Effects of an endogeic and an anecic earthworm on the competition between four annual plants and their relative fecundity     

Kam-Rigne Laossi  Diana Cristina Noguera  Jérôme Mathieu  Sébastien Barot 《Soil biology & biochemistry》2009,41(8):1668-1673

Competition between plants for essential resources determines the distribution of biomasses between species as well as the composition of plant communities through effects on species reproductive potentials. Soil organisms influence plant competitive ability and access to resources; thus they should modify plant community composition. The effects of an endogeic (Aporrectodea caliginosa) and an anecic (Lumbricus terrestris) earthworm species on the competition between grass (Poa annua), two forbs (Veronica persica and Cerastium glomeratum) and legume (Trifolium dubium) were investigated in a greenhouse experiment. We established two types of plant communities: monocultures and polycultures of the four species. L. terrestris increased the biomass of P. annua and V. persica (in monocultures as well as in polycultures). However, the presence of L. terrestris allowed the grass to produce the highest biomass in polycultures suggesting that this earthworm species promoted the growth of P. annua against the other plant species. In monocultures as well as in polycultures, the presence of L. terrestris to increased the number of seeds of T. dubium and the total seed mass of V. persica. These results suggest that L. terrestris enhanced the short term competitive ability of P. annua by promoting its growth. The increased number of seeds of T. dubium in the presence of L. terrestris suggests that this earthworm species could enhance the long-term competitive ability of this legume and may increase its number of individuals after several generations.  相似文献   

Effects of ramipril on renal function during progressive overpacing-induced heart failure in dogs     

Mathieu M  Motte S  Ray L  Pensis A  Jespers P  Brimioulle S  Laroute V  Naeije R  Mc Entee K 《American journal of veterinary research》2006,67(7):1236-1243

OBJECTIVE: To investigate the effects of preventive angiotensin converting enzyme inhibitor treatment with ramipril in dogs with progressively severe experimentally induced heart failure. ANIMALS: 20 dogs. PROCEDURES: Dogs were randomly allocated to receive no treatment (control) or ramipril (0.125 mg/kg, PO, daily) for 7 weeks. Physical examination, repetitive catheterization of the right side of the heart, and echocardiography were performed before the study (day 0) and weekly for 7 weeks. Renal plasma flow (RPF) as determined by para-aminohippuric acid clearance and glomerular filtration rate (GFR) as determined by creatinine and iohexol clearances were measured on day 0 and at weeks 4 and 7. RESULTS: Overpacing induced a progressive increase in right atrial pressure (RAP) and pulmonary artery pressure, occluded (PAPO), with a decrease in systemic arterial pressure. There were progressive alterations of echocardiographic indices of diastolic and systolic ventricular function. The RPF and GFR decreased before cardiac output decreased, and filtration fraction increased. The logarithm of the urinary sodium-to-potassium concentration ratio (log(10)[Na(+)/K(+)]) decreased. Significant effects of ramipril included a delay in clinical signs of heart failure, a late decrease in RAP and PAPO, and increases in the sodium excretion fraction and log(10)(Na(+)/K(+)). There was a satisfactory agreement between the creatinine and iohexol clearance measurements. Conclusions AND CLINICAL RELEVANCE: Results suggest that, in this rapid-evolving, dilated cardiomyopathy, activation of the renin-angiotensin system contributes to the pathophysiology of heart failure late in the disease and essentially by an activation of renal salt and water retention.  相似文献   

Applicability of major histocompatibility complex DRB1 alleles as markers to detect vertebrate hybridization: a case study from Iberian ibex × domestic goat in southern Spain     

Samer Alasaad  Joerns Fickel  Luca Rossi  Mathieu Sarasa  Buenaventura Ben?-tez-Camacho  José E Granados  Ramón C Soriguer 《Acta veterinaria Scandinavica》2012,54(1):56

Background

Hybridization between closely related wild and domestic species is of great concern because it can alter the evolutionary integrity of the affected populations. The high allelic variability of Major Histocompatibility Complex (MHC) loci usually excludes them from being used in studies to detect hybridization events. However, if a) the parental species don’t share alleles, and b) one of the parental species possesses an exceptionally low number of alleles (to facilitate analysis), then even MHC loci have the potential to detect hybrids.

Results

By genotyping the exon2 of the MHC class II DRB1 locus, we were able to detect hybridization between domestic goats (Capra hircus) and free-ranging Iberian ibex (Capra pyrenaica hispanica) by molecular means.

Conclusions

This is the first documentation of a Capra pyrenaica × Capra hircus hybridization, which presented us the opportunity to test the applicability of MHC loci as new, simple, cost-effective, and time-saving approach to detect hybridization between wild species and their domesticated relatives, thus adding value to MHC genes role in animal conservation and management.  相似文献   

A simple stem taper model with mixed effects for boreal black spruce     

Geneviève Lejeune  Chhun-Huor Ung  Mathieu Fortin  Xiao Jing Guo  Marie-Claude Lambert  Jean-Claude Ruel 《European Journal of Forest Research》2009,128(5):505-513

We simplified Kozak’s taper model by setting the inflection point at 1.3 m (dbh) without losing accuracy and precision. The simplification was required to facilitate the estimation of the covariance parameters when using a mixed-effects method. This method was necessary to take into account the correlation among multiple diameter measurements on an individual stem. The simple stem taper model was fitted to an extended data set collected across the province of Quebec, Canada. Comparison of the predicted stem taper and the derived stem volume with those obtained using existing models showed a comparable predictive power for the simple model. Including a prediction of the tree random effects based on supplementary diameter measurements of the bole improves the predictive ability of the model around the extra diameter observation. This model offers welcome simplicity as a means of predicting tree taper at coarse resolution for planning tree harvesting.  相似文献   

Predicting individual tree mortality in northern hardwood stands under uneven-aged management in southern Québec, Canada     

Mathieu Fortin  Steve Bédard  Josianne DeBlois  Sébastien Meunier 《Annals of Forest Science》2008,65(2):205-205

This study proposes a generalized linear mixed model to predict individual tree mortality in northern hardwood stands under uneven-aged management. The model is based on a complementary log-log (CLL) link function, and was calibrated using permanent-plot data. Tree vigor, stem product, diameter at breast height and stand basal area were tested as explanatory variables. A plot and an interval random effect were specified to account for spatial correlations. When compared with the traditional logit link function, the CLL facilitates the inclusion of the time factor. In this case study, there was an important variability of mortality predictions between the plots and the intervals for a given plot. The interval random effect is thought to be associated with catastrophic mortality. Since both tree vigor and stem product proved to be significant mortality predictors, we recommend that these variables be evaluated to increase the accuracy of mortality models.  相似文献   

Organic varieties for cauliflowers and cabbages in Brittany: from genetic resources to participatory plant breeding     

Véronique Chable  Mathieu Conseil  Estelle Serpolay  François Le Lagadec 《Euphytica》2008,164(2):521-529

Plant breeding for organic agriculture (OA) was stimulated when it came under the European Organic Agriculture Regulation (2092/91) in 2004. In Brittany, the need for specific varieties for organic farming arose early for the Brassica species because of the unsuitability of most of the modern varieties to the principles of OA. Moreover, the private sector of plant breeding finds it economically difficult to satisfy the demands of OA. The aim of the present study is to provide varieties and seed for organic farmers for two vegetable Brassica crops, and to show how genetic resources can contribute to this purpose in the framework of a Participatory Plant Breeding (PPB) programme. The emergence of PPB in Brittany is the result of several concomitant and favourable circumstances: the will of the professionals (represented by IBB, Inter Bio Bretagne), their organization (an experimental station, the PAIS, Plateforme Agrobiologique d’IBB à Suscinio), the research initiative in INRA and the availability of genetic resources. From genetic resource observations, our experience showed several breeding situations: reviving a traditional activity (Roscoff cauliflower and local cabbages), extending tradition (autumn cauliflower), diversifying production by new introductions (coloured cauliflowers), and creating new forms of population varieties (broccoli and coloured cauliflowers). Farmers have taken charge of population breeding by mass selection and the PAIS, with INRA scientific support, has taken up innovative selection and the improvement of varieties completing the farmers’ initiatives. The PAIS remained the central point for information and for providing the seed for trials. Seed production will be managed in a collective way. Until now, the exchange of seed remained an experimental dimension of PPB. French seed legislation represents a limitation on the development of seed exchange by PPB.  相似文献   

Change-Point Estimation in the Multivariate Model Taking into Account the Dependence: Application to the Vegetative Development of Oilseed Rape     

V. Brault  C. Lévy-Leduc  A. Mathieu  A. Jullien 《Journal of Agricultural, Biological & Environmental Statistics》2018,23(3):374-389

In this paper, we address the change-point estimation issue in multivariate observations which consist in functions having piecewise constant first derivatives corrupted by some additional noise. We propose to solve this problem by rewriting it as a variable selection issue in a sparse multivariate linear model. Moreover, the methodology that we propose takes into account the dependence that may exist within the multivariate observations. Then, the performance of our approach is assessed through some numerical experiments and compared to other alternative and classical methods. Finally, we apply our methodology to experimental data in order to study the vegetative development of oilseed rape. The evolution of the number of leaves of oilseed rape can be modeled as a function having piecewise constant first derivatives corrupted by some additional noise where the change-points correspond to key times in the plant phenology. Our novel estimation method increases the accuracy of the change-point estimation in comparison with classical approaches. Moreover, we show that the parameters of the covariance matrix depend on the level of competition between plants. Supplementary materials accompanying this paper appear online.  相似文献   

Clinical findings and management of 153 horses with large colon sand accumulations          下载免费PDF全文

Isabelle Kilcoyne MVB  Diplomate ACVS  Julie E. Dechant DVM  MS  Diplomate ACVS & ACVECC  Sharon J. Spier DVM  PhD  Diplomate ACVIM  Mathieu Spriet DVM  MS  Diplomate ACVR & DECVR  Jorge E. Nieto MVZ  PhD  Diplomate ACVS & ACVSMR 《Veterinary surgery : VS》2017,46(6):860-867

  相似文献   

Mesh repair of a large traumatic lateral abdominal wall hernia in an 8‐day‐old foal          下载免费PDF全文

E. V. Gillam  A. Mathieu  M. Lacourt 《Equine Veterinary Education》2017,29(8):422-425

An 8‐day‐old French trotter colt was admitted with a traumatic lateral abdominal wall hernia with reducible intestinal content. A 15 cm long full thickness tear was identified in both the internal abdominal oblique and transverse abdominal muscles. This case report describes the surgical repair of the hernia using a polypropylene mesh.  相似文献   

Mixed-Effects Estimation in Dynamic Models of Plant Growth for the Assessment of Inter-individual Variability     

Charlotte Baey  Amélie Mathieu  Alexandra Jullien  Samis Trevezas  Paul-Henry Cournède 《Journal of Agricultural, Biological & Environmental Statistics》2018,23(2):208-232

Modeling inter-individual variability in plant populations is a key issue to understand crop heterogeneity and its variations in response to the environment. Being able to describe the interactions among plants and explain the variability observed in the population could provide useful information on how to control it and improve global plant growth. We propose here a method to model plant variability within a field, by extending the so-called GreenLab functional-structural plant model from the individual to the population scale via nonlinear mixed-effects modeling. Parameter estimation of the population model is achieved using the stochastic approximation expectation maximization algorithm, implemented in the platform for plant growth modeling and analysis PyGMAlion. The method is first applied on a set of simulated data and then on a real dataset from a population of 34 winter oilseed rape plants at the rosette stage. Results show that our method allows for a good characterization of the variability in the population with only a limited number of parameters, which is a key point for plant models. Results on simulated data show that parameters associated with a low sensitivity index are inaccurately estimated by the algorithm when considered as random effects, but a good stability of the results can be obtained by considering them as fixed effects. These results open new ways for the analysis of inter-plant variability within a population and the study of plant–plant competition.Supplementary materials accompanying this paper appear online.  相似文献