R G Snell

University of Auckland, Окленд, Auckland, New Zealand

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Publications (59)402.05 Total impact

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    ABSTRACT: The objective of this study was to estimate heritability and crossbreeding parameters (breed and heterosis effects) of various fatty acid (FA) concentrations in milk fat of New Zealand dairy cattle. For this purpose, calibration equations to predict concentration of each of the most common FAs were derived with partial least squares (PLS) using mid-infrared (MIR) spectral data from milk samples (n=850) collected in the 2003-04 season from 348 second-parity crossbred cows during peak, mid and late lactation. The milk samples produced both, MIR spectral data and concentration of the most common FAs determined using gas chromatography (GC). The concordance correlation coefficients (CCC) between the concentration of a FA determined by GC and the PLS equation ranged from 0·63 to 0·94, suggesting that some prediction equations can be considered to have substantial predictive ability. The PLS calibration equations were then used to predict the concentration of each of the fatty acids in 26 769 milk samples from 7385 cows that were herd-tested during the 2007-08 season. Data were analysed using a single-trait repeatability animal model. Shorter chain FA (16 : 0 and below) were significantly higher (P<0·05) in Jersey cows, while longer chain, including unsaturated longer chain FA were higher in Holstein-Friesian cows. The estimates of heritabilities ranged from 0·17 to 0·41 suggesting that selective breeding could be used to ensure milk fat composition stays aligned to consumer, market and manufacturing needs.
    Journal of Dairy Research 08/2014; 81(3):340-9. · 1.34 Impact Factor
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    ABSTRACT: Insidious changes in behaviour herald the onset of progressive neurodegenerative disorders such as Huntington's disease (HD), sometimes years before overt symptoms are seen. Sleep and circadian disturbances are particularly disruptive symptoms in patients with neurological disorders, but they are difficult to measure in humans. Here we studied circadian behaviour in transgenic HD sheep expressing the full-length human huntingtin protein with an expanded CAG repeat mutation in the juvenile range. Young HD sheep with no other symptoms exhibited circadian behavioural abnormalities that worsened with age. The most obvious change was a disturbed evening behaviour reminiscent of 'sundowning' that is seen in some patients with dementia. There were no structural abnormalities seen with MRI, even in 5-year-old HD sheep. Interestingly, detection of the circadian abnormalities depended upon their social grouping. Abnormalities emerged in sheep kept in an 'HD-only' flock, whereas the behaviour of HD sheep kept mixed with normal sheep was relatively normal. Sleep-wake abnormalities in HD patients are also likely to be hidden, and may precede overt symptoms by many years. Sleep disruption has deleterious effects, even in normal people. The knock-on effects of sleep-wake disturbance may exacerbate, or even cause symptoms such as irritability and depression that are common in early stage HD patients. HD sheep will be useful models for probing the mechanisms underlying circadian behavioural disorder in HD.
    Human Molecular Genetics 01/2014; · 7.69 Impact Factor
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    ABSTRACT: Milk is composed of a complex mixture of lipids, proteins, carbohydrates and various vitamins and minerals as a source of nutrition for young mammals. The composition of milk varies between individuals, with lipid composition in particular being highly heritable. Recent reports have highlighted a region of bovine chromosome 27 harbouring variants affecting milk fat percentage and fatty acid content. We aimed to further investigate this locus in two independent cattle populations, consisting of a Holstein-Friesian x Jersey crossbreed pedigree of 711 F2 cows, and a collection of 32,530 mixed ancestry Bos taurus cows. Bayesian genome-wide association mapping using markers imputed from the Illumina BovineHD chip revealed a large quantitative trait locus (QTL) for milk fat percentage on chromosome 27, present in both populations. We also investigated a range of other milk composition phenotypes, and report additional associations at this locus for fat yield, protein percentage and yield, lactose percentage and yield, milk volume, and the proportions of numerous milk fatty acids. We then used mammary RNA sequence data from 212 lactating cows to assess the transcript abundance of genes located in the milk fat percentage QTL interval. This analysis revealed a strong eQTL for AGPAT6, demonstrating that high milk fat percentage genotype is also additively associated with increased expression of the AGPAT6 gene. Finally, we used whole genome sequence data from six F1 sires to target a panel of novel AGPAT6 locus variants for genotyping in the F2 crossbreed population. Association analysis of 58 of these variants revealed highly significant association for polymorphisms mapping to the 5'UTR exons and intron 1 of AGPAT6. Taken together, these data suggest that variants affecting the expression of AGPAT6 are causally involved in differential milk fat synthesis, with pleiotropic consequences for a diverse range of other milk components.
    PLoS ONE 01/2014; 9(1):e85757. · 3.53 Impact Factor
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    ABSTRACT: Short-term changes to milking frequency can alter the metabolic status of dairy cows depending on the duration, magnitude, and stage of lactation at which the milking frequency changes occur. Additionally, effects of altered milking frequency that are subsequent to cows returning to a normal twice-daily (2×) milking regimen are not well established. This study tested the hypothesis that plasma concentrations of key hormones and metabolites and transcription of genes involved in the somatotropic axis and lipid metabolism would be altered in liver and subcutaneous adipose tissue from cows milked with different frequencies. Multiparous Holstein-Friesian dairy cows were allocated to 2× milking for the whole lactation, or once-(1×) or 3 times-(3×) daily milking for 3 or 6 wk, immediately postpartum, and then 2× milking for the remainder of the lactation. Liver and subcutaneous fat were biopsied at wk 1 (liver only), 3, 6, and 9 postpartum, and transcription of genes involved in the somatotropic axis and lipid metabolism were measured. At wk 3, cows milked 3× had lower hepatic expression of growth hormone receptor (GHR1A) compared with cows milked 2× or 1×, and lower IGF1 expression compared with cows milked 1×, indicating greater uncoupling of the somatotropic axis. At wk 6, reduced transcription of total GHR and GHR1B occurred in the adipose tissue of cows milked 3×. Cows milked 1× had greater transcription in adipose tissue of lipogenesis genes at wk 3 and 6, and lipolysis genes at wk 6, compared with cows milked 2×, indicating a period of increased fatty acid storage, followed by increased fatty acid reesterification. At wk 9, cows previously milked 3× for 6 wk maintained lower transcription of genes involved in lipogenesis, lipolysis, and ketolysis in adipose tissue compared with cows milked 2×, indicating that the effects of 3× milking persist for at least 3 wk after switching to 2× milking. Results indicate that alterations to milking frequency affect the transcription of genes involved in lipid mobilization and storage, enabling the animal to manage the energy demands associated with the change in milk production. Some of these gene transcription changes were maintained in cows previously milked 3×, indicating that the adipose tissue gene expression changes were still required even after 3 wk of the less-demanding 2× milking regimen.
    Journal of Dairy Science 01/2014; · 2.57 Impact Factor
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    ABSTRACT: Changes to milking frequency (MF) affect the metabolic and energetic status of dairy cows. However, the duration of altered MF necessary to modify hepatic transcription during early lactation is less clear. Additionally, long-term responses to short-term alterations in MF have not been established. Holstein-Friesian dairy cows (n = 120) were allocated to 3 or 6 wk of either once-daily (1×) or thrice-daily (3×) milking, immediately postpartum. Following treatment, cows were switched to twice-daily (2×) milking. These 4 treatment groups were compared with cows milked 2× (n = 30) for the whole lactation. Liver tissue was collected by biopsy at 1, 3, 6, and 9 wk postpartum from 12 cows per treatment, RNA was extracted, and transcript abundance of genes involved in hepatic metabolism was quantified. Milking frequency altered the expression of most of the genes measured; however, we observed no effects caused by the length of time on the alternative milking frequency and no interactions between MF and length. During the MF treatment, mRNA expression of some, but not all, genes involved in gluconeogenesis (G6PC, PCK1), fatty acid β-oxidation (CPT1A, CPT2), ketogenesis (HMGCS2), lipid transport (APOA1), and lipolysis (PNPLA2) were lower for cows milked 1× and plasma glucose and insulin concentrations were greater. Cows milked 3× had reduced mRNA expression for some of the genes involved in fatty acid synthesis (ACACA) and lipid transport (APOB) and had greater plasma NEFA concentrations at wk 1. At 9 wk postpartum, expression data indicated that cows previously milked 3× had a greater capacity for gluconeogenesis (PCK1), ketogenesis (HMGCS2), and urea cycling (ASL, CPS1) and lower glucose concentrations than cows previously milked 1×, because some of the genes involved in these processes were still altered. Milking cows 1× relative to 2×, however, did not result in significant carryover effects on the expression of the genes measured in this study, indicating that metabolic changes are not sustained beyond the period of reduced MF. Changes to MF altered the hepatic response during early lactation; however, this was not dependent on the duration of MF change. Although we observed only minimal carryover effects on hepatic metabolism from short periods of reduced MF postpartum, there may be long-term effects on urea cycling (ASL, CPS1) and ketogenesis (HMGCS2) when 3× milking occurs immediately postpartum.
    Journal of Dairy Science 12/2013; · 2.57 Impact Factor
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    ABSTRACT: Non-protein-bound oligosaccharides are important bioactive components of cow milk, with potential human-health benefits such as stimulation of the growth of beneficial gut bacteria and defense against pathogens. In bovine milk, the majority of oligosaccharides are sialylated; 3'-sialyllactose (3'-N-acetylneuraminyl-d-lactose; 3'-SL) is the predominant sialylated oligosaccharide, followed by 6'-sialyllactose (6'-N-acetylneuraminyl-d-lactose; 6'-SL). Both 3'-SL and 6'-SL have antimicrobial activity. As bovine milk products such as infant formula can be an important component of the human diet, and the concentrations of 3'-SL and 6'-SL are lower in bovine milk compared with human milk, we aimed to identify cows that naturally produce higher concentrations of sialyllactose in their milk. Milk from such cows could be used to produce foods with an increased sialyllactose content, potentially providing increased health benefits. We speculated that cows overexpressing 3'-SL and 6'-SL would exist at low frequency in the population and, to allow their efficient identification, we developed a novel assay for 3'-SL and 6'-SL utilizing flow-injection analysis-mass spectrometry, which could be used for high-throughput analysis of milk samples. We then determined 3'-SL and 6'-SL concentrations in milk samples from 15,507 cows from Friesian, Jersey, and Friesian-Jersey crossbred animals. We found 329 cows with concentrations of 3'-SL or 6'-SL >2-fold higher than the mean, 26 cows with concentrations of 3'-SL or 6'-SL >3-fold higher than the mean, and 1 cow with concentrations of 3'-SL >4-fold higher than the mean. Although these outliers were observed across the 3 groups of cows, breed had a strong effect on mean 3'-SL and 6'-SL concentrations.
    Journal of Dairy Science 10/2013; · 2.57 Impact Factor
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    ABSTRACT: The objective of this study was to investigate the effect of reduced milking frequency, at 2 feeding levels, on gene expression in adipose tissue of grazing dairy cows during early lactation. Multiparous Holstein-Friesian and Holstein-Friesian × Jersey cows (n = 120) were grazed on pasture and milked twice daily (2×) from calving to 34 ± 6 d in milk (mean ± standard deviation). Cows were then allocated to 1 of 4 treatments in a 2 × 2 factorial arrangement. Treatments consisted of 2 milking frequencies (2× or once daily; 1×) and 2 feeding levels for 3 wk: adequately fed (AF), consuming 14.3 kg of dry matter/cow per day, or underfed (UF), consuming 8.3 kg of dry matter/cow per day. After the treatment period, all cows were fed to target grazing residuals ≥1,600 kg of DM/cow per day and milked 2× for 20 wk. Adipose tissue was collected from 12 cows per treatment by subcutaneous biopsy at -1, 3, and 5 wk relative to treatment start, RNA was extracted, and transcript abundance of genes involved in lipid metabolism was quantified using a linear mixed model. At the end of the 3-wk treatment period, transcript abundance of genes involved in fatty acid (FA) uptake into adipose tissue (LPL), FA synthesis [FA synthase (FASN) and stearoyl-coenzyme A desaturase (SCD)], FA oxidation [acyl-coenzyme A synthetase long-chain family member 1 (ACSL1) and carnitine palmitoyltransferase 2 (CPT2)], glyceroneogenesis [glycerol-3-phosphate dehydrogenase 1 (GPD1) and pyruvate carboxylase (PC)], and triacylglyceride synthesis [diacylglycerol O-acyltransferase 2 (DGAT2)] were greater in AF1× cows compared with all other treatments. However, when cows were underfed, no effects of milking frequency were observed on transcript abundance of genes involved in adipose lipid metabolism. Despite increases in plasma NEFA concentrations in UF cows, no effects of underfeeding were observed on the transcription of lipolytic genes. At 5 wk, after cows were returned to 2× milking and standard feed allowance, transcript abundances of genes involved in FA synthesis [acetyl-coenzyme A carboxylase α (ACACA) and SCD)] were increased in cows previously UF. Expression of ACSL1 was decreased in UF1× cows relative to UF2× cows and CPT2 expression was greater in AF1× cows compared with AF2× cows. In conclusion, after 3 wk of reduced milking frequency during a feed restriction, transcription of genes involved in lipid metabolism in adipose tissue were not altered, possibly due to the reduced milk production in these animals. However, 3 wk of 1× milking in AF cows increased transcription of genes involved in FA synthesis, oxidation, and triacylglyceride synthesis.
    Journal of Dairy Science 10/2013; · 2.57 Impact Factor
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    ABSTRACT: The objective of this study was to investigate if a reduced milking frequency altered the effect of dietary energy restriction on the hepatic transcriptome of grazing dairy cows. Multiparous Holstein-Friesian and Holstein-Friesian x Jersey cows (n = 120) were milked twice-daily (2X) from calving until 34 ± 6 days in milk (mean ±SD). Cows were then allocated to one of four treatments in a 2 x 2 factorial arrangement. Treatments consisted of two milking frequencies (2X or once-daily; 1X) and two feeding levels for three weeks: adequately fed (AF), or underfed (UF; 60% of AF). Liver tissue was biopsied from 12 cows per treatment after 3 wk of treatment and the hepatic transcriptome profiled using an Agilent 4x44k bovine microarray. Over 2,900 genes were differentially expressed in response to the energy restriction; however, no effects resulted from changes to milking frequency. This may indicate that after 3wks of 1X milking, any changes to the liver transcriptome that may have occurred earlier have returned to normal. After 3 wk of energy restriction, gene expression patterns indicated that glucose-sparing pathways were activated, and gluconeogenesis was increased in UF cows. Genes involved in hepatic stress were up-regulated in response to the energy restriction indicative of the pressure energy restriction places on liver function. Other pathways up-regulated included 'Cytoskeletal remodeling' indicating that a three week energy restriction resulted in molecular changes to assist tissue remodeling. Overall, 1X milking does not modify the hepatic transcriptome changes that occur in response to an energy restriction.
    Physiological Genomics 10/2013; · 2.81 Impact Factor
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    ABSTRACT: Background: Huntington's disease is a neurodegenerative disorder, typically with clinical manifestations in adult years, caused by an expanded polyglutamine-coding repeat in HTT. There are no treatments that delay or prevent the onset or progression of this devastating disease. Objective and Methods: In order to study its pre-symptomatic molecular progression and provide a large mammalian model for determining natural history of the disease and for therapeutic testing, we generated and previously reported on lines of transgenic sheep carrying a full length human HTT cDNA transgene, with expression driven by a minimal HTT promoter. We report here further characterization of our preferred line, OVT73. Results: This line reliably expresses the expanded human huntingtin protein at modest, but readily detectable levels throughout the brain, including the striatum and cortex. Transmission of the 73 unit glutamine coding repeat was relatively stable over three generations. At the first time-point of a longitudinal study, animals sacrificed at 6 months (7 transgenic, 7 control) showed reduced striatum GABA A 1 receptor, and globus pallidus leu-enkephalin immunoreactivity. Two of three 18 month old animals sacrificed revealed cortical neuropil aggregates. Furthermore, neuronal intranuclear inclusions were identified in the piriform cortex of a single 36 month old animal in addition to cortical neuropil aggregates. Conclusions: Taken together, these data indicate that the OVT73 transgenic sheep line will progressively reveal early HD pathology and allow therapeutic testing over a period of time relevant to human patients.
    JHD. 09/2013; 2:279-295.
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    ABSTRACT: The aim of this study was to determine a genetic basis for IgA concentration in milk of Bos taurus. We used a Holstein-Friesian x Jersey F2 crossbred pedigree to undertake a genome-wide search for QTL influencing IgA concentration and yield in colostrum and milk. We identified a single genome-wide significant QTL on chromosome 16, maximising at 4.8 Mbp. The polymeric immunoglobulin receptor gene (PIGR) was within the confidence interval of the QTL. In addition, mRNA expression analysis revealed a liver PIGR expression QTL mapping to the same locus as the IgA quantitative trait locus. Sequencing and subsequent genotyping of the PIGR gene revealed three divergent haplotypes that explained the variance of both the IgA QTL and the PIGR expression QTL. Genetic selection based on these markers will facilitate the production of bovine herds producing milk with higher concentrations of IgA.
    PLoS ONE 01/2013; 8(3):e57219. · 3.53 Impact Factor
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    ABSTRACT: The liver and the mammary gland have complementary metabolic roles during lactation. Glucose synthesized by the liver is released into the circulation and is taken up by the mammary gland where major metabolic products of glucose include milk sugar (lactose) and the glycerol backbone of milk fat (triglycerides). Hepatic synthesis of glucose is often accompanied by β-oxidation in that organ to provide energy for glucose synthesis, while mammary gland synthesizes rather than oxidizes fat during lactation. We have therefore compared enzyme abundances between the liver and mammary gland of lactating Friesian cows where metabolic output is well established. Quantitative differences in protein amount were assessed using two-dimensional differential in-gel electrophoresis. As predicted, the abundances of enzymes catalysing gluconeogenesis and β-oxidation were greatest in the liver, and enzyme abundances in mammary tissue were consistent with fat synthesis rather than β-oxidation.
    Journal of proteomics 04/2012; 75(14):4429-35. · 5.07 Impact Factor
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    ABSTRACT: We defined the genetic landscape of balanced chromosomal rearrangements at nucleotide resolution by sequencing 141 breakpoints from cytogenetically interpreted translocations and inversions. We confirm that the recently described phenomenon of 'chromothripsis' (massive chromosomal shattering and reorganization) is not unique to cancer cells but also occurs in the germline, where it can resolve to a relatively balanced state with frequent inversions. We detected a high incidence of complex rearrangements (19.2%) and substantially less reliance on microhomology (31%) than previously observed in benign copy-number variants (CNVs). We compared these results to experimentally generated DNA breakage-repair by sequencing seven transgenic animals, revealing extensive rearrangement of the transgene and host genome with similar complexity to human germline alterations. Inversion was the most common rearrangement, suggesting that a combined mechanism involving template switching and non-homologous repair mediates the formation of balanced complex rearrangements that are viable, stably replicated and transmitted unaltered to subsequent generations.
    Nature Genetics 03/2012; 44(4):390-7, S1. · 35.21 Impact Factor
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    ABSTRACT: Animal growth relative to food energy input is of key importance to agricultural production. Several recent studies highlighted genetic markers associated with food conversion efficiency in beef cattle, and there is now a requirement to validate these associations in additional populations and to assess their potential utility for selecting animals with enhanced food-use efficiency. The current analysis tested a population of dairy cattle using 138 DNA markers previously associated with food intake and growth in a whole-genome association analysis of beef animals. Although seven markers showed point-wise significance at P < 0.05, none of the single-nucleotide polymorphisms tested were significantly associated with food conversion efficiency after correction for multiple testing. These data do not support the involvement of this subset of previously implicated markers in the food conversion efficiency of the physiologically distinct New Zealand Holstein-Friesian dairy breed.
    Animal Genetics 02/2012; 43(6):781-4. · 2.58 Impact Factor
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    ABSTRACT: Variation at the pleiomorphic adenoma gene 1 (PLAG1) locus has recently been implicated in the regulation of stature and weight in Bos taurus. Using a population of 942 outbred Holstein-Friesian dairy calves, we report confirmation of this effect, demonstrating strong association of early life body weight with PLAG1 genotype. Peripubertal body weight and growth rate were also significantly associated with PLAG1 genotype. Growth rate per kilogram of body weight, daily feed intake, gross feed efficiency and residual feed intake were not significantly associated with PLAG1 genotype. This study supports the status of PLAG1 as a key regulator of mammalian growth. Further, the data indicate the utility of PLAG1 polymorphisms for the selection of animals to achieve enhanced weight gain or conversely to aid the selection of animals with lower mature body weight and thus lower maintenance energy requirements.
    Animal Genetics 12/2011; 43(5):591-4. · 2.58 Impact Factor
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    ABSTRACT: To identify quantitative trait loci (QTL) affecting the concentration of beta-lactoglobulin in milk, and to evaluate the effect of beta-lactoglobulin genetic variants on the concentration of fat, protein and casein in bovine milk. A herd of 850 F2 Holstein-Friesian x Jersey crossbred cows was produced through mating six Holstein-Friesian x Jersey F1 bulls of high genetic merit with F1 cows from the national herd. A total of 1,610 herd-test records from 556 second-parity crossbreds were analysed. The concentration of fat, protein and casein in milk was measured at peak, mid- and late lactation, during the production seasons of 2003-2004 and 2004-2005. Liveweight was measured daily. DNA from the F2 animals, their F1 dams and sires, and selected grandsires was genotyped across the genome, initially with 285 microsatellite markers, and subsequently with 6,634 single nucleotide polymorphisms (SNP). A highly significant QTL for the concentration of beta-lactoglobulin in milk was identified, which coincided with the position of the beta-lactoglobulin gene on bovine Chromosome 11. No other consistently significant QTL for the concentration of beta-lactoglobulin in milk were detected. Cows with the BB beta-lactoglobulin genotype produced milk with a 30% lower concentration of beta-lactoglobulin than cows with the AA genotype. The beta-lactoglobulin polymorphism also explained variation in the proportion of casein in total protein. In addition, the percentage of fat was higher for BB than AA animals, whereas the percentage of total protein, mean daily milk yield and liveweight did not differ between AA and BB animals. A significant QTL determining the concentration of beta-lactoglobulin in milk was identified. Selection of animals for the beta-lactoglobulin B-allele may enable the production of milk naturally enriched for casein, thus allowing a potential increase in the yield of cheese. There may be additional future value in production of bovine milk more like human milk, where decreasing the concentration of beta-lactoglobulin is desirable.
    New Zealand veterinary journal 02/2010; 58(1):1-5. · 1.06 Impact Factor
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    ABSTRACT: Huntington's disease (HD) is an inherited autosomal dominant neurodegenerative disorder caused by an expansion of a CAG trinucleotide repeat in the huntingtin (HTT) gene [Huntington's Disease Collaborative Research Group (1993) A novel gene containing a trinucleotide repeat that is expanded and unstable on Huntington's disease chromosomes. The Huntington's Disease Collaborative Research Group. Cell, 72, 971-983]. Despite identification of the gene in 1993, the underlying life-long disease process and effective treatments to prevent or delay it remain elusive. In an effort to fast-track treatment strategies for HD into clinical trials, we have developed a new large-animal HD transgenic ovine model. Sheep, Ovis aries L., were selected because the developmental pattern of the ovine basal ganglia and cortex (the regions primarily affected in HD) is similar to the analogous regions of the human brain. Microinjection of a full-length human HTT cDNA containing 73 polyglutamine repeats under the control of the human promotor resulted in six transgenic founders varying in copy number of the transgene. Analysis of offspring (at 1 and 7 months of age) from one of the founders showed robust expression of the full-length human HTT protein in both CNS and non-CNS tissue. Further, preliminary immunohistochemical analysis demonstrated the organization of the caudate nucleus and putamen and revealed decreased expression of medium size spiny neuron marker DARPP-32 at 7 months of age. It is anticipated that this novel transgenic animal will represent a practical model for drug/clinical trials and surgical interventions especially aimed at delaying or preventing HD initiation. New sequence accession number for ovine HTT mRNA: FJ457100.
    Human Molecular Genetics 02/2010; 19(10):1873-82. · 7.69 Impact Factor
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    ABSTRACT: Regulation of milk synthesis and secretion is controlled mostly through local (intramammary) mechanisms. To gain insight into the molecular pathways comprising this response, an analysis of mammary gene expression was conducted in 12 lactating cows shifted from twice daily to once daily milking. Tissues were sampled by biopsy from adjacent mammary quarters of these animals during the two milking frequencies, allowing changes in gene expression to be assessed within each animal. Using bovine-specific, oligonucleotide arrays representing 21,495 unique transcripts, a range of differentially expressed genes were found as a result of less frequent milk removal, constituting transcripts and pathways related to apoptotic signaling (NF-kappaB, JUN, ATF3, IGFBP5, TNFSF12A) mechanical stress and epithelial tight junction synthesis (CYR61, CTGF, THBS1, CLDN4, CLDN8), and downregulated milk synthesis (LALBA, B4GALT1, UGP2, CSN2, GPAM, LPL). Quantitative real-time PCR was used to assess the expression of 13 genes in the study, and all 13 of these were correlated (P < 0.05) with values derived from array analysis. It can be concluded that the physiological changes that occur in the bovine mammary gland as a result of reduced milk removal frequency likely comprise the earliest stages of the involution response and that mechano-signal transduction cascades associated with udder distension may play a role in triggering these events.
    Physiological Genomics 12/2009; 41(1):21-32. · 2.81 Impact Factor
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    ABSTRACT: beta-Carotene biochemistry is a fundamental process in mammalian biology. Aberrations either through malnutrition or potentially through genetic variation may lead to vitamin A deficiency, which is a substantial public health burden. In addition, understanding the genetic regulation of this process may enable bovine improvement. While many bovine QTL have been reported, few of the causative genes and mutations have been identified. We discovered a QTL for milk beta-carotene and subsequently identified a premature stop codon in bovine beta-carotene oxygenase 2 (BCO2), which also affects serum beta-carotene content. The BCO2 enzyme is thereby identified as a key regulator of beta-carotene metabolism.
    Genetics 05/2009; 182(3):923-6. · 4.39 Impact Factor
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    ABSTRACT: Previously we have reported the accumulation of an N-terminal fragment of the TATA-box binding protein (TBP) in Alzheimer's disease brain tissue and here we report the identification of a naturally occurring TBP splice variant as a likely mechanism for its production. The splice variant described here encodes the polyglutamine-containing N-terminal domain of this key transcription factor. We demonstrate the expression of the splice variant mRNA in a variety of human tissues and that the resulting protein forms inclusions in cell culture transfection studies. The unusual properties of the variant protein suggest that it may be functionally relevant in late onset neurodegenerative diseases.
    Brain research 04/2009; 1268:190-9. · 2.46 Impact Factor
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    ABSTRACT: 2-DE and MALDI mass fingerprinting were used to analyse mammary tissue from lactating Friesian cows. The goal was detection of enzymes in metabolic pathways for synthesis of milk molecules including fatty acids and lactose. Of 418 protein spots analysed by PMF, 328 were matched to database sequences, resulting in 215 unique proteins. We detected 11 out of the 15 enzymes in the direct pathways for conversion of glucose to fatty acids, two of the pentose phosphate pathway enzymes and two of the enzymes for lactose synthesis from glucose. We did not detect enzymes that catalyse the first three reactions of glycolysis. Our results are typical of enzyme detection using 2-DE of mammalian tissues. We therefore advocate caution when relating enzyme abundances measured by 2-DE to metabolic output as not all relevant proteins are detected. 2-D DIGE was used to measure interindividual variation in enzyme abundance from eight animals. We extracted relative protein abundances from 2-D DIGE data and used a logratio transformation that is appropriate for compositional data of the kind represented in many proteomics experiments. Coefficients of variation for abundances of detected enzymes were 3-8%. We recommend use of this transformation for DIGE and other compositional data.
    Proteomics 05/2008; 8(7):1502-15. · 4.43 Impact Factor

Publication Stats

4k Citations
402.05 Total Impact Points

Institutions

  • 2000–2014
    • University of Auckland
      • • School of Biological Sciences
      • • Faculty of Medical and Health Sciences
      • • Department of Pharmacology and Clinical Pharmacology
      • • Department of Medicine
      • • Department of Anatomy with Radiology
      Окленд, Auckland, New Zealand
  • 2008–2012
    • Victoria University of Wellington
      • School of Biological Sciences
      Wellington, Wellington, New Zealand
  • 2003–2011
    • Livestock Improvement Corporation
      Hamilton City, Waikato, New Zealand
  • 2010
    • ViaLactia Biosciences Limited
      Окленд, Auckland, New Zealand
  • 2002
    • University of Liège
      • Faculté de Médecine Vétérinaire
      Liège, WAL, Belgium
  • 1996
    • University of Cambridge
      • Department of Pathology
      Cambridge, ENG, United Kingdom
  • 1991–1994
    • University of Wales
      • College of Medicine
      Cardiff, Wales, United Kingdom