28 EFFECT OF TRICHOSTATIN A ON IN VITRO EMBRYO DEVELOPMENT OF INTERSPECIES NUCLEAR TRANSFER EMBRYOS RECONSTRUCTED FROM CAT DONOR NUCLEI AND BOVINE CYTOPLASM

2013 ◽  
Vol 25 (1) ◽  
pp. 161 ◽  
Author(s):  
M. Wittayarat ◽  
Z. Namula ◽  
V. V. Luu ◽  
L. T. K. Do ◽  
Y. Sato ◽  
...  

Interspecies somatic cell nuclear transfer (iSCNT) is an invaluable tool for studying nucleus-cytoplasm interactions and may provide an alternative for cloning endangered animals whose oocytes are difficult to obtain. The developmental ability of iSCNT embryos decreases with increases in taxonomic distance between the donor and recipient species. The development of cat-bovine iSCNT embryos is reportedly blocked at the 8-cell stage (Thongphakdee et al. 2008 J. Reprod. Dev. 54, 142–147). Abnormal epigenetic reprogramming, such as DNA methylation or histone modifications, may cause low iSCNT efficiencies. The present study was conducted to evaluate the effect of the histone deacetylase inhibitor trichostatin A (TSA), previously used to enhance nuclear reprogramming following SCNT, on the developmental ability of cat iSCNT embryos using bovine oocytes matured in vitro. The matured bovine oocyte was enucleated by the glass needle and the domestic cat fetal fibroblast used as the donor nuclei was then placed into the perivitelline space adjacent to the plasma membrane of the oocyte. Couplets with bovine ooplasm were fused and activated simultaneously with a single DC pulse of 2.3 kV cm–1 for 30 µs, respectively, using an electro cell fusion generator followed by cycloheximide treatment. Reconstructed cat-bovine embryos were treated with 0, 25, 50, and 100 nM concentrations of TSA for 24 h following fusion. The percentages of embryos cleaved and embryos developed to the blastocyst stage were subjected to arc sin transformation before ANOVA. The TSA treatment at 50 nM contributed significantly higher rates of cleavage and blastocyst formation (n = 139; 84.3 and 4.6%, respectively) compared with untreated embryos (n = 187; 63.8 and 0%, respectively) and embryos treated with 100 nM TSA (n = 172; 71.4 and 0%, respectively; P < 0.05). Development to the morula stage of iSCNT embryos was observed in the TSA treatment groups, whereas no embryos developed beyond the 16-cell stage in the untreated group. In conclusion, our results indicate that TSA treatment for 24 h following fusion improves the development of iSCNT embryos. Specifically, 50 nM TSA treatment provides a beneficial effect on cleavage and development to the blastocyst stage of cat iSCNT embryos using bovine oocytes matured in vitro as recipients and domestic cat fibroblasts as donor nuclei.

2015 ◽  
Vol 27 (1) ◽  
pp. 113
Author(s):  
L. T. K. Do ◽  
Y. Sato ◽  
M. Taniguchi ◽  
T. Otoi

The developmental ability of interspecies somatic cell nuclear transfer (iSCNT) embryos decreases as the taxonomic distance between the donor and recipient species increases. Treatment of cat iSCNT embryos using bovine oocytes with 50 nM of trichostatin A (TSA) improves in vitro embryonic development (Wittayarat et al. 2013 Cell. Reprogram. 15, 301–308). This study investigated whether the TSA treatment effects differ between the development of cat iSCNT embryos reconstructed with porcine and bovine oocytes. Porcine and bovine cumulus-oocyte complexes were in vitro matured for 44 h and 24 h, respectively. After cumulus cell removal, enucleation was performed by aspiration of the metaphase II plate and the first polar body using a piezo-driven pipette. A cat fibroblast cell was then injected into cytoplasm of successfully enucleated oocyte. Reconstructed cybrids were electrically activated by a single 1.5 kV cm–1 pulse for 100 µs (pig-cat embryos), or a 2.3 kV cm–1 pulse for 30 µs (cow-cat embryos). Pig-cat and cow-cat embryos were cultured in porcine zygote medium (PZM)-5 and modified synthetic oviducal fluid medium (mSOF), respectively. After electrical activation, pig-cat and cow-cat embryos were cultured in medium supplemented with 5 µg mL–1 cytochalasin B + 50 nM TSA (TSA group) or without TSA (control group), and the cow-cat embryo medium was also supplemented with 10 µg mL–1 cycloheximide. After 2 h, TSA-treated pig-cat and cow-cat embryos were incubated in medium supplemented with TSA for 22 h, followed by 48 h incubation without TSA. Pig-cat and cow-cat control embryos were cultured in medium without TSA for 70 h after activation. Then, all pig-cat and cow-cat embryos were cultured in porcine blastocyst medium (PBM) or mSOF medium supplemented with 5% fetal bovine serum, respectively, for 5 additional days. Four to seven replicates were performed for each experiment. Data were analysed using Student's t-test. For pig-cat embryos, no difference was observed in cleavage rates between both groups, but development to the blastocyst stage was higher in the pig control group (n = 147, 8.0%) than that of pig TSA group (n = 131, 0.7%; P < 0.05). In contrast, development to the blastocyst stage in cow-cat embryos was not observed in the cow control group (n = 125, 0%), but it was observed in cow TSA group (n = 136, 3.7%). These results indicate that TSA treatment effects are species-specific, but those effects remain to be clarified.


1995 ◽  
Vol 7 (5) ◽  
pp. 1217 ◽  
Author(s):  
F Delhaise ◽  
FJ Ectors ◽  
Roover R de ◽  
F Ectors ◽  
F Dessy

The developmental potential of nuclei of bovine gonial cells was investigated by nuclear transfer. Gonial cells were collected from male fetuses at about 175 days post coitum (p.c.). They were fused with enucleated oocytes; reconstituted embryos were cultured in vitro for 7 days. Embryos reaching the compacted morula or blastocyst stage were either fixed for cell counting or transferred into recipients. Out of 115 oocyte-gonia fusions, 101 (87.8%) gave rise to cleaved embryos at Day 3 and 26 (22.6%) had reached the 8-cell stage. At Day 7, 1 (1%) developed to the morula stage and 5 (4%) reached the blastocyst stage. Three blastocysts were fixed and showed normal cell numbers (135; 90; 76 cells). Three blastocysts and one morula were transferred in four recipients; two recipients were pregnant at Day 21 but only one was positive at Day 35 p.c.; this last one aborted around Day 40 p.c. No conceptus was collected. These results indicate that gonial cell nuclei can be partially reprogrammed; they are able to develop into blastocysts and to initiate gestation. However, more experiments will be necessary to prove the nuclear totipotency of bovine gonial cells.


2008 ◽  
Vol 20 (1) ◽  
pp. 169 ◽  
Author(s):  
C. E. McHughes ◽  
G. K. Springer ◽  
L. D. Spate ◽  
R. Li ◽  
R. J. Woods ◽  
...  

Identification of transcripts that are present at key development stages of preimplantation embryos is critical for a better understanding of early embryogenesis. To that end, this project had two goals. The first was to characterize the relative abundance of multiple transcripts during several developmental stages, including metaphase II-stage oocytes (MPII), and 2-cell-stage (2-cell), precompact morula (PCM), and in vitro-produced blastocyst-stage (IVTBL) embryos. The second was to characterize differences in the relative abundance of transcripts present in in vivo- (IVVBL), in vitro-, and nuclear transfer-produced (NTBL) blastocysts. It was our hypothesis that the identification of differentially represented transcripts from these stages would reveal not only developmentally important genes, but also genes that might be aberrantly expressed due to embryo production techniques. Individual clusters from a large bovine EST project (http://genome.rnet.missouri.edu/Bovine/), which focused on female reproductive tissues and embryos, were compared using Fisher's exact test weighted by number of transcripts per tissue by gene (SAS PROC FREQ; SAS Institute, Inc., Cary, NC, USA). Of the 3144 transcripts that were present during embryogenesis, 125 were found to be differentially represented (P < 0.01) in at least one pairwise comparison (Table 1). Some transcripts found to increase in representation from the MPII to the 2-cell stage include protein kinases, PRKACA and CKS1, as well as the metabolism-related gene, PTTG1. These same transcripts were also found to decrease in representation from the 2-cell to the PCM stage. RPL15 (translation) and FTH1 (immune function) were both more highly represented in the PCM than in the 2-cell stage. From PCM to IVTBL, we saw an increase in RPS11, another translation-related transcript. When comparing blastocyst-stage embryos from different production techniques, several transcripts involved in energy production (e.g., COX7B and COX8A) were found to be more highly represented in the NTBL than in the IVTBL. COX8A was also more highly represented in the IVVBL than in the IVTBL. By investigating these differentially represented transcripts, we will be able to better understand the developmental implications of embryo manipulation. We may also be able to better develop reproductive technologies that lead to in vitro- and nuclear transfer-derived embryos which more closely follow a normal program of development. Table 1. Differentially represented transcripts between developmental stages


2011 ◽  
Vol 23 (1) ◽  
pp. 128
Author(s):  
J. Lee ◽  
J. Park ◽  
Y. Chun ◽  
W. Lee ◽  
K. Song

Study for equine somatic cell nuclear transfer (SCNT) is an attractive field for research, but it has not been a major field of study because it is hard to obtain a sufficient number of ovaries and it takes a lot of time and effort for the recovery of oocytes matured in vivo by ovum pickup. It was reported that the bovine cytoplast could support the remodelling of equine donor cells (Zhou et al. 2007 Reprod. Domest. Anim. 42, 243–247). The objectives of this study are 1) to monitor the early events of equine SCNT by interspecies SCNT (isSCNT) between bovine cytoplast and equine donor cell, and 2) to investigate the developmental competence of isSCNT embryos. Bovine oocytes were recovered from the follicles of slaughtered ovaries, and matured in TCM-199 supplemented with 10 mU mL–1 FSH, 50 ng mL–1 EGF, and 10% FBS at 39°C under 5% CO2 in air for 22 h. Fibroblasts derived from bovine or equine skin tissues were synchronized at G0/G1 stage by contact inhibition for 72 h. After IVM, oocytes with polar body were enucleated and electrically fused with equine or bovine skin fibroblasts (1.0 kV cm–1, 20 μs, 2 pulses). Fused couplets were activated with 5 μM ionomycin for 4 min followed by 5 h culture in 10 μg mL–1 cycloheximide (CHX) and/or 2 mM 6-DMAP, and cultured in modified synthetic oviduct fluid (mSOF) at 39°C under 5% CO2, 5% O2, and 90% N2 for 7 days. All analyses were performed using SAS (version 9.1; SAS Institute, Cary, NC, USA). The cleavage rate of isSCNT embryos derived from equine cell was not different (252/323, 78.7%; P = 0.94) from that of SCNT embryos derived from bovine cell (230/297, 79.2%). However, the rate of isSCNT embryos developed to over 8-cell stage was lower (3.3%; P < 0.0001) than that of bovine SCNT embryos (39.4%), and total cell number of isSCNT embryos developed to over 8-cell stage was lower (17.5, n = 12; P < 0.0001) than that (80.8, n = 110) of bovine SCNT embryos. Also, the rate of blastocyst formation of isSCNT embryos (0/323; 0.0%) was lower (P < 0.0001) than that of bovine SCNT embryos (83/297; 29.3%). Meanwhile, reconstructed oocytes for isSCNT were fixed at 8 h after activation to investigate the formation of pseudo-pronucleus (PPN) after post-activation treatment with CHX or CHX+6-DMAP. The ratio of oocytes with single PPN after treatment with CHX+6-DMAP (26/35; 74.3%) was not different (P = 0.63) from that of oocytes treated with CHX (24/36; 68.1%). Although isSCNT embryos derived from bovine cytoplast and equine donor cell could not develop to more than the 16-cell stage, it is believed that the results of this isSCNT study could be used for the preliminary data regarding the reprogramming of donor cell in equine SCNT.


2019 ◽  
Vol 31 (1) ◽  
pp. 134
Author(s):  
D. Veraguas ◽  
C. Aguilera ◽  
D. Echeverry ◽  
D. Saez-Ruiz ◽  
F. O. Castro ◽  
...  

The kodkod is considered a vulnerable species by the International Union for Conservation of Nature. Phylogenetically, the kodkod is classified in the Leopardus genus, which has only 36 chromosome pairs compared with the domestic cat, which has 38. The proposed hypothesis was that domestic cat oocytes are capable of reprogramming somatic cells from kodkod after interspecies somatic cell NT (SCNT), allowing the in vitro embryo development up to blastocyst stage. Five experimental groups were made based on the technology and culture system: (1) cat embryos generated by IVF (IVF), (2) cat embryos generated by SCNT (Ca1x), (3) aggregated cat embryos generated by SCNT (Ca2x), (4) kodkod embryos generated by interspecies SCNT (K1x), and (5) aggregated kodkod embryos generated by interspecies SCNT (K2x). Interspecies SCNT was performed using a zona-free method. Reconstructed embryos were activated by 2 electrical pulses of 140 kV cm−1 for 40 µs and then incubated for 5h in 10μg mL−1 of cycloheximide and 5μg mL−1 of cytochalasin B. Embryos were cultured in SOF media using the well of the well system in a 5% O2, 5% CO2, and 90% N2 atmosphere at 38.5°C for 8 days. The morulae and blastocysts rates were estimated, and diameter of cloned blastocysts was measured. The relative expression of OCT4, SOX2, and NANOG was evaluated in blastocysts by RT-qPCR using the standard curve method; SDHA was used for normalization. The Kruskal-Wallis test was used to evaluate the developmental parameters and gene expression. The t-test was used to evaluate blastocyst diameter. Statistical differences were considered at P&lt;0.05. The number of replicates was IVF=10, Ca1x=8, Ca2x=6, K1x=3, and K2x=8. The morulae rate was lower when clone embryos were cultured individually (IVF=97/153, 63.4%; Ca2x=28/51, 54.9%; K2x=63/110, 57.3%; Ca1x=48/126, 38.1%; K1x=22/87, 25.3%; P&lt;0.05). In the domestic cat, blastocysts rate was higher in IVF (58/153, 37.9%) and Ca2x (28/51, 29.4%) groups than in the Ca1x group (21/126, 16.7%; P&lt;0.05). No blastocysts were generated in the K1x group (0/87), whereas 5.5% of blastocysts were obtained from the K2x (6/110; 5.5%); this was not statistically different compared with the K1x group (P&gt;0.05). No differences were found in blastocyst diameter between the Ca1x (220.4µm) and Ca2x (251.2µm) groups (P&gt;0.05). However, the diameter of the blastocysts from the K2x group (172.8µm) tended to be lower than that of the blastocysts from the Ca2x group (P=0.05). Regarding gene expression, only 1 of the 6 kodkod blastocysts expressed OCT4, and none expressed SOX2 and NANOG. On the other hand, the relative expression of OCT4 tended to decrease in blastocysts from the Ca1x and Ca2x groups compared with the IVF group (P=0.09), but no differences were found in the expression of SOX2 and NANOG among groups (P&gt;0.05). In conclusion, after interspecies SCNT, domestic cat oocytes support the development of kodkod embryos until the morula stage. However, the embryo aggregation did not significantly improve the blastocyst rate and gene expression.


Zygote ◽  
2003 ◽  
Vol 11 (4) ◽  
pp. 317-321 ◽  
Author(s):  
Sangho Roh ◽  
Jitong Guo ◽  
Nakisa Malakooti ◽  
John R. Morrison ◽  
Alan O. Trounson ◽  
...  

We report full-term development of nuclear transfer embryos following nuclear exchange at the 2-cell stage. Nuclei from 2-cell rat embryos were transferred into enucleated 2-cell embryos and developed to term after transfer to recipients (NT2). Pronuclear exchange in zygotes was used for comparison (NT1). Zygotes and 2-cell embryos were harvested from 4-week-old female Sprague-Dawley rats. Nuclear transfer was performed by transferring the pronuclei or karyoplasts into the perivitelline space of recipient embryos followed by electrofusion to reconstruct embryos. Fused couplets were cultured for 4 or 24 h before being transferred into day 1 pseudopregnant recipients (Hooded Wistar) at the 1- or 2-cell stage. In vitro culture was also carried out to check the developmental competence of the embryos. In vitro development to the blastocyst stage was not significantly different between the two groups (NT1, 34.3%; NT2, 45.0%). Two of three recipients from NT1 and two of five recipients from NT2 became pregnant. Six pups (3 from NT1, 3 from NT2) were delivered from the four foster mothers. Three female pups survived; 2 from NT1 and 1 from NT2. At 2 months of age these pups appeared healthy, and were mated with Sprague-Dawley males. One rat derived from NT1 delivered 15 pups (5 males, 10 females) as did the rat from NT2 (7 males, 8 females). Our results show that by using karyoplasts from 2-cell stage embryos as nuclear donors and reconstructing them with enucleated 2-cell embryos, healthy rats can be produced.


2006 ◽  
Vol 18 (2) ◽  
pp. 239
Author(s):  
R. S. Prather ◽  
S. Korte ◽  
R. Woods ◽  
L. Spate ◽  
N. Bivens ◽  
...  

Identification of transcripts produced during bovine embryogenesis is the first step in describing the normal developmental program. To that end, mRNA was isolated from in vitro-matured metaphase II oocytes (MPII), in vitro-produced 2-cell-stage (2-Cell), in vitro-produced precompact morula-stage (PCM), in vitro-produced blastocyst-stage (BL), and in vitro-produced nuclear transfer blastocyst-stage (NTBL) embryos. The mRNA was isolated by using Dynabeads® (Dynal, Inc., Lake Success, NY, USA), and amplified by using the SMART system. PCR products were purified and ligated into pSPORT1 and electroporated into E. coli. Random clones were selected for DNA sequencing. Sequence data were evaluated for quality and clustered by sequence similarity with sequences generated from a larger expressed sequence tag (EST) project (http://genome.rnet.missouri.edu/Bovine/) by using the tlcluster program from the University of Iowa. Sequences over 100 bp in length with average Phred scores of over 20 for the entire sequence were submitted to GenBank (NIH genetic sequence database). Sequences were compared to the bovine TIGR (The Institute for Genomic Research) and human databases to gather annotation. The best comparison is listed below by using the HUGO Gene Nomenclature Committee standards (http://www.gene.ucl.ac.uk/nomenclature/) when possible. The number of unique clusters, i.e. no match in GenBank, was 53, 120, 109, 115, and 135, for MPII, 2-Cell, PCM, BL, and NTBL, respectively. The total number of clusters per tissue ranged from 224 to 992. The percent of clusters (number of clusters per total number of ESTs) per library was 12% (224/1762), 42% (746/1771), 48% (819/1715), 49% (900/1818) and 53% (992/1876) for MPII, 2-Cell, PCM, BL, and NTBL, respectively. Either the quality of the MPII library was lower or the complexity of the MPII mRNA was less than mRNA in the other tissues. Examples of mRNA that were in different abundance are shown in Table 1. Clearly, as in other species, there are significant changes in mRNA abundance during early embryogenesis. Furthermore, NTBL embryos, even though they are morphologically similar to BL, possess a population of mRNA that is distinct from that in BL. Table 1. Comparison of mRNA Abundance During Bovine Embryogenesis This work was funded by the USDA NRI 2003–35205–12812 and Food for the 21st Century.


2019 ◽  
Vol 31 (1) ◽  
pp. 148
Author(s):  
Y. H. Zhai ◽  
X. L. An ◽  
Z. R. Zhang ◽  
S. Zhang ◽  
Z. Y. Li

During fertilization, the parental genome undergoes extensive demethylation. Global DNA demethylation is a hallmark of epigenetic reprogramming. Embryos engage non-canonical DNA methylation maintenance mechanisms to ensure inheritance of exceptional germline features. However, the mechanisms ensuring demethylation resistance in light of global reprogramming remain poorly understood. TRIM28 is a maternal-effect factor that controls genomic imprinting during early embryonic reprogramming. In this study, cytoplasmic injections of siRNA were performed into oocytes matured in vitro for 26h to interfere with the expression of TRIM28 in oocytes. The injected oocytes were continually matured in vitro until 42h and used to construct somatic cell nuclear transfer (SCNT) embryos. During 2-cell to blastocyst stages, the expression of development-related genes (NANOG, POU5F1, CDX2, BAX, and BCL2), maternal imprinting genes (IGF2, DIO3, PLAGL1, and DLK1), paternal imprinting genes (H19 and PEG3), TRIM28-recruitment complex-associated genes (ZFP57, PGC7, SETDB1, and DNMT), and epigenetic chromatin modification enzymes were detected by quantitative PCR in the constructed TRIM28-interfered SCNT embryos. The DNA methylation levels in the promoter regions of the imprinted genes (H19 and IGF2) and chromatin repeats (PRE-1 and SATELLITE) were analysed by sodium bisulfite genomic sequencing. The results showed that the TRIM28-interfered SCNT embryos had significantly lower cleavage and blastocyst rates (53.9±3.4% and 12.1±4.3%, respectively) than those in control SCNT embryos (64.8±2.7% and 18.8±1.9%, respectively). The expression levels of development-related genes (NANOG and POU5F1) and TRIM28-recruited transcriptional repression complex-associated genes (PGC7, ZFP57, and DNMT1) in the 4-cell stage were significantly reduced (P&lt;0.05). The imprinted genes were significantly up-regulated (P&lt;0.05) from the 2-cell to blastocyst stage in constructed TRIM28-interfered SCNT embryos, except H19 at the 2-cell and blastocyst stage decreased remarkably (P&lt;0.05). The DNA methylation levels of IGF2 decreased 2-fold from the 2-cell to blastocyst stage in TRIM28-interfered SCNT embryos. The PRE-1 and SATELLITE had a remarkably lower (P&lt;0.05) methylation levels in the TRIM28-interfered 2-cell embryos than in control SCNT embryos. The cluster analysis showed some of the chromatin modification enzymes had abnormal expression in the TRIM28-interfered SCNT embryos, especially in the 8-cell stage, where 48 enzymes were significantly decreased (P&lt;0.05). The down-regulation enzymes were mainly clustered in the histone H3K4 methyl transferase and histone acetylase. These results indicate that down-regulation of maternal TRIM28 breaks the steady-state of genomic methylation at a particular locus of the imprinted gene, disrupts the expression of imprinted gene and epigenetic modifications enzymes, and is detrimental to normal development of SCNT embryos. Maternal TRIM28 is needed in maintaining a stable state of genomic methylation and epigenetic modification state during SCNT embryo development.


Zygote ◽  
2014 ◽  
Vol 23 (4) ◽  
pp. 494-500 ◽  
Author(s):  
Hironobu Sugimoto ◽  
Yuta Kida ◽  
Noriyoshi Oh ◽  
Kensaku Kitada ◽  
Kazuya Matsumoto ◽  
...  

SummaryWe examined growing oocytes collected from follicles remaining in superovulated rabbit ovaries, that were grown (in vitro growth, IVG) and matured (in vitro maturation, IVM) in vitro. We produced somatic cell nuclear transfer (SCNT) embryos using the mature oocytes and examined whether these embryos have the ability to develop to the blastocyst stage. In addition, we examined the effects of trichostatin A (TSA), a histone deacetylase inhibitor (HDACi), on the developmental competence of SCNT embryos derived from IVG–IVM oocytes. After growth for 7 days and maturation for 14–16 h in vitro, the growing oocytes reached the metaphase II stage (51.4%). After SCNT, these reconstructed embryos reached the blastocyst stage (20%). Furthermore, the rate of development to the blastocyst stage and the number of cells in the blastocysts in SCNT embryos derived from IVG–IVM oocytes were significantly higher for TSA-treated embryos compared with TSA-untreated embryos (40.6 versus 21.4% and 353.1 ± 59.1 versus 202.5 ± 54.6, P < 0.05). These results indicate that rabbit SCNT embryos using IVG–IVM oocytes have the developmental competence to reach the blastocyst stage.


Zygote ◽  
2014 ◽  
Vol 24 (1) ◽  
pp. 31-41 ◽  
Author(s):  
Yong-Xun Jin ◽  
Zhong Zheng ◽  
Xian-Feng Yu ◽  
Jia-Bao Zhang ◽  
Suk Namgoong ◽  
...  

SummaryThe mitochondrial genome is maternally inherited in animals, despite the fact that paternal mitochondria enter oocytes during fertilization. Autophagy and ubiquitin-mediated degradation are responsible for the elimination of paternal mitochondria in Caenorhabditis elegans; however, the involvement of these two processes in the degradation of paternal mitochondria in mammals is not well understood. We investigated the localization patterns of light chain 3 (LC3) and ubiquitin in mouse and porcine embryos during preimplantation development. We found that LC3 and ubiquitin localized to the spermatozoon midpiece at 3 h post-fertilization, and that both proteins were colocalized with paternal mitochondria and removed upon fertilization during the 4-cell stage in mouse and the zygote stage in porcine embryos. Sporadic paternal mitochondria were present beyond the morula stage in the mouse, and paternal mitochondria were restricted to one blastomere of 4-cell embryos. An autophagy inhibitor, 3-methyladenine (3-MA), did not affect the distribution of paternal mitochondria compared with the positive control, while an autophagy inducer, rapamycin, accelerated the removal of paternal mitochondria compared with the control. After the intracytoplasmic injection of intact spermatozoon into mouse oocytes, LC3 and ubiquitin localized to the spermatozoon midpiece, but remnants of undegraded paternal mitochondria were retained until the blastocyst stage. Our results show that paternal mitochondria colocalize with autophagy receptors and ubiquitin and are removed after in vitro fertilization, but some remnants of sperm mitochondrial sheath may persist up to morula stage after intracytoplasmic spermatozoon injection (ICSI).


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