Modulation of the chemokines KC and MCP-1 by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in mice

Activation of the aryl hydrocarbon receptor (AhR) by TCDD may lead to the induction of proinflammatory cytokines in various cell types and organs such as liver leading to active chronic inflammation. Here we studied the expression of the chemokines keratinocyte chemoattractant (KC) and monocyte chemoattractant protein 1 (MCP-1) in different organs of mice after exposure to TCDD. TCDD exposure led to an early and clear induction of KC in liver and spleen on day 1 which was sustained over a period of 10 days. The level of MCP-1 mRNA was induced by TCDD on day 1 in spleen, lung, kidney, and liver, which was further increased at day 7. Increase of KC and MCP-1 at day 7 in liver, thymus, kidney, adipose, and heart was associated with elevated levels of the macrophage marker F4/80, indicating the infiltration of macrophages in these organs. Induction of KC requires a functional AhR since mice with a mutation in the AhR nuclear localization domain (AhR(nls)) were found to be resistant to TCDD-induced expression of KC. These results are the first showing the induction of the chemokines KC and MCP-1 in multiple organs of mice associated with an increase of the macrophage marker F4/80 indicating the involvement in TCDD's inflammatory response like infiltration of macrophages.     

Isolation and identification of mesenchymal stem cells from human lipoma tissue

Lipoma is a benign neoplasm of normal fat cells that appears as a soft, movable swelling, often with a slight yellowish coloration. Human mesenchymal stem cells (MSCs) that have been isolated from bone marrow, blood, and other adult tissues including adipose tissue have the potential to be useful candidates for therapy. No literature had reported about stem cells from lipoma tissue. Here, a new cell culture method is described and utilized to greatly accelerate the growth rate and prolong the lifespan of lipoma-derived MSCs. Cells produced in early cultures display characteristics similar to those previously reported for multipotential stem cells, including a high frequency of anchorage-independent growth in soft agar and a lack of gap junctional intercellular communication in cell types with serpiginous morphology. These cells can differentiate into adipocytes, osteoblasts, and chondrocytes after induction. In conclusion, lipoma-derived stem cells possessing the characteristics of MSCs are described for the first time.     

The insertion of the antimicrobial peptide dicynthaurin monomer in model membranes: thermodynamics and structural characterization

This paper is focused on the thermodynamics and the structural investigation of the interaction of the antimicrobial peptide dicynthaurin monomer with model lipid membranes composed of mixtures of 1-palmitoyl-2-oleyl-glycerophosphocholine and -glycerophosphoglycerol. The thermodynamic binding parameters as obtained by isothermal titration calorimetry reveal strong binding toward the lipid model system dominated by large chemical binding constants which exceeds the electrostatic binding effects and thus suggests insertion of the amphipathic alpha-helical peptide into the hydrophobic membrane core. Circular dichroism study shows that the peptide exhibits trans-membrane alpha-helix secondary structure. Neutron diffraction measurements using partially deuterated sequences were successfully applied to determine the orientation of the peptide thus proving insertion into the hydrophobic membrane core. This insertion and the formation of higher order porelike aggregates is assumed to be the most relevant event in microbial membrane perturbation that in vivo finally leads to bacterial cell death on a fast time scale.     

Phylogenetic Analysis of AA-genome Oryza Species (Poaceae) Based on Chloroplast, Mitochondrial, and Nuclear DNA Sequences

Species in the genus Oryza (Poaceae) contain 10 genomic types and are distributed in pan-tropics of the world. To explore phylogenetic relationships of Oryza species having the AA-genome, DNA sequences of the chloroplast trnL intron and trnL-trnF spacer, mitochondrial nad1 intron 2, and nuclear internal transcribed spacer were analyzed, based on materials from 6 cultivated (O. sativa and O. glaberrima) and 13 wild accessions, in addition to a CC-genome species (O. officinalis) that was used as an outgroup. Analyses of the combined sequence data set from different sources provide a much better resolution of the AA-genome species than the individual data set, indicating the limitation of a single gene in phylogenetic reconstruction. The phylogeny based on the combined data set demonstrated an apparent grouping of the AA-genome Oryza species that was well associated with their geographic origin, although the Australian O. meridionalis showed its affinity with the African species. The geographic pattern of the phylogenetic relationship was probably attributed to the frequent genetic exchange and introgression among the AA-genome species from the same continents. In addition, Asian cultivated rice O. sativa showed its close relation to O. rufipogon and O. nivara, whereas African cultivated rice O. glaberrima was closely linked to O. barthii and O. longistaminata, indicating the independent domestication of the two cultivated species in different geographic locations.     

Evolution of enzymatic activities in the enolase superfamily: L-talarate/galactarate dehydratase from Salmonella typhimurium LT2

We assigned l-talarate dehydratase (TalrD) and galactarate dehydratase (GalrD) functions to a group of orthologous proteins in the mechanistically diverse enolase superfamily, focusing our characterization on the protein encoded by the Salmonella typhimurium LT2 genome (GI:16766982; STM3697). Like the homologous mandelate racemase, l-fuconate dehydratase, and d-tartrate dehydratase, the active site of TalrD/GalrD contains a general acid/base Lys 197 at the end of the second beta-strand in the (beta/alpha)7beta-barrel domain, Asp 226, Glu 252, and Glu 278 as ligands for the essential Mg2+ at the ends of the third, fourth, and fifth beta-strands, a general acid/base His 328-Asp 301 dyad at the ends of the seventh and sixth beta-strands, and an electrophilic Glu 348 at the end of the eighth beta-strand. We discovered the function of STM3697 by screening a library of acid sugars; it catalyzes the efficient dehydration of both l-talarate (kcat = 2.1 s-1, kcat/Km = 9.1 x 10(3) M-1 s-1) and galactarate (kcat = 3.5 s-1, kcat/Km = 1.1 x 10(4) M-1 s-1). Because l-talarate is a previously unknown metabolite, we demonstrated that S. typhimurium LT2 can utilize l-talarate as carbon source. Insertional disruption of the gene encoding STM3697 abolishes this phenotype; this disruption also diminishes, but does not eliminate, the ability of the organism to utilize galactarate as carbon source. The dehydration of l-talarate is accompanied by competing epimerization to galactarate; little epimerization to l-talarate is observed in the dehydration of galactarate. On the basis of (1) structures of the wild type enzyme complexed with l-lyxarohydroxamate, an analogue of the enolate intermediate, and of the K197A mutant complexed with l-glucarate, a substrate for exchange of the alpha-proton, and (2) incorporation of solvent deuterium into galactarate in competition with dehydration, we conclude that Lys 197 functions as the galactarate-specific base and His 328 functions as the l-talarate-specific base. The epimerization of l-talarate to galactarate that competes with dehydration can be rationalized by partitioning of the enolate intermediate between dehydration (departure of the 3-OH group catalyzed by the conjugate acid of His 328) and epimerization (protonation on C2 by the conjugate acid of Lys 197). The promiscuous catalytic activities discovered for STM3697 highlight the evolutionary potential of a "conserved" active site architecture.     

Role of p38 mitogen-activated protein kinase pathway in estrogen-mediated cardioprotection following trauma-hemorrhage

p38 mitogen-activated protein kinase (MAPK) activates a number of heat shock proteins (HSPs), including HSP27 and alpha(B)-crystallin, in response to stress. Activation of HSP27 or alpha(B)-crystallin is known to protect organs/cells by increasing the stability of actin microfilaments. Although our previous studies showed that 17beta-estradiol (E(2)) improves cardiovascular function after trauma-hemorrhage, whether the salutary effects of E(2) under those conditions are mediated via p38 MAPK remains unknown. Male rats (275-325 g body wt) were subjected to soft tissue trauma and hemorrhage (35-40 mmHg mean blood pressure for approximately 90 min) followed by fluid resuscitation. At the onset of resuscitation, rats were injected intravenously with vehicle, E(2) (1 mg/kg body wt), E(2) + the p38 MAPK inhibitor SB-203580 (2 mg/kg body wt), or SB-203580 alone, and various parameters were measured 2 h thereafter. Cardiac functions that were depressed after trauma-hemorrhage were returned to normal levels by E(2) administration, and phosphorylation of cardiac p38 MAPK, HSP27, and alpha(B)-crystallin was increased. The E(2)-mediated improvement of cardiac function and increase in p38 MAPK, HSP27, and alpha(B)-crystallin phosphorylation were abolished with coadministration of SB-203580. These results suggest that the salutary effect of E(2) on cardiac function after trauma-hemorrhage is in part mediated via upregulation of p38 MAPK and subsequent phosphorylation of HSP27 and alpha(B)-crystallin.     

ROS介导的蛋白质氧化的生化机制

活性氧（reactive oxygen species,ROS）介导蛋白质氧化的生化机制。ROS可以通过直接诱导蛋白质主链和侧链氧化,也可通过脂质过氧化和糖基化等过程间接诱导蛋白质氧化,从而导致蛋白质主链断裂、侧链β-切除、蛋白质羰基化以及蛋白质-蛋白质交联,最终导致机体生理和病理的改变,乃至加速衰老过程。该文介绍ROS介导蛋白质氧化的生化机制。     

含不同Anti-Waxy基因拷贝数的稻米直链淀粉含量分析

将含单拷贝Anti-Waxy基因的纯合植株分别作为父本或母本进行正反交,获得两组含双拷贝Anti-Waxy基因的杂交后代,分析了未转基因对照、转基因亲本及两组杂交后代糙米直链淀粉含量以揭示不同Anti-Waxy基因拷贝数对降低稻米直链淀粉含量程度的影响.结果显示,2个单拷贝转基因水稻糙米直链淀粉平均含量分别为10.72%和11.13%,比对照分别降低17.98%和14.84%;两组正交和反交杂交后代糙米直链淀粉平均含量分别为8.96%和8.23%,其平均值为8.60%,比2个转基因杂交亲本糙米直链淀粉含量分别降低19.78%和22.73%,比对照降低了34.20%.结果表明,增加转基因水稻基因组中Anti-Waxy基因拷贝数在一定程度上能够进一步降低稻米直链淀粉含量,通过将独立转化获得同品种转基因植株之间杂交可以成为获得高表达转基因植物的途径.