Association of the variant rs2243421 of human DOC-2/DAB2 interactive protein gene (hDAB2IP) with gastric cancer in the Chinese Han population

Human DOC-2/DAB2 interactive protein (hDAB2IP) gene is a novel member of the Ras GTPase-activating family and has been demonstrated to be a tumor-suppressor gene that inhibits cell survival and proliferation and induces cell apoptosis. It was reported that the expression level of hDAB2IP in gastric cancer tissue was highly correlated with tumor progression, however, whether hDAB2IP genetic variants are associated with the risk of gastric cancer remains yet unknown. In this case–control study, we conducted a genetic analysis for hDAB2IP variants in 311 patients with gastric cancer and 425 controls from the Chinese Han population. We found that the SNP rs2243421 of hDAB2IP gene with the minor allele C significantly revealed strong association with decreased gastric cancer susceptibility (P = 0.007, adjusted odds ratio [OR] = 0.734, 95%CI = 0.586–0.919). Haplotypes rs2243421 and rs10985332 (HaploType: CC, P = 0.012, aOR = 0.760) and haplotypes rs2243421 and rs555996 (HaploType: CG, P = 0.034, aOR = 0.788) represented the decreased risk of gastric cancer, respectively. On the contrary, rs2243421 and rs555996 showed an elevated susceptibility (HaploType: TG, P = 0.010, aOR = 1.320). Our results for the first time provided new insight into susceptibility factors of hDAB2IP gene variants in carcinogenesis of gastric cancer.     

Irreversible Changes Occur in Chromatin Structure Upon Dissociation Of Histone H1

Abstract

The role of histone H1 in the actual interactions bringing about chromatin folding is investigated by studying the reversibility of its dissociation. HI was dissociated by increase of the NaCl concentration and reassociated by dialysis, without removal from the dialysis bag. To scrutinize the fidelity of this stoichiometric form of chromatin reconstitution, we use circular dichroism, nuclease digestion, thermal denaturation and the sensitive electric birefringence method. No alteration of the repeat length and no nucleosomal sliding are observed upon the reassociation procedure. However, under all the different conditions investigated, the original value of the positive electric birefringence is never recovered, indicating an irreversible change of structure. CD and melting profiles confirm that DNA-protein interactions are modified, and orientational relaxation time measurements indicate that these structural perturbations affect the salt- induced transition of poly nucleosomal fibers. The striking conclusion of these studies is that variations of ionic concentration are sufficient to induce irreversible structural alterations affecting the higher-order folding of chromatin. It is of interest that the only sample which exhibits behavior upon reassociation comparable to that of native chromatin is the one which experienced the fastest salt transitions. We suggest that these conformational changes arise from the unbinding to DNA of certain basic tails of histone(s), and that a competition for DNA binding locations exists upon the reassociation. These results are then additional arguments (Mazen, A., Hacques, M.F. and Marion, C., J. Mol. Biol. 194, 741–745 (1987)), to suggest that dissociation of H1 might modify a direct interaction between basic tails of core histones and H1.     

Settlement Behaviour of Marine Invertebrate Larvae Measured by EthoVision 3.0

Submerged marine surfaces are rapidly colonized by fouling organisms. Current research is aimed at finding new, non-toxic, or at least environmentally benign, solutions to this problem. Barnacles are a major target organism for such control as they constitute a key component of the hard fouling community. A range of standard settlement assays is available for screening test compounds against barnacle cypris larvae, but they generally provide little information on mechanism(s) of action. Towards this end, a quick and reliable video-tracking protocol has been developed to study the behaviour of the cypris larvae of the barnacle, Balanus amphitrite, at settlement. EthoVision 3.0 was used to track individual cyprids in 30-mm Petri dishes. Experiments were run to determine the optimal conditions vis-à-vis acclimation time, tracking duration, number of replicates, temperature and lighting. A protocol was arrived at involving a two Petri dish system with backlighting, and tracking over a 5-min period after first acclimating the cyprids to test conditions for 2 min. A minimum of twenty replicates was required to account for individual variability in cyprid behaviour from the same batch of larvae. This methodology should be widely applicable to both fundamental and applied studies of larval settlement and with further refinements, to that of smaller fouling organisms such as microalgae and bacteria.     

Characterization of a Serine Hydrolase Targeted by Acyl-protein Thioesterase Inhibitors in Toxoplasma gondii

In eukaryotic organisms, cysteine palmitoylation is an important reversible modification that impacts protein targeting, folding, stability, and interactions with partners. Evidence suggests that protein palmitoylation contributes to key biological processes in Apicomplexa with the recent palmitome of the malaria parasite Plasmodium falciparum reporting over 400 substrates that are modified with palmitate by a broad range of protein S-acyl transferases. Dynamic palmitoylation cycles require the action of an acyl-protein thioesterase (APT) that cleaves palmitate from substrates and conveys reversibility to this posttranslational modification. In this work, we identified candidates for APT activity in Toxoplasma gondii. Treatment of parasites with low micromolar concentrations of β-lactone- or triazole urea-based inhibitors that target human APT1 showed varied detrimental effects at multiple steps of the parasite lytic cycle. The use of an activity-based probe in combination with these inhibitors revealed the existence of several serine hydrolases that are targeted by APT1 inhibitors. The active serine hydrolase, TgASH1, identified as the homologue closest to human APT1 and APT2, was characterized further. Biochemical analysis of TgASH1 indicated that this enzyme cleaves substrates with a specificity similar to APTs, and homology modeling points toward an APT-like enzyme. TgASH1 is dispensable for parasite survival, which indicates that the severe effects observed with the β-lactone inhibitors are caused by the inhibition of non-TgASH1 targets. Other ASH candidates for APT activity were functionally characterized, and one of them was found to be resistant to gene disruption due to the potential essential nature of the protein.     

Replication and trafficking of a plant virus are coupled at the entrances of plasmodesmata

Plant viruses use movement proteins (MPs) to modify intercellular pores called plasmodesmata (PD) to cross the plant cell wall. Many viruses encode a conserved set of three MPs, known as the triple gene block (TGB), typified by Potato virus X (PVX). In this paper, using live-cell imaging of viral RNA (vRNA) and virus-encoded proteins, we show that the TGB proteins have distinct functions during movement. TGB2 and TGB3 established endoplasmic reticulum–derived membranous caps at PD orifices. These caps harbored the PVX replicase and nonencapsidated vRNA and represented PD-anchored viral replication sites. TGB1 mediated insertion of the viral coat protein into PD, probably by its interaction with the 5′ end of nascent virions, and was recruited to PD by the TGB2/3 complex. We propose a new model of plant virus movement, which we term coreplicational insertion, in which MPs function to compartmentalize replication complexes at PD for localized RNA synthesis and directional trafficking of the virus between cells.     

The Dok-3/Grb2 Protein Signal Module Attenuates Lyn Kinase-dependent Activation of Syk Kinase in B Cell Antigen Receptor Microclusters

Recruitment of the growth factor receptor-bound protein 2 (Grb2) by the plasma membrane-associated adapter protein downstream of kinase 3 (Dok-3) attenuates signals transduced by the B cell antigen receptor (BCR). Here we describe molecular details of Dok-3/Grb2 signal integration and function, showing that the Lyn-dependent activation of the BCR transducer kinase Syk is attenuated by Dok-3/Grb2 in a site-specific manner. This process is associated with the SH3 domain-dependent translocation of Dok-3/Grb2 complexes into BCR microsignalosomes and augmented phosphorylation of the inhibitory Lyn target SH2 domain-containing inositol 5′ phosphatase. Hence, our findings imply that Dok-3/Grb2 modulates the balance between activatory and inhibitory Lyn functions with the aim to adjust BCR signaling efficiency.     

Rapid Detection of Ceratocystis platani Inoculum by Quantitative Real-Time PCR Assay

Ceratocystis platani is the causal agent of canker stain of plane trees, a lethal disease able to kill mature trees in one or two successive growing seasons. The pathogen is a quarantine organism and has a negative impact on anthropogenic and natural populations of plane trees. Contaminated sawdust produced during pruning and sanitation fellings can contribute to disease spread. The goal of this study was to design a rapid, real-time quantitative PCR assay to detect a C. platani airborne inoculum. Airborne inoculum traps (AITs) were placed in an urban setting in the city of Florence, Italy, where the disease was present. Primers and TaqMan minor groove binder (MGB) probes were designed to target cerato-platanin (CP) and internal transcribed spacer 2 (ITS2) genes. The detection limits of the assay were 0.05 pg/μl and 2 fg/μl of fungal DNA for CP and ITS, respectively. Pathogen detection directly from AITs demonstrated specificity and high sensitivity for C. platani, detecting DNA concentrations as low as 1.2 × 10⁻² to 1.4 × 10⁻² pg/μl, corresponding to ∼10 conidia per ml. Airborne inoculum traps were able to detect the C. platani inoculum within 200 m of the closest symptomatic infected plane tree. The combination of airborne trapping and real-time quantitative PCR assay provides a rapid and sensitive method for the specific detection of a C. platani inoculum. This technique may be used to identify the period of highest risk of pathogen spread in a site, thus helping disease management.