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1.
Maria João Feio Trefor B. Reynoldson Verónica Ferreira Manuel Augusto S. Graça 《Hydrobiologia》2007,579(1):55-68
We sampled macroinvertebrates at 75 locations in the Mondego river catchment, Central Portugal, and developed a predictive
model for water quality assessment of this basin, based on the Reference Condition Approach. Sampling was done from June to
September 2001. Fifty-five sites were identified as “Reference sites” and 20 sites were used as “Test sites” to test the model.
At each site we also measured 40 habitat variables to characterize water physics and chemistry, habitat type, land use, stream
hydrology and geographic location. Macroinvertebrates were generally identified to species or genus level; a total of 207
taxa were found. By Unweighted Pair Group Method with Arithmetic mean (UPGMA) clustering and analysis of species contribution
to similarities percentage (SIMPER), two groups of reference sites were established. Using Discriminant Analysis (stepwise
forward), four variables correctly predicted 78% of the reference sites to the appropriate group: stream order, pool quality,
substrate quality and current velocity. Test sites’ environmental quality was established from their relative distance to
reference sites, in MDS ordination space, using a series of bands (BEAST methodology). The model performed well at upstream
sites, but at downstream sites it was compromised by the lack of reference sites. As with the English RIVPACS predictive model,
the Mondego model should be continually improved with the addition of new reference sites. The adaptation of the Mondego model
methodology to the Water Framework Directive is possible and would consist mainly of the integration of the WFD typology and
increasing the number of ellipses that define quality bands.
Handling editor: K. Martens 相似文献
2.
J. Paupério J. S. Herman J. Melo‐Ferreira M. Jaarola P. C. Alves J.B. Searle 《Molecular ecology》2012,21(24):6015-6032
Species are generally described from morphological features, but there is growing recognition of sister forms that show substantial genetic differentiation without obvious morphological variation and may therefore be considered ‘cryptic species’. Here, we investigate the field vole (Microtus agrestis), a Eurasian mammal with little apparent morphological differentiation but which, on the basis of previous sex‐linked nuclear and mitochondrial DNA (mtDNA) analyses, is subdivided into a Northern and a Southern lineage, sufficiently divergent that they may represent two cryptic species. These earlier studies also provided limited evidence for two major mtDNA lineages within Iberia. In our present study, we extend these findings through a multilocus approach. We sampled 163 individuals from 46 localities, mainly in Iberia, and sequenced seven loci, maternally, paternally and biparentally inherited. Our results show that the mtDNA lineage identified in Portugal is indeed a distinct third lineage on the basis of other markers as well. In fact, multilocus coalescent‐based methods clearly support three separate evolutionary units that may represent cryptic species: Northern, Southern and Portuguese. Divergence among these units was inferred to have occurred during the last glacial period; the Portuguese lineage split occurred first (estimated at c. 70 000 bp ), and the Northern and Southern lineages separated at around the last glacial maximum (estimated at c. 18 500 bp ). Such recent formation of evolutionary units that might be considered species has repercussions in terms of understanding evolutionary processes and the diversity of small mammals in a European context. 相似文献
3.
Margarida A. Ferreira M.Aurea Cruz Costa A.Correia Alves M.Helena Lopes 《Phytochemistry》1973,12(2):433-435
7-MethyljugIone, 8,8′-dihydroxy-4,4′-dimethoxy-6,6′-dimethyl-2,2′-binaphthyl-1,1′-quinone, 2-methylnaphthazarin, mamegakinone and euclein have been isolated from Euclea pseudebenus. Euclein is the 3,6′-dimer of 7-methyljuglone. 相似文献
4.
In the sequence of superorders Rutiflorae-Santaliflorae-Araliiflorae-Asteriflorae an increase in the mean oxidation state for each series of Cn-polyacetylenes and an extension in the range of the carbon atoms of these polyacetylenes in the direction of smaller numbers are observed. These trends of polyacetylene evolution also seem to be operative at lower hierarchic levels in the family Asteraceae. 相似文献
5.
6.
Reconstitution of the two terminal enzymes of the heme biosynthetic pathway into phospholipid vesicles 总被引:1,自引:0,他引:1
Purified mouse protoporphyrinogen oxidase (EC 1.3.3.4) and ferrochelatase (EC 4.99.1.1), the two terminal enzymes of the heme biosynthetic pathway, have been reconstituted into phospholipid vesicles, and the kinetics of the enzymes in the reconstituted systems were compared with the values obtained with the free enzymes. The apparent Km for free protoporphyrinogen oxidase in detergent solution is 5.61 +/- 0.62 microM for free protoporphyrinogen. The Km was lower when the enzyme was inserted into phospholipid vesicles (0.78 +/- 0.28 microM) and when both enzyme and substrate were incorporated into phospholipid vesicles (0.61 +/- 0.14 microM). In the presence of cardiolipin, a phospholipid present mainly in the inner mitochondrial membrane, the value of the Km for the substrate decreased 3-fold (0.20 +/- 0.02 microM). For reconstituted ferrochelatase similar kinetic analyses were carried out and it was found that the apparent Km values were only weakly affected by the lipid environment. Studies on the orientation of ferrochelatase demonstrated that approximately 50% of the enzyme in the reconstituted system had the active site located in the inner face of the phospholipid vesicle. This is in contrast to intact mitochondria where the active site is located on the matrix side of the inner mitochondrial membrane. The activation energies for both enzymes were determined for free and reconstituted enzymes. It was found that for both enzymes the activation energies were lower for the reconstituted systems than for the free enzymes. 相似文献
7.
Distribution of the major light-harvesting chlorophyll a/b-protein (LHCII) and its mRNA within bundle sheath and mesophyll cells of maize (Zea mays L.) was studied using in situ immunolocalization and hybridization, respectively. In situ hybridization with specific LHCII RNA probes from maize and Lemna gibba definitively shows the presence of high levels of mRNA for LHCII in both bundle sheath cells and mesophyll cells. In situ immuno-localization studies, using an LHCII monoclonal antibody, demonstrate the presence of LHCII polypeptides in chloroplasts of both cell types. The polypeptide composition of LHCII and the amount of LHCII in bundle sheath cells are different from those in mesophyll cells. Both mesophyll and bundle sheath chloroplasts can take up, import and process the in vitro transcribed and translated LHCII precursor protein from L. gibba. Although bundle sheath chloroplasts incorporate LHCII into the pigmented light-harvesting complex, the efficiency is lower than that in mesophyll chloroplasts. 相似文献
8.
Mouse protoporphyrinogen oxidase. Kinetic parameters and demonstration of inhibition by bilirubin. 总被引:4,自引:1,他引:3 下载免费PDF全文
The penultimate step of haem biosynthesis, the oxidation of protoporphyrinogen to protoporphyrin, was examined with purified murine hepatic protoporphyrinogen oxidase (EC 1.3.3.4) in detergent solution. The kinetic parameters for the two-substrate (protoporphyrinogen and oxygen) reaction were determined. The limiting Km for protoporphyrinogen when oxygen is saturating is 6.6 microM, whereas the Km for oxygen with saturating concentrations of protoporphyrinogen is 125 microM. The kcat. for the overall reaction is 447 h-1. The ratio of kcat. to the Km for protoporphyrinogen is approx. 20-fold greater than the kcat./Km,O2 ratio. The ratio of protoporphyrin formed to dioxygen consumed is 1:3. Ubiquinone-6, ubiquinone-10 and dicoumarol stimulate protoporphyrinogen oxidase activity at low concentrations (less than 15 microM), whereas coenzyme Q0 and menadione show no activation at these concentrations. Above 30 microM, all five quinones inhibit the enzyme activity. FAD does not significantly affect the activity of the enzyme. Bilirubin, a product of haem catabolism, is shown to be a competitive inhibitor of the penultimate enzyme of the haem-biosynthetic pathway, protoporphyrinogen oxidase, with a calculated Ki of 25 microM. The terminal enzyme of haem-biosynthetic pathway, namely ferrochelatase, is not inhibited by bilirubin at concentrations over double the Ki value for the oxidase. In contrast with other enzymic systems, the toxicity of bilirubin is not reversed by binding to albumin. 相似文献
9.
10.
Summary A pot experiment with lettuce involving three N forms each at six application levels, showed that lettuce can be grown satisfactorily
with a very low nitrate content when supplied with ammonium sulphate and a nitrification inhibitor. For plants growing on
nitrate N, the optimum midrib sap nitrate concentration as maturity approached was about 1400 mg/1 NO3-N. Large losses of mineral N were observed from the peat medium, even in the absence of plants.
A relationship is presented which would enable a lettuce grower to estimate whole-shoot nitrate concentration from a quick
test of midrib sapi.e. NO3-N (mg/kg in fresh shoot) =0.14×NO3-N (mg/l in sap).
Tipburn was worst at intermediate levels of applied N, and was less serious with pure ammonium nutrition than with nitrate. 相似文献