ABSTRACT
Persistent organic pollutants (POPs) can induce epigenetic changes in the paternal germline. Here, we report that folic acid (FA) supplementation mitigates sperm miRNA profiles transgenerationally following in utero paternal exposure to POPs in a rat model. Pregnant founder dams were exposed to an environmentally relevant POPs mixture (or corn oil) ± FA supplementation and subsequent F1-F4 male descendants were not exposed to POPs and were fed the FA control diet. Sperm miRNA profiles of intergenerational (F1, F2) and transgenerational (F3, F4) lineages were investigated using miRNA deep sequencing. Across the F1-F4 generations, sperm miRNA profiles were less perturbed with POPs+FA compared to sperm from descendants of dams treated with POPs alone. POPs exposure consistently led to alteration of three sperm miRNAs across two generations, and similarly one sperm miRNA due to POPs+FA; which was in common with one POPs intergenerationally altered sperm miRNA. The sperm miRNAs that were affected by POPs alone are known to target genes involved in mammary gland and embryonic organ development in F1, sex differentiation and reproductive system development in F2 and cognition and brain development in F3. When the POPs treatment was combined with FA supplementation, however, these same miRNA-targeted gene pathways were perturbed to a lesser extend and only in F1 sperm. These findings suggest that FA partially mitigates the effect of POPs on paternally derived miRNA in a intergenerational manner.
ABSTRACT
Reducing dietary phosphorus (P) is a common approach to reduce effluent P outputs. The potential resulting P-deficiency is known to negatively impact fish bone condition and might result in vertebral deformities. To date, no large-scale study involving deep sequencing of the bone transcriptome has been conducted in salmonids and vertebral molecular changes remain poorly described. This study aims to provide the first comprehensive vertebral transcriptome for rainbow trout (Oncorhynchus mykiss) to allow functional and quantitative expression studies. Fish weighing 60.8±1.6g, were fed for 27weeks using two practical diets having 0.29% (deficient) and 0.45% (sufficient) available phosphorus (P), respectively. Deep sequencing was conducted using HiSeq2000 Illumina 100 paired-end technology from pooled P-deficient and P-sufficient fish and individuals displaying vertebral deformities. Over 140 million trimmed paired-end reads were assembled de novo with Trinity and resulted in 679,869 transcripts with a mean length of 542.5bp. From these sequences, 340,747 matched with referenced ESTs from rainbow trout. Furthermore, 141,909 and 117,564 sequences were functionally annotated against Nr and Uniprot databases, respectively. Interestingly, we observed putative homologue sequences for most of the key components involved in bone formation and turnover in mammals.
