(Below N is a link to NCBI taxonomic web page and E link to ESTHER at designed phylum.) > cellular organisms: NE > Eukaryota: NE > Opisthokonta: NE > Metazoa: NE > Eumetazoa: NE > Cnidaria: NE > Hydrozoa: NE > Hydroidolina: NE > Leptothecata: NE > Campanulariidae: NE > Clytia: NE > Clytia hemisphaerica: NE
MDGSDARYYLSRQWESNNWVIHLQGGGSCITYDECRSRSEGPLGSSLPLD
AHITGEWTLSNDPKINPTFHKWNKVLIPYCSGDVFVGRMLKKNHPYRLPM
LGHYIFSAVIEDLVRLYKINKKKTKILFGGTSAGGVGVLANADYLQEMTR
PAKVRAYNDGGWFTLFRSFGEKPNMNLPQFFHTLATLFEKHWDGFADKTC
QKHMPKSAACLYGELAIQYVKTPMFVMTSMWDLYQLNQMVPRTSPVIHLP
PKLNQETKYLESFANNSYRSITGLLRKPKNGVFSPACYSHIFFTNCIGGI
ICGAPKKTVYSSGGQTAYGALTDWYLTDGAEGSYIDDIIESPTCNPSCCT
QHCHKCKSLNDILHGTENGHTNLVYRHRKRKKETDTKNEVERNHDNQNNY
QR
LegendThis sequence has been compared to family alignement (MSA) red => minority aminoacid blue => majority aminoacid color intensity => conservation rate title => sequence position(MSA position)aminoacid rate Catalytic site Catalytic site in the MSA MDGSDARYYLSRQWESNNWVIHLQGGGSCITYDECRSRSEGPLGSSLPLD AHITGEWTLSNDPKINPTFHKWNKVLIPYCSGDVFVGRMLKKNHPYRLPM LGHYIFSAVIEDLVRLYKINKKKTKILFGGTSAGGVGVLANADYLQEMTR PAKVRAYNDGGWFTLFRSFGEKPNMNLPQFFHTLATLFEKHWDGFADKTC QKHMPKSAACLYGELAIQYVKTPMFVMTSMWDLYQLNQMVPRTSPVIHLP PKLNQETKYLESFANNSYRSITGLLRKPKNGVFSPACYSHIFFTNCIGGI ICGAPKKTVYSSGGQTAYGALTDWYLTDGAEGSYIDDIIESPTCNPSCCT QHCHKCKSLNDILHGTENGHTNLVYRHRKRKKETDTKNEVERNHDNQNNY QR
Jellyfish (medusae) are a distinctive life-cycle stage of medusozoan cnidarians. They are major marine predators, with integrated neurosensory, muscular and organ systems. The genetic foundations of this complex form are largely unknown. We report the draft genome of the hydrozoan jellyfish Clytia hemisphaerica and use multiple transcriptomes to determine gene use across life-cycle stages. Medusa, planula larva and polyp are each characterized by distinct transcriptome signatures reflecting abrupt life-cycle transitions and all deploy a mixture of phylogenetically old and new genes. Medusa-specific transcription factors, including many with bilaterian orthologues, associate with diverse neurosensory structures. Compared to Clytia, the polyp-only hydrozoan Hydra has lost many of the medusa-expressed transcription factors, despite similar overall rates of gene content evolution and sequence evolution. Absence of expression and gene loss among Clytia orthologues of genes patterning the anthozoan aboral pole, secondary axis and endomesoderm support simplification of planulae and polyps in Hydrozoa, including loss of bilateral symmetry. Consequently, although the polyp and planula are generally considered the ancestral cnidarian forms, in Clytia the medusa maximally deploys the ancestral cnidarian-bilaterian transcription factor gene complement.
We have used Digital Gene Expression analysis to identify, without bilaterian bias, regulators of cnidarian embryonic patterning. Transcriptome comparison between un-manipulated Clytia early gastrula embryos and ones in which the key polarity regulator Wnt3 was inhibited using morpholino antisense oligonucleotides (Wnt3-MO) identified a set of significantly over and under-expressed transcripts. These code for candidate Wnt signaling modulators, orthologs of other transcription factors, secreted and transmembrane proteins known as developmental regulators in bilaterian models or previously uncharacterized, and also many cnidarian-restricted proteins. Comparisons between embryos injected with morpholinos targeting Wnt3 and its receptor Fz1 defined four transcript classes showing remarkable correlation with spatiotemporal expression profiles. Class 1 and 3 transcripts tended to show sustained expression at "oral" and "aboral" poles respectively of the developing planula larva, class 2 transcripts in cells ingressing into the endodermal region during gastrulation, while class 4 gene expression was repressed at the early gastrula stage. The preferential effect of Fz1-MO on expression of class 2 and 4 transcripts can be attributed to Planar Cell Polarity (PCP) disruption, since it was closely matched by morpholino knockdown of the specific PCP protein Strabismus. We conclude that endoderm and post gastrula-specific gene expression is particularly sensitive to PCP disruption while Wnt-/beta-catenin signaling dominates gene regulation along the oral-aboral axis. Phenotype analysis using morpholinos targeting a subset of transcripts indicated developmental roles consistent with expression profiles for both conserved and cnidarian-restricted genes. Overall our unbiased screen allowed systematic identification of regionally expressed genes and provided functional support for a shared eumetazoan developmental regulatory gene set with both predicted and previously unexplored members, but also demonstrated that fundamental developmental processes including axial patterning and endoderm formation in cnidarians can involve newly evolved (or highly diverged) genes.
