Experiments on the effect of environment on gene expression in Drosophila

Many aspects of phenotype are influenced by the genetic composition of an organism and the environment in which it lives, so it can be said that phenotype is a product of the interaction between genotype and environment. The expression of the Drosophila curly wing gene is often modified by the environment, and the effect of environment on gene expression can be shown by observing the expression of this gene in different environments. The curly-wing gene (cu) is sensitive to temperature, and the wing tips of pure (cu/cu) Drosophila are curved when cultured at high temperatures (Fig. 7-1), but some Drosophila individuals with the same genotype have straight wings when cultured at low temperatures, so it can be said that the penetrance of the cu allele is incomplete. On the other hand, especially in Drosophila cultured at low temperatures, the wings show different degrees of curling, so it can be said that the expressivity of the gene is variable. cu gene's expressivity and prevalence also vary according to sex. Source: Laboratory Course in Genetics

Operation method

basic program

Materials and Instruments

Drosophila curved wing
Drosophila culture medium Ether
Constant temperature incubator Stereoscopic dissecting mirror Culture and anesthesia bottles

Move

1. Establish three culture systems from culture flasks of conserved Drosophila curvata (genotype cu/cu), females are not required to be virgin flies. The bottles were labeled with 20℃, 25℃ and 28℃, and the initial incubation temperature was 25℃ until pupation (this can accelerate the experimental process, and the effect of temperature on the expression of the cu gene only occurs in the developmental stage before hatching).

2. Release the parental Drosophila and transfer the culture flasks to a constant temperature incubator at the appropriate temperature for culture.

3. After the emergence of Drosophila adults, anesthetize them and observe the wing morphology of female and male Drosophila separately. The wings could be classified into 3 categories, i.e., curled wings, semi-curled wings, and straight wings (determine your own criteria, but the same criteria must be applied during the experiment).

Calculation of epistasis and expressivity:

Epistasis = number of affected Drosophila (curly-winged and semi-curly-winged)/total number of Drosophila × 100

Expression = (number of Drosophila with curly wings × 2 + number of Drosophila with semi-curly wings × 1)/(number of affected Drosophila × 2) × 100

Note: In calculating the degree of performance, the traits were weighted, Drosophila curly-winged as 2 and Drosophila semi-curly-winged as 1, so that the results were combined into a total degree of performance.

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