自然干燥对冬虫夏草寄主蝠蛾卵孵化的影响

研究在室内自然空气湿度下放置的时间长短对冬虫夏草(Cordyceps)寄主昆虫贡嘎蝠蛾Hepialus gonggaensis Fu et Huang卵孵化率的影响。卵早期的研究结果为:第1批、第2批和第3批卵于室内自然空气湿度下保存的时间达26,11和16h后再保湿都可以正常孵化并且孵化率与对照无显著性差异,所孵化幼虫在饲养初期的成活率分别达62.0%,41.4%和43.4%,与对照无显著性差异。卵中期干燥放置36h的孵化率为66.7%,所孵化幼虫在饲养初期的成活率为50.0%,孵化率和成活率都与对照无显著性差异。卵晚期干燥放置24h的孵化率为70.0%,所孵化幼虫在饲养初期的成活率为49.0%,孵化率和成活率都与对照无显著性差异。以上结果表明,经历一定时间的干燥不会对卵的正常孵化有影响。     

Ultra-fast evaluation of protein energies directly from sequence

The structure, function, stability, and many other properties of a protein in a fixed environment are fully specified by its sequence, but in a manner that is difficult to discern. We present a general approach for rapidly mapping sequences directly to their energies on a pre-specified rigid backbone, an important sub-problem in computational protein design and in some methods for protein structure prediction. The cluster expansion (CE) method that we employ can, in principle, be extended to model any computable or measurable protein property directly as a function of sequence. Here we show how CE can be applied to the problem of computational protein design, and use it to derive excellent approximations of physical potentials. The approach provides several attractive advantages. First, following a one-time derivation of a CE expansion, the amount of time necessary to evaluate the energy of a sequence adopting a specified backbone conformation is reduced by a factor of 10(7) compared to standard full-atom methods for the same task. Second, the agreement between two full-atom methods that we tested and their CE sequence-based expressions is very high (root mean square deviation 1.1-4.7 kcal/mol, R2 = 0.7-1.0). Third, the functional form of the CE energy expression is such that individual terms of the expansion have clear physical interpretations. We derived expressions for the energies of three classic protein design targets-a coiled coil, a zinc finger, and a WW domain-as functions of sequence, and examined the most significant terms. Single-residue and residue-pair interactions are sufficient to accurately capture the energetics of the dimeric coiled coil, whereas higher-order contributions are important for the two more globular folds. For the task of designing novel zinc-finger sequences, a CE-derived energy function provides significantly better solutions than a standard design protocol, in comparable computation time. Given these advantages, CE is likely to find many uses in computational structural modeling.     

Differential regulation of cutaneous oncoprotein HPVE6 by wtp53, mutant p53R248W and ΔNp63α is HPV type dependent

UV exposure and p53 mutations are major factors in non-melanoma skin cancer, whereas a role for HPV infections has not been defined. Previous data demonstrated the wtp53-mediated degradation of cutaneous HPV20E6 by caspase-3. ΔNp63α and hot-spot mutant p53R248W conveyed a protective effect on HPV20E6 under these conditions. We demonstrate a differential regulation by wtp53 of the E6 genes of cutaneous types HPV4, HPV5, HPV7, HPV27, HPV38, HPV48, HPV60 and HPV77. Caspase- or proteasome-mediated down-regulation was HPV type dependent. Mutant p53R248W up-regulated expression of all these E6 proteins as did ΔNp63α except for HPV38E6 which was down-regulated by the latter. None of these cellular proteins affected HPV41E6 expression. Ectopic expression of both mutp53R248W and ΔNp63α in the normal NIKS keratinocyte cell line harbouring endogenous p53 and p63however led to a down-regulation of HPV20E6. We demonstrate that HPV20E6 expression in these cells is modulated by additional, yet unidentified, cellular protein(s), which are not necessarily involved in apoptosis or autophagy. We further demonstrate proliferation of HPV20E6-expressing keratinocytes. Levels of proteins involved in cell cycle control, cyclin-D1, cdk6 and p16(INK4a), phosphorylated pRB, as well as c-Jun and p-c-Jun, were all increased in these cells. HPV20E6 did not compete for the interaction between p16(INK4a) with cyclin-D1 or cdk6. Phosphorylation of pRB in the HPV20E6 expressing cells seems to be sufficient to override the cytokenetic block induced by the p16(INK4a)/pRB pathway. The present study demonstrates the diverse influence of p53 family members on individual cutaneous HPVE6 proteins. HPV20E6 expression also resulted in varying protein levels of factors involved in proliferation and differentiation.     

Regulation of cyp26a1 on Th17 cells in mouse peri‐implantation

Cytochrome P450 26A1 (cyp26a1) is expressed in the mouse uterus during peri‐implantation. The repression of this protein is closely associated with a reduction in implantation sites, suggesting a specific role for cyp26a1 in pregnancy and prompting questions concerning how a metabolic enzyme can generate this distinct outcome. To explore the effective downstream targets of cyp26a1 and confirm if its role in peri‐implantation depends on its metabolic substrate RA (retinoic acid), we characterized the changes in the peripheral blood, spleen and uterine implantation sites using the cyp26a1 gene vaccine constructed before. Flow cytometry results showed a significant increase in CD4⁺RORγt⁺ Th17 cells in both the peripheral blood and spleen in the experimental group. The expression of RORγt and IL‐17 presented the Th17 cells reduction in uterus followed by the suppression of cyp26a1 expression. For greater certainty, cyp26a1 antibody blocking model and RNA interference model were constructed to determine the precise target immune cell group. High performance liquid chromatography results showed a significant increase in uterine at‐RA followed by the immunization of cyp26a1 gene vaccine. Both the ascertain by measuring RARα protein levels in peri‐implantation uterus after gene vaccine immunization and researches using the specific agonist and antagonist against RARα suggested that RARα may be the main RA receptor for signal transduction. These results provided more evidence for the signal messenger role of RA in cyp26a1 regulation from the other side. Here, we showed that the cyp26a1‐regulated Th17 cells are dependent on at‐RA signalling, which is delivered through RARα in mouse peri‐implantation.     

Evidence for an internal entropy contribution to phosphoryl transfer: a study of domain closure, backbone flexibility, and the catalytic cycle of cAMP-dependent protein kinase.

While there is no question that ligands can induce large-scale domain movements that narrow (close) the active-site cleft of the catalytic (C) subunit of cAMP-dependent protein kinase (cAPK), the results from small-angle X-ray scattering, protein footprinting, and thermostability studies are inconsistent with regard to which ligands induce these movements. This inconsistency suggests a greater complexity of cAPK conformational dynamics than is generally recognized. As an initial step to study this issue in relation to the catalysis, a new method to measure cAPK domain closure was developed, and the state of domain closure and the local segmental flexibility at major steps of the cAPK catalytic cycle were examined with site-directed labeling and fluorescence spectroscopy. To achieve this, a C subunit mutant (F239C/C199A) was engineered that allowed for fluorescein 5-maleimide (donor) conjugation of F239C in the large lobe and tetramethylrhodamine (acceptor) conjugation of C343 in the small lobe. Domain closure was assessed as an increase in the efficiency of energy transfer between donor and acceptor. The anisotropy decay of fluoroscein 5-maleimide, conjugated to a site of cysteine substitution (K81C) in the small lobe of the C subunit was used to assess the local backbone flexibility around the B helix. The effects of substrate/pseudosubstrate (ATP and PKI(5-24)), a fragment of protein kinase inhibitor) and products (ADP and phosphorylated PKS) on domain closure and B helix flexibility were measured. The results show that domain closure is not tightly coupled to the flexibility around K81C. Moreover, although substrates/pseudosubstrate and products independently close the active-site cleft, only the substrates substantially decreased the backbone flexibility around the B helix. Because this order-to-disorder transition coincides with the phosphoryl transfer transition, the results suggest the existence of an internal entropy contribution to catalysis.     

Characterization of saponins and phenolic compounds: antioxidant activity and inhibitory effects on α-glucosidase in different varieties of colored quinoa (Chenopodium quinoa Willd)

ABSTRACT

This study investigated the contents of saponins and phenolic compounds in relation to their antioxidant activity and α-glucosidase inhibition activity of 7 colored quinoa varieties. The total saponin content was significantly different among 7 varieties and ranged from 7.51 to 12.12 mg OAE/g DW. Darker quinoa had a higher content of phenolic compounds, as well as higher flavonoids and antioxidant activity than that of light varieties. Nine individual phenolic compounds were detected in free and bound form, with gallic acid and ferulic acid representing the major compounds. The free and bound phenolic compounds (gallic acid and ferulic acid in particular) exhibited high linear correlation with their corresponding antioxidant values. In addition, the free phenolic extracts from colored quinoa exhibited higher inhibitory activity against α-glucosidase than the bound phenolic extracts. These findings imply that colored quinoa with abundant bioactive phytochemicals could be an important natural source for preparing functional food.     

小钻‘白城杨2号’小孢子发生及花粉大小变异

利用醋酸洋红染色压片技术,以温室水培小钻‘白城杨2号’(Populus×xiaozhuanica W.Y.Hsu et Liangcv.‘Baicheng-2’)为材料,对其小孢子发生过程中染色体行为及花粉大小变异进行研究。结果表明:(1)‘白城杨2号’小孢子母细胞减数分裂过程中染色体行为存在一定比例的异常现象,包括终变期单价体、中期Ⅰ染色体提前分离、后期Ⅰ和Ⅱ落后染色体和染色体桥、末期Ⅰ和Ⅱ微核、中期Ⅱ纺锤体定位异常以及胞质分裂异常等,这些异常现象的发生与‘白城杨2号’杂种起源有密切关系。(2)‘白城杨2号’小孢子母细胞减数分裂过程中核仁数目存在动态变化,末期Ⅰ和Ⅱ的子核中最多可看到8个小核仁,可能与杨属树种的多倍体起源有关,其染色体组中可能包含8对具核仁组织者区的染色体。(3)‘白城杨2号’产生空瘪花粉率为3.67%,饱满花粉直径在21.3～52.2μm之间,频率分布总体呈近似高斯分布,0.69%的花粉直径超过37μm,表明其可能产生少量未减数的2n花粉。     

Oxygen isotope temperature calibrations for modern Tridacna shells in western Pacific

Coral Reefs - The oxygen isotope ratio of carbonate in Tridacna shell (δ18Oshell) is assumed to be precipitated in isotopic equilibrium with surrounding seawater and thus reflects a...     

Plasmacytoid dendritic cells in antiviral immunity and autoimmunity

Plasmacytoid dendritic cells (pDCs) represent a unique and crucial immune cell population capable of producing large amounts of type I interferons (IFNs) in response to viral infection. The function of pDCs as the professional type I IFN-producing cells is linked to their selective expression of Toll-like receptor 7 (TLR7) and TLR9, which sense viral nucleic acids within the endosomal compartments. Type I IFNs produced by pDCs not only directly inhibit viral replication but also play an essential role in linking the innate and adaptive immune system. The aberrant activation of pDCs by self nucleic acids through TLR signaling and the ongoing production of type I IFNs do occur in some autoimmune diseases. Therefore, pDC may serve as an attractive target for therapeutic manipulations of the immune system to treat viral infectious diseases and autoimmune diseases.