• Food Science of Animal Resources
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• v.38 no.6
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• pp.1305-1314
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• 2018

To investigate relationships of electronic taste-traits with muscle fiber type composition (FTC) and contents of nucleotides, porcine longissimus lumborum (LL), psoas major (PM), and infra spinam (IS) muscles were obtained from eight castrated LYD pigs. FTC and taste-traits in these three porcine muscles were measured by histochemical analysis and electronic tongue system, respectively. IS had significantly higher proportion of type I fibers while LL had significantly higher proportion of type IIB than other muscles (p<0.05). IS had the highest inosine monophosphate (IMP) content while LL had the lowest IMP content (p<0.05). In contrast, LL had significantly higher hypoxanthine content compared to PM and IS (both p<0.05). For taste-traits, IS had significantly higher umami and richness values but lower sourness value than LL and PM (p<0.05). Sourness and astringency values of LL were significantly higher than those of IS (p<0.05). The proportion of type IIB fiber was positively correlated with sourness and astringency but negatively correlated with saltiness. These results suggest that sourness and astringency tastes are increased with increasing proportions of type IIB fibers in porcine muscles due to increase of hypoxanthine content. These results also imply that umami and richness tastes are increased with increasing contents of type I and IIA fibers because of increased IMP content in porcine muscles.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.4
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• pp.457-463
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• 2016

The goal of this work was to investigate the correlations between MyHC mRNA transcription and their corresponding protein expressions in porcine longissimus muscle (LM) during postnatal growth of pigs. Five DLY ($Duroc{\times}Landrace{\times}Yorkshire$) crossbred pigs were selected, slaughtered and sampled at postnatal 7, 30, 60, 120, and 180 days, respectively. Each muscle was subjected to quantity MyHCs protein contents through an indirect enzyme-linked immunosorbent assay (ELISA), to quantity myosin heavy-chains (MyHCs) mRNA abundances using real-time polymerase chain reaction. We calculated the proportion (%) of each MyHC to total of four MyHC for two levels, respectively. Moreover, the activities of several key energy metabolism enzymes were determined in LM. The result showed that mRNA transcription and protein expression of MyHC I, IIa, IIx and IIb in LM all presented some obvious changes with postnatal aging of pigs, especially at the early stage after birth, and their mRNA transcriptions were easy to be influenced than their protein expressions. The relative proportion of each MyHC mRNA was significantly positively related to that of its corresponding protein (p<0.01), and MyHC I mRNA proportion was positively correlated with creatine kinase (CK), succinate dehydrogenase (SDH), malate dehydrogenase (MDH) activities (p<0.05). These data suggested that MyHC mRNA transcription can be used to reflect MyHC expression, metabolism property and adaptive plasticity of porcine skeletal muscles, and MyHC mRNA composition could be a molecular index reflecting muscle fiber type characteristics.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.2
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• pp.170-175
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• 2019

Objective: Uncoupling protein 3 gene (UCP3) is a candidate gene associated with the meat quality of pigs. The aim of this study was to explore the regulation mechanism of UCP3 expression and provide a theoretical basis for the research of the function of porcine UCP3 gene in meat quality. Methods: Bisulfite sequencing polymerase chain reaction (PCR) and quantitative real-time PCR (Q-PCR) were used to analyze the methylation of UCP3 5′-flanking region and UCP3 mRNA expression in the adipose tissue or skeletal muscle of three pig breeds at different ages (1, 90, 210-day-old Putian Black pig; 90-day-old Duroc; and 90-day-old Dupu). Results: Results showed that two cytosine-guanine dinucleotide (CpG) islands are present in the promoter region of porcine UCP3 gene. The second CpG island located in the core promoter region contained 9 CpG sites. The methylation level of CpG island 2 was lower in the adipose tissue and skeletal muscle of 90-day-old Putian Black pigs compared with 1-day-old and 210-day-old Putian Black pigs, and the difference also existed in the skeletal muscle among the three 90-day-old pig breeds. Furthermore, the obvious changing difference of UCP3 mRNA expression was observed in the skeletal muscle of different groups. However, the difference of methylation status and expression level of UCP3 gene was not significant in the adipose tissue. Conclusion: Our data indicate that UCP3 mRNA expression level was associated with the methylation status of UCP3 promoter in the skeletal muscle of pigs.

• Food Science and Biotechnology
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• v.17 no.5
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• pp.965-970
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• 2008

The objective of this study was to examine the relationship between instrumental tenderness parameters and histochemical characteristics in the porcine longissimus dorsi muscle, and to investigate a comparison between tenderness parameters such as the Warner-Bratzler shear-force (WBS) and texture profile analysis (TPA). A negative relationship between WBS and fiber area was observed. However, there was no significant relationship between hardness and muscle fiber area. The percentage of fiber type IIb exhibited a positive correlation with hardness. There was a negative relationship between the type IIa composition percentage and hardness. This study showed that some muscle fiber characteristics were related to WBS and TPA parameters, especially hardness.

• Food Science and Biotechnology
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• v.14 no.5
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• pp.639-644
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• 2005

The aim of this study was to investigate the effect of the myosin light chain (MLC) isoforms on the muscle fiber characteristics and meat quality traits in porcine longissimus muscle. Pale, soft, exudative (PSE) samples had a lower content of essential light chain (ELC) 1S isoforms and a higher proportion of the fiber type IIB than the reddish-pink, firm, non-exudative (RFN) samples. These compositions suggest that the PSE pork has a higher glycolytic and a lower oxidative capacity than the RFN pork. Therefore, these characteristics of PSE pork might affect the metabolic rate and meat quality traits, including protein solubility. In addition, the indicator traits of the postmortem metabolic rate were related to the ELC 1F/3F ratio ($pH_{45\;min}$: r = -0.43, P < 0.001; R-value: r = 0.53, P < 0.001). These results suggest that the MLC isoform composition can affect the postmortem metabolic rate and meat quality traits.

• Korean Journal of Veterinary Service
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• v.19 no.2
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• pp.154-162
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• 1996

The effcets of adenosine 5'-triphosphate(ATP) were investigated on the uterine smooth muscle motility in the pig. The results were summarized as follows: 1. The effects of the porcine uterine smooth muscle and the contractile responses increased between the concentration of ATP $10^{-5}$ and $10^{-3}$ M with a dose-dependent manner. 2. The contractile response induced by ATP($10^{-4}$ M) was not blocked by pretreatment with cholinergic receptor blocker, atropine ($10^{-6}$ M) 3. The contractile response induced by ATP ($10^{-4}$ M) was not blocked by pretreatment with $\alpha$ -adrenergic receptor blocker, phentolamine(10$^{-6}$ M) and ${\beta}$-adrenergic blocker, propranolol ($10^{-6}$ M). 4. The contractile response induced by ATP($10^{-4}$ M) was not appeared in 4Ca^{++}$ -free medium. As the concentration of $Ca^{++}$ in $Ca^{++}$ -free medium was increased, the contractile response induced by ATP ($10^{-4}$ M) was enhenced but was completely inhibited by pretreatment with $Ca^{++}$ -channel blocker, papaverine($10^{-6}$ M) or verapamil($10^{-6}$ M). From these results, it was conclued that the effects of ATP were the contraction mediated by purinergic receptor in uterine smooth muscle of pig.

• Food Science of Animal Resources
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• v.36 no.5
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• pp.583-593
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• 2016

The aim of this study was to investigate the effects of morphological characteristics of porcine muscle fibers on growth performance, muscle fiber characteristics, and pork quality taken from the longissimus dorsi muscle. A total of 239 crossbred pigs (164 castrated males and 75 females) were used in this study. Experimental pigs were categorized by the total number of muscle fiber (TNF: High and Low) and cross sectional area of muscle fiber (CSAF: Large, Middle, and Small). Their combinations were classified into six groups (High-Large, HL; High-Middle, HM; High-Small, HS; Low-Large, LL; Low-Middle, LM; Low-Small, LS). The TNF and CSAF were significantly (p<0.05) correlated with growth rate and carcass productivity, while the only of the type I number had no meaningful relationships excluding the correlation with loin area (p<0.001). The proportion of type I area was positively correlated with pH_{45 min} while the proportion of type IIB area was negatively correlated with pH_{45 min} and pH_{24 h} (p<0.05). Drip loss and protein denaturation had strong relationships with the proportion of type IIB number or area. The HL group exhibited the greatest growth performance. In addition, the HL group had significantly greater values in protein solubility than the other groups. In conclusion, this study suggest that high TNF combined to large CSAF improve the ultimate lean meat productivity and assure normal meat quality simultaneously with increased both proportion of number and area of type I, type IIA muscle fibers and lowered proportion of number and area of type IIB.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.10
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• pp.1529-1534
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• 2008

The aim of this study was directed at exploring the possible use of muscle fiber characteristics as new selection traits for improving both porcine lean meat production and quality. A total of 174 (114 Yorkshire, 30 Landrace, and 30 Meishan) pigs were used for this study, and lean meat production ability was estimated by backfat thickness and loin eye area. The Longissimus dorsi muscle was taken in order to measure meat quality and muscle fiber characteristics. Due to the high correlations between total muscle fiber number and most of the performance traits, all pigs were classified into three groups (low, intermediate, or high) by total muscle fiber number using cluster analysis. The high group had the highest loin eye area (p<0.001). The meat quality traits were within normal ranges as reddish pink, firm, and nonexudative (RFN) pork, but the groups classified as intermediate and high had relatively large drip loss percentages (p<0.05), produced more than twice the amount of pale, soft, and exudative (PSE) pork as compared to the low group. The group with a high total muscle fiber number was further classified, based on type 2b fiber percentage, into low or high groups by cluster analysis. The results showed that the low type 2b fiber group had good loin eye area (p<0.05), small drip loss (p<0.05), and did not produce PSE pork. For these reasons, a high total muscle fiber number, with a low percentage of type 2b fibers, may be suitable in selecting for improvements in both lean meat production and meat quality.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.7
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• pp.954-960
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• 2008

MiRNAs (microRNAs) are a class of small non-coding RNA molecules of ~21 nucleotides that down- regulate the expression of target genes at post-transcriptional level. In this study, we first accomplished a preliminary scan of miRNA expression using 65 and 90 day fetal pig skeletal muscle samples by microarray hybridization, and 34 miRNAs showed strong positive signals. Five of these miRNAs were selected for further investigation by real-time RT-PCR. The statistical analyses indicated that three miRNAs exhibited significant differential expression (p<0.05) during porcine muscle development from 65 to 90 days of gestation, e.g., miR-24 and miR-424 were down-regulated while miR-133a was up-regulated. Multi-tissue RT-PCR was performed to detect the expression patterns of the five miRNA precursors. The results showed that most of these precursor miRNAs were ubiquitously expressed in different porcine tissues.

• BMB Reports
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• v.43 no.2
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• pp.140-145
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• 2010

The present study investigated whether the mammalian target of rapamycin (mTOR) signal pathway is involved in the regulation of high glucose-induced intramuscular adipogenesis in porcine muscle satellite cells. High glucose (25 mM) dramatically increased intracellular lipid accumulation in cells during the 10-day adipogenic differentiation period. The expressions of CCAAT/enhancer binding protein-$\alpha$ (C/EBP-$\alpha$) and fatty acid synthase (FAS) protein were gradually enhanced during the 10-day duration while mTOR phosphorylation and sterol-regulatory- element-binding protein (SREBP)-1c protein were induced on day 4. Moreover, inhibition of mTOR activity by rapamycin resulted in a reduction of SREBP-1c protein expression and adipogenesis in cells. Collectively, our findings suggest that the adipogenic differentiation of porcine muscle satellite cells and a succeeding extensive adipogenesis, which is triggered by high glucose, is initiated by the mTOR signal pathway through the activation of SREBP-1c protein. This process is previously uncharacterized and suggests a cellular mechanism may be involved in ectopic lipid deposition in skeletal muscle during type 2 diabetes.