bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic morphology of metastatic mouse T‐lymphoma cells invading through monolayers of 10T½ cells
Authors: Verschueren Hendrik , De Baetselier Patrick , Bereiter‐Hahn Jürgen 
Published: February 2005

AbstractWe have used an in vitro model system to analyze cytomechanical aspects of tissue infiltration by T‐lymphocytes. The interaction of metastatic T‐lymphoma cells with a precultured monolayer of 10T½ fibroblast‐like cells was recorded in time‐lapse video with alternating phase contrast and reflection interference contrast microscopy. Sectioning of embedded specimens as well as cytoskeletal stainings have been performed on matching cocultures.The lymphoma cells did not strongly attach or spread on the dorsal surface of the monolayer cells. Invasion started with the protrusion of a pseudopodium through a narrow gap, and conspicious constriction of the invading cell's body and nucleus was a consistent feature during the later steps. Overt retraction of the target cells was not seen, but the invading lymphoma cells elevated the fibroblasts over relatively large areas, thereby creating dome‐shaped open spaces, allowing for further migration under the monolayer with minimal resistance. Invasion was not unidirectional but was readily reversible at any stage. Due to this wavering character, an invasion event could take more than 1 hour, although the shape alterations involved were fast. Even after the invasion process had been completed, the lymphoma cells could come out from below the monolayer again. Therefore we propose that invasion in this model should be considered as a dynamic equilibrium.Invading T‐lymphoma cells displayed diffuse F‐actin staining and a well‐organized microtubular complex with the centrosomes behind the nucleus in the uropod, which also contained most vesicular organelles.
The redeployment of F‐actin in silk glands during moulting
Authors: Henderson Scott C. , Locke Michael 
Published: February 2005

AbstractLabeling of silk glands with rhodaminyl‐phalloin shows that most F‐actin is restricted to parallel bundles that form rings around the gland lumen at the apical cell surface. The bundles are lost when larval feeding stops at moulting, and the F‐actin is redistributed through the cytoplasm as coats to vacuoles and, occasionally, in variably oriented strands. After moulting there is a return to the distribution of filamentous actin in the apical periluminal rings of bundles. These events occur at the same time as F‐actin in the nuclear shell [Henderson and Locke, submitted] undergoes its own set of changes. In silk gland cells two kinds of f‐actin deployment take place concurrently.
Incorporation of fluorescently labeled contractile proteins into freshly isolated living adult cardiac myocytes
Authors: Lorusso Stephen M. , Imanaka‐Yoshida Kyoko , Shuman Henry , Sanger Jean M. , Sanger Joseph W. 
Published: February 2005

AbstractWhen fluorescently labeled contractile proteins are injected into embryonic muscle cells, they become incorporated into the cells' myofibrils. In order to determine if this exchange of proteins is unique to the embryonic stage of development, we isolated adult cardiac myocytes and microinjected them with fluorescently labeled actin, myosin light chains, α‐actinin, and vinculin. Each of these proteins was incorporated into the adult cardiomyocytes and was colocalized with the cells'native proteins, despite the fact that the labeled proteins were prepared from noncardiac tissues. Within 10 min of injection, α‐actinin was incorporated into Z‐bands surrounding the site of injection. Similarly, 30 sec after injection, actin was incorporated into the entire I‐bands at the site of injection. Following a 3‐h incubation, increased actin fluorescence was noted at the intercalated disc. Vinculin exchange was seen in the intercalated discs, as well as in the Z‐bands throug hout the cells. Myosin light chains required 4–6 h after injection to become incorporated into the A‐bands of the adult muscle. Nonspecific proteins, such as fluorescent BSA, showed no association with the myofibrils or the former intercalated discs. When adult cells were maintained in culture for 10 days, they retain the ability to incorporate these contractile proteins into their myofibrils. T‐tubules and the sarcoplasmic reticulum could be detected in periodic arrays in the freshly isolated cells using the membrane dye WW781 and DiOC3[3], respectively. In conclusion, the myofibrils in adult, as in embryonic, muscle cells are dynamic structures, permitting isoform transitions without dismantling of the myofibrils.
Cytokinesis is more rapid in Ha‐T24‐ras transfected rat embryo fibroblasts than in non‐transfected control cells
Authors: Ng Grace , Boylan John , Zimmer Stephen G. , Sisken Jesse E. 
Published: February 2005

AbstractIt has long been known that neoplastic cells are characterized by increases in cell motility. Earlier studies from this laboratory indicated that rnitotic events were also altered in many tumor and experimentally transformed cells and that this included increases in metaphase duration and a reduction in the duration of cytokinesis. The studies presented in this paper were done to determine whether or not transfection of normal rat embryo fibroblasts by the Ha‐T24‐ras oncogene could also produce such alterations in mitotic events. The results obtained with the use of time lapse video microscopy indicate that neither the duration of metaphase nor the rate of chromosome movement during anaphase was altered but that the rate of furrow progression during cytokinesis occurred at a significantly more rapid rate. Thus, the cellular alteratioons induced by transfection with Ha‐T24‐ras accelerate microfilament‐dependent cytokinetic furrowing without significant effects on microtubule‐dependent mitotic events. One of several possible mechanisms that could account for these observations involves a down regulation of protein kinase C which has been reported to occur in many neoplastic cells including those transformed by ras. Such a hypothesis could also have broader implications because it may be applicable to the increase in motility and metastatic activity generally observed in transformed cells.
Reversible intracellular ATP changes in intact rat spermatozoa and effects on flagellar sperm movement
Authors: Jeulin Claudette , Soufir Jean‐Claude 
Published: February 2005

AbstractThe initiation of motility and modification of energy metabolism of rat caudal epididymal spermatozoa can be induced by dilution in a saline medium. We have investigated in these cells the relationships between the energy reserve (sperm ATP content measured by bioluminescence) and flagellar movement (high speed videomicrography, 200 frames/sec). A steady state was observed in sperm ATP content, progressive velocity (Vp) and flagellar beat frequence (F) with sperm dilution in a medium with glucose, lactate, pyruvate and acetate substrates after 30 minutes of incubation, without these substrates, changes in metabolic pathways occurred immediately and initially disturbed the relationship between ATP levels and F, suggesting differences in motility initiation when energy is from an endogenous origin via mitochondrial oxidative phosphorylation. This “energy crisis” was reversed by the addition of substrates to the medium.The three‐dimensional flagellar movement observed in the presence of substrates quickly became two‐dimensional in their absence. The flagellar beat envelope became more splayed, the mean amplitude of lateral head displacement increased and F decreased. The resulting high flagellar beat efficiency can be compared to that observed during hyperactivation which is a physiological event related to a fall in intracellular ATP level. In both media, the displacement of the flagellum in relation to the wave axis varied sinusoidally. The sine period increased with time when the spermatozoa were incubated in the medium without substrates. These results suggest a gradual slowing‐down of the velocity of wave formation in the proximal part of the flagellum.
Actin‐dependent myoid elongation in teleost rod inner/outer segments occurs in the absence of net actin polymerization
Authors: Pagh‐Roehl Kathryn , Brandenburger J. , Wang E. , Burnside B. 
Published: February 2005

AbstractIn the retinas of teleost fish, rod photoreceptors elongate in response to light. Light‐activated elongation is mediated by the myoid of the rod inner segment and is actin‐dependent. Inner segment F‐actin filaments form bundles running parallel to the cell's long axis. We examined the mechanism of rod elongation using mechanically‐detached rod fragments, consisting of the motile inner segment and sensory outer segment (RIS‐ROS). When RIS‐ROS are isolated from darkadapted green sunfish and cultured in the light, they elongate 15μm at 0.3–0.6μm/min. Elongation was inhibited 65% by 0.1μM Cytochalasin D, suggesting a requirement for actin assembly. To determine the extent of assembly during elongation, we used three approaches to measure the F‐actin content in RIS‐ROS: detection of pelletable actin by SDS‐PAGE after detergent‐extraction of RIS‐ROS; quantification of fluorescein‐phalloidin binding by fluorimetry, fluorescence‐activated cell sorting and image analysis; estimation of total F‐actin filament length by electron microscopy. All three assays indicated that no net assembly of RIS‐ROS F‐actin accompanied myoid elongation. An increase in F‐actin content within the elongated myoid was counterbalanced by a decrease in F‐actin content within the 13 microvillus‐like calycal processes located at the end of the inner segment opposite to the growing myoid. O'Connor and Burnside (Journal of Cell Biology 89:517–524, 1981) showed that minus‐ends of rod F‐actin filaments are oriented towards the elongating myoid while plus‐ends are oriented towards the shortening calycal processes. Our observations suggest that RIS‐ROS elongation entails actin polymerization at the minus‐ends of filaments coupled with depolymerization at the filament plus‐ends.
Two distinct isoforms of sea urchin egg dynein
Authors: Grissom Paula M. , Porter Mary E. , McIntosh J. Richard 
Published: February 2005

AbstractExtracts of unfertilized sea urchin eggs contain at least two isoforms of cytoplasmic dynein. One exhibits a weak affinity for microtubules and is primarily soluble. The other isoform, HMr‐3, binds to microtubules in an ATP‐sensitive manner, but is immunologically distinct from the soluble egg dynein (Porter et al.: Journal of Biological Chemistry 263:6759–6771, 1988). We have now further distinguished these egg dynein isoforms based on differences in NTPase activity. HMr‐3 copurifies with NTPase activity, but it hydrolyzes CTP at 10 times the rate of ATP. The soluble egg dynein is similar to flagellar dynein in its nucleotide specificity; its MgCTPase activity is ca. 60% of its MgATPase activity. Non‐ionic detergents and salt activate the MgATPase activities of both enzymes relative to their MgCTPase activities, but this effect is more pronounced for the soluble egg dynein than for HMr‐3. Sucrose gradient‐purified HMr‐3 promotes an ATP‐sensitive microtubule bundling, as seen with darkfield optics. We have also isolated a 20 S microtubule translocating activity by sucrose gradient fractionation of egg extracts, followed by microtubule affinity and ATP release. This 20 S fraction, which contains the HMr‐3 isoform, induces a microtubule gliding activity that is distinct from kinesin. Our observations suggest that soluble dynein resembles axonemal dynein, but that HMr‐3 is related to the dynein‐like enzymes isolated from a variety of cell types and may represent the cytoplasmic dynein of sea urchin eggs.
Intracellular cyclic AMP produces effects opposite to those of cyclic GMP and calcium on shape and motility of neuroblastoma cells
Authors: Bolsover Stephen R. , Gilbert Susan H. , Spector Ilan 
Published: February 2005

AbstractWe have directly evaluated the effects of various intracellular second messengers including cyclic nucleotides, calcium ion, and inositol polyphosphates on shape and motility of differentiating mouse neuroblastoma cells. The messengers were microinjected into cells and the responses of the soma, neurite, and growth cone were monitored using time‐lapse video microscopy. Each messenger altered cell shape and motility in a characteristic manner. Cyclic AMP promoted lamellipodial expansion, neurite outgrowth, and motility. The other injected messengers opposed motility. Cyclic GMP caused motile structures to freeze and to retract permanently, while the inhibitory effects of calcium injection were concentrationdependent. Small calcium injections affected specifically actincontaining motile structures which froze and retracted temporarily. Intermediate calcium injections caused a strong contraction at the site of injection in all cells. With large injections, cells retracted long neurites, rounded up, and frequently began vigorous blebbing that continued to cell death. Injections of the inositol polyphosphates 1P3(1,4,5) and IP4(1,4,5,6) mimicked the effects of small calcium injections, as did electrical stimulation that elicited action potentials. The results suggest that in mouse neuroblastoma cells, intracellular CAMP elevation increases cytoskeletal organization and promotes neurite extension perhaps through an enhancement of cell‐substratum adhesion. On the other hand, a rise of intracellular cGMP or intracellular calcium interferes directly with the function and organization of the actin‐microfilament system. The integrated action of these second messenger systems may, therefore, operate in vivo to allow substances released from neighboring cells to regulate neuronal architecture. © 1992 Wiley‐Liss, Inc.
Overexpression of vinculin suppresses cell motility in BALB/c 3T3 cells
Authors: Fernández José Luis Rodríguez , Geiger Benjamin , Salomon Daniela , Ben‐Ze'ev Avri 
Published: February 2005

AbstractThe content of vinculin, a cytoplasmic protein found in focal contacts and cell‐cell junctions, was increased in BALB/c 3T3 cells by gene transfection. The vinculin expressed from the full length chicken cDNA, incorporated into focal contacts and its pattern was identical to that of the endogenous protein. Cells stably expressing vinculin by 20% over the endogenous level had altered locomotory properties. In these cells, the ability to migrate into a wound formed in a confluent monolayer and the locomotion of individual cells were drastically reduced. The results provide direct evidence that cell locomotion can be regulated by modulating vinculin expression. © 1992 Wiley‐Liss, Inc.
Immunohistochemical studies on the distribution of cellular myosin II isoforms in brain and aorta
Authors: Murakami Noriko , Elzinga Marshall 
Published: February 2005

AbstractThe distribution of nonmuscle myosin isoforms in brain and aorta was studied by using polyclonal antibodies against two synthetic peptides selected from a region near the carboxyl terminus of bovine brain (peptide IIB) and human macrophage (peptide IIA) myosin. Immunoblots of brain homogenates and purified myosin showed two major bands stained by anti‐peptide IIB (MIIB1 and MIIB2) and a minor band stained by anti‐peptide IIA (MIIA2). Polyclonal anti‐human platelet myosin antibodies did not react with MIIB isoforms. In cryosections from bovine, rat, and mouse brains, anti‐peptide IIB stained most neuronal cells. In bovine cryosections, glial staining was also observed. In contrast, anti‐peptide IIA and anti‐platelet myosin antibodies primarily stained blood vessels. In bovine aorta, the anti‐peptide antibodies recognized four bands, MIIB3, MIIB4, MIIA1, and MIIA2. Only MIIA2 was recognized by anti‐human platelet myosin antibodies. In bovine aorta cryosections, anti‐peptide IIB stained smooth muscle cells in tunica intima and tunica media but did not stain endothelial cells. Anti‐peptide IIA stained smooth muscle cells in the tunica media, and endothelial cells of vaso vasorum but not of aorta. Only polyclonal anti‐platelet myosin antibodies stained the endothelial cells of aorta tunica intima. These results indicate that multiple isoforms of cellular myosins exist in mammals, that these isoforms are expressed in a cell specific manner, and that the major myosin isoforms isolated from whole brain originate from neurons and, at least in bovine brain, from glia, but not from blood vessels. © 1992 Wiley‐Liss, Inc.
Mechanics of the chloroplast rotation in Mougeotia: Measurement of angular velocity by laser diffractometry
Authors: Ytow Nozomi , Yamada Toru , Ishizaka Shozo 
Published: February 2005

AbstractThe cell of the green alga Mougeotia orients its chloroplast by rotation, according to the direction or polarization of incident red light. The mechanics of the rotation is described by the angle of rotation and the angular velocity of the rotator (i.e., the chloroplast). We developed a laser diffractometer to determine the angle of rotation of the chloroplast. The angle of rotation of the chloroplast shifted by a constant angular velocity, and hence, the net torque on the chloroplast was zero. This suggests that the driving torque acting on the chloroplast is always balanced by the viscous torque. The maximal driving force acting on the chloroplast was estimated to be nearly equal to the force generated by an actomyosin system. This is the first measurement of the driving force acting on the chloroplast in Mougeotia. The amplitude of the force supported the anchorage site hypothesis. However, it remains unclear whether or not the angular independence of the force also supports the hypothesis. © 1992 Wiley‐Liss, Inc.
240 kDa immunoanalogue of vertebrate α‐spectrin occurs in Paramecium cells
Authors: Kwiatkowska Katarzyna , Sobota Andrzej 
Published: February 2005

AbstractPolypeptide of 240 kDa immunorelated to vertebrate α‐spectrin was detected in Paramecium cells. The antigen was identified by monospecific antibody directed against α‐subunit of spectrin, which was isolated from chicken erythrocytes by affinity and anion‐exchange chromatography. Immunoblotting tests demonstrated that the anti‐α‐spectrin cross reacted with the 240 kDa polypeptide of Paramecium as well as that of various vertebrate cells. In Paramecium, the antigen was detected in cytoskeletal fraction and in contractile extract of the cells. Immuno‐fluorescent and immunoelectron microscopy observations revealed cortical localization of α‐spectrin immunoanalogue in Paramecium. The label was distinctly seen on the whole surface of trichocyst tips. The antigen was also distributed close to the inner alveolar membrane forming a regular, continuous, lattice‐like structure. When stained with rhodamine‐phalloidin, Paramecium cells displayed a similar fluorescent network, which underlay contours of cortical units. Basal bodies of cilia were labeled with phalloidin as well. Detection of α‐spectrin immunoanalogue in Paramecium cortex may provide a new insight into arrangement of cortical elements in this organism. © 1992 Wiley‐Liss, Inc.
A shell of F‐actin surrounds the branched nuclei of silk gland cells
Authors: Henderson Scott C. , Locke Michael 
Published: February 2005

AbstractThe branched nuclei from silk gland cells of larvae of Calpodes ethlius label with antibodies to actin and myosin and with rhodaminyl‐phalloin, which is specific for f‐actin. Optical sectioning localizes this actin and myosin to the nuclear periphery. Residual nuclear‐associated fractions prepared from these cells contain sheets of nuclear lamina‐like structures that bind heavy meromyosin and gold‐tagged antibodies to actin and myosin. The results suggest that both actin and myosin, or a myosin‐like protein, are components of a layer at the nucleocytoplasmic boundary that we call the nuclear shell. The nuclear shell appears to be associated with the nuclear envelope and may correspond to a zone on the cytoplasmic face of the envelope seen in electron micrographs of unextracted cells. The residual nuclear‐associated fraction has a unique isoform of actin (43 kD, pl 6.45) that might allow the nuclei to associate with an actin network structurally and developmentally distinct from that of the cytoplasm. © 1992 Wiley‐Liss, Inc.
Immunological comparison of 22S, 19S, and 12S dyneins from Paramecium cilia
Authors: Walczak Claire E. , Marchese‐Ragona Silvio P. , Nelson David L. 
Published: February 2005

AbstractThree forms of dynein (22S, 19S, and 12S) were purified from Paramecium cilia. Two classes of monoclonal antibodies against purified 22S dynein were generated. One class reacted on immunoblots with the heavy chains of 22S, 19S, and 12S dyneins; the second class reacted with an 88 kD intermediate chain of 22S dynein. Polyclonal antiserum to the heavy chains of 22S dynein reacted with the γ‐heavy chain of 22S and 19S dyneins. A previously described antiserum raised against 22S dynein [Travis et al.: Biochim. Biophys. Acta 966:73–83, 1988] recognized the γ‐heavy chain of 22S dynein which was also present in 19S and 12S dyneins, along with the 88 and 76 kD intermediate chains of 22S dynein. This antiserum was also able to immunoprecipitate dynein from crude extracts of cilia.Electron microscopy revealed that the 22S dynein consisted mainly of two‐headed particles with some three‐headed particles present. The 12S dynein was mainly one‐headed particles. The 19S dynein was a mixture of three‐, two‐, and one‐headed particles. The immunological and electron microscopic studies showed that 19S dynein arises from 22S dynein, and that 12S dynein is heterogeneous, composed of the γ‐heavy chain of 22S dynein and a unique dynein ATPase.The polyclonal antibodies were also used to detect cross‐reactive proteins in other organisms. Both the anti‐heavy chain and the anti‐22S dynein sera reacted strongly with 22S outer arm dynein of Tetrahymena, but not with the 14S dynein of this organism. © 1993 Wiley‐Liss, Inc.
Ciliary dynein of Paramecium tetraurelia: Photolytic maps of the three heavy chains
Authors: Beckwith Susan M. , Asai David J. 
Published: February 2005

AbstractThe ciliate Paramecium tetraurelia presents a powerful system to define the structural basis for dynein functional diversity within a single cell. This analysis will depend on the biochemical resolution of the dynein proteins. As an important first step, the three heavy chains of the ciliary outer arm dynein of paramecium were characterized. Sucrose density gradient centrifugation in a high salt buffer separated the dynein into a 22S species, which contained the α and β heavy chains, and a 12S species, which contained the α chain as well as the inner arm dynein heavy chains. Both the 22S and 12S species retained enzymatic latency as indicated by stimulation of MgATPase activity by 0.1% Triton X‐100. An unusual ATP‐independent V1‐like photolysis of only the β chain provided the basis for estimating that the β chain contributes almost half of the 22S MgATPase activity that is susceptible to V1 photolysis. The combination of the density gradient separation of the partially dissociated dynein and the ATP‐independent V1‐like photolysis of only the β chain led to the unambiguous assignment of the V1 photolytic products to the appropriate parent heavy chains. An estimate of the molecular sizes of the three heavy chains was obtained. The photolytic peptide maps, which define the ATP‐binding domains, were determined for the three heavy chains. © 1993 Wiley‐Liss, Inc.