Effect of Geogenic Lead on Fungal and Collembolan Communities in Garden Topsoil

Geogenic lead (Pb) is considered to be less bioavailable than anthropogenic Pb and exerts less effect on the soil fauna. However, Pb contamination in vegetables has been reported in the case of geogenic anomalies, even at moderate concentrations (around 170 mg kg^–1). In this study, we investigated collembolan communities using both taxonomic- and trait-based approaches and observed fungal communities to assess the effects of a moderate geogenic Pb anomaly on collembolans and fungi in an urban vegetable garden soil. Results indicated that geogenic Pb indeed modified fungi communities and altered the functional structure of collembolan communities in garden soils. Although geogenic Pb presented low bioavailability, it affected soil fauna and vegetables similar to anthropogenic Pb.     

Modelling transport of chokka squid (Loligo reynaudii) paralarvae off South Africa: reviewing,testing and extending the ‘Westward Transport Hypothesis’

Annual landings of chokka squid (Loligo reynaudii), an important fishing resource for South Africa, fluctuate greatly, and are believed to be related to recruitment success. The ‘Westward Transport Hypothesis’ (WTH) attributes recruitment strength to variability in transport of newly hatched paralarvae from spawning grounds to the ‘cold ridge’ nursery region some 100–200 km to the west, where oceanographic conditions sustain high productivity. We used an individual‐based model (IBM) coupled with a 3‐D hydrodynamic model (ROMS) to test the WTH and assessed four factors that might influence successful transport – Release Area, Month, Specific Gravity (body density) and Diel Vertical Migration (DVM) – in numerical experiments that estimated successful transport of squid paralarvae to the cold ridge. A multifactor ANOVA was used to identify the primary determinants of transport success in the various experimental simulations. Among these, release area was found to be the most important, implying that adult spawning behaviour (i.e., birth site fidelity) may be more important than paralarval behaviour in determining paralarval transport variability. However, specific gravity and DVM were found to play a role by retaining paralarvae on the shelf and optimizing early transport, respectively. Upwelling events seem to facilitate transport by moving paralarvae higher in the water column and thus exposing them to faster surface currents.     

Specific proteins allow classification of pigs according to sire breed, rearing environment and gender

The present study used a proteomic data set obtained from a 2 × 2 × 2 factorial experiment on longissimus muscle of 24 pigs to identify single or couples of proteins allowing correct classification of pigs according to gender, sire breed, or rearing environment. An actin isoform, a myosin light chain 2 isoform and cytochrome Bc1 allowed each, correct classification of all pigs according to gender. Peroxiredoxin 6 allowed correct classification of 23 pigs according to indoor or outdoor rearing environment, but only if gender was also taken into account. Heat shock protein 73 allowed correct classification of 21 pigs according to sire breed, Duroc or Large White. Results show that proteins may be used as biomarkers for traceability or genetic research. Relationships between treatment factors and intracellular regulatory mechanisms associated with these proteins are discussed.     

Ranking temperate woody species along a gradient of browsing by deer

As a result of diverse management policies, densities of red and roe deer have varied considerably for the last few decades in Europe. Their selective browsing on woody species can modify the interactions between competing species and thus change overall patterns of plant diversity in forests. However, no classification of woody species according to browsing by deer yet exists in Europe. The selectivity index, which measures the balance between availability and consumption of plant species by herbivores, could be used for such a classification. The aim of this study was, first, to rank woody species according to this selectivity index, then to test whether their rank changed when browsing pressure varied in space or time. We also explored morphological and ecological life traits (Ellenberg indicator values) that might explain differences in selectivity.In 2006, we re-sampled a network of 217 coupled floristic and browsing survey plots, which had been previously described twice (1976, 1981). The plots were located in the forest of Arc-en-Barrois (France), a large woodland area divided into a North and a South Forest which have had different histories of browsing pressure.For the three samples and the two forests, we calculated a selectivity index for 19 woody species. Dogwood (Cornus sp.) and field rose (Rosa arvensis) appeared to be the most selected species whereas beech (Fagus sylvatica), common mezereon (Daphne mezereum) and wild-service tree (Sorbus torminalis) were always avoided. The rank order of species according to their selectivity index remained stable over the three sample years and between the two forests (Spearman's rank correlations: ρ ≈ 0.8 spatially, and range from 0.3 to 0.8 temporally). This indicates that variations in browsing pressure did not strongly modify deer selectivity patterns. Selectivity was positively correlated with wood density and negatively correlated with maximum height of the species, but unrelated to other plant traits. Finally, selectivity can be seen as an intrinsic characteristic of those woody species, and could be used as an additional life trait when analyzing vegetation communities.     

Analyses of albumins, globulins and amphiphilic proteins by proteomic approach give new insights on waxy wheat starch metabolism

Starch is composed of two types of glucose polymers: amylose and amylopectin. The Waxy (Wx) locus controls amylose synthesis in the wheat kernel. Hexaploid wheat has three Wx loci located on chromosomes 7A (Wx-A1), 4A (Wx-B1), and 7D (Wx-D1). Eight near isogenic lines (NILs) of Triticum aestivum cv. Tremie with one, two or three Wx null alleles were used. The albumin–globulin fraction, and amphiphilic proteins were separated using 2-dimensional electrophoresis (2DE) allowing the changes in the waxy kernel to be identified. Albumin–globulin fraction showed overexpression of sucrose synthases in the waxy NILs compared to the normal form of Tremie and a decrease in many proteins related to stress and defence metabolism such as serpins. A subunit of ADP-glucose pyrophosphorylase (AGPase), which is known to play a major role in starch synthesis, was also shown to be down regulated in the waxy NILs. Amphiphilic proteins confirmed the observations made on the albumin–globulin fraction with a decrease in a stress-related protein. These different regulations linked to observations made on wheat kernel (thousand kernel weight (TKW), protein amount per grain, size and distribution of the starch granules) led to formulation of the hypothesis that waxy endosperm does not reach maturity of the wild-type endosperm.     

Impact of okra leaf curl disease on morphology and yield of okra

The impact of okra leaf curl disease on four accessions of a local okra cultivar and four commercial okra cultivars was assessed in field conditions from June to October in 2007 and 2008. Disease incidence varied from 68.5% to 72.5% among accessions of the local cultivar while commercial cultivars were much less infected (8.7–16.2%). Diseased plants of the local cultivar suffered more reduced growth (58% reduction) than those of the commercial cultivars (39.6%). The number of marketable fruits per plant, the fruit length, fruit diameter and fruit weight which were subject to reductions of 26–61%, 19–64%, 6–42% and 23–63%, respectively. The overall yield losses were significantly higher in accessions of the local cultivar (26–55%) than in the commercial ones (4.4–9.6%). The average economic losses for one hectare of crop were estimated at of 11,100 USD and 1950 USD, respectively for the local and the commercial cultivars.     

Determinants of fenhexamid effectiveness against grey mould on grapevine: Respective role of spray timing,fungicide resistance and plant defences

Botrytis bunch rot of grapes is mainly controlled by applying fungicides at three crop growth stages: the end of flowering (BBCH 68), bunch closure (BBCH 77) and the beginning of veraison (BBCH 81). The hydroxyanilide derivative fenhexamid is among the most effective fungicides registered to control Botrytis cinerea. Its effectiveness was examined in relation to spray timing, fungicide resistance and defense responses of grapevine. Overall, the earlier fenhexamid was applied, the more effective it was at controlling B. cinerea. Frequencies of B. cinerea strains which were resistant to fungicides were evaluated at harvest. The frequencies of resistant phenotypes were similar among treatments and years with the exception of a class of multidrug resistant strain (MDR 2) whose frequency appeared to increase after fenhexamid applications. If current spray programs including fenhexamid appear to control bunch rot at the current MDR frequency, a propagation of MDR 2 strains might lead to a decline in disease control. Finally, defense responses were studied in grapevine flowers/berries following fenhexamid application. None of the defense processes tested was induced in flowers/berries at stages 68 and 77. Only an increase in chitinase activity was observed in treated-berries at stage 81, suggesting that fenhexamid effectiveness was not related to a stimulation of defense responses.