Expression of a soluble form of CTLA4 on macrophage and its biological activity

INTRODUCTI0NItisrecentlyreportedthatB7andCD28/CTLA4pathwayplaysacriticalroleintheactivationofT-ce1l[1-3],aswellasintheonsetofautoimmunitybothinhumanandmurinem0delofaut0immunity[4-7].B7moleculesareexpressedonavarietyofcelltypes,includingdentriticcells,Bcells,T-cellsandmacrophages[8-1l].CTLA4Ig,asolubleform0fCTLA4,cou1db10ckB7andCD28/CTLA4pathwayandresultsintheinhibitationofT-cellactivationandautoimmuneresponse[12-19].ThemacrophagicMm1ce1llinewasregardedasag0odmodelforstudyingmacr…     

Variation of Abscisic Acid and Batatasin Content in Yam Bulbils--Effects of Stratification and Light Exposure

Batatasin content of yam (Dioscorea batatas Decne.) bulbilsdecreased slowly during 5 month stratification at 4°C, whileit remained virtually unchanged when stored at 23°C. Abscisicacid increased considerably during the 1st month at 23°Cbut only slightly at 4°C and thereafter remained constantup to the end of the 5-month storage period. On transfer to sprouting beds at 23°C the batatasin contentof stratified bulbils decreased sharply but that of non-stratifiedbulbils showed only slight variation. Light exposure duringsprouting tests suppressed the sprouting of the non-stratifiedbulbils but promoted that of the stratified ones. The changesin batatasin contents were found when the bulbils were exposedto light and this is discussed in relation to sprouting responsesto light. A scheme for batatasin economy in bulbil dormancyis proposed.     

Presence of two glycolytic gene clusters in a severe pathogenic line of Candidatus Phytoplasma asteris

Phytoplasmas are plant-pathogenic bacteria that are associated with numerous plant diseases. We have previously reported the complete genomic sequence of Candidatus Phytoplasma asteris, OY strain, OY-M line, which causes mild symptoms. The phytoplasma genome lacks several important metabolic genes, implying that the consumption of metabolites by phytoplasmas in plants may cause disease symptoms. Here we show that the approximately 30-kb region including the glycolytic genes was tandemly duplicated in the genome of OY-W phytoplasma, which causes severe symptoms. Almost duplicated genes became pseudogenes by frameshift and stop-codon mutations, probably because of their functional redundancy. However, five kinds of genes, including two glycolytic genes, remained full-length ORFs, suggesting that it is advantageous for the phytoplasma to retain these genes in its lifestyle. In particular, 6-phosphofructokinase is known as a rate-limiting enzyme of glycolysis, implying that the different number of glycolytic genes between OY-W and OY-M may influence their respective glycolysis activities. We previously reported that the phytoplasma population of OY-W was higher than that of OY-M in their infected plants. Taking this result into account, the higher consumption of the carbon source may affect the growth rate of phytoplasmas and also may directly or indirectly cause more severe symptoms.     

A NOVEL METHOD FOR PRODUCTION OF MONOCLONAL ANTIBODIES. EVALUATION AND EXPECTATION OF THE RAT LYMPH NODE METHOD IN CELL AND MOLECULAR BIOLOGY

A newly developed method using rat lymph nodes provided us with substantial amounts of high quality monoclonal antibodies. The method has characteristic features, a single injection of an emulsified antigen via the rat's hind footpads is sufficient for immunization. Enlarged medial iliac lymph nodes can be used for cell fusion to produce hybridomas 2 weeks and later after the antigen injection. The production frequency of target hybridomas is about 10 times higher than that of a conventional spleen method. Our current knowledge about the production of monoclonal antipeptide antibodies and monoclonal nephritogenic autoantibodies by the method is described.     

Melanoma Antigen and Transforming Gene

We summarize our recent studies on the analysis of melanoma antigen and the melanoma gene recently cloned. The melanoma antigen analyzed by syngeneic monoclonal antibodies is composed of a complex of GM3 ganglioside and protein molecules. The epitope recognized by antimelanoma cytotoxic T lymphocytes seemed to be the combinatorial determinants of GM3 and proteins, whereas the epitope for the suppressor T cells was found to be solely GM3 (NeuAc). The genomic DNA controlling the melanoma antigen was recently isolated and was found to possess transforming activity. The structure of this transforming gene is discussed based on the sequence data of the corresponding cDNA clone.     

Carotenoid and Steroid Syntheses by Carrot Cells in Suspension Culture

Biosynthesis of carotenoids and steroids in tissue cultures of carrot cells I Daucus carota L.) was studied by measuring the change in their contents and incorporation of ^14lC-acelate. The rate of synthesis of these plant products varied significantly during the growth cycle in batch culture. Carotenoids were most actively synthesized in the early logarithmic phase and the synthetic rate sharply declined as the culture aged, whereas the rate of accumulation of phytosterols was highest at the end of the growth phase. Newly synthesized carotenes were shown to undergo turnover during the growth. The synthesis of both carotecnoid and steroid was stimulated by 2.- 4-dichlorophenoxyacetic acid.     

Effect of serotonin on ouabain-sensitive, K+-dependent, p-nitrophenylphosphatase activity in strial marginal cells of normal and reserpinized guinea pigs

Na+,K+-ATPase activity is abundant on the basolateral infoldings of the strial marginal cells and contributes to the maintenance of the characteristic electrolyte composition of the endolymph. However, the stria vascularis of the cochlea is known not to be innervated. In order to clarify its humoral regulation by serotonin, the K+-p-nitrophenylphosphatase activity of strial marginal cells was investigated with a cerium-based method in normal guinea pigs and in guinea pigs treated with reserpine, 5-hydroxytryptamine or reserpine plus 5-hydroxytryptamine. K+-p-nitrophenylphosphatase activity was almost completely depressed 3--20 days after reserpine administration. Ten days after reserpinization, followed by repeated 5-hydroxytryptamine treatment, the enzyme activity was detectable. These results suggest that 5-hydroxytryptamine increases the phosphatase activity. Thus, the function of the stria vascularis in producing cochlear endolymph may be regulated by 5-hydroxytrypt amine. © 1998 Chapman & Hall