Frimousse--a spontaneous ascidian mutant with anterior ectodermal fate transformation.
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Animals↗
Biomedical subjects
Karine Deschet
Publications and source records attributed to Karine Deschet.
A functional cellulose synthase from ascidian epidermis.
Among animals, urochordates (e.g., ascidians) are unique in their ability to biosynthesize cellulose. In ascidians cellulose is synthesized in the epidermis and incorporated into a protective coat know as the tunic. A putative cellulose synthase-like gene was first identified in the genome sequences of the ascidian Ciona intestinalis. We describe here a cellulose synthase gene from the ascidian Ciona savignyi that is expressed in the epidermis. The predicted C. savignyi cellulose synthase amino acid sequence showed conserved features found in all cellulose synthases, including plants, but was most similar to cellulose synthases from bacteria, fungi, and Dictyostelium discoidium. However, unlike other known cellulose synthases, the predicted C. savignyi polypeptide has a degenerate cellulase-like region near the carboxyl-terminal end. An expression construct carrying the C. savignyi cDNA was found to restore cellulose biosynthesis to a cellulose synthase (CelA) minus mutant of Agrobacterium tumefaciens, showing that the predicted protein has cellulose synthase activity. The lack of cellulose biosynthesis in all other groups of metazoans and the similarity of the C. savignyi cellulose synthase to enzymes from cellulose-producing organisms support the hypothesis that the urochordates acquired the cellulose biosynthetic pathway by horizontal transfer.
Agrobacterium tumefaciens↗
Cloning and developmental expression patterns of Dlx2, Lhx7 and Lhx9 in the medaka fish (Oryzias latipes).
We have isolated three homeodomain and LIM-homeodomain developmental transcription factors from the medaka fish (Oryzias latipes): OlDlx2, OlLhx7, and OlLhx9, and we have studied their expression patterns in the developing and adult brain. This analysis showed that OlDlx2 and OlLhx7 (together with OlNkx2.1b) delineate the subpallial divisions of the medaka telencephalon, and that OlLhx9 exhibits a typical and specific topology of expression in the pallium and diencephalic neuromeres. The expression patterns of these three genes, when compared in details with those of their tetrapod homologs, reveal both commonalities and differences in the basic organization of the developing teleost and vertebrate forebrain.
Amino Acid Sequence↗
Culture of adult ascidians and ascidian genetics.
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Animals↗
Generation of Ci-Brachyury-GFP stable transgenic lines in the ascidian Ciona savignyi.
We report generation of stable transgenic lines of the ascidian Ciona savignyi carrying a Ciona intestinalis-Brachyury-promoter/Green Fluorescent Protein-reporter (Ci-Bra-GFP) construct. The transgenic lines were made using a technique in which the endonuclease I-SceI was coinjected into fertilized eggs with a transgene construct containing flanking recognition sites for I-SceI. Two founder animals, out of 12 F(0) adults tested, were found to transmit the transgene to their offspring (F(1)s) at frequencies of 42% and 23%. The transgene was further inherited by the F(2) in a Mendelian fashion and displayed nonmosaic expression, indicating integration into the genome. The Mendelian inheritance and the absence of mosaicism persisted through the F(3) and F(4) generations. Southern blot analyses showed that the transgene was organized in tandem arrays of no more than 10 copies. Using these Ci-Bra-GFP transgenics, we describe cellular movements and shape changes involved in notochord morphogenesis in both wildtype and mutant embryos.
Animals↗