bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytoskeletal structure of myoblasts with the mitochondrial DNA 3243A→G mutation and of osteosarcoma cells with respiratory chain deficiency
Authors: Rusanen Harri , Annunen Johanna , Ylä‐Outinen Heli , Laurila Aino , Peltonen Juha , Hassinen Ilmo E. , Majamaa Kari 
Published: September 2002

AbstractThe cytoskeleton, mainly composed of actin filaments, microtubules, and intermediate filaments, is involved in cell proliferation, the maintenance of cell shape, and the formation of cellular junctions. The organization of the intermediate filaments is regulated by phosphorylation and dephosphorylation. We examined cell population growth, apoptotic cell death, and the morphology of cytoskeletal components in myoblast cultures derived from patients with the 3243A→G mutation in mitochondrial DNA (mtDNA) and from control subjects by means of assays detecting cellular nucleic acids, histone‐associated DNA fragments and by immunolabeling of cytoskeletal components. Population growth was slower in the 3243A→G myoblast cultures, with no difference in the amount of apoptotic cell death. The organization of vimentin filaments in myoblasts with 3243A→G was disturbed by randomization of filament direction and length, whereas no disturbances were observed in the other cytoskeletal proteins. Vimentin filaments formed large bundles surrounding the nucleus in mtDNA‐less (ρ0) osteosarcoma cells and in osteosarcoma cells after incubation with sodium azide and nocodazole. We conclude that defects in oxidative phosphorylation lead to selective disruption of the vimentin network, which may have a role in the pathophysiology of mitochondrial diseases. Cell Motil. Cytoskeleton 53:231–238, 2002. © 2002 Wiley‐Liss, Inc.
Computer simulation of flagellar movement VIII: Coordination of dynein by local curvature control can generate helical bending waves
Authors: Brokaw Charles J. 
Published: September 2002

AbstractComputer simulations have been carried out with a model flagellum that can bend in three dimensions. A pattern of dynein activation in which regions of dynein activity propagate along each doublet, with a phase shift of approximately 1/9 wavelength between adjacent doublets, will produce a helical bending wave. This pattern can be termed “doublet metachronism.” The simulations show that doublet metachronism can arise spontaneously in a model axoneme in which activation of dyneins is controlled locally by the curvature of each outer doublet microtubule. In this model, dyneins operate both as sensors of curvature and as motors. Doublet metachronism and the chirality of the resulting helical bending pattern are regulated by the angular difference between the direction of the moment and sliding produced by dyneins on a doublet and the direction of the controlling curvature for that doublet. A flagellum that is generating a helical bending wave experiences twisting moments when it moves against external viscous resistance. At high viscosities, helical bending will be significantly modified by twist unless the twist resistance is greater than previously estimated. Spontaneous doublet metachronism must be modified or overridden in order for a flagellum to generate the planar bending waves that are required for efficient propulsion of spermatozoa. Planar bending can be achieved with the three‐dimensional flagellar model by appropriate specification of the direction of the controlling curvature for each doublet. However, experimental observations indicate that this “hard‐wired” solution is not appropriate for real flagella. Cell Motil. Cytoskeleton 53:103–124, 2002. © 2002 Wiley‐Liss, Inc.
Myosin II dynamics in Dictyostelium: Determinants for filament assembly and translocation to the cell cortex during chemoattractant responses
Authors: Levi Stephanie , Polyakov Mark V. , Egelhoff Thomas T. 
Published: September 2002

AbstractIn the simple amoeba Dictyostelium discoideum, myosin II filament assembly is regulated primarily by the action of a set of myosin heavy chain (MHC) kinases and by MHC phosphatase activity. Chemoattractant signals acting via G‐protein coupled receptors lead to rapid recruitment of myosin II to the cell cortex, but the structural determinants on myosin necessary for translocation and the second messengers upstream of MHC kinases and phosphatases are not well understood. We report here the use of GFP‐myosin II fusions to characterize the domains necessary for myosin II filament assembly and cytoskeletal recruitment during responses to global stimulation with the developmental chemoattractant cAMP. Analysis performed with GFP‐myosin fusions, and with latrunculin A–treated cells, demonstrated that F‐actin binding via the myosin motor domain together with concomitant filament assembly mediates the rapid cortical translocation observed in response to chemoattractant stimulation. A “headless” GFP‐myosin construct lacking the motor domain was unable to translocate to the cell cortex in response to chemoattractant stimulation, suggesting that myosin motor‐based motility may drive translocation. This lack of localization contrasts with previous work demonstrating accumulation of the same construct in the cleavage furrow of dividing cells, suggesting that recruitment signals and interactions during cytokinesis differ from those during chemoattractant responses. Evaluating upstream signaling, we find that iplA null mutants, devoid of regulated calcium fluxes during chemoattractant stimulation, display full normal chemoattractant‐stimulated myosin assembly and translocation. These results indicate that calcium transients are not necessary for chemoattractant‐regulated myosin II filament assembly and translocation. Cell Motil. Cytoskeleton 53:177–188, 2002. © 2002 Wiley‐Liss, Inc.
Reorganization and translocation of the ectoplasmic cytoskeleton in the leech zygote by condensation of cytasters and interactions of dynamic microtubules and actin filaments
Authors: Fernández Juan , Cantillana Viviana , Ubilla Andrea 
Published: September 2002

AbstractThe formation and bipolar translocation of an ectoplasmic cytoskeleton of rings and meridional bands was studied in interphase zygotes of the glossiphoniid leech Theromyzon trizonare. Zygotes consisted of a peripheral organelle‐rich ectoplasm and an internal yolk‐rich endoplasm. After microinjection of labeled tubulin and/or actin, zygotes were examined by time‐lapse video imaging, immunofluorescence and confocal microscopy. The rings and meridional bands were formed by condensation of a network of moving cytasters that represented ectoplasmic secondary centers of microtubule and actin filament nucleation. In some cases the network of cytasters persisted between the rings. The cytoskeleton had an outer actin layer and an inner microtubule layer that merged at the irregularly‐shaped boundary zone. Bipolar translocation of the rings, meridional bands, or the network of cytasters led to accumulation of the cytoskeleton at both zygote poles. Translocation of the cytoskeleton was slowed or arrested by microinjected taxol or phalloidin, in a dose‐dependent fashion. Results of drug treatment probably indicate differences in the degree and speed at which the cytoskeleton becomes stabilized. Moreover, drugs that selectively stabilized either microtubules or actin filaments stabilized and impaired movement of the entire cytoskeleton. Microtubule poisons and latrunculin‐B failed to disrupt the cytoskeleton. It is concluded that the microtubule and actin cytoskeletons are dynamic, presumably cross‐linked and resistant to depolymerizing drugs. They probably move along each other by a sliding mechanism that depends on the instability of microtubules and actin filaments. Cell Motil. Cytoskeleton 53:214–230, 2002. © 2002 Wiley‐Liss, Inc.
Embryonic wound healing by apical contraction and ingression in Xenopus laevis
Authors: Davidson Lance A. , Ezin Akouavi M. , Keller Ray 
Published: September 2002

AbstractWe have characterized excisional wounds in the animal cap of early embryos of the frog Xenopus laevis and found that these wounds close accompanied by three distinct processes: (1) the assembly of an actin purse‐string in the epithelial cells at the wound margin, (2) contraction and ingression of exposed deep cells, and (3) protrusive activity of epithelial cells at the margin. Microsurgical manipulation allowing fine control over the area and depth of the wound combined with videomicroscopy and confocal analysis enabled us to describe the kinematics and challenge the mechanics of the closing wound. Full closure typically occurs only when the deep, mesenchymal cell‐layer of the ectoderm is left intact; in contrast, when deep cells are removed along with the superficial, epithelial cell‐layer of the ectoderm, wounds do not close. Actin localizes to the superficial epithelial cell‐layer at the wound margin immediately after wounding and forms a contiguous “purse‐string” in those cells within 15 min. However, manipulation and closure kinematics of shaped wounds and microsurgical cuts made through the purse‐string rule out a major force‐generating role for the purse‐string. Further analysis of the cell behaviors within the wound show that deep, mesenchymal cells contract their apical surfaces and ingress from the exposed surface. High resolution time‐lapse sequences of cells at the leading edge of the wound show that these cells undergo protrusive activity only during the final phases of wound closure as the ectoderm reseals. We propose that assembly of the actin purse‐string works to organize and maintain the epithelial sheet at the wound margin, that contraction and ingression of deep cells pulls the wound margins together, and that protrusive activity of epithelial cells at the wound margin reseals the ectoderm and re‐establishes tissue integrity during wound healing in the Xenopus embryonic ectoderm. Cell Motil. Cytoskeleton 53:163–176, 2002. © 2002 Wiley‐Liss, Inc.
Large‐scale morphological survey of mouse retinal ganglion cells
Authors: Sun Wenzhi , Li Ning , He Shigang 
Published: September 2002

AbstractFive hundred twenty ganglion cells in an isolated whole‐mount preparation of the mouse retina were labeled using the “DiOlistic” method (Gan et al. [2000] Neuron 27:219–225) and were classified according to their morphological properties. Tungsten particles coated with a lipophilic dye (DiI) were propelled into the whole‐mount retina using a gene gun. When a dye‐coated particle contacted the cell membrane, the entire cell was labeled. The ganglion cells were classified into four groups based on their soma size, dendritic field size, and pattern and level of stratification. Broadly monostratified cells were classified into three groups: RGA cells (large soma, large dendritic field), RGB cells (small to medium‐sized soma, small to medium‐sized dendritic field), and RGC cells (small to medium‐sized size soma, medium‐sized to large dendritic field). Bistratified cells were classified as RGD. This study represents the most complete morphological classification of mouse retinal ganglion cells available to date and provides a foundation for further understanding of the correlation of physiology and morphology and ganglion cell function with genetically manipulated animals. J. Comp. Neurol. 451:115–126, 2002. © 2002 Wiley‐Liss, Inc.
Characterization of the optic nerve and retinal ganglion cell layer in the dysmyelinated adult Long Evans Shaker rat: Evidence for axonal sprouting
Authors: Phokeo Vinay , Kwiecien Jacek M. , Ball Alexander K. 
Published: September 2002

AbstractMyelin in the central nervous system (CNS) is hypothesized to help guide the growth of developing axons by inhibiting sprouting of aberrant neurites. Previous studies using animal models lacking CNS myelin have reported that increasing capacity for sprouting axons is negatively correlated with the degree of myelination. In the present study, we investigated the optic nerves of the recently identified Long Evans Shaker (LES) rat with prolonged dysmyelination of adult axons to determine whether the lack of myelin basic protein (MBP) in adult LES rats could manifest as increases in the population of CNS axons. We observed numerous small, unmyelinated axon profiles (<0.3 μm in diameter) clustered in bundles alongside normal caliber axons in dysmyelinated LES rats but not in normal myelinated Long Evans (LE) rats. These putative axon profiles resembled sprouting axons previously described in the CNS. Moreover, the high number of small putative axon profiles could not be accounted for by any significant increases in the number of ganglion cells and displaced amacrine cells in the ganglion cell layer when compared with normal rats as evaluated by using a variety of techniques. This finding suggests that the observed clusters of putative axon profiles were not due to developmental abnormalities in the retina but to the lack of myelin in the optic nerves of LES rats. The adult LES rat, therefore, may serve as a useful model to study the role of myelin in regulating axon development or axon regeneration after CNS injury in the adult mammalian system. J. Comp. Neurol. 451:213–224, 2002. © 2002 Wiley‐Liss, Inc.
Mitotic activation of proliferative cells in the inner nuclear layer of the mature fish retina: Regulatory signals and molecular markers
Authors: Faillace Maria Paula , Julian David , Korenbrot Juan I. 
Published: September 2002

AbstractNew neurons continuously differentiate within the otherwise mature retina of teleost fish, both under normal conditions and in response to injury. We investigated the effects of surgical injury and intraocular injection of neurotrophic factors on the mitotic rate of proliferative inner nuclear layer cells (PINC). PINC are continually born in the inner nuclear layer and then migrate to the outer nuclear layer (ONL). Surgical excision of a part of a retina activates PINC mitotic activity near and far from the lesion. In the injured eye, up‐regulation of PINC cells is largest in the dorsonasal sector of the retina, regardless of the site of lesion. Up‐regulation extends even to the unlesioned contralateral eye, where it occurs in the same dorsonasal sector. Intraocular injection of ciliary neurotrophic factor mimics the effect of injury on PINC in the treated eye but not on the untreated contralateral retina. We searched for the expression in PINC of Pax6, a transcription factor linked to retinal progenitor cells and found that less than 0.5% of all PINC cells express it. Importantly, the number of Pax6‐expressing PINC does not change significantly in the retinas subjected to any of the experimental manipulations tested. Under normal conditions, the default fate of PINC cells is to migrate to the ONL and, likely, replenish the rod progenitor pool. PINC respond to injury (both surgical and light‐dependent) by increasing their mitotic rate; this increase is long lived, but there are no changes in the expression level of Pax6. PINC probably are a heterogenous cell population that can be specified for ultimate, different purposes: creating rod precursors, creating founder cells, creating cone precursors. Several fates are recognized now, but others may also be possible. J. Comp. Neurol. 451:127–141, 2002. © 2002 Wiley‐Liss, Inc.
Some observations on cortical inputs to the macaque monkey amygdala: An anterograde tracing study
Authors: Stefanacci Lisa , Amaral David G. 
Published: September 2002

AbstractWe have previously described the origins of neocortical inputs to the lateral nucleus of the macaque monkey amygdala based on retrograde tracing studies. Here we report results from studies that have attempted to confirm the projections from several candidate afferent regions using3H‐amino acid autoradiography as an anterograde tracer. We have charted, based on the results of 33 separate injections, the topographic distribution of cortical projections throughout the amygdala. Areas TE and TEO of the inferotemporal cortex, portions of the superior temporal gyrus, and the granular region of the insula project primarily to the lateral nucleus, with little or no innervation of other amygdaloid nuclei. In contrast, orbitofrontal, medial prefrontal, and anterior cingulate regions project primarily to the basal and accessory basal nuclei and provide little innervation to the lateral nucleus. The orbitofrontal and medial prefrontal cortices, but not the anterior cingulate cortex, project to medially situated amygdaloid areas such as the cortical and medial nuclei and to the periamygdaloid cortex. The agranular and dysgranular insula, the parainsula, and rostral portions of the superior temporal gyrus project both to the lateral, basal, and accessory basal nuclei and to the medially situated nuclei. Projections to the central nucleus are particularly prominent from these regions. These data are discussed in relation to the hierarchical processing of sensory information that occurs within the amygdaloid complex. J. Comp. Neurol. 451:301–323, 2002. © 2002 Wiley‐Liss, Inc.
In Patas monkey, glutamic acid decarboxylase‐67 and reelin mRNA coexpression varies in a manner dependent on layers and cortical areas
Authors: Rodriguez Miguel A. , Caruncho Hector J. , Costa Erminio , Pesold Christine , Liu Wen‐Sheng , Guidotti Alessandro 
Published: September 2002

AbstractIn nonhuman and human primates, reelin immunoreactivity is expressed consistently in γ‐aminobutyric acid (GABA)‐ergic interneurons of the three upper cortical layers (Impagnatiello et al. [1998] Proc. Natl. Acad. Sci. U S A 95:15718–15723; Rodriguez et al. [2000] Proc. Natl. Acad. Sci. U S A 97:3550–3555). To understand in detail the pattern of reelin synthesis in GABAergic interneurons of primate neocortex, a quantitative analysis of reelin and of glutamic acid decarboxylase‐67 (GAD67) mRNA‐positive neurons as well as a quantitative analysis of total neuronal density measured by neuron‐specific nuclear protein (NeuN) immunoreactivity was carried out in Patas monkey neocortex (Brodmann's areas 2, 3, 4, 6, 9, 17, 18, and 24). Reelin mRNA is expressed in every cortical area and layer studied, but layer II of each cortical area consistently revealed the largest neuronal population expressing reelin mRNA compared with other layers. The percentages of GAD67‐positive neurons in each layer of the eight cortical areas were 83–98% in layer I, 55–64% in layer II, 37–49% in layer III, 71–89% in layer IV, 54–68% in layer V, and 71–85% in layer VI. The percentages of GABAergic neurons expressing reelin were 86–100% in layer I, 76–84% in layer II, 52–96% in layer III, 23–33% in layer IV, 33–57% in layer V, and 34–54% in layer VI. These findings suggest that there may be two classes of GABAergic neurons that can be differentiated by their ability to express reelin mRNA and reelin protein. This differentiation may have a functional significance, considering that reelin is secreted into the extracellular matrix, where it plays a putative role in the maturation of newly formed dendritic spines and binds selectively to dendritic shafts and to spine postsynaptic densities and presumably to integrin receptors, including α3 subunits (Rodriguez et al. [2000]). J. Comp. Neurol. 451:279–288, 2002. © 2002 Wiley‐Liss, Inc.
Anatomy of the brain neurogenic zones revisited: Fractones and the fibroblast/macrophage network
Authors: Mercier Frederic , Kitasako John T. , Hatton Glenn I. 
Published: September 2002

AbstractCytogenesis in adult peripheral organs, and in all organs during development, occurs nearby basal laminae (BL) overlying connective tissue. Paradoxically, cytogenesis in the adult brain occurs primarily in the subependymal layer (SEL), a zone where no particular organization of BL and connective tissue has been described. We have reinvestigated the anatomy of the area considered the most neurogenic in the adult brain, the SEL of the lateral ventricle, in zones adjacent to the caudate putamen, corpus callosum, and lateral septal nucleus. Here, we report structural (confocal microscopy using laminin as a marker) and ultrastructural evidence for highly organized extravascular BL, unique to the SEL. The extravascular BL, termed fractones because of their fractal organization, were regularly arranged along the SEL and consisted of stems terminating in bulbs immediately underneath the ependyma. Fractones contacted local blood vessels by means of their stems. An individual fractone engulfed in its folds numerous processes of astrocytes, ependymocytes, microglial cells, and precursor cell types. The attachment site (base) of stems to blood vessels was extensively folded, overlying large perivascular macrophages that belong to a fibroblast/macrophage network coursing in the perivascular layer and through the meninges. In addition, collagen‐1, which is associated with BL and growth factors during developmental morphogenetic inductions, was immunodetected in the SEL and particularly regionalized within fractones. Because macrophages and fibroblasts produce cytokines and growth factors that may concentrate in and exert their effect from the BL, we suggest that the structure described is implicated in adult neurogenesis, gliogenesis, and angiogenesis. J. Comp. Neurol. 451:170–188, 2002. © 2002 Wiley‐Liss, Inc.
BMP mRNA and protein expression in the developing mouse olfactory system
Authors: Peretto Paolo , Cummings Diana , Modena Chiara , Behrens Maik , Venkatraman Giri , Fasolo Aldo , Margolis Frank L. 
Published: September 2002

AbstractThe bone morphogenetic proteins (BMPs) play fundamental roles during the organization of the central nervous system. The presence of these proteins has also been demonstrated in regions of the adult brain that are characterized by neural plasticity. In this study, we examined the expression of BMP4, 6, and 7 mRNAs and proteins in the murine olfactory system. The olfactory system is a useful model for studying cell proliferation and neural differentiation because both of these processes persist throughout life in the olfactory epithelium (OE) and olfactory bulb (OB). Our results demonstrate a differential expression of BMP4, 6, and 7 in the embryonic, postnatal, and adult olfactory system. In particular, BMP4 and BMP7 showed similar immunostaining patterns, being expressed in the olfactory region from the earliest stages studied (embryonic day 15.5) to adulthood. During development BMPs were expressed in the OE, olfactory bulb nerve layer, glomerular layer (GL), mitral cell layer (MCL), and subventricular zone. During the first postnatal week of life, BMP4 and 7 immunoreactivity (‐ir) was particularly evident in the GL, MCL, and in the subependymal layer (SEL), which originates postnatally from the subventricular zone. In adults, BMP4 and 7 immunostaining was present in the GL and SEL. Within the SEL, BMP4 and 7 proteins were expressed primarily in association with the astrocytic glial compartment. BMP6‐ir was always found in mature olfactory receptor neurons and their axonal projections to the OB. In summary, these data support the hypothesis that BMPs play a role in the morphogenesis of the olfactory system during development and in its plasticity during adulthood. J. Comp. Neurol. 451:267–278, 2002. © 2002 Wiley‐Liss, Inc.