A genome-wide association study demonstrates significant genetic variation for fracture risk in Thoroughbred racehorses

Background: Thoroughbred racehorses are subject to non-traumatic distal limb bone fractures that occur during racing and exercise. Susceptibility to fracture may be due to underlying disturbances in bone metabolism which have a genetic cause. Fracture risk has been shown to be heritable in several species but this study is the first genetic analysis of fracture risk in the horse. Results: Fracture cases (n = 269) were horses that sustained catastrophic distal limb fractures while racing on UK racecourses, necessitating euthanasia. Control horses (n = 253) were over 4 years of age, were racing during the same time period as the cases, and had no history of fracture at the time the study was carried out. The horses sampled were bred for both flat and National Hunt (NH) jump racing. 43,417 SNPs were employed to perform a genome-wide association analysis and to estimate the proportion of genetic variance attributable to the SNPs on each chromosome using restricted maximum likelihood (REML). Significant genetic variation associated with fracture risk was found on chromosomes 9, 18, 22 and 31. Three SNPs on chromosome 18 (62.05 Mb – 62.15 Mb) and one SNP on chromosome 1 (14.17 Mb) reached genome-wide significance (p <0.05) in a genome-wide association study (GWAS). Two of the SNPs on ECA 18 were located in a haplotype block containing the gene zinc finger protein 804A (ZNF804A). One haplotype within this block has a protective effect (controls at 1.95 times less risk of fracture than cases, p = 1 × 10-4), while a second haplotype increases fracture risk (cases at 3.39 times higher risk of fracture than controls, p = 0.042). Conclusions: Fracture risk in the Thoroughbred horse is a complex condition with an underlying genetic basis. Multiple genomic regions contribute to susceptibility to fracture risk. This suggests there is the potential to develop SNP-based estimators for genetic risk of fracture in the Thoroughbred racehorse, using methods pioneered in livestock genetics such as genomic selection. This information would be useful to racehorse breeders and owners, enabling them to reduce the risk of injury in their horses

Arachidonic acid and DHA status in pregnant women is not associated with cognitive performance of their children at 4 or 6–7 years

Arachidonic acid (ARA) and DHA, supplied primarily from the mother, are required for early development of the central nervous system. Thus, variations in maternal ARA or DHA status may modify neurocognitive development. We investigated the relationship between maternal ARA and DHA status in early (11·7 weeks) or late (34·5 weeks) pregnancy on neurocognitive function at the age of 4 years or 6–7 years in 724 mother–child pairs from the Southampton Women’s Survey cohort. Plasma phosphatidylcholine fatty acid composition was measured in early and late pregnancy. ARA concentration in early pregnancy predicted 13 % of the variation in ARA concentration in late pregnancy (β=0·36, P&lt;0·001). DHA concentration in early pregnancy predicted 21 % of the variation in DHA concentration in late pregnancy (β=0·46, P&lt;0·001). Children’s cognitive function at the age of 4 years was assessed by the Wechsler Preschool and Primary Scale of Intelligence and at the age of 6–7 years by the Wechsler Abbreviated Scale of Intelligence. Executive function at the age of 6–7 years was assessed using elements of the Cambridge Neuropsychological Test Automated Battery. Neither DHA nor ARA concentrations in early or late pregnancy were associated significantly with neurocognitive function in children at the age of 4 years or the age of 6–7 years. These findings suggest that ARA and DHA status during pregnancy in the range found in this cohort are unlikely to have major influences on neurocognitive function in healthy children.</p

Characterisation of polyunsaturated fatty acid synthesis in peripheral blood mononuclear cells.

Conversion of the essential n-3 (18:3n-3) and n-6 (18:2n-6) fatty acids to longer chain polyunsaturated fatty acids (PUFA) involves sequential desaturation and elongation reactions. Previous studies have reported gender differences in n-3 PUFA synthesis, whereas the effect of age is less clear. n-3 PUFAs are reported to have important effects on immune cell function. A previous study reported long chain PUFA synthesis in mitogen stimulated but not quiescent peripheral blood mononuclear cells (PBMCs). However, the underlying mechanism is not known. PUFA synthesis was investigated in PBMCs incubated with [1-13C]18:3n-3 for 48 h. Activation with the T-lymphocyte mitogen concanavalin A (Con A) increased PUFA synthesis. 22:6n-3 synthesis was not detected. [1-13C] incorporation was greatest for 20:3n-3 suggesting initial chain elongation is an important fate for 18:3n-3. Con A increased expression of three key genes (FADS2, FADS1 and ELOVL5) involved in PUFA synthesis, suggesting upregulation of the pathway is controlled at the transcriptional level. ELOVL2 expression was negligible, possibly explaining the lack of 22:6n-3 synthesis. Con A increased methylation of 12 CpGs in the FADS2 promoter contradicting the general view that DNA methylation represses transcription. Subsequent 5’RACE analysis verified that activated PBMCs were not using an alternative promoter for FADS2 transcription. Contrary to expectation, 18:3n-3 conversion in activated PBMCs was not affected by gender or menopausal status and there was no clear age effect. PUFA synthesis was constitutive in the Jurkat T-lymphocyte leukaemic cell-line and was higher than in PBMCs. FADS2, FADS1 and ELOVL5 mRNA expression was also higher in Jurkat cells and was associated with 50% lower methylation of 17 CpGs in the FADS2 promoter, suggesting transcriptional dysregulation of PUFA synthesis in Jurkat cells involves altered DNA methylation. These findings have provided novel insights into the regulation of PUFA biosynthesis in PBMCs and upregulation of the pathway in activated PBMCs suggests that newly synthesised PUFAs may be important for cell function

Characterisation of polyunsaturated fatty acid synthesis in peripheral blood mononuclear cells.

Conversion of the essential n-3 (18:3n-3) and n-6 (18:2n-6) fatty acids to longer chain polyunsaturated fatty acids (PUFA) involves sequential desaturation and elongation reactions. Previous studies have reported gender differences in n-3 PUFA synthesis, whereas the effect of age is less clear. n-3 PUFAs are reported to have important effects on immune cell function. A previous study reported long chain PUFA synthesis in mitogen stimulated but not quiescent peripheral blood mononuclear cells (PBMCs). However, the underlying mechanism is not known. PUFA synthesis was investigated in PBMCs incubated with [1-13C]18:3n-3 for 48 h. Activation with the T-lymphocyte mitogen concanavalin A (Con A) increased PUFA synthesis. 22:6n-3 synthesis was not detected. [1-13C] incorporation was greatest for 20:3n-3 suggesting initial chain elongation is an important fate for 18:3n-3. Con A increased expression of three key genes (FADS2, FADS1 and ELOVL5) involved in PUFA synthesis, suggesting upregulation of the pathway is controlled at the transcriptional level. ELOVL2 expression was negligible, possibly explaining the lack of 22:6n-3 synthesis. Con A increased methylation of 12 CpGs in the FADS2 promoter contradicting the general view that DNA methylation represses transcription. Subsequent 5’RACE analysis verified that activated PBMCs were not using an alternative promoter for FADS2 transcription. Contrary to expectation, 18:3n-3 conversion in activated PBMCs was not affected by gender or menopausal status and there was no clear age effect. PUFA synthesis was constitutive in the Jurkat T-lymphocyte leukaemic cell-line and was higher than in PBMCs. FADS2, FADS1 and ELOVL5 mRNA expression was also higher in Jurkat cells and was associated with 50% lower methylation of 17 CpGs in the FADS2 promoter, suggesting transcriptional dysregulation of PUFA synthesis in Jurkat cells involves altered DNA methylation. These findings have provided novel insights into the regulation of PUFA biosynthesis in PBMCs and upregulation of the pathway in activated PBMCs suggests that newly synthesised PUFAs may be important for cell function

Effect of sex hormones on n-3 polyunsaturated fatty acid biosynthesis in HepG2 cells and in human primary hepatocytes

Female humans and rodents have been shown to have higher 22:6n-3 status and synthesis than males. It is unclear which sex hormone is involved. We investigated the specificity of the effects of physiological concentrations of sex hormones in vitro on the mRNA expression of genes involved in polyunsaturated fatty acid (PUFA) biosynthesis and on the conversion of [d5]-18:3n-3 to longer chain fatty acids. Progesterone, but not 17?-ethynylestradiol or testosterone, increased FADS2, FADS1, ELOVl 5 and ELOVl 2 mRNA expression in HepG2 cells and in primary human hepatocytes. In HepG2 cells, these changes were accompanied by hypomethylation of specific CpG loci in the FADS2 promoter. Progesterone, but not 17?-ethynylestradiol or testosterone, increased conversion of [d5]-18:3n-3 to 20:5n-3, 22:5n-3 and 22:6n-3. These findings show that progesterone increases n-3 PUFA biosynthesis by up-regulating the mRNA expression of genes involved in this pathway, possibly via changes in the epigenetic regulation of FADS

Polyunsaturated fatty acid synthesis de novo is required for calcium release in vascular smooth muscle

<p>Previous studies show that inhibition of delta-5 desaturase and delta-6 causes a<br>decrease in phenylepherine (PE)- induced vasoconstriction in human femoral artery,<br>and in rat aorta and mesenteric arteries. These data showed that the activity of the<br>polyunsaturated fatty acid (PUFA) biosynthesis pathway related to vasoconstriction is<br>specifically located in vascular smooth muscle (VSM). The study also showed that<br>inhibiting the PUFA-biosynthesis pathway causes a decrease in the release of the proconstriction<br>eicosanoids prostaglandin (PG) F2 alpha, PGE2 and thromboxane A2 (1).<br>Activity of the PUFA biosynthesis pathway has previously been shown in arterial<br>endothelial (2) and smooth muscle cells (3). However, there is no direct evidence of the<br>exact extent of the pathway and contribution of PUFA biosynthesis to vascular function<br>in VSM is currently unknown.</p

Vegetarian diet during pregnancy is not associated with poorer cognitive performance in children at age 6-7 years

Compared with omnivorous mothers, vegetarian mothers have lower intakes of some nutrients required for neurological development. However, there is a lack of information about the impact of vegetarianism during pregnancy on subsequent cognitive function in children. The aim of this study was to investigate whether vegetarianism during pregnancy is associated with altered maternal nutritional status and with cognitive function in children at six to seven years of age. Women aged 20–34 years participating in a prospective observational study who provided dietary data and blood samples in early pregnancy (11 weeks; 78 vegetarians and 2144 omnivores) or late pregnancy (34 weeks; 91 vegetarians and 2552 omnivores). Compared with omnivorous women, vegetarian women had lower blood concentrations of arachidonic acid, docosahexaenoic acid, and cobalamin in early and late pregnancy. Vegetarianism in pregnancy was linked to higher maternal educational attainment, longer breastfeeding duration, lower incidence of smoking during pregnancy and a tendency towards higher IQ in the mothers. Concentrations of some nutrients required for neurodevelopment were lower in maternal blood during gestation; however, after controlling for confounders consuming a vegetarian diet during pregnancy was not associated with poorer neurocognitive development of the children in this study

data_sheet_1.PDF

<p>Polyunsaturated fatty acids (PUFAs) are important for immune function. Limited evidence indicates that immune cell activation involves endogenous PUFA synthesis, but this has not been characterised. To address this, we measured metabolism of 18:3n-3 in quiescent and activated peripheral blood mononuclear cells (PBMCs), and in Jurkat T cell leukaemia. PBMCs from men and women (n = 34) were incubated with [1-¹³C]18:3n-3 with or without Concanavalin A (Con. A). 18:3n-3 conversion was undetectable in unstimulated PBMCs, but up-regulated when stimulated. The main products were 20:3n-3 and 20:4n-3, while 18:4n-3 was undetectable, suggesting initial elongation and Δ8 desaturation. PUFA synthesis was 17.4-fold greater in Jurkat cells than PBMCs. The major products of 18:3n-3 conversion in Jurkat cells were 20:4n-3, 20:5n-3, and 22:5n-3. ¹³C Enrichment of 18:4n-3 and 20:3n-3 suggests parallel initial elongation and Δ6 desaturation. The FADS2 inhibitor SC26196 reduced PBMC, but not Jurkat cell, proliferation suggesting PUFA synthesis is involved in regulating mitosis in PBMCs. Con. A stimulation increased FADS2, FADS1, ELOVL5 and ELOVL4 mRNA expression in PBMCs. A single transcript corresponding to the major isoform of FADS2, FADS20001, was detected in PBMCs and Jurkat cells. PBMC activation induced hypermethylation of a 470bp region in the FADS2 5′-regulatory sequence. This region was hypomethylated in Jurkat cells compared to quiescent PBMCs. These findings show that PUFA synthesis involving initial elongation and Δ8 desaturation is involved in regulating PBMC proliferation and is regulated via transcription possibly by altered DNA methylation. These processes were dysregulated in Jurkat cells. This has implications for understanding the regulation of mitosis in normal and transformed lymphocytes.</p

Arachidonic and docosahexaenoic acid status in pregnant women is not associated with cognitive performance of their children at 4 or 6 - 7 years

Arachidonic (ARA) and docosahexaenoic (DHA) acids, supplied primarily from the mother, are required for early development of the central nervous system. Thus, variations in maternal ARA or DHA status may modify neurocognitive development. We investigated the relationship between maternal ARA and DHA status in early (11.7 wk) or late (34.5 wk) pregnancy on neurocognitive function at age 4 y or 6-7 y in 724 mother-child pairs from the Southampton Women’s Survey cohort. Plasma phosphatidylcholine fatty acid composition was measured in early and late pregnancy. ARA concentration in early pregnancy predicted 13% of the variation in ARA concentration in late pregnancy (β = 0.36, P &lt; 0.001). DHA concentration in early pregnancy predicted 21% of the variation in DHA concentration in late pregnancy (β = 0.46, P &lt; 0.001). Children’s cognitive function at age 4 y was assessed by the Wechsler Preschool and Primary Scale of Intelligence and at age 6-7 y by the Wechsler Abbreviated Scale of Intelligence. Executive function at age 6-7 y was assessed using elements of the Cambridge Neuropsychological Test Automated Battery. Neither DHA nor ARA concentrations in early or late pregnancy were associated significantly with neurocognitive function in children at age 4 y or age 6-7 y. These findings suggest that ARA and DHA status during pregnancy in the range found in this cohort are unlikely to have major influences on neurocognitive function in healthy children