Changes in dopamine levels and locomotor activity in response to selection on virgin lifespan in Drosophila melanogaster.
ABSTRACT Among various other mechanisms, genetic differences in the production of reactive oxygen species are thought to underlie genetic variation for longevity. Here we report on possible changes in ROS production related processes in response to selection for divergent virgin lifespan in Drosophila. The selection lines were observed to differ significantly in dopamine levels and melanin pigmentation, which is associated with dopamine levels at eclosion. These findings confirm that variation in dopamine levels is associated with genetic variation for longevity. Dopamine has previously been implied in ROS production and in the occurrence of age-related neurodegenerative diseases. In addition, we propose a possible proximate mechanism by which dopamine levels affect longevity in Drosophila: We tested if increased dopamine levels were associated with a "rate-of-living" syndrome of increased activity and respiration levels, thus aggravating the level of oxidative stress. Findings on locomotor activity and oxygen consumption of short-lived flies were in line with expectations. However, the relation is not straightforward, as flies of the long-lived lines did not show any consistent differences in pigmentation or dopamine levels with respect to the control lines. Moreover, long-lived flies also had increased locomotor activity, but showed no consistent differences in respiration rate. This strongly suggests that the response for increased and decreased lifespan may be obtained by different mechanisms.
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ABSTRACT: Body coloration affects how animals interact with the environment. In insects, the rapid evolution of black and brown melanin patterns suggests that these are adaptive traits. The developmental and molecular mechanisms that generate these pigment patterns are largely unknown. We demonstrate that the regulation and function of the yellow and ebony genes in Drosophila melanogaster play crucial roles in this process. The Yellow protein is required to produce black melanin, and is expressed in a pattern that correlates with the distribution of this pigment. Conversely, Ebony is required to suppress some melanin formation, and is expressed in cells that will produce both melanized and non-melanized cuticle. Ectopic expression of Ebony inhibits melanin formation, but increasing Yellow expression can overcome this effect. In addition, ectopic expression of Yellow is sufficient to induce melanin formation, but only in the absence of Ebony. These results suggest that the patterns and levels of Yellow and Ebony expression together determine the pattern and intensity of melanization. Based on their functions in Drosophila melanogaster, we propose that changes in the expression of Yellow and/or Ebony may have evolved with melanin patterns. Consistent with our hypothesis, we find that Yellow and Ebony are expressed in complementary spatial patterns that correlate with the formation of an evolutionary novel, male-specific pigment pattern in Drosophila biarmipes wings. These findings provide a developmental and genetic framework for understanding the evolution of melanin patterns.Development 05/2002; 129(8):1849-58. · 6.21 Impact Factor
- Advances in genetics 02/1987; 24:127-222. · 4.85 Impact Factor
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ABSTRACT: The main purpose of this article is to provide a critical overview of the currently available evidence bearing on the validity of the oxidative stress hypothesis of aging, which postulates that senescence-associated attenuations in physiological functions are caused by molecular oxidative damage. Several lines of correlative evidence support the predictions of the hypothesis, e.g., macromolecular oxidative damage increases with age and tends to be associated with life expectancy of organisms. Nevertheless, a direct link between oxidative stress and aging has not as yet been established. Single gene mutations have been reported to extend the life spans of lower organisms, such as nematodes and insects; however, such prolongations of chronological clock time survival are usually associated with decreases in the rate of metabolism and reproductive output without affecting the metabolic potential, i.e., the total amount of energy consumed during life. Studies on genetic manipulations of the aging process have often been conducted on relatively short-lived strains that are physiologically weak, whereby life-span extensions can not be unambiguously assigned to a slowing effect on the rate of aging. It is concluded that although there is considerable evidence implicating oxidative stress in the aging process, additional evidence is needed to clearly define the nature of the involvement.Free Radical Biology and Medicine 10/2002; 33(5):575-86. · 5.27 Impact Factor