• The Department celebrates the class of 2021 for all of their accomplishments.
  • features 2020 and 2021 recipients of the Genetech grant.
  • Members of the Deptartment of Biological Sciences gathered for the 2019 Department Retreat.

Seminar - Vil Fernandes

Vil Fernades is pictured
September 20, 2021 - 12:00pm
Virtual Seminar - Join Over Zoom

Department of Cell and Developmental Biology

University College London

Title: Tissue architecture and feedback from newly induced neurons set neuronal number in the Drosophila visual system

Abstract: Neural circuit formation and function require that diverse neurons are specified in appropriate numbers relative to each other. Known strategies that control neuronal numbers involve regulating either the number of progeny produced or the number of progeny to survive. We used the Drosophila visual system to probe how neuronal numbers are set. Photoreceptors from each unit eye or ommatidium achieve retinotopy with the lamina, the photoreceptor target field, by inducing a lamina unit (column) for each ommatidium. Photoreceptor-Hedgehog (Hh) specifies lamina precursor cells (LPCs) and promotes their assembly into columns. Although each column initially consists of 6 LPCs, only 5 differentiate into neurons, one for each of the L-neuron types (L1-L5), while the ‘extra’ LPC is eliminated by apoptosis. We uncovered that differential Hh signalling levels along the length of columns restrict LPC potential, such that both the ‘extra’ LPC and its neighbour, fated to be an L5, are restricted to L5 identity. We show that a glial population called the outer chiasm giant glia (xgO), which sit below the lamina secrete multiple ligands to induce L5 differentiation. The LPCs in closest proximity to xgO receive signals first and differentiate into L5s. These newly induced L5 neurons then negatively feedback to prevent glial signals from reaching the ‘extra’ LPCs. Thus, an intricate interplay between glial signals, tissue architecture and feedback from newly induced neurons determines which and, therefore, how many neurons are induced.

Please email [email protected] for a link to this talk.

News and Research Highlights

Portrait photo of Dr. Deborah Mowshowitz

August 24, 2021
On the occasion of her recent transition from Director of Undergraduate Studies in Biological Sciences to teaching in the Frontiers of Science program in Columbia College, Faculty Spotlight talked with Dr. Deborah Mowshowitz about her teaching, her students, and what has changed at Columbia since she arrived in the summer of ‘69.

Portrait photograph of Dr. Ismail Abdus-Saboor

August 24, 2021
The department is excited to welcome the newest addition to our faculty, Dr. Ishmail Abdus-Saboor
By Bryan Wang

Portrait style photograph of Dr. Liang Tong

June 24, 2021
 research has provided unprecedented molecular insights into cellular processes, especially large molecular complexes involved in RNA processing and fatty acid metabolism.

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