Abortive Infection of L Cells by Influenza B Virus: Defect in Bud Formation

Host-dependent restriction of influenza B virus replication in L cells was analysed in comparison with productive infection in MDCK or 1–5C-4 cells. The synthesis and intracellular distribution of virus-specific proteins and the production of cytoplasmic ribonucleoproteins in nonpermissive L cells were similar to those in permissive MDCK cells. However, an electron microscopic study of infected L cells showed neither extracellular virions nor budding virus particles on the cell surface, in contrast to MDCK cells which produced numerous virus particles. PAGE analysis of the plasma membrane isolated from the cells demonstrated no significant difference in the composition of viral polypeptides between permissive 1-5C-4 and nonpermissive L cells. It was noted that the abortiveness of influenza B virus infection in L cells may be due to a defect in host cell function involved in the initiation of virus budding.     

Solution Radioactivated by Hadron Radiation Can Increase Sister Chromatid Exchanges

When energetic particles irradiate matter, it becomes activated by nuclear reactions. Radioactivation induced cellular effects are not clearly understood, but it could be a part of bystander effects. This investigation is aimed at understanding the biological effects from radioactivation in solution induced by hadron radiation. Water or phosphate buffered saline was activated by being exposed to hadron radiation including protons, carbon- and iron-ions. 1 mL of radioactivated solution was transferred to flasks with Chinese hamster ovary (CHO) cells cultured in 5 mL of complete media. The induction of sister chromatid exchanges (SCE) was used to observe any increase in DNA damage responses. The energy spectrum and the half-lives of the radioactivation were analyzed by NaI scintillation detector in order to identify generated radionuclides. In the radioactivated solution, 511 keV gamma-rays were observed, and their half-lives were approximately 2 min, 10 min, and 20 min. They respectively correspond to the beta+ decay of ¹⁵O, ¹³N, and ¹¹C. The SCE frequencies in CHO cells increased depending on the amount of radioactivation in the solution. These were suppressed with a 2-hour delayed solution transfer or pretreatment with dimethyl sulfoxide (DMSO). Our results suggest that the SCE induction by radioactivated solution was mediated by free radicals produced by the annihilated gamma-rays. Since the SCE induction and DMSO modulation are also reported in radiation-induced bystander effects, our results imply that radioactivation of the solution may have some contribution to the bystander effects from hadron radiation. Further investigations are required to assess if radioactivation effects would attribute an additional level of cancer risk of the hadron radiation therapy itself.     

Enhancement of γ-linolenic acid production by Mucor ambiguus with nonionic surfactants

Summary -Linolenic acid (GLA) production by Mucor ambiguus IFO 6742, immobilised in Biomass Support Particles (BSPs), has been investigated in a fluidized-bed fermenter in the presence of nonionic surfactants. In this system, repeated batch cultivation was achieved at higher yield and productivity than by conventional methods, since microbial lipids inlcuding GLA were significantly secreted into the culture broth and/or on the surface of the cell wall.     

Estrogen can regulate the cell cycle in the early G1 phase of yeast by increasing the amount of adenylate cyclase mRNA

The effects of beta-estradiol (estrogen; a minor component of yeast cells) on S. cerevisiae cells in the G0 and G1 phases were examined. Results showed that estrogen stimulated the recovery of growth from G0 arrest induced by nutrient limitation or ts mutation of cdc35 (adenylate cyclase) in the early G1 phase, and inhibited entry into the resting G0 phase by increasing the intracellular cAMP level. However, estrogen had no effect on late G1 arrest induced by the alpha factor or ts mutation of cdc36. Estrogen was found to lead to higher steady-state levels of adenylate cyclase mRNA but not to affect the expression of the RAS1 and RAS2 genes, although these can also alter the intracellular cAMP level. These results suggest that estrogen influences the cell cycle of yeast in the early G1 phase by controlling the level of cAMP through the increase of adenylate cyclase mRNA.     

Synthesis of acetone glycerol acyl esters by immobilized lipase ofMucor miehei

Summary The applications of immobilized lipase ofMucor miehei for the synthesis of acetone glycerol acyl ester from acetone glycerol and fatty acid, which is the first step for monoglyceride production was investigated. With a high oleic acid to acetone glycerol ratio (O/A, mol/mol), a high catalytic activity was observed under low water content in the reaction mixture. By the combination of high O/A ratio (>3) and removal of water which was produced during the reaction, the conversion degree was increased to almost 100%. With the O/A ratio of 3, the approximate half-life of the immobilized lipase and productivity of ester was estimated to be 20 days and 869 g product/g immobilized enzyme per 2 half-lives, respectively.     

Dose-dependent regulation of macrophage differentiation by mos mRNA in a human monocytic cell line.

The proto-oncogene c-mos was expressed during differentiation of the human monocytic cell line U937 into macrophages. To investigate a possible role of the mos oncogene, we introduced the v-mos gene under an inducible promoter, MT-I, into U937 cells. The v-mos transformed cells expressed mos mRNA at an amount proportional to the concentration of Zn2+ ions. The induction of the v-mos gene caused growth inhibition and macrophage differentiation in these cells. The differentiation of v-mos transformed monocytes into macrophages required continuous expression of the v-mos gene. The extent of expression of phenotypic characteristics of macrophages, such as phagocytosis, cell surface antigens and typical morphology, depends on the amount of mos mRNA present. We were therefore able to demonstrate that the expression of only one oncogene, mos, determines monocyte differentiation into macrophages.     

The asymptotic transectional/circumferential homogeneity of the solutions of reaction-diffusion systems in/on cylinder-like domains

It is often reported that an animal with spotty coat markings on its body has a tail with stripe-shaped pattern. In other various biological and chemical phenomena in/on cylinder-like domains, longitudinally periodic band patterns are observed much more often than the other non-uniform patterns. This paper mathematically explains these observations by proving that, in/on a long and narrow cylinder-like domain, any solution of reaction-diffusion system asymptotically loses its spatial dependence in the transectional/circumferential direction.     

Inhibition by Cyclic AMP of Phorbol Ester-Potentiated Norepinephrine Release from Guinea Pig Brain Cortical Synaptosomes

The involvement of Ca2+/phospholipid-dependent protein kinase (protein kinase C, PKC) and cyclic AMP-dependent protein kinase in the K+-evoked release of norepinephrine (NE) was studied using guinea pig brain cortical synaptosomes preloaded with [3H]NE. 12-O-Tetradecanoylphorbol-13-acetate (TPA), a potent activator of PKC, enhanced the K+-evoked release of [3H]NE, in a concentration-dependent manner, but with no effect on the spontaneous outflow and uptake of [3H]NE in the synaptosomes. The apparent affinity of the evoked release for added calcium but not the maximally evoked release was increased by TPA (10(-7) M). Inhibitors of PKC, polymyxin B, and a more potent inhibitor, staurosporine, counteracted the TPA-induced potentiation of the evoked release. Both forskolin and dibutyryl cyclic AMP (DBcAMP) enhanced the evoked release, but reduced the TPA-potentiated NE release. A novel inhibitor of cyclic AMP-dependent protein kinase, KT5720, blocked both the forskolin-induced increase in the evoked release and its inhibition of TPA-induced potentiation in the evoked release, thereby suggesting that forskolin or DBcAMP counteracts the Ca2+-dependent release of NE by activating cyclic AMP-dependent protein kinase. These results suggest that the activation of PKC potentiates the evoked release of NE and that the activation of cyclic AMP-dependent protein kinase acts negatively on the PKC-activated exocytotic neurotransmitter release process in brain synaptosomes of the guinea pig.     

Neuronal activity preceding directional and nondirectional cues in the premotor cortex of rhesus monkeys

Pre-cue activity, the neuronal modulation that precedes a predictable stimulus, was studied in the premotor cortex of three rhesus monkeys. In one condition, a directional cue dictated the timing and target of a forelimb movement. In another condition, a nondirectional cue provided identical timing information but did not indicate the target. Of 501 task-related neurons recorded in premotor cortex, 168 showed pre-cue activity. The onset time of pre-cue activity varied markedly from trial to trial and cell to cell, ranging from trial initiation to 4.8 sec later. No pre-cue activity reflected the direction of limb movement; thus, the data argue against the hypothesis that pre-cue activity reflects preparation for specific limb movements. A small number of cells showed greater pre-cue activity before directional than before nondirectional cues, and this difference may reflect anticipation of the cue's directional information. However, the vast majority (84%) of neurons lacked such differences. We therefore hypothesize that most pre-cue activity reflects or contributes to a facet of behavior common to the two conditions: anticipation of the time and/or nature of events.