Helicobacter pylori infection triggers aberrant expression of activation-induced cytidine deaminase in gastric epithelium

Infection with Helicobacter pylori (H. pylori) is a risk factor for the development of gastric cancer. Here we show that infection of gastric epithelial cells with 'cag' pathogenicity island (cagPAI)-positive H. pylori induced aberrant expression of activation-induced cytidine deaminase (AID), a member of the cytidine-deaminase family that acts as a DNA- and RNA-editing enzyme, via the IkappaB kinase-dependent nuclear factor-kappaB activation pathway. H. pylori-mediated upregulation of AID resulted in the accumulation of nucleotide alterations in the TP53 tumor suppressor gene in gastric cells in vitro. Our findings provide evidence that aberrant AID expression caused by H. pylori infection might be a mechanism of mutation accumulation in the gastric mucosa during H. pylori-associated gastric carcinogenesis.     

Loureirin C and Xanthoceraside Attenuate Depression-Like Behaviors and Expression of Interleukin-17 in the Prefrontal Cortex Induced by Chronic Unpredictable Mild Stress in Mice

Neurochemical Research - Major depressive disorder (MDD) is the most prevalent and serious psychiatric disease involving inflammation. Loureirin C and Xanthoceraside are extracts of dragon’s...     

Structural basis for acceptor‐substrate recognition of UDP‐glucose: anthocyanidin 3‐O‐glucosyltransferase from Clitoria ternatea

UDP‐glucose: anthocyanidin 3‐O‐glucosyltransferase (UGT78K6) from Clitoria ternatea catalyzes the transfer of glucose from UDP‐glucose to anthocyanidins such as delphinidin. After the acylation of the 3‐O‐glucosyl residue, the 3′‐ and 5′‐hydroxyl groups of the product are further glucosylated by a glucosyltransferase in the biosynthesis of ternatins, which are anthocyanin pigments. To understand the acceptor‐recognition scheme of UGT78K6, the crystal structure of UGT78K6 and its complex forms with anthocyanidin delphinidin and petunidin, and flavonol kaempferol were determined to resolutions of 1.85 Å, 2.55 Å, 2.70 Å, and 1.75 Å, respectively. The enzyme recognition of unstable anthocyanidin aglycones was initially observed in this structural determination. The anthocyanidin‐ and flavonol‐acceptor binding details are almost identical in each complex structure, although the glucosylation activities against each acceptor were significantly different. The 3‐hydroxyl groups of the acceptor substrates were located at hydrogen‐bonding distances to the Nε2 atom of the His17 catalytic residue, supporting a role for glucosyl transfer to the 3‐hydroxyl groups of anthocyanidins and flavonols. However, the molecular orientations of these three acceptors are different from those of the known flavonoid glycosyltransferases, VvGT1 and UGT78G1. The acceptor substrates in UGT78K6 are reversely bound to its binding site by a 180° rotation about the O1–O3 axis of the flavonoid backbones observed in VvGT1 and UGT78G1; consequently, the 5‐ and 7‐hydroxyl groups are protected from glucosylation. These substrate recognition schemes are useful to understand the unique reaction mechanism of UGT78K6 for the ternatin biosynthesis, and suggest the potential for controlled synthesis of natural pigments.     

Polyethylene glycol and electric field treatment of plant protoplasts: characterization of some membrane properties

Petiolar protoplasts of a dihaploid line of winter oilseed rape Brassica napus L. ssp. oleifera were exposed to fusogenic polyethylene glycol (PEG) and electric field treatments. The surface properties and stability of membrane components of the treated protoplasts were investigated by contact angle measurements in aqueous two-phase systems and differential scanning calorimetry, respectively. The leakage of intracellular components was estimated with respect to amino acids, proteins and DNA. Both fusogenic treatments resulted in the same apparent changes in membrane surface hydrophobicity and the same destabilization of membrane components. However, the PEG-treated protoplasts were more leaky than both the control and the electric field-treated protoplasts. The results indicate that the molecular mechanisms of PEG- and electrical field-induced fusion are similar. However, the effects of the latter appear to be less harmful presumably because the parameters for electric field treatment are more easily controlled.     

Apartment electrical wiring: a cause of extremely low frequency magnetic field exposure in residential areas

Extremely low frequency (ELF) magnetic fields (MFs) were measured at 696 points in a room of a Japanese apartment building. The building had 124 rooms with layouts and wiring identical to those of the studied room. ELF-MFs exceeded 0.4 microT in 24% of the living space, and the maximum value, 1.8 microT, was detected at floor level. Analysis of the MF distribution revealed that 60 Hz 100 V electrical wiring for room lights within the floor and ceiling had been laid out in large rectangles, equivalent to 1 turn coils. Further plotting of the vertical components every 0.01 m on the floor indicated that the depth of the cable was 0.23 m. Further studies should be conducted in order to confirm that the building investigated in this pilot study is typical of Japanese apartment buildings in terms of ELF-MFs.     

G-protein gamma subunit 1 is required for sugar reception in Drosophila

Though G-proteins have been implicated in the primary step of taste signal transduction, no direct demonstration has been done in insects. We show here that a G-protein gamma subunit, Ggamma1, is required for the signal transduction of sugar taste reception in Drosophila. The Ggamma1 gene is expressed mainly in one of the gustatory receptor neurons. Behavioral responses of the flies to sucrose were reduced by the targeted suppression of neural functions of Ggamma1-expressing cells using neural modulator genes such as the modified Shaker K+ channel (EKO), the tetanus toxin light chain or the shibire (shi(ts1)) gene. RNA interference targeting to the Ggamma1 gene reduced the amount of Ggamma1 mRNA and suppressed electrophysiological response of the sugar receptor neuron. We also demonstrated that responses to sugars were lowered in Ggamma1 null mutant, Ggamma1(N159). These results are consistent with the hypothesis that Ggamma1 participates in the signal transduction of sugar taste reception.