Office: SGM 203
Office phone: (303) 871-5658
Lab: SGM 288
Lab phone: (303) 871-3830
B.A., Marine Biology - University of North Carolina, Wilmington
Ph.D., Integrative Biology - University of California, Berkeley
The focus of my research is on the comparative genomics, cell and developmental biology of sponges. The broader objective of this research is to address fundamental questions about the origin and early evolution of animals. Sponges have particular relevance for our understanding of animal origins because they are likely to be the earliest branching animal lineage, their feeding cells are homologous to choanoflagellates (the closest animal outgroup), and they have an ancient fossil record. Therefore, the sponge body plan — which lacks muscles, nerves and a gut — is thought to have persisted since before the Cambrian and offers a unique window into the biology of the first animals.
A principle aim of the lab is to reconstruct the evolution of epithelial tissues. Epithelia have essential barrier, absorptive, secretory and structural functions that serve to regulate homeostasis between adjacent body compartments; thus, epithelia are hypothesized to have been a prerequisite for animal body plan diversification (Tyler, 2003). Whereas the epithelia of bilaterians are regulated by a conserved set of cell adhesion and polarity mechanisms, the mechanisms that regulate sponge tissues are poorly known. Using a comparative-genomic approach we have identified sponge homologs of many bilaterian adhesion and polarity proteins (Nichols et al., 2006) and have begun to study how these proteins function to regulate sponge tissues. Of particular interest is the sponge feeding epithelium (i.e., the choanoderm), which is unlike the gut of other animals in that it functions to capture and phagocytize bacterial prey. This is thought to be the most ancient animal tissue (Nichols et al. 2009), so the mechanisms that regulate adhesion and polarity in the choanoderm may reflect innovations associated with the transition to multicellularity and may be directly ancestral to the mechanisms operating in other animal tissues. In addition to using a "candidate-gene" approach, we conduct expression profiling experiments and utilize proteomic approaches to gain a more comprehensive perspective on the molecular mechanisms that regulate the sponge choanoderm.
Techniques used in the lab include second-generation DNA- and RNA-sequencing technologies, advanced epifluorescence and confocal microscopy combined with standard techniques in biochemistry and molecular biology. Our two primary model organisms include the sponge Oscarella carmela (Eastern Pacific) and Ephydatia muelleri (lakes and streams in North America, including Colorado).View Nichols' publications