Recovery of aSasa tsuboiana population after mass flowering and death

The recovery process of aSasa tsuboiana population after a mass flowering and death in 1977 was investigated by 15 years of observation in the Hira Mountains, Kinki district, western Japan. Seed production was high (6600–13 800 seeds m⁻² inSasa plots and 3900 seeds m⁻² in a forest plot) but emergent seedling density was low (14–21 seedlings m⁻²), probably because of seed predation byMicrotus montebelli occurring between seed shedding and the next spring. The seedling density had decreased further by the next year and theS. tsuboiana population recovered from only a limited number of seedlings. In spite of such a low initial density, theS. tsuboiana population was able to regenerate successfully and attained the previous full stand height in 7–16 years.Miscantbus sinensis invaded and delayed the recovery ofS. tsuboiana in one plot, butS. tsuboiana became dominant as it caught up with the height ofM. sinensis. Seedling growth patterns, such as frequent tillering, the onset of rhizome extension in the early stage of seedling growth and frequent culm production from rhizomes, played important roles in the successful regeneration ofS. tsuboiana.     

Construction of integrated system for selection of fused plant protoplasts

Summary An integrated system has been constructed to instantly identify and efficiently sort the heterokaryons formed by plant protoplast fusion. The system is composed of the following functions: a) a transport system, b) an electro-manipulator, c) a cell harvester, d) a flow cytometer/cell sorter, and e) a control device. The conditions for an efficient and reproducible enrichment of the heterokaryons have been investigated by this system using the fluorescein isothiocyanate stained protoplasts preparing from Glycyrrhiza glabra cell cultures and unstained protoplasts of Abrus precatorius cell cultures which contain a large quantity of chlorophyll.Abbreviations MS Murashige and Skoog (1962) - 2,4-D 2, 4-dichlorophenoxyacetic acid - NAA 1-naphthaleneacetic acid - BAP 6-benzylaminopurine - ABA abscissic acid - FITC fluorescein isothiocyanate This paper is part 96 in the series Studies on Plant Tissue Cultures. For part 95 see Orinara Y., Noguchi T. and Furuya T. (1993) submitted for publication.     

THE EFFECT OF IRON NUTRITION ON PHOTOSYNTHESIS AND NITROGEN FIXATION IN CULTURES OF TRICHODESMIUM (CYANOPHYCEAE)1

Cultures of Trichodesmium NIBB 1067 were grown in the synthetic medium AQUIL with a range of iron added from none to 5 × 10^?7 M Fe for 15 days. Chlorophyll-a, cell counts, and total cell volume were two or three times higher in medium with 10^?7 M Fe than with no added Fe. Oxygen production rate per chlorophyll-a was over 60% higher with higher iron. Increased iron stimulated photosynthesis at all irradiances from about 12–250 μE · m^?2· s^?1. Nitrogen fixation rate, estimated from acetylene reduction, for 10^?7 and 10^?8 M Fe cultures was approximately twice that of the cultures with no added Fe. The range of rates of O₂ production and N₂ fixation in cultures at the iron concentrations we used were similar to the rates from natural samples of Trichodesmium from both the Atlantic, and the Pacific oceans. This similarity may allow this clone to be used, with some caution, for future physiological ecology studies. This study demonstrates the importance of iron to photosynthesis and nitrogen fixation and suggests that Trichodesmium plays a central role in the biogeochemical cycles of iron, carbon and nitrogen.     

Establishing apoptosis resistant cell lines for improving protein productivity of cell culture

The authors established apoptosis resistant COS–1, myeloma, hybridoma, and Friend leukemia cell lines by genetically engineering cells, aiming at more efficient protein production by cell culture. COS–1 cells, which are most widely used for eukariotic gene expression, were transfected with human bcl–2 gene. Both bcl–2 and mock transfected COS–1 cells were cultured at low (0.2%) serum concentration for 9 days. The final viable cell number of the bcl–2 transfected cells was ninefold of that of the mock transfectants. Both bcl–2 and mock transfectants were further transfected with the vector pcDNA- containing SV40 ori and immunoglobulin gene for transiently expressing protein. The bcl–2 expressing COS–1 cells produced more protein than the mock transfected COS–1 cells after 4 days posttransfection.Mouse myeloma p3-X63-Ag.8.653 cells, which are widely used as the partner for preparing hybridoma, and hybridoma 2E3 cells were transfected with human bcl–2 gene. Both bcl–2 transfected myeloma and hybridoma survived longer than the corresponding original cells in batch culture. The bcl–2 transfected 2E3 cells survived 2 to 4 four days longer in culture, producing 1.5- to 4-fold amount of antibody in comparison with the mock transfectants.Coexpression of bag–1 with bcl–2 improved survival of hybridoma 2E3 cells more than bcl–2 expression alone. The bag–1 and bcl–2 coexpressing cells produced more IgG than the the cells expressing bcl–2 alone.Apoptosis of Friend murine erythroleukemia(F-MEL) cells was suppressed with antisense c-jun expression. The antisense c-jun expressing cells survived 16 days at non-growth state.     

The specific expression of tenascin in the synovial membrane of the temporomandibular joint with internal derangement: An immunohistochemical study

 The expression of tenascin (TN) in the temporomandibular joint (TMJ) disc and synovial membrane was examined in 18 human TMJ samples from patients with internal derangement of the TMJ and ten control specimens by an immunohistological technique using paraffin-embedded tissue and specific anti-human TN monoclonal antibody (RCB-1). The expression of TN was observed in all 28 samples, but it was limited to the walls of blood vessels, the perineurium, and the surface of the TMJ disc. The expression of TN was diffuse in the stroma of mildly hypertrophic synovial membranes and focal in the surface of severely hypertrophic synovial membranes. The clinical symptoms of internal derangement of the TMJ are thought to be related to the degree of synovitis. The present study demonstrates that TN is expressed specifically in the portion of the TMJ synovial membrane affected with internal derangement. Accepted: 17 December 1996     

Induction of T-cell apoptosis by human herpesvirus 6.

The mechanisms of cell death in CD4+ T cells mediated by human herpesvirus 6 (HHV-6) were investigated. The frequency of cell death in the human CD4+ T-cell line JJHAN, which had been inoculated with HHV-6 variant A or B, appeared to be augmented by tumor necrosis factor alpha (TNF-alpha). Agarose gel electrophoresis of DNA from HHV-6-inoculated cells showed DNA fragmentation in multiples of the oligonucleosome length unit. The degree of DNA fragmentation increased when HHV-6-inoculated cells were cultured in the presence of TNF-alpha. Flow cytometry and Scatchard analysis of TNF receptors revealed an increase in the number of the p55 form of TNF receptors on JJHAN cells after HHV-6 inoculation. It also appeared that treatment with anti-Fas monoclonal antibody (MAb) induced marked apoptosis in HHV-6-inoculated cells. Transmission electron microscopy showed characteristics of apoptosis, such as chromatin condensation and fragmentation of nuclei, but virus particles were hardly detected in apoptotic cells. Two-color flow cytometric analysis using anti-HHV-6 MAb and propidium iodide revealed that DNA fragmentation was present predominantly in uninfected cells but not in productively HHV-6-infected cells. In addition, JJHAN cells incubated with UV light-irradiated and ultracentrifuged culture supernatant of HHV-6-infected cells appeared to undergo apoptosis. The present study demonstrated that both HHV-6 variants A and B induce apoptosis in CD4+ T cells by indirect mechanisms, as reported recently in human immunodeficiency virus type 1 infection.