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Energy Shortages (energy + shortage)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Size-Dependent Mating Success at Various Nutritional States in the Yellow Dung Fly

ETHOLOGY, Issue 8 2008
Wolf U. Blanckenhorn
Mating success not only depends on genetic quality, but also equally on environmental factors, most prominently food availability. We investigated the interactive effects of nutritional state and body size on mating success and copula duration in yellow dung fly males (Scathophaga stercoraria; Diptera: Scathophagidae) of three body size selection lines in the laboratory in both non-competitive (single) and competitive (group) situations. Adults require protein and lipids from prey to reproduce, as well as sugars as an energy source for reproductive activity. We expected mating success to decrease with time because of sperm depletion (sugar treatment) and/or energy shortage (water treatment) relative to the control, prey plus sugar treatment. Based on physiological scaling, we also expected large-line males to become depleted either sooner because of their higher energy and sperm demands, or later because of their more efficient energy use. Average mating success indeed declined over a period of 5,7 d (or 5,15 potential copulations per male), but equally for all food treatments and body size classes. Surprisingly, water-fed and small-line males had the highest mating probability in the non-competitive setting, while in the competitive setting large-line males had the highest success. Energy-depleted males showed apparent terminal investment. Small males acquired females more readily but eventually lost them to larger males in the competitive situation. As shown before, copula duration was inversely related to body size and increased with copulation number, independent of food treatment. We conclude that sugar or prey shortage has little effect on mating success in the short term, and does not differentially affect males of different sizes. [source]

Prospects and Challenges for Growth and Poverty Reduction in Asia

DEVELOPMENT POLICY REVIEW, Issue 2006
John Humphrey
The extent of poverty reduction in Asia by 2015 will depend upon two linked issues: sustaining the current rates of economic growth and avoiding increases in income inequality. Rapid growth over the past 15 years has itself created three challenges for its continuation: inadequate infrastructure; energy shortages and insecurity; and depletion of natural resources and environmental degradation. The ways in which these problems are addressed will have impacts not only on growth but also on inequality, requiring policy interventions at multiple levels, having implications for governance at multiple levels, and involving the development of new partnerships within the region and beyond. [source]

A comparative proteomic approach to understand the adaptations of an H+ -ATPase-defective mutant of Corynebacterium glutamicum ATCC14067 to energy deficiencies

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 18 2007
Liyuan Li
Abstract F172-8, an H+ -ATPase-defective mutant of the glutamic acid-producing bacterium Corynebacterium glutamicum ATCC 14067, exhibits enhanced rates of glucose consumption and respiration compared to the parental strain when cultured in a biotin-rich medium with glucose as the carbon source. We conducted a comparative proteomic analysis to clarify the mechanism by which the enhanced glucose metabolism in this mutant is established using a proteome reference map for strain ATCC 14067. A comparison of the proteomes of the two strains revealed the up-regulated expression of the several important enzymes such as pyruvate kinase (Pyk), malate:quinone oxidoreductase (Mqo), and malate dehydrogenase (Mdh) in the mutant. Because Pyk activates glycolysis in response to cellular energy shortages in this bacterium, its increased expression may contribute to the enhanced glucose metabolism of the mutant. A unique reoxidation system has been suggested for NADH in C. glutamicum consisting of coupled reactions between Mqo and Mdh, together with the respiratory chain; therefore, the enhanced expression of both enzymes might contribute to the reoxidation of NADH during increased respiration. The proteomic analysis allowed the identification of unique physiological changes associated with the H+ -ATPase defect in F172-8 and contributed to the understanding of the adaptations of C. glutamicum to energy deficiencies. [source]

Testosterone and energetics in wild chimpanzees (Pan troglodytes schweinfurthii)

AMERICAN JOURNAL OF PRIMATOLOGY, Issue 2 2005
Martin N. Muller
Abstract Ovarian function in female hominoids is sensitive to both energy flux and energy balance, resulting in a reduced probability of conception during periods when a successful reproductive outcome is less likely. However, the extent to which energetic factors constrain gonadal function in male hominoids is not clear. We examined the effects of both acute and chronic variation in energy availability on urinary testosterone (T) levels in adult male chimpanzees. Acute changes in energy availability, which were assayed by means of observational data on feeding behavior, did not result in decreased T production for 11 individuals at Kibale National Park, Uganda. Chronic energy shortages, on the other hand, may be associated with lower T levels in this population. Adult males in Kibale (n=11), who maintain suboptimal access to energy, exhibit significantly lower urinary T levels than males in captivity (n=11), who are more sedentary and better fed. These results suggest that data on hormonal function in captive chimpanzees should be interpreted with caution because individuals may produce T at levels well above those that are typical in the wild. They also suggest that short-term variations in T levels in male hominoids are more likely to be explained by social factors than by energetic ones. Am. J. Primatol. 66:119,130, 2005. © 2005 Wiley-Liss, Inc. [source]