Accumulation of Zn, Cd, Cu, and Pb in Chinese cabbage as influenced by climatic conditions under protected cultivation

Accumulation of heavy metals from agricultural soils contaminated by low levels heavy metals has important implications in the understanding of heavy metal contamination in the food chain. Through field experiments (1994-1996), the influence of thermal regime under different treatments on the accumulation of zinc, cadmium, copper, and lead in Chinese cabbage [Brassica pekinensis (Lour) Rupr. cv. Nagaoka 50] grown in a Calcareous Fluvisol (Xerofluvent) in Granada (southern Spain) was examined. Two floating row covers were used: T(1) (perforated polyethylene, 50 microm thick) and T(2) (17 g m(-2) polypropylene nonwoven fleece). An uncovered cultivation (T(0)) served as control. Zn, Cd, Cu, and Pb levels in the whole tops of experimental plants were analyzed. Treatments T(1) and T(2) gave rise to differences in environmental conditions with respect to T(0). The influence of environmental factors manipulated by floating row covers (particularly under T(1)) increased total heavy metal accumulation in the above ground plant biomass with respect to the open-air crop. The total contents of Zn, Cd, Cu, and Pb were 30, 50, 90, and 40% higher in T(1), respectively, than in T(0). This technique could be used in contaminated zones for different plant species because the thermal effect favors the process of phytoextraction and thus reduces the contamination.     

Influence of the timing of nitrogen additions during synthetic grape must fermentations on fermentation kinetics and nitrogen consumption

Nitrogen deficiencies in grape musts are one of the main causes of stuck or sluggish wine fermentations. In the present study, we have supplemented nitrogen-deficient fermentations with a mixture of ammonium and amino acids at various stages throughout the alcoholic fermentation. The timing of the nitrogen additions influenced the biomass yield, the fermentation performance, the patterns of ammonium and amino acid consumption, and the production of secondary metabolites. These nitrogen additions induced a nitrogen-repressed situation in the cells, and this situation determined which nitrogen sources were selected. Glutamine and tryptophan were the main amino acids consumed in all the fermentations. Ammonium is the preferred nitrogen source for biomass production but was hardly consumed when it was added in the final stages of the fermentation. The higher ammonium consumption in some fermentations correlated with a greater synthesis of glycerol, acetate, and acetaldehyde but with a lower synthesis of higher alcohols.     

Bacterial load reduction of live prey for fish larval feeding using Ox-Aquaculture©

Reduction of the bacterial load in live prey is paramount to achieving efficient microbiological control during fish larval rearing. Several methods have been tested using physical and chemical disinfection procedures. Nevertheless, chemicals are difficult to deal with because of the frequent problems encountered when disposing of their residual products and because of the sensitivity of the live prey. Hydrogen peroxide is a good disinfectant that has been used for a long time in other fields of research and decomposes in non‐toxic products. However, it has not been applied for disinfection in aquaculture until recent years. The effects of a hydrogen peroxide‐based product, Ox‐Aquaculture^©, on rotifers and Artemia nauplii survival and on their associated microbial population have been tested in the present study, a disinfection protocol is proposed, and its effects on live prey fatty acids composition after enrichment were checked. More than 80% survival and a 90% reduction of total heterotrophic bacteria and Vibrionaceae were obtained in rotifers exposed for 15 min to 40 mg L^?1 of the product. In the case of Artemia nauplii, 90% survival and 94.5% reduction of heterotrophic bacteria were obtained after 5 min exposure to 8000 mg L^?1 with a further 82.8% reduction of Vibrionaceae. No differences in the fatty acid composition of the live prey were detected after disinfection with hydrogen peroxide. No oxidation of polyunsaturated fatty acids was observed. A short time exposure and easy removal of the product from the treated live prey make hydrogen peroxide an interesting chemical for industrial application.     

Metabolic characterization of tomato fruit during preharvest development, ripening, and postharvest shelf-life

Tomato is an important crop in terms of its economic and nutritional value. Tomato fruit quality is a function of metabolite content, which is prone to physiological changes related to fruit development and ripening. The aim of this work was to use a metabolomic approach to characterize compositional changes (sugars, acids and amino acids) of tomato during preharvest fruit development, ripening, and postharvest shelf-life. Gas chromatography-mass spectrometry was used to identify both polar and volatile metabolites that were involved in fruit development and ripening. Characteristic metabolites for the various fruit developmental stages were identified. Mannose, citramalic, gluconic and keto-l-gulonic acids were shown to be strongly correlated to final postharvest stages. During on-vine ripening, an increase was observed for the major hexoses, glucose and fructose, cell wall components such as galacturonic acid, and for amino acids such as aspartic, glutamic acid and methionine. Major changes were also observed at the level of the TCA cycle, showing a decrease in malic and fumaric acids, and accumulation of citric acid.     

Molecular characterization of Malassezia nana isolates from cats

Malassezia nana (M. nana) is a lipid-dependent yeast that has been isolated from cats and cows. Some sequence variability has been observed in the large subunit (LSU) and internal transcribed spacer (ITS) regions between strains isolated from cats and cows though these regions in M. nana isolates from cats alone have proven to be relatively conserved. In the present study, microsatellite PCR fingerprinting and β-tubulin gene sequence analysis were carried out on M. nana isolates from cats to investigate the genetic diversity of this species. Although a relatively small number of isolates were available, the similarity in the sequences of the β-tubulin and the microsatellite profiles indicate that a particular M. nana genotype colonizes cats. Moreover, all isolates obtained from animals with otitis externa had the same microsatellite fingerprinting pattern. Further studies of a wider population of M. nana isolates from other hosts and status disease are needed to establish that M. nana is a genetically homogeneous species. This is the first report of the characterization of the β-tubulin gene in Malassezia spp.     

Effects of season and body condition on appetite, body mass and body composition in ad libitum fed pony mares

Changes in appetite, body mass (BM), body condition score (BCS), direct (ultrasonographic) and indirect (deuterium oxide dilution technique) measures of body fat were monitored in Welsh Mountain pony mares (n = 11, 5–19 years of age) offered ad libitum access to a complete diet (gross energy 16.9 ± 0.07 MJ/kg dry matter) for 12 weeks during summer (n = 6; 246 ± 20 kg) and winter (n = 5; 219 ± 21 kg). At the outset, each group comprised two thin (BCS 1–3/9), moderate (BCS 4–6/9) and obese (BCS 7–9/9) animals.For ponies that were non-obese at the outset, BM was gained more rapidly (P = 0.001) in summer (0.8 ± 0.1 kg/day) than winter (0.6 ± 0.0 kg/day). This was associated with a seasonal increase in dry matter intake (DMI) which became maximal (summer, 4.6 ± 0.3% BM as DMI/day; winter, 3.5 ± 0.1% BM as DMI/day) during the second month. The appetite of the obese ponies was half that reported for non-obese animals in the summer and BM remained constant irrespective of season.Body ‘fatness’ increased progressively for non-obese but not obese ponies. Body fat content was exponentially associated with increasing BCS but BCSs >6 were not useful indicators of actual body fat. Endogenous circannual mechanisms to suppress winter weight gain were insufficient to prevent the development of obesity in ad libitum fed ponies.     

Effect of diet on chemical composition of rabbits slaughtered at fixed body weights

Four hundred and thirty-two Spanish Giant rabbits were fed 12 diets of variable energy to protein ratio [kcal digestible energy (DE)/g digestible crude protein (DCP)] from weaning to slaughter, both at different ages and weights. Body composition analysis for various chemical components indicated that body weight accounted for the greatest part of the variation in these constituents. Sex influenced only the N content (P less than .05). Dietary E/P accounted for greater variability in body composition than crude protein or crude fiber content of the diet. High dietary E/P increased (P less than .001) the proportion of body fat and reduced the proportion of body protein. This effect was made more obvious by adjustment to equal rate of weight gain and it showed that there may be a greater influence of dietary E/P on body composition than previously recognized.