秦岭地区大林姬鼠的酯酶和苹果酸脱氢酶同工酶的研究

用聚丙烯酰胺凝胶等电聚焦电泳分析了大林姬鼠(Apodemus peninsulae)心、肝、脾、肾和腿肌的 α-酯酶,β-酯酶和苹果酸脱氢酶同工酶。结果表明3种同工酶的活性在5种器官组织中均有明显差异,其中以肝组织的酯酶活性最高,不同器官组织的酶谱也有明显差别,如脾的β一酯酶仅有B区带,同一器官组织通常以α-酯酶活性高于β-酯酶。苹果酸脱氢酶在碱性溶液中染色,肝组织有明显的AB医。心肌与腿肌的苹果酸脱氢酶活性略高于其他组织。     

Membrane interaction and activity of the glycolipid transfer protein

In this study we have addressed the ability of the glycolipid transfer protein (GLTP) to transfer anthrylvinyl-galactosylceramide at different pH and sodium chloride concentrations, and the ability of three different mutants to transfer the fluorescently labeled galactosylceramide between donor and acceptor model membranes. We constructed single tryptophan mutants with site-directed mutagenesis where two of the three tryptophan (W) of wild-type human GLTP were substituted with phenylalanine (F) and named W85 GLTP (W96F and W142F), W96 GLTP (W85F and W142F) and W142 GLTP (W85F and W96F) accordingly. Wild-type GLTP and W96 GLTP were both able to transfer anthrylvinyl-galactosylceramide, but the two variants W85 GLTP and W142 GLTP did not show any glycolipid transfer activity, indicating that the tryptophan in position 96 is crucial for transfer activity. Tryptophan fluorescence emission showed a blue shift of the maximal emission wavelength upon interaction of glycolipid containing vesicle with wild-type GLTP and W96 GLTP, while no blue shift was recorded for the protein variants W85 GLTP and W142 GLTP. The quantum yield of tryptophan emission was highest for the W96 GLTP protein whereas W85 GLTP, W142 GLTP and wild-type GLTP showed a lower and almost similar quantum yield. The lifetime and anisotropy decay of the different tryptophan mutants also changed upon binding to vesicles containing galactosylceramide. Again wild-type GLTP and W96 GLTP showed similar behavior in the presence of vesicles containing glycolipids. Taken together, our data show that the W96 is involved not only in the activity of the protein but also in the interaction between the protein and glycolipid containing membranes.     

Disruption of TGF-β signaling in smooth muscle cell prevents flow-induced vascular remodeling

Transforming growth factor-β (TGF-β) signaling has been prominently implicated in the pathogenesis of vascular remodeling, especially the initiation and progression of flow-induced vascular remodeling. Smooth muscle cells (SMCs) are the principal resident cells in arterial wall and are critical for arterial remodeling. However, the role of TGF-β signaling in SMC for flow-induced vascular remodeling remains unknown. Therefore, the goal of our study was to determine the effect of TGF-β pathway in SMC for vascular remodeling, by using a genetical smooth muscle-specific (SM-specific) TGF-β type II receptor (Tgfbr2) deletion mice model. Mice deficient in the expression of Tgfbr2 (MyhCre.Tgfbr2^f/f) and their corresponding wild-type background mice (MyhCre.Tgfbr2^WT/WT) underwent partial ligation of left common carotid artery for 1, 2, or 4 weeks. Then the carotid arteries were harvested and indicated that the disruption of Tgfbr2 in SMC provided prominent inhibition of vascular remodeling. And the thickening of carotid media, proliferation of SMC, infiltration of macrophage, and expression of matrix metalloproteinase (MMP) were all significantly attenuated in Tgfbr2 disruption mice. Our study demonstrated, for the first time, that the TGF-β signaling in SMC plays an essential role in flow-induced vascular remodeling and disruption can prevent this process.     

Tracing the origin and evolution of plant TIR-encoding genes

Toll-interleukin-1 receptor (TIR)-encoding proteins represent one of the most important families of disease resistance genes in plants. Studies that have explored the functional details of these genes tended to focus on only a few limited groups; the origin and evolutionary history of these genes were therefore unclear. In this study, focusing on the four principal groups of TIR-encoding genes, we conducted an extensive genome-wide survey of 32 fully sequenced plant genomes and Expressed Sequence Tags (ESTs) from the gymnosperm Pinus taeda and explored the origins and evolution of these genes. Through the identification of the TIR-encoding genes, the analysis of chromosome positions, the identification and analysis of conserved motifs, and sequence alignment and phylogenetic reconstruction, our results showed that the genes of the TIR-X family (TXs) had an earlier origin and a wider distribution than the genes from the other three groups. TIR-encoding genes experienced large-scale gene duplications during evolution. A skeleton motif pattern of the TIR domain was present in all spermatophytes, and the genes with this skeleton pattern exhibited a conserved and independent evolutionary history in all spermatophytes, including monocots, that followed their gymnosperm origin. This study used comparative genomics to explore the origin and evolutionary history of the four main groups of TIR-encoding genes. Additionally, we unraveled the mechanism behind the uneven distribution of TIR-encoding genes in dicots and monocots.     

Common co-lipids, in synergy, impart high gene transfer properties to transfection-incompetent cationic lipids

Efficacious cationic transfection lipids usually need either DOPE or cholesterol as co-lipid to deliver DNA inside the cell cytoplasm in non-viral gene delivery. If both of these co-lipids fail in imparting gene transfer properties, the cationic lipids are usually considered to be transfection inefficient. Herein, using both the reporter gene assay in CHO, COS-1 and HepG2 cells and the whole cell histochemical X-gal staining assay in representative CHO cells, we demonstrate that common co-lipids DOPE, Cholesterol and DOPC, when act in synergy, are capable of imparting improved gene transfer properties to a novel series of cationic lipids (1-5). Contrastingly, lipids 1-5 became essentially transfection-incompetent when used in combination with each of the pure co-lipid components alone.     

Polymorphisms of TNFalpha, IL1beta, and IL1RN genes in chronic obstructive pulmonary disease

It is recognized that genetic factors play a role in the susceptibility to COPD. COPD is characterized by airflow limitation. Chronic inflammation causes small airway disease and parenchymal destruction, leading to the airflow limitation. Polymorphisms in pro-inflammatory cytokine genes may confer a risk for the development of COPD. A case-control association study was performed in Japanese population (88 COPD patients and 61 controls) and Egyptian population (106 patients and 72 controls). Genotype and allele frequencies of the TNFalpha -308 G/A and +489 G/A polymorphisms, the IL1beta -511 C/T, -31 T/C, and +3954 C/T polymorphisms, and a VNTR polymorphism in intron 2 of the IL1RN gene were investigated. In addition, pairwise haplotype frequencies were analyzed. When studied independently, none of the polymorphisms were associated with the development of COPD in both populations. However, in the Egyptian population, the distributions of the haplotype (IL1beta -31 T/C : IL1beta +3954 C/T) were significantly different between the COPD patients and the controls (p(corr)=0.0037). Our findings suggest that this haplotype within the IL1beta gene may be involved in the pathogenesis of COPD and that the genetic factors of COPD susceptibility might be different between different populations.     

Microtubule destruction induces tau liberation and its subsequent phosphorylation

Neurofibrillary tangle-bearing neurons, a pathological hallmark of Alzheimer’s disease, are mostly devoid of normal microtubule (MT) structure and instead have paired helical filaments that are composed of abnormal hyperphosphorylated tau. However, a causal relationship between tau phosphorylation and MT disruption has not been clarified. To examine whether MT disruption induces tau phosphorylation, stathmin, an MT-disrupting protein, was co-expressed with tau in COS-7 cells. Stathmin expression induced apparent MT catastrophe and tau hyperphosphorylation at Thr-181, Ser-202, Thr-205, and Thr-231 sites. In contrast, c-Jun N-terminal kinase activation, or phosphatase inhibition, led to significant tau phosphorylation without affecting MT structure. These findings suggest that MT disruption induces subsequent tau phosphorylation.     

The Recombinant Amyloid-β Peptide Aβ1-42 Aggregates Faster and Is More Neurotoxic than Synthetic Aβ1-42

Aggregation of the amyloid-β (Aβ) peptide is considered a central event in the pathogenesis of Alzheimer's disease (AD). In order to bypass methodological bias related to a variety of impurities commonly present in typical preparations of synthetic Aβ, we developed a simple, generally applicable method for recombinant production of human Aβ and Aβ variants in Escherichia coli that provides milligram quantities of Aβ in very high purity and yield. Amyloid fibril formation in vitro by human Aβ1-42, the key amyloidogenic Aβ species in AD, was completed threefold faster with recombinant Aβ1-42 compared to synthetic preparations. In addition, recombinant Aβ1-42 was significantly more toxic to cultured rat primary cortical neurons, and it was more toxic in vivo, as shown by strongly increased induction of abnormal phosphorylation of tau and tau aggregation into neurofibrillary tangles in brains of P301L tau transgenic mice. We conclude that even small amounts of impurities in synthetic Aβ—including a significant fraction of racemized peptides that cannot be avoided due to the technical limitations of peptide synthesis—prevent or slow Aβ incorporation into the regular quaternary structure of growing β-amyloid fibrils. The results validate the use of recombinant Aβ1-42 for both in vitro and in vivo studies addressing the mechanisms underlying Aβ aggregation and its related biological consequences for the pathophysiology, therapy, and prevention of AD.