Biology subjects

Rozario, T.

Publications and source records attributed to Rozario, T..

4 recordsLinked to original sources

bioRxiv2026

Assembly of a high-quality reference genome for the rat tapeworm Hymenolepis diminuta

The rat tapeworm, Hymenolepis diminuta, is an important laboratory model for uncovering molecular processes that underly the success of tapeworms as parasites. Despite its importance, a high-quality reference genome for this species is lacking. Here we present a highly contiguous and effectively complete genome of H. diminuta assembled from PacBio HiFi long-read sequencing data. Our primary assembly consists of 7 scaffolds (N50=29.25 Mb) with total length of 186.53 Mb, has only 7 gaps, and contains 95.7% complete Lophotrochozoan BUSCOs. Our assembly allows us to confirm aspects of Hymenolepis genome organization, such as high repeat content and unusual chromosomal ends, and to show that Hymenolepis genomes encode [~]10,000 genes. Together with annotations of nuclear tRNAs, mtDNA protein coding genes, and mtDNA tRNAs, our assembly currently provides one of the most complete genome resources for a tapeworm species and will enable research on parasitism, animal regeneration, development, and evolution.

genomics↗

bioRxiv2025

Anterior-posterior polarity signals differentially regulate regeneration-competence of the tapeworm Hymenolepis diminuta.

Competence to regenerate lost tissues varies widely across species. The rat tapeworm, Hymenolepis diminuta, undergoes continual cycles of shedding and regenerating thousands of reproductive segments to propagate the species. Despite its prowess, H. diminuta can only regenerate posteriorly from a singular tissue: the neck or germinative region (GR). What cells and signaling pathways restrict regeneration competence to the GR? In this study, we show that the head regulates regeneration competence by promoting maintenance of the GR and inhibiting proglottid formation in a distance-dependent manner. Anterior-posterior (A-P) patterning within the GR provide local signals that contribute to these responses. {beta}cat1 is necessary for stem cell maintenance, proliferation and proglottidization. On the other hand, sfrp is necessary for maintaining the GR at its proper length. Our study demonstrates that the head organizes a balance of pro- and anti-regeneration signals that must be integrated together and therefore control competence to regenerate. Summary statementThis study explores contradictory roles of the tapeworm head in providing pro- and anti-regeneration signals, which can form a tipping point zone that is refractory to regeneration.

developmental biology↗

bioRxiv2021

Krüppel-like factor 4 is required for development and regeneration of germline and yolk cells from somatic stem cells in planarians

Sexually reproducing animals segregate their germline from their soma. In addition to gamete-producing gonads, planarian and parasitic flatworm reproduction relies on yolk-cell-generating accessory reproductive organs (vitellaria) supporting development of yolkless oocytes. Despite the importance of vitellaria for flatworm reproduction (and parasite transmission), little is known about this unique evolutionary innovation. Here we examine reproductive system development in the planarian Schmidtea mediterranea, in which pluripotent stem cells generate both somatic and germ cell lineages. We show that a homolog of the pluripotency factor Klf4 is expressed in primordial germ cells, presumptive germline stem cells, and yolk-cell progenitors. klf4 knockdown animals fail to specify or maintain germ cells; surprisingly, they also fail to maintain yolk cells. We find that yolk cells display germ-cell-like attributes and that vitellaria are structurally analogous to gonads. In addition to identifying a new proliferative cell population in planarians (yolk cell progenitors) and defining its niche, our work provides evidence supporting the hypothesis that flatworm germ cells and yolk cells share a common evolutionary origin.

developmental biology↗

bioRxiv2018

Region-specific regulation of stem cell-driven regeneration in tapeworms

Tapeworms grow at rates rivaling the fastest-growing metazoan tissues. To propagate they shed large parts of their body; to replace these lost tissues they regenerate proglottids (segments) as part of normal homeostasis. Their remarkable growth and regeneration are fueled by adult somatic stem cells that have yet to be characterized molecularly. Using the rat intestinal tapeworm, Hymenolepis diminuta, we find that regenerative potential is regionally limited to the neck, where head-dependent extrinsic signals create a permissive microenvironment for stem cell-driven regeneration. Using transcriptomic analyses and RNA interference, we characterize and functionally validate regulators of tapeworm growth and regeneration. We find no evidence that stem cells are restricted to the regeneration-competent neck. Instead, lethally irradiated tapeworms can be rescued when cells from either regeneration-competent or regeneration-incompetent regions are transplanted into the neck. Together, the head and neck tissues provide extrinsic cues that regulate stem cells, enabling region-specific regeneration in this parasite.

developmental biology↗