A germline-specific reporter reveals conserved primordial germ cell developmental dynamics between jawless and jawed fish species
- 1Michigan State University
Abstract
Primordial germ cells (PGCs) are the stem cell lineage responsible for transmitting genetic information across generations and are therefore central to studies of germline development, reproduction, and evolution. However, a lack of molecular tools in jawless vertebrates such as lampreys and hagfish has limited comparative insights into the evolutionary origins of vertebrate germline cells. Here, we report the development of the first germline-specific reporter (GSR) in the sea lamprey (Petromyzon marinus), Tg(piwil1: egfp-UTRnanos1), a piwil1-based germline reporter that is driven by the sea lamprey piwil1 regulatory region that directs Green Fluorescent Protein (GFP) expression in early PGCs. Promoter activity was validated by robust GFP expression in PGCs of zebrafish embryos co-injected with Tol2 transposase mRNA. Injection of the construct into sea lamprey embryos resulted in early, persistent, and gonad-localized GFP-positive cells. These results demonstrate stable germline-specific transgene expression in a jawless vertebrate and suggest deep evolutionary conservation of germline regulatory mechanisms between jawless and jawed vertebrates. Furthermore, the piwil1-based germline reporter line enabled lifetime visualization of zebrafish germline cells, revealing that increased PGC abundance during embryogenesis biases toward female sexual differentiation. Together, this study establishes the first GSR system in a jawless vertebrate and provides a useful platform for investigating germline biology and vertebrate germline evolution.
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BibTeX
@misc{sarasamma2026germlinespecific,
title = {{A germline-specific reporter reveals conserved primordial germ cell developmental dynamics between jawless and jawed fish species}},
author = {S. Sarasamma and Y.-W. Chung-Davidson and T. J. Buchinger and J. Song and W. Li},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.23.753524},
url = {https://www.biorxiv.org/content/10.64898/2026.09.23.753524v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - A germline-specific reporter reveals conserved primordial germ cell developmental dynamics between jawless and jawed fish species
AU - S. Sarasamma
AU - Y.-W. Chung-Davidson
AU - T. J. Buchinger
AU - J. Song
AU - W. Li
PY - 2026
DA - 2026/09/23
PB - bioRxiv
DO - 10.64898/2026.09.23.753524
UR - https://www.biorxiv.org/content/10.64898/2026.09.23.753524v1
AB - Primordial germ cells (PGCs) are the stem cell lineage responsible for transmitting genetic information across generations and are therefore central to studies of germline development, reproduction, and evolution. However, a lack of molecular tools in jawless vertebrates such as lampreys and hagfish has limited comparative insights into the evolutionary origins of vertebrate germline cells. Here, we report the development of the first germline-specific reporter (GSR) in the sea lamprey (Petromyzon marinus), Tg(piwil1: egfp-UTRnanos1), a piwil1-based germline reporter that is driven by the sea lamprey piwil1 regulatory region that directs Green Fluorescent Protein (GFP) expression in early PGCs. Promoter activity was validated by robust GFP expression in PGCs of zebrafish embryos co-injected with Tol2 transposase mRNA. Injection of the construct into sea lamprey embryos resulted in early, persistent, and gonad-localized GFP-positive cells. These results demonstrate stable germline-specific transgene expression in a jawless vertebrate and suggest deep evolutionary conservation of germline regulatory mechanisms between jawless and jawed vertebrates. Furthermore, the piwil1-based germline reporter line enabled lifetime visualization of zebrafish germline cells, revealing that increased PGC abundance during embryogenesis biases toward female sexual differentiation. Together, this study establishes the first GSR system in a jawless vertebrate and provides a useful platform for investigating germline biology and vertebrate germline evolution.
ER -