genome initiative
Emerging model for stem cell research
Macrostomum lignano is a free-living flatworm with high regeneration capacity facilitated by neoblasts, the stem cell system of the worm. It was first discovered in 1995 (described as a species in 2005) and since then has been the subject of research in several laboratories.
Due to its small size, short generation time, amenability to genetic manipulation and easy maintenance in laboratory conditions, M. lignano is a highly promising invertebrate experimental model whith a potential to become the next "C. elegans for stem cell research".
Sequencing and annotation of M. lignano genome has been initated at Hubrecht Institute (E. Berezikov) and currently is carried out by an informal consortium of several research groups.
| Size | adults 1-1.5 mm; hatchlings 300µm |
| Cell numbers | ~25.000 total; ~1600 neoblasts; ~400 S-phase, ~25 mitotic |
| Culture in laboratory | easy; feed on diatoms; kept in Petri dishes with algae and light |
| Transparency | highly transparent |
| Embryogenesis | 5 days; Spiral quartet |
| Generation time | 18 days |
| Reproduction | exclusively sexual; obligatory cross-fertilizing hermaphrodite; lay single cell eggs (100µm) |
| Accessibility to eggs | single eggs, whole year through |
| Nervous system | simple; brain with neuropile; 2 main lateral nerve cords; a pair of dorsal and ventral cords; 16 serotoninergic cells; limited number of peptidergic nerve cells |
| Muscle system | 3 layers, outer circular, inner longitudinal and diagonal muscles |
| Testes | continuous sperm production; surrounded by tunica cells; outer region with spermatogonia and spermatocytes; below spermatids; inside mature sperm. |
| Ovaries | oogonia and oocytes; |
| Morphological knowledge | well established |
| Plasticity | high; can endure extreme starvation (degrowth); testes size depends on group size |
| Regeneration potential | head regenerates posterior end with gonads; posterior end makes no new head |
| Phylogenetic position | basal platyhelminth; member of Lophotrochozoa |
| Stem Cell System | pluripotent |
| BrdU/H3 Staining | easy by soaking |
| RNA interference | easy by soaking |
| Amenable to forward and reverse genetics | yes |
| Genome size and availability | 600 MB, 5x coverage; early draft online |