Control of Size and Allometry: A Top-Down Approach

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Name: H. Frederik NijhoutProposal #: IOS-0744952Proposal Title: Control of Size and Allometry: A Top-Down ApproachIntellectual Merit This work will study the mechanisms that regulate the proportional sizes of body parts. The relationship between the relative sizes of body parts and overall body size is called allometry. Within a taxonomic group of animals, morphological evolution occurs primarily by changes in allometry. Hence understanding the processes by which body parts achieve their absolute and relative sizes is critical for a deep understanding of the development and evolution of animal form. Most experimental work in this field has focused on "bottom up" studies that examine the effects of the genetic manipulation on the final size. What is missing is an understanding of the processes by which body parts get to their exact final size and shape. The "top down" approach proposed here will reconstruct the pathways by which body parts achieved their final size by studying how local cell proliferation, cell enlargement, and cell death act to determine final size and shape. The proposed work will focus on the development of the wings of insects where cellular studies are particularly tractable. The proposed work will discover whether genetically- and nutritionally-caused differences in absolute and relative wing sizes and shapes are due to differences in cell size or cell number, in localized rate of cell divisions and/or the timing of cell divisions, and patterned cell death. The significance of this work is that it will begin to identify, step by step, the underlying processes by which genetic changes lead to changes in size and shape. Broader Impacts The approach to understanding size and shape proposed here is generally applicable to other body parts and other species and is an essential complement to molecular-genetic approaches. The education of undergraduate students has always been an integral part of Dr. Nijhout's research program. The research of undergraduate students has resulted in 7 publications in the peer-reviewed literature in the past 5 years. Dr. Nijhout gives regular public lay person's lectures about his NSF-funded research at various venues in the Durham area.