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1.
The polyphenol oxidase (PPO) of field bean (Dolichos lablab) is a tetramer made up of two subunits of mass 29,000 and 31,000 Da. The amino acid sequence of the tryptic peptides showed
approximately 90% sequence identity to the d-galactose specific legume lectins. The haemagglutinating activity of a pure and homogenous preparation of PPO measured using
human erythrocytes was 1261 HAU mg−1 protein and was inhibited by d-galactose. Purification by galactose-sepharose chromatography also indicated that the PPO and haemagglutinating activities
were associated with a single protein. Crude extracts of other legumes did not exhibit PPO activity, yet cross reacted with
anti-PPO antibodies. This dual function protein with PPO and haemagglutinating activity is unique to field bean. The two activities
are independent of each other occurring at different loci on the protein. These observations further evidence and strengthen
the assumption that galactose specific legume lectins have enzymatic function. Both PPO and lectins are proteins that play
a vital role in the defense mechanism of plants. The complementarity of these two simultaneous and independent powerful defense
mechanisms exhibited by a single protein renders it a candidate gene for the development of inbuilt plant protection. 相似文献
2.
Luciano S. Pinto Celso S. Nagano Taianá M. Oliveira Tales R. Moura Alexandre H. Sampaio Henri Debray Vicente P. Pinto Odir A. Dellagostin Benildo S. Cavada 《Journal of biosciences》2008,33(3):355-363
A new galactose-specific lectin was purified from seeds of a Caesalpinoideae plant, Bauhinia variegata, by affinity chromatography on lactose-agarose. Protein extracts haemagglutinated rabbit and human erythrocytes (native and
treated with proteolytic enzymes), showing preference for rabbit blood treated with papain and trypsin. Among various carbohydrates
tested, the lectin was best inhibited by D-galactose and its derivatives, especially lactose. SDS-PAGE showed that the lectin,
named BVL, has a pattern similar to other lectins isolated from the same genus, Bauhinia purpurea agglutinin (BPA). The molecular mass of BVL subunit is 32 871 Da, determined by MALDI-TOF spectrometry. DNA extracted from
B. variegata young leaves and primers designed according to the B. purpurea lectin were used to generate specific fragments which were cloned and sequenced, revealing two distinct isoforms. The bvl gene sequence comprised an open reading frame of 876 base pairs which encodes a protein of 291 amino acids. The protein carried
a putative signal peptide. The mature protein was predicted to have 263 amino acid residues and 28 963 Da in size. 相似文献
3.
An in vitro plant regeneration protocol of Cymbidium faberi from immature seeds was established. The immature seeds of 50 days old started to form rhizomes 4 months after they were cultured on hormone free medium. The rhizomes multiplied 5 times when subcultured on the medium containing 1.0 mg l–1 -naphthalene acetic acid (NAA) for 40 days and more than 90% of the rhizomes initiated shoots within 60 days on the media containing 0.5 or 1.0 mg l–1 NAA plus 2.0 or 5.0 mg l–1N6-benzylaminopurine (BA). Plantlets were regenerated when the shoots were planted on the basal medium amended with 1 g l–1 activated charcoal for 50 days and the plantlets grew normally after transplanting. 相似文献
4.
Growth of alkaliphilic Bacillus halodurans C-125 both on agar plates and in liquid culture was inhibited by methyl-β-cyclodextrin (CD). Furthermore, resting cells of
the strain were lysed by contact with methyl-β-CD higher than 10 mM. α-CD also showed lysis activity against Bacillus and related strains. The activity was not observed with Gram-negative and Gram-positive bacteria except for Bacillus strains. Fluorescence staining and scanning electron microscopy of cells revealed that methyl-β-CD disrupted cell membranes,
and consequently, the cells were lysed. This is a novel physiological property of CDs. 相似文献
5.
Polysaccharides (pectin and intracellular and extracellular arabinogalactans) were isolated from campion callus culture cultivated on medium with varied concentrations of pectinase and beta-galactosidase. A decrease in contents of arabinose residues in pectin and arabinogalactans and of galactose residues in arabinogalactans was associated with an increase in the activities of alpha-L-arabinofuranosidase and beta-galactosidase upon addition of pectinase into the medium. Pectinase destroyed the high-molecular-weight (more than 300 kD) fraction of pectin and decreased the content of galacturonic acid residues. alpha-L-Arabinofuranosidase transformed arabinogalactan into galactan, and galactan was destroyed under the influence of galactosidase. The contents of arabinogalactan and/or galactan in the cells were decreased, and it was released into the culture medium. Pectin samples with low contents of arabinose and galactose in the side chains and galactan samples were obtained from the callus grown on the medium with beta-galactosidase. Cultivation of the plant cells on medium containing carbohydrases resulted in modification of pectin and arabinogalactan of the cell walls. 相似文献
6.
7.
Protoplasts isolated from wild cotton Gossypium davidsonii were cultured in KM8P medium supplemented with different phytohormones. The most effective combination was 0.45 μM 2,4-dichlorophenoxyacetic acid,
2.68 μM α-naphthaleneacetic acid and 0.93 μM kinetin and the division percentage at the 8th day was 30.78 ± 3.04 %. The density of protoplasts at 2–10 × 105 cm−3 was suitable for protoplast division and calli formation, with a division percentage of 32.21 ± 3.64 % and a plating efficiency
of 9.12 ± 2.61 % at the 40th day. The optimal osmotic potential was achieved using 0.5 M glucose or 0.1 M glucose plus 0.5 M mannitol. Protoplasts were
cultured in three ways, a double-layer culture system, with liquid over solid medium was proved to be the best way. Embryo
induction was further increased by addition of 0.14 μM gibberellic acid. 相似文献
8.
Beibei Huang Xiaojun Liu Xinglong Wang Yan Pi Juan Lin Jiong Fei Xiaofen Sun Kexuan Tang 《Molecular Biology》2005,39(5):684-695
9.
The bkdAB gene cluster, which encodes plausible E1 and E2 components of the branched-chain α-keto acid dehydrogenase (BCDH) complex,
was isolated from Streptomyces virginiae in the vicinity of a regulatory island for virginiamycin production. Gene disruption of bkdA completely abolished the production of virginiamycin M (a polyketide-peptide antibiotic), while the production of virginiamycin
S (a cyclodepsipeptide antibiotic) was unaffected. Complementation of the bkdA disruptant by genome-integration of intact bkdA completely restored the virginiamycin M production, indicating that the bkdAB cluster is essential for virginiamycin M biosynthesis, plausibly via the provision of isobutyryl-CoA as a primer unit. In
contrast to a feature usually seen in the Streptomyces E1 component, namely, the separate encoding of the α and β subunits, S. virginiae
bkdA seemed to encode the fused form of the α and β subunits, which was verified by the actual catalytic activity of the fused
protein in vitro using recombinant BkdA overexpressed in Escherichia coli. Supply of an additional bkdA gene under the strong and constitutive promoter ermE* in the wild-type strain of S. virginiae resulted in enhanced production of virginiamycin M, suggesting that the supply of isobutyryl-CoA is one of the rate-limiting
factors in the biosynthesis of virginiamycin M. 相似文献
10.
U. K. S. Shekhawat T. R. Ganapathi L. Srinivas V. A. Bapat T. S. Rathore 《Plant Cell, Tissue and Organ Culture》2008,92(3):261-271
An efficient method for Agrobacterium-mediated genetic transformation of embryogenic cell suspension cultures of Santalum album L. is described. Embryogenic cell suspension cultures derived from stem internode callus were transformed with Agrobacterium
tumefaciens harbouring pCAMBIA 1301 plant expression vector. Transformed colonies were selected on medium supplemented with hygromycin
(5 mg/l). Continuously growing transformed cell suspension cultures were initiated from these colonies. Expression of β-glucuronidase
in the suspension cultures was analysed by RT-PCR and GUS histochemical staining. GUS specific activity in the transformed
suspension cultures was quantified using a MUG-based fluorometric assay. Expression levels of up to 105,870 pmol 4-MU/min/mg
of total protein were noted in the transformed suspension cultures and 67,248 pmol 4-MU/min/mg of total protein in the spent
media. Stability of GUS expression over a period of 7 months was studied. Plantlets were regenerated from the transformed
embryogenic cells. Stable insertion of T-DNA into the host genome was confirmed by Southern blot analysis. This is the first
report showing stable high-level expression of a foreign protein using embryogenic cell suspension cultures in S. album.
U. K. S. Shekhawat and T. R. Ganapathi contributed equally to this work. 相似文献
11.
We have investigated the floral ontogeny of Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis (of the eucalypt group, Myrtaceae) using scanning electron microscopy and light microscopy. Several critical characters for establishing relationships between these genera and to the eucalypts have been determined. The absence of compound petaline primordia in Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis excludes these taxa from the eucalypt clade. Post-anthesis circumscissile abscission of the hypanthium above the ovary in Stockwellia, Eucalyptopsis and Allosyncarpia is evidence that these three taxa form a monophyletic group; undifferentiated perianth parts and elongated fusiform buds are characters that unite Stockwellia and Eucalyptopsis as sister taxa. No floral characters clearly associate Arillastrum with either the eucalypt clade or the clade of Stockwellia, Eucalyptopsis and Allosyncarpia.We gratefully acknowledge Clyde Dunlop and Bob Harwood (Northern Territory Herbarium) for collecting specimens of Allosyncarpia, and Bruce Gray (Atherton) for collecting specimens of Stockwellia. The Australian National Herbarium (CANB) kindly lent herbarium specimens of Eucalyptopsis for examination. This research was supported by a University of Melbourne Research Development Grant to Andrew Drinnan. 相似文献
12.
Evolutionary patterns of sequence divergence were analyzed in genes from the conifer genus Taxus (yew), encoding paclitaxel biosynthetic enzymes taxadiene synthase (TS) and 10-deacetylbaccatin III-10β-O-acetyltransferase
(DBAT). N-terminal fragments of TS, full-length DBAT and internal transcribed spacer (ITS) were amplified from 15 closely related Taxus species and sequenced. Premature stop codons were not found in TS and DBAT sequences. Codon usage bias was not found, suggesting that synonymous mutations are selectively neutral. TS and DBAT gene trees are not consistent with the ITS tree, where species formed monophyletic clades. In fact, for both genes, alleles
were sometimes shared across species and parallel amino acid substitutions were identified. While both TS and DBAT are, overall, under purifying selection, we identified a number of amino acids of TS under positive selection based on inference using maximum likelihood models. Positively selected amino acids in the N-terminal
region of TS suggest that this region might be more important for enzyme function than previously thought. Moreover, we identify
lineages with significantly elevated rates of amino acid substitution using a genetic algorithm. These findings demonstrate
that the pattern of adaptive paclitaxel biosynthetic enzyme evolution can be documented between closely related Taxus species, where species-specific taxane metabolism has evolved recently. 相似文献
13.
Herbaceous Echinochloa crusgalli var. frumentacea is highly resistant to a wide range of heavy metal concentrations. However, its detoxification mechanism has not been reported
yet. We exposed plants to 100 μM CdCl2 for 7 days then examined cadmium accumulation and its subcellular distribution in binding to ligands. Cd concentration increased
over the exposure period to a saturation point at day 5 when its level reached 1,732.41 μg g−1 dry weight, an amount about 820 times greater than that found in the control. In the roots, most Cd was distributed in the
insoluble fraction, perhaps because of an absorption mechanism at the root surface. Our profile for distribution revealed
two Cd-binding ligand peaks: a high molecular weight of 60 kDa and a 2.5-kDa Cd-binding ligand. The latter increased with
time and had a typical phytochelatin (PC) amino acid composition of predominantly cysteine, glutamate, and glycine (16.5%,
16.6%, and 11.9%, respectively). The ratio of glutamate/cysteine/glycine was 1.4:1.4:1.0, which is similar to that for other
typical PCs. 相似文献
14.
15.
Haande S Ballot A Rohrlack T Fastner J Wiedner C Edvardsen B 《Archives of microbiology》2007,188(1):15-25
With exception of South Africa, very little is known about the presence and abundance of toxic cyanobacteria and cyanobacterial blooms on the African continent. The close proximity between society and nature, and the use of the sparse water resources as drinking water in large parts of Africa, lead to the recognition that more knowledge on toxic cyanobacterial blooms is of major importance. The bloom forming cyanobacterium Microcystis aeruginosa is known to produce cyclic heptatoxins (microcystins) which can be toxic to humans. In this study the morphological, genetic, and chemical characters of 24 strains of M. aeruginosa from several water bodies in Kenya and Uganda, some of them used as drinking water sources, were examined. The M. aeruginosa strains possessed different levels of diversity depending on characterisation method. Four morphotypes were identified based on the traditional morphological approach, 10 genotypes by DNA sequence comparison of the PC-IGS and ITS1 rDNA regions, and 10 chemotypes based on MALDI-TOF-MS oligopeptide analysis. Only 4 of the 24 isolated strains from East Africa were found to produce microcystins, while oligopeptides belonging to the aeruginosin and cyanopeptolin class were detected in most strains. 相似文献
16.
Elaine O’Connell Patrick Murray Charles Piggott Franck Hennequart Maria Tuohy 《Journal of applied phycology》2008,20(5):557-565
A β-N-acetylglucosaminidase produced by a novel fungal source, the moderately thermophilic aerobic ascomycete Talaromyces emersonii, was purified to apparent homogeneity. Submerged fermentation of T. emersonii, in liquid medium containing algal fucoidan as the main carbon source, yielded significant amounts of extracellular N-acetylglucosaminidase activity. The N-acetylglucosaminidase present in the culture-supernatant was purified by hydrophobic interaction chromatography and preparative
electrophoresis. The enzyme is a dimer with molecular weight and pI values of 140 and 3.85, respectively. Substrate specificity
studies confirmed the glycan specificity of the enzyme for N-acetylglucosamine. Michaelis-Menten kinetics were observed during enzyme-catalyzed hydrolysis of the fluorescent substrate
methylumbelliferyl-β-D-N-acetylglucosaminide at 50°C, pH 5.0 (Km value of 0.5 mM). The purified N-acetylglucosaminidase displayed activity over broad ranges of pH and temperature, yielding respective optimum values of pH
5.0 and 75°C. The T. emersonii enzyme was less susceptible to inhibition by N-acetylglucosamine and other related sugars than orthologs from other sources. The enzyme was sensitive to Hg2+, Co2+ and Fe3+. 相似文献
17.
Naveen Kumar Arora Ekta Khare Ji Hoon Oh Sun Chul Kang Dinesh K. Maheshwari 《World journal of microbiology & biotechnology》2008,24(4):581-585
Rhizoctonia solani and Phytophthora capsici are two of the most destructive phytopathogens occurring worldwide and are only partly being managed by traditional control
strategies. Fluorescent Pseudomonas isolates PGC1 and PGC2 were checked for the antifungal potential against R. solani and P. capsici. Both the isolates were screened for the ability to produce a range of antifungal compounds. The results of this study indicated
the role of chitinase and β-1,3-glucanase in the inhibition of R. solani, however, antifungal metabolites of a non-enzymatic nature were responsible for inhibition of P. capsici. The study confirmed that multiple and diverse mechanisms are adopted by the same antagonist to suppress different phytopathogens,
as evidenced in case of R. solani and P. capsici. 相似文献
18.
A lectin present in seeds of Trigonella foenumgraecum was isolated and purified by acid precipitation, salt fractionation, and affinity chromatography on mannan cross-linked agarose.
SDS-PAGE revealed a single band corresponding to a molecular weight of 27,350 daltons. The lectin agglutinated trypsin-treated
rat erythrocytes. Sugar specificity as determined by hemagglutination inhibition assay indicated that the lectin belongs to
a glucose/mannose-specific group. The reaction of the lectin with glycoprotein was affected by pH changes. The carbohydrate
binding specificity of the lectin was investigated by turbidity and activity measurements. As the lectin belongs to the Leguminoceae
family, the specificity of the lectin for glucose/mannose renders it a valuable tool for Rhizobium-legume symbiosis.
Published in Russian in Biokhimiya, 2007, Vol. 72, No. 1, pp. 52–57. 相似文献
19.
Summary. A novel practical method for the synthesis of N-methyl-DL-aspartic acid 1 (NMA) and new syntheses for N-methyl-aspartic acid derivatives are described. NMA 1, the natural amino acid was synthesized by Michael addition of methylamine to dimethyl fumarate 5. Fumaric or maleic acid mono-ester and -amide were regioselectively transformed into beta-substituted aspartic acid derivatives.
In the cases of maleamic 11a or fumaramic esters 11b, the α-amide derivative 13 was formed, but hydrolysis of the product provided N-methyl-DL-asparagine 9 via base catalyzed ring closure to DL-α-methylamino-succinimide 4, followed by selective ring opening. Efficient methods were developed for the preparation of NMA-α-amide 13 from unprotected NMA via sulphinamide anhydride 15 and aspartic anhydride 3 intermediate products. NMA diamide 16 was prepared from NMA dimethyl ester 6 and methylamino-succinimide 4 by ammonolysis. Temperature-dependent side reactions of methylamino-succinimide 4 led to diazocinone 18, resulted from self-condensation of methylamino-succinimide via nucleophyl ring opening and the subsequent ring-transformation. 相似文献
20.
Qi Zhu Fengtao Wu Feng Ding Dong Ye Yongqin Chen Yi Li Yang Zhifan 《Plant Cell, Tissue and Organ Culture》2009,96(3):317-324
Dioscorea zingiberensis Wright has been cultivated as a pharmaceutical crop for production of diosgenin, a precursor for synthesis of various important
steroid drugs. Because breeding of D. zingiberensis through sexual hybridization is difficult due to its unstable sexuality and differences in timing of flowering in male and
female plants, gene transfer approaches may play a vital role in its genetic improvement. In this study, the Agrobacterium tumefaciens-mediated transformation of D. zingiberensis was investigated with leaves and calli as explants. The results showed that both leaf segments and callus pieces were sensitive
to 30 mg/l hygromycin and 50–60 mg/l kanamycin, and using calli as explants and addition of acetosyringone (AS) in cocultivation
medium were crucial for successful transformation. We first immersed callus explants in A. tumefaciens cells for 30 min and then transferred the explants onto a co-cultivation medium supplemented with 200 μM AS for 3 days. Three
days after, we cultured the infected explants on a selective medium containing 50 mg/l kanamycin and 100 mg/l timentin for
formation of kanamycin-resistant calli. After the kanamycin-resistant calli were produced, we transferred them onto fresh
selective medium for shoot induction. Finally, the kanamycin resistant shoots were rooted and the stable incorporation of
the transgene into the genome of D. zingiberensis plants was confirmed by GUS histochemical assay, PCR and Southern blot analyses. The method reported here can be used to
produce transgenic D. zingiberensis plants in 5 months and the transformation frequency is 24.8% based on the numbers of independent transgenic plants regenerated
from initial infected callus explants. 相似文献