Title: "Exploring stem cell and germ cell niches in the tapeworm Hymenolepis diminuta"
Tania Rozario, Ph.D
Center for Tropical and Emerging Global Diseases
University of Georgia
Tapeworms grow at rates that rival all metazoan tissues, including during embryonic and neoplastic growth. The rat tapeworm, Hymenolepis diminuta, produces up to 2,200 proglottids, increasing in length up to 3,400 fold, and weight up to 1.8 million fold within the first 15 days of infection. Tapeworms can also regenerate: they shed large parts of their body, releasing their embryos to continue their life cycle, yet are able to continuously replenish proglottids and maintain an equilibrium length. Such remarkable growth, regeneration, and reproduction are fueled by adult somatic stem cells. Using H. diminuta as a laboratory model, we find that regeneration is limited to the tapeworm neck. Using transcriptomic analyses and RNA interference, we functionally validated the
first molecular regulators of tapeworm stem cells. However, we find no evidence
that stem cells are restricted to the regeneration-competent neck. Instead, we find
that lethally irradiated tapeworms can be rescued from death when cells from
both regeneration-competent and regeneration-incompetent regions are
transplanted into the neck, suggesting that stem cells may be maintained
throughout the whole body while the extrinsic signals that make up the neck
microenvironment are crucial for regeneration. Preliminary results suggest that the
head plays at least two important functions: maintaining neck identity and
regulating stem cell proliferation. The microenvironment of the neck is highly
patterned along the anterior-posterior axis by Wnt signaling components among
other factors that we are now characterizing. In addition, the neck is also
responsible for regulating the germ cell niche though ebony-dependent signaling.
Together, the head and neck tissue provide a microenvironment that enables
region-specific regeneration in this tapeworm.
Tania Rozario got her PhD from the University of Virginia studying embryonic development. During her postdoc she joined Phil Newmark's lab (Morgridge Institute
for Research) to study planarian regeneration but pivoted toward their parasitic
cousins- tapeworms. Her work (re)established the rat tapeworm, Hymenolepis
diminuta, as a non-traditional model to explore the molecular mechanisms that
govern how tapeworms grow, regenerate, and reproduce at prolific rates.
Date: Monday, December 4, 2023
Time: 12 pm
Location: Hill Pavilion Room 132 and available virtually Via Zoom
Questions? Please contact Michael Black if you have questions.