15 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
Molecular cloning and characterization of the matricellular protein Sparc/osteonectin in flatfish, Scophthalmus maximus, and its developmental stage-dependent transcriptional regulation during metamorphosis
SPARC/osteonectin is amultifunctionalmatricellular glycoprotein,which is expressed in embryonic and adult tissues
that undergo active proliferation and dynamic morphogenesis. Recent studies indicate that Sparc expression
appears early in development, although its function and regulation during development are largely unknown. In
this report, we describe the isolation, characterization, post-embryonic developmental expression and environmental
thermal regulation of sparc in turbot. The full-length turbot sparc cDNA contains 930 bp and encodes a
protein of 310 amino acids, which shares 77, 75 and 80% identity with human, frog and zebrafish, respectively.
Results of whole-mount in situ hybridization reveal a dynamic expression profile during post-embryonic turbot
development. Sparc is expressed differentially in the cranioencephalic region; mainly in jaws, branchial arches,
fin folds and rays of caudal, dorsal and anal fins. Furthermore, ontogenetic studies demonstrated that Sparc
gene expression is dynamically regulated during post-embryonic turbot development, with high expression during
stage-specific post-embryonic remodeling. Additionally, the effect of thermal environmental conditions on
turbot development and on ontogenetic sparc expression was evaluated.En prens