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31.
RAFAEL MARCÉ MIQUEL ÀNGEL RODRÍGUEZ‐ARIAS JUAN CARLOS GARCÍA JOAN ARMENGOL 《Global Change Biology》2010,16(10):2857-2865
Low dissolved oxygen concentration in bottom layers of lakes and reservoirs usually indicates low water quality. In lakes, empirical models predicting anoxia are almost entirely based on the decay of plankton biomass, while in reservoirs recent findings suggest a prominent role of streamflow and load of organic carbon. This suggests a potential link between water quality in reservoirs and climate processes affecting streamflow. Here we support this hypothesis presenting evidence that both interannual climate variability and recent climate change, mainly consisting in a significant increase in potential evapotranspiration in the upstream basin, affected the oxygen content in a Mediterranean reservoir (Sau Reservoir, Spain). Using a 44‐year monthly record, we found strong and consistent signatures of El Niño Southern Oscillation in the inflow and reservoir oxygen content. Spectral and wavelet techniques showed that the El Niño, streamflow, and reservoir oxygen content series oscillated in common periods, which coincided with the main El Niño variability modes. An empirical model explaining the annual oxygen content in the reservoir suggested that a decreasing streamflow trend reduced the oxygen content of the reservoir by about 20%, counteracting remediation measures implemented at the basin upstream the reservoir. Our results provide the first quantitative evidence of climate change effects on reservoir water quality using long‐term instrumental data, and indicate that streamflow should be considered as a key variable in assessing climate change impact on reservoir water quality. These results are especially relevant in regions of the world where reservoirs are abundant and most climate models predict a decrease in runoff during the next decades. Both the expected trends and the sensitivity of reservoir water quality to global interannual climate variability should be considered for a correct management of water resources in the present and to design adaptation policies in the future. 相似文献
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Jiménez Jose C. Bayó Nuria Chavarría Bibiana López-Macià Àngel Royo Miriam Nicolás Ernesto Giralt Ernest Albericio Fernando 《International journal of peptide research and therapeutics》2002,9(2-3):135-141
Summary α, β-Didehydroamino acids, which are key components of both natural andde novo peptides, are frequently encountered in naturally occurring peptides — mostly of microbial and fungal origin and/or from
marine organisms. Herein, we report on a reappraisal of the use of the water-soluble carbodiimide/CuCl method for the preparation
of this kind of peptide in both solution and solid-phase modes and describe some side reactions encountered during the process.
Abbreviations: Alloc, allyloxycarbonyl; Barlos resin, 2-chlorotrityl chloride resin, Boc,tert-butoxycarbonyl; Boc2O, di-tert-butyl dicarbonate; Bzl, benzyl; DABCO, 1,4-diazabicyclo[2.2.2]octane; DAST, (diethylamino)sulfur trifluoride; DBU, 1,8-diazabicyclo[5.4.0]undec-7-ene;
DDAAs, α, β-didehydroarnino acids; DEAD, diethyl azodicarboxylate; Dha, Didehydroalanine, (Z)-Dhb, Z-Didebydroaminobutyric
acid; (Z)-Dhp, Z-Didehydrophenylalanine; DSC, disuccinimidyl carbonate; DDP, α, β-didehydropeptides; EDC, WSC, 3-(3′-dimethylaminopropyl)-1-ethylearbodiimide;
Fmoc, fiuorenylmethoxycarbonyl; HATU, N-{(dimethylamino)-1H-1,2,3-triazolo[4,5-b]pyridino-1-ylmethylene}-N-methylmethanaminium
hexafluorophosphate; HOAt, 1-hydroxy-7-azabenzotriazole; (β-OH)Phe, phenylserine or β-hydroxyphenylalanine; Ph3P, triphenylphosphine; PyAOP, (7-azabenzotriazol-1-yloxy)-tris(pyrrolidino)phosphonium hexafluorophosphate; TEA, triethylamine;
TFA, trifluoroacetic acid. Amino acid symbols denote thel-configuration unless stated otherwise. All solvent ratios are volume/volume unless stated otherwise. 相似文献
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34.
We investigate the evolution of the age (or size) at sex-reversal in a model of sequential hermaphroditism, by means of the
function-valued adaptive dynamics. The trait is the probability law of the age at sex-reversal considered as a random variable.
Our analysis starts with the ecological model which was first introduced and analyzed by Calsina and Ripoll (Math Biosci 208(2),
393–418, 2007). The structure of the population is extended to a genotype class and a new model for an invading/mutant population
is introduced. The invasion fitness functional is derived from the ecological setting, and it turns out to be controlled by
a formula of Shaw–Mohler type. The problem of finding evolutionarily stable strategies is solved by means of infinite-dimensional
linear optimization. We have found that these strategies correspond to sex-reversal at a single particular age (or size) even
if the set of feasible strategies is considerably broader and allows for a probabilistic sex-reversal. Several examples, including
in addition the population-dynamical stability, are illustrated. For a special case, we can show that an unbeatable size at
sex-reversal must be larger than 69.3% of the expected size at death. 相似文献
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Ethnobotany of Sambucus nigraL. in Catalonia (Iberian Peninsula):The Integral Exploitation of a Natural Resource in Mountain Regions. Economic Botany 58(3):456-469, 2004. We present in this paper data about the popular uses of elder (Sambucus nigra) obtained in two ethnobotanical studies carried out in the districts (comarques) of Pallars Jussà and Pallars Sobirà (Pyrenees) and in the Montseny Massif (Catalan Prelittoral Range), complemented with others from different Catalan regions (also investigated by our group) and compared with those from other Iberian and Mediterranean territories. This bush or small tree belonging to the family Caprifoliaceae is one of the plants that have been most reported and used (for medicinal and other purposes) by the informants, not only in the two regions studied but in all Catalonia and in many Mediterranean areas as well. It is one of the most versatile of plants, being used for food, medicine, crafts and games, as well as for ornamental purposes. In addition, almost every part of the plant, including the bark, roots, leaves, flowers, and fruit, has some uses. 相似文献
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Jörg Schaber Miquel Àngel Adrover Emma Eriksson Serge Pelet Elzbieta Petelenz-Kurdziel Dagmara Klein Francesc Posas Mattias Goksör Mathias Peter Stefan Hohmann Edda Klipp 《European biophysics journal : EBJ》2010,39(11):1547-1556
Parameterized models of biophysical and mechanical cell properties are important for predictive mathematical modeling of cellular processes. The concepts of turgor, cell wall elasticity, osmotically active volume, and intracellular osmolarity have been investigated for decades, but a consistent rigorous parameterization of these concepts is lacking. Here, we subjected several data sets of minimum volume measurements in yeast obtained after hyper-osmotic shock to a thermodynamic modeling framework. We estimated parameters for several relevant biophysical cell properties and tested alternative hypotheses about these concepts using a model discrimination approach. In accordance with previous reports, we estimated an average initial turgor of 0.6 ± 0.2 MPa and found that turgor becomes negligible at a relative volume of 93.3 ± 6.3% corresponding to an osmotic shock of 0.4 ± 0.2 Osm/l. At high stress levels (4 Osm/l), plasmolysis may occur. We found that the volumetric elastic modulus, a measure of cell wall elasticity, is 14.3 ± 10.4 MPa. Our model discrimination analysis suggests that other thermodynamic quantities affecting the intracellular water potential, for example the matrix potential, can be neglected under physiological conditions. The parameterized turgor models showed that activation of the osmosensing high osmolarity glycerol (HOG) signaling pathway correlates with turgor loss in a 1:1 relationship. This finding suggests that mechanical properties of the membrane trigger HOG pathway activation, which can be represented and quantitatively modeled by turgor. 相似文献
38.
ANTONIO DIAZ‐ESPEJO MAGDALENA TOMÀS HIPÓLITO MEDRANO 《Plant, cell & environment》2014,37(12):2707-2721
Crown carbon gain is maximized for a given total water loss if stomatal conductance (gs) varies such that the marginal carbon product of water (?A/?E) remains invariant both over time and among leaves in a plant crown, provided the curvature of assimilation rate (A) versus transpiration rate (E) is negative. We tested this prediction across distinct crown positions in situ for the first time by parameterizing a biophysical model across 14 positions in four grapevine crowns (Vitis vinifera), computing optimal patterns of gs and E over a day and comparing these to the observed patterns. Observed water use was higher than optimal for leaves in the crown interior, but lower than optimal in most other positions. Crown carbon gain was 18% lower under measured gs than under optimal gs. Positive curvature occurred in 39.6% of cases due to low boundary layer conductance (gbw), and optimal gs was zero in 11% of cases because ?A/?E was below the target value at all gs. Some conclusions changed if we assumed infinite gbw, but optimal and measured E still diverged systematically in time and space. We conclude that the theory's spatial dimension and assumption of positive curvature require further experimental testing. 相似文献
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ARIADNA SITJÀ-BOBADILLA PILAR ALVAREZ-PELLITERO 《The Journal of eukaryotic microbiology》1993,40(6):755-764
A new Myxosporea, Zschokkella mugilis n. sp., was found in the gall bladder of several mugilids. It is distinguished from all previously reported Zschokkella from mugilids by the absence of valve ornamentation and from other species by the size of the spores. Prevalence of infection was 62.5% for Mugil capito, 70% for M. cephalus and 64.3% for Liza saliens. Plasmodia with rhizoids attached to epithelial cells appeared to compromise the host as evidenced in light and transmission electron micrographs presented herein. General ultrastructure and disporous sporogenesis of Z. mugilis resembled other Myxosporeans, but sporogonic cells did not seem to be formed in pansporoblasts. 相似文献