Investigation of Chromosome Aneuploidies in Early Porcine Embryos Using Comparative Genomic Hybridization

Abstract

Although numerical chromosome errors are known to be prevalent in early human embryos and are likely to be a considerable factor influencing the mortality of early embryos and implantation failure, in domestic animals data about the frequency and nature of errors is limited. The objectives of this study were to investigate the whole chromosome set of in vivo obtained early pig embryos, applying methods of whole genome amplification and comparative genomic hybridization (CGH) and to contribute to the comprehensive understanding of the topic. The embryos were collected from gilts 72 h after insemination. Further, they were lysed and underwent whole genome amplification by multiple displacement amplification. In a subsequent CGH, amplified DNA was compared to control DNA using different fluorescent labeling and hybridization to male pig mitoses. 11 (14.3%) of the 77 pig embryos examined were observed to be aneuploid. We found chromosome errors comprising loss/gain of one or a few chromosomes (10.4%) but also extensive chromosome imbalances (3.9%). Chromosomes 8, 11, 12, 13, 17, and X were most frequently involved in aneuploidies, when compared to chromosomes 2, 9, and 18, which were rarely involved in chromosome errors.

Aneuploidy Detection in Pigs Using Comparative Genomic Hybridization: From the Oocytes to Blastocysts

“…We have reported the frequency of aneuploidy in porcine oocytes and in in vivo early embryos (collected 3 days after insemination) to be 10.1% and 14.3%, respectively [7], [8]. In our present study we focused on in vivo obtained porcine blastocysts (collected 5.5 days after insemination).…”

“…Recently, we have utilized comparative genomic hybridization (CGH) coupled with whole genome amplification (WGA) in order to study porcine oocytes and early embryos [7], [8]. This protocol is routinely used in human pre-implantation genetic diagnosis and starts to replace well established FISH analysis for this purpose [9], [10].…”

“…Considering that CGH is not able to detect polyploidies, we extended our work and enumerated the incidence of polyploidy in in vivo porcine blastocysts using FISH. Obtaining information from porcine oocytes, early embryos [7], [8], and from the current study of porcine blastocysts using the novel WGA-CGH approach, we would like to detail to what extent is aneuploidy the cause of embryo mortality in animals, particularly in pigs.…”

Aneuploidy Detection and mtDNA Quantification in Bovine Embryos with Different Cleavage Onset Using a Next-Generation Sequencing-Based Protocol

“…In pigs, the frequency of aneuploidy in preimplantation embryos varies from 14.3 to 37.3% based on screening of all chromosomes by comparative genomic hybridization (CGH) [Hornak et al, 2009[Hornak et al, , 2015. In cattle, studies mainly focused on polyploidy and mixoploidy, revealing that mixoploidy occurs in 25-90% of bovine embryos [Viuff et al, 1999;Jakobsen et al, 2006;Garcia-Herreros et al, 2010].…”

Fluorescence in situ Hybridization Applied to Domestic Animal Cytogenetics

“…Results published so far have dealt with embryo sexing [Kawarasaki et al, 2000], or with the detection of aneuploidies [Zudova et al, 2003;Malekinejad et al, 2007]. Recently, aneuploidies in early pig embryos were investigated for the first time using Comparative Genomic Hybridization (CGH) [Hornak et al, 2009]. FISH has also been used to analyze the activation of ribosomal RNA genes [Bjerregaard et al, 2007] or the ability of hyaluronic-acid-binding sperm to increase the efficiency of intracytoplasmic sperm injection [Park et al, 2005].…”