Adipose Tissue Transcriptome Is Related to Pollutant Exposure in Polar Bear Mother-Cub Pairs from Svalbard, Norway.

Being at the food chain apex, polar bears () are highly contaminated with persistent organic pollutants (POPs). Females transfer POPs to their offspring through gestation and lactation; therefore, young cubs present higher POPs concentrations than their mothers. Recent studies suggest that POPs affect the lipid metabolism in female polar bears; however, the mechanisms and impact on their offspring remain unknown.

Intragenic sequences in the trophectoderm harbour the greatest proportion of methylation errors in day 17 bovine conceptuses generated using assisted reproductive technologies.

Background: Assisted reproductive technologies (ART) are widely used to treat fertility issues in humans and for the production of embryos in mammalian livestock. The use of these techniques, however, is not without consequence as they are often associated with inauspicious pre- and postnatal outcomes including premature birth, intrauterine growth restriction and increased incidence of epigenetic disorders in human and large offspring syndrome in cattle. Here, global DNA methylation profiles in the trophectoderm and embryonic discs of in vitro produced (IVP), superovulation-derived (SOV) and unstimulated, synchronised control day 17 bovine conceptuses (herein referred to as AI) were interrogated using the EmbryoGENE DNA Methylation Array (EDMA).

Genome-wide DNA methylation patterns of bovine blastocysts derived from in vivo embryos subjected to in vitro culture before, during or after embryonic genome activation.

Background: Aberrant DNA methylation patterns of genes required for development are common in in vitro produced embryos. In this regard, we previously identified altered DNA methylation patterns of in vivo developed blastocysts from embryos which spent different stages of development in vitro, indicating carryover effects of suboptimal culture conditions on epigenetic signatures of preimplantation embryos. However, epigenetic responses of in vivo originated embryos to suboptimal culture conditions are not fully understood.

Application of Carnobacterium maltaromaticum as a feed additive for weaned rabbits to improve meat microbial quality and safety.

This study addresses the improvement of meat microbial quality by enriching the diet of farm animals with a protective culture. Weaned Grimaud rabbits were divided into two experimental groups: a control and a diet supplemented with Micocin® (Carnobacterium maltaromaticum CB1; 8LogCFU/kg of feed). Overall, meat quality was not affected substantially by the treatment.

Responses of bovine early embryos to S-adenosyl methionine supplementation in culture.

Aim: There is a growing concern about the potential adverse effects of high dose folic acid (FA) supplementation before and during pregnancy. FA metabolism generates S-adenosyl methionine (SAM) which is an important cofactor of epigenetic programming. We sought to assess the impact of a large dose of SAM on early embryo development.

Breed-specific factors influence embryonic lipid composition: comparison between Jersey and Holstein.

Some embryos exhibit better survival potential to cryopreservation than others. The cause of such a phenotype is still unclear and may be due to cell damage during cryopreservation, resulting from overaccumulation and composition of lipids. In cattle embryos, in vitro culture conditions have been shown to impact the number of lipid droplets within blastomeres.

Cumulus Cell Transcripts Transit to the Bovine Oocyte in Preparation for Maturation.

So far, the characteristics of a good quality egg have been elusive, similar to the nature of the physiological, cellular, and molecular cues leading to its production both in vivo and in vitro. Current understanding highlights a strong and complex interdependence between the follicular cells and the gamete. Secreted factors induce cellular responses in the follicular cells, and direct exchange of small molecules from the cumulus cells to the oocyte through gap junctions controls meiotic arrest.

The human decapping scavenger enzyme DcpS modulates microRNA turnover.

The decapping scavenger enzyme DcpS is known for its role in hydrolyzing the cap structure following mRNA degradation. Recently, we discovered a new function in miRNA degradation activation for the ortholog of DcpS in C. elegans.

Genome-Wide DNA Methylation Patterns of Bovine Blastocysts Developed In Vivo from Embryos Completed Different Stages of Development In Vitro.

Early embryonic loss and altered gene expression in in vitro produced blastocysts are believed to be partly caused by aberrant DNA methylation. However, specific embryonic stage which is sensitive to in vitro culture conditions to alter the DNA methylation profile of the resulting blastocysts remained unclear. Therefore, the aim of this study was to investigate the stage specific effect of in vitro culture environment on the DNA methylation response of the resulting blastocysts.

Genetic influence on the reduction in bovine embryo lipid content by l-carnitine.

The decreased rate of pregnancy obtained in cattle using frozen in vitro embryos compared with in vivo embryos has been associated with over-accumulation of intracellular lipid, which causes cell damage during cryopreservation. It is believed that the higher lipid content of blastomeres of bovine embryos produced in vitro results in darker-coloured cytoplasm, which could be a consequence of impaired mitochondrial function. In this study, l-carnitine was used as a treatment to reduce embryonic lipid content by increasing metabolism in cultured bovine embryos.

Exploring the function of long non-coding RNA in the development of bovine early embryos.

Now recognised as part of the cellular transcriptome, the function of long non-coding (lnc) RNA remains unclear. Previously, we found that some lncRNA molecules in bovine embryos are highly responsive to culture conditions. In view of a recent demonstration that lncRNA may play a role in regulating important functions, such as maintenance of pluripotency, modification of epigenetic marks and activation of transcription, we sought evidence of its involvement in embryogenesis.

Impact of whole-genome amplification on the reliability of pre-transfer cattle embryo breeding value estimates.

Background: Genome-wide profiling of single-nucleotide polymorphisms is receiving increasing attention as a method of pre-implantation genetic diagnosis in humans and of commercial genotyping of pre-transfer embryos in cattle. However, the very small quantity of genomic DNA in biopsy material from early embryos poses daunting technical challenges. A reliable whole-genome amplification (WGA) procedure would greatly facilitate the procedure.

Improvement of bovine in vitro embryo production by vitamin K₂ supplementation.

Mitochondria play an important role during early development in mammalian embryos. It has been shown that properly controlled follicular preparation increases the likelihood of in-vitro-produced bovine embryos reaching the blastocyst stage and that competent embryos exhibit heightened expression of genes associated with mitochondrial function. We hypothesized that apparently incompetent embryos could be rescued by restoring mitochondrial function.

Sexual dimorphism in developmental programming of the bovine preimplantation embryo caused by colony-stimulating factor 2.

Physiology of the adult can be modified by alterations in prenatal development driven by the maternal environment. Developmental programming, which can be established before the embryo implants in the uterus, can affect females differently than males. The mechanism by which sex-specific developmental programming is established is not known.

Combined methylation mapping of 5mC and 5hmC during early embryonic stages in bovine.

Background: It was recently established that changes in methylation during development are dynamic and involve both methylation and demethylation processes. Yet, which genomic sites are changing and what are the contributions of methylation (5mC) and hydroxymethylation (5hmC) to this epigenetic remodeling is still unknown. When studying early development, options for methylation profiling are limited by the unavailability of sufficient DNA material from these scarce samples and limitations are aggravated in non-model species due to the lack of technological platforms.

Contribution of oocyte source and culture conditions to phenotypic and transcriptomic variation in commercially produced bovine blastocysts.

Bovine embryo production is practiced worldwide for commercial purposes. A major concern of embryo suppliers is the impact of in vitro production systems on embryo quality. In the present study, we compared Buffalo Rat Liver cell coculture with semidefined, medium-based culture, oocytes recovered postmortem with those obtained from live animals, and in vitro with in vivo embryo development.

The microRNA pathway controls germ cell proliferation and differentiation in C. elegans.

The discovery of the miRNA pathway revealed a new layer of molecular control of biological processes. To uncover new functions of this gene regulatory pathway, we undertook the characterization of the two miRNA-specific Argonaute proteins in Caenorhabditis elegans, ALG-1 and ALG-2. We first observed that the loss-of-function of alg-1 and alg-2 genes resulted in reduced progeny number.

Combining resources to obtain a comprehensive survey of the bovine embryo transcriptome through deep sequencing and microarrays.

While most assisted reproductive technologies (ART) are considered routine for the reproduction of species of economical importance, such as the bovine, the impact of these manipulations on the developing embryo remains largely unknown. In an effort to obtain a comprehensive survey of the bovine embryo transcriptome and how it is modified by ART, resources were combined to design an embryo-specific microarray. Close to one million high-quality reads were produced from subtracted bovine embryo libraries using Roche 454 Titanium deep sequencing technology, which enabled the creation of an augmented bovine genome catalog.

Comprehensive cross production system assessment of the impact of in vitro microenvironment on the expression of messengers and long non-coding RNAs in the bovine blastocyst.

In vitro production (IVP) of cattle embryos over the past two decades has revealed several negative impacts that have been attributed to the artificial microenvironment. Studies on embryos produced in vitro clearly point to aberrant gene expression levels. So far, the causal association between phenotype and measured gene expression has not led to substantial improvement of IVP systems.

Microfluidic device for rapid (<15 min) automated microarray hybridization.

Background: Current hybridization protocols on microarrays are slow and need skilled personnel. Microfluidics is an emerging science that enables the processing of minute volumes of liquids to perform chemical, biochemical, or enzymatic analyzes. The merging of microfluidics and microarray technologies constitutes an elegant solution that will automate and speed up microarray hybridization.

Quantification of cyclin B1 and p34(cdc2) in bovine cumulus-oocyte complexes and expression mapping of genes involved in the cell cycle by complementary DNA macroarrays.

Although high amounts of cyclin B1 mRNA are present in bovine oocytes arrested at the germinal vesicle (GV) stage, the protein is not detectable. Furthermore, there is a depletion of the stored cyclin B1 mRNA in the oocyte as follicular growth progresses. To assess the effect of follicular growth on the accumulation of M-phase promoting factor (MPF) components, mRNA and protein levels of cyclin B1 and p34(cdc2) were measured in GV oocytes collected from diverse follicle size groups (<2 mm, 3-5 mm, and >6 mm).