Common genetic variants and modification of penetrance of BRCA2-associated breast cancer

The considerable uncertainty regarding cancer risks associated with inherited mutations of BRCA2 is due to unknown factors. To investigate whether common genetic variants modify penetrance for BRCA2 mutation carriers, we undertook a two-staged genome-wide association study in BRCA2 mutation carriers. In stage 1 using the Affymetrix 6.0 platform, 592,163 filtered SNPs genotyped were available on 899 young (<40 years) affected and 804 unaffected carriers of European ancestry. Associations were evaluated using a survival-based score test adjusted for familial correlations and stratified by country of the study and BRCA2*6174delT mutation status. The genomic inflation factor (λ) was 1.011. The stage 1 association analysis revealed multiple variants associated with breast cancer risk: 3 SNPs had p-values<10(-5) and 39 SNPs had p-values<10(-4). These variants included several previously associated with sporadic breast cancer risk and two novel loci on chromosome 20 (rs311499) and chromosome 10 (rs16917302). The chromosome 10 locus was in ZNF365, which contains another variant that has recently been associated with breast cancer in an independent study of unselected cases. In stage 2, the top 85 loci from stage 1 were genotyped in 1,264 cases and 1,222 controls. Hazard ratios (HR) and 95% confidence intervals (CI) for stage 1 and 2 were combined and estimated using a retrospective likelihood approach, stratified by country of residence and the most common mutation, BRCA2*6174delT. The combined per allele HR of the minor allele for the novel loci rs16917302 was 0.75 (95% CI 0.66-0.86, ) and for rs311499 was 0.72 (95% CI 0.61-0.85, ). FGFR2 rs2981575 had the strongest association with breast cancer risk (per allele HR = 1.28, 95% CI 1.18-1.39, ). These results indicate that SNPs that modify BRCA2 penetrance identified by an agnostic approach thus far are limited to variants that also modify risk of sporadic BRCA2 wild-type breast cancer.     

Neutral sphingomyelinase-induced ceramide triggers germinal vesicle breakdown and oxidant-dependent apoptosis in Xenopus laevis oocytes

Ceramide regulates many cellular processes, including cell growth, differentiation, and apoptosis. Although the effects of exogenous bacterial neutral sphingomyelinase (SMase) in Xenopus laevis oocytes have been investigated, its microinjection into oocytes has not been reported previously. Thus, we compared the incubation versus microinjection of the neutral Bacillus cereus sphingomyelinase (bSMase) to examine whether the topology of ceramide generation determines its effects on the fate of oocytes. In agreement with previous findings, incubation of mature stage VI oocytes with bSMase increased ceramide levels in oocyte extracts over time, causing the germinal vesicle breakdown indicative of maturation, without evidence of cytotoxicity. In contrast, bSMase microinjection, which increased ceramide levels in a time- and dose-dependent manner, resulted in oocyte apoptosis characterized by reactive oxygen species (ROS) generation, reduced glutathione (GSH) depletion in cytosol and mitochondria, release of cytochrome c and Smac/Diablo from mitochondria, and caspase-3 activation. Microinjection of acidic SMase from human placenta recapitulated the apoptotic effects of bSMase microinjection. Preincubation of oocytes with GSH-ethyl ester before bSMase microinjection prevented ROS generation and mitochondrial downstream events, thus protecting oocytes from bSMase-induced death. These findings show a divergent action of bSMase-induced ceramide on oocyte maturation or apoptosis depending on the intracellular site where ceramide is generated.     

Recreational angling and spearfishing on social media: insights on harvesting patterns,social engagement and sentiments related to the distributional range shift of a marine invasive species

Reviews in Fish Biology and Fisheries - Fisheries are among the human activities that are most strongly affected by ongoing climate-related changes in the presence and abundance of fish species...     

Morphological parameters of abundant and threatened chondrichthyans of the northwestern Mediterranean Sea

The diversity of chondrichthyans in the Mediterranean Sea is relatively high; however, available data indicate that this group is declining in abundance and several species are becoming rare. As a result, the collection of biological data is a priority for demographic models, stock assessments, and food web analysis. In the present study, we report morphological parameters and length–weight relationships of several chondrichthyan species, both abundant and threatened, from the western Mediterranean Sea. Samples were obtained with commercial and scientific bottom trawl vessels between 2001 and 2013. A total of 893 individuals belonging to 11 families and 20 species were weighed and total lengths measured. In addition, seven species of large demersal sharks were measured and length–length relationships obtained to study the relationships between different body length measurements. All species showed positive allometric or isometric growth, except for Centroscymnus coelolepis. The results of the length–weight relationships reveal differences between the western Mediterranean and nearby areas, depending on the species studied.     

Pluripotency and Epigenetic Factors in Mouse Embryonic Stem Cell Fate Regulation

Embryonic stem cells (ESCs) are characterized by their ability to self-renew and to differentiate into all cell types of a given organism. Understanding the molecular mechanisms that govern the ESC state is of great interest not only for basic research—for instance, ESCs represent a perfect system to study cellular differentiation in vitro—but also for their potential implications in human health, as these mechanisms are likewise involved in cancer progression and could be exploited in regenerative medicine. In this minireview, we focus on the latest insights into the molecular mechanisms mediated by the pluripotency factors as well as their roles during differentiation. We also discuss recent advances in understanding the function of the epigenetic regulators, Polycomb and MLL complexes, in ESC biology.     

Functional validation of mouse tyrosinase non-coding regulatory DNA elements by CRISPR–Cas9-mediated mutagenesis

Newly developed genome-editing tools, such as the clustered regularly interspaced short palindromic repeat (CRISPR)–Cas9 system, allow simple and rapid genetic modification in most model organisms and human cell lines. Here, we report the production and analysis of mice carrying the inactivation via deletion of a genomic insulator, a key non-coding regulatory DNA element found 5′ upstream of the mouse tyrosinase (Tyr) gene. Targeting sequences flanking this boundary in mouse fertilized eggs resulted in the efficient deletion or inversion of large intervening DNA fragments delineated by the RNA guides. The resulting genome-edited mice showed a dramatic decrease in Tyr gene expression as inferred from the evident decrease of coat pigmentation, thus supporting the functionality of this boundary sequence in vivo, at the endogenous locus. Several potential off-targets bearing sequence similarity with each of the two RNA guides used were analyzed and found to be largely intact. This study reports how non-coding DNA elements, even if located in repeat-rich genomic sequences, can be efficiently and functionally evaluated in vivo and, furthermore, it illustrates how the regulatory elements described by the ENCODE and EPIGENOME projects, in the mouse and human genomes, can be systematically validated.