The yolk syncytial layer regulates myocardial migration by influencing extracellular matrix assembly in zebrafish

Abstract

The roles of extra-embryonic tissues in early vertebrate body patterning have been extensively studied, yet we know little about their function during later developmental events. Here, we analyze the function of the zebrafish extra-embryonic yolk syncytial layer (YSL) specific transcription factor, Mtx1, and find that it plays an essential role in myocardial migration. Downregulating the function of Mtx1 in the YSL leads to cardia bifida, a phenotype in which the myocardial cells fail to migrate to the midline. Mtx1 in the extra-embryonic YSL appears to regulate the embryonic expression of fibronectin, a gene previously implicated in myocardial migration. We further show dosage-sensitive genetic interactions between mtx1 and fibronectin. Based on these data, we propose that the extra-embryonic YSL regulates myocardial migration, at least in part by influencing fibronectin expression and subsequent assembly of the extracellular matrix in embryonic tissues.

Fgf receptors Fgfr1a and Fgfr2 control the function of pharyngeal endoderm in late cranial cartilage development

“…Embryos were kept in E3 medium at 28 1C and developed until the stages of interest according to Kimmel et al (1995). The transgenic lines Tg(hsp70l:dnfgfr1-EGFP) pd1 (Lee et al, 2005) and Tg(sox17-GFP) s870 (Sakaguchi et al, 2006) were obtained from the ZIRC (Eugene, Oregon, USA).…”

ApoA-II Directs Morphogenetic Movements of Zebrafish Embryo by Preventing Chromosome Fusion during Nuclear Division in Yolk Syncytial Layer

“…External YSN (eYSN) form a marginal band of YSN located in front of the enveloping cell layer. During YSL organization, some of the eYSNs move toward the vegetal pole (epiboly movements), whereas others recede from the marginal zone and undergo convergence and extension (CE) movements (18,19). By contrast, internal YSN (iYSN) are located below the blastoderm and EVL and primarily undergo CE movements (18).…”

“…By contrast, internal YSN (iYSN) are located below the blastoderm and EVL and primarily undergo CE movements (18). The epiboly and convergence and extension movements of YSN constitute the main events of YSL patterning that play crucial roles in embryonic patterning and morphogenesis (17,19).…”

The Nature of Exocytosis in the Yolk Trophoblastic Layer of Silver Arowana (Osteoglossum bicirrhosum) Juvenile, the Representative of Ancient Teleost Fishes

“…The induction and/or patterning of anterior neural tissue, the body axes, formation of the ventrolateral mesoderm and induction of the nodal-related genes in the ventrolateral marginal blastomeres during early embryonic development are also attributed to the ysl (Ho et al, 1999;Hyodo et al, 1999;Chen and Kimelman, 2000). The ysl function is connected with the morphogenesis of the organizer epithelium (D'Amico and Cooper, 2001;Cooper and Virta, 2007), the regulation of cardiac tissue morphogenesis (Sakaguchi et al, 2006), and the formation of the liver bud (Li et al, 2007).…”

“…As the teleost fish embryo and larva mass increases exponentially, the function of the ysl as the ''early embryonic patterning center'' (Ho et al, 1999;Sakaguchi et al, 2006) is transformed into those functions predominantly involved in yolk digestion, synthesis, and release of nutrients from the yolk to the growing body (Krieger and Fleig, 1999). In contrast to other lower vertebrates, including non-teleost fish, teleosts do not have a connection between the endoderm of the presumptive gut and yolk reserves during the whole embryonic and early larval development (Kunz, 2004).…”