Congratulations to former Seaver Lab graduate student Lauren Kunselman who published a paper in Developmental Biology from her dissertation work at the Whitney Lab. In addition, Kunselman's study image was selected as the Developmental Biology journal, Volume 538 cover image.
For centuries, scientists have wondered why some animals regenerate robustly while others can barely regenerate at all. Regenerative differences among species are still a compelling research topic for regeneration biologists today.
However, it is often underappreciated that even individuals of a species have disparate regenerative capacities within their own bodies. Annelids, or segmented worms, are prime examples of this. Some annelids can regenerate structures only if injury occurs at a certain location along their body. For example, one earthworm species regenerates fewer segments the further it is cut from the head, until at some point regeneration fails altogether [1]. Another worm species can regenerate both a head and tail from a single segment—the 14th segment to be precise [2]. In this worm, head regeneration fails when amputations are made at the 15th segment and beyond [2]. This variation begs the question of how regeneration is started or stopped in different regions of the body under the control of the same genetic material.
To investigate regulation of regeneration, the Seaver Lab studies a segmented worm called Capitella teleta. Their most recently published findings are in a paper entitled “Axial differences in cellular regeneration responses in the annelid Capitella teleta” in the journal Developmental Biology.
Adult animals of Capitella teleta consist of over 50 body segments. Head pieces can regenerate tail segments from many different amputation positions along the body, although tail fragments cannot regenerate a head. However, the capacity to regrow head structures had never been tested at different amputation locations along the length of the body. In experiments described in the paper, Kunselman et al. surgically removed the head and first segment in one group of worms and the head and the first ten segments of another group of worms. The tail fragments were analyzed to see if there were any differences in the ability of the two groups to form head structures. Kunselman found that posterior worm fragments with only one segment removed showed some signs of regeneration, including cell proliferation, nerve and muscle fiber growth, and neuron maturation. In contrast, worm tail fragments with ten segments removed did not grow much new tissue at all. This suggests that tail fragments containing more anterior structures had improved ability to regenerate new anterior structures, even though perfect head regeneration was never achieved.
To try to understand the mechanisms that inhibit completion of head regeneration, Kunselman applied a drug that inhibits an important cell signaling pathway, called the Wnt/beta-catenin signaling pathway. She found that worm fragments regenerated better when Wnt/beta-catenin cell signaling was inhibited, suggesting that Wnt signaling itself may suppress anterior regenerative abilities. Furthermore, the regenerated tissue displayed characteristics that were more “head-like” than “tail-like.”
This research is an important step in understanding how to increase or kickstart regenerative abilities in body regions that show limited capacity to replace missing parts. The Seaver Lab is excited to continue exploring how regeneration is regulated in this marine worm, so that one day we may be able to apply the key principles to help humans regenerate.
The full paper, "Axial differences in cellular regeneration responses in the annelid Capitella teleta", can be found at the following link: https://doi.org/10.1016/j.ydbio.2026.07.013
- Myohara M. 2012 What role do annelid neoblasts play? A comparison of the regeneration patterns in a neoblast-bearing and a neoblast-lacking enchytraeid oligochaete. PLoS One 7. (doi:10.1371/journal.pone.0037319)
- Berrill NJ. 1928 Regeneration in the polychaete Chaetopterus variopedatus. Journal of the Marine Biological Association of the United Kingdom , 151–158.
Cover Image: The image depicts regenerating tissue at the amputation site of a C. teleta tail fragment treated with Wnt/beta-catenin inhibitor for one week.