Camilla Larsen

My research focus on one of the fundamental questions in developmental biology namely how cells are specified during development. Using Drosophila as a model organism I am particularly interested in the molecular mechanisms underlying patterning of neurons in the brain. During late embryonic and larval development the Drosophila brain neuropile divides into compartments composed of axonal and dendritic arbors. It has been shown that these compartments prefigure discrete functional units in the adult brain. For example the mushroom body and antennal lobe can be traced as a neuropile compartment from late embryogenesis.

Whereas the genetic components involved in specifying broad regional identity of the early embryonic brain are well understood, little is known about the molecular mechansimsm underlying patterning of the smaller neuronal comartments. Consequently there is a large gap in our understanding about how most of the adult brain is patterned.

The aim of my work is to elucidate the molecular players involved in specifying sub-populations of neurons that give rise to individual compartments. I use a novel promoter trap to screen for genes expressed in restricted populations of developing neurons [3]. This unique approach allows me to label cells and address the function of the “trapped” gene within those cells using loss- and gain-of-function approaches. In addition, the promoter trap allows me to address the function of the neurons themselves within the intact brain. This is a valubale tool since we still know little about the function of large areas of the Drsosophila brain. Thus, my promoter trap allows me to address the function of genes in patterning neuronal sub-populations and to identify the function of novel neuronal circuits. 

Using the promoter trap approach in a pilot screen we have identified an insertion into the transcription factor Odd-skipped (Odd). Odd is expressed in a small number of cells in the developing brain and their projections form a novel circuit which is part of the Mushroom body, the learning and memory centre of the Drosophila brain [5]. In addition, preliminary results suggest that Odd may also function non-autonomously in patterning the embryonic brain.

Presently we are addressing the function of Odd in patterning the brain using gain and loss of function approaches. We are also trying to elucidate the function of the Odd expressing neuron in learning and memory. Finally we are also carrying out a large scale screen for genes expressed in subsets of neuronal cells in the larval and embryonic brain