Project description:Here we present LC-MS/MS proteomic datasets of Heliocidaris erythrogramma, Heliocidaris tuberculata, and Lytechinus variegatus eggs and larvae. We find dramatic proteomic differences likely associated with life history evolution and between developmental stages. This study provides a complimentary dataset to previous transcriptomic analyses of the same three sea urchin species.
Project description:Altered regulatory interactions during development likely underlie a large fraction of phenotypic diversity within and between species, yet identifying specific evolutionary changes remains challenging. Analysis of single-cell developmental transcriptomes from multiple species provides a powerful framework for unbiased identification of evolutionary changes in developmental mechanisms. Here, we leverage a “natural experiment” in developmental evolution in sea urchins, where a major life history switch recently evolved in the lineage leading to Heliocidaris erythrogramma, precipitating extensive changes in early development. Comparative analyses of scRNA-seq developmental time courses from H. erythrogramma and Lytechinus variegatus (representing the derived and ancestral states respectively) reveals numerous evolutionary changes in embryonic patterning. The earliest cell fate specification events, and the primary signaling center are co-localized in the ancestral dGRN but remarkably, in H. erythrogramma they are spatially and temporally separate. Fate specification and differentiation are delayed in most embryonic cell lineages, although in some cases, these processes are conserved or even accelerated. Comparative analysis of regulator-target gene co-expression is consistent with many specific interactions being preserved but delayed in H. erythrogramma, while some otherwise widely conserved interactions have likely been lost. Finally, specific patterning events are directly correlated with evolutionary changes in larval morphology, suggesting that they are directly tied to the life history shift. Together, these findings demonstrate that comparative scRNA-seq developmental time courses can reveal a diverse set of evolutionary changes in embryonic patterning and provide an efficient way to identify likely candidate regulatory interactions for subsequent experimental validation.
Project description:Sea urchins are a unique system for studying developmental transistions because of the stark differences between their bilateral larval and pentaradial adult body plans. Here, we use single cell RNA-sequencing to analyze the development of Heliocidaris erythrogramma (He), a sea urchin species with an accelerated, non-feeding mode of larval development. The sequencing time course extends from early embryogenesis to roughly a day before the onset of metamorphosis in He larvae, which is a period that has not been covered by previous datasets. We find that the non-feeding developmental strategy of He is associated with several changes in the specification of larval cell types compared to sea urchins with feeding larvae, such as the loss of a larva-specific skeletal cell population. Furthermore, the development of the larval and adult body plans in sea urchins may utilize largely different sets of regulatory genes. These findings lay the groundwork for extending existing developmental gene regulatory networks to cover additional stages of biphasic lifecycles.
Project description:We performed untargeted, high-resolution liquid chromatography-tandem mass spectrometry to generate lipidomic and proteomic profiles of eggs and larvae from three sea urchin species: the lecithotroph Heliocidaris erythrogramma, the closely-related planktotroph Heliocidaris tuberculata, and the more distantly-related planktotroph Lytechinus variegatus. We identify numerous molecular changes involving several previously undescribed physiological adaptations possibly associated with the evolution of lecithotrophic development including upregulated carbohydrate metabolism during embryonic development and long-term storage of maternally-derived diacylglycerol ether lipids for post-metamorphic survivorship. These findings demonstrate how mass spectrometry can enrich our understanding of life history evolution by identifying specific molecules associated with distinct life history strategies.
