Capabilities and Challenges of Examination of Gene Expression for Quality Assessment of Domestic Cat Embryos

Abstract

Contents Early embryos are characterized by an accurately controlled gene expression pattern that might be deregulated during in vitro culture (IVC). The expression pattern of the developmental genes may serve as markers for embryo quality. Here, we examined the temporal pattern of relative mRNA abundance of genes important for early embryonic development in embryos produced by different fertilization methods [in vitro fertilization (IVF) vs intracytoplasmic sperm cell injection (ICSI)] and sperm sources (fresh vs frozen–thawed) applying reverse transcriptase (RT) PCR. The temporal pattern of gene expression was found to be gene specific and similar in all four examined groups in a semi‐quantitative assay. In morulae, higher relative mRNA levels were found in embryos generated with fresh sperm, whereas in blastocysts, mRNA abundance tended to be higher in embryos produced with cryopreserved sperm cells. This indicates an influence of sperm cryopreservation on the temporal gene expression pattern in early cat embryos. We also examined relative mRNA abundances by real‐time quantitative RT‐PCR in blastocysts. In this context, blastocysts produced with fresh semen tended to have lower DNA methyltransferase 3A (DNMT3A) but higher gap junction protein alpha 1 (GJA1) and octamer‐binding transcription factor 4 (OCT4) mRNA levels compared with those derived with frozen–thawed semen. We conclude that assessing embryo quality by measuring gene expression pattern in early embryos is challenging because of a high variability between individual embryos.

Meiotic Status Does Not Affect the Vitrification Effectiveness of Domestic Cat Oocytes

“…Pope et al [ 25 ] were the first to confirm ICSI as a successful method for cat oocyte fertilization with the birth of a live kitten in 1998. Since then, many further studies have been reported [ 1 , 21 , 29 , 49 , 50 , 51 , 52 ] substantiating the applicability of this method for fertilization of fresh oocytes.…”

Fighting Like Cats and Dogs: Challenges in Domestic Carnivore Oocyte Development and Promises of Innovative Culture Systems

“…For embryos, once again, culture media were designed to resemble the environment where early embryonic development occurs. For cats, one-step [29,59,60] or multi-step [18,19,24,25,[61][62][63][64] IVC systems have been employed. While the former have the advantage of reducing embryo manipulation, while the latter offer the possibility to adapt the nutrient supply according to the developmental stage of the embryos.…”

The never‐ending search of an ideal culture system for domestic cat oocytes and embryos

“…Investigation on embryo gene expression could also contribute to understand the effects of the in vitro conditions and the specific embryo requirements during IVC. In the domestic cat, it has been proved that gene expression varies according to the embryo stages, and differs between in vitro and in vivo-derived embryos (Filliers et al, 2012), depending also on the culture medium (Hribal, Jewgenow, Braun, & Comizzoli, 2013) and on the spermatozoa status (fresh or cryopreserved; Hribal, Braun, Ringleb, & Jewgenow, 2012).…”