Twenty-four hour (circadian) rhythmicity is an important component of biological variability associated with studies relating to biomarkers of aging. Chronobiological testing techniques must be utilized because (1) ma...Twenty-four hour (circadian) rhythmicity is an important component of biological variability associated with studies relating to biomarkers of aging. Chronobiological testing techniques must be utilized because (1) many variables that are related to the modulation of metabolic output vary dramatically at different times of the day; (2) various experimental variable and treatment groups must be synchronized with environmental cues that control circadian rhythms; and (3) multiple circadian variables may interact together to modulate the rate of aging. The rhythm for physiological factors such as whole animal metabolic output, body temperature, heart rate, urine flow, potassium, etc. were found to be dissociated or altered by the senescence process; behavioral variables such as spontaneous activity, wheel running, feeding and drinking, verbal performance, as well as sleep-wakefulness rhythms, seem to be accurate predictors of biological age. Circadian rhythms for a variety of enzymes of intermediary metabolism which are directly associated with energy metabolism have been well documented. These well-defined rhythms of enzyme activity have also been shown to degenerate with aging. Rhythms tend to lose amplitude as activity falls with age and as a general loss of regulation (especially time of day where maximal activity might be found) of activity across the 24-h span occurs. As with behavioral variables, changes in enzyme rhythms appear to accurately predict aging. Generally speaking, the loss of temporal organization with age, characterized by decreased circadian amplitude, loose internal synchronization, and poor response to external environmental time queues, is associated with poor health states and decreased longevity. Temporal rhythms for whole animal parameters are highly correlated with molecular events, such as regulation of cellular metabolism. DNA repair, and gene expression. Automated data acquisition and process control systems will be required for future Chronobiological studies to develop biomarkers of aging.展开更多
The ＂fly factor＂ was first discovered 〉60 years ago and describes the phe- nomenon that food currently or previously fed on by flies attracts more foraging flies than the same type and amount of food kept inaccessi...The ＂fly factor＂ was first discovered 〉60 years ago and describes the phe- nomenon that food currently or previously fed on by flies attracts more foraging flies than the same type and amount of food kept inaccessible to flies. Since then, there has been little progress made to understanding this phenomenon. Our objectives were （i） to demonstrate the existence of the fly factor in house flies, Musca domestica and （ii） to study underlying mechanisms that may cause or contribute to the fly factor. In 2-choice laboratory bioassays, we obtained unambiguous evidence for a fly factor phenomenon in house flies, in that we demonstrated that feeding flies are more attractive to foraging flies than are nonfeeding flies, and that fed-on food is more attractive to foraging flies than is ＂clean＂ food. Of the potential mechanisms （fly excreta, metabolic output parameters [elevated temperature, relative humidity, carbon dioxide]）, causing the fly factor, fly feces, and regurgitate do at- tract foraging flies but none of the metabolic output parameters of feeding flies does. Even though feeding flies produce significantly more CO2 than nonfeeding flies, elevated levels of CO2 have no behavior-modifying effect on flies. Preferential attraction of house flies to fly feces and regurgitate indicates that the flies sense airborne semiochemicals emana- ting from these sources. Hypothesizing that these semiochemicals are microbe-produced, future studies will aim at isolating and mass producing these microbes to accumulate semiochemicals for identification.展开更多
文摘Twenty-four hour (circadian) rhythmicity is an important component of biological variability associated with studies relating to biomarkers of aging. Chronobiological testing techniques must be utilized because (1) many variables that are related to the modulation of metabolic output vary dramatically at different times of the day; (2) various experimental variable and treatment groups must be synchronized with environmental cues that control circadian rhythms; and (3) multiple circadian variables may interact together to modulate the rate of aging. The rhythm for physiological factors such as whole animal metabolic output, body temperature, heart rate, urine flow, potassium, etc. were found to be dissociated or altered by the senescence process; behavioral variables such as spontaneous activity, wheel running, feeding and drinking, verbal performance, as well as sleep-wakefulness rhythms, seem to be accurate predictors of biological age. Circadian rhythms for a variety of enzymes of intermediary metabolism which are directly associated with energy metabolism have been well documented. These well-defined rhythms of enzyme activity have also been shown to degenerate with aging. Rhythms tend to lose amplitude as activity falls with age and as a general loss of regulation (especially time of day where maximal activity might be found) of activity across the 24-h span occurs. As with behavioral variables, changes in enzyme rhythms appear to accurately predict aging. Generally speaking, the loss of temporal organization with age, characterized by decreased circadian amplitude, loose internal synchronization, and poor response to external environmental time queues, is associated with poor health states and decreased longevity. Temporal rhythms for whole animal parameters are highly correlated with molecular events, such as regulation of cellular metabolism. DNA repair, and gene expression. Automated data acquisition and process control systems will be required for future Chronobiological studies to develop biomarkers of aging.
文摘The ＂fly factor＂ was first discovered 〉60 years ago and describes the phe- nomenon that food currently or previously fed on by flies attracts more foraging flies than the same type and amount of food kept inaccessible to flies. Since then, there has been little progress made to understanding this phenomenon. Our objectives were （i） to demonstrate the existence of the fly factor in house flies, Musca domestica and （ii） to study underlying mechanisms that may cause or contribute to the fly factor. In 2-choice laboratory bioassays, we obtained unambiguous evidence for a fly factor phenomenon in house flies, in that we demonstrated that feeding flies are more attractive to foraging flies than are nonfeeding flies, and that fed-on food is more attractive to foraging flies than is ＂clean＂ food. Of the potential mechanisms （fly excreta, metabolic output parameters [elevated temperature, relative humidity, carbon dioxide]）, causing the fly factor, fly feces, and regurgitate do at- tract foraging flies but none of the metabolic output parameters of feeding flies does. Even though feeding flies produce significantly more CO2 than nonfeeding flies, elevated levels of CO2 have no behavior-modifying effect on flies. Preferential attraction of house flies to fly feces and regurgitate indicates that the flies sense airborne semiochemicals emana- ting from these sources. Hypothesizing that these semiochemicals are microbe-produced, future studies will aim at isolating and mass producing these microbes to accumulate semiochemicals for identification.
