Biology subjects

Seaver, E. C.

Publications and source records attributed to Seaver, E. C..

4 recordsLinked to original sources

bioRxiv2025

A chromosome-level assembly and functional genomic resources for the model annelid Capitella teleta

BackgroundThe polychaete Capitella teleta is a commonly used annelid for studies in evolutionary developmental biology, comparative genomics, conservation, and ecotoxicology. Over a decade ago, it was the first polychaete to have its genome sequenced and assembled, contributing to pioneering studies that transformed our understanding of animal genomes and their evolution. However, this early resource is now outdated compared to current genome sequencing standards, limiting the use of modern functional genomic tools that could further our understanding of numerous biological processes. ResultsWe combine long-read and short-read sequencing with Hi-C chromatin conformation capture data to assemble the chromosome-level nuclear and mitochondrial genomes of the laboratory strain of C. teleta. This reference assembly more accurately reflects the expected genome size for this polychaete ([~]243.6 Mb) and contains a highly complete, evolutionarily conserved gene repertoire. Notably, the nuclear and mitochondrial genomes are heavily rearranged, indicating a decoupling between gene family repertoire and chromosomal evolution. The analyses of multi-omic datasets available for C. teleta, including developmental time courses of bulk and single-cell RNA-seq, ATAC-seq, and EM-seq, using the new reference assembly, resulted in a significant quality improvement, allowing us to identify new cell-type-specific gene markers and gain additional insights of biological relevance. Finally, we generated a publicly available genome browser that ensures all these resources are easily findable, accessible, interoperable, and reusable. ConclusionsOur study provides state-of-the-art genomic resources for the polychaete model C. teleta, addressing a pressing community need that will open new research opportunities in animal and genome evolution.

genomics↗

bioRxiv2025

Regrowing the growth zone: metamorphosis kickstarts regeneration in the annelid, Capitella teleta

The ability to regenerate can vary across an animals life history. We previously showed that Capitella teleta, an annelid worm, gains regenerative ability with age. Although larvae do not replace lost structures, juveniles and adults regenerate posteriorly following metamorphosis. To determine whether metamorphosis enables juveniles to regrow structures lost as larvae, we amputated C. teleta larvae, removing posterior segments, the hindgut, posterior growth zone, anus, and pygidium. Metamorphosis was then induced in these amputated larvae and reared as juveniles for 3-, 7-, or 14-days. New growth in juveniles was assessed by confocal microscopy, EdU staining, immunohistochemistry, and nuclear staining. A pgz and new segments were observed by 7 days post metamorphosis. Morphallaxis of the digestive system in preexisting tissue was also observed. In addition, re-amputation of juveniles resulted in regeneration of the pgz, segments, and hindgut. Our results demonstrate that amputated C. teleta larvae can metamorphose into functional juveniles capable of growing new segments, suggesting that metamorphosis acts as a switch to enable regeneration of structures essential for growth. This study highlights the impact of metamorphosis on changes in developmental plasticity. Summary statementThe annelid Capitella teleta can regain structures lost as a larva only after metamorphosis into a juvenile, indicating that metamorphosis may function as a switch in regeneration potential.

developmental biology↗

bioRxiv2023

Investigating the developmental onset of regenerative potential in the annelid Capitella teleta

An animals ability to regrow lost tissues or structures can vary greatly during its life cycle. The annelid Capitella teleta exhibits posterior, but not anterior, regeneration as juveniles and adults. In contrast, embryos display only limited replacement of specific tissues. To investigate when during development C. teleta becomes capable of regeneration, we assessed the extent to which larvae can regenerate. We hypothesized that larvae exhibit intermediate regeneration potential and demonstrate some features of juvenile regeneration, but do not successfully replace all lost structures. Both anterior and posterior regeneration potential of larvae were evaluated following amputation. Wound sites were analyzed for re-epithelialization, cell proliferation by EdU incorporation, stem cell and differentiation marker expression by in situ hybridization, presence of neurites and muscle fibers by immunohistochemistry and phalloidin staining respectively, and regrowth of structures. Wound healing occurred within 6 hours of amputation for both anterior and posterior amputations. Cell proliferation at both wound sites was observed for up to 7 days following amputation. In addition, the stem cell marker vasa was expressed at anterior and posterior wound sites. However, growth of new tissue was observed only in posterior amputations. Neurites from the ventral nerve cord were also observed at posterior wound sites. De novo ash expression in the ectoderm of anterior wound sites indicated neuronal cell specification, although the absence of elav expression indicated an inability to progress to neuronal differentiation. In rare instances, cilia and eyes reformed. Both amputations induced expanded expression of the myogenesis gene MyoD in pre-existing tissues. Our results indicate that amputated larvae complete early, but not late, stages of regeneration, indicating a gradual acquisition of regenerative ability in C. teleta. Furthermore, amputated larvae can metamorphose into burrowing juveniles, including those missing brain and anterior sensory structures. To our knowledge, this is the first study to assess regenerative potential of annelid larvae.

developmental biology↗

bioRxiv2018

Functional role of pax6 in eye and central nervous system development in the annelid Capitella teleta

The transcription factor Pax6 is an important regulator of early animal development. Loss of function mutations of pax6 in a range of animals results in a reduction or complete loss of the eye, a reduction of a subset of neurons, and defects in axon growth. There are no studies focusing on the role of pax6 during development of any lophotrochozoan representative, however, expression of pax6 in the developing eye and nervous system in a number of species suggest that pax6 plays a highly conserved role in eye and nervous system formation. We investigated the functional role of pax6 during development of the marine annelid Capitella teleta. Expression of pax6 transcripts in C. teleta larvae is similar to patterns found in other animals, with distinct subdomains in the brain and ventral nerve cord as well as in the larval and adult eye. To perturb pax6 function, two different splice-blocking morpholinos were used. Larvae resulting from injections with either morpholino show a reduction of the pax6 transcript, and development of both the larval eyes and the central nervous system architecture are highly disrupted. Preliminary downstream target analysis confirms disruption in expression of some components of the retinal gene regulatory network, as well as disruption of genes involved in nervous system development. Results from this study, taken together with studies from other species, reveal an evolutionarily conserved role for pax6 in eye development, and in neural specification and development.

developmental biology↗