Search

Your search keyword '"Kenyon PR"' showing total 204 results
Start Over Author "Kenyon PR"
204 results on '"Kenyon PR"'

6. Functional development of the adult ovine mammary gland-insights from gene expression profiling

Author

Paten, AM, Duncan, EJ, Pain, SJ, Peterson, SW, Kenyon, PR, Blair, HT, and Dearden, PK

Abstract

Background: The mammary gland is a dynamic organ that undergoes dramatic physiological adaptations during the transition from late pregnancy to lactation. Investigation of the molecular basis of mammary development and function will provide fundamental insights into tissue remodelling as well as a better understanding of milk production and mammary disease. This is important to livestock production systems and human health. Here we use RNA-seq to identify differences in gene expression in the ovine mammary gland between late pregnancy and lactation. Results: Between late pregnancy (135 days of gestation ± 2.4 SD) and lactation (15 days post partum ± 1.27 SD) 13 % of genes in the sheep genome were differentially expressed in the ovine mammary gland. In late pregnancy, cell proliferation, beta-oxidation of fatty acids and translation were identified as key biological processes. During lactation, high levels of milk fat synthesis were mirrored by enrichment of genes associated with fatty acid biosynthesis, transport and lipogenesis. Protein processing in the endoplasmic reticulum was enriched during lactation, likely in support of active milk protein synthesis. Hormone and growth factor signalling and activation of signal transduction pathways, including the JAK-STAT and PPAR pathways, were also differently regulated, indicating key roles for these pathways in functional development of the ovine mammary gland. Changes in the expression of epigenetic regulators, particularly chromatin remodellers, indicate a possible role in coordinating the large-scale transcriptional changes that appear to be required to switch mammary processes from growth and development during late pregnancy to synthesis and secretion of milk during lactation. Conclusions: Coordinated transcriptional regulation of large numbers of genes is required to switch between mammary tissue establishment during late pregnancy, and activation and maintenance of milk production during lactation. Our findings indicate the remarkable plasticity of the mammary gland, and the coordinated regulation of multiple genes and pathways to begin milk production. Genes and pathways identified by the present study may be important for managing milk production and mammary development, and may inform studies of diseases affecting the mammary gland.

Published
2015

7. Identification of reference genes for RT-qPCR in ovine mammary tissue during late pregnancy and lactation and in response to maternal nutritional programming

Author

Paten, AM, Pain, SJ, Peterson, SW, Blair, HT, Kenyon, PR, Dearden, PK, and Duncan, EJ

Abstract

The mammary gland is a complex tissue consisting of multiple cell types which, over the lifetime of an animal, go through repeated cycles of development associated with pregnancy, lactation and involution. The mammary gland is also known to be sensitive to maternal programming by environmental stimuli such as nutrition. The molecular basis of these adaptations is of significant interest, but requires robust methods to measure gene expression. Reverse-transcription quantitative PCR (RT-qPCR) is commonly used to measure gene expression, and is currently the method of choice for validating genome-wide expression studies. RT-qPCR requires the selection of reference genes that are stably expressed over physiological states and treatments. In this study we identify suitable reference genes to normalize RT-qPCR data for the ovine mammary gland in two physiological states; late pregnancy and lactation. Biopsies were collected from offspring of ewes that had been subjected to different nutritional paradigms during pregnancy to examine effects of maternal programming on the mammary gland of the offspring. We evaluated eight candidate reference genes and found that two reference genes (PRPF3 and CUL1) are required for normalising RT-qPCR data from pooled RNA samples, but five reference genes are required for analyzing gene expression in individual animals (SENP2, EIF6, MRPL39, ATP1A1, CUL1). Using these stable reference genes, we showed that TET1, a key regulator of DNA methylation, is responsive to maternal programming and physiological state. The identification of these novel reference genes will be of utility to future studies of gene expression in the ovine mammary gland.

Published
2014

15. Investigation of fetal loss in ewe lambs in relation to liveweight changes and progesterone concentrations in early to mid gestation.

Author

Ridler, AL, Corner-Thomas, RA, Kenyon, PR, and Griffiths, KJ

Subjects
LAMB weight, FETAL death, PROGESTERONE, PREGNANCY, LAMBS, ANIMAL health
Abstract

AIMS: To investigate associations between changes in liveweight and fetal loss in ewe lambs and to determine whether fetal loss was associated with concentrations of progesterone in early and mid-gestation. METHODS: Ewe lambs on two commercial sheep farms (Flock A; n=504 and Flock B; n=460) in the southern North Island of New Zealand were weighed, and body condition score was assessed, prior to breeding and throughout pregnancy. Pregnancy diagnosis was undertaken approximately 56 (PD1), 80 (PD2) and 110 (PD3) days after the start of breeding and fetal loss determined. Blood samples were collected from a cohort of 407 ewe lambs between 45–54 and 73–84 days of gestation. Those that subsequently were diagnosed with fetal loss (n=16) were matched with ewe lambs that maintained pregnancy (n=16), and concentrations of progesterone were measured in the plasma samples from these animals. RESULTS: Fetal loss was diagnosed in 55/472 (11.7%) pregnant ewes from Flock A and 14/378 (3.7%) from Flock B. In both flocks the change in conceptus-free liveweight (CFLW) between PD1 and PD2 differed between ewe lambs with and without fetal loss; in Flock A the mean change was −59.9 (95% CI=−80.1 to −39.7) g/dayvs.−3.43 (95% CI=−9.8 to 3.0) g/day (p<0.001), and in Flock B the change was −38.5 (95% CI=−78.9 to 1.94) g/dayvs.79.5 (95% CI=72.6–86.4) g/day (p<0.001). Similarly in Flock A the mean increase in CFLW between PD2 and PD3 was lower in ewe lambs with fetal loss than in those that maintained pregnancy (25.8 (95% CI=−13.8 to 65.4) g/dayvs.181.9 (95% CI=175.1–188.7) g/day) (p<0.001). There was no difference (p>0.05) in early and mid-gestation mean concentrations of progesterone in plasma between ewe lambs that had fetal loss compared with those that maintained pregnancy. CONCLUSIONS: Ewe lambs with fetal loss had a marked reduction in CFLW in the 24–30 days leading up to the identification of the fetal loss compared with those that maintained pregnancy. Early and mid-gestation concentrations of progesterone in plasma were similar between ewe lambs who went on to have fetal loss and those that maintained pregnancy. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF

19. Influence of demographic factors on the use of farm management tools by New Zealand farmers.

Author

Corner-Thomas, RA, Kenyon, PR, Morris, ST, Ridler, AL, Hickson, RE, Greer, AW, Logan, CM, and Blair, HT

Subjects
*FARM management, *AGROTECHNOLOGY transfer, *FARMERS, *AGRICULTURE, *AGRICULTURAL laborers, *FARM life, *FARM size
Abstract

Knowledge of the use of farm management tools by New Zealand farmers is important to enable the identification of areas where better uptake of tools can result in improvements in farm profitability. In October 2012, a survey was sent to all New Zealand sheep farmers asking them to indicate which farm management tools they had used in the previous 3 years. A total of 962 usable survey responses were returned which represented 7.8% of sheep farmers. The results showed that a number of the management tools were used by a small percentage of farmers thus indicating that improvements in farm productivity could be achieved by increasing their use. In addition, use of these management tools was associated with a number of demographic factors including farm size, farmer age and highest education level. This new knowledge indicates that the delivery of technology transfer should be tailored to farmers based on at least these socioeconomic factors. [ABSTRACT FROM PUBLISHER]

Published
2015
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results