dr Ludwik Gąsiorowski

@article{Gąsiorowski2025b,

title = {Regeneration in the absence of canonical neoblasts in an early branching flatworm},

author = {Ludwik Gąsiorowski and Chew Chai and Andrei Rozanski and Gargi Purandare and Fruzsina Ficze and Athanasia Mizi and Bo Wang and Jochen C. Rink},

doi = {10.1038/s41467-024-54716-x},

issn = {2041-1723},

year  = {2025},

date = {2025-12-00},

urldate = {2025-12-00},

journal = {Nature Communications},

volume = {16},

number = {1},

publisher = {Springer Science and Business Media LLC},

abstract = {The remarkable regenerative abilities of flatworms are closely linked to neoblasts – adult pluripotent stem cells that are the only division-competent cell type outside of the reproductive system. Although the presence of neoblast-like cells and whole-body regeneration in other animals has led to the idea that these features may represent the ancestral metazoan state, the evolutionary origin of both remains unclear. Here we show that the catenulid Stenostomum brevipharyngium, a member of the earliest-branching flatworm lineage, lacks conventional neoblasts despite being capable of whole-body regeneration and asexual reproduction. Using a combination of single-nuclei transcriptomics, in situ gene expression analysis, and functional experiments, we find that cell divisions are not restricted to a single cell type and are associated with multiple fully differentiated somatic tissues. Furthermore, the cohort of germline multipotency genes, which are considered canonical neoblast markers, are not expressed in dividing cells, but in the germline instead, and we experimentally show that they are neither necessary for proliferation nor regeneration. Overall, our results challenge the notion that canonical neoblasts are necessary for flatworm regeneration and open up the possibility that neoblast-like cells may have evolved convergently in different animals, independent of their regenerative capacity.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gąsiorowski2025,

title = {Evidence for Multiple Independent Expansions of Fox Gene Families Within Flatworms},

author = {Ludwik Gąsiorowski},

doi = {10.1007/s00239-024-10226-4},

issn = {1432-1432},

year  = {2025},

date = {2025-01-18},

urldate = {2025-01-18},

journal = {Journal of Molecular Evolution},

publisher = {Springer Science and Business Media LLC},

abstract = {Expansion and losses of gene families are important drivers of molecular evolution. A recent survey of Fox genes in flatworms revealed that this superfamily of multifunctional transcription factors, present in all animals, underwent extensive losses and expansions during platyhelminth evolution. In this paper, I analyzed Fox gene complement in four additional species of platyhelminths, that represent early-branching lineages in the flatworm phylogeny: catenulids (Stenostomum brevipharyngium and Stenostomum leucops) and macrostomorphs (Macrostomum hystrix and Macrostomum cliftonense). Phylogenetic analysis of Fox genes from this expanded set of species provided evidence for multiple independent expansions of Fox gene families within flatworms. Notably, FoxG, a panbilaterian brain-patterning gene, appears to be the least susceptible to duplication, while FoxJ1, a conserved ciliogenesis factor, has undergone extensive expansion in various flatworm lineages. Analysis of the single-cell atlas of S. brevipharyngium, combined with RNA in situ hybridization, elucidated the tissue-specific expression of the selected Fox genes: FoxG is expressed in the brain, three of the Fox genes (FoxN2/3–2, FoxO4 and FoxP1) are expressed in the pharyngeal cells of likely glandular function, while one of the FoxQD paralogs is specifically expressed in the protonephridium. Overall, the evolution of Fox genes in flatworms appears to be characterized by an early contraction of the gene complement, followed by lineage-specific expansions that have enabled the co-option of newly evolved paralogs into novel physiological and developmental functions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gąsiorowski2023b,

title = {Phoronida—A small clade with a big role in understanding the evolution of lophophorates},

author = {Ludwik Gąsiorowski},

doi = {10.1111/ede.12437},

issn = {1525-142X},

year  = {2024},

date = {2024-07-00},

urldate = {2024-07-00},

journal = {Evolution and Development},

volume = {26},

number = {4},

pages = {e12437},

publisher = {Wiley},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gąsiorowski2023,

title = {Convergent evolution of the sensory pits in and within flatworms},

author = {Ludwik Gąsiorowski and Isabel Lucia Dittmann and Jeremias N. Brand and Torben Ruhwedel and Wiebke Möbius and Bernhard Egger and Jochen C. Rink},

doi = {10.1186/s12915-023-01768-y},

issn = {1741-7007},

year  = {2023},

date = {2023-12-00},

urldate = {2023-12-00},

journal = {BMC Biology},

volume = {21},

number = {1},

pages = {266},

publisher = {Springer Science and Business Media LLC},

abstract = {Background

Unlike most free-living platyhelminths, catenulids, the sister group to all remaining flatworms, do not have eyes. Instead, the most prominent sensory structures in their heads are statocysts or sensory pits. The latter, found in the family Stenostomidae, are concave depressions located laterally on the head that represent one of the taxonomically important traits of the family. In the past, the sensory pits of flatworms have been homologized with the cephalic organs of nemerteans, a clade that occupies a sister position to platyhelminths in some recent phylogenies. To test for this homology, we studied morphology and gene expression in the sensory pits of the catenulid Stenostomum brevipharyngium.



Results

We used confocal and electron microscopy to investigate the detailed morphology of the sensory pits, as well as their formation during regeneration and asexual reproduction. The most prevalent cell type within the organ is epidermally-derived neuron-like cells that have cell bodies embedded deeply in the brain lobes and long neurite-like processes extending to the bottom of the pit. Those elongated processes are adorned with extensive microvillar projections that fill up the cavity of the pit, but cilia are not associated with the sensory pit. We also studied the expression patterns of some of the transcription factors expressed in the nemertean cephalic organs during the development of the pits. Only a single gene, pax4/6, is expressed in both the cerebral organs of nemerteans and sensory pits of S. brevipharyngium, challenging the idea of their deep homology.



Conclusions

Since there is no morphological or molecular correspondence between the sensory pits of Stenostomum and the cerebral organs of nemerteans, we reject their homology. Interestingly, the major cell type contributing to the sensory pits of stenostomids shows ultrastructural similarities to the rhabdomeric photoreceptors of other flatworms and expresses ortholog of the gene pax4/6, the pan-bilaterian master regulator of eye development. We suggest that the sensory pits of stenostomids might have evolved from the ancestral rhabdomeric photoreceptors that lost their photosensitivity and evolved secondary function. The mapping of head sensory structures on plathelminth phylogeny indicates that sensory pit-like organs evolved many times independently in flatworms.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Bekkouche2022,

title = {Careful amendment of morphological data sets improves phylogenetic frameworks: re-evaluating placement of the fossil \textit{Amiskwia sagittiformis}},

author = {Nicolas Bekkouche and Ludwik Gąsiorowski},

doi = {10.1080/14772019.2022.2109217},

issn = {1478-0941},

year  = {2022},

date = {2022-12-31},

urldate = {2022-12-31},

journal = {Journal of Systematic Palaeontology},

volume = {20},

number = {1},

pages = {1-14},

publisher = {Informa UK Limited},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Wernström2022,

title = {Brachiopod and mollusc biomineralisation is a conserved process that was lost in the phoronid–bryozoan stem lineage},

author = {Joel Vikberg Wernström and Ludwik Gąsiorowski and Andreas Hejnol},

doi = {10.1186/s13227-022-00202-8},

issn = {2041-9139},

year  = {2022},

date = {2022-12-00},

urldate = {2022-12-00},

journal = {EvoDevo},

volume = {13},

pages = {17},

publisher = {Springer Science and Business Media LLC},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gąsiorowski2021,

title = {Molecular and morphological analysis of the developing nemertean brain indicates convergent evolution of complex brains in Spiralia},

author = {Ludwik Gąsiorowski and Aina Børve and Irina A. Cherneva and Andrea Orús-Alcalde and Andreas Hejnol},

doi = {10.1186/s12915-021-01113-1},

issn = {1741-7007},

year  = {2021},

date = {2021-12-00},

urldate = {2021-12-00},

journal = {BMC Biology},

volume = {19},

number = {175},

publisher = {Springer Science and Business Media LLC},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gąsiorowski2021b,

title = {Molecular evidence for a single origin of ultrafiltration-based excretory organs},

author = {Ludwik Gąsiorowski and Carmen Andrikou and Ralf Janssen and Paul Bump and Graham E. Budd and Christopher J. Lowe and Andreas Hejnol},

doi = {10.1016/j.cub.2021.05.057},

issn = {0960-9822},

year  = {2021},

date = {2021-08-00},

urldate = {2021-08-00},

journal = {Current Biology},

volume = {31},

number = {16},

pages = {3629--3638.e2},

publisher = {Elsevier BV},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gąsiorowski2020,

title = {Hox gene expression during development of the phoronid Phoronopsis harmeri},

author = {Ludwik Gąsiorowski and Andreas Hejnol},

doi = {10.1186/s13227-020-0148-z},

issn = {2041-9139},

year  = {2020},

date = {2020-12-00},

urldate = {2020-12-00},

journal = {EvoDevo},

volume = {11},

number = {2},

publisher = {Springer Science and Business Media LLC},

abstract = {Background. Phoronida is a small group of marine worm-like suspension feeders, which together with brachiopods and bryozoans form the clade Lophophorata. Although their development is well studied on the morphological level, data regarding gene expression during this process are scarce and restricted to the analysis of relatively few transcription factors. Here, we present a description of the expression patterns of Hox genes during the embryonic and larval development of the phoronid Phoronopsis harmeri. Results. We identified sequences of eight Hox genes in the transcriptome of Ph. harmeri and determined their expression pattern during embryonic and larval development using whole mount in situ hybridization. We found that none of the Hox genes is expressed during embryonic development. Instead their expression is initiated in the later developmental stages, when the larval body is already formed. In the investigated initial larval stages the Hox genes are expressed in the non-collinear manner in the posterior body of the larvae: in the telotroch and the structures that represent rudiments of the adult worm. Additionally, we found that certain head-specific transcription factors are expressed in the oral hood, apical organ, preoral coelom, digestive system and developing larval tentacles, anterior to the Hox-expressing territories. Conclusions. The lack of Hox gene expression during early development of Ph. harmeri indicates that the larval body develops without positional information from the Hox patterning system. Such phenomenon might be a consequence of the evolutionary intercalation of the larval form into an ancestral life cycle of phoronids. The observed Hox gene expression can also be a consequence of the actinotrocha representing a “head larva”, which is composed of the most anterior body region that is devoid of Hox gene expression. Such interpretation is further supported by the expression of head-specific transcription factors. This implies that the Hox patterning system is used for the positional information of the trunk rudiments and is, therefore, delayed to the later larval stages. We propose that a new body form was intercalated to the phoronid life cycle by precocious development of the anterior structures or by delayed development of the trunk rudiment in the ancestral phoronid larva.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gąsiorowski2019,

title = {Hox gene expression in postmetamorphic juveniles of the brachiopod Terebratalia transversa},

author = {Ludwik Gąsiorowski and Andreas Hejnol},

doi = {10.1186/s13227-018-0114-1},

issn = {2041-9139},

year  = {2019},

date = {2019-12-00},

urldate = {2019-12-00},

journal = {EvoDevo},

volume = {10},

number = {1},

publisher = {Springer Science and Business Media LLC},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gąsiorowski2019b,

title = {Morphology of the nervous system of monogonont rotifer Epiphanes senta with a focus on sexual dimorphism between feeding females and dwarf males},

author = {Ludwik Gąsiorowski and Anlaug Furu and Andreas Hejnol},

doi = {10.1186/s12983-019-0334-9},

issn = {1742-9994},

year  = {2019},

date = {2019-12-00},

urldate = {2019-12-00},

journal = {Frontiers in Zoology},

volume = {16},

number = {33},

publisher = {Springer Science and Business Media LLC},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gąsiorowski2017,

title = {New insights on the musculature of filospermoid Gnathostomulida},

author = {Ludwik Gąsiorowski and Nicolas Bekkouche and Martin V. Sørensen and Reinhardt M. Kristensen and Wolfgang Sterrer and Katrine Worsaae},

doi = {10.1007/s00435-017-0367-6},

issn = {1432-234X},

year  = {2017},

date = {2017-12-00},

urldate = {2017-12-00},

journal = {Zoomorphology},

volume = {136},

number = {4},

pages = {413--424},

publisher = {Springer Science and Business Media LLC},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gąsiorowski2017b,

title = {Morphology and evolution of the nervous system in Gnathostomulida (Gnathifera, Spiralia)},

author = {Ludwik Gąsiorowski and Nicolas Bekkouche and Katrine Worsaae},

doi = {10.1007/s13127-017-0324-8},

issn = {1618-1077},

year  = {2017},

date = {2017-06-00},

urldate = {2017-06-00},

journal = {Organisms Diversity & Evolution},

volume = {17},

number = {2},

pages = {447--475},

publisher = {Springer Science and Business Media LLC},

keywords = {},

pubstate = {published},

tppubtype = {article}

}