Zaragozic acids production from discomycetes

In search for new zaragozic acids and their derivatives that are potent inhibitors of squalene synthase, discomycetes of the order Leotiales were cultured and their fermentation broth was assayed. Three strains in 2 unidentified species ofMollisia were found to produce zaragozic acid D3 and three new analogs (F-10863s). Fermentative production, productivity of F-10863s and mycological characteristics of the producers are described. Discomycetes are expected to be a biological resource providing novel bioactive compounds.     

A physio-anthropological study of the POS system space scanner

1. 1. We compared the functions of POS system scanners by measuring electromyograms and joint angles during scanning in this paper.

2. 2. We have demonstrated that the space scanner is physically easy to use, movement of the wrist is natural and easy, the most suitable method for scanning perishable foods which spill easily or are fragile.

3. 3. A space scanner can be used with a bar code.

4. 4. Electromyograms were taken from M. deltoideus, M. biceps brachii, M. extensor carpi radialis longus and brevis, M. flexor carpi ulnaris muscles.

Solubilization of Jerusalem artichoke tuber chromatin by 2,4-dichlorophenoxyacetic acid

Chromatin from the tuber of the Jerusalem artichoke (Helianthus tuberosus) was solubilized in 2,4-dichlorophenoxyacetic acid (2,4-D) solution (100 mM) at pH 7.0. This solubilization was much affected by the pH; below 6.0 less chromatin was solubilized. The elution pattern of the products on gel filtration with Sepharose 4B showed that the solubilization was caused by the dissociation of the DNA and associated proteins. The pattern of polyacrylamide gel electrophoresis of histones extracted from the chromatin solubilized by 2,4-D was quite different from those of histones extracted from the original chromatin or from NaCl (2.0M) solubilized chromatin. The F1 and F3 fractions seemed to be little affected by 2,4-D, but the F2a1, F2a2 and F2b fractions were greatly decreased. In addition, the ratios of histones and non-histone proteins to DNA changed considerably in 2,4-D solubilized chromatin in an inverse manner. None of these changes were observed with NaCl. which suggests that the behaviour of 2,4-D for the solubilization of chromatin differs substantially from that of NaCl.     

Extrachromosomal Circular DNA from Nuclear Fraction of Higher Plants

To determine the cellular location of extrachromosomal circularDNA in higher plants, wheat (Triticum aestivum) and tobacco(Nicotiana tabacum) nuclei were isolated and purified, and theircircular DNAs were examined by electron microscopy. Covalentlyclosed circular (ccc) DNAs were found in nuclear fractions fromboth species. They showed a heterogeneous size distributionranging from 0.1 µm to more than 5 µm in contourlength, with a mean of 1.7 µm (5.3 kbp) for T. aestivumand 1.5 µm (4.7 kbp) for N. tabacum, respectively. Thisdistribution is significantly different from that for smallcircular DNAs in mitochondria. Small polydisperse circular (spc)DNA/protein complexes were also observed by a rapid microscalemethod of mica-press-adsorption for electron microscopy. Complexesof spcDNA/protein showed a similar size distribution to cccDNA.The average number of spcDNA/protein complexes per nucleus wasestimated at more than hundred. The origin and biological functionsof the nuclear circular DNAs are discussed. (Received February 13, 1985; Accepted August 8, 1985)     

Enhancing Effect of Zinc on <Emphasis Type="SmallCaps">l</Emphasis>-Histidine Transport in Rat Lung Microvascular Endothelial Cells

The aim of this study was to examine enhancing effect of l-histidine into cultured rat lung microvascular endothelial cells (LMECs), which constitute the gas–blood barrier. Uptake of l-histidine into LMECs markedly increased with the addition of ZnSO₄ (0.1 mmol/L), and this enhanced uptake of l-histidine was drastically reduced in the presence of the Na⁺-independent system L substrate, 2-amino-2-norbornanecarboxylic acid (BCH). However, the uptake of l-histidine together with ZnSO₄ was not reduced by the addition of metabolic inhibitor, 2,4-dinitrophenol, or sodium ion replacement. Moreover, the addition of the system N-substrate, l-glutamic acid γ-monohydroxamate did not significantly decrease the uptake of l-histidine with 143 mmol/L Na ⁺ + 1 mmol/L BCH. These results indicated that system-N transporter does not play a role in the uptake of l-histidine in the presence of ZnSO₄, suggesting that only system-L transporter is involved in the uptake of l-histidine, although l-histidine in the absence of ZnSO₄ was taken up by at least two pathways of Na⁺-dependent system-N and Na⁺-independent system-L processes into rat LMECs. The uptake of l-histidine into rat LMECs in the presence of ZnSO₄ was also found to be unaffected by pH (5.0–7.4), indicating that uptake of l-histidine into LMECs by the addition of zinc may not be involved in the H⁺-coupled transporters.     

Properties of the Circular Plasmid-like DNA Bl from Mitochondria of Cytoplasmic Male-sterile Rice

Mitochondrial DNA from suspension-cultured cells of the cytoplasmicmale-sterile rice line, A-58 CMS, was shown to contain fourminicircular DNAs. We chose for further examination the largestminicircular DNA, designated Bl. A molecular clone containingthe complete sequence of Bl was constructed and used to probemitochondrial and nuclear genomes by Southern hybridization.No evidence was found for the existence of integrated copiesof Bl in the main mitochondrial genomes of either male-sterileor fertile rice. Sequences homologous to Bl, however, were foundin nuclear genomes of both the male-sterile and the fertilerice. The complete nudeotide sequence of Bl (2,135 bp) was determined,and found to contain sequences homologous to those in the 1,913bp plasmid-like DNA of maize. (Received May 15, 1987; Accepted July 20, 1987)     

The responses to choline ions induced by transition metal ions in single water fibers of the frog glossopharyngeal nerve

In single water-sensitive fibers (water fibers) of the frogglossopharyngeal nerve, application of a solution of 500 mMcholine Cl to the tongue elicited responses of varying magnitude.Some water fibers (plain choline-insensitive water fibers) barelyresponded to the solution, while some water fibers (plain choline-sensitivewater fibers) exhibited a considerable response to this solution.NiCl₂. which is barely effective in producing neural responseat concentrations below 5 mM, induced the response of plaincholine-insensitrve water fibers to choline⁺ ions. It was confirmed,in a collision test, that the Ni²⁺-induced responses to choline⁺ions were derived from water fibers. However, NiCl₂ did notaffect the magnitude of me response generated by choline⁺ ionsin plain choline-sensitive water fibers. The concentration-responsecurve for choline Cl in the presence of 1 mM NiCl₂ for plaincholine-insensitive water fibers was similar to the curves obtainedin the absence of NiCl₂ for plain choline-sensitive water fibers.Other organic salts, such as tris(hydroxymethyl)arrdnomethane-HCl,triethanotamine-HCl and tetraethylammonium Cl, elicited no responseor only a very small response from water fibers, and NiCl₂ didnot affect these responses. It is suggested that there existsa choline receptor for the response to choline⁺ ions in theapical membrane of frog taste cells and that Ni²⁺ ions exposethe sites of such choline receptors, which are deeply embeddedin the receptor membrane, to the outside medium. The effectof Ni²⁺ ions results in an increase in the number of the cholinereceptor sites available for binding of choline⁺ ions. The rankorder of effectiveness of transition metal ions in elicitingthe appearance or enhancement of the response to choline Clwas Ni²⁺ > Co²⁺ > Mn²⁺. Mg²⁺ ions had no effect on theresponse to choline⁺ ions. A similar rank order was previouslyobtained in enhancement of the responses to Ca²⁺, Mg²⁺ and Na²⁺ions (Kitada, 1994a). It seems likely that the mechanism forenhancement or elicitation of the response to choline⁺ ionsby the transition metal ions has features in common with thatfor enhancement of the responses to Ca²⁺, Mg²⁺ and Na⁺ ions.     

Nitrate Reductase Activity and Nitrite in Native Pyrenoids Purified from the Green Alga Bryopsis maxima

The native, starchless pyrenoids purified from Bryopsis maximashowed NADH-nitrate reductase [NR, EC 1.6.6.1 [EC] ] activity andcontained nitrite. The specific activity of NR was 0.024 µmolNO₂ formed per min per mg of protein. The value was 80 timesgreater than that in the crude extract of chloroplasts. Theamount of nitrite in the pyrenoids was 2.37 µmol per mgof protein, showing that nitrite was concentrated by a factorof 66 times. These results suggest a physiological role forpyrenoids in the assimilation of nitrate. (Received November 15, 1989; Accepted February 27, 1990)