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Kapell DNRG, Sorensen D, Su G, Janss LLG, Ashworth CJ, Roehe R. Efficiency of genomic selection using Bayesian multi-marker models for traits selected to reflect a wide range of heritabilities and frequencies of detected quantitative traits loci in mice. BMC Genet 2012; 13:42. [PMID: 22651804 PMCID: PMC3453524 DOI: 10.1186/1471-2156-13-42] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 05/31/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Genomic selection uses dense single nucleotide polymorphisms (SNP) markers to predict breeding values, as compared to conventional evaluations which estimate polygenic effects based on phenotypic records and pedigree information. The objective of this study was to compare polygenic, genomic and combined polygenic-genomic models, including mixture models (labelled according to the percentage of genotyped SNP markers considered to have a substantial effect, ranging from 2.5% to 100%). The data consisted of phenotypes and SNP genotypes (10,946 SNPs) of 2,188 mice. Various growth, behavioural and physiological traits were selected for the analysis to reflect a wide range of heritabilities (0.10 to 0.74) and numbers of detected quantitative traits loci (QTL) (1 to 20) affecting those traits. The analysis included estimation of variance components and cross-validation within and between families. RESULTS Genomic selection showed a high predictive ability (PA) in comparison to traditional polygenic selection, especially for traits of moderate heritability and when cross-validation was between families. This occurred although the proportion of genomic variance of traits using genomic models was 22 to 33% smaller than using polygenic models. Using a 2.5% mixture genomic model, the proportion of genomic variance was 79% smaller relative to the polygenic model. Although the proportion of variance explained by the markers was reduced further when a smaller number of SNPs was assumed to have a substantial effect on the trait, PA of genomic selection for most traits was little affected. These low mixture percentages resulted in improved estimates of single SNP effects. Genomic models implemented for traits with fewer QTLs showed even lower PA than the polygenic models. CONCLUSIONS Genomic selection generally performed better than traditional polygenic selection, especially in the context of between family cross-validation. Reducing the number of markers considered to affect the trait did not significantly change PA for most traits, particularly in the case of within family cross-validation, but increased the number of markers found to be associated with QTLs. The underlying number of QTLs affecting the trait has an effect on PA, with a smaller number of QTLs resulting in lower PA using the genomic model compared to the polygenic model.
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Ashworth CJ, Hogg CO, Hoeks CWF, Donald RD, Duncan WC, Lawrence AB, Rutherford KMD. Pre-natal social stress and post-natal pain affect the developing pig reproductive axis. Reproduction 2011; 142:907-14. [DOI: 10.1530/rep-11-0280] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This study assessed the effect of pre-natal social stress and post-natal pain on the reproductive development of young (approximately day 40) pigs. Male pigs carried by sows that were stressed by mixing with unfamiliar older sows for two 1-week periods during mid-pregnancy had lower plasma testosterone (0.54 vs 0.86 ng/ml, s.e.d.=0.11; P=0.014) and oestradiol (E2; 22.9 vs 38.7 pg/ml, s.e.d.=7.80; P=0.021) concentrations compared with males carried by unstressed control sows. Although there was no effect of pre-natal stress on female E2 concentrations, female pigs carried by stressed sows had fewer primordial ovarian follicles (log −4.32/μm2 vs −4.00/μm2, s.e.d.=0.136; P=0.027). Tail amputation on day 3 after birth reduced E2 concentrations in female (4.78 vs 6.84 pg/ml, s.e.d.=0.86; P=0.03) and in male (25.6 vs 34.9 pg/ml, s.e.d.=3.56; P=0.021) pigs and reduced both testis weight (0.09% of body weight vs 0.10% of body weight, s.e.d.=0.003; P=0.01) and the percentage of proliferating Leydig cells (1.97 vs 2.12, s.e.d.=0.114; P=0.036) compared with sham-amputated littermate controls. There was a significant (P=0.036) interaction between the effects of pre-natal stress and post-natal pain on testicular expression of the steroidogenic enzyme 17α-hydroxylase, such that amputation increased expression in pigs born to control sows, but reduced expression in animals born to stressed sows. This study shows that stressful procedures associated with routine animal husbandry can disrupt the developing reproductive axis.
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Hickman CF, Ainslie A, Ealy AD, Ashworth CJ, Rooke JA. Effect of Ovine Granulocyte-Macrophage Colony-stimulating Factor on Bovine In Vitro Embryo Development and Blastocyst Interferon-τ Secretion. Reprod Domest Anim 2010; 46:608-15. [DOI: 10.1111/j.1439-0531.2010.01710.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Ashworth CJ, Toma LM, Hunter MG. Nutritional effects on oocyte and embryo development in mammals: implications for reproductive efficiency and environmental sustainability. Philos Trans R Soc Lond B Biol Sci 2010; 364:3351-61. [PMID: 19833647 DOI: 10.1098/rstb.2009.0184] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The environment in which a breeding female lives prior to conception and during the early stages of her pregnancy has striking effects on oocytes developing in the ovarian follicle and on early embryos in the reproductive tract. Of the various environmental factors known to affect oocyte and embryo development, altered nutrition during this critical period has been particularly well studied. Alterations in the quantity of food consumed or the composition of the diet imposed solely during the pre-mating period affect oocyte maturity, blastocyst yield, prenatal survival and the number of offspring born alive. Importantly, nutrition at this time also affects the quality of embryos and resultant offspring, with increasing evidence from a variety of species showing that peri-conception nutrition can alter behaviour, cardiovascular function and reproductive function throughout post-natal life. In livestock species, it is important to devise nutritional strategies that improve reproductive efficiency and the quality of offspring but that do not add to the environmental footprint of the production system and which recognize likely changes in feedstuff availability arising from predicted changes in climate.
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Hernandez SC, Finlayson HA, Ashworth CJ, Haley CS, Archibald AL. Mapping quantitative trait loci for reproduction in pigs. SOCIETY OF REPRODUCTION AND FERTILITY SUPPLEMENT 2009; 66:117-118. [PMID: 19848274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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McNeil CJ, Nwagwu MO, Finch AM, Page KR, Thain A, McArdle HJ, Ashworth CJ. Glucocorticoid exposure and tissue gene expression of 11beta HSD-1, 11beta HSD-2, and glucocorticoid receptor in a porcine model of differential fetal growth. Reproduction 2007; 133:653-61. [PMID: 17379659 DOI: 10.1530/rep.1.01198] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Glucocorticoids play a critical role in fetal development, but inappropriate exposure is associated with reduced fetal growth. We investigated cortisol exposure and supply in a porcine model of differential fetal growth. This model compares the smallest fetus of a litter with an average-sized sibling at three stages of gestation. At day 45, small fetuses had reduced plasma cortisol (16.8 +/- 3.4 ng/ml) relative to average fetuses (34.4 +/- 3.4 ng/ml, P < 0.001). At day 65 levels had reduced in small and average fetuses to similar concentrations (5.7 +/- 1.0 vs 4.8 +/- 0.5 ng/ml, P = 0.128). By day 100, elevated levels were found in small fetuses (10.7 +/- 1.5 vs 7.6 +/- 0.7 ng/ml, P < 0.001). Maternal plasma cortisol was unchanged over gestation (day 45, 56.7 +/- 21.6 ng/ml; day 65, 57.8 +/- 14.4 ng/ml; day 100, 55.7 +/- 6.5 ng/ml). We examined the cause of altered cortisol by investigating the fetal hypothalamic-pituitary-adrenal axis through the measurement of adrenocorticotropic hormone and assessing exposure to maternal cortisol by quantifying placental 11beta-hydroxysteroid dehydrogenase-isoform 2 (11beta HSD-2) gene expression. These data suggest that altered cortisol supply was of fetal origin. We examined organ glucocorticoid (GC) metabolism by the measurement of GC receptor (GR) and 11beta-hydroxysteroid dehydrogenase-isoform 1 (11beta HSD-1) gene expression. We found that fetal organs have different temporal patterns of 11beta HSD-1 and GR expression, with the liver particularly sensitive to cortisol in late gestation. This study examines GC exposure in naturally occurring differential growth and simultaneously explores tissue GC sensitivity and handling, at three key stages of gestation.
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Tilley RE, McNeil CJ, Ashworth CJ, Page KR, McArdle HJ. Altered muscle development and expression of the insulin-like growth factor system in growth retarded fetal pigs. Domest Anim Endocrinol 2007; 32:167-77. [PMID: 16564666 DOI: 10.1016/j.domaniend.2006.02.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2005] [Revised: 02/09/2006] [Accepted: 02/11/2006] [Indexed: 11/17/2022]
Abstract
We have used a porcine model of spontaneous differential fetal growth to investigate the effects of fetal size on muscle development. We hypothesized that altered muscle development may occur in small fetuses as a consequence of modified expression of selected genes of the insulin-like growth factor system. We examined the development of the Longissimus muscle (m. Longissimus) in small fetuses and their average sized littermates. We collected small for gestational age fetuses and their average sized sibling on days 45, 65 and 100 of gestation (term is 113-116 days). Small fetuses had significantly lower body weight at all three stages of gestation (p<0.05) and significantly reduced secondary to primary muscle fibre ratio in m. Longissimus on day 100 (p<0.05) compared to their littermates. On day 65, the expression of insulin-like growth factor receptor 1 and insulin-like growth factor binding protein 3 were significantly higher (p<0.05) in m. Longissimus of the small fetuses compared with their average sized littermates. On day 100, the expression of insulin-like growth factor receptor 1 remained significantly higher (p=0.001), in addition to significantly higher levels of insulin-like growth factor receptor 2 and insulin-like growth factor binding protein 5 in the small fetuses (p<0.05). No difference in levels of myogenin was observed between the small and average sized littermates. In conclusion, we demonstrate that reduced fetal muscle development is associated with an increased expression of several genes of the insulin-like growth factor system in small fetuses in mid to late gestation.
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Rooke JA, McEvoy TG, Ashworth CJ, Robinson JJ, Wilmut I, Young LE, Sinclair KD. Ovine fetal development is more sensitive to perturbation by the presence of serum in embryo culture before rather than after compaction. Theriogenology 2007; 67:639-47. [PMID: 17070902 DOI: 10.1016/j.theriogenology.2006.09.040] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2006] [Revised: 09/19/2006] [Accepted: 09/21/2006] [Indexed: 11/29/2022]
Abstract
The effects on subsequent fetal development of the presence or absence of serum at different times during IVC of ovine zygotes were studied. Zygotes, recovered from superovulated ewes 36h after intrauterine AI using semen from a single sire, were cultured for 5 days in synthetic oviductal fluid (SOF) media supplemented with either BSA and amino acids (SOF-) or with 10% (v/v) steer serum (SOF+). Serum was present or absent during the first two and last 2 days of IVC giving four treatments (SOF-/SOF-; SOF-/SOF+;SOF+/SOF- and SOF+/SOF+). In total, 224 embryos, including 26 in vivo controls, were transferred singly at day 6 post-AI to synchronous recipients and the products of conception recovered at day 125 of gestation. Presence of serum during IVC had a biphasic effect on embryo development. The inclusion of serum during the first 2 days of IVC retarded early embryo development while the inclusion of serum during the last 2 days of IVC produced more blastocysts by day 6. These effects were independent of each other. The presence of serum during the first 2 days of IVC resulted in increased weights of gravid uterus, placenta, fetus, fetal heart and liver. The incidence of fetuses whose total or organ weights were greater than three standard deviations above the corresponding mean weights of control fetuses was also greater when serum was present during the first 2 days of IVC. However, even when serum was absent throughout IVC there was still an infrequent incidence of fetal weights greater than three standard deviations above the mean for control fetuses. These observations provide evidence that it is the early pre-compaction stages of embryo development that are particularly sensitive to perturbations leading to abnormal fetal development.
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Ferguson EM, Slevin J, Hunter MG, Edwards SA, Ashworth CJ. Beneficial effects of a high fibre diet on oocyte maturity and embryo survival in gilts. Reproduction 2007; 133:433-9. [PMID: 17307911 DOI: 10.1530/rep-06-0018] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The present study examined the effects of feeding gilts a high fibre diet from the third post-pubertal oestrus until either day 19 of the same cycle or insemination at the following oestrus on oocyte maturity, embryo survival and associated changes in reproductive hormone concentrations. Gilts fed with the high fibre diet had lower circulating oestradiol concentrations on days 17, 18 and 19 of the cycle and increased LH pulse frequency on day 18. More oocytes recovered on day 19 from gilts receiving the high fibre diet were at metaphase II after 46-h culture in medium containing 10% of their own follicular fluid, despite fewer large (>7 mm) follicles in these gilts when compared with control animals. There was no effect of diet on ovulation rate, corpora lutea size or progesterone concentrations on days 10–12 after insemination, but embryo survival on days 27–29 after insemination was higher in gilts that received the high fibre diet. This study demonstrates that a high fibre diet that increases embryo survival also improves oocyte maturity and provides information on endocrine correlates that may shed light on underlying mechanisms.
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Mitchell LM, Robinson JJ, Watt RG, McEvoy TG, Ashworth CJ, Rooke JA, Dwyer CM. Effects of cobalt/vitamin B12 status in ewes on ovum development and lamb viability at birth. Reprod Fertil Dev 2007; 19:553-62. [PMID: 17524300 DOI: 10.1071/rd07012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Accepted: 03/12/2007] [Indexed: 01/11/2023] Open
Abstract
Scottish Blackface ewes from cobalt-deficient farmland were fed a diet containing 0.06 mg cobalt per kg dry matter from approximately 30 days before embryo recovery/transfer until lambing. Ewes remained untreated (–Co; n = 82) or were given an intraruminal cobalt-containing bolus to compensate for the dietary deficit (+Co; n = 82). Ewes used as embryo donors (–Co, n = 17; +Co, n = 16) were artificially inseminated with semen from a single Suffolk sire. Day 6 embryos obtained from –Co and +Co donors were transferred in singleton to –Co and +Co recipients in a 2 × 2 factorial-designed experiment to determine the effects of cobalt/vitamin B12 status during the periconception period (factor 1) and pregnancy (factor 2) on lamb viability at birth. Mean (± s.e.m.) circulating concentrations of vitamin B12 in –Co and +Co donors at ovum recovery were 182 ± 10 and 1288 ± 64 pmol L–1, respectively (P < 0.001), and the number of corpora lutea per ewe ovulating was 9.9 ± 1.6 and 14.4 ± 1.3, respectively (P < 0.05). Treatment did not affect the proportion of recovered ova that contained >32 cells (viable) or the median stage of development (late morula), but viable ova recovered from –Co v. +Co ewes had a better morphological grade (2.0 ± 0.1 v. 2.20 ± 0.04, respectively; P < 0.01). There was no effect of treatment on the proportion of recipient ewes that became pregnant. Circulating concentrations of vitamin B12 were lower in –Co than +Co ewes during pregnancy (P < 0.001) and at birth in lambs born to –Co ewes compared with those born to +Co ewes (P < 0.001). There was no effect of donor or recipient cobalt/vitamin B12 status on lamb birthweight, neonatal vigour or neonatal rectal temperatures, but lambs derived from +Co v. –Co embryo donors were more active in the first 3 days after birth (P < 0.05). Results show that sub-clinical cobalt/vitamin B12 deficiency reduces ovulatory response in superovulated ewes and that periconception nutrition can affect neonatal lamb behaviour.
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Jones HN, Ashworth CJ, Page KR, McArdle HJ. Expression and adaptive regulation of amino acid transport system A in a placental cell line under amino acid restriction. Reproduction 2006; 131:951-60. [PMID: 16672359 DOI: 10.1530/rep.1.00808] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Trans-placental transport of amino acids is vital for the developing fetus. Using the BeWo cell line as a placental model, we investigated the effect of restricting amino acid availability on amino acid transport system type A. BeWo cells were cultured either in amino acid-depleted (without non-essential amino acids) or control media for 1, 3, 5 or 6 h. System A function was analysed using alpha(methyl-amino)isobutyric acid (MeAIB) transcellular transport studies. Transporter (sodium coupled neutral amino acid transporter (SNAT1/2)) expression was analysed at mRNA and protein level by Northern and Western blotting respectively. Localisation was carried out using immunocytochemistry. MeAIB transcellular transport was significantly (P < 0.05) increased by incubation of the cells in amino acid-depleted medium for 1 h, and longer incubation times caused further increases in the rate of transfer. However, the initial response was not accompanied by an increase in SNAT2 mRNA; this occurred only after 3 h and further increased for the rest of the 6-h incubation. Similarly, it took several hours for a significant increase in SNAT2 protein expression. In contrast, relocalisation of existing SNAT2 transporters occurred within 30 min of amino acid restriction and continued throughout the 6-h incubation. When the cells were incubated in medium with even lower amino acid levels (without non-essential plus 0.5 x essential amino acids), SNAT2 mRNA levels showed further significant (P < 0.0001) up-regulation. However, incubation of cells in depleted medium for 6 h caused a significant (P = 0.014) decrease in the expression of SNAT1 mRNA. System L type amino acid transporter 2 (LAT2) expression was not changed by amino acid restriction, indicating that the responses seen in the system A transporters were not a general cell response. These data have shown that placental cells adapt in vitro to nutritional stress and have identified the physiological, biochemical and genomic mechanisms involved.
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Ferguson EM, Slevin J, Edwards SA, Hunter MG, Ashworth CJ. Effect of alterations in the quantity and composition of the pre-mating diet on embryo survival and foetal growth in the pig. Anim Reprod Sci 2006; 96:89-103. [PMID: 16426776 DOI: 10.1016/j.anireprosci.2005.11.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Revised: 10/18/2005] [Accepted: 11/23/2005] [Indexed: 11/28/2022]
Abstract
This trial examined the effects of feeding six diets, which varied in either amount or composition, during the oestrous cycle prior to insemination on embryo survival and foetal development on day 27+/-2 of pregnancy in gilts. Ten or 11 gilts per group received either a maintenance (M) diet, 1.8 x M, 2.6 x M or nutritionally balanced diets in which the content of fibre, protein or starch was increased. Of the six diets tested, only the high fibre diet significantly increased embryo survival when compared to its 1.8 x M isoenergetic control (88.20+/-1.96% versus 81.25+/-2.67%; P<0.05). More litters from gilts fed the 1.8 x M and the starch diets had foetuses defined as intra-uterine growth retarded (IUGR; 50% and 62.5 of litters, respectively), compared to the other four groups in which 0-12.5% of litters contained IUGR foetuses (P<0.05). There was no effect of dietary treatment on foetal or placental size or on the within-litter variability in foetal and placental size. Plasma concentrations of oestradiol and progesterone on days 4-8 of the oestrous cycle and on day 27+/-2 of pregnancy were unaffected by treatment. Feed intake was positively related to mean plasma IGF-1 concentrations on days 4-8 of the cycle (P<0.01) and to mean leptin concentrations on days 4 and 5 (P<0.001). Leptin concentrations were unaffected by alterations in the composition of the diet, whereas IGF-1 concentrations were higher in gilts fed the starch diet compared to the M control (159+/-9.52 versus 127+/-7.65 ng/ml; P<0.05). These data demonstrate that alteration to the composition of the feed consumed during the cycle before insemination can affect both embryo survival and the distribution of foetal size within the litter. The underlying mechanism(s) remain to be determined, but probably involve dietary-induced changes in concentrations of reproductive hormones and/or intermediary metabolites that in turn affect ovarian follicular and oocyte development.
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Jones HN, Ashworth CJ, Page KR, McArdle HJ. Cortisol stimulates system A amino acid transport and SNAT2 expression in a human placental cell line (BeWo). Am J Physiol Endocrinol Metab 2006; 291:E596-603. [PMID: 16621896 DOI: 10.1152/ajpendo.00359.2005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Both placental system A activity and fetal plasma cortisol concentrations are associated with intrauterine growth retardation, but it is not known if these factors are mechanistically related. Previous functional studies using hepatoma cells and fibroblasts produced conflicting results regarding the regulation of system A by cortisol. Using the b30 BeWo choriocarcinoma cell line, we investigated the regulation of system A by cortisol. System A function was analyzed using methyl amino isobutyric acid (MeAIB) transcellular transport studies. Transporter expression [system A transporter (SNAT)1/2] was studied at the mRNA and protein levels using Northern and Western blotting, respectively. Localization was carried out using immunocytochemistry. The [(14)C]MeAIB transfer rate across BeWo monolayers after preincubation with cortisol for 24 h was significantly increased compared with control. This was associated with a relocalization of the SNAT2 transporter at lower cortisol levels and significant upregulation of mRNA and protein expression levels at cortisol levels >1 microM. This is the first study to show functional and molecular regulation of system A by cortisol in BeWo cells. It is also the first study to identify which system A isoform is regulated. These results suggest that cortisol may be involved in upregulation of system A in the placenta to ensure sufficient amino acid supply to the developing fetus.
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Powell K, Rooke JA, McEvoy TG, Ashworth CJ, Robinson JJ, Wilmut I, Young LE, Sinclair KD. Zygote donor nitrogen metabolism and in vitro embryo culture perturbs in utero development and IGF2R expression in ovine fetal tissues. Theriogenology 2006; 66:1901-12. [PMID: 16777210 DOI: 10.1016/j.theriogenology.2006.05.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2006] [Revised: 05/02/2006] [Accepted: 05/04/2006] [Indexed: 11/19/2022]
Abstract
Tests were made of the effects of altering nitrogen metabolism in zygote donor ewes on fetal development and expression of the gene encoding the type II insulin-like growth factor receptor (IGF2R) following the transfer of ovine embryos cultured from these zygotes, either in the absence or presence of serum. Zygotes, recovered from superovulated ewes (32 on a urea supplemented (30 g urea/kg) diet (high N) and 32 on a control diet (low N)) 36 h after intrauterine AI using semen from a single sire, were cultured for 5 days in synthetic oviductal fluid (SOF) media either with BSA and amino acids (SOF-) or with 10% (v/v) steer serum (SOF+). In total, 166 embryos, including 30 in vivo controls, were transferred singly at day 6 post-AI to synchronous recipients and the products of conception recovered at day 125 of gestation. Elevated plasma urea concentrations in zygote donors were associated with accelerated early embryo development, low pregnancy rates (16%) for embryos from the high N, SOF+ treatment, and significantly influenced fetal development and the expression of IGF2R in the fetal heart at day 125 of gestation. Importantly, the culture of sheep zygotes under serum-free conditions led to a high incidence of aberrant conceptus development and IGF2R expression. Consequently, maternal nitrogen metabolism prior to zygote recovery and in vitro culture can influence fetal development and the expression of an imprinted gene following embryo transfer, and these data support the notion that environmental effects on the follicle-enclosed oocyte may contribute to the etiology of the Large Offspring Syndrome.
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McNeil CJ, Finch AM, Page KR, Clarke SD, Ashworth CJ, McArdle HJ. The effect of fetal pig size and stage of gestation on tissue fatty acid metabolism and profile. Reproduction 2005; 129:757-63. [PMID: 15923391 DOI: 10.1530/rep.1.00451] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The fetus requires an adequate supply of fatty acids for optimum growth and development. It has been hypothesized that reduced activity of enzymes of fatty acid metabolism could contribute to inadequate fetal growth. In a porcine model of differential fetal growth we examined heart and liver fatty acid synthase, delta5-desaturase and delta6-desaturase gene expression and measured hepatic fatty acid profile to assess long-chain polyunsaturated fatty acid status. On gestation days 45, 65 and 100 sows were killed and tissues extracted from an average-sized fetus and the smallest fetus from each litter. As early as day 45, considerable hepatic delta5- and delta6-desaturase was detected, and this expression significantly increased as gestation progressed. In contrast, cardiac desaturase expression remained stable with time. Fatty acid synthase expression was greatest at day 65 in the liver, but was not expressed in the heart. Overall, the smallest fetus did not exhibit reduced tissue delta5- or delta6-desaturase expression or compromised polyunsaturated fatty acid status at any stage. In fact, small fetuses expressed more cardiac delta5-desaturase than their average-sized siblings, possibly in response to a stress to the heart. It is clear from this study that fatty acid metabolism changes markedly as gestation progresses, and reduced fatty acid supply does not cause inadequate growth in this porcine model of fetal development.
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Hunter MG, Brankin V, Quinn RL, Ferguson EM, Edwards SA, Ashworth CJ. Oocyte-somatic cell-endocrine interactions in pigs. Domest Anim Endocrinol 2005; 29:371-84. [PMID: 15950429 DOI: 10.1016/j.domaniend.2005.02.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2005] [Indexed: 10/25/2022]
Abstract
Oocyte-somatic cell communication is bi-directional and essential for both oocyte and follicular granulosa and theca cell function and development. We have shown that the oocyte secretes factors that stimulate porcine granulosa cell proliferation in serum-free culture, and suppress progesterone production, thereby preventing premature luteinisation. Possible candidates for mediating some of these effects are the bone morphogenetic proteins (BMPs) that belong to the transforming growth factor beta family. They are emerging as a family of proteins critical for fertility and ovulation rate in several mammals, and they are expressed in various cell types in the ovary. We have evidence for a functional BMP system in the porcine ovary and BMP receptors are present in the egg nests in the fetal ovary and in the granulosa cells, oocytes and occasional theca cells throughout subsequent development. In addition to paracrine interactions in the ovary, the porcine oocyte and its developmental potential can also be influenced by nutritional manipulation in vivo. We have demonstrated that feeding a high plane of nutrition to gilts for 19 days prior to ovulation increased oocyte quality compared to control animals fed a maintenance diet, as determined by oocyte maturation in vitro. This was associated with a number of changes in circulating reproductive and metabolic hormones and also in the follicular fluid in which the oocyte is nurtured. Further studies showed a similar increase in prenatal survival on Day 30 of gestation, demonstrating a direct link between oocyte quality/maturation and embryo survival. Collectively, these studies emphasise the importance of the interactions that occur between the oocyte and somatic cells and also with endocrine hormones for ovarian development, and ultimately for the production of oocytes with optimal developmental potential.
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Finch AM, Yang LG, Nwagwu MO, Page KR, McArdle HJ, Ashworth CJ. Placental transport of leucine in a porcine model of low birth weight. Reproduction 2004; 128:229-35. [PMID: 15280562 DOI: 10.1530/rep.1.00193] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Low birth weight is a major factor in neonatal morbidity and mortality in humans and domestic species and is a predictor of physiological disorders in adulthood. This study utilised the naturally occurring variation in pig fetal size within a uterus to test the hypothesis that placental amino acid transport capability is associated with fetal growth. Leucine uptake by trophoblast vesicles prepared from placentas supplying an average-sized fetus and the smallest fetus in the uterus was assessed. On days 45 and 65 of gestation, uptake of leucine by the porcine placenta was predominantly sodium independent and was inhibited by the non-metabolised leucine analogue 2-amino-2-norbornane-carboxylic acid, indicating that uptake occurs via system L. By day 100 the uptake of leucine by placentas supplying average-sized fetuses had changed from being predominantly sodium independent to involving both sodium-dependent (system B0) and -independent (system L) pathways. This change was not seen in placentas supplying the smallest fetus, which continued to display predominantly sodium-independent uptake. In conclusion, these data show gestational- and fetal size-dependent changes in the transport of leucine across the porcine placenta.
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Finch AM, Antipatis C, Pickard AR, Ashworth CJ. Patterns of fetal growth within Large White x Landrace and Chinese Meishan gilt litters at three stages of gestation. Reprod Fertil Dev 2004; 14:419-25. [PMID: 12617785 DOI: 10.1071/rd01131] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Low birthweight piglets have an increased incidence of mortality and morbidity. As there are few opportunities to remedy the detrimental consequences of low birthweight after birth, it is important to understand the nature of fetal growth retardation and to identify when low birthweight fetuses deviate from the growth trajectory of their normally grown siblings. The aims of this study were to identify the nature, timing and possible causal factors influencing inadequate fetal growth in Large White x Landrace (LW) and Chinese Meishan (MS) gilts at three stages of pregnancy. Thirty-six per cent of litters contained inadequately grown fetuses. Both intrauterine-growth-restricted (IUGR) and small-for-gestational-age (SGA) fetuses could be identified as early as Day 30 in MS and LW litters and the percentage of litters containing inadequately grown fetuses was similar throughout gestation. MS fetuses, placentas and piglets had less within-litter variation in weight at all stages studied. Inverse relationships were observed between litter size and both minimum and mean weights of MS neonates. No other relationships between fetal size and either uterine position or litter size were observed.
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Ferguson EM, Ashworth CJ, Edwards SA, Hawkins N, Hepburn N, Hunter MG. Effect of different nutritional regimens before ovulation on plasma concentrations of metabolic and reproductive hormones and oocyte maturation in gilts. Reproduction 2003; 126:61-71. [PMID: 12814348 DOI: 10.1530/rep.0.1260061] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This study examined the effect of feeding either a maintenance (1.35 kg day(-1)) or high (3.5 kg day(-1)) plane of nutrition for 19 days after oestrus on oocyte maturity and both reproductive and metabolic hormone concentrations in gilts. Blood samples were collected each day from oestrus until slaughter on day 19 and during two pulse bleeds (15 min samples for 8 h) conducted on day 12 and day 18. After slaughter, oocytes were recovered from the presumed ovulatory population of follicles, matured in vitro for 46+/-2 h with 10% of their own follicular fluid, and then fixed and stained to determine the stage of nuclear maturation of the oocyte. Gilts fed the high diet had a higher proportion of oocytes that reached metaphase II than gilts fed the maintenance diet (88.3+/-2.71% versus 68.2+/-6.48%; P=0.013). Circulating concentrations of insulin-like growth hormone I (IGF-I) and the number of LH pulses were lower (P<0.05) in gilts fed the maintenance diet compared with gilts fed the high diet on day 12 and day 18. Mean oestradiol and progesterone concentrations were higher (P<0.05) for gilts fed the maintenance diet compared with gilts fed the high diet. Leptin concentrations were also higher on day 19 in gilts fed the high diet (2.16+/-0.26 ng ml(-1) (n=9) versus 3.20+/-0.32 (n=11), P=0.025). The results of this study indicate that improved oocyte quality (increased proportion of oocytes that reached metaphase II) is associated with a number of changes in reproductive and metabolic hormones. Further studies are required to indicate which hormonal mechanism may, in turn, lead to increased embryo survival and eventual litter size.
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Page KR, Ashworth CJ, McArdle HJ, Finch AM, Nwagwu MO. Sodium transport across the chorioallantoic membrane of porcine placenta involves the epithelial sodium channel (ENaC). J Physiol 2003; 547:849-57. [PMID: 12562966 PMCID: PMC2342719 DOI: 10.1113/jphysiol.2002.031153] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2002] [Accepted: 01/02/2003] [Indexed: 11/08/2022] Open
Abstract
The properties of chorioallantoic membrane derived from Large White Landrace sows at 45, 65 and 100 days gestation are examined. Under short circuit conditions positive charge flows from fetal to maternal sides of the tissue. Na+ is shown to be the sole charge carrier as the short circuit current is inhibited reversibly by fetal applications of amiloride and replacement of Na+ by choline in the Ringer solution, and irreversibly by both fetal and maternal applications of ouabain. The initial short circuit current is smaller at day 100 compared to days 45 and 65. The dose responses to amiloride indicate that the epithelial sodium channel (ENaC) is involved in the movement of Na+ and that it is accessible on the fetal side of the tissue only. Immunostaining shows that the ENaC-alpha subunit is present in both the allantoic membrane and the trophoblast. Uptake studies using microvillous (apical) membrane vesicles suggest it is either inactive or only weakly active at this site. The trophoblast at day 100 has a higher content of ENaC than at days 45 and 65. This is the first report of the presence of ENaC in placental tissues. The effects of ouabain indicate the presence of a Na+ pump that is more readily inhibited by applications of the drug on the maternal aspect of the tissue than on the fetal side. Differential mechanisms may be present that would allow net movement of Na+ in either direction across the chorioallantoic membrane according to the changing demands of the developing fetus.
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Pickard AR, Miller SJ, Ashworth CJ. Synchronous onset of oestradiol-17beta secretion by Meishan conceptuses. Reprod Biol Endocrinol 2003; 1:16. [PMID: 12646060 PMCID: PMC151789 DOI: 10.1186/1477-7827-1-16] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2003] [Accepted: 02/11/2003] [Indexed: 11/21/2022] Open
Abstract
The response of Meishan conceptuses to an exogenous precursor for oestradiol-17beta biosynthesis was investigated in vitro, to determine whether gestational age or morphological stage of development elicit changes in hormone metabolism. Conceptuses were recovered on days 11, 12, 13 or 15 after the onset of oestrus and cultured for 6 hours at 37 degrees C, in the presence or absence of testosterone. On days 12 and 13 after the onset of oestrus spherical conceptuses were recovered from some gilts, whereas others yielded elongated or filamentous conceptuses. All conceptuses recovered on day 15 after oestrus had elongated. The number of cells per individual conceptus increased from days 11 to 13 after the onset of oestrus (P < 0.001), as did conceptus surface area (P = 0.038). Supplementing culture media with testosterone, as a substrate for oestrogen biosynthesis, significantly increased conceptus oestradiol-17beta secretion in vitro on days 12, 13 and 15, regardless of whether pre- or post-elongation conceptuses were cultured. However, on day 11 oestradiol-17beta was only detected at significant concentrations in the culture media of four testosterone supplemented conceptuses and only one gilt produced conceptuses capable of secreting oestradiol-17beta in the absence of testosterone. Therefore, the onset of conceptus oestradiol-17beta secretion is apparently limited by the expression of aromatase enzymes that are activated synchronously, irrespective of the stage of morphological development, within Meishan litters. Once established, Meishan conceptus oestradiol-17beta secretion in vitro is increased in the presence of exogenous testosterone.
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McEvoy TG, Ashworth CJ, Rooke JA, Sinclair KD. Consequences of manipulating gametes and embryos of ruminant species. REPRODUCTION (CAMBRIDGE, ENGLAND). SUPPLEMENT 2003; 61:167-82. [PMID: 14635934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
During the past 12 years, ruminants have provided a focus for some significant advances in mammalian reproductive biotechnologies. Lambs were the first offspring generated after nuclear transfer of fetal or adult cells to enucleated oocytes, and many calves of pre-determined gender are today the result of commercialized semen sexing. In 1990, the birth of one calf provided living proof that even 'dead' spermatozoa can be paternal, whereas, more recently, a short-lived gaur calf and viable mouflon lamb represented a novel option for conservation of endangered species. As well as highlights, hazards have emerged, resulting in setbacks or developmental anomalies, such as those associated with the large offspring syndrome which encompasses a range of adverse fetal, placental and post-natal phenomena expressed in ruminants. In this review, the developmental and other consequences of applying manipulative procedures, such as assisted fertilization, semen sexing, cloning and gene transfer, to gametes and embryos from bovine, ovine and caprine species are considered. Although assisted fertilization techniques can overcome mammalian infertility, they also usurp natural gamete selection safeguards, but not always with impunity. In the case of manipulations such as cloning, and to a lesser extent gene transfer, it is evident that nuclear-cytoplasmic interactions and nuclear-mitochondrial DNA interdependences are at least partially damaged or destroyed with a view to reconstruction. Therefore, among surviving zygotes and embryos it is inevitable that the legacy is frequently one of altered genetic, epigenetic or cellular programmes and processes.
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Ashworth CJ, Finch AM, Page KR, Nwagwu MO, McArdle HJ. Causes and consequences of fetal growth retardation in pigs. REPRODUCTION (CAMBRIDGE, ENGLAND) SUPPLEMENT 2002; 58:233-46. [PMID: 11980193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
In pigs, as in other species, fetal growth retardation is associated with reduced birth weight and increased risk of fetal and neonatal death. As there are few opportunities after birth to remedy the detrimental effects of low birth weight, it is important to understand both the intrinsic and extrinsic factors associated with inadequate fetal growth and to determine when growth retarded fetuses deviate from the growth trajectory of their normal sized littermates. Inadequately grown pig fetuses can be identified statistically as early as day 30 of the 114 days of gestation, indicating that limited uterine space is not a primary determinant of fetal growth. Comparisons of the smallest fetus within a litter with a normal sized sibling reveal that inadequately grown fetuses have altered endocrine status and lower circulating concentrations of many essential amino acids. In addition, the placenta supplying the smallest fetus is disproportionately small and has a reduced capacity to transport amino acids. Understanding the timing and the causes of fetal growth retardation in pigs may help us to devise appropriate strategies to reduce the incidence and hence the detrimental postnatal consequences of runting.
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Antipatis C, Ashworth CJ, Riley SC, Hannah L, Hoggard N, Lea RG. Vitamin A deficiency during rat pregnancy alters placental TNF-alpha signalling and apoptosis. Am J Reprod Immunol 2002; 47:151-8. [PMID: 12069200 DOI: 10.1034/j.1600-0897.2002.1o049.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
PROBLEM Vitamin A is important for immune function and deficiency is associated with adverse pregnancy outcome. In the rat, vitamin A deficiency reduces both foetal number and neonatal survival. The role of the placenta is uncertain. The effects of maternal vitamin A deficiency on placental cytokines and apoptosis have been investigated. METHOD OF STUDY Pregnant rats were fed either control or vitamin A free (VAF) diets (n = 4/group) from 8 weeks prior to and throughout pregnancy. Day 20 placentas from viable foetuses were examined for immunoexpression of (a) cytokines: tumour necrosis factor-alpha (TNF-alpha), TNFR1 receptor (p55), leptin and leptin receptor, (b) apoptosis: TdT-mediated dUTP nick end-labelling (TUNEL) positive cells, bax and bcl-2. RESULTS Placentas from VAF rats, but not controls, exhibited an infiltrate of neutrophils positive for TNF-alpha and leptin. The number of TNFR1 (p55) and TUNEL positive trophoblast cells was increased specifically in areas of neutrophil infiltration. Trophoblast giant cells in VAF placentas exhibited reduced bax but no change in bcl-2. CONCLUSIONS Maternal vitamin A deficiency is associated with abnormal placental apoptosis induced by neutrophil derived TNF-alpha acting through the TNFR1 (p55) and/or a change in the bcl-2/bax ratio in the trophoblast giant cells. These changes may underlie the effects of vitamin A deficiency on foetal development.
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Abstract
Vitamins and minerals serve essential roles in cellular metabolism, maintenance and growth throughout life. They are also central components of many enzymes and transcription factors. However, the need for optimum amounts of key micronutrients at critical stages during the periovulatory period and subsequent embryonic and fetal life has become the focus of sustained research activity only recently. In addition to folic acid, the minerals zinc, iron and copper and the antioxidant vitamins A and E are of particular importance during pregnancy. Both excesses and deficiencies of these micronutrients can have profound and sometimes persistent effects on many fetal tissues and organs in the absence of clinical signs of deficiency in the mother. The consequences of micronutrient imbalance on the developing conceptus may not be apparent at the time of the nutritional insult, but may be manifest later in development. However, supplementary micronutrients provided later in gestation or during postnatal life cannot completely reverse the detrimental effects of earlier micronutrient imbalance. Importantly, deficiency of a specific micronutrient, such as zinc, during pregnancy can result in a greater incidence of fetal malformation and resorptions than general undernutrition. Given the range of micronutrients that affect development, the number of developmental stages susceptible to inappropriate micronutrient status and the diverse biochemical systems and types of tissue affected, it is challenging to propose a unifying hypothesis that could explain the effects of micronutrient imbalance on programming throughout gestation. Micronutrient imbalance can affect pregnancy outcome through alterations in maternal and conceptus metabolism, as a consequence of their essential role in enzymes and transcription factors and through their involvement in signal transduction pathways that regulate development. Micronutrient-induced disturbances in the balance between the generation of free oxygen radicals and the production of antioxidants that scavenge free radicals may provide an additional mechanistic explanation. The detrimental effects of many micronutrient deficiencies, particularly zinc and copper, can be alleviated by supplementary antioxidants, whereas deficiencies of antioxidant vitamins A and E are likely to reduce defence against free radical damage.
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