Yuko Ogiso

Reversible and irreversible stages in the transition of cell surface marker during the differentiation of pluripotent teratocarcinoma cell induced with retinoic acid

Abstract Treatment of a pluripotent teratocarcinoma cell line with retinoic acid (RA) results in the disappearance of peanut agglutinin (PNA) receptors, accompanied with the decrease in F9 antigens and the enhanced secretion of plasminogen activator. However, this type of differentiation was inhibited by feeder cells. Furthermore, the transition of PNA receptor was reversible on the cells treated with RA for 2 days and became irreversible by an additional 2-day treatment with RA. Thus, two stages of teratocarcinoma cell differentiation—reversible and irreversible—were demonstrated.

Induction of teratocarcinoma cell differentiation: Effect of the inhibitors of DNA synthesis

Induction of teratocarcinoma cell (F9) differentiation was studied by using inhibitors of DNA synthesis and several agents known to be differentiation inducers. Inhibition of DNA synthesis induced changes in cell surface marker F9 and stimulated the production of plasminogen activator (PA) in a manner that is dependent upon de novo synthesis of RNA and protein. The results thus indicate close association between inhibition of DNA synthesis and induction of cell differentiation. This approach will be useful in investigating the mechanism of teratocarcinoma cell differentiation.

Reconfirmation of replacement of magnesium ion requirement by polyamines in isoleucyl-tRNA formation in Escherichia coli.

Previously we reported that polyamines, such as spermine, spermidine and putrescine stimulate aminoacyl-tRNA formation in the absence of added Mg 2÷ [1 ] and that in the presence of polyamines, isoleucinedependent PPi-ATP exchange did not occur, whereas isoleucyl-tRNA formation did [2]. These findings were supported by other experiments in this laboratory [3-6] and elsewhere [7-9] . However, recently Thiebe [10] reinvestigated the effect of spermidine on aminoacylation and concluded that our results were due to contamination of the tRNA preparation with Mg 2÷, since he claimed that the Mg 2÷ required in aminoacylation could not be replaced by spermidine. This conclusion was supported by the report of Chakraburtty et al. [11]. Santi and Webster [12] also claimed that the stimulatory effects of polyamines which we had reported were artifacts due to Mg 2÷ contaminating the tRNA preparation. This paper reports that our previous finding that polyamines stimulate isoleucyl-tRNA formation in Escherichia coli in the absence of added Mg 2÷ is not due to contamination of our tRNA preparation with Mg 2+.

Mode of cell surface marker changes during retinoic acid-induced differentiation in pluripotent embryonal carcinoma cells

Pluripotent teratocarcinoma cell line, 311, was cultured in the presence of retinoic acid (RA) and studied for the processes of early marker changes associated with cell differentiation. The cell populations that have lost peanut agglutinin (PNA), Lotus tetragonolobus agglutinin (LTA) or wheat germ agglutinin (WGA) receptor increased in proportion to the period since the start of RA treatment. The kinetics of the appearance of these receptor-negative cell populations suggests that the differentiating cells lose lectin receptors in the order of PNA, LTA and WGA. However, the changes in F9 antigen(s) and LTA receptor occurred at an equal frequency in PNA+ and PNA- cells, indicating that, although the loss of lectin receptors takes place in a distinct order, the change in each receptor itself proceeds independently of the state of other lectin receptors.

Studies of nucleosides and nucleotides—LXI : Purine cyclonucleosides 23 synthesis of sulfoxides of adenine s-cyclonucleosides

Abstract 8,2′ - Anhydro - 8 - mercapto - 9 - β - d - arabinofuranosyladenine, 8,3′ - anhydro - 8 - mercapto - 9 - β - d - xylofuranosyladenine and 8,5′ - 8 - mercaptoadenosine were oxidized either with N-bromosuccinimide, t-butyl hypochlorite or performic acid to their 8-sulfoxides. Configuration of sulfoxides were determined to be S in former two cases. In the case of 8,5′-cyclonucleoside, both S - and R -compounds were obtained. UV, NMR and CD spectra of these sulfoxides were recorded.