Physiological Responses of Nile Tilapia,Oreochromis niloticus,Fed Vitamin C‐ and Lipid‐Supplemented Diets and Submitted to Low‐Temperature Stress*

Abstract.— Water temperature alterations can determine harmful physiological modifications in fish, which should be prepared to cope with this, and nutrition strategies seem to be essential. This study evaluated the effects of different levels of vitamin C and lipids on physiological responses of Nile tilapia, Oreochromis niloticus, submitted to temperature stress. There were two phases: Phase I – preparing fish to store vitamin C and lipid at appropriate temperature, and Phase II – evaluating the contributions these reserves make to fish physiology under low‐temperature stress. The experiment used a 3 × 2 factorial design with three vitamin C levels (300, 600, and 1200 mg/kg diet) and two lipid levels (8.0 and 12.0%), plus absence of nutrient test and a diet of 6.0% lipids and 125.0 mg/kg vitamin C. In Phase I, 192 fish were kept at 26.0 ± 1.0 C for 112 d, and in Phase II, 48 fish were kept at 18.0 ± 0.5 C for 32 d and at 15.0 ± 0.5 C for 11 d. Fish fed C₀L₀ diet showed lower erythrocytes values in both phases; higher vitamin C supplement determined higher red blood cell (RBC) number and higher hematocrit (Htc) (Phase II); Htc was significantly lower in Phase II; after temperature stress, fish fed C₀L₀ diet had higher mean corpuscular volume, lower hemoglobin corpuscular concentration, and significantly lower vitamin C concentration in the liver; and higher supplementation determined a higher concentration in the liver (Phases I and II). Higher plasmatic cortisol concentration was seen in fish fed C₀L₀ diet. In conclusion, our results show that the absence of vitamin C in diets impairs RBC formation and does not enable fish to cope with stress; excess vitamin C is efficient in mitigating stress and 600 mg/kg diet is economic and physiologically sufficient to prepare fish for coping with low‐temperature stress. Lipid supplementation does not determine alterations in stress biochemical parameters.     

Does Rhipicephalus microplus tick infestation increase the risk for myiasis caused by Cochliomyia hominivorax in cattle?

The larval phase of Cochliomyia hominivorax (screwworm) is an obligate parasite of vertebrate animals, particularly mammals, and widespread in South America, where it remains one of the most important parasitic diseases of domestic animals. The skin of cattle highly infested by ticks, with cutaneous lesions, exudation of tissue fluid and blood scent seems to produce the ideal environment for fly attraction. However, an association between these parasites was never investigated. The aim of this work was to verify if there is an association between Rhipicephalus microplus tick load and the occurrence of C. hominivorax myiasis in cattle, and to quantify the risk. Sixty bovine (Bos taurus taurus, Angus breed) under field conditions were observed for 24 weeks, during which weekly tick counts and examination for the presence of myiasis were performed. There was a significant association between a high tick burden (24-week mean above 50 ticks per animal) and myiasis occurrence (P = 0.0102). The calculated relative risk (RR) for C. hominivorax myiasis occurrence in cattle with high tick burden was 3.85 (CI95% = 1.23–12.13); indicating that cattle highly parasitized by R. microplus have about four times more risk of myiasis than those with a low parasite load. As far as we aware, this is the first statistically based evidence of the relationship between R. microplus parasitic load and occurrence of myiasis by C. hominivorax. This result could be useful for the design of integrated control strategies for these parasites and to provide more information for the understanding of cattle tick parasitism in cattle production.     

An iron-acquisition-deficient mutant of Corynebacterium pseudotuberculosis efficiently protects mice against challenge

Caseous lymphadenitis (CLA) is a chronic disease that affects sheep and goats worldwide, and its etiological agent is Corynebacterium pseudotuberculosis. Despite the economic losses caused by CLA, there is little information about the molecular mechanisms of bacterial pathogenesis, and current immune prophylaxis against infection has been unable to reduce the incidence of CLA in goats. Recently, 21 different mutant strains of C. pseudotuberculosis were identified by random mutagenesis. In this study, these previously generated mutants were used in mice vaccination trials to develop new immunogens against CLA. Based on this analysis, {"type":"entrez-nucleotide","attrs":{"text":"CZ171053","term_id":"58296493","term_text":"CZ171053"}}CZ171053, an iron-acquisition-deficient mutant strain, was selected. After challenge with a virulent strain, 80% of the animals that were immunized with the {"type":"entrez-nucleotide","attrs":{"text":"CZ171053","term_id":"58296493","term_text":"CZ171053"}}CZ171053 strain survived. Furthermore, this vaccination elicited both humoral and cellular responses. Intracellular survival of the bacterium was determined using murine J774 cells; in this assay, the {"type":"entrez-nucleotide","attrs":{"text":"CZ171053","term_id":"58296493","term_text":"CZ171053"}}CZ171053 had reduced intracellular viability. Because iron acquisition in intracellular bacteria is considered one of their most important virulence factors during infection, these results demonstrate the immunogenic potential of this mutant against CLA.     

Shark reactions to scuba divers in two marine protected areas of the Eastern Tropical Pacific

• 1. Worldwide, there are concerns about the potential impact of a growing tourism industry on the behaviour and ecology of sharks. Several shark species are key attractions in the scuba diving industry in both the Galápagos Marine Reserve (Ecuador) and the Sanctuary of Fauna and Flora Malpelo (Colombia).
• 2. In this study, the reactions of five species of shark to the behaviour of scuba divers were investigated in the Galápagos and Malpelo.
• 3. Four discrete categories of shark reaction (evasion, spontaneous approach, alert and no reaction) were identified and analysed against five categories of diver behaviour (direct approach, camera flash, sudden movement, noise and simple presence), two categories of observation strategy (still and movement) and the distance of the focal diver group to the sharks.
• 4. The type of reaction in the sharks was determined by the behaviour of the divers, their distance to the fish and, especially, by their observation strategy. Shark reactions varied between species and locations and divers acted more intrusively towards those species they were not afraid of, and which they could access more easily due to the conditions of their environment.
• 5. ‘Direct approach’, ‘sudden movement’, the observation strategy ‘moving’ and distances closer than 4 m between divers and sharks elicited stronger behavioural responses by the species targeted. Recommendations are given for the preferred actions divers should employ in order to diminish the effects on the target species analysed in this study. Copyright © 2011 John Wiley & Sons, Ltd.

     

Assisted Selection by Specific DNA Markers for Genetic Elimination of the Kunitz Trypsin Inhibitor and Lectin in Soybean Seeds

Summary The antinutritional factors found in soybean, lectin (SBL) and Kunitz trypsin inhibitor (SKTI), are usually inactivated by heat treatment. However, residual activity of these factors can be found in several types of soy-derived products. Heat treatment does not completely eliminate these factors, and in addition it may considerably decrease protein solubility. The genetic elimination of these antinutritional factors could be an alternative to the heat treatment. This study aimed to develop soybean lines devoid of SKTI and SBL in their seeds. The population under study was obtained by crossing the normal cv. Monarca with a soybean line lacking SKTI and SBL. Specific DNA primers were designed for the identification of the recessive alleles that condition the absence of SKTI and SBL. F₂ seeds presenting the DNA markers that identify the recessive alleles were selected and the corresponding F₂ plants were backcrossed with the recurrent parent (‘Monarca’), producing the BC₁F₁ generation. The F₂ generation was analyzed by SDS-PAGE in order to confirm the genotypes of the F₂ selected. The segregation tests confirmed that these traits are governed by two genes that segregate independently.     

Correction to: Who ate my chocolate? Small mammals and fruit damage in cacao agroforestry

Agroforestry Systems -     

Soil CO2 concentration,efflux, and partitioning in a recently afforested grassland

Relatively few studies have documented the impacts of afforestation, particularly production forestry, on belowground carbon dioxide (CO₂) effluxes to the atmosphere. We evaluated the changes in the soil CO₂ efflux—a proxy for soil respiration (Rs)—for three years following a native grassland conversion to eucalypt plantations in southern Brazil where minimum tillage during site preparation created two distinct soil zones, within planting row (W) and between-row (B). We used root-exclusion and carbon (C)- isotopic approaches to distinguish Rs components (heterotrophic-Rh and autotrophic-Ra respirations), and a CO₂ profile tube (1-m deep) to determine the concentration ([CO₂]) and isotopic C signature of soil CO₂ (δ¹³[CO₂]). The soil CO₂ efflux in the afforested site averaged 0.37 g CO₂ m^?2 h^?1, which was 56% lower than the soil CO₂ efflux in the grassland. The δ¹³CO₂ in the afforested site ranged from ? 14.1‰ to ? 29.4‰, indicating a greater contribution of eucalypt-derived respiration (both Rh and Ra) over time. Higher soil CO₂ efflux and lower [CO₂] were observed in W than B, indicating that soil preparation creates two distinct soil functional zones with respect to C cycling. The [CO₂] and δ¹³[CO₂] decreased in both zonal positions with eucalypt stand development. Although the equilibrium in C fluxes and pools across multiple rotations is needed to fully account for the feedback of eucalypt planted forests to climate change, we provide quantitative information on soil CO₂ dynamics after afforestation and show how soil preparation can leverage the feedback of planted forests to climate change.

     

Organic and Conventional <Emphasis Type="Italic">Coffea arabica</Emphasis> L.: A Comparative Study of the Chemical Composition and Physiological,Biochemical and Toxicological Effects in Wistar Rats

Differentiation between organic and conventional coffee has increased due to the growing demand and high consumption of healthy foods that contain compounds with antioxidant potential, which have been associated with the reduction of chronic diseases. We used organic and conventional coffee in powder 4% (w/w) and infusions 5%, 10% and 20% (w/v) incorporated in a commercial diet to test in vivo. The levels of chlorogenic acid, caffeine and trigonelline were determined by high performance liquid chromatography. The body weight, weight gain, food consumption, aberrant foci crypt, mucin depleted foci, stress biomarkers protein carbonyl and malondialdehyde, biochemical parameters and behavior of the rats were compared between the experimental and control groups within a framework of colon carcinogenesis. The organic coffee showed higher levels of chlorogenic acid, caffeine and trigonelline than conventional, however, this difference did not significantly affect behavior. The infusions had an antioxidant effect, reducing the levels of malondialdehyde; however, the biochemical parameters of the serum were not altered, and there was neither induction nor prevention of preneoplasic lesions.     

Effect of arginine supplementation on the morphology and function of intestinal epithelia and serum concentrations of amino acids in pigs exposed to heat stress

The exposure of pigs to heat stress (HS) appears to damage their intestinal epithelia, affecting the absorption of amino acids (AAs). Arg is involved in the restoration of intestinal epithelial cells but HS reduces Arg intake. The effect of dietary supplementation with Arg on the morphology of intestinal epithelia, AA transporter gene expression, and serum concentration (SC) of free AAs in HS pigs was analyzed. Twenty pigs (25.3 ± 2.4 kg body weight) were randomly assigned to two dietary treatments: Control (0.81% Arg), wheat–soybean meal diet supplemented with l-Lys, l-Thr, dl-Met, and l-Trp, and the experimental diet where 0.16% free l-Arg was supplemented to a similar Control diet (+Arg). All pigs were individually housed and exposed to HS, fed ad libitum with full access to water. The ambient temperature (AT), recorded at 15-min intervals during the 21-d trial, ranged on average from 29.6 to 39.4 °C within the same day. Blood samples were collected on day 18 at 1600 hours (AT peak); serum was separated by centrifugation. At the end of the trial, five pigs per treatment were sacrificed to collect samples of mucosa scratched from each small intestine segment. The expression of AA transporters in intestinal mucosa and the SC of AAs were analyzed. Villi height (VH) was higher (P < 0.01) in the duodenum, jejunum, and ileum but the crypt depth did not differ between the Control and the +Arg pigs. Supplementation of l-Arg increased the mRNA coding for the synthesis of the cationic AA transporter b^0,+ (P < 0.01) and the neutral AA transporter B⁰ (P < 0.05) in the duodenum by approximately 5-fold and 3-fold, respectively, but no effect on mRNA abundance was observed in the jejunum and ileum. The supplementation of l-Arg increased serum Arg, His, Met, Thr, Trp, and urea (P < 0.05) and also tended to increase Val (P < 0.10) but did not affect Ile, Lys, Leu, and Phe. These results indicate that supplementing 0.16% l-Arg to the Control diet may help to improve the function of the small intestine epithelium, by increasing the VH, the abundance of AA transporters, and the SC of most indispensable AAs in pigs exposed to HS conditions. However, the lack of effect of supplemental Arg on both Lys SC and weight gain of pigs suggests that increasing the Lys content in the +Arg diet might be needed to improve the performance of HS pigs.