[Cytogenetic localization of the genes on avian Z and W chromosomes with the use of large insert genomic clones] Цитогенетическая локализация генов на Z- и W- хромосомах птиц при помощи протяженных геномных клонов

Благовещенский И.Ю.; Сазанова А.Л.; Романов М.Н.; Фомичев К.А.; Стекольникова В.А.; Сазанов А.А

Localization of seven HSA3q13-q23 NotI linking clones on the chicken microchromosomes 14 and 15 by double-color FISH

Double-color fluorescence in situ hybridization was performed on chicken chromosomes using seven unique clones from human chromosome 3-specific NotI linking libraries. Six of them (NL1-097, NL2-092, NL2-230, NLM-007, NLM-118, and NLM-196) hybridized to the same chicken microchromosome, while NL1-290 hybridized to another one. Two chicken microchromosome GGA15-specific BAC clones, JE024F14 containing the IGVPS gene and JE020G17 containing the ALDH1A1 gene, were cytogenetically mapped to the same microchromosome that contained the six NotI linking clones, allowing identification of this chromosome as GGA15. Two GGA14-specific clones, JE027C23 and JE014E08, containing the HBA gene cluster, were co-localized on the same microchromosome with NL1-290, marking this chromosome as GGA14. The results indicate that the human chromosome region HSA3q13-q23 is likely to be orthologous to GGA15 and GGA14. The synteny breakpoint between the human and chicken gene segments was detected on HSA3q13.3-q23 between NL1-290 and the six other NotI clones. Previously available comparative mapping data suggest another breakpoint between all the above NotI clones and four genes, TFRC, EIF4A2, SKIL and DHX36, located on HSA3q24-qter and GGA9. Microchromosomal location of seven NotI clones from the HSA3q21 T-band region can be considered as an evidence in support of our hypothesis regarding the functional analogy of mammalian T-bands and avian microchromosomes

Cytogenetic localization of avian Z- and W-linked genes using large insert BAC clones

In all studied neognathous birds, the Z–W pair of sex chromosomes shows strictly localized recombination in a very short pseudoautosomal region. There are five published W-linked genes in this region that have homologs on the Z, reflecting their common origin from an ancestral homologous chromosome pairs: CHD1, HINT, SPIN, UBAP2, and ATP5A1. Using BAC-based FISH, we have investigated in detail the genes located on the chicken Z and W chromosomes, especially those in the pseudoautosomal region. For one of them, UBAP2Z, we identified its precise cytogenetic location on the Z chromosome and mapped its W-linked counterpart, UBAP2W. The fine FISH mapping of two more homologs, ATPA5A1Z and ATPA5A1W, has been completed. By screening two gridded genomic jungle fowl BAC libraries, TAMU 031-JF256-BI and CHORI-261, with labeled amplified gene fragments or overgos, we detected four and five specific clones, respectively. BAC clones TAM31-100C09, TAM31-099N01, TAM31-027P16 and TAM31-095L18 were assigned to GGAZ at Zp23-p22 site (Flpter, 0.12 ± 0.034 to 0.15 ± 0.033). Clones CH261-046G16, CH261-033F10 and CH261-064F22 were detected on GGAZ (Flpter, 0.12 ± 0.033 to 0.14 ± 0.033). They also co-localized on GGAW, along with the CH261-114G22 BAC clone containing the GGAW-specific UBAP2W DNA sequence. We cytogenetically mapped in the chicken genome the sixth, previously unknown pair of Z- and W-linked homologs, UBE2R2Z and UBE2R2W. Using a chicken UBE2R2W-specific overgo, a positive clone was identified in the California condor BAC library and is being used for FISH in this endangered species and other birds