The trade-off between egg size and fecundity in the bruchid beetle Callosobruchus maculatus : a quantitative genetic approach.

Female Callosobruchus maculatus have fixed reproductive resources to allocate to offspring. It is predicted that the option of investing in a few large eggs or many small eggs will result in a trade-off between egg size and fecundity in this species. The aim of this study was to examine this proposed trade-off and obtain empirical evidence for its significance in the life history of C. maculatus. Breeding and selection experiments were used to measure the genetic correlation between egg size and fecundity as evidence for the existence of the trade-off. Selection experiments also allowed egg size to be manipulated to investigate its intrinsic effects on offspring fitness. Chapter 1 introduces life history theory and trade-off from the distinct but complementary perspectives of optimality theory and evolutionary genetics. Empirical methods that can be used to measure trade-offs are evaluated with respect to the egg size versus fecundity trade-off and the biology of C. maculatus. In Chapter 2 the general experimental methods are described. Phenotypic correlations involving egg size, fecundity and other life history traits are measured in Chapter 3. Egg size is not phenotypically correlated with fecundity but varies with maternal emergence weight and age. Correlative effects of egg size on offspring fitness appear to be due to effects on offspring body weight and development rate. The presence of genetic variation in egg size and fecundity are demonstrated in Chapter 4. In Chapter 5 the genetic correlation between egg size and fecundity is measured by means of a half sib breeding experiment. A negative genetic correlation of low precision was obtained. Chapter 6 provides a second estimate of the genetic correlation from an experiment in which egg size was increased and decreased by artificial selection. The correlated response in fecundity was downwards in both directions of selection which was not consistent with the proposed trade-off. The genetic correlation estimated was positive. Reasons for the unexpected response are discussed. The effects of selection for egg size on other life history traits is examined in Chapter 7. Only development rate, fecundity and emergence weight in females had changed after selection. Chapter 8 discusses what the quantitative experiments have revealed about the trade-off between egg size and fecundity and assesses the merits of the methodologies

Delayed return of bowel function after general surgery in South Australia

Introduction: Reference ranges for determining pathological versus normal postoperative return of bowel function are not well characterised for general surgery patients. This study aimed to characterise time to first postoperative passage of stool after general surgery; determine associations between clinical factors and delayed time to first postoperative stool; and evaluate the association between delay to first postoperative stool and prolonged length of hospital stay. Methods: This study included consecutive admissions at two tertiary hospitals across a two-year period whom underwent a range of general surgery operations. Multivariable logistic regression analyses were conducted to determine associations between the explanatory variables and delayed first postoperative stool, and between delayed first postoperative stool and length of hospital stay. The previously specified explanatory variables were used, with the addition of the dichotomised ≥4-day delay to first postoperative stool. Prolonged length of hospital stay was considered ≥7 days. Results: 2,212 general surgery patients were included. Median time to first postoperative stool was 2.28 (IQR 1.06–3.96). Median length of stay was 7.19 (IQR 4.50–12.01). Several operative characteristics and medication exposures were associated with delayed first postoperative stool. There was a statistically significant association between delayed first postoperative stool (≥4 days) and prolonged length of stay (≥7 days) (OR 4.34, 95 %CI 3.27 to 5.77, p < 0.001). Conclusions: This study characterised expected reference ranges for time to return of bowel function across various general surgery operations and determined associations with clinical factors that may improve efficiency and identification of pathology within the postoperative course

Castor Bean Metabolomics: Current Knowledge and Perspectives Toward Understanding of Plant Plasticity Under Stress Condition

Metabolomics provides vital information for the understanding of biological processes and has been vastly applied in plant studies. Several metabolite-profiling studies have correlated physiological events, such as germination or seedling establishment, with metabolic and molecular changes under different environmental conditions. Castor bean displays high plasticity during initial vegetative growth, which is reflected in the metabolome of the seeds and seedlings. In general, several metabolite-profiling techniques are required to obtain a complete response in terms of metabolism plasticity of the studied biological system. Carbohydrates, amino acids, and organic acids have been measured in castor bean seeds and seedlings by nuclear magnetic resonance, gas chromatography coupled to a quadrupole time of flight mass spectrometry (GC-TOF-MS), as well as by high-performance liquid chromatography (HPLC). Fatty acids and some secondary metabolites have been quantified in castor bean seeds and seedlings by gas chromatography coupled to a triple-axis detector (GC-MS). In this chapter, we initially discuss how metabolomics studies suggested a possible role of gamma-aminobutyric acid (GABA) accumulation during early imbibitions and seedling establishment. Later, we consider a specific metabolic signature of castor bean: a shift in carbon–nitrogen metabolism as its main biochemical response to high temperatures. This metabolic shift is usually associated with adjusted growth, and it is likely involved in maintaining cellular homeostasis under heat stress. The castor bean metabolome has been vastly investigated, especially with regard to its ability to respond to external stimuli. These results might help us understand the molecular requirements for vigorous castor bean seed germination and seedling growth under different environmental conditions