An association between angiotensin II type 2 receptor gene A/C3123 polymorphism and glycemic control marker in a general Japanese population

Objective Angiotensin II (Ang II), through the Ang II type 2 receptor (AT2R), may play some roles in the pathogenesis of glucose metabolism and diabetes mellitus (DM). The Adenine/Cytosine 3123 (A/C3123) polymorphism in the AT2R gene has reportedly been associated with metabolic conditions such as blood pressure and body mass index (BMI). The present cross-sectional study was aimed at investigating the association between the AT2R gene A/C3123 polymorphism and glycemic control parameters. Methods Among 286 community-dwelling Japanese subjects (men: women = 126:160; mean age, 65.1 years), AT2R A/C3123 polymorphism, which was detected by polymerase chain reaction methods, and metabolic parameters such as blood pressure, BMI, lipoprotein/lipid, insulin, and glycemic control parameters (fasting plasma glucose and HbA1c) were examined. Results In the whole study population, the proportion of C-allele was 67.0% and A-allele was 33.0%. The A-allele carriers had significantly lower HbA1c levels than the C/C-genotyped subjects in the group of women (5.5 ± 0.6 vs. 5.8 ± 1.5%, P = 0.042). The effect on HbA1c persisted to be significant with adjustments to age and BMI. In men, the associations between the polymorphism and glycemic control parameters were non-significantly noted. There were no differences between genotype-based groups in the other metabolic parameters in both sexes. Conclusion These results suggest that the AT2R A/C3123 polymorphism could be a polymorphic marker related to glycemic control, as presented in HbA1c, among general Japanese women.     

The CLOCK 3111T/C single nucleotide polymorphism and daytime fluctuations of gastric motility in healthy young women: A preliminary study

The 3111T/C single nucleotide polymorphism (SNP) of Circadian Locomotor Output Cycles Kaput (CLOCK) gene reportedly affects gastric motility before breakfast. It is of interest to know whether this SNP can affect the motility during the daytime. We investigated the association between the CLOCK 3111T/C SNP and several gastric motility parameters during the time period from 8:00 to 20:00 in 34 young women with scheduled meals. There were similar daytime fluctuations in gastric motility before and after the meals between the major (T/T) and minor (T/C) allele carriers. The CLOCK SNP may affect daytime gastric motility less than food stimulation.     

ATP modulates load-inducible IL-1beta,COX 2, and MMP-3 gene expression in human tendon cells

Tendon cells receive mechanical signals from the load bearing matrices. The response to mechanical stimulation is crucial for tendon function. However, overloading tendon cells may deteriorate extracellular matrix integrity by activating intrinsic factors such as matrix metalloproteinases (MMPs) that trigger matrix destruction. We hypothesized that mechanical loading might induce interleukin-1beta (IL-1beta) in tendon cells, which can induce MMPs, and that extracellular ATP might inhibit the load-inducible gene expression. Human tendon cells isolated from flexor digitorum profundus tendons (FDPs) of four patients were made quiescent and treated with ATP (10 or 100 microM) for 5 min, then stretched equibiaxially (1 Hz, 3.5% elongation) for 2 h followed by an 18-h-rest period. Stretching induced IL-1beta, cyclooxygenase 2 (COX 2), and MMP-3 genes but not MMP-1. ATP reduced the load-inducible gene expression but had no effect alone. A medium change caused tendon cells to secrete ATP into the medium, as did exogenous UTP. The data demonstrate that mechanical loading induces ATP release in tendon cells and stimulates expression of IL-1beta, COX 2, and MMP-3. Load-induced endogenous IL-1beta may trigger matrix remodeling or a more destructive pathway(s) involving IL-1beta, COX 2, and MMP-3. Concomitant autocrine and paracrine release of ATP may serve as a negative feedback mechanism to limit activation of such an injurious pathway. Attenuation or failure of this negative feedback mechanism may result in the progression to tendinosis.     

Rabbit tendon cells produce MMP-3 in response to fluid flow without significant calcium transients

Forces applied to tendon during movement cause cellular deformation, as well as fluid movement. The goal of this study was to test the hypothesis that rabbit tendon fibroblasts detect and respond to fluid-induced shear stress. Cells were isolated from the paratenon of the rabbit Achilles tendon and then subjected to fluid flow at 1 dyn/cm(2) for 6h in a specially designed multi-slide flow device. The application of fluid flow led to an increased expression of the collagenase-1 (MMP-1), stromelysin-1 (MMP-3), cyclooxygenase II (COX-2) and interleukin-1beta (IL-1beta) genes. The release of proMMP-3 into the medium exhibited a dose-response with the level of fluid shear stress. However, not all cells aligned in the direction of flow. In other experiments, the same cells were incubated with the calcium-reactive dye FURA-2 AM, then subjected to laminar fluid flow in a parallel plate flow chamber. The cells did not significantly increase intracellular calcium concentration when exposed to fluid shear stress levels of up to 25 dyn/cm(2). These results show that gene expression in rabbit tendon cells is sensitive to fluid flow, but that signal transduction is not dependent on intracellular calcium transients. The upregulation of the MMP-1, MMP-3 and COX-2 genes shows that fluid flow could be an important mechanical stimulus for tendon remodelling or injury.     

Circadian Rhythm Genes CLOCK and PER3 Polymorphisms and Morning Gastric Motility in Humans

Background

Clock genes regulate circadian rhythm and are involved in various physiological processes, including digestion. We therefore investigated the association between the CLOCK 3111T/C single nucleotide polymorphism and the Period3 (PER3) variable-number tandem-repeat polymorphism (either 4 or 5 repeats 54 nt in length) with morning gastric motility.

Methods

Lifestyle questionnaires and anthropometric measurements were performed with 173 female volunteers (mean age, 19.4 years). Gastric motility, evaluated by electrogastrography (EGG), blood pressure, and heart rate levels were measured at 8:30 a.m. after an overnight fast. For gastric motility, the spectral powers (% normal power) and dominant frequency (DF, peak of the power spectrum) of the EGG were evaluated. The CLOCK and PER3 polymorphisms were determined by polymerase chain reaction (PCR) restriction fragment length polymorphism analysis.

Results

Subjects with the CLOCK C allele (T/C or C/C genotypes: n = 59) showed a significantly lower DF (mean, 2.56 cpm) than those with the T/T genotype (n = 114, 2.81 cpm, P < 0.05). Subjects with the longer PER3 allele (PER3 ^4/5 or PER3 ^5/5 genotypes: n = 65) also showed a significantly lower DF (2.55 cpm) than those with the shorter PER3 ^4/4 genotype (n = 108, 2.83 cpm, P < 0.05). Furthermore, subjects with both the T/C or C/C and PER3 ^4/5 or PER3 ^5/5 genotypes showed a significantly lower DF (2.43 cpm, P < 0.05) than subjects with other combinations of the alleles (T/T and PER3 ^4/4 genotype, T/C or C/C and PER3 ^4/4 genotypes, and T/T and PER3 ^4/5 or PER3 ^5/5 genotypes).

Conclusions

These results suggest that minor polymorphisms of the circadian rhythm genes CLOCK and PER3 may be associated with poor morning gastric motility, and may have a combinatorial effect. The present findings may offer a new viewpoint on the role of circadian rhythm genes on the peripheral circadian systems, including the time-keeping function of the gut.     

Quantitative Trait Loci (QTL) Associated with Resistance to a Monogenean Parasite (Benedenia seriolae) in Yellowtail (Seriola quinqueradiata) through Genome Wide Analysis

Benedenia infections caused by the monogenean fluke ectoparasite Benedenia seriolae seriously impact marine finfish aquaculture. Genetic variation has been inferred to play a significant role in determining the susceptibility to this parasitic disease. To evaluate the genetic basis of Benedenia disease resistance in yellowtail (Seriola quinqueradiata), a genome-wide and chromosome-wide linkage analyses were initiated using F₁ yellowtail families (n = 90 per family) based on a high-density linkage map with 860 microsatellite and 142 single nucleotide polymorphism (SNP) markers. Two major quantitative trait loci (QTL) regions on linkage groups Squ2 (BDR-1) and Squ20 (BDR-2) were identified. These QTL regions explained 32.9–35.5% of the phenotypic variance. On the other hand, we investigated the relationship between QTL for susceptibility to B. seriolae and QTL for fish body size. The QTL related to growth was found on another linkage group (Squ7). As a result, this is the first genetic evidence that contributes to detailing phenotypic resistance to Benedenia disease, and the results will help resolve the mechanism of resistance to this important parasitic infection of yellowtail.     

Linking behaviour and performance: intermittent locomotion in a climbing fish

How locomotory performance is influenced by prior experience and behaviour is of adaptive significance. The relationship between kinematics, behaviour and performance was investigated by assessing a previously undescribed mode of climbing locomotion performed by adult Pacific lamprey. The lampreys were challenged with a 1.4 m vertical weir under an experimental setting. The majority of ascents used intermittent bouts of climbing (on an average approximately one-fifth of total ascent time) via powerful cycles of axial undulation at 0.35–1.25 Hz, interspersed with periods of stationary attachment with the oral disk. However, two of the most rapid ascents (57 and 85 s) occurred during one continuous bout at a low cycle frequency ( c . 0.38 and 0.50 Hz). Probability of success and ascent time was positively related to experience climbing the weir. The ratio of time spent actively climbing to time spent resting decreased with distance travelled, indicating fatigue. Ascents with long periods of activity had correspondingly high durations of recovery. Moreover, time to ascend was positively related to the proportion of time spent stationary in ascents that took <300 s. The findings suggest that modification of intermittent locomotion allows Pacific lamprey to compensate for variation in climbing performance and can extend distance travelled before exhaustion.     

Structure of the N-terminal Regulatory Domain of a Plant NADPH Oxidase and Its Functional Implications

Plant NADPH oxidases (Rboh, for respiratory burst oxidase homolog) produce reactive oxygen species that are key regulators of various cellular events including plant innate immunity. Rbohs possess a highly conserved cytoplasmic N-terminal region containing two EF-hand motifs that regulate Rboh activity. Rice (Oryza sativa) RbohB (OsRbohB) is regulated by the direct binding of a small GTPase (Rac1) to this regulatory region as well as by Ca²⁺ binding to the EF-hands. Here, we present the atomic structure of the N-terminal region of OsRbohB. The structure reveals that OsRbohB forms a unique dimer stabilized by swapping the EF-hand motifs. We identified two additional EF-hand-like motifs that were not predicted from sequence data so far. These EF-hand-like motifs together with the swapped EF-hands form a structure similar to that found in calcineurin B. We observed conformational changes mediated by Ca²⁺ binding to only one EF-hand. Structure-based in vitro pulldown assays and NMR titration experiments defined the OsRac1 binding interface within the coiled-coil region created by swapping the EF-hands. In addition, we demonstrate a direct intramolecular interaction between the N and C terminus, and that the complete N-terminal cytoplasmic region is required for this interaction. The structural features and intramolecular interactions characterized here might be common elements shared by Rbohs that contribute to the regulation of reactive oxygen species production.     

Distribution of Archaea in Japanese patients with periodontitis and humoral immune response to the components

There is controversy regarding the existence of archaeal pathogens. Periodontitis is one of the human diseases in which Archaea have been suggested to have roles as pathogens. This study was performed to investigate the distribution of Archaea in Japanese patients with periodontitis and to examine the serum IgG responses to archaeal components. Subgingival plaque samples were collected from 111 periodontal pockets of 49 patients (17 with aggressive periodontitis and 32 with chronic periodontitis), and 30 subgingival plaque samples were collected from 17 healthy subjects. By PCR targeting the 16S rRNA gene, Archaea were detected in 15 plaque samples (13.5% of total samples) from 11 patients (29.4% of patients with aggressive periodontitis and 18.8% of patients with chronic periodontitis). Archaea were detected mostly (14/15) in severe diseased sites (pocket depth >/=6 mm), while no amplicons were observed in any samples from healthy controls. Sequence analysis of the PCR products revealed that the majority of Archaea in periodontal pockets were a Methanobrevibacter oralis-like phylotype. Western immunoblotting detected IgG antibodies against M. oralis in eight of the 11 sera from patients. These results suggest the potential of Archaea (M. oralis) as an antigenic pathogen of periodontitis.