Polymorphisms Within DNA Double-Strand Breaks Repair-Related Genes Contribute to Structural Chromosome Abnormality in Recurrent Pregnancy Loss

Background: Structural chromosome abnormality (SCA) is an important cause of human diseases, including recurrent pregnancy loss (RPL). DNA double-strand breaks (DSBs) repair-related genes play critical roles in SCA. The present study aims to investigate the potential contribution of DSBs repair-related gene polymorphisms to SCA.Methods: Fifty-four affected RPL individuals with SCA, 88 affected RPL individuals without SCA, and 84 controls were analyzed. Targeted whole-exome sequencing (WES) was used for screening single nucleotide polymorphisms in six DSBs repair-related genes (EP300, XRCC6, LIG4, XRCC4, PRKDC, and DCLRE1C), and validation was performed by Sanger sequencing. Finally, we detected the frequency of radiation-induced chromosome translocations in no SCA samples with significant polymorphisms by fluorescence in situ hybridization (FISH).Results: A total of 35 polymorphisms have been identified and confirmed. Frequencies of EP300 rs20551, XRCC6 rs132788, and LIG4 rs1805388 were significantly different between SCA RPL and no SCA RPL (p = 0.030, 0.031, and 0.040 respectively). Frequencies of those three gene polymorphisms between SCA RPL and controls also were significantly different (p = 0.017, 0.028, and 0.029 respectively). Moreover, the frequency of the G allele at rs20551 locus, the T allele at rs132788 locus and the A allele at rs1805388 locus was significantly higher in SCA RPL than no SCA RPL (OR = 3.227, p = 0.005; OR = 1.978, p = 0.008 and OR = 1.769, p = 0.036 respectively) and controls (OR = 7.130, p = 0.000; OR = 2.157, p = 0.004; OR = 2.397, p = 0.003 respectively). Additionally, the frequency of radiation-induced translocation in no SCA samples with rs20551, rs132788 or rs1805388 was significantly higher compared with the wild type samples (p = 0.015, 0.012, and 0.007 respectively).Conclusion: Our results suggest that rs20551, rs132788, and rs1805388 might be associated with the risk of SCA. Larger scales of genetic variations studies and functional experiments are necessary to further confirm these findings.

Association of X Chromosome Aberrations with Male Infertility

Male infertility is caused by spermatogenetic failure, clinically noted as oligoor azoospermia. Approximately 20% of infertile patients carry a genetic defect. The most frequent genetic defect leading to azoospermia (or severe oligozoospermia) is Klinefelter syndrome (47, XXY), which is numerical chromosomal abnormality and Y- structural chromosome aberration. The human X chromosome is the most stable of all human chromosomes. The X chromosome is loaded with regions of acquired, rapidly evolving genes. The X chromosome may actually play an essential role in male infertility and sperm production. Here we will describe X chromosome aberrations, which are associated with male infertility.

Structural Chromosome Instability: Types, Origins, Consequences, and Therapeutic Opportunities

Chromosomal instability (CIN) refers to an increased rate of acquisition of numerical and structural changes in chromosomes and is considered an enabling characteristic of tumors. Given its role as a facilitator of genomic changes, CIN is increasingly being considered as a possible therapeutic target, raising the question of which variables may convert CIN into an ally instead of an enemy during cancer treatment. This review discusses the origins of structural chromosome abnormalities and the cellular mechanisms that prevent and resolve them, as well as how different CIN phenotypes relate to each other. We discuss the possible fates of cells containing structural CIN, focusing on how a few cell duplication cycles suffice to induce profound CIN-mediated genome alterations. Because such alterations can promote tumor adaptation to treatment, we discuss currently proposed strategies to either avoid CIN or enhance CIN to a level that is no longer compatible with cell survival.

KARYOTYPAL VARIABILITY OF CARPATHIAN BROWN COWS

Brown Carpathian breed of cattle bred in Transcarpathia at the end of the XIX century. and belongs to the breeds of dairy and meat productivity. Animals of the modern breed are direct descendants of the ancient Brown Carpathian cattle, common at one time throughout Central Europe. The main advantage of the Brown Carpathian breed is that it can be effectively grown on natural pastures – both in the lowlands and in the mountains. The genetics of these animals are resistant to acute infectious diseases, they are well adapted to local conditions, sensitive to improved housing and feeding conditions, and cows produce special milk, which is used in the manufacture of high quality hard cheeses and baby food. Animals of the Brown Carpathian breed belong to the local small domestic breeds and are in a state of significant risk. The uterine population is bred only in households. The aim of our work was to study the karyotype variability of Brown Carpathian cows, which is quite relevant today. Cytogenetic analysis, which was aimed at establishing the karyotypic variability of Brown Carpathian cows, was performed in the village. Nyzhni Vorota, Volovets district, Zakarpattia region, in households. Purebred cows of Brown Carpathian breed – (16 heads) and local animals – (11 heads) were studied. According to the results of cytogenetic analysis, genomic disorders, aneuploidy, were found in purebred cows of Brown Carpathian breed, which was 1.6% and was expressed mainly by hypoploid cells 2n = 56–58. For domestic animals, the frequency of metaphase plates with aneuploidy was 3.3%, which corresponds to a spontaneous level of cytogenetic variability. Structural chromosome abnormalities, chromosomal breaks, in purebred cows were equal to 0.76%, which does not exceed the spontaneous level of chromosomal variability. In local animals, this variability did not manifest itsel. The indicators of the micronucleus test (the proportion of lymphocytes with a micronucleus of 1.7–2.0‰, dinuclear lymphocytes 1.5–2.7‰, and the mitotic index of 4.8–5.5‰, respectively) in domestic animals are higher compared to purebred animals, however, do not exceed those of the species Bos taurus. According to the results of the cytogenetic analysis, it was established that purebred cows of Brown Carpathian breed and their crossbreeds were characterized by quantitative and structural chromosome disorders. Genomic disorders, aneuploidy, in local animals are 2 times higher (3.3%) compared to purebred cows of Brown Carpathian breed with a statistically significant difference in mean values (P > 0.99). Low level or absence of structural disorders of chromosomes in purebred animals and their crossbreeds indicates a low degree of somatic mutagenesis. The indicators of the micronucleus test, as an indicator of the effect of the total mutagenic load on the body of the studied cows, in domestic animals are higher compared to purebred animals, however, do not exceed those characteristic of the species Bos taurus. It was established that the level of somatic mutagenesis is lower and the karyotype is more stable in purebred animals of the Brown Carpathian breed in comparison with the local ones.

DNA-Replikationsstress, Mitose und genomische Instabilität

Chromosomal instability (CIN) is a hallmark of cancer and contributes to tumorigenesis and tumor progression. While structural CIN (S-CIN) leads to structural chromosome aberrations, whole chromosome instability (W-CIN) is defined by perpetual gains or losses of chromosomes during mitosis causing aneuploidy. Mitotic defects, but also abnormal DNA replication (replication stress) can lead to W-CIN. However, the functional link between replication stress, mitosis and aneuploidy is little understood.

Condensins are essential for Pseudomonas aeruginosa corneal virulence through their control of phenotypic programs

Pseudomonas aeruginosa is a significant opportunistic pathogen responsible for a variety of human infections. Its high pathogenicity resides in a diverse array of virulence factors and an ability to adapt to hostile environments. We report that these factors are tied to the activity of condensins, SMC and MksBEF, which primarily function in structural chromosome maintenance. This study revealed that both proteins are required for P. aeruginosa virulence during corneal infection. The reduction in virulence was traced to broad changes in gene expression. Transcriptional signatures of smc and mksB mutants were largely dissimilar and non-additive, with the double mutant displaying a distinct gene expression profile. Affected regulons included those responsible for lifestyle control, primary metabolism, surface adhesion and biofilm growth, iron and sulfur assimilation, and denitrification. Additionally, numerous virulence factors were affected, including type 3 and type 6 secretion systems, hemagglutinin, pyocin and macroglobulin production, and a host of virulence regulators. in vitro properties of condensin mutants mirrored their transcriptional profiles. MksB-deficient cells were impaired in pyocyanin, c-di-GMP production, and sessile growth whereas smc mutants mildly upregulated c-di-GMP, secreted fewer proteases and were growth deficient under nutrient-limiting conditions. Moreover, condensin mutants displayed an abnormal regulation upon transition to stationary phase. These data reveal that condensins are integrated into the control of multiple genetic programs related to epigenetic and virulent behavior, establishing condensins as an essential factor in P. aeruginosa ocular infections.Author SummaryBacterial pathogenicity is a complex phenomenon dependent on the ability of a bacterium to thrive in a hostile environment while combating the host using an array of virulence factors. This study reports that pathogenicity is also tied to structural chromosome maintenance through condensins, proteins that are responsible for the global organization of the chromosome. We show that the two Pseudomonas aeruginosa condensins, SMC and MksB, act as global regulators of gene expression. The inactivation of SMC and MksB induces opposite regulatory programs in the cell that resemble those observed during the acute and chronic phases of infection. A substantial portion of this regulation is mediated by the intracellular signaling network of P. aeruginosa. Accordingly, virulence regulation is altered in condensin mutants. The results were validated by genetic, phenotypic and virulence studies of condensin mutants. Overall, these data establish condensins as an essential factor during ocular P. aeruginosa infections revealing their involvement in the regulatory virulence network and the control of the bacterial lifestyle.

Chromosome Painting in Cultivated Bananas and Their Wild Relatives (Musa spp.) Reveals Differences in Chromosome Structure

Edible banana cultivars are diploid, triploid, or tetraploid hybrids, which originated by natural cross hybridization between subspecies of diploid Musa acuminata, or between M. acuminata and diploid Musa balbisiana. The participation of two other wild diploid species Musa schizocarpa and Musa textilis was also indicated by molecular studies. The fusion of gametes with structurally different chromosome sets may give rise to progenies with structural chromosome heterozygosity and reduced fertility due to aberrant chromosome pairing and unbalanced chromosome segregation. Only a few translocations have been classified on the genomic level so far, and a comprehensive molecular cytogenetic characterization of cultivars and species of the family Musaceae is still lacking. Fluorescence in situ hybridization (FISH) with chromosome-arm-specific oligo painting probes was used for comparative karyotype analysis in a set of wild Musa species and edible banana clones. The results revealed large differences in chromosome structure, discriminating individual accessions. These results permitted the identification of putative progenitors of cultivated clones and clarified the genomic constitution and evolution of aneuploid banana clones, which seem to be common among the polyploid banana accessions. New insights into the chromosome organization and structural chromosome changes will be a valuable asset in breeding programs, particularly in the selection of appropriate parents for cross hybridization.

Chromosome painting in cultivated banana and their wild relatives (Musa spp.) reveals differences in chromosome structure

Edible banana cultivars are diploid, triploid or tetraploid hybrids which originated by natural cross hybridization between subspecies of diploid Musa acuminata, or between M. acuminata and diploid M. balbisiana. Participation of two other wild diploid species M. schizocarpa and M. textilis was also indicated by molecular studies. Fusion of gametes with structurally different chromosome sets may give rise to progenies with structural chromosome heterozygosity and reduced fertility due to aberrant chromosome pairing and unbalanced chromosome segregation. Only a few translocations have been classified on the genomic level so far and a comprehensive molecular cytogenetic characterization of cultivars and species of the family Musaceae is still lacking. FISH with chromosome-arm specific oligo painting probes was used for comparative karyotype analysis in a set of wild Musa species and edible banana clones. The results revealed large differences in chromosome structure discriminating individual accessions. These results permitted identification of putative progenitors of cultivated clones and clarified genomic constitution and evolution of aneuploid banana clones, which seem to be common among the polyploid banana accessions. New insights into the chromosome organization and structural chromosome changes will be a valuable asset in breeding programs, particularly in selection of appropriate parents for cross hybridization.HighlightOligo painting FISH revealed chromosomal translocations in subspecies of Musa acuminata (A genome), their intra-specific hybrids as well as in M. balbisiana (B genome) and in interspecific hybrid clones originating from cross hybridization between M. acuminata and M. balbisiana