Abstract
BackgroundNon-random chromosome positioning has been observed in the nuclei of several different tissue types, including human spermatozoa. The nuclear arrangement of chromosomes can be altered in men with decreased semen parameters or increased DNA fragmentation and in males with chromosomal numerical or structural aberrations. An aim of this study was to determine whether and how the positioning of nine chromosome centromeres was (re)arranged in the spermatozoa of fathers and sons – carriers of the same reciprocal chromosome translocation (RCT).MethodsFluorescence in situ hybridization (FISH) was applied to analyse the positioning of sperm chromosomes in a group of 13 carriers of 11 RCTs, including two familial RCT cases: t(4;5) and t(7;10), followed by analysis of eight control individuals. Additionally, sperm chromatin integrity was evaluated using TUNEL and Aniline Blue techniques.ResultsIn the analysed familial RCT cases, repositioning of the chromosomes occurred in a similar way when compared to the data generated in healthy controls, even if some differences between father and son were further observed. These differences might have arisen from various statuses of sperm chromatin disintegration.ConclusionsNuclear topology appears as another aspect of epigenetic genomic regulation that may influence DNA functioning. We have re-documented that chromosomal positioning is defined in control males and that a particular RCT is reflected in the individual pattern of chromosomal topology. The present study examining the collected RCT group, including two familial cases, additionally showed that chromosomal factors (karyotype and hyperhaploidy) have superior effects, strongly influencing the chromosomal topology, when confronted with sperm chromatin integrity components (DNA fragmentation or chromatin deprotamination).
Highlights
Non-random chromosome positioning has been observed in the nuclei of several different tissue types, including human spermatozoa
Analysis of the linear positioning revealed that the centromeres of all evaluated chromosomes in control males were preferentially localized in the middle part of the sperm nucleus (‘m’; 53.16–66.85%) (Table 2)
Interesting findings were revealed when analysing the number of hyperhaploid chromosomes in familial reciprocal chromosome translocation (RCT) cases, in which we found that a higher level of hyperhaploidy of X and Y chromosomes resulted in a greater number of repositioned chromosomes
Summary
Non-random chromosome positioning has been observed in the nuclei of several different tissue types, including human spermatozoa. The size and location of the CT depends on the size of the chromosome, gene density, transcriptional activity, phases of the cell cycle and cell type [1, 2] Along with interchromatin compartments (ICs), topologically associated domains (TADs) constitute a fundamental structural unit and interact with elements of the nuclear matrix, creating the intranuclear architecture [1, 3,4,5]. Such a nuclear organization has been suggested as one of the elements adjusting epigenetic mechanisms that may regulate genome functioning. The nuclear order of chromosomes can be altered in males with decreased semen parameters, increased DNA fragmentation and chromosomal aberrations, both structural (reciprocal translocation) as well as numerical (sperm hyperhaploidy, marker chromosome) [21,22,23,24,25,26,27,28]
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