Liquid chromatographic determination of microcystins in water samples following pre-column excimer fluorescence derivatization with 4-(1-pyrene)butanoic acid hydrazide.

A method to measure the concentrations of microcystins (MCs) in water samples has been developed by incorporating pre-column fluorescence derivatization and liquid chromatography (LC). A solid-phase extraction for pretreatment was used to extract the MCs in water samples. The MCs were derivatized with excimer-forming 4-(1-pyrene)butanoic acid hydrazide (PBH). The MCs could then be detected by fluorescence after separation with a pentafluorophenyl (PFP)-modified superficially porous (core shell) particle LC column. The derivatization reactions of MCs with PBH proceeded easily in the presence of 4,6-dimethoxy-1,3,5-triazin-2-yl-4-methylmorpholinium (DMT-MM) as a condensation reagent, and the resulting derivatives could be easily separated on the PFP column. The derivatives were selectively detected at excimer fluorescence wavelengths (440-540 nm). The instrument detection limit and the instrument quantification limit of the MCs standards were 0.4-1.2 µg L(-1) and 1.4-3.9 µg L(-1), respectively. The method was validated at 0.1 and 1.0 µg L(-1) levels in tap and pond water samples, and the recovery of MCs was between 67 and 101% with a relative standard deviation of 11%. The proposed method can be used to quantify trace amounts of MCs in water samples.

Metal-tolerant moss Scopelophila cataractae accumulates copper in the cell wall pectin of the protonema.

The growth kinetics in the presence of copper (Cu) of the protonema of the moss Scopelophila cataractae and the matrix polysaccharides of its cell walls have been analyzed in this study. Protonemal cells cultured in a medium containing 0.2mM CuSO(4) showed a rapid accumulation of Cu, reaching a maximum between 30 and 60d at approximately 65 micromolg(-1) DW. Uronic acids were found in similar amounts in cell walls of both control and Cu-treated cells, whereas arabinose and galactose decreased to 61-67% in the presence of Cu. Cell wall polysaccharides were determined after successive extraction with 50mM CDTA, 50mM Na(2)CO(3), 1M KOH, and 4M KOH. The pectic fractions (CDTA- and Na(2)CO(3)-soluble) decreased to 47% and the hemicellulosic fractions (1M KOH- and 4M KOH-soluble) to 86% under Cu application. Approximately 43% of the Cu taken into cell walls was released following endo-pectate lyase treatment, suggesting that two-fifths of the total Cu accumulation was tightly bound to the homogalacturonan of the cell wall pectin.

Highly oxygenated labdane-type diterpenoids, ptychantins from cultured cells of the Ptychantus striatus liverwort.

One novel labdane-type diterpene, named ptychantin O, and two known diterpenes, ptychantin G and F, were isolated from cultured cells of the Phychanthus striatus liverwort, and their structures were determined by NMR spectroscopic analyses.

Lygodium japonicum fern accumulates copper in the cell wall pectin.

The present work reports the results of a study on the growth kinetics and characterization of matrix polysaccharides in the cell walls of Lygodium japonicum prothallium grown in the presence of copper (Cu). When the prothallium was cultured in the media containing 0.2 mM or 0.4 mM CuSO(4), it showed a rapid accumulation of Cu with a maximum uptake of Cu measured in the cells up to 20 d of culture. The maximum rate of Cu uptake into the prothallium was greater for 0.4 mM Cu-treated cells (17.2 micromol g(-1) DW) than for 0.2 mM Cu-treated cells (3.2 micromol g(-1) DW). Cell walls were isolated from both untreated control and Cu-treated cells and then extracted sequentially with cyclohexane-trans-1,2-diaminetetra-acetate (CDTA), Na(2)CO(3), 1 M KOH, and 4 M KOH. The amount of pectin solubilized from 0.4 mM Cu-treated cell walls decreased to 53% of its level in the control, whereas the amount of hemicellulose solubilized from the Cu-treated cell walls represented 82% of that from control cell walls. When the polysaccharides were fractionated by anion-exchange chromatography into four carbohydrate components, considerable increases in fractions PI-3 and PII-3 eluted with 0.5 M NaCl were observed in CDTA-soluble (PI) and Na(2)CO(3)-soluble (PII) pectic polymers from Cu-treated cell walls. Fractions PI-3 and PII-3 were composed predominantly of uronic acid (more than 71% of total sugars). Approximately 66% of Cu within the cell walls was released from the 0.4 mM Cu-treated cells with the endo-pectate-lyase treatment, suggesting that most of the Cu that accumulated into the Lygodium prothallium is tightly bound to the homogalacturonan of the cell wall pectin.

Molecular cloning and cytochemical analysis of exopolygalacturonase from carrot.

Exopolygalacturonase (exo-PGase, EC 3.2.1.67) attacks the non-reducing terminus of the polygalacturonic acid in pectic molecules, releasing galacturonic acid. We cloned the cDNA of exo-PGase purified from cell homogenates of suspension-cultured carrot ( Daucus carota L. cv. Kintoki) cells. The nucleotide sequence of the cDNA (1.4 kb) contains an open reading frame that encodes a 391-amino-acid polypeptide. Sequence homology research showed 97.9% identity to the glycoprotein EP4 obtained from cultured carrot cells and 49.3% identity to the ENOD8 gene product of alfalfa ( Medicago sativa). However, no significant similarity was found to known PGases. The Southern hybridization pattern indicated that this exo-PGase protein is a member of a small-sized gene family. Predominant expression of the exo-PGase gene was detected by in situ hybridization and immunohistochemistry in the root apical meristem and in the elongation region, but not in the root cap. A cross-immunoresponse with anti-exo-PGase also occurred in the root nodule meristem of alfalfa. These results suggest that this exo-PGase plays a role in the degradation of pectic molecules during root development.

Pectin-bound beta-galactosidase present in cell walls of carrot cells under the different calcium status.

Glycosyl-hydrolytic enzymes from suspension-cultured carrot (Daucus carota L. cv. Kintoki) cells grown in calcium (Ca2+)-deficient and normal liquid media were studied after extraction successively by K-phosphate (pH 7.0) and Na-acetate (pH 5.2) containing 3 M LiCl. The same activities were detected in two protein fractions from control and Ca2+-deprived cells. The specific activities of alpha-galactosidase and polygalacturonase decreased under Ca2+ deprivation, but beta-galactosidase activity in the buffer-soluble protein from Ca2+-deprived cells increased 1.7-fold compared to control cells. Upon ion exchange and size-exclusion chromatography the fraction (Ca-Ia-I) in the buffer-soluble protein from Ca2+-deprived cells represented beta-galactosidase activity associated with a galacturonic acid-rich polysaccharide peak, whereas the corresponding fraction could hardly be detected in the buffer-soluble protein from control cells. Several of the same glycosidase activities were detected in the extract solubilized with cyclohexane-trans-1,2-diaminetetra-acetate (CDTA) from active cell walls of Ca2+-deprived cells as in the extract of control cells, but the beta-galactosidase activity was considerably reduced under Ca2+ deprivation. Following the same chromatography the fraction (CDTA-Ca-1) of beta-galactosidase activity in the extract solubilized with CDTA from active cell walls of Ca2+-deprived cells was also completely overlapping with the peak of galacturonic acid-rich polysaccharide. The molecular mass of fractions Ca-Ia-I and CDTA-Ca-1 was 300 kDa, and the polysaccharides in these two fractions were composed of approximately equal amounts of rhamnosyl and galacturonosyl residues. These results suggest that the increase of beta-galactosidase in the buffer-soluble protein fraction from Ca2+-deprived cells is the result of solubilization of a part of the acidic pectic polymer-bound beta-galactosidase due to the structural changes in the cell walls that occur during Ca2+ deprivation.

Molecular cloning and in situ hybridization of alpha-l-arabinofuranosidase from carrot cells.

The cDNA of extracellular alpha-l-arabinofuranosidase (alpha-l-AFase, EC 3.2.1.55) secreted from suspension-cultured carrot cells (Daucus carota L. cv. Kintoki) was isolated and characterized. The nucleotide sequence of the cDNA (2.4 kb) revealed an open reading frame consisting of 655 amino acid residues. Sequence homology research showed 28.4% identity to the alpha-l-AFase A protein of Aspergillus niger. The genomic DNA was cloned by PCR, and the nucleotide ligature sequence showed 18 exons and 17 introns. The first intron was upstream of the initiation codon. In situ hybridization revealed that the alpha-l-AFase gene is expressed in the root meristem, elongation zone and the root hair of carrot seedlings, indicating that this enzyme may participate in cell proliferation and development of carrot root cells.