Bridging methodological gaps in avian cytogenetics: comprehensive and optimized protocols for chromosomal preparation in birds

This methodological study outlines effective and standardized procedures for obtaining high-quality chromosomal preparations in birds, which display complex karyotypes with a large number of microchromosomes. We describe every stage from sample obtaining and culture setup to the successful acquisition of metaphase chromosomes appropriate for in-depth analysis by combining three main methodologies (fibroblast, lymphocyte, and bone marrow cultures) into a coherent and methodical workflow. Furthermore, we offer thorough troubleshooting instructions to tackle typical problems, such as low mitotic indices, poor chromosome spreading, contamination, and suboptimal chromosomal morphology. We also focused on repeatability and adaptation across several bird taxa, taking into consideration species-specific differences in their body sizes, cell development, and chromosomal behavior, extending beyond standard procedure improvement. The incorporation of diverse methodologies into a unified framework offers avian cytogenetics researchers a readily available and practical workflow. Ultimately, our approach enhances the integration of cytogenetic data with novel genomic resources, facilitates the re-evaluation of chromosomal counts, and enables more precise karyotype characterization. This integration is crucial for advancing our understanding of chromosomal evolution, avian genome architecture, and the broader mechanisms underlying avian speciation and diversification.