title: Transcript abundance of amino acid transporters, β-casein, and α-lactalbumin in mammary tissue of periparturient, lactating, and postweaned sows.
abstract: The objective of these experiments was to test the hypothesis that transcript abundance of cationic AA transporter- and milk protein-encoding genes increase in the porcine mammary gland in response to higher lactation demand. Genes of interest included those encoding for the milk proteins α-lactalbumin (α-LA) and β-casein (β-CN; LALBA and CSN2, respectively), and AA transporter b(0,+)AT, y(+)LAT1, y(+)LAT2, ATB(0,+), CAT-1, and CAT-2b (SLC7A9, SLC7A7, SLC7A6, SLC6A14, SLC7A1, and SLC7A2, respectively). Mammary tissue was biopsied from 4 sows on d 110 of gestation (prepartum), on d 2 (early postpartum), on d 5 (early), and d 17 (peak) of lactation, and on d 5 after weaning (postweaning), and mRNA of target genes quantified by reverse transcription quantitative PCR. Compared with prepartum, CAT-1, ATB(0,+), y(+)LAT2, β-CN, and α-LA mRNA abundance was higher at early lactation, whereas compared with early lactation, only CAT-1 and α-LA mRNA abundance was higher at peak lactation. The CAT-2b, y(+)LAT1, and b(0,+)AT mRNA abundance did not differ when comparing either prepartum or peak lactation to early lactation. Compared with peak lactation, postweaning mRNA abundance of CAT-1, ATB(0,+), α-LA, and β-CN decreased, y(+)LAT2, CAT-2b, and b(0,+)AT remained unchanged, and y(+)LAT1 increased. The mRNA abundance of y(+)LAT2 increased from early postpartum to early lactation, and remained unchanged for CAT-1, ATB(0,+), α-LA, and β-CN. From prepartum to peak lactation, the mRNA abundance of CAT-1, y(+)LAT2, and ATB(0,+) was positively correlated with that of β-CN and α-LA. In conclusion, the expression of genes encoding for y(+)LAT1, CAT-2b, and b(0,+)AT remained unchanged in porcine mammary glands over prepartum to peak lactation period, whereas expression of genes encoding for CAT-1, ATB(0,+), and y(+)LAT2 was upregulated and positively correlated to expression of genes encoding for the mammary synthesized milk proteins β-CN and α-LA.
authors.affiliation: Department of Animal Science, and Wildlife, Michigan State University, East Lansing, USA.
authors.forename: R
authors.initials: R
authors.lastname: Manjarin
authors.forename: J P
authors.initials: JP
authors.lastname: Steibel
authors.forename: V
authors.initials: V
authors.lastname: Zamora
authors.forename: N
authors.initials: N
authors.lastname: Am-In
authors.forename: R N
authors.initials: RN
authors.lastname: Kirkwood
authors.forename: C W
authors.initials: CW
authors.lastname: Ernst
authors.forename: P S
authors.initials: PS
authors.lastname: Weber
authors.forename: N P
authors.initials: NP
authors.lastname: Taylor
authors.forename: N L
authors.initials: NL
authors.lastname: Trottier
mesh_terms: D026905:Amino Acid Transport Systems / Q000235:genetics*; D000818:Animals; D002364:Caseins / Q000235:genetics*; D005260:Female; D007768:Lactalbumin / Q000235:genetics*; D007774:Lactation; D008321:Mammary Glands, Animal / Q000378:metabolism*; D058725:Peripartum Period; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine; D014886:Weaning
chemical_list: D026905:Amino Acid Transport Systems; D002364:Caseins; D012333:RNA, Messenger; D007768:Lactalbumin