Increased temperature manifests the reduction of body length in the dbl-1 null mutant
We noticed that the phenotype of mua-3 is dependent on temperature, and so is that of the null mutant of dbl-1, the C. elegans TGFβ2 homolog. At 25° the mutants are shortest, at 15° the mutants are longest, and at 20° the body length is in between the two temperatures (25° and 15°) (see Figure 5, A and B for quantification). This allele does not produce any protein, yet the body length is more reduced at a high temperature. This result suggests that temperature influences the body size phenotype regardless of the stability or function of the protein. Moreover, similar to the case of mua-3, increased temperature exacerbates the phenotype.
Figure 5  dbl-1 null mutants showed temperature-dependent phenotypes. (A) The 2-day-old dbl-1(nu3) mutants grown at different temperatures show different body lengths; they are longest at 15° and shortest at 25°. (B) Quantification of the difference in body lengths. More than 20 mutants were used for each sample and the experiments were repeated three times. P < 0.001 by one-way ANOVA.