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.     

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)。     

Characterization of potassium channels in pancreatic beta cells from ob/ob mice

The patch-clamp technique in the cell-attached mode was used to study the K channels present in the membrane of cultured pancreatic beta cells from ob/ob mice. Three types of K+ channels were regularly observed, with conductances of 64, 20 and 146 pS. The conduction and kinetic properties of the 64 pS channel were similar to those of the ATP-sensitive potassium channel from normal beta cells. Furthermore, glucose blocked the activity of this channel at the same concentrations as that reported for normal cells. The 20 pS and the 146 pS were insensitive to glucose. The latter K+ channel appears to be similar to the large conductance voltage-activated potassium channels described in normal rodent beta cells. Thus, potassium channels in ob/ob pancreatic beta cells in culture are in most respects normal. Other factors may account for the abnormal electrical response to glucose of ob/ob pancreatic islets, such as reversible impairment of their function in vivo or defects not related to potassium permeability.     

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.     

Synchronization of 9L rat brain tumor cells by centrifugal elutriation

Asynchronous 9L cells were separated into relatively homogeneously-sized populations using centrifugal elutriation with both a conventional collection method and a long collection method. A substantial increase in the homogeneity of the volume distributions and in the degree of synchrony of the separated fractions was obtained using the long collection method. Autoradiographic data indicated that fractions containing ≥97% G₁ cells, ≥80% S cells, and 70–75% G₂ cells could be routinely recovered with this procedure. Recovery in these fractions varied from 5 to 8% of the total number of cells elutriated. The colony forming efficiency (CFE) of cells from fractions representing each phase of the cell cycle was a constant 60–70%, which was comparable to the 60–80% usually found for asynchronous 9L cells. The percentage of cells in the G₁, S, and G₂ phases in the elutriated fractions was more accurately determined from the volume distribution than from computer fits of the DNA histogram obtained from flow cytometry. In general, the degree of synchrony was related to the coefficient of variation (CV) of the volume distributions of the elutriated fractions. The CV was about 14% for all elutriated fractions. When the ≥97% G₁ population was allowed to progress to S and G₂, the CVs were about 17 and 20.2%, respectively. Thus, the best nonperturbing method for obtaining synchronous 9L cells in the S or G₂ phases was direct elutriation with the long collection method.     

The structure of monellin and its relation to the sweetness of the protein.

The sweet protein monellin [1-3] has been shown to consist of two non-identical subunits of 50 and 42 amino acid residues, which were separated electrophoretically and chromatographically. Automatic sequential Edman degradation gave the complete sequence of the longer subunit, and a partial sequency of the shorter one. It was found that the sweetness of monellin requires the undissociated molecule. The individual subunits were not sweet, neither did they block the sweet sensation of sucrose or monellin. Blocking of the single SH of monellin abolished its sweetness as did reaction of the single methionyl residue with CNBr. Since the cysteinyl and methionyl residues appear to be adjacent, it is suggested that this part of the molecule is essential for its sweetness.