Increased Postharvest Life of TomLox B Silenced Mutants of Tomato (<Emphasis Type="Italic">Solanum lycopersicum</Emphasis>) Var. TA234

A healthy lifestyle includes fruits and vegetables consumption. Tomato is one of the most consumed vegetables, although it is susceptible to physical damage through postharvest handling, thus leading to important losses. Softening is an important variable during tomato ripening; excessive softening is undesirable and leads to postharvest losses. TomloxB plays an important role in ripening, mainly in the loss of cellular integrity caused by fatty acids released from the lipid matrix of membranes that initiate oxidative deterioration, which is in turn carried into senescence. In order to increase postharvest life, we produced transgenic tomato plants via Rhizobium radiobacter with tomato lipoxygenase B (TomloxB) antisense constructs under control of the cauliflower mosaic virus (CaMV) 35S promoter. Lipoxygenase activity and firmness were measured in tomato fruit and the fatty acids profile was determined. Transgenic fruits were maintained for 40 days at room temperature in optimal conditions, whereas wild type fruits remained in similar conditions for only six days. Firmness in pink and red stages was significantly lower in wild type fruits than in two transgenic lines. Linolenic acid was the most important fatty acid consumed by lipoxygenase in both turning and pink stages of ripening. Lipoxygenase activity was smaller in transformed fruits in comparison with the wild type. These results suggest that silencing the TomloxB gene promoted significant changes in the physiology of transformed tomatoes, being the increase in postharvest life the most important.     

Characterization of digestive enzymes protease and alpha‐amylase activities in the thick‐lipped grey mullet (Chelon labrosus,Risso 1827)

Activities of pepsin, trypsin, chymotrypsin, alpha‐amylase and lipase, as well as their optima and stability to pH and temperature, were determined in digestive extracts of thick‐lipped grey mullet, Chelon labrosus, of three different sizes: Group 1 (45.2 ± 3.0 g), Group 2 (180.9 ± 4.2 g), and Group 3 (328.5 ± 43.3 g). SDS‐PAGE zymograms were also used to assess the role of serine proteases in the digestive tract of C. labrosus. On the other hand, possible changes in the digestive enzyme profile of C. labrosus during development were observed, with a comparatively lower pepsin activity, higher activities of alkaline proteases and alpha‐amylase and no lipase activity recorded in pre‐adult specimens. It is suggested that these variations are linked to the changes in diet composition with age, moving from a partly carnivorous to a more herbivorous feeding habit.     

Effects of supplementation of decapod zoea to Artemia basal diet on fatty acid composition and digestive gland histology in common octopus (Octopus vulgaris) paralarvae

The present study aimed to evaluate the effect of the supplementation of different crab zoeas to enriched Artemia basal diet for Octopus vulgaris paralarvae during the first month of life. Paralarvae were fed using enriched Artemia nauplii alone and Artemia co‐fed either first zoea stages of Grapsus adscensionis or Plagusia depressa. The experiment was carried out over a period of 28 days, in 0.12 m³ tanks with a flow‐through rearing system. Growth in dry weight as well as mantle length and width were assessed weekly. Additionally, prey and paralarvae fatty acid composition and digestive gland (DG) histology were evaluated. Addition of low amounts of crab zoeas (approx. 100 indv. L^?1 day^?1) provided during critical life stages of O. vulgaris proved to be good enough to improve paralarvae growth and survival in comparison with those fed exclusively on enriched Artemia. These results were supported by the finding of a higher number of glycoprotein absorption vacuoles in the DG from paralarvae co‐fed crab zoeas, suggesting a higher feeding activity. In addition, fatty acid analysis of crab zoea showed that these are good sources of dietary arachidonic and eicosapentaenoic acids during the octopus planktonic life stage, whereas the low docosahexaenoic (DHA) content suggests the use of additional DHA sources or higher zoea densities to meet paralarvae nutritional demand to carry out a successful metamorphosis to benthic life.     

Importance of the relative levels of dietary arachidonic acid and eicosapentaenoic acid for culture performance of gilthead seabream (Sparus aurata) larvae

The effect of different arachidonic acid (ARA) dietary contents at several dietary eicosapentaenoic acid (EPA) levels on the growth, survival and biochemical composition of gilthead seabream larvae was studied to better define the importance of this fatty acid as a function of EPA. Larvae of 18 days were fed one of the five isonitrogenous and isolipidic microdiets with three different EPA (0.3%, 2% and 4%) and ARA amounts (0.1%, 0.6% and 1.2%). Although a dietary increase in either ARA or EPA alone did not improve survival significantly, the increase in both fatty acids significantly enhanced growth and survival, suggesting an optimum dietary value of EPA:ARA close to 4:1.2. Dietary ARA was more efficiently incorporated into larval tissues than EPA. Increased dietary EPA or ARA contents reduced the incorporation of ARA or EPA into larval lipids, indicating their competition as substrates for different enzymes. The possible negative effect of further elevation of dietary ARA and its competition with EPA for phospholipids synthesis deserves further studies in marine fish larvae.     

Efficacy of tricaine methanesulphonate and clove oil as anaesthetics for juvenile cobia Rachycentron canadum

Six experiments were designed to determine the optimal anaesthetic dosage of tricaine methanesulphonate (TMS) and clove oil that could be used safely on juvenile cobia Rachycentron canadum of two sizes [G1=4.9±0.8 g; G2=13.9±3.1 g]. We documented the stage of anaesthesia and the acute toxicity as 96 h LC₅₀ (lethal concentration 50% population) at various exposure times of the two anaesthetics. At 10 min induction time, the TMS 96 h LC₅₀ was 93.9 mg L⁻¹ in G1 and 97.0 mg L⁻¹ in G2. Compared with clove oil, the 96 h LC₅₀ was 60.0 mg L⁻¹ in G1 and 69.8 mg L⁻¹ in G2. The difference between the two groups (G1, G2) did not influence anaesthesia safety ( P >0.05). Rachycentron canadum achieved stage 3 anaesthesia more rapidly at a lower clove oil concentration level (40 mg L⁻¹, 10 min) than TMS (60 mg L⁻¹, 10 min), but the recovery period of clove oil, was significantly longer. Clove oil was the most effective in reducing the short-term stress induced by routine biometry (20 mg L⁻¹, 10 min) and also by transporting (1 mg L⁻¹, 8 h). Whereas, for long-term exposure, 40 mg L⁻¹ TMS was found to be safe.     

Influence of temperature on the volatilization of triallate and terbutryn from two soils

The rate of volatilization of the formulated herbicides triallate and terbutryn was studied in a volatilization chamber under controlled laboratory conditions using two soils with sand and loam textures, respectively. The influence of the most relevant experimental variables was investigated by measuring the amount of volatilized herbicides after their incorporation to the soils. The effect of soil temperature was studied in the range from 5 °C to 25 °C. Initial soil water content was fixed at field capacity depending on the physical characteristics of each soil. The volatilized herbicide was trapped in C18 cartridges during different time intervals and analyzed by HPLC. The volatilization losses for triallate ranged from 7 to 58%, whereas the losses for terbutryn ranged from 1 to 6%. Sorption and volatilization resulted in two coupled effects of major importance in these experiments: the sorption process was favoured as temperature decreased, whereas volatilization increased as temperature increased. © 2000 Society of Chemical Industry     

Application of multivariate analysis and artificial neural networks for the differentiation of red wines from the Canary Islands according to the island of origin

Eleven metals (K, Na, Ca, Mg, Fe, Cu, Zn, Mn, Sr, Li, and Rb) were determined in 83 red wines from the Canary Islands. The wines presented high concentrations of Na, and the concentrations of Cu and Zn were much lower than the maximum concentrations established by the International Office of Vine and Wine (OIV). Applying principal component analysis, the dimension space was reduced to five principal components that explain 76.4% of the total variance, and the wines tend to separate on the basis of the island of production. Linear discriminant analysis (LDA) allowed a reasonable classification of wines according to the island of production. When artificial neural networks (Kohonen self-organizing maps and back-propagation feed-forward as unsupervised and supervised techniques, respectively) were applied on the matrix of data constituted by the analyzed metals, the results improved in relation to those obtained by other multivariate methods observing a differentiation of wines according to island of production.     

Statistical validation of the identification of tuna species: bootstrap analysis of mitochondrial DNA sequences

Sequencing of the mitochondrial cytochrome b gene has been used to differentiate three tuna species: Thunnus albacares (yellowfin tuna), Thunnus obesus (bigeye tuna), and Katsuwonus pelamis (skipjack). A PCR amplified 528 bp fragment from 30 frozen samples and a 171 bp fragment from 26 canned samples of the three species were analyzed to determine the intraspecific variation and the positions with diagnostic value. Polymorphic sites between the species that did not present intraspecific variation were given a diagnostic value. The genetic distance between the sequences was calculated, and a phylogenetic tree was constructed, showing that the sequences belonging to the same species clustered together. The bootstrap test of confidence was used to determine the statistical validation of the species assignation, allowing for the first time a quantification of the certainty of the species assignation. The bootstrap values obtained from these results indicate that the sequencing of the cytochrome b fragments allows a correct species assignation with a probability > or =95%.     

Seed germination and seedling survival of two threatened endemic species of the northwest Iberian peninsula

We examined germination and seedling survival of Petrocoptis grandiflora and Petrocoptis viscosa (Caryophyllaceae), two narrow endemic species from the northwest Iberian Peninsula. The experiments were carried out with seeds of three of eight populations of P. grandiflora and one of the three sole populations of P. viscosa. Under natural conditions, both P. grandiflora and P. viscosa produce very large numbers of seeds. However, the specific microhabitat of these species (cracks and crevices of limestone rockfaces) has very marked effects on seed germination, and subsequent seedling survival. In the present study, we examined the effects of light, cold treatment and seed weight on germination capacity. In the case of P. grandiflora, we also compared the germination of seeds of the different populations. In addition, we assessed seedling survival over a 1-year period. Seeds maintained in darkness showed higher germination percentages than seeds maintained with a 12:12 h photoperiod. The application of a short period of cold prior to germination had no significant effect in either species. In the case of P. grandiflora, population of origin had a significant effect on germination percentage. Of all the factors considered, seed weight was the most important source of variability, both in seed germination and subsequent seedling survival. In both species in the natural habitat, less than 10% of germinated seeds survived by the end of the year. Seedling survival was affected by microhabitat. Seedlings in non-rockface soil microhabitats were more likely to suffer herbivory or interspecific competition than seedlings in crevices in the rockface.     

Suitability of Chinese wheat cultivars for production of northern style Chinese steamed bread

Fifty-six bread wheat cultivars and advanced lines from major Chinese wheat growing regions and 10 Australian cultivars were grown in Anyang located in Yellow and Huai Valleys and Chengdu located in Yangtze region. The genotypes were examined for their suitability to produce northern style Chinese steamed bread (CSB) and used to investigate the association between wheat quality traits and performance of northern style CSB under manual and mechanized processing conditions. Anyang-sown wheat samples showed better grain quality characteristics and CSB quality than the Chengdu-sown materials. These differences were largely due to adverse climatic conditions prevailing in Chengdu that resulted in the deterioration of flour whiteness, Farinograph stability, and starch quality. Therefore, Chengdu was generally unfavorable for producing good quality wheat. However, significant variability among cultivars was observed in Chengdu, and Batavia, Dollar bird, and Tasman from Australia and Jing 411, Xiaoyan6, and Shaan 229 from China showed very good CSB quality under manual conditions, and Hartog, Batavia, Tasman, and Vulcan from Australia, and Jing 411 and Dongfeng 1from China were identified to confer good CSB quality under mechanized conditions. The wide range of CSB quality variations indicates that genetic improvement of CSB quality is possible in both environments. Protein content, gluten strength, and extensibility were positively associated with loaf volume and steamed bread elasticity. The relationship between gluten strength, extensibility, and appearance and stickiness were highly dependent on processing methods, i.e., negatively using a manual method and positively or slightly negatively using a mechanized process. Therefore, wheat quality requirement for CSB depends on CSB processing conditions. Medium protein content and medium-to-strong gluten strength with good extensibility is desirable for mechanized methods, but weak-to-medium gluten type for manual methods. High flour whiteness and RVA peak viscosity was found desirable for CSB quality regardless of the processing method used. Flour whiteness, falling number, and peak viscosity appeared to be more crucial in determining CSB quality in Chengdu, although protein content and Farinograph stability also contributed to appearance, elasticity, and stickiness. This revised version was published online in July 2006 with corrections to the Cover Date.