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Responses of the mammary transcriptome of dairy cows to altered photoperiod during late gestation.

ABSTRACT: Cows exposed to short day photoperiod (SD, 8L:16D) during the 60-day nonlactating period prior to parturition produce more milk in their subsequent lactation compared with cows exposed to long day photoperiod (LD, 16L:8D). Although this response is well established in dairy cows, the underlying mechanisms are not understood. We hypothesized that differential gene expression in cows exposed to SD or LD photoperiods during the dry period could be used to identify the functional basis for the subsequent increase in milk production during lactation. Pregnant, multiparous cows were maintained on an SD or LD photoperiod for 60 days prior to parturition. Mammary biopsies were obtained on days -24 and -9 relative to parturition and Affymetrix GeneChip Bovine Genome Arrays were used to quantify gene expression. Sixty-four genes were differentially expressed (P ? 0.05 and fold-change ? |1.5|) between SD and LD treatments. Many of these genes were associated with cell growth and proliferation, or immune function. Ingenuity Pathway Analysis predicted upstream regulators to include TNF, TGF-?1, interferon-?, and several interleukins. In addition, expression of 125 genes was significantly different between day -24 and day -9; those genes were associated with milk component metabolism and immune function. The interaction of photoperiod and time affected 32 genes associated with insulin-like growth factor I signaling. Genes differentially expressed in response to photoperiod were associated with mammary development and immune function consistent with the enhancement of milk yield in the ensuing lactation. Our results provide insight into the mechanisms by which photoperiod affects the mammary gland and subsequently lactation.

SUBMITTER: Bentley PA

PROVIDER: S-EPMC4593831 | biostudies-other | 2015 Oct

REPOSITORIES: biostudies-other

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Responses of the mammary transcriptome of dairy cows to altered photoperiod during late gestation.

Bentley P A PA Wall E H EH Dahl G E GE McFadden T B TB

Physiological genomics 20150714 10

Cows exposed to short day photoperiod (SD, 8L:16D) during the 60-day nonlactating period prior to parturition produce more milk in their subsequent lactation compared with cows exposed to long day photoperiod (LD, 16L:8D). Although this response is well established in dairy cows, the underlying mechanisms are not understood. We hypothesized that differential gene expression in cows exposed to SD or LD photoperiods during the dry period could be used to identify the functional basis for the subse ...[more]

PMID: 26175502

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Project description:Cows exposed to short day photoperiod (SD, 8L:16D) during the 60-day non-lactating period prior to parturition produce more milk in their subsequent lactation compared to cows exposed to long day photoperiod (LD,16L:8D). Although this response is well-established in dairy cows, the underlying mechanisms are not understood. We hypothesized that differential gene expression in cows exposed to SD or LD photoperiods during the dry period could be used to identify the functional basis for the subsequent increase in milk production during lactation. Pregnant, multiparous cows were maintained on a SD or LD photoperiod for 60-days prior to parturition. Mammary biopsies were obtained on days -24 and -9 relative to parturition and Affymetrix GeneChip® Bovine Genome Arrays were used to quantify gene expression. Sixty-four genes were differentially expressed (p ≤ 0.05 and fold-change ≥ |1.5|) between SD and LD treatments. Many of these genes were associated with cell growth and proliferation, or immune function. Ingenuity Pathway Analysis predicted upstream regulators to include TNF, TGFβ1, interferon γ and several interleukins. In addition, expression of 125 genes was significantly different between day -24 and day -9; those genes were associated with milk component metabolism and immune function. The interaction of photoperiod and time affected 32 genes associated with insulin-like growth factor (IGF-I) signaling. Genes differentially expressed in response to photoperiod were associated with mammary development and immune function consistent with the enhancement of milk yield in the ensuing lactation. Our results provide insight into the mechanisms by which photoperiod affects the mammary gland and subsequently lactation. Data were analyzed for the effect of photoperiod treatment (LD minus SD), time relative to parturition (day -24 minus day -9) and the interaction of photoperiod treatment and time ((LD minus SD day -9) minus (LD minus SD day -24))

Project description:Liver and mammary gland are among the most important organs during lactation in dairy cows. With the purpose of understanding both the different and the complementary roles and the crosstalk of those two organs during lactation, a transcriptome analysis was performed on liver and mammary tissues of 10 primiparous dairy cows in mid-lactation. The analysis was performed using a 4×44K Bovine Agilent microarray chip. The transcriptome difference between the two tissues was analyzed using SAS JMP Genomics using ANOVA with a false discovery rate correction (FDR). The analysis uncovered >9,000 genes differentially expressed (DEG) between the two tissues with a FDR<0.001. The functional analysis of the DEG uncovered a larger metabolic (especially related to lipid) and inflammatory response capacity in liver compared with mammary tissue while the mammary tissue had a larger protein synthesis and secretion, proliferation/differentiation, signaling, and innate immune system capacity compared with the liver. A plethora of endogenous compounds, cytokines, and transcription factors were estimated to control the DEG between the two tissues. Compared with mammary tissue, the liver transcriptome appeared to be under control of a large array of ligand-dependent nuclear receptors and, among endogenous chemical, fatty acids and bacteria-derived compounds. Compared with liver, the transcriptome of the mammary tissue was potentially under control of a large number of growth factors and miRNA. The in silico crosstalk analysis between the two tissues revealed an overall large communication with a reciprocal control of lipid metabolism, innate immune system adaptation, and proliferation/differentiation. In summary the transcriptome analysis confirmed prior known differences between liver and mammary tissue, especially considering the indication of a larger metabolic activity in liver compared with the mammary tissue and the larger protein synthesis, communication, and proliferative capacity in mammary tissue compared with the liver. Relatively novel is the indication by the data that the transcriptome of the liver is highly regulated by dietary and bacteria-related compounds while the mammary transcriptome is more under control of hormones, growth factors, and miRNA. A large crosstalk between the two tissues with a reciprocal control of metabolism and innate immune-adaptation was indicated by the network analysis that allowed uncovering previously unknown crosstalk between liver and mammary tissue for several signaling molecules.

Dataset Information

Responses of the mammary transcriptome of dairy cows to altered photoperiod during late gestation.

Publications

Responses of the mammary transcriptome of dairy cows to altered photoperiod during late gestation.

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