ACTA VETERINARIA ET ZOOTECHNICA SINICA ›› 2014, Vol. 45 ›› Issue (3): 402-409.doi: 10.11843/j.issn.0366-6964.2014.03.009

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Effects of the Proportion of Peptide Binding and Free Amino Acids on Casein Synthesis in the Mammary Gland Explants

XIA Ting,SHI Ke-rong,LIN Xue-yan,HOU Qiu-ling,WANG Zhong-hua*   

  1. (College of Animal Science and Veterinary Medicine,Shandong Agricultural University,Tai’an 271018, China)
  • Received:2013-01-14 Online:2014-03-23 Published:2014-03-23

Abstract:

The lactating bovine mammary tissue in vitro in the treatment medium was cultured in this study,FAA were substituted with different proportion of 0%(as control),5 %,10%,15%,20%,40%,60%,80% and 100% of Met-Met or Arg-His-Ile(tripeptide Arg-His-Ile was substituted with His as of proportions).The mRNA expression levels of casein-αS1(CSN1S1),PepTⅡ,ammonia peptide enzyme(ANPEP) and the protein expression levels of casein-β(β-casein) PepTⅡand ANPEP were detected.The results show that:replacing FAA with Met-Met significantly increased the mRNA expression of CSN1S1,the protein expression of β-casein,and also both mRNA and protein expressions of PepTⅡ(P<0.05).However,the mRNA expression of ANPEP had no significant change(P>0.05).While,Arg-His-Ile substitution had no significant effect on either mRNA expression of CSN1S1 or protein expression,but both mRNA and protein expression of PepTⅡwere significantly increased.This study support the hypothesis that mammary tissue can make use of Met-Met as amino acid source at certain percentage and enhance the synthesis of casein.Moreover,peptide transporter Ⅱ(PepTⅡ) may be the main mechanism allowing the small peptides be transported into the mammary epithelial cells.

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