Changes of proximate and fatty acid compositions of the dorsal and ventral ordinary muscles of the full-cycle cultured Pacific bluefin tuna Thunnus orientalis with the growth

Using the full-cycle cultured (FC) Pacific bluefin tuna, Thunnus orientalis [body weights: 13.1 ± 4.5 (FC1; April in 2004), 20.2 ± 1.8 (FC2; July in 2004), 28.5 ± 6.3 (FC3; November in 2004), 27.0 ± 3.3 (FC4; February in 2005) and 33.5 ± 4.7 kg (FC5; May in 2005), n = 3, respectively] and wild bluefin tuna [33.3 ± 1.5kg (June in 2005), n = 3], proximate and fatty acid compositions of the cephalal (Ce-) and caudal (Ca-) parts of the dorsal (D) and ventral (V) ordinary muscles (OMs) were investigated. Lipid contents of the Ce-DOM and VOMs of FC1-5 increased with growth. In particular, lipid content of the Ce-DOM (23.0%) and VOMs (55.1%) of FC5 was higher (P < 0.05) than those of wild tuna [D-(2.0%) and VOMs (16.2%)]. However, lipid contents of the Ca-DOM and VOMs of FC1-5 did not change with growth. On the other hand, the fatty acid compositions of the Ce-DOM and VOMs of FC2-5 resembled each other. However, there was no specific tendency of the changes of each fatty acid composition of the Ce-DOM of FC tuna with growth. On the other hand, total monounsaturated fatty acid content (30.1%) of the Ce-DOM of FC5 was higher (P < 0.05) than that (25.5%) of wild tuna. The ratio of n–3: n–6 (9.4%) of the Ce-VOM of FC5 was lower (P < 0.05) than that (14.0%) of wild tuna. However, the fatty acid compositions of the Ce-DOM and VOMs of FC tuna were not reflected by those of feed (whole fish bodies of sesame mackerel).     

Chelation and reduction of iron by chicken muscle protein digests: the role of sulphhydryl groups

The role of sulphhydryls in the chelation and reduction of iron by digests of chicken muscle was investigated. The salt‐soluble (DSSP) and myofibrillar (DSIP) proteins were extracted from chicken muscle and digested with pepsin/pancreatin, and the digests were then incubated with ferric iron. The DSIP digest bound twice as much iron as the DSSP digest; about half the bound iron was ferrous. Iron binding was accompanied by a 74% drop in free sulphhydryls in the DSSP digest and a 72% drop in the DSIP digest. Modification of sulphhydryls in the digests by either oxygen, N‐ethylmaleimide or p‐chloromercuribenzoate led to a loss of ～90% in reactive sulphhydryl groups and was accompanied by losses in iron binding which averaged 79% for DSSP and 67% for DSIP. Losses in ferrous bound iron were proportional to the loss in total bound iron. It was concluded that for the muscle protein fractions, sulphhydryl residues are the principal component responsible for iron binding, but that other residues may play a minor role. © 2001 Society of Chemical Industry     

Extension of the Pre-rigor Period in Ischemic White Muscle from Yellow-eye Mullet Aldrichetta forsteri) and New Zealand Snapper (Pagrus auratus) as Affected by Hyperbaric Oxygen Treatment

ABSTRACT: Chemical anesthesia (AQUI-STM Plus) was used to harvest tank-rested yellow-eye mullet ( Aldrichetta forsteri ) and snapper ( Pagrus auratus ) in a "rested" state. Fillets were stored at half the acclimated temperature under hyperbaric, hyperoxic conditions and compared with fillets stored under normobaric, hyperoxic conditions. Postmortem (PM) changes in white muscle (WM) cut-surface pH and key metabolites (lactate, adenosine triphosphate [ATP], and inorganic phosphate [P i ]) were measured. Hyperbaric, hyperoxic storage extended the pre-rigor period in the rested WM by delaying PM changes. Prolongation of pre-rigor was greatest in rested snapper WM. This was attributed to an extended period of aerobic metabolism in PM rested WM.     

Dystrophin Cleavage and Sarcolemma Detachment are Early Post Mortem Changes on Bass (Dicentrarchus labrax) White Muscle

Using specific dystrophin antibodies directed against a conserved C-terminal sequence, we demonstrated that dystrophin of fish white muscle was quickly degraded by 50% within 24h and by 100% within 2 days, in parallel with titin cleavage and alpha-actinin release from Z-disks. These changes were accompanied by sarcolemma detachment from the myofibers in costameres (the structures containing dystrophin) and Z-disks weakening. For muscle stored during 2 to 6 mo before thawing, total dystrophin disappearance was observed at 4°C in <8h. Dystrophin may serve as a marker for stored fish to evaluate post mortem changes or detect a thawing-freezing process.     

Development of Intrinsic Fluorescent Multispectral Imagery Specific for Fat, Connective Tissue, and Myofibers in Meat

ABSTRACT: Intrinsic fluorescent properties of muscle tissue were evaluated in order to characterize the different structural components of meat. The combinations of excitation and emission wavelengths showing the best ability to distinguish the 3 components were 290/332 nm for myofiber, 322/440 (or 322/405) nm for fat, and 380/440 nm for connective tissue. Sample orientation and the mincing of meat samples affected fluorescent amplitudes but not the overall shape of the spectra. These emission spectra of meat components were used to make multispectral images to determine whether the 3 components could be distinguished. The results show that auto fluorescence can be used for selective visualization of fat, fiber, and connective tissue on digitized images of meat.     

Texture Properties of Farmed Rainbow Trout (Oncorhynchus mykiss): Effects of Diet,Muscle Fat Content and Time of Storage on Ice

Groups of rainbow trout (Oncorhynchus mykiss) fed diets with low or high fat content were stored on ice for up to 11 days in two separate experiments. After 4, 9 and 11 days storage on ice in the first experiment and after 5, 8 and 11 days in the second experiment the fish were filleted by hand and fillet gaping was evaluated. Texture properties were studied using an Instron compression test. pH was measured in all fillets. In fillets from the second experiment, also fat content and autolytic protease activity were measured. Diet affected fillet fat content and texture properties. Fish fed high fat diet exerted less resistance against compression, indicating a softer consistency. Force at yield point and slope were not significantly affected by diet. The high fat group had higher autolytic protease activity than the low fat group. The results from the Instron measurements indicated that the fish became softer and less tough during 11 days storage on ice. A slight, but statistically significant increase in pH with time was observed in both experiments. In the first experiment a reduction in gaping scores was observed during storage, as opposed to a significant increase in the second experiment. The texture parameters yield point and slope were negatively correlated to gaping in the second experiment.     

维库溴铵的合成工艺改进

以表雄酮为原料经磺酸酯化、消去、酯化、氧化、开环、还原、乙酰化,最后和溴甲烷成盐等8步反应合成维库溴铵,操作简捷、条件温和、成本低,适合工业化生产,产品结构经红外光谱、核磁共振谱、质谱确证,总收率19.6%.     

丹酚酸对大鼠骨骼肌缺血再灌注损伤的保护

目的：分析丹酚酸通过AKT/mTOR/p70S6K信号通路对骨骼肌缺血再灌注损伤小鼠细胞自噬及凋亡的影响。方法：选取SPF级雄性大鼠45只,随机数字表法分为假手术组、模型组、丹酚酸组,模型组、丹酚酸组制备骨骼肌缺血再灌注损伤模型,丹酚酸组分别在开始实验前72 h、48 h、24 h及再灌注前15 min,腹腔注射剂量为30 mg/kg的丹酚酸溶液1 mL,假手术组和模型组大鼠腹腔注射生理盐水1 mL。观察各组大鼠腓肠肌组织病理形态,血清肌酸激酶（CK）、乳酸脱氢酶（LDH）含量,腓肠肌组织Akt、p-Akt、p70S6K、p-p70S6K、mTOR及p-mTOR蛋白表达及腓肠肌组织内Bcl-2、Bax表达。结果： 再灌注0 h、4 h及24 h时模型组大鼠腓肠肌湿/干重（W/D）比值较假手术组升高,丹酚酸组腓肠肌W/D比值较模型组降低,差异有统计学意义（P<0.05）;再灌注0 h、4 h及24 h时模型组大鼠血清LDH、CK含量较假手术组升高,丹酚酸组大鼠血清LDH、CK含量较模型组降低,差异有统计学意义（P<0.05）;模型组大鼠腓肠肌Akt蛋白表达较假手术组降低,p-Akt蛋白表达较假手术组升高;丹酚酸组大鼠Akt、p-Akt、p70S6K、p-p70S6K、mTOR及p-mTOR蛋白表达较模型组升高,差异有统计学意义（P<0.05）;光密度值（IOD）量化腓肠肌细胞内Bax、Bcl-2蛋白表达,模型组Bcl-2 IOD数值、Bcl-2/Bax比值较假手术组降低,Bax IOD数值较假手术组增加;丹酚酸组Bcl-2 IOD数值、Bcl-2/Bax比值较模型组升高,Bax IOD数值较模型组降低,差异有统计学意义（P<0.05）。结论：丹酚酸可维持骨骼肌缺血再灌注损伤大鼠骨骼细胞Bax与Bcl-2动态平衡,抑制细胞凋亡,其作用机制可能和激活AKT/mTOR/p70S6K信号通路有关。     

Ionic Silicon Protects Oxidative Damage and Promotes Skeletal Muscle Cell Regeneration

Volumetric muscle loss injuries overwhelm the endogenous regenerative capacity of skeletal muscle, and the associated oxidative damage can delay regeneration and prolong recovery. This study aimed to investigate the effect of silicon-ions on C2C12 skeletal muscle cells under normal and excessive oxidative stress conditions to gain insights into its role on myogenesis during the early stages of muscle regeneration. In vitro studies indicated that 0.1 mM Si-ions into cell culture media significantly increased cell viability, proliferation, migration, and myotube formation compared to control. Additionally, MyoG, MyoD, Neurturin, and GABA expression were significantly increased with addition of 0.1, 0.5, and 1.0 mM of Si-ion for 1 and 5 days of C2C12 myoblast differentiation. Furthermore, 0.1–2.0 mM Si-ions attenuated the toxic effects of H₂O₂ within 24 h resulting in increased cell viability and differentiation. Addition of 1.0 mM of Si-ions significantly aid cell recovery and protected from the toxic effect of 0.4 mM H₂O₂ on cell migration. These results suggest that ionic silicon may have a potential effect in unfavorable situations where reactive oxygen species is predominant affecting cell viability, proliferation, migration, and differentiation. Furthermore, this study provides a guide for designing Si-containing biomaterials with desirable Si-ion release for skeletal muscle regeneration.