Evaluation of four commonly used normalizer genes for the study of decidual gene expression

Elevated prenatal maternal sex hormones, but not placental aromatase, are associated with child neurodevelopment

Fetal exposure to testosterone may contribute to vulnerability for autism spectrum disorder (ASD). It is hypothesized that placental aromatase prevents fetal exposure to maternal testosterone, however, this pathway and the implications for child neurodevelopment have not been fully explored. We examined the relationships between prenatal maternal testosterone and estradiol at 19.2 ± 1.3 weeks, cord blood testosterone and estradiol at birth, placental aromatase mRNA expression, and neurodevelopment using the Social Communication Questionnaire (SCQ), the Behavioral Assessment System for Children, 3rd Edition (BASC-3), and the Empathizing Quotient for Children (EQ-C) at 4.5-6.5 years of age in a sample of 270 Nulliparous-Mothers-to-be (nuMoM2b) study participants. Maternal testosterone levels were positively associated with SCQ scores, but the association was not significant after adjusting for maternal age at delivery, nor was there a significant interaction with sex. Maternal estradiol levels were negatively associated with BASC-3 Clinical Probability scores among males (n = 139). We report a significant interaction effect of cord blood testosterone and fetal sex on both total SCQ scores and t-scores on the Developmental Social Disorders subscale. Placental aromatase was not associated with any neurodevelopmental or hormone measure, but under conditions of low placental aromatase expression, high maternal testosterone was positively associated with SCQ scores in males (n = 46). No other associations between hormone levels and neurodevelopment were significant. Our findings provide a foundation for further investigation of the mechanisms through which maternal sex hormones and placental steroidogenesis may affect fetal hormone production and neurobehavior.

Selection of reliable reference genes for analysis of gene expression in the rat placenta

The selection of suitable reference genes (RGs), especially the identification of the proper combination of RGs is the key to obtain reliable results of gene expression for quantitative real-time polymerase chain reaction (qRT-PCR). To date, there is no relevant study dealing with the stability of RGs in rat placenta. In this study, the geNorm, NormFinder, and BestKeeper software were used to analyze the expression stability of the candidate RGs in placenta under physiological and prenatal caffeine exposure (PCE) conditions. The expression of Tbp, Gapdh and Ywhaz in female and Polr2a, Gapdh and Ywhaz in male placenta were highly stable under physiological conditions, and there was no obvious gender difference. We further found that two RGs were sufficient for reliable normalization in female and male placenta and the combination of Ywhaz and Gapdh was the most suitable compound RGs under physiological conditions. Under PCE conditions, Ywhaz, Gapdh and Polr2a were the most stable genes in both female and male placenta. Among them, Ywhaz and Gapdh were chosen as the best paring. Finally, selected RGs were employed for normalization of the expression of a clear target gene and the results of standardization supported our choice. In conclusion, our study confirmed that Ywhaz/Gapdh combination was the most suitable RGs in rat placenta under physiological and PCE pathological conditions and provided a theoretical and experimental basis for physiological and pathological research of the rat placenta.

Placental NEGR1 DNA methylation is associated with BMI and neurodevelopment in preschool-age children

Studies have linked maternal pre-pregnancy obesity and hyperglycaemia with metabolic and neurodevelopmental complications in childhood. DNA methylation (DNAm) might enable foetal adaptations to environmental adversities through important gene loci. NEGR1 is involved in both energy balance and behaviour regulation. The aim of this study was to investigate associations between placental DNAm at the NEGR1 gene locus and childhood anthropometric and neurodevelopmental profiles in preschoolers. We analysed 276 mother-child dyads from Gen3G, a prospective birth cohort from Sherbrooke. At 3yo (40.4 ± 3.0 months), we measured body mass index (BMI) and the mothers reported on offspring neurobehavior using the Strengths and Difficulties Questionnaire (SDQ). We quantified DNAm levels at 30 CpGs at the NEGR1 locus using the MethylationEPIC Array in placental biopsies. DNAm at four CpGs located before NEGR1 second exon predicted child's BMI z-score (cg26153364: β=-0.16 ± 0.04; p=0.008, cg23166710: β=0.14 ± 0.08; p=0.03) and SDQ total score (cg04932878: β=0.22 ± 1.0; p= 3.0x10^-4, cg16525738: β=-0.14 ± 0.18; p=0.01, cg23166710: β=-0.13 ± 0.36; p= 0.04), explaining 4.2% (p=0.003) and 7.3% (p= 1.3 x 10^-4) of BMI-z and SDQ variances. cg23166710 was associated with both childhood phenotypes and correlated with NEGR1 placental expression (r=-0.22, p=0.04), suggesting its possible functional role. Together, maternal metabolic characteristics during pregnancy with NEGR1 DNAm levels explained 7.4% (p=4.2 x 10^-4) of BMI-z and 14.2% (p=2.8 x 10^-7) of SDQ variance at 3yo. This longitudinal study suggests that placental NEGR1 DNAm is associated with adiposity and neurodevelopment in preschool children and highlights its potential role in their comorbidity.

Selection and validation of reliable housekeeping genes to evaluate Piscirickettsia salmonis gene expression

Piscirickettsia salmonis is a highly aggressive facultative intracellular bacterium that challenges the sustainability of Chilean salmon production. Due to the limited knowledge of its biology, there is a need to identify key molecular markers that could help define the pathogenic potential of this bacterium. We think a model system should be implemented that efficiently evaluates the expression of putative bacterial markers by using validated, stable, and highly specific housekeeping genes to properly select target genes, which could lead to identifying those responsible for infection and disease induction in naturally infected fish. Here, we selected a set of validated reference or housekeeping genes for RT-qPCR expression analyses of P. salmonis under different growth and stress conditions, including an in vitro infection kinetic. After a thorough screening, we selected sdhA as the most reliable housekeeping gene able to represent stable and highly specific host reference genes for RT-qPCR-driven P. salmonis analysis.