Use of sea stars to study basic reproductive processes

Echinoderms are closely related to chordates and comprise a major group of invertebrate deuterostomes. They are broadcast spawners and as such, each female accumulates millions of eggs and oocytes. These cells are readily isolated, and are often large, clear, and surrounded by accessory cells and extracellular coverings that do not prevent access to the oocyte. Sea star oocytes are stored in prophase of meiosis, and since the natural meiotic stimulus has been identified as 1-methyladenine, these cells can be induced to complete meiotic maturation as individuals, or synchronously en masse. Microinjection and culture of these cells is feasible using quantitative or repetitive methods so that hundreds of oocytes and eggs can be modified each hour. Experimentation on this organism is extensive over a rich history of reproductive and developmental biology so that new investigators can easily incorporate this organism into their repertoire of research. This review will highlight the fundamental protocols to enable a new investigator to perform an array of approaches on this organism, including oocyte isolation, microinjection, and even single cell quantitative PCR.