Browse > Article

Factors Affecting the Efficiency of Animal Cloning by Somatic Cell Nuclear Transfer  

Kim, Min-Goo (Department of Agricultural Biotechnology, Animal Biotechnology Major, and Research Institute for Agriculture and Life Sciences, Seoul National University)
Park, Chi-Hun (Department of Agricultural Biotechnology, Animal Biotechnology Major, and Research Institute for Agriculture and Life Sciences, Seoul National University)
Lee, Sang-Goo (Department of Agricultural Biotechnology, Animal Biotechnology Major, and Research Institute for Agriculture and Life Sciences, Seoul National University)
Seo, Hee-Won (Department of Biological Resources and Technology, and Institute of Biomaterials, Yonsei University)
Choi, Yo-Han (Department of Biological Resources and Technology, and Institute of Biomaterials, Yonsei University)
Lee, Chang-Kyu (Department of Agricultural Biotechnology, Animal Biotechnology Major, and Research Institute for Agriculture and Life Sciences, Seoul National University)
Ka, Hak-Hyun (Department of Biological Resources and Technology, and Institute of Biomaterials, Yonsei University)
Publication Information
Journal of Embryo Transfer / v.23, no.2, 2008 , pp. 67-76 More about this Journal
Abstract
Since the birth of Dolly using fully differentiated somatic cells as a nuclear donor, viable clones were generated successfully in many mammalian species. These achievements in animal cloning demonstrate developmental potential of terminally differentiated somatic cells. At the same time, the somatic cell nuclear transfer (SCNT) technique provides the opportunities to study basic and applied biosciences. However, the efficiency generating viable offsprings by SCNT remains extremely low. There are several explanations why cloned embryos cannot fully develop into viable animals and what factors affect developmental potency of reconstructed embryos by the SCNT technique. The most critical and persuasive explanation for inefficiency in SCNT cloning is incomplete genomic reprogramming, such as DNA methylation and histone modification. Numerous studies on genomic reprogramming demonstrated that incorrect DNA methylation and aberrant epigenetic reprogramming are considerably correlated with abnormal development of SCNT cloned embryos even though its mechanism is not fully understood. The SCNT technique is useful in cloning farm animals because pluripotent stem cells are not established in farm animal species. Therapeutic cloning combined with genetic manipulation will help to control various human diseases. Also, the SCNT technique provides a chance to overcome excessive demand for the organs by production of transgenic animals as xenotransplantation resources. Here, we describe the factors affecting the efficiency of generating cloned farm animals by the SCNT technique and discuss future directions of animal cloning by SCNT to improve the cloning efficiency.
Keywords
animal; cloning; somatic cell nuclear transfer; DNA methylation; epigenetic reprogramming;
Citations & Related Records
연도 인용수 순위
  • Reference
1 Kang YK, Koo DB, Park JS, Choi YH, Kim HN, Chang WK, Lee KK and Han YM. 2001b. Typical demethylation events in cloned pig embryos. Clues on speciesspecific differences in epigenetic reprogramming of a cloned donor genome. J. Biol. Chem. 276:39980-39984   DOI   ScienceOn
2 Kang YK, Park JS, Koo DB, Choi YH, Kim SU, Lee KK and Han YM. 2002. Limited demethylation leaves mosaic-type methylation states in cloned bovine pre-implantation embryos. EMBO. J. 21:1092-1100   DOI   ScienceOn
3 Steinhardt RA and Epel D. 1974. Activation of sea-urchin eggs by a calcium ionophore. Proc. Natl. Acad. Sci. U.S.A. 71:1915-1919
4 Van der Auwera I and D'Hooghe T. 2001. Superovulation of female mice delays embryonic and fetal development. Hum. Reprod. 16:1237-1243   DOI   ScienceOn
5 Wakayama T, Perry AC, Zuccotti M, Johnson KR and Yanagimachi R. 1998. Full-term development of mice from enucleated oocytes injected with cumulus cell nuclei. Nature 394:369-374   DOI   ScienceOn
6 Walker SK, Hartwich KM, Robinson JS, Seamark RF. Influence of in vitro culture of embryos on the normality of development. In: Lauria, A., Gandolfi, F., Enne, G., Gianaroli, L. (Eds.). 1998. Gemetes: Development and Function. Serono Symposia, Italy, pp. 457-484
7 Wang MK, Liu JL, Li GP, Lian L and Chen DY. 2001. Sucrose pretreatment for enucleation: an efficient and non-damage method for removing the spindle of the mouse MII oocyte. Mol. Reprod. Dev. 58:432-436   DOI   ScienceOn
8 Wilmut I, Schnieke AE, McWhir J, Kind AJ and Campbell KHS. 1997. Viable offspring derived from fetal and adult mammalian cells. Nature 385:810-813   DOI   ScienceOn
9 Bestor TH. 2000. The DNA methyltransferases of mammals. Hum. Mol. Genet. 9:2395-2402   DOI   ScienceOn
10 Bestor TH. 1992. Activation of mammalian DNA methyltransferase by cleavage of a Zn binding regulatory domain. EMBO. J. 11:2611-2617   PUBMED
11 Betthauser J, Forsberg E, Augenstein M, Childs L, Eilertsen K, Enos J, Forsythe T, Golueke P, Jurgella G, Koppang R, Lesmeister T, Mallon K, Mell G, Misica P, Pace M, Pfister- Genskow M, Strelchenko N, Voelker G, Watt S, Thompson S and Bishop M. 2000. Production of cloned pigs from in vitro systems. Nat. Biotechnol. 18:1055-1059   DOI   ScienceOn
12 Dean W, Santos F, Stojkovic M, Zakhartchenko V, Walter J, Wolf E and Reik W. 2001. Conservation of methylation reprogramming in mammalian development: aberrant reprogramming in cloned embryos. Proc. Natl. Acad. Sci. U.S.A. 98:13734-13738
13 Fulka J Jr and Moor RM. 1993. Noninvasive chemical enucleation of mouse oocytes. Mol. Reprod. Dev. 34:427-430   DOI   ScienceOn
14 Hansis C, Barreto G, Maltry N and Niehrs C. 2004. Nuclear reprogramming of human somatic cells by xenopus egg extract requires BRG1. Curr. Biol. 14:1475-1480   DOI   ScienceOn
15 Hill JR, Burghardt RC, Jones K, Long CR, Looney CR, Shin T, Spencer TE, Thompson JA, Winger QA and Westhusin ME. 2000. Evidence for placental abnormality as the major cause of mortality in first-trimester somatic cell cloned bovine fetuses. Biol. Reprod. 63:1787-1794   DOI   ScienceOn
16 Ka H, Seo H, Kim M, Moon S, Kim H and Lee CK. 2007. Gene expression profiling of the uterus with embryos cloned by somatic cell nuclear transfer on day 30 of pregnancy. Anim. Reprod. Sci. doi:10.1016/j.anireprosci.2007.07.008
17 Hill JR, Roussel AJ, Cibelli JB, Edwards JF, Hooper NL, Miller MW, Thompson JA, Looney CR, Westhusin ME, Robl JM and Stice SL. 1999. Clinical and pathologic features of cloned transgenic calves and fetuses (13 case studies). Theriogenology 51:1451-1465   DOI   ScienceOn
18 Hochedlinger K and Jaenisch R. 2002. Monoclonal mice generated by nuclear transfer from mature B and T donor cells. Nature 415:1035-1038   DOI   ScienceOn
19 Hussein TS, Thompson JG and Gilchrist RB. 2006. Oocyte-secreted factors enhance oocyte developmental competence. Dev. Biol. 296:514-521   DOI   ScienceOn
20 Kim M, Seo H, Choi Y, Hwang W, Lee CK and Ka H. 2008. Aberrant expression of retinol-binding protein, osteopontin and fibroblast growth factor 7 in the porcine uterine endometrium of pregnant recipients carrying embryos produced by somatic cell nuclear transfer. Anim. Reprod. Sci. doi: 10.1016/j.anireprosci.2008.04.029
21 Loi P, Ptak G, Barboni B, Fulka J Jr, Cappai P and Clinton M. 2001. Genetic rescue of an endangered mammal by crossspecies nuclear transfer using post-mortem somatic cells. Nat. Biotechnol. 19:962-964   DOI   ScienceOn
22 Machaty Z, Day BN and Prather RS. 1998. Development of early porcine embryos in vitro and in vivo. Biol. Reprod. 59:451-455   DOI   ScienceOn
23 Matsuyama K, Miyakoshi H and Fukui Y. 1993. Effect of glucose levels during the in vitro culture in synthetic oviduct fluid medium on in vitro development of bovine oocytes matured and fertilized in vitro. Theriogenology 40: 595-605   DOI   ScienceOn
24 Presicce GA and Yang X. 1994. Parthenogenetic development of bovine oocytes matured in vitro for 24 hr and activated by ethanol and cycloheximide. Mol. Reprod. Dev. 38:380-385   DOI   ScienceOn
25 Park IH, Zhao R, West JA, Yabuuchi A, Huo H, Ince TA, Lerou PH, Lensch MW and Daley GQ. 2008. Reprogramming of human somatic cells to pluripotency with defined factors. Nature 451:141-146   DOI   ScienceOn
26 Polejaeva IA, Chen SH, Vaught TD, Page RL, Mullins J, Ball S, Dai Y, Boone J, Walker S, Ayares DL, Colman A and Campbell KHS. 2000. Cloned pigs produced by nuclear transfer from adult somatic cells. Nature 407:86-90   DOI   ScienceOn
27 Prather RS, Sims MM and First NL. 1989. Nuclear transplantation in early pig embryos. Biol. Reprod. 41:414-418   DOI   ScienceOn
28 Ravelich SR, Shelling AN, Wells DN, Peterson AJ, Lee RS, Ramachandran A and Keelan JA. 2006. Expression of TGFbeta1, TGF-beta2, TGF-beta3 and the receptors TGF-betaRI and TGF-betaRII in placentomes of artificially inseminated and nuclear transfer derived bovine pregnancies. Placenta 27:307-316   DOI   ScienceOn
29 Ribas R, Oback B, Ritchie W, Chebotareva T, Taylor J, Maurício AC, Sousa M and Wilmut I. 2006. Modifications to improve the efficiency of zona-free mouse nuclear transfer. Cloning Stem Cells 8:10-15   DOI   ScienceOn
30 Santos F, Hendrich B, Reik W and Dean W. 2002. Dynamic reprogramming of DNA methylation in the early mouse embryo. Dev. Biol. 241:172-182   DOI   ScienceOn
31 Sinclair KD, Maxfield EK, Robinson JJ, Maltin CA, McEvoy TG, Dunne LD, Young LE and Broadbent PJ. 1997. Culture of sheep zygotes can alter fetal growth and development. Theriogenology 47:380   DOI   ScienceOn
32 Yang X, Presicce GA, Moraghan L, Jiang S and Foote RH. 1994. Synergistic effect of ethanol and cycloheximide on activation of freshly matured bovine oocytes. Theriogenology 41:395-403   DOI   ScienceOn
33 Mann MR, Chung YG, Nolen LD, Verona RI, Latham KE and Bartolomei MS. 2003. Disruption of imprinted gene methylation and expression in cloned preimplantation stage mouse embryos. Biol. Reprod. 69:902-914   DOI   ScienceOn
34 Sanford JP, Clark HJ, Chapman VM and Rossant J. 1987. Differences in DNA methylation during oogenesis and spermatogenesis and their persistence during early embryogenesis in the mouse. Genes. Dev. 1:1039-1046   DOI
35 Shi W and Haaf T. 2002. Aberrant methylation patterns at the two-cell stage as an indicator of early developmental failure. Mol. Reprod. Dev. 63:329-334   DOI   ScienceOn
36 Zimmermann U and Vienken J. 1982. Electric field-induced cell-to-cell fusion. J. Membr. Biol. 67:165-182   DOI
37 Jones KT, Carroll J and Whittingham DG. 1995. Ionomycin, thapsigargin, ryanodine, and sperm induced $Ca^{2+}$ release increase during meiotic maturation of mouse oocytes. J. Biol. Chem. 270:6671-6677   DOI   ScienceOn
38 Reik W, Dean W and Walter J. 2001. Epigenetic reprogramming in mammalian development. Science 293:1089-1093   DOI   ScienceOn
39 Rhee I, Jair KW, Yen RW, Lengauer C, Herman JG, Kinzler KW, Vogelstein B, Baylin SB and Schuebel KE. 20000. CpG methylation is maintained in human cancer cells lacking DNMT1. Nature 404:1003-1007   DOI   ScienceOn
40 Gurdon JB. 1962. Adult frogs derived from the nuclei of single somatic cells. Dev. Biol. 4: 256-273   DOI   ScienceOn
41 Oback B and Wells DN. 2007. Donor cell differentiation, reprogramming, and cloning efficiency: Elusive or illusive correlation? Mol. Reprod. Dev. 74:646-654   DOI   ScienceOn
42 Barnes FL, Crombie A, Gardner DK, Kausche A, Lacham-Kaplan O, Suikkari AM, Tiglias J, Wood C and Trounson A. 1995. Blastocyst development and birth after in vitro maturation of human primary oocytes, intracytoplasmatic injection and assisted hatching. Hum. Reprod. 10:3243-3247   DOI   PUBMED
43 Im GS, Lai L, Liu Z, Hao Y, Wax D, Bonk A and Prather RS. 2004. In vitro development of preimplantation porcine nuclear transfer embryos cultured in different media and gas atmospheres. Theriogenology 61:1125-1135   DOI   ScienceOn
44 Lanza RP, Cibelli JB, Moraes CT, Farin PW, Farin CE, Hammer CJ, West MD and Damiani P. 2000. Cloning of an endangered species (Bos gaurus) using interspecies nuclear transfer. Cloning 2:79-90   DOI   ScienceOn
45 McGrath J and Solter D. 1983. Nuclear transplantation in the mouse embryo by microsurgery and cell fusion. Science 220:1300-1302   DOI
46 Bird A. 2002. DNA methylation patterns and epigenetic memory. Genes. Dev. 16:6-21   DOI   ScienceOn
47 Kues WA, Anger M, Carnwath JW, Paul D, Motlik J and Niemann H. 2000. Cell cycle synchronization of porcine fetal fibroblasts: effects of serum deprivation and reversible cell cycle inhibitors. Biol. Reprod. 62:412-419   DOI   ScienceOn
48 Liu L and Yang X. 1999. Interplay of maturation-promoting factor and mitogen-activated protein kinase inactivation during metaphase-to-interphase transition of activated bovine oocytes. Biol. Reprod. 61:1-7   DOI   ScienceOn
49 Okano M, Bell DW, Haber DA and Li E. 1999. DNA methyltransferases Dnmt3a and Dnmt3b are essential for de novo methylation and mammalian development. Cell, 99:247-257   DOI   ScienceOn
50 Kishigami S, Mizutani E, Ohta H, Hikichi T, Thuan NV, Wakayama S, Bui HT and Wakayama T. 2006. Significant improvement of mouse cloning technique by treatment with trichostatin A after somatic nuclear transfer. Biochem. Biophys. Res. Commun. 340:183-189   DOI   ScienceOn
51 Ravelich SR, Breier BH, Reddy S, Keelan JA, Wells DN, Peterson AJ and Lee RS. 2004a. Insulin-like growth factor- I and binding proteins 1, 2, and 3 in bovine nuclear transfer pregnancies. Biol. Reprod. 70:430-438   DOI   ScienceOn
52 Ravelich SR, Shelling AN, Ramachandran A, Reddy S, Keelan JA, Wells DN, Peterson AJ, Lee RS and Breier BH. 2004b. Altered placental lactogen and leptin expression in placentomes from bovine nuclear transfer pregnancies. Biol. Reprod. 71:1862-1829   DOI   ScienceOn
53 Doherty AS, Mann MR, Tremblay KD, Bartolomei MS and Schultz RM. 2000. Differential effects of culture on imprinted H19 expression in the preimplantation mouse embryo. Biol. Reprod. 62:1526-35   DOI   ScienceOn
54 Walker SK, Heard TM and Seamark RF. 1992. In vitro culture of sheep embryos without co-culture: successes and perspectives. Theriogenology 37:111-126   DOI   ScienceOn
55 Wells DN, Laible G, Tucker FC, Miller AL, Oliver JE, Xiang T, Forsyth JT, Berg MC, Cockrem K, L'Huillier PJ, Tervit HR and Oback B. 2003. Coordination between donor cell type and cell cycle stage improves nuclear cloning efficiency in cattle. Theriogenology 59:45-59   DOI   ScienceOn
56 Li GP, White KL and Bunch TD. 2004. Review of enucleation methods and procedures used in animal cloning: State of the art. Cloning Stem Cells 6:5-13   DOI   ScienceOn
57 Nussbaum DJ and Prather RS. 1995. Differential effects of protein synthesis inhibitors on porcine oocyte activation. Mol. Reprod. Dev. 41:70-75   DOI   ScienceOn
58 Young LE, Fernandes K, McEvoy TG, Butterwith SC, Gutierrez CG, Carolan C, Broadbent PJ, Robinson JJ, Wilmut I and Sinclair KD. 2001. Epigenetic change in IGF2R is associated with fetal overgrowth after sheep embryo culture. Nat. Genet. 27:153-154   DOI   ScienceOn
59 Bourc'his D, Le Bourhis D, Patin D, Niveleau A, Comizzoli P, Renard JP and Viegas-Pequignot E. 2001. Delayed and incomplete reprogramming of chromosome methylation patterns in bovine cloned embryos. Curr. Biol. 11:1542-1546   DOI   ScienceOn
60 Bhak JS, Lee SL, Ock SA, Mohana KB, Choe SY and Rho GJ. 2006. Developmental rate and ploidy of embryos produced by nuclear transfer with different activation treatments in cattle. Anim. Reprod. Sci. 92:37-49   DOI   ScienceOn
61 Hinrichs K, Choi YH, Walckenaer BE, Varner DD and Hartman DL. 2007. In vitro-produced equine embryos: Production of foals after transfer, assessment by differential staining and effect of medium calcium concentrations during culture. Theriogenology 68:521-529   DOI   ScienceOn
62 Vajta G and Gjerris M. 2006. Science and technology of farm animal cloning: Stat of art. Anim. Reprod. Sci. 92:211-230   DOI   ScienceOn
63 Spemann H. 1938. Embryonic Development and Induction.Hafner Publishing Company, New York, U.S.A., pp. 210-211
64 Humpherys D, Eggan K, Akutsu H, Hochedlinger K, Rideout WM III, Biniszkiewicz D, Yanagimachi R and Jaenisch R. 2001. Epigenetic instability in ES cells and cloned mice. Science 293:95-97   DOI   ScienceOn
65 Miyazaki S, Shirakawa H, Nakada K and Honda Y. 1993. Essential role of the inositol 1,4,5-trisphosphate receptor/ $Ca^{2+}$ release channel in $Ca^{2+}$ waves and $Ca^{2+}$ oscillations at fertilization of mammalian eggs. Dev. Biol. 158:62-78   DOI   ScienceOn
66 Zhou Q, Renard JP, Le Friec G, Brochard V, Beaujean N, Cherifi Y, Fraichard A and Cozzi J. 2003. Generation of fertile cloned rats by regulating oocyte activation. Science 302:1179   DOI   PUBMED   ScienceOn
67 Han YM, Kang YK, Koo DB and Lee KK. 2003. Nuclear reprogramming of cloned embryos produced in vitro. Theriogenology 59:33-44   DOI   ScienceOn
68 Medvedev S, Onishi A, Fuchimoto D, Iwamoto M and Nagai T. 2004. Advanced in vitro production of pig blastocysts obtained through determining the time for glucose supplementation. J. Reprod. Dev. 50:71-76   DOI   ScienceOn
69 Eggan K, Baldwin K, Tackett M, Osborne J, Gogos J, Chess A, Axel R and Jaenisch R. 2004. Mice cloned from olfactory sensory neurons. Nature 428:44-49   DOI   ScienceOn
70 Jaenisch R. 1997. DNA methylation and imprinting: Why bother? Trends. Genet. 13:323-329   DOI   ScienceOn
71 Thompson JG. 2000. In vitro culture and embryo metabolism of cattle and sheep embryos - a decade of achievement. Anim. Reprod. Sci. 60-61:263-275   DOI   ScienceOn
72 Swain JE, Bormann CL and Krisher RL. 2001. Development and viability of in vitro derived porcine blastocysts cultured in NCSU23 and G1.2/G2.2 sequential medium. Theriogenology 56:459-469   DOI   ScienceOn
73 Wakayama T, Rodriguez I, Perry AC, Yanagimachi R and Mombaerts P. 1999. Mice cloned from embryonic stem cells. Proc. Natl. Acad. Sci. U.S.A. 96:14984-14989
74 Cibelli JB, Stice S, Golueke PJ, Kane JJ, Jerry J, Blackwell C, Ponce de Leon FA and Robl JL. 1998. Cloned transgenic calves produced from non-quiescent fetal fibroblasts. Science 280:1256-1258   DOI   ScienceOn
75 Elsheikh AS, Takahashi Y, Katagiri S and Kanagawa H. 1998. Functional enucleation of mouse metaphase II oocytes with etoposide. Jpn. J. Vet. Res. 45:217-220   PUBMED
76 Ibanez E, Albertini DF and Overstrom EW. 2003. Demecolcineinduced oocyte enucleation for somatic cell cloning: Coordination between cell-cycle egress, kinetics of cortical cytoskeletal interactions, and second polar body extrusion. Biol. Reprod. 68:1249-1258   DOI
77 Menezo YJ and Herubel F. 2002. Mouse and bovine models for human IVF. Reprod. Biomed. Online. 4:170-175
78 Byrne JA, Simonsson S, Western PS and Gurdon JB. 2003. Nuclei of adult mammalian somatic cells are directly reprogrammed to oct-4 stem cell gene expression by amphibian oocytes. Curr. Biol. 13:1206-1213   DOI   ScienceOn
79 Campbell KHS, Alberio R, Choi I, Fisher P, Klly RDW, Lee JH and Maalouf W. 2005. Cloning: Eight years after Dolly. Reprod. Dom. Anim. 40:256-268   DOI   ScienceOn
80 Boquest AC, Day BN and Prather RS. 1999. Flow cytometric cell cycle analysis of cultured porcine fetal fibroblast cells. Biol. Reprod. 60:1013-1019   DOI   ScienceOn
81 Chatot CL, Ziomek CA, Bavister BD, Lewis JL and Torres I. 1989. An improved culture medium supports development of random-bred 1-cell mouse embryos in vitro. J. Reprod. Fertil. 86: 679-688   DOI   PUBMED   ScienceOn
82 Dindot SV, Farin PW, Farin CE, Romano J, Walker S, Long C and Piedrahita JA. 2004. Epigenetic and genomic imprinting analysis in nuclear transfer derived Bos gaurus/Bos taurus hybrid fetuses. Biol. Reprod. 71:470-478   DOI   ScienceOn
83 Heard E. 2004. Recent advances in X-chromosome inactivation. Curr. Opin. Cell. Biol. 16:247-255   DOI   ScienceOn
84 Takahashi K and Yamanaka S. 2006. Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors. Cell 126:663-676   DOI   ScienceOn
85 Erbach GT, Lawitts JA, Papaioannou VE and Biggers JD. 1994. Differential growth of the mouse preimplantation embryo in chemically defined media. Biol. Reprod. 50:1027-1033   DOI   ScienceOn
86 Farin PW, Piedrahita JA and Farin CE. 2006. Errors in development of fetuses and placentas from in vitro-produced bovine embryos. Theriogenology 65:178-191   DOI   ScienceOn
87 Amano T, Tani T, Kato Y and Tsunoda Y. 2001. Mouse cloned from embryonic stem (ES) cells synchronized in metaphase with nocodazole. J. Exp. Zool. 289:139-145   DOI   ScienceOn
88 Vajta G, Zhang Y and Machaty Z. 2007. Somatic cell nuclear transfer in pigs: recent achievements and future possibilities. Reprd. Fertil. Dev. 19:403-423   DOI   ScienceOn
89 Wakayama T. 2007. Production of cloned mice and ES cells from adult somatic cells by nuclear transfer: How to improve cloning efficiency? J. Reprod. Dev. 53:13-26   DOI   ScienceOn
90 Briggs R and King TJ. 1952. Transplantation of living nuclei from blastula cells into enucleated frog's eggs. Proc. Natl. Acad. Sci. U.S.A. 38:455-461
91 Kang YK, Koo DB, Park JS, Choi YH, Chung AS, Lee KK and Han YM. 2001a. Aberrant methylation of donor genome in cloned bovine embryos. Nat. Genet. 28:173-177   DOI   ScienceOn
92 Pinkert CA. 1994. Transgenic pig models for xenotranplantation. Xeno. 2:10-15
93 Tanaka H and Kanagawa H. 1997. Influence of combined activation treatments on the success of bovine nuclear transfer using young or aged oocytes. Anim. Reprod. Sci. 49: 113-123   DOI   ScienceOn
94 Lai L, Kolber-Simonds D, Park KW, Cheong HT, Greenstein JL, Im GS, Samuel M, Bonk A, Rieke A, Day BN, Murphy CN, Carter DB, Hawley RJ and Prather RS. 2002. Production of alpha-1,3-galactosyltransferase knockout pigs by nuclear transfer cloning. Science 295:1089-92   DOI   ScienceOn
95 Saunders CM, Larman MG, Parrington J, Cox LJ, Royse J, Blayney LM, Swann K and Lai FA. 2002. PLC zeta: a spermspecific trigger of $Ca^{(2+)}$ oscillations in eggs and embryo development. Dev. 129:3533-3544
96 Forsberg EJ, Strelchenko NS, Augenstein ML, Betthauser JM, Childs LA, Eilertsen KJ, Enos JM, Forsythe TM, Golueke PJ, Koppang RW, Lange G, Lesmeister TL, Mallon KS, Mell GD, Misica PM, Pace MM, Pfister-Genskow M, Voelker GR, Watt SR and Bishop MD. 2002. Production of cloned cattle from in vitro systems. Biol. Reprod. 67:327-333   DOI   ScienceOn