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Morphological Transformation (morphological + transformation)
Selected AbstractsHydrothermal Growth: Polymer-Templated Hydrothermal Growth of Vertically Aligned Single-Crystal ZnO Nanorods and Morphological Transformations Using Structural Polarity (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Mater. Abstract Position-configurable, vertical, single-crystalline ZnO nanorod arrays are fabricated via a polymer-templated hydrothermal growth method at a low temperature of 93 °C. A sol-gel processed dense c -oriented ZnO seed layer film is employed to grow nanorods along the c -axis direction [0001] regardless of any substrate crystal mismatches. Here, one-beam laser-interference lithography is utilized to fabricate nanoscale holes over an entire 2-in. wafer during the preparation of the polymer template. As such, vertically aligned ZnO nanorods can be grown from the seed layer exposed at the bottom of each hole. Furthermore, morphological transformations of the ZnO nanorods into pencil-like, needle-like, tubular, tree-like, and spherical shapes are obtained by controlling the growth conditions and utilizing the structural polarity of the ZnO nanorods. [source] Polymer-Templated Hydrothermal Growth of Vertically Aligned Single-Crystal ZnO Nanorods and Morphological Transformations Using Structural PolarityADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Ki Seok Kim Abstract Position-configurable, vertical, single-crystalline ZnO nanorod arrays are fabricated via a polymer-templated hydrothermal growth method at a low temperature of 93 °C. A sol-gel processed dense c -oriented ZnO seed layer film is employed to grow nanorods along the c -axis direction [0001] regardless of any substrate crystal mismatches. Here, one-beam laser-interference lithography is utilized to fabricate nanoscale holes over an entire 2-in. wafer during the preparation of the polymer template. As such, vertically aligned ZnO nanorods can be grown from the seed layer exposed at the bottom of each hole. Furthermore, morphological transformations of the ZnO nanorods into pencil-like, needle-like, tubular, tree-like, and spherical shapes are obtained by controlling the growth conditions and utilizing the structural polarity of the ZnO nanorods. [source] Atomic Imaging of Phase Transitions and Morphology Transformations in NanocrystalsADVANCED MATERIALS, Issue 48 2009Marijn A. van Huis A newly developed SiN microhotplate allows specimens to be studied at temperatures up to 1000 K at a resolution of 100 picometer (see image). Aberration-corrected transmission electron microscopy has become a commonplace tool to investigate stable crystals; however, imaging transient nanocrystals is much more demanding. Morphological transformations in gold nanoparticles and layer-by-layer sublimation of PbSe nanocrystals is imaged with atomic resolution. [source] The anatomy of the palatoquadrate in the Lower Triassic Proterosuchus fergusi (Reptilia, Archosauromorpha) and its morphological transformation within the archosauriform cladeACTA ZOOLOGICA, Issue 3 2009Jozef Klembara Abstract The anatomy of the palatoquadrate ossifications of the Lower Triassic archosauromorph Proterosuchus fergusi from South Africa is described. It consists of two ossifications, the epipterygoid and the quadrate, which were joined by cartilage in life. The margins of the cartilage are clearly indicated by ridges and grooves on the dorsal surface of the pterygoid. The epipterygoid ossification consists of two structures: the anteroposteriorly expanded basal portion and, dorsally from it, an extending, slender, ascending process. From the anterior margin of the basal portion of the epipterygoid, a plate-like structure, herein called the lamina epipterygoidea anteromedialis, extends anteromedially to form the anterolateral wall of the cavum epiptericum. Comparisons with the similarly constructed embryonal and adult epipterygoid components of Sphenodon punctatus show that the anteromedial lamina of the epipterygoid of P. fergusi is an additional component of the epipterygoid of this species and that this lamina is absent in the former species. However, a structure in a topologically similar position to the anteromedial lamina of the epipterygoid of P. fergusi is present in the palatoquadrate of Alligator mississippiensis. In the latter species, the structure is called the lamina palatoquadrati anterior; it ossifies in membrane and forms the dorsolateral cover of the huge trigeminal ganglion. It is hypothesized here that the anteromedial lamina of the epipterygoid of P. fergusi and the anterior lamina of the palatoquadrate of A. mississippiensis are most probably homologous structures and are present in both the basal and one of the crown taxa of the archosauromorph clade, respectively. [source] METAMORPHOSIS AND NEOTENY: ALTERNATIVE PATHWAYS IN AN EXTINCT AMPHIBIAN CLADEEVOLUTION, Issue 7 2006Rainer R. Schoch Abstract The Branchiosauridae was a clade of small amphibians from the Permo-Carboniferous with an overall salamander-like appearance. The clade is distinguished by an extraordinary fossil record that comprises hundreds of well-preserved specimens, representing a wide range of ontogenetic stages. Branchiosaurids had external gills and weakly ossified skeletons, and due to this larval appearance their status as neotenic (perennibranchiate) froms has long been accepted. Despite their extensive fossil record large specimens with an adult morphology appeared to be lacking altogether, but recently two adult specimens were identified in a rich sample of Apateon gracilis collected in the 19th century from a locality near Dresden, Saxony. These specimens are unique among branchiosaurids in showing a high level of ossification, including bones that have never been reported in a branchiosaur. These highlight the successive formation of features believed to indicate terrestrial locomotion, as well as feeding on larger prey items. Moreover, these transformations occurred in a small time window (whereas the degree of size increase is used as a proxy of time) and the degree of concentration of developmental events in branchiosaurids is unique among tetrapods outside the lissamphibians. These specimens are compared with large adults of the neotenic branchiosaurid Apateon caducus from the Saar-Nahe Basin, which despite their largetr body size lack the features found in the adult. A. gracilis specimens. These specimens give new insight into patterns of metamorphosis (morphological transformation) in branchiosaurids that are believed to be correlated to a change of habitat, and clearly show that different life-history pathways comparable to those of modern salamanders were already estabilshed in this Paleozoic clade. [source] Derivation, characterization, and phenotypic variation of hepatic progenitor cell lines isolated from adult ratsHEPATOLOGY, Issue 2 2002Li Yin Liver progenitor cells (LPCs) cloned from adult rat livers following allyl alcohol injury express hematopoietic stem cell and early hepatic lineage markers when cultured on feeder layers; under these conditions, neither mature hepatocyte nor bile duct, Ito, stellate, Kupffer cell, or macrophage markers are detected. These phenotypes have remained stable without aneuploidy or morphological transformation after more than 100 population doublings. When cultured without feeder layers, the early lineage markers disappear, and mature hepatocyte markers are expressed; mature hepatocytic differentiation and cell size are also augmented by polypeptide and steroidal growth factors. In contrast to hepatocytic potential, duct-like structures and biliary epithelial markers are expressed on Matrigel. Because they were derived without carcinogens or mutagens, these bipotential LPC lines provide novel tools for models of cellular plasticity and hepatocarcinogenesis, as well as lines for use in cellular transplantation, gene therapy, and bioreactor construction. [source] Atypical protein kinase C activity is required for extracellular matrix degradation and invasion by Src-transformed cellsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2009Elena M. Rodriguez Atypical protein kinase C (aPKC) isoforms have been shown to mediate Src-dependent signaling in response to growth factor stimulation. To determine if aPKC activity contributes to the transformed phenotype of cells expressing oncogenic Src, we have examined the activity and function of aPKCs in 3T3 cells expressing viral Src (v-Src). aPKC activity and tyrosine phosphorylation were found to be elevated in some but not all clones of mouse fibroblasts expressing v-Src. aPKC activity was inhibited either by addition of a membrane-permeable pseudosubstrate, by expression of a dominant-negative aPKC, or by RNAi-mediated knockdown of specific aPKC isoforms. aPKC activity contributes to morphological transformation and stress fiber disruption, and is required for migration of Src-transformed cells and for their ability to polarize at the edge of a monolayer. The , isoform of aPKC is specifically required for invasion through extracellular matrix in Boyden chamber assays and for degradation of the extracellular matrix in in situ zymography assays. Tyrosine phosphorylation of aPKC, is required for its ability to promote cell invasion. The defect in invasion upon aPKC inhibition appears to result from a defect in the assembly and/or function of podosomes, invasive adhesions on the ventral surface of the cell that are sites of protease secretion. aPKC was also found to localize to podosomes of v-Src transformed cells, suggesting a direct role for aPKC in podosome assembly and/or function. We conclude that basal or elevated aPKC activity is required for the ability of Src-transformed cells to degrade and invade the extracellular matrix. J. Cell. Physiol. 221: 171,182, 2009. © 2009 Wiley-Liss, Inc [source] Nutritional factors determining sclerotial formation of Polyporus umbellatusLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2009Y.-Y. Liu Abstract Aims:, To find out which nutritional condition is the determining factor for sclerotial formation of Polyporus umbellatus. Methods and Results:, The nutritional requirements of 15 carbohydrates, ten nitrogen compounds, eight vitamins and eight mineral elements were studied for their effects on mycelial growth and sclerotial formation of Polyporus umbellatus using the one-factor-at-a-time method. Only fructose could induce sclerotial formation of P.,umbellatus. An additional test indicated that nitrogen source categories influenced sclerotial formation significantly and that peptone was found to be the best for sclerotial production. Through an orthogonal matrix test, the effects of carbon/nitrogen factors on sclerotial formation were found be in the order: fructose > interaction between fructose and peptone > peptone. The optimal concentration for sclerotial formation was determined to be 50·0 g l,1 fructose and 4·0 g l,1 peptone. Conclusions:, Carbon source is the factor determining sclerotial formation of Polyporus umbellatus. Nitrogen source can influence such a morphological transformation significantly. The categories of vitamin and mineral element do not have relationship with the sclerotial formation. Significance and Impact of the Study:, This study provides the preparatory knowledge for the completely artificial culture of Polyporus umbellatus for its sclerotium. [source] Heteroarm Star Polystyrene- block -Poly(4-vinylpyridine): Multiple Morphologies in Dilute SolutionsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 22 2008Chia-Hung Lin Abstract Synthesis and solution morphologies of four new heteroarm star polystyrene- block -poly(4-vinylpyridine) were studied. As the water content increased, a morphological transformation of heteroarm PS4 -P4VP4 from spheres to cylinders, vesicles, and large compound vesicles was observed. The morphology of PS4 -P4VP4 in the solvent mixture of DMF/water or 1,4-dioxane/water was spherical, but changed to large compound micelles in THF/water. As the P4VP molar ratio decreased, the morphology changed from spherical mixed with cylindrical to vesicles, giant vesicles, and then to LCMs. The present study demonstrated the formation of multiple morphologies through manipulating solvent polarity and block ratio in dilute solution. [source] Multifocal dysembryoplastic neuroepithelial tumor with signs of atypia after regrowthNEUROPATHOLOGY, Issue 4 2007Jens Schittenhelm We report the case of a multifocal dysembryoplastic neuroepithelial tumor (DNT) in a 7-year-old girl with local tumor regrowth 6 years later. The tumor was localized in the right parietal lobe extending from the cortex into the periventricular white matter. After subtotal resection of a histopathologically confirmed DNT we observed unexpected tumor progression in long-term follow-up. Therefore, a second surgery was performed when the patient was 14 years of age. In neuropathological examination of the second specimen the tumor showed an increased cellularity and pleomorphism, microvascular proliferations, an elevated proliferative activity (MIB1-index focally up to 10%) and cellular atypia not typical for WHO grade I DNT. Furthermore, MRI studies showed additional supratentorial and infratentorial lesions which remained stable over years and are also well consistent with DNTs. Thus, an unusual form of a DNT with multifocal lesions, local regrowth and morphological transformation is supposed. [source] Morphological changes of sperm nuclei during spermatogenesis in the brown alga Cystoseira hakodatensis (Fucales, Phaeophyceae)PHYCOLOGICAL RESEARCH, Issue 2 2003Shinya Yoshikawa SUMMARY Morphological changes and chromatin condensation of sperm nuclei were observed during spermatogenesis in the fucalean brown alga Cystoseira hakodatensis (Yendo) Fensholt. Ultrastructural studies have shown that the mature spermatozoid has an elongated and concave nucleus with condensed chromatin. The morphological changes and the chromatin condensation process during spermatogenesis was observed. Nuclear size decreased in two stages during spermatogenesis. During the first stage, spherical nuclei decreased in size as they were undergoing meiotic divisions and the subsequent mitoses within the antheridium. During the second stage, the morphological transformation from a spherical into an elongated nucleus occurred. Afterwards, chromatin condensed at the periphery in each nucleus, and chromatin-free regions were observed in the center of the nucleus. These chromatin-free regions in the center of nucleus were compressed by the peripheral chromatin-condensed region. As the result, the elongated and concave nucleus of the mature sperm consisted of uniformly well-condensed chromatin. [source] A further proteomic study on the effect of iron in the human pathogen Trichomonas vaginalisPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 12 2007Jose Batista De Jesus Dr. Abstract Iron is an essential element to support the growth and survival of Trichomonas vaginalis. It plays a critical role in the host,parasite interaction, and modulates the expression of virulence factors in this protozoan. In this work, parasites grown in iron-rich and iron-depleted media were analyzed by (i) light and scanning electron microscopy and (ii) 2-DE and MS. Withdrawal of iron from the culture medium resulted in dramatic changes in both the morphology and in the proteome pattern of T. vaginalis. Trophozoites underwent transformation from ellipsoid or amoeboid forms to rounded cells, whose flagella and axostyle were internalized. Forty-five proteins differentially expressed in parasites cultivated in the absence of iron were identified. In iron-depleted parasites, enzymes involved in energetic metabolism, proteolysis and hydrogenosomal iron-sulfur (Fe-S) proteins were down-regulated or even suppressed. Among up-regulated proteins, six isoforms of actin were detected. In addition, phosphoenolpyruvate carboxykinase, putative lactate dehydrogenase, and putative adenosine triphosphatase were also up-regulated or were exclusively observed in gels related to iron-depleted parasites. Our data demonstrate that iron has a pivotal role in the regulation of the morphological transformation of T. vaginalis and modulates the expression of both Fe-S and non-Fe-S proteins in the parasite. [source] Conditional gene silencing utilizing the lac repressor reveals a role of SHP-2 in cagA -positive Helicobacter pylori pathogenicityCANCER SCIENCE, Issue 5 2004Megumi Higuchi RNA interference (RNAi) is a newly described biological phenomenon mediated by small interfering RNA (siRNA) that targets mRNA for degradation by cellular enzymes and has become a powerful method for studying gene functions in mammalian systems. The development of systems for inducing siRNA expression should enable examination of acute loss-of-function phenotypes in a cell of interest without the need to consider lethality or epigenetic adaptation of cells. We describe in this report an inducible siRNA expression system made by combined utilization of the RNA polymerase III-dependent promoter H1 and the bacterial lac repressor. Using this system, we established AGS gastric epithelial cells in which expression of SHP-2, a cellular tyrosine phosphatase known to specifically bind the Helicobacter pylori virulence factor CagA, is conditionally and reversibly silenced by the lactose analog isopropyl-1-thio-,-D-galactopyranoside (IPTG). Upon expression in AGS cells, CagA provoked a morphological transformation, termed the hummingbird phenotype, which is associated with CagA virulence. This morphogenetic activity of CagA was totally abolished when SHP-2 expression was silenced by inducible siRNA expression in AGS cells. Our results indicate that SHP-2 is a critical downstream effector of H. pylori CagA. The conditional gene silencing system described here should become a powerful tool for investigating the roles of cancer-related genes through a reversed genetic approach. [source] Role of Capping Ligands on the Nanoparticles in the Modulation of Properties of a Hybrid Matrix of Nanoparticles in a 2D Film and in a Supramolecular OrganogelCHEMISTRY - A EUROPEAN JOURNAL, Issue 36 2009Asish Pal Dr. Abstract We incorporate various gold nanoparticles (AuNPs) capped with different ligands in two-dimensional films and three-dimensional aggregates derived from N -stearoyl- L -alanine and N -lauroyl- L -alanine, respectively. The assemblies of N -stearoyl- L -alanine afforded stable films at the air,water interface. More compact assemblies were formed upon incorporation of AuNPs in the air,water interface of N -stearoyl- L -alanine. We then examined the effects of incorporation of various AuNPs functionalized with different capping ligands in three-dimensional assemblies of N -lauroyl- L -alanine, a compound that formed a gel in hydrocarbons. The profound influence of nanoparticle incorporation into physical gels was evident from evaluation of various microscopic and bulk properties. The interaction of AuNPs with the gelator assembly was found to depend critically on the capping ligands protecting the Au surface of the gold nanoparticles. Transmission electron microscopy (TEM) showed a long-range directional assembly of certain AuNPs along the gel fibers. Scanning electron microscopy (SEM) images of the freeze-dried gels and nanocomposites indicate that the morphological transformation in the composite microstructures depends significantly on the capping agent of the nanoparticles. Differential scanning calorimetry (DSC) showed that gel formation from sol occurred at a lower temperature upon incorporation of AuNPs having capping ligands that were able to align and noncovalently interact with the gel fibers. Rheological studies indicate that the gel,nanoparticle composites exhibit significantly greater viscoelasticity compared to the native gel alone when the capping ligands are able to interact through interdigitation into the gelator assembly. Thus, it was possible to define a clear relationship between the materials and the molecular-level properties by means of manipulation of the information inscribed on the NP surface. [source] Evolution and development of the primate limb skeletonEVOLUTIONARY ANTHROPOLOGY, Issue 3 2002Chi-Hua Chiu Abstract The order Primates is composed of many closely related lineages, each having a relatively well established phylogeny supported by both the fossil record and molecular data.1 Primate evolution is characterized by a series of adaptive radiations beginning early in the Cenozoic era. Studies of these radiations have uncovered two major trends. One is that substantial amounts of morphological diversity have been produced over short periods of evolutionary time.2 The other is that consistent and repeated patterns (variational tendencies3) are detected. Taxa within clades, such as the strepsirrhines of Madagascar and the platyrrhines of the Neotropics, have diversified in body size, substrate preference, and diet.2, 4,6 The diversification of adaptive strategies within such clades is accompanied by repeated patterns of change in cheiridial proportions7, 8 (Fig. 1) and tooth-cusp morphology.9 There are obvious adaptive, natural-selection based explanations for these patterns. The hands and feet are in direct contact with a substrate, so their form would be expected to reflect substrate preference, whereas tooth shape is related directly to the functional demands of masticating foods having different mechanical properties. What remains unclear, however, is the role of developmental and genetic processes that underlie the evolutionary diversity of the primate body plan. Are variational tendencies a signature of constraints in developmental pathways? What is the genetic basis for similar morphological transformations among closely related species? These are a sampling of the types of questions we believe can be addressed by future research integrating evidence from paleontology, comparative morphology, and developmental genetics. [source] Hydrothermal Growth: Polymer-Templated Hydrothermal Growth of Vertically Aligned Single-Crystal ZnO Nanorods and Morphological Transformations Using Structural Polarity (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Mater. Abstract Position-configurable, vertical, single-crystalline ZnO nanorod arrays are fabricated via a polymer-templated hydrothermal growth method at a low temperature of 93 °C. A sol-gel processed dense c -oriented ZnO seed layer film is employed to grow nanorods along the c -axis direction [0001] regardless of any substrate crystal mismatches. Here, one-beam laser-interference lithography is utilized to fabricate nanoscale holes over an entire 2-in. wafer during the preparation of the polymer template. As such, vertically aligned ZnO nanorods can be grown from the seed layer exposed at the bottom of each hole. Furthermore, morphological transformations of the ZnO nanorods into pencil-like, needle-like, tubular, tree-like, and spherical shapes are obtained by controlling the growth conditions and utilizing the structural polarity of the ZnO nanorods. [source] Polymer-Templated Hydrothermal Growth of Vertically Aligned Single-Crystal ZnO Nanorods and Morphological Transformations Using Structural PolarityADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Ki Seok Kim Abstract Position-configurable, vertical, single-crystalline ZnO nanorod arrays are fabricated via a polymer-templated hydrothermal growth method at a low temperature of 93 °C. A sol-gel processed dense c -oriented ZnO seed layer film is employed to grow nanorods along the c -axis direction [0001] regardless of any substrate crystal mismatches. Here, one-beam laser-interference lithography is utilized to fabricate nanoscale holes over an entire 2-in. wafer during the preparation of the polymer template. As such, vertically aligned ZnO nanorods can be grown from the seed layer exposed at the bottom of each hole. Furthermore, morphological transformations of the ZnO nanorods into pencil-like, needle-like, tubular, tree-like, and spherical shapes are obtained by controlling the growth conditions and utilizing the structural polarity of the ZnO nanorods. [source] Head morphology in perinatal dolphins: A window into phylogeny and ontogenyJOURNAL OF MORPHOLOGY, Issue 11 2006Michael A. Rauschmann Abstract In this paper on the ontogenesis and evolutionary biology of odontocete cetaceans (toothed whales), we investigate the head morphology of three perinatal pantropical spotted dolphins (Stenella attenuata) with the following methods: computer-assisted tomography, magnetic resonance imaging, conventional X-ray imaging, cryo-sectioning as well as gross dissection. Comparison of these anatomical methods reveals that for a complete structural analysis, a combination of modern imaging techniques and conventional morphological methods is needed. In addition to the perinatal dolphins, we include series of microslides of fetal odontocetes (S. attenuata, common dolphin Delphinus delphis, narwhal Monodon monoceros). In contrast to other mammals, newborn cetaceans represent an extremely precocial state of development correlated to the fact that they have to swim and surface immediately after birth. Accordingly, the morphology of the perinatal dolphin head is very similar to that of the adult. Comparison with early fetal stages of dolphins shows that the ontogenetic change from the general mammalian bauplan to cetacean organization was characterized by profound morphological transformations of the relevant organ systems and roughly seems to parallel the phylogenetic transition from terrestrial ancestors to modern odontocetes. J. Morphol., 2006. © 2006 Wiley-Liss, Inc. [source] | |||||||||||||||||||