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Quantification of food intake in Drosophila.

Wong R, Piper MD, Wertheim B, Partridge L - PLoS ONE (2009)

Bottom Line: We used the method to demonstrate that (a) female flies feed more frequently than males, (b) flies feed more often when housed in larger groups and (c) fly feeding varies at different times of the day.We also show that alterations in food intake are not induced by dietary restriction or by a mutation of the fly insulin receptor substrate chico.In contrast, mutation of takeout increases food intake by increasing feeding frequency while mutation of ovo(D) increases food intake by increasing the volume of food consumed per proboscis-extension.

View Article: PubMed Central - PubMed

Affiliation: Institute of Healthy Ageing, and GEE, University College London, London, UK.

ABSTRACT
Measurement of food intake in the fruit fly Drosophila melanogaster is often necessary for studies of behaviour, nutrition and drug administration. There is no reliable and agreed method for measuring food intake of flies in undisturbed, steady state, and normal culture conditions. We report such a method, based on measurement of feeding frequency by proboscis-extension, validated by short-term measurements of food dye intake. We used the method to demonstrate that (a) female flies feed more frequently than males, (b) flies feed more often when housed in larger groups and (c) fly feeding varies at different times of the day. We also show that alterations in food intake are not induced by dietary restriction or by a mutation of the fly insulin receptor substrate chico. In contrast, mutation of takeout increases food intake by increasing feeding frequency while mutation of ovo(D) increases food intake by increasing the volume of food consumed per proboscis-extension. This approach provides a practical and reliable method for quantification of food intake in Drosophila under normal, undisturbed culture conditions.

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Possible factors that influence feeding frequency.(a) The proportion of time spent feeding of 7-day old mated females over a 2-hour period at varying times after lights-on. Females were housed alone, or in groups of 2, 5 or 10 (the number of flies for each condition = 30, with 30 vials for single flies, 15 vials for groups of 2, 6 vials for groups of 5 and 3 vials for groups of 10). We found that increasing the number of flies per vial increased the feeding frequency of each fly, and overall, flies fed more frequently in the afternoon and evening. We calculated the proportion of time spent feeding by summing the scored feeding events divided by the total number of feeding opportunities, which is unaffected by the difference in the number of vials per condition (b) The proportion of time spent feeding for flies fed different yeast-based diets. Flies were fed two similar diets containing either a water-soluble yeast extract (CSYExtract) or lyophilised yeast (SYBrewer's) at two different concentrations (DR = Dietary Restriction, FF = Full Fed). While feeding frequency was sensitive to the concentration of yeast extract in the diet, it was unchanged by the concentration of lyophilised yeast (NF = 60 and NV = 12 per condition: ** = P<0.005, and error bars = S.E.).
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pone-0006063-g003: Possible factors that influence feeding frequency.(a) The proportion of time spent feeding of 7-day old mated females over a 2-hour period at varying times after lights-on. Females were housed alone, or in groups of 2, 5 or 10 (the number of flies for each condition = 30, with 30 vials for single flies, 15 vials for groups of 2, 6 vials for groups of 5 and 3 vials for groups of 10). We found that increasing the number of flies per vial increased the feeding frequency of each fly, and overall, flies fed more frequently in the afternoon and evening. We calculated the proportion of time spent feeding by summing the scored feeding events divided by the total number of feeding opportunities, which is unaffected by the difference in the number of vials per condition (b) The proportion of time spent feeding for flies fed different yeast-based diets. Flies were fed two similar diets containing either a water-soluble yeast extract (CSYExtract) or lyophilised yeast (SYBrewer's) at two different concentrations (DR = Dietary Restriction, FF = Full Fed). While feeding frequency was sensitive to the concentration of yeast extract in the diet, it was unchanged by the concentration of lyophilised yeast (NF = 60 and NV = 12 per condition: ** = P<0.005, and error bars = S.E.).

Mentions: To test these factors, we performed the undisturbed proboscis-extension assay at 3 different times in the day. Flies are maintained in a 12h∶ 12h light∶ dark cycle, and lights-on occurs at 10am and lights-off occurs at 10pm. We performed the proboscis-extension assay in the morning (at lights-on), in the afternoon (4 hours after lights-on), and in the evening (8 hours after lights-on) using 4 different group sizes (1, 2, 5 or 10 flies: Figure 3a). Both the time of day and the group size had highly significant effects on the proportion of time spent feeding (P<0.001 for both group size and time of day, GLM), while the interaction between these two was not significant (P = 0.88). The lowest feeding proportion was observed in the morning for flies housed singly (0.15 of the time spent feeding), and this increased to approximately 0.50 in the afternoon and evening for flies feeding in groups of 5 or more. Both the afternoon and evening feeding proportions were significantly higher than those in the morning (P<0.0001 in both cases, GLM). There was no significant difference in feeding proportions between flies during the afternoon and evening (P = 0.182, by model simplification). The lowest proportion of feeding was observed for flies housed singly 0.15–0.22 (depending on time of day), and this significantly increased to 0.18–0.31 (depending on time of day) when flies were housed in pairs (P = 0.009, GLM). The proportion of flies feeding was found to nearly double when the number of flies was increased to 5 per vial (0.32–0.49, depending on time of day; 2 flies per vial against 5 flies per vial, P<0.0001, GLM), and did not increase further when flies were housed at 10 per vial (0.36–0.52, depending on time of day; 5 flies per vial against 10 flies per vial, P = 0.287, by model simplification: Figure 3a).


Quantification of food intake in Drosophila.

Wong R, Piper MD, Wertheim B, Partridge L - PLoS ONE (2009)

Possible factors that influence feeding frequency.(a) The proportion of time spent feeding of 7-day old mated females over a 2-hour period at varying times after lights-on. Females were housed alone, or in groups of 2, 5 or 10 (the number of flies for each condition = 30, with 30 vials for single flies, 15 vials for groups of 2, 6 vials for groups of 5 and 3 vials for groups of 10). We found that increasing the number of flies per vial increased the feeding frequency of each fly, and overall, flies fed more frequently in the afternoon and evening. We calculated the proportion of time spent feeding by summing the scored feeding events divided by the total number of feeding opportunities, which is unaffected by the difference in the number of vials per condition (b) The proportion of time spent feeding for flies fed different yeast-based diets. Flies were fed two similar diets containing either a water-soluble yeast extract (CSYExtract) or lyophilised yeast (SYBrewer's) at two different concentrations (DR = Dietary Restriction, FF = Full Fed). While feeding frequency was sensitive to the concentration of yeast extract in the diet, it was unchanged by the concentration of lyophilised yeast (NF = 60 and NV = 12 per condition: ** = P<0.005, and error bars = S.E.).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2698149&req=5

pone-0006063-g003: Possible factors that influence feeding frequency.(a) The proportion of time spent feeding of 7-day old mated females over a 2-hour period at varying times after lights-on. Females were housed alone, or in groups of 2, 5 or 10 (the number of flies for each condition = 30, with 30 vials for single flies, 15 vials for groups of 2, 6 vials for groups of 5 and 3 vials for groups of 10). We found that increasing the number of flies per vial increased the feeding frequency of each fly, and overall, flies fed more frequently in the afternoon and evening. We calculated the proportion of time spent feeding by summing the scored feeding events divided by the total number of feeding opportunities, which is unaffected by the difference in the number of vials per condition (b) The proportion of time spent feeding for flies fed different yeast-based diets. Flies were fed two similar diets containing either a water-soluble yeast extract (CSYExtract) or lyophilised yeast (SYBrewer's) at two different concentrations (DR = Dietary Restriction, FF = Full Fed). While feeding frequency was sensitive to the concentration of yeast extract in the diet, it was unchanged by the concentration of lyophilised yeast (NF = 60 and NV = 12 per condition: ** = P<0.005, and error bars = S.E.).
Mentions: To test these factors, we performed the undisturbed proboscis-extension assay at 3 different times in the day. Flies are maintained in a 12h∶ 12h light∶ dark cycle, and lights-on occurs at 10am and lights-off occurs at 10pm. We performed the proboscis-extension assay in the morning (at lights-on), in the afternoon (4 hours after lights-on), and in the evening (8 hours after lights-on) using 4 different group sizes (1, 2, 5 or 10 flies: Figure 3a). Both the time of day and the group size had highly significant effects on the proportion of time spent feeding (P<0.001 for both group size and time of day, GLM), while the interaction between these two was not significant (P = 0.88). The lowest feeding proportion was observed in the morning for flies housed singly (0.15 of the time spent feeding), and this increased to approximately 0.50 in the afternoon and evening for flies feeding in groups of 5 or more. Both the afternoon and evening feeding proportions were significantly higher than those in the morning (P<0.0001 in both cases, GLM). There was no significant difference in feeding proportions between flies during the afternoon and evening (P = 0.182, by model simplification). The lowest proportion of feeding was observed for flies housed singly 0.15–0.22 (depending on time of day), and this significantly increased to 0.18–0.31 (depending on time of day) when flies were housed in pairs (P = 0.009, GLM). The proportion of flies feeding was found to nearly double when the number of flies was increased to 5 per vial (0.32–0.49, depending on time of day; 2 flies per vial against 5 flies per vial, P<0.0001, GLM), and did not increase further when flies were housed at 10 per vial (0.36–0.52, depending on time of day; 5 flies per vial against 10 flies per vial, P = 0.287, by model simplification: Figure 3a).

Bottom Line: We used the method to demonstrate that (a) female flies feed more frequently than males, (b) flies feed more often when housed in larger groups and (c) fly feeding varies at different times of the day.We also show that alterations in food intake are not induced by dietary restriction or by a mutation of the fly insulin receptor substrate chico.In contrast, mutation of takeout increases food intake by increasing feeding frequency while mutation of ovo(D) increases food intake by increasing the volume of food consumed per proboscis-extension.

View Article: PubMed Central - PubMed

Affiliation: Institute of Healthy Ageing, and GEE, University College London, London, UK.

ABSTRACT
Measurement of food intake in the fruit fly Drosophila melanogaster is often necessary for studies of behaviour, nutrition and drug administration. There is no reliable and agreed method for measuring food intake of flies in undisturbed, steady state, and normal culture conditions. We report such a method, based on measurement of feeding frequency by proboscis-extension, validated by short-term measurements of food dye intake. We used the method to demonstrate that (a) female flies feed more frequently than males, (b) flies feed more often when housed in larger groups and (c) fly feeding varies at different times of the day. We also show that alterations in food intake are not induced by dietary restriction or by a mutation of the fly insulin receptor substrate chico. In contrast, mutation of takeout increases food intake by increasing feeding frequency while mutation of ovo(D) increases food intake by increasing the volume of food consumed per proboscis-extension. This approach provides a practical and reliable method for quantification of food intake in Drosophila under normal, undisturbed culture conditions.

Show MeSH