Rapid in vitro multiplication of jujube through mature stem explants

Stem explants obtained from a mature tree of Ziziphus mauritiana Lamk were grown on modified Murashige and Skoog medium containing 3800 mg l^-1 potassium nitrate, 2475 mg l^-1 ammonium nitrate, 11 M benzyladenine and 0.5 M indole-3-acetic acid. During successive subcultures 15–20 shoots per inoculum were produced. Rooting was induced by pretreatment with 50 M indolebutyric acid or 1-naphthaleneacetic acid for 24 h followed by transfer to auxin-free White's medium. Plantlets grew well in a soil and vermiculite mixture.Abbreviations IAA Indole-3-acetic acid - NAA 1-naphthaleneacetic acid - BA benzyladenine - MS Murashige and Skoog     

Relationship between actions of transforming growth factor (TGF)-β and cell surface expression of its receptors in clonal osteoblastic cells

Various osteoblastic cell lines were examined for the relationship between the presence of cell-surface transforming growth factor (TGF)-β receptors and the synthesis of matrix proteins with their responsiveness to TGF-β. Treatment with TGF-β1 inhibited proliferation and stimulated proteoglycan and fibronectin synthesis in MC3T3-E1 and MG 63 cells. The major proteoglycans synthesized by these cells were decorin and biglycan, and TGF-β1 markedly stimulated the synthesis of decorin in MC3T3-E1 and of biglycan in MG 63 cells. SaOS 2 and UMR 106 cells synthesized barely detectable amounts of decorin or biglycan, and TGF-β1 did not stimulate the synthesis of these proteoglycans. In SaOS 2 cells, however, TGF-β1 enhanced fibronectin synthesis. TGF-β1 did not show any of these effects in UMR 106 cells. Receptor cross-linking studies revealed that only MC3T3-E1 and MG 63 cells had both types I and II signal-transducing receptors for TGF-β in addition to betaglycan. SaOS 2 cells possessed type I but no type II receptor on the cell surface. In contrast, SaOS 2 as well as MC3T3-E1 and MG 63 cells expressed type II receptor mRNA by Northern blot analysis, and cell lysates contained type II receptor by Western blot analysis. Thus, it appears that type II receptor present in SaOS 2 cells is not able to bind TGF-β1 under these conditions. UMR 106 cells with no response to TGF-β1 had neither of the signal-transducing receptors by any of the analyses. These observations using clonal osteoblastic cell lines demonstrate that the ability of osteoblastic cells to synthesize bone matrix proteoglycans is associated with the responsiveness of these cells to TGF-β1, that the responsiveness of osteoblastic cells to TGF-β1 in cell proliferation and proteoglycan synthesis correlates with the presence of both types I and II receptors, and that the effect of TGF-β1 on fibronectin synthesis can develop with little binding of TGF-β1 to type II receptor if type I receptor is present. It is suggested that the combination of cell-surface receptors for TGF-β determines the responsiveness of osteoblastic cells to TGF-β and that changes in cell-surface TGF-β receptors may play a role in the regulation of matrix protein synthesis and bone formation in osteoblasts. © 1995 Wiley-Liss, Inc.     

Effects of surfactant proteins SP-B and SP-C on dynamic and static mechanics of immature lungs

Kobayashi, Tsutomu, Katsumi Tashiro, Ken Yamamoto, ShunichiNitta, Shigeo Ohmura, and Yasuhiro Suzuki. Effects of surfactant proteins SP-B and SP-C on dynamic and static mechanics of immature lungs. J. Appl. Physiol. 83(6):1849-1856, 1997.To investigate the effects of surfactantproteins B (SP-B) and C (SP-C) on lung mechanics, we compared tidal andstatic lung volumes of immature rabbits anesthetized with pentobarbitalsodium and given reconstituted test surfactants (RTS).With a series of RTS having various SP-B concentrations (0-0.7%)but a fixed SP-C concentration (1.4%), both the tidal volume with25-cmH₂O insufflation pressure and the static volume deflated to5-cmH₂O airway pressure increased, significantly correlating with the SP-B concentration: the former increased from 6.5 to 26.0 ml/kg (mean), and the latter increased from6.4 to 31.8 ml/kg. With another series of RTS having afixed SP-B concentration (0.7%) but various SP-C concentrations(0-1.4%), the tidal volume increased from 5.1 to 24.8 ml/kg,significantly correlating with the SP-C concentration, whereas thestatic volume increased from 3.4 to 32.0 ml/kg, the ceiling value, inthe presence of a minimal concentration of SP-C (0.18%). Inconclusion, certain doses of SP-B and SP-C were indispensable foroptimizing dynamic lung mechanics; the static mechanics, however,required significantly less SP-C.

     

Global stability of an SIR epidemic model with time delays

An SIR disease transmission model is formulated under the assumption that the force of infection at the present time depends on the number of infectives at the past. It is shown that a disease free equilibrium point is globally stable if no endemic equilibrium point exists. Further the endemic point (if it exists) is globally stable with respect to the whole state space except the neighborhood of the disease free state.Research partly supported by the Ministry of Education, Science and Culture, Japan, Grant 05640256     

Stabile production of a thrombin resistant pro-urokinase derivative (PRO-UKS1) by Namalwa KJM-1 cells adapted to serum-free medium

Pro-UKS1 was designed as a thrombin-resistant derivative of pro-urokinase (pro-UK) by introducing a glycosylation site using site-directed mutagenesis. An expression plasmid for pro-UKS1, pMo1UKS1SEd1-5, was constructed and introduced into Namalwa KJM-1 cells (Hosoiet al., 1988), and cells resistant to G418 and Methotrexate (MTX) were obtained. Amongst them, the highest pro-UKS1 producer (resistant to 500 nM of MTX), clone 41-8, was selected and further characterized. Clone 41-8 was cultured in serum-free ITPSGF medium (Hosoiet al., 1988). Under the conventional conditions, the concentration of pro-UKS1 reached 26 g ml^–1. Addition of glucose and tri-iodothyronine (T₃) improved productivity, and the maximal productivity of pro-UKS1 was 67 g ml^–1 day^–1. In this conditioned medium, content of pro-UKS1 was above 80% of total proteins.Abbreviations BSA bovine serum albumin - dhfr dihydrofolate reductase - HEPES 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid - kb kilobase pairs - kDa kilodaltons - MTX Methotrexate - PBS phosphate buffered saline - pro-UK pro-urokinase - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis - T₃ tri-iodothyronine - Tween-PBS phosphate buffered saline containing 0.05% Tween 80     

Alkaline phosphatase reactivity in rabbit airway epithelium: a potentially useful marker for airway basal cells

The purpose of this study was to investigate alkaline phosphatase (ALPase) reactivity in rabbit airway epithelial cells. Acetone-fixed, methyl benzoate and xylene-cleared (AMeX-treated) paraffin sections of trachea, bronchus, and lung tissue were stained by an azo dye coupling method for ALPase and examined by light microscopy. Electron histochemical staining was also performed in order to study the sensitivity and specificity of reactivity in each cell type. ALPase reactivity at the light microscopic level was observed exclusively in trachco-bronchial basal cells, and not in bronchiolar basal cells. By electron microscopy, ALPase reactivity was noted in 97.9% of basal cells in the trachea, 97.0% of basal cells in the bronchus, and 94.5% of basal cells and 15.4% of Clara cells in the bronchiole. This was also true for dispersed tracheal epithelial cells. Reactivity was rarely observed in ciliated cells, non-goblet-type secretory cells, and undetermined cells. The reactivity was heatlabile, levamisole-sensitive, and of a non-specific type. These findings indicate that basal cells of rabbit trachea and bonchus have fairly high specificity for ALPase of a non-specific isozyme (92.2% and 95.6%, respectively). Therefore, ALPase is considered to be a useful marker for these cells.     

Changes of an androgen-dependent nuclear protein during functional differentiation and by dedifferentiation of the dorsolateral prostate of rats

In contrast with previous results that indicate that Saccharomyces cerevisiae fructose-1,6-bisphosphatase is a dimer of 56,000 molecular weight subunits, we find that the subunit Mr of the enzyme purified from baker's yeast is 40,000. The same subunit Mr was observed in immunoprecipitates of crude supernatants of baker's yeast and S. cerevisiae cultures, as well as in acid-extracts of cells detected by immunoblotting, suggesting that the native subunit indeed has a Mr of 40,000 and it has not been produced from a larger polypeptide. Complete immunoprecipitation of fructose-1,6-bisphosphatase activity with saturating concentrations of specific antibody suggests that there is only one fructose-1,6-bisphosphatase isozyme in S. cerevisiae. The Mr of the purified enzyme determined by size exclusion HPLC suggests that it has a tetrameric structure characteristic of fructose-1,6-bisphosphatases from a broad phylogenetic spectrum.     

In Vitro Culture of a Root Parasite, Aeginetia indica L. II. The Plane of Cell Division in the Tendril

Factors affecting septation (cell division) of the tendril whichfacilitates the organic connection with the host were studiedin a root parasite Aeginetia indica L. Transverse cell division,which occurs perpendicular to the long axis of the tendril,was promoted by additions of sucrose, glucose and cytokininsto the basal medium. Longitudinal cell division of the tendril,which takes place parallel or obliquely to the long axis, wasstimulated by cytokinins, but not by sucrose. The latter typeof cell division was frequent in basal and sub-basal cells ofthe tendril but was extremely rare in apical cells. The orientationof the planes of these cell divisions was closely related tocell shape. Abnormal growth of the tendril was seen in germinatingseeds grown for six weeks or more in media containing both Miscanthus(a host) root extract and cytokinin. (Received February 23, 1984; Accepted June 12, 1984)