In vitro solid-state production of Steinernema innovationi with cost analysis

Low-cost mass production of entomopathogenic nematodes (EPNs) is an important prerequisite towards their successful commercialisation. This study evaluated six low-cost solid substrate media for in vitro mass production of Steinernema innovationi. Cost analysis was undertaken and an estimated retail price was calculated. This was then compared to the costs of commercial EPN products currently on the market. The highest yield of infective juveniles (IJs) was obtained from a medium containing a puree of house fly, Musca domestica, larvae?+?0.15?g canola oil, (781,678?±?221 IJs/5?g medium). This medium also had the lowest number of adults remaining in the medium and dead IJs (<10%) at the time of harvest (Day 28). The estimated retail price (R243.27 per 50 million IJs) for S. innovationi produced with our solid culture system was considerably lower than the market price for other Steinernema species products sold by E～nema, BASF corporation, Koppert, BioBest and Natural Insect Control. The production system developed in this study offers a competitive technology to produce EPN products without having to invest in large-scale liquid fermentation equipment, by using a relatively cheap production medium and simple solid culture growing conditions using Erlenmeyer flasks.     

Improvement in the specificity of the silver staining technique for AgNOR-associated acidic proteins in paraffin sections

Some recently developed silver staining methods allow selective staining of acidic nucleolar proteins. Pretreating deparaffinized sections with Schiff's reagent improves the specificity of Goodpasture and Bloom's AgNOR staining (as modified by Kodama et al.) after aldehyde fixation.     

Experimental Assessment of the Water Quality Influence on the Phosphorus Uptake of an Invasive Aquatic Plant: Biological Responses throughout Its Phenological Stage

Understanding how an invasive plant can colonize a large range of environments is still a great challenge in freshwater ecology. For the first time, we assessed the relative importance of four factors on the phosphorus uptake and growth of an invasive macrophyte Elodea nuttallii (Planch.) St. John. This study provided data on its phenotypic plasticity, which is frequently suggested as an important mechanism but remains poorly investigated. The phosphorus uptake of two Elodea nuttallii subpopulations was experimentally studied under contrasting environmental conditions. Plants were sampled in the Rhine floodplain and in the Northern Vosges mountains, and then maintained in aquaria in hard (Rhine) or soft (Vosges) water. Under these conditions, we tested the influence of two trophic states (eutrophic state, 100 μg.l⁻¹ P-PO₄ ³⁻ and hypertrophic state, 300 μg.l⁻¹ P-PO₄ ³⁻) on the P metabolism of plant subpopulations collected at three seasons (winter, spring and summer). Elodea nuttallii was able to absorb high levels of phosphorus through its shoots and enhance its phosphorus uptake, continually, after an increase of the resource availability (hypertrophic > eutrophic). The lowest efficiency in nutrient use was observed in winter, whereas the highest was recorded in spring, what revealed thus a storage strategy which can be beneficial to new shoots. This experiment provided evidence that generally, the water trophic state is the main factor governing P uptake, and the mineral status (softwater > hardwater) of the stream water is the second main factor. The phenological stage appeared to be a confounding factor to P level in water. Nonetheless, phenology played a role in P turnover in the plant. Finally, phenotypic plasticity allows both subpopulations to adapt to a changing environment.     

Phylogeography of a game species: the red-crested pochard (Netta rufina) and consequences for its management

Western European populations of red-crested pochard (Netta rufina) are characterized by low size and high fragmentation, which accentuate their sensitivity to hunting. Uncertainties regarding the demographic trends of these populations highlight the need for pertinent hunting regulations. This requires identification of the limits of the populations under exploitation, i.e. delimiting a management unit. We used the left domain of the mitochondrial control region and seven nuclear loci (four microsatellites and three introns) to assess the level of genetic structure and demographic independence between the fragmented Western European and the large Central Asian populations. The second objective was to investigate the colonization history of the Western European populations. This study demonstrated that the Western European populations of red-crested pochard constitute a separate demographic conservation unit relative to the Asian population as a result of very low female dispersal (mitochondrial DNA: PhiST = 0.152). A morphometric analysis further suggested that Central Asian and Western European specimens of both sexes originate from different pools of individuals. Male dispersal seems higher than female dispersal, as suggested by the lack of clear genetic structure for the nuclear markers at this continental scale. Genetic data, in conjunction with historical demographic data, indicate that the current Western European populations probably originate from a recent colonization from Central Asia. As numbers of red-crested pochards in Western Europe cannot be efficiently supplemented by immigration from the larger Asian populations, a management plan regulating the harvest in Western Europe is required.     

Short-term changes in the mesozooplanktonic community in theSeine ROFI (Region of Freshwater Influence)(eastern English Channel)

Discrete-depth, hourly mesozooplankton samples were collectedover a 92 h period in May 1992 at an anchor station within theSeine Region of Freshwater Influence (ROFI) (English Channel).The mesozooplankton community defined as a euryhaline marineassemblage was dominated by the calanoid copepods Acartia spp.,Temora longicornis and Centropages hamatus, the cladoceran Evadnenordmanni and the appendicularian Oikopleura dioica. The semi-diurnaltidal current was the dominant factor in determining the short-termtemporal changes in the community in terms of density and speciescomposition so that zooplankton patches displayed oscillatingmotion in relation to tidal advection. Although a few species(e.g. Pleurobrachia pileus) exhibited higher densities aroundlow tide, maximum densities were observed for most species (e.g.T.longicornis and E.nordmanni) around high tide, according tosalinity variations. Diurnal changes were only reported forcyclopoid copepods (i.e. Halicyclops sp. and Cyclopina sp.)which wer$$$ mainly endobenthic during the day and moved intothe water column at night. Besides temporal changes in depth-averageddensities, most species exhibited vertical migrations at dieland/or tidal periods. Tidal vertical migrations were reportedonly for a few taxa and could be the result of passive mechanisms(e.g. vertical mixing) rather than of active behaviour. Dielvertical migrations were observed in most of the abundant taxa.While this migration pattern did not appear to be an adaptationto predator avoidance within the Seine ROFI, it could regulatehorizontal transport of organisms and promote their retention.The consequences of the short-term mesozooplankton fluctuationsfor sampling designs are discussed.     

Immunological method for direct assessment of the functionality of a denitrifying strain of Pseudomonas fluorescens in soil

This work describes an immunological method for detection and quantification in complex environments of the dissimilative nitrate reductase (NRA) responsible for the reduction of nitrate to nitrite, which plays an important role in ecosystem functioning. The alpha-catalytic subunit of the enzyme was purified from the denitrifying strain Pseudomonas fluorescens YT101 and used for the production of polyclonal antibodies. These antibodies were used to detect and quantify the NRA by a chemifluorescence technique on Western blots after separation of total proteins from pure cultures and soil samples. The specificity, detection threshold and reproducibility of the proposed method were evaluated. A soil experiment showed that our method can be applied to complex environmental samples.     

Occurrence of Listeria spp. in effluents of French urban wastewater treatment plants

Listeria spp. were found in most treated waters (84.4%) and raw sludge (89.2%) of six French urban wastewater treatment plants and one composting facility, examined monthly over a 1-year period. Most strains belonged to Listeria monocytogenes, serotypes 4b/4e being predominant. Sludge composting and liming reduced or prevented Listeria contamination.     

Unique ganglioside binding by botulinum neurotoxins C and D-SA

The botulinum neurotoxins (BoNTs) are the most potent protein toxins for humans. There are seven serotypes of BoNTs (A-G), based on a lack of cross-antiserum neutralization. The BoNT/C and BoNT/D serotypes include mosaic toxins that are organized as D-C and C-D toxins. One BoNT D-C mosaic toxin, BoNT/D-South Africa (BoNT/D-SA), was not fully neutralized by immunization with a vaccine composed of either prototype BoNT/C-Stockholm or BoNT/D-1873. Whereas several BoNT serotypes utilize dual receptors (gangliosides and proteins) to bind to and enter neurons, the basis for BoNT/C and BoNT/D entry into neurons is less well understood. Recent studies solved the crystal structures of the receptor-binding domains of BoNT/C, BoNT/D, and BoNT/D-SA. Comparative structural analysis showed that BoNT/C, BoNT/D and BoNT/D-SA lacked components of the ganglioside-binding pocket that exists within other BoNT serotypes. With the use of structure-based alignments, biochemical analyses, and cell-binding approaches, BoNT/C and BoNT/D-SA have been shown to possess a unique ganglioside-binding domain, the ganglioside-binding loop. Defining how BoNTs enter host cells provides insights towards understanding the evolution and extending the potential therapeutic and immunological values of the BoNT serotypes.