Insights into epigenetic patterns in mammalian early embryos

Mammalian fertilization begins with the fusion of two specialized gametes, followed by major epigenetic remodeling leading to the formation of a totipotent embryo. During the development of the pre-implantation embryo, precise reprogramming progress is a prerequisite for avoiding developmental defects or embryonic lethality, but the underlying molecular mechanisms remain elusive. For the past few years, unprecedented breakthroughs have been made in mapping the regulatory network of dynamic epigenomes during mammalian early embryo development, taking advantage of multiple advances and innovations in low-input genome-wide chromatin analysis technologies. The aim of this review is to highlight the most recent progress in understanding the mechanisms of epigenetic remodeling during early embryogenesis in mammals, including DNA methylation, histone modifications, chromatin accessibility and 3D chromatin organization.

The inhibitory effects of Brusatol on mouse early embryonic development and its molecular mechanism / 医学研究生学报

Objective Up to now, the role of Brucea in early embryonic development of mice and its mechanism is still unclear.This paper aims to explore the role of Brusatol in mouse early embryonic development and its possible mechanism.Methods 100 kunming rats of clean grade(80 female rats and 20 male rats) were divided into 6 group: negative control group(no DMSO)、blank control group(culture in fresh CM with equal DMSO)、20nmol/L brusatol treated group、50nmol/L brusatol treated group、100nmol/L brusatol treated group、200nmol/L brusatol treated group(A solution of Brusatol was diluted in CM to concentrations of 20, 50, 100 or 200nmol/L.).Each group used an average of 20 embryos each time, repeated 4 times.Fertilized eggs after cultured 24h, 48h,72h, 96h were respectively 2-cell stage, 4-cell stage,morula and blastocyst stage..The embryo development rate was observed in the culture medium and the optimal concentration was selected, the embryos were collected to analysis the subcellular localization of the Nrf2 by immunofluorescence.The mRNA expression level of Cyclin B, CDK1 and the protein expression of Nrf2 were detected by Q-PCR and western blot respectively.Results In 4-cell stage, the embryo development rates of 20、50、100nmol/L brusatol treated groups[(75.0±2.8)%、(30.4±7.5)%、(4.2±5.9)%] significantly reduced compared with the negative control group[(93.0±2.8)%]、blank control group[(90.9±1.2)%].In morula stage, compared with blastocyst rates of negative control group、blank control group [(83.5±2.1)%、(84.2±1.2)%], 50nmol/L brusatol treated group[(19.3±13.1)%] decreased obviously [(79.00±0.06)% vs 100%, P<0.05].In the cellular immunofluorescence assay, the expression of Nrf2 protein in 50nmol/L brusatol treated group was lower than blank control group(P<0.05).We further found that 50nmol/L brusatol treated group decreased more mRNA levels of Cyclin B[(59.5±9.2)%] and CDK1[(56.0±1.4)%] than blank control group(100%) in G2/M phase(P<0.05).Conclusion In this study, Brusatol mainly affects the cell cycle transformation from G2 to M phase dependent on Cyclin B-CDK1, further inhibiting the development of the embryo through down-regulating Nrf2.

The role of ripply1 in zebrafish dorsal-ventral development / 中国实验动物学报

Objective To explore the role of ripply1 in zebrafish dorsal-ventral development .Methods Using ze-brafish whole-mount in situ hybridization to examine the ripply1 expression pattern in early embryo development .To analyse the expression pattern changes of dorsal-ventral marker genes at shield stage and the morphological changes at 24 hpf (hours post-fertilization) after overexpression of ripply1 by injecting synthetic mRNA at 1-cell stage.Using Tol2 transposon technology to obtain a ripply1 promoter driven GFP transgenic fish and to identify promoter region that recapitulates endoge -nous ripply1 expression pattern .Results The in situ hybridization results revealed that ripply1 specifically expresses in the future dorsal region at shield stage .Overexpression of ripply1 caused an enhanced expression of dorsal marker genes and a reduction of ventral marker genes .Embryos overexpressing ripply1 also showed severely dorsalized phenotype , with enlarged head, reduced ventral yolk extension , and shortened posterior trunk and tail regions , and the formation of a secondary trunk axis.Transgenic fish revealed the maternal expression of ripply1 and suggested that a 1.2 kb promoter-driven GFP is able to recapitulate the endogenous gene expression pattern .Conclusion ripply1 may participate in the early development of dor-sal-ventral axis in zebrafish embryo .

Study on the role of interleukin 6, matrix metalloproteinases 2 in the first trimester / 实用医学杂志

Objective To explore the relationship between the Interleukin 6 , matrix metalloproteinases 2 and early embryo arrest. Methods Real time-PCR was used to measure the mRNA expression of IL-6 and MMP-2 and immunohistochemistry (IHC, SP method)was used to measure the location and expression of the two different kinds of protein in villus. ELISA was used to measure the level of IL-6 in serum. Results Real-time PCR and IHC showed that the expression levels of IL-6 was significantly lower in experimental group than in control group, and MMP-2 was significantly higher than the control group (P 0.05). Conclusion Proper expressions of IL-6 and MMP-2 in the villus tissue play a key role in the maintenance of early pregnancy.

Rat fertility and early embryo development toxicity of intragastric administration of realgar / 中国药学杂志

OBJECTIVE: To observe the toxicity effect of realgar on rat fertility and early embryo development. METHODS: Male and female SD rats were divided into control group, realgar low (50 mg · kg-1), medium (125 mg · kg-1) and high (250 mg · kg-1) dose groups. Realgar (batch No. H2007052401) was given by i.g. daily to male rats from six weeks before mating until the successful mating day and to females from two weeks before mating until the sixth day of pregnancy. Male rats were sacrificed after mating, and female rats were sacrificed on the 15th day of pregnancy. The numbers of corpus luteum, implantation spot, and survival fetus were recorded. Histopathological examination was carried out. Statistical analysis was done to compare with the control group. RESULTS: The mating rates, pregnancy rates, live fetus rates, loss rates before and after implantation, the number of corpus luteum, the number of implantations and reproductive organs in realgar groups were not significantly different when compared with the control group. Histopathological examination showed that there were micro-vacuolization in liver cells, focal infiltration of mononuclear cells and steatosis in liver in some female rats (3/10) and male rats (1/10) in realgar high-dose groups. And some female rats (2/10) in realgar high-dose group had interstitial fibroblasts proliferation with lymphocyte infiltration and focal renal tubular basophilic change. CONCLUSION: Realgar has no significant toxicity effect on rat fertility and early embryo development, but has certain toxicity to liver and kidney.

The relation between cardiac development and Wnt/β-catenin signal transduction in early embryo / 基础医学与临床

The Wnt/β-catenin signal transduction pathway is essential for regulating cell proliferation, movement, differentiation and embryo development. Researchers have found that Wnt pathway is an important regulation factor in the early stimulation of the cardiogenesis and contacts closely the several key events during cardiac morphogenesis. The article reviews the recent studies about the relation between cardiac development and Wnt pathway in early embryo.

The relation between cardiac development and Wnt/?-catenin signal transduction in early embryo / 基础医学与临床

The Wnt/?-catenin signal transduction pathway is essential for regulating cell proliferation,movement,differentiation and embryo development. Researchers have found that Wnt pathway is an important regulation factor in the early stimulation of the cardiogenesis and contacts closely the several key events during cardiac morphogenesis. The article reviews the recent studies about the relation between cardiac development and Wnt pathway in early embryo.

THE ROLES OF SYMPATHETIC NERVE ON EMBRYO IMPLANTATION AND LOCAL IMMUNITY IN UTERUS OF MICE / 解剖学报

Objective To explore the effect mechanism of sympathetic nerve on early developing embryo of mice. Methods The model of sympathectomy mouse was established by 6-OHDA injected intraperitoneally.The early developing mice embryo and lymphocytes in uterus were observed using histology,immunohistochemistry and ELISA methods. Results In sympathectomy mouse,the number of embryo implantation was decrease to 64.4%,endometrial lamina propria and vascellum were shortfall.The numbers of CD4~+T cell and CD8~+T cell in sympathectomy mice were larger than ones in control groups,especially,the number of CD8~+T cells at E3 and E5 differed highly(P