Diploids in the Cryptococcus neoformans Serotype A Population Homozygous for the α Mating Type Originate via Unisexual Mating

The ubiquitous environmental human pathogen Cryptococcus neoformans is traditionally considered a haploid fungus with a bipolar mating system. In nature, the α mating type is overwhelmingly predominant over a. How genetic diversity is generated and maintained by this heterothallic fungus in a largely unisexual α population is unclear. Recently it was discovered that C. neoformans can undergo same-sex mating under laboratory conditions generating both diploid intermediates and haploid recombinant progeny. Same-sex mating (α-α) also occurs in nature as evidenced by the existence of natural diploid αADα hybrids that arose by fusion between two α cells of different serotypes (A and D). How significantly this novel sexual style contributes to genetic diversity of the Cryptococcus population was unknown. In this study, ∼500 natural C. neoformans isolates were tested for ploidy and close to 8% were found to be diploid by fluorescence flow cytometry analysis. The majority of these diploids were serotype A isolates with two copies of the α MAT locus allele. Among those, several are intra-varietal allodiploid hybrids produced by fusion of two genetically distinct α cells through same-sex mating. The majority, however, are autodiploids that harbor two seemingly identical copies of the genome and arose via either endoreplication or clonal mating. The diploids identified were isolated from different geographic locations and varied genotypically and phenotypically, indicating independent non-clonal origins. The present study demonstrates that unisexual mating produces diploid isolates of C. neoformans in nature, giving rise to populations of hybrids and mixed ploidy. Our findings underscore the importance of same-sex mating in shaping the current population structure of this important human pathogenic fungus, with implications for mechanisms of selfing and inbreeding in other microbial pathogens

Prognostic relevance of Wnt-inhibitory factor-1 (WIF1) and Dickkopf-3 (DKK3) promoter methylation in human breast cancer

BACKGROUND: Secreted Wnt signaling antagonists have recently been described as frequent targets of epigenetic inactivation in human tumor entities. Since gene silencing of certain Wnt antagonists was found to be correlated with adverse patient survival in cancer, we aimed at investigating a potential prognostic impact of the two Wnt antagonizing molecules WIF1 and DKK3 in breast cancer, which are frequently silenced by promoter methylation in this disease. METHODS: WIF1 and DKK3 promoter methylation were assessed by methylation-specific PCR with bisulfite-converted DNA from 19 normal breast tissues and 150 primary breast carcinomas. Promoter methylation was interpreted in a qualitative, binary fashion. Statistical evaluations included two-sided Fisher's exact tests, univariate log-rank tests of Kaplan-Meier curves as well as multivariate Cox regression analyses. RESULTS: WIF1 and DKK3 promoter methylation were detected in 63.3% (95/150) and 61.3% (92/150) of breast carcinoma samples, respectively. In normal breast tissues, WIF1 methylation was present in 0% (0/19) and DKK3 methylation in 5.3% (1/19) of samples. In breast carcinomas, WIF1 methylation was significantly associated with methylation of DKK3 (p = 0.009). Methylation of either gene was not associated with clinicopathological parameters, except for DKK3 methylation being associated with patient age (p = 0.007). In univariate analysis, WIF1 methylation was not associated with clinical patient outcome. In contrast, DKK3 methylation was a prognostic factor in patient overall survival (OS) and disease-free survival (DFS). Estimated OS rates after 10 years were 54% for patients with DKK3-methylated tumors, in contrast to patients without DKK3 methylation in the tumor, who had a favorable 97% OS after 10 years (p < 0.001). Likewise, DFS at 10 years for patients harboring DKK3 methylation in the tumor was 58%, compared with 78% for patients with unmethylated DKK3 (p = 0.037). Multivariate analyses revealed that DKK3 methylation was an independent prognostic factor predicting poor OS (hazard ratio (HR): 14.4; 95% confidence interval (CI): 1.9-111.6; p = 0.011), and short DFS (HR: 2.5; 95% CI: 1.0-6.0; p = 0.047) in breast cancer. CONCLUSION: Although the Wnt antagonist genes WIF1 and DKK3 show a very similar frequency of promoter methylation in human breast cancer, only DKK3 methylation proves as a novel prognostic marker potentially useful in the clinical management of this disease

Bisulfite-Based DNA Methylation Analysis from Recent and Archived Formalin-Fixed, Paraffin Embedded Colorectal Tissue Samples.

We aimed to test the applicability of formalin-fixed and paraffin-embedded (FFPE) tissue samples for gene specific DNA methylation analysis after using two commercially available DNA isolation kits. Genomic DNA was isolated from 5 colorectal adenocarcinomas and 5 normal adjacent tissues from "recent", collected within 6 months, and "archived", collected more than 5 years ago, FFPE tissues using either High Pure FFPET DNA Isolation kit or QIAamp DNA FFPE Tissue kit. DNA methylation analysis of MAL, SFRP1 and SFRP2 genes, known to be hypermethylated in CRC, was performed using methylation-sensitive high resolution melting (MS-HRM) analysis and sequencing. QIAamp (Q) method resulted in slightly higher recovery in archived (HP: 1.22 +/- 3.18mug DNA; Q: 3.00 +/- 4.04mug DNA) and significantly (p < 0.05) higher recovery in recent samples compared to High Pure method (HP) (HP: 4.10 +/- 2.91mug DNA; Q: 11.51 +/- 7.50mug DNA). Both OD260/280 and OD260/230 ratios were lower, but still high in the High Pure isolated archived and recent samples compared to those isolated with QIAamp. Identical DNA methylation patterns were detected for all 3 genes tested by MS-HRM with both isolation kits in the recent group. However, despite of higher DNA recovery in QIAamp slightly more reproducible methylation results were obtained from High Pure isolated archived samples. Sequencing confirmed DNA hypermethylation in CRCs. In conclusion, reproducible DNA methylation patterns were obtained from recent samples using both isolation kits. However, long term storage may affect the reliability of the results leading to moderate differences between the efficiency of isolation kits

Sutureless versus conventional bioprostheses for aortic valve replacement in severe symptomatic aortic valve stenosis

Objective: Sutureless aortic valves are a novel option for aortic valve replacement. We sought to demonstrate noninferiority of sutureless versus standard bioprostheses in severe symptomatic aortic stenosis. Methods: The Perceval Sutureless Implant Versus Standard-Aortic Valve Replacement is a prospective, randomized, adaptive, open-label trial. Patients were randomized (March 2016 to September 2018) to aortic valve replacement with a sutureless or stented valve using conventional or minimally invasive approach. Primary outcome was freedom from major adverse cerebral and cardiovascular events (composite of all-cause death, myocardial infarction, stroke, or valve reintervention) at 1 year. Results: At 47 centers (12 countries), 910 patients were randomized to sutureless (n = 453) or conventional stented (n = 457) valves; mean ages were 75.4 ± 5.6 and 75.0 ± 6.1 years, and 50.1% and 44.9% were female, respectively. Mean ± standard deviation Society of Thoracic Surgeons scores were 2.4 ± 1.7 and 2.1 ± 1.3, and a ministernotomy approach was used in 50.4% and 47.3%, respectively. Concomitant procedures were performed with similar rates in both groups. Noninferiority was demonstrated for major adverse cerebral and cardiovascular events at 1 year, whereas aortic valve hemodynamics improved equally in both groups. Use of sutureless valves significantly reduced surgical times (mean extracorporeal circulation times: 71.0 ± 34.1 minutes vs 87.8 ± 33.9 minutes; mean crossclamp times: 48.5 ± 24.7 vs 65.2 ± 23.6; both P <.0001), but resulted in a higher rate of pacemaker implantation (11.1% vs 3.6% at 1 year). Incidences of perivalvular and central leak were similar. Conclusions: Sutureless valves were noninferior to stented valves with respect to major adverse cerebral and cardiovascular events at 1 year in patients undergoing aortic valve replacement (alone or with coronary artery bypass grafting). This suggests that sutureless valves should be considered as part of a comprehensive valve program