Expression of the T antigen on a T-lymphoid cell line, SupT1

We have measured glycosyltransferase activities of SupT1 cells, a T-lymphoid cell line shown to react with autoantibodies in the sera of many HIV patients. Since considerable -N-acetylgalactosaminyl-transferase and 1, 3 galactosyl-transferase activities were found in SupT1 cells, at least the O-glycan core 1 structure can probably be synthesized. FACS analysis using an anti-T monoclonal antibody showed expression of the T antigen (Gal 1-3 GalNAc). Glycoproteins with the T antigen were isolated by immunoprecipitation with the anti-T antibody from a SupT1 cell lysate labelled metabolically with³H-glucosamine and then analysed by SDS-PAGE. It was revealed that the precipitate contained a glycoprotein with a molecular weight corresponding to that of leukosialin. O-glycans were prepared from the immunoprecipitate by alkaline-borohydride treatment and then fractionated on Bio-Gel P-2, GalNAcOH and Gal-GalNAcOH being identifiedinter alia. These results suggest that an anti-T antibody may be included in the autoantibodies found in HIV-1 infected individuals.     

Nitrogen-flow in the rotifer Brachionus rotundiformis and its significance in mass cultures

The nitrogen budget in the rotifer Brachionus rotundiformis wasmeasured by the stable-isotope technique. The budget was estimatedusing the difference in the turnover time between egestion andexcretion. The rotifer was fed on the algae Nannochloropsiswhich was labeled with ¹⁵N as a tracer. The turnover time ofegestion and excretion were 20 min and 2.5 hours, respectively. Where77% of the ingested nitrogen was egested, and of the assimilated23%, 18% were devoted to growth and 5% to excretion.As for the unassimilated nitrogen egested as faeces, it recycled tothe rotifer through bacteriovory. When the algae provided as foodwere almost fully consumed, bacteriovory became dominant. Thethreshold occurred when the concentration of algae in the culture wasbetween 1.5 and 0.5 million cells of Nannochloropsis per ml. Ina chemostat operated with un-limited food condition, bacterialnitrogen corresponding to 20% of algal feeding, was consumed by therotifer.In a semi-continuous mass culture where food condition was limited,bacteriovory was more effective in supporting the rotiferreproduction. It contributed to the extremely high nitrogen recoveryfrom the provided foods (algae and oil-yeast) to the harvestedrotifers. The rapid and large nitrogen outflow from rotifersaccelerated the propagation of edible bacteria and can explain thestrange paradox observed in the culture; daily supply of foods didnot cover the sum of growth and excretion.It is not too exaggerated to state that the rotifer mass culture issupported by bacteria. The future strategy for maintenance of masscultures should consider this aspect.     

Studies on the factors influencing larval settlement in Balanus amphitrite and Mytilus galloprovincialis

Understanding of factors influencing settlement(attachment and metamorphosis) of marine invertebratelarvae is of great importance in aquaculture andcontrol of biofouling. The influence of two factors onsettlement of larvae was assessed from two separateinvestigations: 1, the influence of age (endogenousfactor) on cyprids of the barnacle Balanusamphitrite; and 2, the influence of a microbial film(exogenous factor) on pediveligers of the mussel Mytilus galloprovincialis.The settlement response of cypris larvae of B.amphitrite was found to be age-dependent. Oldercyprids responded more readily to settlement factorsthan newly molted ones. In M.galloprovincialis, competent pediveligers settled inresponse to a microbial filmed surface but not toan unfilmed surface. Moreover, a factor with MW of lessthan 5000 dalton, derived from culture medium of abacterial strain C1.1 (Pseudomonas-Alteromonasgroup), induced the settlement of M. galloprovincialis larvae.Thus, marine invertebrate larvae may require a periodof competence acquisition, during which they arepoorly responsive to settlement inducers. Uponacquisition of competence, larvae readily respondto external cues (e.g. microbial film, bacterialextracellular products).     

Host range phenotype induced by mutations in the internal ribosomal entry site of poliovirus RNA.

Most poliovirus strains infect only primates. The host range (HR) of poliovirus is thought to be primarily determined by a cell surface molecule that functions as poliovirus receptor (PVR), since it has been shown that transgenic mice are made poliovirus sensitive by introducing the human PVR gene into the genome. The relative levels of neurovirulence of polioviruses tested in these transgenic mice were shown to correlate well with the levels tested in monkeys (H. Horie et al., J. Virol. 68:681-688, 1994). Mutants of the virulent Mahoney strain of poliovirus have been generated by disruption of nucleotides 128 to 134, at stem-loop II within the 5' noncoding region, and four of these mutants multiplicated well in human HeLa cells but poorly in mouse TgSVA cells that had been established from the kidney of the poliovirus-sensitive transgenic mouse. Neurovirulence tests using the two animal models revealed that these mutants were strongly attenuated only in tests with the mouse model and were therefore HR mutants. The virus infection cycle in TgSVA cells was restricted by an internal ribosomal entry site (IRES)-dependent initiation process of translation. Viral protein synthesis and the associated block of cellular protein synthesis were not observed in TgSVA cells infected with three of four HR mutants and was evident at only a low level in the remaining mutant. The mutant RNAs were functional in a cell-free protein synthesis system from HeLa cells but not in those from TgSVA and mouse neuroblastoma NS20Y cells. These results suggest that host factor(s) affecting IRES-dependent translation of poliovirus differ between human and mouse cells and that the mutant IRES constructs detect species differences in such host factor(s). The IRES could potentially be a host range determinant for poliovirus infection.     

Clonal expansion of superantigen-reactive T cells is resistant to FK506 in mice with AIDS.

Subcutaneous injection of FK506 (10 mg/kg of body weight) completely blocked the clonal expansion of staphylococcal enterotoxin A (SEA)-reactive T cells in healthy (control) mice after SEA injection but did not disturb it in mice with murine AIDS (MAIDS) caused by infection with LP-BM5 murine leukemia virus. MAIDS mice are characterized by utilization of a FK506-insensitive pathway for clonal expansion of superantigen-reactive T cells.     

ET-1-induced bronchoconstriction is mediated via ETB receptor in mice

Nagase, Takahide, Tomoko Aoki, Teruaki Oka, YoshinosukeFukuchi, and Yasuyoshi Ouchi. ET-1-induced bronchoconstriction ismediated via ET_B receptor in mice.J. Appl. Physiol. 83(1): 46-51, 1997.Endothelin (ET)-1 is one of the most potent agonists of airwaysmooth muscle and can act via two different ET receptor subtypes, i.e.,ET_A andET_B. To determine the effects ofET-1 on in vivo pulmonary function and which ET receptors are involved in murine lungs, we investigated 1)the effects of ET and sarafotoxin S6c (S6c), a selectiveET_B agonist, on pulmonary functionand 2) the effects of BQ-123 andBQ-788, specific ET_A- andET_B-receptor antagonists, onET-1-induced bronchoconstriction. ICR mice were anesthetized and mechanically ventilated (frequency = 2.5 Hz, tidalvolume = 8 ml/kg, positive end-expiratory pressure = 3 cmH₂O). Intravenous ET-1, ET-2,and ET-3 increased lung resistance similarly and equipotently, whereasS6c elicited a greater degree of bronchoconstriction. Mice were thenpretreated with saline (Sal), BQ-123 (0.2, 1, and 5 mg/kg), or BQ-788(0.2, 1, and 5 mg/kg) before administration of ET-1(10⁷ mol/kg iv). No dose ofBQ-123 blocked ET-1-induced constriction, whereas pretreatment witheach dose of BQ-788 significantly inhibited ET-1-induced responses.There were significant differences in morphometrically assessed airwayconstriction between Sal and BQ-788 and between BQ-123 and BQ-788,whereas no significant difference was observed between Sal and BQ-123.There were no significant morphometric differences in the airway wallarea among the three groups. These observations suggest that theET_B- but notET_A-receptor subtype may mediatethe changes in murine pulmonary function in response to ET-1. Inaddition, the ET_B-receptorantagonist reduces ET-1-induced airway narrowing by affecting airwaysmooth muscle contraction in mice.

     

Phylogenetic relationships of someMicrosporum andArthroderma species inferred from mitochondrial DNA analysis

Thirty-eight strains of 12Microsporum and 10Arthroderma (Nannizzia) species were investigated by analysis of mitochondrial DNA with 6 restriction enzymes, and classified into 13 genetic groups. The phylogenetic tree of the 13 groups thus established was constructed. On the tree,M. audouinii, M. langeronii, M. rivalieri, M. distortum, M. equinum, M. ferrugineum andA. otae comprise one genetic group and are suggested to be the same species.A. gypseum, A. fulvum, M. duboisii, M. ripariae, A. incurvatum, A. persicolor andA. obtusum are clustered on one of five boughs of the tree indicating their close relation.A. racemosum andA. cajetani are also closely related.     

Entrainment of the circadian locomotor activity rhythm in the Japanese newt by melatonin injections

We examined whether melatonin can act as a synchronizing agent within the circadian system of amphibians by testing the ability of melatonin injections to entrain the circadian locomotor activity rhythm of a newt (Cynops pyrrhogaster). Under constant darkness, all newts (13 cases) showing the free-running rhythms were subcutaneously injected with 10 g melatonin at the same time every other day for at least 30 days. Subsequently, they were injected with vehicle (1% ethanolic saline) instead of melatonin for at least another 30 days. In 10 of the 13 newts, the locomotor activity rhythms could be entrained to a period of 24 h by melatonin injections but not by vehicle injections. During the entrained steady-state, the active phase of an activity-rest cycle preceded the time of melatonin injections as previously reported in other diurnal species. These results suggest that the endogenous circadian rhythm of melatonin concentration may be involved in synchronizing circadian oscillator(s) within the newt's circadian system.     

Cellular and subcellular distribution of iron in the lamina propria of rat duodenum

Summary Cellular and subcellular distribution of iron in the lamina propria of rat duodenum was studied after a single i.p. injection of iron dextran, using electron microscopy and peroxidase cytochemistry. X-ray spectrum microanalysis was used for positive identification of iron. Ironcontaining particles (IP) were found in the cytoplasm of three cell types, viz. macrophages, pericytic reticular cells and sheathing fibrocytes. IP-containing organelles in lamina propria cells were more heterogeneous compared to absorptive cells and, in addition, some differences were noted in the subcellular distribution of IP in the 3 cell types. A common denominator in these 3 cell types was the presence of endogenous peroxidase, also shared by Kupffer cells which are known to be involved in iron storage. Peroxidase activity was absent in absorptive epithelial cells. It is hypothesized that the cells of the lamina propria, like Kupffer cells, may be the site of storage of excess iron absorbed, releasing iron upon demand and migrating into the lumen to prevent iron overload. In this fashion they may regulate the exchange of iron with the environment. The presence of peroxidase in these as well as Kupffer cells, and its absence in absorptive cells also raises the possibility that this enzyme may be related to certain aspects of iron storing process.     

Hexane soluble non-volatiles in flowering to fruiting stages of Fatsia japonica

The n-hexane soluble non-volatile fraction of the acetone extracts from the flower buds, the flowers and the immature and the mature fruits of Fatsia japonica were all found to contain fatty acids, fatty acid methyl esters, squalene, β-amyrin and sterols. At all the stages between budding to the mature fruit, the major fatty acids were palmitic and linoleic acids and the major phytosterol was stigmasterol. In addition steryl and β-amyrenyl esters were found in the flowers and the immature and the mature fruits, but these esters were not present in the flower buds. Sitosteryl ester was the major constituent of the steryl ester fraction in the fruiting stages. Phytol was found in only the flowering stage and triglycerides in only the mature fruits. The variations in the lipid constituents is discussed in relation to the stages from budding to the mature fruit.