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The majority of embryos created through in vitro fertilization (IVF) do not implant. It seems plausible that rates of implantation would improve if we had a better understanding of molecular factors affecting embryo competence. Currently, the process of selecting an embryo for uterine transfer uses an ad hoc combination of morphological criteria, the kinetics of development, and genetic testing for aneuploidy. However, no single criterion can ensure selection of a viable embryo. In contrast, RNA-sequencing (RNA-seq) of embryos could yield high-dimensional data, which may provide additional insight and illuminate the discrepancies among current selection criteria. Recent advances enabling the production of RNA-seq libraries from single cells have facilitated the application of this technique to the study of transcriptional events in early human development. However, these studies have not assessed the quality of their constituent embryos relative to commonly used embryological criteria. Here, we perform proof-of-principle advancement to embryo selection procedures by generating RNA-seq libraries from a trophectoderm biopsy as well as the remaining whole embryo. We combine state-of-the-art embryological methods with low-input RNA-seq to develop the first transcriptome-wide approach for assessing embryo competence. Specifically, we show the capacity of RNA-seq as a promising tool in preimplantation screening by showing that biopsies of an embryo can capture valuable information available in the whole embryo from which they are derived. Furthermore, we show that this technique can be used to generate a RNA-based digital karyotype and to identify candidate competence-associated genes. Together, these data establish the foundation for a future RNA-based diagnostic in IVF.

Chromosomal abnormalities arising after fertilization, are observed at a relatively high rate at the cleavage stage. To evaluate the aneuploidy and mosaicism, microarray comparative genomic hybridization (CGH) of trophectoderm cells from blastocysts has been considered in preimplantation screening. However, 1% or less of live births are children with chromosomal abnormalities. In this paper, cytogenetic features of patients with chromosomal abnormalities and methods for detecting the disorders are described. Consideration of the utilities and limitations of cytogenetic techniques is essential in the clinical setting.

We report enrichment in the efficiency of generating mice transgenic for expression of a human protein in their milk using GFP-mediated preimplantation screening. The transgene array consisted of a functional gene (human alpha-1 antitrypsin under the control of the ovine BLG promoter) linked 5' to a reporter gene (GFP under the control of the murine Oct-4 promoter). GFP expression was detected in blastocysts by fluorescence microscopy and green and nongreen embryos were transferred to recipients in separate groups. In the first experiment, of seven pups that resulted from the transfer of blastocysts expressing GFP, five (71%) were transgenic. The experiment was repeated and of 12 pups that resulted from transfer of GFP-expressing blastocysts, 11 were transgenic (92%). The presence of the reporter cassette used for preimplantation screening did not affect the expression level of alpha-1-antitrypsin in the milk of the transgenic mice. In addition, in a related experiment wherein the GFP reporter gene was co-injected with a second mammary-specific transgene, pINC, no effect on transgene expression was observed. For mice transgenic for the mammary-specific gene alone, expression levels for four different lines were 192, 197, 382, and 415 microg/mL. For mice transgenic for both the mammary-specific transgene and the Oct4-GFP reporter cassette, expression levels for seven different lines were 282, 321, 468, 497, 499, 516, and 806 microg/mL.

The genetic manipulation of donor cells before nuclear transfer (NT) enables prior selection for transgene integration. However, selection for genetically modified cells using antibiotic drugs often results in mixed populations, resulting in a mixture of transgenic and nontransgenic donor cells for NT. In this study, we attempted to develop efficient strategies for the generation of human bile salt-stimulated lipase (BSSL) transgenic cows. Preimplantation screening by either biopsy or green fluorescent protein (GFP) expression was used to detect NT-derived BSSL transgenic embryos to ensure that the calf born would be transgenic. We compared the development rates of NT-derived embryos from G418- and GFP-selected donor cells. There were no significant differences (P , 0.001) in cleavage rate (67.2% vs. 60.0%) and blastocyst formation rate (44.9% vs. 41.2%). We also compared the pregnancy rates of the G418/biopsy and GFP preimplantation screened NT-derived blastocysts. The Day 40 pregnancy rate of the G418/biopsy group (40%) was lower than that of the GFP group (57%), but the calf birth rate of the G418/ biopsy group (40%) was higher than that of the GFP group (21%). Healthy BSSL transgenic calves were born after both screening processes. This is the first report of biopsy-screened cloned transgenic animals. The results suggest that both selection methods are useful for detecting transgenic NT embryos without negatively affecting their development into viable transgenic offspring. assisted reproductive technology, early development, embryo, pregnancy