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1.
Fast-growing macroalgae, including Ulva lactuca Linnaeus, respond rapidly to changes in nutrient conditions, particularly to short-term N supply. This ability to rapidly
take up and assimilate N contributes to the increasing occurrence of macroalgal blooms in heavily N loaded coastal ecosystems.
To determine whether long-term nutrient histories affect short-term responses in activity of N-assimilating enzymes, including
nitrate reductase (NRA) and glutamine synthetase activity (GSA), internal N storage, and macroalgal growth, we conducted an
in situ nitrate fertilization experiment between 7 and 22 July 2004, with fronds of U. lactuca collected from estuaries with high and low N loads in Waquoit Bay, Cape Cod, Massachusetts, USA (N 41° and W 70°). Initial
NRA, GSA, % N, δ15N, and growth of U. lactuca fronds were higher in the site where nitrate was in high supply. Differences in NRA persisted even after short-term experimental
enrichment. Differences in internal N pools, δ15N, and growth, in contrast, mirrored the changes of nutrient supply. The rate of turnover of the internal N content of U. lactuca was quite short (<2 d), and turnover of enzyme activity may have been even shorter. N isotopic fractionation by U. lactuca appeared to be of small magnitude, unlike the case of phytoplankton, and similar to that of vascular plants. δ15N was a better indicator of short-term response to external and internal nutrient supplies in U. lactuca than enzyme activity or N content, and may reliably detect rapid changes in N availability, source, and uptake and assimilation
processes. 相似文献
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The starch content and its composition have important consequences for the yield of the harvested crop and the materials extracted from it. The functional properties of the foods or other processed materials derived from these crops are also affected by the structure and composition of the starch. Recently, genetic engineering has been used to produce plants with an elevated starch content, achieved by transforming the plant with a mutated bacterial gene coding for an ADPglucose pyrophosphorylase that is active in the presence of metabolites which inhibit the plant enzyme. Besides the practical implications of these results, this experiment provided direct evidence for the regulatory role of the ADPglucose pyrophosphorylase in starch synthesis. Other bacterial enzymes, such as glycogen synthase and branching enzyme, could be introduced in order to modify starch structure. However, a more elegant (but longer-term) approach would be to learn enough about the structure-function relationships of the plant enzymes so that the product of their action could be changed. To achieve this objective, much more will have to be learned about the enzymes involved in the biosynthesis of starch than is presently known. Here, the basic properties of starch and the current research approaches to understanding its biosynthesis are described, together with a perspective of how genetic manipulation of starch structure may be achieved.Paper presented at the Bio/Environmentally Degradable Polymer Society—Third National Meeting, June 6–8, 1994, Boston, Massachusetts. 相似文献
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Organic contaminants of environmental concern such as polychlorinated biphenyls have dispersed widely throughout the ecosystems and accumulate in living organisms, and a variety of adverse biological effects have been reported. In this study, we investigated the effects of 3-chlorobiphenyl in the aquatic macrophyte Ceratophyllum demersum and the capacity of its detoxication system. After 24 h of exposure to various concentrations of 3-chlorobiphenyl, the total glutathione content (tGSH) was determined and the dose-response curves for glutathione reductase (GR) and microsomal/cytosolic glutathione S-transferases (m- and c-GSTs, respectively) were established. C. demersum showed a decrease of photosynthesis after exposure to 3-chlorobiphenyl, although only significantly at 5 microgl(-1). At 0.005 and 0.05 microgl(-1) the GR, m-GST and c-GST activities were significantly increased and concomitantly a non-significant effect on total GSH was observed. At 0.5 microgl(-1), GR as well as c-GST were still significantly induced, while at 5 microgl(-1) none of the enzymes were activated. These results show that detoxication through glutathione conjugation takes place at low concentrations of 3-chlorobiphenyl, while concentrations in the order of parts per billion cause the inactivation of the enzymatic systems evaluated, enough to place C. demersum in an important physiological stress condition. 相似文献
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Zorana Kljaković-Gašpić Snježana Herceg Romanić Tomislav Bituh Vilena Kašuba Irena Brčić Karačonji Nataša Brajenović Iva Franulović Jasna Jurasović Darija Klinčić Nevenka Kopjar Gordana Marović Mirta Milić Tatjana Orct Ankica Sekovanić Davor Želježić 《Environmental monitoring and assessment》2018,190(11):694
In this study, the influence of anthropogenic pollution on the aquatic environment of Plitvice Lakes National Park (PLNP) was investigated during 2011–2012 using a combination of chemical and cytogenetic analyses. Four groups of major contaminants [(volatile organic compounds: benzene, toluene, ethylbenzene, and xylenes (BTEX); persistent organochlorine pollutants: organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs); major and trace elements; anthropogenic radionuclides (90Sr, 134Cs, and 137Cs)] were determined in three aquatic compartments (water, sediment, fish). Mass fractions of inorganic constituents in different compartments reflected the geological background of the area, indicating their origin from predominantly natural sources. Levels of volatile and persistent organic compounds in water and fish, respectively, were very low, at levels typical for remote pristine areas. Analysis of anthropogenic radionuclides in water and sediment revealed elevated activity concentrations of 137Cs in water, and measurable 134Cs in the upper sediment layers from April 2011, possibly as a consequence of the Fukushima nuclear accident in March 2011. The potential genotoxicity of river and lake water and lake sediment was assessed under laboratory conditions using the alkaline comet assay on human peripheral blood lymphocytes, and measured levels of primary DNA damage were within acceptable boundaries. The results showed that despite the protected status of the park, anthropogenic impact exists in both its terrestrial and aquatic components. Although contaminant levels were low, further monitoring is recommended to make sure that they will not rise and cause potentially hazardous anthropogenic impacts. 相似文献
6.
Čizmić Mirta Babić Sandra Kaštelan-Macan Marija 《Environmental science and pollution research international》2017,24(25):20521-20539
Environmental Science and Pollution Research - In this work, a multi-class analytical method for determination of 22 frequently used pharmaceuticals was developed and validated. Analytes were from... 相似文献
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Abstract INA‐Petrochemical Industry Omi?alj, Yugoslavia is currently producing low density polyethylene, vinyl chloride monomer and ethylene dichloride. Because of a potentially great hazard for environmental pollution, particularly by low molecular weight chlorinated hydrocarbons, the company has been putting significant effort into its anti‐pollution programme. Modern technology, polyfunctional organization and proper control of all waste materials has enabled, thus far, no evident or noticable impact on the environment. Wastewater treatment from the source to final discharged effluent and environmental control results are described. 相似文献
9.
Spatial and Temporal Trends of Physicochemical Parameters in the Water of the Reconquista River (Buenos Aires, Argentina) 总被引:1,自引:0,他引:1
Castañé PM Rovedatti MG Topalián ML Salibián A 《Environmental monitoring and assessment》2006,117(1-3):135-144
The Reconquista river is one of the most polluted watercourses in Argentina. More than 3 million people and over 10,000 industries
are settled on its basin. The available data show that pollution is mainly related to the discharge of domestic and industrial
liquid wastes that are poured into the river almost untreated. At present no site of the river can be characterized as free
of pollutants. Samples were taken monthly from 5 sites of the river; some 18–20 physicochemical parameters were determined
in each sample. Analyses revealed significant differences in the degree of deterioration between sites. Two of them, close
to the source of the river (Cascallares-S1 and Paso del Rey-S2) resulted less polluted than the two points located close to the mouth of the river (San Martin-S4 and Bancalari-S5). The worsening of the water quality in S4–S5 was attributed to the discharges of the Moron stream, a tributary that flows into the main course of the river a complex
mixture of non treated waste waters. PCA was used in the ordination of samples (sites, season and physicochemical parameters).
In the PCA performed using all variables, the first principal component showed positive correlation with N-NH4
+, conductivity, orthophosphate, BOD5, COD and alkalinity, and negative correlation with DO. The second principal component was positively correlated with pH,
temperature and chlorophyll a and negatively with phenols and hardness. In respect to the spatial distribution, the plot of the scores for the first two
components of samples taken in each sampling station showed S1 and S2 values displayed farthest at the left side of the X axis with high DO. In contrast, S4 and S5 values stayed at the right side of this axis with high N-NH4
+, conductivity, orthophosphate, BOD5, COD and alkalinity; data of S3 were “intermediate". In order to identify seasonal trends in the concentration of contaminants scores of cases labeled by
season were plotted. The line drawn on the ordination plane showed that summer samples tended to converge to the upper right
portion of the graph where pollution variables had more importance on the first axis, and along the second axis with high
correlation with pH, temperature and chlorophyll a. Winter scores were settled in the left lower part of the plot with minor contribution of pollution parameters and more importance
of DO on the first axis. Samples of autumn and spring did not fit a clear cut pattern.
Deceased 相似文献
10.
Pérez DJ Menone ML Camadro EL Moreno VJ 《Environmental pollution (Barking, Essex : 1987)》2008,153(3):695-698
The frequency of micronuclei (MN) and chromosome aberrations in anaphase-telophase (CAAT) was determined in root tips of the wetland macrophyte Bidens laevis exposed to environmentally relevant concentrations of endosulfan (0.01, 0.02, 0.5 and 5microg/L) for 48h. MN frequency varied from 0 in negative controls and plants exposed to 0.01microg/L endosulfan to 0-3 in plants exposed to 5microg/L. Moreover, a significant concentration-dependent increase of CAAT was observed. The higher proportion of laggards and vagrand chromosomes observed at 5microg/L would indicate that endosulfan interacts with the spindle interrupting normal chromosome migration. Endosulfan resulted genotoxic to B. laevis, a species of potential value for bioassays and in situ monitoring of environmental contamination by pesticides. 相似文献