Link between Domoic Acid Production and Cell Physiology after Exchange of Bacterial Communities between Toxic Pseudo-nitzschia multiseries and Non-Toxic Pseudo-nitzschia delicatissima

Bacteria are known to influence domoic acid (DA) production by Pseudo-nitzschia spp., but the link between DA production and physiology of diatoms requires more investigation. We compared a toxic P. multiseries to a non-toxic P. delicatissima, investigating links between DA production, physiological parameters, and co-occurring bacteria. Bacterial communities in cultures of both species were reduced by antibiotic treatment, and each of the diatoms was inoculated with the bacterial community of the other species. The physiology of P. delicatissima was minimally affected by the absence of bacteria or the presence of alien bacteria, and no DA was detected. P. multiseries grew faster without bacteria, did not produce a significant amount of DA, and exhibited physiological characteristics of healthy cells. When grown with alien bacteria, P. multiseries did not grow and produced more DA; the physiology of these cells was affected, with decreases in chlorophyll content and photosynthetic efficiency, an increase in esterase activity, and almost 50% mortality of the cells. The alien bacterial community had morphological and cellular characteristics very different from the original bacteria, and the number of free-living bacteria per algal cell was much higher, suggesting the involvement of bacteria in DA production.     

Surrogate Correlations and Near-Infrared Diffuse Reflectance Sensing of Trace Metal Content in Soils

Near-infrared diffuse reflectance sensing (NIRS) of soils has been the object of considerable interest and research in the last few years. This has been motivated by the prospect that this method seems to provide a cheap, convenient alternative to conventional, time-consuming methods for the measurement of a wide range of soil parameters. In particular, various authors have advocated that NIRS could be used to measure rapidly and non-destructively the concentration of trace metals in surface soils. Correlation analyses between NIRS spectra and trace metal concentration have yielded inconclusive results to date, suggesting that trace metal concentration may belong to a class of “tertiary” soil parameters, linked to NIRS spectra through “surrogate”, or indirect, correlations, involving some other primary or secondary parameter like clay or organic matter content, to which NIRS spectra are very sensitive. To assess the validity of this surrogate correlation hypothesis in the case of trace metals, experiments were carried out with soil samples varying only in the amount of trace metals they contain. Field-aged Hudson and Arkport soil pots spiked with Cu and Zn, freshly spiked samples of the same soils, and samples of a metalliferous peat soil from Western New York naturally rich in Cd and Zn were subjected to NIRS under laboratory conditions. Detailed analysis indicates that the NIR spectrum is sensitive to sample handling, including the orientation of the samples in the NIRS instrument, but that, at the same time, there is no discernable effect of the presence of trace metals on any part of the NIR spectrum. These results provide strong experimental support to the hypothesis of “surrogate” correlation for trace metals, and indicate that trace metals, even in severely contaminated soils, should not interfere with the NIR sensing of primary or secondary parameters, like organic matter content. Further work is needed to determine if this feature of NIR spectra extends to other soil chemical parameters.     

Changes during winter in water‐stable aggregation due to crop residue quality

There is a need to develop practices that contribute to increased water‐stable aggregation (WSA) during winter in a humid temperate climate when soil is particularly prone to water erosion. Our objectives were to determine the effects of crop residue quality on WSA during winter and to relate these effects to biochemical indicators of fungal and bacterial biomass. Three graminae crop residues were selected for their different C/N ratios and biochemical characteristics (green oat residues, C/N = 18.8; wheat straw, C/N = 125.6; and mature miscanthus residues, C/N = 311.3). In October 2009, crop residues were added with an equivalent amount of C in the 0–10 cm layer to a Luvisol in north‐west France. WSA, expressed as mean weight diameter (MWD), amino sugar, soil mineral N and water contents were measured at regular intervals during 5 months. Aggregate MWD of the control soil decreased rapidly and remained low until the last sampling date in March which illustrates the structural vulnerability of bare soils in winter in this pedo‐climatic area. The incorporation of all three crop residues had significant positive impacts on aggregate MWD. Despite widely different C/N ratios, the maximum MWD under each treatment was similar (three times greater than the control soil). Maximum MWD occurred at times that clearly depended on residue quality. Maximum values occurred early for green oat (29 day), but were delayed to 50 day for wheat straw and to 154 day for miscanthus. Results from correlation analysis suggest that variations in WSA were partly mediated by microbial agents with a dominant effect of bacteria for green oat and a combined role of fungal and bacterial biomass for wheat straw. We suggest that the maximum MWD associated with the miscanthus late in the experiment is related to changes in the composition of the fungal community. Overall, our study shows that autumn application of crop residues increases WSA during winter with its effect being microbially mediated and determined by residue quality.     

Assessment of yocoboue wild oil palm (Elaeis guineensis Jacq.) from Côte d'Ivoire

Following a survey involving wild oil palm groves in Côte d’Ivoire as a whole in 1968, 17 parents were chosen at Yocoboué (southernCôte d’Ivoire). Agronomic performance of the 17 parents was assessed through Deli × Yocoboué hybrids in 3 trials grown at La Mé (Côte d’Ivoire), Mondoni and La Dibamba (Cameroon).When compared to the Deli × La Mé progenies used as controls, the Deli × Yocoboué hybrids produced 91% for total bunch weight and86% for oil yields. However, the genetic variability within the Deli × Yocoboué progenies allows to select individual progenies as productive as the Deli × La Mé controls, for breeding purposes. A study of major agronomic traits led to the choice of parent YO 11 T , which combines the largest number of favourable traits. On average, Deli × Yocobouéprogenies have slower vertical growth and are susceptible to Fusarium wilt, except 2 parents (YO 3 T and YO 9 T), which seem to be resistant.     

Detection of linkage between RFLP markers and genes affecting anthocyanin pigmentation in maize (Zea mays L.)

Summary Linkages between molecular markers and genes involved in the expression of agronomical traits have already been described in all of the major crops. In most cases, the genetic model underlying the Quantitative Traits Loci (QTL) is discussed. Here, Restriction Fragment Length Polymorphisms (RFLPs) and Mapmaker-QTL have been used to pinpoint seven regions of the genome significantly correlated with four pigmentation qualitative traits of maize (Zea mays L.). Two of these, located on chromosomes 2 and 10, explain most of the variation of these traits. The R and B gene loci known to be involved in the regulation of the anthocyanin pathway map to the same regions and we suggest that these loci could be the candidate genes involved in the correlations detected with RFLPs. This type of result is in accordance with the hypothesis of the candidate gene which supposes that, if we have a very high density map of randomly-selected cDNA clones, it should theoretically be possible to associate a cloned genic sequence with a phenotypic trait where correlations are found.     

Kinetics of formation and functional properties of conjugates prepared by dry-state incubation of beta-lactoglobulin/acacia gum electrostatic complexes

The formation of conjugates between beta-lactoglobulin and acacia gum based on electrostatic complexes formed at pH 4.2 was investigated upon dry-state incubation for up to 14 days at 60 degrees C and 79% relative humidity (RH). By means of SEC-HPLC and RP-HPLC, it was shown that the beta-lactoglobulin incubated alone was able to form polymers with molecular masses higher than 200 kDa until 50% of the initial monomeric protein disappeared after 14 days. In the presence of acacia gum at initial protein to polysaccharide weight mixing ratios of 2:1 and 1:2, only 35% of the initial beta-lactoglobulin monomers disappeared after 14 days. Using RP-HPLC, an apparent reaction order of 2 was found for the disappearance of monomeric beta-lactoglobulin both in the presence or absence of acacia gum. However, the reaction rate was faster in the absence of acacia gum. SDS-PAGE electrophoresis with silver staining confirmed the formation of beta-lactoglobulin/acacia gum conjugates. The solubility curves of the incubated beta-lactoglobulin showed a minimum around pH 4-5. By contrast, the minimum of solubility of the beta-lactoglobulin/acacia gum incubated mixtures shifted to lower pH values compared to initial mixtures. The conjugates exhibited higher foam capacity than the incubated protein as well as lower equilibrium air/water surface tension. Conjugation at ratio 1:2 led to increased interfacial viscosity (300 mN s m(-1) at 0.01 Hz) compared to beta-lactoglobulin alone (100 mN s m(-1) at 0.01 Hz), but similar interfacial elasticity (30-40 mN m(-1)). The foam capacity of the conjugates was significantly higher than that of the incubated beta-lactoglobulin as well as foam expansion and drainage time, especially at pH 5.3, i.e., higher than the pH of formation of the conjugates.     

Variability of the polyphenolic composition of cider apple (Malus domestica) fruits and juices

Five French cider apple varieties were compared on the basis of their detailed polyphenol profile in the cortex and in the juices. Among the factors studied, variety was the most important variability factor in fruits, whereas polyphenol profiles showed an overall stability from one year to another, and a limited decrease of polyphenol concentration was observed during the starch regression period of fruit maturation. In juices, procyanidins remained the preponderant polyphenol class with concentrations up to 2.4 g/L even in centrifuged juices. Compared to the fruits, the average degree of polymerization of procyanidins was significantly reduced in the juice. Centrifugation of the crude juice had only minor effects on the polyphenol composition. For one variety, highly polymerized procyanidins with average degrees of polymerization of 25 were shown to be soluble in the centrifuged juice at a concentration of close to 1.2 g/L. Oxygenation of the juices during processing resulted in a significant decrease of all classes of native polyphenols. Catechins and procyanidins were particularly affected by oxidation, whereas caffeoylquinic acid was partly preserved. The transfer of polyphenols after pressing was maximal for dihydrochalcones and minimal for procyanidins with extraction yield values close to 80 and 30%, respectively.     

Conservation management for Orthoptera in the Dadia reserve, Greece

The diversity patterns, the ecological structure and the typical species of the orthopteran assemblage in the Dadia reserve are investigated. The reserve was designed to protect the black vulture (Aegypius monachus) and other raptors. A total of 39 orthopteran species were found, including Paranocarodes chopardi, a pamphagid species with very restricted distribution. All species can be represented in a network of six complementary habitats, including open oak woodlands, agricultural fields separated with hedges, humid grasslands, as well as serpentine grasslands. The buffer zone of the reserve is far more important for Orthoptera conservation than the core areas, which host most of the black vulture nests. Management focusing on raptors is in general compatible with conservation of Orthoptera. We suggest the maintenance of forest openings in the buffer zone, the maintenance of forest heterogeneity, the enhancement of periodical livestock grazing, and the use of nine indicator species and Paranocarodes chopardi in the reserve monitoring program.     

The effect of water movement on the transport of dicyandiamide,ammonium and urea in unsaturated soils

A laboratory experiment was conducted to investigate the relative mobility of dicyandiamide (DCD) and jointly applied ammoniacal salts or urea in three different soils of lower Egypt, and to determine the extent to which DCD separates from N-fertilizer in unsaturated soil undergoing leaching. The experimental results suggest that, under conditions of water flow, DCD is readily separated from NH₄⁺ but parts from urea to a far lesser extent. The large difference in mobility between DCD and NH₄⁺ should severely limit the effectiveness of DCD as a nitrification inhibitor in the three soils considered when applied in conjunction with ammoniacal salts. In two out of three cases, the situation is similarly unfavorable in the case of joint DCD and urea application. However, the observation that DCD, in a low CEC sandy loam, moves within the soil solution at a slightly lower rate than urea suggests that joint application with urea would keep at least part of the DCD in contact with the NH₄⁺ ions and, therefore, would preserve some of the effectiveness of DCD under leaching conditions in this soil.