Some biochemical and histochemical properties of the age pigment in the human intervertebral disc

Summary In the human intervertebral disc, specially in old age, areas with so-called pigment are found. The composition of this age pigment has been studied with histochemical and microchemical techniques. A special histochemical technique for the detection of masked lipids has been devised. The granules of the pigment areas appeared to be particularly rich in masked lipids. This is also true for the abundant globular structures occurring in different regions of the annulus fibrosus. Tyrosine, sulfhydryl-containing amino acids and keratosulphate were detected histochemically in the granule proteins. By chemical extraction three lipid fractions were isolated from the annulus fibrosus tissue of the disc. With quantitative thin-layer chromatography these fractions were found to contain a large amount of triglycerides. A hypothesis concerning the formation of such areas of age pigment is proposed.     

Applications of solids NMR to the analysis of insect sclerotized structures

This article reviews the solids NMR research conducted on insect sclerotized structures in the last 10 years and previews some of the experiments that will be conducted in the future. Solids NMR has been used as a noninvasive approach to investigate the chemical compositions of, and some covalent interactions that occur in, several types of sclerotized structures that are otherwise highly intractable to conventional chemical analyses. Sclerotization is a complex process used by insects to confer stability and mechanical versatility to their cuticular exoskeletons and certain other proteinaceous structures. Samples analyzed include cuticular exoskeletons, egg cases, egg shells, cocoons and peritrophic membranes. Cross polarization, dipolar decoupling, magic angle spinning, magnetization dephasing, and isotropic enrichment were used to obtain high resolution spectra that provide information about the types and relative concentrations of carbon atoms as well as internuclear distances and covalent bonds between carbon and nitrogen atoms. Relative amounts of protein, chitin, catechols, lipids, pigment, and oxalate were estimated. Covalent interactions between protein nitrogens and catechol carbons were detected in the stiff brown pupal cuticle of the tobacco hornworm, Manduca sexta. The results of these solids NMR studies support the hypothesis that sclerotization of insect structures occurs primarily when quinones derived from N-acylcatecholamines form cross-links and adducts with functional groups of proteins deposited in the structures. Future applications of solids NMR will utilize advanced techniques for further probing the covalent interactions of ¹³C, ¹⁵N and ¹⁷O-labeled catechols, chitin and protein in sclerotized structures.     

The distribution of chlorine e6 and its derivatives in HeLa cells studied using luminescence microscopy

The influence of the chemical structure of porphyrin pigments on their accumulation and localization in HeLa cells has been examined by the scanning fluorescence microphotometry. It has been found that the replacement of carboxyl groups of chlorine e6 for methyl and amino groups has no influence on the pigment distributions in cells. All the pigments are bound by cell membrane structures. The chemical modification of chlorine e6 structure is essential for the ability of pigment to be accumulated by cells that can be used to increase the efficiency of cancer phototherapy. The charge and hydrophobic properties of pigment molecules are of great importance for accumulating porphyrin sensitizers by cells.     

Plant cell wall characterization using scanning probe microscopy techniques

Lignocellulosic biomass is today considered a promising renewable resource for bioenergy production. A combined chemical and biological process is currently under consideration for the conversion of polysaccharides from plant cell wall materials, mainly cellulose and hemicelluloses, to simple sugars that can be fermented to biofuels. Native plant cellulose forms nanometer-scale microfibrils that are embedded in a polymeric network of hemicelluloses, pectins, and lignins; this explains, in part, the recalcitrance of biomass to deconstruction. The chemical and structural characteristics of these plant cell wall constituents remain largely unknown today. Scanning probe microscopy techniques, particularly atomic force microscopy and its application in characterizing plant cell wall structure, are reviewed here. We also further discuss future developments based on scanning probe microscopy techniques that combine linear and nonlinear optical techniques to characterize plant cell wall nanometer-scale structures, specifically apertureless near-field scanning optical microscopy and coherent anti-Stokes Raman scattering microscopy.     

桑椹红色素纯化的动态吸附条件研究

桑椹红色素是一种安伞、无毒的食用天然色素。本实验埘8种大孔吸附树脂进行筛选,然后通过单因素试验、正交试验和方差分析确定了吸附桑椹红色素的最佳操作条件。结果表明,LSA-21树脂对桑椹红色素的吸附和解吸性能较好;确定的最佳吸附条件为：料液浓度(以吸光度计)为0．425Abs,上柱速度3．5BV／h,料液pH1．57。     

Engineering soft nanostructured functional materials via orthogonal chemistry

Nanostructured amphiphilic block copolymers, graft copolymers, polymeric thermally responsive molecular brushes and polymer stars are only few examples of macromolecular architectures accessible either via controlled/living radical polymerization (CLRP) techniques or the combination of CLRP mechanisms with efficient post-polymerization routes including click chemistry. Precise control over the composition, molecular weight and functionalities is a prerequisite for soft polymeric materials to self-organize into ordered morphologies. This contribution describes novel orthogonal chemical routes for the synthesis of macromolecular architectures and self-assembly of functional soft polymeric materials. Emerging potential applications of well-defined block and graft copolymers are outlined as well.     

高产红曲黄色素菌株的选育

利用紫外、硫酸二乙酯、氯化锂和亚硝基胍复合诱变的方法,选育到一株高产黄色素的红曲霉突变株MYM2.经过稳定性实验证明,诱变得到的菌株稳定性较好,液态发酵试验黄色素色价达到100U/mL以上,黄色素色调达到3.5左右.此黄色素在300nm～600nm波长之间只有一个在410 nm附近的最大吸收峰,在pH 3～8之间稳定性较好.当pH小于3时,红曲黄色素不稳定,黄色素溶液变混浊,放置后有沉淀产生.     

Inhibition of Microbial Growth by Fatty Amine Catalysts from Polyurethane Foam Test Tube Plugs

When polyurethane foam test tube plugs are autoclaved, they release volatile fatty amines that inhibit the growth of some microorganisms. The chemical structures of these amines were determined by the use of a gas chromatographmass spectrometer. They are catalysts used to produce the foam. The problem of contaminating growth media with toxic substances released from polymeric materials is discussed.     

A Standardized Test for the Identification and Characterization of Melanins Using Electron Paramagnetic Resonance (EPR) Spectroscopy

Melanins are complex, incompletely understood polymeric pigments that historically have been difficult to investigate with common chemical, histochemical, and physicochemical techniques. Because these pigments uniquely contain a stable population of organic free radicals, electron paramagnetic resonance (EPR) spectroscopy is a particularly effective method for studying them, and a set of qualitative EPR criteria has been established for their identification. However, a number of practical problems have arisen in applying these criteria to identify and characterize unknown pigments in relatively scarce pathological specimens, indicating that a standardized approach is needed. As reported here, a standardized EPR test for melanin based on the EPR criteria has been developed, guided by the requirements that it be sensitive, accurate, simple, and easy to interpret. It has been evaluated using the well-characterized synthetic melanin prepared by alkaline autooxidation of 5,6-dihydroxyphenylalanine (Dopa) and initially applied to the identification and characterization of an unknown pigment purified from an unusual malignant lung tumor.     

Organic/inorganic complex pigments: ancient colors Maya Blue

Maya Blue is an ancient blue pigment composed of palygorskite clay and indigo. It was used by the ancient Maya and provides a dramatic background for some of the most impressive murals throughout Mesoamerica. Despite exposure to acids, alkalis, and chemical solvents, the color of the Maya Blue pigment remains unaltered. The chemical interaction between palygorskite and indigo form an organic/inorganic complex with the carbonyl oxygen of the indigo bound to a surface Al(3+) in the Si-O lattice. In addition indigo will undergo an oxidation to dehydroindigo during preparation. The dehydro-indigo molecule forms a similar but stronger complex with the Al(3+). Thus, Maya Blue varies in color due to the mixed indigo/dehydroindigo complex. The above conclusions are the result of application of multiple techniques (X-ray diffraction, differential thermal analysis/thermal gravimetric analysis, high resolution transmission electron microscopy, scanning electron microscopy, infrared and Raman spectroscopy) to the characterization of the organic/inorganic complex. A picture of the bonding of the organic molecule to the palygorskite surface forming a surface complex is developed and supported by the results of density functional theory calculations. We also report that other organic molecules such as thioindigo form similar organic/inorganic complexes thus, opening an entirely new class of complex materials for future applications.     

Correlating transfection barriers and biophysical properties of cationic polymethacrylates

Transfection efficiencies of several polymeric gene carriers were compared and correlated quantitatively to the amounts of cellular accumulation of plasmid DNA and to the expression of mRNA by quantitative real-time polymerase chain reaction (real-time PCR). Three polycations polymers with similar chemical structure were used in this study: poly(dimethylamino)ethyl methacrylate (PDMA) homopolymer, PEO-b-PDMA copolymer, and PEO-b-poly(diethylamino)ethyl methacrylate (PEO-b-PDEA) copolymer. Despite their similar chemical structures, the transfection efficiencies were significantly different. PEO-b-PDEA copolymer was significantly less efficient as gene carrier as compared to both PDMA and PEO-b-PDMA. Correlations between cytotoxicity, cellular uptake of plasmid DNA, expression levels of transgene and protein, and the physical properties of the polymers were observed. With the PEO-b-PDEA studies, cytotoxicity was due primarily to the excess of polymers that did not participate in the DNA binding. In addition, the inability of the polymer/DNA polyplexes to interact with cell effectively was identified as a critical barrier for high efficiency of transfection. This study demonstrated that the use of quantitative real-time PCR in combination with physical characterization techniques could provide useful insights into the transfection barrier at different cellular levels.     

Current challenges in understanding melanogenesis: bridging chemistry,biological control,morphology, and function

Melanin is a natural pigment produced within organelles, melanosomes, located in melanocytes. Biological functions of melanosomes are often attributed to the unique chemical properties of the melanins they contain; however, the molecular structure of melanins, the mechanism by which the pigment is produced, and how the pigment is organized within the melanosome remains to be fully understood. In this review, we examine the current understanding of the initial chemical steps in the melanogenesis. Most natural melanins are mixtures of eumelanin and pheomelanin, and so after presenting the current understanding of the individual pigments, we focus on the mixed melanin systems, with a critical eye towards understanding how studies on individual melanin do and do not provide insight in the molecular aspects of their structures. We conclude the review with a discussion of important issues that must be addressed in future research efforts to more fully understand the relationship between molecular and functional properties of this important class of natural pigments.     

富含多糖草莓果实总RNA提取方法的改进

以草莓果实为模式实验材料,将Chomczynski提出的常规RNA提取方法与Kenneth等提出的改进方法相结合,并做了进一步改进,建立了一种简单实用的从富舍多糖的植物材料中提取总RNA的方法。先利用冷的丙酮去除色素类物质,再利用乙二醇丁醚去除多糖,从而有效克服了从富含色素和多糖娄物质的植物材料中提取RNA的困难;获取的RNA样品在纯度和浓度上都可以满足PCR及Northern杂交等分子生物学实验的要求。     

一株产槲皮素类色素的银杏内生真菌的研究

从银杏树根中分离出70余株内生真菌.将它们置于马铃薯葡萄糖(PD)液体培养基中培养,发现其中一株(Gh01)能产生橙黄色色素.经过化学反应及HPLC检测证明该橙黄色色素为槲皮素类糖苷.这是关于内生真菌产槲皮素类糖苷的首次报道.本文深入探讨了碳源,氮源,金属离子,初始PH及培养温度对色素产量的影响.PD液体培养基的最适培养温度和初始PH分别为28℃和7.0.正交设计结果显示:最适碳源和氮源分别为20g/L葡萄糖和5g/L蛋白胨.增加1g/L的氯化锌可提高色素产量.在最适培养条件下连续培养120h色素的产量可达到27.515g/L.     

Immunofluorescence evidence for cytoskeletal rearrangement accompanying pigment redistribution in goldfish xanthophores

Immunofluorescence and phase-contrast microscopic studies of goldfish xanthophores with aggregated or dispersed pigment show two unusual features. First, immunofluorescence studies with anti-actin show punctate structures instead of filaments. These punctate structures are unique for the xanthophores and are absent from both goldfish dermal non-pigment cells and a dedifferentiated cell line (GEM-81) derived from a goldfish xanthophore tumor. Comparison of immunofluorescence and phase-contrast microscopic images with electron microscopic images of thin sections and of Triton-insoluble cytoskeletons show that these punctate structures represent pterinosomes with radiating F-actin. The high local concentration of actin around the pterinosomes results in strong localized fluorescence such that, when the images have proper brightness for these structures, individual actin filaments elsewhere in the cell are too weak in their fluorescence to be visible in the micrographs. Second, whereas immunofluorescence images with anti-tubulin show typical patterns in xanthophores with either aggregated or dispersed pigment, namely, filaments radiating out from the microtubule organizing center, immunofluorescence images with anti-actin or with anti-intermediate filament proteins show different patterns in xanthophores with aggregated versus dispersed pigment. In cells with dispersed pigment, the punctate structures seen with anti-actin are relatively evenly distributed in the cytoplasm, and intermediate filaments appear usually as a dense perinuclear band and long filaments elsewhere in the cytoplasm. In cells with aggregated pigment, both intermediate filaments and pterinosomes with associated actin are largely excluded from the space occupied by the pigment aggregate, and the band of intermediate filaments surrounds not only the nucleus but also the pigment aggregate. The patterns of distribution of the different cytoskeleton components, together with previous results from this laboratory, indicate that formation of the pigment aggregate depends at least in part on the interaction between pigment organelles and microtubules. The possibility that intermediate filaments may play a role in the formation/stabilization of the pigment aggregate is discussed.     

Spectroscopic studies of methylglyoxal in water and dimethylsulfoxide

Methylglyoxal is a highly reactive dicarbonyl compound, which reacts in vivo with biological macromolecules and thereby affects their structure and function. These changes are associated with complications during aging, diabetes and Alzheimer's disease as well as with growth inhibition in different tumors. Many enzymes are involved in the metabolism of methylglyoxal, but its true physiological role in metabolism and chemical properties are still obscure. In this study it was shown that methylglyoxal, during the freeze-drying of aqueous solutions, polymerizes into small polymeric structures which are stable in organic media such as dimethylsulfoxide. When re-exposed to water, the polymers are immediately transformed into the monomeric mono- and dihydrate forms of methylglyoxal. By NMR and UV spectroscopy, it was shown that solvent, temperature, and the amount of available water strongly influence the equilibrium of the different forms of methylglyoxal and thereby change its reactivity. 1H and 13C NMR spectroscopy were used to determine the structures of the different monomeric and oligomeric structures of methylglyoxal.     

The major pigment composition of different strains of Oscillatoria (Cyanophyta) recorded in vivo by a modified Shibata technique

The pigmentation of five strains of Oscillatoria bornetii and four strains of Oscillatoria agardhii/rubescens were surveyed in vivo by spectrophotometry. The O. bornetii strains are very homogeneous with regard to qualitative pigment composition, but strain differences with regard to relative pigment content are remarkable. The O. agardhii/rubescens complex is variable, especially with regard to phycoerythrin content. In vivo pigment techniques may be promising as an additional, simple tool in blue–green algal taxonomy.     

Ultrasound-assisted adsorption of anionic nanoscale pigment on cationised cotton fabrics

Application of pigments in textile coloring has many advantages such as less water and energy consumption, less effluent load and higher efficiency, so the pigments are perfect alternatives to dyes for eco-friendly coloring. In this work, a stable anionic nanoscale pigment suspension was prepared using a polymeric dispersant to color the cationised cotton with the exhaust method. Meanwhile, ultrasound was carried out during the adsorption to evaluate the ultrasonic influences on the uptake of pigment, adsorption efficiency and final product quality. The uptake of pigment is found to be higher with ultrasonic method than that with conventional technique because of the good dispersing capacity of ultrasound to pigment particles. Besides, it is found that nanoscale pigment has higher adsorption rate when using ultrasonic method because the ultrasound promotes the diffusion of pigment through the fiber-liquid boundary layer. Lastly, the color difference (ΔE) reveals the nanoscale pigment can be deposited on cotton surface more uniformly under ultrasonic condition, improving the product quality obviously.     

DETECTION OF NEW PIGMENTS FROM EMILIANIA HUXLEYI (PRYMNESIOPHYCEAE) BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY, LIQUID CHROMATOGRAPHY–MASS SPECTROMETRY, VISIBLE SPECTROSCOPY, AND FAST ATOM BOMBARDMENT MASS SPECTROMETRY

Pigment extracts from Emiliania huxleyi (Lohm.) Hay et Mohler (strains CCMP 370, CCMP 373, and NIOZ CH 24) were analyzed using high-performance liquid chromatography (HPLC) on highly efficient monomeric and polymeric octadecylsilica columns using either ammonium acetate or pyridine containing mobile phases. Both systems showed chromatographic profiles with peaks corresponding to pigments of uncertain structure: those of the polar and nonpolar chlorophyll c forms and one peak whose on-line diode array spectrum resembled that of the fucoxanthin acyloxy derivatives. Liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry gave a molecular mass of 786 units for the unknown carotenoid. The pigments corresponding to each of these fractions were isolated and their visible spectra recorded in various solvents. Samples of the isolated pigments were subjected to analysis by fast atom bombardment mass spectrometry that confirmed a molecular mass of 786 for the unknown carotenoid and gave a mass of 654 units for the polar chlorophyll c ₃, compatible with the monovinylic structure previously suggested. The detection of these new pigments calls for attention on the use of correct methodologies when HPLC pigment signatures are used to study the taxonomic composition of natural phytoplankton populations.     

Analysis of the subunit structure of protochlorophyllide holochrome by sodium dodecyl sulfate-polyacrylamide gel electrophoresis

The subunit structures of protochlorophyllide holochrome (PCH) and chlorophyllide holochrome (CH) were studied by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. PCH from leaves of dark-grown (Phaseolus vulgaris var. red kidney) is a polymeric pigment-protein complex of approximately 600,000 daltons. It is composed of 12 to 14 polypeptides of 45,000 daltons, when examined prior to and immediately following photoconversion. The protochlorophyllide or chlorophyllide pigment molecules are associated with these polypeptides. Subsequent to photoconversion, the absorption maximum of newly formed chlorophyllide shifts from 678 nm to 674 nm upon standing in darkness. Following the 678 to 674 spectral shift, the chlorophyllide is associated with a polypeptide with a molecular weight of 16,000 daltons. In addition, sucrose gradient centrifugation of PCH and CH under nondenaturing conditions indicates that during the course of the dark spectroscopic shift, the 600,000 dalton CH undergoes dissociation into a small chlorophyllide protein. The dissociation of CH, the change in the molecular weight of the chlorophyllide polypeptide from 45,000 to 16,000 daltons, as well as the dark spectroscopic shift are temperature-dependent and blocked below 0 C. It was also found that each holochrome molecule of 600,000 daltons contains at least four protochlorophyllide pigment molecules.