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Infections caused by emerging fungal pathogens represent a new threat to human health. The yeast Yarrowia (Candida) galli was first described from chicken breast and liver in 2004 and has occasionally been isolated in clinical settings. In this study, we present the first report of a Y. galli isolate from a face granuloma of a woman. Y. galli is unable to grow at human physiological temperature (37 °C). Phenotypic analysis demonstrates that Y. galli can exist as several morphological types, namely fluffy, sticky, tight, and yeast forms, based on their cellular and colony appearances. Interestingly, Y. galli is able to undergo switching among different morphologies. These morphological changes are similar to the switching systems in pathogenic Candida species such as Candida albicans and Candida tropicalis. We further sequenced the genome of the Y. galli isolate. A comparative analysis with pathogenic yeast species indicated that a set of lipid metabolism genes were enriched in Y. galli. Domain enrichment analysis demonstrated that, similar to Candida clade species, the genome of Y. galli maintained several gene families required for virulence. Our biological and genomic analyses provide new insights into the understanding of the biology of Y. galli as either an environmental isolate or a potential human pathogen. [ABSTRACT FROM AUTHOR]

Vitronectin (Vtn), one of the extracellular matrix proteins, has been reported to result in cell cycle exit, neurite formation, and polarization of neural progenitor cells during neurogenesis. The underlying mechanism, however, has not been fully understood. In this study, we investigated the roles of Vtn and its integrin receptors, during the transition of neurites from multipolar to bipolar morphology, accompanying the cell cycle exit in neural progenitor cells. We used mouse neuroblastoma cell line Neuro2a as a model of neural progenitor cells which can induce cell cycle exit and the morphological transition of neurites by retinoic acid (RA)-stimulation. Treatment with an antibody for Vtn suppressed the RA-induced cell cycle exit and multipolar-to-bipolar transition. Furthermore, immunostaining results showed that in the cells displaying multipolar morphology Vtn was partially localized at the tips of neurites and in cells displaying bipolar morphology at both tips. This Vtn localization and multipolar-to-bipolar transition was perturbed by the transfection of a dominant negative mutant of cell polarity regulator Par6. In addition, a knockdown of β5 integrin, which is a receptor candidate for Vtn, affected the multipolar-to-bipolar transition. Taken together, these results suggest that Vtn regulates the multipolar-to-bipolar morphological transition via αvβ5 integrin. [ABSTRACT FROM AUTHOR]

Although gas-filled microbubbles with high echogenicity are widely applied inclinical ultrasonography, the micron scale particle size impedes their use in the treatment of solid tumors,which are accessible to objects less than several hundred nanometers. We herein propose an unusual approach involving apH-induced core-shell micelle-to-vesicle transition to prepare ultrasound-sensitive polymeric nanospheres (polymersomes in structure) possessing multiple features, including nanosize, monodispersity, and incorporation of a phase-transitional imaging agent into the aqueous lumen. These features are not achievable via the conventional double-emulsion method for polymersome preparation. The nanospheres were constructed based on a novel triblock copolymer with dual pH sensitivity. The liquid-to-gas phase transition of the imaging agent induced by external low-frequency ultrasound may destroy the nanospheres for a rapid drug release, with simultaneous tissue-penetrating drug delivery inside a tumor. These effects may provide new opportunities for the development of an effective cancer therapy with few adverse effects. [ABSTRACT FROM AUTHOR]

Candida albicans is the most common opportunistic fungal pathogen, which switches its morphology from single-cell yeast to filament through the various signaling pathways responding to diverse environmental cues. Various transcriptional factors such as Nrg1, Efg1, Brg1, Ssn6, and Tup1 are the key components of these signaling pathways. Since C. albicans can regulate its transcriptional gene expressions using common eukaryotic regulatory systems, its morphological transition by these signaling pathways could be linked to the epigenetic regulation by chromatin structure modifiers. Histone proteins, which are critical components of eukaryotic chromatin structure, can regulate the eukaryotic chromatin structure through their own modifications such as acetylation, methylation, phosphorylation and ubiquitylation. Recent studies revealed that various histone modifications, especially histone acetylation and deacetylation, participate in morphological transition of C. albicans collaborating with well-known transcription factors in the signaling pathways. Here, we review recent studies about chromatin-mediated morphological transition of C. albicans focusing on the interaction between transcription factors in the signaling pathways and histone deacetylases. [ABSTRACT FROM AUTHOR]

In order to develop polymeric self-assembly with an intelligent morphological transition property under appropriate stimuli, a series of pH-sensitive amphiphilic block copolymers have been prepared via atom transfer radical polymerization (ATRP). Due to the delicately designed macromolecular structure, poly(ethylene glycol)- b-poly(2-diisopropylaminoethyl methacrylate) (PEG- b-PDPA) could form self-assemblies with a controllable morphological transition in response to the physiological pH changes. As demonstrated by the results of dynamic light scattering (DLS) records and transmission electron microscopy (TEM) micrographs, PEG- b-PDPA could self-assemble into toruloid aggregates arranged by several single micelles at pH 7.4, but the morphology changed into uniform single micelles at pH 6.5. With a further decrease of pH value to 5.5, PEG- b-PDPA became double hydrophilic and could not self-assemble into any nanostructure. Therefore, this block copolymer provides a feasible approach to construct a nanoscale smart self-assembly with adjustable morphologies, which exhibits its potential for biomedical applications with specific physiological pH stimuli, such as intracellular delivery and tumor therapy. [ABSTRACT FROM AUTHOR]

Morphological evolution of silver nanocomposite films prepared by the wet colloidal route and surface-enhanced phenomena on aggregate nanostructures evolved during annealing were investigated. Dramatic changes in morphologies of particles and pores incurred by rearragement, coarsening, premelting, and dewetting of the silver clusters at different concentrations (i.e., mass thicknesses). At a higher mass thickness, the morphological transitions from self-organized nanoaggregates with aciniform pattern at 300 °C to elongated and coarsened particles with circular holes at 400 °C to island clusters at 500 °C occurred in the films. The peculiar absorption with a much redder and broader surface plasmon feature, which gone far beyond the theoretical prediction, induced by the formation of aciniform nanoaggregates embedded in the porous polymer matrix at a critical mass thickness of 9.6 nm during partial degradation of the PVP polymer and rearrangement of silver clusters at 300 °C. The surface-enhanced absorption was dramatically reduced by the elemination of the aggregate nanostructures and the spontaneous formation of the silver nanoisland film at the dewetting temperature of 500 °C. [ABSTRACT FROM AUTHOR]

Changes in erythrocyte shape during morphological response modified by benzalkonium chloride (BzA) were studied in sucrose solutions. Fixation of the cells with glutaraldehyde- and formaldehyde-containing fixatives at some time points is usually inadequate to maintain the current cell shape. Considering the reconstruction of erythrocyte shape, which takes into account the mode of fixative action, we showed that the echinocyte-forming activity of BzA depends on the concentration of this surfactant. It can induce a direct spherostomatocyte-spheroechinocyte transition without altering the near-spherical shape of the cells. On the other hand, the reverse spheroechinocyte-spherostomatocyte transition was always accompanied by some flattening of the cells, although in some instances discoidal shape was not achieved. The data point to asymmetric shape transitions of erythrocytes in sucrose solution, which contradicts the continuum and bilayer-couple models of shape regulation. It seems that the nonuniform structure of native erythrocyte membrane plays a more important role in morphological transitions of these cells than suggested earlier. [ABSTRACT FROM AUTHOR]

The transition in morphology of Ni3Sn4 grains that formed at the interface between liquid Sn-3.5Ag (numbers are in wt.% unless specified otherwise) solder and Ni substrate has been observed at 250–650°C. The morphological transition of Ni3Sn4 is due to the decrease of entropy of formation of the Ni3Sn4 phase and has been explained well by the change of Jackson’s parameter with temperature. According to the variation of solder joint strength with temperature, it decreased rapidly between 350°C and 450°C, where the thickness of the Ni3Sn4 intermetallic compound (IMC) layer was around 6.5 µm. However, the solder joint strength decreased slowly with an increase of soldering time without a significant drop, although the thickness of the IMC was larger than 6.5 µm. The notable drop of solder joint strength and the fracture mode transition with increase of soldering temperature appears to come from excessive lateral growth of IMC grains between 350°C and 450°C. [ABSTRACT FROM AUTHOR]

The Posuk-Chung Pavilion is a defunct irregular stone water channel in Kyongju, Korea, once used for the ‘meandering stream feast’ by kings of Silla Dynasty during the first millennium. The poets were seated around this stone water channel who composed the Chinese poems, overlooking the streams. They had to take the punishment drinks unless they finished the poem before the drifting cup filled with the rice wine arrived at their seats on the meandering stream. In this paper, we have made computer simulation as well as model experiment on the ancient meandering stream of the Posuk-Chung Pavilion. The computational results are compared with the experiment and the channel flow characteristics are delineated here. It is discussed how the present Posuk-Chung channel is morphologically distinguished from the Chinese and Japanese meandering streams. [ABSTRACT FROM AUTHOR]

The article presents abstracts of research on polymers. They include "Molecular Design of Block- and Graft Polymers and Their Nanophase-Separated Hierarchical Structures in Condensed," "Synthesis and Evaluation of Polystyrenes for Pigment Dispersant through ATRP Using Dimethyl 2,6-Dibromoheptanedioate as the Initiator" and "Effects of Size and Shape of Polymers on Spreading a Fire."

A dual-read detection system is described for non-enzymatic and non-aggregation based analysis of uric acid (UA). Silver triangular nanoprisms (AgTNPs) were used as colorimetric probes, while the reduction in the fluorescence of nitrogen-doped carbon quantum dots (N-CQDs) served as the fluorometric readout. The absorption band of the AgTNPs overlaps the emission band of N-CQDs (with a peak at 440 nm). Therefore, fluorescence is reduced owing to an inner filter effect. The AgTNPs are etched if exposed to H2O2, and round nanodiscs are formed. In the presence of UA, etching of the AgTNPs is suppressed because the facets of the AgTNPs are coated with UA. The absorbance, best measured at 683 nm, increases with the concentration of the pre-added UA. The colorimetric assay works in the 0.1-45 μM UA concentration range, and the fluorometric assay between 1 and 42 μM of UA. The respective detection limits are 50 and 200 nM, respectively. The probe can be used for direct visualization of UA. The method was successfully applied to the determination of UA in urine samples.The fluorescence of nitrogen-doped carbon quantum dots (N-CQDs) is quenched by AgTNPs (silver triangular nanoprisms). As the AgTNPs are etched by H2O2, fluorescence recovers in the system after H2O2 is added, and also undergoes a color change. Uric acid (UA) protects the AgTNPs from etching because the facets of the AgTNPs are coated with UA. The fluorescence of N-CQDs decreases. Thus, a dual-read probe is developed for determination of UA. [ABSTRACT FROM AUTHOR]