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1.
Li WB Gerstmann U Giussani A Oeh U Paretzke HG 《Radiation and environmental biophysics》2008,47(1):101-110
The mysterious death of Mr. Alexander Litvinenko who was most possibly poisoned by Polonium-210 (210Po) in November 2006 in London attracted the attention of the public to the kinetics, dosimetry and the risk of this high
radiotoxic isotope in the human body. In the present paper, the urinary excretion of seven persons who were possibly exposed
to traces of 210Po was monitored. The values measured in the GSF Radioanalytical Laboratory are in the range of natural background concentration.
To assess the effective dose received by those persons, the time-dependence of the organ equivalent dose and the effective
dose after acute ingestion and inhalation of 210Po were calculated using the biokinetic model for polonium (Po) recommended by the International Commission on Radiological
Protection (ICRP) and the one recently published by Leggett and Eckerman (L&E). The daily urinary excretion to effective dose
conversion factors for ingestion and inhalation were evaluated based on the ICRP and L&E models for members of the public.
The ingestion (inhalation) effective dose per unit intake integrated over one day is 1.7 × 10−8 (1.4 × 10−7) Sv Bq−1, 2.0 × 10−7 (9.6 × 10−7) Sv Bq−1 over 10 days, 5.2 × 10−7 (2.0 × 10−6) Sv Bq−1 over 30 days and 1.0 × 10−6 (3.0 × 10−6) Sv Bq−1 over 100 days. The daily urinary excretions after acute ingestion (inhalation) of 1 Bq of 210Po are 1.1 × 10−3 (1.0 × 10−4) on day 1, 2.0 × 10−3 (1.9 × 10−4) on day 10, 1.3 × 10−3 (1.7 × 10−4) on day 30 and 3.6 × 10−4 (8.3 × 10−5) Bq d−1 on day 100, respectively. The resulting committed effective doses range from 2.1 × 10−3 to 1.7 × 10−2 mSv by an assumption of ingestion and from 5.5 × 10−2 to 4.5 × 10−1 mSv by inhalation. For the case of Mr. Litvinenko, the mean organ absorbed dose as a function of time was calculated using
both the above stated models. The red bone marrow, the kidneys and the liver were considered as the critical organs. Assuming
a value of lethal absorbed dose of 5 Gy to the bone marrow, 6 Gy to the kidneys and 8 Gy to the liver, the amount of 210Po which Mr. Litvinenko might have ingested is therefore estimated to range from 27 to 1,408 MBq, i.e 0.2–8.5 μg, depending
on the modality of intake and on different assumptions about blood absorption. 相似文献
2.
The release of radioactive particles through large gaps in the containment of the destroyed Chernobyl reactor was assessed during two measurement periods. In 1996–1999, a total radionuclide flow rate of 274 Bq s−1 or 8.64 × 109 Bq year−1 was determined. These releases were predominantly due to 137Cs (78.5%), 90Sr (21.1%), and 239+240Pu (0.4%). The mean activity concentration in the aerosol measured directly at the gaps was about 240 mBq m−3 with an activity median aerodynamic diameter (AMAD) of 2.4 μm for 137Cs, 120 mBq m−3 with an AMAD in the range 3.1–13 μm for 90Sr, 1.8 mBq m−3 with an AMAD in the range 3.5–11 μm for 239+240Pu, and 2.0 mBq m−3 with an AMAD of 1.5 μm for 241Am. The resulting total inhalation dose rate calculated close to the gaps was about 100 nSv h−1. In the near environment, the mean 137Cs activity in the aerosol was 2.2 mBq m−3 with an AMAD of 2.2 μm, which gave rise to an inhalation dose rate of about two orders of magnitude lower than the corresponding dose rate at the gaps. Occasionally, however, dose levels were measured in the near environment that were similar to those at the gaps. In 2000–2003, lower activity concentrations were observed. The decrease was more pronounced at the gaps than in the near environment. The results indicate that effective dose due to inhalation must be considered for the dose assessment of construction workers who will be deployed at the Chernobyl site to reconstruct the old or to build the new Shelter, in the future. 相似文献
3.
Schimmack W Gerstmann U Oeh U Schultz W Schramel P 《Radiation and environmental biophysics》2005,44(3):183-191
The basic features of the leachability of depleted uranium (DU) projectiles in soil was investigated by using 12 projectiles
(145–294 g DU) and 16 columns installed in an air-conditioned laboratory. Two soils widely distributed in Europe, a sandy-loamy
cambisol and a silty-loamy luvisol, were filled into the columns (3.3 kg dry soil each). The effluents of all columns were
collected weekly during the observation period of 1 year. In 648 samples, 235U and 238U were determined by inductively coupled plasma mass spectrometry. The leaching rates of 238U from natural uranium were in general about 0.01 μg week-1 or smaller, while those of 238U from the DU munitions varied considerably and reached values of up to 100 μg week-1, for the different columns. In total, about 0.3 μg natural uranium corresponding to 20 ppm of its inventory in the soil was
leached during the observation period. From the projectiles, an average of about 50 μg DU were leached corresponding to 18 ppm
of the corroded DU mass (about 1.6% of the mean initial DU mass of the projectiles). Assuming that corrosion and leaching
continue as observed, the mobilisation of 238U from DU munitions will last, on an average, for thousands of years in the soils investigated, while the munitions themselves
will have been corroded after a much shorter time. It is proposed to use, for the investigated soil types, the mean leaching
rates of the six columns with projectiles for transport calculations of 238U to the groundwater and, thus, for a better risk assessment of the water-dependent uptake pathways of DU. 相似文献
4.
Diana M. Cheng Gad G. Yousef Mary H. Grace Randy B. Rogers J. Gorelick-Feldman I. Raskin Mary Ann Lila 《Plant Cell, Tissue and Organ Culture》2008,94(1):73-83
In order to develop a sustainable source of metabolism-enhancing phytoecdysteroids, cell suspension and hairy root cultures
were established from shoot cultures of wild-harvested Ajuga turkestanica, a medicinal plant indigenous to Uzbekistan. Precursors of phytoecdysteroids (acetate, mevalonic acid cholesterol) or methyl
jasmonate (an elicitor) were added to subculture media to increase phytoecdysteroid accumulation. In cell suspension cultures,
20-hydroxyecdysone (20E) content increased 3- or 2-fold with the addition of 125 or 250 μM methyl jasmonate, respectively,
compared to unelicited cultures. Precursor addition, however, did not provoke phytoecdysteroid accumulation. In hairy root
cultures, addition of sodium acetate, mevalonic acid, and methyl jasmonate, but not cholesterol, increased phytoecdysteroid
content compared to unelicited cultures. Hairy root cultures treated with 150 mg l−1 sodium acetate, or 15 or 150 mg l−1 mevalonic acid, increased 20E content approximately 2-fold to 19.9, 20.4 or 21.7 μg mg−1, respectively, compared to control (10.5 μg mg−1). Older hairy root cultures, extracted after the seventh subculture cycle, also showed increases in 20E content (24.8 μg mg−1), turkesterone (0.9 μg mg−1) and cyasterone (8.1 μg mg−1) compared to control cultures maintained for a shorter duration of four subculture cycles. Doses of 10 or 20 μg ml−1 hairy root extract increased protein synthesis by 25.7% or 31.1%, respectively, in a C2C12 mouse skeletal cell line. These
results suggest that sustainable production of metabolically active phytoecdysteroid can be achieved through hairy root culture
systems.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
5.
M. Vanko D. Rauová L. Bezáková I. Holková F. Bilka M. Cupáková 《Biologia Plantarum》2012,56(1):105-110
Lipoxygenase (LOX) from opium poppy (Papaver somniferum L.) chloroplasts was isolated and 126.1-fold purified to electrophoretic homogeneity by combination of ion-exchange chromatography
on HA-Ultragel column and affinity chromatography on a linoleyl-aminopropyl agarose column. The relative molecular mass of the LOX determined
by SDS-PAGE was 92 kDa. Kinetic properties of purified LOX were determined in spectrophotometric assay by using of linoleic
acid (KM = 1.78 mM and Vmax = 11.4 μmol mg−1 min−1) and linolenic acid (KM = 1.27 mM and Vmax = 10.2 μmol mg−1 min−1). The optimum pH was 6.0 for both linoleic and linolenic acid dioxygenation catalyzed by LOX. HPLC analysis of the products
revealed a dual positional specificity of linoleic acid dioxygenation at pH 6.0 with ratio of 9- and 13-hydroperoxide products
being about 1:1. The activity of purified LOX was stimulated by Mg2+ and Ca2+. 相似文献
6.
Artemisinin production by hairy roots of Artemisia annua L. was increased 6-fold to 1.8 μg mg−1 dry wt over 6 days by adding 150 mg chitosan l−1. The increase was dose-dependent. Similar treatment of hairy roots with methyl jasmonate (0.2 mM) or yeast extract (2 mg ml−1) increased artemisinin production to 1.5 and 0.9 μg mg−1 dry wt, respectively. 相似文献
7.
Pakkasmaa S Penttinen OP Piironen J 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2006,176(5):387-391
The metabolic rate (specific heat output) of individual eyed-stage eggs of Arctic charr Salvelinus alpinus (Linnaeus, 1758) originating from different families was measured with direct microcalorimetry. Metabolic rates varied between 2.3–7.9 μW ind−1 and 0.06–0.22 μW mg−1. Absolute heat output was unrelated to egg size, but size-scaled or specific heat output was negatively correlated with egg size, measured as diameter, dry mass or fresh mass. Metabolic rates varied significantly between families, suggesting that genetic and/or maternal effects affect embryonic metabolism in Arctic charr. Heat output increased almost linearly from 3.4 to 16.7 μW ind−1 (0.09–0.67 μW mg−1) during the embryonic development. Although the metabolic rate varied between the families and egg metabolic rate increased during development, there was an unexpected disconnect between metabolic rate and hatching time. 相似文献
8.
The assessment doses due to ingestion of 137Cs and 90Sr for the population suffering from the Chernobyl accident was performed on the basis of the new mechanistic ecological model
for assessment of radiological consequences of agricultural lands contamination (EMARC). The EMARC model allows estimation
of internal doses based on ecological factors influencing the contamination of foodstuff, for the post-accidental years in
the countries of the former Soviet Union. The EMARC model allows estimation of all quantities required in radiation hygiene
practice. For example, the proposed analytical method may be used for both retrospective dose reconstruction and prospective
estimates of annual dose and integrated “life-time” dose, for different age intervals. According to the EMARC model, estimated
reference “life-time” doses for adults are between 7 and 269 μSv kBq−1 m2 for 137Cs, and between 25 and 235 μSv kBq−1 m2 for 90Sr. Maximal doses were estimated for persons who were 3, 9 and 11 years old, at the time of the accident and these doses exceed
those for adults by a factors of 1, 5 for 90Sr, and 1.4 for 137Cs. 相似文献
9.
Mature embryonic axes were used for chickpea (Cicer arietinum L.) regeneration via somatic embryogenesis. Qualitative and quantitative estimation of protein profile during somatic embryogenesis by SDS-PAGE and densitometric analysis showed differential expression of various storage proteins at different stages of somatic embryo development, which was compared with the profile of developing seeds. Total protein content in somatic embryos of chickpea increased from globular stage [2.9 μg mg−1(f.m.)] to cotyledonary stage [4.8 μg mg−1(f.m.)] and then started decreasing during onset of maturation and germination [up to 1.5 μg mg−1(f.m.)]. Differential expression of seed storage proteins, late embryogenesis abundant (LEA) proteins and proteins related with stress response were documented at different stages of somatic embryogenesis. Germinating somatic embryos showed degradation products of several seed storage proteins and the appearance of new polypeptides (76.8, 67.6, 49.9 and 34.2 kDa), which were absent during differentiation of somatic embryos. A low molecular mass (17.7 kDa) polypeptide was uniformly present during all stages of somatic embryogenesis and it may belong to a group of stress-related proteins. This study describes the expression of true seed storage proteins like legumin, vicilin, convicilin and their subunits at different stages of somatic embryogenesis, which may serve as excellent markers for embryogenic pathway of regeneration in chickpea. 相似文献
10.
Masmoudi Raja Rival Alain Nato Aimé Lavergne Danièle Drira Nourredine Ducreux Georges 《Plant Cell, Tissue and Organ Culture》1999,57(2):139-143
While describing major trends of carbon metabolism during the initiation and expression of somatic embryogenesis in date palm
(Phoenix dactylifera L., cv. Deglet Nour), we have investigated the role of two carboxylases, namely PEPC (Phosphoenolpyruvate
carboxylase, EC 4.1.1.31) and RubisCO (Ribulose 1,5-bisphosphate carboxylase/oxygenase, EC 4.1.1.39), in embryogenic and non-embryogenic
cultures. The detection of PEPC activity on polyacrylamide native gels after electrophoresis revealed the presence of 3 active
isoforms in crude extracts from the embryogenic (E) callus strain, whereas only a single band was present in the non-embryogenic
(NE) one. The level of PEPC specific capacity was of the same order (3.9 ± 1.2 μmol CO2 h−1 mg−1 TSP) in both types of cultures. Further changes in carboxylase (PEPC and RubisCO) activities during the growth and development
of somatic embryo–derived plantlets were also analysed. The PEPC/RubisCO ratio was found to progressively decrease (from 17.7
to 0.2) throughout the in vitro development of plantlets, due to a substantial depletion of PEPC activity, which decreased
from 5.3 to 1.2 μmol CO2 h−1 mg−1 TSP. Concomitantly, RubisCO assumed greater importance (from 0.3 to 5.3 μmol CO2 h−1 mg−1
TSP
) and became the main route for inorganic carbon fixation. Western blot analysis using polyclonal antibodies raised against
PEPC and RubisCO purified from tobacco leaves confirmed this trend in terms of relative enzyme abundance.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
11.
12.
Fungal biomass in the decaying cones ofPinus densiflora was investigated. Leaching, immobilization and mobilization phases were recognized in the decomposition process of cones.
Fungal biomass was estimated by the agar-film technique, using a conversion factor of 0.62 mg dry wt. mm−3 of hyphal volume to biomass and a factor of 2.5 for in-efficiencency of homogenization. The fungal biomass was 4.9±2.1 (mean±S.D.)
mg dry wt. g−1 dry matter in the cones on the tree, 11±6 mg g−1 in the leaching phase, 19±7 mg g−1 in the immobilization phase and 30±15 mg g−1 in the mobilization phase. It significantly increased after cones had lain on the forest floor, and also in the immobilization
phase. The latter result suggests that the fungal biomass contributed to the immobilization of nitrogen in the decomposition
process. The ratio of ergosterol content to fungal biomass in the cones was 2.9–8.8 μg mg−1 dry wt., lying in the range of 2–16 μg mg−1 reported for mycelia. This suggested that the estimate of fungal biomass was reasonable. Reduction in this ratio with the
dry weight loss in the cones suggested that the proportion of relatively active fungal biomass decreased with the progress
of decomposition. 相似文献
13.
Liang C Xiao W Hao H Xiaoqing L Chao L Lei Z Fashui H 《Biological trace element research》2008,121(3):249-257
Mg2+ in various concentrations was added to purified Rubisco in vitro to gain insight into the mechanism of molecular interactions
between Mg2+ and Rubisco. The enzyme activity assays showed that the reaction between Rubisco and Mg2+ was two order, which means that the enhancement of Rubisco activity was accelerated by low concentration of Mg2+ and slowed by high concentration of Mg2+. The kinetics constant (K
m) and V
max was 1.91 μM and 1.13 μmol CO2 mg−1 protein∙min−1, respectively, at a low concentration of Mg2+, and 3.45 μM and 0.32 μmol CO2∙mg−1 protein∙min−1, respectively, at a high concentration of Mg2+. By UV absorption and fluorescence spectroscopy assays, the Mg2+ was determined to be directly bound to Rubisco; the binding site of Mg2+ to Rubisco was 0.275, the binding constants (K
A) of the binding site were 6.33 × 104 and 5.5 × 104 l·mol−1. Based on the analysis of the circular dichroism (CD) spectra, it was concluded that the binding of Mg2+ did not alter the secondary structure of Rubisco, suggesting that the observed enhancement of Rubisco carboxylase activity
was caused by a subtle structural change in the active site through the formation of the complex with Mg2+. 相似文献
14.
S A Shaikh J M Khire M I Khan 《Journal of industrial microbiology & biotechnology》1997,19(4):239-245
A thermostable β-galactosidase was produced extracellularly by a thermophilic Rhizomucor sp, with maximum enzyme activity (0.21 U mg−1) after 4 days under submerged fermentation condition (SmF). Solid state fermentation (SSF) resulted in a nine-fold increase
in enzyme activity (2.04 U mg−1). The temperature range for production of the enzyme was 38–55°C with maximum activity at 45°C. The optimum pH and temperature
for the partially purified enzyme was 4.5 and 60°C, respectively. The enzyme retained its original activity on incubation
at 60°C up to 1 h. Divalent cations like Co2+, Mn2+, Fe2+ and Zn2+ had strong inhibitory effects on the enzyme activity. The K
m and V
max for p-nitrophenyl-β- D-galactopyranoside and o-nitrophenyl-β - D-galactopyranoside were 0.39 mM, 0.785 mM and 232.1 mmol min−1 mg−1 respectively. The K
m and V
max for the natural substrate lactose were 66.66 μM and 0.20 μ mol min−1 mg−1.
Received 10 March 1997/ Accepted in revised form 17 July 1997 相似文献
15.
Two endoglucanases were purified to electrophoretic homogeneity from the culture filtrate of a mutant strain Trichoderma sp. M7. EG-III and EG-IV had Mr of 49.7 and 47.5 kDa, and estimated pi values of 3.7 and 6.35, respectively. The optimal pH and
temperature values were determined to be pH 5.0 and 60°C for the first cellulase, whereas pH 5.2 and 50 °C were optimal for
the other. Endoglucanases exhibited typical Michaelis-Menten kinetics with K
m and V values of 2.9 mg ml−1 and 60498.5 μmol min−1 mg−1 for EG-III and 3.8 mg ml−1 and 22650.9 μmol min−1 mg−1 for EG-IV, respectively. Mn2+, Cu2+ and Pd2+ strongly inhibited the enzymes. EC-IV catalyzed the hydrolysis of Na-CMC and hydroxyethyl cellulose (HEC) only, whereas EG-III
displayed high activity towards xylans, also. Different preferences towards cellulosic substrates and their regions define
a different role of the investigated enzymes in the degradation of plant biomass.
Published in Russian in Prikladnaya Biokhimiya i Mikrobiologiya, 2009, Vol. 45, No. 2, pp. 171–175.
The article is published in the original. 相似文献
16.
Glutathione-S-transferase (GST) was isolated from the northern hardshell clam Mercinaria mercinaria (quahog) using a two-step procedure involving ammonium sulfate precipitation and affinity chromatography. Kinetic analysis
of the purified enzyme using 1-chloro-2,4-dinitrobenzene as substrate revealed a specific activity of 38.0 μmol min−1 mg−1, while V
max and K
m
values were estimated as 48.0 μmol min−1 mg−1 and 0.24 mM, respectively. Electrophoretic analysis of GST indicated multiple forms of the dimeric enzyme in quahogs with
subunit molecular masses of 22, 24, 25, and 27 kDa. Isoelectric focusing analysis resulted in pI values for three isoenzymes
of 5.1, 4.9, and 4.6. The acidic pI values obtained indicated that quahog GST belongs to the π class. Inhibition of quahog
GST by tetrapyrroles was similar to that of GST from oyster and rat liver. Quantitative comparison of tetrapyrrole inhibition
patterns of quahog GST with those of oyster and rat liver GST indicated lower inhibition rates by three of the four tetrapyrroles
tested (bilirubin, biliverdin, and chlorophillyin), suggesting that quahog GST could differ structurally or functionally from
oyster and rat liver GSTs.
Received March 17, 1998; accepted August 18, 1998. 相似文献
17.
Biodegradation of BTEX by a microbial consortium isolated from a closed municipal landfill was studied using respirometric
techniques. The kinetics of biodegradation were estimated from experimental oxygen uptake data using a nonlinear parameter
estimation technique. All of the six compounds were rapidly degraded by the microbial culture and no substrate inhibition
was observed at the concentration levels examined (200 mg L−1 as COD). Microbial growth and contaminant degradation were adequately described by the Monod equation. Considerable differences
were observed in the rates of BTEX biodegradation as seen from the estimates of the kinetic parameters. A three-fold variation
was seen in the values of the maximum specific growth rate, μmax. The highest value of μmax was 0.389 h−1 for p-xylene while o-xylene was characterized by a μmax value of 0.14 h−1, the lowest observed in this study. The half saturation coefficient, K
s, and the yield coefficient, Y, varied between 1.288–4.681 mg L−1 and 0.272–0.645 mg mg−1, respectively. Benzene and o-xylene exhibited higher resistance to biodegradation while toluene and p-xylene were rapidly degraded. Ethylbenzene and m-xylene were degraded at intermediate rates. In biodegradation experiments with a multiple substrate matrix, substrate depletion
was slower than in single substrate experiments, suggesting an inhibitory nature of substrate interaction.
Received 15 February 1998/ Accepted in revised form 5 July 1998 相似文献
18.
The objective of the present work is to apply the plasma clearance parameters to strontium, previously determined in our laboratory,
to improve the biokinetic and dosimetric models of strontium-90 (90Sr) used in radiological protection; and also to apply this data for the estimation of the radiation doses from strontium-89
(89Sr) after administration to patients for the treatment of the painful bone metastases. Plasma clearance and urinary excretion
of stable strontium tracers of strontium-84 (84Sr) and strontium-86 (86Sr) were measured in GSF-National Research Center for Environment and Health (GSF) in 13 healthy German adult subjects after
intravenous injection and oral administration. The biological half-life of strontium in plasma was evaluated from 49 plasma
concentration data sets following intravenous injections. This value was used to determine the transfer rates from plasma
to other organs and tissues. At the same time, the long-term retention of strontium in soft tissue and whole body was constrained
to be consistent with measured values available. A physiological urinary path was integrated into the biokinetic model of
strontium. Parameters were estimated using our own measured urinary excretion values. Retention and excretion of strontium
were modeled using compartmental transfer rates published by the International Commission on Radiological Protection (ICRP),
the SENES Oak Ridge Inc. (SENES), and the Urals Research Center for Radiation Medicine (TBM). The results were compared with
values calculated by applying our GSF parameters (GSF). For the dose estimation of 89Sr, a bone metastases model (GSF-M) was developed by adding a compartment, representing the metastases, into the strontium
biokinetic model. The related parameters were evaluated based on measured data available in the literature. A set of biokinetic
parameters was optimized to represent not only the early plasma kinetics of strontium but also the long-term retention measured
in soft tissue and whole body. The ingestion dose coefficients of 90Sr were computed and compared with different biokinetic model parameters. The ingestion dose coefficients were calculated
as 2.8 × 10−8, 2.1 × 10−8, 2.5 × 10−8 and 3.8 × 10−8 Sv Bq−1 for ICRP, SENES, TBM and GSF model parameters, respectively. Moreover, organ absorbed dose for the radiopharmaceutical of
89Sr in bone metastases therapy was estimated based on the GSF and ICRP biokinetic model parameters. The effective doses were
3.3, 1.8 and 1.2 mSv MBq−1 by GSF, GSF-M, and ICRP Publication 67 model parameters, respectively, compared to the value of 3.1 mSv MBq−1 reported by ICRP Publication 80. The absorbed doses of red bone marrow and bone surface, 17 and 21 mGy MBq−1 calculated by GSF parameters, and 7.1 and 8.8 mGy MBq−1 by GSF-M parameters, are comparable to the clinical results of 3–19 mGy MBq−1 for bone marrow and 16 mGy MBq−1 for bone surface. Based on the GSF-M model, the absorbed dose of 89Sr to metastases was estimated to be 434 mGy MBq−1. The strontium clearance half-life of 0.25 h from the plasma obtained in the present study is obviously faster than the value
of 1.1 h recommended by ICRP. There are no significant changes for ingestion dose coefficients of 90Sr using different model parameters. A model including the metastases was particularly developed for dose estimation of 89Sr treatment for the pain of bone metastases. 相似文献
19.
J. Vijaya Kumar B. D. Ranjitha Kumari G. Sujatha Enrique Castaño 《Plant Cell, Tissue and Organ Culture》2008,93(1):85-96
The present study describes a system for efficient plant regeneration via organogenesis and somatic embryogenesis of safflower
(Carthamus
tinctorius L.) cv. NARI-6 in fungal culture filtrates (FCF)-treated cultures. FCF was prepared by culturing Alternaria carthami fungal mycelia in selection medium for host-specific toxin production. Cotyledon explants cultured on callus induction medium
with different levels of FCF (10–50%) produced embryogenic callus. In organogenesis, 42.2% microshoots formed directly from
embryogenic callus tissues in plant regeneration medium with 40% FCF. Isolated embryogenic callus cultured on embryo induction
medium containing 40% FCF induced 50.2% somatic embryogenesis. Embryo germination percentage was decreased from 64.5 to 28
in embryo maturation medium containing 40% FCF. However, nine plantlets from organogenesis and 24 plantlets from somatic embryogenesis
were selected as FCF-tolerant. Alternaria carthami fungal spores (5 × 105 spores/ml) sprayed on the leaves of FCF-tolerant plants showed enhanced survival rate over control plants, which plants were
more susceptible to fungal attack. The number of leaf spot lesions per leaf was decreased from 3.4 to 0.9 and their lesion
length was also reduced from 2.9 to 0.7 mm in organogenic derived FCF-tolerant plants over control. In somatic embryo derived
FCF-tolerant plants, the number of lesions was decreased from 3.1 to 0.4 and the lesion size was also reduced to 2.7–0.5 mm
when compared to the control. This study also examined antioxidant enzyme activity in FCF-tolerant plants. Catalase (CAT)
activity was slightly decreased whereas peroxidase (POD) activity was increased to a maximum of 42% (0.19 μmol min−1 mg−1 protein) from organogenesis and 47% (0.23 μmol min−1 mg−1 protein) from embryogenesis in FCF-tolerant plants. Superoxide dismutase (SOD) activity was also increased to 17% (149 U
mg−1 protein) and 19.5% (145 U mg−1 protein) in FCF-tolerant plants derived from organogenesis and somatic embryogenesis when compared with control plants. 相似文献
20.
Two carotenoid 1,2-hydratase (CrtC) genes from the photosynthetic bacteria Rubrivivax gelatinosus and Thiocapsa roseopersicina were cloned and expressed in Escherichia coli in an active form and purified by affinity chromatography. The biochemical properties of the recombinant enzymes and their
substrate specificities were studied. The purified CrtCs catalyze cofactor independently the conversion of lycopene to 1-HO-
and 1,1′-(HO)2-lycopene. The optimal pH and temperature for hydratase activity was 8.0 and 30°C, respectively. The apparent K
m and V
max values obtained for the hydration of lycopene were 24 μM and 0.31 nmol h−1 mg−1 for RgCrtC and 9.5 μM and 0.15 nmol h−1 mg−1 for TrCrtC, respectively. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis revealed two protein bands of 44 and
38 kDa for TrCrtC, which indicate protein processing. Both hydratases are also able to convert the unnatural substrate geranylgeraniol
(C20 substrate), which functionally resembles the natural substrate lycopene. 相似文献