S.H. Lee

Skeletal muscle fiber type and myofibrillar proteins in relation to meat quality

Although numerous studies have reported the relationships among muscle fiber characteristics, lean meat content and meat quality, controversial perspectives still remain. Conventional histochemical classifications may be involved in a high level of error, subjectivity and it could not clearly explain variety of myofibrillar protein isoforms. Therefore, more information is needed on how different factors, such as species, breeds, gender, nutrient conditions, physiological state of animals, and environment factors, affect ultimate meat quality in order to evaluate these uncertainness. Unfortunately, there is little information that completely covers with relationship among the muscle fiber types, myofibrillar proteins and enzymatic proteolysis. In addition to the perspective of postmortem metabolism, protein quality control in skeletal muscle and proteolytic degradation of muscle proteins during postmortem period could help to clarify this relationship. Therefore, the present review will focus on muscle fiber types, typing methods, muscle proteins and meat quality, and will summarize aspects of enzymatic view of proteasome.

The influence of pork quality traits and muscle fiber characteristics on the eating quality of pork from various breeds

The purpose of this study was to compare parameters associated with pork quality, muscle fiber, and eating quality among various breeds, and to examine if differences in eating quality were associated to pork quality and muscle fiber characteristics. For carcass and pork quality, although there were significant differences among breeds, the values of parameters in all pigs were assigned a normal quality class, a likely outcome of the similarity in the area percentage of type I and IIB fibers. For eating quality, pork loins from Berkshire pigs were more tender and full of pork flavor than Landrace and Yorkshire pigs. Except juiciness and mouth coating, over 20% of the variability in the eating quality parameters can be explained by pork quality traits and muscle fiber characteristics using multiple regression analysis. Furthermore, differences in muscle pH(24h), cooking loss, shear force, and NPPC marbling score could explain a large proportion of variation in eating quality parameters associated with the texture of pork.

Serum 25-hydroxyvitamin D levels, obesity and the metabolic syndrome among Korean children

BACKGROUND AND AIMnEvidence of the relationship between serum vitamin D levels and cardiovascular risk factors in children is limited. We investigated the associations between serum vitamin D levels (25-hydroxyvitamin D [25(OH)D]) and obesity and metabolic syndrome and its components in Korean children.nnnMETHODS AND RESULTSnWe recruited 1660, nine-year-old, Korean children (904 boys and 756 girls) who voluntarily participated in this study while being examined during school-based health examinations. We measured anthropometric variables (height and weight), metabolic parameters (blood pressure, fasting plasma glucose, triglyceride, and HDL cholesterol levels) and serum vitamin D levels. We analyzed the data using multivariate logistic regression models. Mean 25(OH)D levels were lower in children defined as obese or abdominally obese (P <0.001). When serum levels of 25(OH)D were divided into quartiles, BMI, waist circumference, and triglyceride levels were lower, and HDL cholesterol levels were higher, as vitamin D levels increased. Using children from the highest quartile of 25(OH)D levels as a referent, the adjusted ORs (95% CI) for obesity in those in the third, second, and lowest quartiles of 25(OH)D levels were 1.55 (1.01-2.40), 1.87 (1.22-2.85), and 2.59 (1.71-3.90), respectively (P for trend <0.001). For abdominal obesity the ORs (CI) were 2.08 (1.20-3.60), 2.32 (1.36-3.95), and 2.96 (1.75-5.00) (P for trend<0.001), and for metabolic syndrome they were 2.60 (1.08-6.30), 4.00 (1.73-9.26), and 4.25 (1.84-9.85), respectively (P for trend <0.05).nnnCONCLUSIONSnWe found low vitamin D levels in Korean children to be associated with obesity and metabolic syndrome. Insufficient serum vitamin D levels in children may be a risk factor of obesity and metabolic syndrome.

Association between polymorphisms of the heart fatty acid binding protein gene and intramuscular fat content, fatty acid composition, and meat quality in Berkshire breed

The objective of this study was to examine the relationship between polymorphisms of the heart fatty acid binding protein (H-FABP) gene and variation in intramuscular fat (IMF) content, fatty acid composition, and meat quality in Berkshire breed. We detected an association between IMF content and H-FABP HinfI restriction fragment length polymorphism (RFLP) genotype. The HH genotype showed the greatest IMF content among the genotype classes (P<0.05). Regarding meat quality traits, only drip loss was significantly different among the H-FABP HinfI RFLP genotype classes (P<0.01). In the case of fatty acid composition, the degree of saturation of fatty acids was greater in hh-genotype pigs than in HH and Hh genotypes. The H-FABP MspI RFLP genotype affected unsaturated fatty acid content, and the ratio of polyunsaturated fatty acid to saturated fatty acid (P<0.05), whereas the H-FABP HaeIII RFLP genotype had no effect on fatty acid characteristics.

Effects of myosin heavy chain isoforms on meat quality, fatty acid composition, and sensory evaluation in Berkshire pigs.

The main objective of this study was to investigate the effects of myosin heavy chain (MHC) isoforms on meat and sensory quality in Berkshire pigs. A total of 85 pigs were evaluated, and muscle samples were taken for the analyses of MHC isoform, meat quality, fatty acid composition, and sensory evaluation. Content of the MHC slow isoform was significantly correlated with pH(24h) (r=0.26, P<0.05) and drip loss (r=-0.32, P<0.01), although the content of MHC isoforms showed limited relationships with individual fatty acids. In the case of sensory evaluation of meat by a trained panel test, the MHC fast/slow ratio was correlated with the juiciness (r=-0.33, P<0.01), off-flavor (r=0.34, P<0.01), tenderness attributes (r=-0.43 to -0.47). These results imply that the content of MHC isoforms can influence various aspects of quality including pork and sensory quality in Berkshire pigs.

Assessment of Genetic Diversity and Relationships Between Korean Cattle and Other Cattle Breeds by Microsatellite loci

For the genetic assessment of the cattle breeds including Hanwoo, eleven microsatellite markers on ten bovine autosomes were genetically characterized for 618 individuals of nineteen cattle breeds; North Eastern Asian breeds (Korean cattle, Korean Black cattle, Japanese Black cattle, Japanese Brown cattle, Yanbian cattle), Chinese yellow cattle (Luxi cattle, Nanyang cattle), European Bas taurus (Angus, Hereford, Charolais, Holstein, Limousin), African Bas taurus (NDama, Baoule), African Bas indicus (Kavirondo Zebu, White Fulani), Asian Bas indicus (Sahiwal, Nelore) and one Bali cattle, Bas banteng as an outbreed-reference population. Allele frequencies derived from the genotyping data were used in estimating heterozygosities, gene diversities and genetic distances. The microsatellite loci were highly polymorphic, with a total of 162 different alleles observed across all loci. Variability in allele numbers and frequencies was observed among the breeds. The average expected heterozygosity of North Eastern Asian breeds was higher than those of European and African taurines, but lower than those of Asian and African indicines. Genetic distances were estimated using Neis DA genetic distance and the resultant DA matrix was used in the construction of the phylogenetic trees. The genetic distances between North Eastern Asian cattle breeds and Bas indicus were similar with those between European Bas taurus and Bas indicus, and African Bas taurus and Bas indicus, respectively. The clusters were clearly classified into North Eastern Asian, European and African taurines groups as well as different cluster with Chinese mainland breeds, firstly out-grouping with Bas indicus. These results suggest that Korean cattle, Hanwoo, had not been originated from a crossbred between Bas primigenius in Europe and Bas indicus in India and North Eastern Asian Bas taurus may be have separate domestication from European and African Bas taurus.

Single nucleotide polymorphism association study for backfat and intramuscular fat content in the region between SW2098 and SW1881 on pig chromosome 6

This study was carried out to identify SNP associated with fatness traits on pig chromosome 6. In total, 11,067 putative genomic variations were detected in 125 complete bacterial artificial chromosome sequences corresponding to the region between SW2098 and SW1881, which harbors multiple QTL affecting intramuscular fat content (IMF) and backfat thickness (BFT). Among 173 putative SNP validated by MassArray, 120 SNP were used in an association study on 541 offspring produced by a cross of Korean native pig and Landrace breeds. The significance level of each SNP was determined using single marker regression analysis. Further, significant threshold values were determined using a false discovery rate. Nine out of 120 SNP showed significant effects on BFT or IMF or both. Of the 9 significant SNP, 4 were significantly associated with IMF, 7 were significantly related to BFT, and 2 SNP (Kps8172 and Kps6413) showed significant effects on both traits. Moreover, multiple regression analysis considering all significant SNP was used to correct spurious false positives due to linkage disequilibrium. Consequently, only 1 SNP (Kps6413) was significant for IMF, whereas 4 SNP including Kps6413 showed significant effects on BFT. The significant SNP had generally additive effects and on average explained 1.72% of the genetic variation for IMF and 3.92% for BFT, respectively. These markers can potentially be applied in pig breeding programs for improving IMF and BFT traits after validation in other populations.

Complete genome sequence of Bacillus sp. 275, producing extracellular cellulolytic, xylanolytic and ligninolytic enzymes

Technologies for degradation of three major components of lignocellulose (e.g. cellulose, hemicellulose and lignin) are needed to efficiently utilize lignocellulose. Here, we report Bacillus sp. 275 isolated from a mudflat exhibiting various lignocellulolytic activities including cellulase, xylanase, laccase and peroxidase in the cell culture supernatant. The complete genome of Bacillus sp. 275 strain contains 3832 protein cording sequences and an average G+C content of 46.32% on one chromosome (4045,581bp) and one plasmid (6389bp). The genes encoding enzymes related to the degradation of cellulose, xylan and lignin were detected in the Bacillus sp. 275 genome. In addition, the genes encoding glucosidases that hydrolyze starch, mannan, galactoside and arabinan were also found in the genome, implying that Bacillus sp. 275 has potentially a wide range of uses in the degradation of polysaccharide in lignocellulosic biomasses.

Influences of Media Compositions on Characteristics of Isolated Bacteria Exhibiting Lignocellulolytic Activities from Various Environmental Sites

Efficient isolation of lignocellulolytic bacteria is essential for the utilization of lignocellulosic biomass. In this study, bacteria with cellulolytic, xylanolytic, and lignolytic activities were isolated from environmental sites such as mountain, wetland, and mudflat using isolation media containing the combination of lignocellulose components (cellulose, xylan, and lignin). Eighty-nine isolates from the isolation media were characterized by analyzing taxonomic ranks and cellulolytic, xylanolytic, and lignolytic activities. Most of the cellulolytic bacteria showed multienzymatic activities including xylanolytic activity. The isolation media without lignin were efficient in isolating bacteria exhibiting multienzymatic activities even including lignolytic activity, whereas a lignin-containing medium was effective to isolate bacteria exhibiting lignolytic activity only. Multienzymatic activities were mainly observed in Bacillus and Streptomyces, while Burkholderia was the most abundant genus with lignolytic activity only. This study provides insight into isolation medium for efficient isolation of lignocellulose-degrading microorganisms.

Differentiation of human neural progenitor cells on PLGA microfibers

In this study, we investigated the application of human embryonic stem cells (hESCs) to neural tissue engineering. hESCs were differentiated to neural progenitor cells and cultured on poly(lactic-co-glycolic acid) (PLGA) microfibers. PLGA microfibers were prepared by using a microfluidic spinning system and aligned in parallel manner by winding the nascent fibers around a rotating frame. Neural progenitor cells were prepared by differentiating embryoid bodies (EBs). Neural progenitors cultured on the PLGA fibers were assessed for further proliferation and differentiation. To verify the expression of neural progenitor markers, cells were immunostained with neuronal specific antibodies. After six-days in culture, neuronal protein expression was confirmed with neuron specific beta III tubulin antibody (Tuj1) and glial fibrillary acidic protein (GFAP). After 20-days, cells were immunostained with microfilament associated protein (MAP) and neurofilament. The neurites of differentiated cells cultured for 20 days elongated along the direction of the PLGA microfibers. This result shows the possibility of using PLGA microfibers for neural tissue regeneration as a guidance cue for hESC derived cells.