Forward neutral-pion transverse single-spin asymmetries in p + p collisions at sqrt[s] = 200 GeV

We report precision measurements of the Feynman x (xF) dependence, and first measurements of the transverse momentum (pT) dependence, of transverse single-spin asymmetries for the production of pi0 mesons from polarized proton collisions at sqrt[s] = 200 GeV. The xF dependence of the results is in fair agreement with perturbative QCD model calculations that identify orbital motion of quarks and gluons within the proton as the origin of the spin effects. Results for the pT dependence at fixed xF are not consistent with these same perturbative QCD-based calculations.

Longitudinal double-spin asymmetry for inclusive jet production in p[over -->] + p[over -->] collisions at sqrt[s]=200 GeV

We report a new STAR measurement of the longitudinal double-spin asymmetry A(LL) for inclusive jet production at midrapidity in polarized p + p collisions at a center-of-mass energy of sqrt[s]=200 GeV. The data, which cover jet transverse momenta 5<p(T)<30 GeV/c, are substantially more precise than previous measurements. They provide significant new constraints on the gluon spin contribution to the nucleon spin through the comparison to predictions derived from one global fit to polarized deep-inelastic scattering measurements.

98 VITRIFICATION OF ZYGOTES SUPPORTS FULL-TERM DEVELOPMENT IN RABBITS

Rabbit can serve as an excellent model for human reproduction and relevant disease study. The objective of the study was to develop an effective procedure to preserve the rabbit genome by vitrifying zygotes. Sexually matured New Zealand White rabbits maintained under a 16 h light:8 h dark cycle were superovulated with a regime of two 0.3-mg, two 0.4-mg, and two 0.7-mg injections of FSH with an interval of 12 h between, followed by an injection of 200 IU hCG and mating. Presumptive zygotes were flushed from the oviducts and collected by midventral lapartomy 18 h after hCG injection. One-cell-stage embryos were assigned to pre-equilibration at 38.5�C in HEPES-buffered TCM199 supplemented with 20% FBS + 7.5% ethylene glycol (EG) (v/v) + 7.5% dimethylsulphoxide (DMSO) (v/v) (dehydration medium) for 3 min, and subsequently to 1.0 ml of vitrification medium (TCM199 supplemented with 20% FBS + 20% EG and 20% DMSO), as described by Vajta et al. (1998 Mol. Reprod. Dev. 51, 53–58), at room temperature for 3 min. Five to six embryos per group were then vitrified in a micro-droplet (approximately 1–2 µL) by directly dropping them into a thin layer of liquid nitrogen on the solid surface that generated a super cold surface for vitrification. Vitrified embryos were sequentially warmed, rehydrated in 20% FBS M199 with different concentrations of sucrose, and washed in 20% FBS M199 for 5 min. Warmed embryos were assigned either for further in vitro culture or for embryo transfer to test corresponding developmental potentials. Dutch rabbits were used as recipients in the procedure of asynchronous ovulation induction (22-h delay to zygote donors) by an intramuscular injection of 15 µg of GnRH per doe. Three or four warmed zygotes were surgically transferred into the recipients on the same day of thawing. Pregnancy was monitored by palpation and/or ultrasound on Days 14–16 post-embryo transfer (ET); C-sections were performed on Day 31 to retrieve full-term developed newborns. Preliminary results showed that a 96% (n = 35) post-warming survival rate was achieved with vitrified rabbit zygotes; subsequent cleavage and blastocyst development were 41.6 and 33.3%, respectively. Transfer of a total of 23 warmed embryos into 6 recipients resulted in 5 pregnancies (83.3%, 5/6). Five live kits (21.7%, 5/23) were delivered. Our study suggests that vitrification of rabbit zygotes is a feasible approach for preserving rabbit genetic material. The establishment of suitable conditions for the vitrification of rabbit zygotes could be useful as a model for vitrification of human 1-celled embryos. The authors thank the staff of the animal facility at the University of Connecticut for animal care and maintenance. This work was supported by NIH/NCRR-SBIR grant: 1R43RR020261-01.

199 EFFECT OF HEPARIN CONCENTRATION ON BOVINE PREIMPLANTATIONAL DEVELOPMENT IN VITRO USING SEX-SORTED SPERM

The objective of this study was to examine the effect of heparin on bovine IVF and to improve the efficiency of IVF production by using sex-sorted sperm. The fertility performance of sex-sorted and unsorted semen from 4 bulls was compared to determine the optimal heparin concentration during preimplantational embryo development. A total of 7615 matured bovine oocytes were randomly allocated among different heparin concentrations (0, 2.5, 5, 10, 20, 40, 60, 80, and 100 μg mL–1) in Brackett-Oliphant medium and coincubated with either sex-sorted or unsorted sperm for 6 h. Presumptive zygotes were cultured in CR1aa+ 6 mg mL–1 of BSA in 5% O2 , 5% CO2 and 90% N2 at 39°C until Day 8 (Day 0, culture post-IVF). Cleavage rates at Day 2 and embryo development to blastocyst (BL) at Day 8 were recorded. Data (4 replicates) were analyzed by a general linear model (SPSS 11.0, SPSS Inc., Chicago, IL). The optimal heparin concentration for each treatment was determined as the lowest value from those groups that resulted in the highest BL rates. The results (Table 1) demonstrated that a differential requirement of heparin concentration was important for the highest preimplantational BL development between sexed sperm and unsorted control within each bull. By optimizing heparin concentration, in 3 out of 4 (75%) bulls, the in vitro BL development with sex-sorted sperm could be increased to a level that was comparable to the highest BL rate from unsorted sperm (bulls A, B, and C, P > 0.05). A higher heparin concentration was required for optimal BL development in bulls A and C; however, a lower concentration was desirable for bulls B and D, indicating that a partial capacitation to the sperm may have taken place in bulls B and D during the sorting process, as reported by Lu and Seidel (2004 Theriogenology 62, 819–830). The fertility of sorted sperm from bull D (1 out of 4, 25%) was adversely affected, even after heparin optimization for BL development (P < 0.05). This result suggests that sperm sorting could affect the IVF fertility of sorted sperm in a bull-specific manner, but it was not significant for all bulls. Table 1. Blastocyst (BL) development in bovine IVF after heparin optimization using sorted and unsorted sperm This project was supported by the SBIR program under a USDA Cooperative State Research, Education, and Extension Service (CSREES) grant to F. Du (USDA #2006-03069).

Nuclear reprogramming by somatic cell nuclear transfer--the cattle story

Somatic cell nuclear transfer (cloning) returns a differentiated cell to a totipotent status; a process termed nuclear reprogramming. Nuclear transfer has potential applications in agriculture and biomedicine, but is limited by low efficiency. To understand the deficiencies of nuclear reprogramming, our research has focused on both candidate genes (imprinted and X-linked genes) and global gene expression patterns in cloned bovine embryos/offspring as compared to those generated by conventional reproduction. We found aberrant expression patterns of H19 and Igf2r as well as X-linked genes in term cloned calves. The expression profiles of cloned blastocysts, however, closely resembled those of the naturally fertilized embryos but were considerably different from those of their nuclear donor cells. Our findings suggest that cloned embryos have undergone significant nuclear reprogramming by the blastocyst stage. However, it is possible that during re-differentiation in later development gene expression aberrancies occur. Additionally, small initial nuclear reprogramming errors may be manifested during subsequent development.

Pregnancy and fetal characteristics after transfer of vitrified in vivo and cloned bovine embryos

This study was conducted to examine pregnancy progression and fetal characteristics following transfer of vitrified bovine nuclear transfer versus in vivo-derived embryos. Nuclear transfer (NT) was conducted using cumulus cells collected from an elite Holstein-Friesian dairy cow. Expanding and hatching blastocysts on Day 7 were vitrified using liquid nitrogen surface vitrification. Day 7 in vivo embryos, produced using standard superovulation procedures applied to Holstein-Friesian heifers (n=6), were vitrified in the same way. Following warming, embryos were transferred to synchronized recipients (NT: n=65 recipients; Vivo: n=20 recipients). Pregnancies were monitored by ultrasound scanning on Days 25, 45 and 75 and a sample of animals were slaughtered at each time point to recover the fetus/placenta for further analyses. Significantly more animals remained pregnant after transfer of in vivo-derived embryos than NT embryos at all time points: Day 25 (95.0 versus 67.7%, P<0.05), Day 45 (92.8 versus 49.1%, P<0.01) and Day 75 (70.0 versus 20.8%, P<0.0). There was no significant difference (P=0.10) in the weight of the conceptus on Day 25 from NT transfers (1.14+/-0.23 g, n=8) versus in vivo transfers (0.75+/-0.19 g, n=8). On Day 45, there was no significant difference in the weight of either fetus (P=0.393) or membranes (P=0.167) between NT embryos (fetus: 2.76+/-0.40, n=12; membranes: 59.0+/-10.0, n=11) or in vivo-derived embryos (fetus: 2.60+/-0.15, n=6; membranes: 41.8+/-5.2, n=4). However, on Day 75 the weight of the fetus and several of the major organs were heavier from NT embryos. These data suggest that morphological abnormalities involving the fetus and the placenta of cloned pregnancies are manifested after Day 45.

Measurement of transverse single-spin asymmetries for Dijet production in proton-proton collisions at sqrt[s]=200 GeV

We report the first measurement of the opening angle distribution between pairs of jets produced in high-energy collisions of transversely polarized protons. The measurement probes (Sivers) correlations between the transverse spin orientation of a proton and the transverse momentum directions of its partons. With both beams polarized, the wide pseudorapidity (-1< or = eta < or = +2) coverage for jets permits separation of Sivers functions for the valence and sea regions. The resulting asymmetries are all consistent with zero and considerably smaller than Sivers effects observed in semi-inclusive deep inelastic scattering. We discuss theoretical attempts to reconcile the new results with the sizable transverse spin effects seen in semi-inclusive deep inelastic scattering and forward hadron production in pp collisions.

Partonic Flow and phi-Meson production in Au+Au collisions at sqrt radical sNN = 200 GeV

We present first measurements of the phi-meson elliptic flow (v2(pT)) and high-statistics pT distributions for different centralities from radical sNN=200 GeV Au+Au collisions at RHIC. In minimum bias collisions the v2 of the phi meson is consistent with the trend observed for mesons. The ratio of the yields of the Omega to those of the phi as a function of transverse momentum is consistent with a model based on the recombination of thermal s quarks up to pT approximately 4 GeV/c, but disagrees at higher momenta. The nuclear modification factor (R CP) of phi follows the trend observed in the K S 0 mesons rather than in Lambda baryons, supporting baryon-meson scaling. These data are consistent with phi mesons in central Au+Au collisions being created via coalescence of thermalized s quarks and the formation of a hot and dense matter with partonic collectivity at RHIC.

Transverse momentum and centrality dependence of high-pT nonphotonic electron suppression in Au+Au collisions at sqrt[s NN]=200 GeV

The STAR collaboration at the BNL Relativistic Heavy-Ion Collider (RHIC) reports measurements of the inclusive yield of nonphotonic electrons, which arise dominantly from semileptonic decays of heavy flavor mesons, over a broad range of transverse momenta (1.2<p(T)<10 GeV/c) in p+p, d+Au, and Au+Au collisions at sqrt[s_{NN}]=200 GeV. The nonphotonic electron yield exhibits an unexpectedly large suppression in central Au+Au collisions at high p(T), suggesting substantial heavy-quark energy loss at RHIC. The centrality and p(T) dependences of the suppression provide constraints on theoretical models of suppression.

Scaling properties of hyperon production in Au+Au collisions at square root [sNN]=200 GeV

We present the scaling properties of Lambda, Xi, and Omega in midrapidity Au+Au collisions at the Brookhaven National Laboratory Relativistic Heavy Ion Collider at sqrt[s_{NN}]=200 GeV. The yield of multistrange baryons per participant nucleon increases from peripheral to central collisions more rapidly than that of Lambda, indicating an increase of the strange-quark density of the matter produced. The strange phase-space occupancy factor gamma_{s} approaches unity for the most central collisions. Moreover, the nuclear modification factors of p, Lambda, and Xi are consistent with each other for 2<p_{T}<5 GeV/c in agreement with a scenario of hadron formation from constituent quark degrees of freedom.

Premature Chromosome Condensation Is Not Essential for Nuclear Reprogramming in Bovine Somatic Cell Nuclear Transfer1

Premature chromosome condensation (PCC) was believed to promote nuclear reprogramming and to facilitate cloning by somatic cell nuclear transfer (NT) in mammalian species. However, it is still uncertain whether PCC is necessary for the successful reprogramming of an introduced donor nucleus in cattle. In the present study, fused NT embryos were subjected to immediate activation (IA, simultaneous fusion and activation), delayed activation (DA, activation applied 4 h postfusion), and IA with aged oocytes (IAA, activation at the same oocyte age as group DA). The morphologic changes, such as nuclear swelling, the occurrence of PCC, and microtubule/aster formation, were analyzed in detail by laser-scanning confocal microscopy. When embryos were subjected to IA in both IA and IAA groups, the introduced nucleus gradually became swollen, and a pronuclear-like structure formed within the oocyte, but PCC was not observed. In contrast, delaying embryo activation resulted in 46.5%-91.2% of NT embryos exhibiting PCC. This PCC was observed beginning at 4 h postcell fusion and was shown as one, two, or multiple chromosomal complexes. Subsequently, a diversity of pronuclear-like structures existed in NT embryos, characterized as single, double, and multiple nuclei. In the oocytes exhibiting PCC, the assembled spindle structure was observed to be an interactive mass, closely associated with condensed chromosomes, but no aster had formed. Regardless of whether they were subjected to IA, IAA, or DA treatments, if the oocytes contained pronuclear-like structures, either one or two asters were observed in proximity to the nuclei. A significantly higher rate of development to blastocysts was achieved in embryos that were immediately activated (IA, 59.1%; IAA, 40.7%) than in those for which activation was delayed (14.2%). The development rate was higher in group IA than in group IAA, but it was not significant (P = 0.089). Following embryo transfer, there was no statistically significant difference in the pregnancy rates (Day 70) between two of the groups (group IA, 11.7%, n = 94 vs. group DA, 12.3%, n = 130; P > 0.05) or live term development (group IA, 4.3% vs. group DA, 4.6%; P > 0.05). Our study has demonstrated that the IA of bovine NT embryos results in embryos with increased competence for preimplantational development. Moreover, PCC was shown to be unnecessary for the reprogramming of a transplanted somatic genome in a cattle oocyte.

96 TRICHOSTATIN A IMPROVED THE QUALITY OF RABBIT NUCLEAR TRANSFER EMBRYOS

Nuclear reprogramming is dependent upon a number of factors, including chromatin organization and modification. Trychostatin A (TSA), a histone deacetylase inhibitor, was used to increase histone acetylation and to improve reprogrammability in both cattle and mice. The objective of the study was to determine whether TSA could improve the pre-implantational development potential of rabbit nuclear transplant (NT) embryos. Rabbit oocytes were flushed from the oviducts of superovulated donors treated with the regime of FSH and hCG. Cumulus cells were then denuded from the oocytes by incubation in 0.5% hyaluronidase and pipetting. Oocyte enucleation was conducted in 10% FBS M199 and confirmed under fluorescence microscopy. Cumulus cells were prepared as nuclear donors for NT; a donor cell with the diameter approximately 15–19 µm was transferred into the perivitelline space of an enucleated oocyte, and subsequently fused with the oocyte recipient by application of 3 direct current pulses at 3.2 kV cm−1 for a duration of 20 µs/pulse. Fused embryos were activated by the same electrical stimulation regime described above, and subsequently cultured in M199 + 10% FBS containing 2.0 mM 6-dimethylaminopurine (DMAP) and 5 µg mL−1 cycloheximide for 1 h. Rabbit NT embryos were cultured in 5 nM TSA-2.5% FBS-B2 medium for 10 h before being transferred into regular medium (FBS-B2). The TSA-treated embryos (5 nM vs. 0 nM) were cultured in 400 µL FBS-B2 medium for 5 days in 5% CO2 in a humidified atmosphere at 38.5°C (initiation of activation = Day 0). NT embryo development to cleaved (2 to 4 cell), morula, and blastocyst stages was evaluated on Day 2, Day 3, and Day 5, respectively. The selected NT blastocysts were counted for cell numbers following Hoechst 33342 epifluorescenin staining. The results (Table 1) showed that there was no difference on pre-implantational development of cloned embryos between TSA-added and control groups (P &gt; 0.05). However, a significantly higher cell number per NT blastocyst was found in the TSA-added group (357 vs. 113; P &lt; 0.05). This indicated that the blastocyst quality in NT embryos was improved with the addition of TSA by increasing histone acetylation activity. The developmental potential of TSA-treated NT embryos to term is under investigation. Table 1.Effects of TSA on the pre-implantational development of cloned rabbit embryos This work was supported by NIH/NCRR-SBIR grant: 1R43RR020261-01.

307 ADDITION OF HIGH CONCENTRATIONS OF HEPARIN DURING IN VITRO FERTILIZATION IMPROVES PERCENTAGES OF CLEAVAGE AND BLASTOCYST FORMATION WHEN BOVINE OOCYTES ARE INSEMINATED IN VITRO WITH SEX-SORTED SPERM

The developmental potential of oocytes fertilized in vitro by sexed–sorted frozen–thawed sperm remains low. The aim of this study was to find an optimal concentration of heparin during IVF using frozen–thawed sex-sorted sperm to improve the percentages of fertilization and blastocyst formation. A total of 1708 matured bovine oocytes were randomly allocated among different concentrations of heparin (0, 2.5, 5, 10, 20, and 40 µg mL−1) in Bracket-Olifant medium and co-incubated with non-sexed or sex-sorted sperm for 6 h (Day 0). The sperm (sorted or not) used for IVF was from one bull of proven fertility. Presumptive zygotes then were cultured in CR1aa + 6 mg mL−1 of BSA in 5% O2, 5% CO2, and 90% N2 at 39°C until Day 8. Percentages of cleavage were recorded on Day 2. Data (3 replicates) were analyzed by ANOVA. The results (Table 1) demonstrated that addition of different concentrations of heparin in IVF medium for non-sexed sperm groups did not alter cleavage and blastocyst formation. However, the lowest percentages of cleavage were observed with 0, 2.5, and 5 µg mL−1 of heparin in sexed sperm groups, demonstrating that high concentrations of heparin (20 and 40 µg mL−1) positively affected the percentages of cleavage and blastocyst formation. A greater proportion of zygotes in 20 and 40 µg mL−1 sexed sperm groups developed into grade 1 blastocysts on Day 7, and subsequently formed more blastocysts on Day 8 compared with 0, 2.5, and 5 µg mL−1 of heparin in sexed sperm groups. In conclusion, addition of heparin was not necessary when frozen–thawed non-sexed sperm were used for IVF with this particlar bull. However, addition of higher concentrations of heparin during IVF improved fertilization and blastocyst formation in vitro (40 µg mL−1 of heparin could be used as an alternative concentration for frozen–thawed sex-sorted sperm with this particular bull). The incidence of polyspermy as well as polyploidy in blastocysts is currently being studied. Table 1.Effect of heparin concentrations during IVF on cleavage and blastocyst formation

Longitudinal double-spin asymmetry and cross section for inclusive jet production in polarized proton collisions at square root of s = 200 GeV

We report a measurement of the longitudinal double-spin asymmetry A(LL) and the differential cross section for inclusive midrapidity jet production in polarized proton collisions at square root of s = 200 GeV. The cross section data cover transverse momenta 5 < pT < 50 GeV/c and agree with next-to-leading order perturbative QCD evaluations. The A(LL) data cover 5 < pT < 17 GeV/c and disfavor at 98% C.L. maximal positive gluon polarization in the polarized nucleon.

Direct observation of dijets in central Au+Au collisions at sqrt[sNN]=200 GeV

The STAR Collaboration at the Relativistic Heavy Ion Collider reports measurements of azimuthal correlations of high transverse momentum (pT) charged hadrons in Au+Au collisions at higher pT than reported previously. As (pT) is increased, a narrow, back-to-back peak emerges above the decreasing background, providing a clear dijet signal for all collision centralities studied. Using these correlations, we perform a systematic study of dijet production and suppression in nuclear collisions, providing new constraints on the mechanisms underlying partonic energy loss in dense matter.

Identified baryon and meson distributions at large transverse momenta from Au + Au collisions at square root sNN=200 GeV

Transverse momentum spectra of pi+/-, p, and p up to 12 GeV/c at midrapidity in centrality selected Au + Au collisions at square root sNN=200 GeV are presented. In central Au + Au collisions, both pi +/- and p(p) show significant suppression with respect to binary scaling at pT approximately >4 GeV/c. Protons and antiprotons are less suppressed than pi+/-, in the range 1.5 approximately < pT approximately < 6 GeV/c. The pi-/pi+ and p/p ratios show at most a weak pT dependence and no significant centrality dependence. The p/pi ratios in central Au + Au collisions approach the values in p + p and d + Au collisions at pT approximately >5 GeV/c. The results at high pT indicate that the partonic sources of pi+/-, p, and p have similar energy loss when traversing the nuclear medium.

Forward neutral pion production in p + p and d + Au collisions at square root sNN=200 GeV

Measurements of the production of forward pi0 mesons from p + p and d + Au collisions at square root sNN=200 GeV are reported. The p + p yield generally agrees with next-to-leading order perturbative QCD calculations. The d + Au yield per binary collision is suppressed as eta increases, decreasing to approximately 30% of the p + p yield at eta =4.00, well below shadowing expectations. Exploratory measurements of azimuthal correlations of the forward pi0 with charged hadrons at eta approximately 0 show a recoil peak in p + p that is suppressed in d + Au at low pion energy. These observations are qualitatively consistent with a saturation picture of the low-x gluon structure of heavy nuclei.

Strange baryon resonance production in sqrt s NN=200 GeV p+p and Au+Au collisions

We report the measurements of Sigma(1385) and Lambda(1520) production in p+p and Au+Au collisions at sqrt[s{NN}]=200 GeV from the STAR Collaboration. The yields and the p(T) spectra are presented and discussed in terms of chemical and thermal freeze-out conditions and compared to model predictions. Thermal and microscopic models do not adequately describe the yields of all the resonances produced in central Au+Au collisions. Our results indicate that there may be a time span between chemical and thermal freeze-out during which elastic hadronic interactions occur.

Developmental potential of vitrified holstein cattle embryos fertilized in vitro with sex-sorted sperm

In vitro fertilization (IVF) is a feasible way to utilize sex-sorted sperm to produce offspring of a predetermined sex in the livestock industry. The objective of the present study was to examine the effects of various factors on bovine IVF and to systematically improve the efficiency of IVF production using sex-sorted sperm. Both bulls and sorting contributed to the variability among differential development rates of embryos fertilized by sexed sperm. Increased sorting pressures (275.8 to 344.75 kPa) did not have a significant effect on the in vitro fertility of the sorted sperm; neither did an extended period of 9 to 14 h from semen collection to sorting. As few as 600 sorted sperm were used to fertilize an oocyte, resulting in blastocyst development of 33.2%. Postwarming of vitrified sexed IVF embryos resulted in high morphological survival (96.3%) and hatching (84.4%) rates, similar to those fertilized by nonsexed sperm (93.1 and 80.6%, respectively). A 40.9% pregnancy rate was established following the transfer of 3,627 vitrified, sexed embryos into synchronized recipients. This was not different from the rates with nonsexed IVF (41.9%, n = 481), or in vivo-produced (53.1%, n = 192) embryos. Of 458 calves born, 442 (96.5%) were female and 99.6% appeared normal. These technologies (sperm sexing-IVF-vitrification-embryo transfer) provide farmers, as well as the livestock industry, with a valuable option for herd expansion and heifer replacement programs. In summary, calves were produced using embryos fertilized by sex-sorted sperm in vitro and cryopreserved by rapid cooling vitrification.

Prolonging bovine sperm-oocyte incubation in modified medium 199 improves embryo development rate and the viability of vitrified blastocysts

This study was conducted to compare the efficacy of four in vitro fertilization (IVF) media: Bracket and Oliphant's medium (BO), modified medium 199 (IVF-M199), modified Tyrode's medium (MTM), and modified KSOM (m-KSOM) on fertilization efficiency and blastocyst formation rate. In addition, we wanted to investigate the benefit of prolonging the IVF period (from 6 to 18 h) using the two most effective IVF media determined in our initial experiment; subsequently, blastocyst viability was assessed following vitrification. A higher incidence of polyspermic fertilization was observed in the MTM (6%) and in BO, in both the 6 and 18 h (7% and 11%, respectively) groups, than in the m-KSOM (1%) or in the IVF-M199 6 or 18 h (1 and 3%, respectively) groups. Cleavage rates were similar in BO, IVF-M199, and MTM 48 h post-fertilization; however, the lowest cleavage rate was observed for m-KSOM. A greater proportion of zygotes developed into 8-cell embryos in IVF-M199 than in other IVF media. Subsequently, a greater proportion of blastocyst formation and hatching was achieved in IVF-M199 (40% and 79%, respectively) or BO (35% and 74%, respectively) than in m-KSOM (18% and 58%, respectively) or MTM (22% and 66%, respectively). Prolonging IVF to 18 h did not alter cleavage rates; however, the highest rate of overall blastocyst formation was achieved in the IVF-M199 18 h (49%), rather than in the BO 18 h (20%) group. Vitrified/thawed blastocysts from IVF-M199 groups re-expanded and developed better, as compared to the BO 18 h group, and hatching rate and total cell number in IVF-M199 18 h group was comparable to the control groups (non-vitrified). Vitrification reduced survival compared to controls. In conclusion, IVF-M199 was successfully used for IVF, compared favorably to BO medium, and offered the advantage of an extended IVF period for up to 18 h that requires only one-half a dose of semen, and resulted in better quality blastocysts that endured vitrification with a hatching rate comparable to that of control groups.

Higher survival rate of vitrified and thawed in vitro produced bovine blastocysts following culture in defined medium supplemented with β-mercaptoethanol

The present study was conducted to compare bovine embryo developmental quality, after culture in different defined culture media, up to blastocyst stage, and subsequently cultured in media supplemented with beta-mercaptoethanol (beta-ME) following blastocyst vitrification and thawing. In part one of this study, presumptive zygotes were randomly allocated into the following media: (1) CR1, (2) KSOM, (3) SOF, and (4) sequential KSOM-SOF. In the second part of the study, blastocysts derived from four different culture media were subjected to a solid surface vitrification (35% (v/v) ethylene glycol+0.5M Sucrose+5% (w/v) Polyvinylpyrrolidone (PVP), and tested for the effect of beta-ME on their post-vitrification survival. Following thawing, blastocysts were cultured with or without beta-ME. Culture medium had no effect on cleavage rates; however, a significantly greater number of zygotes cultured in KSOM, KSOM-SOF, or SOF developed to the 8-cell stage, compared with those cultured in CR1. A greater proportion of the zygotes cultured in SOF or KSOM-SOF reached blastocysts, than did those cultured in CR1 or KSOM. The use of sequential KSOM-SOF significantly increased total cell numbers of Day 7 expanded-blastocysts when compared to those cultured in CR1, KSOM, or SOF. Addition of beta-ME into culture media after vitrification and thawing improved blastocyst survival, hatching rates, and total cell numbers of blastocysts. In conclusion, supplementation of beta-ME into culture medium after vitrification and thawing significantly increased blastocyst survival, hatching rates, and their total cell numbers. These results suggest that vitrified IVF embryos should be thawed and briefly cultured in beta-ME medium prior to embryo transfer.