New techniques for creating parthenogenetic larvae of the sea urchin Lytechinus pictus for gene expression studies

Abstract

Background: Sea urchins are model organisms for studying the spatial-temporal control of gene activity during development. The Southern California species, Lytechinus pictus, has a sequenced genome and can be raised in the laboratory from egg to egg in 4 to 5 months.

Results: Here, we present new techniques for generating parthenogenetic larvae of this species and include a gallery of photomicrographs of morphologically abnormal larvae that could be used for transcriptomic analysis.

Conclusions: Comparison of gene expression in parthenogenotes to larvae produced by fertilization could provide novel insights into gene expression controls contributed by sperm in this important model organism. Knowledge gained from transcriptomics of sea urchin parthenogenotes could contribute to parthenogenetic studies of mammalian embryos.

Keywords: embryo; ionophore activation; larvae; parthenogenesis; sea urchin.

Fig. 1.

Photomicrographs of morphologically abnormal parthenogenetic Lytechinus pictus plutei. Number on each frame is the days in culture. Red cells contain the pigment echinochrome. C-E are the same individual. The brown inclusion in E is the dead urchin rudiment. Developmental arrest at the 4-arm stage as seen in F is common. Shapes such as those seen in J-M and O, P are also common. The guitar shaped individual (Q) and R-T plutei all came from the same egg lot. In these four, the first two large posterior arms had fused to form one large arm with two side-by-side skeletal rods. Diameter of an individual larva varies from 200–300 um.