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Nuclear transfer of domestic cat can be used as a tool to develop reproductive biotechnologies in wild felids. The importance of cell cycle phase during the nuclear transfer has been a matter of debate since the first mammalian clone was produced. The cell cycle phase of donor cells interferes on maintenance of correct ploidy and genetic reprogramming of the reconstructed embryo. The use of G0/G1 arrested donor cells has been shown to improve nuclear transfer efficiency. The present study was conducted to test the hypothesis that domestic cat foetal fibroblasts cultured up to the fifth passage and submitted to full confluency provide a higher percentage of cells at G0/G1 stage than fibroblasts cultured in serum starved media. Results demonstrated that serum starvation increased (p < or = 0.05) the percentage of G0/G1 fibroblasts when compared with control. Moreover, the combined protocol using confluency and serum starvation was more efficient (p < or = 0.05) synchronizing cells at G0/G1 stage than serum starvation or confluency alone for the first 3 days of treatment. In conclusion, serum starvation and full confluency act in a synergistic manner to improve domestic cat foetal fibroblast cell cycle synchronization at the G0/G1 stage.

This study evaluated in vitro maturation of pig oocytes in two maturation media (TCM199 and NCSU23) supplemented with 10% porcine follicular fluid (pFF) or 0.1% polyvinyl alcohol (PVA) and four hormonal treatments. The best media was then used to evaluate the effect of reversible meiosis inhibitors cycloheximide (5 microgram/ml) [DOSAGE ERROR CORRECTED]and butyrolactone I (12.5M) on the maturation of pig oocytes was evaluated. After maturation for 44 h, the oocytes were fixed, stained, and examined under epifluorescence microscopy. The comparison of the proportion of oocytes in metaphase II revealed that hormonal treatment 2(incubation for 22 h - 10 ng EGF/ml, 10 IU hCG/ml and 10 IU eCG/ml, followed by incubation for 22 h - 10 ng EGF/ml) presented higher repeatability percentages: TCM+ PVA (54.5% - 61/112); TCM+ pFF (65.0% - 63/97);NCSU23 + PVA (54.6% - 65/119), and NCSU23 + pFF (58.1% - 61/105). The comparison of maturation media showed that TCM199 presented more constant results than NCSU23. Regarding supplementation with pFF or PVA, TCM199 with pFF presented better results. The comparison between butyrolactone I and cycloheximide demonstrated that both drugs effectively inhibited meiosis; however, only cycloheximide presented metaphase II percentages similar to the control (70.29% and 75.49%, respectively). In conclusion, it is recommended the use of TCM199 medium supplemented with pFF and hormonal treatment with 10 ng EGF/ml, 10 UI hCG/mland 10 UI eCG/ml during the first 22 h and more 22 h with 10 ng EGF/ml for the pig oocytes maturation. Butyrolactone I and cycloheximide effectively arrested/resumpted maturation; however, the oocytes percentages in metaphase II was the same for both cycloheximide and the control groups.

Arrest of cells in G0/G1 cell cycle phase is desired for nuclear transfer procedures. Serum starvation and cell cycle inhibitors are different ways to induce synchronization of the cell cycle. This study investigated the effects of serum starvation and cycloheximide (CHX) on the cell cycle of low (5th) and high (15th) passages fetal porcine fibroblasts. Cell cycle phases were determined using fluorescent activated cell sorting. Fifth passage fibroblast cultures had higher (p < 0.05) proportion of cells in G0/G1 only after 72 h of serum starvation (77.60 +/- 0.65) when compared with non-starved cells (71.44 +/- 1.88). Serum starvation for all periods tested induced an increase (p < 0.05) on proportion of cells in G0/G1 on the 15th passage. No significant differences were observed on the 5th passage cultures exposed to CHX, although, on the 15th passage an increase on proportion of cells was observed after all periods of exposure (p < 0.05). These data indicates that high passage cells in vitro are more susceptible to serum starvation and CHX G0/G1 synchronization.

Cryopreservation of mammalian embryos is an important tool for the application of reproductive biotechnologies. Subjective evaluation to determine embryo viability is often used. The determination of the best cryopreservation protocol depends on morphological and molecular analysis of cellular injuries. The main objective of this study was to compare two methods of cryopreservation by assessing morphological alterations of frozen embryos using light, fluorescence, and transmission electron microscope. Fresh (control), slow frozen, and vitrified mouse embryos were composed. To evaluate the viability of the embryos, the cell membrane integrity was assessed using Hoechst33342 and propidium iodide (H/PI) staining. Morphological analyses using hematoxylin and eosin (HE) staining were performed to test different techniques (in situ, paraffin, and historesin) by both light and fluorescence microscopy. Transmission electron microscope was used to detect ultrastructural alterations in Spurr- and Araldite-embedded samples. H/PI staining detected more membrane permeability in the vitrification (69.8%) than in the slow freezing (48.4%) or control (13.8%) groups (P < 0.001). Historesin-embedded samples showed to be more suitable for morphological analyses because cellular structures were better identified. Nuclear evaluation in historesin sections showed the induction of pycnosis in slow freezing and vitrification groups. Cytoplasm evaluation revealed a condensation and an increase in eosinophilic intensity (indicating apoptosis) in the slow freezing group, and weakly eosinophilic structures and degenerated cells (indicating oncosis) in the vitrification group (P < 0.05). Ultrastructural analyses confirmed HE morphological findings. It was concluded that both cryopreservation techniques resulted in oncosis and apoptosis injuries. However, vitrification caused more severe cellular alterations and reduced embryonic viability compared to slow freezing.

The cryopreservation of bovine oocytes remains a challenge despite significant reported progress. Immature bovine oocytes have a complex structure and the conventional cryoprotectants (penetrating cryoprotectants, sugars, and macromolecules) appear to be not sufficient to preserve them efficiently during freezing. Studies on semen and fibroblast cryopreservation indicate that amino acids, particularly l-glutamine, protect enzymes during freezing and increase the post-thaw viability. Therefore, the amino acids may optimize oocyte cryopreservation when associated with conventional cryoprotectants. This work evaluated the effect of l-glutamine on cryopreservation of immature bovine oocytes after in vitro maturation. Oocytes with homogeneous cytoplasm and several cumulus cell layers from slaughterhouse ovaries were distributed randomly in three groups: non-vitrified control, vitrified control, and vitrified with l-glutamine. Oocytes from vitrified groups were exposed for 10 min to PBS + 10% FCS + 10% ethylene glycol (EG) + 0.25 m trehalose (T), and for 30 s to PBS + 10% FCS + 25% EG + 25% dimethylsulfoxide + 0.5 m T at room temperature, adding 80 mm l-glutamine for the third group. Oocytes were loaded into OPS and plunged in liquid nitrogen. For thawing, OPS were immersed in PBS + 10% FCS + 10% EG + 1 m T for three min. Oocytes werethen placed in PBS + 10% FCS + 0.5 m T and in PBS + 10% FCS, remaining three min in each solution. For in vitro maturation, oocytes were washed three times on holding medium (TCM-HEPES + FCS + pyruvate + gentamycin), washed three times in maturation medium (TCM-bicarbonate + FCS + pyruvate + gentamycin + hCG + FSH + estradiol), and cultured in microdrops (90 μL) of maturation medium covered with mineral oil at 38.5°C under 5% CO2 in air and high humidity for 24 h. Oocytes were denuded, fixed in paraformaldehyde and triton, stained with Hoechst 33342, and evaluated under epifluorescence microscopy. Oocytes at metaphase II were considered matured. The group vitrified with l-glutamine had a significantly higher maturation rate than the group vitrified without l-glutamine; however, both had significantly lower maturation rates than the non-vitrified control group. In conclusion, l-glutamine improved the viability of vitrified oocytes. Table 1. Oocyte maturation rates of non-vitrified control, vitrified control, and vitrified with glutamine groups This work was supported by FAPESP 03/08543-1.

The aim of this study was to compare two ethylene glycol (EG) equilibration procedures for the quick freezing of in vitro-produced bovine embryos. Cumulus-oocyte complexes (COCs) were collected from slaughterhouse ovaries. COCs were matured in TCM199 containing 10% of bovine fetal serum, LH, FSH and E2, and fertilized. Presumptive zygotes were co-cultured in TCM199 with a granulosa cell monolayer, at 39°C in humidified atmosphere of 5% CO2 in air. Grade 1, expanded blastocysts (n = 761) were selected 7 and 9 days after insemination and randomly distributed to one of eight treatment groups. In Equilibration Procedure 1, embryos were exposed to 10% EG for 5 min, and then to 17%, 22% or 28% EG for 60 s (respectively referred to as EG 17, EG 22 and EG 28). In Equilibration Procedure 2, embryos were exposed to the same EG solutions as in Equilibration Procedure 1, but the period of exposure was 10 min to 10% EG and 30 s to EG 17, EG 22 and EG 28. In Equilibration Procedure 3 (slow-freezing controls), embryos were exposed to 10% EG for either 5 or 10 min and then cryopreserved by slow-freezing method at 1.2°C/min. In all treatment groups, EG solutions were prepared in PBS + 0.2% BSA, and embryos were exposed to EG solutions at 22°C. Embryos were loaded into 0.25 mL straws and heat-sealed. Straws were cooled in liquid nitrogen vapor for 2 min, and then plunged into and stored in liquid nitrogen. Straws were thawed in room temperature air for 10 s, and then in 25°C water for 20 s. Thawed embryos were diluted by transferring them into 0.5 ml of PBS + 0.2% BSA + 0.3 M sucrose for 3 min, and then 0.5 mL of PBS + 0.2% BSA for 3 min. Embryos were co-cultured on granulosa cell monolayer in TCM199 and evaluated after 24 h for blastocyst re-expansion (EXP), and again at 48, 72 and 96 h for hatching (HAT). A total of 724 in vitro-produced bovine blastocysts were used as controls to determine hatching rates. The results are presented in the table. Embryos exposed to 10% EG for 10 min (Equilibration Procedure 1) yielded significantly higher rates of blastocyst re-expansion and hatching when compared to embryos exposed for 5 min (Equilibration Procedure 2, P

Adult skin and fetal fibroblasts are the most frequently used donor cell types for bovine cloning by nuclear transfer (NT) but there are few reports concerning Nelore cattle. The aim of this study was to evaluate in vitro and in vivo viability of Nelore nuclear transfer embryos reconstructed with Metaphase II oocytes and differentiated somatic cells (adult ear and fetal fibroblasts). Oocytes from ovaries collected at slaughterhouse were matured in vitro for 17h. Enucleation was conducted by aspiration of the first polar body (PB) and small volume of cytoplasm containing metaphase plate. For NT, each nucleus donor cell was inserted under the zona pellucida of each enucleated oocyte and the enucleated oocyte-nuclei donor cell complexes were electrofused (2 pulses of 4KVcm−1 for 20s). After electrical activation, the couplets were incubated in TCM199 plus 7.5% FCS supplemented with cycloheximide (10gmL−1) and cytochalasin D (2.5gmL−1) for 1h and ciclohexemide alone for 4 additional hours. Immediately after activation, reconstructed embryos were co-cultured with granulosa cells in SOF + 5% FCS for 7–9 days. At 7th day of culture, some blastocysts were fixed for counting cells and some transferred into recipients. A total of 377 couplets were reconstructed from fetal and 457 from adult fibroblasts. After electrofusion, 138 (fetal cells) and 166 (adult cells) embryos were incubated, and 24 (17.4%) and 26 (15.7%) reached blastocyst stage, respectively. The blastocyst cell number means were 101.3, 120 and 114.3, respectively, for adult, fetal and IVF (control) embryos. There were no significant differences in the numbers of cells of blastocysts among the groups. After transferring 18 (fetal cells) and 21 (adult cells) blastocysts, pregnancy rates at day 90 were 16.7% (3) and 19% (4). There were no significant differences between pregnancy rates. The first pregnancy from fetal cells delivered a healthy male calf weighing 34kg at Day 290. One of the remaining recipients died with hydrallantois at Day 229 and the other aborted at Day 252. There are four 5-month-pregnancies of adult fibroblast reconstructed embryos. These results indicate that NT embryos produced by fetal and adult fibroblasts of Nelore breed show similar rates of in vitro and in vivo developments. This work was supported by FAPESP (99/07377-3).