Related Experiment Video
Updated: Jun 13, 2026

Multi-locus Variable-number Tandem-repeat Analysis of the Fish-pathogenic Bacterium Yersinia ruckeri by Multiplex PCR and Capillary Electrophoresis
Published on: June 17, 2019
Variability of 18S rDNA locus among Symphysodon fishes: chromosomal rearrangements
M C Gross1, C H Schneider, G T Valente
1Instituto de Ciências Biológicas, Universidade Federal do Amazonas, Manaus, Amazonas, Brazil. gross@ufam.edu.br
Abstract:
Three species of cichlids belonging to the genus Symphysodon have demonstrated interspecific and intraspecific variation in nucleolus organizer regions (NOR) detected with silver nitrate. In order to understand the evolution of this marker in the genus, the structural variability of these sequences in mitotic chromosomes from Symphysodon aequifasciatus, Symphysodon discus and Symphysodon haraldi was investigated using both silver nitrate impregnation and hybridization of the 18S rRNA gene probe. For the three species, the two markers were intraspecifically and interspecifically variable both in the number and in the size of the sites. This polymorphism may stem from duplications and translocations, which suggests that structural chromosome rearrangements effectively act in the karyoevolution of wild Symphysodon species and may have favoured the adaptability of these fishes to diverse aquatic environments in the Amazon.
Related Concept Videos
Conservative Site-specific Recombination and Phase Variation
The recognition sites for Cre recombinase called LoxP...
Synteny and Evolution
Around 80 million years ago, the human and mice lineages diverged from the common ancestor. During the course of evolution, the ancestral chromosome underwent...
Lampbrush Chromosomes
LBCs are made up of two pairs of conjugating homologous chromatids. Each chromatid consists of alternatively positioned regions of condensed-inactive chromatin and loosely placed-active side loops, which can be contracted and extended. The loops resemble the...
Evolutionary Relationships through Genome Comparisons
Diversity of Protists III
Exon Recombination
Exon shuffling follows “splice frame rules.” Each exon has three reading...
