Association between SREBP-1 gene expression in mammary gland and milk fat yield in Sarda breed sheep

Abstract

SummaryThe aim of this study was to examine the expression patterns of SREBP-1 gene in milk somatic cells and its association with milk fat yield during early lactation in Sarda breed sheep. A sample of 20 Sarda ewes, aged between 4 and 5 years, in their third to fourth lactation were chosen. From each ewe 28 days after lambing milk yield was measured, and a 160 ml milk sample for the RNA extraction and to test somatic cells count and lactose, fat and protein contents were collected. From the obtained RNA, total cDNA was synthesized and the quantitative PCR was performed. The fat, proteins and lactose content showed many differences among the animals, but these variations were no correlated with the milk yield. The SREBP-1 gene expression resulted higher in the high milk fat producing ewes. The correlation analysis showed that the SREBP-1 expression level is directly related to the amount of milk fat (g/die) (P < 0.001), while the total RNA obtained from each sample was found to be related to the somatic cells number (P < 0.001). Instead the expression of this gene showed no relations with the concentration of fat in milk. Our data highlight that in sheep SREBP-1 gene is expressed in the mammary gland during early lactation. Moreover, the positive relationship between SREBP-1 gene expression and the milk fat yield suggests that SREBP-1 gene is required for the lipid synthesis in the sheep mammary gland.

The effect of long term under- and over-feeding on the expression of genes related to lipid metabolism in mammary tissue of sheep

“…It is remarkable that the activation of PPARγ by rosiglitazone in goat mammary epithelial cells was accompanied by a significant increase in the expression of SREBP-1 gene, demonstrating that SREBP-1 is a PPARγ target gene in ruminants (Shi et al 2013). Recently, Carcangiu et al (2013) suggests that the SREBP-1 gene is required for the milk fat synthesis, since a positive relationship between SREBP-1 gene expression in the milk somatic cells and the milk fat yield of ewes was observed. Indeed, the overfed sheep in our study produced higher milk fat yield compared with the underfed ones (Tsiplakou et al 2012).…”

Feeding level regulates the expression of some genes involved with programed cell death and remodeling in goat and sheep mammary tissue

“…So, based on the fact that the UXT has been proposed both in cows and goats as a stable reference gene for the MT during lactation (Bionaz and Loor, 2007;Bonnet et al, 2013) it was also used in the present study. Additionally, the UXT has been used as a reference gene in a study with sheep MT (Carcangiu et al, 2013). As the choice of RPS9 is concerned, it was done taking into account that it has been characterized also by high stability in the MT of cows (Bionaz and Loor, 2007) while in goats, Finot et al (2011) concluded that in the choice of reference genes should be included at least one ribosomal protein gene.…”

Buffalo SREBP1: molecular cloning, expression and association analysis with milk production traits

“…Twinning rates in cattle range from 1% to 5% depending on the breed, with dairy breeds typically having the highest rates. [1][2][3][4][5] However, the rate of heteropaternal superfecundation (HS) has so far not been studied, although it receives attention in the popular press. 6-8 HS occurs when two or more ova are fertilized by two or more males during the same reproductive cycle.…”

“…Sterol regulatory element‐binding proteins (SREBPs) belong to the basic helix‐loop‐helix‐leucine zipper (bHLH‐zipper) family of transcription factors, which are critical regulators of cholesterol and lipid homeostasis . The SREBP1 gene has significant genetic effects on milk fatty acid composition, low‐fat milk syndrome, milk composition and milk fat yield . Here we report on water buffalo SREBP 1 tissue expression patterns, identify SNPs and investigate the associations between these SNPs and milk traits.…”

“…1 The SREBP1 gene has significant genetic effects on milk fatty acid composition, 2 low-fat milk syndrome, 3 milk composition 4 and milk fat yield. 5 Here we report on water buffalo SREBP1 tissue expression patterns, identify SNPs and investigate the associations between these SNPs and milk traits.…”