April’s issue of Cold Spring Harbor Protocols introduces, well, re-introduces two longstanding experimental model systems, the snail (Ilyanassa obsoleta) and the leech (Helobdella).

The use of Ilyanassa in the laboratory dates back to the 1890’s, and it was a favorite of Thomas Hunt Morgan’s in the 1930’s. As a member of the Lophotrochozoa, a group made up of nearly one third of the animal phyla, the snail exhibits a spiralian developmental program. In addition to its use to study spiral cleavage, Ilyanassa is also used to study asymetric cell division and other phenomena:

It is an important model for studies of metamorphosis, the ecology of parasitism, and imposex, a striking morphological disorder caused by the disruption of sexual endocrine systems by environmental contaminants. Ilyanassa is also useful for studies of comparative neurobiology.

Protocols are provided for Obtaining Embryos, Induction of Larval Metamorphosis, Fixation, Isolation of Genomic DNA, Protein Isolation, and Pressure Injection.

In the 1870’s, C.O. Whitman, director of the MBL at Woods Hole used a local leech species for developmental biology studies. Gunther Stent’s lab used leeches for neurobiology research in the 1970’s. Like Ilyanassa, leeches are Lophotrochozoans and exhibit spiral cleavage and thus are useful species for studying this poorly understood program of development. Leeches are also used for the study of segmentation, regeneration and neurogenesis.

Protocols are provided for Handling Embryos, Microinjection, Devitellinization, Silver Staining, Immunohistochemistry, In Situ Hybridization, and Preparation for Microscopy.

For more emerging (and re-emerging) model systems, these articles and others like them are collected in Volume 1 of a new laboratory manual series.