Zoologia porównawcza bezkręgowców

Tematyka badań

Nasz zespół skupia się na zrozumieniu w jaki sposób ewoluuje różnorodność form i historii życiowych zwierząt. W szczególności badamy mikroskopijne wolnożyjące płazińce z grupy Catenulida, które stanowią dla nas modelowy klad umożliwiający lepsze poznanie rozmaitych zagadnień związanych z ewolucyjną biologią rozwoju i szeroko pojętą zoologią porównawczą. W swoich badaniach łączymy klasyczne pytania biologiczne (np. jak ewoluują nowe struktury morfologiczne i strategie życiowe? Jak organizmy dostosowują się do zmiennych warunków środowiska? Dlaczego organizmy formują kolonie lub rozmnażają się bezpłciowo?) z nowoczesnymi metodami badawczymi (hybrydyzacja RNA in situ, transkryptomika porównawcza, laserowa mikroskopia konfokalna, interferencja RNA). Ponadto prowadzimy również badania terenowe nad bioróżnorodności i ekologią słodkowodnych katenulidów na terenie Polski oraz podejmujemy próby hodowania rozmaitych gatunków tych zwierząt w warunkach laboratoryjnych z zamiarem wykorzystania ich w przyszłych projektach.

Realizowane projekty badawcze

Polskie Powroty NAWA nr BPN/PPO/2023/1/00002 „Ekologiczne i rozwojowe podstawy rozmnażania bezpłciowego i formowania kolonii u płazińców” (kierownik Ludwik Gąsiorowski)

Tematyka prac dyplomowych (więcej informacji)

W oparciu o obecnie realizowane projekty proponujemy następujące tematy prac dyplomowych:

Molekularna i morfologiczna charakteryzacja wybranych typów komórkowych u katenulida Stenostomum brevipharyngium
Taksonomia i różnorodność gatunków polskich katenulidów
Morfologia porównawcza rodzajów Stenostomum i Catenula
Ewolucja wybranych rodzin białkowych u płazińców

Ponadto osoby zainteresowane zoologią porównawczą bezkręgowców, które mają inne, już sprecyzowane zainteresowania badawcze zachęcamy do kontaktu z dr Ludwikiem Gąsiorowskim w celu omówienia alternatywnych projektów dyplomowych.

Dobór metod i szczegółowych zagadnień badawczych w projektach dyplomowych będzie uzgadniany indywidualnie w celu znalezienia projektu zgodnego z zainteresowaniami i oczekiwaniami poszczególnych osób.

Współpraca

Dr Christopher Laumer, Natural History Museum London
Dr Nicolas Bekkouche, Sorbonne University (link)
Department for Tissue Dynamics and Regeneration, Max Planck Institute for Multidisciplinary Sciences (link)

Przykładowe publikacje

Gąsiorowski, Ludwik; Chai, Chew; Rozanski, Andrei; Purandare, Gargi; Ficze, Fruzsina; Mizi, Athanasia; Wang, Bo; Rink, Jochen C.

Regeneration in the absence of canonical neoblasts in an early branching flatworm Journal Article

In: Nature Communications, vol. 16, no. 1, 2025, ISSN: 2041-1723.

Abstract | Links | BibTeX

@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}

}

Gąsiorowski, Ludwik

Evidence for Multiple Independent Expansions of Fox Gene Families Within Flatworms Journal Article

In: Journal of Molecular Evolution, 2025, ISSN: 1432-1432.

Abstract | Links | BibTeX

@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}

}

Gąsiorowski, Ludwik; Dittmann, Isabel Lucia; Brand, Jeremias N.; Ruhwedel, Torben; Möbius, Wiebke; Egger, Bernhard; Rink, Jochen C.

Convergent evolution of the sensory pits in and within flatworms Journal Article

In: BMC Biology, vol. 21, no. 1, pp. 266, 2023, ISSN: 1741-7007.

Abstract | Links | BibTeX

@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}

}

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.