Meiotic Segregation of an Isodicentric Derived from Chromosome 15 in Sperm of a Patient with Mosaic Karyotype: Case Report and Review of the Literature.

Small supernumerary marker chromosomes (sSMCs) are defined as structurally abnormal chromosomes that are difficult to identify by conventional cytogenetic techniques. sSMCs are 3.75 times more common in infertile men than in the general population. This study aimed at characterizing a supernumerary marker chromosome in a nonconsanguineous infertile couple and analyzing its meiotic segregation in sperm by multicolor FISH. The male partner's karyotype was mos 47,XY,+idic(15)(pter→q11.1::q11.1→pter)[6]/46,XY[24].ish idic(15)(NOR+,D15Z3+,SNRPN-,D15Z3+,NOR+). In triple FISH using CEP 15, BAC 15, and BAC 21 probes, 4,227 spermatozoa of the patient were analyzed, and the sSMC was detected in only 0.66% of spermatozoa. In triple FISH employing CEP X, CEP Y, and BAC 18 probes, 2,008 spermatozoa of the patient were analyzed. The frequency of disomic and diploid sperm was not significantly different from control donors. To our knowledge, segregation of an sSMC 15 has been reported in only 9 males with non-mosaic karyotypes. These studies described rates of spermatozoa with sSMC 15 ranging from 6.23% to more than 50%. In this work, we report the first meiotic segregation analysis of a chromosome 15-derived sSMC in spermatozoa of a patient with a mosaic karyotype. The low rate of spermatozoa with sSMC detected is concordant with the low proportion of abnormal cells in our patient's lymphocytes. Moreover, the risk of interference of this sSMC with other chromosomes seems minimal. Genetic counseling was recommended given that the risk of chromosomal imbalance in the fetus linked to paternal sSMC was very low. Finally, a healthy boy was born after a natural pregnancy.

MACS-annexin V cell sorting of semen samples with high TUNEL values decreases the concentration of cells with abnormal chromosomal content: a pilot study.

We question whether, in men with an abnormal rate of sperm DNA fragmentation, the magnetic-activated cell sorting (MACS) could select spermatozoa with lower rates of DNA fragmentation as well as spermatozoa with unbalanced chromosome content. Cryopreserved spermatozoa from six males were separated into nonapoptotic and apoptotic populations. We determined the percentages of spermatozoa with (i) externalization of phosphatidylserine (EPS) by annexin V-Fluorescein isothiocyanate (FITC) labeling, (ii) DNA fragmentation by TdT-mediated-dUTP nick-end labeling (TUNEL), and (iii) numerical abnormalities for chromosomes X, Y, 13, 18, and 21 by fluorescence in situ hybridization (FISH), on the whole ejaculate and selected spermatozoa in the same patient. Compared to the nonapoptotic fraction, the apoptotic fraction statistically showed a higher number of spermatozoa with EPS, with DNA fragmentation, and with numerical chromosomal abnormalities. Compared to the whole ejaculate, we found a significant decrease in the percentage of spermatozoa with EPS and decrease tendencies of the DNA fragmentation rate and the sum of disomy levels in the nonapoptotic fraction. Conversely, we observed statistically significant higher rates of these three parameters in the apoptotic fraction. MACS may help to select spermatozoa with lower rates of DNA fragmentation and unbalanced chromosome content in men with abnormal rates of sperm DNA fragmentation.

Virulence of Vibrio harveyi ORM4 towards the European abalone Haliotis tuberculata involves both quorum sensing and a type III secretion system.

Environmental Vibrio strains represent a major threat in aquaculture, but the understanding of their virulence mechanisms heavily relies on the transposition of knowledge from human-pathogen vibrios. Here, the genetic bases of the virulence of Vibrio harveyi ORM4 towards the European abalone Haliotis tuberculata were characterized. We demonstrated that luxO, encoding a major regulator of the quorum sensing system, is crucial for the virulence of this strain, and that its deletion leads to a decrease in swimming motility, biofilm formation, and exopolysaccharide production. Furthermore, the biofilm formation by V. harveyi ORM4 was increased by abalone serum, which required LuxO. The absence of LuxO in V. harveyi ORM4 yielded opposite phenotypes compared with other Vibrio species including V. campbellii (still frequently named V. harveyi). In addition, we report a full type III secretion system (T3SS) gene cluster in the V. harveyi ORM4 genome. LuxO was shown to negatively regulate the promoter activity of exsA, encoding the major regulator of the T3SS genes, and the deletion of exsA abolished the virulence of V. harveyi ORM4. These results unveil virulence mechanisms set up by this environmentally important bacterial pathogen and pave the way for a better molecular understanding of the regulation of its pathogenicity.