4 research outputs found
Transient Ectopic Overexpression of Agouti-Signalling
While flatfish in the wild exhibit a pronounced countershading of the dorso-ventral pigment pattern, malpigmentation is
commonly observed in reared animals. In fish, the dorso-ventral pigment polarity is achieved because a melanization
inhibition factor (MIF) inhibits melanoblast differentiation and encourages iridophore proliferation in the ventrum. A
previous work of our group suggested that asip1 is the uncharacterized MIF concerned. In order to further support this
hypothesis, we have characterized asip1 mRNAs in both turbot and sole and used deduced peptide alignments to analyze
the evolutionary history of the agouti-family of peptides. The putative asip precursors have the characteristics of a secreted
protein, displaying a putative hydrophobic signal. Processing of the potential signal peptide produces mature proteins that
include an N-terminal region, a basic central domain with a high proportion of lysine residues as well as a proline-rich region
that immediately precedes the C-terminal poly-cysteine domain. The expression of asip1 mRNA in the ventral area was
significantly higher than in the dorsal region. Similarly, the expression of asip1 within the unpigmented patches in the
dorsal skin of pseudoalbino fish was higher than in the pigmented dorsal regions but similar to those levels observed in the
ventral skin. In addition, the injection/electroporation of asip1 capped mRNA in both species induced long term dorsal skin
paling, suggesting the inhibition of the melanogenic pathways. The data suggest that fish asip1 is involved in the dorsalventral
pigment patterning in adult fish, where it induces the regulatory asymmetry involved in precursor differentiation
into mature chromatophore. Adult dorsal pseudoalbinism seems to be the consequence of the expression of normal
developmental pathways in an inaccurate position that results in unbalanced asip1 production levels. This, in turn,
generates a ventral-like differentiation environment in dorsal regions.Publicado
Bases moleculares de las malformaciones pigmentarias en peces: implicación en el cultivo del rodaballo (Scophthalmus maximus L.)
In mammals the colour of skin is due to production of eumelanins (brown-black pigments) and pheomelanins (yellow-brownish pigments) in a specific type cell, the melanocytes. In contrast, in fish, pigmentation patternare determine by three different types of cells, melanophores, xantophores and iridophores. However, in both cases the melanogenesis is controlled by a similar mechanism. The α-MSH which stimulate the synthesis of melanin, and the ASP which antogonize its effects. Flounder (Scophthalmus maximus L.) agouti gen was cloned from skin tissue by using RACE-PCR with degenerated oligos. High expression of agouti gene was found in white epidermis areas compared with the black ones. Furthermore, dermal-injection of capped agouti mRNA produced a striking skin lightening. Thus, suggesting a central role of agouti gene in pigmentation pattern control in fish
Supplementary Material for: Critical Role of the Matricellular Protein SPARC in Mediating Erythroid Progenitor Cell Development in Zebrafish
Sparc (osteonectin) is a multifunctional matricellular glycoprotein expressed by many differentiated cells. Members of this family mediate cell-matrix interactions rather than acting as structural components of the extracellular matrix (ECM); therefore, they can influence many remodelling events, including haematopoiesis. We have investigated the role of <i>sparc</i> in embryonic haematopoiesis using a morpholino antisense oligonucleotide-based knockdown approach. Knockdown of <i>sparc</i> function resulted in specific erythroid progenitor cell differentiation defects that were highlighted by changes in gene expression and morphology, which could be rescued by injection of <i>sparc</i> mRNA. Furthermore, a comparison of blood phenotypes of <i>sparc</i> and <i>fgfs</i> knockdowns with similar defects and the <i>sparc</i> rescue of the<i> fgf21</i> blood phenotype places <i>sparc</i> downstream of <i>fgf21</i> in the genetic network regulating haematopoiesis in zebrafish. These results establish a role for an ECM protein (Sparc) as an important regulator of embryonic haematopoiesis during early development in zebrafish