Depletion study and estimation of the withdrawal period for enrofloxacin in pacu (Piaractus mesopotamicus)

Defining the pharmacokinetic parameters and depletion intervals for antimicrobials used in fish will help in the development of important guidelines for future regulations by Brazilian agencies on the use of these substances in fish farming. This paper presents a depletion study for enrofloxacin (ENR) and its main metabolite, ciprofloxacin (CIP), in pacu (Piaractus mesopotamicus) fillets. The depletion study was carried out under monitored environmental conditions, with the temperature controlled at 27 °C to mimic the fish farming conditions in Brazil. ENR was administered orally via medicated feed for 10 consecutive days at daily dosages of 10 mg/kg body weight (b.w.). The fish were slaughtered at 6, 12, and 24 h and 2, 3, 5, 8, 12, 17, and 24 days after the medication period. Considering a maximum residue limit of 100 μg/kg for the sum of the ENR and CIP residues in the fillet, the results obtained in the depletion study allowed the estimation of a half‐life for ENR of 2.75 days and a withdrawal period of 23 days. The results obtained in this study are important for the farming of pacu in tropical regions.     

Shade effects on feeding behavior,feed intake,and daily gain of weight in female goat kids

Solar radiation and high ambient temperatures negatively affect feeding time, performance, and animal welfare in several species. The provision of shade is a simple method that helps to minimize the negative effects. To determine whether shade influences feeding behavior, feed intake, and daily weight gain (DWG) in female goat kids, 40 dairy goat kids were used in 2 similar pens whose feeders were shaded (n = 20) or unshaded (n = 20) during 60 days. From May to July, behavioral data were collected through 10-minute scan samples during a 24-hour period for a total of 300 hours. Both pens were shaded on the opposite side to the feeder with 15 m² each in a resting area. All goat kids were observed for their position inside the pen, and the number of times they were seen eating was recorded. When the concentrate was provided (between 13:00 and 13:30 hours, as usually in the farm), the time was recorded until >50% of the animals stopped feeding and went back to the resting area (concentrate test). Food wastes were collected and weighed daily to calculate the food consumption. Ambient and black globe temperatures were daily recorded. Body weight was recorded every week to calculate DWG. A higher percentage of animals feeding was recorded in the shaded feeders than that in the unshaded feeders (P < 0.05). Food refusal was higher in the unshaded feeders (30 ± 1.8%) than that in the shaded feeders (25 ± 1.9%; P = 0.05). The concentrate test duration was 26.6 minutes (±1.3) in the shaded feeders and 16.1 minutes (±1) in the unshaded feeders (P < 0.05). The concentrate test duration was negatively correlated to the ambient temperature in the unshaded animals (r = ?0.50 and r² = 0.25; P = 0.02), and it was not significant in the shaded ones (r = ?0.23, r² = 0.05; P > 0.05). DWG was not different between groups (0.08 ± 0.03 kg per group; P > 0.05). Results suggest that shade on feeders helps to ameliorate some negative effects of solar radiation increasing feeding time and feed intake in female goat kids. This could be of great interest to prevent performance and welfare negative affectations.     

Characterization of a resistance locus (Pfs-1) to the spinach downy mildew pathogen (Peronospora farinosa f. sp. spinaciae) and development of a molecular marker linked to Pfs-1

Downy mildew is a destructive disease of spinach worldwide. There have been 10 races described since 1824, six of which have been identified in the past 10 years. Race identification is based on qualitative disease reactions on a set of diverse host differentials which include open-pollinated cultivars, contemporary hybrid cultivars, and older hybrid cultivars that are no longer produced. The development of a set of near-isogenic open-pollinated spinach lines (NILs), having different resistance loci in a susceptible and otherwise common genetic background, would facilitate identification of races of the downy mildew pathogen, provide a tool to better understand the genetics of resistance, and expedite the development of molecular markers linked to these disease resistance loci. To achieve this objective, the spinach cv. Viroflay, susceptible to race 6 of Peronospora farinosa f. sp. spinaciae, was used as the recurrent susceptible parent in crosses with the hybrid spinach cv. Lion, resistant to race 6. Resistant F(1) progeny were subsequently backcrossed to Viroflay four times with selection for race 6 resistance each time. Analysis of the segregation data showed that resistance was controlled by a single dominant gene, and the resistance locus was designated Pfs-1. By bulk segregant analysis, an amplified fragment length polymorphism (AFLP) marker (E-ACT/M-CTG) linked to Pfs-1 was identified and used to develop a co-dominant Sequence characterized amplified region (SCAR) marker. This SCAR marker, designated Dm-1, was closely linked ( approximately 1.7 cM) to the Pfs-1 locus and could discriminate among spinach genotypes that were homozygous resistant (Pfs-1Pfs-1), heterozygous resistant (Pfs-1pfs-1), or homozygous susceptible (pfs-1pfs-1) to race 6 within the original mapping population. Evaluation of a wide range of commercial spinach lines outside of the mapping population indicated that Dm-1 could effectively identify Pfs-1 resistant genotypes; the Dm-1 marker correctly predicted the disease resistance phenotype in 120 out of 123 lines tested. In addition, the NIL containing the Pfs-1 locus (Pfs-1Pfs-1) was resistant to multiple races of the downy mildew pathogen indicating Pfs-1 locus may contain a cluster of resistance genes.     

Debaryomyces hansenii L2‐enriched diet enhances the immunity status,gene expression and intestine functionality in gilthead seabream (Sparus aurata L.)

This study evaluates the effects of the dietary administration of the live yeast Debaryomyces hansenii strain L2 on the immune responses of gilthead seabream for 4 weeks. Cellular immune parameters were measured from serum and head‐kidney leucocytes respectively. The expression levels of immune‐associated genes were quantified by real‐time polymerase chain reaction. In addition, the profile of intestinal microbiota was studied by denaturing gradient gel electrophoresis. The results showed that seabream fed a diet containing D. hansenii had significantly increased cellular immune parameters. The yeast‐supplemented diet up‐regulated the expression of most seabream genes at week 2 and down‐regulated all of them at week 4, except in the head‐kidney. Finally, a reduction in the diversity of the intestinal microbiota was detected in those specimens receiving the yeast‐supplemented diet. These results support the idea that the live yeast D. hansenii strain L2 stimulates the immune system of gilthead seabream.     

MDN-0170, a New Napyradiomycin from Streptomyces sp. Strain CA-271078

A new napyradiomycin, MDN-0170 (1), was isolated from the culture broth of the marine-derived actinomycete strain CA-271078, together with three known related compounds identified as 4-dehydro-4a-dechloronapyradiomycin A1 (2), napyradiomycin A1 (3) and 3-chloro-6,8-dihydroxy-8-α-lapachone (4). The structure of the new compound was determined using a combination of spectroscopic techniques, including 1D and 2D NMR and electrospray-time of flight mass spectrometry (ESI-TOF MS). The relative configuration of compound 1, which contains two independent stereoclusters, has been established by molecular modelling in combination with nOe and coupling constant analyses. Biosynthetic arguments also allowed us to propose its absolute stereochemistry. The antimicrobial properties of the compounds isolated were evaluated against methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, Aspergillus fumigatus, and Candida albicans. The potent bioactivity previously reported for compounds 2 and 3 against methicillin-sensitive S. aureus has been extended to methicillin-resistant strains in this report.     

Two provenances of Quercus ilex ssp. ballota (Desf) Samp. nursery seedlings have different response to frost tolerance and autumn fertilization

Despite evidences that Holm oak has a high plasticity and great adaptability, there is limited or contradictory knowledge of the morphological and physiological variability of this species. Holm oak has been widely used for reforestation projects in Mediterranean areas, but has frequently shown poor field performance. We hypothesized that Holm oak has inter-population differences in physiological responses to abiotic stressors that could affect reforestation success. The influence of nursery culture on the characteristics of Holm oaks from different provenances has not been explored in depth. Thus, we studied the effect of nursery autumn fertilization on morphological traits, frost tolerance, root growth potential, and nutritional status of two Spanish provenances of Holm oak, La Alcarria (a region with inland Mediterranean climate) and Sierra Morena Occidental (a region with a warm coastal Mediterranean climate). There were significant differences between the provenances in frost tolerance, biomass allocation, and leaf nutrient content, suggesting a role of genetic factors. The leaves of seedlings from La Alcarria had less visual damage at ?12°C than seedlings from the warmer provenance (45% vs. 92%). Seedlings from La Alcarria, compared to those from Sierra Morena, had higher leaf P concentration (0.17% vs. 0.15%), greater stem diameter (3.1?mm vs. 2.7?mm), lower shoot-to-root dry mass ratio (0.46 vs. 0.53), and lower slenderness (4.03 vs. 5.31). For both provenances, N autumn fertilization improved growth, root growth potential, cold hardiness, and nutritional status of seedlings. We suggest that forest reforestation programs should consider to a greater extent Holm oak provenances and their tolerances to different abiotic stressors.     

Characterization of E1 Kraft Mill Effluent by Toxicity Identification Evaluation Methodology

In order to recover and reuse water in the Kraft mill process, evaluation of separate streams is required to identify toxic compounds or microcontaminants. The stage E1 Kraft effluent, corresponding to the first extraction step of the bleaching Kraft mill process, provides the main toxic compounds found in the final process effluent. This paper uses the toxicity identification evaluation (TIE) procedure for the physicochemical and ecotoxicological characterization of the E1 Kraft effluent. To distinguish the most important toxic compounds, a physicochemical characterization and Phase I of the TIE procedure were performed. The acute toxic effect of the E1 Kraft effluent and treated fraction was performed on Daphnia magna. Results show that untreated E1 Kraft effluent exerts an acute toxic effect on D. magna (24 h LC₅₀?=?27.6%), where the E1 Kraft effluent is characterized by pH 10.5, chemical organic demand (COD) 1,348.8 mg/l, and biological organic demand (BOD₅) 397.5 mg/l, while total phenolic compounds and color are 853.7 mg/l and 0.204 1?×?1 cm, respectively. Additionally, Cu⁺² (0.51 mg/l) and Fe⁺² (0.64 mg/l) were detected. With respect to different treatments, our results indicate that activated carbon, anionic and cationic exchange treatments were able to reduce more that 45% of E1 Kraft effluent’s acute toxicity and that the ethylenediaminetetraacetic acid treatment was able to reduce the E1 Kraft effluent’s acute toxicity to around 75% and the Cu⁺² concentration to 0.019 mg/l. Moreover, specific analysis of heavy metals and organic compounds by GC-MS show that the main compound responsible for the toxicity was Cu⁺², whose tolerance level on D. magna of the 0.12 mg/l.     

Understanding biological characteristics of <Emphasis Type="Italic">Acacia melanoxylon</Emphasis> in relation to fire to implement control measurements

Key message

Acacia melanoxylon produces abundant seeds leading to large seed banks in the soil. These seeds display a large viability and their germination is stimulated by heat. To control the populations, it is necessary to remove adults and young individuals, and to prevent seedling establishment after fire occupying the space with rapid growth and high competitive native species.

Context

Acacia melanoxylon displays a widespread distribution in South West Europe, and an improved knowledge of its reproductive characteristics is required in order to control its expansion.

Aims

This experiment was designed to provide useful indicators for an efficient management of A. melanoxylon populations based on its biological cycle in relation to fire.

Methods

We explored the reproductive biology of A. melanoxylon, from seed dissemination—–quantifying seed rain over a year, their germination with and without fire—the seedling and sapling banks and the structure of the adult population. We analysed the effects of fire, seed maturation and scarification on the viability of seeds and the stimulation of seed germination in the aerial seed bank and in the different strata of the soil seed bank.

Results

Our results indicate that A. melanoxylon produced millions of seeds per ha and per year, half of which germinated and the other half went to the soil seed bank, maintaining the viability many years. The germination was the most critical step in the population dynamics of this species, and fire stimulates germination up to 90%.

Conclusion

A. melanoxylon adults and seedlings removal, followed by colonization of rapid growth and high competitive native species that cover the ground very quickly would be a good control action.

     

Nitrogen in plant growth and yield of common bean

The aim of this research was to determine the effect of nitrogen (N) availability on wild Rhizobiumnodulation, plant growth and grain yield of the common bean crop. Experiments were conducted in two growing periods, from 2 March to 3 June 2011 (autumn) and from 21 September to 23 December 2011 (spring), in pots using sand as substrate. Nitrogen concentrations of 5.12 (T1), 7.6 (T2), 10.12 (T3), 12.62 (T4), and 15.12 (T5) mmol L^?1 were supplied by fertigation. In spring, the grain yield, number of grains and shoot growth of both cultivars reduced by effect of N concentration but in the cultivar BRS Valente they reducedonly in autumn. Number of nodules and root growth decreased in both cultivars while N concentration increased in the plant tissues. Nitrogen fertilization is not required to the common bean and its use inhibits nodulation. The increased availability does not enhance plant growth and grain yield.