EARLY REQUIREMENT OF FURRY IN ORGANIZER FORMATION AND MORPHOGENETIC MOVEMENTS

CERVINO, AILEN; CIRIO, MARIA CECILIA

Jornada; A systems approach to biology; 2018

CELFI-DATOS

During vertebrate embryonic development, fundamental events such as the formation of the three primary germ layers and the morphogenetic events that will shape the embryo are initially executed and coordinated by a dynamic group of cells. In amphibians it has been called ?the Spemann organizer? and cell populations with similar organizing activity have been found in other vertebrates. The molecular mechanisms that regulate formation and maintenance of the organizer and the process of gastrulation are focus of numerous studies given the significance of these events for normal development.Furry (Fry) gene encodes a large, evolutionarily conserved protein with a wide variety of functions, mostly associated with maintenance of cytoskeleton structure, cell polarization and morphogenesis. In Xenopus, dorsal depletion of Fry produces shortening of the dorsal axis and interferes with head formation, a phenotype that is frequently associated with gastrulation defects and/or incorrect progenitor cells specification.Since little is known about the role of Fry in early development, we first investigated its expression pattern by in situ hybridization. While maternal fry mRNA is homogenously distributed in immature oocites, it is accumulated in the animal pole of mature oocites. This polarized distribution is maintained in blastula stages. At the beginning of gastrulation, fry mRNA is found in the involuting marginal zones and later in axial mesoderm. At tailbud stage, fry expression remains in mesoderm derivates such as notochord, somites and pronephros. This expression pattern is indicative of a role in mesoderm patterning. In order to study Fry requirements in the organizer formation, we depleted Fry by injecting a specific validated morpholino, in both dorsal blastomeres of 4-cells embryos. Dorsal depletion of fry results in a reduced expression domain of the organizer genes goosecoid, chordin and otx2, indicating that Fry is required for organizer´s formation. Fry-depleted embryos also exhibit gastrulations defects, gauged by blastopore closure. Specifically, chordamesoderm convergent extension, responsible for antero-posterior axis extension, is impaired in these embryos. Together, our results suggest that Fry has a dual role in early development: it is involved in the establishment of the dorsal organizer and regulates the correct execution of morphogenetic movements.