Ilyanassa as a model system

The Ilyanassa embryo has advantages for the study of asymmetric cell division as well as classic spiralian development, making it a favorable system for examining both of these phenomena. [see Research]


A number of practical and experimental advantages potentiate these natural attributes, making Ilyanassa an important emerging model system.  It is amenable to a variety of experimental techniques, including an array of classical embryological manipulations.  Studies using these methods have defined the contribution of all cells in the early embryo, by lineage tracing (Render, 1991; 1997) and cell ablation (Crampton, 1896; Clement, 1952, 1962, 1967, 1976).  Recently, methods have been developed  for specific knockdown of particular genes in development (Rabinowitz et al, 2008), laying the foundation for mechanistic molecular studies of spiralian development.  We have also found that the Ilyanassa embryo is exceptionally good material for imaging events during cell division. The cells of the early embryo are large, and have excellent properties for imaging.


Ilyanassa is also a very practical lab animal.  The adults are abundant at many locations on the east and west coasts of North America, and close relatives are found all over the world.  They can be easily collected at low tide, or ordered from suppliers like the Marine Resources Center at the Marine Biological Laboratory in Woods Hole, Massachusetts.  Unlike most marine invertebrates, Ilyanassa can be relied on to produce high-quality embryos nearly year round, even though its normal spawning season is in the early summer.  This is because animals collected in the late fall can be induced to lay eggs 6-7 months before the natural spawning season, and animals collected before the natural spawning season can be kept from laying eggs until needed (up to at least 6 months).  The animals are hardy, and can be maintained in simple saltwater aquaria, even in inland laboratories.


Clement, A. C. (1952). Experimental studies on germinal localization in Ilyanassa. I. The role of the polar lobe in determination of the cleavage pattern and its influence in later development. Journal of Experimental Zoology 132, 427-446.


Clement, A. C. (1967). The embryonic value of micromeres in Ilyanassa obsoleta, as determined by deletion experiment. I. The first quartet cells. Journal of Experimental Zoology 166, 77-88.


Clement, A. C. (1976). Cell Determination and Organogenesis in Molluscan Development - Reappraisal Based On Deletion Experiments in Ilyanassa. American Zoologist 16, 447-453.


Crampton, H. E. (1896). Experimental studies on gastropod development. Roux' Arch. Entw.-mech 3, 1-19.


Rabinowitz, J. S., Chan, X. Y., Kingsley, E. P., Duan, Y. and Lambert, J. D. (2008). Nanos Is Required in Somatic Blast Cell Lineages in the Posterior of a Mollusk Embryo. Curr Biol.


Render, J. (1991). Fate Maps of the 1st Quartet Micromeres in the Gastropod Ilyanassa obsoleta. Development 113, 495-501.


Render, J. (1997). Cell fate maps in the Ilyanassa obsoleta embryo beyond the third division. Developmental Biology 189, 301-310.