Role of transglutaminase-mediated cross-linking of protein in the temperature-dependent setting of Alaska pollack surimi

During the low temperature setting of fish paste, myosin heavy chain (MHC) is polymerized to cross-linked myosin heavy chain (CMHC), which is considered to occur by the action of endogenous transglutaminase (TGase). In this study the contribution of TGase on the setting of Alaska pollack surimi at different temperatures was studied. Alaska pollack surimi was ground with 3% NaCl, 30% h2o and with or without ethylene glycol bis (β-aminoethylether) N, N, N¹,N¹- tetra acetic acid (EGTA), an inhibitor of TGase. Among the pastes without EGTA, highest TGase activity was observed at 25°C but breaking force of the gel set at 25°C was lower than that set at 30°, 35°, and 40°C. Addition of EGTA (5m mol/kg) to the paste suppressed TGase activity at all setting temperatures from 20° to 40°C. Gelation of the pastes and cross-linking of MHC on addition of EGTA were suppressed completely at 20° and 25°C, partially at 30° and 35°C, and not at all at 40°C. The findings suggested that during the setting of Alaska pollack surimi TGase mediated cross-linking of MHC was strong at around 25°C but the thermal aggregation of MHC by non-covalent bonds was strong at above 35°C. Setting of surimi at 40°C and cross-linking of its MHC did not involve TGase.

Major histocompatibility complex class I involvement in the rejection of allogeneic erythrocytes in rainbow trout (Oncorhynchus mykiss)

Major histocompatibility complex genes are thought to be involved in allogeneic graft rejection but not many reports are available on their functional analysis in fish. Analysis of available sequences of MHC genes suggests functions in antigen presentation similar to those found in higher vertebrates. In mammals, the MHC class I and class II molecules are major determinants of allogeneic graft rejection due to their polymorphism in conjunction with their antigen presenting function. In fish, MHC class H molecules are found to be involved in rejection of allogeneic scale grafts. The present study was designed to investigate the involvement of MHC class I molecules in allograft rejection. Erythrocytes were collected from donors of rainbow trout expressed different class MHC class I alleles, stained with two dyes, mixed and grafted to the recipients that were of the same sibling group as the donors. The grafts were rejected by allogeneic recipients and the MHC class I linkage group was the major determinant for the rejection.

Species Variation in the Mechanisms of Mesenchymal Stem Cell-Mediated Immunosuppression

Bone marrow-derived mesenchymal stem cells (MSCs) hold great promise for treating immune disorders because of their immunoregulatory capacity, but the mechanism remains controversial. As we show here, the mechanism of MSC-mediated immunosuppression varies

Repetitive element-mediated recombination as a mechanism for new gene origination in Drosophila

Previous studies of repetitive elements (REs) have implicated a mechanistic role in generating new chimerical genes. Such examples are consistent with the classic model for exon shuffling, which relies on non-homologous recombination. However, recent data

Enhancement of GABAA Receptor-Mediated Inhibitory Postsynaptic Currents Induced by "Partial Oxygen-Glucose Deprivation

下载PDF阅读器"氧糖剥夺"模型作为研究脑缺血的离体模型被广泛使用,该模型模拟了局灶性脑缺血的主要病理变化.然而在缺血病灶核心区与正常脑组织之间称为缺血半暗带的区域,脑血流也有程度不一的降低.为了模拟这种病理变化,发展了一种"不完全氧糖剥夺"的离体脑片模型,该模型满足两个条件,灌流液里氧气部分剥夺而葡萄糖含量降低;"氧糖剥夺"可以导致谷氨酸介导的兴奋性毒性,从而引起神经细胞的坏死.而A型γ-氨基丁酸受体(GABAAR)介导的神经元抑制性活动可以对抗谷氨酸引起的兴奋性毒性,因此近年来引起广泛的研究兴趣.而谷氨酸受体和γ-氨基丁酸受体功能在缺血半暗带是否有改变尚不得而知.因此本文采用海马脑片全细胞膜片钳的记录方法,研究"不完全氧糖剥夺"对海马CA1区神经元的A型γ-氨基丁酸受体介导的抑制性突触后膜电流(IPSCs)的影响.研究发现"不完全氧糖剥夺"使GABAAR介导的IPSCs的峰值增加而衰减时程延长.进一步研究发现该电流的峰值增加是由于GABAAR-氯离子通道的电导增加所致,而与氯离子的反转电位变化无关.这些发现提示在脑缺血的缺血半暗带区域GABAAR介导的神经元抑制性活动可能是增强的,这可能是神经元面对缺血状态产生自我保护的一种内稳态机制.