Y chromosomal microdeletions at the azoospermia factor locus and chromosome abnormalities have been implicated as the major causes of idiopathic male infertility. A marker chromosome is a structurally abnormal chromosome in which no part can be identified by cytogenetics. In this study, to identify the origin of the marker chromosomes and to perform a genetic diagnosis of patients with azoospermia, two-color fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) techniques were carried out.
Fluorescence in situ hybridization
The alternative forms of the alleles in biallelic genes display a synchronous pattern of replication that is different from genes subjected to monoallelic expression, which exhibit an asynchronous mode of replication. The present study sought to gain insight into changes in the allele-specific replication timing in phenotypically normal humans with balanced chromosomal rearrangements, and to investigate the potential mechanism for chromosomal rearrangements.
We cytogenetically characterized three species of Heptapteridae (Pimelodella sp, Pimelodella taenioptera, and Imparfinis schubarti) by investigating the distribution of constitutive heterochromatin and nucleolar organizer regions by silver nitrate impregnation (Ag-NOR) and fluorescence in situ hybridization. Pimelodella sp showed had a diploid number (2n) = 46 chromosomes, 26m + 10sm + 10st, and FN = 92; P. taenioptera, 2n = 52 chromosomes, 26m + 22sm + 4st, and FN = 104; and I.