November’s issue of CSH Protocols continues to expand our coverage of emerging model organisms, with three sets of articles on the Tomato (Solanum lycopersicum), Comb Jellies (Ctenophora) and the Blind Mexican Cave Fish (Astyanax mexicanus).

The tomato has obvious agricultural importance as a research system, but beyond that, it has many characteristics such as fleshy fruit, a sympodial shoot and compound leaves, which are lacking in other plant model systems like rice or Arabidopsis. The variety among the thirteen recognized wild tomato species and the differing phenotypes exhibited make it an interesting organism for the study of genetic variation and evolution. Protocols are available for growth, performing crosses, grafting and transformation of tomatoes.

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Their biological features and phylogenetic placement have long made Comb Jellies an attractive experimental species. Recently, their role as an invasive species has led to an increased interest and study in ctenophores. Protocols for spawning and embryo collection, whole-mount antibody staining, whole-mount in situ hybridization, extraction of DNA, and extraction of RNA are available.

The perpetual darkness of the cave environment has had a variety of effects on the Blind Mexican Cave Fish, ranging from reduced eyes and pigmentation to increased metabolism. A. mexicanus is particularly valuable because the species is interfertile with eyed sister fish living in streams on the surface. This makes for a superb experimental system for delving into the genetic, developmental and evolutionary basis of a wide variety of traits. Protocols are available for determining the gender, breeding, in vitro fertilization and handling eggs and fry of A. mexicanus.

New organisms will continue to be added over the next several months, but if you don’t want to wait that long, the entire series is being collected in a new laboratory manual, Emerging Model Organisms that is available this month.

Emerging Model Organisms