Influence of ingredients on the self-diffusion of aroma compounds in a model fruit preparation: an nuclear magnetic resonance-diffusion-ordered spectroscopy investigation

Diffusion-ordered spectroscopy (DOSY)-pulsed field gradient (PGF) nuclear magnetic resonance (NMR) spectroscopy was used to measure self-diffusion coefficients of aroma molecules in model fruit preparations. The impact of the sucrose content on aroma diffusion was specifically investigated, and the relationship with viscosity, water activity, and dry matter parameters was evidenced. DOSY-PGF NMR spectroscopy was found to be a relevant and accurate technique to follow self-diffusion of aroma compounds at low concentrations in a complex food matrix and to obtain information on diffusion of the sucrose and of the water molecules. We showed that aroma self-diffusion was strongly decreased in fruit preparation because of the high sucrose content, which induces the formation of a network through hydrogen bonds with water. Self-diffusion coefficients were determined for aroma molecules of different natures, and values are related to the physicochemical properties of the molecule.     

Fish responses to acidity in Québec lakes: A review

To establish the impact of acidity on fish populations,studies were conducted in 37 Québec lakes located in four regions; the réserve des Laurentides and Portneuf and the Charlevoix and Témiscamingue regions. Density (catch per unit effort) of brook chary (Salvelinus fontinalis) decreases with increasing acidity. Moreover, in the Charlevoix region, this species has disappeared from three acid lakes (4.6 ?pH?5.l) with low Ca levels. Unlike growth, condition demonstrates a close relationship to acidity in brook charr populations. The total Al concentration in gills decreases with increasing size and pH. Lake acidity and sensitivity to acidification introduces problems in gamefish management. A survey of 17 lakes of the Témiscamingue region reveals that species diversity and total fish biomass are much lower in acid lakes than non acid lakes. In addition, two acid lakes are devoid of fish. Cyprinidae and Johnny darters (Etheostoma nigrum) are abundant in lakes with a pH level of 5.9 to 7.0 but are absent in lakes with a pH lower than 5.2. The yellow perch (Perca flavescens) is the only fish that appears to be tolerant to a wide pH range. This species, however, is in poor condition in acid lakes as compared with non acid lakes.     

Identification of nosiheptide in feeds and detection of residues in animal tissues

Nosiheptic is determined in fermentation broths of Streptomyces actuosus either by a microbiological method using Staphylococcus aureus or, more easily, by an automated colorimetric method. The results obtained with both methods correspond well for concentrations greater than 100 microgram/mL with a standard deviation of 1-3%. For determination of nosiheptide as a feed additive, the microbiological assay is made more specific by pretreatment with petroleum ether and 1N HCl. Standard deviation is less than 4%, and the assay is sensitive to 1 ppm. Nosiheptide is identified in feed containing other frequently used antibiotics by thin layer chromatography with bioautography; sensitivity is 1 ppm. The absence of traces of nosiheptide in tissues of treated swine and broiler is confirmed by microbiological diffusion, sensitive to 0.025 ppm.     

Thermal stability of soil organic matter pools and their δC values after C3-C4 vegetation change

Carbon isotopic composition of soils subjected to C₃-C₄ vegetation change is a suitable tool for the estimation of C turnover in soil organic matter (SOM) pools. We hypothesized that the biological availability of SOM pools is inversely proportional to their thermal stability. Soil samples from a field plot with 10.5 years of cultivation of the C₄ plant Miscanthus×gigantheus and from a reference plot under C₃ grassland vegetation were analysed by thermogravimetry coupled with differential scanning calorimetry (TG-DSC). According to differential weight losses (dTG) and energy release or consumption (DSC), five SOM pools with increasing thermal stability were distinguished: (I) 20-190 °C, (II) 190-310 °C, (III) 310-390 °C, (IV) 390-480 °C, and (V) 480-1000 °C. Their δ¹³C values were analysed by EA-IRMS. The weight losses in pool I were connected with water evaporation, since no significant C losses were measured and δ¹³C values remained unchanged. The δ¹³C of pools II and III in soil samples under Miscanthus were closer to the δ¹³C of the Miscanthus plant tissues (−11.8‰) compared to the thermally stable SOM pool V (−19.5‰). The portion of the Miscanthus-derived C₄-C in total SOM in 0-5 cm reached 55.4% in the 10.5 years. The C₄-C contribution in pool II was 60% and decreased down to 6% in pool V. The mean residence times (MRT) of SOM pools II, III, and IV were similar (11.6, 12.2, and 15.4 years, respectively), while pool V had a MRT of 163 years. Therefore, we concluded that the biological availability of thermal labile SOM pools (<480 °C) was higher, than that of the thermal stable pool decomposed above 480 °C. However, the increase of SOM stability with rising temperature was not gradual. Therefore, the applicability of the TG-DSC for the separation of SOM pools with different biological availability is limited.     

Warming increases tolerance of an insect pest to fungicide exposure through temperature-mediated hormesis

Pest management strategies relying on agrochemicals could be altered by climate change, because of the temperature-dependent toxicity of the compound involved. Many studies have explored the response of targeted pests to pesticide and temperature. Pesticides are seldom strictly selective and also affect nontarget pests. Surprisingly, the way temperature may shape these side effects of pesticides remains overlooked, limiting our understanding of the net impacts of future chemical treatments on the overall damage induced by different pests. We investigated how temperature modulates the response of a major grape insect pest (the tortricid moth Lobesia botrana) to a copper-based fungicide. We examined the lethal (larval survival) and sublethal (larval development, pupal mass, immune parameters) effects of exposure to different concentrations of copper in larval food. We found that copper concentration had negative linear effects on larval development and pupal mass. In addition, copper concentration had biphasic curvilinear effects on total phenoloxidase activity, which is indicative of hormesis (stimulation and inhibition of insect performance at low and high copper concentrations, respectively). Temperature stimulated development, while compromising immunity (total phenoloxidase activity). Significant interaction between copper concentration and temperature was detected for larval survival and phenoloxidase activity: warmer conditions improved pest tolerance to copper through temperature-driven hormesis (larval survival) or by shifting the hormesis-related peak of performance toward higher copper concentrations (phenoloxidase activity). This combination of simple and interactive effects could propagate to populations, communities and agroecosystem, with implications for future management of viticultural pests.

     

Experimental infection of Pacific oyster Crassostrea gigas spat by ostreid herpesvirus 1: demonstration of oyster spat susceptibility

ABSTRACT: In 2008 and 2009, acute mortalities occurred in France among Pacific cupped oyster, Crassostrea gigas, spat. Different hypothesis including the implication of environmental factors, toxic algae and/or pathogens have been explored. Diagnostic tests indicated that OsHV-1 including a particular genotype, termed OsHV-1 μVar, was detected in most of samples and especially in moribund oysters with the highlighting of virus particles looking like herpes viruses by TEM examination. In this study, an experimental protocol to reproduce OsHV-1 infection in laboratory conditions was developed. This protocol was based on the intramuscular injection of filtered (0.22 μm) tissue homogenates prepared from naturally OsHV-1 infected spat collected on French coasts during mortality outbreaks in 2008. Results of the experimental trials showed that mortalities were induced after injection. Moreover, filtered tissue homogenates induced mortalities whereas the same tissue homogenates exposed to an ultraviolet (UV) treatment did not induce any mortality suggesting that oyster spat mortalities require the presence of a UV sensitive agent. Furthermore, analysis of injected oyster spat revealed the detection of high amounts of OsHV-1 DNA by real-time quantitative PCR. Finally, TEM analysis demonstrated the presence of herpes virus particles. The developed protocol allowed to maintain sources of infective virus which can be useful for the development of further studies concerning the transmission and the development of OsHV-1 infection.     

Measurements of canine aqueous humor inflammatory mediators and the effect of carprofen following anterior chamber paracentesis

Objectives Phase I: To evaluate levels of prostaglandin E₂ (PGE₂), nitrites and nitrates (NO_x), tumor necrosis factor‐alpha (TNF‐α) and expression of inducible cyclo‐oxygenase (COX‐2), nitric oxide synthase (NOS‐2), and matrix metalloproteinases (MMP‐3 and ‐9) in canine aqueous humor following repeated anterior chamber paracenteses (ACP). Phase II: to evaluate the effect of carprofen on PGE₂, NO_x, and TNF‐α in canine aqueous humor following ACP. Animals studied Four beagles in phase I and 8 beagles in phase II. Procedures Phase I: ACP was performed at time (T) 0, 4 and 8 h. Phase II: A randomized, placebo‐controlled cross‐over design with four dogs per group where carprofen was given 4.4 mg/kg/day on day (D) 1, 2 and 3. ACP was performed at T0 and T1.5 on D3. Statistical analysis was performed with repeated measures anova and post hoc Tukey‐Kramer multiple‐comparison procedure. In phase II, TNF‐α level was analyzed with a Wilcoxon signed‐rank test. Results Phase I: PGE₂ significantly increased (P < 0.0001) to plateau at T4. NO_X was decreased at T4 (P < 0.06), but increased at T8 (P < 0.0001). COX‐2 showed detectable expression only at T8. TNF‐α, NOS‐2, MMP‐3 and ‐9 were undetectable at all time points. Phase II: At T1.5, PGE₂ was significantly elevated in both groups but was lower in the carprofen group (P = 0.037). NO_x and TNF‐α did not statistically increase in either group. Conclusions Following ACP, significant increases in PGE₂ levels confirmed inflammation characterized by a rise of COX‐2. The NO_x pathway took longer to induce as compared with PGE₂. Carprofen decreased PGE₂ levels and could help control intraocular inflammation.     

The genetic control of seed quality traits: effects of allelic variation at the Tri and Vc-2 genetic loci in Pisum sativum L.

Genetic variation at the Tri locus, controlling seed trypsin inhibitor activity, is relevant to both food and feed uses of Pisum sativum L. (pea). Near-isogenic lines of Pisum sativum L. (pea) were developed previously to examine the impact on digestibility of variation at Tri on linkage group V. Further studies of these lines have now revealed a significant difference in seed nitrogen concentration between near-isolines having contrasting seed trypsin inhibitor activity. In order to investigate this apparent association, the multiple genes at a closely linked locus, Vc-2, encoding a set of major vicilin polypeptides, were analysed and shown to differ between the near-isolines. Characterisation of Vc-2 cDNAs revealed distinguishing features of the functional genes between the parents of the near-isolines, while analyses of gene structure showed that a disrupted variant Vc-2 gene was present in one, but not the second, parent of the near-isolines. The variant gene appeared to be non-functional, based both on its deduced truncated protein lacking part of one conserved cupin structural domain, and the fact that it did not correspond to any isolated cDNA. Recombinant near-isolines were generated between the closely linked Tri and Vc-2 loci to investigate the genetic association with seed nitrogen concentration. Seeds from near-isolines and recombinant inbred lines where the variant Vc-2 gene was present had lower seed nitrogen concentration than lines lacking the variant gene. Furthermore, the disrupted Vc-2 gene was absent from several pea genotypes with high seed protein content. Expression analyses suggested that gene expression at the Vc-2 locus was higher when the non-functional gene variant was absent. Markers based either on the element which disrupts the coding sequence within the variant gene at the Vc-2 locus, or on the closely linked Tri locus, may be exploited in the selection of haplotypes associated with genetic variation in seed protein composition and concentration. The gene content in the genomic region of Medicago truncatula chromosome 7 that is syntenic with the pea linkage group V has identified further candidates for functional analyses and marker assisted selection.     

Characterization of a noncytopathic HIV-2 strain with unusual effects on CD4 expression

A new isolate of the human immunodeficiency virus type 2, designated HIV-2UC1, was recovered from an Ivory Coast patient with normal lymphocyte numbers who died with neurologic symptoms. Like some HIV-1 isolates, HIV-2UC1 grows rapidly to high titers in human peripheral blood lymphocytes and macrophages and has a differential ability to productively infect established human cell lines of lymphocytic and monocytic origin. Moreover, infection with this isolate also appears to involve the CD4 antigen. However, unlike other HIV isolates, HIV-2UC1 does not cause cytopathic effects in susceptible T cells nor does it lead to loss of CD4 antigen expression on the cell surface. These results indicate that HIV-2 may be found in individuals with neurologic symptoms and that the biological characteristics of this heterogeneous subgroup can differ from those typical of HIV-1.