Effects of 20-hydroxyecdysone and serotonin on neurite growth and survival rate of antennal lobe neurons in pupal stage of the silk moth Bombyx mori in vitro

Effects of 20-hydroxyecdysone and serotonin on the morphological development and the survival of antennal lobe neurons from day-2 pupal brains of the silk moth Bombyx mori were investigated in vitro. Four morphologically distinct neuronal types could be identified in the cultured antennal lobe neurons: unipolar, bipolar, multi-polar and projection neurons. Antennal lobe neurons in culture with 20-hydroxyecdysone and serotonin showed different patterns of the morphological development from those described in Manduca sexta. Projection neurons extend their neurites remarkably by 20-hydroxyecdysone in B. mori, but there is no extension from antennal lobe neurons in M. sexta. Multi-polar neurons conspicuously increase only formation of new branches from their primary neurites by serotonin in B. mori, but there are both extension and branching of the neurites in M. sexta. On day-5, antennal lobe neurons in lower titers of 20-hydroxyecdysone had significantly higher survival rates than those in higher titers. Neurons cultured for 7 days at different levels of 20-hydroxyecdysone generally showed significantly lower survival rates than neurons cultured for 5 days under the same conditions.     

Induction of apoptosis in p16INK4A mutant cell lines by adenovirus-mediated overexpression of p16INK4A protein

The tumor suppressor gene p16INK4A is a cyclin-dependent kinase inhibitor (CDKI) and an important cell cycle regulator. We have previously constructed a recombinant adenovirus which expresses p16 (Adp16) and shown that infection in a variety of human tumor cell lines with this recombinant virus results in high levels of p16INK4A protein expression resulting in cell cycle arrest and loss of cyclin-cdk activity. Furthermore, adenoviral-mediated overexpression of wild-type p16INK4A is more toxic in cancer cells which express mutant forms of p16INK4A compared to cancer cell lines containing endogenous wild-type p16. TUNEL assay and DAPI staining following infection of MDA-MB 231 breast cancer cells with Adp16 indicate that p16INK4A-mediated cytotoxicity was associated with apoptosis. This is supported by studies demonstrating a decrease in cpp32 and cyclinB1 protein levels and induction of poly (ADP-ribose) polymerase (PARP) cleavage following infection of MDA-MB-231 cells with Adp16. These results suggest that gene therapy using Adp16 may be a promising treatment option for human cancers containing alterations in p16 expression.     

mei-41 is required for precocious anaphase in Drosophila females

This paper reports on a new role for mei-41 in cell cycle control during meiosis. This function is revealed by the requirement of mei-41 for the precocious anaphase observed in crossover-defective mutants. Normally in Drosophila oocytes, tension on the meiotic spindle causes a metaphase I arrest. This tension results because crossovers, and the resulting chiasmata, hold homologs together that are being pulled by kinetochore microtobules toward opposite spindle poles. In the absence of tension, such as in a recombination-defective mutant, metaphase arrest is not observed and meiosis proceeds through the two divisions. Here we show that in some recombination-defective mutants, the precocious anaphase requires the mei-41 gene product. For example, metaphase arrest is not observed in mei-218 mutants because of the severe reduction in crossing over. In mei-41 mei-218 double mutants, however, metaphase arrest was restored. The effect of mei-41 is dependent on double-strand break formation. Thus, in mutants that fail to initiate meiotic recombination the absence of mei-41 has no effect. Received: 15 October 1999; in revised form: 9 December 1999 / Accepted: 13 December 1999     

Transesterification of phosphatidylcholine with eicosapentaenoic acid ethyl ester using phospholipase A2 in organic solvent

Phospholipase A₂-catalysed transesterification of phosphatidylcholine (PC, 99%) with eicosapentaenoic acid ethyl ester (EPAEE, 95%) was carried out in organic solvent. The maximum yield was 14.3% (w/w). The optimum reaction condition was 50°C, 48 h, initial water activity 0.25 and molar ratio of PC to EPAEE 1:10 in 5 ml toluene.     

Characterization of an extracellular flocculating substance produced by a planktonic cyanobacterium, Anabaena sp.

Two planktonic cyanobacteria, Anabaena sp. N1444 and Anabaena sp. PC-1, and a green eukaryotic alga, Scene-desmus sp., produced extracellular flocculants. The flocculant of Anabaena PC-1, when purified, was found to be a macromolecular polysaccharide consisting of neutral sugars, uronic acids, and proteins, but not keto acids, hexosamines nor fatty acids. The flocculant bound a cationic dye, Alcian Blue, indicating it to be polyanionic. The flocculating activity was high under acidic conditions, slightly enhanced by the addition of salts and metals, and increased to about 40% upon heating at 100 °C for 7 min. The flocculant could flocculated various inorganic and organic compounds in solution. © Rapid Science Ltd. 1998     

Generation of active oxygen species (AOS) and induction of β-Glucanase activity by fungal elicitor xylanase in the suspension cultured cells of Tobacco

It was investigated that active oxygen species (AOS) involved in the plant defense responses induced by fungal elicitor xylanase. When xylanase from the fungusTrichoderma viridae was treated to tobacco suspension cultured cells as an elicitor, β-glucanase activity was increased markedly. Lignin biosynthesis was also increased and peaked at 72 h after the treatment with xylanase. The treatment of H₂O₂ also dramatically increased β-glucanase activity at 24 h, which was much earlier than that of xylanase did. Using lucigenin-and luminol-dependent chemiluminescence, the effects of xylanase on oxidative burst were examined. Superoxide anion (O₂) production was peaked at 40 h and 52 h after xylanase treatment and hydrogen peroxide (H₂O₂) release was peaked at 44 h and 56 h, suggesting H₂O₂ burst was followed by O₂ generation. The scavengers of AOS, n-propyl gallate (PG) and mannitol, inhibited xylanase-induced β-glucanase activity by 85% and 50%, respectively. The activity of superoxide dismutase (SOD), which catalyzes the dismutation of O₂ to H₂O₂, began to increase from 24 h and reached to maximum at 48 h after xylanase treatment. Pretreatment of N,N,-diethyldithiocarbamate (DDC), known as a SOD inhibitor, caused the inhibition of H₂O₂ generation by 80% and reduced the β-glucanase activity by 60%. Treatment of 2,5-norbonadiene (NBD), a specific ethylene-action inhibitor, did not have any significant effect on xylanase-induced β-glucanase activity. This result suggested that ethylene did not involve in xylanase-induced response. Our results strongly suggest that the AOS generation is an essential component in plant defense response, in which cell wall degrading enzyme, glucanase, contributes to remove the necrotic tissue induced by pathogens.     

Age-related changes in antioxidant enzyme activities in the small intestine and liver from Wistar rats.

The present study was designed to determine age-related changes in intestinal and hepatic antioxidant enzymes including superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and glutathione-S-transferase (GST), and lipid peroxidation in male Wistar rats (n = 8) aged 2 wk, 2.5 mon, 5 mon, 10 mon, and 23 mon. In the small intestine, cytosolic SOD, GSH-PX activities and lipid peroxidation were not affected by age, but intestinal GST activity was noticeably enhanced as age increased. In particular, intestinal GST activity in 23 mon old rats was 3 times as strong as that in 2 wk old rats. In the liver, the activity of hepatic cytosolic SOD was not affected by age, whereas GSH-PX and GST activities in rats aged 10 mon and 23 mon were much stronger than those in rats aged 2 wk, 2.5 mon, and 5 mon. The increased lipid peroxidation in 2.5 mon and 5 mon old rats was observed when compared with that of other groups. It is therefore concluded from the results presented here that age greatly increases GST activity in the small intestinal mucosae and increasing GSH-PX, GST activities and lipid peroxidation in the liver from male Wistar rats.     

Dextran–estrone conjugate: synthesis and in vitro release study

A novel hormone conjugate has been prepared by a coupling reaction between modified estrone and dextran. In order to provide a suitable reactive estrone derivative for coupling with dextran and a spacer between the drug carrier and the hormone, the steroidal sex hormone was succinylated by reaction with succinic anhydride. Subsequently, the carboxylic acid terminal of succinylated estrone was further reacted with thionyl chloride to replace the hydroxy group with chlorine to make a better leaving group. The ester bond was employed as labile linkage between the hormone and the biopolymer carrier backbone so that the coupled estrogen could be released from the conjugate via ester hydrolysis. Structures of the modified estrone and dextran–estrone conjugate were determined by elemental analysis and by FTIR, ¹H and ¹³C NMR spectroscopies. The degree of substitution (D.S.) per anhydroglucose (AHG) unit was 0.33 (11.0 mol-% of estrone moieties), as calculated from the ¹H NMR spectrum. In vitro hydrolysis of the conjugate in aqueous phosphate buffer/ethanol solutions at pH 8.0 and 7.4 and 37°C released estrone was completed within a few days and followed zero-order kinetics.