Biomedical subjects

Ricardo Utsunomia

Publications and source records attributed to Ricardo Utsunomia.

3 recordsLinked to original sources

PubMed2026

Satellite DNA evolution in Tytonidae (Aves: Strigiformes): dynamic repeat landscapes despite conserved karyotypes.

The elevated chromosome numbers observed in Tytonidae relative to the putative ancestral avian karyotype suggest that lineage-specific chromosomal fissions may have played an important role in the evolutionary history of this family. Here, we provide the first cytogenetic characterization of the American barn owl (Tyto furcata) and performs a comparative repeatome analysis across members of the Tytonidae, including other two species, the Western barn owl (Tyto alba), and the Oriental bay owl (Phodilus badius). The karyotype of T. furcata showed a 2n = 92, closely resembling that previously described for T. alba, indicating a high degree of chromosomal conservation within Tytonidae. Although T. furcata and T. alba exhibit similar karyotypic organization, comparative repeatomic analyses revealed differences in their composition, including variation in satellite DNA (satDNA) repertoires and abundance. Eight satDNA families were identified in T. furcata, nine in T. alba, and 28 in P. badius, highlighting the dynamic evolution of repetitive sequences. Several satDNA families were shared between T. furcata and T. alba, whereas some appeared species-specific, supporting the library hypothesis of satDNA evolution. In P. badius, multiple satDNAs exhibited similarity to transposable elements, suggesting that mobile elements contributed to their diversification. Cytogenetic analyses demonstrated centromeric heterochromatin distribution in T. furcata, as well as a large heterochromatic W chromosome enriched in DNA repeats. The localization of satDNAs in centromeric regions and the apparent accumulation of repeats on the W chromosome reinforce the role of repetitive sequences in chromosome organization and sex chromosome differentiation. Together, these findings reveal repeatome diversification despite conserved macrochromosomal structure and provide new insights into genome evolution and chromosomal dynamics in birds.

Animals↗

PubMed2026

Molecular divergence and genomic composition of B chromosomes in the fish Cyphocharax modestus (Characiformes, Curimatidae).

B chromosomes are supernumerary elements that evolve from standard A chromosomes and are primarily composed of repetitive DNAs, yet their origin, diversification, and molecular composition remain poorly understood in most vertebrates. We investigated two allopatric populations of Cyphocharax modestus (Curimatidae) combining classical cytogenetics, comparative genomic hybridization (CGH), and comparative satellitomics to characterize the repetitive DNA landscape of its B chromosomes. While both populations exhibited a conserved karyotype of 2n=54 biarmed chromosomes, five individuals from the Batalha River (BR) carried supernumerary chromosomes, comprising two distinct variants: a C-positive B1 and an C-negative B2. Comparative satellitome analysis between 3B-carrying and B-lacking individuals identified 116 satellite DNAs (CmoSatDNAs), with the 3B library showing higher abundances of specific sequences. Fluorescence in situ hybridization (FISH) revealed that both B variants share two centromeric satellites (CmoSat01-192 and CmoSat02-108) with the A complement, while CmoSat58-47 was exclusively to B2. Minimum spanning tree analysis of CmoSat58-47 revealed B-exclusive haplotypes alongside haplotypes shared with B-lacking individuals, suggesting a recent origin for these chromosomes. CGH experiments further confirm the sequence sharing between the A and B chromosomes, supporting an intraspecific origin, and revealing substantial genomic differentiation among B variants.

Animals↗

PubMed2025

Repetitive DNAs and differentiation of the ZZ/ZW sex chromosome system in the combtail fish Belontia hasselti (Perciformes: Osphronemidae).

BACKGROUND: Java combtail fish Belontia hasselti (Cuvier, 1831), a member of the Osphronemidae family, inhabits lakes and rivers throughout Southeast Asia and Sri Lanka. Previous cytogenetic research revealed it possesses a diploid chromosome number of 48 chromosomes with a female-heterogametic ZZ/ZW sex chromosome system, where the W chromosome is distinguishable as the only metacentric element in the complement. Female-heterogametic sex chromosome systems seem to be otherwise surprisingly rare in the highly diverse order Perciformes and, therefore, B. hasselti provides an important comparative model to evolutionary studies in this teleost lineage. To examine the level of sex chromosome differentiation in B. hasselti and the contribution of repetitive DNAs to this process we combined bioinformatic analyses with chromosomal mapping of selected repetitive DNA classes, and comparative genomic hybridization. RESULTS: By providing the first satellitome study in Perciformes, we herein identified 13 satellite DNA monomers in B. hasselti, suggesting a very low diversity of satDNA in this fish species. Using fluorescence in situ hybridization, we revealed detectable clusters on chromosomes only for four satellite DNA monomers. Together with the two mapped microsatellite motifs, the repeats primarily accumulated on autosomes, with no distinct clusters located on the sex chromosomes. Comparative genomic hybridization showed no region with accumulated female-specific or enriched repeats on the W chromosome. Telomeric repeats terminated all chromosomes, and no additional interstitial sites were detected. CONCLUSION: These data collectively indicate a low degree of sex chromosome differentiation in B. hasselti despite their considerable heteromorphy. Possible mechanisms that may underlie this pattern are discussed.

Animals↗