Fenghua Lu

Buffalos (Bubalus bubalis) Cloned by Nuclear Transfer of Somatic Cells

Abstract Cloning of buffalos (Bubalus bubalis) through nuclear transfer is a potential alternative approach in genetic improvement of buffalos. However, to our knowledge, cloned offspring of buffalos derived from embryonic, fetal, or somatic cells have not yet been reported. Thus, factors affecting the nuclear transfer of buffalo somatic cells were examined, and the possibility of cloning buffalos was explored in the present study. Treatment of buffalo fibroblasts and granulosa cells with aphidicolin plus serum starvation resulted in more cells being arrested at the G0/G1 phase, the proportion of cells with DNA fragmentation being less, and the number of embryos derived from these cells that developed to blastocysts being greater. In addition, a difference was found in the development of embryos reconstructed with fetal fibroblasts from different individuals (P < 0.001). Forty-two blastocysts derived from granulosa cells and fetal fibroblasts were transferred into 21 recipient swamp buffalos, and 4 recipients were confirmed to be pregnant by rectal palpation on Day 60 of gestation. One recipient received two embryos from fetal fibroblasts aborted on Day 300 of gestation and delivered two female premature calves. Three recipients maintained pregnancy to term and delivered three female cloned calves after Days 338–349 of gestation. These results indicate that buffalo embryos derived from either fetal fibroblasts or granulosa cells can develop to the term of gestation and result in newborn calves.

Generation of induced pluripotent stem cells from buffalo (Bubalus bubalis) fetal fibroblasts with buffalo defined factors.

Ectopically, expression of defined factors could reprogram mammalian somatic cells into induced pluripotent stem cells (iPSCs), which initiates a new strategy to obtain pluripotent stem cell lines. Attempts have been made to generate buffalo pluripotent stem cells by culturing primary germ cells or inner cell mass, but the efficiency is extremely low. Here, we report a successful method to reprogram buffalo fetal fibroblasts (BFFs) into pluripotent stem cells [buffalo induced pluripotent stem cell (biPSCs)] by transduction of buffalo defined factors (Oct4, Sox2, Klf4, and c-Myc) using retroviral vectors. The established biPSCs displayed typical morphological characteristics of pluripotent stem cells, normal karyotype, positive staining of alkaline phosphatase, and expressed pluripotent markers including Oct4, Sox2, Nanog, Lin28, E-Cadherin, SSEA-1, SSEA-4, TRA-1-81, STAT3, and FOXD3. They could form embryoid bodies (EBs) in vitro and teratomas after injecting into the nude BALB/C mice, and 3 germ layers were identified in the EBs and teratomas. Methylation assay revealed that the promoters of Oct4 and Nanog were hypomethylated in biPSCs compared with BFFs and pre-biPSCs, while the promoters of Sox2 and E-Cadherin were hypomethylated in both BFFs and biPSCs. Further, inhibiting p53 expression by coexpression of SV40 large T antigen and buffalo defined factors in BFFs or treating BFFs with p53 inhibitor pifithrin-a (PFT) could increase the efficiency of biPSCs generation up to 3-fold, and nuclear transfer embryos reconstructed with biPSCs could develop to blastocysts. These results indicate that BFFs can be reprogrammed into biPSCs by buffalo defined factors, and the generation efficiency of biPSCs can be increased by inhibition of p53 expression. These efforts will provide a feasible approach for investigating buffalo stem cell signal pathways, establishing buffalo stem cell lines, and producing genetic modification buffaloes in the future.

Immunisation against inhibin enhances follicular development, oocyte maturation and superovulatory response in water buffaloes

This study was carried out to test the feasibility of enhancing embryo production in vivo and in vitro by immunoneutralisation against inhibin or follistatin. In Experiment 1, multi-parity buffaloes were assigned into three groups: High group (n=8), which received one primary (2mg) and two booster (1mg) vaccinations (28-day intervals) with a recombinant inhibin α subunit in 1 mL of white oil adjuvant; Low group (n=8), which received half that dose; and Control group (n=7), which received only adjuvant. Immunisation against inhibin stimulated development of ovarian follicles. Following superovulation and artificial insemination, inhibin-immunised buffaloes had more developing follicles than the Control buffaloes. The average number of embryos and unfertilised ova (4.5±0.6, n=6) in the High group was higher (P<0.05) than in the Control group (2.8±0.6, n=5) and was intermediate (4.1±0.7, n=7) in the Low group. The pooled number of transferable embryos of the High and Low groups (3.2±0.5, n=13) was also higher (P<0.05) than that (1.6±0.7, n=5) of the controls. The immunised groups also had higher plasma concentrations of activin, oestradiol and progesterone. In Experiment 2, the addition of anti-inhibin or anti-follistatin antibodies into buffalo oocyte IVM maturation medium significantly improved oocyte maturation and cleavage rates following parthenogenic activation. Treatment with anti-follistatin antibody also doubled the blastocyst yield from activated embryos. These results demonstrated that immunisation against inhibin stimulated follicular development, enhanced oocyte quality and maturation competence, yielded more and better embryos both in vivo and in vitro.

Treatment of donor cells with trichostatin A improves in vitro development and reprogramming of buffalo (Bubalus bubalis) nucleus transfer embryos.

It has been reported that buffalo (Bubalus bubalis) embryos reconstructed by somatic cell nucleus transfer (SCNT) can develop to the full term of gestation and result in newborn calves. However, the developmental competence of reconstructed embryos is still low. Recently, it has been reported that treating donor cells or embryos with trichostatin A (TSA) can increase the cloning efficiency in some species. Thus, the present study was undertaken to improve the development of buffalo SCNT embryos by treatment of donor cells (buffalo fetal fibroblasts) with TSA and explore the relation between histone acetylation status of donor cells and developmental competence of SCNT embryos. Treatment of donor cells with either 0.15 or 0.3 μM TSA for 48 hours resulted in a significant increase in the cleavage rate and blastocyst yield of SCNT embryos (P < 0.05). Meanwhile, the expression level of HDAC1 in donor cells was also decreased (0.4-0.6 fold, P < 0.05) by TSA treatment, although the expression level of HAT1 was not affected. Further measurement of the epigenetic maker AcH4K8 in buffalo IVF and SCNT embryos at the eight-cell stage revealed that the spatial distribution of acH4K8 staining in SCNT embryos was different from the IVF embryos. Treatment of donor cells with TSA resulted in an increase in the AcH4K8 level of SCNT embryos and similar to fertilized counterparts. These results suggest that treatment of donor cells with TSA can facilitate their nucleus reprogramming by affecting the acetylated status of H4K8 and improving the in vitro development of buffalo SCNT embryos. The AcH4K8 status at the eight-cell stage can be used as an epigenetic marker for predicting the SCNT efficiency in buffalos.

DGAT1, GH, GHR, PRL and PRLR polymorphism in water buffalo (Bubalus bubalis).

The polymorphism of several genes has been shown to affect the milk composition traits in dairy cattle, including DGAT1-exon8 K232A, GH-intron3 MspI, GH-exon5 AluI, GHR-exon8 F279Y, PRL-exon3 RsaI and PRLR-exon3 S18N. However, the polymorphism and effects of these genes on the milk traits of water buffalo are still unclear. In this study, four DNA pooling samples from Murrah, Nili-ravi, Murrah-Nili-Swamp crossbreed and Chinese swamp buffalo were constructed, respectively, and polymorphism of these sites was investigated using PCR-Single-strand conformation polymorphism and sequencing. Twenty-eight inter-specific single-nucleotide polymorphism (SNPs) were found in these six assayed gene fragments between buffalo and dairy cattle, including nine intra-specific SNPs among buffalo groups. All buffalo fixed a K allele genotype in DGAT1-exon8, MspI(+) restriction site(c nucleotide) and AluI(+) site(c nucleotide) at intron3 and exon5 of GH gene, F allele genotype of F279Y mutation in GHR gene, RsaI(-) restriction site at PRL-exon3/exon4 and N allele genotype of S18N mutation at PRLR-exon3. It provides an indirect evidence that water buffalo have fixed alleles with genotypes reported in dairy cattle, which is thought to be responsible for high milk fat, high protein content and low milk yield. Moreover, three new intra-specific SNPs were found including 275th bp (c/t) in DGAT1 of Murrah buffalo, 109th bp (t/a) in PRL-exon3/exon4 and 43rd bp (c/t) in PRLR-exon3 of Chinese swamp buffalo. Information provided in this study will be useful in further studies to improve buffalo breeding for better lactation performances.

Generation of buffalo (Bubalus bubalis) transgenic chimeric and nuclear transfer embryos using embryonic germ-like cells expressing enhanced green fluorescent protein.

The possibility of producing transgenic buffalo embryos by chimera and nuclear transfer (NT) using buffalo embryonic germ (EG)-like cells expressing enhanced green fluorescent protein (EGFP) has been explored in this study. Buffalo EG-like cells and fibroblasts with two to eight passages were transfected with the lined plasmid (pCE-EGFP-IRES-Neo-dNdB) using Lipofectamine 2000 and selected by culturing in 200 microg/ml G418 for 6-8 days. G418 resistant fibroblasts and EG-like cells were used for embryo chimera and NT. To produce blastocysts by chimera, 8-16 cells embryos were injected with EG-like and fibroblast cells. Then, to produce blastocysts by NT, in vitro maturated oocytes were enucleated and afterwards EG-like/fibroblast cells transferred into the perivitelline space. No statistical differences were observed for the total blastocyst produced by the chimeric method, using EG-like and fibroblasts as donor cells, resulting on an accomplishment of 35.6% vs 33.3%, respectively. Nevertheless, besides from the 37 blastocysts produced, 23 (62.2%) from EG-like cells expressed EGFP, none of blastocysts from foetal fibroblasts expressed this protein. When the NT method was used, no statistical difference among different generations was observed in the percentage of oocytes fused, cleaved, and developed to blastocysts after NT for EG-like cells. On average, the percentage of oocytes fused, cleaved, and developed to blastocysts after NT was respectively 81.8%, 67.7% and 10.7%. For the expression of EGFP, from the 12 blastocysts produced by NT, 7 of them were positive, while none of NT embryos from EGFP positive fibroblasts developed to blastocysts. Results of the present study clearly demonstrated that gene transfected buffalo EG-like cells have the ability to form chimeric embryos after injecting into buffalo early embryos and reprogramming ability after NT, which can be employed to produce transgenic buffalos through either embryo chimera or NT.

Comparative Proteomic Analysis of Buffalo Oocytes Matured in vitro Using iTRAQ Technique

To investigate the protein profiling of buffalo oocytes at the germinal vesicle (GV) stage and metaphase II (MII) stage, an iTRAQ-based strategy was applied. A total of 3,763 proteins were identified, which representing the largest buffalo oocytes proteome dataset to date. Among these proteins identified, 173 proteins were differentially expressed in GV oocytes and competent MII oocytes, and 146 proteins were differentially abundant in competent and incompetent matured oocytes. Functional and KEGG pathway analysis revealed that the up-regulated proteins in competent MII oocytes were related to chromosome segregation, microtubule-based process, protein transport, oxidation reduction, ribosome, and oxidative phosphorylation, etc., in comparison with GV and incompetent MII oocytes. This is the first proteomic report on buffalo oocytes from different maturation stages and developmental competent status. These data will provide valuable information for understanding the molecular mechanism underlying buffalo oocyte maturation, and these proteins may potentially act as markers to predict developmental competence of buffalo oocyte during in vitro maturation.

Effects of Scriptaid on the Histone Acetylation, DNA Methylation and Development of Buffalo Somatic Cell Nuclear Transfer Embryos

The present study was undertaken to examine the effect of Scriptaid treatment on histone acetylation, DNA methylation, expression of genes related to histone acetylation, and development of buffalo somatic cell nuclear transfer (SCNT) embryos. Treatment of buffalo SCNT embryos with 500 nM Scriptaid for 24 h resulted in a significant increase in the blastocyst formation rate (28.2% vs. 13.6%, p<0.05). Meanwhile, treatment of buffalo SCNT embryos with Scriptaid also resulted in higher acetylation levels of H3K18 and lower methylation levels of global DNA at the blastocyst stage, which was similar to fertilized counterparts. The expression levels of CBP, p300, HAT1, Dnmt1, and Dnmt3a in SCNT embryos treated with Scriptaid were significantly lower than the control group at the eight-cell stage (p<0.05), but the expression of HAT1 and Dnmt1a was higher than the control group at the blastocyst stage (p<0.05). When 96 blastocysts developed from Scriptaid-treated SCNT embryos were transferred into 48 recipients, 11 recipients (22.9%) became pregnant, whereas only one recipient (11.1%) became pregnant following transfer of 18 blastocysts developed from untreated SCNT embryos into nine recipients. These results indicate that treatment of buffalo SCNT embryos with Scriptaid can improve their developmental competence, and this action is mediated by resulting in a similar histone acetylation level and global DNA methylation level compared to in vitro-fertilized embryos through regulating the expression pattern of genes related to histone acetylation and DNA methylation.

Effects of recipient oocyte age and interval from fusion to activation on development of buffalo (Bubalus bubalis) nuclear transfer embryos derived from fetal fibroblasts.

The objective was to investigate the effect of recipient oocyte age and the interval from activation to fusion on developmental competence of buffalo nuclear transfer (NT) embryos. Buffalo oocytes matured in vitro for 22 h were enucleated by micromanipulation under the spindle view system, and a fetal fibroblast (pretreated with 0.1 μg/mL aphidicolin for 24 h, followed by culture for 48 h in 0.5% fetal bovine serum) was introduced into the enucleated oocyte, followed by electrofusion. Both oocytes and NT embryos were activated by exposure to 5 μM ionomycin for 5 min, followed by culture in 2 mM 6-dimethyl-aminopurine for 3 h. When oocytes matured in vitro for 28, 29, 30, 31, or 32 h were activated, more oocytes matured in vitro for 30 h developed into blastocysts in comparison with oocytes matured in vitro for 32 h (31.3 vs 19.9%, P < 0.05). When electrofusion was induced 27 h after the onset of oocyte maturation, the cleavage rate (78.0%) was higher than that of electrofusion induced at 28 h (67.2%, P < 0.05), and the blastocyst yield (18.1%) was higher (P < 0.05) than that of electrofusion induced at 25 or 26 h (7.4 and 8.5%, respectively). A higher proportion of NT embryos activated at 3 h after electrofusion developed to the blastocyst stage (18.6%) in comparison with NT embryos activated at 1 h (6.0%), 2 h (8.3%), or 4 h (10.6%) after fusion (P < 0.05). No recipient was pregnant 60 d after transfer of blastocysts developed from NT embryos activated at 1 h (0/8), 2 h (0/10), or 4 h (0/9) after fusion. However, 3 of 16 recipients were pregnant following transfer of blastocysts developed from the NT embryos activated at 3 h after fusion, and two of these recipients maintained pregnancy to term. We concluded that the developmental potential of buffalo NT embryos was related to recipient oocyte age and the interval from fusion to activation.

Effects of scriptaid on the histone acetylation of buffalo oocytes and their ability to support the development of somatic cell nuclear transfer embryos

The present study was undertaken to investigate the effect of scriptaid treatment on histone H3 on lysine 18 (H3K18) acetylation and relative expression levels of genes related to histone acetylation (HAT1, CBP, and p300) in buffalo oocytes during IVM. Meanwhile, the embryonic developmental ability of buffalo oocytes after SCNT was also examined. The H3K18 acetylation in oocytes increased from the germinal vesicle (GV) stage to the GV breakdown (GVBD) stage and arrived at a high acetylation level at the GVBD stage. Then, the H3K18 deacetylated completely at the metaphase I (MI) and acetylated again at the MII stage. However, addition of 500-nM scriptaid to the maturation medium resulted in a significant increase in the H3K18 acetylation at the MI stage. The expression profiles of genes related to histone acetylation (HAT1, CBP, and p300) in the meiosis stages of oocytes matured in the medium supplemented with 500-nM scriptaid were significantly higher than those of the oocytes matured in the medium without scriptaid (P < 0.05) with the exception of p300 at the GVBD stage. More SCNT embryos reconstructed with oocytes matured in the medium supplemented with 500-nM scriptaid developed to blastocysts (23.1%) in comparison with oocytes matured in the medium without scriptaid (13.8%, P < 0.05). These results indicate that scriptaid can increase the histone acetylation of buffalo oocytes during meiotic maturation and improve their ability to support the development of SCNT embryos.