Analysis of imprinted IGF2/H19 gene methylation and expression in normal fertilized and parthenogenetic embryonic stem cells of pigs

Pluripotent pig embryonic stem cell lines originating from in vitro-fertilized and parthenogenetic embryos

Here, we report in vivo developmental competent pig embryonic stem cells (ESCs) originating from in vitro-fertilized and parthenogenetic embryos cultured in chemically defined culture media. The pig ESC lines expressed pluripotency markers and were capable of forming teratomas following subcutaneous injection into nude mice. These cell lines would be a useful resource for comparative developmental biology and agricultural biotechnology.

[A survey of pubertal development in children born with assisted reproductive technology]

OBJECTIVE

To investigate the status of pubertal development in children born with assisted reproductive technology (ART).

METHODS

A retrospective analysis was performed on the pubertal development data of children born with ART in Peking University Third Hospital from 1994 to 2003 (ART group). The data in the cross-sectional study "Reports on the Physical Fitness and Health Research of Chinese School Students in 2010" were used as a control. The age at menarche and the age at spermarche were compared between the two groups. The status of pubertal development in the overweight and obese children in the ART group was evaluated to investigate the correlation between pubertal development and body mass index (BMI).

RESULTS

A total of 200 children born with ART were enrolled in this study, and 72 of them (41 males and 31 females) completed the survey (response rate=36.0%). In the ART group, the mean age at spermarche and the mean age at menarche were 13.9 years (95%CI: 13.7-14.3 years) and 12.2 years (95%CI: 11.8-12.6 years), respectively. There were no significant differences in the age at spermarche and the age at menarche between the ART and control groups (P>0.05). In the ART group, there were no significant differences in the age at spermarche and the age at menarche between the overweight and obese children and the normal weight children (P>0.05). There were also no significant differences in overweight rate and obesity rate between the children in the ART group and the adolescents in Beijing (P>0.05). In the ART group, there was no significant correlation between the age at spermarche or menarche and BMI (P>0.05).

CONCLUSIONS

No delayed or precocious puberty is observed in children born with ART. This is consistent with the normal control data. And there is no significant correlation between pubertal development and BMI in children born with ART.

Non-coding RNAs: emerging regulatory factors in the derivation and differentiation of mammalian parthenogenetic embryonic stem cells

Parthenogenetic embryonic stem cells (PESCs) are ESCs derived from early parthenogenetic embryos. Haploid PESCs, containing haploid DNA, originate from a single sperm or occyte, while, diploid PESCs originate from two fused occytes. Most PESC lines used so far are diploid. PESCs exhibit representative pluripotent stem cell features, such as the capacity for self-renewal and the pariticular molecular signatures. Whereas, PESCs display distinctive properties, such as differential regulation of X-chromosome inactivation (XCI) and divergent monitor of genes involved in multiple biological processes. PESCs are considered promising in the regeneration medicine and developmental biology. Non-coding RNAs (ncRNAs), especially miRNAs and lncRNAs, have garnered increasing attention over the past 2 decades. They are now known to be involved in almost all cellular processes due to their full-range regulation of gene expression. Numerous studies have indicated that embryonic stem cells (ESCs) displayed distinct signatures of ncRNA genes, which play key roles in the pluripotency and self renewal of ESCs. However, the expression pattern of ncRNAs in PESCs and their roles in the derivation and differentiation of PESCs were rarely reported. In this paper, we reviewed recent research on the derivation and differentiation of PESCs and describe the emerging role of ncRNAs in these processes.

The Importance of Endophenotypes to Evaluate the Relationship between Genotype and External Phenotype

With the exception of a few Mendelian traits, almost all phenotypes (traits) in livestock science are quantitative or complex traits regulated by the expression of many genes. For most of the complex traits, differential expression of genes, rather than genomic variation in the gene coding sequences, is associated with the genotype of a trait. The expression profiles of the animal's transcriptome, proteome and metabolome represent endophenotypes that influence/regulate the externally-observed phenotype. These expression profiles are generated by interactions between the animal's genome and its environment that range from the cellular, up to the husbandry environment. Thus, understanding complex traits requires knowledge about not only genomic variation, but also environmental effects that affect genome expression. Gene products act together in physiological pathways and interaction networks (of pathways). Due to the lack of annotation of the functional genome and ontologies of genes, our knowledge about the various biological systems that contribute to the development of external phenotypes is sparse. Furthermore, interaction with the animals' microbiome, especially in the gut, greatly influences the external phenotype. We conclude that a detailed understanding of complex traits requires not only understanding of variation in the genome, but also its expression at all functional levels.

Faithful expression of imprinted genes in donor cells of SCNT cloned pigs

To understand if the genomic imprinting status of the donor cells is altered during the process of SCNT (somatic cell nuclear transfer), cloned pigs were produced by SCNT using PEF (porcine embryonic fibroblast) and P-PEF (parthenogenetic-PEF) cells as donors. Then, the gene expression and methylation patterns of H19, IGF2, NNAT and MEST were compared between PEF vs. C-PEF (cloned-PEF), P-PEF vs. CP-PEF (cloned-P-PEF), respectively. Taken together, the results revealed that there was no significant difference in the expression of imprinted genes and conserved genomic imprints between the donor and cloned cells.