Chromosome fission or duplication in Macrostomum lignano (Macrostomorpha, Plathelminthes) - remarks on chromosome numbers in 'archoophoran turbellarians'

Egger, Bernhard; Ishida, Sachiko

doi:10.1111/j.1439-0469.2005.00300.x

Cited by 25 publications

(33 citation statements)

References 35 publications

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“…2A), suggesting a high frequency of genomic duplications (peaks 3 and 4). Indeed M. lignano has four (2n = 8) sets of chromosomes in comparison with three (2n = 6) sets of chromosomes found in the majority of other Macrostomum species studied to date (30), suggesting a potential chromosomal duplication. The proportion of duplicated sequences was higher, however, than what one would expect based on the duplication of one small chromosomal pair.…”

Section: Resultsmentioning

confidence: 99%

Genome and transcriptome of the regeneration-competent flatworm, Macrostomum lignano

Wasik

Gurtowski

Zhou

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

100

138

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The free-living flatworm, Macrostomum lignano has an impressive regenerative capacity. Following injury, it can regenerate almost an entirely new organism because of the presence of an abundant somatic stem cell population, the neoblasts. This set of unique properties makes many flatworms attractive organisms for studying the evolution of pathways involved in tissue self-renewal, cellfate specification, and regeneration. The use of these organisms as models, however, is hampered by the lack of a well-assembled and annotated genome sequences, fundamental to modern genetic and molecular studies. Here we report the genomic sequence of M. lignano and an accompanying characterization of its transcriptome. The genome structure of M. lignano is remarkably complex, with ∼75% of its sequence being comprised of simple repeats and transposon sequences. This has made high-quality assembly from Illumina reads alone impossible (N50 = 222 bp). We therefore generated 130× coverage by long sequencing reads from the Pacific Biosciences platform to create a substantially improved assembly with an N50 of 64 Kbp. We complemented the reference genome with an assembled and annotated transcriptome, and used both of these datasets in combination to probe gene-expression patterns during regeneration, examining pathways important to stem cell function.F latworms belong to the superphylum Lophotrochozoa, a vast assembly of protostome invertebrates (1, 2) (Fig. 1A). The evolutionary relationships within this clade are poorly resolved and the specific position of flatworms is currently debated (3, 4). Flatworms have attracted scientific attention for centuries because of their astonishing regenerative capabilities (5, 6), as well as their ability to "degrow" in a controlled way when starved (7). As far back as the early 1900s, Thomas Morgan recognized the potential of flatworms and conducted a number of fascinating regeneration experiments on planarian flatworms before his focus shifted to Drosophila genetics (8).Macrostomum lignano is (Fig. 1B), a free-living, regenerating flatworm isolated from the coast of the Mediterranean Sea. M. lignano is an obligatorily cross-fertilizing simultaneous hermaphrodite (9) that belongs to Macrostomorpha, whereas the other often-studied freeliving flatworms and human parasitic flatworms all belong to clades that are potentially more derived (less ancestral) in comparison with Macrostomorpha (2) (Fig. 1C).Many flatworms can regenerate nearly their entire body or amputated organs. This regenerative capacity is thought to be attributable to the presence of somatic stem cells, termed neoblasts (10, 11). In Schmidtea mediterranea (planarian flatworm), even a single transplanted neoblast has the ability to rescue, regenerate, and change the genotype of a fatally irradiated worm (12). M. lignano can regenerate every tissue, with the exception of the head region containing the brain (13,14).Neoblasts in M. lignano ( Fig. 1 D and E), in contrast to most vertebrate somatic stem cells, are plentiful, making up about ...

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Section: Resultsmentioning

confidence: 99%

Genome and transcriptome of the regeneration-competent flatworm, Macrostomum lignano

Wasik

Gurtowski

Zhou

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

100

138

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“…When starting new dishes, about 40 adult worms were put into a new, clean dish and algal f/2 suspension was added until the dish was half-filled. For the preparation of algae see Egger & Ishida (2005).…”

Section: Methodsmentioning

confidence: 99%

A cultivable acoel species from the Mediterranean, Aphanostoma pisae sp. nov. (Acoela, Acoelomorpha)

Zauchner¹,

Salvenmoser²,

Egger³

2015

Zootaxa

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Aphanostoma pisae sp. nov. is an interstitial acoel found at the coast of the Liguric Sea in Pisa (Tuscany, Italy). It belongs to the large family Isodiametridae, characterised by a male copulatory organ with a cylindrical shape and non-anastomising longitudinal muscle fibers. It is the first recognised species of Aphanostoma in the Mediterranean and it can occur in great abundance at its type locality (several hundred specimens in a spoonful of sand). A. pisae has been cultured in the laboratory for several years with diatoms for food. The embryonic development lasts for just under two days at 20 °C.We provide a description of the new species using live observations, light and electron microscopy of sagittal sections and stainings of the filamentous actin and the serotonergic nervous system, and we discuss and update the genus diagnoses of the genera Aphanostoma and Praeconvoluta.

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“…The chromosome number of M. lignano is 8 (2n), two more than in most other macrostomid species studied so far. This may indicate that in M. lignano one chromosome pair has either undergone duplication or fission (Egger and Ishida, 2005). The reproductive system consists of paired testes located laterally in the central region of the animal and posterior to them there are paired ovaries and developing eggs.…”

Section: Morphologymentioning

confidence: 97%

“…lignano is very easy to maintain in the laboratory. For long-term cultures animals are generally kept in glass petri dishes in f/2, a nutrient-enriched artificial seawater medium at a salinity of 32‰ (Andersen et al, 2007;Egger and Ishida, 2005). These dishes are kept in a climate chamber at a constant temperature (20°C), with a 14 h:10 h or 13:11 h light:dark cycle and at 60% relative humidity (Schärer et al, 2007a;Egger and Ishida, 2005).…”

Section: Culturing Macrostomum Lignanomentioning

confidence: 99%

“…For long-term cultures animals are generally kept in glass petri dishes in f/2, a nutrient-enriched artificial seawater medium at a salinity of 32‰ (Andersen et al, 2007;Egger and Ishida, 2005). These dishes are kept in a climate chamber at a constant temperature (20°C), with a 14 h:10 h or 13:11 h light:dark cycle and at 60% relative humidity (Schärer et al, 2007a;Egger and Ishida, 2005). In the laboratory, M. lignano can survive in artificial seawater from salinities as low as 1‰ to as high as 40‰ Temperatures may vary between refrigerator conditions (4°C) to 40°C or more, reflecting the capacity to survive cold winter environments and the heat of the sand surface in summer.…”

Section: Culturing Macrostomum Lignanomentioning

confidence: 99%

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The Stem Cell System of the Basal Flatworm Macrostomum lignano

et al. 2008

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The scope of this review is to introduce the free-living flatworm Macrostomum lignano as an excellent model organism to address questions of platyhelminth stem cell biology. First, we sketch the historical origin of flatworm stem cell research. Second, we introduce M. lignano, and summarize the main advantages that we think it has over the classical planarian model. Third, we give a short summary of the simple culture techniques. Fourth, we give a detailed overview over its morphology and embryology as far as it is relevant for stem cell biology. Fifth, we summarize our main findings on stem cell biology, with respect to the identification of neoblasts, their distribution and number. We describe the ultrastructure of neoblasts, their dynamics and gene expression. Sixth, we outline ways to study sex allocation by means of stem cell labeling and manipulation. Last, we highlight the regeneration capacity of this species and link it to the stem cell system. We conclude that M. lignano is a highly suitable model organism to gain knowledge about flatworm stem cells and to provide insight into stem cell systems of higher organisms, including humans.

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Chromosome fission or duplication in Macrostomum lignano (Macrostomorpha, Plathelminthes) - remarks on chromosome numbers in 'archoophoran turbellarians'

Cited by 25 publications

References 35 publications

Genome and transcriptome of the regeneration-competent flatworm, Macrostomum lignano

Genome and transcriptome of the regeneration-competent flatworm, Macrostomum lignano

A cultivable acoel species from the Mediterranean, Aphanostoma pisae sp. nov. (Acoela, Acoelomorpha)

The Stem Cell System of the Basal Flatworm Macrostomum lignano

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