The free-living flatworm Macrostomum lignano

Abstract

Macrostomum lignano is a free-living flatworm that is emerging as an attractive experimental animal for research on a broad range of biological questions. One feature setting it apart from other flatworms is the successful establishment of transgenesis methods, facilitated by a steady supply of eggs in the form of single-cell zygotes that can be readily manipulated. This, in combination with the transparency of the animal and its small size, creates practical advantages for imaging and fluorescence-activated cell sorting in studies related to stem cell biology and regeneration. M. lignano can regenerate most of its body parts, including the germline, thanks to the neoblasts, which represent the flatworm stem cell system. Interestingly, neoblasts seem to have a high capacity of cellular maintenance, as M. lignano can survive up to 210 Gy of γ-irradiation, and partially offset the negative consequence of ageing. As a non-self-fertilizing simultaneous hermaphrodite that reproduces in a sexual manner, M. lignano is also used to study sexual selection and other evolutionary aspects of sexual reproduction. Work over the past several years has led to the development of molecular resources and tools, including high-quality genome and transcriptome assemblies, transcriptional profiling of the germline and somatic neoblasts, gene knockdown, and in situ hybridization. The increasingly detailed characterization of this animal has also resulted in novel research questions, such as bio-adhesion based on its adhesionrelease glands and genome evolution due to its recent whole-genome duplication.

Large-scale phylogenomics of the genus Macrostomum (Platyhelminthes) reveals cryptic diversity and novel sexual traits

“…After the Catenulida, the Macrostomorpha are the earliest-branching lineage of Platyhelminthes (Laumer et al 2015), giving Macrostomum an interesting taxonomic position, and representing a valuable point of comparison to other well-studied flatworms such as members of the Tricladida and the parasitic Neodermata. The genus contains the model organism M. lignano (Ladurner et al 2005; Wudarski et al 2020), which, in part due to its high transparency and experimental amenability, is used for the study of a variety of biological topics, including aging (Mouton et al 2018), bioadhesion (Lengerer et al 2016; Wunderer et al 2019), regeneration and stem cells (Egger et al 2006; Grudniewska et al 2016; Lengerer et al 2016), and sexual selection (Schärer et al 2011; Marie-Orleach et al 2020). A rich experimental and genomic toolset is available for M. lignano , including in situ hybridization, RNA interference, transgenesis, a range of transcriptomes, and a sequenced genome (Pfister et al 2007, 2008; Wasik et al 2015; Wudarski et al 2017).…”

Computational analysis of spliced leader trans-splicing in the regenerative flatworm <i>Macrostomum lignano</i> reveals its prevalence in conserved and stem cell related genes

“…Macrostomum lignano is the only flatworm species for which a method for stable transgenesis is available so far. The worm also has a number of features allowing for efficient cell lineage tracing and phenotype screening, which makes M. lignano an attractive model to study a wide range of biological processes (Grudniewska et al, 2016;Wudarski et al, 2017Wudarski et al, , 2019Wudarski et al, , 2020. Well-annotated M. lignano genome and transcriptome assemblies were re cently published (Wudarski et al, 2017;Grudniewska et al, 2018).…”

Frequent origins of traumatic insemination involve convergent shifts in sperm and genital morphology

“…In summary, our work clearly highlights that the genus Macrostomum is a promising taxon for the study of sperm form and function, combining a high morphological diversity with a large number of evolutionary origins, and additionally offering many desirable laboratory animal characteristics and an increasing availability of genetic tools [100–102]. Macrostomum will also afford more in-depth investigation of HI and shed light on this intriguing behaviour’s origin and function.…”