Project title: Identifying sexually dimorphic genes controlled by inter-allelic interactions.

Type of rotation: M1 (2 months) or M2 (6 months) Supervisors: Benjamin Prud’homme

Concept and Objectives

The expression of a gene is regulated by its flanking cis-regulatory sequences. However, it is becoming increasingly clear that in a growing number of biological contexts, proper gene expression also requires interactions between the two alleles of a gene. This gene regulatory phenomenon, known as transvection (or interallelic interaction), is particularly important to study for X chromosome-linked genes, which are present in two copies in XX females but only in one copy in XY males, as it can contribute to sexually dimorphic gene expression. Our group studies transvection in Drosophila fruit flies, focusing on the sexually dimorphic regulation of the yellow gene and its role in producing a male-specific spot at the wing tip. Using a combination of molecular techniques, transgenesis, genetics, DNA-FISH, quantitative confocal microscopy and image analysis, we aim to understand how two homologous alleles can find each other in the nuclear space, how they interact functionally, and how this interaction is related to the physical distance and spatial conformation of the two alleles. We also investigate whether transvection shapes sexually dimorphic gene expression in the brain. During the Master’s project (M1 or M2), the student will use some of the techniques used in the laboratory to quantitatively interrogate the structure-function relationship underlying interallelic interactions.

References

1) Galouzis, C. C. & Prud’homme, B. Transvection regulates the sex-biased expression of a fly X-linked gene. Science 371, 396–400 (2021). 2) Galouzis, C. C. & Prud’homme, B. Relevance and mechanisms of transvection. C.R. Biol. 344, 373–387 (2021). 3) Le Poul, Y. et al. Regulatory encoding of quantitative variation in spatial activity of a Drosophila enhancer. Sci. Adv. 6, eabe2955 (2020). 4) Arnoult, L. et al. Emergence and diversification of fly pigmentation through evolution of a gene regulatory module. Science 339, 1423–1426 (2013). 5) Gompel et al. Chance caught on the wing: cis-regulatory evolution and the origin of pigment patterns in Drosophila. Nature 433, 481–487 (2005).