Sequence Of Morphological Changes Research Articles

Axonal Neuropathy-associated TRPV4 Regulates Neurotrophic Factor-derived Axonal Growth

Spinal muscular atrophy and hereditary motor and sensory neuropathies are characterized by muscle weakness and atrophy caused by the degenerations of peripheral motor and sensory nerves. Recent advances in genetics have resulted in the identification of missense mutations in TRPV4 in patients with these hereditary neuropathies. Neurodegeneration caused by Ca(2+) overload due to the gain-of-function mutation of TRPV4 was suggested as the molecular mechanism for the neuropathies. Despite the importance of TRPV4 mutations in causing neuropathies, the precise role of TRPV4 in the sensory/motor neurons is unknown. Here, we report that TRPV4 mediates neurotrophic factor-derived neuritogenesis in developing peripheral neurons. TRPV4 was found to be highly expressed in sensory and spinal motor neurons in early development as well as in the adult, and the overexpression or chemical activation of TRPV4 was found to promote neuritogenesis in sensory neurons as well as PC12 cells, whereas its knockdown and pharmacologic inhibition had the opposite effect. More importantly, nerve growth factor or cAMP treatment up-regulated the expression of phospholipase A(2) and TRPV4. Neurotrophic factor-derived neuritogenesis appears to be regulated by the phospholipase A(2)-mediated TRPV4 pathway. These findings show that TRPV4 mediates neurotrophic factor-induced neuritogenesis in developing peripheral nerves. Because neurotrophic factors are essential for the maintenance of peripheral nerves, these findings suggest that aberrant TRPV4 activity may lead to some types of pathology of sensory and motor nerves.

Study of Microstructures in Single Crystalline Chemical Vapor Deposited Diamond Thin Films

Homo-epitaxial (100) single crystal diamond films of different isotopic (13C) composition were synthesized by micro-wave plasma chemical vapor deposition (MPCVD). Undoped 12C (100) films were also synthesized at different thicknesses. The growth surface of 13C doped showed a sequential morphological change from flat surface to stepped or ledge surface and coarsening of the steps/ledges with the increase of 13C-isotope concentration. As the growth proceeds via surface steps/ledges and coarsening of these steps/ledges, further increase in imperfection of the grown CVD single crystal diamonds observed with the development of non-(100) orientations. In case of undoped 12C samples, as the thickness increased the in-grain misorientation got reduced.

Image-based Screening Identifies Novel Roles for IκB Kinase and Glycogen Synthase Kinase 3 in Axonal Degeneration

Axon degeneration is an active, evolutionarily conserved self-destruction program by which compromised axons fragment in response to varied insults. Unlike programmed cell death, axon degeneration is poorly understood. We have combined robotic liquid handling with automated microscopy and image analysis to create a robust screening platform to measure axon degeneration in mammalian primary neuronal cultures. Using this assay, we performed an unbiased screen of 480 bioactive compounds, identifying 11 that reproducibly delay fragmentation of severed axons in vitro, including two inhibitors of glycogen synthase kinase 3 and two inhibitors of IκB kinase. Knockdown of each of these targets by shRNA lentivirus also delays axon degeneration in vitro, further supporting their role in the axon degeneration program.

Hypermethylation of MGMT and DAPK gene promoters is associated with tumorigenesis and metastasis in oral squamous cell carcinoma

Background/purpose Oral squamous cell carcinoma (OSCC) is the fourth major cause of mortality among males in Asia. The tumorigenesis of OSCC is a multi-step process characterized by sequential morphological changes. The extent of lymph node metastasis is a major determinant in the prognosis of cancer. Hypermethylation is an important pathway for repression of gene transcription in cancer cells and a promising marker for cancer detection. It is also found in early metastatic cancer patients. Materials and methods Sixty-four histologically confirmed OSCC tissues and corresponding nontumorous tissues were enrolled in this study. DNA was extracted. The promoter methylation status of the p16, death-associated protein kinase (DAPK), MGMT, and glutathione S-transferase genes in OSCC tissues was evaluated by a methylation-specific polymerase chain reaction analysis. Results Frequencies of promoter hypermethylation of p16, DAPK, and MGMT in OSCC tissue were 67.2%, 45.3%, and 31.3%, respectively. No methylation was found in normal oral mucosa. Methylation rates of MGMT (50%) and DAPK (55.6%) in metastasized OSCC were higher than those of MGMT (23.9%) and DAPK (41.3%) in nonmetastasized OSCC. No glutathione S-transferase P methylation was found in any tissue samples. Conclusions Our study supports the hypothesis that hypermethylation of p16 gene promoters may indicate a high risk of oral cancer, and hypermethylation of the MGMT and DAPK genes may be a major indicator of early OSCC metastasis.

Caspase-activated ROCK-1 allows erythroblast terminal maturation independently of cytokine-induced Rho signaling

Stem cell factor (SCF) and erythropoietin are strictly required for preventing apoptosis and stimulating proliferation, allowing the differentiation of erythroid precursors from colony-forming unit-E to the polychromatophilic stage. In contrast, terminal maturation to generate reticulocytes occurs independently of cytokine signaling by a mechanism not fully understood. Terminal differentiation is characterized by a sequence of morphological changes including a progressive decrease in cell size, chromatin condensation in the nucleus and disappearance of organelles, which requires transient caspase activation. These events are followed by nucleus extrusion as a consequence of plasma membrane and cytoskeleton reorganization. Here, we show that in early step, SCF stimulates the Rho/ROCK pathway until the basophilic stage. Thereafter, ROCK-1 is activated independently of Rho signaling by caspase-3-mediated cleavage, allowing terminal maturation at least in part through phosphorylation of the light chain of myosin II. Therefore, in this differentiation system, final maturation occurs independently of SCF signaling through caspase-induced ROCK-1 kinase activation.

Abstract LB-103: Circulating chromatin is a novel DNA damaging agent that induces genomic instability and malignant transformation

Abstract A paradox of clinical oncology is that while chemotherapy (CT) or radiotherapy (RT) can induce dramatic tumor responses, they do not translate into commensurate improvements in patient survival. To address this paradox, we have proposed a hypothesis that posits that apoptotic genetic material released from tumor cells into the circulation can enter healthy cells at distant sites to induce oncogenic transformation that masquerade as metastasis (Nature Clinical Practice Oncology 2007;4:203). Implicit in this hypothesis is the suggestion that CT and RT, by inducing tumor cell apoptosis, may encourage dissemination of cancer by a process of “remote de novo oncogenesis”. To test this hypothesis, we purified circulating chromatin fragments (PCFs) from sera of 40 cancer patients, both before and after CT or RT, and from 40 age and sex matched healthy donors, and added them to cells in culture. PCFs from all samples tested readily entered the recipients and triggered a DNA damage response (DDR) evidenced by the activation of H2AX and proteins of DDR and apoptotic pathways, namely, ataxia telangiectasia mutated (ATM), ataxia telangiectasia and Rad3 related (ATR), p53 and Caspase3. The DDR induced the integration of the incoming PCFs into the mouse cell genomes, and some of the genes contained within the PCFs were found to be expressed as human proteins. The extent of DDR induction by PCFs from the various samples followed the order: post- CT/RT > pre- CT/RT > healthy donors. When diverse cell types of human and mouse origin were exposed to PCFs, DDR was activated in all of them indicating that this activation was not cell-type specific but was universal in nature. When injected into mice, PCFs got stably integrated into the genomes of cells of their vital organs. Cultured cells exposed to PCFs showed numerous chromosomal aberrations as well as numerical increase and amplification of centrosomes within 48 hours, indicating an early onset of chromosomal instability. The treated cells exhibited a sequence of morphological changes within a span of 6 days that included: cell cycle arrest increase in cell size apoptosis senescence. By day 8, rapidly dividing resurgent cells with altered morphologies, some of which were apparently oncogenically transformed, arose to surround the senescent cells and ultimately to fill the dish. In contrast to PCFs, DNA purified from PCFs, or directly from serum, had no biological activity. When PCF-treated cells were injected into immuno-deficient mice, tumors developed in 26 % of the injected animals. Our results clearly identify circulating chromatin fragments as novel DNA damaging agents that are capable of entering and integrating into healthy cell genomes to induce chromosomal instability and malignant transformation. These novel findings provide strong support for our proposal for a mechanism of metastasis that implicates a process of “remote de novo oncogenesis.” Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-103.

Time sequence of auditory nerve and spiral ganglion cell degeneration following chronic kanamycin-induced deafness in the guinea pig

We investigated the time sequence of morphological changes of the spiral ganglion cell (SGC) and auditory nerve (AN) following chronic kanamycin-induced deafness. Guinea pigs were treated with kanamycin by subcutaneous injection at 500 mg/kg per day for 7 days. Histological changes in hair cells, SGCs, Schwann cells and the area of the cross-sectional of the AN with vestibular ganglion (VG) in the internal acoustic meatus were quantified at 1, 7, 14, 28, 56 and 70 days after kanamycin treatment. Outer hair cells decreased at 7 and 14 days. Loss of inner hair cells occurred at 14 and 28 days. The cross-sectional area of the AN with VG increased at 1 day and decreased shortly following loss of SGCs and Schwann cells at 7, 14 and 28 days after deafening. There was a similar time course of morphological changes in the overall cochlea and the basal turn. Thus, the effects of kanamycin on hair cells, spiral ganglion and Schwann cells are progressive. Early degeneration of SGC and Schwann cell mainly results from the direct toxic effect of kanamycin. However, multiple factors such as loss of hair cell, degeneration of Schwann cell and the progressive damage of kanamycin, may participate in the late degeneration process of SGCs. The molecular mechanism of the degeneration of SGC and Schwann cell should be investigated in the future. Moreover, there is a different time sequence of cell degeneration between acute and chronic deafness by kanamycin.

Prevalence of Hepatic Parasites in Korean Wild Rats (Rattus norvegicus) and Their Association With Pulmonary Arteriolar Medial Hypertrophy

C hepatica, an important zoonotic parasite, and C fasciolaris are common parasites in rodents. In rodent livers, C hepatica causes sequential morphologic changes that are designated as early, intermediate, or late phase, and C fasciolaris forms cysts surrounded by fibroplasia and granulomatous inflammation. The present study describes the prevalence of these parasites and associated liver and lung lesions in wild rats (Rattus norvegicus) living around pig farms in South Korea. Selected parenchymal organs, including liver and lung, of 89 wild rats were examined. Of 89 rats, 28 (31.5%) were infected with either C hepatica or C fasciolaris or with both parasites. Severe medial hypertrophy of small arterioles was observed in the lungs of 11 of the 28 parasite-infected rats (P < .01). The pulmonary arteriolar hypertrophy in the rats infected with C hepatica was strongly associated with early and/or intermediate phases (88.8%) of morphologic change in the livers (P < .01). As such, this report is the first to suggest a significant association between parasite-induced hepatitis and pulmonary arteriolar hypertrophy in rodents. Further studies are warranted for the use of C hepatica-infected rats as an animal model to explore the underlying mechanisms of portopulmonary hypertension in humans.

Alteration in cellular morphology, density and distribution in rat vocal fold mucosa following injury

The vocal fold mucosa plays an important role in voice production. Its cellular composition and density frequently change under various pathological conditions, often contributing to altered extracellular matrix production, tissue viscoelasticity, and voice quality. In this study, cellular changes in the rat mucosa following a unilateral stripping injury were investigated and analyzed semi-quantitatively. Distinctive and sequential changes in cellular morphology, composition, and density were observed in the mucosa post-injury. Cellular recruitment was a major event during the early stage of injury and reached its peak level by day 5 post-injury. Several types of cells, including neutrophil-like cells, epithelial cells, and fibroblast-like cells, were sequentially recruited. The sequential emergence of reactive cell populations following injury and subsequent reconstruction of the mucosa suggests their involvement in vocal fold tissue repair and scar formation processes.

Changing expression patterns: focus on “The transcription factor, glial cell missing 2, is involved in differentiation and functional regulation of H+-ATPase-rich cells in zebrafish (Danio rerio)”

euryhaline species of fish have a remarkable osmo- and ionoregulatory capacity. Some euryhaline species like the Mozambique tilapia can directly be transferred from freshwater to seawater and vice versa, i.e., osmolarity of the external fluid changes by ∼1,000 mOsm. Many others can tolerate this

Platelet Birth.

Abstract How and where human platelets get born are two questions still harboring great mystery. In vivo and in vitro approaches have contributed to a better understanding of the phenomenon. The recent study of a family with congenital autosomal-dominant thrombocytopenia showed ectopic platelet release in the bone marrow of the affected individuals. Further, molecular studies identified a new mutation in the gene encoding cytochrome c, which yields a cytochrome c with enhanced apoptotic activity. It is known that platelet birth occurs when megakaryocytes (MKs) undergo compartmentalized apoptotic activity. In this family case, enhanced apoptosis in MKs led to the premature release of platelets in the bone marrow, preventing their natural birth into the circulation after MK migration and causing thrombocytopenia. A similar finding, i.e., platelet birth in the marrow, was made in Wiskott Aldrich syndrome, providing a pathophysiological explanation for the thrombocytopenia, related to impaired migration capacities of MKs upon SDF chemotaxis. Indeed, direct platelet delivery in the human bone marrow space is not currently observed. However, maturing MKs are located close to the marrow sinusoids whose barrier they are able to cross, and entire MKs have been seen in the circulating blood where they become exposed to circulatory shear forces. Since the rate of platelet shedding in culture systems is remarkably low, we hypothesised that a missing element for efficient platelet production in static culture systems would be shear stress. Thus, we exposed human MKs, cultured in vitro until full maturation, to a substrate of matrix protein and high shear rates equivalent to those encountered in capillaries and small arteries. Cells were observed by real-time videomicroscopy, immunofluorescence, and electron microscopy. Shear forces specifically induced a sequence of morphological changes, converting mature MKs into proplatelets, and platelets, which consistently detached from the mother cells into the flow,, at a rate 20 times higher than static culture conditions. Using specific antibody inhibition, we showed the major involvement of GPIb in platelet formation, since its blockade inhibited MK adhesion and subsequent platelet formation. In addition, aIIbb3 was essential for firm MK anchorage, which was required for subsequent platelet formation. These experiments show that MK exposure to high shear rates promotes platelet production via GPIb (and secondarily aIIbb3) interactions with vascular matrix proteins. In conclusion, the above studies converge to present evidence that platelet birth takes place in circulating blood, being regulated by the migratory and apoptotic capacities of MKs and dependent on GPIb and hemodynamic forces.

Caspase Activated Rock-1 Allows Erythroblasts Enucleation Independently of Cytokine Signaling

Stem Cell Factor (SCF) and Erythopoietin (Epo) are strictly required for preventing apoptosis and stimulating proliferation, allowing differentiation of erythroid precursors from CFU-E until the polychromatophilic stage. In contrast, terminal maturation generating erythrocytes occurs independently of cytokine signaling by a mechanism poorly understood. Terminal differentiation is characterized by a sequence of morphological changes including a progressive decrease in cell size and nucleus with chromatin condensation and disappearance of organelles that require transient caspase activation. These events are followed by nuclei extrusion as a consequence of plasma membrane and cytoskeleton reorganization. Two serine/threonine protein kinases, Rock-1 and Rock-2, the main Rho effectors, are key regulators of the actomyosin-based contractility. To determine the role of the Rho/Rock pathway in the terminal stage of erythropoiesis, we used an in vitro model of erythroid differentiation based on human hematopoietic cells derived from cord blood. We showed that in early step, SCF stimulates Rho/Rock pathway that is involved in erythroblasts proliferation and cytokinesis until the basophilic stage. Thereafter, Rock-I is activated independently of Rho signaling by caspase-3-mediated cleavage. To investigate the role of Rock during erythroid terminal differentiation, we used a Rock inhibitor (Y-27632). At day 8 of the CD36+ control culture, 55% of cells exhibited a mature phenotype (30% polychromatic, and 25% orthochromatic erythroblasts). By contrast, in the Y-27632 treated culture, there were no more than 23% mature cells (22% polychromatic and 1% orthochromatic erythroblasts) and 47% exhibited apoptotic features. Most of these apoptotic cells exhibited mature morphology suggesting that apoptosis occurred during the late step of maturation at the time of caspase activation. The percentage of enucleated cells was low in these culture conditions, thus, to determine whether or not Rock was also involved in the enucleation process, we used a coculture on MS5 stromal layer system (Giarratana, Nat Biotechnol 2005). At day 18, the rate of enucleated cells was 30% in the control culture whereas it was two-fold decreased in the Y-27632 treated culture and many of mature cells were instead dying by apoptosis. This finding suggested that Rock inhibition could be also involved in the enucleation process. By using shRNA technique, we demonstrated that Rock-1 is involved in terminal maturation and enucleation through phosphorylation of the light chain of Myosin II (MLC2). Therefore, in this differentiation system, caspase activation allows final maturation independently of cytokine signaling through kinase cleavage and activation.

Quantitative evaluation of bone resorption activity of osteoclast‐like cells by measuring calcium phosphate resorbing area using incubator‐facilitated and video‐enhanced microscopy

Quantitative evaluation of the ability of bone resorption activity in live osteoclast-like cells (OCLs) has not yet been reported on. In this study, we observed the sequential morphological change of OCLs and measured the resorbing calcium phosphate (CP) area made by OCLs alone and with the addition of elcatonin utilizing incubator facilitated video-enhanced microscopy. OCLs, which were obtained from a coculture of ddy-mouse osteoblastic cells and bone marrow cells, were cultured on CP-coated quartz cover slips. The CP-free area increased constantly in the OCLs alone, whereas it did not increase after the addition of elcatonin. This study showed that analysis of the resorbed areas under the OCL body using this method enables the sequential quantitative evaluation of the bone resorption activity and the effect of several therapeutic agents on bone resorption in vitro.

Embryonic development of Girardia tigrina (Girard, 1850) (Platyhelminthes, Tricladida, Paludicola)

The embryonic development of freshwater triclads is mainly known from studies of species of Dendrocoelum, Planaria, Polycelis, and, more recently, Schmidtea. The present study characterizes the development of Girardia tigrina (Girard, 1850) by means of optical microcopy using glycol methacrylate semi-thin sections. 94 cocoons were collected in the period from laying to hatching, with intervals of up to twenty-four hours. The sequence of morphological changes occurring in the embryo permitted the identification of nine embryonic stages. At the time of cocoon laying, numerous embryos were dispersed among many yolk cells, with a rigid capsule covering the entire cocoon. In the first stage (approx. up to 6 hours after cocoon laying), yolk cells and embryonic cells showed random distribution. Stage II (between 12 and 24 hours after cocoon laying) is characterized by aggregates of blastomeres, which later aggregate forming an enteroblastula. Approximately 2 days after cocoon laying (stage III), formation of the embryonic epidermis and embryonic digestive system took place, the latter degenerating during the subsequent stage. Stage V (until the fourth day) is characterized by the formation of the definitive epidermis. Between 4 and 6 days after laying, organogenesis of the definitive inner organs starts (stage VI). Approximately 14 days after laying (stage IX), formation of the nervous system is completed. At this stage, the embryo shows similar characteristics to those of newly hatched juveniles. The hatching of Girardia tigrina occurs in the period between twelve to twenty-two days after cocoon laying.

Comparative investigation of the late embryogenesis of Leptodora kindtii (Focke, 1844) (Crustacea: Branchiopoda), with notes on types of embryonic development and larvae in Cladocera

The embryonic development of the parthenogenetic eggs of Leptodora kindtii has been investigated by observing living embryos removed from the female brood pouch. The sequence of morphological changes was analysed, as was the time at which the activity of certain organs began. The timing of these events at 20–22°C is documented. These data were compared with similar information obtained for some representatives of Ctenopoda and Anomopoda. The sequence of appearance of rudiments of organs on the ventral side of the embryos is similar in all these groups but the timing of shedding of the embryonic membranes differs. Hatching from the inner egg membranes takes place at the late metanauplius stage in Leptodora as in Ctenopoda and Cyclestherida, while in Anomopoda this stage is embryonized. The development of Leptodora is more like that of Ctenopoda than of Anomopoda. The embryos of all the above‐mentioned groups begin to grow at approximately the same morphological stage. A new scheme for the periodization of the embryogenesis of L. kindtii is proposed, which includes four well‐separated stages. Previously, the same number of developmental stages has been reported for Ctenopoda and Anomopoda. In Leptodora, as well as in Ctenopoda, the first two of these occur within the egg membranes. Cyclestheria has at least one embryonic moult and one embryonic stage more than Leptodora and other cladocerans. Embryonic stages 3 and 4 of the parthenogenetic eggs of L. kindtii represent a peculiar type of secondary larvae developing inside the female's brood pouch. The appearance of a free‐living nauplius in L. kindtii arises from its mode of hatching from the gamogenetic egg.

Plasma Interactions With Bacterial Biofilms as Visualized Through Atomic Force Microscopy

Bacterial biofilms are microbial communities that are less susceptible to standard killing methods than free-living bacteria. Gas-discharge plasmas were used to treat biofilms for various exposure times. After 5-min plasma exposure, 90% of culturable cells were removed. Atomic-force-microscope images that reveal the sequential changes in cell morphology occurring during plasma treatment are presented.

Studies on the development of omasum in west african dwarf goats (Capra hircus)

This work studied the sequential morphological changes of omasum in foetuses, neonates and adult West African Dwarf (WAD) goats by gross and light microscopic methods. The mean omasal volume was 1.37 +/- 0.36, 4.2 +/- 0.4, 8.7 +/- 6.9 and 60.1 +/- 8.6 ml for gestation day 87 and 146 foetuses, neonates and adults respectively. Grossly the mucosa exhibited longitudinally oriented primary, secondary, tertiary and quartnery laminae with smooth surface in foetuses and numerous papillae in the adults. Microscopically it was lined by stratified squamous epithelium which was divided into larger lighter luminal and smaller darker basal zones in gestation day 60 foetuses. The core of the laminae contained extension of the inner muscular tunic. The basal zone developed lateral evaginations (corial papillae) into the lighter zone of the laminae in gestation day 106 foetuses. By term these corial papillae approached the luminal surface. The papillae emerged above the luminal surface in 4 week old neonates. The papillae were fully developed in adult goats. The mean papillary height and width were -205.1 +/- 34.0, 67.0 +/- 9.6; 235.0 +/- 86.5, 185.0 +/- 42.3 and 570.3 +/- 60.0, 290.1 +/- 66.3 microm for foetuses, neonates and adult goats. The inner circular layer was thicker than the outer longitudinal layer of the muscular tunic. The central muscular layer of the laminae originated from the inner circular layer with attachment to the outer muscular layer in adults. This attachment could be adaptation for better anchorage and muscular contraction of the laminae in WAD goats.

Intestinal regeneration by a novel surgical procedure

Treatment of short bowel syndrome is problematical. Small bowel tissue engineering has achieved modest results in animal studies. The aim of this study was to investigate intestinal regeneration in a novel surgical model. Roux-en-Y bypass procedures were performed on 40 Wistar rats weighing 250-350 g. Animals were killed at 1, 2, 3, 4, 8, 12 and 24 weeks after implantation with a 3-cm silicone tube. The spatio temporal relationship of intestinal regeneration was analysed using three-dimensional multislice computed tomography, and examination of sequential morphological changes on gross or histological findings and measurement of missing intestinal tissue (growth defects). Progressive intestinal regeneration on a silicone tube was identifiable in 35 animals. Most adhesions were initially localized on the tube but spread to a distal site 4 weeks after implantation. Growth defects decreased with time, with a marked reduction in the first 4 weeks and a gradual reduction to week 24 after implantation. Luminal patency shown radiologically as well as sequential histological findings, such as mucosal lining, matrix remodelling and muscular regeneration, suggested that regeneration of intestinal tissue took place, not merely scar contraction. Non-invasive as well as histomorphological assessment followed intestinal regeneration over time in this model, which provides scope for further studies.

Moesin Controls Cortical Rigidity, Cell Rounding, and Spindle Morphogenesis during Mitosis

During mitosis, animal cells undergo a complex sequence of morphological changes, from retraction of the cell margin and cell rounding at the onset of mitosis to axial elongation and cytokinesis at mitotic exit. The molecular mechanisms driving the early changes in mitotic cell form and their functional significance, however, remain unknown. Here we identify Moesin as a key player. Moesin is the sole Drosophila member of the ERM proteins, which, once activated via phosphorylation, crosslink actin filaments to the cytoplasmic tails of plasma membrane proteins. We find that the Moesin is activated upon entry into mitosis, is necessary for the accompanying increase in cortical rigidity and cell rounding and, when artificially activated, is sufficient to induce both processes in interphase cells, independently of Myosin II. This phospho-Moesin-induced increase in cortical rigidity plays an important role during mitotic progression, because spindle morphogenesis and chromosome alignment are compromised in Moesin RNAi cells. Significantly, however, the spindle defects observed in soft metaphase cells can be rescued by the re-establishment of cortical tension from outside the cell. These data show that changes in the activity and localization of Moesin that accompany mitotic progression contribute to the establishment of a stiff, rounded cortex at metaphase and to polar relaxation at anaphase and reveal the importance of this Moesin-induced increase in cortical rigidity for spindle morphogenesis and orderly chromosome segregation. In doing so, they help to explain why dynamic changes in cortical architecture are a universal feature of mitosis in animal cells.

Morphologic changes in cat epithelium following continuous wear of orthokeratology lenses: A pilot study

To investigate the sequence of morphologic changes over time in cat epithelium during continuous wear of orthokeratology lenses. Four 2-year-old female cats were used; one served as a no lens wear control and three wore custom designed Paragon CRT lenses for myopic and hyperopic correction in the right and left eyes, respectively. Lenses were worn continuously and animals were euthanased after 4h, 8h and 14 days. Corneal tissue was fixed then stained with hematoxylin and eosin for histologic evaluation and measurement of epithelial thickness. Average epithelial thickness of control eyes in the centre (38+/-1 microm) and mid-periphery (3.0 mm from the centre, 38+/-2 microm) of the cornea was similar. Epithelial thickness in myopic corrected eyes showed progressive thinning in the centre and progressive thickening in the mid-periphery with increased lens wearing time. Hyperopic corrected eyes showed the opposite pattern of progressive epithelial thickening in the centre and thinning in the mid-periphery with lens wearing time. The epithelium appears to play a major role in the changes induced by orthokeratology lenses. The epithelial effects were dependent on time and lens design. Further studies are needed to determine the mechanisms responsible for these changes.