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1.
Swamp buffalos are becoming endangered due to reproductive inefficiencies. This is of concern because many countries depend heavily on their products. Somatic cell nuclear transfer (SCNT) is a potential strategy for preserving endangered species. To date, SCNT in swamp buffalo has succeeded in the creation of blastocyst embryos. However, development to term of SCNT swamp buffalos is extremely limited, and only 1 live birth has been reported. An abnormal epigenetic mechanism is suspected to be the cause of developmental failure, as is also seen in other species. The DNA methylation and histone acetylation are key players in epigenetic modification and display marked variability during embryonic preimplantation development. Knowledge of epigenetic modifications will aid in solving the developmental problems of SCNT embryos and improving reproductive technology in the swamp buffalo. The objective of this study was to determine the relationship between preimplantation embryonic development and 2 epigenetic patterns, global DNA methylation and histone acetylation, in SCNT and in vitro-fertilized (IVF) swamp buffalo embryos. In addition, we examined the correlations between those 2 mechanisms in the SCNT and IVF swamp buffalo embryos throughout the developmental stages using double immunostaining and quantification of the emission intensities using confocal microscopy. We discovered an aberrant methylation pattern in early preimplantation-stage swamp buffalo SCNT embryos. In addition, greater variability in the DNA methylation levels among nuclei within SCNT embryos was discovered. Hyperacetylation was also observed in SCNT embryos compared with IVF embryos at the 4- and 8-cell stages (P < 0.05). Dynamic changes and interplay between these 2 epigenetic mechanisms could be crucial for embryonic development during the early preimplantation period. The aberrancies uncovered here may contribute to the low efficiency of SCNT.  相似文献   

2.
Phosphorylation of histone H3 at Ser10 (H3S10P) has been linked to a variety of cellular processes, such as chromosome condensation and gene activation/silencing. Remarkably, in mammalian somatic cells, H3S10P initiates in the pericentromeric heterochromatin during the late G2 phase, and phosphorylation spreads throughout the chromosomes arms in prophase, being maintained until the onset of anaphase when it gets dephosphorylated. Considerable studies have been carried out about H3S10P in different organisms; however, there is little information about this histone modification in mammalian embryos. We hypothesized that this epigenetic modification could also be a marker of pericentromeric heterochromatin in preimplantation embryos. We therefore followed the H3S10P distribution pattern in the G1/S and G2 phases through the entire preimplantation development in in vivo mouse embryos. We paid special attention to its localization relative to another pericentromeric heterochromatin marker, HP1β and performed immunoFISH using specific pericentromeric heterochromatin probes. Our results indicate that H3S10P presents a remarkable distribution pattern in preimplantation mouse embryos until the 4-cell stage and is a better marker of pericentromeric heterochromatin than HP1β. After the 8-cell stage, H3S10P kinetic is more similar to the somatic one, initiating during G2 in chromocenters and disappearing upon telophase. Based on these findings, we believe that H3S10P is a good marker of pericentromeric heterochromatin, especially in the late 1- and 2-cell stages as it labels both parental genomes and that it can be used to further investigate epigenetic regulation and heterochromatin mechanisms in early preimplantation embryos.  相似文献   

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Chromium in its trivalent form (chromium (III)) is an essential component of a balanced diet, and its deficiency disturbs glucose and lipid metabolism in humans and animals. The prevailing view is that chromium (III) is notably less toxic than chromium (VI), which is genotoxic and carcinogenic. Thus, the biotransformation of environmental chromium (VI) to chromium (III) is a promising and environmentally friendly detoxification method. However, increasing evidence suggests that chromium (III) induces considerable cytotoxicity. However, the toxicity of chromium (III) to early embryos remains largely unknown. In the present study, we used in vitro fertilization (IVF) to produce mouse embryos and identified the direct embryotoxicity of chromium (III). On exposure to high concentrations of CrCl3, blastocyst formation almost completely failed and a large proportion of embryos were arrested at the 2- to 4-cell stage. At low concentrations of CrCl3, IVF embryos showed a significant decrease in blastocyst formation, reduced total cell numbers, aberrant lineage differentiation, increased oxidative stress, and apoptosis. We also found that chromium (III) exposure during the preimplantation stage, even at low concentrations, led to impaired post-implantation development. Thus, our study substantiates the direct embryotoxicity of chromium (III) during preimplantation development and prolonged impairment of development potential. The results further highlight the potential adverse effects of chromium (III) on public reproductive health with respect to increased environmental enrichment of and dietary supplementation with chromium (III) complexes.  相似文献   

5.
哺乳动物个体由终端分化的单倍体精子和卵子受精融合成的双倍体受精卵发育而来。在胚胎发育的初始阶段,合子基因组处于休眠状态,胚胎发育调控由卵母细胞内母源调控逐渐转换为合子基因组调控(Maternal-Zygotic Transition,MZT)。在此期间,随着母源物质的清除,合子基因组激活(Zygotic Genome Activation,ZGA),但调控MZT的具体分子机制还不清楚。最新研究表明,DNA甲基化、染色质重塑、组蛋白表观修饰、ncRNA在MZT和ZGA中发挥重要的作用。本文总结了上述4种表观修饰在动物植入前胚胎MZT中的生物学功能和特异的分子机制,对揭示动物胚胎MZT的调控机理有借鉴意义。  相似文献   

6.
Mammalian preimplantation embryos enter the S phase immediately after the end of the M phase; their cell cycle lacks a substantial G1 phase. Previously, we suggested that the absence of the G1 phase was attributable to a loss of retinoblastoma protein (RB) function, which is required for suppression of S phase entrance and that this loss of RB function in turn was attributable to the low RB expression level during preimplantation development in mouse embryos. The present study aimed to examine whether or not RB inhibition by CDK4/6-cyclin D-dependent phosphorylation is involved in the loss of RB function in preimplantation mouse embryos by the expression of p16(INK4a), a potent endogenous inhibitor of CDK4/6-cyclin D. First, the decrease in RB expression between the four-cell and morula stages was confirmed in in vivo-derived mouse embryos. We then examined the efficiency of the p16(INK4a) expression vector in inhibiting RB phosphorylation and cell cycle progression using NIH-3T3 cells and obtained gradual RB dephosphorylation and a significantly lower proliferation rate in p16(INK4a)-transfected cells than in control cells. This indicated the successful p16(INK4a) effects on cell-cycle progression by the vector used. On the other hand, the development rate of mouse embryos injected with the p16(INK4a) expression vector was the same as that of the control embryos, although p16(INK4a) expression was detected at mRNA and protein levels in the former group but not in the control group. These results suggest that RB phosphorylation is not involved in RB dysfunction or in the lack of a G1 phase in mouse embryos and that the decrease in RB expression is important for preimplantation-embryo-specific cell-cycle regulation. Moreover, the present study indicates the similarity between preimplantation embryos and cancer cells, which p16(INK4a) expression does not arrest at the G1 phase.  相似文献   

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In a diabetic pregnancy, an altered maternal metabolism led to increased formation of reactive α‐dicarbonyls such as glyoxal (GO) and methylglyoxal (MGO) in the reproductive organs and embryos. The enzyme glyoxalase (GLO) 1 detoxifies reactive α‐dicarbonyls thus protecting cells against malfunction or modifications of proteins by advanced glycated end products (AGEs). The aim of this study was to analyse the influence of a maternal insulin‐dependent diabetes mellitus (IDD) on GLO1 expression and activity in preimplantation embryos in vivo and human trophoblast cells (Ac‐1M88) in vitro. Maternal diabetes was induced in female rabbits by alloxan before conception and maintained during the preimplantation period. GLO1 expression and activity were investigated in 6‐day‐old blastocysts from healthy and diabetic rabbits. Furthermore, blastocysts and human trophoblast cells were exposed in vitro to hyperglycaemia, GO and MGO and analysed for GLO1 expression and activity. During gastrulation, GLO1 was expressed in all compartments of the rabbit blastocyst. Maternal diabetes decreased embryonic GLO1 protein amount by approx. 30 per cent whereas the enzymatic activity remained unchanged, indicating that the specific GLO1 activity increases along with metabolic changes. In in vitro cultured embryos, neither hyperglycaemia nor MGO and GO had an effect on GLO1 protein amount. In human trophoblast cells, a stimulating effect on the GLO1 expression was shown in the highest GO concentration, only. Our data show that maternal diabetes mellitus affects the specific activity of GLO1, indicating that GLO1 was post‐translationally modified due to changes in metabolic processes in the preimplantation embryos.  相似文献   

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Epigenetics provides a molecular mechanism of inheritance that is not solely dependent on DNA sequence and that can account for non-Mendelian inheritance patterns. Epigenetic changes underlie many normal developmental processes, and can lead to disease development as wel. While epigenetic effects have been studied in wel-characterized rodent models, less research has been done using agricultural y important domestic animal species. This review wil present the results of current epigenetic research using farm animal models(cattle, pigs, sheep and chickens). Much of the work has focused on the epigenetic effects that environmental exposures to toxicants, nutrients and infectious agents has on either the exposed animals themselves or on their direct offspring. Only one porcine study examined epigenetic transgenerational effects; namely the effect diet micronutrients fed to male pigs has on liver DNA methylation and muscle mass in grand-offspring(F2 generation). Healthy viable offspring are very important in the farm and husbandry industry and epigenetic differences can be associated with production traits. Therefore further epigenetic research into domestic animal health and how exposure to toxicants or nutritional changes affects future generations is imperative.  相似文献   

11.
Epigenetics provides a molecular mechanism of inheritance that is not solely dependent on DNA sequence and that can account for non-Mendelian inheritance patterns. Epigenetic changes underlie many normal developmental processes, and can lead to disease development as well. While epigenetic effects have been studied in well-characterized rodent models, less research has been done using agriculturally important domestic animal species. This review will present the results of current epigenetic research using farm animal models (cattle, pigs, sheep and chickens). Much of the work has focused on the epigenetic effects that environmental exposures to toxicants, nutrients and infectious agents has on either the exposed animals themselves or on their direct offspring. Only one porcine study examined epigenetic transgenerational effects; namely the effect diet micronutrients fed to male pigs has on liver DNA methylation and muscle mass in grand-offspring (F2 generation). Healthy viable offspring are very important in the farm and husbandry industry and epigenetic differences can be associated with production traits. Therefore further epigenetic research into domestic animal health and how exposure to toxicants or nutritional changes affects future generations is imperative.  相似文献   

12.
The objective of this study was to evaluate the effect of retinol on the in vitro development of early embryos of cultured Bos indicus (Expt 1) to the blastocyst stage in medium simplex of optimization (KSOM) or sintetic fluid of oviduct (SOF) or co-cultured (Expt 2) with an oviduct cell monolayer (OCM) in KSOM or SOF. A total of 3149 cumulus-oocyte complexes obtained by aspirating follicles (2-5 mm diameter) from ovaries of slaughtered animals were selected for IVM and incubated in TCM 199 supplemented with 25 mM HEPES at 39 degrees C in air with 5% CO(2) and maximum humidity for 24 h. In vitro fertilization (IVF) was performed in modified defined medium (mDM) medium. Eighteen hours after IVF, cumulus cells were removed and presumptive zygotes were randomly allocated to the experimental groups. Zygotes cultured (Expt 1) in KSOM + retinol, KSOM, SOF + retinol and SOF were incubated in maximum humidity at 39 degrees C, 5% CO(2), 5% O(2) and 90% N(2). Zygotes co-cultured (Expt 2) in KSOM + retinol + OCM, KSOM + OCM, SOF + retinol + OCM and SOF + OCM were incubated at 39 degrees C, 5% CO(2). In both experiments media were partially changed 48 h after IVF and unfertilized ova were removed. Afterwards embryos were kept in culture or co-culture for further 9 days. In Expt 1, blastocyst rates (day 7) were 14.6% (KSOM + retinol), 15.8% (KSOM), 16.4% (SOF + retinol) and 15.9% (SOF). In Expt 2, the blastocyst rates (day 7) were 25.4% (KSOM + retinol + OCM) 14.2% (KSOM + OCM), 24.3% (SOF + retinol + OCM) and 15.9% (SOF + OCM). The same influence profile of retinol was observed in the formation of the expanded (day 9) and hatched (day 11) blastocysts. The results obtained in Expt 2 demonstrated that the addition of 0.28 microg/ml retinol to the embryo culture media used in this study had a significant (p < 0.05) positive effect on bovine early embryonic development, under the conditions tested, and can be used to enhance in vitro embryo production.  相似文献   

13.
Lysosomes are acidic and highly dynamic organelles that are essential for macromolecule degradation and many other cellular functions. However, little is known about lysosomal function during early embryogenesis. Here, we found that the number of lysosomes increased after fertilization. Lysosomes were abundant during mouse preimplantation development until the morula stage, but their numbers decreased slightly in blastocysts. Consistently, the protein expression level of mature cathepsins B and D was high from the one-cell to morula stages but low in the blastocyst stage. One-cell embryos injected with siRNAs targeted to both lysosome-associated membrane protein 1 and 2 (LAMP1 and LAMP2) were developmentally arrested at the two-cell stage. Pharmacological inhibition of lysosomes also caused developmental retardation, resulting in accumulation of lipofuscin. Our findings highlight the functional changes in lysosomes in mouse preimplantation embryos.  相似文献   

14.
This article presents a new, simple and rapid embryo biopsy method. The blastomere for genetic analysis can be separated from a precompacted mouse embryo after a partial zona digestion with the use of a holding pipette. For the micromanipulation only two microcapillaries and micromanipulators are needed. The development of the biopsied embryos was studied during in vitro culture and in utero following embryo transfer. There was no significant difference between the treated and the control groups in the ratio of embryos that developed to the blastocyst stage, although the biopsied embryos were delayed in their development because they contained significantly fewer cells compared to the control ones at the same stage. Although there was no difference in the ratio of implantation, the development of the biopsied embryos in utero was also delayed 12-24 hours on the 9th day of pregnancy. No difference in development was visible from the 13th day of pregnancy. Statistically, no differences were found in the developmental ratio (number of developed fetuses/transferred embryos) of the control and treated embryos during gastrulation (9th day of pregnancy), at the beginning of organogenesis (13th day of pregnancy) and before birth (19th day of pregnancy). The embryo biopsy method presented here can be a new and useful tool for preimplantation genetic diagnosis.  相似文献   

15.
本研究利用卵母细胞体外成熟(IVM)、体外受精(IVF)技术,体外生产牛胚胎,以获得试管牛.结果表明:卵母细胞体外培养22~24h后,其成熟率为85%;体外受精率为83%.体外受精卵分别在颗粒细胞单层(GCM)和输卵管细胞单层(OCM)上培养,其胚胎最后产量(以授精时卵母细胞的数目为基数)分别为19%和29%,差异极显著(P<0.01).若体外受精卵先在GCM中培养72h后,再将已发生卵裂的(>4细胞)胚胎移到OCM中培养,其胚胎最后产量为35%.由此表明,早期胚胎在其发育过程中至少存在着3个发育相期,即1~8细胞、8~16细胞和16细胞~囊胚3个阶段,各阶段需要不同的培养环境.IVM/IVF胚胎移植到受体黄牛体内后,其足月时的妊娠率为15%.第一头试管犊牛已于1993年4月18日凌晨产出.  相似文献   

16.
将小鼠附植前胚胎分别经戊二醛一锇酸固定后,采取琼脂糖预包埋法使胚胎凝聚成团,然后对含胚胎的琼脂糖块进行脱水、渗透和包埋。结果显示,Epon812包埋块中的胚胎排列紧密,半薄切片胚胎的整体形态完整,胚胎超微结构保存良好。说明琼脂糖预包埋法是制备小鼠附植前胚胎超薄切片的有效方法。  相似文献   

17.
The embryo culture technique has been improving, but the detailed demands for energy substrates such as glucose, fructose, pyruvate and lactate of preimplantation embryos are still unclear. In the present study, the demands of pig preimplantation embryos at each different developmental stage were investigated by use of parthenogenetic diploids as a model of pig preimplantation embryos. Pig parthenogenetic diploids showed different use of glucose and fructose before and after the 4-cell stage. Although glucose supported the development of pig embryos throughout the preimplantation stages and even maintained the expansion and hatching of blastocysts, it suppressed development to the blastocyst stage when glucose coexisted with pyruvate and lactate from 4 h after activation, but not after 48 h (early 4-cell stage). Since ketohexokinase that metabolizes fructose was not expressed in 2-cell and 4-cell diploids, a medium that included only fructose as a major energy substrate did not support early cleavage of pig diploids beyond the 4-cell stage, and almost no diploids developed to the morula stage just as in a medium without carbohydrates. These results may explain the different suppressive effects on pig preimplantation development between glucose and fructose when pyruvate and lactate were present in a medium. In addition, 4-cell diploids that had been cultured in a medium with pyruvate and lactate developed to the expanded blastocyst stage without any carbohydrates as a major energy substrate. These results show that the demands for carbohydrates are different depending on the developmental stage in pig preimplantation embryos.  相似文献   

18.
We found retardation of preimplantation embryo growth after exposure to maternal restraint stress during the preimplantation period in our previous study. In the present study, we evaluated the impact of preimplantation maternal restraint stress on the distribution of inner cell mass (ICM) and trophectoderm (TE) cells in mouse blastocysts, and its possible effect on physiological development of offspring. We exposed spontaneously ovulating female mice to restraint stress for 30 min three times a day during the preimplantation period, and this treatment caused a significant increase in blood serum corticosterone concentration. Microscopic evaluation of embryos showed that restraint stress significantly decreased cell counts per blastocyst. Comparing the effect of restraint stress on the two blastocyst cell lineages, we found that the reduction in TE cells was more substantial than the reduction in ICM cells, which resulted in an increased ICM/TE ratio in blastocysts isolated from stressed dams compared with controls. Restraint stress reduced the number of implantation sites in uteri, significantly delayed eye opening in delivered mice, and altered their behavior in terms of two parameters (scratching on the base of an open field test apparatus, time spent in central zone) as well. Moreover, prenatally stressed offspring had significantly lower body weights and in 5-week old females delivered from stressed dams, fat deposits were significantly lower. Our results indicate that exposure to stress during very early pregnancy can have a negative impact on embryonic development with consequences reaching into postnatal life.  相似文献   

19.
The development of preimplantation mammalian embryos in vitro is less than optimal. Follicular fluid and cumulus cells have both been used independently, to improve preimplantation embryo quality in culture. This study was undertaken to evaluate the influence of a cumulus cell monolayer in human follicular fluid on mouse early embryo development in vitro. One-cell embryos were obtained from NMRI mice after superovulation with eCG and hCG. Cumulus cells were prepared from mouse egg-cumulus mass. These cells were separated from red blood cells using a Percoll gradient. Follicular fluid was collected from patients undergoing an IVF program during oocyte pick-up. The cumulus cell monolayer was prepared in follicular fluid (FC) and Ham's F10 (HC). Mouse one-cell embryos were cultured in FC, HC, Ham's F10 (HF) and follicular fluid (FF) for 120 h. Only 10.5% of embryos passed the two-cell block in HF. However, the proportions of embryos passing the two-cell block were 23.1%, 21.4% and 68.5% in FF, HC, and FC treatments, respectively; which were significantly different from HF (p<0.05). The differences between FC and the two other treatments were also significant (p<0.001). In FC, 33.7% of one-cell embryos continued to grow to the blastocyst stage whereas only 2.1% and 1.9% of one-cell embryos in FF and HC reached this stage and no embryos developed to blastocyst in HF. The proportion of blastocysts in FC was significantly higher than all other treatments (p<0.001). It can be concluded that follicular fluid and cumulus cells in monolayer form synergistically improve the early embryo culture condition.  相似文献   

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