钙荧光探剂的研究及其在生命科学中的应用

钙荧光探剂测量活细胞胞浆游离Ｃａ２＋浓度的方法在钙研究中已成为一种越来越重要的技术。特别是由于新的一代荧光探剂的合成和激光共聚焦显微镜的发展,使其应用更加广泛。由于国内使用这种技术的实验室逐渐增多,本文将系统介绍钙荧光探剂的发展、测量原理和方法、新的常用钙荧光探剂的比较及其在生命科学中的应用。     

Descriptions of Two New Species of Chronogaster Cobb, 1913 from India

Two new species of Chronogaster in India were described and illustrated, based on light and scanning electron microscopy. Chronogaster neotypica n. sp. collected from a sewage slurry was characterized by a medium-sized body, a ventral tail mucro without additional spines, absence of longitudinal incisures in lateral fields, and by the presence of crystalloids in the body. Diagnostic for C. spinicauda n. sp. collected from soil around roots of mango were a medium-sized body, a tail mucro with 10 spines, and absence of lateral lines and crystalloids. Males were not found.     

alpha-cardiac actin (ACTC) binds to the band 3 (AE1) cardiac isoform

The band 3 protein is the major integral protein present in the erythrocyte membrane. Two tissue-specific isoforms are also expressed in kidney alpha intercalated cells and in cardiomyocytes. It has been suggested that the cardiac isoform predominantly mediates the anion exchange in cardiomyocytes, but the role of the cytoplasmic domain of the band 3 (CDB3) protein in the cardiac tissue is unknown. In order to characterize novel associations of the CDB3 in the cardiac tissue, we performed the two-hybrid assay, using a bait comprising the region from leu 258 to leu 311 of the erythrocyte band 3, which must also be present in the cardiac isoform. The assay revealed two clones containing the C-terminal region of the alpha-cardiac actin. Immunoprecipitation of whole rat heart using an anti-actin antibody, immunoblotted with anti-human band 3, showed that actin binds to band 3 which was confirmed in the reverse assay. The confocal microscopy showed band 3 in the intercalated discs. Thus, besides the in vivo physical interaction in the Saccharomyces cerevisiae cell, we demonstrated using immunopreciptation that there is a physical association of band 3 with alpha-cardiac actin in cardiomyocyte, and we suggest that the binding occur "in situ," in the intercalated disc, a site of cell-cell contact and attachment of the sarcomere to the plasma membrane.     

Bilayer structural destabilization by low amounts of chlorophyll a

The present study shows that small admixtures of one chlorophyll a (Chla) molecule per several hundred lipid molecules have strong destabilizing effect on lipid bilayers. This effect is clearly displayed in the properties of the L_α-H_II transformations and results from a Chla preference for the H_II relative to the L_α phase. Chla disfavors the lamellar liquid crystalline phase L_α and induces its replacement with inverted hexagonal phase H_II, as is consistently demonstrated by DSC and X-ray diffraction measurements on phosphatidylethanolamine (PE) dispersions. Chla lowers the L_α-H_II transition temperature (42 °C) of the fully hydrated dipalmitoleoyl PE (DPoPE) by ∼ 8 °C and ∼ 17 °C at Chla/DPoPE molar ratios of 1:500 and 1:100, respectively. Similar Chla effect was recorded also for dielaidoyl PE dispersions. The lowering of the transition temperature and the accompanying significant loss of transition cooperativity reflect the Chla repartitioning and preference for the H_II phase. The reduction of the H_II phase lattice constant in the presence of Chla is an indication that Chla favors H_II phase formation by decreasing the radius of spontaneous monolayer curvature, and not by filling up the interstitial spaces between the H_II phase cylinders. The observed Chla preference for H_II phase and the substantial bilayer destabilization in the vicinity of a bilayer-to-nonbilayer phase transformation caused by low Chla concentrations can be of interest as a potential regulatory or membrane-damaging factor.     

Developing novel hCT derived cell-penetrating peptides with improved metabolic stability

Many promising therapeutics are currently awaiting their clinical application. Due to their low capability of cell membrane crossing, these compounds do not reach their site of action. One way to overcome this problem might be the fusion of these agents to cell-penetrating peptides (CPP), which are able to shuttle various cargoes across cellular membranes. One disadvantage in using CPP in drug delivery is their low metabolic stability. The aim of our work was to increase the proteolytic resistance of the CPP hCT(9-32), a truncated C-terminal fragment of human calcitonin. Thus, we synthesised six modified N-terminally carboxyfluorescein labelled hCT(9-32) derivatives by replacing positions 12 and/or 16 of hCT(9-32) with either N-methylphenylalanine or d-phenylalanine, respectively. By using confocal laser scanning microscopy we showed that the modifications did neither affect the peptide internalisation efficiency in HeLa nor HEK 293T cells. The metabolic stability of the peptides was investigated in human blood plasma and HEK 293T cell culture supernatant. To analyse the degradation patterns, we used RP-HPLC and MALDI-TOF mass spectrometry. However, we found for all of the new derivatives high metabolic stabilities. In blood plasma, the half-lives for five of the six peptides increased compared to unmodified hCT(9-32). The degradation patterns showed a distinct stabilisation in the N-terminal part of the modified peptides, in the C-terminal part, we found some cleavage to a minor extent. Furthermore, we studied the conformation of the peptides by CD spectroscopy and demonstrated that they possess no cell toxicity. Since our metabolically more stable compounds are still able to pass the cell membrane they provide powerful tools as drug delivery vectors.     

Surface Chirality of Gly‐Pro Dipeptide Adsorbed on a Cu(110) Surface

The adsorption of chiral Gly‐Pro dipeptide on Cu(110) has been characterized by combining in situ polarization modulation infrared reflection absorption spectroscopy (PM‐RAIRS) and X‐ray photoelectron spectroscopy (XPS). The chemical state of the dipeptide, and its anchoring points and adsorption geometry, were determined at various coverage values. Gly‐Pro molecules are present on Cu(110) in their anionic form (NH₂/COO⁻) and adsorb under a 3‐point binding via both oxygen atoms of the carboxylate group and via the nitrogen atom of the amine group. Low‐energy electron diffraction (LEED) and scanning tunneling microscopy (STM) have shown the presence of an extended 2D chiral array, sustained via intermolecular H‐bonds interactions. Furthermore, due to the particular shape of the molecule, only one homochiral domain is formed, creating thus a truly chiral surface. Chirality 27:411–416, 2015. © 2015 Wiley Periodicals, Inc.     

车前草中熊果酸的含量测定

本实验以95％的乙醇为溶剂,采用超声波提取法对车前草进行了提取,并用双波长薄层扫描法测定其含量。结果表明,车前草中熊果酸的平均含量为0．302％。该方法简便、准确、经济、安全、数据可靠。     

Mechanical robustness of the calcareous tubeworm Hydroides elegans: warming mitigates the adverse effects of ocean acidification

Development of antifouling strategies requires knowledge of how fouling organisms would respond to climate change associated environmental stressors. Here, a calcareous tube built by the tubeworm, Hydroides elegans, was used as an example to evaluate the individual and interactive effects of ocean acidification (OA), warming and reduced salinity on the mechanical properties of a tube. Tubeworms produce a mechanically weaker tube with less resistance to simulated predator attack under OA (pH 7.8). Warming (29°C) increased tube volume, tube mineral density and the tube’s resistance to a simulated predatory attack. A weakening effect by OA did not make the removal of tubeworms easier except for the earliest stage, in which warming had the least effect. Reduced salinity (27 psu) did not affect tubes. This study showed that both mechanical analysis and computational modeling can be integrated with biofouling research to provide insights into how fouling communities might develop in future ocean conditions.     

Outstanding Low Temperature Thermoelectric Power Factor from Completely Organic Thin Films Enabled by Multidimensional Conjugated Nanomaterials

In an effort to create a paintable/printable thermoelectric material, comprised exclusively of organic components, polyaniline (PANi), graphene, and double‐walled nanotube (DWNT) are alternately deposited from aqueous solutions using the layer‐by‐layer assembly technique. Graphene and DWNT are stabilized with an intrinsically conductive polymer, poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). An 80 quadlayer thin film (≈1 μm thick), comprised of a PANi/graphene‐PEDOT:PSS/PANi/DWNT‐PEDOT:PSS repeating sequence, exhibits unprecedented electrical conductivity (σ ≈ 1.9 × 10⁵ S m^?1) and Seebeck coefficient (S ≈ 120 μV K^?1) for a completely organic material. These two values yield a thermoelectric power factor (PF = S ² σ ^?1) of 2710 μW m^?1 K^?2, which is the highest value ever reported for a completely organic material and among the highest for any material measured at room temperature. These outstanding properties are attributed to the highly ordered structure in the multilayer assembly. This water‐based thermoelectric nanocomposite is competitive with the best inorganic semiconductors (e.g., bismuth telluride) at room temperature and can be applied as a coating to any flexible surface (e.g., fibers in clothing). For the first time, there is a real opportunity to harness waste heat from unconventional sources, such as body heat, to power devices in an environmentally‐friendly way.     

血红素加氧酶介导GA对小麦糊粉层中α-淀粉酶的诱导表达

单独以赤霉素（GA）处理或与HO．1诱导物高铁血红素（Ht）和CO水溶液组合处理均导致小麦糊粉层中血红素加氧酶（H0）活性的提高,同时仪-淀粉酶基因表达和α-淀粉酶活性也明显受诱导;用HO-1专一性抑制剂锌原卟啉（ZnPPIX）预处理6h后,上述效应部分受阻断。这暗示HO可能参与GA诱导的α-淀粉酶基因表达。