Ceramide in Rice Grain

A rice lamina inclination test that is simple and specific for brassinosteroids was used as a micro-quantitative bioassay for brassinolide 1 and its 6-keto congener, castasterone 2, in the concentration range of 5 x 10^–5 /ig/ml to 5 x 10^–3μg/ml, when uniform seedlings of the rice cultivars Arborio J-l and Nihonbare were selected. A phytohormone, indole-3-acetic acid (IAA), showed similar activity in this bioassay. Its lowest effective concentration, however, was 50 /ig/μl, about five orders of magnitude greater than that of brassinolide. Other phytohormones, abscisic acid (ABA) and the cytokinins kinetin and A⁶-benzyladenine, inhibited the lamina inclination of rice seedlings. The addition of a cytokinin reduced the promoting effect of brassinolide. Thus, the rice lamina inclination test can be used both as a micro-quantitative bioassay for brassinosteroids and as a method for detecting antibrassinolide compouds.     

A tightly regulated expression system for <Emphasis Type="Italic">E. coli</Emphasis> using supersaturated silicic acid

Objective

To develop a new expression system regulated by a ferric uptake regulator in which silicic acid is used as an inducer.

Results

Fur box (binding site for Fur) was substituted for the lac operator to regulate the expression of GFP with the lac promoter. Since the addition of supersaturated silicic acid invokes iron deficiency, supersaturated silicic acids were used as an inducer. GFP expression was dependent on silica concentration, and the expression level without silica was negligible. Basal expression level of this lac-Fur system was extremely low and, hence, lytic enzyme gene E from bacteriophage ?X174 could be retained in this system. Furthermore, the expression of genes of interest was spontaneously initiated as the cell density increased and the costs of the inducer are considerably less than IPTG.

Conclusion

The combination of lac promoter and Ferric uptake repressor allowed the protein expression by supersaturated silicic acid as an inducer in an easy and cost-effective way.

     

Oligomerization of N-tosylindole with aluminum chloride

The reactivity of N-tosylindole (4) in the presence of aluminum chloride was studied, and two types of oligomerization of 4 were observed. One type was condensation between both pyrrole parts (dimers 5 and 6 and trimer 7) and the other was between a pyrrole part and a benzene part of each indole nucleus (dimers 8 and 9).     

Urotensin II-related peptide, the endogenous ligand for the urotensin II receptor in the rat brain

Urotensin II (UII) is a piscine neuropeptide originally isolated from the teleost urophysis. The existence of UII in mammals has been demonstrated by cloning of the mammalian orthologs of UII precursor protein genes. While rat and mouse orthologs have been reported, only the tentative structures of UII peptides of these animals have been demonstrated, since prepro-UII proteins lack the typical processing sites in the amino-terminal region of the mature peptides. A novel peptide, UII-related peptide (URP), was discovered by monitoring UII-immunoreactivity in the rat brain, and its amino acid sequence was determined to be ACFWKYCV. cDNAs encoding rat, mouse, and human precursor proteins for URP were cloned and showed that the sequences of mouse and human URP peptides are identical to that for rat URP. URP was found to bind and activate the human or rat urotensin II receptors [GPR14, UT receptor (UTR)] and showed a hypotensive effect when administrated to anesthetized rats. The prepro-URP gene is expressed in several rat tissues, although with lower levels than the prepro-UII gene and, in the human, is expressed comparably to prepro-UII in several tissues except the spinal cord. These results suggest that URP is the endogenous and functional ligand for urotensin II receptor in the rat and mouse, and possibly in the human.     

Inducible liver injury in the transgenic rat by expressing liver-specific suicide gene

Suicide gene expression in specific tissue of transgenic animals has been used for cell-specific ablation. To examine the influence of hepatocyte removal, we produced the herpes simplex virus thymidine kinase (HSVtk) transgenic rat, whose gene was regulated by an albumin enhancer promoter. The liver presence of HSVtk was demonstrated in one line of the transgenic rats. We injected ganciclovir (GCV, 50mg/kg) into the rat on alternate days. After 28 days of GCV administration, liver tissues, and blood of the rats were collected. The histological investigation revealed infiltration of T cells, macrophages, granulocytes/neutrophils, and hepatocyte cell death. The biochemistry analysis demonstrated elevated levels of AST, ALT, and total bilirubin in transgenic rat. In conclusion, the transgenic rat with expressed albumin-specific HSVtk developed experimental hepatitis with administration of GCV, and will be a useful model to facilitate the evaluation of drug effects for clinical control of liver disease.     

A G protein-coupled receptor responsive to bile acids

So far some nuclear receptors for bile acids have been identified. However, no cell surface receptor for bile acids has yet been reported. We found that a novel G protein-coupled receptor, TGR5, is responsive to bile acids as a cell-surface receptor. Bile acids specifically induced receptor internalization, the activation of extracellular signal-regulated kinase mitogen-activated protein kinase, the increase of guanosine 5'-O-3-thio-triphosphate binding in membrane fractions, and intracellular cAMP production in Chinese hamster ovary cells expressing TGR5. Our quantitative analyses for TGR5 mRNA showed that it was abundantly expressed in monocytes/macrophages in human and rabbit. Treatment with bile acids was found to suppress the functions of rabbit alveolar macrophages including phagocytosis and lipopolysaccharide-stimulated cytokine productions. We prepared a monocytic cell line expressing TGR5 by transfecting a TGR5 cDNA into THP-1 cells that did not express TGR5 originally. Treatment with bile acids suppressed the cytokine productions in the THP-1 cells expressing TGR5, whereas it did not influence those in the original THP-1 cells, suggesting that TGR5 is implicated in the suppression of macrophage functions by bile acids.     

Molecular heterogeneity of heat-stable toxin-producing and non-producing Escherichia coli O25 strains isolated in Japan

Escherichia coli O25 strains that produce heat-stable toxin (ST) have been recently isolated in Japan, and epidemiological study of this type of enterotoxigenic E. coli is required. In this study the heterogeneity of 16 ST-producing and non-producing strains of E. coli O25 was investigated. All eight ST-producing strains were shown to have STIb gene, and seven of them had similar profiles of plasmids, ladder-banding of LPS in SDS-polyacrylamide gel electrophoresis, and chromosomal DNA digestions in pulsed-field gel electrophoresis (PFGE). In contrast, ST-non-producing strains were more heterogeneous in all parameters examined. PFGE of the digested chromosomal DNA with several restriction enzymes was proved to be an effective procedure to compare the closely related strains of E. coli O25.     

Kinetic analysis of microbial desulfurization of model and light gas oils containing multiple alkyl dibenzothiophenes

The reaction mechanism of biodesulfurization was investigated using whole cells of Rhodococcus erythropolis KA2-5-1, which have the ability to convert dibenzothiophene (DBT) into 2-hydroxybiphenyl. The desulfurization patterns of alkyl DBTs were represented by the Michaeis-Menten equation. The values of rate constants, the limiting maximal velocity (Vmax) and Michaelis constant (Km), for desulfurization of alkyl DBTs were calculated. The relative desulfurization activities of various alkyl DBTs were reduced in proportion to the total carbon numbers of alkyl substituent groups. Alkyl DBTs that had a total of six carbons of alkyl substituent groups were not desulfurized. The type or position of alkyl substituent groups had little effect on desulfurization activity. The desulfurization activity of each alkyl DBT, when mixed together, was reduced. This phenomenon was caused by apparent competitive inhibition of substrates. Using the apparent competitive inhibition model, the desulfurization pattern of a multiple components system containing alkyl DBTs was elucidated. This model was also applicable for biodesulfurization of light gas oil.     

Insulin-like growth factor I enhances gonadotropin-releasing hormone-stimulated luteinizing hormone release from bovine anterior pituitary cells

The role of insulin-like growth factor I (IGF-I) in the release of luteinizing hormone (LH) is unclear in ruminants. In the present study, the effects of IGF-I on the release of LH stimulated by gonadotropin-releasing hormone (GnRH) were examined in primary cultures of bovine anterior pituitary (AP) cells, and the interaction between estradiol-17beta (E(2)) and IGF-I was characterized. GnRH(100nM)-stimulated LH release from the cultured cells was increased (P<0.05) 12, 24 and 36h after addition of IGF-I (250ng/ml), with a maximum at 12h (48.4ng/ml media versus 35.4ng/ml media in controls). IGF-I at concentrations of 25, 250 and 500ng/ml increased the release by 18.7, 24.2 and 28.9%, respectively (P<0.05), when compared with controls (37.2ng/ml media). E(2) (10nM), IGF-I (250ng/ml) and combined treatment of E(2) plus IGF-I also induced significant increases in LH release (P<0.05). The amounts of LH release after treatment with E(2) alone was 37.3% greater than with IGF-I alone (39.0ng/ml media versus 28.4ng/ml media) (P<0.05). When E(2) and IGF-I were added together (45.6ng/ml media), the release of LH was significantly greater than with either E(2) alone or IGF-I alone (P<0.05). E(2) (10nM) significantly (P<0.05) increased the amount of GnRH bound to the cells by 51.6% when compared with controls, however, IGF-I (250ng/ml) failed to increase GnRH binding. These results show that IGF-I enhances GnRH-stimulated LH release without changing the number of GnRH receptors in cattle, and IGF-I interacts with E(2) to increase the response to GnRH.