Passage VI

When Drosophila melanogaster (fruit flies) are exposed to unfavorable environmental conditions, they produce stress proteins (specialized molecules that help each organism survive stress). The stress proteins remain active until the flies are exposed to favorable environmental conditions that cause the stress protein production to cease. Two experiments examined how temperature and nutrient concentration affect the production of stress proteins in D. melanogaster.

Experiment 1
Each of 20 identical containers received 100 mL of nutrient solution and 150 freshly hatched D. melanogaster larvae. The containers were randomly divided into 5 groups (Groups A–E). For each group of containers, the nutrient solution was maintained at 1 of 5 different temperature values (see Table 1).

Each container was then incubated at the assigned temperature and monitored for 10 days at a nutrient concentration of 800 mg/L. At the end of 10 days, the number of stress proteins that had been produced in each container was counted, and the average number of stress proteins produced in each group was calculated (see Figure 1).

Figure 1

Experiment 2
Each of 25 identical containers received 100 mL of nutrient solution and 150 freshly hatched D. melanogaster larvae. The containers were randomly divided into 5 groups (Groups F–J). For each group of containers, the nutrient solution was maintained at 1 of 5 different nutrient concentrations (see Table 2).

At the end of 10 days, the average number of stress proteins produced in each group was determined as in Experiment 1 (see Figure 2).

Figure 2