The Demosponge Amphimedon queenslandica: Reconstructing the Ancestral Metazoan Genome and Deciphering the Origin of Animal Multicellularity

Abstract

INTRODUCTIONSponges are one of the earliest branching metazoans. In addition to undergoing complex development and differentiation, they can regenerate via stem cells and can discern self from nonself ("allorecognition"), making them a useful comparative model for a range of metazoan-specific processes. Molecular analyses of these processes have the potential to reveal ancient homologies shared among all living animals and critical genomic innovations that underpin metazoan multicellularity. Amphimedon queenslandica (Porifera, Demospongiae, Haplosclerida, Niphatidae) is the first poriferan representative to have its genome sequenced, assembled, and annotated. Amphimedon exemplifies many sessile and sedentary marine invertebrates (e.g., corals, ascidians, bryozoans): They disperse during a planktonic larval phase, settle in the vicinity of conspecifics, ward off potential competitors (including incompatible genotypes), and ensure that brooded eggs are fertilized by conspecific sperm. Using genomic and expressed sequence tag (EST) resources from Amphimedon, functional genomic approaches can be applied to a wide range of ecological and population genetic processes, including fertilization, dispersal, and colonization dynamics, host-symbiont interactions, and secondary metabolite production. Unlike most other sponges, Amphimedon produce hundreds of asynchronously developing embryos and larvae year-round in distinct, easily accessible brood chambers. Embryogenesis gives rise to larvae with at least a dozen cell types that are segregated into three layers and patterned along the body axis. In this article, we describe some of the methods currently available for studying A. queenslandica, focusing on the analysis of embryos, larvae, and post-larvae.

Draft Genomes Shed Light on the Dual Bacterial Symbiosis that Dominates the Microbiome of the Coral Reef Sponge Amphimedon queenslandica

“…Reduced sulfur compounds might not be only symbiotic in origin, but could also be environmentally derived. The habitat of A. queenslandica on Heron Island reef is characterized by fine sand patches and often heavy siltation (Degnan et al, 2008). During times of high sand movement or high silt deposition, adult sponges can easily be partially buried to the extent that they may be subject to anoxic conditions with high sulfide concentrations.…”

Origin of the Animal Circadian Clock: Diurnal and Light-Entrained Gene Expression in the Sponge Amphimedon queenslandica

“…Embryogenesis occurs in the dark, in brood chambers located basally inside the maternal adult sponge (Degnan et al, 2008). Mature larvae emerge into the full sunlight between 12 and 4 p.m. (Figure 2), and subsequent settlement through to the first 12 h of metamorphosis typically occurs overnight in the dark .…”

Ontogenetic Changes in the Bacterial Symbiont Community of the Tropical Demosponge Amphimedon queenslandica: Metamorphosis Is a New Beginning

“…The demosponge Amphimedon queenslandica (Hooper and Van Soest, 2006) lives on the intertidal reef flat of tropical Pacific coral reefs, and has a well-characterized life cycle that comprises typical pelagic larva and benthic adult stages (reviewed in Degnan et al, 2008Degnan et al, , 2015. It is particularly tractable for investigating host-symbiont interactions through the entire life cycle, as it houses asynchronously developing embryos and larvae through much of the year, in easily accessible brood chambers (Leys and Degnan, 2002;Degnan et al, 2005Degnan et al, , 2015Leys et al, 2008).…”