RESUMEN
Milk protein synthesis in the mammary gland involves expression of six major milk protein genes whose nutritional regulation remains poorly defined. In this study, the effect of long term under- and over-feeding on the expression of αs1-casein: CSN1S1, αs2-casein: CSN1S2, ß-casein: CSN2, κ-casein: CSN3, α-lactalbumin: LALBA and ß-lactoglobulin: BLG gene in sheep mammary tissue (MT) was examined. Twenty-four lactating dairy sheep, at 90-98 d in milk, were divided into three groups and fed the same ration, for 60 d, in quantities which met 70% (underfeeding), 100% (control) and 130% (overfeeding) of their energy and crude protein requirements. The results showed a significant reduction on mRNA of CSN1S1, CSN1S2, CSN2 and BLG gene in the MT of underfed sheep compared with the overfed ones and a significant reduction in CSN3 and LALBA gene expression compared with the respective control animals. Significant positive correlations were observed between the mRNA levels of milk proteins' genes with the milk protein yield and milk yield respectively. In conclusion, the feeding level and consequently the nutrients availability, affected the milk protein yield and milk volume by altering the CSN1S1, CSN1S2, CSN2, CSN3, LALBA and BLG gene expression involved in their metabolic pathways.
Asunto(s)
Fenómenos Fisiológicos Nutricionales de los Animales/fisiología , Dieta/veterinaria , Expresión Génica , Glándulas Mamarias Animales/metabolismo , Proteínas de la Leche/genética , Ovinos/fisiología , Alimentación Animal , Animales , Caseínas/genética , Proteínas en la Dieta/administración & dosificación , Ingestión de Energía , Femenino , Lactalbúmina/genética , Lactancia , Lactoglobulinas/genética , Glándulas Mamarias Animales/química , Leche/química , Proteínas de la Leche/análisis , Necesidades Nutricionales , ARN Mensajero/análisisRESUMEN
Glucose utilisation for lactose synthesis in the mammary gland involves expression of a large number of genes whose nutritional regulation remains poorly defined. In this study, the effect of long term under- and over-feeding on the expression of genes [glucose transporter 1: GLUT1, glucose transporter 3: GLUT3, Sodium glucose contransporter 1: SGLT1, two isoforms of ß- (1,4) galactosyltransferase: ß- (1,4) GAT1, ß- (1,4) GAT3 and α-lactalbumin: LALBA] related to glucose metabolism in sheep mammary tissue (MT) was examined. Twenty-four lactating dairy sheep were divided into three homogenous sub-groups and fed the same ration in quantities which met 70% (underfeeding), 100% (control) and 130% (overfeeding) of their energy and crude protein requirements. The results showed a significant reduction on mRNA of GLUT1 and LALBA gene in the MT of underfed sheep, compared with the respective controls and overfed and a significant reduction on mRNA level of SGLT1 and ß- (1,4) GAT1 in the MT of underfed sheep, compared with the overfed ones. A significant increase in the GLUT3 mRNA accumulation in the MT of both under- and over- fed sheep was found. Additionally, a trend of reduction on ß- (1,4) GAT3 mRNA level in the MT of the underfed sheep, compared with the overfed, was observed. A close positive relationship was obtained between the mRNA transcripts accumulation of GLUT1, SGLT1, ß- (1,4) GAT1 and LALBA gene with the milk lactose content and milk lactose yield respectively. In conclusion, feeding level and consequently nutrient availability, may affect glucose uptake and utilisation in sheep MT by altering the GLUT1, GLUT3, SGLT1, ß- (1,4) GAT1 and LALBA gene expression involved in their metabolic pathways.
Asunto(s)
Privación de Alimentos/fisiología , Regulación de la Expresión Génica/efectos de los fármacos , Glucosa/metabolismo , Glándulas Mamarias Animales/metabolismo , Ovinos/fisiología , Alimentación Animal , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Dieta/veterinaria , Ingestión de Energía , Metabolismo Energético , Femenino , Galactosiltransferasas/genética , Galactosiltransferasas/metabolismo , Transportador de Glucosa de Tipo 1/genética , Transportador de Glucosa de Tipo 1/metabolismo , Transportador de Glucosa de Tipo 3/genética , Transportador de Glucosa de Tipo 3/metabolismo , Lactalbúmina/genética , Lactalbúmina/metabolismo , Lactancia , Necesidades Nutricionales , ARN Mensajero/genética , ARN Mensajero/metabolismo , Transportador 1 de Sodio-Glucosa/genética , Transportador 1 de Sodio-Glucosa/metabolismoRESUMEN
Milk fatty acid (FA) synthesis by the mammary gland involves expression of a large number of genes whose nutritional regulation remains poorly defined. In this study, we examined the effect of long-term under- and over-feeding on the expression of genes (acetyl Co A carboxylase, ACC; fatty acid synthetase, FAS; lipoprotein lipase, LPL; stearoyl Co A desaturase, SCD; peroxisome proliferator activated receptor γ2, PPARγ2; sterol regulatory element binding protein-1, SREBP-1c; and hormone sensitive lipase, HSL) related to FA metabolism in sheep mammary tissue (MT). Twenty-four lactating sheep were divided into three homogenous sub-groups and fed the same ration in quantities covering 70% (underfeeding), 100% (control) and 130% (overfeeding) of their energy and crude protein requirements. The results showed a significant reduction of mRNA of ACC, FAS, LPL and SCD in the MT of underfed sheep, and a significant increase on the mRNA of LPL and SREBP-1c in the MT of overfed compared with the control respectively. In conclusion, the negative, compared to positive, energy balance in sheep down-regulates ACC, FAS, LPL, SCD, SREBP-1c and PPARγ2 expression in their MT which indicates that the decrease in nutrient availability may lead to lower rates of lipid synthesis.
