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DNA amount of chicken chromosomes resolved by image cytometry

Mendonça, Maria Andréia Corrêa, Carvalho, Carlos Roberto, Clarindo, Wellington Ronildo
Caryologia 2016 v.69 no.3 pp. 201-206
DNA, chickens, chromosomes, evolution, genome, genomics, haploidy, karyotyping, morphometry
Avian karyotypes are remarkably conserved throughout evolution. Hence, studies have given priority to the chicken for characterizing and understanding the chromosome organization in this clade. Chicken chromosomes are conventionally classified as macrochromosomes (MACs), microchromosomes (MICs) and sexual chromosomes (ZW). For expanding karyotype data, the DNA amount of the MACs, ZW and a few MICs have been reported. In spite of the progress, hitherto chicken chromosomes have not been fully classified and characterized, especially MICs, accounting for a gap in evolutionary approaches and genomic projects. The chicken karyotype is considered one of the most challenging for cytogenetic study. This study focused on image cytometry, a quantitative measure of the chromosome DNA amount, to fine-tune morphometric data. The methodology was fundamental to identify and discriminate each MIC, overlapping between MICs and MICs/MACs. Associating these data to classical cytogenetic rules, karyograms were assembled. Mean DNA amount was also used to calculate the percentage equivalent of each chromosome group in the haploid genome. Therefore, image cytometry represented a powerful application that can be used for avian karyotype characterization, opening up a range of possibilities for scientific research.