bluuebunny/crossref_metadata_2025 huggingface dataset:
Expression of nuclear lamins in mammalian somatic cells lacking cytoplasmic intermediate filament proteins
Authors: Paulin-Levasseur M. , Scherbarth A. , Giese G. , Röser K. , Bohn W. , Traub P.
Published: April 2021

Using immunofluorescence and immunoblotting techniques, we have examined the composition of the nuclear lamina in murine plasmacytoma cells, MPC-11, exposed to the phorbol ester TP A as well as in two cell lines devoid of cytoplasmic intermediate filament proteins, the human adrenal cortex carcinoma-derived cells SW-13 and the clone C6;-M-D4 derived from the rat glial cell line C6. Our results show that the inhibition of proliferation and the induction of vimentin synthesis observed in TPA-treated MPC-11 populations are not paralleled by changes in the lamin complement of these cells, which contain lamin B but lack lamins A and C. Furthermore, the analysis performed on SW-13 and C6-M-D4 cell lines clearly demonstrates that mammalian somatic cells display considerable variations in lamin expression and indicates that lamin B may be the only lamin species constitutively expressed in mammalian cells.
Quantal tektin synthesis and ciliary length in sea-urchin embryos
Authors: Stephens R. E.
Published: April 2021

Previous work using pulse-chase labelling of embryos from the sea-urchin Strongylocentrotus droebachiensis during ciliogenesis, regeneration or steady-state maintenance and elongation showed that a ciliary outer doublet microtubule-associated protein, originally termed component-20, was synthesized in a fixed or quantal amount. This suggested that the limited synthesis of component-20 might limit ciliary length, since the embryo has a large pool of most other ciliary components. Labelling experiments with S. purpuratus embryos now confirm quantal synthesis of component-20, while antibodies to S. purpuratus sperm flagellar tektins identify component-20 as the ciliary equivalent of the flagellar 55 ×lO3Mr tektin, tektin A. Sequential pulse-chase labelling at various times prior to isolation of cilia proves that the high specific activity of this protein truly reflects de novo synthesis of a structurally stable protein and not rapid protein turnover. Embryos may be animalized by growth in the presence of zinc ions, resulting in cilia averaging nearly twice the normal 20 pm length. When these embryos are pulse-chase labelled during ciliary growth and elongation, labelling of tektin A is proportional to the greater ciliary length, as is the pool of labelled but unincorporated tektins and other minor proteins. Deciliated animalized and control embryos, pulsechase labelled during their identical phases of ciliary regeneration, incorporate labelled tektin A to the same extent and have similar pools of unincorporated proteins. The correlation of enhanced tektin A synthesis with increased ciliary length and the coincidence of tektin A synthesis with ciliary elongation are observations consistent with the hypothesis that tektin A is a ciliary length-limiting structural element.
Biochemical characterization of the proteins of Paramecium secretory granules
Authors: Tindall Stephen H. , Devito Lynn D. , Nelson David L.
Published: April 2021

The proteins of trichocysts (secretory granules) from Paramecium tetraurelia have been biochemically characterized. Two-dimensional electrophoresis revealed 34 major components and at least 120 minor components, most with molecular weights ranging from 14000 to 21000 and isoelectric points ranging from 4·8 to 5·2. Comparison of two-dimensional electrophoretic patterns of trichocysts before and after exocytosis revealed only minor changes in these patterns, although the protein matrix undergoes a striking change in morphology. To clarify the interrelationships among trichocyst proteins, two proteins from extruded trichocyst matrix were purified to homogeneity and sequenced at their N termini. Their sequences are distinct, but they share limited homology.
The relationship between talin and acetylcholine receptor clusters in Xenopus muscle cells
Authors: Rochlin M. William , Chen Qiming , Tobler Markus , Turner Christopher E. , Burridge Keith , Peng H. Benjamin
Published: April 2021

Talin is involved in mediating the cytoskeleton-extracellular matrix interaction at focal contacts in cultured fibroblasts. Recently this protein has been localized at both the myotendinous junction (MTJ) and the neuromuscular junction (NMJ) in skeletal muscle. At the MTJ, talin may mediate the insertion of myofibrils into the plasma membrane, thus serving a function similar to that seen at focal contacts. However, the function of talin at the NMJ is unknown. In this study, we examined its distribution at both mature and developing acetylcholine receptor (AChR) clusters in Xenopus muscle cells both in vivo and in vitro with immunofluorescence. At the NMJs of both myotomal and submaxillaris muscles, talin was absent from the AChR clusters. In cultured myotomal muscle cells, it was absent from 40% of both the nerve-associated AChR patches and the spontaneously formed AChR clusters located on the top surface of the cells. We therefore conclude that this protein is not essential for maintenance of AChR clusters at the NMJ. In addition to MTJs, talin was invariably associated with AChR clusters induced by polyornithine-coated beads, and, to a large extent, with spontaneously formed clusters on the ventral side of cultured cells. A common feature of these talin-positive domains is the deep membrane infoldings, where bundles of actin filaments are inserted into the membrane. Thus, talin may be involved in the formation and maintenance of these structures. The deep membrane infoldings, though prominent at most NMJs, are absent from the two muscles under study in vivo. Our work thus suggests that the postjunctional membrane at the NMJ is heterogeneous, consisting of an AChR cluster domain and, often but not always, a domain for proteins involved in cytoskeleton-membrane linkage as exemplified by talin.
A rapid and convenient assay for counting cells cultured in microwell plates: Application for assessment of growth factors
Authors: Oliver Michael H. , Harrison Nicholas K. , Bishop Jill E. , Cole Peter J. , Laurent Geoffrey J.
Published: April 2021

There is currently much interest in the role of mediators that regulate cell proliferation. Methods to assay proliferative effects of such mediators usually involve cell counting techniques, which are tedious to perform, or methods based on uptake of radiolabelled thymidine, which may be prone to errors caused by precursor pool artefacts. We describe here an assay for estimating the number of adherent cells present in a microculture and its application to the study of growth factors. The assay depends on the binding of Methylene Blue to the fixed monolayer at pH 8·5 and, after washing the monolayer, release of dye by lowering pH. The use of an elution solvent containing acidified ethanol ensures a linear correlation between absorbance of the dye and cell number, and enables the assay to be carried out in 96-well plates measuring absorbance with an automated vertical light-path microplate photometer. The assay is rapid, highly reproducible and easy to perform, making it ideal for screening large numbers of samples. It was shown to be applicable to a number of foetal and adult cell lines derived from man and experimental animals. It was also demonstrated to be useful for assaying purified growth factors and detecting growth promoting activity in cell and tissue extracts.
Glycosylation mutations of serine/threonine-linked oligosaccharides in low-density lipoprotein receptor: Indispensable roles of O-glycosylation
Authors: Kuwano Michihiko , Seguchi Tadashi , Ono Mayumi
Published: April 2021

The low-density lipoprotein (LDL) receptor is a surface glycoprotein that mediates the cellular uptake of LDL, a cholesterol-carrying plasma protein (Goldstein et al. 1985). After receptor-mediated endocytosis of LDL, LDL receptor recycles to the cell surface from the acid compartment, the endosome, and LDL is then transported and degraded in lysosomes where the cholesterol ester core is hydrolysed and from which the unesterified cholesterol is released. The cholesterol molecules from LDL regulate de novo cholesterol biosynthesis and LDL receptor expression. Mutations in the receptor gene for the LDL receptor impair LDL uptake into cells and cause familial hypercholesterolemia (FH) because of the lack of normal regulation of cholesterol metabolism (Goldstein et al. 1985).
Involvement of transmembrane proteins in the association of cortical microtubules with the plasma membrane in tobacco BY-2 cells
Authors: Akashi Tomohiro , Shibaoka Hiroh
Published: April 2021

Abundant microtubules (MTs) were present both in protoplasts isolated from tobacco BY-2 cells and on membrane ghosts prepared from such protoplasts. However, only a few MTs or none at all were observed on membrane ghosts prepared from protoplasts pretreated with protease, trypsin or chymotrypsin, although abundant MTs were present in protease-pretreated protoplasts. These observations suggest that the digestion of the extracellular portion of transmembrane protein(s) results in the dissociation of cortical MTs from the plasma membrane. Exogenously applied extensin or poly-L-lysine increased the cold-stability of cortical MTs in the control protoplasts, but not in protease-pretreated protoplasts. It appears that the transmembrane protein(s) is also involved in the stabilization of cortical MTs by extensin or poly-L-lysine. Cortical MTs in BY-2 cells were arranged parallel to one another and were resistant to cold. Treatment with protease rendered the MTs sensitive to cold and often disturbed the parallel array of cortical MTs. These results suggest that transmembrane protein(s) is involved in the arrangement and stabilization of cortical MTs in tobacco BY-2 cells.
Expression of a developmentally regulated cross-linking intermediate filament-associated protein (ifapa-400) during the replacement of vimentin for desmin in muscle cell differentiation
Authors: Cossette Louis J. , Vincent Michel
Published: April 2021

Myogenic and neurogenic tissues of the chick embryo transiently express IFAPa-400, a high molecular weight protein that colocalizes and is copurified with intermediate filaments. Using monoclonal antibody F51H2 to identify it, we carried out immunoelectron microscopy experiments on whole-mount chick embryo cells and showed that IFAPa-400 was localized at crossing points of intermediate filaments. Also, immunoblot experiments with F51H2, anti-vimentin and anti-desmin antibodies demonstrated the complete disappearance of IFAPa-400 in those muscle cell types that change their vimentin content for desmin during embryogenesis. During in vitro myogenesis, the expression of IFAPa-400 was shown to be concurrent with the progressive replacement of vimentin by desmin in myoblasts. When long-term myotube cultures were maintained on a fibroblastlike cell layer, we observed the complete replacement of vimentin by desmin, followed by the disappearance of IFAPa-400 from the myotubes. These results suggest that IFAPa-400 might be involved in the reorganization of the intermediate filament network during muscle differentiation.
Cellular invasion into matrix beads: Localization of fa integrins and fibronectin to the invadopodia
Authors: Mueller Susette C. , Chen Wen-Tien
Published: April 2021

We have examined the contribution of adhesion mechanisms to cell invasiveness by growing chicken embryo fibroblasts (CEF) or Rous sarcoma virus-transformed cells (RSVCEF) on fibronectin-coated crosslinked gelatin beads (FN-beads). RSVCEF attached more readily and spread more rapidly on FN-beads than CEF, suggesting an increase in the adhesion-related motility of the transformed cells. In addition, RSVCEF invaded the FN-beads, but CEF did not, by extending specialized cell surface protrusions called invadopodia at sites of cell invasion. FN removal by RSVCEF cultured on prelabeled fluorescent FN-beads (FL-FN) was evident at sites of invadopodia, and internalized FL-FN occurred in vacuoles near the ventral membrane of cells at sites of FN removal. The precise distribution of FN and integrins in cells invading FN-beads was determined by immunofluorescence and immunoelectron microscopy of frozen thin-sections. In both CEF and RSVCEF, α1 integrins and FN occupied separate intracellular compartments during the early stage of spreading on FN-beads. Later, α1 integrins were largely localized at the ventral cell surface of both CEF and RSVCEF. Polyclonal anti-integrin antibody recognizing α1 and several β chains, however, labeled both ventral and dorsal cell surfaces. During invasion by RSVCEF, α1 integrins were concentrated at extended invadopodia and also colocalized with internalized FL-FN material in phagocytic vesicles. Furthermore, secreted FN was deposited by RSVCEF at the base of invadopodia colocalizing with α1 integrin. Both FL-FN matrix removal and formation of the invadopodia were found to be resistant to treatment with GRGDS at concentrations that inhibit the interaction between cells and FN-beads. Thus, the localization of α1 integrins to the plasma membrane contacting immobilized FN results in an extremely tight cellular adherence to the matrix bead, that stabilizes invadopodia and also mediates endocytic clearance of degraded FN-matrix material.
Spatial and temporal distribution of DNA replication sites localized by immunofluorescence and confocal microscopy in mouse fibroblasts
Authors: Fox M. H. , Arndt-Jovin D. J. , Jovin T. M. , Baumann P. H. , Robert-Nicoud M.
Published: April 2021

The temporal course of replication monitored by 2- or 5-min pulses of bromodeoxyuridine (BrdUrd) incorporation in synchronized 3T3 cells was mapped by high-resolution light microscopy employing a charge-coupled device (CCD) camera and a confocal laser scanning microscope (CLSM). The cells were labeled simultaneously with monoclonal antibodies directed against BrdUrd and nuclear lamin, and stained with the A+T-specific dye 4′,6-diamidino-2-phenylindole (DAPI). Stereoscopic reconstructions of cells showing both the lamin and BrdUrd distributions demonstrate that DNA replication occurs at discrete sites in the nucleus, the locations of which progress through a programmed sequence during S phase. Replication begins in a small number of sites in the interior of the nucleus exclusive of the nuclear membrane and proceeds rapidly in early S phase to encompass a relatively large number of small, discrete sites located throughout the nucleus, with the exception of the condensed heterochromatic regions. Replication is primarily confined to the condensed heterochromatic regions in mid-to-late S phase, and to the nuclear periphery at the end of S phase. These distinctive patterns demonstrate a programmed control of replication sites in the spatial domain in differentiated cell nuclei.
Pollen development in orchids 3. A novel generative pole microtubule system predicts unequal pollen mitosis
Authors: Brown R. C. , Lemmon B. E.
Published: April 2021

Cytoplasmic preparation for the unequal first mitosis in non-vacuolate pollen of moth orchids (Pbalaenopsis) includes reorganization of the microtubular cytoskeleton and nuclear migration. Following meiotic cytokinesis, both microtubules and F-actin are unpolarized in microspores of persistent tetrads. Microtubules radiate from the centrally located nucleus and F-actin forms a reticulate pattern in the cytoplasm. Polarization of the microspores is marked by a dramatic reorganization of microtubules while the pattern of F-actin remains unchanged. We describe a novel system of microtubules at the generative pole (GPMS), which forms a polar structure at the distal surface and marks the path of nuclear migration prior to pollen mitosis. The GPMS consists of numerous microtubules that extend between the plasma membrane and nuclear envelope. The nucleus becomes displaced toward the generative pole and flattened in association with microtubules of the GPMS. Initiation of the GPMS is marked by a localized proliferation of ER and clearing of large organelles from the generative pole.
A common epitope is shared by ciliary rootlets and cell-cell adherens junctions in ciliated ependymal cells
Authors: Peraldi-Roux Sylvie , Klotz Catherine , Nguyen-Thanh-Dao Brigitte , Gabrion Jacqueline
Published: April 2021

Using immunoblot, light and electron immunocytochemistry, we investigated the presence and the localization of polypeptides cross-reacting with the monoclonal antibody CC.310 (mAb CC.310), which is mainly directed against a 175K (K=103Mr) ciliary rootlet protein. In hypothalamic ependymal cultures, the unique antigen recognized by mAb CC.310 was associated with the Triton X-100-insoluble fraction in these cultures and electrophoretically migrated to 94K. mAb CC.310, which appears to be a very suitable marker for ciliated ependymocytes, allowed us to observe ciliogenesis during the growth of the ependymal cultures, from a single spot in each undifferentiated ependymal cell to a massive labeling in ciliated ependymal cells. In fully differentiated ciliated epen dymocytes, mAb CC.310 strongly reacted with fibrous structures corresponding to ciliary rootlets, as confirmed by ultrastructural observations. In addition, a weaker immunostaining was also found along the intercellular junctions, and showed that proteins sharing a common epitope are located in ependymal ciliary rootlets and near adherens-type junctional complexes. Immunofluoréscence studies confirmed the presence of positive labeling at the level of junctional complexes between cells in two epithelial lines, HeLa and PtK2, in which mAb CC.310 mainly reacted with one polypeptide of 85K.
Expression of lymphocyte perforin in the mouse uterus during pregnancy
Authors: Zheng Li Mou , Liu Chau-Ching , Ojcius David M. , Young John Ding-E
Published: April 2021

In situ hybridization and immunofluorescence were used to study the expression of a lymphocyte poreforming protein (perforin) in the uterus of pregnant mice. Cells expressing perforin mRNA were detected as early as gestation day 5, whereas perforin protein was detected one or two days later. Although the number of cells expressing both perforin mRNA and perforin protein varied subsequently with time, they were consistently observed from the day of implantation until parturition. The highest levels of mRNA expression were observed sometime dining midgestation. The high abundance of this cytolytic protein in the metrial gland during pregnancy and the time course of its expression thus suggest that GMG perforin expression is tightly regulated, probably hormonally, by the uterus, and that GMG cell perforin plays an important role in the normal completion of pregnancy.
Cytodifferentiation of mouse mammary epithelial cells cultured on a reconstituted basement membrane reveals striking similarities to development in vivo
Authors: Aggeler Judith , Ward Jerome , Blackie Leslie Mackenzie , Barcellos-Hoff Mary Helen , Streuli Charles H. , Bissell Mina J.
Published: April 2021

In the present study we provide evidence that the cytodifferentiation of primary mouse mammary epithelial cells within the alveolar-like structures formed after culture on a reconstituted basement membrane resembles development in vivo during late pregnancy and early lactation. During the first two days in culture on a basement membrane gel in the presence of lactogenic hormones, epithelial cells isolated from mid-pregnant mice are disorganized and central lumina are largely absent. Levels of mRNA for the milk proteins, β-casein and transferrin, are dramatically reduced. By the second or third day in culture, cytoplasmic polarization becomes evident and prominent apical junctional complexes are formed. Synthesis of both mRNA and milk protein is reinitiated at this time. By day 4, well-defined lumina appear, and abundant synthesis and secretion of casein and lipid is observed. A striking feature of this differentiation in culture is the specific localization of milk protein gene expression (β-casein mRNA) to luminal epithelial cells in the alveolar-like structures. At the ultrastructural level, increased milk protein synthesis and secretion are paralleled by a fourfold increase in rough ER that resembles the dramatic increase in the ER observed in vivo following parturition. One indication of tissuespecific differentiation observed in later cultures (days 4–11) is the synthesis and secretion of abundant casein micelles. A second characteristic of lactating mammary epithelial cells in vivo that has not previously been observed in culture is the secretion of milk fat globules. Taken together, these observations indicate that mammary epithelial cells plated onto a reconstituted basement membrane differentiate to the lactating phenotype in culture.
Morphological expression of cell transformation induced by c-Ha-ras oncogene in human breast epithelial cells
Authors: Russo J. , Tait L. , Russo I. H.
Published: April 2021

The present work describes the morphological pattern of c-Ha-ras-transformed MCF-10A cells. This immortalized human breast epithelial cell line was transfected utilizing the calcium phosphate technique with pHo6 containing the neomycin-resistant gene alone, and identified as MCF-lOAneo, or with the normal Ha-ras proto-oncogene, MCF-lOAneoN, or with the human p24 mutated Ha-ras oncogene, MCF-lOAneoT cells. These three cell types were studied by scanning and transmission electron microscopy at passages 6 and 20 post-transfection. It was observed that transfection with the plasmid alone did not induce any morphological changes in MCF-10A cells. These two cell types exhibited those features that are characteristic of mammary epithelial cells in culture. Amplification of the normal c-Ha-ras oncogene by transfection induced significant morphological changes at the level of cell shape, from flat to cuboidal, and cytoplasmic changes suggesting a more metabolically active cell. These changes were made more prominent by transfection with the mutated ras oncogene, which induced stratification of a cuboidal epithelium and increase in cell size as well as a more pleomorphic nuclear and cytoplasmic appearance.

Distinctive features induced by the mutated c-Ha-ras oncogene were the lengthening and thickening of cell surface microvilli, formation of blebs and emission of filopodial projections. It induced cytoplasmic changes consisting of formation of intracellular lumina, and increased the number of lysosomes, mitochondria and glycogen content, significantly decreasing the number of intermediate filaments. This is the first report that describes the morphological characteristics of a human breast epithelial cell line transformed in vitro.
Cell surface oligosaccharides on Dictyostelium during development
Authors: Amatayakul-Chantler Supavadee , Ferguson Michael A. J. , Dwek Raymond A. , Rademacher Thomas W. , Parekh Raj B. , Crandall Ian E. , Newell Peter C.
Published: April 2021

Developmental studies of the changes in protein glycosylation are useful in elucidating the role of oligosaccharides in biological events. We have used the chemical technique, hydrazinolysis, to release oligosaccharides from cell surface glycoproteins of Dictyostelium discoideum. Oligomannose type, xylose- and fucose-containing oligosaccharides were found to be present. The charged oligosaccharides contained sulphate and mannose 6-phosphate residues; no sialic acid was detected. The charged oligosaccharides also contained significant amounts of xylose, arabinose, fucose and galactose, as well as mannose and N-acetylglucosamine, which were the main constituents of the neutral glycans.

By monitoring the chemical characteristics of the liberated oligosaccharides, dramatic changes in both the charge and size distribution of cell surface oligosaccharides were observed throughout the 24 h period of cell development. A comparison, however, between the neutral glycan structures of prestalk and prespore cells, over the same time frame showed no dramatic differences.

Discoidin, a lectin present on the cell surface of 8 h cells, was found not to be glycosylated. Affinity chromatography using immobilised discoidin was used to probe a sugar library made from the cell surface glycoproteins of 8h cells. Discoidin was found to bind selectively an oligosaccharide with the structure Manα3(Manα6)(Xylβ2)Manβ4GlcNAc. This oligosaccharide lacks a conventional N,N′-diacetyl- chitobiose core and has only been previously observed in plant glycoproteins. Peptide-N-glycosidase F treatment of horseradish peroxidase released an identical structure, confirming that the oligosaccharide was not a degradation fragment of the hydrazine. The oligosaccharide was found to inhibit discoidin-mediated haemagglutination with a Ki of 0.75 mM, a concentration approximately 100 times lower than that for galactose.

The correlation between changes in the amoebal plasma membrane oligosaccharide structures and the biological events occurring at different stages of development such as cell-cell adhesion and cell-substratum attachment suggest an important role for sugars in these processes.
The organic anion transport inhibitor, probenecid, inhibits the transport of Lucifer Yellow at the plasma membrane and the tonoplast in suspension-cultured plant cells
Authors: Cole Louise , Coleman Julian , Kearns Anne , Morgan Gareth , Hawes Chris
Published: April 2021

In this paper we report on the uptake of the membrane-impermeant fluorescent probe Lucifer Yellow CH (LY-CH) into the vacuolar system of plant cell suspension cultures. LY-CH is internalised into vacuoles of maize cells at a faster ‘rate’ than carrot cells and in each case, the probe is also trapped at the cell wall. In the presence of the uricosuric drug probenecid, the vacuolar uptake of LY-CH by carrot and maize cells is inhibited and in some cells internalisation of probe is blocked at the plasma membrane. In electroporated carrot cells, LY-CH is sequestered slowly from the cytoplasm into vacuoles by a probenecid-inhibitable transport process. These results are compared with the effects of probenecid on the sequestration of LY-CH from the cytoplasm into the lysosomal system of fibroblasts. In view of the above findings and recent evidence for the putative uptake of LY-CH by fluid-phase endocytosis in plant cells, the possibility that LY-CH is transported across plant membranes via probenecid-inhibitable organic anion transporters is discussed.
Unexpected destruction of chitosomal chitin synthetase by an endogenous protease during sucrose density gradient purification
Authors: Kamada Takashi , Bracker Charles E. , Lippman Eleanor , Bartnicki-Garcia Salomon
Published: April 2021

Because of their intrinsic low buoyant density, chitosomes can be separated from crude cell homogenates (1000 g or 35000 g supernatants) of Mucor rouxii by isopycnic sedimentation in sucrose density gradients. To accelerate and simplify the isolation of chitosomes, we centrifuged the cell-free extracts at ultrahigh speed (in a fixed-angle rotor at forces up to 311000 g Rav) and found that the duration of centrifugation was critical. Prolonged centrifugation at ultrahigh speed caused severe distortion of the chitin synthetase profile in the gradient as the peak of chitosomal chitin synthetase nearly disappeared. We traced the problem to a soluble protease(s) that moved into the chitosome band during protracted centrifugation and destroyed the chitin synthetase activity. The interfering protease was a soluble protein with a sedimentation coefficient of 4.6 S and a pH optimum of 7-7.5, and it was sensitive to PMSF (phenyhnethylsulfonyl fluoride), indicating that it was a serine protease. Unlike other proteases, it destroyed chitin synthetase but did not activate the chitin synthetase zymogen. The interfering protease could be eliminated either by adding PMSF to the cells immediately after breakage or by removing the upper part of the sucrose gradient midway through the centrifugation of the cell-free extract and then completing the sedimentation with the ‘decapitated’ gradient
Adhesion of L1210 cells to modified styrene copolymer surfaces in the presence of serum
Authors: Kowalczyńska Hanna Maria , Kamiński Jarosław
Published: April 2021

The static adhesion of living L1210 cells (in serum-containing medium) to the surface of (styrene/methyl methacrylate) copolymers differing in styrene content (from 5% to 50% of styrene units) was investigated. The examination of wettability of the copolymer surfaces showed that the contact angle of water on the hydrophobic surfaces is an increasing linear function of styrene content in the copolymer. Cell adhesion to the unwettable surfaces is low (within 2-4 %). A novel method of modification of the styrene copolymer surfaces was used to render these surfaces suitable for cell attachment. The modification consists of sulfonation of the surfaces with sulfur trioxide at the gas/solid interface. The contact angle of sulfonated copolymer surfaces is a decreasing linear function of styrene content in the copolymer. The contact angle decreases due to the increased number of highly hydrophilic sulfonic groups bonded to styrene. By acetylation of the sulfonated surfaces it was shown that cell adhesion to acetylated surfaces is not diminished and is at the same level as cell adhesion to sulfonated copolymer surfaces. Thus, it can be concluded that sulfonation of copolymer surfaces does not form hydroxyl groups. Cell adhesion to substrata of high wettability stabilizes after 30 s. The relative number of cells adhering to the sulfonated copolymer surfaces is a decreasing linear function of the contact angle. For the copolymer surfaces containing 50% of styrene units the contact angle decreases sevenfold, due to sulfonation, and the number of adhering cells increases 40-fold. The results obtained show that for cell-substratum adhesive interaction the presence of sulfonic groups at the substratum surface is important
Fusion proteins containing a minimal G Pl-attachment signal are apically expressed in transfected MDCK cells
Authors: Lisanti Michael P. , Caras Ingrid W. , Rodriguez-Boulan Enrique
Published: April 2021

We have shown that addition of the C-terminal 37 amino acids of decay-accelerating factor (DAF) to secretory proteins leads to glycosyl-phosphatidyl-inositol (GPI) anchoring and apical surface expression in MDCK cells. Theoretically, transferred apical sorting information may reside in the glycol-lipid-anchor moiety or the DAF sequence (9 amino acids) that remains after signal cleavage and GPI attachment We show here that removal of eight of these nine remaining amino acids, thereby creating a minimal GPI-attachment signal, results in apical expression of GPI-anchored human growth hormone. These data argue that the apical sorting information conveyed by the C terminus of DAF is related to its ability to direct GPI attachment, rather than to a specific sequence that remains in the fusion protein.
The synthesis of type X collagen by bovine and human growth-plate chondrocytes
Authors: Marriott Anne , Ayad Shirley , Grantx Michael E.
Published: April 2021

Chondrocytes were isolated from bovine growth-plate cartilage and cultured within type I collagen gels. A major collagen with chains of Mr 59000, decreasing to 47 000 on pepsinization, was synthesized and identified as type X collagen. This collagen was cleaved at two sites by mammalian collagenase, resulting in a major triple-helical fragment with chains of Mr 32000. The species of Mr 59000, 47000 and 32000 were not detected by SDS-polyacrylamide gel electrophoresis before reduction, indicating the presence of disulphide bonds within the triple helix. In contrast, similar biosynthetic studies with human growth-plate cartilage in organ culture, indicated that human type X collagen does not contain disulphide bonds. A polyclonal antiserum was raised to bovine type X collagen and used in immunolocalization studies to provide direct evidence for the association of type X collagen with the hypertrophic chondrocytes in both bovine and human growth plates during development.
Transferrin gene expression and transferrin immunolocalization in developing foetal rat lung
Authors: Skinner Stephen J. M. , Somervell Christine E. , Buch Shilpa , Post Martin
Published: April 2021

In previous studies we have shown that transferrin (Tf) specifically stimulates dermatan- and chondroitm-sulphate proteoglycan accumulation around lung cells, and in the extracellular matrix of lung tissue, in vitro. The aim of this study was to determine whether the gene for Tf was activated in specific lung cells during development, and whether the protein product showed evidence of association with extracellular matrix. The expression of the gene in developing lung was shown by the hybridization of a Tf cDNA to a 2.4 kb (kilobase) mRNA species in total RNA extracts of foetal lung. The expression of the Tf gene in comparison to a control gene (GAPD, glyceraldehyde phosphate dehydrogenase) was greatest in 19, 20 and 21 day foetal lung, rising from low levels on day 18 and decreasing markedly at term (day 22). Extracts of RNA from primary cultures of mesenchymal fibroblasts and type II epithelial cells were also analysed for Tf mRNA. These experiments indicated that Tf gene expression was predominantly confined to the mesenchymal compartment.

The presence of Tf in histological sections of foetal lung was demonstrated by immunohistochemistry and showed a distinct pattern, with intense staining of the alveolar and the capillary basement membranes. The matrix surrounding the mesenchymal fibroblasts was stained in a diffuse network while epithelial cells were unstained. The staining was low from days 12-16 of gestation, increased to a maximum at days 19-20 but decreased markedly toward term. The Tf staining did not co-localize with transferrin receptor, also demonstrated by immunohistochemistry.

These results suggest that Tf is not only present at specific sites in the developing lung, but also is synthesized according to a strict developmental schedule of gene expression.
Extracellular matrix adhesion-promoting activities of a dermatan sulfate proteoglycan-associated protein (22K) from bovine fetal skin
Authors: Lewandowska Kristine , Choi Haing U. , Rosenberg Lawrence C. , Sasse Joachim , Ame Peter J. Ne , Culp Lloyd A.
Published: April 2021

A 22×103Mr protein (abbreviated 22K) that co-purifies with dermatan sulfate proteoglycans (DS-PGs) following the biochemical fractionation of bovine fetal skin has been evaluated for adhesion-promoting activity in vitro using Balb/c 3T3 cells, as well as bovine and human dermal fibroblasts. Substrata coated with 22K protein promote attachment of a subset of 3T3 and dermal fibroblasts that respond to plasma fibronectin (pFN) substrata. Cells on 22K protein display partial cytoplasmic spreading, comparable to that of cells adhering to cell-binding fragments of pFN. Adhesion activity of 22K is not due to contamination with known adhesive proteins of dermal matrices and is not dermal cell type-specific, since two classes of neuronal cells also respond effectively to 22K substrata. DS-PGs from cartilage or skin completely inhibit 22K adhesion activity when the PGs are adsorbed to 22K substrata under conditions prohibiting PGs from binding to substrata directly. Cartilage chondroitin/keratan sulfate proteoglycan at much higher concentrations is only partially inhibitory. Inhibition by DS-PGs is mediated by DS chains binding to 22K. Properties of the cell surface ‘receptor’ for 22K protein were tested by several approaches. It is not cell surface DS-PG, since: (1) cells unable to produce this proteoglycan class also responded; (2) cells treated with chondroitinase ABC responded equally well; and (3) substrata of proteoglycan-binding platelet factor-4 generated responses from cells that were quantitatively and qualitatively different A synthetic peptide in the medium containing the Árg-Gly-Asp-Ser (RGDS) sequence completely inhibited responses to 22K substrata. This observation, coupled with sequencing data of 22K protein revealing an Arg-Gly-Ala-Thr sequence at residues 151-154, suggest that 22K protein mediates adhesion by cell surface integrin binding. Therefore, this newly discovered matrix protein from skin may serve as a communication link between the dermal fibroblast cell surface and its extracellular matrix environment
Observations on the Muscular Tissue of the Skin
Authors: Lister Joseph
Published: April 2021

Among the abundant new matter contained in those parts of ‘Kolliker’s Microscopische Anatomie ‘that are hitherto published, there is perhaps nothing more striking than the announcement that small bundles of unstriped muscle exist in all parts of the dermis that are provided with hairs, connected inferiorly with the hair-follicles, just below the sebaceous glands, and passing up obliquely towards the free surface of the skin.
On the Identity of a Colouring Matter present in several Animals with the Chlorophyll of Plants
Authors: Schultze M. Max
Published: April 2021

The author enumerates several animals of a green colour, which are common in ditches and marshes—such as Hydra viridis, several green Turbellariœ, Vortex viridis, Mesosternum viridatum, and Derostomum cæcum ; and also several green Infusoria, such as Stentor polymorphus, Ophrydium versatile, Bursaria vernalis, &c. The colour in these animals is afforded by minute green globules, about 0.016 inch in diameter, which are situated under the integument in the parenchyma of the animals. They are perfectly spherical, and exhibit within the green substance an extremely minute, colourless, and homogeneous nucleus; or they may consist of several minute green globules, grouped together in a mulberry form ; in this latter case they arise from the division of a homogeneous vesicle.
Principles of the anatomy and physiology of the vegetable cell
Authors: Mohl Hugo Von
Published: April 2021

The use of the microscope alone has rendered the production of such a work as this possible. It is only a few years ago, if the existence of cells in plants was not altogether ignored, that their presence was regarded as a matter of little or no consequence, and vegetable physiologists speculated on the functions of plants, without knowing anything of the agencies by which they were produced. Microscopic research has, however, shown us that it is in the interior of these minute constituents of vegetable tissue that all the functions of plants are carried on. Hence we may truly say that the principles of the anatomy and physiology of the vegetable cell are the principles of vegetable anatomy and physiology.
Royal institution of great britain
Authors: Huxley Thomas H.
Published: April 2021

The Lecturer commenced by referring to his endeavours last year to shew that the distinction between living creatures and those which do not live, consists in the fact, that while the latter tend to remain as they are, unless the operation of some external cause effect a change in their condition, the former have no such inertia, but pass spontaneously through a definite succession of states—different in kind and order of succession, for different species, but always identical in the members of the same species.
On the Structure of the Muscular Fibril and the Muscularity of Cilia
Authors: Barry Dr.
Published: April 2021

Dr. M. Barry’s “dominant idea” is a twin spiral; and, inspired by this perverse and pertinacious spirit, he has again presented us with a repetition of his views with respect to the structure of the muscular fibre and vibratile cilium, in an attempt to assign the “Main cause of discordant views on the Structure of the Muscular Fibril,” together with some “Further Remarks on the Muscularity of Cilia,” in the November number of the ‘ Philosophical Magazine.’
Microscopical Society
Authors: Jackson George
Published: April 2021

The author stated, that the object of this paper was to afford a practical illustration from Nature herself, in proof of the reality of that which has hitherto been but a theory in histology. For this purpose the structure of the hairs growing on the spurred petal of Viola tricolor, or Heartsease, is described as seen under the microscope, each hair affording in itself examples of the three processes considered by the author as requisite for the formation of tube.
On a microscope adapted for Anatomical Demonstrations ; and on a Binocular Microscope
Authors: Nachet M.
Published: April 2021

All micrographers have felt the difficulty of defining the nature and situation of an object in the field of a microscope so as to make it apparent to several persons. I need not explain that this arises from the number of different objects visible at the same time, and often also from the moving of the objects themselves in fluids, particularly infusoria, which it is impossible to show in the same state in which one has observed them oneself.
On the Ultimate Structure and Relations of the Malpighian Bodies of the Spleen and of the Tonsillar Follicles
Authors: Huxley Thomas
Published: April 2021

The first account of those peculiar whitish corpuscles, discovered by Malpighi and to be met with, more or less distinctly marked, in the spleen of every animal, which at all satisfies the requirements of modern anatomical science, was given by Professor Müllier, in his Archiv. for 1834. Müller describes with great accuracy the mode in which these bodies are supplied by minute arteries, and explains that they are, in fact, outgrowths of the adventitious tunic of those arteries. He states that, by means of fine injections, he found that “the arterial twigs sometimes passed by the side of the Malpighian bodies without giving off any branches to them—sometimes went straight through the whole body or a part of it, in which case, however, no portion of the arteries terminated in them. These fine arterial twigs appear less to pass through the middle of the corpuscles than to run on their walls and then to leave them. When an arterial twig divides into many minute branches in the Malpighian body, which never takes place upon its surface, but always in the thickness of its walls, these arterioles pass out again to be distributed as very minute branches in the surrounding red pulp : in fact, the ultimate termination of all the finest penicellate arteries is in this red substance. From all this I have become convinced that the white bodies, as mere outgrowths of the tunicœ adventitiæ, have no relation with the finest ramifications of the arteries.”
On the theory of the illumination of objects under the microscope, with relation to the aperture of the object-glass, and properties of light ; with practical methods for special differences of texture and colour
Authors: Wenham F. H.
Published: April 2021

Having on a former occasion written a paper published in the ‘Transactions of the Microscopic Society for March, 1850,’ entitled, “On the Illumination of Transparent Microscopic Objects on a new Principle,” I should deem it an intrusion for again appearing on the same ground were it not for the reason that I have since that time effected some improvements, and it has become evident that the theory of the subject was too briefly explained in my first communication to give a general idea of my meaning in the way that I had wished to be understood. As I have no predilection for a theory that does not bear upon a practical result, in that which I bring forward I shall endeavour as much as possible to support it by experimental facts.
On the development of starch
Authors: Crüger H.
Published: April 2021

The following observations, the result of lengthened investigations, relate principally to the history of the development of the starch granule, a subject which appears to have been, hitherto, but little studied.
On the Aperture of Object-Glasses
Authors: Wenham F. H.
Published: April 2021

In the ‘Quarterly Journal of Microscopical Science,’ for Jan. 1854, I described a method of measuring the angular aperture of object-glasses (which had previously been made use of by Professor Amici). Since that time there has been some discussion in relation to this subject, and as the plan that I proposed has been somewhat misunderstood, I will offer some further explanation.
The Microscope, and its application to Clinical Medicine
Authors: Beale Lionel
Published: April 2021

We suppose at the present day that there are few properly-educated medical men who would deny the value of the stethoscope as a means of ascertaining the presence of disease. The man who would be hardy enough to forego its use would run the hazard of even popular neglect for his temerity. This is not, perhaps, the case at present with the microscope, but we feel sure that whatever argument could be advanced in favour of the stethoscope, as a means of diagnosis, might be urged with tenfold force in favour of the microscope. The stethoscope, in fact, only facilitates the use of the organ of hearing; whilst the microscope widens and extends the power of vision, and creates a new world of observation. By it that which the unaided mind could only imagine, or vaguely indicate, as a probable existence, is demonstrated, and the structure, which was a puzzle and a mystery, becomes perfectly understood. This instrument has now become a necessity for the anatomist and physiologist ; no structure can be truly investigated, no function perfectly understood, without its aid. If, therefore, a knowledge of disease can only be obtained by a knowledge of the structure and functions of the body in health, it is necessary that those who undertake to treat disease should be conversant with the results of microscopic research. The microscope, in fact, should be put into the hands of every medical student, and he should be expected to be as well acquainted with the results of its use as he is of the scalpel, the test-tube, the stethoscope, or any other means of investigation. We fear this is not the case, and that many a young man passes his medical curriculum without even the inquiry being made as to whether he is acquainted with the powers of this mighty instrument of research. We are glad, however, to find that the means of microscopic instruction are multiplying. In many of our medical schools demonstrations with the microscope are given, our medical journals devote some portion of their space to micrological discussions, and here we have a professor in one of our metropolitan medical colleges, writing a book on the microscope especially adapted for medical students. We give Dr. Beale’s remarks on the value of the microscope as a means of diagnosis, entire.
Observations on Noctiluca (miliaris ?)
Authors: Busch Dr. W.
Published: April 2021

The following observations upon the structure and reproduction of a species of Noctiluca were made by Dr. Busch in the year 1849, and will be found in his work cited below, which was published in 1851. With respect to the structure of the animal, they perhaps present nothing in addition to what has already been made known to our readers in the Papers by Mr. Huxley and by Dr. Webb, in the present Volume of the ‘ Journal ;’ but as regards the reproduction and development of the Noctiluca, they afford several new points, and it is for that reason that we have thought it might be useful here to introduce them, and the more so, as it would seem these remarks by Dr. Busch had escaped the notice of Krohn, † as well as of Mr. Huxley ‡ and Dr. Webb.§ The species noticed by Dr. Busch occurred in great abundance in the Bay of Malaga, and is regarded by him, but we think, perhaps, erroneously, as distinct from N. miliaris. He terms it N. punctata, from the circumstance that the integument was covered with very numerous minute pigment-points; but the resemblance of his figure to N. miliaris is so striking, and the structure, so far as he describes it, so closely identical with that of the latter, that no doubt can be entertained as to the identity of the two forms.
On the Filamentous, Long-Horned Diatomaceæ, with a description of two new species
Authors: Brightwell Thomas
Published: April 2021

In a gathering of Diatomaceæ, made by the late Mr. Wigham in July 1854, on the borders of the salt-water estuary, called Breydon, near Yarmouth, a singular filamentous, horned species was detected, allied to the genus Chœtoceros of Ehrenberg.