Rheb (Ras Homologue Enriched in Brain)-dependent Mammalian Target of Rapamycin Complex 1 (mTORC1) Activation Becomes Indispensable for Cardiac Hypertrophic Growth after Early Postnatal Period

Cardiomyocytes proliferate during fetal life but lose their ability to proliferate soon after birth and further increases in cardiac mass are achieved through an increase in cell size or hypertrophy. Mammalian target of rapamycin complex 1 (mTORC1) is critical for cell growth and proliferation. Rheb (Ras homologue enriched in brain) is one of the most important upstream regulators of mTORC1. Here, we attempted to clarify the role of Rheb in the heart using cardiac-specific Rheb-deficient mice (Rheb^−/−). Rheb^−/− mice died from postnatal day 8 to 10. The heart-to-body weight ratio, an index of cardiomyocyte hypertrophy, in Rheb^−/− was lower than that in the control (Rheb^+/+) at postnatal day 8. The cell surface area of cardiomyocytes isolated from the mouse hearts increased from postnatal days 5 to 8 in Rheb^+/+ mice but not in Rheb^−/− mice. Ultrastructural analysis indicated that sarcomere maturation was impaired in Rheb^−/− hearts during the neonatal period. Rheb^−/− hearts exhibited no difference in the phosphorylation level of S6 or 4E-BP1, downstream of mTORC1 at postnatal day 3 but showed attenuation at postnatal day 5 or 8 compared with the control. Polysome analysis revealed that the mRNA translation activity decreased in Rheb^−/− hearts at postnatal day 8. Furthermore, ablation of eukaryotic initiation factor 4E-binding protein 1 in Rheb^−/− mice improved mRNA translation, cardiac hypertrophic growth, sarcomere maturation, and survival. Thus, Rheb-dependent mTORC1 activation becomes essential for cardiomyocyte hypertrophic growth after early postnatal period.     

Rediagnosis of the monotypic genus Lepadicyathus Prokofiev 2005 (Gobiesocidae: Diademichthyinae) and redescription of Lepadicyathus minor (Briggs 1955), new combination

Ichthyological Research - A revised diagnosis is provided for the poorly known clingfish genus Lepadicyathus Prokofiev 2005. The genus belongs to Diademichthyinae (sensu Conway et al.) and is...     

Chloroplast phylogeny indicates that bryophytes are monophyletic

Opinions on the basal relationship of land plants vary considerably and no phylogenetic tree with significant statistical support has been obtained. Here, we report phylogenetic analyses using 51 genes from the entire chloroplast genome sequences of 20 representative green plant species. The analyses, using translated amino acid sequences, indicated that extant bryophytes (mosses, liverworts, and hornworts) form a monophyletic group with high statistical confidence and that extant bryophytes are likely sisters to extant vascular plants, although the support for monophyletic vascular plants was not strong. Analyses at the nucleotide level could not resolve the basal relationship with statistical confidence. Bryophyte monophyly inferred using amino acid sequences has a good statistical foundation and is not rejected statistically by other data sets. We propose bryophyte monophyly as the currently best hypothesis.     

Evaluation of systemic blood NO dynamics by EPR spectroscopy: HbNO as an endogenous index of NO

The measurement of hemoglobin-nitric oxide (NO) adduct (HbNO) in whole blood by the electron paramagnetic resonance (EPR) method seems relevant for the assessment of systemic NO levels. However, ceruloplasmin and unknown radical species overlap the same magnetic field as that of HbNO. To reveal the EPR spectrum of HbNO, we then introduced the EPR signal subtraction method, which is based on the computer-assisted subtraction of the digitized EPR spectrum of HbNO-depleted blood from that of sample blood using the software. Rats were treated with N(omega)-nitro-L-arginine methyl ester (L-NAME; 120 mg. kg-1. day-1) for 1 wk to obtain HbNO-depleted blood. When this method was applied to the analysis of untreated fresh whole blood, the five-coordinate state of HbNO was observed. HbNO concentration in pentobarbital-anesthetized rats was augmented (change in [HbNO] = 1.6-5.5 microM) by infusion of L-arginine (0.2-0.6 g/kg) but not D-arginine. Using this method, we attempted to evaluate the effects of temocapril on HbNO dynamics in an L-NAME-induced rat endothelial dysfunction model. The oral administration of L-NAME for 2 wk induced a serious hypertension, and the HbNO concentration was reduced (change in [HbNO] = 5.7 microM). Coadministration of temocapril dose dependently improved both changes in blood pressure and the systemic HbNO concentration. In this study, we succeeded in measuring the blood HbNO level as an index of NO by the EPR HbNO signal subtraction method. We also demonstrated that temocapril improves abnormalities of NO dynamics in L-NAME-induced endothelial dysfunction rats using the EPR HbNO signal subtraction method.     

Proteasome activator PA28gamma-dependent nuclear retention and degradation of hepatitis C virus core protein

Hepatitis C virus (HCV) core protein plays an important role in the formation of the viral nucleocapsid and a regulatory protein involved in hepatocarcinogenesis. In this study, we have identified proteasome activator PA28gamma (11S regulator gamma) as an HCV core binding protein by using yeast two-hybrid system. This interaction was demonstrated not only in cell culture but also in the livers of HCV core transgenic mice. These findings are extended to human HCV infection by the observation of this interaction in liver specimens from a patient with chronic HCV infection. Neither the interaction of HCV core protein with other PA28 subtypes nor that of PA28gamma with other Flavivirus core proteins was detected. Deletion of the PA28gamma-binding region from the HCV core protein or knockout of the PA28gamma gene led to the export of the HCV core protein from the nucleus to the cytoplasm. Overexpression of PA28gamma enhanced the proteolysis of the HCV core protein. Thus, the nuclear retention and stability of the HCV core protein is regulated via a PA28gamma-dependent pathway through which HCV pathogenesis may be exerted.     

Influence of GnRH analogue (fertirelin acetate) doses on synchronization of ovulation and fixed-time artificial insemination in lactating dairy cows

The effect of using a dose of 50 micro g rather than 100 micro g fertirelin in an ovulation/fixed-time insemination protocol for Holstein-Friesian dairy cows was investigated in three experiments. In each experiment, fertirelin was administered at the beginning of the protocol followed 7 days later by 500 micro g cloprosterol. Two days later, a second dose of fertirelin was given and AI performed 16-19 h later regardless of the incidence of behavioral oestrus.The effect on conception rate was studied in experiment 1 using 114 postpartum anoestrus cows. There was no significant difference in the age, parity or number of days after parturition in each treatment groups. The conception rate did not differ between the 50 micro g fertirelin group (61.1%; n=72) and the 100 micro g group (59.5%; n=42; NS). In experiment 2, a further 12 cows at 40-60 days postpartum were treated with 100 or 50 micro g fertirelin (n=6 per dose) with treatment commencing in the follicular or luteal phase of the oestrous cycle. The plasma concentration of luteinizing hormone (LH) reached similar peaks of over 5 ng/ml 120 min after the intramuscular administration of fertirelin in both groups. There were no significant differences in LH levels between treatments or phase of the oestrous cycle when treatment commenced. Doses of 50 and 100 micro g fertirelin were compared in experiment 3 using 17 cows to study follicular wave development and synchronization by transrectal ultrasonography, conception rate and corpus luteum function. There were no significant differences between treatments for these factors.It was concluded that using a dose of 50 micro g fertirelin enabled the drug costs to be reduced without affecting the efficiency of a synchronization of ovulation/fixed-time AI protocol for dairy cows.     

Effect of epidermal growth factor on intestinal adaptation after allogeneic small bowel transplantation in rats

We reported that epidermal growth factor (EGF) stimulated graft adaptation in a rat model of syngeneic small bowel transplantation. However, graft rejection is a severe problem with clinical small bowel transplantation, because small intestinal wall contains large amounts of lymphoid tissue. Studies were performed to investigate the effect of EGF on allogeneic graft adaptation after small bowel transplantation in rats treated with an immunosuppressant FK506. The transplanted animals received intraperitoneally EGF or saline (untreated) after surgery and were examined for analysis one week later. EGF-treated group markedly enhanced the water absorption and induction of sodium glucose cotransporter (SGLTI) as compared with EGF-untreated group. EGF-treated group also increased the mucosal crypt depth and its cell proliferating rate, although there was no significant difference in the mucosal villus height between the two groups. These results indicate that EGF accelerates intestinal allograft adaptation in part by the recovery of mucosal structure and function after small bowel transplantation in rats. EGF may have relevance to promote graft function in clinical small intestinal transplantation.     

Role of bradykinin in acid-induced mesenteric hyperemia and duodenal villous damage

Intestinal mucosal capsaicin-sensitive afferent nerves mediate, in part, the mesenteric hyperemia after intraduodenal acidification. The hyperemia plays a role in protecting the duodenal mucosa against acid damage. We tested the hypothesis that bradykinin contributes to this protective hyperemia. A specific antagonist of bradykinin will attenuate the hyperemia and exacerbate duodenal villous damage induced by acid. Study 1: Intravenous vehicle, or the specific bradykinin B2 receptor antagonist (HOE 140) was administered to anesthetized rats. This was followed by intraduodenal bolus administration of 160 microM capsaicin or 0.1 N HCl, and then intravenous bradykinin. Study 2: Intravenous administration of vehicle or HOE 140 was followed by duodenal perfusion with 0.1 N HCl. Superior mesenteric artery blood flow (pulsed Doppler flowmetry) (Study 1) and duodenal villous damage (histology) (Study 2) were recorded. HOE 140 significantly reduced the hyperemia induced by bradykinin and intraduodenal capsaicin or acid. Deep villous injury was significantly increased after treatment with HOE 140. These findings support the hypothesis that acid-induced and afferent nerve-mediated mesenteric hyperemia is modulated by a mechanism that involves bradykinin B2 receptor. Antagonism of bradykinin B2 receptor also increased acid-induced deep duodenal villous damage. Thus, maintenance of bradykinin-mediated mesenteric hyperemia, is a previous unrecognized mechanism associated with protection of the rat duodenal mucosa against acid-induced damage.