Effect of the UV-C Radiation on Shelf Life of Vacuum-Packed Refrigerated Pirarucu (Arapaima gigas) Fillets

The effect of Ultraviolet radiation type C (UV-C) radiation (0.100 ± 0.010 J/cm²) on shelf life of Arapaima gigas fillets stored at 4 ± 1°C for 18 days was investigated. The samples were analyzed for total aerobic mesophilic bacteria (TAMB) counts; total aerobic psychrotrophic bacteria (TAPB) counts; Enterobacteriaceae; purge loss; pH; lipid oxidation; total volatile bases (TVB-N); ammonia; biogenic amines (BAs); and L*, a*, and b* values. UV-C radiation increased (P < 0.05) the generation time of all bacterial groups evaluated, increasing the shelf life by 2 days. UV-C-treated fillets showed lower (P < 0.05) L* values, purge loss, pH, TVB-N, ammonia, and BAs levels than their control counterparts throughout the storage period. Moreover, UV-C treatment did not result (P > 0.05) in detrimental effects on lipid oxidation or a* and b* values. UV-C at 0.100 J/cm² demonstrated a good potential for use in A. gigas fillets and, therefore, it could be applied at industrial scale.     

Proper supply of S increases GSH synthesis in the establishment and reduces tiller mortality during the regrowth of Tanzania guinea grass used for Cd phytoextraction

Purpose

Cadmium has caused serious environmental problems due to its phytotoxicity, requiring solutions to reduce its concentration in the environment. Because S can alleviate the phytotoxicity caused by heavy metals, the evaluation of the effects of S supply is a promising approach to address this problem. The aim of this study was to determine the influence of S in reducing the phytotoxicity caused by Cd to Panicum maximum Jacq. cv. Tanzania (guinea grass) and to evaluate the potential of this grass for Cd phytoextraction.

Materials and methods

Tanzania guinea grass was cultivated in a nutrient solution to evaluate the combinations of five rates of S (0.1, 1.0, 1.9, 2.8, and 3.7 mmol L^?1) and five rates of Cd (0.0, 0.5, 1.0, 1.5, and 2.0 mmol L^?1), in a 5² fractional factorial design with six replications. Six plants were grown per pot in two growth periods to evaluate the effect of Cd on the establishment (51 days of age) and on the regrowth (18 days of growth) of the plants. During regrowth, Cd was not supplied in the nutrient solution. At the end of each growth period, growth parameters, concentrations of S and Cd, Cd transport factor, and concentrations of hydrogen peroxide (H₂O₂), malondialdehyde, reduced glutathione, and oxidized glutathione were evaluated.

Results and discussion

On the establishment of Tanzania guinea grass, application of Cd reduced mass production by 39 % due to the increases in the concentration of Cd (30 times compared with the treatment without Cd) and in lipid peroxidation (124 %). During regrowth, the residual effect of Cd resulted in a lower number of tillers (62 %) and leaves (89 %) caused by the increase in concentrations of Cd, H₂O₂ (49 %), and lipid peroxidation, which resulted in a 65 % lower dry mass production. The proper supply of S reduced concentration of Cd and tiller mortality rate due to the residual effect of Cd on the regrowth of the grass. Mass production by the roots was 43 % lower because of Cd, but the transport of Cd from roots to shoots increased. The increase in the concentration of glutathione (GSH) associated with a possible higher activity of antioxidant enzymes alleviated the phytotoxic effects of Cd on the guinea grass.

Conclusions

The supply of S reduces the phytotoxicity caused by Cd to guinea grass, especially during the regrowth of the plant, when the concentration of Cd is higher because of the transport from roots to shoots. Tanzania guinea grass showed to be very promising for phytoextraction of Cd due to its high mass production, even when Cd was largely available in the nutrient solution.

     

Toxicity of soybean-registered agrochemicals to <Emphasis Type="Italic">Telenomus podisi</Emphasis> and <Emphasis Type="Italic">Trissolcus basalis</Emphasis> immature stages

Biological control of phytophagous bugs in soybean crops is efficiently performed by egg parasitoids, such as Telenomus podisi and Trissolcus basalis. Based on this, the use of agrochemicals in these crops must be managed consciously, making use of pesticides that are selective to the egg of these parasitoids, in order to ensure a balanced ecosystem. The aim of this study was to assess the selectivity of 15 registered pesticides to the immature stages (pre and post-parasitism) of T. podisi and T. basalis, following the method proposed by the “International Organization for Biological and Integrated Control” (IOBC). Pesticides were classified as class 1 – harmless (RP?<?30%); class 2 – slightly harmful (30%?≤?RP?≤?79%); class 3 – moderately harmful (80%?≤?RP?≤?99%); and class 4 – harmful (RP?>?99%). During pre-parasitism, the insecticides imidacloprid+beta-cyfluthrin, deltamethrin, lambda-cyhalothrin+thiamethoxam, acephate, and fenitrothion reduced parasitism of both parasitoids. The others: flubendiamide, diflubenzuron, Bacillus thuringiensis, lufenuron, and the herbicide isopropylamine were selective, i.e. harmless (class 1), to both parasitoids, except for pyraclostrobin+metconazole, which significantly reduced T. basalis parasitism, being considered slightly harmful (class 2). In post parasitism, all the aforementioned pesticides were harmless to T. podisi and T. basalis. Moreover, in pre-parasitism, T. basalis was found to be more sensitive to the tested pesticides when compared to T. podisi. Still, more studies must be conducted to provide a better understanding of the impact of agrochemicals on these parasitoid species in semi-field conditions.     

Effect of days postburning and calcium oxide on the fermentation,aerobic stability and nutritional characteristics of sugarcane silage for finishing Nellore steers

In this study, the effects of days postburning and calcium oxide (CaO) on the fermentation, aerobic stability and nutritional characteristics of sugarcane silages for finishing Nellore steers were investigated. Silages were prepared in minisilos from in natura and burned sugarcane that remained in the field 1 and 10 days postburning (1‐day burned and 10‐day burned, respectively). Next, forages were left untreated or treated with CaO (10 g/kg fresh forage). Compared to that in untreated silages, CaO application increased the dry‐matter (DM) recovery of in natura, 1‐day and 10‐day burned silages (p < 0.001) by 67, 179 and 209 g/kg DM respectively. The CaO treatment increased (p < 0.001) the aerobic stability of the in natura and 10‐day burned silages by 62.7 and 24.7 hr respectively. In a feedlot experiment, feeding 1‐day burned silage reduced DM intake of steers throughout the feedlot period (0–93 days; p < 0.05) compared with that of steers fed in natura silage diet, but the average daily gain (ADG) was lower (p = 0.006) only during the adaptation period (?0.16 kg/day; 0–28 days). The CaO application decreased DM intake (p = 0.007; ?1.17 kg/day) and ADG (p < 0.001; ?0.13 kg/day) of steers only during the adaptation period likely owing to low silage palatability caused by increased Ca and butyric acid concentrations (≥11.6 g/kg DM). We recommend feeding beef cattle with CaO‐treated burned sugarcane silages in low‐dietary concentration because of its high butyric acid concentration.     

Accompanying ions of ammonium sources and nitrate : ammonium ratios in tomato plants

The tomato (Solanum lycopersicum L.) cultivar Micro‐Tom (MT) is widely used in physiological studies, but the effects of nitrate ( ) and ammonium ( ) ratios ( : ratios) and, in particular, the effects of the accompanying ions in sources are unknown. To determine whether the accompanying ions in sources influence toxicity, the effects of : ratios on the physiology, electrolyte leakage index, nutrition, and dry weight were studied using hydroponics. The sources were ammonium chloride (NH₄Cl) or ammonium sulfate [(NH₄)₂SO₄], and five : ratios were used: 100 : 0, 75 : 25, 50 : 50, 25 : 75, and 0 : 100. The source was calcium nitrate [Ca(NO₃)₂], and the nitrogen (N) concentration was 15 mmol L^?1. The results indicate that NH₄Cl or (NH₄)₂SO₄ can be used in studies on toxicity because the accompanying ions did not influence the tomato plants. In addition, : ratios of 100 : 0 and 75 : 25 resulted in the highest dry weight of tomato plants, whereas ratios of 25 : 75 or 0 : 100 were toxic.     

Genotoxicity in the Offspring of Rats Exposed to Contaminated and Acidified Experimentally Soils

The aim of this study was to evaluate the genotoxic and mutagenic potential of contaminated soil diluted in acidic solutions and not acidic, in the offspring of rats exposed during pregnancy and neonatal periods. To this end, a comet assay and micronucleus test were performed. Soil samples were solubilized in the following three solvents: distilled water (control group), acid solvent at pH 5.2, and acid solvent at pH 3.6. Soil and solvent were mixed in a rate of 1:2 in g/mL, and hydrofluoric acid was used in the acid solvents. In the comet assay, the tail length, percentage of DNA within the tail and tail moment was analyzed in the whole blood of the pups that were studied. The number of micronuclei found in the bone marrow cells was counted in the micronucleus test. In all parameters evaluated in the comet assay, the group exposed to the lowest pH value when associated with contaminated soil (p < 0.05) had the most damage. However, the micronucleus test showed differences between all exposed groups and the control group (p < 0.05). These results reaffirm the health risks related to the exposure to soil contaminants.