Genetic diversity, population structure and origin of the native goats in Central Laos.

Maintaining genetic diversity and variation in livestock populations is critical for natural and artificial selection promoting genetic improvement while avoiding problems due to inbreeding. In Laos, there are concerns that there has been a decline in genetic diversity and a rise in inbreeding among native goats in their village-based smallholder system. In this study, we investigated the genetic diversity of Lao native goats in Phin, Songkhone and Sepon districts in Central Laos for the first time using Illumina's Goat SNP50 BeadChip. We also explored the genetic relationships between Lao goats with 163 global goat populations from 36 countries. Our results revealled a close genetic relationship between Lao native goats and Chinese, Mongolian and Pakistani goats, sharing ancestries with Guangfen, Jining Grey and Luoping Yellow breeds (China) and Teddi goats (Pakistan). The observed (Ho) and expected (He) heterozygosity were 0.292 and 0.303 (Laos), 0.288 and 0.288 (Sepon), 0.299 and 0.308 (Phin) and 0.289 and 0.305 (Songkhone), respectively. There was low to moderate genetic differentiation (FST: 0.011-0.043) and negligible inbreeding coefficients (FIS: -0.001 to 0.052) between goat districts. The runs of homozygosity (ROH) had an average length of 5.92-6.85 Mb, with short ROH segments (1-5 Mb length) being the most prevalent (66.34%). Longer ROH segments (20-40 and >40 Mb length categories) were less common, comprising only 4.81% and 1.01%, respectively. Lao goats exhibit moderate genetic diversity, low-inbreeding levels and adequate effective population size. Some genetic distinctions between Lao goats may be explained by geographic and cultural features.

The effect of sex and dietary crude protein level on nutrient transporter gene expression and cecal microbiota populations in broiler chickens.

It is well known that male and female broilers differ in their growth performance and that many physiological factors contribute to this difference. The aim of this experiment is to investigate if there are differences between male and female broilers in cecal microbiota and nutrient transporter gene expression and if these differences play a role in the growth performance of broilers. The possible effect of protein level and its interaction with sex on microbiota and expression of the nutrient transporters were also investigated. Samples were collected from male and female birds fed either standard crude protein (SCP) or reduced crude protein diets (RCP) at the age of d 35. The experiment was designed as a 2 × 2 factorial arrangement of treatments consisting of 448 Cobb 500 broilers assigned to 32-floor pens with 4 treatments, 8 replicates, and 14 birds per pen for performance measurements. The factors were sex (male or female) and dietary crude protein (CP) level (standard or reduced). Body weight gain (BWG), feed intake and feed conversion ratio were recorded for each pen. Sex had a significant effect on BWG and FCR (P < 0.001) where males had a significantly higher BWG and better FCR compared to females. There was a significant interaction between sex and protein level on feed intake (FI) (P < 0.05), where male birds had a higher FI compared to female birds only when the birds were fed SCP but not RCP diets. There was a significant interaction between CP level and sex on the expression of CAT2 (P = 0.02) and PEPT2 (P = 0.026) where the genes were significantly upregulated in females but only when the RCP diet was fed. The RCP diet upregulated the expression of BoAT (P = 0.03) as a main effect. Female birds had significantly higher expression of the PepT-2 gene compared to the males. The alpha diversity of the cecal microbiota showed differences among the treatments. The Shannon diversity index was statistically higher (P = 0.036) for males fed the SCP diet and the Chao1 index for evenness was statistically higher (P = 0.027) in females fed the SCP diet. There was also a difference in the relative abundance of the 15 most common genera found in the cecal content of the broilers in this experiment and lastly, the differential composition of microbiota between the different treatments was also significantly different. This study suggests that chickens are able to compensate for a reduction in AA substrates when fed a low CP diet through the upregulation of certain AA transporters, females may adapt to low CP diets better by such upregulation compared to males, and lastly, sex has an effect on the cecal microbial population and these differences contribute towards the performance differences between male and female broilers.

QTLs and Candidate Genes Associated with Semen Traits in Merino Sheep.

Ram semen traits play a significant role in conception outcomes, which in turn may influence reproductive efficiency and the overall productivity and profitability of sheep enterprises. Since hundreds of ewes may be inseminated from a single ejaculate, it is important to evaluate semen quality prior to use in sheep breeding programs. Given that semen traits have been found to be heritable, genetic variation likely contributes to the variability observed in these traits. Identifying such genetic variants could provide novel insights into the molecular mechanisms underlying variability in semen traits. Therefore, this study aimed to identify quantitative trait loci (QTLs) associated with semen traits in Merino sheep. A genome-wide association study (GWAS) was undertaken using 4506 semen collection records from 246 Merino rams collected between January 2002 and May 2021. The R package RepeatABEL was used to perform a GWAS for semen volume, gross motility, concentration, and percent post-thaw motility. A total of 35 QTLs, located on 16 Ovis aries autosomes (OARs), were significantly associated with either of the four semen traits in this study. A total of 89, 95, 33, and 73 candidate genes were identified, via modified Bonferroni, within the QTLs significantly associated with volume, gross motility, concentration, and percent post-thaw motility, respectively. Among the candidate genes identified, SORD, SH2B1, and NT5E have been previously described to significantly influence spermatogenesis, spermatozoal motility, and high percent post-thaw motility, respectively. Several candidate genes identified could potentially influence ram semen traits based on existing evidence in the literature. As such, validation of these putative candidates may offer the potential to develop future strategies to improve sheep reproductive efficiency. Furthermore, Merino ram semen traits are lowly heritable (0.071-0.139), and thus may be improved by selective breeding.

Parameter estimation and assessment of bias in genetic evaluation of carcass traits in Hanwoo cattle using real and simulated data.

Most carcass and meat quality traits are moderate to highly heritable, indicating that they can be improved through selection. Genetic evaluation for these types of traits is performed using performance data obtained from commercial and progeny testing evaluation. The performance data from commercial farms are available in large volume, however, some drawbacks have been observed. The drawback of the commercial data is mainly due to sorting of animals based on live weight prior to slaughter, and this could lead to bias in the genetic evaluation of later measured traits such as carcass traits. The current study has two components to address the drawback of the commercial data. The first component of the study aimed to estimate genetic parameters for carcass and meat quality traits in Korean Hanwoo cattle using a large sample size of industry-based carcass performance records (n = 469,002). The second component of the study aimed to describe the impact of sorting animals into different contemporary groups based on an early measured trait and then examine the effect on the genetic evaluation of subsequently measured traits. To demonstrate our objectives, we used real performance data to estimate genetic parameters and simulated data was used to assess the bias in genetic evaluation. The results of our first study showed that commercial data obtained from slaughterhouses is a potential source of carcass performance data and useful for genetic evaluation of carcass traits to improve beef cattle performance. However, we observed some harvesting effect which leads to bias in genetic evaluation of carcass traits. This is mainly due to the selection of animal based on their body weight before arrival to slaughterhouse. Overall, the non-random allocation of animals into a contemporary group leads to a biased estimated breeding value in genetic evaluation, the severity of which increases when the evaluation traits are highly correlated.

Heritability and Genetic Parameters for Semen Traits in Australian Sheep.

Semen characteristics including volume, gross motility, spermatozoal concentration, and percent post-thaw motility are routinely assessed to determine the quality and quantity of an ejaculate prior to use in artificial breeding programs. Currently, artificial breeding programs in sheep place relatively little emphasis on ram-side factors, such as the fertilising potential of an ejaculate, which may contribute to variability in conception outcomes. Estimating genetic parameters for ejaculate quality and quantity traits could provide insights into whether selective breeding can be used to improve such ram-side traits, improving ovine reproductive performance and farm profitability. Therefore, in this study, a total of 11,470 ejaculate records, including data for ejaculate volume, gross motility, spermatozoal concentration, and percent post-thaw motility, collected over a 20-year period was used to estimate genetic parameters in sheep. Univariate and bivariate mixed model analysis was performed including a variety of fixed effects such as breed, age at collection, centre of collection, collection number, season of collection, and method of collection; and the permanent environmental effects associated with each ram, stud and year of collection, and the breeding value of rams included as random effects. The heritability for ejaculate volume, gross motility, concentration, and percent post-thaw motility was estimated to be 0.161, 0.170, 0.089, and 0.081. Repeatability estimates were moderate, ranging between 0.4126 and 0.5265. Overall, results indicate that semen traits are lowly heritable and moderately repeatable, indicating that these traits are significantly influenced by environmental variables.

Phytogenic Blend Improves Intestinal Health and Reduces Obesity, Diabetes, Cholesterol and Cancers: A Path toward Customised Supplementation.

Poultry production is among the most challenging industries for pathogen control. High animal density and abundance of faecal material demand strict biosecurity measures and continual vigilance in monitoring animal health parameters. Despite this vigilance, dealing with disease outbreaks is a part of farmers' routines. Phytogenic feed additives comprised of herbs, spices, essential oils, and oleoresins have potent antimicrobial and anti-inflammatory actions. Related studies are gaining substantial interest in human and animal health worldwide. In this study, a commercial blend phytogenic feed additive was supplemented to layers in an industrial free-range production system with 20,000 birds in both control and treatment groups. At the end of the trial, the ileum tissue was sampled for RNAseq transcriptomic analysis to study the host reaction to the supplement. Phytogenic supplement significantly inhibited four cholesterol-related pathways and reduced the Arteriosclerosis disease category towards improved cardiovascular health. The supplemented birds exhibited reduced disease susceptibility for 26 cancer categories with p-values in the range from 5.23 × 10-4 to 1.02 × 10-25. Major metabolic shifts in Lipid metabolism in combination with Carbohydrate metabolism have resulted in a decrease in the Obesity category, altering the ratio of fat and carbohydrate metabolism toward lower fat storage.

Genome-wide association study for carcass traits in Hanwoo cattle using additional relatives' information of non-genotyped animals.

The aim of this study was to find significant genomic regions associated with carcass traits in Hanwoo cattle and to compare the benefit of using additional information from non-genotyped animals. Imputed whole-genome sequence data were used along with phenotypic data on 13 715 genotyped animals as well as phenotypes of 440 284 non-genotyped animals that were offspring of 454 genotyped sires. For carcass weight, 15 083 SNPs in 33 QTL regions and 313 candidate genes were identified. We found 410 SNPs in 17 QTL regions containing 122 candidate genes for back fat thickness. In total, 656 SNPs in 19 QTLs with 137 candidate genes for eye muscle area and 79 SNPs in 12 QTL regions with 77 candidate genes were identified for marbling score. The most important candidate genes included ZFAT, TG, PLAG1, CHCHD7, and TOX for carcass weight and eye muscle area, NOG for back fat thickness, and EVOVL5 for marbling score. This study showed that the use of phenotypic records on non-genotyped progeny along with imputed whole-genome sequence data increased the power of detecting new significant genomic regions.

Comparison of Clevidipine and Nicardipine for Acute Blood Pressure Reduction in Hemorrhagic Stroke.

BACKGROUND: Intracranial hemorrhage is associated with high mortality and morbidity. Lowering systolic blood pressure (SBP) with an intravenous antihypertensive, such as nicardipine or clevidipine, may reduce the risk of hematoma expansion and rebleeding. Previous studies comparing nicardipine and clevidipine in patients with stroke found no significant difference in blood pressure management. The inclusion of patients with ischemic stroke limited those studies because of convoluted results related to faster door-to-needle times. The purpose of this study was to compare clevidipine with nicardipine in time to goal SBP in hemorrhagic stroke. METHODS: This single-center retrospective observational cohort study evaluated adult hemorrhagic patients with stroke who received clevidipine or nicardipine from January 1, 2015, to December 31, 2020. Patients were excluded if they had trauma-related hemorrhage, received concurrent continuous intravenous antihypertensives, received the study drug for less than 1-h duration, had a less than 24-h washout period between agents, required any dialysis, were pregnant, or were incarcerated. The primary outcome was time to goal SBP. Secondary outcomes included need for additional antihypertensives, percentage of time at goal SBP, all-cause mortality, 30-day readmission, rebleeding, total volume of antihypertensive infusion, hematoma expansion, intensive care unit length of stay (LOS), hospital LOS, and cost of infusion. Safety outcomes included hypotension, severe hypotension, rebound hypertension, bradycardia, tachycardia, onset of atrial fibrillation, and acute kidney injury. RESULTS: Of 89 patients included in this study, 60 received nicardipine and 29 received clevidipine. There was no significant difference between nicardipine and clevidipine in time to goal SBP in the unmatched cohort (30 vs. 45 min; p = 0.73) or the propensity-score-matched cohort (30 vs. 45 min; p = 0.47). Results were not affected by potential confounders in the multiple linear regression. The nicardipine group had a higher total volume from infusion compared with the clevidipine group (1410 vs. 330 mL; p < 0.0001) but significantly lower cost ($99.6 vs. $497.4; p < 0.0001). There were no significant differences in need for additional antihypertensives, percentage of time at goal SBP, all-cause mortality, 30-day readmission, rebleeding, hematoma expansion, intensive care unit LOS, and hospital LOS. Compared with the clevidipine group, the nicardipine group had less rebound hypertension (40% vs. 75.9%; p = 0.0017) and less bradycardia (23.3% vs. 44.8%; p = 0.05). There were no significant differences in hypotension, severe hypotension, tachycardia, and acute kidney injury. CONCLUSIONS: In patients with hemorrhagic stroke, nicardipine appeared to have similar efficacy as clevidipine in SBP reduction, with a more likely reduction of rebound hypertension and drug cost. This retrospective study was underpowered, which may limit these implications. Further prospective studies are warranted to confirm these results.

Necrotic enteritis challenge regulates peroxisome proliferator-1 activated receptors signaling and ß-oxidation pathways in broiler chickens.

Necrotic enteritis (NE) is an important enteric disease in poultry and has become a major concern in poultry production in the post-antibiotic era. The infection with NE can damage the intestinal mucosa of the birds leading to impaired health and, thus, productivity. To gain a better understanding of how NE impacts the gut function of infected broilers, global mRNA sequencing (RNA-seq) was performed in the jejunum tissue of NE challenged and non-challenged broilers to identify the pathways and genes affected by this disease. Briefly, to induce NE, birds in the challenge group were inoculated with 1 mL of Eimeria species on day 9 followed by 1 mL of approximately 108 CFU/mL of a NetB producing Clostridium perfringens on days 14 and 15. On day 16, 2 birds in each treatment were randomly selected and euthanized and the whole intestinal tract was evaluated for lesion scores. Duodenum tissue samples from one of the euthanized birds of each replicate (n = 4) was used for histology, and the jejunum tissue for RNA extraction. RNA-seq analysis was performed with an Illumina RNA HiSeq 2000 sequencer. The differentially expressed genes (DEG) were identified and functional analysis was performed in DAVID to find protein-protein interactions (PPI). At a false discovery rate threshold <0.05, a total of 377 DEG (207 upregulated and 170 downregulated) DEG were identified. Pathway enrichment analysis revealed that DEG were considerably enriched in peroxisome proliferator-activated receptors (PPAR) signaling (P < 0.01) and ß-oxidation pathways (P < 0.05). The DEG were mostly related to fatty acid metabolism and degradation (cluster of differentiation 36 [CD36], acyl-CoA synthetase bubblegum family member-1 [ACSBG1], fatty acid-binding protein-1 and -2 [FABP1] and [FABP2]; and acyl-coenzyme A synthetase-1 [ACSL1]), bile acid production and transportation (acyl-CoA oxidase-2 [ACOX2], apical sodium-bile acid transporter [ASBT]) and essential genes in the immune system (interferon-, [IFN-γ], LCK proto-oncogene, Src family tyrosine kinase [LCK], zeta chain of T cell receptor associated protein kinase 70 kDa [ZAP70], and aconitate decarboxylase 1 [ACOD1]). Our data revealed that pathways related to fatty acid digestion were significantly compromised which thereby could have affected metabolic and immune responses in NE infected birds.

Characterization of Breed Specific Differences in Spermatozoal Transcriptomes of Sheep in Australia.

Reduced reproductive efficiency results in economic losses to the Australian sheep industry. Reproductive success, particularly after artificial insemination, is dependent on a number of contributing factors on both ewe and ram sides. Despite considerable emphasis placed on characterising ewe side contributions, little emphasis has been placed on characterising ram side contributions to conception success. Over 14,000 transcripts are in spermatozoa of other species, which are transferred to the ova on fertilisation. These transcripts conceivably influence early embryonic development and whether conception is successful. Semen was collected (n = 45) across three breeds; Merino, Dohne, and Poll Dorset. Following collection, each ejaculate was split in two; an aliquot was assessed utilising Computer Assisted Semen Analysis (CASA) and the remaining was utilised for RNA extraction and subsequent next-generation sequencing. Overall, 754 differentially expressed genes were identified in breed contrasts and contrast between ejaculates of different quality. Downstream analysis indicated that these genes could play significant roles in a broad range of physiological functions, including maintenance of spermatogenesis, fertilisation, conception, embryonic development, and offspring production performance. Overall results provide evidence that the spermatozoal transcriptome could be a crucial contributing factor in improving reproductive performance as well as in the overall productivity and profitability of sheep industries.

Differential Gene Expression in Longissimus Dorsi Muscle of Hanwoo Steers-New Insight in Genes Involved in Marbling Development at Younger Ages.

The Korean Hanwoo breed possesses a high capacity to accumulate intramuscular fat, which is measured as a marbling score in the beef industry. Unfortunately, the development of marbling is not completely understood and the identification of differentially expressed genes at an early age is required to better understand this trait. In this study, we took muscle samples from 12 Hanwoo steers at the age of 18 and 30 months. From the contrast between age and marbling score, we identified in total 1883 differentially expressed genes (FDR < 0.05 and logarithm fold change ≥ 1.5) with 782 genes up-regulated and 1101 down-regulated. Differences in gene expression were higher between the ages x marbling groups rather than between high and low marbling groups. At 18 months of age, the genes SLC38A4, ABCA10, APOL6, and two novel genes (ENSBTAG00000015330 and ENSBTAG00000046041) were up-regulated in the high marbling group. From the protein-protein interaction network analysis, we identified unique networks when comparing marbling scores between different ages. Nineteen genes (AGT, SERPINE1, ADORA1, FOS, LEP, FOXO1, FOXO3, ADIPOQ, ITGA1, SDC1, SDC4, ITGB3, ITGB4, CXCL10, ACTG2, MX1, EDN1, ACTA2, and ESPL1) were identified to have an important role in marbling development. Further analyses are needed to better understand the role of these genes.

Use of gene expression and whole-genome sequence information to improve the accuracy of genomic prediction for carcass traits in Hanwoo cattle.

BACKGROUND: In this study, we assessed the accuracy of genomic prediction for carcass weight (CWT), marbling score (MS), eye muscle area (EMA) and back fat thickness (BFT) in Hanwoo cattle when using genomic best linear unbiased prediction (GBLUP), weighted GBLUP (wGBLUP), and a BayesR model. For these models, we investigated the potential gain from using pre-selected single nucleotide polymorphisms (SNPs) from a genome-wide association study (GWAS) on imputed sequence data and from gene expression information. We used data on 13,717 animals with carcass phenotypes and imputed sequence genotypes that were split in an independent GWAS discovery set of varying size and a remaining set for validation of prediction. Expression data were used from a Hanwoo gene expression experiment based on 45 animals. RESULTS: Using a larger number of animals in the reference set increased the accuracy of genomic prediction whereas a larger independent GWAS discovery dataset improved identification of predictive SNPs. Using pre-selected SNPs from GWAS in GBLUP improved accuracy of prediction by 0.02 for EMA and up to 0.05 for BFT, CWT, and MS, compared to a 50 k standard SNP array that gave accuracies of 0.50, 0.47, 0.58, and 0.47, respectively. Accuracy of prediction of BFT and CWT increased when BayesR was applied with the 50 k SNP array (0.02 and 0.03, respectively) and was further improved by combining the 50 k array with the top-SNPs (0.06 and 0.04, respectively). By contrast, using BayesR resulted in limited improvement for EMA and MS. wGBLUP did not improve accuracy but increased prediction bias. Based on the RNA-seq experiment, we identified informative expression quantitative trait loci, which, when used in GBLUP, improved the accuracy of prediction slightly, i.e. between 0.01 and 0.02. SNPs that were located in genes, the expression of which was associated with differences in trait phenotype, did not contribute to a higher prediction accuracy. CONCLUSIONS: Our results show that, in Hanwoo beef cattle, when SNPs are pre-selected from GWAS on imputed sequence data, the accuracy of prediction improves only slightly whereas the contribution of SNPs that are selected based on gene expression is not significant. The benefit of statistical models to prioritize selected SNPs for estimating genomic breeding values is trait-specific and depends on the genetic architecture of each trait.

Correction: Weighted Genomic Best Linear Unbiased Prediction for Carcass Traits in Hanwoo Cattle. Genes 2019, 10, 1019.

The authors wish to make the following corrections to this paper [...].

Weighted Genomic Best Linear Unbiased Prediction for Carcass Traits in Hanwoo Cattle.

The genomic best linear unbiased prediction (GBLUP) method has been widely used in routine genomic evaluation as it assumes a common variance for all single nucleotide polymorphism (SNP). However, this is unlikely in the case of traits influenced by major SNP. Hence, the present study aimed to improve the accuracy of GBLUP by using the weighted GBLUP (WGBLUP), which gives more weight to important markers for various carcass traits of Hanwoo cattle, such as backfat thickness (BFT), carcass weight (CWT), eye muscle area (EMA), and marbling score (MS). Linear and different nonlinearA SNP weighting procedures under WGBLUP were evaluated and compared with unweighted GBLUP and traditional pedigree-based methods (PBLUP). WGBLUP methods were assessed over ten iterations. Phenotypic data from 10,215 animals from different commercial herds that were slaughtered at approximately 30-month-old of age were used. All these animals were genotyped using Illumina Bovine 50k SNP chip and were divided into a training and a validation population by birth date on 1 November 2015. Genomic prediction accuracies obtained in the nonlinearA weighting methods were higher than those of the linear weighting for all traits. Moreover, unlike with linear methods, no sudden drops in the accuracy were noted after the peak was reached in nonlinearA methods. The average accuracies using PBLUP were 0.37, 0.49, 0.40, and 0.37, and 0.62, 0.74, 0.67, and 0.65 using GBLUP for BFT, CWT, EMA, and MS, respectively. Moreover, these accuracies of genomic prediction were further increased to 4.84% and 2.70% for BFT and CWT, respectively by using the nonlinearA method under the WGBLUP model. For EMA and MS, WGBLUP was as accurate as GBLUP. Our results indicate that the WGBLUP using a nonlinearA weighting method provides improved predictions for CWT and BFT, suggesting that the ability of WGBLUP over the other models by weighting selected SNPs appears to be trait-dependent.

Estimation of Genetic Parameters by Single-Trait and Multi-Trait Models for Carcass Traits in Hanwoo Cattle.

Hanwoo breed is preferred in South Korea because of the high standards in marbling and the palatability of its meat. Numerous studies have been conducted and are ongoing to increase the meat production and quality in this beef population. The aim of this study was to estimate and compare genetic parameters for carcass traits using BLUPF90 software. Four models were constructed, single trait pedigree model (STPM), single-trait genomic model (STGM), multi-trait pedigree model (MTPM), and multi-trait genomic model (MTGM), using the pedigree, phenotype, and genomic information of 7991 Hanwoo cattle. Four carcass traits were evaluated: Back fat thickness (BFT), carcass weight (CWT), eye muscle area (EMA), and marbling score (MS). Heritability estimates of 0.40 and 0.41 for BFT, 0.33 and 0.34 for CWT, 0.36 and 0.37 for EMA, and 0.35 and 0.38 for MS were obtained for the single-trait pedigree model and the multi-trait pedigree model, respectively, in Hanwoo. Further, the genomic model showed more improved results compared to the pedigree model, with heritability of 0.39 (CWT), 0.39 (EMA), and 0.46 (MS), except for 0.39 (BFT), which may be due to random events. Utilization of genomic information in the form of single nucleotide polymorphisms (SNPs) has allowed more capturing of the variance from the traits improving the variance components.

Combining information from genome-wide association and multi-tissue gene expression studies to elucidate factors underlying genetic variation for residual feed intake in Australian Angus cattle.

BACKGROUND: Genome-wide association studies (GWAS) are extensively used to identify single nucleotide polymorphisms (SNP) underlying the genetic variation of complex traits. However, much uncertainly often still exists about the causal variants and genes at quantitative trait loci (QTL). The aim of this study was to identify QTL associated with residual feed intake (RFI) and genes in these regions whose expression is also associated with this trait. Angus cattle (2190 steers) with RFI records were genotyped and imputed to high density arrays (770 K) and used for a GWAS approach to identify QTL associated with RFI. RNA sequences from 126 Angus divergently selected for RFI were analyzed to identify the genes whose expression was significantly associated this trait with special attention to those genes residing in the QTL regions. RESULTS: The heritability for RFI estimated for this Angus population was 0.3. In a GWAS, we identified 78 SNPs associated with RFI on six QTL (on BTA1, BTA6, BTA14, BTA17, BTA20 and BTA26). The most significant SNP was found on chromosome BTA20 (rs42662073) and explained 4% of the genetic variance. The minor allele frequencies of significant SNPs ranged from 0.05 to 0.49. All regions, except on BTA17, showed a significant dominance effect. In 1 Mb windows surrounding the six significant QTL, we found 149 genes from which OAS2, STC2, SHOX, XKR4, and SGMS1 were the closest to the most significant QTL on BTA17, BTA20, BTA1, BTA14, and BTA26, respectively. In a 2 Mb windows around the six significant QTL, we identified 15 genes whose expression was significantly associated with RFI: BTA20) NEURL1B and CPEB4; BTA17) RITA1, CCDC42B, OAS2, RPL6, and ERP29; BTA26) A1CF, SGMS1, PAPSS2, and PTEN; BTA1) MFSD1 and RARRES1; BTA14) ATP6V1H and MRPL15. CONCLUSIONS: Our results showed six QTL regions associated with RFI in a beef Angus population where five of these QTL contained genes that have expression associated with this trait. Therefore, here we show that integrating information from gene expression and GWAS studies can help to better understand the genetic mechanisms that determine variation in complex traits.

Gene expression of Hanwoo satellite cell differentiation in longissimus dorsi and semimembranosus.

BACKGROUND: Korean Hanwoo cattle are known for their high meat quality, especially their high intramuscular fat compared to most other cattle breeds. Different muscles have very different meat quality traits and a study of the myogenic process in satellite cells can help us better understand the genes and pathways that regulate this process and how muscles differentiate. RESULTS: Cell cultures of Longissimus dorsi muscle differentiated from myoblast into multinucleated myotubes faster than semimembranosus. Time-series RNA-seq identified a total of 13 differentially expressed genes between the two muscles during their development. These genes seem to be involved in determining muscle lineage development and appear to modulate the expression of myogenic regulatory factors (mainly MYOD and MYF5) during differentiation of satellite cells into multinucleate myotubes. Gene ontology enriched terms were consistent with the morphological changes observed in the histology. Most of the over-represented terms and genes expressed during myoblast differentiation were similar regardless of muscle type which indicates a highly conserved myogenic process albeit the rates of differentiation being different. There were more differences in the enriched GO terms during the end of proliferation compared to myoblast differentiation. CONCLUSIONS: The use of satellite cells from newborn Hanwoo calves appears to be a good model to study embryonic myogenesis in muscle. Our findings provide evidence that the differential expression of HOXB2, HOXB4, HOXB9, HOXC8, FOXD1, IGFN1, ZIC2, ZIC4, HOXA11, HOXC11, PITX1, SIM2 and TBX4 genes could be involved in the differentiation of Longissimus dorsi and Semimembranosus muscles. These genes seem to modulate the muscle fate of the satellite cells during myogenesis through a differential expression profile that also controls the expression of some myogenic regulatory factors (MYOD and MYF5). The number of differentially expressed genes across time was unsurprisingly large. In relation to the baseline day 0, there were 631, 155, 175, 519 and 586 DE genes in LD, while in SM we found 204, 0, 615, 761 and 1154 DE genes at days 1, 2, 4, 7 and 14 respectively.