3 results for Argenton, F

  • Mother-of-snow-white (msw) a maternal effect allele affecting behavior and the formation of the left- right axis in zebrafish (Danio rerio)

    Domenichini, Alice; Dadda, M; Facchin, L; Bisazza, A; Argenton, F (2010-10)

    Conference item
    The University of Auckland Library

    The vertebrate body plan displays distinct left-right asymmetries in the position of visceral organs. This asymmetrical organization extends to the vertebrate brain that is both anatomically and functionally asymmetric. The development of left-right patterning and cerebral lateralization are thought to be regulated by evolutionary conserved genes. Here we report the evidence of the maternal effect allele mother-of-snow-white (msw) controlling the establishment of LR body asymmetries in a vertebrate embryo suggesting conserved mechanisms in the evolution and establishment of this trait. In a recent study Facchin and colleagues [1] showed that the progeny of lines of zebrafish artificially selected for the right eye preference in scrutiny a mirror had a significant increase in the frequency of reversed left-right asymmetry in the epithalamus. In the present study it is proposed that Facchin’s selection for behavioral lateralization could have lead to the isolation of a spontaneous maternal effect allele responsible for the disruption of normal left-right patterning in zebrafish neuroanatomical structures. We analyzed the genetic transmission of the msw allele and we identified three different classes of females according to the percentage of reversed brain asymmetries in their offspring. Females generating a frequency of 0-5% (class I), between 5 and 12.5% (class II) and females generating more than 12.5% (class III) of progeny with reversed asymmetries. Animals from the last group were considered as homozygous recessive females for the msw allele (HRF). We also investigated in the three classes the expression of members of signaling pathways responsible for the establishment of visceral and diencephalic left-right asymmetries and measured the size of Kupffer’s vescicle (KV). We found that HRF offspring had smaller KV and, sometimes, no vesicle at all. We could observe a correlation between the frequency of reversed parapineal and the size of KV. The msw allele has shown to be semi-dominant as class II females showed an intermediate phenotype. Our hypothesis suggests that smaller size of KV can reduce the amount of morphogens accumulated by the leftward flow, thus leading to a randomization of the expression of genes of the Nodal pathway. Moreover we evidenced significant behavioral differences between fish with opposite parapineal position subjected to various laterality tests. We could also discuss a complex but relevant influence of neuroanatomical asymmetries on zebrafish personality [2]. Now using Paired-end Mapping and next-generation sequencing techniques (SOLiD approach) we are aiming at identifying the msw allele. 1. Facchin, L., F. Argenton, and A. Bisazza, Lines of Danio rerio selected for opposite behavioural lateralization show differences in anatomical left-right asymmetries. Behavioural Brain Research, 2009. 197 (1): p. 157-165. 2. Dadda, M., et al., Early differences in epithalamic left-right asymmetry influence lateralization and personality of adult zebrafish. Behavioural Brain Research. 206 (2): p. 208-215.

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  • Isolation and Genetic Characterization of Mother-of-Snow-White, a Maternal Effect Allele Affecting Laterality and Lateralized Behaviors in Zebrafish

    Domenichini, Alice; Dadda, M; Facchin, L; Bisazza, A; Argenton, F (2011-10-13)

    Journal article
    The University of Auckland Library

    In the present work we report evidence compatible with a maternal effect allele affecting left-right development and functional lateralization in vertebrates. Our study demonstrates that the increased frequency of reversed brain asymmetries in a zebrafish line isolated through a behavioral assay is due to selection of mother-of-snow-white (msw), a maternal effect allele involved in early stages of left-right development in zebrafish. msw homozygous females could be identified by screening of their progeny for the position of the parapineal organ because in about 50% of their offspring we found an altered, either bilateral or right-sided, expression of lefty1 and spaw. Deeper investigations at earlier stages of development revealed that msw is involved in the specification and differentiation of precursors of the Kupffer's vesicle, a structure homologous to the mammalian node. To test the hypothesis that msw, by controlling Kupffer's vesicle morphogenesis, controls lateralized behaviors related to diencephalic asymmetries, we analyzed left- and right-parapineal offspring in a “viewing test”. As a result, left- and right-parapineal individuals showed opposite and complementary eye preference when scrutinizing a model predator, and a different degree of lateralization when scrutinizing a virtual companion. As maternal effect genes are expected to evolve more rapidly when compared to zygotic ones, our results highlight the driving force of maternal effect alleles in the evolution of vertebrates behaviors.

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  • Early differences in epithalamic left-right asymmetry influence lateralization and personality of adult zebrafish

    Dadda, M; Domenichini, Alice; Piffer, L; Argenton, F; Bisazza, A (2010-01)

    Journal article
    The University of Auckland Library

    The habenulae are part of an evolutionary conserved conduction system that connects the limbic forebrain areas with midbrain structures and is implicated in important functions such as feeding, mating, avoidance learning, and hormonal response to stress. Very early during zebrafish neurogenesis the parapineal organ migrates near to one habenula, commonly the left, inducing wide left–right habenular asymmetries in gene expression and connectivity. It was posited that this initial symmetry-breaking event determines the development of lateralized brain functions and early differences in epithalamic left–right asymmetry give rise to individual variation in coping styles and personality. We tested these two hypotheses by sorting zebrafish with left or right parapineal at birth using a foxD3:GFP marker and by measuring visual and motor laterality and three personality dimensions as they become adults. Significant differences between fish with opposite parapineal position were found in all laterality tests while the influence of asymmetry of the habenulae on personality was more complex. Fish with atypical right parapineal position, tended to be bolder when inspecting a predator, spent less time in the peripheral portion of an open field and covered a shorter distance when released in the dark. Activity in the open field was not associated to anatomical asymmetry but correlated with laterality of predator inspection that in turn was influenced by parapineal position. One personality dimension, sociality, appeared uncorrelated to both anatomical and functional asymmetries and was instead influenced by the sex of the fish, thus suggesting that other factors, i.e. hormonal, may be implicated in its development.

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