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PubMed1997

DNA polymorphism at the Pgi locus of a wild yam, Dioscorea tokoro.

To study the origin and maintenance mechanisms of the PGI allozyme polymorphism of a wild plant, Dioscorea tokoro, DNA sequences of the entire coding region (1701 bp) and two intronic regions (total 2049 bp) of the Pgi gene as well as a part of the Adh gene (590 bp) were analyzed. Two replacement substitutions were revealed to be responsible for the differentiation of three allozymes alleles (Pgi-a, Pgi-b and Pgi-c) that occur in natural population in intermediate frequencies. Interspecific comparison of DNA sequences identified Pgi-b as the oldest allele, from which two other alleles were derived probably within the last 150,000 years. The level of DNA polymorphism at D. tokoro Pgi locus was low. No elevated level of DNA polymorphism was detected in the close vicinity of the two replacement sites differentiating the three allozymes. Departures from the neutral mutation hypothesis were detected by Fu and Li's and MK tests. The observed patterns of DNA polymorphism are explainable by both (1) the neutral mutation hypothesis with an assumption of small effective size of D. tokoro population, and (2) the positive selection hypothesis that the allele frequencies of Pgi-a and Pgi-c have increased in a short time by their selective advantages.

Alcohol Dehydrogenase↗
PubMed1980

Multiple components of alpha-amylase in germinating tubers of a yam, Dioscorea dumetorum.

alpha-Amylase from germinating tubers of a yam Dioscorea dumetorum was extracted and purified by four steps of purification. A total yield of 23.1% was obtained with over 1,600-fold increase in specific activity. Three distinct amylolytically active protein forms were resolved upon treatment of the preparation on DEAE-cellulose ion exchange chromatography at pH 8.3. All the partially purified alpha-amylase fractions have similar physical properties with respect to pH optimum, Km values, molecular weights, and energies of activation. Qualitative paper chromatographic analysis of the alpha-amylase-amylose digest revealed variable product specificity for the three alpha-amylase fractions. One form exhibited a dual product specificity for the formation of maltose and maltohexaose, while another form produced exclusively maltopentaose from polysaccharide substrates. The third amylase fraction showed usual action pattern characteristic of most alpha-amylases.

Amylases↗
PubMed1994

Occupational asthma caused by two herb materials, Dioscorea batatas and Pinellia ternata.

There have been very few cases of occupational allergies caused by herb materials. In this paper, we report a case of occupational asthma and rhinitis caused by two herb materials, Dioscorea batatas and Pinellia ternata, which are known as Sanyak and Banha respectively. The patient had strong positive responses to grass pollens and cat fur, as well as to Sanyak and Banha extracts on skin-prick tests. Bronchoprovocation tests showed a dual asthmatic response to Sanyak whereas only an early asthmatic response to Banha. Serum specific IgE and IgG4 antibodies to Sanyak were detected by enzyme-linked immunosorbent assay (ELISA) but there was no specific IgE antibody binding to Banha. In order to further characterize the allergenic component of these extracts, sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and electroblotting studies were also performed. Three IgE binding components (29,000, 57,000, 63,000 Da) were detected within the Sanyak extracts, but no IgE-binding component was noted within the Banha extracts. It is suggested that Sanyak can induce IgE-mediated bronchoconstriction in an exposed worker. Further studies are needed to investigate the pathogenetic mechanism triggered by Banha.

Adult↗
PubMed1994

Microsatellite polymorphism in Dioscorea tokoro, a wild yam species.

Six microsatellite loci were characterized in Dioscorea tokoro, a wild yam species in East Asia. All six loci were polymorphic in a sample of 23 individuals from natural populations in Japan. The microsatellite loci displayed many alleles (6.2 alleles per locus on average), and the observed heterozygosity (Ho = 0.54) as well as expected heterozygosity (He = 0.68) were high. The heterozygosities were far more than that previously detected by allozyme analysis of D. tokoro (Ho = 0.23, He = 0.28). Five microsatellite loci were sufficient to provide a paternity exclusion rate (Q) of Q = 0.98, which enables monitoring of the pollen-mediated gene flow between plants in a population. Microsatellite loci are abundant and highly polymorphic in D. tokoro and other plants and are therefore ideal markers for plant population genetic studies.

Alleles↗
PubMedDate not supplied

Peroxidase-polyphenol oxidase association in Dioscorea esculenta.

A crude enzyme extract from Dioscorea esculenta var. fasiculata tissue subjected to ion exchange chromatography on DEAE-Sephadex A-50 column. This procedure resolved the extract into two main protein peaks one of which eluted through the column relatively unbound while the other protein peak which remained bound to the column was eluted with 1.0 M NaCl. Both protein peaks contained polyphenol oxidase (PPO) and peroxidase (POD) activities. The non-binding protein peak was resolved by gel filtration on Sephadex G-200 into distinct PPO and POD activities and by virtue of their apparent molecular weights of 95.5 Kd and 38.0 Kd for PPO and POD respectively were determined to be the typical enzymes. The PPO activity was completely inhibited invitro by 5 mM polyvinyl pyrrolidone (PVP). The binding protein peak was not resolved by gel filtration. It contained PPO activity which was not inhibited by PVP and a POD activity which was completely inhibited by dithiothreitol (DTT) This ionic protein peak contained 60% of total POD in the tissue, has an apparent molecular weight of 56 Kd and is suggested to be a strongly anionic peroxidase which also exhibits polyphenol oxidase activity.

Catechol Oxidase↗
PubMedDate not supplied

Influence of different light intensities on the content of diosgenin, lipids, carotenoids and fatty acids in leaves of Dioscorea zingiberensis.

Cultivation of the climbing plant Dioscorea zingiberensis at a light intensity of 100 microE. m(-2) sec(-1) yields three different phenotypes. Most of the plants grow as green phenotype (DzW). Two further forms differ in their leaf shape and leaf color. Whereas one type exhibits a more pointed leaf shape in the upper part of the plant with leaves appearing yellow-green with white stripes or hatchings (DzY), the other type shows a more round leaf shape with an intensive yellow-green color (DzT). These three plant types differ in their diosgenin content not only in their rhizomes but also in the chloroplasts. In the rhizomes the diosgenin content in the green form is 0.4%, in the DzY-form 0.6% and in the DzT-form even 1.3% of the dry weight. Furthermore, even in chloroplasts of the green DzW-form and of the DzY-form the presence of diosgenin was demonstrated. It occurs there as the epimeric form yamogenin. The DzT-form contains no yamogenin in its chloroplasts. Besides this, these plant forms differ in their chlorophyll and carotenoid content and in their fatty acid composition. Carotenoids increase from 1.3% of total lipids in the green phenotype to 3.3% in the DzY- and to 4.2% in the DzT-form. This increase refers to beta-carotene as well as to lutein and neoxanthin. The chlorophyll content in the green type is 8.1% and lower in the DzY-form with 7%. The highest chlorophyll content is found in the DzT-form with 12%. Fatty acids in the DzY-form and in the DzT-form have a more unsaturated character than in the green phenotype. The content of the monoenoic acid trans-hexadecenoic acid is considerably lower in both phenotypes when compared to the green phenotype. In both phenotypes the quantity of fatty acids with 16 carbon atoms is reduced, whereas fatty acids with 18 carbon atoms occur in higher concentration. Cultivation of the green phenotype (DzW) at the three light intensities of 10, 100 and 270 microE x m(-2) x sec(-1) leads to changes of the diosgenin content in rhizomes, to an increase of leaf dry weight, to a reduction of the grana structure in chloroplasts and therewith to a decrease of the chlorophyll content. The total lipid content is highest under the cultivation at 100 microE x m(-2) x sec(-1) and reduced by 30% at 10 and 270 microE x m(-2) x sec(-1). Carotenoids, however, are highest in shaded plants (10 microE x m(-2) x sec(-1)) and plants grown under high light conditions of 270 microE x m(-2) x sec(-1). At 100 microE x m(-2) x sec(-1) a decrease of saturated fatty acids is observed in comparison to plants grown under shaded conditions.

Carotenoids↗
PubMed1992

Purification and characterization of invertase inhibitors from Dioscorea rotundata tuber.

Three invertase inhibitors (A), (B) and (C) from Dioscorea rotundata tuber were resolved on DEAE-cellulose ion exchanger. Two of the inhibitors, (B) and (C), were proteins and homogenous on polyacrylamide gels Mr 21,000 +/- 85 and 26,982 +/- 40/36,307 +/- 50 respectively. The inhibitors (B) and (C) were inactivated at 60 degrees C and had activity-pH optima at 5.2 and 6.4 respectively. (B) and (C) were non competitive inhibitors of invertase from yam and other sources.

Animals↗
PubMedDate not supplied

[Use of enzymic preparations during diosgenine isolation from Dioscorea caucasica Lipsky].

The use of enzymic preparations of the cellulolytic and macerating effect was studied as applied to the isolation of diosgenine from rhizomes of Dioscorea caucasica Lypsky. The enzymic treatment of the steroid containing raw material prior to acid hydrolysis increased the yield of diosgenine by 30-48%. It is suggested that additional extraction of diosgenine takes place due to: 1) enzymic hydrolysis of structural polysaccharide components of the plant tissue and intercellular binding materials and 2) disintegration of glycoside bonds of saponins.

Cellulase↗
PubMed1992

The complete amino acid sequence of yam (Dioscorea japonica) chitinase. A newly identified acidic class I chitinase.

The complete amino acid sequence of acidic chitinase from yam (Dioscorea japonica) aerial tubers was determined. The protein is composed of a single polypeptide chain of 250 amino acid residues and has a calculated molecular mass of 27,890 Da. There is an NH2-terminal domain, a hinge region, and a main structure, typical for class I chitinases (Shinshi, H., Neuhaus, J.-M., Ryals, J., and Meins, F., Jr. (1990) Plant Mol. Biol. 14, 357-368). We have obtained the first evidence for an acidic class I chitinase. Comparison with sequences of other class I chitinases revealed approximately 40% sequence similarity, a value lower than that for other class I chitinases (70-80%). We assume that there is a local conformational change in the molecule; cysteine residues that probably form disulfide bonds are completely conserved, with the exception of Cys-178. The difference in structure between this chitinase and other basic class I chitinases suggests that acidic and basic isoforms should be grouped into subclasses; this protein is an ethylene- or a pathogen-independent chitinase produced by a gene that is inherent in the tuber.

Amino Acid Sequence↗
PubMed2006

[Research of polysaccharide from Dioscorea opposita Thunb].

OBJECTIVE: To isolate a homogeneous polysaccharide RP from RDP (a crude polysaccharide from Dioscorea opposita Thunb.) , and study its preliminary composition and structure. METHODS: RP was obtained with water extraction, alcohol sedimentation, CTAB deprotein, cellulose column and SephadexG-100 column. The purities of RP were identified by SephadexG-200. PC analysis on its acidic hydrolysates was used to determine the sugar components. Sephadex chromatography was used to mensurate its molecular weight. IR was used to analysis RP. RESULTS: RP was homogeneous. IR indicated that RP had beta configurations. The compositon was identified by paper chromatography as glucose, D-mannose, D-galactose. CONCLUSION: The research could provide a theoretical foundation for further development and utilization.

Dioscoreaceae↗
PubMed1989

[Research on correlations between climatic factors and diosgenin content in Dioscorea zingiberensis Wright].

Dioscorea zingiberensis wright is native to China. In this paper correlations between seven climatic factors (mean annual temperature, mean annual relative humidity, mean annual 5 cm soil temperature, annual precipitation. Annual sunshine hours, mean annual sunshine percentage and annual greater than or equal to 10 degrees C accumulative temperature) and diosgenin content has been reported. It is annual precipitation and mean annual 5 cm soil temperature that are real principal factors affecting the diosgenin content. The most suitable climatic range for the biosynthesis and accumulation of diosgenin is as follows: Annual precipitation: 800-900 mm, 850 mm the best. Mean annual 5 cm soil temperature: 15-17 degrees C, 16 degrees C the best.

Diosgenin↗
PubMedDate not supplied

[Steroid saponins from the rhizomes of Dioscorea caucasica Lipsky].

Deltonin or diosgenin-3-0-alpha-L-rhamnopyranosyl-(1----2)-[beta-D- glucopyranosyl-(1----4)-]-beta-D-glucopyranoside, m. p. 282 degrees, [alpha] 20(546): -96.4 degrees (c 1, pyridine) and a new oligospirostanoside beta-D-glucopyranosyl-(1----3'' Glcp)-deltonin, m. p. 242-243 degrees, [alpha]20(546): -63.7 degrees (c 1, pyridine) were isolated from rhizomes of Dioscorea caucasica.

Plants, Medicinal↗
PubMed1993

[Effect of processing on phospholipid of Dioscorea opposita Thunb].

A study of the chemical changes of phospholipid in crude and seven processed samples of Dioscorea opposita was carried out by molybdenum blue colorimetry and TLCS. The result shows that the total phospholipid content in the sample processed by honey bran comes out the highest (180.31 mg/100g).

Chromatography, Thin Layer↗
PubMed2005

Biological control of postharvest fungal rot of yam (Dioscorea spp.) withBacillus subtilis.

The potential of isolates of Bacillus subtilis from yam farm soil to control rot of yam in storage barns was investigated. Yam tubers inoculated in vivo with B. subtilis showed no rot while those inoculated with Aspergillus niger, Botryodiploidia theobromae or Penicillium oxalicum showed considerable rot. The set of yams in which B. subtilis and the fungi were simultaneously inoculated produced rot whereas those in which B. subtilis was inoculated a day before the fungi was inoculated were totally reduced or free of rot. Many fewer fungi were isolated from the surface of tubers treated with B. subtilis than from the untreated (control) and there was high recovery of B. subtilis (99-100%) throughout the period of storage. Rot build up was faster in uninoculated control tubers or those inoculated with a spoilage fungus, while those treated with the antagonist were totally reduced or free of rot. The culture filtrate of B. subtilis prevented spore germination in some spoilage fungi. The importance of this study in relation to farmers in developing countries is discussed.

Bacillus subtilis↗