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- 저자 : Jang Taehwan (검색결과 62 건)
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The effects of temperature on starvation resistance are context dependent in Drosophila melanogaster
Taehwan Jang,Kwang Pum Lee 한국응용곤충학회 2018 한국응용곤충학회 학술대회논문집 Vol.2018 No.04
Temperature can modulate how insects respond to environmental stressors, such as starvation. In this study, we examine whether and how the effects of temperature on starvation resistance depend on nutritional condition and developmental stages in Drosophila melanogaster. Starvation resistance decreased as the temperature exposed during starvation rose from 18 to 28 ̊C, which was mainly caused by warming-induced increase in energy expenditure. When exposed to warm temperatures during feeding, D. melanogaster accumulated more energy reserves and thus become more starvation resistant. The temperature experienced during the larval stage also had a significant effect on starvation resistance at adult stages, with those larvae raised at cold temperatures developing into adult phenotypes with reduced resistance to starvation. This study suggests that the effects of temperature on starvation resistance are highly complex and context dependent in D. melanogaster.
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The Effects of Mating on Starvation Resistance in Drosophila melanogaster
Taehwan Jang,Kwang Pum Lee 한국응용곤충학회 2014 한국응용곤충학회 학술대회논문집 Vol.2014 No.10
Mating elicits a dramatic changes in physiology, behavior, and life-history traits in insects, but little is known about the relationship between mating and the capacity of insects to resist environmental stressors. Starvation is one of the most ubiquitous forms of environmental stress faced by all insects under natural conditions. Previous studies using Drosophila melanogaster flies has shown that mated females lived longer under starvation than did virgin females, but the mechanistic basis for such post-mating increase in starvation resistance remains largely unexplored. The objective of this study was to investigate the behavioral and physiological mechanisms of mating-induced alteration in starvation resistance and its heritable genetic variations in D. melanogaster. In the first experiment (Experiment 1), we compared starvation resistance (measured as starving time before death), body compositions, and food intake between mated and unmated flies of both sexes using a large outbred population. In the second experiment (Experiment 2), starvation resistance and body composition were quantified for mated male and female flies derived from each of 19 highly inbred genetic lines. Results from Experiment 1 showed that mated females were better able to resist starvation than virgin females and males because they ate more and thus laid down more fats in their body. Results from Experiment 2 revealed a significant heritable genetic variation in starvation resistance and its correlated body composition parameters for both sexes. Overall, females had a higher starvation resistance than males, but the magnitude of such intersexual difference varied among genetic lines, as suggested by a significant sex-by-line interaction. Cross-sex genetic correlations were highly significant and positive for starvation resistance, indicating that the genetic factors controlling the starvation resistance in D. melanogaster are shared between the two sexes.
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Genotype by Nutrient Interactions for Starvation Resistance in Drosophila melanogaster
Taehwan Jang,Kwang Pum Lee 한국응용곤충학회 2014 한국응용곤충학회 학술대회논문집 Vol.2014 No.04
Starvation resistance is an important fitness trait that is controlled by both environmental and heritable factors. The main objective of this study is to explore the genotype-by-nutrient interactions for starvation resistance and its correlating physiological traits in Drosophila melanogaster. In this study, we conducted a split-family quantitative genetic experiment, in which female adults of Drosophila from 19 isofemale genetic lines were allowed to ingest one of two synthetic diets that differed in protein-to-carbohydrate ratio (P:C = 4:1 or 1:16 with the P+C concentration of 120 g L-1) before they were assayed for starvation time and lipid storage. In all genetic lines, Drosophila flies that had fed carbohydrate-rich diet (P:C=1:16) resisted starvation better and stored more lipids than did those that had fed protein-rich diet (4:1). Importantly, the extent to which both starvation resistance and lipid reserves were affected by dietary P:C ratio varied greatly among different genetic lines of Drosophila, as indicated by significant genotypeby-nutrient interactions for these two traits. When the patterns of the bivariate reaction norm for body lipid and starvation resistance were compared across the genotypes, we found strong evidence for genetic variations in the pattern of energy storage and usage associated with maintaining survival under starvation in Drosophila.
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Nutritional effects on starvation resistance in Drosophila melanogaster
Taehwan Jang,Kwang Pum Lee 한국응용곤충학회 2013 한국응용곤충학회 학술대회논문집 Vol.2013 No.10
Food limitation is the most common environmental challenge faced by animals and the capacity of animals to survive prolonged periods of starvation is linked to their diet and nutritional status. The objective of this study is to investigate the effects of nutrition on starvation resistance in Drosophila melanogaster. Experimental flies were given ad libitum access to artificial diets differing in concentrations and ratios of protein and carbohydrate for 5 days before they were assayed for starvation time, body composition and life-history parameters. Starvation resistance in Drosophila was greatly influenced by the dietary protein:carbohydrate (P:C) ratio, but neither by the caloric content of the diet nor by dietary carbohydrate alone. Starvation resistance was strongest at the lowest P:C ratio and declined with rising P:C ratio. While starving, Drosophila underwent a dramatic transition in the utilization of physiological fuels, switching from the early phase characterized by preferential consumption of non-lipid substrates to the next phase in which they began to mobilize lipids as fuels for enduring starvation. Our results highlight the importance of nutrition as a key factor determining starvation responses of Drosophila.
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Taehwan Jang,Myung Suk Rho,Kwang Pum Lee 한국응용곤충학회 2015 한국응용곤충학회 학술대회논문집 Vol.2015 No.10
Macronutrient balance has a strong influence on fitness in insects. Previous studies have revealed that altering the concentrations of yeast and sugar in the semi-synthetic diet has a profound impact on lifespan and fecundity in Drosophila melanogaster, indicating the role of dietary protein:carbohydrate (P:C) balance in determining these two key components of fitness. However, since yeast contains not only proteins but also other macro- and micronutrients, this lifespan-determining role of dietary P:C balance needs to be corroborated using a chemically defined diet. In this study, the effects of dietary P:C balance on lifespan and fecundity were investigated in female D. melanogaster flies on one of eight isocaloric synthetic diets differing in P:C ratio (0:1, 1:16, 1:8, 1:4, 1:2, 1:1, 2:1 or 4:1). Lifespan and dietary P:C ratio were related in a convex manner, with lifespan increasing to a peak at the two intermediate P:C ratios (1:2 and 1:4) and falling at the imbalanced ratios (0:1 and 4:1). Ingesting nutritionally imbalanced diets caused flies to start ageing earlier and senesce faster. Egg production increased progressively as the dietary P:C ratio rose from 0:1 to 4:1. Long-lived flies at the intermediate P:C ratios(1:2 and 1:4) stored a greater amount of lipids than those short-lived ones at the two imbalanced ratios (0:1 and 4:1). These findings provide a strong support to the notion that dietary P:C balance is a critical determinant of lifespan and fecundity in D. melanogaster.
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Taehwan Jang,Kwang Pum Lee 한국응용곤충학회 2018 한국응용곤충학회 학술대회논문집 Vol.2018 No.04
Protein and carbohydrate are two major macronutrients that exert profound influences over fitness in many insects, including Drosophila melanogaster. Until recently, most studies examining the impacts of these macronutrients on various life-history traits in this species have used semi-synthetic diets that are not nutritionally well-defined. Here we used chemically defined diets to examine the patterns of larval and adult traits expressed across 34 diets systematically varying in the ratio and concentration of protein and carbohydrate. The shapes of the nutritional landscapes plotted for all larval and adult traits differed significantly from one another. Diverging nutritional optima identified for these landscapes suggest that D. melanogaster cannot maximize the expression of all life-history traits simultaneously, thus leading them to face a nutrient-dependent life-history trade-off.
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Temperature-dependence of starvation resistance in Drosophila melanogaster
Taehwan Jang,Keonhee Kim,Kun Kim,Kwang Pum Lee 한국응용곤충학회 2017 한국응용곤충학회 학술대회논문집 Vol.2017 No.10
Temperature can affect the ability of insects to tolerate prolonged period of food deprivation through altering the amountof energy storage, the speed of energy expenditure, or the threshold energy storage for survival. In this study, we examinedthe mechanistic basis of the temperature-dependence of starvation resistance in Drosophila melanogaster. Starvation resistancedecreased as the temperature experienced during starvation rose from 18 to 28 ̊C. This warming-mediated decrease instarvation resistance was due to accelerated energy expenditure. However, the threshold energy storage for survival wasnot affected by starvation temperature. Exposure to warm temperatures during feeding led D. melanogaster to accumulatemore energy reserves and thus to become more starvation resistant. This study highlights the important role played bytemperature in shaping the phenotypic responses of insects to starvation.
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Jang, Taehwan,Lee, Kwang Pum The Company of Biologists Limited 2018 The Journal of experimental biology Vol.221 No.21
<P>Protein and carbohydrate are the two major macronutrients that exert profound influences over fitness in many organisms, including <I>Drosophila melanogaster.</I> Our understanding of how these macronutrients shape the components of fitness in <I>D. melanogaster</I> has been greatly enhanced by the use of nutritional geometry, but most nutritional geometric analyses on this species have been conducted using semi-synthetic diets that are not chemically well defined. Here, we combined the use of nutritional geometry and chemically defined diets to compare the patterns of larval and adult life-history traits expressed across 34 diets systematically varying in protein:carbohydrate (P:C) ratio and in protein plus carbohydrate (P+C) concentration. The shape of the response surfaces constructed for all larval and adult traits differed significantly from one another, with the nutritional optima being identified at P:C 1:4 for lifespan (P+C 120 g l<SUP>−1</SUP>), 1:2 for egg-to-adult viability (120 g l<SUP>−1</SUP>), 1:1 for female body mass at adult eclosion (240 g l<SUP>−1</SUP>) and lifetime fecundity (360 g l<SUP>−1</SUP>), 2:1 for larval developmental rate (60 g l<SUP>−1</SUP>) and 8:1 for egg production rate (120 g l<SUP>−1</SUP>). Such divergence in nutritional optima among life-history traits indicates that <I>D. melanogaster</I> confined to a single diet cannot maximize the expression of these traits simultaneously and thus may face a life-history trade-off. Our data provide the most comprehensive and nutritionally explicit analysis of the impacts of macronutrients on life-history traits in <I>D. melanogaster</I> and support the emerging notion that the fundamental trade-offs among life-history traits are mediated by macronutrients.</P><P><B>Summary:</B> Nutritional optima diverge among various life-history traits expressed at larval and adult stages in fruit flies, providing evidence for nutrient-mediated life-history trade-offs.</P>
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Taehwan Jang,Kwang Pum Lee 한국응용곤충학회 2015 한국응용곤충학회 학술대회논문집 Vol.2015 No.10
Recent studies have shown that mating can alter starvation resistance in female D. melanogaster, but little is known about the behavioral and physiological mechanisms underlying such mating-mediated changes in starvation resistance. In the present study, we first investigated whether the effect of mating on starvation resistance is sex-specific in D. melanogaster. As indicated by a significant sex × mating status interaction, mating increased starvation resistance in females but not in males. In female D. melanogaster, post-mating increase in starvation resistance was mainly attributed to increases in food intake and in the level of lipid storage relative to lean body weight. We then performed quantitative genetic analysis to estimate the proportion of the total phenotypic variance attributable to genetic differences (i.e., heritability) for starvation resistance in mated male and female D. melanogaster. The narrow-sense heritability (h2) of starvation resistance was 0.235 and 0.155 for males and females, respectively. Mated females were generally more resistant to starvation than males, but the degree of such sexual dimorphism varied substantially among genotypes, as indicated by a significant sex × genotype interaction for starvation resistance. Cross-sex genetic correlation was greater than 0 but less than l for starvation resistance, implying that the genetic architecture of this trait was partially shared between the two sexes. For both sexes, starvation resistance was positively correlated with longevity and lipid storage at genetic level. The present study suggests that sex differences in starvation resistance depend on mating status and have a genetic basis in D. melanogaster.
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