Chromosome Evolution in African Cichlid Fish: Contributions from the Physical Mapping of Repeated DNAs

Abstract

Cichlid fishes have been the subject of increasing scientific interest because of their rapid adaptive radiation that has led to extensive ecological diversity and because of their enormous importance to tropical and subtropical aquaculture. To further understanding of chromosome evolution among cichlid species, we have comparatively mapped the SATA satellite DNA, the transposable element ROn-1, and repeated sequences in the bacterial artificial chromosome clone BAC-C4E09 on the chromosomes of a range of African species of Cichlidae, using fluorescence in situ hybridization. The SATA satellite DNA was mapped in almost all the centromeres of all tilapiine and haplochromine species studied. The maintenance and centromeric distribution of the SATA satellite DNA in African cichlids suggest that this sequence plays an important role in the organization and function of the centromere in these species. Furthermore, analysis of SATA element distribution clarifies that chromosome fusions occurred independently in Oreochromis and Tilapia genera, and led to the reduced chromosome number detected in O. karongae and T. mariae. The comparative chromosome mapping of the ROn-1 SINE-like element and BAC-C4E09 shows that the repeated sequences have been maintained among tilapiine, haplochromine and hemichromine fishes and has demonstrated the homology of the largest chromosomes among these groups. Furthermore, the mapping of ROn-1 suggested that different chromosomal rearrangements could have occurred in the origin of the largest chromosome pairs of tilapiines and non-tilapiines.

The Tilapias' Chromosomes Influencing Sex Determination

“…Additionally, there are no observed karyotypic differences between species having male or female heterogametic sex-determination mechanisms [Kornfield et al, 1979;Majumdar and McAndrew, 1986;Ferreira et al, 2010].…”

Cytogenetic Mapping of the Retroelements <i>Rex1, Rex3</i> and <i>Rex6</i> among Cichlid Fish: New Insights on the Chromosomal Distribution of Transposable Elements

“…In O. niloticus the largest chromosome pair might have originated by chromosome fusions [Chew et al, 2002;Ferreira et al, 2010] and is recognized as the sex chromosome [Carrasco et al, 1999;Griffin et al, 2002]. It has been broadly reported that TEs have been important to genome evolution in a range of species, causing in some cases loss and gain of sequences and chromosomal rearrangements [Lyttle and Haymer, 1992;Cáceres et al, 1999Cáceres et al, , 2001Zhang and Peterson, 1999;Evgen'ev et al, 2000;Biémont and Vieira, 2006].…”

“…As the largest chromosome pair of O . niloticus may reflect an ancient state for the sex chromosome in the tilapiine group [Cnaani et al, 2008], the accumulation of Rex elements along the length of the q arm, together with other repeated sequences [Harvey et al, 2003;Ferreira and Martins, 2008;Ferreira et al, 2010], indicates that the repetitive elements played important roles in the differentiation of sex chromosomes in the group. Similarly, in C. hamatus , the retrotransposon Rex3 has also accumulated in the long arm of the male Y chromosome, indicating that the TE could have been involved in the fusion process and molecular differentiation that created the sex chromosomes in this species [Ozouf-Costaz et al, 2004].…”

“…They include satellite DNAs [Oliveira et al, 1998;Mazzuchelli and Martins, 2009;Mota-Velasco et al, 2010], transposable elements [Oliveira et al, 1999[Oliveira et al, , 2003Ferreira and Martins, 2008;Mazzuchelli and Martins, 2009;Teixeira et al, 2009;Ferreira et al, 2010], telomeric (TTAGGG) n repeats [Chew et al, 2002;Mota-Velasco et al, 2010;Poletto et al, 2010a], rDNA repeats [Martins et al, 2002;Vicari et al, 2006;Gross et al, 2010;Poletto et al, 2010b], and other repetitive sequences [Ferreira and Martins, 2008;Mazzuchelli and Martins, 2009;Valente et al, 2009]. The cichlids have attracted the attention of biologists due to the rapid radiation of some groups in the Great Lakes of East Africa, in which almost 2,000 species arose in the last 10 million years [Kocher, 2004].…”

Construction of Chromosome Markers from the Lake Victoria Cichlid Paralabidochromis chilotes and Their Application to Comparative Mapping

“…This mismatch may have been caused by chromosome rearrangements during the evolutionary process. The number of chromosomes in cichlid species has changed during evolution [Ferreira et al, 2010;Poletto et al, 2010a], and a high frequency of chromosome rearrangements is suggested by fluorescence in situ hybridization (FISH) analyses [Mazzuchelli et al, 2011[Mazzuchelli et al, , 2012. Furthermore, the LGs may not match in different cichlid species because the existing microsatellite markers isolated from one species may not be present in the species of interest.…”