Overexpression of Let-7a mitigates diploidization in mouse androgenetic haploid embryonic stem cells.

Mouse androgenetic haploid embryonic stem cells (mAG-haESCs) can be utilized to uncover gene functions, especially those of genes with recessive effects, and to produce semicloned mice when injected into mature oocytes. However, mouse haploid cells undergo rapid diploidization during long-term culture and subsequently lose the advantages of haploidy, and the factors that drive diploidization are poorly understood. In this study, we compared the small RNAs (sRNAs) of mAG-haESCs, normal embryonic stem cells (ESCs), and mouse round spermatids by high-throughput sequencing and identified distinct sRNA profiles.

Appropriate glycemic management protects the germline but not the uterine environment in hyperglycemia.

Emerging evidence indicates that parental diseases can impact the health of subsequent generations through epigenetic inheritance. Recently, it was shown that maternal diabetes alters the metaphase II oocyte transcriptome, causing metabolic dysfunction in offspring. However, type 1 diabetes (T1D) mouse models frequently utilized in previous studies may be subject to several confounding factors due to severe hyperglycemia.

Transcriptome profiles and chromatin states in mouse androgenetic haploid embryonic stem cells.

Haploid embryonic stem cells (haESCs) are derived from the inner cell mass of the haploid blastocyst, containing only one set of chromosomes. Extensive and accurate chromatin remodelling occurs during haESC derivation, but the intrinsic transcriptome profiles and chromatin structure of haESCs have not been fully explored. We profiled the transcriptomes, nucleosome positioning, and key histone modifications of four mouse haESC lines, and compared these profiles with those of other closely-related stem cell lines, MII oocytes, round spermatids, sperm, and mouse embryonic fibroblasts.

Distinct H3K9me3 and DNA methylation modifications during mouse spermatogenesis.

DNA methylation and histone modifications critically regulate the expression of many genes and repeat regions during spermatogenesis. However, the molecular details of these processes in male germ cells remain to be addressed. Here, using isolated murine sperm cells, ultra-low-input native ChIP-Seq (ULI-NChIP-Seq), and whole genome bisulfite sequencing (WGBS), we investigated genome-wide DNA methylation patterns and histone 3 Lys-9 trimethylation (H3K9me3) modifications during mouse spermatogenesis.

Mammalian haploid stem cells: establishment, engineering and applications.

Haploid embryonic stem cells (haESCs) contain only one set of genomes inherited from the sperm or egg and are termed AG- or PG-haESCs, respectively. Mammalian haESCs show genome-wide hypomethylation and dysregulated imprinting, whereas they can sustain genome integrity during derivation and long-term propagation. In addition, haESCs exhibit similar pluripotency to traditional diploid ESCs but are unique because they function as gametes and have been used to produce semi-cloned animals.

Reduced Self-Diploidization and Improved Survival of Semi-cloned Mice Produced from Androgenetic Haploid Embryonic Stem Cells through Overexpression of Dnmt3b.

Androgenetic haploid embryonic stem cells (AG-haESCs) hold great promise for exploring gene functions and generating gene-edited semi-cloned (SC) mice. However, the high incidence of self-diploidization and low efficiency of SC mouse production are major obstacles preventing widespread use of these cells. Moreover, although SC mice generation could be greatly improved by knocking out the differentially methylated regions of two imprinted genes, 50% of the SC mice did not survive into adulthood.

Allelic reprogramming of the histone modification H3K4me3 in early mammalian development.

Histone modifications are fundamental epigenetic regulators that control many crucial cellular processes. However, whether these marks can be passed on from mammalian gametes to the next generation is a long-standing question that remains unanswered. Here, by developing a highly sensitive approach, STAR ChIP-seq, we provide a panoramic view of the landscape of H3K4me3, a histone hallmark for transcription initiation, from developing gametes to post-implantation embryos.

Xist repression shows time-dependent effects on the reprogramming of female somatic cells to induced pluripotent stem cells.

Although the reactivation of silenced X chromosomes has been observed as part of the process of reprogramming female somatic cells into induced pluripotent stem cells (iPSCs), it remains unknown whether repression of the X-inactive specific transcript (Xist) can greatly enhance female iPSC induction similar to that observed in somatic cell nuclear transfer studies. In this study, we discovered that the repression of Xist plays opposite roles in the early and late phases of female iPSCs induction. Our results demonstrate that the downregulation of Xist by an isopropyl β-d-1-thiogalactopyranoside (IPTG)-inducible short hairpin RNA (shRNA) system can greatly impair the mesenchymal-to-epithelial transition (MET) in the early phase of iPSC induction but can significantly promote the transition of pre-iPSCs to iPSCs in the late phase.

A pre-breeding screening program for transgenic boars based on fluorescence in situ hybridization assay.

For efficient transgenic herd expansion, only the transgenic animals that possess the ability to transmit transgene into next generation are considered for breeding. However, for transgenic pig, practically lacking a pre-breeding screening program, time, labor and money is always wasted to maintain non-transgenic pigs, low or null transgenic transmission pigs and the related fruitless gestations. Developing a pre-breeding screening program would make the transgenic herd expansion more economical and efficient.

Asymmetric reprogramming capacity of parental pronuclei in mouse zygotes.

It has been demonstrated that reprogramming factors are sequestered in the pronuclei of zygotes after fertilization, because zygotes enucleated at the M phase instead of interphase of the first mitosis can support the development of cloned embryos. However, the contribution of the parental pronucleus derived from either the sperm or the oocyte in reprogramming remains elusive. Here, we demonstrate that the parental pronuclei have asymmetric reprogramming capacities and that the reprogramming factors reside predominantly in the male pronucleus.

Generation and developmental characteristics of porcine tetraploid embryos and tetraploid/diploid chimeric embryos.

The aim of this study was to optimize electrofusion conditions for generating porcine tetraploid (4n) embryos and produce tetraploid/diploid (4n/2n) chimeric embryos. Different electric field intensities were tested and 2 direct current (DC) pulses of 0.9 kV/cm for 30 μs was selected as the optimum condition for electrofusion of 2-cell embryos to produce 4n embryos.

[Cloning and gene expression of sall4b gene in pig].

Sall4, a member of sall4 gene family, plays important roles in embryo development; organogenesis as well as pluripotency maintenance and re-establishment. There are two isoforms of Sall4, Sall4A and Sall4B. The sequence of porcine sall4 gene is still not reported.