254 DEVELOPMENTAL COMPETENCE OF MOUSE OOCYTES AFTER IN VITRO GROWTH, NUCLEAR TRANSFER, AND IN VITRO FERTILIZATION

Long-term effects of in vitro maturation of oocytes and in vitro culture of fertilized eggs have been reported in ruminants, mice, and humans. However, effects of in vitro oocyte growth are unknown. Although a large number of non-growing oocytes can be a gamete resource, very few oocytes ever acquire competence to support full-term development after in vitro growth. The objective of the study was to evaluate different culture conditions and the long-term effects of in vitro oocyte growth on the production of offspring. Oocytes of newborn, 10-day-old, and adult BDF1 (C57BL/6N � DBA2) mice were cultured for 22, 11, and 1 day(s), respectively. The results showed that alpha-MEM medium was superior to Waymouth medium in oocyte growth (68.6 � 3.87 �m vs. 61.7 � 3.26 �m, respectively; P < 0.001), and in maintenance of follicular integrity (69% vs. 30%; P < 0.001) when non-growing oocytes from newborn mice were cultured. However, oocytes grown in vitro were incompetent to support meiotic maturation by themselves in the case of either the 22-day culture of oocytes from newborn mice (1/59 in alpha-MEM vs. 1/65 in Waymouth) or the 11-day culture of oocytes from 10-day-old mice (51/140 in alpha-MEM vs. 2/157 in Waymouth), and none of them developed to the blastocyst stage. Subsequently, to examine the nucleic competence of oocytes grown in vitro, serial nuclear transfers were carried out. Karyoplasts from oocytes grown in vitro using alpha-MEM were fused with the GV oocytes grown in vivo after enucleation. The reconstituted oocytes were cultured in alpha-MEM. After 14 h, MII chromosomes of the reconstituted oocytes were transferred into the enucleated and ovulated MII oocytes in order to provide cytoplasmic competency. The results showed that when the donor oocytes attained a diameter of e60 �m, the reconstituted oocytes could develop into pups at extremely high rates (30-41%) after in vitro fertilization (IVF) and embryo transfer in the case of either the 22-day culture of oocytes from newborn mice (7/17) or the 11-day culture of oocytes from 10-day-old mice (25/77). A significant difference was not observed in the competence to develop to term of the reconstituted oocytes when compared with that of the oocytes reconstituted from the control GV (25/52; P > 0.05). When the donor oocytes attained a diameter of 50–60 �m, the reconstituted oocytes also could develop into pups (7/33); however, their efficiency was significantly reduced when compared with that of the reconstituted oocytes from the control GV (P < 0.05). On the other hand, the weight of the offspring depended on the duration of culture, and offspring from non-growing oocytes (1.48 � 0.17 g) were heavier than those of the IVF control (1.25 � 0.14 g; P < 0.05). In conclusion, we have demonstrated that using a nuclear transfer technique combined with in vitro growth of oocytes was sufficient to produce functional oocytes, and long-term culture for oocyte growth did not affect the nucleic ability of oocytes to develop to term; however, fetal growth may be susceptible to the duration of culture.

Disruption of parental-specific expression of imprinted genes in uniparental fetuses

In mammals, imprinted genes show parental origin-dependent expression based on epigenetic modifications called genomic imprinting (GI), which are established independently during spermatogenesis or oogenesis. Due to GI, uniparental fetuses never develop to term. To determine whether such expression of imprinted genes is maintained in uniparental mouse fetuses, we analyzed the expression of 20 paternally and 11 maternally expressed genes in androgenetic and parthenogenetic fetuses. Four genes of each type were expressed in both groups of fetuses. Furthermore, quantitative analysis showed that expression levels deviated from the presumed levels for some imprinted genes. These results suggest that mechanisms acting in trans between paternal and maternal alleles are involved in the appropriate expression of some imprinted genes.

Oocyte growth-dependent progression of maternal imprinting in mice

In mammals, some genes categorized as imprinted genes are exclusively expressed either from maternal or paternal allele. This parental-origin-specific gene expression is regulated by epigenetic modification of DNA methylation in differentially methylated region (DMR), which is independently imposed during oogenesis and spermatogenesis. It is known that methylation of DMR in the female germ line is established during oocyte growth phase. However, the cause of the progression of methylation on DMR, due to either aging of mice or growth-size of oocyte was unclear up to now. Here, we analyzed the methylation of DMR for each eight imprinted genes (Igf2r, Lit1, Zac1, Snrpn, Peg1/Mest, Impact, Meg1/Grb10, and H19) by bisulfite sequencing methylation assay, using oocytes from 10 dpp (days post partum), 15 dpp, 20 dpp, and adult mice. To find whether the size of oocytes is the cause of methylation, above oocytes were classified into seven groups (each oocyte diameter ranging from 40 to 75 microm with intervals of 5 microm). The results from juvenile mice oocytes showed that DMR methylation progressed according to oocyte growth each imprinted gene. More than 85% of DMR methylation was achieved for both Igf2r, Zac1 & Lit1 with oocyte size of reaching 55 microm and Snrpn, Peg1/Mest, Impact, and Meg1/Grb10 with oocyte size of reaching 60 microm. Preferential methylation of maternal allele was observed in Zac1 and Peg1/Mest of juvenile oocytes and in Snrpn of juvenile and adult oocytes. The oocyte size-dependent-methylation progressed equally for all three different-age juvenile mice. The size-dependent-methylation was also recognized in the growing oocytes collected from adult mice, although the progress is slightly slower than that of juvenile mice. From these results, we concluded that DNA methylation is established with oocyte size dependent manner, not with aging of mice.

Combination Therapy of Personalized Peptide Vaccination and Low-Dose Estramustine Phosphate for Metastatic Hormone Refractory Prostate Cancer Patients: An Analysis of Prognostic Factors in the Treatment

The aim of this study was to investigate prognostic factors of patients with metastatic hormone refractory prostate cancer (HRPC) under combined administration of personalized peptide vaccination and low-dose estramustine phosphate (EMP). From February 2001 to July 2004, 58 men with metastatic HRPC received the combination therapy of personalized peptide vaccination and low-dose EMP. Conducted immune monitorings for those patients were peptide-specific cytotoxic T lymphocyte (CTL) precursor analysis by interferon-gamma production and peptide-reactive immunoglobulin G (IgG) by an enzyme-linked immunosorbent assay. Clinical responses and survival times were also evaluated. The combination therapy was well tolerated with no major adverse effects. Increased levels of CTL precursors and IgG responses to the vaccinated peptides were observed in 29 of 37 (78%) patients and in 36 of 41 (88%) patients tested, respectively. A prostate-specific antigen decline of at least 50% occurred in 24% of patients. The median survival time was 17 months (95% confidence interval, 12-25 months). Cox proportional hazards analysis showed that a low number of lymphocytes (p = 0.0075, odds ratio 2.700), a negative immunological activity response after the vaccination (p = 0.0185, odds ratio 2.658), and poor performance status (p = 0.0347, odds ratio 2.569) were independent predictors of disease death. These encouraging results show the need for further evaluation of the combination of personalized peptide vaccination and low dose of EMP for metastatic HRPC patients.

Regulated expression of two sets of paternally imprinted genes is necessary for mouse parthenogenetic development to term

Mouse parthenogenetic embryos (PEs) are developmentally arrested until embryo day (E) 9.5 because of genomic imprinting. However, we have shown that embryos containing genomes from non-growing (ng) and fully grown (fg) oocytes, i.e. ngwt/fgwtPE (wt, wild type), developed to E13.5. Moreover, parthenogenetic development could be extended to term by further regulation ofIgf2andH19expression using mice with deletion of theH19transcription unit (H19Δ13) together with its differentially unit (DMR). To gain an insight into the extended development of the parthenotes to term, we have here investigated the expression levels of paternally imprinted genes in ngH19Δ13/fgwtPE throughout their development. In ngH19Δ13/fgwtPes that died soon after recovery, the expression ofIgf2andH19was restored to the appropriate levels except for lowIgf2expression in the liver after E15.5. Further, the paternally expressedDlk1andDio3were repressed, while the expression levels of the maternalGtl2andMirgwere twice those of the controls. However, the above-mentioned four genes showed almost normal expression in the surviving ngH19Δ13/fgwtPEs. The methylation analysis revealed that the intragenic DMR of theDlk1-Gtl2domain was hypermethylated in the ngH19Δ13/fgwtPEs that survived, but not in the PEs that died soon after recovery. The present study suggests that two sets of co-ordinately regulated but oppositely expressed genes,Igf2-H19andDlk1-Gtl2,act as a critical barrier to parthenogenetic development in order to render a paternal contribution obligatory for descendants in mammals.

358 MICROINSEMINATION USING MALE GERM CELLS FROM EPIDIDYMIDES AND TESTES STORED IN FREEZERS WITHOUT CRYOPROTECTANT

Cryopreservation of male germ cells is a strategy for the conservation of species and strains valuable to biomedical researchers. However, to minimize damage that may occur during freezing and thawing, complex cryopreservation protocols that have been optimized for the stage and species of the male germ cell are usually employed. This study was undertaken to see whether mouse male germ cells could be safely cryopreserved for later use by freezing the whole epididymides and testes without cryoprotectant. Furthermore, we examined whether frozen male germ cells maintained their fertilization ability after international transportation on dry ice. Epididymides and testes were collected from sexually mature male ICR and C57BL/6Cr mice and placed in polypropylene cryotubes. The cryotubes were frozen at -80�C with or without a freezing container, or were plunged directly into liquid nitrogen (LN2). They were stored at -80�C or in LN2 from between one week and one year. Epididymides and testes were thawed by placing the cryotubes in a water bath at room temperature. B6D2F1 and C57BL/6Cr oocytes were microinseminated with either epididymal and testicular spermatozoa or round spermatids. After embryo transfer into pseudopregnant females, normal pups were obtained irrespective of the method of cryopreservation and cell type used. However, their birth rates (2-33%) were lower than those of our conventional microinsemination using fresh sperm or spermatids (20-60%). For transportation experiments, testes were collected from C57BL/6J mice and placed in a cryotube. The cryotubes were frozen at -80�C in a freezing container. On the day of transportation, the cryotubes were placed in a polystyrene foam case filled with dry ice and were transported from Harwell (UK) to Tsukuba (Japan) by air and land. After three days, the samples were delivered to the recipient facility and were stored at -80�C until use (about 1 month). After thawing and collection of spermatogenic cells, C57BL/6J oocytes were microinseminated with either testicular spermatozoa or elongated spermatids. After embryo transfer, 24 (34% per transfer) and 8 (16%) offspring, respectively, were obtained from the two groups. These results indicate that mouse male germ cells retain their nuclear integrity even after freezing epididymides or testes in freezers without cryoprotectant. Since this cryopreservation technique is very simple and allows storage at -80�C for at least several months, it may enable transportation of mouse male germ cells internationally on dry ice, even when the senders are not specialized in cryopreservation.

Reactive oxygen species production by mitochondria in endothelial cells exposed to reoxygenation after hypoxia and glucose depletion is mediated by ceramide

In endothelium, reoxygenation after hypoxia (H/R) has been shown to induce production of reactive oxygen species (ROS) by complex III of the mitochondrial respiratory chain. The purpose of the present study was to test the involvement of ceramide in this phenomenon. Human umbilical vein endothelial cells underwent 2 h of hypoxia (Po2, ∼20 mmHg) without glucose and 1 h of reoxygenation (Po2, ∼120 mmHg) with glucose. ROS production was measured by the fluorescent marker 2′,7′-dichlorodihydrofluorescein diacetate, and cell death by propidium iodide. We showed that 1) after 1 h of reoxygenation, fluorescence had risen and that ROS production was inhibited by desipramine, an inhibitor of sphingomyelinase, an enzyme responsible for ceramide production (126 ± 7% vs. 48 ± 12%, P < 0.05); 2) administration of ceramide ( N-acetylsphingosine) per se (i.e., in the absence of H/R) induced ROS production (65 ± 3%), which was inhibited by complex III inhibitor: antimycin A (24 ± 3%, P < 0.0001), or stigmatellin (31 ± 2%, P < 0.0001); 3) hypoxia/reoxygenation-induced ROS production was not affected by either ceramide-activated protein kinase inhibitor dimethyl aminopurine or mitochondrial permeability transition inhibitor cyclosporin A but was significantly inhibited by the antiapoptotic protein Bcl-2 (82 ± 8%, P < 0.05); 4) ceramide-induced ROS production was also inhibited by Bcl-2 (41 ± 4%, P < 0.0001). These results demonstrate that in endothelial cells submitted to hypoxia and glucose depletion followed by reoxygenation with glucose, the pathway implicated in mitochondrial complex III ROS production is ceramide dependent and is decreased by the antiapoptotic protein Bcl-2.

Immunologic Evaluation of Personalized Peptide Vaccination for Patients with Advanced Malignant Glioma

PURPOSE

The primary goal of this phase I study was to assess the safety and immunologic responses of personalized peptide vaccination for patients with advanced malignant glioma.

EXPERIMENTAL DESIGN

Twenty-five patients with advanced malignant glioma (8 grade 3 and 17 grade 4 gliomas) were evaluated in a phase I clinical study of a personalized peptide vaccination. For personalized peptide vaccination, prevaccination peripheral blood mononuclear cells and plasma were provided to examine cellular and humoral responses to 25 or 23 peptides in HLA-A24+ or HLA-A2+ patients, respectively; then, only the reactive peptides (maximum of four) were used for in vivo administration.

RESULTS

The protocols were well tolerated with local redness and swelling at the injection site in most cases. Twenty-one patients received more than six vaccinations and were evaluated for both immunologic and clinical responses. Increases in cellular or humoral responses specific to at least one of the vaccinated peptides were observed in the postvaccination (sixth) samples from 14 or 11 of 21 patients, respectively. More importantly, significant levels of peptide-specific IgG were detected in the postvaccination tumor cavity or spinal fluid of all of the tested patients who showed favorable clinical responses. Clinical responses were 5 partial responses, 8 cases of stable disease, and 8 cases of progressive disease. The median overall survival for patients with recurrent glioblastoma multiforme in this study (n = 17) was 622 days.

CONCLUSIONS

Personalized peptide vaccinations were recommended for the further clinical study to malignant glioma patients.

Immunological evaluation of vaccination of peptides derived from epithelial cancer-related antigens in two patients with hematological malignancy

Recent advances in tumor immunology have resulted in identification of many epithelial cancer-related antigens and peptides applicable to specific immunotherapy. We and others have reported that several epithelial cancer-related antigens are also expressed in hematological malignancies. Two patients with hematological malignancy (multiple myeloma and chronic lymphocytic leukemia) were vaccinated with peptides derived from epithelial cancer-related antigens to evaluate the immune responses to peptides under a personalized peptide vaccination regimen. There was no adverse event except for local skin reaction at the injection site. The peptide vaccination augmented both peptide-specific CTLs cytotoxic to hematological malignant cells in post-vaccination peripheral blood mononuclear cells and peptide-specific IgG in post-vaccination sera. A transient but obvious decrease of malignant cells was observed at the early phase of the vaccination in both cases. Vaccines consisting of peptides derived from epithelial cancer antigens safely increased anti-tumor cell activity in patients with hematological malignancies. These results may provide a scientific rationale in use of epithelial cancer-related antigens for specific immunotherapy to patients with hematological malignancies.

Immunological evaluation of individualized peptide vaccination with a low dose of estramustine for HLA-A24+ HRPC patients

BACKGROUND

The safety, toxicity, and immunological response of individualized peptide vaccination or human leukocyte antigen (HLA)-A24+ hormone refractory prostate cancer (HRPC) patients in combination with a low dose of estramustine were evaluated.

METHODS

Sixteen patients with HLA-A24+ HRPC were enrolled in the phase I/II study. Conducted immune monitorings for those patients were peptide-specific cytotoxic T lymphocyte (CTL) precursor analysis by interferon-gamma production and peptide-reactive immunoglobulin G (IgG) by an enzyme-linked immunosorbent assay. Clinical responses and quality of life (QOL) outcomes using a self-reported patient questionnaire were also evaluated.

RESULTS

Vaccinations were well tolerated, but all patients developed grade 1 or 2 local redness and swelling at the injection site. There was no significant immunosuppression in most cases when the peptide and a half dose (280 mg/day) of estramustine were administrated. Augmentation of peptide-specific CTL precursors or peptide-specific IgG was observed in 10 of 14 or 7 of 14 patients at 12 weeks (peptide vaccination alone), and in 6 of 8 or 10 of 12 patients at 24 weeks (during the combination therapy), respectively. All 13 patients treated, with the combination therapy, showed a decrease of serum prostate-specific antigen (PSA) level from the baseline, including six patients with a serum PSA level decrease of >or=50%. QOL outcomes were not deteriorated during the treatment.

CONCLUSION

These results might encourage the further evaluation of the combination of peptide vaccination and a low dose of estramustine phosphate for HLA-A24+ HRPC patients.

Nuclei of Oocytes Derived from Mouse Parthenogenetic Embryos Are Competent to Support Development to Term1

Mouse parthenotes result in embryonic death before 10 days of gestation, but parthenogenetic embryos (ng/fg PE) that contain haploid sets of genomes from nongrowing (ng) oocytes derived from newborn fetuses and fully grown (fg) oocytes derived from adults can develop into 13.5-day-old fetuses. This prolonged development is due to a lack of genomic imprinting in ng oocytes. Here, we show maternal genomes of oocytes derived from ng/fg PE are competent to support normal development. After 28 days of culture, the ovaries from ng/fg PE grew as well as the controls, forming vesicular follicles with follicular antrums. The oocytes collected from the developed follicles were the same size as those of the controls. To determine whether maternal primary imprinting had been established in the oocytes derived from ng/fg PE, we examined the DNA methylation status in differentially methylated regions of three imprinted genes, Igf2r, Lit1, and H19. The results showed that maternal-specific modifications were imposed in the oocytes derived from ng/fg PE. Further, to assess nuclear competence to support development, we constructed matured oocytes containing a haploid genome derived from ng/fg PE oocytes by serial nuclear transfer. After in vitro fertilization and culture and embryo transplantation into recipients, two live pups were obtained. One developed normally to a fertile adult. These results revealed that oocytes derived from ng/fg PE can be normally imprinted during oogenesis and acquire competence to participate in development as female genomes.

Birth of parthenogenetic mice that can develop to adulthood

Only mammals have relinquished parthenogenesis, a means of producing descendants solely from maternal germ cells. Mouse parthenogenetic embryos die by day 10 of gestation. Bi-parental reproduction is necessary because of parent-specific epigenetic modification of the genome during gametogenesis. This leads to unequal expression of imprinted genes from the maternal and paternal alleles. However, there is no direct evidence that genomic imprinting is the only barrier to parthenogenetic development. Here we show the development of a viable parthenogenetic mouse individual from a reconstructed oocyte containing two haploid sets of maternal genome, derived from non-growing and fully grown oocytes. This development was made possible by the appropriate expression of the Igf2 and H19 genes with other imprinted genes, using mutant mice with a 13-kilobase deletion in the H19 gene as non-growing oocytes donors. This full-term development is associated with a marked reduction in aberrantly expressed genes. The parthenote developed to adulthood with the ability to reproduce offspring. These results suggest that paternal imprinting prevents parthenogenesis, ensuring that the paternal contribution is obligatory for the descendant.

Multivariate spline interpolation as a novel method to optimize pharmaceutical formulations

One of the difficulties in the quantitative approach for formulation design is the difficulty in understanding the actual relationship between causal factors and individual pharmaceutical responses. In this regard, several techniques were applied to determine the relationship between causal factors and the pharmaceutical responses. The generation of response surfaces using multivariate spline interpolation (MSI) has provided rapid and detailed information. Nevertheless, no application of MSI in the pharmaceutical field has been reported to date, even though it promises potential applications. To overcome the shortcomings of the classical response surface method, we newly developed a multi-objective simultaneous optimization method, in which MSI had been incorporated. The method was applied to the optimization problem of a transdermal hydrogel formulation for ketoprofen containing several chemical enhancers. Results suggested a superior function of the MSI approach.

Characterization and imprinting status of OBPH1/Obph1 gene: implications for an extended imprinting domain in human and mouse

Human 11p15.5, as well as its orthologous mouse 7F4/F5, is known as the imprinting domain extending from IPL/Ipl to H19. OBPH1 and Obph1 are located beyond the presumed imprinting boundary on the IPL/Ipl side. We determined full-length cDNAs and complete genomic structures of both orthologues. We also investigated their precise imprinting and methylation status. The orthologues resembled each other in genomic structure and in the position of the 5' CpG island and were expressed ubiquitously. OBPH1 and Obph1 were predominantly expressed from the maternal allele only in placenta, with hypo- and not differentially methylated 5' CpG islands in both species. These results suggested that the imprinting domain would extend beyond the presumed imprinting boundary and that methylation of the 5' CpG island was not associated with the imprinting status in either species. It remains to be elucidated whether the gene is under the control of the KIP2/LIT1 subdomain or is regulated by a specific mechanism. Analysis of the precise genomic sequence around the region should help resolve this question.

Domain regulation of imprinting cluster in Kip2/Lit1 subdomain on mouse chromosome 7F4/F5: large-scale DNA methylation analysis reveals that DMR-Lit1 is a putative imprinting control region

Mouse chromosome 7F4/F5, where the imprinting domain is located, is syntenic to human 11p15.5, the locus for Beckwith-Wiedemann syndrome. The domain is thought to consist of the two subdomains Kip2 (p57(kip2))/Lit1 and Igf2/H19. Because DNA methylation is believed to be a key factor in genomic imprinting, we performed large-scale DNA methylation analysis to identify the cis-element crucial for the regulation of the Kip2/Lit1 subdomain. Ten CpG islands (CGIs) were found, and these were located at the promoter sites, upstream of genes, and within intergenic regions. Bisulphite sequencing revealed that CGIs 4, 5, 8, and 10 were differentially methylated regions (DMRs). CGIs 4, 5, and 10 were methylated paternally in somatic tissues but not in germ cells. CGI8 was methylated in oocyte and maternally in somatic tissues during development. Parental-specific DNase I hypersensitive sites (HSSs) were found near CGI8. These data indicate that CGI8, called DMR-Lit1, is not only the region for gametic methylation but might also be the imprinting control region (ICR) of the subdomain.

A microarray-based method for detecting methylated loci

CpG island DNA methylation plays an important role in regulating gene expression in development and carcinogenesis. We developed a new microarray-based method called methylation amplification DNA chip (MAD) for detecting differences in methylation. In this method, only methylated CpG islands from the two samples that we wanted to compare were amplified and used for hybridization. The resource material for the microarray was derived from the methylated DNA library of the sample in which we wanted to detect hypermethylation. Choosing the methylated DNA library as the resource material of the microarray increased the percentage of DNA fragments derived from hypermethylated loci on the microarray.

Vasopressin with delayed combination of nitroglycerin increases survival rate in asphyxia rat model

Recently, vasopressin has been reported as a more effective drug than epinephrine (adrenaline) for cardiopulmonary resuscitation (CPR). However, vasopressin decreases myocardial blood flow (MBF) because of its strong vasoconstriction, to maintain better coronary perfusion pressure (CPP) compared with epinephrine. Nitroglycerin is well known to be able to maintain MBF and increase survival rate. In a VF model, vasopressin combined with nitroglycerin maintained CPP; however, low survival rates were observed compared with vasopressin alone. We investigated the effectiveness of the delayed use of nitroglycerin combined with vasopressin in a severe asphyxia model. Fourteen Sprague-Dawley male rats were divided into two groups: vasopressin 0.8 U/kg alone (V-Gr.), and nitroglycerin 0.3 microg/kg 45 s after the administration of 0.8 U/kg vasopressin (VN-Gr.). Six min after asphyxia induced by obstructing the tracheal tube, CPR was performed in two ways. Three animals resuscitated in the V-Gr. (42%) and six/seven (84%) in the VN-Gr. (P<0.05). In the 6 min of asphyxia rat model, vasopressin combined with delayed nitroglycerin is more effective than vasopressin alone.

Gene silencing: maturation of mouse fetal germ cells in vitro

Nuclear reprogramming is essential during gametogenesis for the production of totipotent zygotes. Here we show that premeiotic female germ cells derived from mouse fetuses as early as 12.5 days post coitum are able to complete meiosis and genomic imprinting in vitro and that these matured oocytes are highly competent in supporting development to full term after nuclear transfer and in vitro fertilization. To our knowledge, this is the first time that complete oogenesis has been successfully accomplished in vitro.

Efficient cloning and expression of HLA class I cDNA in human B-lymphoblastoid cell lines

Analysis of HLA restriction specificity is one of the important steps in characterizing T cell clones. This usually requires either a panel of HLA-typed cells or HLA cDNA transfectants. Although preparation of HLA cDNA transfectants is laborious, utilization of transfectants is advantageous when a suitable panel is not available due to linkage disequilibrium or rarity of the HLA allele of interest. In this report, we describe an efficient and rapid HLA cloning and expression system. Three sets of PCR primers specific for HLA-A, B and C loci were designed by extensively sequencing 5'- and 3'- untranslated regions of HLA class I genes. The PCR-amplified products were introduced into modified Phoenix retrovirus vectors containing a puromycin resistant gene under the control of a LTR promotor. Gibbon ape leukemia virus (GALV)-pseudotyped retrovirus was produced and infected into B-lymphoid cell lines. Following expansion in selection media, more than 80% of cells expressed transduced HLA at a comparable level to that normally expressed. These results indicate that locus-specific PCR cloning and utilization of GALV-pseudotyped retroviral vector can be an effective and relatively efficient tool for constructing a panel of different HLA transfectants.

Nuclear competence for maturation and pronuclear formation in mouse oocytes

BACKGROUND

In response to gonadotrophins, a fully grown mouse oocyte matures to the metaphase of the second meiotic division and becomes competent for the development of female and male pronuclei after fertilization. The present study was carried out to clarify when during the growth period an oocyte nucleus acquires the ability to promote pronuclei formation after fertilization.

METHODS

Fully grown germinal vesicle (GV) oocytes were enucleated and fused with nuclei from growing oocytes from 1-20 day old mice by standard nuclear transfer technique. The reconstructed oocytes were matured and fertilized in vitro, and pronuclear formation was assessed.

RESULTS

The oocytes whose nuclei were exchanged for those of the non-growing-stage oocytes matured to the metaphase of the second meiotic stage, but no normal female pronuclei were formed. Female pronuclei first formed in 27% of the oocytes reconstituted with the nuclei of oocytes from 8 day old pups after fertilization. Recondensed sperm chromatin was detected in 27% of the oocytes reconstructed with oocyte nuclei from 8 day old mice, and a male pronucleus was first formed in 6% of the oocytes that had been reconstructed with the nuclei of oocytes from 15 day old mice. The sizes of the female and male pronuclei increased with oocyte donor age, and reached normal size when the oocytes from 15 and 20 day old mice respectively were used. An electron microscopic study using oocytes that had received the oocyte nuclei of 8 day old mice confirmed these results.

CONCLUSION

The factors required for pronuclear formation are derived from fully grown GV oocytes, and the transformation from decondensed sperm chromatin to a recondensed male pronucleus is governed by GV-derived factors.

Unregulated expression of the imprinted genes H19 and Igf2r in mouse uniparental fetuses

The present study shows that the H19 and Igf2r genes, which are imprinted and expressed solely from maternal alleles, are expressed in an unregulatable manner in mouse uniparental, androgenetic, and parthenogenetic fetuses at day 9.5 of gestation. In the androgenetic fetuses, the H19 and Igf2r genes were respectively expressed at 12 and 40% of the levels in biparental fetuses. In addition, the expression of both genes was excessive (1259 and 482%, respectively) in the parthenotes. These expressions of the imprinted genes were not regulated by methylation in the regulatory regions. Moreover, the expression of the antisense Igf2r RNA (Air) was also excessive and was not correlated with Igf2r gene expression in the uniparental fetuses. Taken together, these results indicate that the parental specific expression of imprinted genes is not maintained in particular genes in uniparental embryos, which in turn suggests that both parental genomes are required to establish maternal specific expression of the H19 and Igf2r genes by trans-acting mechanisms.

Imprinting of a small nucleolar RNA gene on mouse chromosome 12

We have identified a novel, maternally expressed imprinted gene encoding a C/D-box small nucleolar RNA (snoRNA) called MBII-343, which may regulate RNA editing or alternative splicing of an as yet unknown target gene. This gene is closely linked to an imprinted gene, Meg3, on mouse distal chromosome 12, which is syntenic to human chromosome 14. The paternal duplication of mouse distal chromosome 12 leads to late embryonal/neonatal lethality, growth promotion, and cardiomyopathy, whereas maternal duplication leads to late embryonal lethality and growth retardation. Human paternal uniparental disomy for chromosome 14 leads to musculoskeletal problems and mental retardation, whereas maternal uniparental disomy leads to intrauterine growth retardation, motor developmental delay, premature puberty, hypotonia, joint laxity, macrocephaly, short statue, neonatal poor sucking, skill with jigsaw puzzles, skin picking, obesity, and maturity onset diabetes of the young.