Soil macrofaunal biodiversity in Amazonian pastures: Matching sampling with patterns

Soil biodiversity varies through space as influenced by habitat features and land-use history. The performance of any sampling strategy highly depends on its relevance with regards to this pattern. We surveyed the soil macrofaunal species richness in the pastures of the Benfica Field Station (Eastern Amazonia, State of Pará, Brazil) and described its variability in 4 independent replicate plots. We designed a within-plot sampling scheme that accounted for the soil spatial variation (stratified sampling). Replicated pasture plots had different species richness (49-65) corresponding to a low proportion (40-53%) of the total number of species (123). Pairs of replicated plots showed an outstandingly low number of shared species (28-41% of the species pool). Likewise, different classes of soil thickness, corresponding to a Ferralsol-Cambisol sequence, had different species richness (12-44) and exhibited a very low proportion of shared species (15-29%). The proportion of rare species, i.e. singletons, ranged from 40-51% of the total species richness depending on the plot considered. We used the abundance-based coverage estimator of species richness (ACE) and the Chao shared species estimator that provides a correction based on the relative abundance of rare species. These indices also showed both a high between plots dissimilarity and a substantial within plot variability of species composition. Because of the high proportion of rare species, the rarefaction curves failed to reach any asymptote in all replicated plots. Bootstrap resampling showed that less than 5 samples per stratum (class of soil thickness) provided inconsistent species richness values. We simulated the efficiency of sampling strategies that included our 4 replicate plots and the 3 classes of soil thickness but with varying sampling effort within each stratum. The results indicated that a fairly large (74%) proportion of species would be recorded if strata were sampled using 5 sampling units (hence 15 samples per plot for a total of 4×15=60 samples). This study showed the need for adequate plot replication in soil macrofaunal biodiversity studies. Also, the main relevant factors of within-replicate plot spatial heterogeneity (e.g. soil, vegetation) should be accounted for through stratified sampling. The results showed that there is no way of reducing the local sampling effort below a certain level (here, 5 sampling units per stratum).     

Genetic parameters of growth,straightness and wood chemistry traits in <Emphasis Type="Italic">Pinus pinaster</Emphasis>

Introduction   

Tree breeding is giving an increasing attention to wood properties in order to better fit the requirements of the saw, board, pulp and paper industries. In particular, it has been reported that lignin and cellulose content display moderate to high heritabilities making them prime candidates for genetic improvement of wood chemistry. Moreover, these traits have been shown to be negatively correlated at both phenotypic and genetic levels. However, they have generally been evaluated against a narrow genetic background, and little is known about their correlations with mandatory selection criteria such as growth and straightness.     

Inflammatory cytokines IL-6 and TNF-α regulate lymphocyte trafficking through the local lymph node

Lymphocyte trafficking from blood to lymph and back is a tightly regulated process. Given appropriate stimuli, trafficking of cells through the lymph node changes from a 'steady-state' to a bimodal flow. Initially, a 'shutdown' phase occurs, leading to a dramatic reduction in efferent cell output. This is followed by a 'recruitment' phase whereby the efferent cell output becomes greatly elevated before returning to baseline levels. The shutdown/recruitment process is hypothesised to promote encounters between Ag-specific lymphocytes and APCs in an environment conducive to immune response induction. Cytokines, such as TNF-α have been shown to play an important role in regulating lymphocyte trafficking. Here, we unravel the role of cytokines in the regulation of cell trafficking using an in vivo sheep lymphatic cannulation model whereby the prefemoral lymph nodes were cannulated and recombinant cytokines were injected subcutaneously into the draining area of the cannulated node. We demonstrate that local injection of purified IL-6 or TNF-α stimulates shutdown/recruitment in the draining lymph node. While the effect of IL-6 appears to be direct, TNF-α may mediate shutdown/recruitment through IL-6.     

Polyphenol oxidase and peroxidase expression in four pineapple varieties (Ananas comosus L.) after a chilling injury

Pineapple internal browning (IB) is a chilling injury that produces enzymatic browning associated with flesh translucency. Pineapple biodiversity allowed the investigation of how polyphenol oxidase (PPO) and peroxidase (POD) activities with their different isoforms are involved in the IB mechanism. Fruits of four varieties that expressed IB symptoms differently, Smooth Cayenne (SCay) and the hybrids MD2, Flhoran 41 (Flh 41), and Flhoran 53 (Flh 53), were stressed by cold. The susceptible varieties showed classical brown spots but different patterns of IB, whereas MD2 and controls showed no IB. Enzymatic activities were measured on fruit protein extracts and PPO and POD isoforms separated on mini-gels (PhastSystem). Only PPO activity was significantly enhanced in the presence of IB. Up to six PPO isoforms were identified in the susceptible varieties. PPO was barely detectable in the nonsusceptible variety MD2 and in controls. The number of PPO isoforms and the total PPO activity after chilling are varietal characteristics.     

Set up of simple sequence repeat markers and first investigation of the genetic diversity of West-African watermelon (<Emphasis Type="Italic">Citrullus lanatus</Emphasis> ssp. <Emphasis Type="Italic">vulgaris</Emphasis> oleaginous type)

Citrullus lanatus ssp. vulgaris oleaginous type (West-African watermelon) is a crop cultivated in sub-Saharan Africa for its dried seeds reported to be rich in nutrients. In previous studies, little polymorphism was found in watermelon—cultivated for its flesh with the use of microsatellite (SSR) markers. Such study has never been applied to the oleaginous type until now. The objectives of the present study were firstly to apply the SSR markers set up for watermelon to the West-African watermelon and secondly to study the genetic structure of this type in Ivory Coast. For the first objective, 37 markers were studied on eight plants pertaining to four accessions. For the second objective, the polymorphic markers were applied on three morphologically and geographically separated accessions with twenty plants per accession. Multiple correspondence analysis (MCA), unweighted pair-group method with arithmetic averaging (UPGMA), molecular analysis of variance (AMOVA) and assignments test structure were applied. The optimal annealing temperature varied from 49 to 59°C according to the markers. Thirty-two markers that proved to amplify their respective loci were selected, but only nine of them appeared to show polymorphism on the set of 8 plants studied. The application of these markers on the three accessions revealed several features. No stucturation into sub-populations was observed inside a given accession. The genetic variance proved to be substantially higher between the different accessions than inside a given accession. Moreover this analysis is a first hint that the morphology classification does not match the genetic structure of C. lanatus. The results of this work provide the first quantitative information regarding the genetic variability of Citrullus lanatus oleaginous type. In order to sharpen our understanding of the mechanisms responsible for the genetic variance inter/intra accessions, further studies based on a larger sample of plants and accessions are required.     

Assessing the influence of resource covariates at multiple spatial scales: an application to forest-dwelling caribou faced with intensive human activity

Efforts in isolating the relative effects of resources and disturbances on animal-distribution patterns remain hindered by the difficulty of accounting for multiple scales of resource selection by animals with seasonally dynamic drivers. We developed multi-scale, seasonal models to explore how local resource selection by the threatened forest-dwelling woodland caribou (Rangifer tarandus caribou) was influenced by both broad-scale landscape context and local resource heterogeneity in the intensively managed region of Charlevoix, Québec, Canada, located on the southern border of the North American caribou range. We estimated resource selection functions using 23 GPS-collared caribou monitored from 2004 to 2006 and landscape data on vegetation classes, terrain conditions, and roads. We found evidence of thresholds in road “proximity” effects (up to 1.25 km), which underscores the importance of including landscape context variables in addition to locally measured variables, and of fitting seasonal-specific models given temporal variation in the magnitude of selection and optimal scale of measurement. Open lichen woodlands were an important cover type for caribou during winter and spring, whereas deciduous forests, wetlands, and even young disturbed stands became important during calving and summer. Caribou consistently avoided roads and rugged terrain conditions at both local and landscape levels. Landscape context fundamentally constrains the choices available to animals, and we showed that failing to consider landscape context, or arbitrarily choosing an inappropriate scale for measuring covariates, may provide biased inferences with respect to habitat selection patterns. Effective habitat management for rare or declining species should carefully consider the hierarchical nature of habitat selection.     

Application of Soil Fractionation Methods to the Study of the Distribution of Pollutant Metals

Three agricultural Fluvisols polluted by sewage sludge were dispersed by shaking in water or in organic solvent for particle size and density separations. The perturbations caused by the ultrasonic treatment were discussed. Only the carbonate particles were disrupted to very fine particles. The pollutant metals were not displaced by the treatments, except perhaps Cd that is partly soluble in water and in other solvents. We discussed the relationship between soil constitution and major element chemical analyses. We obtained enough different fractions by using the ultrasonic and other dispersion treatments and by fractionating versus two physical parameters (i.e. particle size and density), for a correlation study between the contents of major and trace elements. We found that Cu was the only element to be more concentrated in the “free” organic matter. Other metals were more concentrated within an organo-mineral compartment, containing evoluted organic matter, fine clay and hydrous oxides. No pollutant metals were associated with carbonates, feldspars, and quartz. Other less general features were discussed.     

Cytokine and chemokine gene expression of IL-1beta stimulated equine articular chondrocytes

OBJECTIVE: To evaluate mRNA expression of several proinflammatory and anti-inflammatory cytokines and chemokines in equine unstimulated and interleukin-1beta (IL-1beta)-stimulated chondrocytes. STUDY DESIGN: In vitro experiment using equine chondrocyte cultures. SAMPLE POPULATION: Whole articular cartilage from metacarpophalangeal joints (n=5 horses; 10 fetlocks). METHODS: Chondrocyte monolayer cultures were established from digested adult equine articular cartilage and stimulated with 5 ng/mL of recombinant human IL-1beta. RNA was extracted from the cells 24 hours after stimulation. IL-1beta, IL-4, IL-6, IL-8, tumor necrosis factor-alpha (TNF-alpha), and ubiquitin (house keeping gene) mRNA expression were investigated by real-time RT-PCR. RESULTS: IL-1beta, IL-6, and IL-8 mRNA were expressed in unstimulated chondrocytes from macroscopically normal joints and were significantly up-regulated after stimulation (5/5 horses). IL-4 mRNA was not detected in any samples (0/5 horses). TNF-alpha mRNA, by comparison, was expressed in 2/5 unstimulated samples and in all stimulated samples but a considerable sample variation in response to IL-1beta stimulation was observed. CONCLUSIONS: Equine chondrocytes express mRNA for several proinflammatory cytokines and chemokines and IL-1beta modulates their expression. CLINICAL RELEVANCE: Chondrocytes express proinflammatory cytokines and chemokines capable of modulating a local inflammatory cascade in articular cartilage, which could potentially lead to focal degradation and osteoarthritis.