Effect of Cationic Comb-Type Copolymer on Quadruplex Folding of Human Telomeric DNA

Cationic comb-type copolymer (CCC) consisting of a polycationic backbone and abundant graft water-soluble chains exhibited considerable stabilization effect on DNA hybrids, such as double- and triple-stranded DNAs. Here, we describe the effect of CCC on antiparallel G-quadruplex folding of human telomeric DNA, d(GGGTTA) _n in the presence of sodium ions. CCC did not significantly alter the circular dichroism (CD) spectra of d((GGGTTA) ₃ GGG) and d((GGGTTA)₇GGG) indicating that the CCC did not influence the antiparallel folding of the telomeric repeats. Hence, the ionic interaction of CCC with the DNA sequence did not interfere with specific interaction of the DNA with sodium ions to form G-quartets. Interestingly, CCC did not change the melting temperature of the d((GGGTTA) ₃ GGG) suggesting negligible stabilizing effect of CCC on the antiparallel quadruplex structure.     

Comparison between integrated backscatter intravascular ultrasound and 64-slice multi-detector row computed tomography for tissue characterization and volumetric assessment of coronary plaques

ABSTRACT: BACKGROUND: The purpose of this study was to determine the cut-off values of Hounsfield units (HU) for the discrimination of plaque components and to evaluate the feasibility of measurement of the volume of plaque components using multi-detector row computed tomography (MDCT). Methods: Coronary lesions (125 lesions in 125 patients) were visualized by both integrated backscatter intravascular ultrasound (IB-IVUS) and 64-slice MDCT at the same site. The IB values were used as a gold standard to determine the cut off values of HU for the discrimination of plaque components. Results: Plaques were classified as lipid pool (n =50), fibrosis (n =65) or calcification (n =35) by IB-IVUS. The HU of lipid pool, fibrosis and calcification were 18 +/- 18 HU (-19 to 58 HU), 95 +/- 24 HU (46 to 154 HU) and 378 +/- 99 HU (188 to 605 HU), respectively. Using receiver operating characteristic curve analysis, a threshold of 50 HU was the optimal cutoff values to discriminate lipid pool from fibrosis. Lipid volume measured by MDCT was correlated with that measured by IB-IVUS (r =0.66, p <0.001), whereas fibrous volume was not (r =0.21, p =0.059). Conclusion: Lipid volume measured by MDCT was moderately correlated with that measured by IB-IVUS. MDCT may be useful for volumetric assessment of the lipid volume of coronary plaques, whereas the assessment of fibrosis volume was unstable.     

ZEITLUPE positively regulates hypocotyl elongation at warm temperature under light in Arabidopsis thaliana

Hypocotyl cell elongation has been studied as a model to understand how cellular expansion contributes to plant organ growth. Hypocotyl elongation is affected by multiple environmental factors, including light quantity and light quality. Red light inhibits hypocotyl growth via the phytochrome signaling pathways. Proteins of the FLAVIN-BINDING KELCH REPEAT F-BOX 1 / LOV KELCH PROTEIN 2 / ZEITLUPE family are positive regulators of hypocotyl elongation under red light in Arabidopsis. These proteins were suggested to reduce phytochrome-mediated inhibition of hypocotyl elongation. Here, we show that ZEITLUPE also functions as a positive regulator in warmth-induced hypocotyl elongation under light in Arabidopsis.     

Isolation and identification of two potential phytotoxic substances from the aquatic fern <Emphasis Type="Italic">Marsilea crenata</Emphasis>

Organic agriculture emphasized using of biologically originated herbicides and phytotoxic substances are being considered as a replacement to chemical herbicides. Marsilea crenata is an aquatic perennial fern distributed in the South-East Asian countries and is well known for various biological properties. However, to date, there has been no report that addresses the phytotoxicity of Marsilea crenata. Therefore, we explored phytotoxic properties and phytotoxic substances from Marsilea crenata. An aqueous methanol extracts of Marsilea crenata showed inhibition on the seedling growth of cress, lettuce, alfalfa, barnyard grass, Italian ryegrass, and foxtail fescue. Inhibition increased with increasing extract concentration. The extract was purified by several chromatographic steps and two phytotoxic substances were isolated and identified by spectroscopic analysis as loliolide and isololiolide. At the concentration of 30 μM, loliolide and isololiolide inhibited seedling growth of cress and barnyard grass by 41.3 to 51.1%, and 58.15 to 87.5% of control seedlings, respectively. The concentrations required for 50% inhibition of cress and barnyard grass seedlings ranged from 32.1 to 128.5 μM for loliolide, 37.0 to 176.2 μM for isololiolide. These results suggest these compounds may be responsible for phytotoxic effects of Marsilea crenata extract and could be an important part of organic agriculture.     

Thiol-based SAHA analogues as potent histone deacetylase inhibitors

In order to find novel nonhydroxamate histone deacetylase (HDAC) inhibitors, a series of thiol-based compounds modeled after suberoylanilide hydroxamic acid (SAHA) was synthesized, and their inhibitory effect on HDACs was evaluated. Compound 6, in which the hydroxamic acid of SAHA was replaced by a thiol, was found to be as potent as SAHA, and optimization of this series led to the identification of HDAC inhibitors more potent than SAHA.     

Typing of hepatic nonparenchymal cells using fibulin-2 and cytoglobin/STAP as liver fibrogenesis-related markers

Fibulin-2 and cytoglobin/stellate cell activation-associated protein (Cygb/STAP) are considered to be markers of hepatic myofibroblasts (MFs) and stellate cells (HSCs), respectively. The aim of the present study was to characterize the nonparenchymal cells (NPCs) of normal rat livers and carbon tetrachloride-induced fibrotic rat livers with respect to the expression of these two proteins. NPCs in normal (Glissons capsules) and fibrotic (fibrotic septa) connective tissues were immunohistochemically categorized into four cell types in terms of the expression of fibulin-2 and Cygb/STAP: fibulin-2 and Cygb/STAP double-positive (Fib⁺/STAP⁺); fibulin-2-positive and Cygb/STAP-negative (Fib⁺/STAP^–); Fib^–/STAP⁺; and Fib^–/STAP^–. The Glissons capsules had Fib⁺/STAP⁺ and Fib^–/STAP^– cell occupancy rates of 45.5% and 54.5%, respectively, but did not contain Fib⁺/STAP^– or Fib^–/STAP⁺ cells. On the other hand, the fibrotic septa contained Fib⁺/STAP⁺, Fib^–/STAP⁺, and Fib^–/STAP^– cells at occupancy rates of 35.0%, 50.5%, and 9.1%, respectively, but did not contain Fib⁺/STAP^– cells. Thus, fibrosis is characterized by a dramatic increase in Fib^–/STAP⁺ NPCs, and a dramatic decrease in Fib^–/STAP^– NPCs. Fib⁺/STAP⁺ NPCs are located uniformly in Glissons capsules and peripherally in fibrotic septa. The present study strongly suggests that Fib⁺/STAP⁺ and Fib^–/STAP⁺ NPCs correspond to MFs and activated HSCs, respectively, both of which may contribute to liver fibrogenesis.     

Chloroplast unusual positioning1 is essential for proper chloroplast positioning

The intracellular distribution of organelles is a crucial aspect of effective cell function. Chloroplasts change their intracellular positions to optimize photosynthetic activity in response to ambient light conditions. Through screening of mutants of Arabidopsis defective in chloroplast photorelocation movement, we isolated six mutant clones in which chloroplasts gathered at the bottom of the cells and did not distribute throughout cells. These mutants, termed chloroplast unusual positioning (chup), were shown to belong to a single genetic locus by complementation tests. Observation of the positioning of other organelles, such as mitochondria, peroxisomes, and nuclei, revealed that chloroplast positioning and movement are impaired specifically in this mutant, although peroxisomes are distributed along with chloroplasts. The CHUP1 gene encodes a novel protein containing multiple domains, including a coiled-coil domain, an actin binding domain, a Pro-rich region, and two Leu zipper domains. The N-terminal hydrophobic segment of CHUP1 was expressed transiently in leaf cells of Arabidopsis as a fusion protein with the green fluorescent protein. The fusion protein was targeted to envelope membranes of chloroplasts in mesophyll cells, suggesting that CHUP1 may localize in chloroplasts. A glutathione S-transferase fusion protein containing the actin binding domain of CHUP1 was found to bind F-actin in vitro. CHUP1 is a unique gene identified that encodes a protein required for organellar positioning and movement in plant cells.