature while Sorghum propinquum alleles increased relative water content; these species-specific strategies reflect their variable belowground growth and impact of domestication on drought-responsive phenotypes. The QTL detected for relative water content and leaf temperature contained genes involved in auxin and abscisic acid (ABA) synthesis and signaling. In addition to playing roles in root development and water uptake, phytohormones can also affect aboveground responses, such as growth and stomatal closure. Therefore, our findings highlight the contribution of plant hormones to root-to-shoot communication and water uptake and loss through both above- and belowground strategies. The relationship between above- and belowground responses and hormone signaling was explored further in Chapter 5. Using the same Sorghum RIL population, five QTL for belowground responses to drought exposure were identified. Three of these QTL co-localized on chromosome four and with a root biomass QTL detected in this same population evaluated under salinity stress, suggesting shared genetic control of belowground traits under osmotic stress. Further, these traits were all controlled by S. bicolor alleles. This control demonstrated that root system architecture is reorganized under osmotic stress by the domesticated parent to favor vertical growth while also increasing root biomass, suggesting a main goal of enhanced water uptake in the osmotic stress response. Candidate genes within these QTL were associated with root development and hormone synthesis/recognition, contributing additional support to the allelic effects described in this work, as well as to the role of water acquisition described in Chapter 4. Genes within the two remaining QTL detected in the drought population were also involved in plant hormone responses, specifically abscisic acid (ABA). Genes encoding pentatricopeptide repeat (PPR)-containing proteins and Late Embryogenesis Abundant- like (LEA) proteins were identified in these regions. PPR’s have established roles in ABA signaling in Arabidopsis and were also shown to be up-regulated in response to heat and drought stress in Sorghum. Further, LEA proteins are induced upon ABA and osmotic stress exposure, and function as molecular chaperones. Altogether, these findings further highlight the contribution of phytohormones in drought resistance, particularly through intricate signal cascades that influence plant functioning under drought, at the morphological, physiological, and molecular levels

C-reactive protein, interleukin-6, and prostate cancer risk in men aged 65 years and older.

Inflammation is believed to play a role in prostate cancer (PCa) etiology, but it is unclear whether inflammatory markers C-reactive protein (CRP) and interleukin-6 (IL-6) associate with PCa risk in older men. Using Cox regression, we assessed the relationship between baseline concentrations of CRP and IL-6 and the subsequent PCa risk in the Cardiovascular Health Study, a population-based cohort study of mostly European American men of ages >64 years (n = 2,234; mean follow-up = 8.7 years; 215 incident PCa cases). We also tested associations between CRP and IL-6 tagSNPs and PCa risk, focusing on SNPs that are known to associate with circulating CRP and/or IL-6. Neither CRP nor IL-6 blood concentrations was associated with PCa risk. The C allele of IL-6 SNP rs1800795 (-174), a known functional variant, was associated with increased risk in a dominant model (HR = 1.44; 95% CI = 1.03-2.01; p = 0.03), but was not statistically significant after accounting for multiple tests (permutation p = 0.21). Our results suggest that circulating CRP and IL-6 do not influence PCa risk. SNPs at the CRP locus are not associated with PCa risk in this cohort, while the association between rs1800795 and PCa risk warrants further investigation

Population-based estimates of the relation between breast cancer risk, tumor subtype, and family history.

OBJECTIVE: Many studies that have estimated the breast cancer risk attributable to family history have been based on data collected within family units. Use of this study design has likely overestimated risks for the general population. We provide population-based estimates of breast cancer risk and different tumor subtypes in relation to the degree, number, and age at diagnosis of affected relatives. METHODS: Cox Proportional Hazards to calculate risks (hazard ratios; 95% confidence interval) of breast cancer and tumor subtypes for women with a family history of breast cancer relative to women without a family history among a cohort of 75,189 women age >or=40 years of whom 1,087 were diagnosed with breast cancer from June 1, 2001-December 31, 2005 (median follow-up 3.16 years). RESULTS: Breast cancer risk was highest for women with a first-degree family history (1.54; 1.34-1.77); and did not differ substantially by the affected relative's age at diagnosis or by number of affected first-degree relatives. A second-degree family history only was not associated with a significantly increased breast cancer risk (1.15; 0.98-1.35). There was a suggestion that a positive family history was associated with risk of triple positive (Estrogen+/Progesterone+/HER2+) and HER2-overexpressing tumors. CONCLUSIONS: While a family history of breast cancer in first-degree relatives is an important risk factor for breast cancer, gathering information such as the age at diagnosis of affected relatives or information on second-degree relative history may be unnecessary in assessing personal breast cancer risk among women age >or=40 years

Die Einstellungs-Verhaltens-Relation : Eine verhaltenswissenschaftliche Untersuchung am Beispiel von ökologischen Lebensmitteln

A new imaging contrast agent is reported that provides an increased fluorescent signal upon application of ultrasound (US). Liposomes containing lipids labelled with pyrene were optically excited and the excimer fluorescence emission intensity was detected in the absence and presence of an ultrasound field using an acousto-fluorescence setup. The acousto-fluorescence dynamics of liposomes containing lipids with pyrene labelled on the fatty acid tail group (PyPC) and the head group (PyPE) were compared. An increase in excimer emission intensity following exposure to US was observed for both cases studied. The increased intensity and time constants were found to be different for the PyPC and PyPE systems, and dependent on the applied US pressure and exposure time. The greatest change in fluorescence intensity (130%) and smallest rise time constant (0.33 s) are achieved through the use of PyPC labelled liposomes. The mechanism underlying the observed increase of the excimer emission intensity in PyPC labelled liposomes is proposed to arise from the “wagging” of acyl chains which involves fast response and requires lower US pressure. This is accompanied by increased lipid lateral diffusivity at higher ultrasound pressures, a mechanism that is also active in the PyPE labelled liposomes