Heterogeneity of high affinity uptake of L-glutamate and L-aspartate in the mammalian central nervous system.

Characteristics of high affinity uptake of L-glutamate are examined in order to evaluate the possible use of the uptake of [3H]L-glutamate, [3H]L-aspartate or any other suitable [3H]-labelled substrate as a marker for glutamatergic and aspartergic synapses in autoradiographic studies in the mammalian brain. Review of data on substrate specificity indicates the presence of at least two high affinity uptake systems specific for acidic amino acids in the central nervous tissue; one which takes up L-glutamate and L-aspartate and the other which is selective for L-glutamate only. Studies on ionic requirements, too, point to the existence of at least two distinct uptake systems with high affinity for L-glutamate. The Na(+)-dependent uptake system(s) handle(s) both L-glutamate and L-aspartate whereas the Na(+)-independent uptake system(s) show(s) selectivity for L-glutamate only. Available data do not favour the Na(+)-dependent binding of [3H]D-aspartate to thaw-mounted sections of frozen brain tissue as a suitable marker for glutamatergic/aspartergic synaptic nerve endings. However, there are reasons--such as the results of lesion studies and the existence of uptake sites which have a higher affinity for L-aspartate than for D-aspartate--to suggest that Na(+)-dependent binding of [3H]L-aspartate, rather than that of [3H]D-aspartate, should be further investigated as a possible marker for the glutamatergic/aspartergic synapses in the autoradiographic studies using sections of frozen brain.     

Analysis of styryl-based inhibitors of the lymphocyte tyrosine protein kinase p56lck.

Several styryl-based compounds were evaluated for their capacity to act as inhibitors of the non-receptor tyrosine protein kinase p56lck. Our results demonstrate that alpha-cyanocinnamamide compounds can inhibit both the in vitro tyrosine autophosphorylation of p56lck as well as p56lck phosphorylation of exogenous substrates. Compound 67B-83-A was found to inhibit p56lck protein kinase activity with a calculated IC50 of 7 to 10 microM. This compound did not significantly inhibit the tyrosine protein kinase activity of the epidermal growth factor receptor and was found to be a less effective tyrosine protein kinase inhibitor for other members of the src family of protein kinases.     

Promotive effect of chrysanthemic acids on adventitious root formation in some plants

Adventitious root formation in excised cucumber (Cucumis sativus L.) cotyledons was significantly promoted by (±)-cis-chrysanthemic acid at 0.006–1.8 mM. The effect of (±)-cis-chrysanthemic acid on indole-3-acetic acid (IAA)-induced rooting was additive. Rooting in excised cucumber cotyledons was significantly promoted by several isomers of chrysanthemic acid and sodium (±)-cis-chrysanthemate at 0.18 mM. Rooting in mung bean (Phaseolus radiatus L.) hypocotyls was also stimulated by the sodium salt at 0.06–0.6 mM. Rooting of kidney bean (Phaseolus vulgaris L.) hypocotyls was also clearly enhanced by sodium (±)-cis-chrysanthemate at 0.18–6 mM.     

Protection against acute paraquat toxicity by ambroxol

An expression vector for G-CSF, pASLB3-3, was constructed and introduced into Namalwa KJM-1 cells (Hosoi et al., 1988), and cells resistant to 100 nM of methotrexate (MTX) were obtained. Among them, the highest producer, clone SC57, was selected and the productivity of this clone was further characterized. The maximal production of G-CSF was at the most 1.8 g/ml/day using a 25 cm² tissue culture flask, even though the cell number was above 7×10⁵ cells/ml. The limiting factors at high density were analyzed as the deficiency of nutrients, such as glucose, cysteine and serine, and pH control. The depression of specific G-CSF productivity per cell under the batch culture conditions was overcome by using a perfusion culture system, Biofermenter^TM (Sato, 1983) with modifications of nutrients supplementation by a dialysis membrane and/or dissolved oxygen (DO) supplementation by microsilicone fibers. ITPSGF medium was modified to elevate concentrations of amino acids and glucose by 2.0- and 2.5-times, respectively. Under the control of pH at 7.4 and DO at 3 ppm, the specific G-CSF productivity was not depressed even at high cell density (above 1×10⁷ cells/ml), and the amount of G-CSF reached 41 g/ml. These results indicated the possibility of finding the optimum culture conditions for the production of recombinant proteins by Namalwa KJM-1 cells.Abbreviations ABTS 2,2-Azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid - BSA Bovine Serum Albumin - BSA-PBS Phosphate-buffered Saline without Ca²⁺ and Mg²⁺ containing Bovine Serum Albumin - dhfr Dihydrofolate Reductase - DO Dissolved Oxygen - G-CSF Granulocyte Colony-stimulating Factor - HEPES 4-(2-Hydroxyethyl)-1-piperazineethansulfonic Acid - IFN Interferon - MTX Methotrexate - PBS(-) Phosphate-buffered saline without Ca²⁺ and Mg²⁺ - Tween-PBS Phosphate-buffered saline without Ca²⁺ and Mg²⁺ containing 0.05% of Tween 20     

玉米未成熟胚乳愈伤组织和器官的发生及其倍性变化的初步研究

本试验在附加和不附加外源激素的MS培养基上,均得到了玉米未成熟胚乳愈伤组织。愈伤组织在附加外源激素的MS培养基上达到器官分化,获得了发育正常的和许多畸形的胚乳植株。所得到的愈伤组织细胞和植株根尖细胞染色体数目和倍性是不稳定的,二者有相同的趋向,其中有整倍体的细胞(2n=10,20,30,40,50),也有各种非整倍体的细胞(2n=5—49)。     

DISCOVERY OF MONOGRAPTIDS IN BASAL PART OF LOWER SILURIAN FROM S. ANHUI WITH SPECIAL REFERENCE TO THEIR ORIGIN

For a long time, the evolutionary series of a idoraptids-dimorphograptids-monograptids has been generally recognized by graptolite researchers. In the past years, the akidograptids were found to appear in the Lower Silurian Parakidograptus acuminatus Zone, while the dimorphograptids in the P. acuminatus and Orthograpius vesiculosus Zones, but the monograptids appeared as late as in the O. vesiculosus zone; this evolutionary series can be easily accepted by other people. Chen Xu and Lin Yao-kun (1978) pu...     

Analysis of endo-beta-N-acetylglucosaminidase activity by high-pressure liquid chromatography on a silica-based chemically bonded octadecyl column

We have devised a new method for assaying the endo-β-N-acetylglucosaminidase activity by using the dansyl asparaginyl oligosaccharide, (Man)₅(GlcNAc)₂-Asn-DNS, as the substrate and analyzing the product, GlcNAc-Asn-DNS, by a reverse-phase high-pressure liquid chromatography using a silica-based chemically bonded octadecyl column (Waters μBondapack C₁₈). The column is eluted with 8% acetonitrile in 25 mm sodium borate buffer, pH 7.5, at 3 ml/min. The effluent is monitored by a Perkin-Elmer LC-75 uv monitor at 213 nm and a Perkin-Elmer LC-1000 fluorescence monitor (excitation, 313 nm; emission, 540 nm). Under these conditions, GlcNAc-Asn-DNS is well separated from (Man)₅(GlcNAc)₂-Asn-DNS and the analysis can be completed in 5 min. The peak height is used to quantify the dansyl derivatives. Under the conditions described above, the lower limit of detection is 0.1 nmol of dansyl glycopeptides.