An avian serum alpha 1-glycoprotein, hemopexin, differing significantly in both amino acid and carbohydrate composition from mammalian (beta-glycoprotein) counterparts

We report here on physicochemical characteristics of chicken hemopexin, which can be isolated by heme-agarose affinity chromatography [Tsutsui, K., & Mueller, G. C. (1982) J. Biol. Chem. 257, 3925-3931], in comparison with representative mammalian hemopexins of rat, rabbit, and human. The avian polypeptide chain appears to be slightly longer (52 kDa) than the human, rat, or rabbit forms (49 kDa), and also the glycoprotein differs from the mammalian hemopexins in being an alpha 1-glycoprotein instead of a beta 1-glycoprotein. This distinct electrophoretic mobility probably arises from significant differences in the amino acid composition of the chicken form, which, although lower in serine and particularly in lysine, has a much higher glutamine/glutamate and arginine content, and also a higher proline, glycine, and histidine content, than the mammalian hemopexins. Compositional analyses and 125I concanavalin A and 125I wheat germ agglutinin binding suggest that chicken hemopexin has a mixture of three fucose-free N-linked bi- and triantennary oligosaccharides. In contrast, human hemopexin has five N-linked oligosaccharides and an additional O-linked glycan blocking the N-terminal threonine residue [Takahashi, N., Takahashi, Y., & Putnam, F. W. (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 2021-2025], while the rabbit form has four N-linked oligosaccharides [Morgan, W. T., & Smith, A. (1984) J. Biol. Chem. 259, 12001-12006]. In keeping with the finding of a simpler carbohydrate structure, the avian hemopexin exhibits only a single band on polyacrylamide gel electrophoresis under both nondenaturing and denaturing conditions, whereas the hemopexins of the three mammalian species tested show several bands.(ABSTRACT TRUNCATED AT 250 WORDS)     

Human alveolar macrophage fibronectin: synthesis, secretion, and ultrastructural localization during gelatin-coated latex particle binding

Human pulmonary alveolar macrophages synthesized and secreted several characteristic high molecular weight proteins for at least 7 d in vitro. Immunoprecipitates of medium and cell lysates from metabolically labeled cultures with specific anti-human plasma fibronectin IgG contained one major labeled polypeptide of molecular weight 440,000 (unreduced) or 220,000 (reduced). An identical polypeptide in conditioned medium from radiolabeled macrophages bound specifically to gelatin-Sepharose, demonstrating that alveolar macrophages synthesized and secreted a molecule immunologically and functionally similar to fibronectin. Fibronectin was the major newly synthesized and secreted polypeptide of freshly harvested alveolar macrophages. Pulse-chase experiments revealed that newly synthesized fibronectin was rapidly secreted into medium, approximately 50 percent appearing by 1 h and 80 percent by 8 h. Immunoperoxidase staining using antifibronectin F(ab’)(2)-peroxidase conjugates revealed the majority of immunoreactive fibronectin to be intracellular, localized to endoplasmic reticulum and Golgi apparatus. No extracellular matrix fibronectin was visualized, and cell surface staining was rarely seen, usually appearing only at sites where cells were closely apposed and not at sites of macrophage-substrate attachment. Similar immunostaining of fibroblast cultures revealed cell surface-associated fibrillar fibronectin. Ultrastructural localization of fibronectin during binding and phagocytosis of gelatin-coated and plain latex particles revealed fibronectin only on gelatin-latex beads and at their cell binding sites. Neigher plain latex beads nor their cell membrane binding sites stained for fibronectin. These results demonstrate that fibronectin is a major product of human alveolar macrophages, is rapidly secreted, and is localized at cell membrane binding sites for gelatin-coated particles. In view of the known binding properties of fibronectin, it may serve as an endogenous opsonic factor promoting the binding of staphylococcus, denatured collagen, fibrin, or other macromolecules to macrophages in the lower respiratory tract.     

The amide-type phytoalexin activity of carnation extracts is partly due to an artifact

The relative distribution of phytoalexins induced by Fusarium oxysporum fsp. dianthi in carnation and localized by pyrolysis-mass spectrometry in the xylem differs from that found by HPLC in acetone extracts. In situ, in the xylem, there is a predominance of 2-aryl-1,3-benzoxazin-4H-ones over the more fungitoxic N-aroylanthranilates. At least part of the dianthramides in the extracts has to be ascribed to artifacts apparently due to hydrolysis of benzoxazinones.     

Resistance to human immunodeficiency virus type 1 (HIV-1) infection in human CD4+ lymphocyte-derived cell lines conferred by using retroviral vectors expressing an HIV-1 RNA-specific ribozyme.

Toward gene therapy for the treatment of human immunodeficiency virus type 1 (HIV-1) infections in AIDS, Moloney murine leukemia virus-derived retroviral vectors were engineered to allow constitutive and tat-inducible expression of an HIV-1 5' leader sequence-specific ribozyme (Rz1). These vectors were used to infect the human CD4+ lymphocyte-derived MT4 cell line. The stable MT4 transformants expressing an HIV-1 RNA-specific ribozyme, under the control of the herpes simplex virus thymidine kinase (tk) promoter, were found to be somewhat resistant to HIV-1 infection as virus production was delayed. In cells allowing ribozyme expression under control of the simian virus 40 or cytomegalovirus promoter, the rate of HIV-1 multiplication was slightly decreased, and virus production was delayed by about 14 days. The highest level of resistance to HIV-1 infection was observed in MT4 cells transformed with a vector containing a fusion tk-TAR (trans activation-responsive) promoter to allow ribozyme expression in a constitutive and tat-inducible manner; no HIV-1 production was observed 22 days after infection of these cells. These results indicate that retroviral vectors expressing HIV-1 RNA-specific ribozymes can be used to confer resistance to HIV-1 infection.     

Mapping of facioscapulohumeral muscular dystrophy gene to chromosome 4q35-qter by multipoint linkage analysis and in situ hybridization

We have recently assigned the facioscapulohumeral muscular dystrophy (FSHD) gene to chromome 4 by linkage to the microsatellite marker Mfd 22 (locus D4S171). We now report that D4S139, a VNTR locus, is much more closely linked to FSHD. Two-point linkage analysis between FSHD and D4S139 in nine informative families showed a maximum combined lod score (Zmax) of 17.28 at a recombination fraction theta of 0.027. Multipoint linkage analysis between FSHD and the loci D4S139 and D4S171 resulted in a peak lod score of 20.21 at 2.7 cM from D4S139. Due to the small number of recombinants found with D4S139, the position of the FSHD gene relative to that of D4S139 could not be established with certainty. D4S139 was mapped to chromosome 4q35-qter by in situ hybridization, thus firmly establishing the location of the FSHD gene in the subtelomeric region of chromosome 4q. One small family yielded a negative lod score for D4S139. In the other families no significant evidence for genetic heterogeneity was obtained. Studies of additional markers and new families will improve the map of the FSHD region, reveal possible genetic heterogeneity, and allow better diagnostic reliability.     

Ultrastructural changes associated with weaning in the mandibular condyle of the rat

To determine the postnatal structural changes due to increasing articular activity, we have compared the development of the posterior and posterosuperior superficial layers of the rat mandibular condylar cartilage by electron microscopy. In contrast to the uniform development posteriorly, the posterosuperior articular zone showed an extensive remodelling process with collagen breakdown and replacement between the ages of 21 and 28 days, i.e. during weaning. Enlarged spheroid fibroblasts contained numerous micropynocytotic vesicles, collagen debris enclosing vacuoles and a nuclear fibrous lamina enveloping the nucleus; abundant electron-dense amorphous material was present in the matrix as well as covering the surface. An increased number of metabolically active fibroblasts was supplied by the mesenchymal stem cells of the underlying chondrogenic zone. The adaptation process resulted in the replacement of small randomly oriented collagen fibers by large compact bundles running parallel to the glenoid fossa, providing protection to the condyle against excessive wear and tear during incisal biting and grinding. The direct local relationship between (ultra) structure and functional load can be utilized in experimental research on the role of biomechanical forces in mandibular condylar growth and development.     

Zwei Muskelrezeptoren an der Mandibel von Leuctra (Insecta,Plecoptera) — Beispiele für nicht-ciliäre Sinnesorgane mit Tubularkörper-ähnlichen Strukturen

Zusammenfassung Beide Muskelrezeptoren an der Mandibel von Leuctra ziehen vom vorderen Tentorium-Arm zur Mandibel-Basis. Der ventrale Rezeptor besteht aus zwei dünnen Muskelfasern (6 bis 7 m Durchmesser) und mindestens 10 multiterminalen Sinneszellen, deren Dendriten sich im Innern der Fasern verzweigen und an den Z-Scheiben enden. Der dorsale Rezeptor besitzt drei ähnlich dünne Muskelfasern, aber nur eine einzelne multiterminale Sinneszelle. Ihre Dendriten enden im Ansatzgebiet des Muskels, zwischen Muskelfasern und Epidermiszellen.Beide Rezeptoren haben im wesentlichen denselben Feinbau wie bei Coleopteren, jedoch treten — besonders beim dorsalen Rezeptor — in den Dendriten-Enden Strukturen auf, die den Tubularkörpern bei Mechanosensillen ähneln.

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Two muscle receptor organs at the mandible of Leuctra (Insecta, Plecoptera) — examples for non-ciliary sense organs with tubular-body-like structures

Summary The muscle receptor organs of the mandible of Leuctra extend between the anterior tentorial arm and the mandible base. The ventral receptor is composed of two thin muscle fibres (6–7 m in diameter) and at least ten multiterminal sensory cells, the dendrites of which branch in the interior of the fibres and end near the z-bands. The dorsal receptor organ consists of three muscle fibres of similar diameter and only one multiterminal sensory cell. The dendritic ends lie at the distal end of the muscle, where muscle fibres and epidermal cells make contact.Both receptor organs essentially show the same ultrastructural characteristics as in Coleoptera. However, the dorsal receptor organ in particular possesses organelles in its dendritic ends, which look like the tubular bodies in ciliary mechanoreceptors.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft     

Murine malaria. I. Measurement of the mean rate of increase in vivo of Plasmodium berghei

Swiss mice were inoculated intraperitoneally with RBC infected with Plasmodium berghei. The moment a certain parasitemia was reached in each individual mouse was estimated by means of linear interpolation. The relationship between latent period and log inoculum was investigated by means of simple linear regression. The slopes of the latent period per log inoculum curves were significantly different using different donor mice inoculated with serial 10-fold dilution of infected RBC and exsanguinated in the same phase of the infection. It could not be demonstrated that the slopes of the regression lines depended on the stage of the disease of the donor mouse.