157 PREGNANCIES AND CALVES AFTER TRANSFER OF IN VITRO-PRODUCED RIVER BUFFALO EMBRYOS AFTER CRYOPRESERVATION

In the buffalo, the use of embryo-based biotechnologies for breeding and genetic improvement is still very limited because multiple-ovulation embryo transfer delivers poor results compared with cattle and in vitro embryo production has been used mainly for research purposes. At present, very few reports are available on the transfer of in vitro-produced (IVP) and cryopreserved buffalo embryos. Therefore, the scope of this work was to perform a pilot study to evaluate the viability of frozen-thawed IVP embryos by nonsurgical embryo transfer to recipients in an IVF-embryo transfer program on a farm located on the north coast of Colombia, South America. Buffalo oocytes were recovered at the slaughterhouse from selected donors, matured in vitro for 18 to 20 h in TCM-199 + 10% FCS and 0.5 IU of FSH and 0.5 IU of LH in 5% CO2 at 38.5°C. Four different bulls were used for IVF. After thawing, the semen was separated on a Percoll® gradient and then diluted into SOF-IVF media supplemented with 1 μg mL–1 of heparin and phenylalanine. Presumptive zygotes were cultured in modified SOF supplemented with MEM amino acids for 6 days. Half of the medium was replaced on Day 4 and 6. Developing embryos were selected for freezing on Day 6 and 7. Grade 1 embryos were frozen at the blastocyst stage by slow cooling in 10% glycerol or 1.5 M ethylene glycol. Recipients (heifers n = 79 and uniparous cows n = 17) were synchronized using the CIDR-Synch protocol: on Day 0, gonadotropin-releasing hormone was injected and a CIDR was inserted; on Day 7, prostaglandin F2α was administered; on Day 9, the CIDR was removed; on Day 11, a second injection of gonadotropin-releasing hormone was given; and on Day 17, the embryo was transferred. Each female received, nonsurgically, 1 or 2 embryos in the ipsilateral horn to the functional corpus luteum evaluated by ultrasonography. Pregnancies were evaluated by ultrasonography 30 days after transfer and confirmed by rectal palpation 30 days later. This work was performed in 2 successive experiments during the breeding seasons (January and December, respectively). Overall, 96 recipients were transferred, with 136 embryos obtaining 23 pregnancies (24.2%). There were no statistical differences in pregnancy rate between heifers and cows (25.3 vs 17.7%) and between single (n = 56) and double (n = 39) embryo transfers (21.4 vs 27.5%) by chi square test (P > 0.05). To date, 4 females and 5 males have been born by spontaneous calving (1 stillborn male due to dystocia), 3 pregnancies have been aborted (13%) and 11 pregnancies are ongoing (>7 months). The pregnancy rate obtained in this study in farm conditions (24.2%) is lower than generally obtained with frozen IVP cattle embryos, but it is still a good result in buffalo, where even conventional AI provides a lower success rate as compared with cattle. Finally, this work demonstrates that in vitro embryo production can be successfully implemented in buffalo breeding programs for the exploitation of superior genetics. This work was supported by Regione Lombardia, Por Fers 2007–2013, n°13827741, InnovaB.

234 EFFICIENT EXPRESSION OF HUMAN ENDOTHELIAL PROTEIN C RECEPTOR AND HUMAN THROMBOMODULIN IN TRANSFECTED PIG PRIMARY hCD55+-GAL–/– FIBROBLASTS USING F2A EXPRESSION VECTOR

The genetic engineering of the pig genome for xenotransplantation studies requires the insertion of different transgenes to create multi-transgenic pigs. In order to simultaneously add more transgene in a single genetic insertion, we constructed a polycistronic vector using the F2A self-cleaving peptide. Moreover, this solution has the added advantages of preventing possible segregation during breeding of the animals and of guaranteeing an equimolar production of chosen transgenes. The scope of this work was the construction and validation of an ubiquitous F2A-bicistronic expression vector for human thrombomodulin (hTM) and human endothelial protein C receptor (hEPCR) genes in pig primary hCD55-GAL–/– cells to establish transgenic fibroblasts colonies, to be used for somatic cell nuclear transfer (SCNT) to generate pigs for xenotransplantation research. The expression vector consisted of pCAGGS promoter (CMV-IE+chicken β actin) followed by hEPCR-furinF2A-hTM coding sequence. The resulting expression cassette was inserted between 2 insulators obtained from the 5′ MAR region of chicken lysozyme. Outside of this insulated structure, there is a loxable puromycin selection cassette. The resulting purified and linearized expression vector (pEFTM/Lgu I = 5 μg) was transfected into hCD55-GAL–/– primary fibroblasts (1 × 106), using Nucleofector (Amaxa, Lonza, Cologne, Germany), in parallel for comparative purposes we cotransfected the 2 pCAGGS-monocistronic vectors for the same transgenes (hEPCR and hTM = 1:3, 5 μg). Transfected cells were selected with puromycin (1 μg mL–1) for 15 days. After 8 days of selection, resistant colonies were picked up and expanded into 24-well plates for cryopreservation and analyses. Bicistronic transfection produced 20 clones and cotransfection only 8 clones that were analysed by Western blot (WB) and by immunocytochemistry (ICC) using polyclonal antibody anti-EPCR (1:250, R&D) and monoclonal antibody ab6980-Abcam (1:5000, Abcam, Cambridge, UK) in WB; polyclonal antibody RCR252 (1:100, Sigma-Aldrich, St. Louis, MO, USA) and monoclonal antibody ab6980-Abcam (1:100, Abcam) for ICC. Seventeen bicistronic clones (85%) and 2 cotransfected monocistronic clones (25%) were positive for both transgenes using WB. After ICC analyses, only 11 bicistronic colonies (55%) and 1 cotransfected colony (12.5%) uniformly expressed the desired transgenes and were selected for SCNT. The pCAGGS promoter maintained its strong expression also using the hEPCR-FurinF2A-hTM coding sequence and this bicistronic solution permitted us to improve our results obtained with co-transfection. Availability of hEPCR+ hTM+ hCD55+-GAL–/– colonies will allow us to obtain a new transgenic background for future xenotransplantation projects. This study was supported by EU grant no. LSHB-CT-2006-037377 (Xenome) and by Regione Lombardia (Superpig project).

198 CILOSTAMIDE SUSTAINS GAP JUNCTION-MEDIATED COMMUNICATION AND CHROMATIN REMODELLING IN PIG OOCYTES

In the pig, the efficiency of in vitro embryo production procedures is still limited. It has been suggested that prematuration treatments could improve the developmental capability of oocytes. In particular, recent studies conducted in the bovine (Luciano, 2011, BOR, in press) indicate that the prolongation of a patent bidirectional crosstalk between the oocyte and the surrounding cumulus cells, together with the maintenance of a proper level of cAMP during the prematuration culture, could be beneficial to oocytes that have not yet acquired full meiotic and developmental capability. The aim of the present study was to assess the effect of treatment with cilostamide, an inhibitor of the phosphodiesterase 3 (PDE3), which degrades cAMP, on the functional status of gap junction-mediated communication (GJC) in pig cumulus–oocyte complexes (COC). Moreover, since chromatin configuration represents a marker of oocyte differentiation and competence, the effect of cilostamide on the process of chromatin remodeling was also evaluated during the culture period. To this aim, COC were collected from 3- to 6-mm antral follicles and cultured for up to 24 h in defined culture medium supplemented with 0.1 IU mL–1 of FSH in the presence or absence of 1 μM cilostamide. The GJC functionality was assessed by Lucifer Yellow fluorescent dye microinjection at the time of collection (0 h) and after 12, 18, or 24 h of culture. Chromatin configuration was evaluated by fluorescence microscopy after removal of cumulus cells and DNA staining with Hoechst and oocytes were classified according to Bui et al. (2004 BOR 70, 1843–1851) as SC, (with stringy chromatin within the germinal vesicle), GVI (with chromatin condensed in a rim around the nucleolus), GVII-IV (where the beginning of formation of chromatin strands is typical), ProMI (prometaphase I) and MI (metaphase I). The administration of cilostamide sustained functional coupling for up to 24 h of culture as the percentage of COC with open GJC was significantly higher when compared with the control group (62.2% vs 30%; P < 0.05) and not significantly different from the time 0 h (80%). The maintenance of the coupling during the culture period was accompanied by a delay of the meiotic resumption as only 26.3% of cilostamide-treated oocytes underwent germinal-vesicle breakdown and reached ProMI stage compared to the control group (62.1%; P < 0.05). Moreover the transition towards advanced stages of differentiation, as judged by the chromatin configuration, was slowed down in the presence of cilostamide. In conclusion, our study indicates that the maintenance of elevated cAMP levels through the inhibition of PDE3 sustains a functional bidirectional communication between the oocyte and cumulus cells and delays meiotic resumption in the pig oocyte. This could be a useful approach for the development of prematuration treatments aimed at improving the embryonic developmental potential of pig oocytes. Experiments are in progress in our laboratories to confirm this hypothesis. This study has been supported by EU FP6 grant n LSHB-CT-2006-037377 (Xenome) EU FP7- n°223485 (Plurisys).

The RANKL distal control region is required for the increase in RANKL expression, but not the bone loss, associated with hyperparathyroidism or lactation in adult mice

Osteoclast-mediated bone resorption plays an essential role in calcium homeostasis and lactation. The cytokine receptor activator of nuclear factor κB ligand (RANKL) is one of a number of factors that controls the production, survival, and activity of osteoclasts. Calciotropic hormones, such as PTH, control RANKL transcription in part via an enhancer known as the distal control region (DCR), and mice lacking this enhancer have fewer osteoclasts under normal physiological conditions. Here, we have addressed the role of the DCR in situations in which activation of the PTH receptor is thought to stimulate bone resorption via elevation of RANKL expression. Dietary calcium deficiency stimulated RANKL expression in the bone of young (1 month old) wild-type, but not DCR knockout (KO), mice. Consistent with this, the cancellous bone loss and the increase in osteoclasts caused by dietary calcium deficiency were blunted in young KO mice. DCR deletion also prevented the increase in RANKL expression caused by dietary calcium deficiency in 6-month-old mice. However, the diet-induced bone loss was similar in wild-type and KO mice at this age. The increase in RANKL expression caused by lactation was also blunted in DCR KO mice, but lactation-induced bone loss was similar in both genotypes. These results demonstrate that, even though the DCR is required for the increase in RANKL expression associated with hyperparathyroidism or lactation, this increase is not required for the bone loss caused by these conditions in adult mice, suggesting that changes in other factors, such as osteoprotegerin or estrogen levels, play a dominant role.

Serum hepatitis B surface antigen monitoring in long-term lamivudine-treated hepatitis B virus patients

Serum hepatitis B virus surface antigen (HBsAg) levels have been suggested to predict interferon response in chronic hepatitis B. A few data are available on the role of HBsAg measurement in nucleos(t)ide analogues (NA) treatment. We retrospectively investigated the relation between HBsAg changes and main treatment outcomes during long-term lamivudine treatment in hepatitis e antigen (HBeAg)-negative chronic hepatitis B. A total of 42 HBeAg-negative patients were consecutively enrolled in an open-label study on long-term lamivudine monotherapy (150 mg/die). Serum HBsAg levels were quantified every 6 months by Architect assay (Abbott Diagnostics). HBV-DNA was quantified quarterly by real-time PCR (Roche Diagnostics). The median duration of lamivudine treatment was 66 months (20-153). One patient (2%) was a primary nonresponder, 35 (83%) developed virological breakthrough (VB) and the remaining six patients (14%) were classified as long-term on-treatment responders. During treatment, HBsAg levels decreased only in long-term on-treatment responders, while no changes were observed in resistant patients. Failure to achieve a decrease of 0.7 log(10) IU/mL in serum HBsAg at month six of lamivudine had a positive predictive value of developing VB of 90% and a negative predictive value of 100%. These high predictive values were also maintained in the subgroup of patients negative for HBV-DNA at month six. The results of this study with a small sample size suggest a role of on-treatment HBsAg quantification in the management of lamivudine-treated patients. If validated prospectively in a larger patient cohort, HBsAg measurements would be a useful adjunct to optimize antiviral therapy.

Serum hepatitis B surface antigen monitoring in long-term lamivudine-treated hepatitis B virus patients

Serum hepatitis B virus surface antigen (HBsAg) levels have been suggested to predict interferon response in chronic hepatitis B. A few data are available on the role of HBsAg measurement in nucleos(t)ide analogues (NA) treatment. We retrospectively investigated the relation between HBsAg changes and main treatment outcomes during long-term lamivudine treatment in hepatitis e antigen (HBeAg)-negative chronic hepatitis B. A total of 42 HBeAg-negative patients were consecutively enrolled in an open-label study on long-term lamivudine monotherapy (150 mg/die). Serum HBsAg levels were quantified every 6 months by Architect assay (Abbott Diagnostics). HBV-DNA was quantified quarterly by real-time PCR (Roche Diagnostics). The median duration of lamivudine treatment was 66 months (20-153). One patient (2%) was a primary nonresponder, 35 (83%) developed virological breakthrough (VB) and the remaining six patients (14%) were classified as long-term on-treatment responders. During treatment, HBsAg levels decreased only in long-term on-treatment responders, while no changes were observed in resistant patients. Failure to achieve a decrease of 0.7 log(10) IU/mL in serum HBsAg at month six of lamivudine had a positive predictive value of developing VB of 90% and a negative predictive value of 100%. These high predictive values were also maintained in the subgroup of patients negative for HBV-DNA at month six. The results of this study with a small sample size suggest a role of on-treatment HBsAg quantification in the management of lamivudine-treated patients. If validated prospectively in a larger patient cohort, HBsAg measurements would be a useful adjunct to optimize antiviral therapy.

PTH receptor signaling in osteocytes governs periosteal bone formation and intracortical remodeling

The periosteal and endocortical surfaces of cortical bone dictate the geometry and overall mechanical properties of bone. Yet the cellular and molecular mechanisms that regulate activity on these surfaces are far from being understood. Parathyroid hormone (PTH) has profound effects in cortical bone, stimulating periosteal expansion and at the same time accelerating intracortical bone remodeling. We report herein that transgenic mice expressing a constitutive active PTH receptor in osteocytes (DMP1-caPTHR1 mice) exhibit increased cortical bone area and an elevated rate of periosteal and endocortical bone formation. In addition, DMP1-caPTHR1 mice display a marked increase in intracortical remodeling and cortical porosity. Crossing DMP1-caPTHR1 mice with mice lacking the Wnt coreceptor, LDL-related receptor 5 (LRP5), or with mice overexpressing the Wnt antagonist Sost in osteocytes (DMP1-Sost mice) reduced or abolished, respectively, the increased cortical bone area, periosteal bone formation rate, and expression of osteoblast markers and Wnt target genes exhibited by the DMP1-caPTHR1 mice. In addition, DMP1-caPTHR1 lacking LRP5 or double transgenic DMP1-caPTHR1;DMP1-Sost mice exhibit exacerbated intracortical remodeling and increased osteoclast numbers, and markedly decreased expression of the RANK decoy receptor osteoprotegerin. Thus, whereas Sost downregulation and the consequent Wnt activation is required for the stimulatory effect of PTH receptor signaling on periosteal bone formation, the Wnt-independent increase in osteoclastogenesis induced by PTH receptor activation in osteocytes overrides the effect on Sost. These findings demonstrate that PTH receptor signaling influences cortical bone through actions on osteocytes and defines the role of Wnt signaling in PTH receptor action.

How is the reactivity of laccase affected by single-point mutations? Engineering laccase for improved activity towards sterically demanding substrates

In spite of its broad specificity among phenols, Trametes versicolor laccase hardly succeeds in oxidizing hindered substrates. To improve the oxidation ability of this laccase towards bulky phenolic substrates, we designed a series of single-point mutants on the basis of the amino-acid layout inside the reducing substrate active site known from the crystal structure of the enzyme. Site-directed mutagenesis has addressed four phenylalanine residues in key positions 162, 265, 332, and 337 at the entrance of the binding pocket, as these residues appeared instrumental for docking of the substrate. These phenylalanines were replaced by smaller-sized but still apolar alanines. A double mutant F162A/F332A was also designed. Measurement of the oxidation efficiency towards encumbered phenols has shown that mutant F162A was more efficient than the wild-type laccase. The double mutant F162A/F332A led to 98% consumption of bisphenol A in only 5 h and was more efficient than the single mutants in the aerobic oxidation of this bulky substrate. In contrast, lack of appropriate hydrophobic interactions with the substrate possibly depresses the oxidation outcome with mutants F265A and F332A. One explanation for the lack of reactivity of mutant F337A, supported by literature reports, is that this residue is part of the second coordination shell of T1 Cu. A mutation at this position thus leads to a drastic coordination shell destabilization. Thermal stability of the mutants and their resistance in a mixed water-dioxane solvent have also been investigated.

Rough surface topography enhances the activation of Wnt/β-catenin signaling in mesenchymal cells

It is known that the roughness of titanium surfaces affects cell proliferation and differentiation. However, the mechanisms mediating the cellular responses to surface topography are only partially understood. The present study investigated whether Wnt canonical signaling, an important pathway in determining cell fate, is modulated by surface roughness. This study analyzed the behavior of the murine C2C12 mesenchymal cell line on polished or acid-etched, sand-blasted (SLA) commercially pure titanium. When we transfected cells with Wnt3a or wild-type β-catenin and a reporter construct, we found that stimulation of Wnt canonical signaling was enhanced in cells on SLA surfaces. Moreover, more β-catenin translocated to the nucleus in cells on SLA surfaces after stimulation with Wnt3a as evidenced by immunofluorescence. However, when cells were transfected with constitutively active S33Y β-catenin mutant, no difference was observed between the groups. Higher levels of transcripts of Wnt target genes were detected in C2C12 cells cultured on SLA surfaces following transfection with Wnt3a, but the expression of a gene regulating β-catenin degradation, Axin 2, was reduced on SLA surfaces. Inhibition of β-catenin mediated transcription by dnTCF in murine osteoblastic MC3T3 cells, reversed the effects of topography on cell differentiation. Taken together, these results show that surface roughness modulates the responsiveness of mesenchymal cells to Wnt3a, that this requires the control of β-catenin degradation, and that the control of β-catenin signaling by surface topography is accountable for at least part of the effects of surface on cell differentiation.

FoxOs, Wnts and oxidative stress-induced bone loss: new players in the periodontitis arena?

BACKGROUND AND OBJECTIVE

Chronic periodontitis is a widespread disease affecting tooth-supporting structures that can lead to extensive loss of periodontal ligament and bone, ultimately resulting in tooth loss. Extensive evidence has demonstrated a strong association between age, metabolic disorders such as type II diabetes, oxidative stress and alveolar bone loss. The molecular players controlling bone maintenance and underlying age-related bone loss and its links to the general metabolism are currently the object of intense research.

MATERIAL AND METHODS

Recent findings are summarized to elucidate the molecular mechanisms linking oxidative stress, bone loss and metabolic factors.

RESULTS

It is well known that reactive oxygen species are an inevitable consequence of cellular respiration and that organisms have developed an efficient array of defenses against them. The core of this complex defense line is a family of transcription factors, known as FoxOs, which can bind to β-catenin and initiate a transcriptional programme regulating cell apoptosis, DNA repair and degradation of reactive oxygen species. An increase in reactive oxygen species due, for example, to age or insulin resistance, generates a situation in which bone formation is impaired by activation of FoxO, and a decrease in Wnt signaling and bone resorption are promoted.

CONCLUSION

The balance between FoxO and the Wnt pathway is finely tuned by systemic and local factors, creating a far-reaching mechanism that dictates the fate of mesenchymal progenitors and regulates the homeostasis of bone, providing a rationale for the impairment of systemic and alveolar bone maintenance clinically observed with age and metabolic diseases.

Embryonic genotype and inbreeding affect preimplantation development in cattle

Infertility in cattle herds is a growing problem with multifactorial causes. Embryonic genotype and level of inbreeding are among the many factors that can play a role on reproductive efficiency. To investigate this issue, we produced purebred and crossbred bovine embryos by in vitro techniques from Holstein oocytes and Holstein or Brown Swiss semen and analyzed several cellular and molecular features. In the first experiment, purebred and crossbred embryos, obtained from abattoir oocytes, were analyzed for cleavage, development to morula/blastocyst stages, amino acid metabolism and gene expression of developmentally important genes. The results indicated significant differences in the percentage of compacted morulae, in the expression of three genes at the blastocyst stage (MNSOD, GP130 and FGF4) and in the utilization of serine, asparagine, methionine and tryptophan in day 6 embryos. In the second experiment, bovine oocytes were collected by ovum pick up from ten Holstein donors and fertilized with the semen of the respective Holstein sires or with Brown Swiss semen. The derived embryos were grown in vitro up to day 7, and were then transferred to synchronized recipients and recovered on day 12. We found that purebred/inbred embryos had lower blastocyst rate on days 7-8, were smaller on day 12 and had lower expression of the trophoblast gene PLAC8. Overall, these results indicate reduced and delayed development of purebred embryos compared with crossbred embryos. In conclusion, this study provides evidence that embryo genotype and high inbreeding can affect amino acid metabolism, gene expression, preimplantation development and therefore fertility in cattle.

Titanium Topography Controls FoxO/β-catenin Signaling

Little is known about how surface topography can modulate mesenchymal cell responses to oxygen-related stress occurring with age, or during the early phases of wound healing or inflammation. To antagonize Reactive Oxygen Species (ROS), cells resort to defense mechanisms, relying on β-catenin, a molecular switch between a TCF-mediated pathway, which promotes cells proliferation and commitment, and an alternative one controlled by FoxO, which induces quiescence and defenses against ROS. In the present study, we show that mesenchymal C2C12 cells are protected from H2O2-induced oxidative stress when they grow on rough (SLA) titanium surfaces. The expression of anti-ROS genes and FoxO/β-catenin signaling, as measured by a reporter assay, were increased on SLA surfaces. We also show that TCF-mediated transcription was inhibited by ROS in cells growing on either smooth or SLA titanium. Our results demonstrate that surface topography modulates cell resistance to ROS and the balance between the molecular pathways regulating cell growth and cell defense against oxidative stress.

43 SHORT- AND LONG-LASTING EFFECTS OF TRICHOSTATIN A TREATMENT OF SCNT EMBRYOS IN CATTLE

Both preimplantation and full-term development of mouse somatic cell nuclear transfer (SCNT) embryos are significantly enhanced by treatment with trichostatin A (TSA), an inhibitor of histone deacetylase (Kishigami et al. 2006 Biochem. Biophys. Res. Commun. 340, 183–189; Rybouchkin et al. 2006 Biol. Reprod. 74, 1083–1089). The present study was designed to examine the effect of TSA treatment on preimplantation and full-term development of bovine cloned embryos. To investigate the effect of TSA on bovine NT embryos development, we treated them with 50 nM TSA during the first 10 h after activation. Bovine NT-embryos were reconstructed using adult fibroblasts of 2 female donors (A and B) with significantly different in vitro cloning efficiency (respectively, 84/245; 34.3% v. 155/298; 52.1% blastocyst D7, P ≤ 0.05, chi-square test). TSA treatment significantly improved blastocyst rate in A, however did not affect development in B (56.3% and 50.5%, respectively). The level of acetylated histone H3K9 10 h after activation detected by anti-acH3K9 antibody was significantly increased after TSA-treatment in A (P ≤ 0.05, Student’s t-test) but did not change in B, thus demonstrating that the levels of histone acetylation in cloned embryos correlate with their in vitro developmental potential. To evaluate the long-lasting effect of TSA-treatment on the full-term development of cloned embryos, SCNT embryos derived from 4 female donor animals were reconstructed. 196 TSA-treated embryos at the blastocyst stage were transferred into 98 recipients and 2 calves (2%) were born. In the control group, 167 embryos were transferred into 141 recipients and 3 calves (2.1%) were born. Our data show that cell lines demonstrate different susceptibility to TSA that may affect reprogramming of the somatic genome with low level of acetylation resulting in higher in vitro embryo development. However, TSA does not improve overall cloning efficiency in cattle, measured as full-term development. Project partly supported by EU grants Plurisys (n 22348), Xenome (LSHB-CT-2006-037377) and Regione Lombardia.

Precision genetics for complex objectives in animal agriculture

Indirect modification of animal genomes by interspecific hybridization, cross-breeding, and selection has produced an enormous spectrum of phenotypic diversity over more than 10,000 yr of animal domestication. Using these established technologies, the farming community has successfully increased the yield and efficiency of production in most agricultural species while utilizing land resources that are often unsuitable for other agricultural purposes. Moving forward, animal well-being and agricultural sustainability are moral and economic priorities of consumers and producers alike. Therefore, these considerations will be included in any strategy designed to meet the challenges produced by global climate change and an expanding world population. Improvements in the efficiency and precision of genetic technologies will enable a timely response to meet the multifaceted food requirements of a rapidly increasing world population.

377 EMBRYO PRODUCTION BY OVUM PICKUP-INTRACYTOPLASMIC SPERM INJECTION-IVC IN AN EQUINE OVUM PICKUP PROGRAM USING SEMEN FROM FERTILE AND INFERTILE STALLIONS

The introduction in equine reproduction of ovum pickup (OPU) combined with intracytoplasmic sperm injection (ICSI), IVC, and embryo transfer, has allowed for the production of offspring from donors and stallions that could not reproduce by conventional techniques. For this reason, we used in our OPU-ICSI-IVC program both fertile stallions and stallions with field records of low or no fertility. Overall, 805 and 584 OPU oocytes were fertilized with sperm from fertile and infertile stallions, respectively. Cleavage rate was statistically lower in the latter group (65.94 v. 59.24%, chi square test; P < 0.05) but embryo development was similar (11.67 v. 8.20% blastocysts/injected oocytes, chi-square test). In order to further investigate the stallion effect on embryo development, we selected 3 stallions with low (A) or no (B, C) fertility in the field and we compared the results of the OPU program with embryo development obtained using oocytes recovered from abattoir ovaries and matured, fertilized, and cultured in vitro as the OPU oocytes. Part of the abattoir oocytes was fertilized with a stallion with known high fertility both in vivo and in vitro (abattoir fertile). Overall, the results (shown in the table) suggest a reduction in the efficiency of stallions A, B, and C compared with to the fertile stallion used as control (10.79, 7.69, and 5.0% v. 17.35%, respectively). For stallions A and B, the efficiency was further reduced in the OPU setting, indicating that the female component can play a role in the overall efficiency of the procedure. In particular, 4 mares out of 8 had a history of no pregnancy and all mares had some rate of inbreeding with the respective stallion used for the ICSI. Instead, the oocytes from the abattoir ovaries were collected in large pools from several mares, representing an average oocyte quality, and the mares were of different breed than the stallions. All data were analyzed by chi-square test and significance was set at P < 0.05. In conclusion, we demonstrated that, for those stallions in which fertility in the field is low or absent, OPU-ICSI-IVP is a suitable choice to obtain embryos, although the efficiency is variable depending not only on the stallion but also on the origin of the oocytes. Table 1.Stallion effect on embryo development of ovum pickup (OPU) and abattoir oocytes This work was supported by Fondazione Cariplo and Regione Lombardia.

431 GENERATION OF CLONED CD55-CD39 TRANSGENIC α1,3-GALACTOSYLTRANSFERASE DEPLETED (GAL - / - ) PIGLETS

Success in xenotransplantation relies on engineering of the pig genome to express human transgenes, such as CD55/CD39, that can control coagulation and inflammation to prolong the graft survival of a 1,3-galactosyltransferase depleted (Gal-/-) pig organs in nonhuman primates and then able to bypass the hyperacute rejection. The aim of our work was to produce Gal-/- piglets overexpressing CD55/CD39. In experiment (Exp.) 1 exploiting 2 ubiquitous expression vectors (pCAGGS-CD55 and pCAGGS-CD39), we transfected immortalized porcine kidney cells (PK15) with CD55 and CD39 using Nucleofector (Amaxa Biosystems, Cologne, Germany) and selected 5 cell colonies each (PK15-CD55 and PK15-CD39) that were expanded and analyzed by RT-PCR, immunohistochemistry (IHC) and Western blot (WB). The monoclonal antibodies IA10 for hCD55 and BU61 for hCD39 were used. Transgenic transcription was confirmed by Northern blot (NB) using digoxigenin-labeled probes. In Exp. 2, a neonatal pig Gal-/- fibroblast line was co-transfected by Nucleofector using 2 ubiquitous expression vectors (hEF-CD55 and pCAGGS-CD39) for the expression of CD55 and CD39. Colonies were analyzed by RT-PCR and IHC only, because of the limited number of cells available. Cells from one colony with a high level of CD55/CD39 expression according to IHC were used for nuclear transfer into enucleated oocytes. Day 5 compact morula/blastocyst (n = 144) were transplanted in 2 synchronized sows. Porcine aortic endothelial cells (PAEC) and fibroblasts derived from 2 stillborn piglets were analysed with IHC, NB, and WB. The expression level of transgenes from both experiments was compared with human umbilical vein endothelial cells (HUVEC) by fluorescence-activated cell sorting (FACS), using IA10, BRIC110, IH4, 2G2, and MEM-118 antibodies for hCD55 and TU66 for hCD39. In Exp. 1, RT-PCR showed CD55 mRNA expression in 3 out of 5 (2, 15, 24) PK15-CD55 colonies. A high level of CD55 expression was confirmed only in colony 24 by IHC, NB, WB, and FACS. Low expression level in colony 2 revealed by FACS was not detected by IHC, indicating that FACS analysis is more accurate to quantify the level of expression. All PK15-CD39 colonies were positive according to RT-PCR and IHC. Only one colony PK15-CD39 was further analyzed by NB and WB and confirmed positive. In Exp. 2, IHC, NB, WB, and FACS analyses of fibroblasts and PAEC derived from both cloned piglets confirmed the high level of CD39 expression detected by IHC in donor cells used for nuclear transfer. However, strong CD55 expression detected by IHC was not confirmed by NB analyses and, by FACS, was lower than in HUVEC cells. In conclusion, we produced cloned CD55-CD39 transgenic Gal-/- piglets with a high level of CD39 expression but the expression level of CD55 was lower than in HUVEC cells. We found that although IHC is the method of choice in preliminary screening, it is not sufficiently quantitative when only a few cells for each clone are available. Thus, IHC needs to be complemented with additional methods (e.g. WB, FACS, real-time RT-PCR) to obtain complete evaluation of the expression pattern of transgenes before nuclear transfer experiments. This study was supported by EU grant no. LSHB-CT-2006-037377 and Fondazione Banca Popolare di Cremona.

Measurement of the sensitivity of different commercial assays in the diagnosis of CMV infection in pregnancy

To evaluate the performance of different commercial assays for the detection of recent cytomegalovirus (CMV) in pregnancy, the sensitivity and specificity of assays for CMV-specific IgM antibodies were compared. Routine specimens from pregnant women were screened for CMV IgM using the Abbott AxSYM assay. Sera that were reactive according to AxSYM were further tested for IgM by other commercial assays. In selected IgM positive samples a CMV IgG avidity assay (Radim) and virus isolation from urine (shell vial) were also performed. The positivity rate for IgM anti-CMV by AxSYM was relatively high (140 out of 492, combining reactive and grayzone results). Only 26 of the 140 samples were positive for IgM according to Radim. The IgG avidity was low in 16 of the 43 samples tested, and the Radim and DiaSorin IgM assays were negative in 5 of them; 2 of the latter cases were also positive for viral isolation according to a shell vial method. There are differences in the sensitivity of the commercially available tests for CMV antibodies. CMV screening in pregnancy is performed as a first step by immunoassays and the choice of highly sensitive IgM test associated with further serological and virological methods could help to identify early primary infections.

Commitment to the osteoblast lineage is not required for RANKL gene expression

Differentiation of bone-resorbing osteoclasts from hematopoietic precursors depends upon expression of the cytokine receptor activator of NFkappaB ligand (RANKL) by fibroblastic stromal cells, which some evidence suggests are of the osteoblast lineage. We have shown previously that hormonal-responsiveness of the murine RANKL gene is mediated in part by a distal enhancer that binds Runx2, a transcription factor required for commitment to the osteoblast lineage, supporting the idea that osteoclast-supporting stromal cells may be osteoblasts or their progenitors. However, in this study we demonstrate that parathyroid hormone (PTH) stimulation of RANKL in mice is not affected by a significant reduction in the number of osteoblasts. Consistent with this, neither Runx2, nor Cbfb, a binding partner essential for Runx activity, are required for basal or PTH-stimulated RANKL expression in fibroblastic stromal cell models. Nonetheless, RANKL responsiveness to PTH was elevated in cultured calvaria cells expressing high levels of osterix, another transcription factor required for osteoblast differentiation, and this was associated with elevated PTH receptor expression. The responsiveness of RANKL to 1,25-dihydroxyvitamin D(3) was not elevated in the osterix-expressing cells. Together, these results suggest that commitment to the osteoblast lineage is not a requirement for RANKL gene transcription in fibroblastic stromal cells but may enhance responsiveness of this gene to specific hormones via control of their receptors.

Protective effects of the cumulus-corona radiata complex during vitrification of horse oocytes

Vitrifying oocytes is a potentially valuable means of preserving the female germ line, but significantly compromises oocyte developmental competence. This study examined the hypothesis that the cumulus complex protects the oocyte during vitrification. Vitrified-warmed immature cumulus oocyte complexes (COCs) were labelled with a plasma membrane impermeant DNA marker (ethidium homodimer-1) to examine the percentage and location of dead cumulus cells, and to investigate the effect of the proportion of dead cells (+1,+2 or +3) on the success of in vitro maturation (IVM). Further, oocytes were labelled for connexin-43 or injected with Lucifer yellow dye to determine whether the integrity of the gap junctions between an oocyte and its cumulus was compromised by vitrification. Finally, the effect of denuding immature and mature oocytes on their ability to withstand vitrification was examined. Cryopreserving immature COCs increased the number of dead cumulus cells (13 vs 2.6% for controls; P<0.05). However, an increased proportion of dead cumulus cells did not affect post-warming maturation rates (∼30% MII) presumably because dead cells were located at the periphery of the cumulus mass and cumulus-oocyte gap junction communication was not disrupted. Moreover, cumulus removal prior to IVM or vitrification indicated that while the cumulus does protect immature oocytes during vitrification it does so by mechanisms other than support during maturation. Cumulus presence was also found to protect mature equine oocytes against vitrification-induced damage since cumulus-enclosed MII oocytes preserved their meiotic spindle quality better during vitrification than denuded oocytes (38.1 vs 3.1% normal spindles; P<0.05).

262 ICSI OF EQUINE OOCYTES WITH SEX-SORTED FROZEN-THAWED SEMEN RESULTS IN LOW CLEAVAGE RATE BUT NORMAL EMBRYO DEVELOPMENT AND PREGNANCIES

Sorting of sperm by flow cytometer has allowed selection of offspring of predetermined sex in several species by artificial insemination, although the success rate is often lower than with non-sexed semen. In horses, the problem was partially overcome with hysteroscopic insemination using sex-sorted fresh sperm. However, when sex-sorted frozen–thawed sperm were used the pregnancy rate was heavily reduced in comparison with non-sexed frozen–thawed semen. Because it has been demonstrated that in vitro assisted reproductive techniques, namely intracytoplasmic sperm injection (ICSI), has permitted live foals to be obtained using sperm with low fertility in the field, in this study we investigated the possibility of using ICSI with sexed-sorted frozen–thawed sperm for equine embryo production in vitro. Briefly, semen was collected from two Standardbred stallions of proven fertility (Stallions A, B), sorted using a MoFlo SX flow cytometer and frozen (Johnson LA and Welch GR 1999 Theriogenology 52, 1323–1341). Sex-sorted and control non-sexed frozen semen (two stallions of in vitro proven fertility: C, D) was thawed, centrifuged on a Percoll gradient, washed and diluted 1:1 in PVP before ICSI. Oocytes were collected from ovaries of slaughtered mares and matured in vitro. Metaphase II oocytes were injected with sperm, subsequently cultured up to the blastocyst stage and frozen conventionally in 10% of glycerol (Galli et al. 2002 Theriogenology 58, 713–715). Six embryos from sexed-sorted sperm were thawed and non-surgically transferred in naturally cycling synchronous recipient mares. Results are summarized in Table 1. Overall, 70 and 58 (stallion A, B) and 30 and 15 (stallion C, D) oocytes were injected with sex-sorted or control frozen–thawed sperm, respectively. Mean cleavage rates were 20.3% for sorted sexed sperm and 71.1% for control, showing a significantly lower cleavage rate for sexed sperm. This difference was reflected in the number of blastocysts obtained (4.7% v. 20.0%). From the 6 frozen–thawed embryos derived from sexed sperm, that were transferred, 4 pregnancies resulted. One pregnancy was lost around 21 days, a second was pharmacologically aborted, and two were maintained (one from male and one from female sorted semen are currently in the 11th month of gestation). In conclusion, this study demonstrates that ICSI with sex-sorted sperm can be used for producing equine blastocysts able to establish pregnancies at a high rate following embryo transfer. However, the overall efficiency of the system is limited due to the very low cleavage rate obtained with sexed-sorted frozen–thawed sperm. Table 1.Development of embryos produced by ICSI with sorted and non-sorted frozen–thawed semen This work was supported by an RFO (ex 60%) and Camera di Commercio Cremona grant. The Authors wish to thank Società Italiana Produttori Sementi.

The in vitro effects of cigarette smoke on fatty acid metabolism are partially counteracted by simvastatin

BACKGROUND

Statins enhance the synthesis of long-chain polyunsaturated fatty acids (LC-PUFAs) from their precursors both in vitro and in vivo. In particular, an increased conversion of linoleic acid (LA) and of alpha-linolenic acid to their derivatives is observed in cultured cells. On the contrary, cigarette smoke (CS) negatively and dose-dependently affects the LC-PUFA production.

AIM

To evaluate the effects of CS alone or with simvastatin, on [1-(14)C] LA metabolism in THP-1 cells.

RESULTS

CS inhibits LA conversion; after co-incubation, simvastatin nullifies the effects of CS, maintaining LA conversion comparable to controls. However, at the highest CS concentration, simvastatin is unable to counteract the effects of CS. Changes of LA conversion reflect the modulation of desaturase activities by simvastatin and CS.

CONCLUSION

CS decreases PUFA conversion and its effects are modulated by the opposite effect of statins. It can be speculated that statin treatments in smoking patients may provide some beneficial effects on PUFA metabolism in addition to lowering cholesterol levels.

Hydrogen atom abstraction from C-H bonds of benzylamides by the aminoxyl radical BTNO: a kinetic study

The aminoxyl radical BTNO (benzotriazole-N-oxyl; >N-O*) is generated from HBT (1-hydroxybenzotriazole; >N-OH) by oxidation with a Ce(IV) salt. BTNO presents a broad absorption band with lambda(max) 474 nm that lends itself to investigate the kinetics of H-abstraction from H-donor substrates by spectrophotometry. Thus, rate constants (k(H)) of H-abstraction by BTNO from CH(2)-groups alpha to the nitrogen atom in X-substituted-(N-acetyl)benzylamines (X-C(6)H(4)CH(2)NHCOCH(3)) have been determined in MeCN solution at 25 degrees C. Correlation of the k(H)(X) data with the Hammett sigma(+) parameters gives a small value for rho (-0.65) that is compatible with a radical H-abstraction step. The sizeable value (k(H)/k(D)=8.8) of the kinetic isotope effect from a suitably deuteriated amide substrate further confirms H-abstraction as rate-determining. Evidence is acquired for the relevance of stereoelectronic effects that speed up the H-abstraction whenever the scissile C-H bond is co-linear with either the nitrogen lone-pair of the amide moiety or an adjacent aromatic group. An assessment of the dissociation energy value of the benzylic C-H bond in ArCH(2)NHCOMe is accordingly reported.

Control of bone mass and remodeling by PTH receptor signaling in osteocytes

Osteocytes, former osteoblasts buried within bone, are thought to orchestrate skeletal adaptation to mechanical stimuli. However, it remains unknown whether hormones control skeletal homeostasis through actions on osteocytes. Parathyroid hormone (PTH) stimulates bone remodeling and may cause bone loss or bone gain depending on the balance between bone resorption and formation. Herein, we demonstrate that transgenic mice expressing a constitutively active PTH receptor exclusively in osteocytes exhibit increased bone mass and bone remodeling, as well as reduced expression of the osteocyte-derived Wnt antagonist sclerostin, increased Wnt signaling, increased osteoclast and osteoblast number, and decreased osteoblast apoptosis. Deletion of the Wnt co-receptor LDL related receptor 5 (LRP5) attenuates the high bone mass phenotype but not the increase in bone remodeling induced by the transgene. These findings demonstrate that PTH receptor signaling in osteocytes increases bone mass and the rate of bone remodeling through LRP5-dependent and -independent mechanisms, respectively.

BioEnterics intragastric balloon for treatment of morbid obesity in Prader-Willi syndrome: specific risks and benefits

BACKGROUND

Obesity in Prader-Willi Syndrome (PWS) is progressive, severe, and resistant to dietary, pharmacological, and behavioral treatment. A body weight reduction is mandatory to reduce the risk of cardio-respiratory and metabolic complications. The aim of the study was to assess risks and benefits of BioEnterics Intragastric Balloon (BIB) for treatment of morbid obesity in PWS patients.

METHODS

Twenty-one BIB were positioned in 12 PWS patients (4 M, 8 F), aged from 8.1 to 30.1 years, and removed after 8 +/- 1.4 months (range: 5-10 months). Auxological, clinical, and nutritional evaluations were performed every 2 months. Variations in body composition were analysed by dual energy X-ray absorbiometry (DXA).

RESULTS

One patient (28.5 years, BMI: 59.3 kg/m(2)) died 22 days after BIB positioning because of gastric perforation. In another case (26.2 years, BMI: 57.6 kg/m(2)), BIB was surgically removed after 25 days because of symptoms suggesting gastric perforation (not confirmed). The remaining ten patients showed a significant decrease of BMI (p = 0.005) and of fat tissue as measured by DXA (p = 0.012). No significant modifications in bone mineral density (BMD) occurred, but a slight loss in lean body mass (p = 0.036) was documented. In five patients, BIB treatment was repeated more than once.

CONCLUSION

This study shows that when noninvasive pharmacological therapies fail, BIB may be effective to control body weight in PWS patients with morbid obesity, particularly when treatment is started in early childhood. However, careful clinical follow-up and close collaboration with parents are crucial to avoid severe complications, which can be caused by persisting unrestrained food intake.

Maternal smoking habits are associated with differences in infants' long-chain polyunsaturated fatty acids in whole blood: a case-control study

OBJECTIVE

To study the effects of maternal smoking on the status of long-chain polyunsaturated fatty acids (LCPUFA) in infants' whole-blood lipids.

DESIGN

A case-control matched study planned on the basis of preliminary observations.

SETTING

Maternity ward.

PATIENTS

A total of 159 healthy, term, breastfed infants with weight appropriate for gestational age, subdivided (53 per group) into those born to non-smokers (reference), smokers (> or = 5 cigarettes per day) who either stopped within the first trimester of pregnancy (early smokers) or who continued througout pregnancy (late smokers).

INTERVENTIONS

The fatty acid profile of 4-day-old infants was determined on whole blood.

RESULTS

Higher levels of linoleic (LA) and alpha-linolenic acid (ALA) and lower levels of the metabolic products di-homo-gammalinolenic (DHGLA) and arachidonic (AA), of the n-6 series, and docosahexaenoic acid (DHA), of the n-3 series, were found in infants born to late smokers compared with the reference group. The DHGLA/LA and AA/DHGLA ratios in the n-6 series and DHA/ALA in the n-3 series, which are indices of the metabolic processes in LCPUFA synthesis, were lower in infants born to smokers compared with those born to non-smokers. Infants born to early smokers showed n-6 PUFA levels and ratios similar to references and n-3 parameters closer to those born to late smokers. No dietary differences were found among the three groups of mothers. All the independent associations with smoking persisted after adjustment for maternal covariates. Pre-pregnancy body weight, which is lower in late smokers compared with non-smokers, independently correlated with LCPUFA levels in both series.

CONCLUSIONS

Maternal smoking is associated with a reduction in LCPUFA pools in infants, which might have structural and functional consequences.

Analysis of ferritin genes in Parkinson disease

BACKGROUND

Genes that regulate iron metabolism may be involved in increasing brain iron content in Parkinson disease (PD). The ferritin L-chain is one of these genes, but the rare insertional mutations that cause neuroferritinopathy with basal ganglia degeneration have not yet been identified in PD.

METHODS

We used denaturing HPLC (DHPLC) to investigate 124 PD patients and 180 controls for variations in the coding and in the 5' untranslated regions of the H- and L-ferritin genes.

RESULTS

In the H-ferritin gene, we found one new and rather common intronic polymorphism and the K54R substitution in two controls. The L-ferritin gene showed a very common L55L polymorphism and four other types of DNA variations, three of which were in the patient cohort. A mutation of the conserved His133 to Pro was found in a PD patient and in his daughter. The patient did not show signs of neuroferritinopathy, but the mutation was associated with low L-ferritin levels and with mild chronic anemia.

CONCLUSIONS

The results support the hypothesis that DNA variations in the ferritin genes are not a common cause for PD.

Non-hormone-induced mixed epithelial and stromal tumor of kidney in a man: description of a rare case

Mixed epithelial and stromal tumor of the kidney is a recently recognized category of lesions occurring mostly in adult, middle-age women with a history of hormonal treatment. We present a rare case of a 58-year-old asymptomatic man without a history of hormonal treatment with a tumor characterized by proliferation of multiple cysts lined by single layers of epithelial cells and hypercellular stroma of spindle "ovarian-like" cells. Immunohistochemically, the stromal cells reacted against estrogen and progesterone receptors, vimentin, desmin, and CD34. A follow-up computed tomography scan performed 8 months after surgical enucleation of the lesion showed no signs of recurrence.

Analysis of living cells grown on different titanium surfaces by time-lapse confocal microscopy

In this study we have combined fluorescence- and reflection-confocal laser scanning microscopy for the simultaneous visualization of living cells and surface topography beneath them. To this purpose we have designed a specific flow chamber and we have tested it with osteoblasts grown on an opaque, thick support, made of smooth or sandblasted titanium. Cells were loaded with Calcein-AM or tetramethylrhodamine methyl ester (TMRM), two probes employed as indicators of cell viability/morphology and mitochondrial membrane potential, respectively. Besides the acquisition of stacks of confocal sections, the system allowed also vertical views and faithful three-dimensional reconstruction of the samples. Confocal microscope implemented with our flow chamber proved to be a promising tool for time-lapse investigation of cell-biomaterial interactions.

300 HEMIZYGOUS PRION PROTEIN GENE (PRNP) KNOCKOUT IN CATTLE FIBROBLASTS

Bovine spongiform encephalopathy (BSE) represents a real threat for human health, as has been demonstrated by the causal link with the variant form of Creutzfeldt-Jakob disease. The aim of our project is to create a bovine strain knockout for the prion protein gene (PRNP) that should be resistant to BSE infection. We combined the use of homologous recombination by PRNP targeting vectors in bovine fibroblasts with the subsequent use of nuclear transfer (NT). We transfected fetal (male) and adult (female) bovine fibroblasts by nucleofection, using targeting vectors disrupting the PRNP by means of loxP flanked cassettes. They expressed resistance to different drugs driven by a PGK or TK promoter and the thymidine kinase gene as a negative selection marker. We screened, by PCR, 907 drug-resistant colonies, from which we identified 8 Neo-resistant colonies with a recombined PRNP allele (overall efficiency 3.2%; 7/108 from fetal, 1/145 from adult; P < 0.5). Fibroblasts PRNP+/– Neo were used to produce NT blastocysts from which neural precursors cell lines were established (Lazzari et al. 2006 Stem Cells 24, 2514–2521). These lines were capable of extensive proliferation (over 120 doublings during 4 months of culture) and provided unlimited material for Southern blot analysis to confirm PCR findings. Three clones (2 from fetal and 1 from adult) were further analyzed and confirmed PRNP+/– by Southern blot and were subsequently used for NT to generate blastocysts for transfer to recipient heifers. On Day +40 of gestation, the pregnancy rate was 33.3% (9/30) for the fetal line and 50% (2/4) for the adult line. One of the fetuses originating from fetal fibroblasts was removed on Day +45 to establish a rejuvenated fibroblast cell line used for a second round of gene targeting to obtain a PRNP –/– clone. We nucleofected these fibroblasts with Puro, Hygro, and promoterless Hygro cassette-carrying targeting vectors. We screened 625 drug-resistant colonies by PCR but none tested positive for the second targeting. In conclusion, we have obtained heterozygous PRNP+/– fibroblasts with the Neo vector both in fetal and adult fibroblasts, but failed with other vectors. In the first targeting, the efficiency was 10 times greater in fetal v. adult fibroblasts. The derivation of neural precursor cell lines from cloned blastocysts is a useful procedure to have sufficient material for molecular analysis without the need of rejuvenating the cell through the production of a fetus. None of the vectors used for the targeting of the second allele was successful.

170 EXPRESSION PATTERN OF THE Sox2 GENE IN BOVINE OOCYTES AND IN VITRO-DERIVED EMBRYOS

Sox2 is a member of the Sox (SRY-related HMGbox) family. It acts to maintain developmental potential and marks the pluripotent lineage of the early mouse embryo; in particular, as in the case of Oct-4 and Nanog, Sox2 is expressed specifically in the inner cell mass (ICM) and in the epiblast of this species. Moreover, it plays an important role in the transcription network that maintains stem cell pluripotency, interacting with other factors such as Oct-4 and Nanog. Little information is available on this gene in bovine; therefore aims of the present study were: a) to identify and characterize the Sox2 expression profile in bovine oocytes and preimplantation embryos; and b) to investigate its expression pattern in ICM and trophectoderm (TE). Bovine oocytes and embryos were obtained by in vitro maturation and fertilization; blastocysts at Day 7 post-insemination underwent microsurgery to separate TE from ICM. mRNA was isolated from 3 pools, each consisting of 5 MII oocytes, 2-, 4-, 8-, and 16-cell embryos, morulae, blastocysts, ICMs, and TEs. Semi-quantitative analysis of Sox2 expression was performed in the exponential phase of PCR amplification using rabbit globin as exogenous control. Data were analyzed with one-way ANOVA, followed by multiple pairwise comparisons with Tukey test (SigmaStat 2.03, SPSS, Inc., Chicago, IL, USA). Values are presented as mean � SEM and differences of P ≤ 0.05 are considered significant. In order to rule out false negative results, PCR amplifications of isolated ICMs and TEs were extended to the plateau phase. Fragment identity was confirmed by sequencing. Comparison of bovine Sox2 cDNA sequence (EMBL AM774325) with databases revealed a 98%, 93%, and 87% homology with sheep, human, and mouse, respectively. Sox2 mRNA was detectable in oocytes as well as in embryos at the different developmental stages analyzed. Semi-quantitative expression studies revealed that Sox2 was present as both maternal and embryonic transcript; in particular, a statistically significant increase from the 8-cell stage, concomitant with embryo genome activation, was observed. Differently from the mouse, Sox2 was expressed in both bovine ICM and TE, resembling the profile previously shown for Oct-4 (van Eijk et al. 1999 Biol. Reprod. 60, 1093–1103), and suggesting that Sox2 expression might be regulated by Oct-4 also in bovine, as described in mouse and human. These findings also suggest that its expression may become restricted to the ICM only at the expanded hatched stage, as previously described for Oct-4 in pig embryos (Vejlsted et al. 2006 Mol. Reprod. Dev. 73, 709–718). This work was supported by PRIN 2006, FIRST 2005, TECLA-MIUR, and EUROSTELLS-ESF.

308 INFLUENCE OFA MATRIX ATTACHMENT REGION ON THE EXPRESSION OF BICISTRONIC VECTORS TRANSFECTED IN MAMMALIAN CELLS CULTURED IN VITRO

We investigated the effect of the 52 MAR (matrix attachment region) sequence of chicken lysozyme gene as a possible insulator for the expression of our transgenes in somatic cells to be used for nuclear transfer. With the preliminary purpose to demonstrate a possible positive effect (position or copy number) on the long-term combined expression during in vitro culture, we have created a bicistronic ubiquitous expression vector with (MAR+) or without (MAR–) MAR. The main structure of our constructs is composed of the pCAGGS promoter driving the expression of a reporter gene (enhanced green fluorescent protein, EGFP) followed by a loxable selection cassette (loxP-PGKneo). The MAR region was inserted before the selection cassette. After KpnI digestion, the resulting linearized vectors were purified and subsequently used to transfect adult porcine fibroblast cell lines using the Nucleofector system (Amaxa, Cologne, Germany). Fibroblasts were cultured in DMEM/M199 medium (1:1) + 10% FCS supplemented with 5 ng mL–1 of basic fibroblast growth factor (bFGF). In every experiment, 1 � 106 cells were transfected with 2.5 µg of linearized plasmid and selected for 3 weeks with medium supplemented with 400 µg mL–1 of Geneticin (G418 sulfate, Calbiochem, La Jolla, CA). On Day 8 of G418 selection, we analyzed 150 colonies for each treatment, using fluorescence microscopy with fluorescein isothiocyanate filters. Colonies were classified according to size (large) and cell morphology (small cells without signs of aging). In addition, colonies were classified for uniform GFP expression (uniform), patchy GFP expression (variegated), and no GFP expression (negative). Resistant colonies derived from MAR+ and MAR– vectors, respectively, had 36 (24%), 42 (28%), and 56 (37%) v. 79 (53%), 58 (39%), and 29 (19%) uniform, variegated, and negative GFP. Differences were significant for variegated and negative in MAR+ v. MAR– (chi square, P < 0.05). Thirty-six MAR+ and 42 MAR– colonies uniformly expressing GFP were transferred to 24-well plates and subjected to G418 selection until Day 22, when 7 MAR+ and 15 MAR– clones were still growing in culture. Four of seven MAR+ (57%) and 7/15 MAR– (47%) uniformly expressed high levels of GFP. In conclusion, we found that significantly fewer colonies expressed GFP with the MAR+ vector; however, within the GFP-expressing clones, expression was more uniform. Therefore, we did not find a beneficial effect of MAR sequences on expression in somatic cells during in vitro culture; however, further work is needed to investigate their effect after nuclear transfer and/or on the next generation of cloned transgenic animals.

Targeted deletion of a distant transcriptional enhancer of the receptor activator of nuclear factor-kappaB ligand gene reduces bone remodeling and increases bone mass

Receptor activator of nuclear factor-kappaB ligand (RANKL) is essential for osteoclast differentiation, and hormones and cytokines that stimulate bone resorption increase RANKL expression in stromal/osteoblastic cells. We have previously shown that PTH and 1,25-dihydroxyvitamin D(3) control murine RANKL gene expression in vitro, in part, via an evolutionarily conserved transcriptional enhancer, designated the distal control region (DCR), located 76 kb upstream from the transcription start site. Herein we describe the phenotype of mice lacking this enhancer. Deletion of the DCR reduced PTH and 1,25-dihydroxyvitamin D(3) stimulation of RANKL mRNA and osteoclast formation in primary bone marrow cultures as well as stimulation of RANKL mRNA in bone. DCR deletion also reduced basal RANKL mRNA levels in bone, thymus, and spleen. Moreover, mice lacking the DCR exhibited increased bone mass and strength. The increase in bone mass was due to reduced osteoclast and osteoblast formation leading to a low rate of bone remodeling similar to that observed in humans and mice with hypoparathyroidism. These findings demonstrate that hormonal control of RANKL expression via the DCR is a critical determinant of the rate of bone remodeling.