Understanding how events at the molecular and cellular scales contribute to tissue form and function is key to uncovering mechanisms driving animal development, physiology and disease.Elucidating these mechanisms has been enhanced through the study of model organisms and the use of sophisticated genetic, biochemical and imaging tools. Here we present an optimized method for non-invasive imaging of Drosophila melanogaster at high resolution using micro computed tomography (µ-CT). Our method allows for rapid processing of intact animals at any developmental stage, provides precise quantitative assessment of tissue size and morphology, and permits analysis of inter-organ relationships. We then use the power of µ-CT imaging to model human diseases through the characterization of microcephaly in the fly. Our work demonstrates that µ-CT is a versatile and accessible tool that complements standard imaging techniques, capable of uncovering novel biological mechanisms that have remained undocumented due to limitations of current methods.

Insulators play important roles in genome structure and function in Drosophila and mammals.More than six different insulator proteins are required in Drosophila for normal genome function, whereas CTCF is the only identified protein contributing to insulator function in mammals.Interactions between a DNA binding insulator protein and its interacting partner proteins define the properties of each insulator site. The different roles of insulator protein partners in the Drosophila genome and how they confer functional specificity remain poorly understood.Functional analysis of insulator partner proteins in Drosophila is necessary to understand how genomes are compartmentalized and the roles that different insulators play in genome function. In Drosophila, the Suppressor of Hairy wing [Su(Hw)] insulator is targeted to the nuclear lamina, preferentially localizes at euchromatin/heterochromatin boundaries, and is associated with the Gypsy retrotransposon. The properties that the insulator confers to these sites rely on the ability of the Su(Hw) protein to bind the DNA at specific sites and interact with Mod(mdg4)-67.2 and CP190 partner proteins. HP1 and insulator partner protein 1 (HIPP1) is a recently identified partner of Su(Hw), but how HIPP1 contributes to the function of Su(Hw) insulators has not yet been elucidated. Here, we find that mutations in the HIPP1 crotonase-like domain have no impact on the function of Su(Hw) enhancer-blocking activity but do exhibit an impaired ability to repair double-strand breaks. Additionally, we find that the overexpression of each HIPP1 and Su(Hw) causes defects in cell proliferation by limiting the progression of DNA replication. We also find that HIPP1 overexpression suppresses the Su(Hw) insulator enhancer-blocking function.