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The role of near-UV radiation as a cytoskeletal actin-damaging agent was investigated. Two procedures were used to analyse fresh smooth dogfish (Mustelus canis) eye lenses that were incubated for up to 22 hr in vitro, with elasmobranch Ringer's medium, and with or without exposure to a near-UV lamp (emission principally at 365 nm; irradiance of 2.5 mW cm-2). These were observed histologically using phalloidin-rhodamine specific staining and by transmission electron microscopy. In addition, solutions of purified polymerized rabbit muscle actin were exposed to the same UV conditions and depolymerization was assayed by ultracentrifugation and high-pressure liquid chromatography. While the two actins studied do differ very slightly in some amino acid sequences, they would react physically nearly identically. The results showed that dogfish lenses developed superficial opacities due to near-UV exposure. Whole mounts of lens epithelium exhibited breakdown of actin filaments in the basal region of the cells within 18 hr of UV exposure. TEM confirmed the breakdown of actin filaments due to UV exposure. SDS-PAGE and immunoblotting positively identified actin in these cells. Direct exposure of purified polymerized muscle actin in polymerizing buffer led to an increase in actin monomer of approximately 25% in the UV-exposed solutions within 3-18 hr, whether assayed by ultracentrifugation or HPLC. The above indicates that elasmobranch lens epithelial cells contain UV-labile actin filaments, and that near-UV radiation, as is present in the sunlit environment, can break down the actin structure in these cells. Furthermore, breakdown of purified polymerized muscle actin does occur due to near-UV light exposure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The effects of near-UV radiation on elasmobranch lens cytoskeletal actin. 142 55

Actin distribution in serially passaged embryonic mouse fibroblasts has been visualized by the anti-actin-PAP method; the organization of the microfilaments has been observed by electron microscopy (SEM and TEM). Four successive actin patterns have been identified: early (few well-organized bundles of microfilaments), middle-aged (many well-organized bundles and patches around the nucleus), late (numerous ill-organized filamentous structures and diffuse perinuclear-actin) and "senescent" (heavy packs of short microfilaments around the nucleus). All the observed actin-positive filaments were disrupted by cytochalasin B treatment. The cytoplasmic actin complex was cell-age and not cell-size-dependent; it behaved differently from the cytoplasmic microtubular complex to serially subcultivated fibroblasts. Measurements of the cell-protein content (Lowry's method) and SDS-polyacrylamide gel electrophoresis (Laemmli's method) have been performed in the successive population doubling levels (PDL) of the primary cultures. Triton-insoluble actin increased in parallel with total protein and reached about 4% of the total proteins in all the PDLs. Triton-soluble actin also increase at the beginning of the middle-aged period (generally 6 PDL) and another in declining cultures (generally 10 PDL). Total actin amounted to about 8% of the total proteins in early fibroblasts, to about 16% at the beginning of the middle-aged period and to about 20% in the declining terminal cultures. Taking into account all the known characteristics of subcultivated primary cultures, we tentatively consider the evolution of the fibroblasts as an in vitro differentiation followed by true in vitro senescence in the declining cultures. Regarding the cytoplasmic actin-complex, senescence would be characterized by a sharp increase in soluble actin, an unbalanced ratio between soluble and insoluble actin and an impairment of the ability of the microfilaments to form well-organized bundles.
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PMID:Actin content and organization of microfilaments in primary cultures of mouse embryonic fibroblasts (in vitro ageing). 293 19

Seven noncomplementing female sterile mutations that affect eggshell assembly in Drosophila have been mapped to the 7C1-3 region of the X-chromosome. TEM of the mature eggshell of one of the alleles, fs(1)410, shows a lack of organization within the endochorion and an accumulation of electron dense material in the vitelline membrane of stage 14 eggchambers. SDS-PAGE of radiolabeled eggshell proteins shows that two proteins, s67 and s85, fail to accumulate in the fs(1)410 eggshell. In wild-type flies s85 is produced during stage 10 of oogenesis and then processed to s67 in stages 13 and 14. Neither s85 nor an additional stage 10 specific follicle cell protein (s130) are detected in fs(1)410 or four of the mutant alleles. Short-term labeling studies, analyses of in vitro translation products, and the simultaneous occurrence of s85 and s130 as electrophoretic variants in geographic fly strains indicate s85 is derived from s130. Although major biochemical differences appear in stage 10, mutant and wild-type eggshells are morphologically indistinguishable until stages 13-14. These results suggest that follicle cell proteins synthesized during the time of vitelline membrane deposition (stage 10) are important for proper assembly of the chorion layers during stages 13 and 14.
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PMID:7C female sterile mutants fail to accumulate early eggshell proteins necessary for later chorion morphogenesis in Drosophila. 310 48

The incidence and mechanisms of ampicillin resistance (MIC greater than 1 mg/l) were investigated in 105 clinical isolates of Haemophilus influenzae collected in Edinburgh during 1983/4. Fifteen (14.3%) ampicillin-resistant strains were identified and these were non-serotypable and comprised six biotypes. Isoelectric focusing and beta-lactamase-inhibition studies demonstrated that production of the TEM-1 beta-lactamase was the principal mechanism of resistance in nine (60%) strains. Radiolabelling revealed that one beta-lactamase-positive strain also had an unusual penicillin-binding protein (PBP) profit. No beta-lactamase activity was detected in the other six (40%) ampicillin-resistant strains. Two beta-lactamase-negative ampicillin-resistant strains had atypical PBP profiles. SDS-PAGE analysis showed that four beta-lactamase-negative ampicillin-resistant strains, including one with altered PBPs, exhibited outer membrane protein profiles which differed from those of sensitive strains of the same biotype. The ampicillin-resistance mechanism of the remaining strain could not be determined. Thus, several resistance mechanisms, either acting individually or in combination, are implicated in ampicillin resistance in H. influenzae.
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PMID:Ampicillin resistance in Haemophilus influenzae: identification of resistance mechanisms. 350 21

A fucose binding protein was detected in boar spermatozoa by means of a specifically developed modified enzyme-linked-lectin-assay using glycosylated peroxidase derivatives. The distribution of the fucose binding protein was assessed by means of fluorescence microscopy with fluoresceinyl-glycosylated peroxidase. Fucose binding was particularly prominent at the apical region of the sperm head. In order to gain more insight into the precise localization of the carbohydrate binding protein electron microscopical studies were performed using fucosyl peroxidase coupled to colloidal gold. In ultrathin sections as well as in specimens prepared in toto for TEM an intensive binding of fucosylperoxidase-colloidal gold was predominantly found at the apical part of the acrosome appearing as a crescent-like area. In some cases this binding pattern was replaced by a triangle-like intensive labelling at the equatorial segment as revealed clearly by specimens prepared in toto. By SDS-PAGE of the SDS-extractable sperm-proteins, followed by transblotting to nitrocellulose and visualization with the fucosylperoxidase by enzymatic amplification with 4-chloro-1-naphthol mainly one protein with the reduced molecular weight of approximately 53 kdal and some small proteins with apparent molecular weights less than 20 kdal was found to be responsible for the fucose-binding ability of porcine spermatozoa.
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PMID:Evidence for a fucose-binding protein in boar spermatozoa. 390 13

The leukemic cells in chronic lymphatic leukemia (CLL) patients have been studied prior to theory with a panel of immunological markers. Cells were assayed for the presence of receptors for sheep erythrocytes (E active and total rosettes), C3d component of complement (EAC rosettes), mouse erythrocytes (M rosettes), some of them also for surface membrane immunoglobulins (SmIg). In vitro 24 h cultures without mitogen (detection of spontaneous DNA synthesis) or 72 h cultures with phytohemagglutinin (PHA) were also performed. These conventional immunological markers and functional lymphocyte characteristics have been correlated with enzyme activities of adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP). Electrophoretic patterns of radiolabeled proteins under denaturing conditions (SDS-PAGE) have also been determined in some patients of this group. Phenotypic surface characterization of blood elements of all CLL patients studied revealed their B origin, with increased values of EAC rosette forming cells and especially increased values of M rosette forming cells. Significantly decreased values of both, ADA and PNP, were found in all the cases. Electrophoretic patterns of radiolabeled surface proteins from cells of CLL patients were essentially similar within the group with characteristically strongly radiolabeled glycoproteins gp44--HLA heavy chain and glycoproteins gp29, gp35--Ia-like or HLA-DR antigen.
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PMID:Some immunological and biochemical markers in chronic lymphatic leukemia patients. 681 48

Placental extract was prepared with Tris-HCl buffer pH 7.4 containing EDTA and 2-mercaptoethanol. It agglutinated erythrocytes (E) sensitized with subagglutinating amounts of IgG antibodies from rabbits, guinea pigs and mice, but not E sensitized with IgG from chickens. E or E sensitized with F(ab)2 or IgM antibodies were not agglutinated. The agglutination of EA by the extract was inhibited by human, rabbit and guinea pig IgG, but not by bovine and porcine IgG. Aggregated IgG was more inhibitory than monomeric IgG. IgG3 was the most effective subclass. The extract inhibited the formation of EA rosettes with human mononuclear cells, but did not influence the formation of E or EAC rosettes. The significance of the disulfide bonds and the C gamma 3 and C gamma 2 regions was implied by the finding that the extract neither agglutinated E sensitized with preparations of mildly reduced and alkylated IgG, nor with Facb fragments. These preparations did not inhibit the agglutination. The results strongly indicated that the active component was solubilized placental Fc receptor (FcR). Functionally active FcR was purified by affinity chromatography using aggregated human IgG coupled to Sepharose 4B. SDS-PAGE if the purified FcR under reducing conditions showed one distance band corresponding to approx. 47,000 daltons. The band neither consisted o Ig fragments nor Clq. A rabbit antiserum against the FcR inhibited the agglutination of EA by the extract and stained th FcR-positive areas in placenta.
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PMID:Isolation and characterization of Fc gamma receptors from human placenta. 731 57

We present a novel approach for making cybrids. By introducing neo gene expression plasmids into rabbit reticulocytes, fusing the gene transferred reticulocytes with K562 cells and selecting in G418 selection medium, a cybrid strain K-RRneo was established. Whole mount TEM study demonstrated that after cybridization, there was a reorganization of the intermediate filaments which showed a tendency to differentiate towards reticulocytes. SDS-PAGE and western blot analysis verified the above observation, in which the vimentin blot pattern of the cybrids was similar to that of reticulocytes, but totally different from that of K562 cells. Using this model, we reaffirmed the hypothesis that the erythroid differentiation factor (EDF) might be responsible for erythroid differentiation as well as the initiation of denucleation.
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PMID:The relationships between erythroblast denucleation and the nuclear matrix--intermediate filaments. 778 Jan 9

Atrial Natriuretic Peptide (ANP), produced by atrial cardiomyocytes, is an endogenous hypotensive agent that brings about vasodilation and diuresis. Similar to other polypeptide hormones, ANP is synthesized as a precursor, preproANP. The preprohormone is processed intracellularly and is stored in secretory granules as the prohormone. During the events of exocytosis, the prohormone is converted to its active form, ANP. In this study, a double-label immunocytochemistry experiment was performed using ANP and clathrin antibodies to determine if the transport of this hormone is mediated by clathrin-coated vesicles. Additionally, we have isolated clathrin-coated vesicles (CVs) from adult rat atria using immunoadsorption, and have characterized the fraction by using SDS PAGE, TEM, and Western blot analysis. The data demonstrate that: (1) ANP and clathrin co-localize in myocardial tissue, (2) clathrin-coated vesicles can be isolated from adult rat atria, and (3) clathrin-coated vesicles isolated from adult atrial myocardium contain predominantly proANP. The presence of proANP in clathrin-coated vesicles suggests that this polypeptide hormone is transported intracellularly via a clathrin-mediated pathway and during transit the prohormone is not significantly converted to its active form.
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PMID:A clathrin-coated vesicle-mediated pathway in atrial natriuretic peptide (ANP) secretion. 834 Sep 33

Experiments using monoclonal and polyclonal anti-actin antibodies allowed us to demonstrate the presence of F- or G-actin in original protists, dinoflagellates, either by biochemistry, immunofluorescence and in TEM. SDS-PAGE electrophoresis and immunoblottings made either from total or nuclear protein extracts revealed the presence of a 44-kDa band reacting with monoclonal anti-actin antibody in two species, Prorocentrum micans and Crypthecodinium cohnii, and thus demonstrated the presence of actin in nuclear and cytoplasmic fractions. After squash preparation of P micans cells, actin was identified within the nucleus and in some regions of the cytoplasm by immunofluorescence microscopy. Labelling of both the nucleolus and the centrosome region was evident together with amorphous nucleoplasmic material surrounding the chromosomes. The use of cryosections of intact P micans and C cohnii cells for immunofluorescence along with staining with DAPI to delineate the chromosomes themselves, yielded finer resolution of the intranuclear network labelling pattern and allowed us to complete our observations, in particular on the cytoplasmic labelling. In P micans, in addition to the centrosome region, the cytoplasmic channels passing through the nucleus in dividing cells are labelled. In C cohnii, the cortex, the centrosome region, the cytoplasmic channels, the region surrounding the nucleus, the filaments linking it to the cortex and the cleavage furrow are also labelled. In the nucleus of the two species, there is a prominent "weft' of fine actin filaments in the nucleoplasm forming a matrix of varying density around the persistent chromosomes. This actin matrix, of unknown function, is most conspicuous at the end of the S-phase of the cell cycle. Fluorescent derivatives of phalloidin, used as diagnostic cytochemical probes for polymeric actin (F-actin), gave similar results. Positive TEM immunolabelling of intranuclear actin confirms its presence in the nucleoplasm, in the nucleolus where the preribosomal region is labelled while C cohnii chromosomes are unlabelled and the P micans chromosomes very slightly. In the cytoplasm, lips of the cleavage furrow and kinetosome regions are labelled as well as the centrosome region. The possible functions of this protein located in several compartments of dinoflagellate cells are discussed.
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PMID:Nuclear and cytoplasmic actin in dinoflagellates. 900 84


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