The Pig Lhx8 Gene:cDNA Cloning,Bioinformatic Analysis and Expression Level in Tissues and Preimplantation Embryos

Evidence has shown in mouse that Lhx8 is a critical factor for maintenance and differentiation of the oocyte during early oogenesis. In the current paper, attempts were made to clone and characterize a gene encoding Lhx8 from pig. Rapid amplification of cDNA ends （RACE） gave rise to a full-length of Lhx8 which contained 1 681 bp nucleotides, with a complete open reading frame of 885 bp, encoding a 295 amino acid polypeptide. Homology search and sequence multialignment demonstrated that the deduced pig Lhx8 protein sequence shared a high identity with Lhx8 from other mammals, including several highly conservative motifs and amino acids. The phylogenetic tree of the LIM superfamily proteins has been constructed to reveal the evolutionary relationship of various species. RT-PCR analysis showed that the Lhx8 gene was expressed in gonad and immunity tissues. In preimplantation embryos, Lhx8 mRNA expression profiling using realtime PCR revealed that its mRNA levels were highest in 4-cell stage embryos and gradually decreased until the blastocyst stage.

Review:Mitochondrial functions on oocytes and preimplantation embryos

Oocyte quality has long been considered as a main limiting factor for in vitro fertilization （IVF）. In the past decade, extensive observations demonstrated that the mitochondrion plays a vital role in the oocyte cytoplasm, for it can provide adenosine triphosphate （ATP） for fertilization and preimplantation embryo development and also act as stores of intracellular calcium and proapoptotic factors. During the oocyte maturation, mitochondria are characterized by distinct changes of their distribution pattern from being homogeneous to heterogeneous, which is correlated with the cumulus apoptosis. Oocyte quality decreases with the increasing maternal age. Recent studies have shown that low quality oocytes have some age-related dysfunctions, which include the decrease in mitochondrial membrane potential, increase of mitochondrial DNA （mtDNA） damages, chromosomal aneuploidies, the incidence of apoptosis, and changes in mitochoncLrial gene expression. All these dysfunctions may cause a high level of de- velopmental retardation and arrest of preimplantation embryos. It has been suggested that these mitochondrial changes may arise from excessive reactive oxygen species （ROS） that is closely associated with the oxidative energy production or calcium overload, which may trigger permeability transition pore opening and subsequent apoptosis. Therefore, mitochondria can be seen as signs for oocyte quality evaluation, and it is possible that the oocyte quality can be improved by enhancing the physical function of mitochondria. Here we reviewed recent advances in mitochondrial functions on oocytes.

Differential regulation of H3S10 phosphorylation, mitosis progression and cell fate by Aurora Kinase B and C in mouse preimplantation embryos

Coordination of cell division and cell fate is crucial for the successful development of mammalian early embryos. Aurora kinases are evolutionarily conserved serine/threonine kinases and key regulators of mitosis. Aurora kinase B （AurkB） is ubiquitously expressed while Aurora kinase C （AurkC） is specifically expressed in gametes and preimplantation embryos. We found that increasing AurkC level in one blastomere of the 2-cell embryo accelerated cell division and decreasing AurkC level slowed down mitosis. Changing AurkB level had the opposite effect. The kinase domains of AurkB and AurkC were responsible for their different ability to phosphorylate Histone H3 Serine 10 （H3S10P） and regulate metaphase timing. Using an Oct4-photoactivat- able GFP fusion protein （Oct4-paGFP） and fluorescence decay after photoactivation assay, we found that AurkB overexpression reduced Oct4 retention in the nucleus. Finally, we show that blastomeres with higher AurkC level elevated pluripotency gene expression, which were inclined to enter the inner cell mass lineage and subsequently contributed to the embryo proper. Collectively, our results are the first demonstration that the activity of mitotic kinases can influence cell fate decisions in mammalian preimplantation embryos and have important implications to assisted reproduction.

The dynamics of 3D chromatin architecture in mammalian preimplantation embryos

Subject Code:C06Research groups of Prof.Xie Wei(颉伟)at Tsinghua University published a research paper in Nature(2017,547:232—235)on July 13th,entitled“Allelic reprogramming of 3Dchromatin architecture during early mammalian development”with the support by the National Natural Science Foundation of China.

The Study on the Gene Expression of Preimplantation IVF Bovine Embryos

The cattle different stage embryos obtained from in vitro was studied using the technology of single preimplantation embryo mRNA different display:single 8-cell and blastocyst stage embryos were studied using technology of mRNA different display and one different fragment was found. The result suggested that this fragment displayed high homology (99%) to cattle mRNA for ribosomal protein L31. Then to detect the expression of RPL31mRNA in 8 cell and blastocyst stage embryos by real-time quantitative PCR,the result showed the relative amount of 8 cells was 3.2 times of blastocyst's.

Insulin-like Growth Factor-I (IGF-I) in Reproduction System of Female Bovine

Insulin-like growth factor-I （IGF-I） plays a key role in female reproduction, because it has the effect of anti-apoptosis improving cell proliferation, transformation and differentiation. This paper reviewed the effects of IGF-I on ovary, follicle growth, acquisition of oocyte competence and preimplantation embryo viability, and then summarized different points about IGF-1 for reproduction system

Endocannabinoid Signaling in Modulating Periimplantation Events

Cannabinoids have long been suspected associating with abnormal fetal growth and outcome. However, the molecular mechanisms in which they are involved had long been obscure for several decades. Only recently, after the identification of two types of cannabinoid receptors （CB1-R and CB2-R） and the following discoveries of their corresponding endogenous ligands, the mystery behind those seemingly facts began gradually unveiled. Through a series of landmark research, it is now indicated that the endocannabinoid signaling via the ligand-receptor interaction plays an important role in modulating early development of preimplantation embryo and synchronizing embryo development with uterine receptivity for implantation. Current data suggest that the physiological functions their metabolic pathways are potentially very of endocannabinoid signaling as well as exited areas to be explored further. This review will first introduce the reproductive functions of endocannabinoid signaling from epidemiological and molecular background, then focus on its reciprocal interactions between the embryo and maternal tissues, as well as related metabolic aspects in regards to implantation. It is hoped that further investigation of this physiologically fundamental signaling will generate more exciting information elucidating the complexity of implantation thus lead to a better control of human reproduction.

Effect of the P1 Medium and the ECM Medium on Embryo Quality in IVF

Objective To investigate the effect of the glucose-free preimplantation stage one （P1） medium and the ECM medium on embryo development quality in IVF. Methods The patients with ≥4 zygotes of 2PN were studied. A total of 201 retrieval cycles were included in a prospective randomized study. Each patient was herself control. Half of zygotes of 2PN were transferred into ECM medium （group A） and half into P1 medium （group B）for further culture. Embryo development was evaluated on the day of embryo transfer. The efficacy of ECM was compared with P1 as culture medium for the development of preimplantation embryos. Results No statistically significant differences were noted between the two groups regarding embryo-cleavage rate （97.13% vs 97.55%） and rate of normal-cleaving embryos （58.29% and 58.37%）. The rate of top-quality embryos was statistically higher in group A than in group B （27.59% vs 19.75%, P〈O.05）. Embryo quality, as assessed by morphological parameters （the amount of detached anuclear fragments 〉30%）, was better in group A than in group B （19.86% vs 21.75%）, however, there was no statistically significance. Both the rate of good-quality embryos （47.95% vs 46.17%） and available embryos （63.22% vs 61.19%） were higher in group A than in group B, but there was also no statistically significance. Conclusion The ECM medium may be associated with a better embryo quality compared with the P1 medium.

Omics Views of Mechanisms for Cell Fate Determination in Early Mammalian Development

During mammalian preimplantation development,a totipotent zygote undergoes several cell cleavages and two rounds of cell fate determination,ultimately forming a mature blastocyst.Along with compaction,the establishment of apicobasal cell polarity breaks the symmetry of an embryo and guides subsequent cell fate choice.Although the lineage segregation of the inner cell mass(ICM)and trophectoderm(TE)is the first symbol of cell differentiation,several molecules have been shown to bias the early cell fate through their inter-cellular variations at much earlier stages,including the 2-and 4-cell stages.The underlying mechanisms of early cell fate determination have long been an important research topic.In this review,we summarize the molecular events that occur during early embryogenesis,as well as the current understanding of their regulatory roles in cell fate decisions.Moreover,as powerful tools for early embryogenesis research,single-cell omics techniques have been applied to both mouse and human preimplantation embryos and have contributed to the discovery of cell fate regulators.Here,we summarize their applications in the research of preimplantation embryos,and provide new insights and perspectives on cell fate regulation.

Molecules and mechanisms controlling the active DNA demethylation of the mammalian zygotic genome

The active DNA demethylation in early embryos is essential for subsequent development. Although the zygotic genome is globally demethylated, the DNA methylation of imprinted regions, part of repeat sequences and some gamete-specific regions are maintained. Recent evidence has shown that multiple proteins and biological pathways participate in the regulation of active DNA demethylation, such as TET proteins, DNA repair pathways and DNA methyltransferases. Here we review the recent understanding regarding proteins associated with active DNA demethylation and the regulatory networks controlling the active DNA demethylation in early embryos.

MR-seq:measuring a single cell's transcriptome repeatedly by RNA-seq

We described a novel single-cell RNA-seq technique called MR-seq （measure a single-cell transcriptome repeatedly）, which permits statistically assessing the technical variation and identifying the differentially expressed genes between just two single ceils by measuring each single cell twice. We demonstrated that MR-seq gave sensitivity and reproducibility similar to the standard single-cell RNA-seq and increased the positive predicate value, Application of MR-seq to early mouse embryos identified hundreds of candidate intra-embryonic heterogeneous genes among mouse 2-, 4- and 8-cell stage embryos. MR-seq should be useful for detecting differentially exnre^ed ~enes ~rnnn~ ~ ~m^ll nHmhpr nf c^ll~