Identification and developmental expression of Ci-msxb: a novel homologue of Drosophila msh gene in Ciona intestinalis

Abstract

We report the cloning and expression pattern of Ci-msxb the second Ciona intestinalis homeobox gene homologue to the Drosophila muscle segment homeobox (msh) gene. Northern blot analysis showed that transcripts appeared at gastrula stage, peaked in the early tailbud and decreased during the tailed stages. Whole mount in situ hybridization showed that the Ci-msxb expression first is detected at 110 cell-stage in the blastomeres that are precursors of different tissue (muscle, spinal cord, endodermal strand, brain, mesenchyme, pigmented cells and primordial pharynx). Transcript level declined in mesoderm cells after the completion of gastrulation, but mRNAs were still present in the folding neural plate during neurulation and in the pigmented cells. Later, at larval stage, transcripts were present around the otolith and ocellus, in a restricted part of the nervous system and in the primordial pharynx; the gene expression was conserved after metamorphosis in the juvenile.

A conserved role for the MEK signalling pathway in neural tissue specification and posteriorisation in the invertebrate chordate, the ascidianCiona intestinalis

“…6K,K′,L,L′). Furthermore, two markers of a-line neural tissue, Ci-gsx (Hudson and Lemaire, 2001) and Ci-msxb (Aniello et al, 1999), were lost in MEK inhibitor treated neurulae (0% expression, n=37, 85, respectively; data not shown).…”

Evolution of Hox genes in molluscs: a comparison among seven morphologically diverse classes

“…1). As for non-Hox/ParaHox homeobox genes, an Msx (muscle segment homeobox; Aniello et al, 1999) cognate was assigned for L. stagnalis and Gbx (gastrulation brain homeobox; Bubnoff, Schmidt & Kimelman, 1995) for the solenogastre species and N. pompilius (Fig. 1).…”

“…Xgbx-2, one of Xenopus Gbx homologues, is expressed in the presumptive neural ectoderm and epidermis, and suggested to have a role in the early establishment of the midbrain -hindbrain boundary in vertebrates (Bubnoff et al, 1995). One of Msx genes, Ci-msxb of an ascidian, Ciona intestinalis, is expressed in the sensory organs and a part of the epidermis (Aniello et al, 1999). Fragments of the Mox gene, which is included in the extended Hox cluster in addition to the Evx and the Hox cluster itself, are often retrieved in the PCR surveys of Hox genes, using degenerate primers (e.g.…”

Patterning of brain precursors in ascidian embryos

“…Gene markers used for in situ hybridisation have been described (Aniello et al, 1999;Hudson and Lemaire, 2001;Imai et al, 2004) (http://ghost.zool. kyoto-u.ac.jp) and named according to recent guidelines (Stolfi et al, 2015).…”