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Gornung, Ekaterina; Gabrielli, Ivan; Cataudella, Stefano; Sola, Luciana

doi:10.1023/a:1018441402370

Cited by 52 publications

(12 citation statements)

References 15 publications

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“…Cytogenetic studies showed that 5S rRNA probes hybridize to chr-4q [62]–[64] and this is confirmed by the distribution of the 5s rRNA sequence motif in Zv9, with a strong enrichment on chr-4q (Table 2, Figure 5A, B row 1). The centromere-proximal portion of the heterochromatic region includes a cluster of 55 members of the miRNA family mir-430 at about 28.0 Mb.…”

Section: Resultsmentioning

confidence: 64%

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Multiple Sex-Associated Regions and a Putative Sex Chromosome in Zebrafish Revealed by RAD Mapping and Population Genomics

et al. 2012

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Within vertebrates, major sex determining genes can differ among taxa and even within species. In zebrafish (Danio rerio), neither heteromorphic sex chromosomes nor single sex determination genes of large effect, like Sry in mammals, have yet been identified. Furthermore, environmental factors can influence zebrafish sex determination. Although progress has been made in understanding zebrafish gonad differentiation (e.g. the influence of germ cells on gonad fate), the primary genetic basis of zebrafish sex determination remains poorly understood. To identify genetic loci associated with sex, we analyzed F2 offspring of reciprocal crosses between Oregon *AB and Nadia (NA) wild-type zebrafish stocks. Genome-wide linkage analysis, using more than 5,000 sequence-based polymorphic restriction site associated (RAD-tag) markers and population genomic analysis of more than 30,000 single nucleotide polymorphisms in our *ABxNA crosses revealed a sex-associated locus on the end of the long arm of chr-4 for both cross families, and an additional locus in the middle of chr-3 in one cross family. Additional sequencing showed that two SNPs in dmrt1 previously suggested to be functional candidates for sex determination in a cross of ABxIndia wild-type zebrafish, are not associated with sex in our AB fish. Our data show that sex determination in zebrafish is polygenic and that different genes may influence sex determination in different strains or that different genes become more important under different environmental conditions. The association of the end of chr-4 with sex is remarkable because, unique in the karyotype, this chromosome arm shares features with known sex chromosomes: it is highly heterochromatic, repetitive, late replicating, and has reduced recombination. Our results reveal that chr-4 has functional and structural properties expected of a sex chromosome.

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Section: Resultsmentioning

confidence: 64%

“…Subsequently, LGs were assigned to physical chromosomes [18] that cytogeneticists had previously numbered based on physical length [15], [16], [62]–[64]. In this paper, we use the designation ‘chr’ to mean ‘Linkage Group’ rather than cytogenetically identified physical chromosomes, in agreement with zebrafish nomenclature conventions.…”

Section: Methodsmentioning

confidence: 99%

Multiple Sex-Associated Regions and a Putative Sex Chromosome in Zebrafish Revealed by RAD Mapping and Population Genomics

et al. 2012

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“…However, the accurate assignment of chromosomal pairs is hampered by lack of substantial size differences among the zebrafish chromosomes and their poor staining. Ten teams reported the lack of a heteromorphic chromosomal pair in the zebrafish karyotype [60], [61], [62], [63], [64], [65], [66], [67], [68], [69], while only two publications described the presence of such a pair [70], [71]. Researchers have also tried to look for sex chromosomes in the zebrafish genome by searching for sex bivalent synaptonemal complexes [72] and performing comparative genomic hybridization (CGH) between male and female gDNAs [73].…”

Section: Discussionmentioning

confidence: 99%

Polygenic Sex Determination System in Zebrafish

et al. 2012

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BackgroundDespite the popularity of zebrafish as a research model, its sex determination (SD) mechanism is still unknown. Most cytogenetic studies failed to find dimorphic sex chromosomes and no primary sex determining switch has been identified even though the assembly of zebrafish genome sequence is near to completion and a high resolution genetic map is available. Recent publications suggest that environmental factors within the natural range have minimal impact on sex ratios of zebrafish populations. The primary aim of this study is to find out more about how sex is determined in zebrafish.Methodology/Principal FindingsUsing classical breeding experiments, we found that sex ratios across families were wide ranging (4.8% to 97.3% males). On the other hand, repeated single pair crossings produced broods of very similar sex ratios, indicating that parental genotypes have a role in the sex ratio of the offspring. Variation among family sex ratios was reduced after selection for breeding pairs with predominantly male or female offspring, another indication that zebrafish sex is regulated genetically. Further examinations by a PCR-based “blind assay" and array comparative genomic hybridization both failed to find universal sex-linked differences between the male and female genomes. Together with the ability to increase the sex bias of lines by selective breeding, these data suggest that zebrafish is unlikely to utilize a chromosomal sex determination (CSD) system.Conclusions/SignificanceTaken together, our study suggests that zebrafish sex is genetically determined with limited, secondary influences from the environment. As we have not found any sign for CSD in the species, we propose that the zebrafish has a polygenic sex determination system.

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“…Some other studies carried out in Hypostomus ( Artoni and Bertollo 1999 , Kavalco et al 2004 , Cereali et al 2008 ) also showed that this fish group may possess different classes of GC and/or AT-rich repetitive DNA families, as observed in the species analyzed in the present report. AT-rich regions are also rare among fishes, and have been reported mainly in some Hypostomini species ( Artoni and Bertollo 1999 , Kavalco et al 2004 , Rubert et al 2008 ), some zebrafish species ( Gornung et al 1997 , Phillips and Reed 2000 ), and gobiid fishes ( Canapa et al 2002 ).…”

Section: Discussionmentioning

confidence: 99%

Cytogenetic characterization of four species of the genus Hypostomus Lacépède, 1803 (Siluriformes, Loricariidae) with comments on its chromosomal diversity

Rubert¹,

Rosa²,

Jerep³

et al. 2011

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Cytogenetic analyses were performed on fishes of the genus Hypostomus (Hypostomus ancistroides (Ihering, 1911), Hypostomus strigaticeps (Regan, 1908), Hypostomus regani (Ihering, 1905), and Hypostomus paulinus (Ihering, 1905)) from the seven tributaries of the Paranapanema River Basin (Brazil) by means of different staining techniques (C-, Ag-, CMA3- and DAPI-banding) and fluorescence in situ hybridization (FISH) to detect 18S rDNA sites. All species showed different diploid numbers: 2n=68 (10m+26sm+32st-a) in Hypostomus ancistroides, 2n=72 (10m+16sm+46st-a) in Hypostomus strigaticeps, 2n=72 (10m+18sm+44st-a) in Hypostomus regani and 2n=76 (6m+16sm+54st-a) in Hypostomus paulinus. Ag-staining and FISH revealed various numbers and locations of NORs in the group. NORs were usually located terminally on the subtelocentric/acrocentric chromosomes: on the long arm in Hypostomus strigaticeps (2 to 4) and Hypostomus paulinus (2); and on the short arm in Hypostomus ancistroides (2 to 8) and Hypostomus regani (2 to 4). Conspicuous differences in heterochromatin distribution and composition were found among the species, terminally located in some st-a chromosomes in Hypostomus ancistroides, Hypostomus strigaticeps, and Hypostomus paulinus, and interstitially dispersed in most st-a chromosomes, in Hypostomus regani. The fluorochrome staining indicated that different classes of GC and/or AT-rich repetitive DNA evolved in this group. Our results indicate that chromosomal rearrangements and heterochromatin base-pair composition were significant events during the course of differentiation of this group. These features emerge as an excellent cytotaxonomic marker, providing a better understanding of the evolutionary mechanisms underlying the chromosomal diversity in Hypostomus species.

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Cited by 52 publications

References 15 publications

Multiple Sex-Associated Regions and a Putative Sex Chromosome in Zebrafish Revealed by RAD Mapping and Population Genomics

Multiple Sex-Associated Regions and a Putative Sex Chromosome in Zebrafish Revealed by RAD Mapping and Population Genomics

Polygenic Sex Determination System in Zebrafish

Cytogenetic characterization of four species of the genus Hypostomus Lacépède, 1803 (Siluriformes, Loricariidae) with comments on its chromosomal diversity

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