Effects of Ages of Donors and Conditions of Preserving Ovaries on Porcine Oocytes Maturation in vitro and Efficiency of Parthenogenetic Activation

Effects of different ages of donors and different conditions of preserving ovaries onporcine oocytes maturation in vitro and efficiency of parthenogenetic activation werestudied. The experiments included: 1) effects of different temperatures (22, 30, 37, 38.5and 40℃) of preserving ovaries on porcine oocytes maturation in vitro and developmentalpotential; 2) effects of periods of preserving ovaries on porcine oocytes maturation invitro and development in vitro; 3) effects of different ages of donors on porcine oocytesmaturation in vitro and developmental potential. The results of the experiment showed:1) There were no statistical differences (p>0.05) of the parthenogenetic cleavage rate(79.64% vs 76.18%) and blastocyst rate (18.11% vs 33.82%) between oocytes from ovariespreserved at 38.5℃ and those preserved at 37℃. When the preserving temperature wasincreased to 40℃, the cleavage rate (21.68%) and the blastocyst rate (0) were greatsignificantly lower than those at 37℃(p<0.01). The cleavage rate (80.79% vs 76.18%) andblastocyst rate (29.61% vs 33.82%) were not different between 30 and 37℃(p>0.05). Whenthe preserving temperature was decreased to 22℃, the rate of cleavage was not different,but the rate of blastocyst was significantly lower, compared with that at 37℃; 2) Thecleavage and blastocyst rates of the porcine oocytes collected after slaughter 2 or 6hwere not different (p>0.05); 3) The cleavage rate of oocytes from gilts and sows aftermaturation was not different, but the blastocyst rate of the sow group was significantlyhigher than that of gilt group (p<0.05). The blastocyst cell number of sows and giltshowed no difference (p>0.05).

Effects of Chemical Activation on the Parthenogenetic Development of Porcine in vitro Maturation Oocytes

The objective of this study was to determine the effects of ionomycin combined with cytochalasin B （CB）, cycloheximide （CHX）, or 6-dimethylaminopurine （6-DMAP） on the activation of porcine oocytes. In Experiment 1, in vitro matured oocytes were activated with 15, 20, 25 or 30 mmol L -1 ionomycin separately. Activation rates of 20, 25 mmol L-1 and 30 mmol L treatments were higher （P〈0.05） than that of 15 mmol L-1 treatment. In Experiment 2, in vitro matured oocytes were activated with 20 mmol L-1 ionomycin for 10, 20, 30, 40 or 50 rain and then incubated with 2 mmol L-1 6-DMAP for 6 h. Cleavage and blastocyst rates [（72.40 ± 13.02）%, （25.37 ± 11.43）%] after treatments for 40 min were higher （P〉0.05） than those of the other treatments. In Experiment 3, matured oocytes were activated with ionomycin and then incubated with 7.5 mg mL-1 CB, 10 mg mL-1 CHX, 2 mmol L-1 6-DMAP, 7.5 mg mL-1 CB ＋ 10 mg mL-1 CHX or 7.5 mg mL-1 CB ＋ 2 mmol L-1 6-DMAP for 6 h. The rates of activation, cleavage and blastocyst of 2 mmol L -1 6-DMAP treatment [（86.05 ± 4.29）%, （61.77 ±8.10）% and （21.62± 3.31）%] were higher （P〈0.05） than those of 7.5 mg mL-1 CB treatment. In Experiment 4, matured oocytes were activated with ionomycin and then incubated with 2 mmol L-1 6-DMAP for 3.5, 5.5 or 7.5 h. Cleavage rates and blastocyst rates of 5.5 h treatment [（66.59 ± 14.36）% and （25.40 ± 10.16）%] were higher （P〉0.05） than those of other treatments. In conclusion, activation of porcine oocytes appears to be most successful using the combination of ionomycin （20 mmol L-1, 40 min） followed by 6-DMAP （2 mmol L-1, 5.5 h）.

Melatonin improves the first cleavage of parthenogenetic embryos from vitrified-warmed mouse oocytes potentially by promoting cell cycle progression

Background:This study investigated the effect of melatonin(MT)on cell cycle(G1/S/G2/M)of parthenogenetic zygotes developed from vitrified-warmed mouse metaphase II(MII)oocytes and elucidated the potential mechanism of MT action in the first cleavage of embryos.Results:After vitrification and warming,oocytes were parthenogenetically activated(PA)and in vitro cultured(IVC).Then the spindle morphology and chromosome segregation in oocytes,the maternal mRNA levels of genes including Miss,Doc1r,Setd2 and Ythdf2 in activated oocytes,pronuclear formation,the S phase duration in zygotes,mitochondrial function at G1 phase,reactive oxygen species(ROS)level at S phase,DNA damage at G2 phase,early apoptosis in 2-cell embryos,cleavage and blastocyst formation rates were evaluated.The results indicated that the vitrification/warming procedures led to following perturbations 1)spindle abnormalities and chromosome misalignment,alteration of maternal mRNAs and delay in pronucleus formation,2)decreased mitochondrial membrane potential(MMP)and lower adenosine triphosphate(ATP)levels,increased ROS production and DNA damage,G1/S and S/G2 phase transition delay,and delayed first cleavage,and 3)increased early apoptosis and lower levels of cleavage and blastocyst formation.Our results further revealed that such negative impacts of oocyte cryopreservation could be alleviated by supplementation of warming,recovery,PA and IVC media with 10^(−9) mol/L MT before the embryos moved into the 2-cell stage of development.Conclusions:MT might promote cell cycle progression via regulation of MMP,ATP,ROS and maternal mRNA levels,potentially increasing the first cleavage of parthenogenetic zygotes developed from vitrified-warmed mouse oocytes and their subsequent development.

Comparative Study on Activation and Fertilization of Mouse Oocytes at Different Ages

Comparisons of activation rates and fertilization rates were made among oocytes at different ages. Results showed that oocytes at different ages had different activation and fertilization rates when stimulated by sperm or ethanol. Oocytes at 15～24 h after the injection of hCG were readily activated by 8% ethanol. The activation rate of oocytes increased with the age of oocytes, up to the highest average of 81.6%, but decreased after 20 h posthCG. Oocytes at 20 h posthCG exhibited the highest immediate cleavage rate(48.0%) after being stimulated by ethanol. On the other hand, 13～15 h oocytes exhibited higher fertilization rates, and the older oocytes were more difficult to be fertilized by sperm in vitro. These suggest that oocytes can be activated in different ways; the mechanism of fertilization might be different from that of activation; and in vitro fertilization is more dependent on oocyte age.

Studies on Electrical Activation of Porcine Oocytes Matured in vitro and Embryo Culture Systems

Conditions for electrical parthenogenetic activation of porcine oocytes matured in vitro and in vitro culture systems of porcine embryo were studied. The best results were achieved under the conditions of electrical field strength and the pulse duration at 130Vmm-1/80 us, with a blastocyst development rate of (20.12 ± 8.18) % (P > 0.05). No significant difference was found between treatments of multiple pulses and a single pulse (P > 0.05). Parthenogenetic embryos were cultured with different methods and air conditions for 7 days in vitro, blastocyst development rate of embryos with changed culture media [ (26.44 ± 8.35) % ] or changed media with 10% fetal bovine serum (FBS) [ (17.68 ± 5.39)% ] on the fifth day showing no significant difference from that of embryos without change of culture media [ (25.30 ± 7.55) % , P > 0.05 ], while cell numbers of blastocysts from embryos with changed culture media (15.78 + 5.46 and 14.55 ± 4.81) were significantly lower than number of blastocysts from embryos without change of culture media (18.01 ± 6.79, P<0.01). Blastocyst development rate and blastocyst cell number of embryos cultured in lower O2(5%CO2: 7%O2:88%N2) also showed no significant difference from those in high O2(5%CO2 in air) [(20.78 ± 8. 80)% and 17.0016.12 vs. (25.30 ± 7.55)% and 18.0116.79, P>0.05]. It is concluded that change of culture media with the same new one or changing over to media with 10% fetal bovine serum (FBS) on the fifth day and low O2 environment are not necessary for porcine embryos development.

Collection of superovulated mouse oocytes continuously by surgery and their development after activation

Objective:To establish a new way to collect superovulated oocytes or zygotes repeatedlyfrom an individual mouse.Methods:Superovulations were induced by injection PMSG and hCG in Kunming strainmice.The ampullaes of oviduct of all anaesthetised mouse were put in a specially designed'U'sink and released.The second and third times of PMSG injection were made on the sixth day andeleventh day after the first superovulation injection.The capacity of development was examinedby in vitro culture of parthenogenesis activation oocytes.Results:Development to blastocyst stage was not significantly different between the first andsecond time collection.The percentage of blastocyst stage in CD and Sr^(++) treatment was signifi-cantly higher(P<0.05)than the oocytes treated in CB and Sr^(++).Conclusion:This method enables us to collect oocytes or zygotes repeatedly from one individ-ual mouse in an interval as short as 5 days and without influence on the quality of oocytes.

Studies on Methods and Influencing Factors of Porcine Oocyte Activation

The effects of ionomycin, electrical pulses, dithiothreitol(DTT), 6-DMAP and thimersal, used either alone or in combinations, on the activation rate, pronuclear type and cleavage of porcine oocyte were studied in this paper. The results are as follows:(1)The activation rates of oocytes treated with ionomycin(88.9%)or pulsed(80.0%)alone did not differ significantly from each other and from those in oocytes treated in combination with 6-DMAP(84. 3 and 79. 1%, respectively). While 6-DMAP improved electrical activation(increased the proportion of oocytes with 1 PN), it had no effect on oocyte activation by ionomycin;(2)Post-treatment with DTT significantly enhanced the thimersal activation of porcine oocytes with activation rates increased from 4.6 to 82.6%;(3)When pulsed, the activation rates of oocytes with crimped(85.4%)or fragmented first polar bodies(86. 2%)were significantly higher than those of oocytes with intact polar bodies(58. 8%); the ratio of 1 PN activated oocytes(78. 8%)was significantly higher, but that of 2 PN oocytes(18. 2%)was significantly lower in oocytes with intact polar bodies;(4)The cleavage rate of oocytes activated by electrical stimulus(52.4%)was significantly higher than that in oocytes activated by ionomycin(23.0%)when combined with 6-DMAP, but it was not significantly different from that in oocytes activated by electrical stimulus alone(46.1%).

Parthenogenesis and activation of mammalian oocytes for <i>in vitro</i>embryo production: A review

Parthenogenesis is a form of asexual reproduction found in females, where growth and development of embryos occurs without fertilization by a male. Parthenogenesis occurs naturally in aphids, Daphnia, rotifers, nematodes and some other invertebrates but can also be induced efficiently in mammalian oocytes by providing appropriate stimuli invitro. Recently, parthenogenesis has attracted wide attention because of the role of activated oocytes in the field of research that have been described such as intra cytoplasmic sperm injection, cloning by nuclear transfer, somatic cell cloning, investigating culture conditions etc. & potential for deriving pluripotent stem cell lines and their differentiation into various cell lines that can be utilized for various tissue engineering applications. The parthenogenetically activated oocytes possess maternal genome and can developed in to either haploid, diploid or polyploidy embryos with the help of it we can analyze the possible role of all the genes involved in imprinting processes as well as the role the paternal genome plays during early embryo development by comparing them with fertilized embryos. Several methods are able to induce parthenogenetic activation through the elevation of cytoplasmic free calcium in oocytes. But one common, universal method or activation agents has not been developed for all species because the process is highly specific for each species. Therefore, activation step for each species need to be optimized accordingly. This review describes the general method of activation of mammalian oocytes and their genomic imprinting analysis.

The fertilization-induced Ca^(2+) oscillation in mouse oocytes is cytoplasmic maturation dependent

Mature eggs (at metaphase Ⅱ stage) produce a series of Ca2+ oscillation at fertilization. To define whether the fertilization-induced Ca2+ oscillation is restrict to the metaphase Ⅱ eggs and cell cycle dependent, mouse oocytes at prophase Ⅰ (arrested at germinal vesicle stage),metaphase Ⅰ, metaphase Ⅱ, as well as the pronuclear embryos at interphase of the first mitotic division derived from fertilization or parthenogenetic activation were inseminated after removal of zona pellucida. The results show that the fertilization-induced Ca2+ oscillation is not specific to metaphase Ⅱ eggs. This is supported by the fact that immature oocytes generated the Ca2+ oscillations at fertilization regardless of their nuclear progression from prophase Ⅰ to metaphase Ⅰ (in vitro matured) stage. More interestingly, it was first found that pronuclear embryos at interphase derived from parthenogenetic activation showed Ca2+ oscillations in response to fertilization while the zygotes at interphase did not after reinsemination or intracytoplasmic injection of sperm extracts which induce Ca2+ oscillations in MII eggs. This suggests that the ability of oocytes to generate Ca2+ oscillation in response to sperm penetration is not regulated in a cell cycle dependent manner but dependent on the cytoplasmic maturation.

No effect of exogenous melatonin on development of cryopreserved metaphase Ⅱ oocytes in mouse

Background： This study was conducted to investigate effect of exogenous melatonin on the development of mouse mature oocytes after cryopreservation. Results： First, mouse metaphase II （MII） oocytes were vitrified in the open-pulled straws （OPS）. After warming, they were cultured for 1 h in M2 medium containing melatonin at different concentrations （0, 10-9, 10-7, 10-s, 10 3 mol/L）. Then the oocytes were used to detect reactive oxygen species （ROS） and glutathione （GSH） levels （fluorescence microscopy）, and the developmental potential after parthenogenetic activation. The experimental results showed that the ROS level and cleavage rate in 10-3 mol/L melatonin group was significantly lower than that in melatonin-free group （control）. The GSH levels and blastocyst rates in all melatonin-treated groups were similar to that in control. Based on the above results, we detected the expression of gene Hsp9Oaal, Hsfl, Hspalb, Nrf2 and Bcl-xl with qRT-PCR in oocytes treated with 10-7, or 10-3 mol/L melatonin and untreated control. After warming and culture for 1 h, the oocytes showed higher Hsp90oal expression in 10-7 mol/L melatonin-treated group than in the control （P 〈 0.05）; the Hsfl, Hsp9Oaal and Bcl-xl expression were significantly decreased in 10-3 mol/L melatonin-treated group when compared to the control. Based on the above results and previous research, we detected the development of vitrified-warmed oocytes treated with either 10-7 or 0 mol/L melatonin by in vitro fertilization. No difference was observed between them. Conclusions： Our results indicate that the supplementation of melatonin （10-9 to 10-3 mol/L） in culture medium and incubation for 1 h did not improve the subsequent developmental potential of vitrified-warmed mouse MII oocytes, even if there were alteration in gene expression.

Pronuclear formation by ICSI using chemically activated ovine oocytes and zona pellucida bound sperm

Background： In order to improve ICSI, appropiate sperm selection and oocyte activation is necessary. The objective of the present study was to determine the efficiency of fertilization using ICSI with chemically activated ovine oocytes and sperm selected by swim up（SU） or swim up ＋ zona pellucida（SU ＋ ZP） binding.Results： Experiment 1, 4–20 replicates with total 821 in vitro matured oocytes were chemically activated with ethanol, calcium ionophore or ionomycin, to determine oocyte activation（precense of one PN）. Treatments showed similar results（54, 47, 42 %, respectively） but statistically differents（P 0.05）.Conclusions： Chemical activation induces higher ovine oocyte activation than mechanical activation. Ethanol slightly displays higher oocyte activation than calcium ionophore and ionomicine. Sperm selection with SU ＋ ZP increased AR/A and AR/D rates in comparison with SU in fresh and frozen-thawed sperm. According to this, in terms of fertilization rates, chemical activation after ICSI increased oocyte PN formation compared to mechanical activation. Also, fresh sperm treated with SU and SU ＋ ZP were significantly different than frozen-thawed sperm,but between sperm treatments no significant differences were obtained.

No genetic alterations in infants from intracytoplasmic sperm injection in combination with artificial oocyte activation： a pilot study

The combination of intracytoplasmic sperm injection （ICSI） with artificial oocyte activation has overcome repeated fertilization failure after ICSI due to sperm defects in activating oocyte, resulting in pregnancies and births for many couples. However, in comparison to the growing data illustrating the effectiveness of artificial oocyte activation in reproductive medicine, the safety of this approach has not been well studied. Previously,

Generation of developmentally competent oocytes and fertile mice from parthenogenetic embryonic stem cells

Parthenogenetic embryos,created by activation and diploidization of oocytes,arrest at mid-gestation for defective paternal imprints,which impair placental development.Also,viable offspring has not been obtained without genetic manipulation from parthenogenetic embryonic stem cells(pESCs)derived from parthenogenetic embryos,presumably attributable to their aberrant imprinting.We show that an unlimited number of oocytes can be derived from pESCs and produce healthy offspring.Moreover,normal expression of imprinted genes is found in the germ cells and the mice.pESCs exhibited imprinting consistent with exclusively maternal lineage,and higher X-chromosome activation compared to female ESCs derived from the same mouse genetic background.pESCs differentiated into primordial germ cell-like cells(PGCLCs)and formed oocytes following in vivo transplantation into kidney capsule that produced fertile pups and reconstituted ovarian endocrine function.The transcriptome and methylation of imprinted and X-linked genes in pESC-PGCLCs closely resembled those of in vivo produced PGCs,consistent with efficient reprogramming of methylation and genomic imprinting.These results demonstrate that amplification of germ cells through parthenogenesis faithfully maintains maternal imprinting,offering a promising route for deriving functional oocytes and having potential in rebuilding ovarian endocrine function.

Spontaneous activation of hamster oocytes in vitro

Objectives To observe the time of spontaneous activation of hamster oocytes and to find out the early signs of hamster oocytes activation Methods First, 63 hamster oocytes including activated and non activated oocytes (group A) and 51 non activated oocytes (group B) were injected with human sperm and checked for fertilization after 16-18 hours Then, 20 hamster oocytes were cultured in vitro in medium with or without calcium and examined under light microscope every half an hour up to 9 hours Results Under light microscope, hamster oocytes activation were observed to undergo 4 stages: metaphase Ⅱ stage without meiotic spindle, appearance of meiotic spindle near the first polar body, protrusion of oolemma, and complete extrusion of second polar body with pronucleus formation After culture for 1 5 hours in vitro, 30% 40% of the oocytes demonstrated meiotic spindle; but after 9 hours, 50% showed complete activation Culture in medium without calcium showed a little delay in the process of activation The earliest sign of spontaneous activation in hamster oocytes was the appearance of meiotic spindle near the first polar body Although group A and B showed no difference, the damage rate was lower in group B (19 7%±16 6%) than in group A (35 9%±5 7%) ( P =0 08), whereas the fertilization rate (18 3%±10 9%) was higher in group B than in group A (14 2%±8 7%) ( P =0 135) Conclusions Hamster oocytes may be activated spontaneously early after their removal It is important to recognize the earliest sign of spontaneous activation and perform intracytoplasmic sperm injection (ICSI) before it happens

Derivation of human embryonic stem cell lines from parthenogenetic blastocysts

Parthenogenesis is one of the main, and most useful, methods to derive embryonic stem cells （ESCs）, which may be an important source ofhistocompatible cells and tissues for cell therapy. Here we describe the derivation and characterization of two ESC lines （hPES-1 and hPES-2） from in vitro developed blastocysts following parthenogenetic activation of human oocytes. Typical ESC morphology was seen, and the expression of ESC markers was as expected for alkaline phosphatase, octamer-binding transcription factor 4, stage-specific embryonic antigen 3, stage-specific embryonic antigen 4, TRA- 1-60, and TRA- 1-81, and there was absence of expression of negative markers such as stage-specific embryonic antigen 1. Expression of genes specific for different embryonic germ layers was detected from the embryoid bodies （EBs） of both hESC lines, suggesting their differentiation potential in vitro. However, in vivo, only hPES-1 formed teratoma consisting of all three embryonic germ layers （hPES-2 did not）. Interestingly, after continuous proliferation for more than 100 passages, hPES-1 cells still maintained a normal 46 XX karyotype; hPES-2 displayed abnormalities such as chromosome translocation after long term passages. Short Tandem Repeat （STR） results demonstrated that the hPES lines were genetic matches with the egg donors, and gene imprinting data confirmed the parthenogenetic origin of these ES cells. Genome-wide SNP analysis showed a pattern typical of parthenogenesis. All of these results demonstrated the feasibility to isolate and establish human parthenogenetic ESC lines, which provides an important tool for studying epigenetic effects in ESCs as well as for future therapeutic interventions in a clinical setting.

A live birth of activated one-day-old unfertilized oocyte for a patient who experienced repeatedly near-total fertilization failure after intracytoplasmic sperm injection

Total or near-total fertilization failure after intracytoplasmic sperm injection （ICSl） is a rare event, but it occurs repeatedly because of sperm defects in activating oocyte. The case presents a successful pregnancy and live birth after calcium ionophore A23187 （A23187） activation on one-day-old unfertilized oocytes in a patient whose husband suffered oligoasthenoteratozoospermia, and who had experienced repeated near-total fertilization failure after ICSI. In the second ICSI cycle, only one oocyte was fertilized while nine were unfertilized. Oocyte activation with A23187 were performed on the one-day-old unfertilized oocytes after ICSI and resulted in fertilization and embryo transfer. A clinical pregnancy was achieved and a healthy baby was born. To our knowledge, this is the first reported case of a healthy birth after oocyte activation on the one-day-old unfertilized oocyte. This indicates that ＂rescue oocyte activation＂ on one-day-old unfertilized oocytes after ICSI may be helpful for preventing total or near-total fertilization failure after ICSI.

A FACTOR FROM GRANULOSA CELLS CAN STIMULATE OOCYTE TISSUE PLASMINOGEN ACTIVATOR ACTIVITY

Several studies indicate that substances synthesized by granulosa cells are capableof regulating oocyte activity. We have studied the effect of factors synthesized by gran-ulosa cells on tPA activity of denuded oocytes using a co- culture system. The resultsshow that an FSH- dependent factor(s) synthesized by granulosa cells (but not by theca-interstitial cells) is capable of stimulating tPA activity of denuded oocytes. This findingis important for understanding hormonal regulation of oocyte tPA activity by mediatorssynthesized in granulosa cells.

回族及维吾尔族圆头精子症患者的基因诊断、精子超微结构观察和辅助生殖结局分析

目的探讨2例少数民族(P1回族、P2维吾尔族)圆头精子症患者的临床表型、精子特点、遗传学病因以及辅助生殖结局。方法分析2例少数民族圆头精子症患者的临床资料和各种精液检查参数,观察精子超微结构,并利用全外显子检测技术和qPCR检测分析患者的遗传学病因,采用卵胞质内单精子注射联合卵母细胞激活技术(ICSI+AOA)进行辅助生殖治疗,并观察其助孕结局。结果2例患者均存在DPY19L2基因109681 bp纯合缺失,其中P2患者的DPY19L2基因缺失来源于近亲结婚的父母。P1患者精子活力低下,精子DNA碎片率高,精子形态为100%圆头精子,电镜下发现精子顶体缺失,同时存在质膜、线粒体和微管等超微结构缺陷;P2患者精子活力及精子DNA碎片率均正常,精子形态为100%圆头精子,电镜下观察发现精子主要缺陷为头部小而圆伴随顶体缺失,质膜、线粒体和微管等细胞器结构损伤与超微结构缺陷少见。2例患者夫妇均接受ICSI+AOA助孕,ICSI受精率P1患者夫妇为62.5%,P2患者夫妇为75%,均成功获得临床妊娠。结论DPY19L2基因异常在不同民族背景的圆头精子症患者中都是主要的致病遗传学原因。圆头精子可同时存在质膜、线粒体和微管等细胞器结构损伤与超微结构缺陷。ICSI+AOA是圆头精子症患者的有效辅助生殖治疗。

基于Smart-seq2探究玻璃化冷冻对猪孤雌激活囊胚基因表达的影响

旨在探究玻璃化冷冻对猪孤雌激活(parthenogenetic activation,PA)囊胚基因表达的影响。本研究以猪PA囊胚为研究对象,根据试验处理分为新鲜组、玻璃化冷冻组Ⅰ和玻璃化冷冻组Ⅱ,随后从每组挑选3枚形态良好的囊胚,利用Smart-seq2单细胞全长转录组测序技术进行转录组测序分析。结果显示,玻璃化冷冻组Ⅰ与新鲜组相比,共鉴定到772个差异表达基因(differential expression genes,DEGs),GO和KEGG富集分析结果显示,这些DEGs与细胞脂质代谢过程、细胞葡萄糖稳态、MAPK信号通路、PI3K-Akt信号通路等相关;玻璃化冷冻组Ⅱ与新鲜组相比,共鉴定到1613个DEGs,主要与糖异生、代谢途径、氨基酸生物合成等相关;玻璃化冷冻组Ⅱ与玻璃化冷冻组Ⅰ相比,鉴定到822个DEGs,主要与丙酮酸代谢过程、N-聚糖生物合成、细胞衰老等相关。综上,本研究基于Smart-seq2单细胞全长转录组测序技术揭示了玻璃化冷冻对猪PA囊胚脂质代谢、能量代谢、MAPK信号通路等相关基因表达的影响。

印记基因在孤雌生殖方面的研究进展

孤雌生殖是一种独特的生殖方式,指的是卵母细胞在不经过受精的情况下,可以自发或通过物理、化学刺激发育为正常个体,而无需精子参与。在低等动物中,孤雌生殖可以仅由雌性个体完成,从而实现从单个雌性个体产生后代。然而在哺乳动物中,能够通过孤雌生殖发育为正常个体的实例极为罕见。该文介绍了孤雌激活的方式,孤雌胚胎获取方式和印记基因在孤雌生殖中的应用,以期为未来孤雌生殖的相关应用提供思路。