April 2005, Volume 47 Issue 4, Pages 385-507.


Cover Caption:
Microtubules assembled by lily pollen tubulin on the surface of isolated nucleus of tobacco suspension BY-2 cells. Microtubules were visualized by monoclonal anti-a-tubulin Cy3-conjugated mouse antibody in the top left image and fluorescent microtubules assembled by NHS-rhodamine conjugated tubulin in the bottom right image. (See the text by Chun-Hua XU et al. on pages 457-466).

 

          Research Articles
Volatile Organic Compounds and Their Roles in Bacteriostasis in Five Conifer Species
Author: Yan GAO, You-Ju JIN, Hai-Dong LI£¬Hua-Jun CHEN
Journal of Integrative Plant Biology 2005 47(4)
DOI: 10.1111/j.1744-7909.2005.00081.x
      
    In order to make clear the functions of plant volatile organic compounds (VOCs) on bacteriostasis and air decontamination, we analyzed the composition and content of VOCs in Pinus tabulaeformis Carr., P. bungeana Zucc., Sabina chinensis Antoine, Picea koraiensis Nakai, and Cedrus deodara G. Don under near-natural conditions using the thermal-desorption cold trap gas chromatography/mass spectrometer technique. The effects of the VOCs on airborne microorganisms were investigated using the method of natural sedimentation. Results showed that the major VOCs were as follows: limonene, b-pinene, a-pinene, and a-caryophyllene in Pinus tabulaeformis and P. bungeana; limonene, borneol acetate, b-pinene, myrcene, and tricylene in S. chinensis; limonene, a-pinene, myrcene, camphene, and b-pinene in Picea koraiensis; and limonene, 2, (10)-pinene, a-pinene, and myrcene in C. deodara. These VOCs and the corresponding foliar extracts inhibited the growth of bacteria and stimulated the growth of fungi. Experimental data using monomers of the VOCs demonstrated that limonene, b-pinene, and three aldehydes could significantly inhibit bacterial growth, suggesting an inhibitory effect of VOCs on the growth of airborne microorganisms in the five conifer species. The bacteriostasis and air-decontaminating effects of plant VOCs are further discussed in terms of their chemical composition.
Abstract (Browse 3651)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Chemical Constituents from the Seeds of Ziziphus jujuba var. spinosa (Bunge) Hu
Author: Li-Mei LI, Xun LIAO, Shu-Lin PENG£¬Li-Sheng DING
Journal of Integrative Plant Biology 2005 47(4)
DOI: 10.1111/j.1744-7909.2005.00060.x
      
    To search for new and bioactive minor components from traditional Chinese medicines, a new compound, named jujuphenoside (1), was isolated from the seeds of Ziziphus jujuba var. spinosa (Bunge) Hu. The structure of jujuphenoside was elucidated by spectral and chemical methods, particularly two-dimensional nuclear magnetic resonance analysis. Together with the new compound, 22 known compounds were also isolated and identified from the seeds of Z. jujuba var. spinosa, among which, epiceanothic acid (2) was first obtained from natural resources, whereas compounds 7¨C16 were first obtained from this plant.
Abstract (Browse 3861)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Vitamins A, C, and E and b-Carotene Content in Seeds of Seven Species of Vicia L.
Author: Ahmet SAHIN, Yasar KIRAN, Fikret KARATAS£¬Senem SONMEZ
Journal of Integrative Plant Biology 2005 47(4)
DOI: 10.1111/j.1744-7909.2005.00083.x
      
    To determine the vitamins A, C, and E and b-carotene content of Vicia species that can be used in animal feed, a high performance liquid chromatography (HPLC) method was used to investigate the vitamin and b-carotene content in mature and immature seeds of seven Vicia species (Vicia anatolica Turrill., V. ervilia (L.) Willd., V. michauxii Sprengel, V. mollis Boiss. et Hausskn. ex Boiss., V. noeana Reuter ex Boiss., V. peregrina L., and V. sericocarpa Fenzl.), which are useful plants in animal feed in the eastern Anatolia region in Turkey. The vitamin content was found to differ between mature and immature seeds. The levels of vitamins A, C, and E and b-carotene were higher in mature seeds than in immature seeds (P < 0.01).
Abstract (Browse 3007)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Isolation and Expression Pattern Analysis of Two Ferritin Genes in Tobacco
Author: Ting-Bo JIANG
Journal of Integrative Plant Biology 2005 47(4)
DOI: 10.1111/j.1744-7909.2005.00044.x
      
    For understanding of the ferritin gene expression pattern and the mechanism of iron homeostasis in tobacco (Nicotiana tabaccum L.) plants, two full-length ferritin cDNAs, NtFer1 and NtFer2, were isolated from tobacco seedlings and characterized. These cDNAs are 1 214 and 1 125 bp nucleotides and encode 251 and 259 amino acid residues, respectively. The deduced amino acid sequences showed that two tobacco ferritins share the same characteristics as the plant ferritins from Arabidopsis, soybean, and maize. Southern blotting analysis indicated that both NtFer1 and NtFer2 were probably multicopy genes in the tobacco genome. Northern blotting analysis indicated that iron loading of tobacco plantlets increased the ferritin mRNA abundance and that NtFer1 expression was higher and more sensitive to iron than NtFer2 expression. Furthermore, NtFer1 was expressed in both leaves and roots, whereas NtFer2 was expressed mainly in leaves.
Abstract (Browse 3053)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
OsDREB4 Genes in Rice Encode AP2-Containing Proteins that Bind Specifically to the Dehydration-Responsive Element
Author: Xiu-Hong TIAN, Xue-Ping LI, Hua-Lin ZHOU, Jin-Song ZHANG, Zhi-Zhong GONG£¬Shou-Yi CHEN
Journal of Integrative Plant Biology 2005 47(4)
DOI: 10.1111/j.1744-7909.2005.00028.x
      
    Most dehydration-responsive element-binding (DREB) factors interact specifically with the dehydration-responsive element (DRE) and control the expression of many stress-inducible genes in Arabidopsis. In rice (Oryza sativa L. cv. Lansheng), we cloned three DREB homologs: OsDREB1-1, OsDREB4-1, and OsDREB4-2. The deduced amino acid sequences revealed that each protein contained a potential nuclear localization signal, an AP2 DNA-binding domain, and a possible acidic activation domain. The yeast one-hybrid assay indicated that both OsDREB4-1 and OsDREB4-2 proteins specifically bound to DRE and activated expression of the dual reporter genes of histidine (HIS3) and galactosidase (LacZ). In rice seedlings, expression of OsDREB4-1 was induced by dehydration and high salt, whereas OsDREB1-1 and OsDREB4-2 were expressed constitutively. Under normal growth conditions, OsDREB1-1 was expressed strongly in the leaf, sheath, and spike, was expressed relatively weak in the stem and only faintly expressed in the roots, whereas expression of transcripts of OsDREB4-1 and OsDREB4-2 was higher in the roots, stem, and spike, lower in the leaf, and undetectable in the sheath. Together, these results imply that expression of the OsDREB genes could be controlled by specific aspects of differentiation or development. Thus, OsDREB4-1 could function as a trans-acting factor in the DRE/DREB regulated stress-responsive pathway.
Abstract (Browse 3658)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Dimethyl Sulfoxide Is Feasible for Plant Tubulin Assembly In vitro: A Comprehensive Analysis  
Author: Chun-Hua XU, Shan-Jin HUANG£¬Ming YUAN
Journal of Integrative Plant Biology 2005 47(4): 457-466
DOI: 10.1111/j.1744-7909.2005.00086.x
      
    It is much more difficult for tubulin from plant sources to polymerize in vitro than tubulin from animal sources. Taxol, a most widely used reagent in microtubule studies, enhances plant microtubule assembly, but hinders microtubule dynamics. Dimethyl sulfoxide (DMSO), a widely used reagent in animal microtubule studies, is a good candidate for the investigation of plant microtubule assembly in vitro. However, proper investigation is lacking about the effects of DMSO on plant microtubule assembly in vitro. In the present study, DMSO was used to establish optimal conditions for the polymerization of plant tubulin. Tubulin, purified from lily pollen, polymerizes into microtubules at a critical concentration of 1.2 mg/mL in the presence of 10% DMSO. The polymers appear to have a normal microtubule structure, as revealed by electron microscopy. In the presence of 10% DMSO, microtubule polymerization decreases when the pH of the medium is increased from 6.5 to 7.4. Both the polymerization rate and the mass of the polymers increase as temperature increases from 25 to 40 ¡ãC. Tubulin polymerizes and depolymerizes along with cycling of temperature, from 37 to 4 ¡ãC, or following the addition to or the removal of Ca2+ from the medium. When incubated with nuclei isolated from tobacco BY-2 suspension cells, tubulin assembles onto the nuclear surface in the presence of 10% DMSO. Labeling lily pollen tubulin with 5- (and 6-) carboxytetramethyl-rhodamine succinimidyl ester (NHS-rhodamine) was performed successfully in the presence of 10% DMSO. Labeled tubulin assembles into a radial structure on the surface of BY-2 nuclei. The polymerization of lily pollen tubulin is also enhanced by microtubule-associated proteins from animal sources in the presence of 10% DMSO. All the experimental results indicate that plant tubulin functions normally in the presence of DMSO. Therefore, DMSO is an appropriate reagent for plant tubulin polymerization and investigation of plant microtubules in vitro.
Abstract (Browse 3956)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Starch Mobilization in Ultradried Seed of Maize (Zea mays L.) During Germination
Author: Xiao-Feng WANG, Xin-Ming JING£¬Jian LIN
Journal of Integrative Plant Biology 2005 47(4)
DOI: 10.1111/j.1744-7909.2005.00088.x
      
    The effects of ultradry storage on the starch mobilization in maize (Zea mays L.) seed after aging were investigated. The results indicated that there were no significant differences in the content of ATP, starch, and soluble sugar, as well as the activity of amylase, between ultradried seeds and seeds stored at ¨C20 ¡ãC during germination. These results were consistent with the higher level of vigor of the ultradried seed. Sieve tube introduction of a fluorescence dye (carboxyl fluoresceindiacetate) and laser confocal microscopy were used to study the development of plasmodesmata in the ultradried seeds. The results indicated that plasmodesmata developed well in ultradried seeds. Fluorescence analysis also showed that the fluorescence intensity in the radicle of ultradried seeds was stronger than that in seeds with a higher moisture content. This suggests that ultradry treatment has no adverse effects on the seeds. After seed imbibition, cell orgaelles could be resumed. It is concluded that ultradry seed storage is beneficial for maintaining seed vigor and that starchy mobilization proceeds regularly during germination.
Abstract (Browse 3452)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Effects of Interaction Between Cadmium and Plumbum on Phytochelatins and Glutathione Production in Wheat (Triticum aestivum L.)
Author: Qin SUN, Xiao-Rong WANG, Shi-Ming DING£¬Xin-Fang YUAN
Journal of Integrative Plant Biology 2005 47(4)
DOI: 10.1111/j.1744-7909.2005.00073.x
      
    Phytochelatins (PCs) may function as a potential biomarker for metal toxicity. However, less attention has been paid to the effects of metal interactions on the production of PCs and glutathione (GSH), the most prominent cellular thiol. In the present study, the effects of interactions between cadmium (Cd) and plumbum (Pb) on the production of PCs and GSH were monitored over a period of 14 d in wheat (Triticum aestivum L.) tissues. The results showed that combination of Cd and Pb led to synergistic growth inhibition in wheat. Exposure to Cd or Pb increased levels of PCs in a concentration-, tissue-, and time-dependent manner. Cadmium was more effective that Pb in increasing PCs production. Compared with the effects of Cd or Pb alone on the production of PCs, the combination of Cd and Pb acted synergistically, resulting in an enhanced production of PCs. Cadmium also stimulated GSH production in a concentration-, tissue-, and time-dependent manner. However, Pb had no obvious effects on GSH levels. The combination of Pb and Cd antagonized GSH production over the course of the growth period. The results of the present study suggest that metal interactions should be considered in the application of PCs and GSH as potential biomarkers for the evaluation of metal toxicity.
Abstract (Browse 3167)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Effects of Exogenous Spermidine on Antioxidant System Responses of Typha latifolia L. Under Cd2+ Stress
Author: Chun-Fang TANG, Yun-Guo LIU, Guang-Ming ZENG, Xin LI, Wei-Hua XU, Cheng-Feng LI£¬ Xing-Zhong YUAN
Journal of Integrative Plant Biology 2005 47(4)
DOI: 10.1111/j.1744-7909.2005.00074.x
      
    The effects of foliar spraying with spermidine (Spd), ranging in concentration from 0.25 to 0.50 mmol/L, on the antioxidant system under Cd2+ stress (range 0.1¨C 0.2 mmol/L Cd2+) in Typha latifolia L. grown hydroponically were investigated in order to offer a referenced evidence for an understanding of the mechanism by which polyamines (PAs) relieve the damage to plants by heavy metal and improve the phytoremediation efficiency of heavy metal-contaminated water. The results showed that Cd2+ stress induced oxidative injury, as evidenced by an increase in the generation of superoxide anion (O2-. ), as well as the hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents in both leaves and caudices. With the exception of superoxide dismutase (SOD) activity in the leaves, an increase in the activities of catalase (CAT), guaiacol peroxidase (GPX), and glutathione reductase (GR) was observed in both leaves and caudices, SOD activity was increased in caudices, and ascorbate peroxidase (APX) activity was increased in leaves following Cd2+ treatment. The reduced glutathione (GSH) content in both leaves and caudices and the reductive ascorbate content in leaves was obviously increased, which were prompted by the application of exogenous Spd. Spraying with Spd increased the activity of GR and APX in both leaves and caudices, whereas the activity of SOD, CAT, and GPX was increased only in caudices following spraying with Spd. The generation of O2-. and the H2O2 and MDA content in both leaves and caudices decreased after spraying with Spd. The decrease in MDA was more obvious following the application of 0.25 than 0.50 mmol/L Spd. It is supposed that exogenous Spd elevated the tolerance of T. latifolia under Cd2+ stress primarily by increasing GR activity and the GSH level.
Abstract (Browse 3976)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Effects of Phosphorus Nutrient on the Hydraulic Conductivity of Sorghum (Sorghum vulgare Pers.) Seedling Roots Under Water Deficiency
Author: Zhou-Ping SHANGGUAN, Ting-Wu LEI, Ming-An SHAO and Qing-Wu XUE
Journal of Integrative Plant Biology 2005 47(4)
DOI: 10.1111/j.1744-7909.2005.00069.x
      
    Retraction Zhou-Ping Shangguan, Ting-Wu Lei, Ming-An Shao and Qing-Wu Xue (2005). Effects of phosphorus Nutrient on the Hydraulic Conductivity of Sorghum (Sorghum vulgare Pers.) Seedling Roots Under Water Deficiency. J Integr Plant Biol 47, 421-427. The first and the corresponding author, Zhou-Ping Shangguan, of the above article has requested that its publication to be retracted from Journal of Integrative Plant Biology (JIPB), with the following statement: With the fact that the data published in the above-mentioned article contained plagiarized materials from the article of ¡°Yufang Shen, Baoli Wang, Dong Qu, Rongfu Chen. Effects of phosphorus on root hydraulic conductance of corn under water stress. Journal of Northwest Sci-Tech University of Agriculture and Forestry (JNSTUAF, Natural Science Edition). 2002, 30(5): 1115¡±, I have to retract the paper from JIPB. In addition, I admit that the manuscript was prepared and published without the consensus of the other three authors listed, therefore, I myself is solely responsible for the plagiarism and falsification. I deeply apologize for the damages toJIPB and the authors of the JNSTUAF paper, and for misleading the readers by the publication and citation of the data. Zhou-Ping Shangguan Institute of Soil and Water Conservation, the Chinese Academy of Sciences Yangling, Shannxi, 712100, China Tel: 86-29-87019107 Fax: 86-29-87012210 E-mail: shangguan@ms.iswc.ac.cn 16 July, 2006 Editorial It brought to our attention that the above-mentioned paper co-authored by ZP Shangguan et al. (2004) has involved in serious scientific misconducts. We communicated for several times with the first and the corresponding author (ZP Shangguan), to allow him to clarify the case by himself. We have carefully investigated the case, with the help from the authors¡¯s home institution, Institute of Soil and Water Conservation (ISWC), the Chinese Academy of Sciences. On December 5th, 2006, we received a formal statement from ISWC, which described the result of official investigation and conclusion about the case. Based on these documents, we would like to make the following statement: 1) it is apparent that the above-mentioned paper contains a whole set of plagiarized and falsified data from the paper published by Y. Shen, B. Wang, D. Qu, R. Chen (2002) ¡°Effects of phosphorus on root hydraulic conductance of corn under water stress¡±, Journal of Northwest Sci-Tech University of Agriculture and Forestry (Natural Science Edition), 30(5): 11-15. 2) The first author is fully responsible for the misconduct, although he has stated that an un-authored visiting student has been involved in putting these data together. 3) We acknowledge that a formal request was made by ZP Shangguan on10 April, 2006, to the editorial office to retract the paper, but the journal has not been able to publish the retraction letter earlier since the investigation was not formally completed. 4) ZP Shangguan has been discharged from the administrative duties of the ISWC. We think this is a lesson to all of us, and we all should know that scientific integrity requires original research from each of us. Journal of Integrative Plant Biology 11 December, 2006
Abstract (Browse 3629)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Soil Organic Matter Dynamics Along a Vertical Vegetation Gradient in the Gongga Mountain on the Tibetan Plateau
Author: Lin WANG, Hua OUYANG, Cai-Ping ZHOU, Feng ZHANG, Ming-Hua SONG£¬Yu-Qiang TIAN
Journal of Integrative Plant Biology 2005 47(4)
DOI: 10.1111/j.1744-7909.2005.00085.x
      
    Our knowledge about soil organic matter (SOM) dynamics is limited although this is an important issue in the study of responses of ecosystems to global climate changes. Twelve sampling plots were set up every 200 m from 1 700 to 3 900 m along the vertical vegetation gradient along the east slope of Gongga Mountain. Samples were taken from all 12 plots for SOM content measurement, although only 5 of the 12 plots were subjected to radiocarbon measurements. A radiocarbon isotope method and a time-dependent model were used to quantify the SOM dynamics and SOM turnover rates along the vertical vegetation gradient. The results showed that the SOM turnover rate decreased and turnover time increased with soil depth for all vegetation types. The litter layer turnover rates presented a clear trend along the gradient. The litter layer turnover rates decreased with an increase in elevation, except that the litter layer turnover rate of mixed forest was higher than that of evergreen forest. Climatic factors, such as temperature and precipitation, were the main factors influencing the surface soil carbon dynamics. The turnover rates of the subsoil (including the A, B, and C horizons in the soil profiles) along the vertical gradient had no clear trends. The SOM of subalpine shrub and meadow turned over more slowly than that of the forest types in almost all soil horizons. The characteristic of short roots distributing in the upper part of the soil profile leads to different SOM dynamics of shrub and meadow compared with the forest types. Coniferous and mixed forests were susceptible to carbon loss from the young carbon pool, but their long and big roots resulted in high D14C values of the deep soil profiles and increased the input of young carbon to the deep soil. In evergreen forest, the carbon cumulative ability from the B horizon to the C horizon was weak. The different vegetation types, together with their different modes of nutrient and carbon intake, may be the mechanism conditioning the subsoil organic matter dynamics.
Abstract (Browse 3078)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Isolation and Characterization of a Novel Chitosan-Binding Protein from Non-Heading Chinese Cabbage Leaves
Author: Hui-Ping CHEN£¬Lang-Lai XU
Journal of Integrative Plant Biology 2005 47(4)
DOI: 10.1111/j.1744-7909.2005.00022.x
      
    To know the mechanism of ammonia assimilation in non-heading Chinese cabbage (Brassica campestris L. ssp. chinensis (L.) Makino) leaves regulated by chitosan (CTS), a CTS-binding protein was isolated from non-heading Chinese cabbage leaves using the chitosan affinity chromatography approach and this CTS-binding protein was partially characterized. The profile of the 53.1 kDa purified protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis was compared with the native molecular weight of 106.5 kDa, which indicated that the purified protein was a dimer with identical subunits. After isoelectric focusing, a band was obtained at pH 8.25. The agglutination test and periodic acid-Schiff staining further revealed that the protein was a glycoprotein with lectin activity. Moreover, the purified protein contained 17.4% (w/w) neutral carbohydrate and 82.56% (w/w) protein. The comparison of this protein and the 67 kDa CTS-binding protein isolated previously from Rubus culture tissue exhibited some differences in characterization. According to results of peptide mass fingerprinting analysis, the protein purified in the present study does not show any similarity with any protein in the protein data bank. Thus, it was deduced that the protein purified in the present study is a novel CTS-binding protein.
Abstract (Browse 3124)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Analysis of the Genetic Structure of Sclerotinia sclerotiorum (Lib.) de Bary Populations from Different Regions and Host Plants by Random Amplified Polymorphic DNA Markers
Author: Jun-Ming SUN, Witold IRZYKOWSKI, Malgorzata JEDRYCZKA£¬Fen-Xia HAN
Journal of Integrative Plant Biology 2005 47(4)
DOI: 10.1111/j.1744-7909.2005.00077.x
      
    The genetic diversity and genetic structure of a population of isolates of Sclerotinia sclerotiorum (Lib.) de Bary from different regions and host plants were investigated using the random amplified polymorphic DNA (RAPD) method with 20 random decamer primer pairs in order to provide some information on the phylogenetic taxa and breeding for resistance to sclerotinia stem rot. A minimum of three and a maximum of 15 unambiguously amplified bands were generated, furnishing a total of 170 bands ranging in size from 100 to 3 200 bp, corresponding to an average of 8.5 bands per primer pair. One hundred and four of these 170 bands (61.2%) were polymorphic, the percentage of polymorphic bands for each primer pair ranging from 0.0% to 86.7%. The genetic relationships among the isolates, based on the results of RAPD analysis, were examined. The genetic similarity of all selected isolates was quite high. At the species level, the genetic diversity estimated by Nei¡¯s gene diversity (h) was 0.197 and Shannon¡¯s index of diversity (I) was 0.300. The unweighted pair-group mean analysis (UPGMA) cluster analysis showed that most isolates from the same regions were grouped in the same cluster or a close cluster. The population of isolates from Hefei (Anhui Province, China) was more uniform and relatively distant to other populations. The Canadian population collected from carrot (Daucus carota var. sativa DC.) was relatively close to the Polish population collected from oilseed rape (Brassica napus L.) plants. There was no relationship between isolates from the same host plants. An analysis of molecular variance (AMOVA) revealed that the percentage of variance attributable to variation among and within populations was 50.62% and 49.38%, respectively. When accessions from China, Europe, and Canada were treated as three separate groups, the variance components among groups, among populations within groups, and within populations were ¨C0.96%, 51.48%, and 49.47%, respectively. The genetic differentiations among and within populations were highly significant (P < 0.001). Similarly, the coefficient of gene differentiation (Gst) in total populations calculated by population genetic analysis was 0.229 4, which indicated that the genetic variation among populations was 22.94%. The gene flow (Nm) was 1.68, which indicated that the gene permutation and interaction among populations was relatively high.
Abstract (Browse 3362)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Causes and Consequences of Changes in Nutrient Structure in the Jiaozhou Bay  
Author: Shu-Jiang ZHAO, Nian-Zhi JIAO, Zhi-Liang SHEN£¬Yu-Lin WU
Journal of Integrative Plant Biology 2005 47(4): 396-410
DOI: 10.1111/j.1744-7909.2005.00005.x
      
    Concentrations and ratios of nutrients in Jiaozhou Bay, China, have changed much in the past decades, with trends indicating an increase in nitrogen and a decrease in silicate. Statistical analysis has shown that the long-term variations of nutrients are associated with agricultural activities, precipitation, and anthropogenic factors. Stoichiometric calculations indicate that the nutrient structure has become more and more unbalanced. There has been almost no possibility for nitrogen limitation since the 1980s, the probability of P limitation has increased, and the probability of Si limitation has also increased markedly from the 1980s to the 1990s. As a consequence of changes in nutrient structure, a decrease in the abundance of net phytoplankton was evident, whereas total chlorophyll a levels have remained roughly unchanged at around 3.55 mg/L. Thus, it is likely that smaller species have taken the niche vacated by the larger species. Changes in phytoplankton size and species composition may ultimately lead to various functional and structural changes at the system level.
Abstract (Browse 3367)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
 

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