Abstract

Microarray analysis of hepatic gene expression from dry-off through early lactation in dairy cows fed at two intakes during the dry period 

J. J. Loor, N. A. Janovick, H. M. Dann, R. E. Everts, S. L. Rodriguez-Zas, H. A. Lewin, and J. K. Drackley.  University of Illinois, Urbana.

ADSA/ASAS/PSA Annual Joint Meeting, St. Louis, July 25-29, 2004

A bovine cDNA microarray was used to study gene expression during the periparturient period in response to restricted or ad libitum DMI during the dry period.  Liver from four Holstein cows with ad libitum (ca. 150% of NRC requirements; AA) or restricted (80% of requirements; RR) DMI of far-off and close-up diets was biopsied at -65, -30, -14, 1, 14, 28, and 49 d relative to parturition.  All cows had ad libitum access to the same lactation diet.  A microarray consisting of 7,872 cDNA inserts was used for transcript profiling.  Annotation was based on similarity searches using BLASTN and TBLASTX against human and mouse UniGene databases and the human genome.  Cy3- and Cy5-labelled cDNA from liver and a reference standard (derived from a mixture of cattle tissues) were used for hybridizations (106 microarrays).  Loess-normalized log-transformed ratios (liver/standard) were used to detect differential gene expression.  Using Benjamini and Hochberg’s False Discovery Rate (0.10) to determine effects of prepartum DMI, day, or their interaction on differential gene expression resulted in 2, 537, or 29, respectively, significant genes.  Among those with significant interactions were genes associated with lipid metabolism, signal transduction, and insulin action.  Genes differentially expressed by day relative to parturition included some involved in cell proliferation, carbohydrate metabolism, and protein catabolism.  Hierarchical clustering showed that expression patterns on d –14, 1, and 14 were grouped in two clusters according to prepartum DMI.  RR resulted in greater number of genes being upregulated 1.5 fold or greater on d 1 vs. d –14 (AA, 21; RR, 286).  A similar trend was observed when comparing d 14 (AA, 31; RR, 139), d 28 (AA, 334; RR, 910), and d 49 (AA, 398; RR, 1,036) vs. d 1.  Our data indicate that prepartum plane of nutrition alters hepatic gene expression during the peripartum period. (Supported by award 2001-35206-10946 from NRI Competitive Grants Program/CSREES/USDA). Journal of Dairy Science, 87(Suppl. 1):T133.