Blue light does not inhibit nodulation in Sesbania rostrata.

Earlier, we reported that root nodulation was inhibited by blue light irradiation of Lotus japonicus. Because some legumes do not establish nodules exclusively on underground roots, we investigated whether nodule formation in Sesbania rostrata, which forms both root and "stem" nodules following inoculation with Azorhizobium caulinodans, is inhibited by blue light as are L. japonicus nodules. We found that neither S. rostrata nodulation nor nitrogen fixation was inhibited by blue light exposure. Moreover, although A. caulinodans proliferation was not affected by blue light irradiation, bacterial survival was decreased. Therefore, blue light appears to impose different responses depending on the legume-rhizobial symbiosis.

Blue Light Perception by Both Roots and Rhizobia Inhibits Nodule Formation in Lotus japonicus.

In many legumes, roots that are exposed to light do not form nodules. Here, we report that blue light inhibits nodulation in Lotus japonicus roots inoculated with Mesorhizobium loti. Using RNA interference, we suppressed the expression of the phototropin and cryptochrome genes in L. japonicus hairy roots. Under blue light, plants transformed with an empty vector did not develop nodules, whereas plants exhibiting suppressed expression of cry1 and cry2 genes formed nodules. We also measured rhizobial growth to investigate whether the inhibition of nodulation could be caused by a reduced population of rhizobia in response to light. Although red light had no effect on rhizobial growth, blue light had a strong inhibitory effect. Rhizobial growth under blue light was partially restored in signature-tagged mutagenesis (STM) strains in which LOV-HK/PAS- and photolyase-related genes were disrupted. Moreover, when Ljcry1A and Ljcry2B-silenced plants were inoculated with the STM strains, nodulation was additively increased. Our data show that blue light receptors in both the host plant and the symbiont have a profound effect on nodule development. The exact mechanism by which these photomorphogenetic responses function in the symbiosis needs further study, but they are clearly involved in optimizing legume nodulation.

Enhanced hyphal growth of arbuscular mycorrhizae by root exudates derived from high R/FR treated Lotus japonicus.

Red/Far Red (R/FR) sensing positively influences the arbuscular mycorrhizal (AM) symbiosis of both legume and nonlegume plants through jasmonic acid (JA) and strigolactone signaling. We previously reported that root exudates obtained from high R/FR-grown plants contained more strigolactone than low R/FR-grown plants. To determine whether JA and JA derivatives were secreted from roots, we investigated the expression levels of JA-responsive genes in L. japonicus Miyakojima MG20 plants treated with root exudates prepared from either high or low R/FR light-treated plants. The root exudates from high R/FR light-treated plants were found to enhance the expression levels of JA-responsive genes significantly. Moreover, exogenous JA increased AM fungal hyphal elongation as did the root exudates derived from high R/FR-grown L. japonicus plants. We conclude that increased JA accumulation and secretion into root exudates from high R/FR light-grown plants is the best explanation for increased colonization and enhanced mycorrhization under these conditions.

Emergence of anti-islet autoantibodies in Japanese patients with type 1 diabetes.

Circulating anti-islet autoantibodies in sera are used as a predictive marker for type 1 diabetes (T1D). We here report two Japanese patients with autoimmune thyroid disease complicated with T1D in whom the time course of anti-islet autoantibodies were observed before the clinical onset of diabetes. Case 1: A woman who had developed Graves' disease at age 25 was diagnosed with type 2 diabetes at age 31; six months later, insulin therapy was started. At age 36 she was diagnosed with T1D due to glutamic acid decarboxylase 65 autoantibodies (GAD65Ab)-positive status and decreased C-peptide levels. With stored sera we retrospectively followed her anti-islet autoantibodies. GAD65Ab, zinc transporter 8 autoantibodies (ZnT8Ab) and insulin autoantibodies (IAA) were found to be positive at age 25. IAA soon turned negative, but GAD65Ab and ZnT8Ab remained positive with high levels. Insulinoma-associated antigen-2 autoantibodies (IA-2Ab) emerged 2 years before the initiation of insulin therapy. She has T1D-susceptible HLA-DRB1-DQB1 haplotypes, (*)0405- (*)0401/(*)0802-(*)0302. Case 2: A 49-year-old woman with hypothyroidism due to 19 years' history of atrophic thyroiditis noticed marked thirst, polyuria and weight loss. On admission she was diagnosed as T1D due to GAD65Ab-positive findings and poor C-peptide response to i.v. glucagon. Retrospective serology revealed the emergence of GAD65Ab and IAA just after the clinical onset. IA-2Ab and ZnT8Ab never developed. She has T1D-susceptible and -resistant HLADRB1- DQB1 haplotypes, (*)0901-(*)0303/(*)1502-(*)0601. The autoantibody profile and the mode of diabetes onset in the two cases were remarkably different. These cases imply that anti-islet autoantibodies do not always precede the onset of T1D.

17Beta-estradiol induces gastrointestinal motility disorder by decreasing CPI-17 phosphorylation via changes in rho-family G-protein Rnd expression in small intestine.

In the present study, we investigated the long-term effects of 17beta-estradiol on the motility of small intestine in in vitro organ culture and in vivo treatment studies. When rat ileal circular smooth muscle tissues were cultured with 17beta-estradiol (0.1 and 1 microM) for 5 days, carbachol-induced contraction was inhibited. In ileal tissue isolated from ovariectomized rat treated with 17beta-estradiol (200 microg/kg/day s.c. for 3 days), carbachol-induced contraction was also impaired. Both in vitro and in vivo, 17beta-estradiol treatment upregulated heat shock protein 27 (HSP27) expression, indicating the activation of estrogen receptor in the intestinal smooth muscle. 17beta-estradiol did not change protein expression levels of RhoA and RhoA-associated coiled coil-forming serine/threonine kinases (ROCKs); however, it upregulated Rnd2 and Rnd3, Rho-family G-proteins that counteract the functions of RhoA, both in vitro and in vivo. In organ culture, treatment of ileal tissue with 17beta-estradiol greatly suppressed the carbachol-induced increase in phosphorylation at Thr38 in CPI-17 without altering total CPI-17 protein expression. These results suggest that 17beta-estradiol upregulates Rnd expression to inhibit the RhoA-mediated Ca(2+) sensitization of contractile mechanisms, which are mediated by CPI-17 phosphorylation in ileal smooth muscle. This mechanism may contribute to the intestinal motility disorder occurring in gender-dependent bowel diseases.

Protein phosphatase inhibitory activity of tautomycin photoaffinity probes evaluated at femto-molar level.

Herein we describe the further improvement of our in-house developed firefly bioluminescence assay system for the determination of inhibition of protein phosphatase (PP). The advantage with the new system is higher sensitivity as well as being time and sample efficient. The inhibition activity of tautomycin with PP1gamma was determined using the upgraded test system and Ki was found to be 4.5 nM, which compare favorably with the activity reported previously by others using different methods. The test system was then used in order to determine the activity of nine tautomycin (TTM) photoaffinity probes. One of the TTM photoaffinity probes (anti-10) was found to possess higher activity than the natural product itself with a Ki of 3.4 nM, while the remaining photoaffinity probes were found to possess Ki in the range of 8.0-213 nM.