Light-Induced CREB Phosphorylation and Gene Expression in Rat Retinal Cells

Abstract: The signal pathway for light-induced expression of c- fos and the neuropeptide somatostatin (SS) in rat retinal cells was investigated. Flashing light induced c- fos and SS mRNA in the inner nuclear layer and the ganglion cell layer. As both c- fos and SS genes have a cyclic AMP response element (CRE) in their promoters, CRE-binding protein (CREB) phosphorylation in retinal cells was examined with a phospho-CREB-specific antibody. Both flashing light and administration of the L-type Ca²⁺ channel activator Bay K 8644 induced phosphorylation of CREB in the nuclei of the amacrine cells and the ganglion cells where c- fos /SS mRNAs were expressed. These cells could be double-stained with anti-calmodulin kinase II (anti-CaM kinase II) monoclonal antibody and phospho-CREB-specific polyclonal antiserum after Bay K 8644 administration, indicating the colocalization of phosphorylated CREB at Ser¹³³ and CaM kinase II in the neural retina.     

Putative morphogen, DIF, of Dictyostelium discoideum induces apoptosis in rat pancreatic AR42J cells

We have recently shown that differentiation-inducing factor-1 (DIF-1) of Dictyostelium discoideum is capable of raising intracellular calcium concentration ([Ca²⁺]_i) and suppressing cell proliferation of rat pancreatic AR42J cells in a dose-dependent manner, and that DIF-1 at a concentration of 40 μmol/L is toxic to the cells. In this study, we have further characterized the cytotoxic effect of DIF-1 on AR42J cells and have analyzed the effect of DIF-1 on [Ca²⁺]_i. In the presence of 40 μmol/L DIF-1, cells began to bleb after approximately 6 h, and most had died within 48 h. Biochemical analysis revealed that DNA fragmentation was accompanied by cell death. Monitoring the changes in [Ca²⁺]_i induced by DIF-1, it was found that cells were able to adapt to stimulation with DIF-1 so that they did not respond to subsequent stimulation by DIF-1. These results indicate that DIF-1 induced apoptosis in AR42J cells probably via a cell signaling system.     

Conversion of Ulva fronds to a hatchery diet for Artemia nauplii utilizing the degrading and attaching abilities of Pseudoalteromonas espejiana

An algal suspension containing protoplasmic detritus [termed, single cell detritus (SCD)] was prepared from freeze-dried fronds of Ulva and its dietary value to Artemia nauplii was tested after size fractionation. The dissolved fraction (<0.22 μm) ofthe Ulva suspension contained ca. 48% of theoriginal protein in the Ulva, but had no dietaryvalue to Artemia, which is a suspension feeder. In contrast, the fraction passing through a 100-μm meshand containing SCD of 2–14 μm in diameter, contributedto the survival of Artemia. The fraction remaining on the 100 μm mesh was further incubated with and without the bacterium Pseudoalteromonas espejiana strain AR06 FERM BP-5024. The bacterium degraded Ulva forming new SCD over 10⁶ mL ^-1 level as rapidly as by 16 h of incubation. The dietary value of Ulva for Artemia growth was elevated over four times by the incubation. The protein content of the SCD was approximately doubled by the attaching of bacteria, suggesting the enhanced Artemia growth is attributable to the combined effect of the SCD and the bacteria. Development of a hatchery diet from Ulva , a resource with a low commercial value, is suggested utilizing the degrading and attaching ability of P. espejiana. This revised version was published online in August 2006 with corrections to the Cover Date.     

Yersinia pseudotuberculosis in China

Thirty strains of Yersinia pseudotuberculosis were isolated from rabbits (17 strains), wild rats (9 strains) and house rats (4 strains) in China between 1990 and 1993. The biochemical properties of these isolates were identical with those of Y. pseudotuberculosis and no special characteristics were found in these strains. Serologically, serogroups 4b and 5b were identical to isolates found in Japan, and a new serogroup 1c and unclassified strains have also been detected. The existence of virulence-associated properties were different among strains. The pYV plasmid was detected from 6 strains of 30 isolates. This report documents the presence of Y. pseudotuberculosis in China, providing important epidemiological information.     

Mammalian expression of single chain variable region fragments dimerized by Fc regions

To promote application of a single chain variable region fragment (sFv) in immunoglobulins, a sFv gene was connected to an IgG1 Fc gene, designated as a sFvc gene, and used for transfection of Sp2/0. As a result, the sFvc protein was found to be secreted in a dimeric form. It is thus felt that the sFvc protein, which mimicks the shape of a naturally occurring antibody, can be simple and useful to reproduce divalency and Fc-associated effecter functions as seen in a natural antibody.Abbreviations Abbreviations sFv single chain variable region fragment - Fc constant region of immunoglobulin - sFvc single chain variable region fragment with an Fc region     

Roles of auxin and gibberellic acid in growth and maturation of epicotyls of Vigna angularis: Cell wall changes

The effects of auxin and gibberellic acid on cell wall composition in various regions of epicotyls of azuki bean ( Vigna angularis Ohwi and Ohashi cv. Takara) were investigated with the following results. (1) Young segments excised from apical regions of the epicotyl elongated in response to added 10⁻⁴ M indole-3-acetic acid (IAA). When the segments were supplied with 50 m M sucrose, the IAA-induced segment growth was accompanied by enhanced overall synthesis of cell wall polysaccharides, such as xyloglucans, polyuronides and cellulose. This IAA effect on the cell wall synthesis is a consequence of extension growth induced by IAA. Gibberellic acid (GA) at 10⁻⁴ M synergistically enhanced the IAA-induced cell wall synthesis as well as IAA-induced extension growth, although GA by itself neither stimulated the cell wall synthesis nor extension growth. In the absence of sucrose, cell wall synthesis was not induced by IAA or GA. (2) In mature segments excised from basal regions of the epicotyl, no extension growth was induced by IAA or GA. GA enhanced the synthesis of xylans and cellulose when the segments were supplied with 50 m M sucrose. IAA had no effect on the cell wall synthesis. These findings indicate that synthesis of polyuronides, xyloglucans and cellulose, which occurs during extension growth of the apical region of the epicotyl, is regulated chiefly by auxin whereas synthesis of xylans and cellulose during cell maturation in the basal region of the epicotyl is regulated by GA.     

A new prolyl hydroxylase acting on poly-L-proline, from suspension cultured cells of Vinca rosea

A new prolyl hydroxylase having a novel substrate specificity was isolated from the suspension-cultured cells of Vinca rosea. This enzyme was solubilized with 0.05 M Tris-HCl buffer (pH 7.4) containing 0.1% Triton X-100, 0.3 M NaCl and 0.5 mM beta-mercaptoethanol from the membrane fractions of the cells, and was partially purified by (NH4)2SO4 fractionation and DEAE-Sephadex A-50 column chromatography. The enzyme preparation was found to require O2, Fe2+, ascorbate, alpha-ketoglutarate and poly-L-proline to attain maximum activity. The plant enzyme does not hydroxylate free proline and di-, tri- and tetra-L-proline, but hydroxylates octa-L-proline and poly-L-proline (Mr greater than 2000). Model peptides of unhydroxylated collagen, (Pro-Pro-Gly)5 and (Pro-Pro-Gly)10 are poor substrates for the plant enzyme. This means that the plant enzyme has a novel substrate specificity in regard to peptidyl substrate, and this differs from vertebrate prolyl hydroxylase, proline,2-oxoglutarate dioxygenase (prolyl-glycyl-peptide, 2-oxoglutarate: oxygen oxidoreductase, EC 1.14.11.2).