Targeted suppression of E-cadherin gene expression in bovine preimplantation embryo by RNA interference technology using double-stranded RNA

RNA interference (RNAi) has become acknowledged as an effective and useful tool to study gene function in diverse groups of cells. We aimed to suppress the expression of the E-cadherin gene during in vitro development of bovine preimplantation embryos using RNAi approach. In this experiment the effect of microinjection of E-cadherin and Oct-4 (as control) double-stranded (ds) RNA on the mRNA and protein expression level of the target E-cadherin gene was investigated. For this, a 496 bp long bovine E-cadherin and 341 bp long Oct-4 dsRNA sample were prepared using in vitro transcription. In vitro produced bovine zygotes were categorized into four treatment groups including those injected with E-cadherin dsRNA, Oct-4 dsRNA, RNase-free water, and uninjected controls. While the injection of E-cadherin dsRNA resulted in the reduction of E-cadherin mRNA and protein levels at the morula and blastocyst stage, the transcript and protein product remained unaffected in the Oct-4 dsRNA, water injected and uninjected control groups. The relative abundance of E-cadherin mRNA in the E-cadherin dsRNA injected morula stage embryos was reduced by 80% compared to the control group (P < 0.05). The Western blot analysis also showed a significant decrease in the E-cadherin protein (119 kDa) in E-cadherin dsRNA injected embryos compared to the other three groups. Microinjection of E-cadherin dsRNA has resulted only 22% blastocyst rate compared to 38%-40% in water injected and uninjected controls. In conclusion, our results indicated the suppression of E-cadherin mRNA and protein has resulted in lower blastocyst rate and the RNAi technology is a promising approach to study the function of genes in early bovine embryogenesis.

Bovine blastocyst diameter as a morphological tool to predict embryo cell counts, embryo sex, hatching ability and developmental characteristics after transfer to recipients

The aim of the present study was to explore whether the blastocyst diameter and the zona thickness at 168 h after fertilisation are useful parameters to predict quality and viability of bovine in-vitro-produced (IVP)-embryos. Although significant (P < 0.05), the blastocyst diameter at 168 h correlated only poorly with the total number of cells (R2 = 0.13) and with the number of trophectoderm (TE) cells (R2 = 0.17). Hatched blastocysts (n = 66) at 216 h had a significantly greater mean diameter at 168 h (194.8 ± 16.8 µm) compared with either blastocysts that had started but not finished hatching at 216 h (n = 26, 178.4 ± 16.7 µm) or failed to commence hatching (n = 136, 162.7 ± 12.9 µm). Transfer of 101 IVP blastocysts to synchronised recipients resulted in the birth of 38 calves (38%). There were significantly more bull calves born than cow calves (P < 0.05), but this was not correlated with blastocyst diameter or zona thickness at 168 h. There was also no correlation between the diameter of blastocysts or the zona thickness at 168 h and parameters of subsequent developmental characteristics, including rates of pregnancy, resorptions and abortions, pregnancy duration, delivery to term and birthweight. Overall, the present results indicate that the blastocyst diameter and the zona thickness at 168 h are good predictors for subsequent hatching ability in vitro, but not for the number of TE cells, inner cell mass cells or total cells and neither for subsequent developmental characteristics after transfer to recipients.

267 TARGETED SUPPRESSION OF THE EXPRESSION OF MATERNAL AND EMBRYONIC GENES DURING IN VITRO DEVELOPMENT OF BOVINE EMBRYOS

Despite enormous advances in the identification and sequencing of developmentally relevant bovine genes, the function of the majority of these transcripts is not yet known. Here we aimed to apply the RNA interference (RNAi) approach to suppress the expression of the maternal transcript c-mos (AY630920) and embryonic transcripts E-cadherin (AY508164) and Oct-4 (AY490804) during in vitro development of bovine embryos using microinjection of sequence-specific double-stranded RNA (dsRNA). For this 435-, 341- and 341-bp-long dsRNA specific to the coding sequences of c-mos, E-cadherin and Oct-4 transcripts, respectively, were synthesized using Promega RiboMax" T7 system (Promega, Madison, WI, USA), where sense and antisense strands were transcribed from the target DNA template. Slaughterhouse ovaries were used to aspirate bovine oocytes, which were matured in TCM-199 with 12% estrus cow serum (ECS), fertilized in Fert-TALP, and cultured in CR1 medium at 39�C under humidified atmosphere of 5% CO2 in air. In Experiment 1, immature oocytes were categorized into three groups, each containing 50-60 oocytes: those injected with c-mos dsRNA, those injected with RNase-free water, and uninjected controls. In Experiment 2, zygotes were categorized into four groups, each containing 50-60 zygotes: those injected with E-cadherin dsRNA, those injected with Oct-4 dsRNA, those injected with RNase-free water, and uninjected controls. Each experiment was repeated four times. The effect of dsRNA on in vitro development of oocytes or embryos was assessed after microinjection during culture. The level of mRNA and protein expression was investigated using real-time PCR and western blot analysis, respectively. Data were analyzed using SAS, version 8 (SAS Institute Inc., Cary, NC, USA). Microinjection of c-mos dsRNA resulted in a 70% reduction of c-mos transcript abundance after maturation compared to the water-injected and uninjected controls (P < 0.05). Similarly, microinjection of E-cadherin and Oct-4 dsRNA at the zygote stage resulted in 80% and 60% reduction in transcript abundance at the blastocyst stage, respectively, compared to the uninjected controls (P < 0.05). Decreases in the c-mos (39 kDa) and E-cadherin proteins (119 kDa) were observed in the c-mos and E-cadherin dsRNA-injected groups, respectively, compared to the control. A higher proportion of oocytes (75%) showed first polar body extrusion after maturation in c-mos dsRNA-injected groups, compared to 52% in water-injected and 57% in uninjected controls. Only 22% from E-cadherin dsRNA- and 24% from Oct-4 dsRNA-injected zygotes developed to the blastocyst stage compared to 39 and 37% blastocyst rates in water-injected and uninjected control groups, respectively. In conclusion, injection of sequence-specific dsRNA in bovine oocytes and embryos resulted in suppression of mRNA and their protein products, thereby affecting in vitro development of bovine embryos.

Polymorphisms of the androgen receptor gene associate with fatness, uterus and ovary measurements in the pig

Abstract. Quantitative trait loci, QTL, for fatness and carcass traits in pigs have been recently mapped to the X chromosome approximately at the position where the androgen receptor gene (AR) is localized. The AR acts as a nuclear transcription factor regulating expression of a number of androgenic response genes during various stages of sexual development. The present study aimed to analyze association of the AR genotype on traits related to fatness and phenotype of primary female sexual organs, ovary and uterus. Animals of a F2 resource population based on Duroc and Berlin Miniature pig were genotyped at a multi-allelic microsatellite marker (CCTTT)n situated in the 5' untranslated region and a bi-allelic CAG-insertion/deletion polymorphism (CAG-INDEL) within exon 1 of the AR. Association analysis showed that the AR genotype both at the CAG-INDEL and microsatellite affect almost all fatness traits measured. The D allele inherited from Duroc was associated with the decrease of fat thickness. The AR genotypes also affect uterus and ovary measurements. The pigs homozygous for D allele were likely to have a lighter uterus, shorter uterus horns, oviducts and smaller ovaries than pigs homozygous for the M allele. Our results confirm the previously reported QTL for fatness traits and provide evidence for a QTL affecting dimensions of uterus and ovary on the X chromosome. The AR is a positional functional candidate gene for both trait complexes.

Divergent selection for ω3:ω6 polyunsaturated fatty acid ratio in quail eggs

Abstract. It is well known, that the ω6:ω3 PUFA (polyunsaturated fatty acids) ratio of the egg yolk can be changed by modifying the hen's diet. Information on genetic effects on PUFA in egg yolks is limited. Therefore four generations of divergent selection of high and low ω6:ω3 PUFA ratio were performed with quails as model animals to estimate genetic effects on the fatty acid profile of eggs. Heritability and correlated response to selection were analysed. Generation 4 consisted of 125 hens in the HIGH and 114 hens in the LOW line and 40 sires per line. Fatty acid profiles of the eggs were measured on pools of 3 yolks per hen, two times per hen. After four generations of selection ω6:ω3 PUFA ratio was significantly different in the LOW (12.4) and HIGH line (14.9), i.e. a difference of 1.6 phenotypic standard units. Heritability for ω6:ω3 PUFA ratio was estimated at 0.45 (SE 0.05). Selection tended to be asymmetric in the way that response to selection in the LOW line was higher. Fertility and hatchability of fertile, age at first egg, laying intensity, egg weight and fat percentage were not significantly different between selected lines, but yolk weight, yolk proportion and fat content were significantly higher in the Low line. Moderate heritability of ω6:ω3 PUFA ratio in egg yolks and lack of correlated responses to selection in major production and reproduction traits indicate that breeding for a lower ω6:ω3 PUFA ratio in eggs is promising.

Identification of functional candidate genes for body composition by expression analyses and evidencing impact by association analysis and mapping

This study aims to identify hepatic genes affecting traits related to muscularity and obesity by combining expression analyses, association studies, and gene mapping. Functional candidate genes with trait-associated expression were obtained by hybridising custom made application-specific cDNA microarrays with targets of discordant sib pairs of a porcine experimental population. Out of 238 genes addressed, nine genes were regulated by the factor>or=2 between the sib pairs. Differential gene expression was independently confirmed for selected genes by real time RT-PCR. Transcript levels of four genes (APOH, PEDF, SLCO1B3, TBG) were significantly different between the phenotype groups. Screening for trait associated markers within TBG and APOH by comparative sequencing of discordant sib pairs revealed a SNP at position nt 778 (A>C) (N229H) of TBG. No polymorphism in APOH was detected. Association analysis confirmed effects of TBG on carcass traits statistically. Allocating TBG to a QTL region on chromosome X revealed genetic evidence for the effect. Moreover, our results indicate that there are probably two polymorphisms segregating-one (N229H) altering binding capability of TBG and another still to be detected altering the transcription rate of TBG.

Expression of retinoid X receptor transcripts and their significance for developmental competence in in vitro-produced pre-implantation-stage bovine embryos

Retinoid X receptors are frequently implicated in their role in embryonic development. However, there is no report regarding their expression in embryos with different qualities. In this study, expression pattern and levels of retinoid X receptor transcripts in different qualities and stages of in vitro-produced pre-implantation bovine embryos were examined using real-time polymerase chain reaction (PCR) techniques. Four independent cDNA pools per sample were prepared from mRNAs isolated from different developmental-stage embryos, after classifying them to be of good and bad quality. Primers were also designed to amplify products with PCR. Based on analysis, except retinoid X receptor gamma (RXRG) transcripts, the remaining two types (alpha and beta forms) were expressed in all samples with significantly higher (p < or = 0.05) levels until the eight-cell stage compared with the stages thereafter. However, the transcript levels for bad-quality embryos were consistently lower in all cases in comparison with good-quality embryos. RXRG was identified in 39% of the samples, but all in the pre-embryonic genome activation development stage. Therefore, strong expression patterns of these transcripts in earlier stages indicates their possible role during the maternal phase of embryo development, and the variations of copy number in embryos with different qualities substantiates their possible candidacy as potential quality markers. Moreover, identifying the transcript variations in different qualities and expression of RXRG at these stages is a novel input to the pre-implantation-stage knowledge.

Intrafallopian transfer of gametes and early stage embryos for in vivo culture in cattle

It may be possible to avoid inadequate in vitro culture conditions by incubating gametes or embryos in the oviducts for a short time. Ideally, an optimized procedure should be devised, combining in vitro and in vivo systems, in order to achieve synchronization in cattle. We transferred gametes as well as embryos in various stages of development and placed them into the oviducts. Embryos were recovered on Day 7 by flushing of oviducts and uterine horns. Blastocyst rates were determined on Day 7 and on Day 8. Experimental designs included transfer of in vitro matured cumulus oocyte complexes into previously inseminated heifers (COCs group), transfer of in vitro matured COCs simultaneously with capacitated spermatozoa (GIFTs group), transfer of four to eight cell stage embryos developed in vitro after IVM/IVF (Cleaved Stages group) and a group of solely in vitro produced embryos (IVP control group). Our results indicate that in vivo culture of IVM/IVF embryos in the homologous bovine oviduct has a positive influence on subsequent pre-implantation development. In addition, we have evidence that in vitro maturation and in vivo fertilization cannot be synchronized.

Polymorphisms in candidate genes as markers for sperm quality and boar fertility

Alpha-actinins (ACTN1 and ACTN4) and gamma-actin (ACTG2), were investigated as candidate genes on the basis of their known functions, for their possible association with sperm concentration, motility, semen volume per ejaculate, plasma droplets rate, abnormal sperm rate and the fertility traits, non-return rate and number of piglets born alive. Polymorphisms were identified in intron 18 (G>A) of the porcine ACTN1 gene and in exon 22 (A>C) of the porcine ACTN4 gene by comparative sequencing of animals from the Pietrain (PI) and Hampshire (HA) breeds. Pietrain (n = 244) and crossbreed PI x HA (n = 112) boars from an artificial insemination boar station were genotyped for the single nucleotide polymorphisms (SNPs) within ACTN1 and ACTN4 as well as for a previously described microsatellite within ACTG2. The study provides evidence for effects of ACTN1 on fertility and of ACTG2 on sperm quality traits, while no indication of impact of ACTN4 on any of these traits was found.

227 CONSTRUCTION OF STAGE-SPECIFIC cDNA MICROARRAY, AND ANALYSIS OF IN VITRO PRODUCED PRE-IMPLANATION STAGE BOVINE EMBRYOS FOR DEVELOPMENTAL COMPETENCE

Microarray technology currently has wide acceptance as a research tool in the study of gene expression profiling, mainly as a result of its use for monitoring the expression profiles of thousands of genes in a single experiment. However, its use in analyzing gene expression in the pre-implantation stage of bovine embryo development has been limited for reasons such as the large amount of RNA required and the lack of bovine specific cDNA clone collections (Smith L and Greenfield A 2003 Hum. Mol. Genet. 12, 1–8). In this study, with the objectives of producing pre-implantation-stage-specific bovine cDNA clones and examining the developmental competence, eighty-two selected target clones of pre-implantation-stage-specific genes were prepared and spotted on the glass slide. Embryos were produced in vitro and mRNAs were isolated from contrasting probes of good quality matured oocytes and blastocyst-stage embryos using a Dynabead mRNA isolation kit by following the manufacturer's instructions. First-strand cDNA syntheses were primed with T7 Oligo d(T)21 primer, followed by random primed second-strand syntheses using a DOP master kit (Roche Diagnostics, Mannheim, Germany) and global amplification using the same primers used for the first- and second-strand syntheses. In vitro transcription was performed to amplify the RNA by using the AmpliScribe T7 transcription kit (EPICENTRE Technologies, Oldendorf, Germany), and the amplified RNA (aRNA) was purified using a RNeasy Mini kit (Qiagen, Hilden, Germany). Finally, the results of different RNA amplifications (aRNA) were tested by hybridization on microarrays and also using real-time PCR techniques. With these analyses, the sufficiency of the yield and linearity of amplification procedures were confirmed. Three micrograms each of aRNA were labelled with Cy3 and Cy5 dyes and hybridized to the array. After overnight incubation at 42°C, the slides were sequentially washed and scanned using an ArrayWorx biochip reader (Applied Precision, Marlborough, UK), and quantifications as well as all analyses were carried out using different TIGR software modules (Saeed AI et al. 2003 Biotechniques 34(2), 374–378). Analyses of the results of repeated hybridizations showed that 35 genes (43%), which belong to different functional groups, were differentially expressed between the two stages. Further independent analyses using real-time PCR confirmed the results of 25 genes. Hence, it is possible to conclude that the established methods can be used for large scale gene expression analysis, and the identified genes can be potential candidates for characterizing developmental competence.

160 IN VIVO-CULTURE OF BOVINE EMBRYOS: TRANSFER OF SEMEN PRE-INCUBATED OOCYTES, ZYGOTES AND 4 TO 8 CELL STAGE EMBRYOS INTO THE BOVINE OVIDUCT

Oviduct as well as oocyte and embryo development are subject to developmental changes which have crucial effects on the application of in vivo culture. The present study aimed at optimizing in vivo culture of IVP bovine embryos at different developmental stages in the bovine oviduct. Cumulus oocyte complexes (COC) were collected from slaughterhouse ovaries, matured in vitro for 22 h and assigned to four groups. In groups I and II, oocytes were pre-incubated for 3 to 4 h with 5 × 106 sperm/mL, and then immediately transferred to recipients, which had just completed ovulation (group I), or kept in vitro for a further 12 to 18 h and transferred to Day 1 synchronized recipients (group II). In groups III and IV, COC were subjected to standard IVF/IVC; then embryos were either transferred at the 4- to 8-cell stage on Day 3 into the oviducts of Day 3-synchronized recipients (group III) or kept in vitro for a further 4 to 5 days (group IV). Thirty-four 18- to 30-month-old temporary recipients were synchronized using a standard Ovsynch protocol. COC and embryos were transferred and re-collected by transvaginal endoscopy. COC or embryos were loaded into a 180° curved glass capillary, which was inserted via the infundibulum 5 to 8 cm deep into the ampulla ipsilateral to the CL. On recipient Day 7, a 90° curved metal canula served for tubal flushing prior to conventional uterine embryo flushing. Sixty mL of PBS containing 1% fetal calf serum were rinsed through the oviduct into the uterus and a further 400 mL of medium were finally used for flushing of the uterine horn and collected via an embryo filter. Embryo development was evaluated directly after flushing (Day 7) and on Day 8. For statistical analysis (ANOVA), the blastocyst rates (Days 7 and 8) in group III were related to COC corrected by the collection rate. In group I, 575 COC were transferred to 11 recipients and 420 (73%) were re-collected as oocytes or embryos. The blastocyst yields on Day 7 and Day 8 were 23% (97) and 25% (104), respectively. In group II, the transfer of 489 presumptive zygotes into 13 heifers resulted in only 175 re-collected (36%), of which 15% developed into blastocysts (Day 7: 26; Day 8: 27). Ten heifers (group III) served for in vivo culture of 643 embryos at the 4- to 8-cell stage. On Day 7, 568 (88%) embryos were flushed and 171 (30%) reached the blastocyst stage. A further 24 h culture in vitro finally resulted in 244 (42%) blastocysts. The complete in vitro production system delivered 13% (63/477) blastocysts on Day 7 and 34% (161/477) blastocysts on Day 8. The collection rates (P < 0.001) and the blastocyst rates on Day 7 (P < 0.05) and Day 8 (P < 0.001) differed significantly in all groups. The present data demonstrate that the developmental stage of transferred complexes has an influence on embryo recovery as well as an embryo development. This work was supported by Austrian BMBWK and BMLFUW (#1227).

108 THE ROLE OF NITRIC OXIDE SYNTHASE IN IN VITRO DEVELOPMENT OF BOVINE OOCYTES AND PRE-IMPLANTATION EMBRYOS

Nitric oxide (NO) is a free radical that serves as a key-signal molecule in various physiological processes including reproduction. Four isoforms of nitric oxide synthase (NOS) have been characterized: endothelial (eNOS), inducible (iNOS), neuronal (nNOS), and mitochondrial (mtNOS). The first two isoforms are reported to be expressed in mouse follicles, oocytes, and pre-implantation embryos (Nishikimi A et al. 2001 Reproduction 122, 957–963). However, the role of any of these isoforms have not yet been investigated in bovine embryos. Here we aimed to examine the role of NOS in in vitro development of bovine embryos by treating embryos with NOS inhibitor, N-omega-L-nitro-arginine methyl esther (L-NAME), and examining the localization of the protein in pre-implantation embryos. Oocytes and embryos were grown in the media with NOS inhibitor added at a level of 0 mM (control), 1 mM, and 10 mM to either maturation or culture medium. Each experiment was conducted in four replicates each containing 100 oocytes for IVP. Cleavage and blastocyst rate were recorded at Days 2 and 7, respectively. Data were analyzed using the General Linear Model in SAS version 8.02 (SAS Institute, Inc., Cary, NC, USA) with the main factors being the level of L-NAME and the point of application. Pairwise comparisons were done using the Tukey test. Protein localization in bovine oocytes and embryos was performed by immunocytochemistry using eNOS- and iNOS-specific antibodies. Embryos were fixed in 3.7% paraformaldehyde, permeabilized in 0.1% Triton-X100, and washed three times in PBS supplemented with BSA. They were incubated with eNOS and iNOS primary antibody (1:200 dilutions) and washed before incubation with secondary antibody conjugated to FITC. After washing they were mounted on glass slides and examined under a confocal laser scanning microscope (Carl Zeiss Jena, Carl Zeiss AG, Oberkochen, Germany). In the controls the primary antibodies were omitted. As shown in the table below, the presence of L-NAME in the maturation medium significantly reduced the cleavage and blastocyst rate independent of the dosage applied. However the presence of L-NAME in the culture medium had an influence only on the blastocyst rate. The immunocytochemical staining results showed that both eNOS and iNOS are expressed in the cytoplasm of the MII oocytes, and during the pre-implantation stage the fluorescence signal was observed in nuclei and cytoplasm. However, the nuclear signal was much weaker. In conclusion, the present study is the first to determine the role of NO and to detect NOS protein in bovine oocytes and pre-implantation embryos. These results indicate that nitric oxide may play an important role as diffusible regulator of bovine oocyte maturation and preimplantation embryo development. Table 1. Effect of l-name addition in maturation or culture medium on embryo development

A Comparative Expression Analysis of Gene Transcripts in Post-fertilization Developmental Stages of Bovine Embryos Produced in Vitro or in Vivo

This study was carried out to examine the temporal variation in the relative abundance of transcripts during the post-fertilization stages of bovine embryos derived from in vitro or in vivo culture. For this purpose, cumulus-oocyte complexes obtained from ovaries from slaughterhouses were matured, fertilized and cultured in vitro. The in vitro culture was carried out using CR1 medium. In vivo embryos were derived from superovulated and artificially inseminated Simmental heifers and cows. Embryos were recovered from both systems approximately at day 1 (two-cell), day 2 (four-cell), day 3 (eight-cell), day 4 (16-cell), day 5 (morula) and day 7 (blastocyst) after insemination. Relative abundance of target transcripts was performed using real-time PCR. The transcripts studied were the nucleosome assembly protein, mRNA for alivin 1, Pleckstrin homology Sec7 coiled domain, polyadenylate binding protein, NADH dehydrogenase subunit 2, high-mobility group transcription factor, cytokine-like nuclear factor, NY-REN-58 antigen mRNA, mRNA for KIAA1764 and one novel transcript. These transcripts were derived from our previous study conducted using mRNA differential display reverse transcription-polymerase chain reaction (DDRT-PCR) between in vitro-produced bovine eight-, 16-cell, morula and blastocyst-stage embryos. The results of the present study have demonstrated the temporal variation in the relative abundance of these transcripts between in vitro and in vivo culture systems. Such variation in the relative abundance of transcripts during the post-fertilization developmental stages of in vitro and in vivo embryos may reflect the effect of the in vitro culture condition on the transcriptional activity thereby on the developmental competence of the resulting embryos.

Polymorphisms of the porcine androgen receptor gene affecting its amino acid sequence and expression level

Diverse physiological effects of the androgen receptor (AR), a nuclear transcription factor, and its mapping position within a quantitative trait loci (QTL) region on chromosome X propose it as an interesting candidate gene for pig reproduction and performance. Therefore, the aims of this study were isolation of the gene and detection of polymorphisms as a tool for association study and analysis of functional properties of the porcine AR. The mRNA and promoter sequences were obtained and screened for polymorphisms. Based on comparative sequencing, eight single nucleotide polymorphisms (SNPs), TG- and T-insertion/deletetion polymorphisms (INDELs) upstream transcription initiation sites, three SNPs in the 5'-untranslated region (UTR), one microsatellite (CCTTT)n in the intron of 5'-UTR, and a CAG-INDEL in exon 1 were detected. Two haplotypes originated from Duroc and Berlin Miniature Pig were segregating in the DUMI-F2 resource population. Characterization of the porcine AR promoter showed two conserved transcription start sites, a consensus sequence of GC-box and a homopurine/homopyrimidine stretch at similar locations compared to the human, rat and mouse as well as sequences similar to androgen response elements (ARE). The AR mRNA expression levels determined by real-time RT-PCR in various tissues of female pigs were high in ovary (100%) and adrenal gland (83.9% relative to ovary), moderate in uterus (61.6%) and liver (47.4%), and low in pituitary gland (1.3%) as well as in tonsil, muscle, mammary gland, leukocyte and jejunum (less than 1%). Detection of the AR mRNA transcripts in liver revealed that hemizygous males carrying the AR haplotype descended from Berlin Miniature pig had higher relative AR expressions than did those with the Duroc haplotype. Here we showed that the porcine AR is a highly polymorphic gene. Polymorphisms identified in the present study affect the predicted amino acid sequence as well as consensus transcription factor binding sites and are associated with the allele-specific differences of the AR mRNA transcript level in liver, reinforcing AR as a potential candidate gene for traits related to pig reproduction and performance.

BF, HP, DQB and DRB are associated with haemolytic complement activity, acute phase protein reaction and antibody response in the pig

In order to examine the loci factor B (BF), C3, corticotropin releasing hormone (CRH), DQB, DRB, haptoglobin (HP) and transforming growth factor beta 1 (TGFB1) for association with traits of humoral, specific and unspecific defence F2-animals of a porcine resource family were genotyped at single nucleotide polymorphisms within these loci. Haemolytic complement activity in the alternative and classical pathway, C3c and haptoglobin serum concentration and antibody titres were determined immediately prior and at days 4 and 10 after vaccinations against Mycoplasma hyopneumoniae (Mh), Aujeszky's disease virus, and porcine reproductive and respiratory syndrome virus at 6, 14 and 16 weeks of age, respectively. Analysis of variance revealed association of BF, HP and DRB with C3c serum concentration. The trend of haemolytic complement activity and C3c serum concentration during the experiment was affected by the interaction of DQB genotype and time of measurement. Association with antibody titres were found for BF, DQB and DRB. Results of the mixed model analyses were confirmed by quantitative transmission disequilibrium test that showed linkage and association with antibody titres, complement activity and acute phase reaction at certain times of measurement. The findings promote the importance of the candidate genes for humoral mechanisms of unspecific and specific defence that provide natural resistance against many pathogens.

Molecular cloning and sequencing of porcine C5 gene and its association with immunological traits

The complement system helps in the lysis of invading pathogens and modulates the inflammatory as well as the humoral and cellular immune responses. C5 mediates many potent inflammatory and cytolytic events after proteolytic activation by complement convertase enzymes. Hence, to investigate the role of pig C5 ( pC5) as a candidate gene for disease resistance in pigs, the complete cDNA of pC5 was sequenced, screened for single nucleotide polymorphisms (SNPs), and an association analysis with various immunological parameters measured in F2 animals of a pig resource population based on a cross of Duroc and Berlin miniature pigs (DUMI) was carried out. In total, 5,422 bp of pC5 cDNA was sequenced, which codes for the 1,677-amino-acid precursor of C5. Four polymorphic sites were detected, one of which was segregating in the DUMI population in three genotypic patterns: AA, AC and CC. Classical (CH50) and alternative (AH50) complement activities, C3c levels, haptoglobin (HP) acute phase protein levels, and antibody titers against Mycoplasma (Mk) and Aujesky (ADV) vaccines were measured in the resource population. Association analysis between C5 and the immunological parameters was carried out using repeated measures mixed and general linear model analysis. The homozygote AA was found to be significantly different from the other two genotypes with respect to AH50 and CH50, whereas genotype CC was found to be significantly different from the other genotypes for C3c and HP levels. No significant difference could be seen between genotypes for antibody titers against vaccinations. Association of C5 with complement activity traits and acute phase proteins promotes pC5 as a candidate gene for innate disease resistance.

Quantitative expression analysis of blastocyst-derived gene transcripts in preimplantation developmental stages of in vitro-produced bovine embryos using real-time polymerase chain reaction technology

The main objective of the present study was to analyse the quantitative expression pattern of genes from a subtracted blastocyst transcriptome throughout the preimplantation developmental stages of in vitro-produced bovine oocytes and embryos. For this purpose, Day 5 morula (M) cDNAs were subtracted from Day 7 blastocyst (B) cDNAs (B–M) and used to establish a B–M subtracted cDNA library, as reported previously. From the total generated clones, 19 were analysed quantitatively. The mRNA samples isolated from pools of immature oocytes (n = 150), mature oocytes (n = 150) and two-cell (n = 80), four-cell (n = 40), eight-cell (n = 20), morula (n = 6) and blastocyst (n = 3) embryos were reverse transcribed and subjected to real-time polymerase chain reaction (PCR) using sequence-specific primers and SYBR green as the DNA dye. A relative standard curve method was used to analyse the real-time data taking the morula stage as a calibrator. Applying suppression subtractive hybridisation (SSH), a total of 71 clones, which represent 33 different expressed sequence tags, were generated and available for analysis. Most transcripts were analysed for the first time in bovine embryogenesis. The real-time PCR has validated the results of SSH positively for 84% (16/19) of transcripts, whereas 16% (3/19) showed deviation in the expression pattern from the one seen during SSH. Several transcript-specific expression patterns were observed for genes that play decisive roles in bovine embryogenesis. In addition to identification, accurately quantifying the expression profiles of transcripts during development will pave the way towards understanding the molecular mechanisms of embryogenesis and their potential role in early embryo development. Most importantly, the present study has contributed to the enrichment of bovine embryo gene collection by generating new transcripts involved in bovine embryo development.

252A COMPARATIVE EXPRESSION ANALYSIS OF GENES IN PREIMPLANTATION DEVELOPMENTAL STAGES OF BOVINE EMBRYOS PRODUCED IN VITRO OR IN VIVO

A comparative analysis of mRNA expression patterns between embryos produced under different in vitro and in vivo culture systems allows the isolation of genes associated with embryo quality and investigation of the effect of culture environment on the embryonic gene expression. In this study, expression analysis of four known (PSCD2, TCF7L2, NADH-subunit and PAIP1) genes and one novel transcript, derived from differential display PCR, was performed in in vitro (Ponsuksili et al., 2002, Theriogenology 57, 1611–1624) or in vivo- (Moesslacher et al., 2001 Reprod. Dom. Anim. 32, 37) produced bovine 2-, 4-, 8-, 16-cell, morula and blastocyst stage embryos using real time PCR technology. Poly(A) RNA was isolated from four separate individual embryos from each developmental stage and embryo group (in vitro or in vivo) using Dynabeads mRNA kit (Dynal, Oslo, Norway). After reverse transcription, quantitative PCR was performed with sequence specific primers in an ABI PRISM® 7000 Sequence Detection System instrument (Applied Biosystems, Foster City, CA, USA) using SYBR® Green as a double-strand DNA-specific fluorescent dye. Standard curves were generated for target and endogenous genes using serial dilutions of plasmid DNA. Final quantification was done using the relative standard curve method, and results were reported as relative expression or n-fold difference to the calibrator cDNA (i.e., the blastocyst stage) after normalization with the endogenous control (Histone2a). Data were analyzed using SAS version 8.0 (SAS Institute Inc., NC, USA) software package. Analysis of variance was performed with the main effects being the developmental stage and embryo source (in vitro or in vivo) and their interactions followed by multiple pairwise comparisons using Tukey’s test. No significant difference was observed in the relative abundance of the PSCD2 gene between the two embryo groups. However, its expression was higher (20-fold) (P&lt;0.05) at the 8-cell stage than the other developmental stages among in vitro embryos. Higher expression (P&lt;0.05) of NADH-subunit mRNA was detected in vivo than in vitro at the 2-cell stage of development. The TCF7L2 mRNA was expressed in the in vitro embryos but not in the in vivo ones. PAIP1 mRNA was higher (P&lt;0.05) in in vitro (1500-fold) than in the in vivo embryos (500-fold) at the 2-cell developmental stage compared to the calibrator. The novel transcript was also detected at higher level (P&lt;0.05) in the in vitro than in the in vivo embryos at the 2-cell stage of development. However, the PAIP1 and the novel transcript showed no significant difference in their expression between the two embryo groups beyond the 2-cell developmental stage. Both PAIP1 and the novel transcript were detected only up to 8-cell stage in both embryo groups, suggesting their maternal origin. In conclusion, the variations in the expression of studied genes between in vitro and in vivo may reflect the effect of the two culture systems on the transcriptional activity of early embryos.

244REAL TIME PCR EVALUATION OF EXPRESSION PROFILES OF SOME MATERNAL-SOURCED GENE TRANSCRIPTS IN IN VITRO PRODUCED PRE IMPLANTATION STAGE BOVINE EMBRYOS

Gene expression profiling data collected in a time series and quality related parameters are important for understanding the developmental mechanisms carried out in a developing embryo, and are also a source to enrich the knowledge base of embryo development. However, such data are frequently constrained by limitation and handling of the sample as well as cost associated with generating such data. Cumulatively, these factors have contributed to the existing insufficient data compared to the large need stemming from a drive to control and guide optimum embryo development. In this ongoing study, with objectives to quantify and evaluate gene transcripts identified from certain developmental stages, expression profiles of two ESTs (C256 and C112), derived from an oocyte cDNA library, were analyzed from the above perspectives to understand the change in the level of these gene transcripts throughout the pre-implantation stage of embryo development. For this analysis, pools of oocytes and embryos were prepared by balancing the amount proportional to the number of cells present. mRNA was isolated separately from each pool of matured oocytes, 2-cell, 4-cell, 8-cell, and 16-cell stages, as well as morula and blastocyst stages by using Dynal beads Oligo (dt)25 (Dynabeads, Dynal Biotech, Oslo, Norway) following the manufacturer’s recommendations. These mRNAs were checked for DNA contamination and, when proved free, first-strand cDNA was synthesised by reverse transcribtion at 42°C for 2h following standard laboratory procedures. Transcript quantification was performed by real-time PCR using gene-specific primers, equal amounts of cDNA from each sample and SYBR Green universal master mix. Following this analysis, both transcripts were found to be expressed in a wave-like manner being highly expressed in mature oocytes, declining gradually as the development stage advanced, with the lowest level at the 16-cell stage, and then reviving in level thereafter until it reached blastocyst stage. Taking the 16-cell stage as calibrator for both, C256 was 26.4, 23.2, 8.5, 1.7. 2.4 and 2.7 times more expressed in oocyte, 2-cell, 4-cell, 8-cell, morula and blastocyst stages, respectively. Similarly, C112 was 110.7, 169.2, 9.8, 2.5, 4.1 and 7.3 times more expressed in oocyte, 2-cell, 8-cell, morula and blastocyst stages, respectively. These expression patterns suggest the probable origin of these transcripts initially to be maternal. C256 is strongly similar to human retinoid X receptor beta (RXRb) gene (NM_021976.3), which is involved in transcriptional functions and in increasing DNA binding, whereas C112 is strongly similar to TATA box-binding protein-associated factor gene (AY189986.1), which is also involved in transcriptional functions. As seen from their functions, these transcripts can be vital for developing the embryo and the variations at different developmental stages shows their most probable role as part of genes contributing to developmental competence in pre-implantation development stages.

165RE-EXPANSION AND QUALITY OF SPLIT BOVINE EMBRYOS IN VITRO

Transferring split bovine embryos results in a higher number of calves born per embryo. In addition to generating genetically identical progeny, biopsies can be made for molecular biological analyses. We aimed to determine the effect of splitting ratio on the in vitro development of Day 7 (164 to 168h post insemination) IVP bovine embryos. The inner cell mass (ICM) and trophoblast cells were split in three ratios (50:50, 60:40 and 70:30) with a Beaver microblade (Becton Dickinson, N.J., USA.) fixed to a micromanipulator under an inverse microscope at 100 X (Leica, Bensheim, Germany). Split blastocysts were cultured singly in 50μL drops of CR1aa medium at 39°C under 5% CO2 in a moisture-saturated atmosphere. After 1 and 2h culture, the morphology was assessed by judging the shape of the embryos and re-development of the blastocoel. On Day 8 (after 22h culture), the shape of the blastocysts, development of the ICM, blastocoel, proportion of degenerated cells and embryos and re-expanded blastocysts were recorded. Embryos were stained with propidium iodide and Hoechst 33258 for cell counting. The re-expansion status of Group A (50, 60 and 70%) and B (50, 40 and 30%) embryos after 1 and 2h and their quality after 22h culture (1: excellent=&lt;10% degenerated cells, well-defined ICM; 2: fair=&lt;20% degenerated cells) are shown in Table 1. With regards to Group A split blastocysts, a higher (P&lt;0.05) percentage of embryos that re-expanded after 1 and 2h and which yielded Quality 1 and 2 embryos suitable for embryo transfer was observed with the 60% and 70% than with demi-embryos. There were significant differences (P&lt;0.05) between all split blastocysts in Group B after 1h culture. The 30% split embryos showed the lowest re-expansion rate and quality of embryos after 2h and 22h culture, respectively. No differences (P&lt;0.05) were seen in the ratio of the ICM to the total number of cells in both Group A and B. This study showed that the ratio in which blastocysts were split had a significant effect on re-expansion and quality but not on the number of cells. Table 1

Mapping of ESTs derived from pre-implantation stage cattle embryos to allocate 16 new additions to the ordered comparative map of cattle and human

Twenty expressed sequence tags (ESTs) derived from cDNA libraries of different developmental stages of embryos were mapped using a whole genome bovine hamster radiation hybrid panel. These include 14 markers representing genes, most of which have not so far been mapped in cattle, with another three being novel in both cattle and human. The markers were placed on specific chromosomes with high LOD scores and except two all localizations fit the current human and cattle comparative map. The assignment of these genes further enriches the cattle genome map and also contributes to the international effort of generating comparative maps.

Effects of different laser-drilled openings in the zona pellucida on hatching of in vitro-produced cattle blastocysts

OBJECTIVE

To examine whether the size of artificial openings in the zona pellucida effects the hatching process in in vitro-produced cattle embryos.

DESIGN

We evaluated the course of hatching of cattle blastocysts with and without laser-drilled zona pellucida openings of different sizes.

SETTING

University-based cattle reproductive biotechnology laboratory.

INTERVENTION(S)

Cattle blastocysts were produced in vitro. Laser treatment was performed 7 days after fertilization. In group I, a small opening of 7-15 microm in width and 40 microm in length was created. In group II, an opening of at least 40 by 40 microm was created. Group III blastocysts received no laser treatment.

MAIN OUTCOME MEASURE(S)

Hatching course, zona pellucida thickness, diameter.

RESULT(S)

By day 9, the rate of hatched blastocysts was 27.1%, 63,0%, and 42,9% in groups I, II, and III, respectively. The remainder in group I were entrapped during hatching in a typical figure eight shape. The hatching rate in group II was significantly different from the other groups. All laser-treated blastocysts (groups I and II) showed no change of zona pellucida diameter until day 9.

CONCLUSION(S)

These results suggest that the size of the artificial openings in the zona pellucida has an influence on the hatching process.

Identification and quantification of differentially expressed transcripts in in vitro-produced bovine preimplantation stage embryos

In this study, we used mRNA differential display reverse transcription polymerase chain reaction (DDRT-PCR) to analyze the mRNA expression patterns in in vitro-produced bovine 8-cell, 16-cell, morula, and blastocyst stage embryos and isolate differentially expressed amplicons. Moreover, we have used a fluorescence monitored real time quantitative PCR to quantify and analyze the expression patterns of the target differentially expressed transcripts through out the preimplantation stages from oocytes to blastocyst. For this, total RNA isolated from bovine 8-cell (n = 188), 16-cell (n = 94), morula (n = 35), and blastocyst (n = 15) were reverse transcribed and subjected to DDRT-PCR. Target differentially expressed transcripts were quantified by real time quantitative PCR. The cDNA banding pattern analysis revealed that large number of cDNA bands were conserved at 8-cell and blastocyst stage with a slight decrease at the morula stage. A total of 16 amplicons were cloned and sequenced. All expressed sequence tags (ESTs), except 1C19, showed sequence similarity with known genes or ESTs in GenBank. Sixty-two percent (10/16) of cDNA bands representing differentially expressed genes originated from 8-cell stage and the rest derived from the 16-cell, morula, or blastocyst stage. The quantitative PCR analysis has validated the expression patterns of 75% (12/16) of our transcripts to be in agreement with the results of DDRT-PCR. However, the quantitative PCR results of four transcripts showed a deviation from the pattern seen in DDRT-PCR. In conclusion, we have successfully applied mRNA DDRT-PCR to identify and isolate stage-specific expressed genes in bovine preimplantation embryos. In addition to validating the results of DDRT-PCR, quantitative real time PCR provides quantitative data on the expression of target genes.

Association of the porcine C3 gene with haemolytic complement activity in the pig

The complement component C3 plays an essential role in the activated complement system, which is involved in phagocytosis, inflammation and immunoregulation to destroy infectious microorganisms. The C3 molecule has more implications in the general defence mechanisms. In this study, the porcine C3 cDNA sequences including 5'- and 3'- flanking regions were determined and the polymorphisms in this gene were identified to carry out an association analysis between C3 and complement activity traits. Porcine C3 gene has high homology with human C3. Five single nucleotide polymorphisms (SNPs) and one microsatellite were detected in the porcine C3 gene. Haemolytic complement activity of alternative and classical pathways (ACH, CCP) was measured in 416 F2 animals of a crossbred of Duroc x Berlin Miniature Pig, which were immunized with Mycoplasma, Aujeszky and PRRS vaccines. C3 markers were found to be significantly associated (P <0.05) with both ACP and CCP. Animals with the more frequent haplotype present in Duroc and other commercial breeds exhibit higher ACP and CCP levels than the animals with haplotype specific to some Berlin Miniature Pigs. The association of C3 with complement activity reinforces the importance of C3 as a candidate gene for natural resistance to microorganisms.

Comparison of different methods to assess the composition of pig bellies in progeny testing

The objective of the study was to validate methods that assess the belly composition of stationary tested progenies of Piétrain boars. In German performance test stations, there are currently three methods of determining belly compositon in use: 1) a regression equation that contains different carcass characteristics, such as fat thickness and muscle area; 2) planimetric analysis of video or digital images acquired at the cut between the 13th and 14th ribs; and 3) estimation of the belly composition using ultrasound data from a three-dimensional ultrasound image produced an online carcass-grading system. Validation of these techniques was performed on 400 carcasses of stationary-tested Piétrain and Piétrain-sired crossbred pigs, which were slaughtered at a mean carcass weight of 85 and 97 kg. Magnetic resonance imaging (MRI) served as a reference to determine the lean content of the bellies. The correlation to MRI lean content ranged from 0.71 to 0.81, and corresponding correlation values were 0.62 to 0.64 for the digital imaging technique, and 0.53 to 0.59 for the AutoFOM online carcass-grading system. An increase in precision was achieved when information from digital imaging and linear carcass measures were included in the regression equation. Accuracy of the AutoFOM system does not seem to be sufficient to assess the belly composition for the special breeds in performance testing. However, extracting and combining 127 AutoFOM-base recordings into modified equations using partial least squares techniques yielded an improvement in the prediction accuracy for all tested breed and/or weight groups.

Nucleolar proteins and ultrastructure in bovine in vivo developed, in vitro produced, and parthenogenetic cleavage-stage embryos

In the present study, ribosomal RNA (rRNA) gene activation, monitored through nucleolus development, was studied by autoradiography following (3)H-uridine incubation, transmission electron microscopy, and immunofluorescence confocal laser scanning microscopy of key nucleolar proteins involved in rRNA transcription (topoisomerase I, upstream binding factor, and RNA polymerase I) and processing (fibrillarin, nucleolin, and nucleophosmin) in in vivo developed, in vitro produced, and parthenogenetic bovine embryos. In general, in vivo developed embryos displayed formation of fibrillo-granular nucleoli during the 4th post-fertilization cell cycle. During the previous stages of development, nucleolus precursor bodies (NPBs) were observed. However, on some occasions the initial steps of nucleolus formation were observed already at the 2- and 4-cell stage in cases where such embryos were collected from superovulated animals together with later embryonic stages presenting nucleolar development and autoradiographic labeling. The in vitro produced embryos displayed very synchronous formation of fibrillo-granular nucleoli and autoradiographic labeling during the 4th cell cycle. In vivo developed and in vitro produced embryos displayed allocation of nucleolar proteins to fibrillar and granular compartments of the developing nucleoli during the 4th cell cycle. The parthenogenetic embryos typically displayed formation of fibrillo- granular nucleoli during the 5th cell cycle and autoradiographic labeling was not observed until the morula stage. Moreover, the 1-, 2-, and 4-cell parthenogenetic embryos practically lacked NPBs. On the other hand, parthenogenetic embryos displayed allocation of nucleoar proteins to nuclear entities during the 4th cell cycle. In conclusion, both in vivo developed and in vitro produced bovine embryos displayed activation of transcription and nucleolar development during the 4th cell cycle. However, in vivo developed embryos flushed together with later developmental stages displayed premature activation of these processes. Parthenogenetic bovine embryos, on the other hand, displayed a delayed activation.

[Some factors affecting in vitro development of porcine embryo reconstitution from somatic cells nuclear transfer]

In this paper, a study on reconstitution of porcine oocytes by using nuclear transfer with cumulus cells(CC) and fibroblast cells(FC) was carried out. Reconstituted oocytes which were the fusion with CC and showed a cleavage rate of 56.7%, developed to morula(11.7%) and blastocysts(6.7%) phases which were higher than those derived from the fusion with FC(p < 0.05). The results of this study also involved the effects of oocyte collection method and maturational age of recipient oocytes during the in vitro development of nuclear-transfer embryos which were reconstructed with cultured cumulus cells. The cumulus cells synchronized in G0/G1 phases through serum-starvation culture, were transferred into enucleated oocytes which were collected by aspiration or dissection method and cultured for 33 or 44 h. Reconstituted embryos were activated with a combination of calcium ionophore A23187 or electric pulsation and 6-DMAP, and cultured for 6 days. As for the oocytes collection methods, activation treatment in the presence of cytochalasin B did not affect the developmental rate of embryos reconstituted with 44-h-mature recipients. However, the development rate of reconstituted embryos with 33-h-mature recipients was significantly higher(p < 0.05) by activation with the combination of electric pulsation and 6-DMAP. These results suggest that reconstituted porcine embryos derived from cultured cumulus cells can develop to the blastocyst stage and that the development of the former could be improved by reconstruction with young oocyte cytoplast after the activation with the combination of electric pulsation and 6-DMAP.

Molecular characterization of the pig C3 gene and its association with complement activity

The complement system catalyzes direct lysis of micro-organisms and modulates phagocytosis, inflammation, humoral and cellular immune responses. Since the complement protein C3 is the central component within all pathways of complement activation, C3 is a candidate gene for complement activity and also for improved protection against many pathogens. The pig C3 gene was sequenced, screened for polymorphisms, and analyzed for association with hemolytic complement activity of the alternative and classical pathway (AH(50), CH(50)). C3c serum levels and haptoglobin (HP) serum concentrations were measured before and after vaccination against Mycoplasma hyopneumoniae, Aujeszky virus, and porcine reproductive and respiratory syndrome virus in F2 animals of a pig resource population based on crossbreeding of Duroc and Berlin Miniature Pig. The genomic C3 sequence covers 444 bp of promoter region, 41 exons and 40 introns, as well as 881 bp of the 3'-flanking region. The cDNA codes for a 1,661-amino acid precursor C3. Five polymorphic sites were detected in the 5'-UTR, intron 13, exon 15, exon 30, and the 3'-UTR. Within the resource population two haplotypes were found to segregate. Analysis of variance applying a repeated measures model revealed a significant effect of the interaction of C3 genotype and time of measurement relative to immunization on CH(50), AH(50,)and C3c that is likely to be due to variation of C3 expression. In contrast, the time course of the HP acute-phase reaction is not associated with C3 genomic variation. The association of C3 with complement activity indicates the importance of C3 as a candidate gene for natural resistance to micro-organisms, although the causative polymorphism modulating the expression of C3 remains to be delineated.

Stage-specific expressed sequence tags obtained during preimplantation bovine development by differential display RT-PCR and suppression subtractive hybridization

Differential display RT-PCR (DDRT-PCR) and suppression subtractive hybridization (SSH) were applied in order to detect preimplantation stage-specific expressed sequence tags (ESTs) of bovine embryos. Seventeen ESTs were detected from the differential display RT-PCR approach. All clones but two showed homology to genes or ESTs known in human, cattle or other species. One of the clones similar to H. sapiens mRNA for KIAA1764 protein was used exemplarily to quantify the transcripts by real-time PCR. The result of quantitative differential screening was found to be in agreement with DDRT-PCR banding patterns. In the second approach, a blastocyst-stage enriched cDNA library was constructed using SSH of blastocyst versus morula transcripts. The 71 clones that were analysed represent 33 distinct loci including candidate genes for the regulative processes during differentiation of inner cell mass (ICM) and trophoblast cells and the initial phase of embryo implantation, such as galectin-3 and fibronectin. As revealed by real-time PCR, the mRNA level of galectin-3 was three times higher in the blastocyst stage than in the morula stage. DDRT-PCR and SSH are both powerful tools for the identification of stage-specific expressed gene in preimplantation bovine embryos. Real-time PCR allows to test and confirm the outcome and to add quantitative data of selected transcripts of interest.

Chromosomal assignments for porcine genes encoding enzymes in hepatic metabolic pathways

Increasing the number of mapped genes will facilitate (1) the identification of potential candidate genes for a trait of interest within quantitative trait loci regions and (2) comparative mapping. The metabolic activities of the liver are essential for providing fuel to peripheral organs, for regulation of amino acid, carbohydrate and lipid metabolism and for homoeostasis of vitamins, minerals and electrolytes. We aimed to identify and map genes coding for enzymes active in the liver by somatic cell genetics in order to contribute to the improvement of the porcine gene map. We mapped 28 genes of hepatic metabolic pathways including six genes whose locations could be confirmed and 22 new assignments. Localization information in human was available for all but one gene. In total 24 genes were assigned to in the expected chromosomal regions on the basis of the currently available information on the comparative human and pig map while for four genes our results suggest a new correspondence or extended regions of conservation between porcine and human chromosomes.

Somatic gene transfer into the lactating ovine mammary gland

BACKGROUND

Somatic gene therapy requires safe and efficient techniques for the gene transfer procedure. The ovine mammary gland is described as a model system for the evaluation of somatic gene transfer methods.

METHODS

Different gene delivery formulations were retrogradely injected into the mammary gland of lactating sheep. The efficiency of the gene transfer was subsequently measured by the detection of the secreted transgene products in the milk. To counteract the milk flow in the lactating gland caused by the permanent milk production, a newly developed pretreatment of the mammary gland with hyperosmotic solutions was applied. In addition, in vivo electroporation of DNA into the mammary gland is described.

RESULTS

Gene transfer using naked DNA or simple complexes of DNA with polycations did not result in traceable amounts of reporter gene products. However, utilizing the complex cationic lipid DOSPER, a peak expression of about 400 ng/ml was observed 6 days after transfection. Maximum expression rates of more than 1 microg/ml were obtained by combining hyperosmotic pretreatment and receptor-mediated gene transfer. For the in vivo electroporation, the proof of principle for this technique in the mammary gland is reported.

CONCLUSIONS

The ovine mammary gland turned out to be a very well suited as a model system for evaluation and optimization of various gene transfer protocols.

Detection of quantitative trait loci for carcass traits in the pig by using AFLP

For evaluation of the suitability of Amplified Fragment Length Polymorphism (AFLP) for detection of quantitative trait loci in farm animals, a combination of AFLP and selective genotyping has been applied as a rapid screening method for marker-QTL associations. Focusing on loci affecting eye muscle area, six extreme discordant sib pairs were selected from a Duroc x Berlin Miniature Pig F2 experimental cross and examined by using 48 AFLP primer combinations. Two prominent AFLP markers were converted into simple codominant PCR markers ( STS-Bo1 and STS-Bo3) and assigned to Sscr4 by physical and linkage mapping. Single marker analysis indicated association of the STS markers with a putative QTL influencing eye muscle area. Interval mapping confirmed the presence of a significant QTL for eye muscle area (Pgenomewide < 0.01) on the Sscr4, with STS-Bo1 being the closer marker. At the same location, significant effects (Pgenomewide < 0.01) on carcass length and backfat thickness were also detected. Our results demonstrate the capability of the combination of AFLP analysis and selective genotyping as a method for detection of genome regions containing QTL in livestock.

A source for expression profiling in single preimplantation bovine embryos

Our knowledge of the genes active during normal preimplantation development in cattle is limited, despite the importance for further improvement of fertility and applicability of biotechniques, like in vitro production and embryo transfer. We report on the construction of cDNA libraries as a source for expression profiling in oocytes and single preimplantation cattle embryos. cDNAs were prepared from two unfertilized oocytes, single two-cell, four-cell and eight-cell, morula, and blastocyst stage embryos, respectively. The oocytes, eight-cell, morula, and blastocyst stage embryo-derived cDNAs were ligated to a lambda-based expression vector and these have complexities of 8 x 10(5), 5 x 10(5), 1 x 10(6) and 2 x 10(6) independent clones, respectively. A total of 48 clones were picked and sequenced, 62.5% (30/48) of the sequence were homologous to known transcripts from human and mouse, 18.75% (9/48) to expressed sequence tags (ESTs) of human and mouse origin. Novel sequences were detected at a frequency of 14.58% (7/48). PCR analyses of the embryonic libraries for specific genes revealed transcripts for genes including housekeeping genes (GAPDH and beta-actin), developmental genes (OCT-4, IGF-I receptor and homeodomain sequences) and genes coding for metabolic and protective enzymes (manganese superoxide dismutase, glutamine synthetase, flavin-containing mono-oxygenase, glutamate dehydrogenase, alpha-2-macroglobulin). These cDNA libraries are a valuable resource for the isolation of clones representing genes active at these early developmental stages. The ability to construct cDNA expression libraries from only a few cells will allow gene expression analyses from embryo biopsies and embryos derived by nuclear transfer procedures.

Application of differential display RT-PCR to identify porcine liver ESTs

Differential display banding patterns of liver and nine other tissues were produced in order to isolate porcine expressed sequence tags (ESTs), representing genes active in liver while avoiding redundant analysis of housekeeping genes. We cloned and sequenced those cDNA fragments that were unique to the liver banding pattern or that appeared in liver and a maximum of four other tissues. We analyzed 240 sequences that represent 200 distinct ESTs/genes and that make up the first list of liver ESTs in the pig. Ninety-one clones correspond to known genes and 109 clones showed no significant match with any gene or DNA sequence in GenBank and EMBL databases. Fifty-eight clones represent 18 distinct genes, the most abundant representing the albumin gene (13/240). The majority of genes that were represented by more than one clone code for proteins released by the liver into the plasma. We demonstrated the suitability of the differential display reverse transcription polymerase chain reaction approach for the detection of porcine liver ESTs. It is shown that this approach is appropriate to reduce redundant analysis of clones containing the same sequence.

Expression of homeobox-containing genes in cDNA libraries derived from cattle oocytes and preimplantation stage embryo

The homeobox-containing gene family plays a pivotal role in regulating, patterning, and axial morphogenesis in the developing embryo. But there is still very little known about the expression and function of these genes in mammalian oocytes and preimplantation stage embryos. In this study we have used degenerate primers corresponding to the highly conserved regions of Antennapedia class homeodomains as a rapid and an efficient method to survey bovine cDNA libraries derived from unfertilised oocytes, single 2-cell, 4-cell, 8-cell, morula, and blastocyst stage embryos for the presence of homeobox sequences. Our results provide, for the first time, evidence for the transcription of Hoxa3 and Hoxd1 in oocytes; Cdx1 and Cdx2 in the 2-cell; Cdx1, Hoxa1, Hoxd1, and Hoxd4 in the 4-cell; Cdx1, Hoxa1, and Hoxc9 in the 8-cell; Cdx2, Hoxb9, and Hoxc9 in the morula; Cdx2, Hoxb7, Hoxb9, and Hoxc9 in blastocyst stage cattle embryos. These are candidate genes for the developmental capacity of in vivo and in vitro produced bovine embryos.

Genetische Fundierung von AutoFOM-Merkmalen

Abstract. Title of the paper: Genetic foundation of AutoFOM-traits Since the beginning of the year 2000 the payment System of pig carcasses in some slaughter houses in northwest Germany is based on the recordings of the fully automated carcass Classification system AutoFOM. Besides legal information 'estimated lean meat percentage' relative exact details of the weights of important valuable cuts are available. Genetic parameters of the AutoFOM lean carcass cut information, ham-, chop-, Shoulder- and belly weights as well as lean meat percentage of the belly cut were estimated. Using the field data of the pig breeding organisations BHZP (n = 2224) and SNW (n = 3601) the estimated heritabilties of these carcass cuts vary between 0.13 and 0.27 (BHZP) and 0.13 and 0.31 (SNW), respectively. The estimated heritabilities of the AutoFOM carcass traits of station-tested pigs were more pronounced for the dam lines German Landrace and Large White (n = 1693) and Piétrain Al-boars mated to Fl sows (n = 1053). The estimates ranged from 0.27 to 0.59 (dam lines) and 0.05 to 0.40 (Pi Al-boars), respectively. Using the records of Station tested purebred Pietrain pigs (n = 1693) the heritabilities of the AutoFOM carcass cuts did not exceed 0.10. The genetic correlation between the different AutoFOM carcass traits exceed the absolute value of 0.8. In a similar way, the genetic correlation between the "estimated lean meat percentage" used in the test Station and the AutoFOM carcass traits were close to unity. We concluded that AutoFOM traits of slaughter pigs provide a useful information for the selection of Al-boars. Moreover, with regard to the Station testing of dam lines AutoFOM carcass informations derived from AutoFOM are a useful supplementation. Because of the low heritability, only a marginal additional benefit could be expected for the genetic ranking of Pi-boars using AutoFOM carcass cut records of purebred Station tested progenies.

Ribosomal RNA gene expression and chromosome aberrations in bovine oocytes and preimplantation embryos

This review focuses on the key features of development of the bovine oocyte and embryo, with comparisons of the developmental characteristics of embryos produced in vivo and in vitro. The oocyte is transcriptionally quiescent in the primordial and primary follicle. In the secondary follicle transcription is initiated in the oocyte and a ribosome-synthesizing nucleolus is established in this cell. Transcription and nucleolar activity are enhanced in the tertiary follicle during oocyte growth. When the oocyte reaches approximately 110 microm in diameter, corresponding to a follicle of about 3 mm in diameter, transcription ceases and the nucleolus is inactivated, forming a dense spherical remnant. During the final phase of follicular dominance this remnant becomes vacuolated and, in conjunction with resumption of meiosis, it disperses. The rRNA genes are apparently re-activated during the four-cell stage, that is, the third cell cycle after fertilization, but a nucleolus is not formed. During the subsequent cell cycle, that is, during the eight-cell stage, ribosome-synthesizing nucleoli are again established. Bovine embryos produced in vitro apparently display the same pattern of nucleolus development as that in embryos developed in vivo. Examination of the ploidy of embryonic cells using fluorescence in situ hybridization has revealed that the production of bovine embryos in vitro is associated with increased chromosome aberrations in the embryos. Blastocysts produced in vitro display a significantly higher rate of mixoploidy, that is, when the embryo consists of both normal diploid and abnormal polyploid cells, than that in embryos developed in vivo. The rate of mixoploidy among embryos produced in vitro increases with increasing developmental stage. Moreover, after fertilization in vitro, initially there is a high rate of 'true' polyploidy, that is, when all cells of the embryos are polyploid. However, the polyploid embryos are eliminated before they cleave beyond the eight-cell stage, the stage at which major activation of the embryonic genome occurs in cattle.

Ribosomal RNA gene expression and chromosome aberrations in bovine oocytes and preimplantation embryos

This review focuses on the key features of development of the bovine oocyte and embryo, with comparisons of the developmental characteristics of embryos produced in vivo and in vitro. The oocyte is transcriptionally quiescent in the primordial and primary follicle. In the secondary follicle transcription is initiated in the oocyte and a ribosome-synthesizing nucleolus is established in this cell. Transcription and nucleolar activity are enhanced in the tertiary follicle during oocyte growth. When the oocyte reaches approximately 110 microm in diameter, corresponding to a follicle of about 3 mm in diameter, transcription ceases and the nucleolus is inactivated, forming a dense spherical remnant. During the final phase of follicular dominance this remnant becomes vacuolated and, in conjunction with resumption of meiosis, it disperses. The rRNA genes are apparently re-activated during the four-cell stage, that is, the third cell cycle after fertilization, but a nucleolus is not formed. During the subsequent cell cycle, that is, during the eight-cell stage, ribosome-synthesizing nucleoli are again established. Bovine embryos produced in vitro apparently display the same pattern of nucleolus development as that in embryos developed in vivo. Examination of the ploidy of embryonic cells using fluorescence in situ hybridization has revealed that the production of bovine embryos in vitro is associated with increased chromosome aberrations in the embryos. Blastocysts produced in vitro display a significantly higher rate of mixoploidy, that is, when the embryo consists of both normal diploid and abnormal polyploid cells, than that in embryos developed in vivo. The rate of mixoploidy among embryos produced in vitro increases with increasing developmental stage. Moreover, after fertilization in vitro, initially there is a high rate of 'true' polyploidy, that is, when all cells of the embryos are polyploid. However, the polyploid embryos are eliminated before they cleave beyond the eight-cell stage, the stage at which major activation of the embryonic genome occurs in cattle.

Transgenic activation of Ras in neurons promotes hypertrophy and protects from lesion-induced degeneration

Ras is a universal eukaryotic intracellular protein integrating extracellular signals from multiple receptor types. To investigate its role in the adult central nervous system, constitutively activated V12-Ha-Ras was expressed selectively in neurons of transgenic mice via a synapsin promoter. Ras-transgene protein expression increased postnatally, reaching a four- to fivefold elevation at day 40 and persisting at this level, thereafter. Neuronal Ras was constitutively active and a corresponding activating phosphorylation of mitogen-activated kinase was observed, but there were no changes in the activity of phosphoinositide 3-kinase, the phosphorylation of its target kinase Akt/PKB, or expression of the anti-apoptotic proteins Bcl-2 or Bcl-X(L). Neuronal Ras activation did not alter the total number of neurons, but induced cell soma hypertrophy, which resulted in a 14.5% increase of total brain volume. Choline acetyltransferase and tyrosine hydroxylase activities were increased, as well as neuropeptide Y expression. Degeneration of motorneurons was completely prevented after facial nerve lesion in Ras-transgenic mice. Furthermore, neurotoxin-induced degeneration of dopaminergic substantia nigra neurons and their striatal projections was greatly attenuated. Thus, the Ras signaling pathway mimics neurotrophic effects and triggers neuroprotective mechanisms in adult mice. Neuronal Ras activation might become a tool to stabilize donor neurons for neural transplantation and to protect neuronal populations in neurodegenerative diseases.