Drosophila Lab           

The fruit fly, Drosophila melanogaster, eye serves as an excellent model to study cell type specification during development. Drosophila eye has been extensively used to address diverse biological processes like patterning cell proliferation, cell death, cell survival, polarity and genetic basis of human diseases.  The compound eye of an adult fly develops from the primordium called eye imaginal disc harbored inside larva, which initiates from a group of 20- cells as early as an embryo (Fig. 1).

Fig.1 The compound eye of Drosophila comprising of 800 unit eyes, ommatidia, initiates from eye-antennal (E.A.) primordium present in the embryo (A), which grows into larval E.A imaginal disc (B). E.A imaginal disc give rise to adult eye (C), which comprises of dorsal (red) and     ventral (blue) compartments antenna (green) and adult head structures.  (Dorsal up and ventral down).    

Axial Patterning: Dorso-ventral patterning in Drosophila eye.

Axial patterning is hallmark of organogenesis which results in transition of a single sheet of cells into a 3-D organ. Our lab is interested in understanding the molecular genetic basis of the Dorso-ventral patterning, the first lineage restriction event of early eye primordium. DV patterning thus plays a crucial role in inducing growth and patterning of early eye disc. The dorsal and ventral domains of the eye are generated by the domain specific expression and function of the dorsal selector genes and the ventral growth controlling genes. Our results show that antagonistic interactions between dorsal and ventral genes define the dorso-ventral eye boundary or equator. Our lab will focus on identifying new components of DV patterning and their role in retinal determination of the eye.

Fig. 2. Ventral is the ground state of the early eye. Early larval eye primordium arises from an initial ventral state which require ventral gene function. Later, when dorsal genes expression emerges in the eye disc Dorsal-Ventral (DV) axis specification of the eye takes place. DV axis is the first axis defined in Drosophila eye (Singh & Choi, 2003)

Birth Defects:

 "Birth defects are the single leading cause of infant mortality. While we've made great strides in recent years, the causes of over 70 percent of birth defects remain unknown. The collective habilitation costs for these children surpass $1 billion dollars annually, a cost that pales to insignificance when compared to the physical and psychological impact of these birth defects on the affected children and their families. Despite unprecedented strides in molecular genetics, brought about through sequencing of the human genome, the causes of greater than 60% of all birth defects remain unknown. Our laboratory seek to provide a better understanding of the molecular, genetic, and environmental basis of normal eye development, as well as elucidate the genes and molecules that when altered result in the genesis of birth defects in eye.

Fig.3. Mutations in DV eye patterning- and RD- genes like eyeless/ PAX-6 in Drosophila results in (B) No-eye, (A) Wild-type eye. (C, D) A range of birth defects like loss  of  eye  field  are seen in the newborns. Genetic basis of these birth defects in eye is far from complete.

Cell Survival:

Early development of an organ primordium is marked by the rapid growth phase until a threshold of cell number is attained which allow differentiation process to begin. Our interest is to identify the genes which are required for cell survival during this early rapid growth phase. We have found that DV patterning genes also play this crucial role of cell survival during early eye development. Our focus would be to understand the mechanism and to identify the downstream components of this pathway.