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PubMed1991

Plasmodium falciparum polypeptides interacting with human red cell membranes show high affinity binding to Band-3.

P. falciparum proteins were labelled with [35S]methionine and harvested at various asexual stages. A number of parasite proteins bound to uninfected red cell membranes (ghosts). Some of these proteins differentially partitioned when ghosts were extracted with detergent. Several of these proteins bound very strongly to immobilised whole ghost proteins or immobilised purified Band-3 in a stage-specific manner, but not to a sham-coupled matrix or to immobilised Band-3 extract from cells rendered refractory to invasion. Such specific binding of parasite proteins to immobilised Band-3 supports recent conjecture as to its role as a host receptor during parasite invasion. However, our results demonstrate the complex and multifactorial nature of the interaction between parasite and host proteins during invasion and development.

Animals↗
PubMed1977

Ultrastructure and histochemistry of the supportive structures associated with the radula of the slug, Limax maximus.

The odontophore and connective tissue-filled portion of the radular sac (called the "collostyle") of the slug, Limax maximus, were examined by light and electron microscopy. While both of these structures grossly resemble vertebrate cartilage, neither is composed of a type of tissue with the microscopic appearance and histochemical properties of cartilage. The roughly U-shaped odontophore possesses a thin capsule composed of connective tissue. The parenchyma of the odontophore consists of modified muscle cells which are organized into irregular groups by incomplete trabeculae composed of conventional muscle cells. The odontophoral cells are variable in size; they contain glycogen-filled "cores" as well as bundles of peripherally located filaments resembling myofilaments; and they are innervated like muscle cells. The nuclei of the cells are located eccentrically in the glycogen-filled portions of the cells and typically contain prominent nucleoli. The nuclei are surrounded by multiple small Golgi complexes and pleomorphic dense bodies resembling lysosomes. The extracellular matrix of the odontophore is very sparse and contains glycogen and fibrillar material but no histochemically demonstrable acidic mucosubstances. The collostyle consists of a gelatinous type of tissue somewhat like vertebrate mucoid connective tissue. The abundant extracellular matrix contains cross-banded filaments, a flocculent material disposed in wavy indefinite strands, and small electron-dense particles. The matrix contains histochemically demonstrable neutral and weakly acidic mucosubstances. The cell population of the collostyle includes solitary muscle cells and fibrocytes containing large quantities of glycogen.

Animals↗
PubMed1982

Extracellular matrix synthesis by skeletal muscle in culture. Proteins and effect of enzyme degradation.

Extracellular matrix proteins produced by a mouse skeletal muscle cell line, G8-1, were isolated and characterized. Cultures were incubated with [35S]methionine or [3H]glycine and [3H]proline, and the labeled, substrate-attached proteins were obtained after cellular proteins were extracted by deoxycholate in neutral salt. The labeled matrix was analyzed by gel electrophoresis and fluorography before and after enzymatic digestion. Of the nine major bands present in the matrix, four were identified. Fibronectin and collagen were detected on the bases of their relative mobilities, differential labeling with 3H-versus 35S-labeled amino acids and their solubilization by protease free collagenase. High molecular weight material which was present in the matrix was also sensitive to collagenase and probably included cross-linked collagen and laminin. Proteins co-migrating with actin and myosin were also present in the extracellular matrix. These results are novel in that they demonstrate that the skeletal muscle phenotype, not contaminated with fibroblastic elements, is able to synthesize basal lamina-type macromolecules and incorporate them into an insoluble, extracellular matrix. Since this cell line is able to form functional synaptic contacts with neuronal cells, the influence of nerve on basal lamina production by muscle in vitro is possible.

Animals↗
PubMed1994

Type XII and XIV collagens mediate interactions between banded collagen fibers in vitro and may modulate extracellular matrix deformability.

Type XII and XIV collagens are very large molecules containing three extended globular domains derived from the amino terminus of each alpha chain and an interrupted triple helix. Both collagens are genetically and immunologically unique and have distinct distributions in many tissues. These collagens localize near the surface of banded collagen fibrils. The function of the molecules is unknown. We have prepared a mixture of native type XII and XIV collagens that is free of contaminating proteins by electrophoretic criteria. In addition, we have purified the collagenase-resistant globular domains of type XII or XIV collagens (XII-NC-3 or XIV-NC-3). In this study, we have investigated the effect of intact type XII and XIV and XII-NC-3 or XIV-NC-3 on the interactions between fibroblasts and type I collagen fibrils. We find that both type XII and XIV collagens promote collagen gel contraction mediated by fibroblasts, even in the absence of serum. The activity is present in the NC-3 domains. The effect is dose-dependent and is inhibited by denaturation. The effect of type XII NC-3 is inhibited by the addition of anti-XII antiserum. To elucidate the mechanism underlying this phenomenon, we examined the effect of XII-NC-3 or XIV-NC-3 on deformability of collagen gels by centrifugal force. XII-NC-3 or XIV-NC-3 markedly promotes gel compression after centrifugation. The effect is also inhibited by denaturation, and the activity of type XII-NC3 is inhibited by the addition of anti-XII antiserum. The results indicate that the effect of XII-NC-3 or XIV-NC-3 on collagen gel contraction by fibroblasts is not due to activation of cellular events but rather results from the increase in mobility of hydrated collagen fibrils within the gel. These studies suggest that collagen types XII and XIV may modulate the biomechanical properties of tissues.

Animals↗
PubMed2005

Electronic spectroscopy of C2 in solid rare gas matrixes.

Electronic spectroscopy of the C(2) molecule is investigated in Ar, Kr, and Xe matrixes in the 150-500 nm range. In the Ar matrix, the D ((1)Sigma(u)(+)) <-- ((1)Sigma(g)(+)) Mulliken band near 240 nm is the sole absorption in the UV range, whereas in the Kr matrix additional bands in the 188-209 nm range are assigned to the Kr(n)()(+)C(2)(-) <-- Kr(n)()C(2) charge-transfer absorptions. Because of the formation of a bound C(2)Xe species, the spectral observations in the Xe matrix differ dramatically from the lighter rare gases: the Mulliken band is absent and new bands appear near 300 and 423 nm. The latter is assigned to the forbidden B'((1)Sigma(g)(+)) <-- X ((1)Sigma(g)(+)) transition, but the origin of the former remains unclear. The spectral assignments are aided by electronic structure calculations at the MCSCF, CCSD(T), and BCCD(T) levels of theory and correlation consistent basis sets. A significant presence of multireference character of the C(2)Xe system was noted and a linear ground-state structure is predicted. The computational results contradict previous density functional studies on the same system.

Journal Article↗
PubMed2001

Localization of strain in metal matrix composites studied by a scanning electron microscope-based grating method.

The deformation characteristics of the metal matrix composites Ag/Ni and Al/Al2O3 are studied at microstructural level by a scanning electron microscopebased grating method and finite element (FE) simulation. The measured strain was found to localize in narrow bands in the ductile matrix of both composites. In the case of the Al/Al2O3 composite, the bands are preferentially initiated in Al regions adjacent to the interface of large Al2O3 particles, leading to local strain maxima. The band positions found in the Ag/Ni composite are also affected by the less deformable Ni phase, but strain localization first occurs by sliding of single Ag grains sometimes located away from the Ni phase. Using a FE model of real phase geometry and measured border displacements as boundary conditions, the simulation agrees reasonably with the experiment. The differences in the case of the Al/Al2O3 composite are due to particle cracks and voids at the particle/matrix interface. This effect was found in the experiment but not considered in modelling. For the Ag/Ni composite the band positions agree fairly well. However, the level and gradient of strain is clearly different as the crystallographic orientation of the Ag grains was not accounted for in modelling.

Journal Article↗
PubMed1981

Structure of the auditory system of the weta Hemideina crassidens (Blanchard, 1851). (Orthoptera, Ensifera, Gryllacridoidea, Stenopelmatidae). 2. Ultrastructure of the auditory sensilla.

This study of the ultrastructure of the auditory sensilla of the New Zealand weta, Hemideina crassidens, is the first such study on a member of the orthopteran Superfamily Gryllacridoidea. Ultrastructure of the auditory sensilla is similar in all of the tibial mechanosensory organs, here called subgenual organ, intermediate organ and crista acoustica by analogy with comparable structures in Tettigoniidae. Distal to each sensory soma is a dendrite containing multiple ciliary rootlets that fuse into a single ciliary root. This splits into nine root processes that pass around the outside of the proximal basal body and then rejoin at the level of the distal basal body, distal to which the dendrite has a modified ciliary structure with a circlet of nine peripheral paired tubes and rods as it passes through the proximal extracellular space. It is then enclosed by a zone of scolopale cell cytoplasm before expanding into a dilatation within the distal extracellular space. In some sensilla this space is partially occluded by electron dense material which is part of the scolopale cell. Distal to the dilatation the cilium shrinks and ends surrounded by the scolopale cap. Accessory cells consist of glia enwrapping the sensory neuron in the region of its soma, the scolopale cell surrouinding the ciliary portion of the dendrite, and the attachment cell surrounding the scolopale cell and scolopale cap and connected to them by desmosomes. The attachment cells are filled with microtubules in differing densities and orientations. Lamellae are present in the acellular matrix surrounding the attachment cells. Banded fibres, presumably of collagen, are also present in the matrix.

Animals↗
PubMed2006

HXeCCH in Ar and Kr matrices.

HXeCCH molecule is prepared in Ar and Kr matrices and characterized by IR absorption spectroscopy. The experiments show that HXeCCH can be made in another host than the polarizable Xe environment. The H-Xe stretching absorption of HXeCCH in Ar and Kr is blueshifted from the value measured in solid Xe. The maximum blueshifts are +44.9 and +32.3 cm(-1) in Ar and Kr, respectively, indicating stabilization of the H-Xe bond. HXeCCH has a doublet H-Xe stretching absorption measured in Xe, Kr, and Ar matrices with a splitting of 5.7, 13, and 14 cm(-1), respectively. Ab initio calculations for the 1:1 HXeCCHcdots, three dots, centeredNg complexes (Ng = Ar, Kr, or Xe) are used to analyze the interaction of the hosts with the embedded molecule. These calculations support the matrix-site model where the band splitting observed experimentally is caused by specific interactions of the HXeCCH molecule with noble-gas atoms in certain local morphologies. However, the 1:1 complexation is unable to explain the observed blueshifts of the H-Xe stretching band in Ar and Kr matrices compared to a Xe matrix. More sophisticated computational approach is needed to account in detail the effects of solid environment.

Journal Article↗
PubMed2001

[Raman spectra of nacre from shells of main pearl-culturing mollusk in China].

The Raman spectra of nacre and cultured pearl from main pearl-culturing mollusks in China have been studied systematically in this paper. It shows that: 1) the Raman bands caused by organic matrix have not been observed in nacre from shell of pinctada maxima; 2) in nacre from shell of pinctada martensii and hyriopsis cumingii, besides the bands caused by aragonite mineral, two bands resulted from all-trans carotenoid are obviously observed, and the number of C=C double bonds in molecular of this carotenoid is predicted to be 10 based on the position of its Raman bands; 3) a number of complicated bands are observed in nacre from shell of peteria penguin, and we predicted that this bands perhaps are caused by metalloporphyrin compounds; 4) the relative concentrations of carotenoid and metalloporphyrin in nacre are closely associated with the color of nacre. The Raman spectra research on organic matrix in nacre and cultured pearl provides insight into the applications of them in cosmetics and food, as well as in application of pearl bleaching.

Animals↗
PubMed1997

Composite Membrane of Niobium(V) Oxide and Cellulose Acetate: Preparation and Characterization

Composite membranes of niobium(V) oxide and cellulose acetate (Cel/Nb2O5) were prepared with the following Nb2O5 loadings (in wt%): 1.1, 6.1, 9.8, 15.6, and 20.9. The thermal stability of the membranes slightly decreased in relation to the pure membrane on incorporation of the metal oxide into the matrix. Scanning electron microscopy and niobium mapping with an X-ray EDS microprobe showed that the metal oxide particles are homogeneously dispersed in the matrix. The electronic absorption bands indicated that the oxide particle size varies from that of the monomer to those of oligomer species on increased Nb2O5 loading in the matrix. The dispersed oxide possesses mainly Lewis acid character, a clear indication that on increasing the oxide loading in the matrix, the coordination number of the metal is not saturated by formation of the Nb-O-Nb bond. Copyright 1997Academic Press

Journal Article↗
PubMed1987

Bone formation in organ cultures of bone marrow.

Bone formation in organ cultures of intact marrow fragments from mouse is described. Marrow explants were cultured on the top surface of a millipore filter at a gas-liquid interface. Observations with both light- and electron microscopes demonstrated the formation of a well-organised trabecular matrix lined with osteoblast-like cells. The tissue and cells were positive for alkaline-phosphatase activity. Large amounts of thick, well-banded collagen fibrils and matrix vesicles typical of those found in bone were present. The tissue became mineralised in the presence of 10 mM Na-beta-glycerophosphate; in its absence a similar trabecular matrix developed but mineralisation did not take place.

Animals↗
PubMed1991

Modular organization of projection neurons in the matrix compartment of the primate striatum.

It is well known that the striatum has a chemical architecture dividing it into striosomes and matrix, and that these compartments have different input-output connections. However, striatal afferent-fiber systems also form vividly patchy terminal fields in the matrix, and studies in the past year have uncovered instances of nonstriosomal clustering of striatal output neurons. In the experiments reported here, we systematically investigated this output-neuron clustering in the primate, using the striatopallidal system as a model. Our goals were to determine whether the modular organization is a general characteristic of projection neurons in the striatal matrix, whether the modularity occurs independent of striosomal boundaries, and whether the output modules are systematically organized. We studied the distribution of striatopallidal projection neurons in 9 adult squirrel monkeys by centering deposits of the retrograde tracer HRP-WGA in either the external segment or the internal segment of the globus pallidus. Following injections of each type, many retrogradely labeled neurons appeared in the striatal matrix in clusters and bands having cross-sectional diameters of 0.2-0.8 mm. Comparisons with adjoining sections stained to demonstrate striosomes established that the local groups of striatal output neurons sometimes abutted striosomes but often did not. The retrogradely labeled clusters and bands appeared both in the caudate nucleus and in the putamen. Their arrangements were regular and often periodic. These findings suggest that the large matrix compartment of the primate striatum, which is the primary site of origin of striatal outputs to the pallidum and the reticular part of the substantia nigra, contains systematic mosaics of projection neurons. We propose that this output-neuron modularity of the striatal matrix in the primate could serve as the template for redistribution of the massive afferent-fiber systems of the striatum into specialized striatopallidal output channels.

Animals↗
PubMed2004

Identification of a novel rat microsomal vitamin D3 25-hydroxylase.

Vitamin D3 requires the 25-hydroxylation in the liver and the subsequent 1alpha-hydroxylation in the kidney to exert its biological activity. Vitamin D3 25-hydroxylation is hence an essential modification step for vitamin D3 activation. Until now, three cytochrome P450 molecular species (CYP27A1, CYP2C11, and CYP2D25) have been characterized well as vitamin D3 25-hydroxylases. However, their physiological role remains unclear because of their broad substrate specificities and low activities toward vitamin D3 relative to other substrates. In this study, we purified vitamin D3 25-hydroxylase from female rat liver microsomes. The activities of the purified fraction toward vitamin D3 and 1alpha-hydroxyvitamin D3 were 1.1 and 13 nmol/min/nmol of P450, respectively. The purified fraction showed a few protein bands in a 50-60-kDa range on SDS-PAGE, typical for a cytochrome P450. The tryptic peptide mass fingerprinting of a protein band (56 kDa) with matrix-assisted laser desorption ionization/time of flight mass spectrometry identified this band as CYP2J3. CYP2J3 was heterologously expressed in Escherichia coli. Purified recombinant CYP2J3 showed strong 25-hydroxylation activities toward vitamin D3 and 1alpha-hydroxyvitamin D3 with turnover numbers of 3.3 and 22, respectively, which were markedly higher than those of P450s previously characterized as 25-hydroxylases. Quantitative PCR analysis showed that CYP2J3 mRNA is expressed at a level similar to that of CYP27A1 without marked sexual dimorphism. These results strongly suggest that CYP2J3 is the principal P450 responsible for vitamin D3 25-hydroxylation in rat liver.

Animals↗
PubMedDate not supplied

Rat seminal-vesicle secretory protein SVS II binds DNA with a preference for the 5' regulatory region of secretory protein SVS IV gene: co-isolation with components of the nuclear matrix.

In rats, the ventral prostate and seminal vesicles produce distinct sets of proteins whose functions and tissue-specific regulation by androgens remain unclear. We have utilized the genes encoding the major secretory protein of seminal vesicles, SVS IV, and the C3 subunit of prostatein of the ventral prostate to study how the nuclear matrix might determine their tissue-specific gene expression. Nuclear matrix proteins were prepared from purified nuclei with DNase and 2 M NaCl, separated in SDS gels, and transferred onto membranes for DNA-binding (southwestern) and immunological (western) analyses. The 5' region of the SVS IV gene (SVS IV-7S) bound to a 45,000-kDa molecular-weight protein band in the nuclear matrix of seminal vesicles but not to that of ventral prostate, kidney, or liver. Sequencing revealed that this band was a seminal-vesicle secretory protein, SVS II, whose identity was confirmed with an anti-SVS II antiserum in western blots. Actin-like protein, similar in mobility to SVS II, was detected in seminal-vesicle and ventral prostate nuclear matrix, but not in seminal-vesicle fluid. Reducing agent (10 mM dithiothreitol) and acidic (pH 6.5) buffer did not eliminate SVS II, but isolation of nuclear matrices with ammonium sulfate, nucleases, and urea decreased SVS II immunoreactivity and removed actin-like protein. SVS II binding to SVS IV-7S DNA was greater than its binding to either a comparable fragment of the C3 gene or linearized pUC-19 plasmid, and it was not eliminated by a 100-fold competition. When seminal-vesicle fluid was mixed with rat liver, some SVS II co-isolated with the nuclear-matrix proteins, indicating that nonspecific interactions contribute to its association with the nucleoskeleton. However, these interactions may not represent the intracellular behavior of SVS II in seminal-vesicle epithelium. Sequence comparisons indicate significant homologies between SVS II and some other seminal proteins, including bovine caltrin, which, under the name seminalplasmin, is known to possess antimicrobial activity. Collectively, these data suggest that in addition to its known functions, SVS II may also bind extraneous DNA in seminal fluid. Additionally, SVS II may participate as a structural component in the organization of a tissue-specific seminal-vesicle nuclear matrix.

Animals↗
PubMed2005

The use of RAPD genomic fingerprinting to study relatedness in strains of Acidithiobacillus ferrooxidans.

Twelve strains of Acidithiobacillus ferrooxidans were recovered from acid mine drainage (AMD) sites from three different geographical locations: Copper Cliff, Ontario, Canada; Mineral City, OH, USA; and Cornwall, England. The spread-plate technique and various culture media were used to isolate and purify all strains. DNA was extracted from each purified culture and amplified using PCR and twenty, 10-mer primers. Amplification products were separated by gel electrophoresis and photographed under UV light. The RAPD (Randomly Amplified Polymorphic DNA) profiles were compared on the basis of the presence or absence of each DNA band and a data matrix was constructed. Strain diversity was calculated using the Jaccard's coefficient and UPGMA (Unweighted Pair-Group Arithmetic Average Clustering) cluster analysis. The variations in the banding patterns indicated genomic variability among the twelve A. ferrooxidans strains tested. The primers used in this study grouped the twelve strains into five major groups. Similarities between the strains ranged from 5.49% to 85.14%. These results show that the strains have a high degree of genomic diversity and that the RAPD procedure is a powerful technique to assess strain variability in this bacterium.

Acidithiobacillus↗
PubMed1991

Immunolocalization of N-acetylgalactosaminylphosphotransferase in the adult retina and subretinal space.

The cell surface N-acetylgalactosaminylphosphotransferase (GalNAcPTase) modulates N-cadherin-mediated adhesion among embryonic chick retinal cells (Balsamo et al., 1990). We are investigating the potential role of this transferase in modulating adhesive interactions in the adult retina. Using a previously characterized monoclonal anti-GalNAcPTase, we have used immunohistochemical and immunoblot techniques to localize and characterize the transferase in the retinas of the post metamorphic frog (Xenopus laevis), adult cow, and adult cynomolgus macaque. On frozen sections, anti-GalNAcPTase specifically labels the outer segments of photoreceptors in all species. Immunolabel appears at the surface of, or between rod outer segments in all species. The nerve fiber layer also shows high immunoreactivity in all species. Monkey cone outer segments are also highly immunoreactive. Photoreceptor inner segments are clearly immunoreactive in the cow retina. Immunoblots of purified cow rod outer segments show immunolabeled bands near 220 kDa, which is the molecular mass of the GalNAcPTase used as immunogen. Purified Xenopus rod outer segments are not immunoreactive on blots, while soluble interphotoreceptor matrix (IPM) shows immunoreactive bands principally at 113-130, and 166 kDa. Cow soluble IPM shows immunoreactivity at 180 kDa. Based on these findings, we propose that the GalNAcPTase, or a fragment thereof, is a component of the IPM, and perhaps of the photoreceptor outer segment as well.

Animals↗
PubMed2002

Responses of partially immersed elastic structures using a symmetric formulation for coupled boundary element and finite element methods.

Using a coupled BEM/FEM, this work describes a numerical method to compute the response and acoustic radiation for structures partially immersed in fluid. The structures and their responses are assumed to be symmetric about a symmetric plane. A symmetric complex matrix derived from the BEM and a reciprocal principle for surface acoustics is also used to represent the acoustic loading against the structures. In addition, selecting a proper Green's function based on image source method satisfies the boundary conditions of pressure release on the fluid surface and null normal velocity on the symmetric plane. Moreover, a boundary integral equation emerges when the field point approaches the structural surface where the normal derivative of the Green's function over partial, infinitesimal spheres is evaluated. These limiting values depend on locations of the field point on the surface. Owing to the symmetry of the acoustic loading matrix, the matrix for the coupled BEM/FEM is a banded, symmetric one, thereby allowing us to employ a variable banded storage method and invert of the matrix. Doing so markedly increases computational efficiency. Furthermore, an analytical solution of a spherical thin shell with the lower semi-sphere immersed in water is carried out by characteristic function expansions for shell equation and acoustic loading. These analytical solutions compare with the results obtained from the proposed numerical method. A good correlation for low frequencies is obtained and minor discrepancies are observed with an increasing frequency.

Journal Article↗
PubMed2006

Spectroscopic alterations on enamel and dentin after nanosecond Nd:YAG laser irradiation.

Laser irradiation on hard tissue has produced a resistant surface that is likely to prevent caries. In this study, human enamel and dentine were exposed to nanosecond pulsed Nd:YAG laser with energy densities of 20-40 J/cm(2) and pulse width of 6 ns inducing chemical changes in these tissues. Infrared analysis of human dental enamel and dentine was performed using the KBr method (2mg sample/300 mg KBr). A correlation between non-lased and lased spectra was performed that gives an indication of the changes in organic and inorganic compounds after laser-tissue interaction. Spectra of teeth simultaneously show the inorganic and organic parts of the tissue. The principal bands: amide bands A, I, II, and III from the collagen-matrix, phosphate from the mineral content, and carbonate bands were identified. The normalized area of peak versus peak position was determined. Changes of the bands attributed to the collagen matrix were verified after Nd:YAG irradiation. The present results suggest a chemical modification of organic and mineral compounds by laser. The spectral results indicated an alteration in the absorption bands relative to, essentially, organic compounds.

Dental Enamel↗