Variations of thioredoxin system contributes to increased susceptibility to apoptosis in cardiomyocytes of type 2 diabetic rats

Cardiac complications are the leading cause of death in diabetes. However, the mechanism of diabetes in inducing myocardial injury and apoptosis, and whether the thioredoxin （Trx） system is involved remain unclear. In this study, male Sprague-Dawley rats were randomly divided into two groups： the control and the diabetes groups, and then were randomly divided into five different timepoints （the 1st, 2nd, 4th, 12th, and 24th week）. The results showed that diabetes-induced cardiac injury was enhanced in the type 2 diabetes rats, as evidenced by aggravated cardiac dysfunction, biochemical indicators, and increased myocardial apoptosis （TUNEL and caspase-3 activity）. The activity of myocardial Trx and Trx reductase （TR） in diabetic rats was significantly decreased from the second week and continually aggravated with the disease progression. In diabetic rats, the mRNA expression of Trxl, Trx2, TR1, and TR2 was decreased first and then increased after the fourth week. Meanwhile, the protein expression of these Trx system members was significantly increased at the 12th week. Trx nitration was cleared, the Trx/ASK1 interaction was significantly decreased, and the activity of p38 was significantly enhanced in cardiac tissues at the 12th week. These results demonstrated that diabetes may cause myocardial injury and apoptosis, and the extent of which was accompanied with the development of the disease. The mechanism is associated with the development of diabetes and the decreased activity of Trx and TR. The reasons for decreased Trx activity may include： decrease of Trx and TR protein expression; nitration modification of Trx; and up-regulation of TXNIP expression.     

不同林龄油茶人工林土壤酶化学计量及其影响因素

土壤酶化学计量比是揭示微生物生长代谢过程及评价土壤养分资源限制状况的重要指标。油茶是中国南方主要的木本油料作物,近年来愈来愈受关注,但鲜有从生态化学计量学的角度深入理解人工经济林的土壤微生物养分限制状况。本文以亚热带地区不同林龄油茶人工林土壤为研究对象,采用时空互代法在区域尺度上随机选取32个不同林龄油茶人工林并将其分为四个林龄组(9年幼龄林;9—20年近熟林;21—60年成熟林; 60年过熟林),通过测定土壤碳(C)、氮(N)、磷(P)转化酶活性(β-葡糖苷酶(BG)、α-纤维素酶(CBH)、β-乙酰葡糖胺糖苷酶(NAG)、亮氨酸氨基肽酶(LAP)、酸性磷酸酶(AP))及土壤理化因子,探讨不同林龄油茶人工林土壤C、N、P转化酶化学计量特征及其与土壤理化因子的关系。结果表明:五种C、N、P转化酶活性均有随林龄增大而增加的趋势,且AP活性显著高于其它四种酶活性。相关分析结果表明,五种土壤C、N、P转化酶活性均与土壤有机碳和总氮显著相关,与土壤总磷和速效磷含量不相关。土壤酶化学计量比ln(CBH+BG)∶ln(NAG+LAP)、ln(CBH+BG)∶ln(AP)和ln(NAG+LAP)∶ln(AP)均随林龄增大而一定程度增加。亚热带区油茶人工林土壤酶C∶N∶P化学计量比为1∶1∶1.5,这与全球生态系统土壤酶C∶N∶P化学计量比1∶1∶1相偏离,表明亚热带地区油茶人工林土壤微生物生长受磷素限制。冗余分析(RDA)进一步揭示土壤有机碳含量是影响土壤酶活性和酶化学计量比的主要因子。因此,在油茶人工林经营管理中应考虑磷和外源碳的投入,提高土壤微生物酶活性,缓解油茶人工林生态系统的磷限制。研究结果可为亚热带区油茶人工林土壤养分管理和可持续利用提供基础理论支撑。     

Casparian strips in needles are more solute permeable than endodermal transport barriers in roots of Pinus bungeana

The structure and development of endodermal Casparian strips in Pinus bungeana needles and roots were studied by scanning electron microscopy and fluorescence microscopy. Primary pit fields (PFs) frequently occurred in radial walls of Casparian strips isolated from needles, whereas PFs were never detected in Casparian strips from roots. Formation of Casparian strips in needles as well as roots started at the outer parts of the radial walls and they finally occupied the entire radial walls of the endodermis. Fourier transform infrared (FTIR) spectroscopy of Casparian strips isolated from roots revealed significant absorption bands characteristic for suberin. However, in Casparian strips of needles, evidence for suberin was rarely detected by FTIR spectroscopy. The apoplastic permeability of Casparian strips in needles and roots was probed by the apoplastic tracers calcofluor and berberine. Casparian strips in roots efficiently blocked the apoplastic transport (AT) of calcofluor and berberine. Casparian strips in needles blocked the AT of calcofluor, but diffusion of berberine was not inhibited and berberine thiocyanate crystals were detectable in the vascular tissue of the needles. From the data presented, it must be concluded that Casparian strips in needles, which are characterized by the absence of suberin, are more solute permeable compared with Casparian strips in roots.     

Protein structure preference, tRNA copy number, and mRNA stem/loop content

From statistical analyses of protein sequences for humans and Escherichia coli we found that the messenger RNA segment of m-codons (for m=2 to 6) with average high tRNA copy number (TCN) (larger than approximately 10.5 for humans or approximately 1.95 for E. coli) preferably code for the alpha helix and that with low TCN (smaller than approximately 7.5 for humans or approximately 1.7 for E. coli) preferably code for coil. Between them there is an intermediate region without correlation to structure preference. For the beta strand the preference/ avoidance tendency is not obvious. All strong preference-modes of TCN for protein secondary structures have been deduced. The mutual interaction between two factors--protein secondary structural type and codon TCN--is tested by F distribution. A phenomenological model on the relation between structure preference and translational efficiency or accuracy is proposed. It is pointed out that the structure preference of codons is related to the distribution of mRNA stem/loop content in three TCN regions.     

Detailed kinetic studies of an aggregating inhibitor; inhibition of phosphomannomutase/phosphoglucomutase by disperse blue 56

Phosphomannomutase/phosphoglucomutase occupies a central position in the pathways by which several virulence factors are synthesized in Pseudomonas aeruginosa. Virtual screening was used to identify potential inhibitors of phosphomannomutase/ phosphoglucomutase, and one compound, the anthraquinone-based dye Disperse Blue 56, showed potent inhibition in vitro. The kinetics of inhibition was complex; the time courses for reactions in the presence of the inhibitor were biphasic, suggestive of slow-binding inhibition. Quantitative analysis of the progress curves and preincubation experiments demonstrated that slow-binding inhibition was not occurring, however. Initial velocity kinetic studies indicated that Disperse Blue 56 was a parabolic, noncompetitve inhibitor. Progress curves for reactions in the presence of Disperse Blue 56 could be fitted very well by a model in which 2 equiv of the inhibitor bound to free enzyme or the enzyme-substrate complex. The inhibition was largely relieved by the inclusion of 0.01% Triton X-100 in the assay solutions, which has been suggested to be the hallmark for inhibition by compounds that exert their effect through aggregates [McGovern, S. L., Caselli, E., Grigorieff, N., and Shiochet, B. K. (2002) J. Med. Chem. 45, 1712-1722]. Our kinetic data appear to be consistent with either inhibition by a dimer of Disperse Blue 56 or inhibition by a Disperse Blue 56 aggregate, but the latter appears much more likely. We present a detailed analysis of the system to provide further information that may help in the recognition of inhibition through aggregation.     

Vector prime/protein boost vaccine that overcomes defects acquired during aging and cancer

We showed that the Ad-sig-TAA/ecdCD40L vaccine induces a tumor suppressive immune response to the hMUC-1 and rH2N tumor-associated self Ags (TAA) and to the Annexin A1 tumor vascular Ag, even in mice in which anergy exists to these Ags. When the TAA/ecdCD40L protein is given s.c. as a boost following the Ad-sig-TAA/ecdCD40L vector, the levels of the TAA-specific CD8 T cells and Abs increase dramatically over that seen with vector alone, in young (2-mo-old) as well as old (18-mo-old) mice. The Abs induced against hMUC-1 react with human breast cancer. This vaccine also induces a 4-fold decrement of negative regulatory CD4CD25FOXP3-T cells in the tumor tissue of 18-mo-old mice. These results suggest that the Ad-sig-TAA/ecdCD40L vector prime-TAA/ecdCD40L protein boost vaccine platform may be valuable in reducing postsurgery recurrence in a variety of epithelial neoplasms.     

Hydrophilic anilinogeranyl diphosphate prenyl analogues are Ras function inhibitors

Sequential processing of H-Ras by protein farnesyl transferase (FTase), Ras converting enzyme (Rce1), and protein-S-isoprenylcysteine O-methyltransferase (Icmt) to give H-Ras C-terminal farnesyl-S-cysteine methyl ester is required for appropriate H-Ras membrane localization and function, including activation of the mitogen-activated protein kinase (MAPK) cascade. We employed a Xenopus laevis oocyte whole-cell model system to examine whether anilinogeranyl diphosphate analogues of similar shape and size, but with a hydrophobicity different from that of the FTase substrate farnesyl diphosphate (FPP), could ablate biological function of H-Ras. Analysis of oocyte maturation kinetics following microinjection of in vitro analogue-modified H-Ras into isoprenoid-depleted oocytes revealed that analogues with a hydrophobicity near that of FPP supported H-Ras biological function, while the analogues p-nitroanilinogeranyl diphosphate (p-NO2-AGPP), p-cyanoanilinogeranyl diphosphate (p-CN-AGPP), and isoxazolaminogeranyl diphosphate (Isox-GPP) with hydrophobicities 2-5 orders of magnitude lower than that of FPP did not. We found that although H-Ras modified with FPP analogues p-NO2-AGPP, p-CN-AGPP, and Isox-GPP was an efficient substrate for C-terminal postprenylation processing by Rce1 and Icmt, co-injection of H-Ras with analogues p-NO2-AGPP, p-CN-AGPP, or Isox-GPP could not activate MAPK. We propose that H-Ras biological function requires a minimum lipophilicity of the prenyl group to allow important interactions downstream of the C-terminal processed H-Ras protein. The hydrophilic FPP analogues p-NO2-AGPP, p-CN-AGPP, and Isox-GPP are H-Ras function inhibitors (RFIs) and serve as lead compounds for a unique class of potential anticancer therapeutics.     

Differences in mtDNA whole sequence between Tibetan and Han populations suggesting adaptive selection to high altitude

We performed a mitochondrial whole-genome comparison study in 40 Tibetan and 50 Han Chinese. All subjects could be classified into 13 haplogroups pertained to the Macrohaplogroup M and N that pitched different quadrants by principal component analysis. We observed a difference in the M9 haplogroup and identified 18 significant variants by comparing whole sequences between Tibetan and Han populations. Variants in ND2, COX2, tRNA alanine and 12S rRNA were predicted to confer increased protein stability in Tibetans. We compared the base substitutions of nonsynonymous (NS) versus synonymous (S) of 13 protein-encoding genes and found the NS/S values of the ATP6, ATP8, and Cyt b genes were larger (>1) in Tibetans than that in Han population. Our findings provide clues for the existence of adaptive selection for the ATP6, ATP8, Cyt b, ND2, COX2, tRNA alanine and 12S rRNA genes in Tibetans which likely contributed to adaptation to their specific geographic environment, such as high altitude.     

Functional dioecy in <Emphasis Type="Italic">Morinda parvifolia</Emphasis> (Rubiaceae), a species with stigma-height dimorphism

The evolution of dioecy from heterostyly has been well documented, but detailed studies on this transitional process are rare. Here we report the occurrence of cryptic dioecy in a perennial liana species with stigma-height dimorphism, Morinda parvifolia Bartl. ex DC. (Rubiaceae). Floral morphology, ancillary characters and cross compatibility of long-styled (L-morph) and short-styled (S-morph) were examined. L-morph and S-morph display obvious pistil dimorphisms, with the stigma of S-morph lacking papillae cells. Both floral morphs show similar pollen morphology, although pollen viability is higher in S-morph than in L-morph. S-morph flowers produce viable pollen grains but much reduced stigma and set no fruits, functioning as males; L-morphs, although with viable pollen grains and receptive stigmas, exhibit strong self- and intramorph incompatibility, with self- and intramorph pollen tubes arrested in the stigma lobes and the upper part of style, respectively, resulting in L-morphs functioning only as females. The species thus has physiological androdioecy but functional dioecy. This might be the first case showing the possibility that androdioecy could be a mid-stage in the pathway of dioecy evolving from stigma-height dimorphism.