78 EFFECTS OF DIFFERENT ACTIVATION PROTOCOLS ON ACTIN FILAMENT DISTRIBUTION AND IN VITRO DEVELOPMENT OF MINIATURE PIG NT EMBRYOS

2006 ◽  
Vol 18 (2) ◽  
pp. 147
Author(s):  
K. Yamanaka ◽  
S. Sugimura ◽  
T. Wakai ◽  
T. Shoji ◽  
H. Sasada ◽  
...  

In the process of producing reconstructed oocytes nuclear transfer (NT) embryos by somatic cell nuclear transfer, in vitro-matured oocytes can be used as recipient ones. It, however, has been well documented that after IVF porcine embryos derived from in vitro-matured oocytes have a small number of cells and low viability compared from those in vivo. As one possible reason, abnormal actin filament distribution has been detected in abnormal embryo cleavage and small cell numbers (Wang et al. 1999 Biol. Reprod. 60, 1020-1028). Artificial activation, which is necessary for development of NT embryos, can affect actin filament distribution of porcine oocytes matured in vitro, resulting in fragmentation (Kawahara et al. 2002 Theriogenology 58, 1081-1095). In the present study, we investigated effects of different activation protocols on actin filament distribution and in vitro development of miniature pig NT embryos. Porcine oocytes collected from ovaries were matured in vitro for 40 to 44 h in NCSU-23. First, we compared different activation protocols in development rates to blastocysts of oocytes activated. We used three activation methods (15 �M ionomycin treatment for 20 min (I), double DC pulses of 1.2 kV/cm for 60 ms in intervals of 5 s (E), and 5 mg/mL cycloheximide treatment for 5 h (C)) to prepare seven activation protocols (I, E, C, I + C, I + E, E + C, and I + E + C). Second, we examined effects of different activation protocols on actin filament distribution and subsequent development of NT embryos activated by the different activation protocols. Matured oocytes were enucleated, and fused with miniature pig fetal fibroblasts in calcium-free medium; approximately 3 h later, the resultant NT embryos were activated with three activation protocols (E, I + C, or I + E + C). All data were analyzed by chi-square test. The developmental rates to blastocysts in the I, E, C, I + C, I + E, E + C, and I + E + C groups were 5.6, 11.1, 0.0, 36.1, 20.7, 14.6, and 24.7%, respectively, showing that the rate in oocytes activated with I + C was significantly higher (P < 0.05) than the rates in oocytes activated by other treatments. In NT embryos, the developmental rates to blastocysts in the E, I + C, or I + E + C groups were 4.1, 14.3, and 4.6%, respectively, showing that the rate in NT embryos activated with I + C was significantly higher (P < 0.05) than the rate in NT embryos activated with other treatments. The abnormal rate of actin filament distribution in NT embryos activated with E or I + E + C was significantly higher (P < 0.05) than that in NT embryos activated with I + C (26.7% or 33.3% vs. 6.7%). The present results suggest that in miniature pig NT embryos an activation protocol by ionomycin combined with cycloheximide treatments may avoid physical damage to actin filaments with the resultant improvement of subsequent development.

2009 ◽  
Vol 55 (3) ◽  
pp. 236-239 ◽  
Author(s):  
Kenji NARUSE ◽  
Yan-Shi QUAN ◽  
Baek-Chul KIM ◽  
Su-Min CHOI ◽  
Chang-Sik PARK ◽  
...  

2003 ◽  
Vol 65 (9) ◽  
pp. 989-994 ◽  
Author(s):  
Mario A. MARTINEZ DIAZ ◽  
Tadashi MORI ◽  
Masashi NAGANO ◽  
Seiji KATAGIRI ◽  
Yoshiyuki TAKAHASHI

2004 ◽  
Vol 16 (2) ◽  
pp. 144
Author(s):  
G.-S. IM ◽  
L. Lai ◽  
Z. Liu ◽  
Y. Hao ◽  
C.M. Murphy ◽  
...  

Although nuclear transfer (NT) has successfully produced cloned piglets, the development to blastocyst and to term is still low. Activation of the NT embryos is one of the key factors to improve the developmental ability of porcine NT embryos. Electric pulses as well as chemicals have been used to activate porcine NT embryos. This study was conducted to investigate the effect of continued activation following fusion pulses on in vitro development of porcine NT Embryos. Oocytes derived from a local abattoir were matured for 42 to 44h and enucleated. Ear skin cells were obtained from a 4-day-old transgenic pig transduced with eGFP recombinant retrovirus. Enucleated oocytes were reconstructed and cultured in PZM-3 in a gas atmosphere of 5% CO2 in air. Cleavage and blastocyst developmental rates were assessed under a stereomicroscope on Day 3 or 6. Blastocysts were stained with 5μg of Hoechst 33342 and total cell number was determined with an epifluorescent microscope. In Experiment 1, oocytes were activated with two 1.2kV/cm for 30μs (E) in 0.3M mannitol supplemented with either 0.1 or 1.0mM Ca2+. In each treatment, activated oocytes were divided into three groups. The first group was control (E). Other two groups were exposed to either ionomycin and 6-DMAP (E+I+D) or 6-DMAP (E+D) immediately after the electric pulses. In Experiment 2, fusion was conducted by using 1.0mM Ca2+ in the fusion medium. Fused NT embryos were divided into three treatments. NT embryos were fused and activated simultaneously with electric pulse as a control (C); the second group was treated with 6-DMAP immediately after fusion treatment (D0); and the third group was treated with 6-DMAP at 20min (D20) after fusion. In experiment 1, for 0.1mM Ca2+, developmental rates to the blastocyst stage for E, E+I+D or E+D were 12.5, 26.7 and 22.5%, respectively. For 1.0mM Ca2+, developmental rates to the blastocyst stage were 11.4, 28.3 and 35.6%, respectively. The activated oocytes treated with 6-DMAP following the electric pulses by using 1.0mM Ca2+ in fusion medium had higher (P&lt;0.05) developmental rates to the blastocyst stage. In Experiment 2, developmental rates to the blastocyst stage for C, D0 or D20 were 10.0, 12.3, and 19.9%, respectively. Developmental rate to the blastocyst stage was higher (P&lt;0.05) in D20. Fragmentation rates were 19.9, 10.8, and 9.0%, respectively. Regardless of Ca2+ concentration in fusion medium, continued treatments with chemicals following electric pulses supported more development of porcine activated oocytes. Treating NT embryos with 6-DMAP alone after fusion was completed by using 1.0mM Ca2+ in fusion medium improved the developmental rates to the blastocyst stage and prevented fragmentation accompanied by electric fusion. This study was supported by NIH NCRR 13438 and Food for the 21st Century.


2017 ◽  
Author(s):  
◽  
Bethany Rae Mordhorst

Gene edited pigs serve as excellent models for biomedicine and agriculture. Currently, the most efficient way to make a reliably-edited transgenic animal is through somatic cell nuclear transfer (SCNT) also known as cloning. This process involves using cells from a donor (which may have been gene edited) that are typically grown in culture and using their nuclear content to reconstruct a new zygote. To do this, the cell may be placed in the perivitelline space of an enucleated oocyte and activated artificially by a calcium-containing media and electrical pulse waves. While it is remarkable that this process works, it is highly inefficient. In pigs the success of transferred embryos becoming live born piglets is only 1-3%. The creation of more cloned pigs enables further study for the benefit of both A) biomedicine in the development of prognosis and treatments and B) agriculture, whether it be for disease resistance, feed efficiency, gas emissions, etc. Two decades of research has not drastically improved the cloning efficiency of most mammals. One of the main impediments to successful cloning is thought to be due to inefficient nuclear reprogramming and remodeling of the donor cell nucleus. In the following chapters we detail our efforts to improve nuclear reprogramming of porcine fetal fibroblasts by altering the metabolism to be more blastomere-like in nature. We used two methods to alter metabolism 1) pharmaceutical agents and 2) hypoxia. After treating donor cells both methods were used in nuclear transfer. Pharmaceutical agents did not improve in vitro development of gestational survival of clones. Hypoxia did improve in vitro development and we are currently awaiting results of gestation.


Author(s):  
Paul J. Verma ◽  
Zhong-Tao Du ◽  
Lesley Crocker ◽  
Renate Faast ◽  
Christopher G. Grupen ◽  
...  

2000 ◽  
Vol 12 (2) ◽  
pp. 1 ◽  
Author(s):  
Sangho Roh ◽  
Hosup Shim ◽  
Woo-suk Hwang ◽  
Jong-taek Yoon

Nuclear transfer using transfected donor cells provides an efficient new strategy for the production of transgenic farm animals. The present study assessed in vitro development of nuclear transfer embryos using green fluorescent protein (GFP) gene-transfected bovine fetal fibroblasts. In experiment 1, bovine fetal fibroblasts (BFF) were transfected with linearized pEGFP-N1 by electroporation, and the enucleated oocytes were reconstructed by nuclear transfer of transfected cells (BFF-GFP). The rates of blastocyst formation did not differ significantly between BFF and BFF-GFP (18.2% v. 15.6%). In experiment 2, before nuclear transfer, the donor cell stage was synchronized by serum deprivation or forming a confluent monolayer. The rates of cleavage (67.1% v. 71.8%) and blastocyst formation (15.8% v. 15.5%) did not differ between confluent and serum-starved cells after nuclear transfer. In experiment 3, the effects of different passages of donor fibroblast cells on the development of nuclear transfer embryos were investigated. Donor cells from ‘early’ (at passage 8–16) showed better blastocyst development (18.9%) than those from ‘late’ (at passage 17–32; 10.5%). In conclusion, this study suggests that transgenic somatic cell nuclei from early passages can be reprogrammed more effectively than those from late passages. In addition, GFP, a non-invasive selection marker, can be used to select transgenic nuclear transfer embryos.


1999 ◽  
Vol 51 (1) ◽  
pp. 204
Author(s):  
J.R Hill ◽  
Q.A Winger ◽  
K.L Jones ◽  
J.A Thompson ◽  
R.C Burghardt ◽  
...  

2007 ◽  
Vol 19 (1) ◽  
pp. 138 ◽  
Author(s):  
K. Hasegawa ◽  
S. Takahashi ◽  
S. Akagi ◽  
K. Takeda ◽  
K. Imai ◽  
...  

We previously produced a cloned calf by nuclear transfer (NT) using cumulus cells removed from cumulus–oocyte complexes (COCs) after IVM. If both cumulus cells and oocytes are obtained identically and individually, and can be used simultaneously for NT, the production of cloned cows will be more expedient. And the cloned offspring produced from them will not exhibit the heteroplasmic mixed mtDNAs of donor cells and recipient oocytes. In this study, we examined the developmental potential of NT embryos using cumulus–oocyte complexes (COCs) collected from cows individually by ovum pickup (OPU). The cumulus cells were removed from COCs after IVM. The cumulus cells and cumulus-free MII oocytes derived from the same cow were used as donor nuclei and recipient oocytes, respectively. NT was performed as previously described (Akagi et al. 2003 Clon Stem Cells 5, 101–108). In Experiment 1, we examined the in vitro development of NT embryos using COCs collected by OPU. The aspiration of the follicles was performed once a week consecutively for 6 weeks in 6 cows (Cows A, B, C, D, E, and F) without hormone stimulation. In Experiment 2, we examined fetal development after the transfer of NT embryos. A Japanese black cow (Cow G) was used for OPU. On Day 7, 13 NT blastocysts were transferred to 7 recipient cows. The mtDNA genotypes of the donor cow and the cloned calf were analyzed by PCR-mediated single-strand conformation polymorphism analysis as previously described (Takeda et al. 2003 Mol. Reprod. Dev. 64, 429–437). The results of Experiment 1 are summarized in Table 1. Fusion rates did not differ among individual cows. However, the developmental rates of NT embryos at the blastocyst stage varied widely among individual cows, with a range of 19 to 64%. In Experiment 2, 2 of 7 recipient cows became pregnant on Day 30. One pregnant cow aborted on Day 60, and another cow calved a healthy calf. The mtDNA genotype of the cloned calf was confirmed to be identical with that of the donor cow. These results indicate that COCs from an identical individual can be used as donor nuclei and recipient oocytes for NT in order to produce female clones with the same mtDNA as that of the donor cow. Table 1.In vitro development of NT embryos using COCs collected by OPU


Sign in / Sign up

Export Citation Format

Share Document