Project description:Marine pelagic larvae from throughout the animal kingdom use a hierarchy of environmental cues to identify a suitable benthic habitat on which to settle and metamorphose into the reproductive phase of the life cycle. The majority of larvae are induced to settle by biochemical cues and many species have long been known to preferentially settle in the dark. Combined, these data suggest that larval responses to light and biochemical cues may be linked, but this is yet to be explored at the molecular level. Here, we track vertical position of larvae of the sponge Amphimedon queenslandica to show that they descend to the benthos at twilight, by which time they are competent to respond to biochemical cues, consistent with them naturally settling in the dark. We then conduct larval settlement assays under three different light regimes (natural day-night, constant dark or constant light), and use transcriptomics on individual larvae to identify candidate molecular pathways underlying the different settlement responses that we observe. We find that constant light prevents larval settlement in response to biochemical cues, likely via actively repressing chemostransduction; this is consistent with the sustained upregulation of a photosensory cryptochrome and two putative inactivators of G-protein signalling in the constant light only. We hypothesise that photo- and chemosensory systems may be hierarchically integrated into ontogeny to regulate larval settlement via nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) signalling in this sponge that belongs to one of the earliest branching of the extant animal lineages.
Project description:The larval brain of Ciona intestinalis has similar architecture to that of vertebrates, but is only composed of approximately 330 cells. Transgenic embryos that carried Ci-beta-tubulin(promoter)::Kaede exhibited robust Kaede expression in the larval brain. Kaede-expressing cells were isolated, and their transcriptome was compared with that of cells that did not express Kaede using an oligonucleotide-based microarray. Our analysis identified 565 candidate genes that were preferentially expressed in the larval brain, 77 of which have previously been reported to be brain-related. The 565 genes included transcription factors, such as Otx, en, Pax3/7, Prop-A, Lhx1, Six3/6, Unc4-A, FoxC, and DMRT1; and signal transduction molecules, such as FGF4/5/6, Hedgehog1, Hedgehog2, patched, Fringe1, and Dkk3. Nearly 30 of the identified genes coded for receptors for neurotransmitters, neuropeptides or hormone pepetides. In addition, 15 genes encoded neuropeptides and hormone peptides, five of which were novel. Our catalog of genes that are expressed in the Ciona larval brain provides a foundation for future studies exploring the complex gene regulatory networks that mediate chordate brain development and function. Two samples (Brain vs Cells without Brain),Two biological replicates,Dye Swap design
Project description:The larval brain of Ciona intestinalis has similar architecture to that of vertebrates, but is only composed of approximately 330 cells. Transgenic embryos that carried Ci-beta-tubulin(promoter)::Kaede exhibited robust Kaede expression in the larval brain. Kaede-expressing cells were isolated, and their transcriptome was compared with that of cells that did not express Kaede using an oligonucleotide-based microarray. Our analysis identified 565 candidate genes that were preferentially expressed in the larval brain, 77 of which have previously been reported to be brain-related. The 565 genes included transcription factors, such as Otx, en, Pax3/7, Prop-A, Lhx1, Six3/6, Unc4-A, FoxC, and DMRT1; and signal transduction molecules, such as FGF4/5/6, Hedgehog1, Hedgehog2, patched, Fringe1, and Dkk3. Nearly 30 of the identified genes coded for receptors for neurotransmitters, neuropeptides or hormone pepetides. In addition, 15 genes encoded neuropeptides and hormone peptides, five of which were novel. Our catalog of genes that are expressed in the Ciona larval brain provides a foundation for future studies exploring the complex gene regulatory networks that mediate chordate brain development and function.
Project description:Larval settlement and metamorphosis is a vital transition period for marine invertebrates and can have far-reaching effects on the ecology and evolution of a species. To explore the molecular mechanisms of this critical process in a non-model organism, the tropical abalone Haliotis asinina, we employed cDNA microarray methods. By comparing gene expression profiles through mid to late larval development and metamorphosis, we identified 144 genes as likely candidates for a role in competence and/or metamorphosis. Gene characterization showed that ~60% of these were significantly similar to previously described genes from other taxa, while ~40% had no significant similarities to any known genes. A high 49.3% of genes were gastropod- or abalone-specific, but none appear to be Lophotrochozoan-specific, despite the fact that metamorphosis is thought to have had a separate origin in this group. Based on temporal expression profiles, the differentially expressed larval and postlarval genes can be clustered into 5 categories that reveal there are strikingly different transcriptional patterns occurring during this phase of development. Some classes of gene activation are contingent upon exogenous cues and correlate with the initiation of settlement and metamorphosis. Importantly, there is also extensive gene activity associated with the endogenous attainment of competence, which occurs prior to, and independent of, the exogenous induction of settlement. Our results show that as the haliotid veliger larva matures, it requires the coordinated regulation of temporally different batteries of genes involved in a wide range of physiological and developmental processes associated with colonisation of the benthos. Although the signalling pathways operating at metamorphosis may be conserved across the animal kingdom, it appears they are regulating the expression of novel genes specific to abalone, gastropods and molluscs during H. asinina metamorphosis. Keywords: timecourse; metamorphosis; marine ecology
2008-10-04 | GSE13039 | GEO
Project description:Behavioral Genomics of Porites astreoides larval preference for settlement cues
| PRJNA531192 | ENA
Project description:Microbiome acquisition during larval settlement of the barnacle Semibalanus balanoides
Project description:Larval settlement and metamorphosis is a vital transition period for marine invertebrates and can have far-reaching effects on the ecology and evolution of a species. To explore the molecular mechanisms of this critical process in a non-model organism, the tropical abalone Haliotis asinina, we employed cDNA microarray methods. By comparing gene expression profiles through mid to late larval development and metamorphosis, we identified 144 genes as likely candidates for a role in competence and/or metamorphosis. Gene characterization showed that ~60% of these were significantly similar to previously described genes from other taxa, while ~40% had no significant similarities to any known genes. A high 49.3% of genes were gastropod- or abalone-specific, but none appear to be Lophotrochozoan-specific, despite the fact that metamorphosis is thought to have had a separate origin in this group. Based on temporal expression profiles, the differentially expressed larval and postlarval genes can be clustered into 5 categories that reveal there are strikingly different transcriptional patterns occurring during this phase of development. Some classes of gene activation are contingent upon exogenous cues and correlate with the initiation of settlement and metamorphosis. Importantly, there is also extensive gene activity associated with the endogenous attainment of competence, which occurs prior to, and independent of, the exogenous induction of settlement. Our results show that as the haliotid veliger larva matures, it requires the coordinated regulation of temporally different batteries of genes involved in a wide range of physiological and developmental processes associated with colonisation of the benthos. Although the signalling pathways operating at metamorphosis may be conserved across the animal kingdom, it appears they are regulating the expression of novel genes specific to abalone, gastropods and molluscs during H. asinina metamorphosis. Keywords: timecourse; metamorphosis; marine ecology Each microarray slide contained a different combination of 2 of the 9 developmental stages used in the experiment (66 hpf, 78 hpf, 90 hpf, 108 hpf, 120 hpf, 144 hpf, 12 hpi, 24 hpi, 48 hpi). Each developmental stage was subjected to 4 hybridisations â amounting to 4 technical replicates per stage - in a loop design (Churchill 2002; Oleksiak et al. 2002). This design led to raw data consisting of 72 measurements - 9 stages with 8 replicates (including 2 replicates per chip) - for each of 5541 spots.
Project description:Scleractinian corals are the major builders of the complex structural framework of coral reefs. They live in tropical waters around the globe where they are frequently exposed to potentially harmful ultraviolet radiation (UVR). Coral eggs and early embryonic stages are thought to be the most sensitive life stages of corals to UVR given that they are highly buoyant and remain near the sea surface for prolonged periods of time. Here we analyzed gene expression changes in different larval stages of the Caribbean coral Montastraea faveolata to natural levels of UVR using high-density cDNA microarrays (10,930 clones). We found that larvae exhibit low sensitivity to natural levels of UVR during most time points analyzed as reflected by comparatively few transcriptomic changes in response to UVR. However, we identified a time window of high UVR sensitivity that coincides with the motile planula stage and the onset of larval competence. These processes have been shown to be affected upon UVR exposure, and the transcriptional changes we identified explain these observations well. Our analysis of differentially expressed genes indicates that UVR induces a stress response and affects the expression of neurogenesis-related genes that can be linked to swimming and settlement behavior at later stages. Taken together, our study provides further data to the impact of natural levels of UVR on coral larvae. Furthermore, our results might allow a better prediction of settlement and recruitment rates after coral spawning events based on UVR climate data.