Cold-Sensing TRP Channels and Temperature Preference Modulate Ovarian Development in the Model Organism Drosophila melanogaster

Abstract

Temperature is perceived primarily via transient receptor potential (TRP) channels, which are integral to the molecular machinery sensing environmental and cellular signals. Functional evidence of TRP channels' involvement in regulating cold-induced developmental/reproductive responses remains scarce. Here, we show that mutations affecting cold-sensing TRP channels antagonize the reduction in ovarian development induced by low temperatures (reproductive dormancy) in Drosophila melanogaster. More specifically, mutants for brv1, trp, and trpl significantly lowered dormancy levels at 12 °C and exhibited well-developed oocytes characterized by advanced vitellogenesis. Similarly, functional knockouts for norpA, a gene encoding a phospholipase C acting downstream to Trp and Trpl, exhibited a reduced dormancy response, suggesting that Ca²⁺ signaling is key to relaying cold-sensing stimuli during dormancy induction and maintenance. Finally, mutants with an altered temperature preference (i.e., exhibiting impaired cold or warm avoidance) differentially responded to the cold, either lowering or increasing dormancy levels. In summary, our phenotypic analysis provides functional evidence of developmental/reproductive modulation by specific cold-sensing TRP channels in Drosophila melanogaster and indicates that temperature preference affects developmental processes.

Keywords: TRP channels; ovarian development; reproductive dormancy; temperature preference; temperature sensing.

Figure 1

Phylogenetic tree reconstruction of Drosophila and human TRP channels highlighting the different classes within this protein family. Black arrows mark TRP channels analyzed in the present study. For bootstrap values, please refer to Supplementary Figure S1.

Figure 2

Levels of ovarian dormancy expressed as percentage of dormant females in Drosophila mutants for TRP channels. All strains were tested under LD 8:16. (A) Percentage of ovarian dormancy (mean ± 95% confidence interval) in brv1 mutants (brv^hyp and brv1^-/-) and respective background controls (please refer to Section 4) (**** p < 0.0001). (B,C) Percentage of ovarian dormancy (mean ± 95% confidence interval) in females of (B) trp (trp1, trpP343, trpP365) and (C) trpl mutants, and pertinent background controls. Controls used in (A,C) are the same, as experiments were run in parallel (** p < 0.01, **** p < 0.0001). (D–I) Representative pictures of ovarian development in genotypes assayed for ovarian dormancy (11 days at 12 °C) in brv1 (D,E) and trp (G,H) mutants, with pertinent background controls at the timeless locus (please refer to Section 4), i.e., w¹¹¹⁸ (ls-tim/ls-tim) (F) and w¹¹¹⁸ (s-tim/s-tim) (I). White bars = 0.2 mm. (J) Percentage (mean ± 95% confidence interval) of dormant females in norpA^P41 mutants and pertinent background controls. Controls in (J) are the same as in (B), as experiments were run in parallel (**** p < 0.0001).

Figure 3

Levels of ovarian dormancy expressed as percentage of dormant females in Drosophila mutants displaying abnormal temperature preference. (A) Percentage of ovarian dormancy (mean ± 95% confidence interval) in rut¹ and ort¹ mutants and pertinent background controls (please refer to Section 4). Controls used in (A) are the same as in Figure 2A,C, as experiments were run in parallel (*** p < 0.001). (B) Percentage of ovarian dormancy (mean ± 95% confidence interval) in dnc¹ and ort¹ mutants and pertinent background controls. Ctrl2 are the same as in [26], as experiments were run in parallel (**** p < 0.0001).