Liquid crystal phase transitions in suspensions of polydisperse plate-like particles

Colloidal suspensions that form periodic self-assembling structures on sub-micrometre scales are of potential technological interest; for example, three-dimensional arrangements of spheres in colloidal crystals might serve as photonic materials, intended to manipulate light. Colloidal particles with non-spherical shapes (such as rods and plates) are of particular interest because of their ability to form liquid crystals. Nematic liquid crystals possess orientational order; smectic and columnar liquid crystals additionally exhibit positional order (in one or two dimensions respectively). However, such positional ordering may be inhibited in polydisperse colloidal suspensions. Here we describe a suspension of plate-like colloids that shows isotropic, nematic and columnar phases on increasing the particle concentration. We find that the columnar two-dimensional crystal persists for a polydispersity of up to 25%, with a cross-over to smectic-like ordering at very high particle concentrations. Our results imply that liquid crystalline order in synthetic mesoscopic materials may be easier to achieve than previously thought.     

CHFR: a key checkpoint component implicated in a wide range of cancers

CHFR (Checkpoint with Forkhead-associated and RING finger domains) has been implicated in a checkpoint regulating entry into mitosis. However, the details underlying its roles and regulation are unclear due to conflicting lines of evidence supporting different notions of its functions. We provide here an overview of how CHFR is thought to contribute towards regulating mitotic entry and present possible explanations for contradictory observations published on the functions and regulation of CHFR. Furthermore, we survey key data showing correlations between promoter hypermethylation or down-regulation of CHFR and cancers, with a view on the likely reasons why different extents of correlations have been reported. Lastly, we explore the possibilities of exploiting CHFR promoter hypermethylation status in diagnostics and therapeutics for cancer patients. With keen interest currently focused on the association between hypermethylation of CHFR and cancers, details of how CHFR functions require further study to reveal how its absence might possibly contribute to tumorigenesis.     

SPIN90 dephosphorylation is required for cofilin-mediated actin depolymerization in NMDA-stimulated hippocampal neurons

Actin plays a fundamental role in the regulation of spine morphology (both shrinkage and enlargement) upon synaptic activation. In particular, actin depolymerization is crucial for the spine shrinkage in NMDAR-mediated synaptic depression. Here, we define the role of SPIN90 phosphorylation/dephosphorylation in regulating actin depolymerization via modulation of cofilin activity. When neurons were treated with NMDA, SPIN90 was dephosphorylated by STEP61 (striatal-enriched protein tyrosine phosphatase) and translocated from the spines to the dendritic shafts. In addition, phosphorylated SPIN90 bound cofilin and then inhibited cofilin activity, suggesting that SPIN90 dephosphorylation is a prerequisite step for releasing cofilin so that cofilin can adequately sever actin filaments into monomeric form. We found that SPIN90 YE, a phosphomimetic mutant, remained in the spines after NMDAR activation where it bound cofilin, thereby effectively preventing actin depolymerization. This led to inhibition of the activity-dependent redistribution of cortactin and drebrin A, as well as of the morphological changes in the spines that underlie synaptic plasticity. These findings indicate that NMDA-induced SPIN90 dephosphorylation and translocation initiates cofilin-mediated actin dynamics and spine shrinkage within dendritic spines, thereby modulating synaptic activity.     

Anti-adipogenesis by 6-thioinosine is mediated by downregulation of PPAR γ through JNK-dependent upregulation of iNOS

Adipocyte dysfunction is associated with the development of obesity. This study shows that 6-thioinosine inhibits adipocyte differentiation. The mRNA levels of PPAR γ and C/EBPα, but not C/EBPβ and δ, were reduced by 6-thioinosine. Moreover, the mRNA levels of PPAR γ target genes (LPL, CD36, aP2, and LXRα) were down-regulated by 6-thioinosine. We also demonstrated that 6-thioinosine inhibits the transactivation activity and the mRNA level of PPAR γ. Additionally, attempts to elucidate a possible mechanism underlying the 6-thioinosine-mediated effects revealed that 6-thioinosine induced iNOS gene expression without impacting eNOS expression, and that this was mediated through activation of AP-1, especially, JNK. In addition, 6-thioinosine was found to operate upstream of MEKK-1 in JNK activation signaling. Taken together, these findings suggest that the inhibition of adipocyte differentiation by 6-thioinosine occurs primarily through the reduced expression of PPAR γ, which is mediated by upregulation of iNOS via the activation of JNK.     

韩国伞滑刃属线虫的形态和分子特征

以锥尾伞滑刃线虫（Bursaphelenchus conicaudatus）作为对照,在韩国不同地域和寄主中采集了15个松材线虫分离物、3 个拟松材线虫的分离物及5个未鉴定的该属的分离物,并对其进行了ITS 和 D2D3 rDNA序列分析。以单条雌线虫的DNA为模板,ITS 和 D2D3 区由PCR仪扩增并克隆其序列。结果表明,所有松材线虫的ITS 和 D2D3 区序列相同,没有种内变异。然而2个采自黑松和红松的拟松材线虫分离物的基因型分别是亚洲型和欧洲型。5个未鉴定线虫的数据表明,它们分别接近B. tusciae、B. lini、B. thailandae、B. doui和 B. hylobianum,该结果同时被形态学结果所支持。利用5种酶（Hinf I、Alu I、Msp I、Hae III、Rsa）,PCR产物克隆并测序的数据也可以区分不同种和基因型。