58 PRODUCTION OF CLONED BOVINE EMBRYOS DERIVED FROM AMNIOTIC CELLS OF PREGNANT COWS

Progeny tests are widely used for selection of sires for beef and dairy cattle. A less costly method might be to clone the sire candidates at their earliest developmental stage possible. To produce cloned bulls, we obtained amniotic cells as donors for nuclear transfer by transvaginal aspiration of pregnant cows. However, the collected cells may include some maternal cells. In this study, we examined collection methods to obtain only fetal cells from the collected fluid. We also examined the developmental capacity of the embryos cloned from these cells. Amniotic fluids were aspirated from pregnant cows by ultrasound-guided aspiration. We collected amniotic fluids from 27 pregnant Japanese black beef cattle (between 58 and 132 days of gestation). In Method 1, cells were recovered from the whole amniotic fluid (approximately 15 mL). In Method 2, the initial 5 mL of aspirated fluid was discarded and then the next 10 mL sample was collected. Cells were recovered from the collected fluids. The cells in the fluids were washed twice by centrifugation and then cultured in AmnioMAX™-II medium (GIBCO, Grand Island, NY, USA). After 3–4 passages, the sex of the cell lines was determined by the loop-mediated isothermal amplification (LAMP) method (Eiken Chemical Co., Ltd., Tokyo, Japan). For the cell lines that were determined as 'male' by the LAMP method we further analyzed the sex of individual cells (137–620 cells of each cell line) by fluorescent in situ hybridization (FISH) using a bovineY chromosome-specific probe (Kobayashi et al. 1998 Mol. Reprod. Dev. 51, 390–394). The percentage of male cells obtained from Methods 1 and 2 were 0–0.4% (from 4 animals) and 93.7–99.5% (from 6 animals), respectively. Then, we used confluent amniotic cells from 3 cell lines obtained by Method 2 as donor cells for nuclear transfer and examined the developmental capacity of the cloned embryos. Bovine fibroblasts cultured under serum starvation were used as a control. The cells were electrically fused (2.7 kV cm–1, 11 µs, 2 times) with enucleated bovine oocytes, and activated with a calcium ionophore and cycloheximide. They were subsequently cultured in mSOF until 168 h post-activation. The data were analyzed with Fisher's protected least-squares difference (PLSD) test following ANOVA. The rates of fusion, cleavage, and development to the blastocyst stage of the cloned embryos were the same as those of the control embryos (78% v. 81%, 75% v. 75%, and 22% v. 27%, respectively; P > 0.05). Furthermore, the rate of male blastocysts derived from the cloned embryos with the three cell lines was 95% (19/20). These results indicate that the amniotic fluids collected from pregnant cows by Method 2 contained fewer maternal cells, and that the embryos cloned from the cells developed in a manner similar to that of embryos cloned from the fibroblasts. This work was supported byWakayama Prefecture CREATE, JST.

163 SEARCH FOR GENES OF WHICH THE AMOUNTS OF TRANSCRIPTS OSCILLATE EVERY 24 h IN THE MOUSE OVARY

Perturbation of circadian rhythm is believed to be detrimental to the physiology of organs, including the mammalian ovary. However, the molecular mechanisms that are regulated by circadian rhythm in the ovary have not been identified. To identify the molecular mechanisms that are regulated by circadian rhythm and to speculate on the physiologies that are likely to be damaged by perturbation of circadian rhythm in the ovary, we searched for genes in which the amount of transcripts oscillates every 24 h in the mouse ovary. To achieve this, expression profiles of circadian genes (per1, per2, and bmal1) that code transcription-regulation factors for which transcription activities are known to oscillate every 24 h in almost all organs, and wee1, the transcription activity of which circadian genes regulate and which is known to elongate the G2 phase in the cell cycle, were analyzed in this study. Six-week-old female ICR mice were kept individually under a lighting schedule with lights on for 14 h followed by lights off for 10 h. A vaginal smear of each mouse was collected every day to determine its estrous cycle. Ovaries of 3 mice were collected continuously every 4 h over a 4-day period from the start of the light period on the day of proestrus. Total RNA was extracted from each ovary, and 500 ng each was used for cDNA synthesis. Transcripts of each gene and of tbp were quantified by real-time PCR, and the amount of the transcripts of each gene in each sample was divided by the amount of tbp transcripts. The obtained relative values in each sample were used as the representative data of the amount of transcripts of each gene. The amounts of per1, per2, and bmal1 clearly oscillated every 24 h. The maximum and minimum values of per1 and per2 were observed at 16 and 4 h, respectively, after onset of the light period each day. The maximum and minimum values of bmal1 were observed at the time of onset of the light period and at 12 h after onset of the light period each day. Averages of the maximum values of per1, per2, and bmal1 each day were significantly greater than averages of the minimum values (per1, 3.60 � 0.10 and 1.38 � 0.09; per2, 0.82 � 0.08 and 0.27 � 0.06; bmal1, 0.61 � 0.05 and 0.17 � 0.01; P < 0.05). The cyclicity in the oscillation of the amount of wee1 transcripts was weaker than that observed in circadian genes, but the average of values that were obtained from 12 to 20 h after onset of the light period each day was significantly greater than that obtained from 0 to 8 h (0.29 � 0.02 and 0.22 � 0.01; P < 0.05). Our results suggested that the cell cycle of ovarian cells is regulated in a circadian manner through wee1 transcription, which is regulated by circadian genes of which the amounts of transcripts oscillate every 24 h. Because an abnormal cell cycle seems to trigger the development of tumors or follicular cysts, perturbation of circadian rhythm may cause those ovarian diseases.

38 EFFECTS OF TRICHOSTATIN A ON DNA METHYLATION IN CLONED BOVINE EMBRYOS

Recently, the efficiency of full-term development of somatic cloned mouse embryos was significantly increased 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). We have shown that TSA treatment improved the rate of development of the cloned bovine embryos to the blastocyst stage (Iwamoto et al. 2007 Reprod. Fertil. Dev. 19, 142 abst). Higher levels of DNA methylation have been shown in early cloned bovine embryos than in in vitro-fertilized (IVF) embryos (Dean et al. 2001 Proc. Nat. Acad. Sci. USA 98, 13734–13738; Santos et al. Curr. Biol. 13, 1116–1121). In this study, we examined the effects of TSA on DNA methylation levels in cloned bovine embryos by immunostaining with an antibody to 5-methyl cytosine (5-MeC). Bovine fibroblasts were cultured under serum starvation (0.4% FCS) for 7 days before they were used as donor cells. The cells were electrofused with bovine enucleated matured oocytes, and activated with a calcium ionophore and cycloheximide. Atotal of 131 cloned embryos were produced. The NT embryos were exposed to 0 (control) and 50 nmTSA from the start of activation to 48 h post-activation (hpa). They were then cultured in an mSOF medium. At 60 hpa, only embryos developed to the 8-cell stage were used for assessment of DNA methylation levels. Sixteen TSA-treated, 22 non-treated, and 19 IVF embryos were immunostained with 5-MeC antibody. For quantitative analysis of the DNA methylation levels, 5-MeC signals in the fluorescent images were determined using an image analyzer system (Aqua Cosmos; Hamamatsu Photonics, Shizuoka, Japan). The data were analyzed with Tukey-Kramer post hoc test for multiple comparisons following ANOVA. Relative levels of DNA methylation of TSA-treated cloned and IVF embryos did not differ (P > 0.05), but were lower than those of non-treated cloned embryos (P < 0.05). The results indicate that TSA treatment of cloned bovine embryos leads to a reduction of DNA methylation levels of their genome. The data suggest that the TSA treatment decreased the DNA methylation levels of cloned bovine embryos to the levels of IVF embryos, resulting in improved blastocyst development of the cloned embryos.

46 EXPRESSION OF TRANSCRIPTION FACTORS SPECIFIC TO THE TROPHOBLAST LINEAGE IN MOUSE SOMATIC NUCLEAR TRANSFER EMBRYOS

Somatic cell nuclear transfer (SCNT) embryos can develop at relatively high rates during the preimplantation period; however, most of these fail after implantation. Development of extraembryonic tissue is indispensable for normal embryonic development. Hence, an abnormality of trophoblast development might be a significant factor in post-implantation lethality of SCNT embryos. A transcription factor, caudal-related homeobox 2 (Cdx2), appears to be involved in the segregation of ICM and trophectoderm (TE) in preimplantation embryos (Niwa et al. 2005 Cell 123, 917–929). Both Cdx2 and Oct3/4 are expressed in all cells at the morula stage, and then Cdx2 expression becomes restricted to the TE and Oct3/4 to the ICM as the blastocyst develops. Mouse embryos deficient in Cdx2 are able to develop to normal blastocysts but die soon after implantation, probably because of defects in the TE lineage. Moreover, dysplasia of the spongiotrophoblast layer might attribute to an abnormality of Tpbpa expression in mouse SCNT embryos (Wakisaka-Saito et al. 2006 Biochem. Biophys. Res. Commun. 349, 106–114). In this study, we examined the expression profiles of transcription factors implicated in trophoblast development in mouse SCNT embryos and intracytoplasmic sperm injection (ICSI) embryos by immunohistochemistry and real-time PCR analysis. SCNT embryos were produced according to the method reported previously (Wakayama et al. 1998 Nature 394, 369–374). In brief, B6D2F1 and B6C3F1 female mice were used for the collection of recipient oocytes and donor cells, respectively. After nuclear transfer, the oocytes were activated and cultured in KSOM to the morula and blastocyst stages. Immunohistochemical analysis demonstrated that in ICSI embryos Cdx2 was only partially expressed at the 8-cell stage but completely in early morulae. In contrast, in SCNT embryos, it was absent at the 8-cell stage and appeared partially at the early morula stage. Thereafter, Cdx2 expression became restricted to the TE cells in both the ICSI and the SCNT blastocysts. However, ectopic expression of Oct3/4 was observed in the TE cells of SCNT, but not in ICSI blastocysts. Real-time PCR analysis showed that at the 8-cell stage, Cdx2 was expressed in ICSI but not in SCNT embryos. In addition, the expression level of Cdx2 in SCNT embryos at the blastocyst stage was only half that in ICSI embryos (P < 0.05). However, there was no significant difference in expression level of Oct3/4 between ICSI and SCNT embryos. Eomesodermin (Eomes) is also implicated in trophoblast development and its expression depends on Cdx2, BMP4, and FGF4. In SCNT embryos, the expression level of Eomes was also only half that in ICSI embryos. These results indicate that the delayed expression of Cdx2 in SCNT embryos may lead to the ectopic expression of Oct3/4 in blastocysts and, along with the limited expression of Cdx2 and Eomes, may contribute to disorders in the function of the trophoblast lineage for normal placental development. This work was supported by a Grant-in-Aid for the 21st Century Center of Excellence Program of the MEXT, Japan, and by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science.

Monetary costs of dietary energy reported by young Japanese women: association with food and nutrient intake and body mass index

Objective

Little is known about the relationship of monetary diet costs to dietary intake and obesity, particularly in non-Western populations. This study examined monetary cost of dietary energy in relation to diet quality and body mass index (BMI) among young Japanese women.

Design

Dietary intake was assessed by a validated, self-administered, diet history questionnaire. Diet costs were estimated using retail food prices. Monetary cost of dietary energy (Japanese yen 1000 kcal−1) was then calculated. BMI was computed from self-reported body weight and height.

Subjects

A total of 3931 female Japanese dietetic students aged 18–20 years.

Results

Monetary cost of dietary energy was positively associated with intakes of fruits, vegetables, fish and shellfish, and pulses; however, higher monetary cost of dietary energy was also associated with higher consumption of fat and oil, meat and energy-containing beverages, and lower consumption of cereals (rice, bread and noodles) (all P for trend <0.01). At the nutrient level, monetary cost of dietary energy was positively associated with intakes of dietary fibre and key vitamins and minerals, but also associated positively with intakes of fat, saturated fatty acids, cholesterol and sodium, and negatively with carbohydrate intake (all P for trend <0.0001). After adjustment for possible confounders, monetary cost of dietary energy was quite weakly but significantly negatively associated with BMI (P for trend = 0.0197).

Conclusions

Increasing monetary cost of dietary energy was associated with both favourable and unfavourable dietary intake patterns and a quite small decrease in BMI in young Japanese women.

Dietary patterns associated with functional constipation among Japanese women aged 18 to 20 years: a cross-sectional study

Although several nutrients and foods have been suggested to be preventive for constipation, all previous studies have examined a single nutrient or food in each analysis. In contrast, analysis of dietary patterns may provide new insights into the influence of diet on functional constipation. We conducted a cross-sectional examination of the association between dietary pattern and functional constipation in 3,770 Japanese female dietetic course students aged 18-20 y from 53 institutions in Japan. Diet was assessed with a validated self-administered diet history questionnaire with 148 food items, from which 30 food groups were created and entered into a factor analysis. Functional constipation was defined using the Rome I criteria, which has previously been used in several epidemiologic studies on constipation. The prevalence of functional constipation was 26.0% (n=979). Four dietary patterns were identified: (1) "Healthy", (2) "Japanese traditional", (3) "Western," and 4) "Coffee and dairy products." After adjustment for several confounding factors, the "Japanese traditional" pattern, characterized by a high intake of rice, miso soup, and soy products and a low intake of bread and confectionaries, was associated with a significantly lower prevalence of functional constipation. In comparison with the lowest quintile, the multivariate adjusted odds ratio (95% confidence interval) was 0.52 (0.41-0.66) in the highest quintile (p for trend < 0.0001). Other dietary patterns were not associated with functional constipation. The Japanese traditional dietary pattern, characterized by a high intake of rice and a low intake of bread and confectionaries, may be beneficial in preventing functional constipation in young Japanese women.

Negative regulation of MEKK1/2 signaling by serine-threonine kinase 38 (STK38)

Mitogen-activated protein kinases (MAPKs) are activated through the kinase cascades of MAPK, MAPK kinase (MAPKK) and MAPKK kinase (MAPKKK). MAPKKKs phosphorylate and activate their downstream MAPKKs, which in turn phosphorylate and activate their downstream MAPKs. MAPKKK proteins relay upstream signals through the MAPK cascades to induce cellular responses. However, the molecular mechanisms by which given MAPKKKs are regulated remain largely unknown. Here, we found that serine-threonine protein kinase 38, STK38, physically interacts with the MAPKKKs MEKK1 and MEKK2 (MEKK1/2). The carboxy terminus, including the catalytic domain, but not the amino terminus of MEKK1/2 was necessary for the interaction with STK38. STK38 inhibited MEKK1/2 activation without preventing MEKK1/2 binding to its substrate, SEK1. Importantly, STK38 suppressed the autophosphorylation of MEKK2 without interfering with MEKK2 dimer formation, and converted MEKK2 from its phosphorylated to its nonphosphorylated form. The negative regulation of MEKK1/2 was not due to its phosphorylation by STK38. On the other hand, stk38 short hairpin RNA enhanced sorbitol-induced activation of MEKK2 and phosphorylation of the downstream MAPKKs, MKK3/6. Taken together, our results indicate that STK38 negatively regulates the activation of MEKK1/2 by direct interaction with the catalytic domain of MEKK1/2, suggesting a novel mechanism of MEKK1/2 regulation.

Three major dietary patterns are all independently related to the risk of obesity among 3760 Japanese women aged 18-20 years

OBJECTIVE

To examine associations between dietary patterns and obesity.

DESIGN

Cross-sectional study.

SUBJECTS

A total of 3760 Japanese female dietetic course students aged 18-20 years from 53 institutions in Japan.

MEASUREMENTS

Diet was assessed over a 1-month period with a validated self-administered diet history questionnaire with 148 food items, from which 30 food groups were created and entered into a factor analysis. Body mass index (BMI) was calculated from self-reported body height and weight.

RESULTS

Mean BMI (+/-s.d.) was 20.9+/-2.8 kg m(-2). Four dietary patterns were identified. After adjustment for several confounding factors and total energy intake, the 'Healthy' pattern, characterized by high intakes of vegetables, mushrooms, seaweeds, potatoes, fish and shellfish, soy products, processed fish, fruit and salted vegetables, was significantly associated with a lower risk of BMI> or =25 (odds ratio of the highest quintile vs lowest, 0.57; 95% confidence interval: 0.37-0.87; P for trend <0.05). In contrast, the 'Japanese traditional' pattern, characterized by high intakes of rice, miso soup and soy products, and the 'Western' pattern, characterized by high intakes of meats, fats and oils, seasonings, processed meats and eggs, were both significantly associated with an increased risk of BMI> or =25 (OR: 1.77; 95% CI: 1.17-2.67; P for trend <0.01 and OR: 1.56; 95% CI: 1.01-2.40; P for trend=0.04, respectively).

CONCLUSION

Three major dietary patterns, Healthy, Japanese traditional and Western, were all independently and significantly related to the risk of obesity even among a relatively lean young Japanese female population.

Dietary fiber intake, dietary glycemic index and load, and body mass index: a cross-sectional study of 3931 Japanese women aged 18–20 years

OBJECTIVE

Few observational studies have investigated dietary fiber intake and dietary glycemic index (GI) and glycemic load (GL) simultaneously in relation to obesity, particularly in non-Western populations. We examined the associations between dietary fiber intake and dietary GI and GL, and body mass index (BMI) in young Japanese women.

DESIGN

Cross-sectional study.

SUBJECTS

A total of 3931 female Japanese dietetic students aged 18-20 years from 53 institutions in Japan.

METHODS

Dietary fiber intake and dietary GI and GL (GI for glucose=100) were assessed by a validated, self-administered, diet history questionnaire. BMI was calculated from self-reported body weight and height.

RESULTS

Mean values of BMI, dietary fiber intake, dietary GI and dietary GL were 21.0 kg/m(2), 6.5 g/4186 kJ, 65.1 and 82.1/4186 kJ, respectively. White rice (GI=77) was the major contributor to dietary GI and GL (45.8%). After controlling for potential dietary and nondietary confounding factors, dietary fiber intake was negatively correlated with BMI (adjusted mean=21.1 kg/m(2) in the lowest and 20.7 kg/m(2) in the highest quintiles; P for trend=0.0007). Conversely, dietary GI and GL were independently positively correlated with BMI (20.8 and 21.2 kg/m(2); P for trend=0.03, and 20.5 and 21.5 kg/m(2); P for trend=0.0005, respectively).

CONCLUSIONS

Dietary fiber intake showed an independent negative association with BMI, and dietary GI and GL showed an independent positive association with BMI among relatively lean young Japanese women.

284 IDENTIFICATION AND CHARACTERIZATION OF THE 5′-FLANKING REGION OF THREE MOUSE MATERNAL GENES (HISTONE H1OO, NUCLEOPLASMIN 2, AND ZYGOTE ARREST 1): TRANSCRIPTIONAL ACTIVITY IN MOUSE OOCYTES

Maternal transcripts that accumulate during oocyte growth are involved in the meiotic maturation, the initiation of the first mitosis, and the later pre-implantation development. Although the conserved E-box sequences in promoter region of some maternal genes (for example, Zp3 and Gdf-9), which are important in regulating gene transcripts as binding sites of transcriptional factors, may play a role in the oocyte-specific expression in ovary, the molecular mechanism that regulates the expression of the maternal genes is still not known. In this study, we have focused on the transcriptional activity of promoter regions to clarify the molecular mechanism of transcriptional regulation of these maternal genes [Histone H1oo (H1oo), Nucleoplasmin 2 (Npm2), and Zygote arrest 1 (Zar1)]. First, we observed the expression of firefly luciferase expression vectors under promoter regions of 3 maternal genes in oocytes isolated from 10- to 12-day-old mice, which is mainly NSN-type, transcriptionally active form (Bouniol-Baly et al. 1999 Biol. Reprod. 60, 580–587). Transcriptional activities of H1oo (-3975), Npm2 (-2610), and Zar1 (-5187) promoters were detected in oocytes, the relative luciferase activities being an average of 70, 130, and 12, respectively. On the other hand, these promoter activities were not detected in embryos at the 2-cell stage. Furthermore, deletion analysis of promoter elements (E-boxes) of H1oo and Npm2 was done by microinjecting deletion constructs into oocytes. In the H1oo promoter, deletion of sequences between -3975 and -72 bp from the transcription start site resulted in one-third of the level obtained in the full H1oo (-3975) promoter. In addition, deletion of sequence -68 bp resulted in no detection of luciferase activity. These findings indicate that the putative distal promoter sequences exist at the 52-flanking region (-3975 to -759) of the H1oo gene and that the region (-314 to -68) including the E-box region (-72) may be required for high-level transcriptional activity of the H1oo promoter. In the Npm2 promoter, deletion of sequences between -2610 and -180 bp from the transcription start site resulted in one-third of the level of wild-type activity of the Npm2 (-2610) promoter. In addition, deletion of sequence -101 bp resulted in no detection of luciferase activity. These findings also indicate that 3 putative distal promoter sequences exist at the 52-flanking region (-2610 to -210) of the Npm2 gene and that the region (-210 to -101) that includes the E-box region (-180) is crucial for high-level transcriptional activity of the Npm2 promoter. In conclusion, the E-box may be a key regulatory region for the expression of two of the maternal genes (H1oo and Npm2) examined. Currently, we are attempting to identify the transcriptional factor binding sites by DNase I footprint analysis and gel mobility shift assay.

48 EFFECTS OF TRICHOSTATIN A ON DEVELOPMENT OF BOVINE SOMATIC CELL NUCLEAR TRANSFER EMBRYOS

Although cloning by somatic cell nuclear transfer (SCNT) has been achieved in various mammalian species, its efficiency has been very low (Han et al. 2003 Theriogenology 59, 33–44). Successful cloning requires conversion from differentiated donor nuclei to embryonic nuclei after transfer of the somatic nuclei into enucleated oocytes. Reprogramming of the transferred somatic nuclei must be completed by the time when normal activation of the embryonic genome occurs (Solter 2000 Nat. Rev. Genet. 1, 199–207). Recently, both full-term development and pre-implantation development of mouse SCNT embryos were 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 objective of this study was to investigate the effects of TSA on the development of bovine SCNT embryos. Bovine fibroblasts were cultured under serum starvation (0.4% FCS) for 7 days and then used as donor cells. The cells were electro-fused with bovine enucleated matured oocytes, and activated with a calcium ionophore and cycloheximide. They were subsequently cultured in mSOF medium until 168 h post-activation (hpa). The NT embryos were exposed to 0 (control), 5, 50, and 500 nM TSA from the start of activation to 48 hpa. Experiments were repeated 3 times, and the data were analyzed with Fisher's PLSD test following ANOVA. The cleavage rates were the same among the groups (60 to 80&percnt;; P &gt;0.05). However, the blastocyst rate of NT embryos treated with 50 nM TSA was higher than that of control embryos (40&percnt; vs. 19&percnt;, respectively; P &lt; 0.05). On the other hand, the blastocyst rate was lower with 500 nM TSA than with 5 or 50 nM TSA (7&percnt; vs. 33&percnt; or 40&percnt;; P &lt; 0.05). These data suggest that proper TSA treatment after somatic cloning improves the rate of development of bovine cloned embryos to the blastocyst stage. Further research is needed to examine whether NT embryos derived from different cell lines or types have similar susceptibility to TSA.

324 EFFECT OF AGING ON AMOUNTS OF DNA METHYLTRANSFERASE mRNA IN MOUSE SPERMATOZOA

The spermatozoon is a specially differentiated cell designed to carry a haploid male genome into an oocyte at fertilization. It recently was reported that a matured spermatozoon contains several kinds of mRNAs and these are delivered into the oocyte at fertilization (Ostermeier et al. 2004 Nature 429, 154). The physiological role of paternally derived mRNAs is not clear; however, there is a report that the DNA methyltransferase (Dnmt) mRNA level in spermatozoa from male rats exposed to ethanol was significantly reduced (Bielawski et al. 2002 Alcohl. Clin. Res. 26, 347–351). The reduction of mRNA levels of Dnmt in spermatozoa would lead to altered epigenetic modification of the genome. Because factors such as age may affect spermatozoa mRNA levels, this study evaluated the effect of individual aging on the expression levels of Dnmts during spermatogenesis. This was accomplished by determining expression levels of Dnmts in the whole testis and in spermatozoa from young and aged mice by quantitative reverse-transcription-PCR. Seven- (young) and 68- (aged) week-old C57BL/6N male mice (n = 3/group) were sacrificed by cervical dislocation and whole testes and matured spermatozoa were collected. Total RNA was extracted and purified from each sample. In this study, 5 Dnmts (Dnmt1s, Dnmt1p, Dnmt3a, Dnmt3b, and Dnmt3l) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a reference gene, were examined for expression levels in whole testis and spermatozoa using SYBR Premix Ex Taq (Takara Bio, Inc., Otsu, Shiga, Japan) and the 7300 Real-Time PCR System (Applied Biosystems, Foster City, CA, USA). Real-Time PCR runs for each Dnmt and GAPDH were repeated 3 times using different RNA batches from different individuals. The GAPDH expression level was used to normalize the expression levels of each Dnmt. Data were analyzed by Student&apos;s t-test. Relative expression levels of each Dnmt in testis from aged males compared to that of young males were 0.94, 1.15, 0.91, 1.15, and 1.14 (Dnmt1s, Dnmt1p, Dnmt3a, Dnmt3b, and Dnmt3l, respectively). There was no difference in the expression levels of the 5 Dnmts examined between testes from aged and young males. On the other hand, the relative amounts of each Dnmt mRNA in spermatozoa from aged males compared to that of young males were 0.87, 0.01, 0.54, 1.07, and 1.75 (Dnmt1s, Dnmt1p, Dnmt3a, Dnmt3b, and Dnmt3l, respectively). There was a significant reduction (P &lt; 0.05) in the amount of Dnmt1p mRNA. The reason why the amount of Dnmt1p mRNA in spermatozoa from aged male mice showed such reduction is not clear. There was no difference in the relative expression levels of Dnmt1p in testis irrespective of male age. Dnmt1p is only translated in the spermatocyte during the pachytene stage in meiosis and its physiological role is not clear. To elucidate this male, age-related reduction of the amount of Dnmt1p mRNA in spermatozoa would clarify part of physiological role of Dnmt1p. This work was supported by Wakayama Prefecture Collaboration of Regional Entities for the Advanced of Technological Excellence, Japan, and by a Grant-in-Aid for the 21st Century Center of Excellence Program of the MEXT, Japan.

229 DERIVATION OF PRESUMPTIVE GONOCYTES IN VITRO FROM PRIMATE EMBRYONIC STEM CELLS

Embryonic stem cells (ESCs) of nonhuman primates are important for research into human gametogenesis, because of similarities between the embryos and fetuses of nonhuman primates and those of humans. Recently, the formation of germ cells from mouse ESCs in vitro has been reported. In this study, we established cynomolgus monkey ES (cyES) cell lines and attempted to induce their differentiation into germ cells in order to obtain further information on the development of primate germ cells by observing the transcripts of some markers reported as specific for germ cells. CyES cell lines were established using blastocysts produced by intracytoplasmic sperm injection (ICSI). For inducing superovulation, females were treated with 25 IU kg-1 pregnant mare serum gonadotropin once a day for 9 days, followed by 400 IU kg-1 hCG. Oocytes were collected at 40 h after injection of hCG. After sperm injection, embryos were cultured in mCMRL medium to the blastocyst stage. For cyES cell establishment, inner cell masses (ICMs) were isolated by immunosurgery. The ESC colonies developed at about 10 days after ICM plating, and 3 cell lines were successfully established (3/11; 27.3%). All cell lines expressed Oct3/4, SSEA-4, and ALP activity. These ESCs formed teratomas containing 3 different embryonic layers when injected into SCID mice. And the cells could be passaged over 50 times without losing their original properties. To observe in vitro gametogenesis, we attempted to induce differentiation by non-adherent conditions. When cyES cells differentiated spontaneously, the aggregated structures (i.e. embryoid bodies; EBs) accumulated vasa, the expression of which is restricted to germ cells, and some meiotic markers such as dmc1 and sycp1 that exist only in synaptonemal complexes in meiosis. The existence of these markers was also confirmed by immunocytochemistry on cryosections. Interestingly, these products expressed oct4 and nanog again at Day 16, though the expression of both genes diminished at once with onset of differentiation. In vivo, it is reported that vasa, oct4, and nanog are expressed in migrating PGCs, posibly throughout the development of germ cells into spermatocytes/oocytes. Given the results obtained with the meiotic markers, it is possible that developing germ cells such as PGCs or gonocytes could be formed in cynomolgus EBs as in previous cases with mouse or human EBs. These results demonstrate that cyES cells might contribute to putative germ cells in vitro by differentiating into EBs and could be used as a model for studying mechanisms of germ cell development. This study was supported by a Grant-in-Aid for the 21st Century COE Program of the Japan Mext and by a grant for the Wakayama Prefecture Collaboration of Regional Entities for the Advancement of Technology Excellence of the JST.

44 NUCLEAR TRANSFER IN CATTLE USING SOMATIC CELLS FROM FROZEN TESTICLES WITHOUT CRYOPROTECTANTS

Obtaining somatic cells from preserved organs or tissues is useful for the conservation and regeneration of genetic resources by nuclear transfer (NT). Bovine cells for NT have been obtained from cooled carcasses stored at 0�C for several days (Arat et al. 2005 Reprod. Fert. Dev. 17, 164 abst) and from fetal skin tissue cryopreserved with DMSO (Fahrudin et al. 2001 J. Vet. Med. Sci. 63, 1151–1154). However, frozen storage of organs or tissues without cryoprotectants was considered to be quite inappropriate for obtaining viable cells. We report here that viable donor cells for NT were obtained from bovine testicles after frozen storage without cryoprotectants. In the first experiment, we investigated whether viable cells can be recovered from frozen testicles castrated from Japanese Black bulls. The testicles were frozen at -80�C in a freezer for several days; then some were stored in liquid nitrogen for 10 months without cryoprotectants. Before thawing, the testicles were divided into 3 pieces, caput epididymis, cauda epididymis, and testis. Each piece was then put in saline at 42�C for quick thawing. Thawed tissues were minced into 5-mm pieces and incubated at 39�C for 2 h in DMEM containing 0.1% collagenase and 0.2% dispase. After filtration through a 250-�m nylon mesh filter, the filtrates were centrifuged at 250 � 4g for 5 min. Then precipitates were resuspended with MF-start� primary culture medium (TM Cell Research Inc., Fukui, Japan) and incubated at 38.5�C under the atmosphere of 5% CO2 in air with high humidity. After 5 days of incubation, the medium was replaced and nonadherent debris was discarded. Viable cells were obtained from the caput epididymis. These cells actively proliferated and expanded. In the next experiment, to determine whether these cells can be used for NT, the cells were electrically fused with enucleated bovine oocytes. Bovine fibroblasts taken from unfrozen ear tissue were used as controls. The NT embryos were activated by Ca-ionophore treatment, followed by treatment with cycloheximide for 6 h, and then cultured in mSOF for 168 h. NT embryos reconstructed from testicle cells did not significantly differ from NT embryos made with control cells with regard to blastocyst rates (22.1% and 20.2%), cell number of blastocysts [130 � 43 and 121 � 43 (mean � SD)], and ICM ratio (21.1% and 22.6%), respectively (ANOVA). These results suggest that somatic cells derived from bovine frozen testicles can be used for nuclear transfer. Further studies are needed to examine whether viable cells can be obtained from other frozen organs or tissues. This study was partially supported by a grant from the Wakayama Prefecture Collaboration of Regional Entities for the Advancement of Technological Excellence, JST.

50 DNA METHYLATION PROFILES OF UPSTREAM ELEMENTS OF Oct-3/4 GENE IN IN VITRO FERTILIZATION (IVF) AND SOMATIC CELL NUCLEAR-TRANSFERRED (SCNT) EMBRYOS

Cloning by adult somatic cell nuclear transfer (SCNT) has proven to be successful for the production of clones from many species (Keith 2004 Cytogenet. Genome Res. 105, 285). However, somatic cloning is currently highly inefficient. One of the reasons for this is that SCNT is believed to be associated with epigenetic errors including abnormal DNA methylation of the reconstructed embryo. The Oct-3/4 gene, a member of the POU transcription factor family, is expressed throughout the pre-implantation embryo. Abnormal expression of the Oct-3/4 gene in the nuclear-transferred embryo is either directly or indirectly caused by nuclear transfer and is suggested to be indicative of a general failure to reset the genetic program (Boiani et al. 2002 Genes Dev. 16, 1209). In this study, we investigated the DNA methylation profiles of the Oct-3/4 gene in the genome of SCNT embryos, using bisulfite sequencing analysis. Then, we observed the detailed subcellular localization of Oct-3/4 proteins in SCNT embryos using immunocytochemical (ICC) analysis. Nuclear transfer of cumulus cell nuclei was carried out as previously described (Wakayama et al. 1998 Nature 394, 369). After nuclear transfer, embryos were subsequently cultured in KSOM media to the morula and blastocyst stages. We compared the methylation profiles of 3 transcriptional control elements (distal enhancer, DE; proximal enhancer, PE; and promoter) of the upstream region of the Oct-3/4 gene with the genome of in vitro fertilization (IVF) and SCNT embryos. The methylation rate of CpG sites in the DE and promoter regions of both IVF and SCNT embryos was low at both the morula and the blastocyst stages. What&apos;s interesting is that there was a significant difference in the methylation level on CpG sites in the PE element between IVF and SCNT embryos. At the morula stage, the methylation level on CpG sites in the PE element was very low in the IVF embryo and moderately high in the SCNT embryo (0.9&percnt; and 26.3&percnt;). Conversely, at the blastocyst stage, CpG sites in the PE element showed high methylation in the IVF embryo and low methylation in the SCNT embryo (55.2&percnt; and 10.5&percnt;). CpG sites in the PE element were lightly methylated (3.0&percnt;) in the inner cell mass (ICM) of the IVF embryo. This means that the main portion of methylation in the IVF blastocyst embryo occurred at the trophectoderm (TE). On the other hand, in ICM of the SCNT embryo, the methylation level of each embryonic cell was almost the same in the whole blastocyst embryo (9.8&percnt; and 10.5&percnt;). As a result, it is highly possible that the CpG sites in the PE element of ICM were methylated as in the TE. ICC analysis revealed that some SCNT embryos showed aberrant Oct-3/4 expression in the TE. These results indicate that the methylation of CpG sites in the Oct-3/4 PE element may be related to expression of Oct-3/4 in the mouse IVF and SCNT embryos. These differences in methylation level between IVF and SCNT embryos were reflected as abnormal expressions of Oct-3/4 on SCNT embryos. This study was supported by the 21st COE Program of MEST. M.K. is a JSPS Research Fellow and supported by Grant-in Aid for Scientific Research (No. 1751132) of JSPS.

298 EFFECTS OF TRICHOSTATIN A DURING IN VITRO FERTILIZATION OF BOVINE OOCYTES ON SUBSEQUENT DEVELOPMENT, CELL NUMBER, AND ALLOCATION OF RESULTING EMBRYOS

Histone acetylation is one of the major mechanisms of epigenetic reprogramming of gamete genomes after fertilization or of transferred cell genomes after nuclear transfer to establish a totipotent state for normal development. In the fertilization of bovine oocytes, asynchronous histone acetylation occurs during pronuclear formation in the manner that modification of the paternal genome precedes that of the maternal genome (Wee et al. 2006 J. Biol. Chem. 281, 6048–6057). In the present study, the effects of trichostatin A (TSA), an inhibitor of histone deacetylase, during in vitro fertilization (IVF) of bovine oocytes on subsequent embryonic development were investigated. Cumulus-enclosed oocytes obtained from slaughterhouse ovaries were in vitro-matured (IVM) for 21 h in TCM-199 supplemented with 5% v/v FCS, 0.5 mM sodium pyruvate, 0.02 AU mL-1 FSH, and 1 �g mL-1 estradiol-17β at 39�C under 5% CO2 in air. After IVM, the oocytes were subjected to IVF with 3 � 106 mL-1 of Percoll gradient-selected sperm in a defined medium (Brackett and Oliphant 1975 Biol. Reprod. 12, 260–274) supplemented with 0 (control), 5, 50, and 500 nM TSA for 18 h. After IVF, presumptive zygotes were freed from cumulus cells and cultured in mSOF medium until 168 h post-insemination (hpi) at 39�C under 5% CO2, 5% O2, and 90% N2 with high humidity. Cleavage and blastocyst development were assessed at 48 and 168 hpi, respectively. Inner cell mass (ICM) and trophectoderm (TE) of blastocysts were differentially stained by the method of Thouas et al. (2001 Reprod. Biomed. Online 3, 25–29) to assess cell number and ICM/TE ratio. Experiments were replicated 3 times. Data are presented as means � SEM and statistically analyzed by multiple comparison with the Holm method. Rates of cleavage (0 nM: 71.0 � 7%, n = 102; 5 nM: 75.5 � 5%, n = 106; 50 nM: 68.8 � 6%, n = 105; and 500 nM: 71.7 � 4%, n = 98) and blastocyst formation (21.4 � 5%, 22.3 � 6%, 17.8 � 2%, and 18.2 � 2%, respectively) were similar among the groups. However, 500 nM TSA significantly (P &lt; 0.05) increased ICM and total cell numbers (59.8 � 4 and 143.5 � 7, respectively, n = 31) compared with the control (43.1 � 3 and 120.9 � 7, n = 31). In addition, ICM/TE ratios were higher in the 50 nM (0.81 � 0.08, n = 29) and 500 nM (0.92 � 0.2, n = 31) groups than in the control (0.59 � 0.04, P &lt; 0.05). These results suggest that TSA treatment during IVF of bovine oocytes does not affect the blastocyst rate but alters the cell numbers and their allocation to ICM and TE. Overriding epigenetic modification of the genome during fertilization may have a carryover effect on cell proliferation and differentiation in pre-implantation embryos. This study was supported by a grant from Wakayama Prefecture Collaboration of Regional Entities for the Advancement of Technological Excellence, JST.

281 EXPRESSION PROFILE AND KNOCKDOWN ANALYSIS OF A FUNCTIONALLY UNKNOWN DD2-2 GENE IN MOUSE PRE-IMPLANTATION EMBRYOS

Zygotic gene activation (ZGA) starts at the G2 phase at the 1-cell stage in the mouse. However, the molecular mechanism of ZGA has not been completely elucidated. We have investigated the molecular functions of many gene clusters, DD clones obtained by differential display assays for ovulated eggs at the M II stage and 1-cell stage embryos at the G2 phase. As a result, we have identified a functionally unknown gene, whose sequence did not match a known transcript in the gene bank DD2-2 gene. Here, we report the expression profile and knockdown analysis of the DD2-2 gene in mouse pre-implantation embryos. Nucleotide sequence analysis of the DD2-2 cDNA revealed that the open reading frame of 1056 bp encodes a protein of 351 amino acids with a predicted molecular mass of 41.5 kDa. The deduced amino acid sequence indicated that DD2-2 protein might be a soluble protein without a signal peptide. We first investigated the expression profiles of DD2-2 in pre-implantation embryos by quantitative real-time PCR using an ABI PRISM 7300 Sequence Detection System (Applied Biosystems, Foster City, CA, USA). To investigate the effect of knockdown of the DD2-2 gene on the development of pre-implantation embryos, we injected pβ-act/antisenseDD2-2/IRES/EGFP into male pronuclei of embryos at 7 to 9 h after insemination (hpi) and observed the development of embryos that showed EGFP expression at 24 hpi. Real-time PCR analysis of pre-implantation embryos showed that maternal DD2-2 mRNA at a low level significantly increased up to the early 2-cell stage, and significantly decreased by the 4-cell stage and later, suggesting that DD2-2 gene specifically expresses at major ZGA. In the knockdown analysis, EGFP-positive embryos with pβ-act/antisenseDD2-2/IRES/EGFP showed a lower rate of development to the 4-cell stage and later, compared with that of EGFP-positive embryos with pβ-act/luc+/IRES/EGFP [72% (94/130) vs. 54% (71/131); P &lt; 0.05], indicating that the knockdown of DD2-2 by antisense RNA resulted in a inhibition of pre-implantation development. In conclusion, the DD2-2 gene, a functionally unknown gene, may play an important role in pre-implantation development. This study was supported by a Grant-in-Aid for the 21st Century COE Program of the Japan Mext and by a grant for the Wakayama Prefecture Collaboration of Regional Entities for the Advancement of Technology Excellence of the JST.

227 DIFFERENTIATION OF HEPATOCYTE-LIKE CELLS FROM MOUSE EMBRYONIC STEM CELLS IN A MONOLAYER CULTURE SYSTEM

Embryonic stem (ES) cells can be differentiated in vitro into a variety of cell lineages. In vitro differentiation of ES cells, therefore, provides a model system for organogenesis as well as an innovative approach for regenerative medicine. However, current in vitro hepatic differentiation systems from ES cells require embryoid body formation, and such systems achieve quite low differentiation efficacy. In this study, in order to examine a system for preparation of significant numbers of hepatocytes from ES cells, mouse ES cells were directly differentiated into hepatocyte-like cells using monolayer culture conditions, and their hepatic characteristics were examined. ES cells were cultured on gelatin-coated plates for 3 days in ES cell medium containing leukemia inhibitory factor (100 units mL-1) and retinoic acid (10-8 M). After 3 days, the cells were harvested by trypsinization and cultured on gelatin-coated plates for 5 days in ES cell medium containing acidic fibroblast growth factor (aFGF; 100 ng mL-1), FGF4 (20 ng mL-1), and human growth factor (50 ng mL-1). After 5 days, the cells were passaged on type I collagen-coated plates for 2 days in ES cell medium containing Oncostatin M (10 ng mL-1), followed by additional culture in modified William&apos;s E medium containing 5% FBS and dexamethasone (10-7 M) for 7 days. For characterizing the differentiated ES cells, the cells were examined for albumin production by immunocytochemistry, and the expression profiles of hepatic genes by RT-PCR. For analyzing their hepatic function, the cells were examined for glycogen production by PAS staining, and their metabolic activities of ammonia elimination and urea synthesis were measured. After 10 days of culture, almost all cells showed albumin production by immunofluoresence. RT-PCR analysis showed expression of various genes specific for hepatocytes, such as ALB, AFP, TTR, and HNF3�, but not HNF4α, and genes specific for matured hepatocytes, such as PEPCK, TAT, G6P, and Cyp7a1. After 11 days of culture, glycogen production was partially detected in the hepatocyte-like cells by PAS staining. Although ammonia elimination activity of hepatocyte-like cells was shown to be significantly lower than that of the primary culture of fetal hepatocytes after 24 and 48 h of treatment (P &lt; 0.05), its metabolic activity was acquired at the level of about 40% of that of fetal hepatocytes. Hepatocyte-like cells also showed lower activity of urea synthesis than fetal hepatocytes at 6, 12, and 24 h of treatment (P &lt; 0.05), but this activity increased thereafter and reached about 70% of that of fetal hepatocytes after 48 h of treatment. These results demonstrated that monolayer culture conditions for ES cell differentiation could provide an in vitro system to produce significant numbers of hepatocytes. This work was supported by a Grant-in-Aid for the 21st Century Center of Excellence Program of the MEXT, Japan, and by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science.

Association between dietary fiber, water and magnesium intake and functional constipation among young Japanese women

OBJECTIVE

Most research on constipation has focused on dietary fiber intake. Here, we examined the intake of water and magnesium, nutrients possibly associated with constipation, as well as that of dietary fiber in relation to constipation.

DESIGN

Cross-sectional study.

SUBJECTS

A total of 3835 female Japanese dietetic students aged 18-20 years from 53 institutions in Japan.

METHODS

Dietary intake was estimated with a validated, self-administered diet history questionnaire. Functional constipation was defined using the Rome I criteria.

RESULTS

The prevalence of functional constipation was 26.2%. Neither dietary fiber intake (mean=6.4 g/4186 kJ) nor intakes of total water and water from fluids were associated with constipation. Conversely, low intake of water from foods was associated with an increasing prevalence of constipation. In comparison with women in the first (lowest) quintile, the multivariate adjusted odds ratio (OR) (95% confidence interval (CI)) for women in the second, third, fourth, and fifth quintiles were 0.72 (0.57, 0.90), 0.78 (0.62, 0.98), 0.71 (0.56, 0.89), and 0.77 (0.61, 0.97), respectively (P for trend=0.04). Additionally, low magnesium intake was associated with increasing prevalence of constipation. Compared with women in the first quintile, the multivariate adjusted OR (95% CI) for women in the second, third, fourth and fifth quintiles were 0.70 (0.56, 0.88), 0.75 (0.60, 0.95), 0.73 (0.58, 0.92) and 0.79 (0.63, 0.996), respectively (P for trend=0.09).

CONCLUSIONS

Low intakes of water from foods and magnesium are independently associated with an increasing prevalence of functional constipation among a population whose dietary fiber intake is relatively low.

Preservation of ovarian function by ovarian shielding when undergoing total body irradiation for hematopoietic stem cell transplantation: a report of two successful cases

The purpose of this study was to evaluate the possibility of preserving ovarian function by ovarian shielding to reduce the irradiation dose in total body irradiation (TBI). The subjects in the study were females aged less than 40 years, who were undergoing allogeneic hematopoietic stem cell transplantation using a TBI-based regimen and who desired to have children after transplantation. For ovarian shielding, abdominal computed tomography (CT) and skin marking were performed in both the supine and prone positions, prior to the TBI. A pair of columnar blocks was placed just above the patient's body. Thus far three patients have been treated. The serum estradiol level decreased to an undetectable level (<8.5 pg/ml) after transplantation and the follicle-stimulating hormone (FSH) level increased above 90 mIU/ml in all patients and they became amenorrheic. However, regular menstruation recovered in patients no. 1 and 2 about 800 and 370 days after transplantation, respectively, with a decrease in the serum FSH level. Menstruation did not recover in patient no. 3, and serum estradiol was transiently detected above 20 pg/ml. The preservation of ovarian function was made possible by ovarian shielding. However, a longer follow-up is needed to know if normal pregnancy and delivery can occur.

Dietary glycemic index and load in relation to metabolic risk factors in Japanese female farmers with traditional dietary habits

BACKGROUND

Little is known about the relation of dietary glycemic index (GI) and glycemic load (GL) to metabolic risk factors, particularly in non-Western populations.

OBJECTIVE

We examined the cross-sectional associations between dietary GI and GL and several metabolic risk factors in healthy Japanese women with traditional dietary habits.

DESIGN

The subjects were 1354 Japanese female farmers aged 20-78 y from 5 regions of Japan. Dietary GI and GL were assessed with a self-administered diet-history questionnaire. Body mass index (BMI) was calculated as weight (kg) divided by the square of height (m). Fasting blood samples were collected for biochemical measurements.

RESULTS

The mean dietary GI was 67, and the mean dietary GL (/1000 kcal) was 88 (GI for glucose = 100). White rice (GI = 77) was the major contributor to dietary GI and GL (58.5%). After adjustment for potential dietary and nondietary confounding factors, dietary GI was positively correlated with BMI (n = 1354; P for trend = 0.017), fasting triacylglycerol (n = 1349; P for trend = 0.001), fasting glucose (n = 764; P for trend = 0.022), and glycated hemoglobin (n = 845; P for trend = 0.038). Dietary GL was independently negatively correlated with HDL cholesterol (n = 1354; P for trend = 0.004) and positively correlated with fasting triacylglycerol (P for trend = 0.047) and fasting glucose (P for trend = 0.012).

CONCLUSIONS

Both dietary GI and GL are independently correlated with several metabolic risk factors in subjects whose dietary GI and GL were primarily determined on the basis of the GI of white rice.

Dietary patterns associated with bone mineral density in premenopausal Japanese farmwomen

BACKGROUND

Because several nutrients are known to affect bone mineral density (BMD), the analysis of dietary patterns or combinations of foods may provide insights into the influence of diet on bone health.

OBJECTIVE

We evaluated associations between dietary patterns and BMD in Japanese farmwomen.

DESIGN

The study included 291 premenopausal farmwomen (aged 40-55 y) who participated in the Japanese Multi-centered Environmental Toxicant Study (JMETS; n = 1407). Forearm BMD was measured by using dual-energy X-ray absorptiometry. Diet was assessed by using a validated self-administered diet history questionnaire comprising 147 food items, from which 30 food groups were created and entered into a factor analysis.

RESULTS

Four dietary patterns were identified. The "Healthy" pattern, characterized by high intakes of green and dark yellow vegetables, mushrooms, fish and shellfish, fruit, and processed fish, was positively correlated with BMD after adjustment for several confounding factors (P = 0.048). In contrast, the "Western" pattern, characterized by high intakes of fats and oils, meat, and processed meat, tended to be inversely associated with BMD; however, the association was not significant (P = 0.08).

CONCLUSION

A dietary pattern with high intakes of fish, fruit, and vegetables and low intakes of meat and processed meat may have a beneficial effect on BMD in premenopausal women.

69 RELATION OF SPATIAL GENE EXPRESSION PATTERNS IN BOVINE EMBRYOS RECONSTRUCTED WITH SOMATIC CELLS TO BLASTOCYST DEVELOPMENT

Recently, enhanced development to full term was obtained with embryos reconstructed with bovine early G1 cells rather than with G0 cells (Kasinathan et al. 2001 Nat. Biotechnol. 19, 1176-1178; Urakawa et al. 2004 Theriogenology 62, 714-728). However, the reason why donor somatic cells at the early G1 phase are better for embryo reconstruction is unclear. In this study, we investigated the relation of spatial gene expression patterns at the 4- to 8-cell stage to blastocyst development of embryos reconstructed with early G1 cells. Bovine fibroblasts stably transfected with �-act/luc+/IRES/EGFP were used for embryo reconstruction. M phase cells were prepared as described by Urakawa et al. (2004). Early G1 cells were obtained from cultured M phase cells soon after the M phase cells divided. Quiescent cells (cultured in 0.4% serum for 7 days) were used as G0 cells for a control. The cells were electrofused with enucleated bovine oocytes matured in vitro, and activated with a calcium ionophore and cycloheximide. The reconstructed embryos were cultured until 60 hours post fusion (hpf), and zonae pellucidae of 4- to 8-cell embryos were removed by pronase. To determine gene expression, the LUC+ activity (luminescence) in the embryo blastomeres was detected with an imaging photon counter (Hamamatsu Photonics, Hamamatsu City, Shikuoka Prefecture, Japan) for 10 min. The embryos were categorized as being positive, mosaic, or negative depending on whether all, some or no blastomeres were luminescent, respectively. The embryos were cultured in mSOF medium individually until 168 hpf to assess development to the blastocyst stage. Blastocyst development of reconstructed embryos without detection of luminescence was also examined. Experiments were repeated three times, and the data were analyzed with Fisher's PLSD test following ANOVA. At 60 hpf, 75% (74/99) of embryos reconstructed with early G1 cells and 55% (46/83) of embryos with G0 cells developed to 4- to 8-cell stage embryos. The difference is significant (P < 0.05). The percentages of positive, mosaic, and negative embryos with G1 cells were 49, 35 and 16%, and blastocyst rates were 30, 11, and 0%, respectively. With G0 cells, the percentages were 32, 56, and 12%, and the blastocyst rates were 15, 4, and 0%, respectively. More positive embryos were obtained with early G1 cells than with G0 cells (P < 0.05). Blastocyst rates of the positive embryos with early G1 cells were the same as with G0 cells (P > 0.05). Blastocyst development of positive embryos was higher than that of mosaic and negative embryos in early G1 and G0 groups (P < 0.05). Without detection of luminescence, the blastocyst rates from the reconstructed embryos were 43% (35/81) and 16% (20/125) with early G1 and G0 cells, respectively (P < 0.05). These results suggest that the higher developmental capacity of embryos reconstructed with early G1 cells might be related to the appropriate spatial gene expression at the 4- to 8-cell stage. A part of this study was supported by a grant from the Wakayama Prefecture Collaboration of Regional Entities for the Advancement of Technological Excellence of the JST.

136 FUNCTIONAL ANALYSIS OF RHOPHILIN-2 GENE IN PRE-IMPLANTATION MOUSE EMBRYO

Zygotic gene activation (ZGA), which starts at the G2 phase at the 1-cell stage (Latham 1999), promotes the reprogramming of gene expression and is critical for the subsequent development of pre-implantation embryos. We have investigated the molecule function of many gene clusters, DD clones obtained by Differential-Display assays for ovulated eggs at the M II stage, and 1-cell embryos at the G2 phase. The differential expression of rhophilin-2 shown in DD assays was also confirmed by 3 independent real-time PCR analyses (P < 0.05). For these reasons, in this study, we focused on the rhophilin-2 gene, which regulates cytoskeletal organization (Peck et al. 2002). At first, we identified a protein that interacts with the Rhophilin-2 protein by a yeast 2-hybrid system. To confirm the interaction between Rhophilin-2 and the putative protein obtained by a yeast two-hybrid system, we used a co-immunoprecipitaion assay. We also investigated the expression profiles of rhophilin-2 and the transcripts of the identified protein in ovary and pre-implantation embryos using real-time PCR and immunofluorescence (IF) analysis. The ICR mice at 48 h after PMSG priming were primed with hCG, and ovaries were collected at 7 h after hCG priming. Pre-implantation embryos were collected at 1-cell, 2-cell, and 4-cell stages, and cDNA was produced by mRNA isolated from 10 oocytes or embryos in each group and was subjected to real-time PCR using a TaqMan Probe system (ABI). Sectioned ovaries and pre-implantation embryos were analyzed by IF analysis using antibody of Rhophilin-2 and the identified protein. This is the first report that GABA receptor-association protein (GABARAP) was identified as a protein that interacts with Rhophilin-2, as a result of using the yeast 2-hybrid system and subsequent co-immunoprecipitation assay. After fertilization, transcript levels of rhophilin-2 significantly decreased from the 1-cell stage to the 2-cell stage (P < 0.05), but transcript levels of GABARAP significantly increased from the 1-cell stage to the 2-cell stage (P < 0.05). The IF analysis revealed localization of Rhophilin-2 and GABARAP at the nucleolus of all follicle stage in the ovary. Moreover, Rhophiln-2 and GABARAP were found to be localized on the microtubules of 1-cell and 2-cell embryos, but no signal of Rhophilin-2 was detected in 4-cell embryos. These results suggest that Rhophilin-2 protein regulates the cytoskeletal organization in 1-cell to 2-cell embryos and is involved in the molecular mechanism of cell division by coupling with GABARAP. This study was supported by a Grant-in-Aid for the 21st Century COE Program of the Japan Mext and by a grant for the Wakayama Prefecture Collaboration of Regional Entities for the Advancement of Technology Excellence of the JST.