LHYMO: A new Water Framework Directive-compliant multimetric index to assess lake hydromorphology and its application to French lakes     

Alexandra Carriere  Nathalie Reynaud  Aurore Gay  Jean-Marc Baudoin  Christine Argillier 《水产资源保护:海洋与淡水生态系统》2024,34(1):e4029

Fruit development, not GPP, drives seasonal variation in NPP in a tropical palm plantation   总被引：1，自引：0，他引：1  

Navarro MN  Jourdan C  Sileye T  Braconnier S  Mialet-Serra I  Saint-Andre L  Dauzat J  Nouvellon Y  Epron D  Bonnefond JM  Berbigier P  Rouziere A  Bouillet JP  Roupsard O 《Tree physiology》2008,28(11):1661-1674

We monitored seasonal variations in net primary production (NPP), estimated by allometric equations from organ dimensions, gross primary production (GPP), estimated by the eddy covariance method, autotrophic respiration (R(a)), estimated by a model, and fruit production in a coconut (Cocos nucifera L.) plantation located in the sub-tropical South Pacific archipelago of Vanuatu. Net primary production of the vegetative compartments of the trees accumulated steadily throughout the year. Fruits accounted for 46% of tree NPP and showed large seasonal variations. On an annual basis, the sum of estimated NPP (16.1 Mg C ha(-1) year(-1)) and R(a) (24.0 Mg C ha(-1) year(-1)) for the ecosystem (coconut trees and herbaceous understory) closely matched GPP (39.0 Mg C ha(-1) year(-1)), suggesting adequate cross-validation of annual C budget methods. However, seasonal variations in NPP + R(a) were smaller than the seasonal variations in GPP, and maximum tree NPP occurred 6 months after the midsummer peak in GPP and solar radiation. We propose that this discrepancy reflects seasonal variation in the allocation of dry mass to carbon reserves and new plant tissue, thus affecting the allometric relationships used for estimating NPP.  相似文献   

Esterified whey proteins can protect Lactococcus lactis against bacteriophage infection. Comparison with the effect of native basic proteins and L-polylysines     

Sitohy M  Chobert JM  Haertlé T 《Journal of agricultural and food chemistry》2005,53(9):3727-3734

Inhibitory action of basic esterified milk whey proteins [methylated (Met) or ethylated (Et) beta-lactoglobulin (BLG) and alpha-lactalbumin (ALA)], basic native proteins (chicken egg white lysozyme and calf thymus histone), and basic protein-like substances (L-polylysines) against the activity and replication of lactococcal bacteriophages (bIL66, bIL67, and bIL170) was tested. Chemical interactions of these proteins with phage DNA were determined as well as their protective effect on the growth of a laboratory plasmid-cured Lactococcus lactis subjected to an infection by the bacteriophages. All the proteins studied showed inhibitory activity against the three bacteriophages as tested by marked reduction of their lytic activities and decreasing the replication of studied phages. Histone and Met-BLG were more active toward bIL66 and bIL67, respectively, while both proteins were highly and equally active toward bIL170. Lysozyme showed lower antiviral activity. Antiviral activity of Et-BLG was a little bit lower than that observed in the case of the Met derivative. Esterified ALA also showed considerable but slightly lower antiviral activity as compared to other proteins. L-polylysines also showed an antiviral effect against the three bacteriophages studied, their influence being highly dependent on their molecular size. The best effective size of L-polylysines was in the range 15-70 kDa. Replication of bIL67 was inhibited by the presence of esterified ALA or BLG and native basic proteins. Complete inhibition of replication of bIL67 occurred when using polylysines with molecular masses in the ranges 4-15, 15-30, and 30-70 kDa, while protein-like substrates with lower molecular masses had only a slight effect. The presence of histone and Met-BLG at a concentration of 0.13 mg/mL in the incubation medium protected L. lactis against lysis when it was subjected to an infection by bIL67 (10(5) pfu/mL). The same action was achieved by l-polylysine (15-30 kDa) used at a concentration of 0.03 mg/mL in the incubation medium.  相似文献   

Transformation of catechol in the presence of a laccase and birnessite     

Mi-Youn Ahn  Douglas D. Archibald  Jean-Marc Bollag 《Soil biology & biochemistry》2006,38(5):1015-1020

The transformation of naturally occurring phenols to humic polymers through oxidative coupling reactions may involve oxidoreductive enzymes and soil minerals as catalysts. There is limited information on the possible inhibitory or synergistic interactions between oxidoreductases and mineral catalysts as they participate in oxidative coupling of phenolic substrates. In this study, a ternary system was investigated, in which a fungal enzyme (Trametes villosa laccase), birnessite (δ-MnO₂), and a naturally occurring phenolic compound (catechol) were reacted together to model soil processes. Binary systems (catechol/laccase and catechol/birnessite) were included for comparison. In the absence of the mineral, T. villosa laccase (950 katal ml⁻¹) transformed 31% of catechol, whereas birnessite (1 mg ml⁻¹) in the absence of the enzyme showed a 24% catechol transformation. The percentages of catechol transformation in the binary systems did not accumulate in the ternary system; instead, birnessite and laccase tested together transformed only 36% of catechol. This suggested that birnessite had an inhibitory effect on substrate transformation by laccase catalysis. Enzyme assays indicated that inhibition was a result of enzyme deactivation by humic-like polymers produced by birnessite, and by Mn²⁺ ions released from the mineral. These observations underscore the importance of considering enzyme-soil mineral-organic matter interactions in studies of humus formation and contaminant removal.  相似文献   

Diffusion of oxygen in cork     

Lequin S  Chassagne D  Karbowiak T  Simon JM  Paulin C  Bellat JP 《Journal of agricultural and food chemistry》2012,60(13):3348-3356

This work reports measurements of effective oxygen diffusion coefficient in raw cork. Kinetics of oxygen transfer through cork is studied at 298 K thanks to a homemade manometric device composed of two gas compartments separated by a cork wafer sample. The first compartment contains oxygen, whereas the second one is kept under dynamic vacuum. The pressure decrease in the first compartment is recorded as a function of time. The effective diffusion coefficient D(eff) is obtained by applying Fick's law to transient state using a numerical method based on finite differences. An analytical model derived from Fick's law applied to steady state is also proposed. Results given by these two methods are in close agreement with each other. The harmonic average of the effective diffusion coefficients obtained from the distribution of 15 cork wafers of 3 mm thickness is 1.1 × 10(-9) m(2) s(-1) with a large distribution over four decades. The statistical analysis of the Gaussian distribution obtained on a 3 mm cork wafer is extrapolated to a 48 mm cork wafer, which length corresponds to a full cork stopper. In this case, the probability density distribution gives a mean value of D(eff) equal to 1.6 × 10(-9) m(2) s(-1). This result shows that it is possible to obtain the effective diffusion coefficient of oxygen through cork from short time (few days) measurements performed on a thin cork wafer, whereas months are required to obtain the diffusion coefficient for a full cork stopper. Permeability and oxygen transfer rate are also calculated for comparison with data from other studies.  相似文献   

Absence of oxysterol-like side effects in human monocytic cells treated with phytosterols and oxyphytosterols     

Vejux A  Montange T  Martine L  Zarrouk A  Riedinger JM  Lizard G 《Journal of agricultural and food chemistry》2012,60(16):4060-4066

Oxysterols, found in some commonly consumed foods, can induce a wide range of cytotoxic effects, which have been extensively studied. On the other hand, the side effects of phytosterols and oxyphytosterols are less well-known. Over the past few years, different types of foods have been enriched with phytosterols on the basis of the properties of these compounds that reduce circulating cholesterol levels in certain experimental conditions. It is therefore important to gain better knowledge of the risks and benefits of this type of diet. In this study, conducted in human monocytic U937 cells, the ability of phytosterols (sitosterol, campesterol) and oxyphytosterols (7β-hydroxysitosterol, 7-ketositosterol) to induce cell death, polar lipid accumulation, and pro-inflammatory cytokine (MCP-1; IL-8) secretion was determined and compared to that of oxysterols (7-ketocholesterol, 7β-hydroxycholesterol). Phytosterols and oxyphytosterols had no significant effects on the parameters studied; only 7β-hydroxysitosterol slightly increased cell death, whereas at the concentration used (20 μg/mL), strong cytotoxic effects were observed with the oxysterols. With sitosterol, campesterol, and 7-ketositosterol, IL-8 secretion was decreased, and with campesterol the intracellular polar lipid level was reduced. The data show that phytosterols and oxyphytosterols have no oxysterol-like side effects, and they rather argue in favor of phytosterols' beneficial effects.  相似文献   

Disease Progress Curve Parameters Help to Characterise the Types of Resistance to Late Blight Segregating in Cultivated Potato     

Sylvie Marhadour  Roland Pellé  Jean-Marc Abiven  Frédérique Aurousseau  Hervé Dubreuil  Yves Le Hingrat  Jean-Eric Chauvin 《Potato Research》2013,56(2):99-114

To decrease the environmental impact of treatments against late blight caused by Phytophthora infestans on potato, plant genetic resistance is a keystone in developing new culture strategies. Nonspecific resistance to late blight is a complex trait which is difficult to evaluate, while selection is both difficult and time consuming. However, we consider it is important to select for this type of resistance as it is a promising way to achieve durable resistance. In this study, parameters derived from disease progress curves (DPCs) were used to characterise the types of resistance among individuals of three tetraploid full-sib families named G1, B2, and K2. These families were composed of 280 (G1), 280 (B2), and 150 (K2) genotypes. Our aim was to avoid visual inspection of 5,710 DPCs and to identify genotypes exhibiting stable resistance. We used three parameters: the slope of the DPC, the date of appearance of the first symptoms in the tested genotypes compared with a susceptible standard, and the relative area under the disease progress curve (rAUDPC). Using an appropriate threshold for each parameter, we demonstrated that it is possible to classify the response of each genotype in one of the following categories: susceptible, non-specific resistance, specific resistance, non-specific resistance plus specific resistance (or specific resistance not overcome). Data were obtained each year from 2005 to 2007 under conditions of natural infection. According to the parameters analysed, non-specific resistance and specific resistance segregated in the families. The year effect was more than double the family effect for rAUDPC. Empirical adjustment of threshold values in a subsample of the tested genotypes led to an increase in the effectiveness of our classification method. Calculated classification enabled detection of stable genotypes in each family. The impact of the year effect differed with the family. In the G1 family, the distribution of genotypes in each category was relatively stable over the 3 years, whereas in K2, the proportion of genotypes demonstrating specific resistance alone increased, particularly in 2007. In the B2 family, the proportion of genotypes in the non-specific resistance category decreased from 40% to 15% from 2005 to 2006, and then remained stable in 2007. The heritabilities of the parameters ranged from 61% to 96% depending on the family and on the parameter concerned.  相似文献   

Triiodothyronine is necessary for the action of growth hormone in acclimation to seawater of brown (Salmo trutta) and rainbow trout (Oncorhynchus mykiss)   总被引：1，自引：0，他引：1  

Jacques Leloup  Jean-Marc Lebel 《Fish physiology and biochemistry》1993,11(1-6):165-173

Brown (BT) and rainbow trout (RT) in freshwater (FW) were treated with ovine growth hormone (GH), GH + iopanoic acid (IOP), and GH + IOP plus triiodothyronine (T₃) for RT only. After 1 week of treatment, trout were transferred to 30 o/oo SW and treatment continued. In FW, GH treatment increased significantly plasma T₃ level (BT) and T₃/T₄ ratio (BT and RT) by stimulating T₄ to T₃ deiodination. In the GH + IOP group, the plasma T₃ levels and T₃/T₄ ratio fell significantly as T₄ to T₃ deiodination was inhibited. In GH + IOP + T₃-treated RT, plasma T₃ and T₃/T₄ ratios increased significantly relative to other groups. No mortality occurred and plasma osmolarity (PO) was not altered by any treatment in FW. After transfer to SW, all IOP + GH trout died within 2 (BT) or 3 days (RT). All GH-treated or control BT survived to the end of the experiment (6 days). RT survival rates tended to be improved in GH and GH + IOP + T₃ groups relative to controls. Correlatively on day 1 the PO increase was significantly higher in IOP + GH groups (BT and RT) than in the other groups and significantly lower in GH and GH + IOP + T₃ treated RT than in controls from days 1 to 6. These data confirm the requirement of T₃ and deiodination of T₄ to T₃ for the development of hypoosmoregulatory mechanisms in SW as previously shown (Lebel and Leloup 1992). Furthermore, the suppression of the hypoosmoregulatory effect of GH, when conversion of T₄ to T₃ was inhibited by IOP and the reversal when T₃ was added to IOP + GH treatment suggests that GH osmoregulatory action in SW acts via the simulation of T₄-5′ monodeiodination which increases T₃ production.  相似文献   

Is selective thinning an adequate practice for adapting <Emphasis Type="Italic">Quercus ilex</Emphasis> coppices to climate change?     

Jesús Rodríguez-Calcerrada  Ignacio M. Pérez-Ramos  Jean-Marc Ourcival  Jean-Marc Limousin  Richard Joffre  Serge Rambal 《Annals of Forest Science》2011,68(3):575-585

Introduction   

Future climatic scenarios demand an increasing involvement of management for forest preservation, but little is known on how forestry practices will benefit stands in facing variation of climatic components.  相似文献   

MED23 mutation links intellectual disability to dysregulation of immediate early gene expression     

Hashimoto S  Boissel S  Zarhrate M  Rio M  Munnich A  Egly JM  Colleaux L 《Science (New York, N.Y.)》2011,333(6046):1161-1163

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