The single nucleotide polymorphism g.133A>C in the stearoyl CoA desaturase gene (SCD) promoter affects gene expression and quali-quantitative properties of river buffalo milk

Detection of Polymorphisms in FASN, DGAT1, and PPARGC1A Genes and Their Association with Milk Yield and Composition Traits in River Buffalo of Bangladesh

This study aimed to identify SNPs in the intron, exon, and UTR regions of the FASN, DGAT1, and PPARGC1A genes and to investigate their possible association with milk yield and composition traits in the riverine buffalo of Bangladesh. A total of 150 DNA samples from riverine buffalo were used for PCR amplification with five pairs of primers, followed by association studies using a generalized linear model in R. SNP genotyping was performed by direct sequencing of the respective amplicon. Traits analyzed included DMY, fat%, protein%, and SNF%. This study identified 8 SNPs in FASN (g.7163G>A and g.7271C>T), DGAT1 (g.7809C>T and g.8525C>T) and PPARGC1A (g.387642C>T, g.387758A>G, g.409354A>G, and g.409452G>A). Genotypic and allelic frequencies differed significantly for each SNP genotype and did not follow the Hardy-Weinberg principle (p < 0.01 or p < 0.001) in most cases. The g.7163G>A and g.7271C>T SNP genotypes of the FASN gene were significantly associated with milk fat%, with the latter also significantly associated with SNF%. The g.8525C>T polymorphism of the DGAT1 gene significantly affected protein% (p < 0.01). Additionally, PPARGC1A gene polymorphisms showed significant associations: g.387642C>T with fat% (p < 0.05); g.387758A>G and g.409354A>G with protein% (p < 0.001) and SNF% (p < 0.01); and g.409452G>A with DMY (p < 0.001), fat% (p < 0.05), and protein% (p < 0.01). Reconstructed haplotypes of the PPARGC1A gene were significantly associated (p < 0.01) with all traits except SNF%. These findings suggest that polymorphisms in these three candidate genes have the potential as molecular markers for improving milk yield and composition traits in the riverine buffalo of Bangladesh.

Single nucleotide polymorphisms in the KRT82 promoter region modulate irregular thickening and patchiness in the dorsal skin of New Zealand rabbits

BACKGROUND

While rabbits are used as models in skin irritation tests, the presence of irregular patches and thickening on the dorsal skin can affect precise evaluation. In this study, genes associated with patchiness or non-patchiness on the dorsal skin of New Zealand rabbits were investigated to identify potential regulators of the patchiness phenotype.

RESULTS

The results showed that parameters associated with hair follicles (HFs), such as HF density, skin thickness, and HF depth, were augmented in rabbits with the patchiness phenotype relative to the non-patchiness phenotype. A total of 592 differentially expressed genes (DEGs) were identified between the two groups using RNA-sequencing. These included KRT72, KRT82, KRT85, FUT8, SOX9, and WNT5B. The functions of the DEGs were investigated by GO and KEGG enrichment analyses. A candidate gene, KRT82, was selected for further molecular function verification. There was a significant positive correlation between KRT82 expression and HF-related parameters, and KRT82 overexpression and knockdown experiments with rabbit dermal papilla cells (DPCs) showed that it regulated genes related to skin and HF growth and development. Investigation of single nucleotide polymorphisms (SNPs) in the exons and promoter region of KRT82 identified four SNPs in the promoter region but none in the exons. The G.-631G > T, T.-696T > C, G.-770G > T and A.-873 A > C alleles conformed to the Hardy - Weinberg equilibrium, and three identified haplotypes showed linkage disequilibrium. Luciferase reporter assays showed that the core promoter region of KRT82 was located in the - 600 to - 1200 segment, in which the four SNPs were located.

CONCLUSIONS

The morphological characteristics of the patchiness phenotype were analyzed in New Zealand rabbits and DEGs associated with this phenotype were identified by RNA-sequencing. The biological functions of the gene KRT82 associated with this phenotype were analyzed, and four SNPs were identified in the promoter region of the gene. These findings suggest that KRT82 may be a potential biomarker for the breeding of experimental New Zealand rabbits.

CSN1S1, CSN3 and LPL: Three Validated Gene Polymorphisms Useful for More Sustainable Dairy Production in the Mediterranean River Buffalo

The search for DNA polymorphisms useful for the genetic improvement of dairy farm animals has spanned more than 40 years, yielding relevant findings in cattle for milk traits, where the best combination of alleles for dairy processing has been found in casein genes and in DGAT1. Nowadays, similar results have not yet been reached in river buffaloes, despite the availability of advanced genomic technologies and accurate phenotype records. The aim of the present study was to investigate and validate the effect of four single nucleotide polymorphisms (SNP) in the CSN1S1, CSN3, SCD and LPL genes on seven milk traits in a larger buffalo population. These SNPs have previously been reported to be associated with, or affect, dairy traits in smaller populations often belonging to one farm. A total of 800 buffaloes were genotyped. The following traits were individually recorded, monthly, throughout each whole lactation period from 2010 to 2021: daily milk yield (dMY, kg), protein yield (dPY, kg) and fat yield (dFY, kg), fat and protein contents (dFP, % and dPP, %), somatic cell count (SCC, 103 cell/mL) and urea (mg/dL). A total of 15,742 individual milk test day records (2496 lactations) were available for 680 buffalo cows, with 3.6 ± 1.7 parities (from 1 to 13) and an average of 6.1 ± 1.2 test day records per lactation. Three out four SNPs in the CSN1S1, CSN3 and LPL genes were associated with at least one of analyzed traits. In particular, the CSN1S1 (AJ005430:c.578C>T) gave favorable associations with all yield traits (dMY, p = 0.022; dPY, p = 0.014; dFY, p = 0.029) and somatic cell score (SCS, p = 0.032). The CSN3 (HQ677596: c.536C>T) was positively associated with SCS (p = 0.005) and milk urea (p = 0.04). Favorable effects on daily milk yield (dMY, p = 0.028), fat (dFP, p = 0.027) and protein (dPP, p = 0.050) percentages were observed for the LPL. Conversely, the SCD did not show any association with milk traits. This is the first example of a confirmation study carried out in the Mediterranean river buffalo for genes of economic interest in the dairy field, and it represents a very important indication for the preselection of young bulls destined for breeding programs aimed at more sustainable dairy production.

Genetic variability among and within domestic Old and New World camels at the α-lactalbumin gene (LALBA) reveals new alleles and polymorphisms responsible for differential expression

α-Lactalbumin (α-LA), which is encoded by the LALBA gene, is a major whey protein that binds to Ca2+ and facilitates lactose synthesis as a regulatory subunit of the synthase enzyme complex. In addition, it has been shown to play central roles in immune modulation, cell-growth regulation, and antimicrobial activity. In this study, a multitechnical approach was used to fully characterize the LALBA gene and its variants in both coding and regulatory regions for domestic camelids (dromedary, Bactrian camel, alpaca, and llama). The gene analysis revealed a conserved structure among the camelids, but a slight difference in size (2,012 bp on average) due to intronic variations. Promoters were characterized for the transcription factor binding sites (11 found in total). Intraspecies sequence comparison showed 36 SNPs in total (2 in the dromedary, none in the Bactrian camel, 22 in the alpaca, and 12 in the llama), whereas interspecies comparison showed 86 additional polymorphic sites. Eight SNPs were identified as trans-specific polymorphisms, and 2 of them (g.112A>G and g.1229A>G) were particularly interesting in the New World camels. The first creates a new binding site for transcription factor SP1. An enhancing effect of the g.112G variant on the expression was demonstrated by 3 independent pGL3 gene reporter assays. The latter is responsible for the p.78Ile>Val AA replacement and represents novel allelic variants (named LALBA A and B). A link to protein variants has been established by isoelectric focusing (IEF), and bioinformatics analysis revealed that carriers of valine (g.1229G) have a higher glycosylation rate. Genotyping methods based on restriction fragment length polymorphism (PCR-RFLP) were set up for both SNPs. Overall, adenine was more frequent (0.54 and 0.76) at both loci. Four haplotypes were found, and the AA and GA were the most common with a frequency of 0.403 and 0.365, respectively. Conversely, a putative biological gain characterizes the haplotype GG. Therefore, opportunities for rapid directional selection can be realized if this haplotype is associated with favorable milk protein properties. This study adds knowledge at the gene and protein level for α-LA (LALBA) in camelids and importantly contributes to a relatively unexplored research area in these species.

Polymorphisms at Candidate Genes for Fat Content and Fatty Acids Composition: Effects on Sheep Milk Production and Fatty Acid Profile Using Two Dietary Supplementations

The nutritional value of sheep's milk and its derivatives is influenced by the lipid fraction, which is affected by diet and genetics. This study aimed to explore the genetic variations in the DGAT1 and SCD genes and assessed the impact of the DGAT1 genotype on milk quality in Valle del Belìce sheep, considering diet supplementation with carob pulp and barley grain. Among the potentially polymorphic sites, only DGAT1 g.127 C > A and SCD g.87 C > A showed variability. The DGAT1 genotype did not significantly impact milk yield and composition, except for higher urea content in the CA genotypes than in the CC ones. Carob pulp increased the milk fat content compared to barley grain. Genetic variation in DGAT1 was associated with changes in the milk fatty acid profile; specifically, the CA genotype exhibited higher levels of short-chain fatty acids and lower levels of polyunsaturated fatty acids compared to the CC genotype. Carob pulp supplementation increased saturated fatty acids and reduced unsaturated fractions, leading to milk with higher atherogenic and thrombogenic indices. No significant interaction was found between genotype and diet. This study provides insights into the genetic and dietary factors influencing sheep's milk composition. Further research is needed to understand the impact of these genetic variations on milk production and composition, as well as to determine optimal levels of carob pulp for improving fat percentage and promoting sustainable sheep breeding practices.

The ovine HIAT1 gene: mRNA expression, InDel mutations, and growth trait associations

Background

The hippocampal abundant transcript 1 (HIAT1) gene, also known as major facilitator superfamily domain-containing 14A (MFSD14A), encodes for a transmembrane transporter protein and has been previously shown to be associated with milk production in buffalo and sheep breeds, as well as growth traits in chicken and goats. However, tissue level distribution of the ovine HIAT1 gene, as well as its effect on body morphometric traits in sheep, has yet to be studied.

Methods

The HIAT1 mRNA expression profile of Lanzhou fat-tailed (LFT) sheep was determined by quantitative real-time PCR (qPCR). A total of 1498 sheep of three indigenous Chinese sheep breeds were PCR-genotyped for polymorphisms of HIAT1 gene. Student's t-test was used to observe the association between the genotype and sheep morphometric traits.

Results

HIAT1 was widely expressed in all examined tissues, and was particularly abundant in the testis of male LFT sheep. Additionally, a 9-bp insertion mutation (rs1089950828) located within the 5'-upstream region of HIAT1 was investigated in Luxi black-headed (LXBH) sheep and Guiqian semi-fine wool (GSFW) sheep. The wildtype allele frequency 'D' was found to be more prevalent than that of the mutant allele 'I'. Furthermore, low genetic diversity was confirmed in all sampled sheep populations. Subsequent association analyses indicated an association between the 9-bp InDel mutation of interest and the morphometric traits of LXBH and GSFW sheep. Furthermore, yearling ewes with a heterozygous genotype (ID) demonstrated smaller body sizes, while yearling rams and adult ewes with the heterozygous genotype were found to have overall better growth performance.

Conclusion

These findings imply that functional InDel polymorphism (rs1089950828) has the potential to be utilized for marker-assisted selection (MAS) of growth traits in domestic Chinese sheep populations.

Comparative metabolomics analysis of milk components between Italian Mediterranean buffaloes and Chinese Holstein cows based on LC-MS/MS technology

Buffalo and cow milk have a very different composition in terms of fat, protein, and total solids. For a better knowledge of such a difference, the milk metabolic profiles and characteristics of metabolites was investigated in Italian Mediterranean buffaloes and Chinese Holstein cows were investigated by liquid chromatography tandem-mass spectrometry (LC-MS/MS) in this study. Totally, 23 differential metabolites were identified to be significantly different in the milk from the two species of which 15 were up-regulated and 8 down-regulated in Italian Mediterranean buffaloes. Metabolic pathway analysis revealed that 4 metabolites (choline, acetylcholine, nicotinamide and uric acid) were significantly enriched in glycerophospholipid metabolism, nicotinate and nicotinamide metabolism, glycine, serine and threonine metabolism, as well as purine metabolism. The results provided further insights for a deep understanding of the potential metabolic mechanisms responsible for the different performance of Italian Mediterranean buffaloes' and Chinese Holstein cows' milk. The findings will offer new tools for the improvement and novel directions for the development of dairy industry.

Effect of Dietary Palm Kernel Oil on the Quality, Fatty Acid Profile, and Sensorial Attributes of Young Bull Meat

Lipid supplementation through vegetable oils in diets for ruminants can be a nutritional strategy to increase energy density, manipulate ruminal fermentation and change the physicochemical composition and sensorial properties of meat. This study evaluated the optimal dietary inclusion of palm kernel oil (PKO) for Nellore bulls on meat quality. The diets consisted of 0.0, 11.5, 23.0, and 34.6 g/kg dry matter (DM) PKO levels. PKO inclusion did not influence the centesimal composition, pH, color indices, water holding capacity, cooking loss, or shear force of the beef. There were linear increases in the concentrations of lauric acid (C12:0) and myristic acid (C14:0) in the bull's meat. However, palmitic acid (C16:0), oleic acid (C18:0), vaccenic acid (t-11-C18:1) and conjugated linoleic acid (CLA), ∑n - 6, ∑n - 3, ∑n - 6/∑n 3, the hypocholesterolemic: hypercholesterolemic ratio of the fatty acid content, and the thrombogenicity index were not affected. There were linear reductions in the oleic acid meat concentration (c-9-C18:1) and elongated enzymatic activity when PKO was added to the bull diet. The atherogenicity index increased linearly due to PKO inclusion in the bull diet. No effect of the inclusion of PKO on meat flavor, perception of tenderness, juiciness, or global acceptance from the sensorial evaluation was recorded. The inclusion of PKO up to 34.6 g/kg DM can be recommended to supplement young bulls with no effects on meat composition and quality characteristics.

Signatures of selection reveal candidate genes involved in production traits in Chinese crossbred buffaloes

Identification of selection signature is important for a better understanding of genetic mechanisms that affect phenotypic differentiation in livestock. However, the genome-wide selection responses have not been investigated for the production traits of Chinese crossbred buffaloes. In this study, an SNP data set of 133 buffaloes (Chinese crossbred buffalo, n = 45; Chinese local swamp buffalo, n = 88) was collected from the Dryad Digital Repository database (https://datadryad.org/stash/). Population genetics analysis showed that these buffaloes were divided into the following 2 groups: crossbred buffalo and swamp buffalo. The crossbred group had higher genetic diversity than the swamp group. Using 3 complementary statistical methods (integrated haplotype score, cross population extended haplotype homozygosity, and composite likelihood ratio), a total of 31 candidate selection regions were identified in the Chinese crossbred population. Here, within these candidate regions, 25 genes were under the putative selection. Among them, several candidate genes were reported to be associated with production traits. In addition, we identified 13 selection regions that overlapped with bovine QTLs that were mainly involved in milk production and composition traits. These results can provide useful insights regarding the selection response for production traits of Chinese crossbred buffalo, as identified candidate genes influence production performance.

FASN, SCD1 and ANXA9 gene polymorphism as genetic predictors of the fatty acid profile of sheep milk

In this study, single nucleotide polymorphisms (SNPs) in the ANXA9 (annexin 9), FASN (fatty acid synthase) and SCD1 (stearoyl-CoA desaturase 1) genes were analyzed as factors influencing fatty acid profiles in milk from Zošľachtená valaška sheep. SNP in selected genes was identified using polymerase chain reaction (PCR) and restriction fragment length polymorphism (PCR–RFLP). The long-chain fatty acids profile in sheep milk was identified by gas chromatography. Statistical analysis of the SCD1/Cfr13I polymorphism showed that the milk of the homozygous AA animals was characterized by a lower (P < 0.05) share of C4:0, C6:0, C8:0, C10:0, C12:0, C14:0 in comparison to the homozygous CC sheep. The milk of heterozygous sheep was characterized by a higher (P < 0.05) proportion of C13:0 acid compared to the milk of sheep with the homozygous AA type. A higher (P < 0.05) level of saturated fatty acids (SFA) was found in the milk of CC genotype sheep compared to the AA genotype. Our results lead to the conclusion that the greatest changes were observed for the SCD1/Cfr13I polymorphism and the least significant ones for FASN/AciI. Moreover, it is the first evidence that milk from sheep with SCD1/Cfr13I polymorphism and the homozygous AA genotype showed the most desirable fatty acids profile.

Transcriptional profiling of buffalo mammary gland with different milk fat contents

Milk fat is the most important energy substance in milk and contributes to its quality and health benefits. Water buffalo milk is well known for its high milk quality with higher fat contents compared with cattle milk. Dehong buffalo is a unique local swamp breed in Yunnan Province with higher milk fat and excellent milk quality which provides a good model for the investigation of the molecular mechanisms of milk fat deposition. In this study, we used RNA-seq to obtain mammary tissue transcriptomics of buffalo with different milk fat phenotypes including high(H), medium (M)and low (L) fat content groups. Comparative analyses of buffalo among three groups yielded differentially expressed genes (DEGs). Analyzing the number of different genes among H_VS_L, H_VS_M, and M_VS_L showed the same expression pattern between H_VS_M. The increasing expression levels of genes including CSN1S1, BTN1A1, LALBA, ALDH1L2, SCD and MUC15, and down-regulated expression levels of genes containing CCL2, CRABP2, ADTRP, CLU and C4A in H_VS_L and M_VS_L were found. GO and KEGG enriched pathways revealed these DEGs involved in milk protein and fat as well as immune response. The findings would enhance the understanding of the interplay between the milk composition and immune response, which suggests that the immune capacity should be considered when we tried to improve the milk quality.

lncSAMM50 Enhances Adipogenic Differentiation of Buffalo Adipocytes With No Effect on Its Host Gene

Fat deposition is one of the most important traits that are mediated by a set of complex regulatory factors in meat animals. Several researches have revealed the significant role of long non-coding RNAs (lncRNAs) in fat deposition while the precise regulatory mechanism is still largely elusive. In this study, we investigated the lncRNA profiles of adipose and muscle tissues in buffalo by using the Illumina HiSeq 3000 platform. In total, 43,809 lncRNAs were finally identified based on the computer algorithm. A comparison analysis revealed 241 lncRNAs that are differentially expressed (DE) in adipose and muscle tissues. We focused on lncSAMM50, a DE lncRNA that has a high expression in adipose tissue. Sequence alignment showed that lncSAMM50 is transcribed from the antisense strand of the upstream region of sorting and assembly machinery component 50 homolog (SAMM50), a gene involved in the function of mitochondrion and is subsequently demonstrated to inhibit the adipogenic differentiation of 3T3-L1 adipocyte cells in this study. lncSAMM50 is highly expressed in adipose tissue and upregulated in the mature adipocytes and mainly exists in the nucleus. Gain-of-function experiments demonstrated that lncSAMM50 promotes the adipogenic differentiation by upregulating adipogenic markers but with no effect on its host gene SAMM50 in buffalo adipocytes. These results indicate that lncSAMM50 enhances fat deposition in buffalo and provide a new factor for the regulatory network of adipogenesis.

Genetic Association of PPARGC1A Gene Single Nucleotide Polymorphism with Milk Production Traits in Italian Mediterranean Buffalo

PPARGC1A gene plays an important role in the activation of various important hormone receptors and transcriptional factors involved in the regulation of adaptive thermogenesis, gluconeogenesis, fiber-type switching in skeletal muscle, mitochondrial biogenesis, and adipogenesis, regulating the reproduction and proposed as a candidate gene for milk-related traits in cattle. This study identified polymorphisms in the PPARGC1A gene in Italian Mediterranean buffaloes and their associations to milk production and quality traits (lactation length, peak milk yield, fat and protein yield, and percentage). As a result, a total of seven SNPs (g.-78A>G, g.224651G>C, g.286986G>A, g.304050G>A, g.325647G>A, g.325817T>C, and g.325997G>A) were identified by DNA pooled sequencing. Analysis of productivity traits within the genotyped animals revealed that the g.286986G>A located at intron 4 was associated with milk production traits, but the g.325817T>C had no association with milk production. Polymorphisms in g.-78A>G was associated with peak milk yield and milk yield, while g.304050G>A and g.325997 G>A were associated with both milk yield and protein percentage. Our findings suggest that polymorphisms in the buffalo PPARGC1A gene are associated with milk production traits and can be used as a candidate gene for milk traits and marker-assisted selection in the buffalo breeding program.

The distribution of runs of homozygosity in the genome of river and swamp buffaloes reveals a history of adaptation, migration and crossbred events

Background

Water buffalo is one of the most important livestock species in the world. Two types of water buffalo exist: river buffalo (Bubalus bubalis bubalis) and swamp buffalo (Bubalus bubalis carabanensis). The buffalo genome has been recently sequenced, and thus a new 90 K single nucleotide polymorphism (SNP) bead chip has been developed. In this study, we investigated the genomic population structure and the level of inbreeding of 185 river and 153 swamp buffaloes using runs of homozygosity (ROH). Analyses were carried out jointly and separately for the two buffalo types.

Results

The SNP bead chip detected in swamp about one-third of the SNPs identified in the river type. In total, 18,116 ROH were detected in the combined data set (17,784 SNPs), and 16,251 of these were unique. ROH were present in both buffalo types mostly detected (~ 59%) in swamp buffalo. The number of ROH per animal was larger and genomic inbreeding was higher in swamp than river buffalo. In the separated datasets (46,891 and 17,690 SNPs for river and swamp type, respectively), 19,760 and 10,581 ROH were found in river and swamp, respectively. The genes that map to the ROH islands are associated with the adaptation to the environment, fitness traits and reproduction.

Conclusions

Analysis of ROH features in the genome of the two water buffalo types allowed their genomic characterization and highlighted differences between buffalo types and between breeds. A large ROH island on chromosome 2 was shared between river and swamp buffaloes and contained genes that are involved in environmental adaptation and reproduction.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12711-021-00616-3.

Complete CSN1S2 Characterization, Novel Allele Identification and Association With Milk Fatty Acid Composition in River Buffalo

The αs2-casein is one of the phosphoproteins secreted in all ruminants' milk, and it is the most hydrophilic of all caseins. However, this important gene (CSN1S2) has not been characterized in detail in buffaloes with only two alleles detected (reported as alleles A and B), and no association studies with milk traits have been carried out unlike what has been achieved for other species of ruminants. In this study, we sequenced the whole gene of two Mediterranean river buffalo homozygotes for the presence/absence of the nucleotide C (g.7539G>C) realized at the donor splice site of exon 7 and, therefore, responsible for the skipping of the same exon at mRNA level (allele B). A high genetic variability was found all over the two sequenced CSN1S2 alleles. In particular, 74 polymorphic sites were found in introns, six in the promoter, and three SNPs in the coding region (g.11072C>T, g.12803A>T, and g.14067A>G) with two of them responsible for amino acid replacements. Considering this genetic diversity, those found in the database and the SNP at the donor splice site of exon 7, it is possible to deduce at least eight different alleles (CSN1S2 A, B, B1, B2, C, D, E, and F) responsible for seven different possible translations of the buffalo αs2-casein. Haplotype data analysis suggests an evolutionary pathway of buffalo CSN1S2 gene consistent with our proposal that the published allele CSN1S2 A is the ancestral αs2-CN form, and the B2 probably arises from interallelic recombination (single crossing) between the alleles D and B (or B1). The allele CSN1S2 C is of new identification, while CSN1S2 B, B1, and B2 are deleted alleles because all are characterized by the mutation g.7539G>C. Two SNPs (g.7539G>C and g.14067A>G) were genotyped in 747 Italian buffaloes, and major alleles had a relative frequency of 0.83 and 0.51, respectively. An association study between these SNPs and milk traits including fatty acid composition was carried out. The SNP g.14067A>G showed a significant association (P < 0.05) on the content of palmitic acid in buffalo milk, thus suggesting its use in marker-assisted selection programs aiming for the improvement of buffalo milk fatty acid composition.

Genetics of Omega-3 Long-Chain Polyunsaturated Fatty Acid Metabolism and Meat Eating Quality in Tattykeel Australian White Lambs

Meat eating quality with a healthy composition hinges on intramuscular fat (IMF), fat melting point (FMP), tenderness, juiciness, flavour and omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) content. These health-beneficial n-3 LC-PUFA play significant roles in optimal cardiovascular, retinal, maternal and childhood brain functions, and include alpha linolenic (ALA), eicosapentaenoic (EPA), docosahexaenoic (DHA) and docosapentaenoic (DPA) acids. The primary objective of this review was to access, retrieve, synthesise and critically appraise the published literature on the synthesis, metabolism and genetics of n-3 LC-PUFA and meat eating quality. Studies on IMF content, FMP and fatty acid composition were reviewed to identify knowledge gaps that can inform future research with Tattykeel Australian White (TAW) lambs. The TAW is a new sheep breed exclusive to MARGRA brand of lamb with an outstanding low fat melting point (28-39°C), high n-3 LC-PUFA EPA+DHA content (33-69mg/100g), marbling (3.4-8.2%), tenderness (20.0-38.5N) and overall consumer liking (7.9-8.5). However, correlations between n-3 LC-PUFA profile, stearoyl-CoA desaturase (SCD), fatty acid binding protein 4 (FABP4), fatty acid synthase (FASN), other lipogenic genes and meat quality traits present major knowledge gaps. The review also identified research opportunities in nutrition-genetics interactions aimed at a greater understanding of the genetics of n-3 LC-PUFA, feedlot finishing performance, carcass traits and eating quality in the TAW sheep. It was concluded that studies on IMF, FMP and n-3 LC-PUFA profiles in parental and progeny generations of TAW sheep will be foundational for the genetic selection of healthy lamb eating qualities and provide useful insights into their correlations with SCD, FASN and FABP4 genes.

Sequencing of lipoprotein lipase gene in the Mediterranean river buffalo identified novel variants affecting gene expression

Lipoprotein lipase (LPL) is a key enzyme for lipid metabolism, playing a fundamental role in the composition of fat in adipose tissue and milk. The LPL gene has been seldom investigated in dairy ruminants and barely studied in river buffalo (Bubalus bubalis). The aim of this work was to explore the genetic diversity of LPL and its promoter and to identify functional mutations, using a combined approach based on sequencing, dual-color electrophoretic mobility shift assay, and quantitative PCR. Thirteen consensus sequences for transcription factors were found in the promoter. Eleven SNP were detected, and the attention was focused on the SNP with potential functional effects: g.-446A>G, because the presence of G created a consensus motif for the transcription factor Sp1, and g.107A>G, which was the only exonic SNP. We developed PCR-RFLP methods for genotyping the 2 SNP and calculated the allele frequencies. A strong linkage disequilibrium (D' = 1; r² = 0.903) was found between the 2 SNP. The dual-color electrophoretic mobility shift assay demonstrated that only genotype g.-446GG allowed the binding of the Sp1 transcription factor, resulting in overexpression of the gene (~2.5 fold), as confirmed by the quantitative PCR results. Haploinsufficiency is proposed as a regulation mechanism. This study adds further knowledge on the structure of the LPL gene and its expression in river buffalo, with potential effects on milk qualitative and quantitative production.

A Functional 3' UTR Polymorphism of FADS2 Affects Cow Milk Composition through Modifying Mir-744 Binding

Simple Summary

Fatty acid desaturase 2 (FADS2) is the rate-limiting enzyme involved in the synthesis of long-chain polyunsaturated fatty acids (LC-PUFAs). Many studies have suggested that polymorphisms in the FADS2 gene can modify its delta-6 desaturase activity. However, much remains unknown in regards to the regulatory mechanisms interpreting how DNA variants influence the function of FADS2. A previous study has suggested that c.1571G>A is located within the miR-744 binding site, indicating that this single nucleotide polymorphism (SNP) may be functional. Therefore, the aim of the present study was to determine the association of SNP c.1571G>A with milk PUFAs content and to further elucidate how this SNP contributes to regulating FADS2 expression. Our results support the use of SNP c.1571G>A as a potential genetic marker in the selective breeding of cattle to increase beneficial FAs content in milk.

Abstract

This study determined the associations of FADS2 c.1571G>A with milk FAs content and revealed that cows with the GG genotype had improved levels of delta-6 desaturase substrates (linoleic acid, C18:2n-6; p < 0.001) and decreased levels of desaturase products (gamma-linolenic acid, C18:3n-6; p < 0.001), indicating a reduction in FADS2 expression or delta-6 desaturase activity caused by this polymorphism. Computer alignment demonstrated that c.1571G>A occurred within a potential miR-744 binding site. When the c.1571G allele was present, the luciferase activity of reporter constructs was significantly suppressed by miR-744, while no such effect was observed with the A allele. Overexpression of miR-744 in bovine mammary epithelial cells (with the 1571GG genotype) downregulated FADS2 expression at both mRNA and protein levels. In contrast, inhibition of endogenous miR-744 with a specific inhibitor dramatically upregulated FADS2 expression. Taken together, these lines of evidence indicated that the c.1571A minor allele abolished the ability of miR-744 to bind FADS2, with a consequent increase in FADS2 expression levels and synthesis of omega-6 LC-PUFAs.