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51.
Alcohol dehydrogenases of 89 species of plants, from the Bryophyta, Pteridophyta, Gymnosperms and Angiosperms were examined by starch gel electrophoresis for their substrate and coenzyme specificities. High activities and multiple bands were observed with EtOH and NAD in most species. The same, but weaker banding patterns were also observed with benzyl alcohol and salicin. When coniferyl alcohol was used as substrate, activity was found only with NADP as coenzyme and the resulting bands were distinct from those obtained with the other substrates. Most plants tested had only one or occasionally a second coniferyl alcohol dehydrogenase band. Salix species were an exception, with multiple bands found in each of the species tested. 相似文献
52.
53.
Differential inter- and intra-specific defense induction in Lupinus by Myzus persicae feeding 总被引:1,自引:0,他引:1
Yasmin J. Cardoza Jenny Reidy-Crofts & Owain R. Edwards 《Entomologia Experimentalis et Applicata》2005,117(2):155-163
Experiments were conducted to investigate the potential induction of plant defenses by Myzus persicae Sulzer (Homoptera: Aphididae) feeding on five lupin, Lupinus spp. (Leguminosae), varieties with well‐characterized levels of aphid resistance. Myzus persicae feeding on L. angustifolius and L. luteus varieties induced genotype‐specific changes in their host that were not consistent with the level of aphid resistance or the plant species. The plant responses were systemically detected by apterous and alate forms of the aphids. Chemical assays revealed no induction of oxidizing enzyme (catalase, peroxidase, or polyphenol oxidase) activity, serine or cystein proteinase inhibitors, or soluble phenolics in any of the five varieties tested following 3 days of feeding by 10 or 30 aphids. However, there were significant differences among the five lupin varieties in the levels of peroxidase and polyphenol oxidase activity, proteinase inhibitors, and soluble phenolics. 相似文献
54.
Kate Swift Natalie Moltschaniwskyj 《Journal of experimental marine biology and ecology》2005,315(2):177-186
The cephalopod digestive gland plays an important role in the efficient assimilation of nutrients and therefore the fast growth of the animal. The histological and enzymatic structure of Euprymna tasmanica was studied and used in this experiment to determine the dynamics of the gland in response to feeding. The major roles of the digestive gland were secretion of digestive enzymes in spherical inclusions (boules) and excretion of metabolic wastes in brown body vacuoles. High levels of trypsin, chymotrypsin and α-amylase, low levels of α-glucosidase and negligible carboxypeptidase activity were produced by the gland. There was no evidence of secretion of digestive enzymes in other organs of the digestive tract. Within 60 min of a feeding event, the gland produced increasing numbers of boules to replace those lost from the stomach during the feeding event. Initially, small boules were seen in the digestive cells, they increased in size until they are released into the lumen of the gland where they are transported to the stomach. There was no evidence of an increase in activity of digestive enzymes following a feeding event, despite structural changes in the gland. However, there was large variation among individuals in the level of digestive enzyme activity. A negative correlation between boule and brown body vacuole density suggested that the large variation in enzyme activity may be due to the digestive gland alternating between enzyme production and excretion. 相似文献
55.
真菌源激发子对采后葡萄果皮抗性产生的诱导 总被引:2,自引:2,他引:0
利用细胞壁提取法从葡萄采后致病菌Alternaria alternate(Fr.)Keissl中提取出激发子。在采前一周用激发子处理葡萄,研究激发子诱导葡萄采后抗病效果。结果表明:葡萄经激发子处理后,果皮内与抗病有关的过氧化物酶(POD)、多酚氧化酶(PPO)和苯丙氨酸解氨酶(PAL)活性显著增强,酚类物质和木质素含量也显著提高,贮藏期自然发病率和发病指数降低,其中以125μg·mL-1处理效果最好,果实发病率和发病指数比对照降低500%左右。 相似文献
56.
Carlos E. Aragón Maritza Escalona Iris Capote Danilo Pina Inaudis Cejas Roberto Rodriguez Maria Jesus Cañal Jorge Sandoval Sophe Roels Pierre Debergh Justo Gonzalez-Olmedo 《In vitro cellular & developmental biology. Plant》2005,41(4):550-554
Summary The photosynthetic capacity changes and the main enzymatic systems related to carbon metabolism were investigated during the
in vitro culture of plantain shoots (Musa AAB cv. CEMSA 3/4) in temporary immersion bioreactors (TIB) and their subsequent acclimatization.
The maximal rate of photosynthesis (Pn), transpiration, and the activity of the carbon metabolism enzymes phosphoenolpyruvate
carboxylase (PEPC), acid invertase (AI), pyruvate kinase (PK) and sucrose phosphate synthase (SPS) were measured every 7 d
during the 21 d of elongation in TIB, and the following 42 d of acclimatization. Sucrose content in the liquid medium and
in the leaves was also determined. The most significant changes in plant growth were observed during acclimatization. During
the in vitro stage photosynthesis was limited (4–6 μmol CO2m−2s−1); the photosynthetic rate however increases rapidly and significantly as soon as in vitro culture is over during acclimatization. PEPC activity increased during the whole evaluation period. The highest levels were
achieved around days 42 and 56. PK and SPS activities were optimal during the first weeks in acclimatization (28–35 d), while
AI increased at the beginning of the elongation phase (7 d), and later at the end of the acclimatization (49–63 d). The relationships
between morphological parameters, photosynthetic capacity of the plantlets and the carbon metabolism enzymes during both phases
of the culture are discussed. 相似文献
57.
Jian-Feng LI Robert QI Liang-Hu QU Autar K Mattoo Ning LI 《植物学报(英文版)》2005,47(11):1352-1363
1-Aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) is the principal enzyme in phytohormone ethylene biosynthesis. Previous studies have shown that the hypervariable C-terminus of ACS is proteolytically processed in vivo. However, the protease responsible for this has not yet been identified. In the present study, we investigated the processing of the 55-kDa full-length tomato ACS (LeACS2) into 52-, 50- and 49-kDa truncated isoforms in ripening tomato (Lycopersicon esculentum Mill. cv. Cooperation 903) fruit using the sodium dodecyl sulfate-boiling method. Meanwhile, an LeACS2-processing protease was purified via multi-step column chromatography from tomato fruit. Subsequent biochemical analysis of the 64-kDa purified protease revealed that it is a metalloprotease active at multiple cleavage sites within the hypervariable C-terminus of LeACS2. N-terminal sequencing and matrix-assisted laser desorption/ionization time-of-flight analysis indicated that the LeACS2-processing metalloprotease cleaves at the C-terminal sites Lys^438, Glu^447, Lys^448, Asn^456, Ser^460, Ser^462, Lys^463, and Leu^474, but does not cleave the N- terminus of LeACS2. Four C-terminus-deleted (26-50 amino acids) LeACS2 fusion proteins were overproduced and subjected to proteolysis by this metalloprotease to identify the multiple cleavage sites located on the N-terminal side of the phosphorylation site Ser^460. The results indisputably confirmed the presence of cleavage sites within the region between the α-helix domain (H14) and Ser^460 for this metalloprotease. Furthermore, the resulting C-terminally truncated LeACS2 isoforms were active enzymatically. Because this protease could produce LeACS2 isoforms in vitro similar to those detected in vivo, it is proposed that this metalloprotease may be involved in the proteolysis of LeACS2 in vivo. 相似文献
58.
《植物学报(英文版)》2005,47(11)
l-Aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) is the principal enzyme in phytohormone ethylene biosynthesis. Previous studies have shown that the hypervariable C-terminus of ACS is proteolytically processed in vivo. However, the protease responsible for this has not yet been identified. In the present study, we investigated the processing of the 55-kDa full-length tomato ACS (LeACS2) into 52-, 50- and 49-kDa truncated isoforms in ripening tomato (Lycopersicon esculentum Mill. cv.Cooperation 903) fruit using the sodium dodecyl sulfate-boiling method. Meanwhile, an LeACS2-processing protease was purified via multi-step column chromatography from tomato fruit. Subsequent biochemical analysis of the 64-kDa purified protease revealed that it is a metalloprotease active at multiple cleavage sites within the hypervariable C-terminus of LeACS2. N-terminal sequencing and matrix-assisted laser desorption/ionization time-of-flight analysis indicated that the LeACS2-processing metalloprotease cleaves at the C-terminal sites Lys438, Glu447, Lys448, Asn456, Ser460, Ser462, Lys463, and Leu474, but does not cleave the Nterminus of LeACS2. Four C-terminus-deleted (26-50 amino acids) LeACS2 fusion proteins were overproduced and subjected to proteolysis by this metalloprotease to identify the multiple cleavage sites located on the N-terminal side of the phosphorylation site Ser460. The results indisputably confirmed the presence of cleavage sites within the region between the α-helix domain (H14) and Ser460 for this metalloprotease.Furhermore, the resulting C-terminally truncated LeACS2 isoforms were active enzymatically. Because this protease could produce LeACS2 isoforms in vitro similar to those detected in vivo, it is proposed that this metalloprotease may be involved in the proteolysis of LeACS2 in vivo. 相似文献
59.
60.
Jacek Patykowski 《Acta Physiologiae Plantarum》2006,28(6):589-598
The aim of the research was to estimate the sensitivity of tomato tissue and spore from necrotrophic isolate of B. cinerea on H2O2. The influence of exogenic H2O2 and B. cinerea on plant tissue and on the activity of peroxidases (PO), catalase (CAT) and superoxide dismutase (SOD) in apoplastic tomato
leaves fraction were investigated.
It was proved that 40 mM H2O2 damaged the cells of a host, and inhibited in vitro germination of B.cinerea spores. Complete inhibition of germination was observed after the use 100 mM H2O2. In the presence of spores H2O2 was decomposed to H2O and O2. Trace activity of catalase was observed in a solution of spores used for inoculation. Necrosis which appeared on the leaves
after 40 mM H2O2 treatment resembled hypersensitive response. On the leaves pretreated at this concentration the development of infection
was observed. The H2O2 concentration harmful for the tissues, stimulated the PO activity measured with NADH — responsible for generation of ·O
2
−
, as well as with syringaldazine (S) and ferulic acid (FA), substrates characteristics of forms lignifying and strengthening
the cell wall. Clear increase in CAT activity, resulting from infection and early pretreatment with H2O2 was observed in apoplast. No effect on SOD activity was observed.
A hypothesis may be put forward, that germinating spores produce enzymes which allow them to decompose H2O2 generated in apoplast, so there is little likelihood that B. cinerea can be directly inhibited by reactive oxygen forms (ROS) during initial stages of infection. Necrotic lesions resembling
HR generated by exogenous H2O2 as well as induction of activity of apoplastic plant enzymes, particularly PO connected with strengthening and lignification
of cell wall, were not sufficient factors to inhibit fungal expansion. 相似文献