RESUMO
Mastitis is an economically devastating disease affecting the dairy industry. Dairy cows with mastitis give reduced milk yield and produce milk that is unfit for consumption. The chemokine receptor CXCR1 is an excellent prospective genetic marker for mastitis resistance in cattle because it regulates neutrophil migration, killing, and survival during infection. We detected 4 single nucleotide polymorphisms (SNPs) of the CXCR1 gene in Chinese native cattle and analyzed their associations with milk traits. Screening for genetic variations in CXCR1 among 648 Chinese Holstein, Luxi Yellow, and Bohai Black cattle by created restriction site polymerase chain reaction (PCR), nested PCR, and DNA sequencing revealed 4 new SNPs with allelic frequencies ranging from 0.676 to 0.821, 0.706 to 0.803, 0.647 to 0.824, and 0.558 to 0.581. All four CXCR1 gene SNPs were located in exon II. Two SNPs, c.337A>G and c.365C>T, were nonsynonymous mutations [ATC (Ile) > GTC (Val) and GCC (Ala) > GTC (Val)], whereas two, c.291C>T and c.333C>T, were synonymous mutations [TTC (Gly) > TTT (Gly) and GGC (Phe) > GGT (Phe)]. Statistical analyses revealed the significant association of c.337A>G and c.365C>T with the somatic cell score, which suggests the possible role of these SNPs in the host response against mastitis. Our data suggest that combined genotypes CCAC/CCGC, CCAC/CTAT, and CCAT/CTAT (lowest somatic cell scores); CTAC/CTAT (highest protein rate); CCAC/CTGC (highest fat rate); and CCAT/CTAT (highest 305-day milk yield) can be used as possible candidates for marker-assisted selection in dairy cattle breeding programs.
Assuntos
Bovinos/genética , Lactação/genética , Polimorfismo de Nucleotídeo Único , Receptores de Interleucina-8A/genética , Animais , Animais Endogâmicos , Éxons , Feminino , Estudos de Associação Genética , Mastite Bovina/genética , Leite/metabolismo , Mutação , Característica Quantitativa HerdávelRESUMO
Bovine lactoferrin (bLF) is a member of the transferrin family; it plays an important role in the innate immune response. We identified novel splice variants of the bLF gene in mastitis-infected and healthy cows. Reverse transcription-polymerase chain reaction (RT-PCR) and clone sequencing analysis were used to screen the splice variants of the bLF gene in the mammary gland, spleen and liver tissues. One main transcript corresponding to the bLF reference sequence was found in three tissues in both healthy and mastitis-infected cows. Quantitative real-time PCR analysis showed that the expression levels of the LF gene's main transcript were not significantly different in tissues from healthy versus mastitis-infected cows. However, the new splice variant, LF-AS2, which has the exon-skipping alternative splicing pattern, was only identified in mammary glands infected with Staphylococcus aureus. Sequencing analysis showed that the new splice variant was 251 bp in length, including exon 1, part of exon 2, part of exon 16, and exon 17. We conclude that bLF may play a role in resistance to mastitis through alternative splicing mechanisms.
Assuntos
Lactoferrina/genética , Glândulas Mamárias Animais/imunologia , Mastite Bovina/metabolismo , Infecções Estafilocócicas/veterinária , Staphylococcus aureus/genética , Processamento Alternativo , Animais , Bovinos , Éxons , Feminino , Expressão Gênica , Lactoferrina/imunologia , Lactoferrina/metabolismo , Fígado/imunologia , Fígado/metabolismo , Glândulas Mamárias Animais/metabolismo , Glândulas Mamárias Animais/microbiologia , Mastite Bovina/imunologia , Mastite Bovina/microbiologia , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Baço/imunologia , Baço/metabolismo , Infecções Estafilocócicas/imunologia , Infecções Estafilocócicas/metabolismo , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/imunologiaRESUMO
Transferrin (Tf) is a ß-globulin protein that transports iron ions in mammalian cells. It contributes to innate immunity to microbial pathogens, primarily by limiting microbial access to iron. Thus, polymorphisms present in bovine Tf could potentially underlie inherited differences in mastitis resistance and milk production traits. We detected three novel single-nucleotide polymorphisms of the Tf gene in Chinese native cattle by screening for genetic variation of Tf in 751 individuals of three Chinese cattle breeds, namely China Holstein, Luxi Yellow and Bohai Black, using PCR-RFLP and DNA sequencing techniques. The three new SNPs, g.-1748G>A ss250608649, g.13942T>C ss250608650, and g.14037A>G ss250608651, had allele frequencies of 85.9, 86.3 and 92.5%, 64.5, 73.3 and 65.0%, and 67.6, 73.7 and 60.0%, respectively. SNP g.-1748G>A was located in the 5' flanking region of Tf. SNP g.14037A>G was located in intron 8 of Tf. SNP g.13942T>C, located in exon 8 of Tf, was a synonymous mutation (TTA > CTA), encoding a leucine (326 aa) in the Tf protein. Associations of the Tf SNPs with milk traits were also analyzed. Significant (P < 0.05) relationships among the Tf polymorphisms, somatic cell scores (SCS), and milk productive traits were observed. Cows with genotypes TT (g.13942T>C), GG (g.-1748G>A) and AG (g.14037A>G) had a lower SCS and higher protein levels and 305-day milk yield. Nineteen combinations of different haplotypes from the three SNPs were identified in Chinese Holstein cattle. The haplotype combination ATA/GCA, GCA/GCA and GCG/ GTA was dominant in cows with a lower SCS, a higher protein level and a higher 305-day milk yield, respectively. Moreover, the gene expression level of Tf was higher in mastitis-affected mammary tissues than in normal mammary tissues. These results suggest that the Tf gene affects milk production, as well as mastitis-resistance traits, in Chinese Holsteins.