Effect of inoculation of the cyanobacteria Oscillatoria sp. on tilapia biofloc culture

Cyanophytes are the most ancient photosynthetic organisms. During its evolution, they have developed various ecophysiological adaptation strategies to survive in extreme conditions. The environment prevailing under biofloc cultures provides various conditions appropriate for cyanobacterial proliferation. An outdoor experiment (7 weeks) was performed with a simple random design consisting of four inoculation levels (by triplicate) of Oscillatoria sp. (0.0, 0.1, 0.5 and 1 mg L^?1) in saltwater biofloc. The objective was to evaluate the effect of the cyanobacteria inoculation on water quality and tilapia production parameters. The results indicated that the amount of Oscillatoria sp. inoculated significantly affected water quality (pH, chlorophyll a, TSS and NO₃‐N) and tilapia parameters (final weight, feed conversion ratio, specific growth rate and survival). No significant effects on dissolved oxygen, total ammonia nitrogen (TAN) or NO₂‐N were observed. We recommend identifying the cyanobacteria species that are able to grow in a biofloc system and their possible adverse effects on the system.     

Plant Growth and Sugars Content of Agave americana L. Cultivated with Vermicompost and Rock Phosphate and Inoculated with Penicillium sp. and Glomus fasciculatum

The objective of this study was to investigate the effect of vermicompost, rock phosphate, Glomus fasciculatum (arbuscular mycorrhizal fungi), and Penicillium sp. (phosphate solubilizing fungi) on growth; mycorrhization percent; fructan, sucrose, glucose, and fructose contents in leaves and stem of Agave americana L. Experiments were done according to an orthogonal experimental design L₈ with four variables at two levels: vermicompost (0 or 10 g per plant), rock phosphate (0 or 1 g per plant), G. fasciculatum (0 or 1 × 10⁶ spores per plant), and Penicillium sp. (0 or 1 × 10⁹ spores per plant). Vermicompost affected stem dry weight; the fructan, glucose, and fructose in stem; and mycorrhization percent in roots. Rock phosphate and Penicillium sp. increased the mycorrhization percent. Co-inoculation of Penicillium sp. and G. fasciculatum increased A. americana plant growth. The results obtained suggested a synergistic interaction between the arbuscular mycorrhizic fungi and the phosphate solubilizing fungi.     

Effect of diphenyl diselenide diet supplementation on oxidative stress biomarkers in two species of freshwater fish exposed to the insecticide fipronil

The ability of diphenyl diselenide [(PhSe)₂] to attenuate oxidative damage was evaluated in the liver, gills, brain, and muscle of carp (Cyprinus carpio) and silver catfish (Rhamdia quelen) experimentally exposed to fipronil (FPN). Initially, the fish were fed a diet without (PhSe)₂ or a diet containing 3.0 mg/kg of (PhSe)₂ for 60 days. After the 60-day period, the fish were exposed to 0.65 µg/L of FPN for 192 h. The results showed that carp exposed to FPN and not fed with (PhSe)₂ exhibited acetylcholinesterase (AChE) inhibition in brain and muscle, and increased thiobarbituric acid-reactive substance (TBARS) in liver, gills, and brain. Furthermore, FPN decreased nonprotein thiols (NPSH) and δ-aminolevulinate dehydratase (δ-ALA-D) in carp liver and gills, and increased plasma glucose and protein levels. In silver catfish, FPN inhibited AChE and increased TBARS levels in muscle. In addition, glutathione S-transferase (GST) decreased in liver and muscle, and plasma glucose was increased. (PhSe)₂ reversed some of these effects. It prevented the increase in TBARS levels in liver, gills, and brain in carp and in silver catfish muscle, and reversed the increase in plasma glucose levels in both species. Additionally, (PhSe)₂ increased the NPSH levels in carp and silver catfish that had decreased in response to FPN exposure. However, (PhSe)₂ was not effective in reversing the AChE inhibition in brain and muscle or the δ-ALA-D decrease in carp liver. Thus, (PhSe)₂ protects tissues of both species of fish, mainly by preventing or counteracting the effects of FPN, on TBARS levels, antioxidants, and present anti-hyperglycemic property.     

Relationships among twelve genotypes of roselle (Hibiscus sabdariffa L.) cultivated in western Mexico

The aim of this study was to characterize agromorphological and molecular relationships between twelve genotypes of roselle (Hibiscus sabdariffa L.) grown in western Mexico. Variables related to crop yield and management at two localities were used for agromorphological characterization. Data were analyzed using principal component analysis. The first four components explained 75.77% of the variation between genotypes. Molecular characterization was conducted using the inverse sequence-tagged repeat marker, which separated the 12 genotypes into two main groups. Three of the genotypes that grouped together at the molecular level had a similar leaf phenotypic characteristic (the number of lobes), which differed from that of the other genotypes. Variation between genotypes was evident in respect of molecular variables, which were used as genetic markers to distinguish between genotypes. Grouping of genotypes according to agromorphological variables, which reflect the response of a genotype to the environment, yielded similar results to molecular grouping. Genetic structure analysis indicated that the China, Fresa, Diamante, and Gigante genotypes probably share a common origin.     

Life in the suburbs: Behavior and survival of a freshwater turtle in response to drought and urbanization

Urbanization fundamentally alters the abiotic and biotic components of landscapes, presenting wildlife with serious challenges to which they must respond in order to avoid excess mortality from urban dangers. In this study, we used radio-telemetry to examine the behavior and survivorship of an Australian freshwater turtle, Chelodina longicollis, in a suburban environment compared to a control group on an adjacent nature reserve. We expected turtles in the suburbs to be less mobile, but the suburban environment did not inhibit the ability of turtles to traverse large areas and make frequent movements among several different wetlands. In fact, suburban turtles were more vagile, moving distances twice as far as those on the nature reserves. Turtles on the nature reserve responded to dropping water levels during drought by estivating for several months in sheltered woodland micro-habitats. Suburban turtles did not estivate terrestrially, in part because their water bodies experienced dampened water level fluctuations and retained water during drought, though the relative unavailability of suitable estivation sites and perceived threats could also account for their avoidance of extended forays into the terrestrial environment. Annual survival rate was 95.3% in the reserves compared to 87.6% in the suburbs, but this 7.7% decrease in survival from road mortality was not significant in our survivorship models. The continued ability of suburban turtles to remain vagile without suffering from high mortality rates is likely a product of the availability of vegetated drainage lines and under-road “box” culverts that allow turtles to travel safely throughout the suburban landscape.     

Effects of conjugated linoleic acid and curcumin on growth performance and oxidative stress enzymes in juvenile Pacific white shrimp (Litopenaeus vannamei) feed with aflatoxins

Aflatoxicosis is a growing problem in aquaculture. A 42‐day study was designed to evaluate the efficacy of conjugated linoleic acid (CLA) and curcumin (CUR) to protect juvenile Pacific white shrimp (Litopenaeus vannamei) from aflatoxins. Growth parameters along with alkaline phosphatase (ALP) and glutathione S‐transferase (GST) activities were measured. Shrimps (36) with an average weight of 76 ± 0.9 mg were randomly allocated in eight experimental groups. Non‐contaminated diet (NCD) and aflatoxin‐contaminated diet (ACD) at 200 μg/kg were prepared. ACD was used to prepare six diets supplemented with CLA (4, 5 or 6 g/kg) and CUR (0.15, 0.2 and 0.3 g/kg). ACD reduced feed intake, growth rate and nitrogen retention efficiency, and increased ALP and GST activity. Improved nitrogen retention was observed for all groups feed with CLA. CUR supplementation at 0.2 g/kg increased feed intake and growth rate while at 0.15 g/kg increased nitrogen retention. ALP activity was reduced in all CUR groups and in 5 and 6 g/kg CLA groups. Reduction in GST activity was observed in 0.15 and 0.2 g/kg CUR groups and 4 g/kg CLA group. CLA supplementation and CUR supplementation can be beneficial to protect juvenile shrimp against aflatoxins.     

Effect of a Cell‐Wall‐Degrading Enzyme Complex on Starch Recovery and Steeping Requirements of Sorghum and Maize

The effect of a commercial cell‐wall‐degrading enzyme (CWDE) complex on the steeping time and starch yields of white regular sorghum (RSOR) compared with yellow maize (YMZ) was determined. An in vitro wet‐milling method standardized to test dosages of 0–120 fungal β‐glucanase units (FBG)/100 mL indicated that starch yields were significantly higher for YMZ than RSOR and increased proportionally as enzyme dosage increased. A factorial experiment with a level of confidence of P < 0.05 was performed to study the effect of CWDE addition to coarsely ground grains for 4 hr after 20 or 44 hr of SO₂ steeping of whole grains. At both regular steep times, YMZ yielded significantly higher amounts of starch than RSOR. When steep times were compared, grains soaked for 48 hr produced 1.7% higher starch yields than counterparts treated for 24 hr. CWDE significantly increased starch yields and recoveries. Enzyme‐treated grains yielded 2.5% more starch than counterparts steeped regularly. For both grains, the best wet‐milling conditions to obtain the highest amount of starch were 48 hr of steeping and CWDE addition. Under these conditions, YMZ and RSOR yielded 66.9 and 66.6% starch, respectively. Starches obtained after the enzyme treatment at both steep times contained higher amounts of residual protein and ash compared with the untreated counterparts. Rapid viscoamylograph properties of YMZ and RSOR starches were not affected by the use of the CWDE nor the steep time. In comparison with RSOR starch, the YMZ starch initiated gelatinization at lower temperature, had less shear thinning and higher viscosity or setback at the end of cooling.     

Protein and lipid requirement for the growth and reproduction of the peppermint shrimp Lysmata wurdemanni

The effect of dietary protein and lipid level on growth and reproductive efficiency of the pepermint shrimp Lysmata wurdemanni was evaluated over a 90‐day period. The percentage of protein and lipid (%P/L) in the experimental diets varied as follows: 34/7, 34/8, 34/9, 37/7, 37/8, 37/9, 40/7, 40/8 and 40/9, and a commercial diet was used as control (35/7‐Silver Cup^®). Fifteen shrimps per treatment and three replicates were used. The number of moults, survival, and growth, number of ovigerous females as well as protein and carbon content of fertilized eggs were evaluated. The shrimps fed experimental diets 37/7 and 40/9 exhibited a survival of 100%, whilst the survival of shrimp fed diet 40/7 was 73%, without significant differences being observed among the treatment groups. The weight gained (g) by shrimps fed diets 37/9 and 40/8 was significantly greater than the control group. The greatest percentage of ovigerous females was observed in those fed 34/7 and 37/9 diets, and the lowest in the control group. The greatest content of protein/carbon in the eggs was found in females fed the 40/8 diet. The results indicated that a P/L relationship of 34/7% promote efficient growth; however, during the reproductive phase it is necessary to increase the P/L to 40/8% to improve the quality and viability of the eggs.     

Isotopic Evaluation of the Nutritional Contribution of Poultry By‐product Meal and Fish Meal to the Growth of Pacific White Shrimp,Litopenaeus vannamei

The nutritional contribution of the dietary nitrogen supplied by poultry by‐product meal (PBM) and fish meal (FM) to the somatic growth of Pacific white shrimp, Litopenaeus vannamei, was assessed by means of stable isotope analysis. Seven experimental diets were formulated with different proportions of PBM replacing FM. Practical diets were formulated to replace 0, 35, 50, 65, 80, 95, and 100% of FM with PBM, on a dietary nitrogen basis. At the end of the experiment, there were no significant differences in survival among dietary treatments (89 ± 5%); however, significant differences in final wet weights were observed. Diets having FM replacement levels of 35 and 50% with PBM promoted mean final weights (708–789 mg) similar to those observed in shrimps fed on diet containing 100% FM (874 mg). Shrimp final mean weight significantly decreased as a function of PBM inclusion (r = −0.98) owing to the use of only two dietary nitrogen sources and by possible nutritional restrictions as PBM levels increased. The relative proportions of dietary nitrogen supplied by PBM and FM were incorporated in muscle tissue at proportions that were statistically similar to those established in the dietary formulations.