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1.
Manganese peroxidase (MnP) production by Phlebia sp. MG-60 is strongly regulated by Mn2+ and NH4+ at various sea salt incubation conditions. Extra-added Mn2+ and NH4+ obviously inhibited MnP production, but sea salts relieved the inhibition partially or completely. Three media were prepared: Kirk medium with addition of 0%–5% sea salts (KS medium), a high level of Mn2+ (300mg/l) in KS medium (HM-KS medium), and a high level of NH4+ (430mg/l) in KS medium (HN-KS medium). Without addition of sea salts, the dye Poly R-478 was significantly decolorized by low MnP activity (about 200U/l) and a low level of laccase activity (about 100U/l) in KS and HM-KS media. In the cultures in which laccase activity was almost completely inhibited by 3% and 5% sea salts, MnP activity higher than 400U/l was necessary for Poly R-478 decolorization in all of the three media. We first report the linear correlation of MnP activity and decolorization of Poly R-478 under saline conditions and the effect of laccase on this relation. 相似文献
2.
The process of peroxide bleaching of Populus tomentosa kraft pulp with H2O2 pretreatment under acid condition was studied. The variations of pulp characteristics such as brightness, Kappa number and
viscosity during the peroxide bleaching process were discussed and the concept of the A/B value was presented for the first
time. The results show that acid pretreatment with H2O2 is essential to improve pulp brightness and avoid viscosity loss. The conclusion is reached that the A/B value has great
influence on pulp properties when the total amount of peroxide used in the bleaching process is 2%–5%. Pulp with a high viscosity
and brightness can be obtained when A/B is about 0.15.
[Supported by the National “863” Project (Grant No. 2002AA241071)] 相似文献
3.
Takeshi Iimori Shoichi Miyawaki Makoto Machida Kunichika Murakami 《Journal of Wood Science》1998,44(6):451-456
Unbleached and oxygen-bleached hardwood kraft pulp (UKP and OKP), respectively, were bleached with a culture filtrate containing manganese peroxidase (MnP) and lignin peroxidase (LiP) fromPhanerochaete chrysosporium Burds. The brightness increases of UKP upon biobleaching with the culture filtrate with and without MnSO4 were the same. The brightness increase of OKP with MnSO4 decreased to about half that seen without MnSO4. Changes in the brightness of UKP and OKP by treatment with the culture filtrate were determined. The brightness increased sharply by about eight points during the first 3h. The 3-h treatment was repeated seven times. The brightness increased linearly with the bleaching of UKP. On bleaching of OKP, the brightness increased slowly and stopped at about 78%.Part of this report was presented at the 62nd Pulp and Paper Research Conference of the Japan Tappi, Tokyo, June 1995 相似文献
4.
Conditions for cell growth of suspension cultures of Cupressus lusitanica, which has high β-thujaplicin productivity, were studied. The medium that provided the highest growth rate was IS-1 medium (pH 5.5), modified
from Gamborg B5 medium containing 32 mM of total nitrogen. Its NO3-N/NH4-N ratio was 30 : 2. The maximum growth represented a 25-fold increase over the initial biomass on a fresh weight basis after
30 days of culture in this medium. The highest cell growth was obtained with an initial pH of 3.5–5.5, but the pH of the medium
settled to about pH 4.0 from any of the initial pH values in this report. The cells cultured under this condition were able
to produce a high level of β-thujaplicin.
Received: September 7, 2001 / Accepted: May 7, 2002
Present address: Teijin Ltd., Ehime 791-8530, Japan
Present address: Q'SAI Co. Ltd., Fukuoka 811-3422, Japan
Part of this report was presented at the 10th international symposium on wood and pulp chemistry, Yokohama, Japan, June 1999
Correspondence to:K. Fujita 相似文献
5.
Hot water extract (HWE) from Pinus radiata bark was fractionated into monomeric polyphenol (MPP), oligomeric proanthocyanidin (OPA), and polymeric proanthocyanidin
(PPA) fractions by monitoring the UV-visible spectrum of the eluted fractions. Nine polyphenols were identified in MPP: three
phenolic acids and six flavonoids. The major compounds of MPP were taxifolin (456 μg/mg), catechins (240 μg/mg), and protocatechuic
acid (46.2 μg/mg). The OPA components ranged from dimers to hexamers. PPA comprised procyanidin (PC, 94%), a small amount
of prodelphinidin (PD, 6%), and also the higher trans configuration, rather than the cis configuration, of C2-C3. The average molecular weight (Mw, Mn), polydispersity (Mw/Mn), and DP of PPA were 3,800 (Mw), 1,200
(Mn), 3.2 and 13, respectively. The potential antioxidant activities of HWE and the three fractions were estimated using proton-
or electron-donating assays containing 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate)
(ABTS) radical cation, superoxide anion (O2•−), hydrogen peroxide (H2O2), reducing power and lipid peroxidation. All the bark fractions exhibited potent quenching abilities against both commercially
available radicals (DPPH•, ABTS•+) and chemically induced radicals (H2O2, O2•−), as well as strong reducing power and inhibitory activity of lipid peroxidation. Particularly, OPA showed a hydrogen peroxide
scavenging activity significantly higher (p < 0.05) than that of the other fractions. From 2-thiobarbituric acid reactive substances and ferric thiocyanate assays, PPA
was suspected to act by essentially delaying the formation of hydroperoxide by quenching free oxygen radicals that operates
in oil-in-water emulsion. 相似文献
6.
The role of Tween 80 in biobleaching of unbleached hardwood kraft pulp (HWKP) with manganese peroxidase (MnP) was investigated. Among the surfactants (e.g., Tween 80, Tween 20, CHAPSO) the most significant brightness increase was obtained with Tween 80. Tween 80 and Tween 20 exhibited several effects, such as dispersion of degraded lignin and activation of MnP, that partly contributed to the brightening of HWKP during MnP treatment. However, these characteristics did not explain the most appreciable effect on the brightness increase by Tween 80. Lipid peroxidation of surfactants during MnP biobleaching was determined by measuring the peroxide value (POV). The order of the POV increase was consistent with that of the brightness increase of pulp during MnP treatment in the presence of various surfactants or linolenic acid. However, radicals and peroxides derived from lipid (linolenic acid) peroxidation by lipoxidase hardly brightened the HWKP by themselves. These results suggested that Tween 80 was peroxidized by Mn(III), and that Mn(III) and lipid peroxidation of Tween 80 synergistically brightened HWKP.This study was presented in part at the 43rd lignin symposium, Fuchu, Tokyo, Oct. 26–27, 1998 and the 49th annual meeting of the Japan Wood Research Society, Tokyo, April 2–4, 1999 相似文献
7.
Root biomass and root distribution were studied in Entisols derived from the thick deposition of volcanic pumice on Hokkaido
Island, Japan, to examine the effect of soil conditions on tree root development. The soil had a thin (<10 cm) A horizon and
thick coarse pumiceous gravel layers with low levels of available nutrients and water. Two stands were studied: a Picea glehnii–Abies sachalinensis stand (PA stand) and a Larix kaempferi–Betula platyphylla var. japonica stand (LB stand). The allometric relationships between diameter at breast height (DBH) and aboveground and belowground biomass
of these species were obtained to estimate stand biomass. The belowground biomass was small: 30.6 Mg ha−1 for the PA stand and 24.3 Mg ha−1 for the LB stand. The trunk/root ratios of study stands were 4.8 for the PA stand and 4.3 for the LB stand, which were higher
than those from previous studies in boreal and temperate forests. All species developed shallow root systems, and fine roots
were spread densely in the shallow A horizon, suggesting that physical obstruction by the pumiceous layers and their low levels
of available water and nutrients restricted downward root elongation. The high trunk/root ratios of the trees may also have
resulted from the limited available rooting space in the study sites. 相似文献
8.
Spatial distribution of sporocarps of Suillus pictus A.H. Smith and Thiers was studied in a plot of 6 × 12 m in size established in a stand of Pinus koraiensis Sieb. et Zucc. in Kyoto, Japan for 4 years, and the biomass of mycorrhizas was examined in the last year. S. pictus was dominant in both sporocarp and ectomycorrhizal community in the study plot. The number of S. pictus sporocarps ranged from 0.94 to 1.26 m−2 (surface area) in the study plot and did not vary very much during the study period. Sporocarps of S. pictus occurred in clumps and the distributions of clumps were generally random. As the spots of sporocarp occurrence changed gradually
from year to year, the distributions of sporocarps that occurred successively in 2-year periods overlapped, especially when
analyzed in 9-m2 unit size using the m
*
–m method. Mycorrhizas of S. pictus were distributed in more subplots than its sporocarps. Distribution of mycorrhizas and sporocarps of S. pictus generally overlapped well. The biomass of mycorrhizas and mycelia in the mycorrhizas of S. pictus was estimated at 15.5 g DW m−2 and 6.2 g DW m−2 (surface area) in this plot, respectively. The biomass of mycorrhizas and mycelia in the mycorrhizas supporting the production
of one sporocarp (average dry weight was 0.86 g) of S. pictus was evaluated as about 16.4 and 7.3 g DW, respectively, in this plot.
Received: December 20, 2001 / Accepted: August 12, 2002
Acknowledgments We thank Dr. T. Furuno, Mr. N. Kato, and Dr. I. Nakai for their help in preparing the study plot and collecting sporocarps,
and Prof. K. Yokoyama for the identification of sporocarps. Thanks are also due to Dr. E. Kuno for his suggestion about analysis.
Correspondence to:J. Kikuchi 相似文献
9.
Structural changes of residual lignin in unbleached softwood kraft pulp (SWKP) during manganese peroxidase (MnP) treatment were investigated to obtain some understanding of the biobleaching action of SWKP with MnP treatment. Alkaline-extracted lignin from darkened SWKP by MnP showed more intense color and contained moreo-quinone than that from control SWKP. However, no difference in the conjugated-carbonyl was observed between the lignins from MnP-treated and control SWKP. The nitrobenzene oxidation analysis revealed that oxidative condensation of non-condensed lignin in SWKP occurs during an early stage of MnP treatment. These observations were supported by the model experiment in which the lignin prepared from control SWKP was subjected to MnP treatments three times, and the changes of color and functional groups in the lignin were determined after each treatment. These results suggested that an increase ino-quinone and the condensation reaction of non-condensed lignin in SWKP are responsible for the characteristic darkening of SWKP during MnP treatment. It was also ascertained that darkened lignin was degraded and brightened by repeated MnP treatments. 相似文献
10.
Takuya Kajimoto Akira Osawa Yojiro Matsuura Anatoly P. Abaimov Olga A. Zyryanova Kazuma Kondo Naoko Tokuchi Muneto Hirobe 《Journal of Forest Research》2007,12(2):103-112
We present results of individual-based root system measurement and analysis applied for Larix gmelinii trees growing on the continuous permafrost region of central Siberia. The data of root excavation taken from the three stands
were used for the analyses; young (26 years old), mature (105 years old), and uneven-aged over-mature stand (220 years old).
In this article, we highlight two topics: (1) factors affecting spatio-temporal pattern of root system development, and (2)
interactions between aboveground (i.e., crown) and belowground (i.e., root) competition. For the first topic, the detailed
observation of lateral roots was applied to one sample tree of the overmature stand. The tree constructed a superficial (<30 cm
in depth) and rather asymmetric root system, and each lateral root expanded mainly into elevated mounds rather than depressed
troughs. This indicated that spatial development of an individual root system was largely affected by microtopography (i.e.,
earth hummocks). For these lateral roots, elongation growth curves were reconstructed using annual-ring data, and annual growth
rates and patterns were compared among them. The comparison suggested that temporal root system development is associated
with differences in carbon allocation among the lateral roots. For the second topic, we examined relationships between individual
crown projection area (CA) and horizontal rooting area (RA) for the sample trees of each stand. RA was almost equal to CA
in the young stand, while RA was much larger (three or four times) than CA in the mature and overmature stands. Two measures
of stand-level space occupation, crown area index (aboveground: CAI; sum of CAs per unit land area) and rooting area index
(belowground: RAI; sum of RAs), were estimated in each stand. The estimates of RAI (1.3–1.8 m2 m−2) exceeded unity in all stands. In contrast, CAI exceeded unity (1.3 m2 m−2) only in the young stand, and was much smaller (<0.3 m2 m−2) in the two older stands. These between-stand differences in RAI–CAI relationships suggest that intertree competition for
both aboveground and belowground spaces occurred in the young stand, but only belowground competition still occurred in the
two older stands. Based on this finding, we hypothesized that competition below the ground may become predominant as a stand
ages in L. gmelinii forests. Methodological limitations of our analysis are also discussed, especially for the analysis using the two indices
of space occupation (CAI, RAI). 相似文献
11.
We investigated the biomass, vertical distribution, and specific root length (SRL) of fine and small roots in a chronosequence
of Japanese cedar (Cryptomeria japonica D. Don) plantations in Nara Prefecture, central Japan. Roots were collected from soil blocks up to 50 cm in depth in five
plantations of differing age: 4, 15, 30, 41, and 88 years old. Fine-root biomass reached a maximum (639 g m−2) in the 15-year-old stand before canopy closure, decreased in the 30-year-old stand (422 g m−2), and thereafter was stable. Except in the 30-year-old stand, fine-root biomass increased in deeper soil layers as stand
age increased, and the depth at which the cumulative biomass of fine roots reached 90% exhibited a good allometric relationship
with mean stem diameter. Both root-length density (root length per unit soil volume) and SRL decreased with soil depth in
all stands, indicating that plants mainly acquire water and nutrients from shallow soils. The highest SRL was observed in
the 4-year-old stand, but the relationship between SRL and stand age was unclear in older stands. The SRL in surface soils
seemed to decrease with increases in root-length density, suggesting that branching of the fine-root system during development
is related to density-dependent processes rather than age. 相似文献
12.
The role of antioxidant system in freezing acclimation-induced freezing resistance of Populus suaveolens cuttings 总被引:1,自引:0,他引:1
We investigated the changes in the contents of H2O2, malonaldehyde (MDA) and endogenous antioxidants, the activities of protective enzymes and some critical enzymes involved in the ascorbate-glutathione (ASA-GSH) cycle as well as freezing resistance (expressed as LT50) and correlations mentioned above, in detail using Populus suaveolens cuttings. The purpose was to explore the physiological mechanism of the enhancement of freezing resistance induced by freezing acclimation at –20°C, and to elucidate the physiological mechanisms by which trees adapt to freezing. The results showed that freezing acclimation enhanced the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), monodehydroascorbate reductase (MDAR), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR). And it increased the contents of reduced ascorbate (ASA), reduced glutathione (GSH), dehydroascorbate (DHA) and oxidized glutathione (GSSG). However, H2O2 and MDA contents and LT50 of cuttings were decreased. LT50 in cuttings was found to be closely correlated to the levels of SOD, POD, CAT, APX, DHAR, MDAR, GR, H2O2, MDA, ASA, GSH, DHA and GSSG during freezing acclimation. This suggested that the enhancement of freezing resistance of cuttings induced by freezing acclimation may relate to the distinct increase for the levels of SOD, POD, CAT, APX, DHAR, MDAR, GR, ASA, GSH, DHA, and GSSG. In addition, the observed levels of APX, DHAR, MDAR, GR, ASA, DHA, GSH and GSSG were higher than those of SOD, POD and CAT during freezing acclimation. It indicated that a higher capacity of the ASA-GSH cycle is required for H2O2 detoxification, and growth and development of cuttings. Based on the obtained results, it can be concluded that the ASA-GSH cycle plays an important role in enhancement of freezing resistance of P. suaveolens cuttings during freezing acclimation. 相似文献
13.
A. Itoh T. Yamakura S. Tan J. J. Kendawang H. S. Lee 《Journal of Forest Research》2003,8(2):0117-0121
Cuttings from older trees of the Dipterocarpaceae generally lose their ability to root. However, branches in a canopy of
adult dipterocarps are a possible source of cuttings because they show juvenile characteristics in architecture due to “adaptive
reiteration”, suggesting physiological rejuvenation. Effects of resource plant size on the rooting of cuttings and the possibility
of using cuttings from reiterated branches of adult trees were studied for Dryobalanops lanceolata, an emergent dipterocarp species. A cutting experiment with non-mist propagators was conducted for cuttings collected from
resource plants of four different size classes: <2 m, 2–5 m, 8–15 m, and 70 m in height. The smallest size class included
two different age classes: <2 and >2 years old. Cuttings from the tallest resource plant were collected from reiterated branches.
Rooting percentage was negatively correlated with resource plant size: 77–78% for resource plants <2 m, 63% for 2–5 m, 36%
for 8–15 m, and 0% for 70 m. Rooting percentages of cuttings collected from different individuals were not different for the
2–5 m tall class, while they were significantly different for the 8–15 m tall class. Resource plant size was negatively correlated
with the number of roots for rooted cuttings. No significant relationship was observed between resource plant size and mean
length of each root, total root length or total root dry weight for rooted cuttings. The results suggest the possibility of
collecting cuttings from relatively large resource plants up to 15 m tall and >20 years old if we chose good individuals for
resource plants. The results, however, show the difficulty in using reiterated branches of adult trees as a source of cuttings
for D. lanceolata.
Received: October 15, 2001 / Accepted: November 11, 2002
Acknowledgments We express our sincere thanks to Dr. S. Tamura, Dr. K. Ogino, and Mr. A.A. Hamid for their kind support. The tree tower was
constructed in a cooperative project between Japan and Sarawak supported by the Ministry of Education, Culture, Sports, Science
and Technology, Japan (Grant NP0201). The cutting experiment was partly funded by the Nippon Life Insurance Foundation and
the Japan Society for the Promotion of Science (JSPS-RFTF96R16001).
Correspondence to:A. Itoh 相似文献
14.
The programmed cell death (PCD) characteristics of Ulmus pumila L. seeds were investigated. The seeds were treated at a high temperature of 37°C and 100% relative humidity for six days.
DAPI (4′6-diamidino-2-phenylindole) staining revealed that the aging treatment induced condensation and margination of chromatin,
as well as the formation of apoptotic bodies. DNA electrophoresis results of U. pumila seeds on an agarose gel showed a characteristic “ladder” pattern. Levels of electrolyte leakage of seed cells showed that
membranes retained their integral form during almost the entire aging time. There was an immediate increase in the production
rate of superoxide anion (O2
−) and in the amount of hydrogen peroxide (H2O2), which remained at a μmol level. All of these common characteristics indicate that seed aging can be classified as PCD.
__________
Translated from Journal of Beijing Forestry University, 2007, 29(3): 8–14 [译自: 北京林业大学学报] 相似文献
15.
Hermann Rodenkirchen Axel Göttlein Alessandra R. Kozovits Rainer Matyssek Thorsten E. E. Grams 《European Journal of Forest Research》2009,128(2):117-128
Saplings of Fagus sylvatica and Picea abies were grown under conditions of intra and interspecific competition in a 2-year phytotron study under combinations of ambient
and elevated ozone (+O3 which is 2 × O3, but <150 nl l−1) as well as carbon dioxide concentrations (+CO2 which is amb. CO2 + 300 μl CO2 l−1) in a full factorial design. Saplings were analysed for various mineral nutrients in different plant organs as well as biomass
production and crown development. The study was based on the assumption that nutritional parameters important for growth and
competitiveness are affected by stress defence under limiting nutrient supply. The hypotheses tested were (1) that nutrient
uptake-related parameters (a) as well as efficiencies in nutrient use for above-ground competition (b) of beech rather than
spruce are impaired by the exposure to elevated O3 concentrations, (2) that the efficiency in nutrient uptake of spruce is enhanced by elevated CO2 concentrations in mixed culture, and (3) that the ability to occupy above-ground space at low nutrient cost is co-determinant
for the competitive success in mixed culture. Clear nitrogen deficiencies were indicated for both species during the 2-year
phytotron study, although foliar nitrogen-biomass relationships were not so close for spruce than for beech. O3 stress did not impair nutrient uptake-related parameters of beech; thus hypothesis (1a). was not supported. A negative effect
of elevated O3 (under amb. CO2) on the N and P based efficiencies in above-ground space occupation (i.e. lower crown volume per unit of N or P invested
in stems, limbs and foliage) of beech supported hypothesis (1b). It appeared that ozone stress triggered a nutrient demand
for stress defence and tolerance at the expense of above-ground competition (trade-off). Crown volume of beech under O3 stress was stabilized in monoculture by increased nutrient uptake. In general, the +CO2-treatment was able to counteract the impacts of 2 × O3. Elevated CO2 caused lower N and S concentrations in current-year foliage of both tree species, slightly higher macronutrient amounts in
the root biomass of spruce, but did not increase the efficiencies in nutrient uptake of spruce in mixed culture. Therefore
hypothesis (2) was not supported. At the end of the experiment spruce turned out to be the stronger competitor in mixed culture
as displayed by its higher total shoot biomass and crown volume. The amounts of macronutrients in the above-ground biomass
of spruce individuals in mixed culture distinctly exceeded those of beech, which had been strongly reduced by interspecific
competition. The superior competitiveness of spruce was related to higher N and P-based efficiencies in above-ground space
occupation as suggested in hypothesis (3).
This article belongs to the special issue “Growth and defence of Norway spruce and European beech in pure and mixed stands”. 相似文献
16.
Sheng-Yang?Wang Jyh-Horng?Wu Sen-Sung?Cheng Chiu-Ping?Lo Hsing-Ning?Chang Lie-Fen?Shyur Shang-Tzen?Chang
Calocedrus formosana Florin (Cupressaceae) is an endemic tree to Taiwan. To evaluate the antioxidant activity of the plant extracts from heartwood, bark, and leaf of C. formosana, assays for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and superoxide anion scavenging activities, as well as prevention of DNA strand cleavage were performed in this study. Similar IC50 values against the DPPH radical were found for the heartwood and bark extracts at approximately 23µg/ml. Moreover, the heartwood extract exhibited the highest inhibitory activity against superoxide radicals among the test samples; a 2.3-fold lower value of IC50 for superoxide radical inhibition was found in the heartwood extract relative to that of (+)-catechin. Much less effect on inhibition of DPPH and superoxide radicals was found from the leaf extract of C. formosana. More than 70% of superoxide radicals were inhibited in the presence of 10µg/ml heartwood extract, whereas only 15% inhibition was obtained from the leaf extract. The heartwood extract, at a dose of approximately 0.5mg/ml, apparently completely prevented the X174 supercoiled DNA cleavage induced by ultraviolet photolysis of H2O2, as judged by agarose gel electrophoresis. This report also suggests that the antioxidant activities of the plant extracts of C. formosana are in good correlation with their phenolic contents. 相似文献
17.
Tomoyuki Nakatsubo Yu Kitamura Norikazu Sakakibara Masaharu Mizutani Takefumi Hattori Nozomu Sakurai Daisuke Shibata Shiro Suzuki Toshiaki Umezawa 《Journal of Wood Science》2008,54(4):312-317
The function of an Arabidopsis thaliana gene, At5g54160 annotated as a caffeic acid O-methyltransferase CAOMT gene was characterized. The recombinant enzyme of this gene (AtOMT1) catalyzed the O-methylation of phenylpropanoid and flavonoid substrates. The specificity constants (k
cat/K
m) for 5-hydroxyconiferaldehyde (5-HCAld) and quercetin were both 0.11 μM−1·min−1. On the other hand, lignins of At5g54160-knockout Arabidopsis mutants lacked syringyl units. In addition, we showed that the gene silencing also resulted in significant accumulation of
caffeyl alcohol (CaAlc). These results strongly suggested that At5g54160 gene is involved in syringyl lignin synthesis for
the methylation of both 5-hydroxyconiferaldehyde and 3,4-dihydroxyphenyl compound(s).
Part of this work was presented at the Annual Meeting of Japan Society for Bioscience, Biotechnology, and Agrochemistry, March
24–27, 2007 相似文献
18.
Jonas Hafrén 《Journal of Wood Science》2005,51(6):655-658
Antibodies recognizing galacturonan were used in immunoassays for industrial unbleached and hydrogen peroxide-bleached chemithermomechanical
pulp (CTMP). The assays were based on a colorimetric method using specific monoclonal antibody recognition of acidic and methylated
homogalacturonan, respectively, on the pulp fiber surfaces. Alkaline phosphatase-conjugated antibodies were linked to the
galacturonan specific antibodies, and an alkaline phosphatase substrate (p-nitrophenylphosphate) was used to develop a yellow reaction product that can be followed spectrophotometrically. Together
the newly developed immunoassays were able to describe the deesterification, specifically, of surface-localized galacturonan
on CTMP, induced by alkaline hydrogen peroxide bleaching. Unbleached CTMP showed relatively more labeling by methylated galacturonan
recognizing antibodies, whereas bleached CTMP was relatively more labeled for acidic galacturonan. The increase in negative
charge of the bleached pulp was also shown by polyelectrolyte titration; the negative surface charge was 9.3 μeq g−1 in unbleached CTMP and 21.7 μeq g−1 in bleached pulp. 相似文献
19.
The changes of hydrogen peroxide (H2O2) metabolism and antioxidant enzyme activities in a hybrid poplar (Populus simonii × P. pyramidalis ‘Opera 8277’) in response to mechanical damage (MD) and herbivore wounding (HW) were investigated to determine whether H2O2 could function as the secondary messenger in the signaling of systemic resistance. Results show that H2O2 was generated in wounded leaves through MD and HW treatments and systemically in unwounded leaves around the wounded leaves.
The activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were
also enhanced. However, the H2O2 accumulation and antioxidant enzyme activities were inhibited in MD leaves through the pretreatment with DPI (which is a
specific inhibitor of NADPH oxidase). The results of this study suggest that H2O2 could be systemically induced by MD and HW treatments, and H2O2 metabolism was closely related to the change in SOD, APX and CAT activities. A high level of antioxidant enzymes could decrease
membrane lipid peroxidation levels and effectively induce plant defense responses.
Foundation project: This research is supported by the Key Science Program of the Sate Forestry Administration of China (2006–59),
and the National Key Project of Scientific and Technical Supporting Programs Funded by Ministry of Science & Technology of
China (2006BAD01A15; 2006BAD24B04).
Biography: AN Yu (1982–), female, Postgraduate in College of Biological Sciences and Biotechnology, Beijing Forestry University,
Beijing 100083, P. R. China. 相似文献
20.
To guide the development of thermal decomposition methods for disposal of CCA treated wood, reactions during the thermal
decomposition of CCA treated wood were modeled using thermogravimetric analysis (TGA), with special focus placed on arsenic
volatilization. Simple inorganic compounds, such as As2O5, CuO, and Cr2O3, were used to model the thermal behavior of the inorganics in CCA treated wood. In air and nitrogen, arsenic (V) oxide began
to volatilize at 600 °C during temperature ramps at 5 °C/min. During a 5 °C/min ramp in a hydrogen mix, arsenic (V) oxide
began decomposition at 425 °C. Arsenic volatile loss from CCA treated wood can depend strongly on the gases produced by wood
thermal decomposition. In the presence of As2O5, chromium (III) oxide and copper (II) oxide formed arsenates in air and nitrogen. Chromium arsenates began decomposition
as low as 790 °C. This suggested that chromium arsenates in CCA treated wood formed during original preservative fixation
may decompose as low as 790 °C. Copper arsenates were stable up to 900 °C in air, but showed only a limited range of stability
in nitrogen. Depending on process conditions, the formation of copper arsenates may limit arsenic loss during thermal decomposition
of CCA treated wood up to 900 °C. The thermal decomposition of inorganic oxides was influenced by interactions with wood and
wood decomposition products. In a dry YP sawdust/As2O5 mix, arsenic (V) oxide volatilized at 370 °C during inert pyrolysis at 5 °C/min and at 320 °C during smoldering combustion
at 5 °C/min. Thermal dwells of a dry YP/As2O5 mix showed no arsenic loss at 250 °C, but significant loss occurred during higher temperature dwells. During inert pyrolysis
at 5 °C/min, the formation of complexes and hydrates were shown to prevent arsenic loss up to 400 °C.
Received 14 July 1999 相似文献