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Ilyanassa obsoleta is a marine gastropod that is a long-standing and very useful model for studies of embryonic development. It is especially important as a model for the spiralian development program, a distinctive mode of early development shared by a large group of animal phyla, but poorly understood. Ilyanassa adults are readily obtainable and easy to keep in the laboratory, and they produce large numbers of embryos throughout most of the year. The embryos are amenable to classic embryological manipulation techniques as well as a growing number of molecular approaches. In this article, we present an overview of aspects of its biology and use as a model organism.

INTRODUCTIONThe marine gastropod Ilyanassa obsoleta is a long-standing and very useful model for studies of embryonic development. It is an especially important model for spiralian development, and for studies of asymmetric cell division. The embryos are amenable to classic embryological manipulation techniques, as well as a growing number of molecular approaches. Ilyanassa is also an important model for studies of metamorphosis, the ecology of parasitism, the effects of environmental contaminants on morphology and sexual function, and comparative neurobiology. Intracellular microinjection is an important tool, especially for lineage tracing and perturbations of specific genes by knockdown approaches and synthetic mRNA injections. Two methods for the introduction of lineage tracers into particular cells are routine in Ilyanassa. Iontophoresis of charged molecules, such as fluorophore-dextran conjugates can be accomplished using a simply built current generator. Injection of an oil-based solution containing the fluorescent probe 1,1-dioctadecyl-3,3,3′,3′-tetramethyl indocarbocyanine perchlorate (DiI) is also straightforward. However, injection of oil-based solutions and iontophoresis have not been useful for delivering water-soluble reagents to perturb gene function, and pressure injection of aqueous solutions has been more challenging. This protocol describes a recently optimized procedure for the pressure injection of aqueous solutions into Ilyanassa embryos and zygotes with high rates of survival and normal development. The key parameters seem to be the injection needles, injection media, and the stage of injected embryos.

The marine gastropod Ilyanassa obsoleta is a long-standing and very useful model for studies of embryonic development. It is an especially important model for spiralian development, and for studies of asymmetric cell division. The embryos are amenable to classic embryological manipulation techniques, as well as a growing number of molecular approaches. Ilyanassa is also an important model for studies of metamorphosis, the ecology of parasitism, the effects of environmental contaminants on morphology and sexual function, and comparative neurobiology. Ilyanassa embryos are particularly well suited for RNA and protein localization studies because of the relatively large cells and favorable properties for imaging. This protocol describes how to fix and store Ilyanassa embryos and larvae for use in whole-mount in situ hybridization and immunohistochemical studies.

INTRODUCTIONThe marine gastropod Ilyanassa obsoleta is a long-standing and very useful model for studies of embryonic development. It is an especially important model for spiralian development, and for studies of asymmetric cell division. The embryos are amenable to classic embryological manipulation techniques as well as a growing number of molecular approaches. Ilyanassa is also an important model for studies of metamorphosis, the ecology of parasitism, the effects of environmental contaminants on morphology and sexual function, and comparative neurobiology. This protocol describes the procedure for extracting protein from Ilyanassa embryos for use in techniques such as Western blotting or two-dimensional (2D) gel electrophoresis.

The marine gastropod Ilyanassa obsoleta is a long-standing and very useful model for studies of embryonic development. It is an especially important model for spiralian development, and for studies of asymmetric cell division. The embryos are amenable to classic embryological manipulation techniques as well as a growing number of molecular approaches. Ilyanassa is also an important model for studies of metamorphosis, the ecology of parasitism, the effects of environmental contaminants on morphology and sexual function, and comparative neurobiology. Ilyanassa adults are readily obtainable and easy to keep in the laboratory, and they can produce high-quality embryos nearly year-round in the laboratory. After hatching from capsules, larval Ilyanassa can be maintained in culture, feeding on single-celled algae. The larvae will become competent to undergo metamorphosis after approximately 3 wk in culture. Metamorphosis can be induced artificially by treating with either the neurotransmitter serotonin or the nitric oxide synthase inhibitor 7-nitroindazole. Both of these reagents have been shown to induce metamorphosis in75% of larvae within 48 h. This protocol describes the induction of metamorphosis in snail larvae.

INTRODUCTIONThe marine gastropod Ilyanassa obsoleta is a long-standing and very useful model for studies of embryonic development. It is an especially important model for spiralian development, and for studies of asymmetric cell division. The embryos are amenable to classic embryological manipulation techniques as well as a growing number of molecular approaches. Ilyanassa is also an important model for studies of metamorphosis, the ecology of parasitism, the effects of environmental contaminants on morphology and sexual function, and comparative neurobiology. Ilyanassa is host to several species of parasitic trematode worms, so care must be taken to avoid contamination of Ilyanassa genomic DNA with that of the parasites. The easiest way to avoid this contamination is to isolate DNA from veliger larvae, which are not parasitized. This also avoids other problems that can be encountered when isolating DNA from adult mollusc tissues, such as the presence of large amounts of polysaccharides. This protocol describes the isolation of genomic DNA from Ilyanassa larvae.

INTRODUCTIONThe marine gastropod Ilyanassa obsoleta is a long-standing and very useful model for studies of embryonic development. It is an especially important model for spiralian development, and for studies of asymmetric cell division. The embryos are amenable to classic embryological manipulation techniques as well as a growing number of molecular approaches. Ilyanassa is also an important model for studies of metamorphosis, the ecology of parasitism, the effects of environmental contaminants on morphology and sexual function, and comparative neurobiology. Ilyanassa adults are readily obtainable and easy to keep in the laboratory. Although the normal spawning season for Ilyanassa is during early summer, they can produce high-quality embryos nearly year-round in the laboratory. Snails collected in the late fall, winter, or spring can be induced to deposit zygotes before the natural spawning season by warming them to room temperature, and snails collected before the natural spawning season can be made to postpone zygote deposition until needed (up to at least 6 mo) by maintaining them in tanks in a cold room at 4°C-8°C. This protocol describes how to induce embryo production in Ilyanassa snails, collect the embryos, and rear them to the stage required for study.

INTRODUCTIONThe marine gastropod Ilyanassa obsoleta is a long-standing and very useful model for studies of embryonic development. It is an especially important model for spiralian development, and for studies of asymmetric cell division. The embryos are amenable to classic embryological manipulation techniques, as well as a growing number of molecular approaches. Ilyanassa is also an important model for studies of metamorphosis, the ecology of parasitism, the effects of environmental contaminants on morphology and sexual function, and comparative neurobiology. Ilyanassa embryos are particularly well suited for RNA and protein localization studies because of the relatively large cells and favorable properties for imaging. This protocol describes how to fix and store Ilyanassa embryos and larvae for use in whole-mount in situ hybridization and immunohistochemical studies.

INTRODUCTIONThe marine gastropod Ilyanassa obsoleta is a long-standing and very useful model for studies of embryonic development. It is an especially important model for spiralian development, and for studies of asymmetric cell division. The embryos are amenable to classic embryological manipulation techniques as well as a growing number of molecular approaches. Ilyanassa is also an important model for studies of metamorphosis, the ecology of parasitism, the effects of environmental contaminants on morphology and sexual function, and comparative neurobiology. Ilyanassa adults are readily obtainable and easy to keep in the laboratory, and they can produce high-quality embryos nearly year-round in the laboratory. After hatching from capsules, larval Ilyanassa can be maintained in culture, feeding on single-celled algae. The larvae will become competent to undergo metamorphosis after ~3 wk in culture. Metamorphosis can be induced artificially by treating with either the neurotransmitter serotonin or the nitric oxide synthase inhibitor 7-nitroindazole. Both of these reagents have been shown to induce metamorphosis in >75% of larvae within 48 h. This protocol describes the induction of metamorphosis in snail larvae.

INTRODUCTIONIlyanassa obsoleta is a marine gastropod that is a long-standing and very useful model for studies of embryonic development. It is especially important as a model for the spiralian development program, a distinctive mode of early development shared by a large group of animal phyla, but poorly understood. Ilyanassa adults are readily obtainable and easy to keep in the laboratory, and they produce large numbers of embryos throughout most of the year. The embryos are amenable to classic embryological manipulation techniques as well as a growing number of molecular approaches. In this article, we present an overview of aspects of its biology and use as a model organism.