Genome-wide association study shows that microtia in Altay sheep is caused by a 76 bp duplication of HMX1.

Microtia is a congenital malformation of the external ear that can be observed in many species including sheep. However, the genetic basis of microtia still remains unclear. Here, a GWAS was conducted to investigate the genetic basis underlying microtia. A total of 55 samples from 26 microtia and 29 normal animals were genotyped with Illumina OvineHD BeadChip. The strongest significant SNP was identified on OAR6, approximating the evolutionarily conserved region of the HMX1 gene, which is related to congenital malformations of the external ear in other species such as cattle and rats. Sequencing an evolutionarily conserved region surrounding HMX1 revealed a duplication of 76 bp, which is concordant with microtia, suggesting a dominant inheritance mode. Identification of this causal mutation in the HMX1 gene indicates the role of this particular gene in the development of the external ear and provides a genetic marker for selection against microtia.

Relationships between residual feed intake and hepatic mitochondrial function in growing beef cattle.

The objective of this study was to evaluate the relationship between hepatic mitochondrial function and residual feed intake (RFI) in growing beef cattle. In Trial 1, RFI was measured in 29 Angus heifers (initial BW = 258.0 ± 24.9 kg) from divergent IGF-I selection lines created at the Eastern Agricultural Research Station (The Ohio State University) fed a grain-based diet (calculated ME = 2.85 Mcal/kg DM). In Trial 2, RFI was measured in 119 Santa Gertrudis steers (initial BW = 308.4 ± 28.1 kg) fed a roughage-based diet (calculated ME = 2.21 Mcal/kg DM). At the end of the RFI measurement period, cattle in Trial 1 (n = 7 low RFI and n = 7 high RFI) and in Trial 2 (n = 6 low RFI and n = 8 high RFI) with measures of RFI exceeding 0.5 (Trial 1) or 1.0 (Trial 2) SD from the mean RFI were selected to measure mitochondrial function. Overall ADG, DMI, and RFI were 1.19 ± 0.15, 9.31 ± 1.12, and 0.00 ± 0.63 kg/d and 0.83 ± 0.16, 9.48 ± 1.00, and 0.00 ± 0.86 kg/d in Trial 1 and 2, respectively. Cattle with low RFI consumed 13 and 24% less (P < 0.05) DM and had 14 and 56% greater (P < 0.05) G:F than cattle with high RFI in Trial 1 and 2, respectively, even though ADG and BW were similar (P > 0.10). In Trial 1, cattle with low RFI tended (P = 0.06) to have greater state 3 respiration rates than cattle with high RFI, but state 3 respiration rates were similar (P > 0.10) between cattle with low and high RFI in Trial 2. In both trials, cattle with low RFI had greater (P < 0.05) acceptor control ratios than their high RFI counterparts. The respiratory control ratio tended (P = 0.09) to be greater for cattle with low RFI compared with high RFI cattle in Trial 1, but no difference (P > 0.10) was observed in Trial 2. Proton-leak kinetics were similar (P > 0.05) between cattle with low and high RFI in both trials. These data suggest that ADP has greater control of oxidative phosphorylation in liver mitochondrial of cattle with low RFI compared to their high RFI counterparts.

Body weight loss in beef cows: II. Increased antioxidant messenger ribonucleic acid levels in skeletal muscle but not erythrocyte antioxidant activity.

Twenty-six Angus-cross cows were used to examine the effect of BW loss (WL) on skeletal muscle and erythrocyte markers of oxidative stress. Serum NEFA concentrations, erythrocyte superoxide dismutase, and glutathione peroxidase activities were measured during WL and BW maintenance. Real-time reverse-transcription-PCR was used to determine mRNA levels of antioxidant genes during both periods to assess skeletal muscle response to WL. Body weight loss resulted in elevated serum NEFA concentrations but no change in erythrocyte superoxide dismutase and glutathione peroxidase activities. During WL, mRNA levels of the antioxidant genes glutathione peroxidase 4, mitochondrial superoxide dismutase, thioredoxin reductase 1, and selenoprotein W increased. Abundance of mRNA of genes involved in antioxidant signaling, specifically, PPARgamma coactivator-1 alpha, nuclear respiratory factor 1, estrogen-related receptor alpha, and tumor protein 53, was also increased. In summary, during WL cows had no change in peripheral antioxidant enzyme activity, but mRNA abundance of proteins involved in protecting the body from oxidative stress increased in skeletal muscle. During times when NEFA are used as a fuel source, signals such as mild reactive oxygen species production or increased concentration of lipid by-products activate the transcription of nuclear signaling molecules such as PPARgamma gamma coactivator-1 alpha, nuclear respiratory factor 1, estrogen-related receptor alpha, and tumor protein 53. These genes work to activate antioxidant genes such as mitochondrial superoxide dismutase, glutathione peroxidase 4, and thioredoxin reductase 1 to aid in the detoxification of reactive oxygen species. These data suggest an important role for antioxidant genes to protect cattle that are mobilizing body fat.

Body weight loss in beef cows: I. The effect of increased beta-oxidation on messenger ribonucleic acid levels of uncoupling proteins two and three and peroxisome proliferator-activated receptor in skeletal muscle.

Twenty-six Angus-cross cows were studied during BW loss (WL) and BW maintenance (WM) to examine the effects of elevated beta-oxidation on mRNA levels of NEFA-responsive signaling molecules in skeletal muscle. At the end of the WL and WM sampling periods, muscle biopsies were removed from the biceps femoris and mRNA levels were measured using real-time PCR. In comparison with WM, cows undergoing WL had elevated mRNA levels of carnitine palmitoyltransferase 1 (4.6-fold), fatty acid binding protein 3 (2.0-fold), and acyl-coenzyme A oxidase 1 (2.8-fold), all of which are indicators of beta-oxidation. Levels of mRNA of the NEFA-responsive signaling molecules PPAR alpha, delta, and gamma increased 2.0-fold, 2.2-fold, and 1.84-fold, respectively, during WL. Uncoupling proteins 2 and 3 also had increased mRNA (3.0-fold and 6.0-fold, respectively) during WL, but Western blot analysis found no changes in protein abundance of uncoupling protein 3. Uncoupling protein expression can be directly stimulated by elevated NEFA, potentially to protect cells from damage by lipid oxidation by-products. Thus, an increase in mRNA levels of genes involved in beta-oxidation of fatty acids and fatty acid by-products occurs during BW loss in beef cattle. These data support previous findings in nonruminants and suggest that these genes play a role in the same physiological processes in ruminants.

The bovine fatty acid binding protein 4 gene is significantly associated with marbling and subcutaneous fat depth in Wagyu x Limousin F2 crosses.

Fatty acid binding protein 4 (FABP4), which is expressed in adipose tissue, interacts with peroxisome proliferator-activated receptors and binds to hormone-sensitive lipase and therefore, plays an important role in lipid metabolism and homeostasis in adipocytes. The objective of this study was to investigate associations of the bovine FABP4 gene with fat deposition. Both cDNA and genomic DNA sequences of the bovine gene were retrieved from the public databases and aligned to determine its genomic organization. Primers targeting two regions of the FABP4 gene were designed: from nucleotides 5433-6106 and from nucleotides 7417-7868 (AAFC01136716). Direct sequencing of polymerase chain reaction (PCR) products on two DNA pools from high- and low-marbling animals revealed two single nucleotide polymorphisms (SNPs): AAFC01136716.1:g.7516G>C and g.7713G>C. The former SNP, detected by PCR-restriction fragment length polymorphism using restriction enzyme MspA1I, was genotyped on 246 F2 animals in a Waygu x Limousin F2 reference population. Statistical analysis showed that the FABP4 genotype significantly affected marbling score (P = 0.0398) and subcutaneous fat depth (P = 0.0246). The FABP4 gene falls into a suggestive/significant quantitative trait loci interval for beef marbling that was previously reported on bovine chromosome 14 in three other populations.

Frequency distribution of a Cys430Ser polymorphism in peroxisome proliferator-activated receptor-gamma coactivator-1 (PPARGC1) gene sequence in Chinese and Western pig breeds.

Identification of major genes, that genetically impact fat tissue formation is important for successful selection of lean animals with good meat quality. Because of its central role in fat cell differentiation and muscle fibre type determination, PPARGC1 is a potential candidate gene affecting fattening traits and pig meat quality. In this study, a T/A substitution at position 1378 (GenBank accession no. AY346131) in the porcine PPARGC1 gene causing a Cys430Ser amino acid substitution at position 430 was genotyped on a total of 239 animals, including 101 from seven Chinese and 138 from six Western pig breeds. Bayesian analysis revealed that the mean frequency of allele T (Cys) was 92.64 +/- 4.82% in Chinese pigs, and 45.99 +/- 4.13% in Western pigs. The 95% interval of the posterior mean frequency of allele T was 0.82-1.00 in Chinese pigs and 0.38-0.54 in Western pigs, indicating these two groups of pigs diverged at this locus during genetic evolution of the breed. Because marked differences in fat and lean tissue deposition exist between Western and Chinese pig breeds, this Cys430Ser exchange in the PPARGC1 gene deserves further evaluation to determine its phenotypic effect on fattening and carcass traits in commercial pig populations.

An independent confirmation of a quantitative trait locus for milk yield and composition traits on bovine chromosome 26.

Several reports have demonstrated that bovine chromosome 26 (BTA26) harbours significant or suggestive quantitative trait loci (QTL) for milk production and composition traits in dairy cattle. Our previous study showed that a C/T substitution in the bovine TCF7L2 gene on BTA26 was significantly linked to QTL for protein yield (PY) in a Canadian dairy cattle population. Actually, this polymorphism was one of the markers derived from a genome-wide screening of QTL for milk PY using an amplified fragment length polymorphism technique combined with a DNA pooling strategy. In the present study, 990 Holstein bulls with complete genotype and phenotype data from 14 sire families were analysed to confirm, if the QTL effects exist in other populations. Statistical analysis revealed that this marker was significantly associated with PY, protein percentage, milk yield and fat yield (FY) (p < 0.001) in the US Holstein population. These results indicate that this QTL region has a pleiotrophic effecton different milk traits and is portable in different populations.

Modulatory effects of dietary beta-carotene on blood and mammary leukocyte function in periparturient dairy cows.

Beginning 4 wk prior to predicted calving, 14 Holstein cows per treatment were fed diets 1) unsupplemented (control) or supplemented daily with 2) 300 mg of beta-carotene, 3) 600 mg of beta-carotene, or 4) 120,000 IU of vitamin A. Blood was collected around calving on wk -4, -2, -1, 0 (within 24 h postcalving), 1, 2, and 4 for isolation of lymphocytes and neutrophils and for the analysis of plasma vitamins. Lacteal secretions were collected on wk 0, 1, 2, and 4 for the isolation of phagocytes. Cows supplemented with 600 mg of beta-carotene had higher concentrations of plasma beta-carotene and retinol than did unsupplemented cows. Supplemental vitamin A increased plasma retinol on wk 4 and decreased plasma beta-carotene on wk -1 and 0. Treatment did not affect concentrations of plasma alpha-tocopherol. Blood lymphocyte proliferation in response to concanavalin A, phytohemagglutinin, and pokeweed mitogen during the peripartum period was higher in cows supplemented with beta-carotene than in unsupplemented controls. Phagocytic activity of blood neutrophils was enhanced on wk 1 in cows fed 300 mg of beta-carotene. Intracellular killing by blood neutrophils was enhanced in cows supplemented with beta-carotene (wk 0) and vitamin A (wk 0 and 1). Iodine uptake and nitroblue tetrazolium reduction by blood neutrophils was stimulated in cows supplemented with beta-carotene. Phagocytic activity, iodine uptake, and nitroblue tetrazolium reduction by mammary phagocytes from all cows generally were lower postpartum than on the day of calving. The incidence of retained placenta and metritis was higher for unsupplemented cows than for cows supplemented with beta-carotene. Therefore, dietary beta-carotene can elevate peripartum concentrations of blood beta-carotene, enhance host defense mechanisms by potentiating lymphocyte and phagocyte function, and decrease the incidence of certain reproductive disorders.

Uptake of orally administered beta-carotene by blood plasma, leukocytes, and lipoproteins in calves.

The uptake of beta-carotene by blood cells, plasma, and lipoproteins was studied in bull calves that were orally administered a single (Exp. 1; n = 18 Angus calves) or multiple (Exp. 2; n = 16 Holstein calves) doses of beta-carotene. Administration of beta-carotene increased plasma beta-carotene and the amount of beta-carotene associated with each lipoprotein fraction. Before beta-carotene treatment, the total amount of beta-carotene associated with the high-density lipoprotein (HDL) was three- to fourfold higher than the amount associated with low-density lipoprotein (LDL) and fivefold higher than the amount associated with very-low-density lipoprotein (VLDL). The relative increase in total beta-carotene associated with the lipoproteins was greater for LDL than for HDL or VLDL. Orally administered beta-carotene increased the uptake of beta-carotene by lymphocytes. Subcellular fractions of blood lymphocytes isolated from animals fed beta-carotene revealed that beta-carotene was taken up in significant amounts by the mitochondrial, nuclear, and microsomal fractions. The profile of beta-carotene uptake by these subcellular fractions did not mirror that observed in plasma. In contrast, beta-carotene was not detectable in blood neutrophils and erythrocytes in either beta-carotene-supplemented or unsupplemented calves. Treatment did not influence the concentrations of retinol or alpha-tocopherol in plasma, lipoproteins, lymphocytes, neutrophils, or erythrocytes. These data revealed the presence of beta-carotene in bovine lymphocyte subcellular fractions and suggest a possible physiological role of beta-carotene in these cells.

Kinetic characteristics of beta-carotene uptake after an injection of beta-carotene in pigs.

Two experiments were conducted to study the uptake of beta-carotene in plasma, lipoproteins, and blood cells in pigs (50 to 55 kg; n = 40) after an i.m. injection of 0, 10, 20, or 40 mg of beta-carotene. Blood was sampled at 0, 3, 6, 12, 24, and 48 h postinjection. beta-Carotene was not detectable in plasma, lipoproteins, or blood cells of control pigs. However, concentrations of beta-carotene in plasma and lipoproteins increased in a dose-related manner in injected animals. Distribution of beta-carotene in the lipoproteins changed with time postinjection. The beta-carotene associated with very low density lipoproteins increased and that in low density lipoproteins decreased with time in treated pigs. Concentrations of beta-carotene in lymphocytes of treated pigs also increased within 3 h postinjection. The profile of beta-carotene in lymphocytes was different from that observed in plasma and lipoproteins. Carotene was not detectable in neutrophils and erythrocytes. Treatment did not alter concentrations of retinol or alpha-tocopherol in plasma, lipoproteins, or blood cells. Therefore, lymphocytes specifically take up beta-carotene, thereby suggesting a possible role of beta-carotene in this immune cell.

Subcellular distribution of beta-carotene, retinol, and alpha-tocopherol in porcine lymphocytes after a single injection of beta-carotene.

The subcellular distribution of beta-carotene, retinol, and alpha-tocopherol in lymphocytes was studied in pigs (50 to 55 kg) injected once with 0, 20, or 40 mg of beta-carotene. Blood was sampled at 0, 24, 48, and 72 h postinjection. Plasma beta-carotene in treated pigs peaked at 24 h and decreased rapidly thereafter. Beta-carotene was found in all subcellular fractions of lymphocytes. Concentrations in nuclei mirrored changes in plasma. However, beta-carotene in mitochondria and cytosol peaked at 24 h, whereas that in microsomes peaked at 48 h. Concentrations in the latter three subcellular fractions remained high at 48 and 72 h even though plasma beta-carotene had decreased to very low concentrations. Peak concentrations of beta-carotene were highest in the nuclei, intermediate in the mitochondria and microsomes, and lowest in the cytosol. Treatment did not influence concentrations of retinol or alpha-tocopherol in the various subcellular fractions. These data provide more compelling evidence for the possible role of beta-carotene in lymphocytes.

Porcine lymphocytes secrete a bioactive and immunoreactive LH-like factor in response to LHRH and concanavalin A.

Lymphocyte conditioned medium (CM) was prepared by incubating 0 (cell-free control) or 4 x 10(6) lymphocytes/ml in serum-supplemented RPMI containing 0, 10(-9), 10(-7), and 10(-5) M luteinizing hormone releasing hormone (LHRH), 10(-5) M LHRH antagonist (LHRHA), or 10(-7) M LHRH + 10(-5) M LHRHA. Treatments were applied with and without 10 micrograms/ml concanavalin A (con A), and media were analyzed for LH. Aliquots of the CM from cultures incubated for 48 h were later applied to porcine granulosa cell cultures (suspended to 1.25 x 10(5) cells in 450 mul). Thereafter, 50 mul of CM were added to granulosa cell cultures. Media were collected after 12, 24, and 48 h and progesterone determined. Immunoreactive LH increased with time of incubation in lymphocyte CM but not cell-free CM. LH content of lymphocyte CM increased as LHRH concentration increased. LHRHA significantly reduced the amount of LH measured. The presence of con A in the medium resulted in maximal concentrations of LH, irrespective of dose of LHRH or LHRHA. Cell-free CM containing LHRH, LHRHA, and/or con A did not affect progesterone production by granulosa cells at any of the time periods. Lymphocyte CM containing LHRH caused a dose-dependent increase in progesterone production at 48 h. This stimulation was blocked by lymphocyte CM containing LHRHA. Lymphocyte CM containing con A also stimulated progesterone production at all of the LHRH concentrations studied. This response was not inhibited by lymphocyte CM containing the LHRHA.(ABSTRACT TRUNCATED AT 250 WORDS)