Research in the Newmark laboratory utilizes the tools of molecular cell biology and functional genomics to address several major biological problems for which planarians serve as excellent models.
Differentiation of the Regenerative Stem Cells: Roles in Regeneration and Tissue Maintenance
Planarians can regenerate a complete animal from a tiny fragment of tissue; this amazing regenerative ability is based upon a population of somatic stem cells maintained in the adult. How
are these stem cells specified to adopt specific fates? How is their
differentiation choreographed to correctly replace the missing
structures? How are newly differentiated cells integrated into
functional tissues and organs, during regenerative and homeostatic
processes? How are stem cell proliferation and differentiation regulated systemically? We address these and related questions using the planarian, Schmidtea mediterranea, as a model, combining
high-throughput in situ hybridization screens to
identify cell type-specific markers, with transcriptomic analyses and
functional studies using double-stranded RNA-mediated genetic
interference (RNAi).
Regulation of Germ Cell Development and Differentiation
We are also interested in understanding the mechanisms
by which germ cells are specified, and how physiological/environmental signals regulate their proper
differentiation. In contrast to the commonly studied genetic model invertebrates, in which localized determinants specify germ cells in the early
embryo, planarians use inductive signals to form their germ cells from the somatic stem cells much later in development. Thus, the functional genomic
resources available for studying planarians can be used to examine
inductive germ cell specification and the factors required to convert a
somatic stem cell into a germ cell.
We are currently using unbiased,
genome-wide approaches to identify both intrinsic and extrinsic factors
required for proper germ cell development.
Using planarians as models for understanding parasitic flatworms
Schistosomes are parasitic flatworms and are the causative agents of schistosomiasis, a major neglected tropical disease affecting hundreds of millions of people. Although parasitic flatworms display several striking differences in their life cycles relative to their free-living relatives, they also share many common features. We are capitalizing on the experimental accessibility of planarians to help us understand several fundamental aspects of schistosome biology.
Image credits: Top, phosphotyrosine labeling in a planarian visualized by confocal microscopy (P. Newmark); Middle, distinct stages of spermatogenesis visualized by nuclear morphology (grey/black) and nanos mRNA (magenta) (Yuying Wang); Bottom, scanning electron micrograph of male and female pair of adult schistosomes (Ana Vieira and Jim Collins).