Plant Growth-regulating Activities of 4-Methoxydiphenylmethanes and Their Related Compounds

The discovery that anisomycin showed plant growth-regulating activity led to the investigation of compounds having p-methoxyphenyl group; the p-anisole derivatives. 4-Methoxydiphenylmethanes and related compounds inhibited the growth of both shoots and roots in test plants. Growth-inhibitory activity in the series of 4-methoxydiphenylmethanes was lowered by an increase in the electron donating or withdrawing ability of the substituent and was parabolically dependent on the Hammett’s σ. Selective actions of these compounds in their growth inhibition are discussed based on correlations between their activities against barnyard grass and other test plants.

Some 4-methoxydiphenylmethanes induced chlorosis, a disturbance in phototropism or geotropism, and root hypertrophy.     

Studies on the Hypertrophic Disease of Cherry (Genus Prunus), So-called “Witch’s Broom” Caused by Taphrina wiesneri

Metabolites of Taphrina wiesneri (Rath.) Mix. were examined. Brassicasterol, stearic acid, and p-hydroxyphenylacetic acid were isolated in crystalline form. p-Hydroxybenzoic acid and vanillic acid were identified by paper chromatography and UV measurement. Palmitic acid was identified by gas-chromatography. The fungus produced usually these compounds on any one of four kinds of medium used. p-Hydroxyphenylacetic acid promoted germination of rape seeds at the concentration of 20 ppm in water and showed inhibition at 250 ppm.

Phenolic acids and their related compounds in Japanese flowering cherry leaves infected by Taphrina wiesneri were examined. In the acidic and neutral extracts of infected cherry leaves (I), eighteen compounds positive to diazotized sulfanilic acid and two fluorescent compounds were detected by paper chromatography. Of these compounds, coumarin, 3, 4-dihydrocoumarin, melilotic acid, o- and p-coumaric acids, p-hydroxybenzoic melilotic acid, ferulic acid and caffeic acid were identified. Melilotic acid and coumarin were obtained in crystalline form. The amount of melilotic acid in I was higher than that in healthy leaves independent of sample source, although increased with the growth of cherry leaves.     

The Photochemical Reaction of Pentachlorophenol

The chemical structure of a yellow C₁₈-compound (IV), isolated from the decomposition products of sodium pentachlorophenoxide (Na-PCP) in an aqueous solution by sunlight, has been determined by chemical and spectroscopic evidences. Some of the chemistry and the absorption spectra of IV and its related compounds containing 3-cyclohexene-1,2-dione and spiroketal structures are also described.     

Ipragliflozin Improves Hepatic Steatosis in Obese Mice and Liver Dysfunction in Type 2 Diabetic Patients Irrespective of Body Weight Reduction

Type 2 diabetes mellitus (T2DM) is associated with a high incidence of non-alcoholic fatty liver disease (NAFLD) related to obesity and insulin resistance. Currently, medical interventions for NAFLD have focused on diet control and exercise to reduce body weight, and there is a requirement for effective pharmacological therapies. Sodium-glucose cotransporter 2 (SGLT2) inhibitors are oral antidiabetic drugs that promote the urinary excretion of glucose by blocking its reabsorption in renal proximal tubules. SGLT2 inhibitors lower blood glucose independent of insulin action and are expected to reduce body weight because of urinary calorie loss. Here we show that an SGLT2 inhibitor ipragliflozin improves hepatic steatosis in high-fat diet-induced and leptin-deficient (ob/ob) obese mice irrespective of body weight reduction. In the obese mice, ipragliflozin-induced hyperphagia occurred to increase energy intake, attenuating body weight reduction with increased epididymal fat mass. There is an inverse correlation between weights of liver and epididymal fat in ipragliflozin-treated obese mice, suggesting that ipragliflozin treatment promotes normotopic fat accumulation in the epididymal fat and prevents ectopic fat accumulation in the liver. Despite increased adiposity, ipragliflozin ameliorates obesity-associated inflammation and insulin resistance in epididymal fat. Clinically, ipragliflozin improves liver dysfunction in patients with T2DM irrespective of body weight reduction. These findings provide new insight into the effects of SGLT2 inhibitors on energy homeostasis and fat accumulation and indicate their potential therapeutic efficacy in T2DM-associated hepatic steatosis.     

Crystal structure of the rac activator, Asef, reveals its autoinhibitory mechanism

The Rac-specific guanine nucleotide exchange factor (GEF) Asef is activated by binding to the tumor suppressor adenomatous polyposis coli mutant, which is found in sporadic and familial colorectal tumors. This activated Asef is involved in the migration of colorectal tumor cells. The GEFs for Rho family GTPases contain the Dbl homology (DH) domain and the pleckstrin homology (PH) domain. When Asef is in the resting state, the GEF activity of the DH-PH module is intramolecularly inhibited by an unidentified mechanism. Asef has a Src homology 3 (SH3) domain in addition to the DH-PH module. In the present study, the three-dimensional structure of Asef was solved in its autoinhibited state. The crystal structure revealed that the SH3 domain binds intramolecularly to the DH domain, thus blocking the Rac-binding site. Furthermore, the RT-loop and the C-terminal region of the SH3 domain interact with the DH domain in a manner completely different from those for the canonical binding to a polyproline-peptide motif. These results demonstrate that the blocking of the Rac-binding site by the SH3 domain is essential for Asef autoinhibition. This may be a common mechanism in other proteins that possess an SH3 domain adjacent to a DH-PH module.     

Immature multipotent hemopoietic progenitors lacking long-term bone marrow-reconstituting activity in the aorta-gonad-mesonephros region of murine day 10 fetuses

Previous studies indicated that multipotent progenitors exist in early fetuses that do not contain long-term reconstituting (LTR) activity. However, it remained unclear whether these multipotent progenitors are committed to the hemopoietic lineage or are immature mesodermal cells or hemangioblasts. In this study, we have succeeded in enriching the multipotent progenitors that are capable of generating myeloid, T, and B cells in the LFA-1(-) subpopulation of TER-119(-)c-kit(+)CD45(+) cells from the aorta-gonad-mesonephros (AGM) region of day 10 fetuses. We found that these day 10 AGM LFA-1(-) cells do not show the LTR activity, whereas day 11 AGM LFA-1(-) cells do have such an activity. These results strongly suggest that multipotent progenitors lacking LTR activity emerge as CD45(+) hemopoietic progenitor cells in the AGM region on the 10th day of gestation, and such p-Multi mature into hemopoietic stem cells by acquiring LTR activity.     

Isolation and characterization of cDNAs encoding mitochondrial phosphate transporters in soybean,maize, rice,and Arabidopsis

cDNA clones encoding mitochondrial phosphate transporters were isolated from four herbaceous plants. The cDNAs for the soybean, maize and rice transporters contained entire coding regions, whereas the Arabidopsis cDNA lacked the 5 portion. The hydropathy profiles of the deduced amino acid sequences predicted the existence of six membrane-spanning domains which are highly conserved in the mitochondrial transporter family. In soybeans, the mRNA level for the transporter was high in tissues containing dividing cells. It was suggested that there are multiple copies of transporter genes in both dicots and monocots. The soybean transporter was expressed as inclusion bodies in Escherichia coli, solubilized with detergents, and then reconstituted into liposomes. The resulting proteoliposomes exhibited high phosphate transport activity. The activity was inhibited by N-ethylmaleimide, like those of mammalian phosphate transporters.     

Cloning and expression analysis of a MAPKKK gene and a novel nodulin gene of Lotus japonicus

We isolated a cDNA encoding mitogen-activated protein kinase kinase kinase alpha, designated LjM3Kalpha, from Lotus japonicus, a model legume. The gene was expressed constitutively in roots, root nodules, and shoots. We also identified a novel nodulin gene, LjNUF, that shows specific expression in nodules. LjNUF resembles the C-terminal half of a hypothetical protein (pir//D85436), the N-terminal half of which is similar to a portion of mitogen-activated protein kinase kinase kinase gamma. Although LjNUF was predicted to be a secreted protein, its function remains to be clarified.     

Crystallization and preliminary X-ray crystallographic analysis of Plasmodium falciparum S-adenosyl-L-homocysteine hydrolase

S-adenosyl-l-homocysteine hydrolase from a malaria parasite Plasmodium falciparum (PfSAHH) has been crystallized by the vapor diffusion method. The crystals belong to an orthorhombic space group P212121 with the cell dimensions of a = 76.66 A, b = 86.31 A, and c = 335.6 A. There are four subunits (one tetramer) per asymmetric unit. X-ray diffraction data have been collected up to 2.8 A resolution. Self-rotation function studies suggest that the tetrameric PfSAHH molecule has the 222 point group symmetry.     

Overexpression of a cyanobacterial phospho<Emphasis Type="Italic">enol</Emphasis>pyruvate carboxylase with diminished sensitivity to feedback inhibition in<Emphasis Type="Italic"> Arabidopsis</Emphasis> changes amino acid metabolism

Phosphoenolpyruvate carboxylase (EC 4.1.1.31) from Synechococcus vulcanus (SvPEPC) is a unique enzyme, being almost insensitive to feedback inhibition at neutral pH. In order to assess its usefulness in metabolic engineering of plants, SvPEPC was expressed in Arabidopsis thaliana (L.) Heynh. under the control of the cauliflower mosaic virus 35S promoter. About one-third of the transformants of the T1 generation showed severe visible phenotypes such as leaf bleaching and were infertile when grown on soil. However, no such phenotype was observed with Arabidopsis transformed with Zea mays L. PEPC (ZmPEPC) for C4 photosynthesis, which is normally sensitive to a feedback inhibitor, l-malate. For the SvPEPC transformants of the T2 generation, which had been derived from fertile T1 transformants, three kinds of phenotype were observed when plants were grown on an agar medium containing sucrose: Type-I plants showed poor growth and a block in true leaf development; Type-II plants produced a few true leaves, which were partially bleached; Type-III plants were apparently normal. In Type-I plants, total PEPC activity was increased about 2-fold over the control plant but there was no such increase in Type-III plants. The phenotypes of Type-I plants were rescued when the sucrose-containing agar medium was supplemented with aromatic amino acids. Measurement of the free amino acid content in whole seedlings of Type-I transformants revealed that the levels of the aromatic amino acids Phe and Tyr were lowered significantly as compared with the control plants. In contrast, the levels of several amino acids of the aspartic and glutamic families, such as Asn, Gln and Arg, were markedly enhanced (4- to 8-fold per plant fresh weight). However, when the medium was supplemented with aromatic amino acids, the levels of Asn, Gln, and Arg decreased to levels slightly higher than those of control plants, accompanied by growth recovery. Taken together, it can be envisaged that SvPEPC is capable of efficiently exerting its activity in the plant cell environment so as to cause imbalance between aromatic and non-aromatic amino acid syntheses. The growth inhibition of Type-I plants was presumed to be primarily due to a decreased availability of phosphoenolpyruvate, one of the precursors for the shikimate pathway for the synthesis of aromatic amino acids and phenylpropanoids. The possible usefulness of SvPEPC as one of the key components for installing the C₄-like pathway is proposed.Abbreviations CaMV Cauliflower mosaic virus - GUS -Glucuronidase - Kan Kanamycin - 2-ME 2-Mercaptoethanol - MS/G medium 1/2 Murashige–Skoog and 1/2 Gamborg mixed medium - PEP Phosphoenolpyruvate - PEPC Phosphoenolpyruvate carboxylase - Sv Synechococcus vulcanus - ZmPEPC Maize PEPC involved in C₄ photosynthesis