SNP analysis, genotyping and mapping of the porcine <i>GPCR142</i> gene (Brief report)

Abstract. The RLN3 gene has been recently reported as a ligand for two related orphan G protein-coupled receptors, GPCR135 and GPCR142 (BATHGATE et al., 2002; LIU et al., 2003a; LIU et al., 2003b; CHEN et al., 2005). Pharmacological studies of the GPCR142 gene indicated that the RLN3 gene is the only member of the RLN family showing the ability to activate this gene (BATHGATE et al., 2002). The GPCR142 gene contains a single exon and is located on chromosome 1 (1q22) in human (FREDRIKSSON et al., 2003). It is expressed abundantly in the hypothalamus with discrete expression in the paraventricular nucleus of the hypothalamus and supraoptic nucleus; as well as in the cortex, septal nucleus and preoptical area (LIU et al., 2003b). The functional roles of the RLN3 gene and its receptors within the mammalian physiology are still unclear. The objectives of this study were to characterize the GPCR142 gene in pigs, to determine the chromosomal location and to analysis the expression profile in pigs.

Molecular and subcellular characterisation of oocytes screened for their developmental competence based on glucose-6-phosphate dehydrogenase activity

Oocyte selection based on glucose-6-phosphate dehydrogenase (G6PDH) activity has been successfully used to differentiate between competent and incompetent bovine oocytes. However, the intrinsic molecular and subcellular characteristics of these oocytes have not yet been investigated. Here, we aim to identify molecular and functional markers associated with oocyte developmental potential when selected based on G6PDH activity. Immature compact cumulus-oocyte complexes were stained with brilliant cresyl blue (BCB) for 90 min. Based on their colouration, oocytes were divided into BCB(-) (colourless cytoplasm, high G6PDH activity) and BCB(+) (coloured cytoplasm, low G6PDH activity). The chromatin configuration of the nucleus and the mitochondrial activity of oocytes were determined by fluorescence labelling and photometric measurement. The abundance and phosphorylation pattern of protein kinases Akt and MAP were estimated by Western blot analysis. A bovine cDNA microarray was used to analyse the gene expression profiles of BCB(+) and BCB(-) oocytes. Consequently, marked differences were found in blastocyst rate at day 8 between BCB(+) (33.1+/-3.1%) and BCB(-) (12.1+/-1.5%) oocytes. Moreover, BCB(+) oocytes were found to show higher phosphorylation levels of Akt and MAP kinases and are enriched with genes regulating transcription (SMARCA5), cell cycle (nuclear autoantigenic sperm protein, NASP) and protein biosynthesis (RPS274A and mRNA for elongation factor 1alpha, EF1A). BCB(-) oocytes, which revealed higher mitochondrial activity and still nucleoli in their germinal vesicles, were enriched with genes involved in ATP synthesis (ATP5A1), mitochondrial electron transport (FL405), calcium ion binding (S100A10) and growth factor activity (bone morphogenetic protein 15, BMP15). This study has evidenced molecular and subcellular organisational differences of oocytes with different G6PDH activity.

Biological interpretations of transcriptomic profiles in mammalian oocytes and embryos

The characterization of gene-expression profiles in oocytes and embryos is critical to understand the influence of genetic and environmental factors on preimplantation and fetal development. Numerous gene-expression microarray studies using different platforms and species are offering insights into the biological processes extensively represented among the genes exhibiting differential expression. Major advances on understanding the direct relationship between gene expression and developmental competence are being reported. Integration of information across studies using meta-analysis techniques can increase the precision and accuracy to identify expression profiles associated with embryo development. Gene network and pathway analyses are offering insights into gene interactions and expression profiles of embryos. All these advances are cementing the way toward a comparative and systems approach to understanding the complex processes underlying vertebrate development.

Combined line-cross and half-sib QTL analysis in Duroc-Pietrain population

A Duroc-Pietrain resource population was built to detect quantitative trait loci (QTL) that affect growth, carcass composition, and pork quality. The data were analyzed by applying three least-squares Mendelian models: a line-cross (LC) model, a half-sib (HS) model, and a combined LC and HS model (CB), which enabled the detection of QTL that had fixed, equal, and different allele frequencies for alternate breed alleles, respectively. Permutation tests were performed to determine 5% chromosome-wide and 5% genome-wide threshold values. A total of 40 (137) QTL were detected at the 5% genome-wide (chromosome-wide) level for the 35 traits analyzed. Of the 137 QTL detected, 62 were classified as the LC type (LC-QTL), 47 as the HS type (HS-QTL), and 28 as the CB type (CB-QTL). The results indicate that implementation of a series of model-based framework is not only beneficial to detect QTL, but also provides us with a new and more robust interpretation from which further methodology could be developed.

Trait correlated expression combined with expression QTL analysis reveals biological pathways and candidate genes affecting water holding capacity of muscle

Background

Leakage of water and ions and soluble proteins from muscle cells occurs during prolonged exercise due to ischemia causing muscle damage. Also post mortem anoxia during conversion of muscle to meat is marked by loss of water and soluble components from the muscle cell. There is considerable variation in the water holding capacity of meat affecting economy of meat production. Water holding capacity depends on numerous genetic and environmental factors relevant to structural and biochemical muscle fibre properties a well as ante and post slaughter metabolic processes.

Results

Expression microarray analysis of M. longissimus dorsi RNAs of 74 F2 animals of a resource population showed 1,279 transcripts with trait correlated expression to water holding capacity. Negatively correlated transcripts were enriched in functional categories and pathways like extracellular matrix receptor interaction and calcium signalling. Transcripts with positive correlation dominantly represented biochemical processes including oxidative phosphorylation, mitochondrial pathways, as well as transporter activity. A linkage analysis of abundance of trait correlated transcripts revealed 897 expression QTL (eQTL) with 104 eQTL coinciding with QTL regions for water holding capacity; 96 transcripts had trans acting and 8 had cis acting regulation.

Conclusion

The complex relationships between biological processes taking place in live skeletal muscle and meat quality are driven on the one hand by the energy reserves and their utilisation in the muscle and on the other hand by the muscle structure itself and calcium signalling. Holistic expression profiling was integrated with QTL analysis for the trait of interest and for gene expression levels for creation of a priority list of genes out of the orchestra of genes of biological networks relevant to the liability to develop elevated drip loss.

Parthenogenetic activation of bovine oocytes using bovine and murine phospholipase C zeta

BACKGROUND

During natural fertilization, sperm fusion with the oocyte induces long lasting intracellular calcium oscillations which in turn are responsible for oocyte activation. PLCZ1 has been identified as the factor that the sperm delivers into the egg to induce such a response. We tested the hypothesis that PLCZ1 cRNA injection can be used to activate bovine oocytes.

RESULTS

Mouse and bovine PLCZ1 cRNAs were injected into matured bovine oocytes at different concentrations. Within the concentrations tested, mouse PLCZ1 injection activated bovine oocytes at a maximum rate when the pipette concentration of cRNA ranged from 0.25 to 1 mug/muL, while bovine PLCZ1 was optimal at 0.1 mug/muL. At their most effective concentrations, PLCZ1 induced parthenogenetic development at rates similar to those observed using other activation stimuli such as Ionomycin/CHX and Ionomycin/DMAP. Injection of mouse and bovine PLCZ1 cRNA induced dose-dependent sperm-like calcium oscillations whose frequency increased over time. Injection of bovine and mouse PLCZ1 cRNA also induced IP3R-1 degradation, although bovine PLCZ1 cRNA evoked greater receptor degradation than its mouse counterpart.

CONCLUSION

Injection of PLCZ1 cRNA efficiently activated bovine oocytes by inducing a sperm-like calcium oscillatory pattern. Importantly, the high rate of aneuploidy encountered in parthenogenetic embryos activated by certain chemical means was not observed in PLCZ1 activated embryos.

Porcine IL12A and IL12B gene mapping, variation and evidence of association with lytic complement and blood leucocyte proliferation traits

Interleukin-12, a heterodimeric cytokine consisting of glycosylated subunits of 35 and 40 kDa, is a central molecule in controlling innate as well as adaptive immunity. This study was aimed to investigate the role of IL12A and IL12B as candidate genes for immune competence in pigs. The porcine genes were screened for polymorphism and association analysis was carried out by mixed model analysis with parameters of innate immunity, in vitro haemolytic complement activity in the classical and alternative pathways, in vivo complement activation expressed as C3c serum concentration, and blood leucocyte proliferation measured in F2 animals of a pig resource population based on cross of Duroc and Berlin miniature pig (DUMI resource population). A single nucleotide polymorphism (SNP) in the promoter region (C > A) of IL12A was identified. Two SNPs were detected in intron 4 of IL12B at positions 192 (A > G) and 437 (C > T). Significant effects of IL12 genotypes on complement activity traits and mitogen-induced leucocyte proliferation were found. The IL12A and IL12B genes were assigned to chromosome13 and 16, respectively, by using radiation hybrid analysis and genetic mapping in the DUMI resource population. Mapping and association analyses promote the IL12 genes as functional and positional candidate gene for disease resistance in pigs.

189 microRNA EXPRESSION PROFILING DURING BOVINE OOCYTE MATURATION

MicroRNAs (miRNAs) are members of noncoding small RNAs (~21–25 nucleotides long) that inhibit translation and/or induce degradation of protein-coding mRNAs that contain complementary sequences to miRNAs by interacting with the 32 untranslated region. They are known to influence the expression of hundreds of genes in numerous biological processes including development. In order to get insight into the regulation of miRNAs during bovine early development, we applied a heterologous approach to identify and predict bovine miRNAs differentially regulated during oocyte maturation. For this purpose, the miRCURYTM locked nucleic acids (LNA) array (Exiqon, Vedbaek, Denmark), consisting of 454 capture probes for human, mouse, and rat miRNAs, as registered and annotated in the miRBase release 8.0 at TheWellcomeTrust Sanger Institute, was used to compare the miRNA expression profile between bovine immature and matured oocytes. Total RNAs with miRNAs were isolated from three independent pools (each containing 200 oocytes) of immature and in vitro-matured oocytes using an miRNeasy mini kit (Qiagen, Hilden, Germany). The isolated miRNAs were amplified using a Global MicroRNA amplification kit (System Bioscience LLC, Mountain View, CA, USA) to obtain enough targets for hybridization. The RNA samples from immature and matured oocytes were labelled with either Hye3™ or Hye5™ dyes and hybridized on three independent slides. After 16 h of incubation at 60�C, slides were sequentially washed and scanned using an Axon GenePix 4000B scanner (Axon Instruments, Foster City, CA, USA). Species-specific GenePix� Array Lists (GAL; Molecular Devices Corp., Sunnyvale, CA, USA) files of human, mouse, and rat were used independently. Following normalization using GProcessor 2.0a, probes with an average value of ≥1.5-fold change were considered to be differentially regulated. From the total miRNA probes (454) spotted on the array, about 400 were detected in bovine oocytes. Analysis of the array data using a human, mouse, and rat files indicated that a total of 33, 46, and 76 clones were differentially regulated during oocyte maturation, respectively. Of these, 11 miRNAs were found to come out as differentially regulated in all three array analyses. Accordingly, immature oocytes were found to be enriched with miR-208, miR-125a, miR-130b, miR-25, miR-375, and miR-382, while mature oocytes were enriched with miR-122a, miR-101, miR-206, miR-515-5P, and miR-101. The candidate miRNAs were predicted to target mRNA products of genes related to growth regulating proteins, transcription, and tumor necrosis factors. Investigation of the corresponding target mRNAs and protein products during oocyte maturation will enable insight into miRNA-controlled regulation of maternal gene expression.

254 MOLECULAR AND SUBCELLULAR CHARACTERIZATION OF OOCYTES SCREENED FOR THEIR DEVELOPMENTAL COMPETENCE BASED ON G6PDH ACTIVITY

Oocyte selection based on glucose-6-phosphate dehydrogenase (G6PDH) activity has been successfully used to differentiate between competent and incompetent bovine oocytes (Alm 2005 Theriogenology 63, 2194–2205). However, the intrinsic molecular and subcellular characteristics of these oocytes have not yet been investigated. Here we aim to compare the developmental, molecular, and subcellular characteristics of oocytes selected using brilliant cresyl blue (BCB) staining based on G6PDH activity. Immature compact cumulus–oocyte complexes (COCs) were stained with 26 µm BCB (B-5388, Sigma-Alderich, Taufenkirchen, Germany) for 90 min. Based on their coloration, oocytes were divided into BCB– (colorless cytoplasm, high G6PDH activity) and BCB+ (colored cytoplasm, low G6PDH activity). The chromatin configuration and the mitochondrial activity of oocytes were determined by fluorescence labelling and photometric measurement (n = 337). The abundance and phosphorylation pattern of protein kinases Akt and MAP kinase were estimated by western blot analysis (n = 500). A bovine cDNA microarray with 2000 clones was used to analyze the gene expression profiles of BCB+ and BCB– oocytes (n = 580). BCB+ oocytes were found to result in a higher blastocyst rate (33.1 � 3.1%) until Day 8 of in vitro culture compared to BCB– ones (12.1 � 1.5%). Moreover, BCB+ oocytes showed higher phosphorylation levels of Akt and MAP kinase compared to the BCB– oocytes. After array data analysis, BCB+ oocytes were found to be enriched with genes regulating transcription (SMARCA5), cell cycle (NASP), and protein biosynthesis (RPS274A and EEF1A1), while the BCB– oocytes had a higher level of genes involved in ATP synthesis (ATP5A1), mitochondrial electron transport (FL405), calcium ion binding (S100A10), and growth factor activity (BMP-15). Independent real-time quantitative PCR validated 90% (9/10) of the genes investigated to be in agreement with the array expression profile. The study has shown evidence of differences in molecular and subcellular organization of oocytes with different G6PDH activity.

190 SUPPRESSION OF A TRANSCRIPTION FACTOR MSX1 GENE IN BOVINE PREIMPLANTATION EMBRYOS AND ITS EFFECT ON mRNA, PROTEIN, AND EXPRESSION OF DOWNSTREAM GENES

MSX1 is a transcription factor gene that orchestrates gene expression and regulates cell growth, proliferation, differentiation, cell-to-cell communication, and the apoptotic pathway during pattern formation in vertebrate embryogenesis. However, its role in bovine preimplantation embryo is not known. Here we aim to investigate the effects of suppressing MSX1 transcript on the development of in vitro-produced bovine embryos, study the expression of mRNA and protein products of the gene, and identify downstream genes using microarray analysis. In the first experiment, IVP zygotes were injected with 341 bp-long dsRNA (LdsRNA) (n = 384), 19 bp small interfering RNA (siRNA) (n = 374), and scrambled sequence RNA (scRNA) (n = 388). Uninjected zygotes (n = 313) were used as control. Developmental phenotype data were collected during culture until Day 8. The mRNA and protein expression levels of the different treatment groups were validated at the 8-cell and blastocyst stages using quantitative real-time PCR and immunohistochemistry, respectively. Developmental phenotype and mRNA data were analyzed using ANOVA under statistical package SPSS (SPSS, Inc., Chicago, IL, USA). In the second experiment, custom SMARTpool siRNA (Dharmacon Inc., Chicago, IL, USA) targeting bovine MSX1 (NM_174798) was used for microinjection together with siRNA and uninjected control. Following treatment at zygote stage, 8-cell embryos were used for mRNA isolation and subsequent array hybridization using bovine cDNA array containing 2000 clones. Array data analysis was performed using statistical analysis of microarray (SAM) procedure. While 33% and 29% of the zygotes from the control and scRNA treatment groups, respectively, reached blastocyst stage, only 20% and 19% of the zygotes from the LdsRNA and siRNA treatment groups, respectively, reached the same stage. Injection of LdsRNA and siRNA at the zygote stage reduced the mRNA expression level by 52% and 33% at the 8-cell stage and by 77% and 87%, respectively, at the blastocyst stage as compared to the control. Similarly, cellular protein expression levels in LdsRNA- and siRNA-injected treatment groups were found to be lower than the control groups at each stage. In all cases, injection of scRNA had no effect on mRNA and protein levels. SAM analysis revealed that, of the total 2000 clones, 3.5% and 5.4% were found to be differentially expressed in embryos injected with SMARTpool and siRNA, respectively, compared to the control. Genes involved in various activities including transcription factors (ALF), cell growth (BMP-15), metabolism (RIOK3), and cytokinasis (AURKA) were found to be down-regulated in 8-cell embryos treated with SMARTpool siRNA compared to the controls. On the other hand, genes involved in protein synthesis (RPL23), energy metabolism (COQ1), cell growth (MNS1) and skeletal development (LGALS3) were found to be upregulated in the same samples. In conclusion, suppression of MSX1 at the mRNA and protein level significantly affected the development of bovine embryos, and our study revealed list of downstream genes regulated by the activity of MSX1.

134 EFFECT OF ELEVATED CIRCULATING PROGESTERONE CONCENTRATION ON DEVELOPMENT OF IN VITRO PRODUCED BOVINE ZYGOTES IN VIVO

Elevated concentrations of circulating progesterone in the immediate post-conception period have been associated with an increase in embryonic growth rate, interferon-tau production, and pregnancy rate in cattle and sheep. Much of this effect is likely mediated via downstream effects of progesterone-induced changes in gene expression in the tissues of the uterus. However, whether or not progesterone has a direct effect on the embryo also is unknown and, at least in vivo, in single ovulating animals, is difficult to assess. Using state-of-the-art endoscopic techniques, the objective of this study was to examine the effect of elevated progesterone on the development of IVP zygotes transferred to the oviducts of cattle with high or normal circulating progesterone concentrations. Simmental heifers (n = 14) were synchronized using a combination of 2 injections of a prostaglandin F2α analogue administered 11 days apart and gonadotropin-releasing hormone. Only animals exhibiting a clear standing oestrus (= day 0) were used. In order to produce animals with divergent progesterone concentrations, half of the animals received a PRID on day 3 of the oestrous cycle, which was left in place until embryo recovery. All animals were blood sampled daily from days 0 to 7. Cleaved embryos were transferred using endoscopy to the ipsilateral oviduct of each recipient on day 2 and recovered by non-surgically flushing the oviduct and the uterus on day 7. The number of embryos developing to the morula/blastocyst stage was recorded at recovery and following overnight culture in CR1aa medium. Data were analyzed by chi-square analysis. Insertion of a PRID on day 3 resulted in a significant elevation in progesterone concentrations from day 4 (2.36 ± 0.16 ng mL–1 v. 0.54 ± 0.10 ng mL–1, P < 0.001) until day 6 (1.98 ± 0.22 ng mL–1 v. 0.95 ± 0.17 ng mL–1; P < 0.01). The recovery rate was lower in animals that received a PRID (P < 0.05). However, there was no effect of progesterone on the proportion of embryos developing to the morula/blastocyst stage. These results suggest that elevated concentrations of progesterone do not affect the ability of the early embryo to reach the blastocyst stage in vivo and that the reported positive effect of high progesterone levels in terms of fertility are manifested after day 8. Table 1. Effect of elevated progesterone concentration on development of in vitro produced bovine zygotes in vivo

112 Birc6/Apollon INVOLVED IN BOVINE PREIMPLANTATION EMBRYO DEVELOPMENT

Baculoviral inhibitor of apoptosis repeat-containing (Birc)6 gene is known by different names as Birc6, Apollon, Bruce, or KIAA1289. The bovine Birc6 contains the ubiquitin conjugating enzyme. A deletion of the C-terminal half and the ubiquitin conjugating enzyme domain of the mouse apollon is known to activate apoptosis and resulted in embryonic lethality. Moreover, its overexpression in drug-resistance cancer cells suggested its antiapoptotic role. However, its involvement in bovine preimplantation embryo development is not yet known. Therefore, this experiment was conducted to investigate the role of Birc6 in bovine preimplantitive embryos by targeted suppression of the Birc6 mRNA using RNA interference (RNAi). For this, gene-specific long double-stranded RNA (dsRNAi) and short hairpin RNA (shRNAi) targeting Birc6 were in vitro synthesized. In vitro-fertilized zygotes were injected with dsRNAi (n = 347) and shRNAi (n = 374), and uninjected zygotes (n = 366) were used as a control. Sham injection was not used as an additional control in this experiment, because water-injected and uninjected control embryos (Nganvongpanit et al. 2006 Mol. Reprod. Dev. 53, 153–163) have shown similar embryonic development. Following microinjection, the proportion of uncleaved zygotes, 2-, 4- and 8-cell embryos, and the Birc6 mRNA knockdown were determined at 96 h post-insemination (hpi). The effect of Birc6 knockdown on genes involved in apoptotic pathway was evaluated by determining the pro-apoptotic Bax mRNA. The specificity of RNAi was investigated by quantifying glyceraldehyde 3-phosphate dehydrogenase in each treatment group. SPSS version 12.0 (SPSS Inc., Chicago, IL, USA) was used for statistical analysis. The least significant difference t-test pairwise comparison was done between the treatment groups to test varation in uncleaved zygotes, 2-, 4-, and 8-cell embryos. The results showed that the proportion of 8-cell embryos (mean � SEM) was significantly (P < 0.05) higher in control (49.1 � 3.3) compared to dsRNAi (34 � 4.4) and shRNAi (33.5 � 5.2) groups, but the proportion of the 2-cell embryos was significantly higher in dsRNAi (15.1 � 2.3) and shRNAi (14.9 � 3.5) compared to control (8.9 � 1.7), indicating developmental arrest of 2-cell embryos in RNAi groups before reaching the 8-cell stage. Furthermore, the proportion of uncleaved embryos tended to be higher in dsRNAi (34.6 � 3.2) and shRNAi (35.2 � 4.4) compared to control (28.2 � 3.02). The data on the level of suppression on these embryos showed that the Birc6 mRNA in 2-cell embryos was reduced by 85% in dsRNAi and by 50% in shRNAi treatment groups. In 8-cell embryos, 40 and 50% knockdown was achieved in shRNAi and dsRNAi groups, respectively, compared to the control. Similarly, in 8-cell embryos, there was a 23 and 70% increase in mRNA level of Bax in dsRNAi and shRNAi groups, respectively, compared to control, indicating the incidence of apoptosis in the RNAi groups. In conclusion, significantly lower proportions of 8-cell embryos and higher proportion of 2-cell and uncleaved embryos in Birc6 RNAi treatment groups compared to the control groups may reveal the involvement of Birc6 in bovine preimplantation embryo development.

SNP analysis, genotyping and mapping of the porcine <i>PTHR1</i> gene to chromosome 13 (Brief report)

Abstract. The parathyroid hormone/parathyroid hormone like hormone type I receptor (PTHR1) belongs to the family of G protein-coupled receptors for peptide hormones, including parathyroid hormone (PTH) and parathyroid hormone like hormone (PTHLH), which participate in epithelial-mesenchymal interactions during the formation and differentiation of epithelial organs (FOLEY et al., 2001; CHOMDEJ et al., 2004). The function of PTHR1 and its ligands suggest its candidacy for traits related to the development of bones and joints but also of mammary gland. The porcine gene was screened for SNPs and assigned to SSC13.

Identification of genes differentially expressed during prenatal development of skeletal muscle in two pig breeds differing in muscularity

Background

Postnatal muscle growth is largely depending on the number and size of muscle fibers. The number of myofibers and to a large extent their metabolic and contractile properties, which also influence their size, are determined prenatally during the process of myogenesis. Hence identification of genes and their networks governing prenatal development of skeletal muscles will provide insight into the control of muscle growth and facilitate finding the source of its variation. So far most of the genes involved in myogenesis were identified by in vitro studies using gene targeting and transgenesis. Profiling of transcriptome changes during the myogenesis in vivo promises to obtain a more complete picture. In order to address this, we performed transcriptome profiling of prenatal skeletal muscle using differential display RT-PCR as on open system with the potential to detect novel transcripts. Seven key stages of myogenesis (days 14, 21, 35, 49, 63, 77 and 91 post conception) were studied in two breeds, Pietrain and Duroc, differing markedly in muscularity and muscle structure.

Results

Eighty prominent cDNA fragments were sequenced, 43 showing stage-associated and 37 showing breed-associated differences in the expression, respectively. Out of the resulting 85 unique expressed sequence tags, EST, 52 could be assigned to known genes. The most frequent functional categories represented genes encoding myofibrillar proteins (8), genes involved in cell adhesion, cell-cell signaling and extracellular matrix synthesis/remodeling (8), genes regulating gene expression (8), and metabolism genes (8). Some of the EST that showed no identity to any known transcripts in the databases are located in introns of known genes and most likely represent novel exons (e.g. HMGA2). Expression of thirteen transcripts along with five reference genes was further analyzed by means of real-time quantitative PCR. Nine of the target transcripts showed higher than twofold differences in the expression between the two breeds (GATA3, HMGA2, NRAP, SMC6L1, SPP1, RAB6IP2, TJP1 and two EST).

Conclusion

The present study revealed several genes and novel transcripts not previously associated with myogenesis and expands our knowledge of genetic factors operating during myogenesis. Genes that exhibited differences between the divergent breeds represent candidate genes for muscle growth and structure.

Dielectrophoretic behavior of in vitro-derived bovine metaphase II oocytes and zygotes and its relation to in vitro embryonic developmental competence and mRNA expression pattern

Selecting developmentally competent oocytes and zygotes based on their morphology is more often influenced by personal judgments and lacks universal standards. Therefore, this experiment was conducted to investigate the rate of development and mRNA level of dielectrophoretically separated oocytes and zygotes to validate dielectrophoresis (DEP) as non-invasive option for selection of oocytes and zygotes. In the first experiment, metaphase II oocytes with (PB(+)) and without (PB(-)) first polar body and zygotes were subjected to DEP at 4 MHz and 450 mum electrode distance and classified into fast, very fast, slow, and very slow depending on the time elapsed to reach one of the electrodes in the electric field. Parthenogenetic activation was employed to monitor the embryonic development of dielectrophoretically classified oocytes. The result revealed that at 6 and 7 days of post-activation, the blastocyst rate of very slow dielectrophoretic PB(+) and PB(-) oocytes was significantly (P < 0.05) lower than other groups. Similarly, in zygotes, the blastocyst rate at 7 days post-insemination was higher (P < 0.05) in the very fast dielectrophoretic categories when compared with the slow and very slow categories. In the second experiment, mRNA level was analyzed in the very fast and very slow dielectrophoretic PB(+) oocytes and zygotes respectively using the bovine cDNA microarray. The result showed that 36 and 42 transcripts were differentially regulated between the very fast and very slow dielectrophoretic categories PB(+) oocytes and zygotes respectively. In conclusion, dielectrophoretically separated oocytes and zygotes showed difference in the rate of blastocyst development accompanied by difference in transcriptional abundances.

Associations of functional candidate genes derived from gene-expression profiles of prenatal porcine muscle tissue with meat quality and muscle deposition

Ten genes (ANK1, bR10D1, CA3, EPOR, HMGA2, MYPN, NME1, PDGFRA, ERC1, TTN), whose candidacy for meat-quality and carcass traits arises from their differential expression in prenatal muscle development, were examined for association in 1700 performance-tested fattening pigs of commercial purebred and crossbred herds of Duroc, Pietrain, Pietrain x (Landrace x Large White), Duroc x (Landrace x Large White) as well as in an experimental F(2) population based on a reciprocal cross of Duroc and Pietrain. Comparative sequencing revealed polymorphic sites segregating across commercial breeds. Genetic mapping results corresponded to pre-existing assignments to porcine chromosomes or current human-porcine comparative maps. Nine of these genes showed association with meat-quality and carcass traits at a nominal P-value of < or = 0.05; PDGFRA revealed no association reaching the P < or = 0.05 threshold. In particular, HMGA2, CA3, EPOR, NME1 and TTN were associated with meat colour, pH and conductivity of loin 24 h postmortem; CA3 and MYPN exhibited association with ham weight and lean content (FOM) respectively at P-values of < 0.003 that correspond to false discovery rates of < 0.05. However, none of the genes showed significant associations for a particular trait across all populations. The study revealed statistical-genetic evidence for association of the functional candidate genes with traits related to meat quality and muscle deposition. The polymorphisms detected are not likely causal, but markers were identified that are in linkage disequilibrium with causal genetic variation within particular populations.

Alterations in transcript abundance of bovine oocytes recovered at growth and dominance phases of the first follicular wave

Background

Oocyte developmental competence is highly affected by the phase of ovarian follicular wave. Previous studies have shown that oocytes from subordinate follicles recovered at growth phase (day 3 after estrus) are developmentally more competent than those recovered at dominance phase (day 7 after estrus). However, the molecular mechanisms associated with these differences are not well elucidated. Therefore, the objective of this study was to investigate transcript abundance of bovine oocytes retrieved from small follicles at growth and dominance phases of the first follicular wave and to identify candidate genes related to oocyte developmental competence using cDNA microarray.

Results

Comparative gene expression analysis of oocytes from growth and dominance phases and subsequent data analysis using Significant Analysis of Microarray (SAM) revealed a total of 51 differentially regulated genes, including 36 with known function, 6 with unknown function and 9 novel transcripts. Real-time PCR has validated 10 transcripts revealed by microarray analysis and quantified 5 genes in cumulus cells derived from oocytes of both phases. The expression profile of 8 (80%) transcripts (ANAXA2, FL396, S100A10, RPL24, PP, PTTG1, MSX1 and BMP15) was in agreement with microarray data. Transcript abundance of five candidate genes in relation to oocyte developmental competence was validated using Brilliant Cresyl Blue (BCB) staining as an independent model. Furthermore, localization of mRNA and protein product of the candidate gene MSX1 in sections of ovarian follicles at days 0, 1, 3 and 7 of estrous cycle showed a clear fluorescent signal in both oocytes and cumulus cells with higher intensity in the former. Moreover, the protein product was detected in bovine oocytes and early cleavage embryos after fertilization with higher intensity around the nucleus.

Conclusion

This study has identified distinct sets of differentially regulated transcripts between bovine oocytes recovered from small follicles at growth and dominance phases of the first follicular wave. The validation with independent model supports our notion that many of the transcripts identified here may represent candidate genes associated with oocyte developmental competence. Further specific functional analysis will provide insights into the exact role of these transcripts in oocyte competence and early embryonic development.

Association of the FADS2 Gene withω-6 andω-3 PUFA Concentration in the Egg Yolk of Japanese Quail

This study focused on the association of polymorphisms of the FADS2 gene with fatty acid profiles in egg yolk of eight Japanese quail lines selected for high and low omega-6:omega-3 PUFA ratio (h2 = 0.36-0.38). For the identification of polymorphisms within the FADS2 gene 1350 bp of cDNA sequence were obtained encoding 404 amino acids. Five synonymous SNPs were found by comparative sequencing of animals of the high and low lines. These SNPs were genotyped by single base extension on 160 Japanese quail. The association analysis, comprising analysis of variance and family based association test (FBAT), revealed significant effects of SNP3 and SNP4 genotypes on the egg yolk fatty acid profiles, especially the omega-6 and omega-3 PUFAs (P < 0.05). No effects of the other SNPs were found - indicating that these are not in linkage disequilibrium with the causal polymorphism. The results of this study promote FADS2 as a functional candidate gene for traits related to omega-6 and omega-3 PUFA concentration in the egg yolk.

Selective degradation of transcripts in mammalian oocytes and embryos

During the last decade several gene expression analysis studies have been carried out to investigate the transcriptional profile of bovine embryos in response to various culture and treatments conditions. Despite this fact, the function of a large number of genes in mammalian embryogenesis has not yet been investigated or is not known. The conventional gene-knockout experiments have been used extensively to study the function of genes in mammalian embryogenesis. However, these studies are relatively slow and cannot keep pace with the rapid accumulation of new sequence information produced by various genome projects. For this, the posttranscriptional gene silencing (PTGS) by double-stranded RNA (dsRNA), or RNA interference (RNAi), has emerged as a new tool for studying gene function in an increasing number of organisms. The present review will focus on recent developments in the use of RNAi for selective degradation of transcripts in mammalian embryos to elucidate their function in early development.

Molecular genetic analysis of porcine mannose-binding lectin genes, MBL1 and MBL2, and their association with complement activity

Mannose-binding lectin (MBL) mediates activation of the complement system via the lectin pathway. Two forms of MBL, MBL-A and MBL-C, were characterized in rodents, rabbits, bovine and rhesus monkeys, whereas only one form was identified in humans, chimpanzees and chickens. The two forms are encoded by two distinct genes named MBL1 and MBL2, which have been identified in many species including the pig. In this report, we studied the two porcine genes MBL1 and MBL2. The porcine MBL genes had higher identities to bovine rather than primate and rodent sequences. Both genes were assigned to chromosome 14 by radiation hybrid panel and linkage mapping. Both MBL genes were highly expressed in liver. MBL1 was also found to be expressed in the lung, testis and brain, whereas low expression of MBL2 was detected in the testis and kidney. New single nucleotide polymorphisms of porcine MBL2 gene were found and genotyped in an experimental F2 pig population, together with a previously reported SNP of MBL1. MBL1 genotypes differed in C3c serum concentration, i.e. in vivo complement activity, at P < 0.1. Correspondingly, linkage analysis revealed a quantitative trait locus for C3c serum level close to the position of the MBL genes. The study thus promotes the porcine MBL genes as functional and positional candidate gene for complement activity.

A genome scan reveals QTL for growth, fatness, leanness and meat quality in a Duroc-Pietrain resource population

We performed a genome-wide QTL scan for production traits in a line cross between Duroc and Pietrain breeds of pigs, which included 585 F(2) progeny produced from 31 full-sib families genotyped with 106 informative microsatellites. A linkage map covering all 18 autosomes and spanning 1987 Kosambi cM was constructed. Thirty-five phenotypic traits including body weight, growth, carcass composition and meat quality traits were analysed using least square regression interval mapping. Twenty-four QTL exceeded the genome-wide significance threshold, while 47 QTL reached the suggestive threshold. These QTL were located at 28 genomic regions on 16 autosomal chromosomes and QTL in 11 regions were significant at the genome-wide level. A QTL affecting pH value in loin was detected on SSC1 between marker-interval S0312-S0113 with strong statistical support (P < 3.0 x 10(-14)); this QTL was also associated with meat colour and conductivity. QTL for carcass composition and average daily gain was also found on SSC1, suggesting multiple QTL. Seventeen genomic segments had only a single QTL that reached at least suggestive significance. Forty QTL exhibited additive inheritance whereas 31 QTL showed (over-) dominance effects. Two QTL for trait backfat thickness were detected on SSC2; a significant paternal effect was found for a QTL in the IGF2 region while another QTL in the middle of SSC2 showed Mendelian expression.

Quantification of DNA binding, uptake, transmission and expression in bovine sperm mediated gene transfer by RT-PCR: Effect of transfection reagent and DNA architecture

In this study, we compared the transfection effectiveness of liposomes with the new transfection reagent FuGene 6 in bovine sperm mediated gene transfer (SMGT). Furthermore, we examined whether plasmid architecture affects overall efficiency by comparing two plasmids, one of them bearing an additional murine nontranscribed spacer (nts) insert (CMV-INF-tau-IRES-EGFP versus CMV-INF-tau-IRES-EGFP-nts). To accomplish that, we quantified plasmid binding and uptake to spermatozoon and transfer and expression of foreign DNA into embryos by real time PCR. More plasmids bound to spermatozoa when treated with FuGene 6 than with liposome treatment (p<0.05) reaching highest counts in plasmids bearing the nts sequence (p<0.05). Mean number of plasmids taken up was significantly (p<0.05) affected by transfection strategy (1-3 versus 15-81 versus 120-162) with plasmids bearing the nts sequence being 2-8 fold more effective (p<0.05). Culture of SMGT derived embryos up to day 9 did not result in any difference in terms of cleavage rate (64.2-84.2%) and development to blastocyst stage (18.8-26.3%) between different groups. Insert of the nts fragment significantly (p<0.05) affected mean number of transmitted plasmids to 4-cell stage embryos (44 versus 7) and relative INF-tau mRNA expression level in day 9 blastocysts (7-8 fold). However, only six blastocysts (3.6%) exhibited green fluorescence indicating low EGFP protein production. In conclusion, we were able to show effectiveness of sperm mediated gene transfer is significantly affected by choice of transfection reagent and by plasmid architecture.

Transcript profiles of some developmentally important genes detected in bovine oocytes and in vitro-produced blastocysts using RNA amplification and cDNA microarrays

To study the mRNA transcript profiles of some potential candidate developmental genes during bovine oocyte and blastocyst stages, RNA amplification procedures, cDNA microarray of 82 target genes spotted onto glass slide and real-time polymerase chain reaction (PCR) were used. Messenger RNAs were isolated from in vitro-produced bovine matured oocytes and blastocysts. Using equal amounts of input mRNAs but different cycles of amplifications, cDNAs were produced and served as template for RNA amplification by the in vitro transcriptions. After amplification, the RNA yields transcribed from cDNAs of different cycles were evaluated both by hybridization on the cDNA microarrays and by using real-time PCR techniques. The analyses indicated best results from lower amplification cycle templates with consistent signals at hybridization. Generally, the RNA yield was directly proportional to the amplification cycle but inversely related with signal consistency at repeated hybridizations. Using the protocols established, equal amounts of amplified RNA from matured oocytes and blastocysts were hybridized to the array. Analyses of replicated hybridizations indicated that 35 transcripts were differentially expressed. Most of these were not described in previous bovine embryo studies. Independent analyses of 23 transcripts with real-time PCR and unamplified RNA confirmed the results of 22 genes. Moreover, the functional analyses showed various roles related to development. Hence, it is possible to conclude that the genes identified here are potential candidates for characterizing developmental competence, and that the methods established can be used for large-scale gene expression analysis with more comprehensive arrays.

Suppression of connexin 43 and E-cadherin transcripts in in vitro derived bovine embryos following culture in vitro or in vivo in the homologous bovine oviduct

In this study, a combination of RNAi and endoscopic transfer to the oviduct of synchronized heifers has been used to investigate the effect of suppression of Cx43 and E-cadherin on the development, mRNA and protein expression of bovine blastocysts cultured in vitro or in vivo. In vitro matured and fertilized bovine zygotes were randomly assigned to one of four groups namely: Connexin43 dsRNA-injected (n = 790), E-cadherin dsRNA-injected (n = 775), water-injected (n = 774), and noninjected controls (n = 652). Following 2 days in vitro culture, 4- and 8-cell stage embryos from each treatment group were used for culture in vitro or in vivo. About half of the 4-8-cell stage embryos from each treatment group were transferred to the oviduct of synchronized heifers, while the remainder were further cultured in vitro. Embryos from in vivo culture were flushed from recipients on the fourth day post transfer (= Day 7 post insemination). Blastocyst stage embryos from both culture systems were used for mRNA and protein expression analysis. Irrespective of treatment or culture conditions, microinjection resulted in a decline in the proportion of embryos reaching the blastocyst stage. Significantly, lower blastocyst development was observed in E-cadherin and water-injected embryos following in vivo culture compared to the noninjected controls, while intermediate results were obtained following injection with Cx43 dsRNA. Both mRNA and protein products of the target genes were suppressed but the efficiency of suppression of the target genes varied depending on the initial level of transcript abundance, which is known to be greatly affected by the culture environment.

190 INFLUENCE OF IN VITRO CULTURE OF BOVINE EMBRYOS ON THE STRUCTURE OF THE ZONA PELLUCIDA

The zona pellucida is an extracellular structure at the direct interface between the maternal and embryonic sides, through which all signals of the embryo–maternal dialogue as well as nutritional factors have to pass. Up to now there has been no investigation as to whether in vitro culture influences the structure of the zona pellucida compared to that of in vivo embryos. Therefore, in vitro (oocyte, zygote, 2-, 4-, 8-, 16-cell, morula, and Day 7 blastocyst, using the protocol published by Nganvongpanit et al. 2006 Reproduction 131, 861–874) and in vivo (zygote, 4-cell, morula, and blastocyst) embryos were prepared for microscopical investigation. In total, 191 in vitro and 99 in vivo embryos of quality 1 and 2 from at least 2 replicates were used. Araldit-embedded embryos were semi-thin-sectioned and stained with hematoxilin. A morphometrical evaluation was performed to determine the percentage of the more reticular outer part compared to the total thickness of the zona. Furthermore, the total thickness of the zona pellucida was compared between in vitro and in vivo embryos. In parallel, embryos were analyzed by scanning electron microscopy. Up to the 16-cell stage, the zona of in vivo and in vitro embryos is similar, but in vivo morulae and blastocysts show significantly thicker zonae than the in vitro stages. The reticular part of the zona is thicker in in vivo embryos than in in vitro embryos (30.2 � 2.1% vs. 12.4 � 1.8%, respectively). Investigating the pores of the zona pellucida, in vivo morulae/blastocysts show smaller-sized pores than in those derived in vitro. Most of the in vivo morulae/blastocysts are totally covered by secreted granules, and therefore the pores could not be investigated. Furthermore, 30-50% of the in vitro embryos show partly degenerated outer layers of the zona pellucida. This investigation demonstrates that in vitro and in vivo zonae pellucidae are significantly different, reflecting a negative influence of the IVM and IVC.

250 TRANSCRIPTIONAL PROFILING OF BOVINE OOCYTES DERIVED FROM THE GROWTH AND DOMINANCE PHASES OF THE FIRST FOLLICULAR WAVE

Oocytes recovered at the growth phase have a higher blastocsyt rate (24.5%) than those recovered in the dominance phase (11.7%) (Machatkova et al. 2004 Theriogenology 61, 329–335). However, so far the intrinsic properties of these oocytes in relation to the gene expression patterns have not been investigated. Therefore, we aimed here to compare the transcriptional activity of bovine oocytes recovered at the growth and dominance phases of the first follicular wave. Sixty cyclic Simmental heifers (24 to 30 months old) were selected based on general clinical and ovarian normality, divided into 2 groups (30 heifers per group), and housed together. Estrous cycle was synchronized by 2 injections of PGF2α with an 11-day interval, and onset of estrus was considered as Day 0. Ultrasonography-guided ovum pickup (OPU) was performed to collect oocytes from small follicles (3–5 mm) at the growth (Day 3) and dominance (Day 7) phases in 2 sessions per phase. Triplicate pools of oocytes (each with 20 oocytes) from each developmental phase were used for transcriptional analysis using custom bovine cDNA array with 2000 clones (Sirard et al. 2005 Reprod. Fertil. Dev. 17, 47–57). Array images were analyzed using GenePix� Pro 4.0 (Axon Instruments, Inc., Union City, CA, USA), and then the data were LOESS normalized with GPRocessor 2.0a (http://bioinformatics.med.yale.edu/softwarelist.html). Microarray data were analyzed using Significance Analysis for Microarray (SAM) to obtain differentially regulated genes, followed by validation of 10 transcripts with real-time PCR. Data analysis revealed a total of 51 transcripts to be differentially regulated; out of these transcripts, 36 (70%) represented those with known function, 6 (12%) were those with unknown function, and 9 (18%) were novel transcripts. The quantitative real-time PCR validated the expression profile of 8 out of 10 to be in agreement with microarray results. Oocytes from the growth phase (Day 3) were found to be enriched with transcripts involved in protein biosynthesis (RPLP0, RPL8, RPL24, ARL6IP, RpS14, RpS15, RpS4x, and RPS3A), translation elongation (EF1A), ATP binding (ATP5A1), NADH dehydrogenase activity (FL396 and FL405), cytoskeleton (Actin, beta-Actin, H2AZ, and KRT8), calcium ion binding (S100A10 and ANXA2), signal transduction (G-beta like protein), and thiol-disulfide exchange intermediate (TXN). On the other hand, oocytes from the dominance phase (Day 7) were enriched with genes involved in cell cycle (CCNB1, CKS2, UBE2D3, and CDC31), transcription factors (MSX1, PTTG1, FANK1, and PWP1), aldehyde reductase activity (AKR1B1), nucleotide binding (TUBA6), growth factor (BMP15), and fertilization (ZP4). In conclusion, our results indicate that there are differences in transcriptional activity of oocytes derived from different stages of follicular development which may explain their reported differences in developmental competence. Transcripts identified in this study may be used as markers of oocyte competence.

152 DIELECTROPHORETIC BEHAVIOR OF BOVINE OOCYTES AND ZYGOTES IN RELATION TO DEVELOPMENT AND TRANSCRIPTIONAL ABUNDANCE

Selection of developmentally competent oocytes and zygotes based on external morphology has been employed to increase in vitro embryo production. However, this method is more often influenced by personal judgments and lacks universal standards. Hence, this study was aimed at investigating the dielectrophoretic behavior of oocytes and zygotes in relation to their development and mRNA abundance. To achieve the objective, 2 experiments were conducted. In the first experiment, matured bovine oocytes (PB+) and zygotes were subjected to a dielectrophoresis (DEP) procedure designed as follows: 4 MHz AC, 450-�m electrode distance, 5 V, and 80-�s cm-1 medium conductivity. The time elapsed for each of the oocytes and zygotes to reach one of the electrodes from the center was recorded. To accomplish this, 457 PB+ oocytes were subjected to the DEP procedure and 152, 121, 90, and 94 were classified as very fast, fast, slow, and very slow, respectively. Moreover, 152 oocytes were used as controls. Similarly, a total of 940 zygotes were subjected to the DEP procedure and classified as very fast (n = 329), fast (n = 329), slow (n = 97), and very slow (n = 245). In addition, 323 zygotes were used as the control group. The oocyte DEP groups were parthenogenetically activated, and the zygote DEP groups were further in vitro-cultured in a CR1 culture medium supplemented with 10% estrous cow serum, 20 mL mL-1 �-mercaptoethanol, and 10 mL mL-1 minimal essential medium. In PB+ DEP groups, the results show that the blastocyst rate (mean � SEM) at 7 days post-parthenogenetic activation was significantly (P &lt; 0.05) lower in the very slow moving group (7.2 � 4.9) compared to the very fast (21.8 � 3.2), fast (21.5 � 4.6), slow (23.3 � 4.5), and the control (19.7 � 3.7) groups. In zygotes, the blastocyst rate at 7 days post-insemination was significantly (P &lt; 0.05) higher in the very fast (16.1 � 2.7) compared to the slow (9.1 � 2.7) and very slow (10.6 � 2.7) groups, but it was not significantly higher than the fast (12.2 � 2.7) and control (12.3 � 2.7) groups. To investigate whether the transcriptional level of DEP separated very fast and very slow oocytes and zygotes, mRNA expression level was analyzed using a bovine cDNA microarray from a pool of 30 zygotes and oocytes in 6 replications including the dyeswap. The data analyzed using statistical analysis for microarray revealed that 31 and 5 genes were up- and down-regulated, respectively, in very fast compared to very slow PB+ DEP groups. The up-regulated genes are known to be involved in RNA binding and protein biosynthesis (RPL2, RPL8, and RPLPO), ion binding (PTGS2 and ANXA2), and cell cycle regulation (CDC91L1, NUSAP1, and CKS1B). Similarly, 25 and 17 genes were up- and down-regulated, respectively, in the very fast compared to the very slow zygote DEP groups. Some of these genes enriching the very fast zygotes are involved in ion binding (ZNF85, ZNF519, and NANOS1), regulation of cell cycle (NASP, SMARCA5, and AURKA), and signal transduction (RALA). Therefore, from this experiment we can conclude that dielectrophoretically separated oocytes and zygotes show differences in the rate of blastocyst development accompanied by differences in transcriptional abundances.

283 TRANSCRIPTIONAL ANALYSIS OF BIOPSIES DERIVED FROM IN VITRO-PRODUCED BOVINE BLASTOCYSTS IN RELATION TO PREGNANCY SUCCESS AFTER TRANSFER TO RECIPIENTS

Early embryonic mortality is a recognized cause of reproductive failure in cattle leading to the loss of a large number of potential calves, retarded genetic progress, and significant loss of money and time in rebreeding cows. The purpose of this work was to address the relationship between the transcriptional profile of embryos, using the microarray technique, and pregnancy success based on blastocyst biopsies taken prior to transfer to recipients. Biopsies (3 to 40% of the intact embryo) were taken from IVP Day 7 blastocysts (n = 98) and 60 to 70% was transferred to recipients (2-year-old Simmental heifers) after re-expansion. Based on the success of pregnancy, biopsies were pooled in 3 groups: those resulting in no pregnancy (G1), resorption (G2), and calf delivery (G3). Gene expression analysis of these groups of biopsies was performed using a home-made bovine pre-implantation-specific array (with 219 clones) and bovine cDNA array (BlueChip) (with 2000 clones) (Sirard et al. 2005 Reprod. Fertil. Dev. 17, 47–57). Approximately 3 �g of amplified RNA from pooled biopsies (10 biopsies each) was used as a template in reverse transcription reactions incorporating amino-modified dUTPs into labeled cDNA using the CyScribeTM post-labelling kit (Amersham Bioscience, Freiburg, Germany). The synthesized cDNAs from all 3 groups were differentially labeled using Cy3 and Cy5 dyes. Slides were scanned using a GenePix 4000B scanner and images were analyzed using GenePix Pro Version 4.0 software (Axon Instruments, Union City, CA, USA). Data were analyzed using Significant Analysis for Microarray (SAM) software (http//www.stst.stanford.edu/tips/SAM). Quantitative real-time PCR was used to confirm the differentially expressed genes revealed by microarray experiments. Results revealed that 52 genes were differentially regulated between G1 and G3, and 58 genes were differentially regulated between G2 and G3. Biopsies resulting in calf delivery were enriched with genes necessary for implantation (COX-2 and CDX2), signal transduction (PLAU), polyamine biosynthesis (ODC1), response to oxidative stress (TXN), growth factor (BMP15), and placenta-specific 8 (PLAC8). Biopsies that ended up with resorption were enriched with transcripts involving protein phosphorylation (KRT8) plasma membrane (OCLN), and glucose metabolism (PGK1, AKR1B1). Biopsies resulting in no pregnancy were enriched with transcripts involving inflammatory cytokines (TNF), protein amino acid binding (EEF1A1), transcription factors (MSX1, PTTG1), glucose metabolism (PGK1, AKR1B1), and CD9, which is an inhibitor of implantation. In conclusion, we generated direct candidates of blastocyst-specific genes that determine the fate of the embryo after transfer.

Expression of the prion protein gene (PRNP) and cellular prion protein (PrPc) in cattle and sheep fetuses and maternal tissues during pregnancy

We investigated the expression of prion protein gene both on mRNA and protein levels in bovine and ovine female reproductive organs during gestation and various tissues of their fetuses. The fetal tissues of both species included brain, cotyledon, heart, intestine, kidney, liver, lung, and muscle. In cattle, prion protein gene (PRNP) transcripts were detected by semiquantitative RT-PCR in reproductive tissues such as ovary, oviduct, endometrium, myometrium, follicles, and granulosa cells. In various tissues of 2-month-old fetuses, higher expression levels were found in brain and cotyledon compared to the other tissues. To detect the expression of the gene transcript in in vivo preimplantation embryos and 1-month-old fetuses, real-time PCR was performed showing that the level of gene expression in zygote stage was significantly higher (p < or = 0.05) than that of the other stages. Sheep were categorized as resistant (RI) or high susceptible (R5) to scrapie according to their PRNP genotype. In both genotype groups, the PRNP mRNA was detectable in all tissues studied including ovary, oviduct, endometrium, myometrium, and caruncle of ewes and all tissues of 2-month-old fetuses of both groups. Comparison between reproductive organs demonstrates the highest expression level in caruncle tissue of R1 ewes, whereas the level was high in brain and low in liver of both R1 and R5 fetuses. In addition, real-time RT-PCR was performed in immature oocytes, mature oocytes, in vivo embryos at morula stage, and 1-month-old fetuses. The results showed that the relative expression levels of the ovine PRNP mRNA in mature oocytes and morula stage embryos were significantly lower than those in immature oocytes and 1-month-old fetuses (p < or = 0.05). Western blot analyses revealed the immunoreactive bands corresponding to the cellular prion protein (PrPc) in all maternal and fetal tissues examined of both cattle and sheep. Moreover, immunohistochemical staining implicated localization of the PrPc in ovarian cortex and ovarian medulla of both species. However, PrPc was not detected in oocyte, granulosa cells, theca cells, and corpus luteum in this study.

The effect of FF-MAS on porcine cumulus-oocyte complex maturation, fertilization and pronucleus formation in vitro

Follicular fluid meiosis-activating sterol (FF-MAS) has been isolated from the follicular fluid (FF) of several species including man. FF-MAS increases the quality of in vitro oocyte maturation, and thus the developmental potential of oocytes exposed to FF-MAS during in vitro maturation is improved. The aim of the present study was to investigate the effects of FF-MAS on porcine oocyte maturation and pronucleus formation in vitro. Porcine cumulus-oocyte complexes (COCs) were isolated from abattoir ovaries and in vitro matured for 48 h in NCSU 37 medium supplemented with 1 mg/l cysteine, 10 ng/ml epidermal growth factor and 50 microM 2-mercaptoethanol with or without 10% porcine follicular fluid (pFF). For the first 22 h, 1 mM db-cAMP and 10 I.E PMSG/hCG was added. The medium was supplemented with 1 microM, 3 microM, 10 microM, 30 microM or 100 microM FF-MAS dissolved in ethanol. After maturation the COCs were denuded mechanically using a fine glass pipette under constant pH and in vitro fertilized with fresh semen (5 x 10(5) spermatozoa/ml). The presumptive zygotes were evaluated 18 h after fertilization. The addition of pFF increased the monospermic as well as the polyspermic penetration of oocytes. In the absence of pFF, the addition of FF-MAS decreased the polyspermic penetration rate, whereas FF-MAS in combination with pFF decreased monospermic and increased polyspermic penetration. The degeneration rate of ova decreased in the presence of FF-MAS irrespective of the presence or absence of pFF. In the absence of pFF, FF-MAS at 3-10 microM increased the number of zygotes with advanced maternal pronuclear stages. In supraphysiological doses, i.e. 30-100 microM, FF-MAS dose-dependently and reversibly inhibited nuclear maturation in the absence of pFF.

Evidence for Effects of Testis and Epididymis Expressed Genes on Sperm Quality and Boar Fertility Traits

Retinol-binding protein 4 (RBP4), androgen receptor (AR), relaxin (RLN), acrosin (ACR) and osteopontin (polymorphism in intron 6 named OPNin6; polymorphism in promoter region named OPNprom) were addressed as functional candidate genes for sperm quality and boar fertility and investigated for their association with sperm concentration, motility, semen volume per ejaculate, plasma droplets rate, abnormal spermatozoa rate as well as non-return rate and number of piglets born alive. Therefore 356 AI boars of the purebred Pietrain (PI) and crossbred Pietrain x Hampshire (PI x HA) were genotyped at these loci. Analysis of variance revealed significant associations of RBP4 (p < 0.05), ACR (p < 0.01), and OPNin6 (p < 0.05) with sperm motility. OPNin6 (p < 0.05) was also associated with number of piglets born alive. Moreover, AR (p < 0.05) and OPNprom (p < 0.05) were significantly associated with abnormal spermatozoa rate. For RLN (p < 0.01) there was evidence for effects on sperm volume and ACR significantly affected sperm concentration (p < 0.05) as well as non-return rate (p < 0.05). No significant effects of any locus on plasma droplets rate were observed.

The Effect of Nitric Oxide Inhibition and Temporal Expression Patterns of the mRNA and Protein Products of Nitric Oxide Synthase Genes During In Vitro Development of Bovine Pre-implantation Embryos

This study was conducted to determine the effect of Nitric oxide (NO) inhibition in bovine in vitro development and expression analysis of the three Nitric oxide synthase (NOS) isoforms: endothelial (eNOS), neuronal (nNOS) and inducible (iNOS), mRNA and protein in bovine oocytes and embryos. Selective inhibitor of NOS, N-omega-nitro-l-arginine methyl ester (l-NAME) was applied at different doses (0, 0.1, 1 and 10 mm) in maturation (experiment 1A), culture medium (experiment 1B) and in both maturation and culture media (experiment 1C). No significant differences were observed in cleavage and blastocyst rates when oocytes were matured in the presence of l-NAME as long as the inhibitor was omitted during fertilization and culture. However, significantly lower blastocyst rates were observed when l-NAME was present at higher level (10 mm) in culture medium alone and in both maturation and culture media. In experiment 2, mRNA isolated from triplicate pools of oocytes and embryos (n = 15-20) was subjected to quantitative real time reverse transcription polymerase chain reaction to investigate the expression of eNOS, iNOS and nNOS mRNA in normal IVP bovine oocytes and embryos. While eNOS and iNOS transcripts were detected at higher level in oocytes (immature and mature), two-cell and four-cell stage embryos, the nNOS was detected only in immature oocyte, two-cell and morula stages. In experiment 3, eNOS and iNOS protein expression analysis was performed in IVP oocytes and embryos and both proteins were detected in the cytoplasm and the nuclei (weak) of oocytes and embryos. These data provide the first evidence for the role of NO production and the presence of mRNA and protein products of NOS isoforms during bovine embryogenesis.

Haplotype analysis of ?-actin gene for its association with sperm quality and boar fertility

beta-actin (ACTB) was examined as a direct functional candidate gene for the possible association with sperm concentration, motility (MOT), semen volume per ejaculate, plasma droplet rate, abnormal sperm rate (ASR) and the fertility traits, non-return rate and number of piglets born alive (NBA). Three polymorphisms in intron 3 (T>C) and one polymorphism in exon 4 (T>C) of porcine ACTB gene were identified by comparative sequencing of animals of the breeds Pietrain and Hampshire. Association analysis revealed that haplotypes affected the variation of the traits MOT, ASR and NBA. The beneficial haplotypes may provide considerable improvement of sperm quality and fertility in the tested commercial boar population.

Selective degradation of maternal and embryonic transcripts in in vitro produced bovine oocytes and embryos using sequence specific double-stranded RNA

RNA interference (RNAi) has been used for selective degradation of an mRNA transcript or inhibiting its translation to a functional protein in various species. Here, we applied the RNAi approach to suppress the expression of the maternal transcript C-mos and embryonic transcripts Oct-4 in bovine oocytes and embryos respectively, using microinjection of sequence-specific double-stranded RNA (dsRNA). For this, 435 bp C-mos and 341 bp Oct-4 dsRNA were synthesized and microinjected into the cytoplasm of immature oocytes and zygotes respectively. In experiment 1, immature oocytes were categorized into three groups: those injected with C-mos dsRNA, RNase-free water and uninjected controls. In experiment 2, in vitro produced zygotes were categorized into three groups: those injected with Oct-4 dsRNA, RNase-free water and uninjected controls. The developmental phenotypes, the level of mRNA and protein expression were investigated after treatment in both experiments. Microinjection of C-mos dsRNA has resulted in 70% reduction of C-mos transcript after maturation compared to the water-injected and uninjected controls (P<0.01). Microinjection of zygotes with Oct-4 dsRNA has resulted in 72% reduction in transcript abundance at the blastocyst stage compared to the uninjected control zygotes (P<0.01). Moreover, a significant reduction in the number of inner cell mass (ICM) cells was observed in Oct-4 dsRNA-injected embryos compared to the other groups. From oocytes injected with C-mos dsRNA, 60% showed the extrusion of the first polar body compared to 50% in water-injected and 44% in uninjected controls. Moreover, only oocytes injected with C-mos dsRNA showed spontaneous activation. In conclusion, our results demonstrated that sequence-specific dsRNA can be used to knockdown maternal or embryonic transcripts in bovine embryogenesis.

Identification and characterization of an AFLP marker associated with carcass composition in the pig (Brief report)

Abstract. Amplified Fragment Length Polymorphism (AFLP) is a DNA fingerprinting technique that allows genotyping of DNA polymorphisms, mainly single nucleotide substitutions (SNP), across the whole genome with high multiplex ratio and without the need of their prior knowledge. We have successfully combined AFLP with selective genotyping for mapping of quantitative trait loci (QTL) in a F2 resource population based on Duroc and Berlin Miniature pig (DUMI) (WIMMERS et al., 2002). Here we report application of this approach for the identification of loci associated with carcass composition in a herd of commercial German Landrace pigs.

Large-scale transcriptional analysis of bovine embryo biopsies in relation to pregnancy success after transfer to recipients

The purpose of this work is to address the relationship between transcriptional profile of embryos and the pregnancy success based on gene expression analysis of blastocyst biopsies taken prior to transfer to recipients. Biopsies (30-40% of the intact embryo) were taken from in vitro-produced day 7 blastocysts (n = 118), and 60-70% were transferred to recipients after reexpansion. Based on the success of pregnancy, biopsies were pooled in three groups (each 10 biopsies) namely: those resulting in no pregnancy (G1), resorbed embryos (G2), and those resulting in calf delivery (G3). Gene expression analysis of these groups was performed using home-made bovine preimplantation-specific cDNA array (219 clones) and BlueChip (with approximately 2,000 clones). Microarray data analysis results revealed a total of 52 and 58 genes were differentially regulated during comparison between G1 vs. G3 and G2 vs. G3. Biopsies resulted in calf delivery were enriched with genes necessary for implantation (COX2 and CDX2), carbohydrate metabolism (ALOX15), growth factor (BMP15), signal transduction (PLAU), and placenta-specific 8 (PLAC8). Biopsies from embryos resulting in resorption are enriched with transcripts involved protein phosphorylation (KRT8), plasma membrane (OCLN), and glucose metabolism (PGK1 and AKR1B1). Biopsies from embryos resulting in no pregnancy are enriched with transcripts involved inflammatory cytokines (TNF), protein amino acid binding (EEF1A1), transcription factors (MSX1, PTTG1), glucose metabolism (PGK1, AKR1B1), and CD9, which is an inhibitor of implantation. In conclusion, we generated direct candidates of blastocyst-specific genes which may play an important role in determining the fate of the embryo after transfer.

Association of corticotropin-releasing hormone gene variation with performance and meat quality traits in commercial pig lines

The porcine corticotropin-releasing hormone(CRH) gene is a functional-positional candidate for quantitative tract loci on porcine chromosome 4 with major effects on growth and carcass composition. In addition, the central role of CRH in the neuroendocrine response to stress implicates the CRH gene as a functional candidate for meat quality. Association of a single nucleotide polymorphism (SNP) in the promoter region of the porcine CRH gene (g.233C > T) with several growth, carcass and meat quality traits was examined using more than 2000 individuals from four commercial lines: German Landrace (LR), Pietrain (Pi), German Large White x German Landrace (F1) and the German commercial fattening pig cross of Pietrain x F1 (PiF1). Significant association of the CRH SNP was found with feed conversion ratio in the PiF1 line, with carcass length in the LR line and with lean content in the F1, LR and Pi lines. Moreover, significant association with meat colour was found in the Pi and LR lines; however, the effects were in opposite directions. The presented results indicate that sequence variation in the porcine CRH gene has no major effect on growth and carcass composition in commercial pig lines, although it may significantly contribute to variation in meat quality. The g.233C>T SNP may be in incomplete linkage disequilibrium with causal mutations and/or exhibit effects in the context of DNA variation at other interacting loci.

SNP detection and genetic mapping of porcine genes encoding enzymes in hepatic metabolic pathways and evaluation of linkage with carcass traits

We have previously identified and mapped porcine expressed sequence tags (ESTs) derived from genes that are preferentially expressed in liver. The aim of the present study was to identify single nucleotide polymorphisms (SNPs) in porcine genes encoding enzymes in hepatic metabolic pathways and use the SNPs for mapping. Furthermore, these genes, which are involved in utilization and partitioning of nutrients, were examined for their effects on carcass and meat quality traits by linkage analyses. In total, 100 ESTs were screened for SNPs by single strand conformation polymorphism analyses across a diverse panel of animals with a 36% success rate. Twelve of 36 polymorphic loci segregated in a three-generation Duroc x Berlin Miniature Pig (F2) resource population, the DUMI resource population, and were genetically mapped. Interval mapping of the corresponding chromosomes was performed to verify mapping of the genes within quantitative trait loci (QTL) regions detected in this resource population. QTL with genome-wide significance were detected in the vicinity of GNMT, ESTL147 and HGD. These loci therefore are positional candidate genes.

Candidate gene markers for sperm quality and fertility of boar

Candidate genes gonadotropin releasing hormone receptor (GNRHR), prolactin (PRL), prolactin receptor (PRLR), follicle-stimulating hormone beta (FSHB), luteinizing hormone beta (LHB), follistatin (FST), inhibin alpha (INHA), inhibin beta A (INHBA) and inhibin beta B (INHBB) were investigated for their association with sperm quality traits of sperm concentration (SCON), motility (MOT), semen volume per ejaculate (VOL), plasma droplets rate (PDR), abnormal sperm rate (ASR) and fertility traits of non return rate (NRR) and number of piglets born alive (NBA). The experimental material included 356 boars of Pietrain (PI) and Pietrain x Hampshire (PI x HA). Analysis of variance revealed significant association of GNRHR with MOT (P = 0.0161), PDR (P = 0.0048) and ASR (P = 0.0201), INHBA was found to have significant effects on PDR (P = 0.0318) and ASR (P = 0.0067), INHBB was significant (P = 0.0360) for SCON trait. FSHB, FST, INHA, PRL, PRLR and LHB had no significant effects on any trait in this experiment.

[Effects of different donor cells and passages on the development of nuclear transfer porcine embryos]

This study was undertaken to systematically examine effects of different donor cells and passages on the development of nuclear transfer porcine embryos, so as to establish a preliminary procedure for porcine cloning. Porcine oocytes obtained from ovaries at slaughter were matured in vitro for 40-44h and then enucleated in manipulation medium containing 5 microg/mL cytochalasin B. Fibroblast cells (FC), oviduct epithelial cells (OEC), granulosa cells (GC) and cumulus cells(CC) after 3-9 passages in TCM + 10% FBS were treated by serum starvation (0.5% FBS for 2-9 days), 0.1 microg/mL aphidiconlin (APD) for 1 day and 0.5% FBS for 2-9 days or continue culturing in 10% FBS for 2-9 days, then, were transferred into enucleated oocytes by microinjection or electronic fusion (100 V/mm, 30 micros and 1 pulses). Reconstituted embryos were activated with a combination of calcium ionophore A23187 or electric pulse and 6-DMAP, and cultured for 6 days, to evaluate their cleavage and embryonic development. The cleavage rate of embryos reconstructed with FC and GC pretreated with 0.1 microg/mL APD + 0.5% FBS were significantly higher than that of serum starvation group and control group (P<0.01). There was significantly difference in the cleavage rate and embryonic development among embryos derived from GC, CC and FC, OEC pretreated with 0.1 microg/mL APD + 0.5% FBS. The cleavage rate of embryos reconstructed with GC by electrofusion was significantly higher than that by microinjection (P<0.05), but no difference was found in their proportion developing to blastocysts. 75% to 85% of GC at 3 and 6 passages, and FC at 6 and 10 passages had normal karyotype, which did not show significant difference among them (P>0.05). When GC at G3, G4, G5 and G6 of passages were used as donor cells, the cleavage rate and blastocyst rate was similar, moreover, FC at G6, G7, G8 and G9 of passages also resulted in a similar cleavage rate and blastocyst development. These results indicate that: (1) FC and GC can be cultured up to 9 passages and keep relatively stable karyotepe; (2) Using 0.1 microg/mL APD to treat donor cells prior to nuclear transfer can improve the efficiency of somatic cell nuclear transfer in buffalo but serum starvation is inefficient in our system; (3) Both of FC and GC cells can be used as the donor karyoplasts for nuclear transfer, and their efficiency are not influenced by the culture passages; (4) The development of reconstructed embryos by electrofusion is higher than that by microinjection, but there is no difference in the total efficiency between the two methods.

Molecular characterization and evidencing of the porcine CRH gene as a functional-positional candidate for growth and body composition

Corticotropin-releasing hormone (CRH), a major regulator of neuroendocrine response to stress, is involved in the control of energy balance and thus may affect body composition and growth. The porcine CRH (pCRH) gene was studied as a comparative-positional candidate for QTL for longissimus muscle area, average backfat thickness, carcass length, and average daily gain on test on porcine chromosome 4. Sequence of the complete transcriptional unit of pCRH gene spanning 2068bp was determined along with 582bp of the 5'-flanking region. Cross-species sequence comparison revealed a number of potential regulatory regions including an intronic evolutionary conserved region and an adjacent CpG island that may control cell-type specific expression of the CRH gene. A SNP in exon 2 (c.+83G>A) leading to a non-conservative amino acid exchange (p.28Arg>Gln) in the prohormone was identified that is segregating in the DUMI resource population. Linkage and association analysis based on this SNP revealed that for all four traits the pCRH gene falls in the QTL peak area and that the c.+83G>A SNP shows a highly significant additive effect (p<0.0001). Physical mapping using the IMpRH panel assigned the pCRH gene to interval SW724-S0107, promoting the gene as a positional candidate also for QTL identified in other porcine resource populations. Additional four variable sites were identified that segregate in commercial pig breeds. Particularly interesting is a SNP (g.233C>T) in the 5'-flanking region that occurred in an evolutionary conserved motif. The knowledge of the DNA-variation of pCRH gene will facilitate follow-up studies necessary to provide definite genetic evidence of the effect of pCRH gene on body composition and growth.

QTL for microstructural and biophysical muscle properties and body composition in pigs

Background

The proportion of muscle fibre types and their size affect muscularity as well as functional properties of the musculature and meat quality. We aimed to identify QTL for microstructural muscle properties including muscle fibre size, their numbers and fibre type proportions as well as biophysical parameters of meat quality and traits related to body composition, i.e. pH, conductivity, area of M. longissimus dorsi and lean meat content. A QTL scan was conducted in a porcine experimental population that is based on Duroc and Berlin Miniature Pig.

Results

Least square regression interval mapping revealed five significant and 42 suggestive QTL for traits related to muscle fibre composition under the line-cross model as well as eight significant and 40 suggestive QTL under the half-sib model. For traits related to body composition and biophysical parameters of meat quality five and twelve significant plus nine and 22 suggestive QTL were found under the line-cross and half-sib model, respectively. Regions with either significant QTL for muscle fibre traits or significant QTL for meat quality and muscularity or both were detected on SSC1, 2, 3, 4, 5, 13, 14, 15, and 16. QTL for microstructural properties explained a larger proportion of variance than did QTL for meat quality and body composition.

Conclusion

Microstructural properties of pig muscle and meat quality are governed by genetic variation at many loci distributed throughout the genome. QTL analysis under both, the line-cross and half-sib model, allows detecting QTL in case of fixation or segregation of the QTL alleles among the founder populations and thus provide comprehensive insight into the genetic variation of the traits under investigation. Genomic regions affecting complex traits of muscularity and meat quality as well as microstructural properties might point to QTL that in first instance affect muscle fibre traits and by this in second instance meat quality. Disentangling complex traits in their constituent phenotypes might facilitate the identification of QTL and the elucidation of the pleiotropic nature of QTL effects.

Bovine NALP5, NALP8, and NALP9 Genes: Assignment to a QTL Region and the Expression in Adult Tissues, Oocytes, and Preimplantation Embryos

A 3204-bp full-length cDNA of bovine NALP9 was cloned and its genomic organization was analyzed. The 2988-bp open reading frame covers 9 exons and encodes a deduced protein of 996 amino acids containing Pyrin, Nacht and leucine-rich repeat domains like the human NALP gene family members. Mapping with the WGRH5000 panel and fluorescence in situ hybridization assigned NALP9 in close vicinity to BM2078 (LOD score 25.71; distance 0.0 cR5000) on bovine chromosome 18, BTA18q25-q26, within a previously identified QTL region for reproductive traits flanked by the bovine marker BM2078 and TGLA227. BAC contig analysis revealed that NALP9, NALP8, and NALP5 map in this QTL region. Temporospatial expression of these members of the NALP gene family was monitored. Among the adult tissues examined, transcripts of NALP8 and NALP9 were detected exclusively in testis and ovary, whereas transcripts of the NALP5 gene are limited to the ovary. The transcripts of NALP9, NALP8, and NALP5 were detected in oocytes before and after in vitro maturation and with a gradual decline from 2-cell to 8-cell stage, suggesting no reactivation at the time of bovine maternal to embryonic transition. Assignment to a QTL region for reproductive traits and preferential expression of NALP9, NALP8, and NALP5 in oocyte, germinal lineage, and gonad cells may suggest their functional relevance to reproduction and possible contribution to phenotypic variation.