A Novel SNPs in Alpha-Lactalbumin Gene Effects on Lactation Traits in Chinese Holstein Dairy Cows
by
, ,
Fan Yang
1,2
,
Manling Zhang
1,2,
Yuewen Rong
3,
Zaiqun Liu
2,
Shuai Yang
2,
Wei Zhang
1,
Jun Li
2,* and
Yafei Cai
1,* 
1
College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
2
College of Life Sciences, Anhui Provincial Key Lab of the Conservation and Exploitation of Biological Resources, Anhui Normal University, Wuhu 241000, China
3
Physical and chemical testing laboratory, Anji County Center for Food and Drug Control, Huzhou 313300, China
*
Authors to whom correspondence should be addressed.
Animals 2020, 10(1), 60; https://doi.org/10.3390/ani10010060
Submission received: 5 December 2019
/
Revised: 23 December 2019
/
Accepted: 25 December 2019
/
Published: 29 December 2019
(This article belongs to the Special Issue Biomarkers Involved in Meat and Milk Yield, Composition and Technological Properties in Livestock Species)
Simple Summary
Alpha-lactalbumin (α-LA) is a major whey protein component in mammalian milk, such as human (approximately 36%), bovine (approximately 17%), and other species, etc., It is involved in the regulation of lactose synthesis and has high nutritional value, especially in infant formula. Previous studies have confirmed that bovine α-LA gene 5′-flanking region has single nucleotide polymorphisms (SNPs), but little is known about polymorphisms in other regions, especially sequence coding for amino acids in protein (CDS) and their adjacent non-coding regions, including Chinese Holstein dairy cows. This study focused on investigated SNPs in the CDS and their adjacent non-coding regions of the α-LA gene in Chinese Holstein dairy cows, and assessed the association between SNPs and lactation traits. Sequence alignment showed that a potential SNPs (562th, G/A) in CDS2 region affect protein spatial structure, suggesting that this SNPs might affect the lactation traits of cows (milk type (Holstein and Jersey), and non-milk type (Bos Taurus)) need more in-depth study. More importantly, a novel SNPs at 1847th (T/C) bp in non-coding region near CDS4 was significantly associated with milk lactose composition, and lactose contents were significantly correlated with milk protein content, indicating that the SNPs could be used as a novel potential molecular marker for lactation traits in Chinese Holstein dairy cows.
Abstract
Alpha-lactalbumin (α-LA) is a major whey protein in bovine and other mammalian milk, which regulates synthesis of lactose. Little is known about its genetic polymorphism and whether can be used as a potential marker for dairy ingredients, milk yield traits, and milk properties. To investigate its polymorphisms and their relationship with milk lactation traits in Chinese Holstein dairy cows, single-strand conformation polymorphism method (PCR-SSCP) and direct sequencing method were used to mark the α-LA gene SNPs. AA (0.7402) and AB (0.2598) genotypes were screened out by PCR-SSCP bands analysis in two independent populations. Direct sequencing revealed that there is one SNP at 1847th (T/C) bp in noncoding region of α-LA gene with highly polymorphic (0.5 < PIC = 0.5623 or 0.5822), of which T is in AA genotype while C in AB. Association analysis also showed that lactose content (p < 0.05) was negatively correlated with fat and protein contents within subgroup, indicating that the SNPs (1847th, T/C) in α-LA gene could be used as a novel potential molecular marker for lactation traits in Chinese Holstein dairy cows.
Keywords:
Alpha-lactalbumin (α-LA); PCR-SSCP; Chinese Holstein dairy cows; SNPs; lactose
