Distribution of Telomeric DNA Sequences on the X-Radiation-Induced Chromosome Fragments Observed in the Genome of Androgenetic Brook Trout (<b><i>Salvelinus fontinalis</i></b>, Mitchill 1814)

Abstract

Cytogenetic screening of the androgenetic brook trout (Salvelinus fontinalis, Mitchill 1814) offspring hatched from eggs exposed to 420 Gy of X-radiation before insemination exhibited residues of the irradiated maternal nuclear genome in the form of small chromosome fragments. Remnants of the irradiated chromosomes had different sizes, and their number varied intraindividually from 1 to 15. To efficiently pass through the series of the cell divisions, such chromosome fragments must have had functional kinetochores. Distribution patterns of the telomeric hybridization signals on the chromosome fragments enabled us to distinguish their 3 groups: (i) telomere-less ring chromosomes with fused broken chromosome arms, (ii) rings formed in the course of fusion of the radiation-broken chromosome arm with the opposite telomeric region and exhibiting interstitial telomeric signals at the fusion point, and (iii) chromosome fragments with fused unprotected sister chromatids of 1 broken arm and intact telomeres from the other arm. Disturbances during segregation of such fragments, mainly breakages during anaphase, may partially explain intraindividual variation in the number and size of the chromosome fragments observed in the androgenetic brook trout.

Induction of Gynogenetic and Androgenetic Haploid and Doubled Haploid Development in the Brown Trout (Salmo trutta Linnaeus 1758)

“…Low doses of UV-and X-radiation applied to damage nuclear DNA in the spermatozoa and eggs resulted in the incomplete genetic inactivation of the brown trout gametes. Residues of the irradiated chromosomes may interfere with the cell cleavages and provoke consequent chromosome rearrangements what in turn may increase mortality among the doubled haploids (Ocalewicz et al 2012). Furthermore, genes from the radiation-induced chromosome fragments may contain mutated genetic information that is harmful for the haploid and doubled haploid individuals.…”

High-resolution chromosome painting with repetitive and single-copy oligonucleotides in Arachis species identifies structural rearrangements and genome differentiation

“…Staining with 4′, 6-diamidino-2-phenylindole (DAPI) and the use of rDNA probes are major tools that are traditionally used to differentiate peanut chromosomes [ 5 – 8 ]. The application of centromeric and telomeric repeat probes has significantly improved the ability to resolve Arachis karyotypes [ 9 , 10 ]. Zhang et al [ 11 ] identified seven A. duranensis bacterial artificial chromosome (BAC) clones that facilitated the differentiation of almost all chromosomes of peanut.…”