Identificazione e caratterizzazione di FoxP nel sistema nervoso centrale di Octopus vulgaris (Mollusca, Cephalopoda)
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Sirakov, Maria
Tota, Bruno
Borra, Marco
Fiorito, Graziano
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Dottorato di Ricerca in Biologia Animale, XX Ciclo,a.a.2006-2007; In this study, I searched and was able to identify FoxP in the transcriptome of the
cephalopod mollusc Octopus vulgaris, an invertebrate. In addition, I attempted to analyze
the expression of Ov-FoxP in the brain of this animal. The results of this analysis are
preliminary at this stage.
Fox proteins are a set of transcription factors highly conserved in metazoans. They are
characterized by a typical DNA binding domain (Forkhead) that, among others, allows to
identify 15 different classes of Fox genes. Fox proteins are reported to act as
activators/repressors of transcription during both development (including differentiation)
and the adult life (e.g. lung, brain, etc.). In vertebrates, FoxP2 (together with FoxP1), in
particular, are known to be involved in the development of the neural circuit controlling
bird-song and human speech.
Our interest for the octopus derives from the fact that this animal, together with other
cephalopods, is considered as the most evolved among molluscs. The complexity of the
architecture and wiring of the cephalopod nervous system stems from the simpler nervous
systems of other taxa belonging to the phylum. In addition, cephalopods show a highly rich
behavioral repertoire including the unique capability of changing the appearance of their
body (through body patterning) in fractions of seconds and for both mimetic and
communicative purposes. Taken all together, these features allow these animals to be
considered analogous to higher vertebrates.
In the first part of my project, a detailed analysis of the aminoacidic and nucleotidic
sequences available for FoxP2 (vertebrates) and FoxP (invertebrates), allowed us to design
FoxP in Octopus vulgaris
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appropriate oligos that were utilized in subsequent PCR experiments to identify the gene of
interest in the transcriptome of the brain of O. vulgaris. FoxP resulted in a fragment of 220
bp that corresponded to the Forkhead domain. Further efforts allowed us to identify a
1111bp mRNA sequence of Ov-FoxP corresponding to almost the entire part of the mature
mRNA codifying for this protein (the 5’ extremity of the gene results unidentified at this
stage).
During the second part of my project, I attempted to analyze the expression pattern of Ov-
FoxP in the octopus brain using Real Time qPCR and in-situ hybridization. This was
carried out with the aim of investigating the possible variability of expression of the gene in
different parts of the brain (i.e. supra-, sub-esophageal masses and optic lobes) relative to
another tissue (muscular tissue of the mantle) here considered as control. Other genes (16S,
tubulin, actin) were also cloned for the aims of this project and their expression was taken
as reference; an analysis that is carried out for the first time in O. vulgaris.
By Real-Time qPCR I was able to recognize a different pattern of expression in different
parts of the brain (N = 10). The data allowed to identify a gradient in the expression levels
of FoxP (relative to reference genes) in the subesophageal mass, when the smallest
individual of my sample (30 g body weight) was compared with the others (150-2100 g
body weight).
In situ hybridization (N=6) allowed to localize the expression of FoxP in the lobes of the
octopus brain. Ov-FoxP transcripts were identified in neurons of: i. the optic lobes (several
sparse cells possibly related with visual input processing); ii. the superior buccal and the
lateral part of the basal lobes (high-order motor centers of the supraesophageal mass), and
iii. the pedal tracts and anterior and posterior chromatophore lobes (subesophageal mass).
FoxP in Octopus vulgaris
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An elevated number of cells was revealed through in-situ hybridization in the last two
lobes. It is noteworthy to mention that these structures are known to play a key role in the
neural control of the chromatic expression of the skin of O. vulgaris (and other
cephalopods): namely the animal’s body pattern.
Our data seems to suggest that Ov-FoxP is expressed during different phases of the life of
the octopus. In addition the localized expression in definite lobes and the variability among
individuals of its expression in the same brain parts allows us to formulate the working
hypothesis of the role of Ov-FoxP in the plasticity and/or maintainance of neural networks.
My project in O. vulgaris confirms similar results deduced from other studies in both
invertebrates (i.e. motor neurons in C. elegans) and vertebrates (i.e. song-birds, mouse,
etc).; Università della CalabriaSoggetto
Biologia animale; Sistema nervoso; Sistema nervoso; Molluschi
Relazione
BIO/06;