Performance of a photo‐heterotrophic,hypersaline system for intensive cultivation of white leg shrimp (Litopenaeus vannamei) with minimal water replacement in lined ponds using a stochastic approach

The aim of the study was to evaluate the performance of Litopenaeus vannamei in an intensive photo‐heterotrophic hypersaline system with minimal seawater replacement, and establish relationships between parameters of a stochastic production model and relevant water quality variables. Six experimental 1000 m² lined ponds were stocked at a density of 120 shrimp m^?2 for a 105‐day trial. Salinity increased from 37 to 45 ± 2 g/L, and the water level was maintained with the weekly addition of filtered seawater, equivalent to 1.6% per day. The stochastic model predicted that, at harvest, there is 95% confidence that the system produces between 12.1 and 14.7 t/ha with a mean final individual weight of 13.1 g and a mean survival of 84.2%. Sensitivity analyses showed that dissolved oxygen and individual final weight of shrimp were the main variables influencing yield variance. Nitrogenous compounds were maintained between optimal cultivation levels (NH₃–NH₄⁺ = 0.73 ± 0.43 mg/L, N–NO₂^? = 0.09 ± 0.05 mg/L, N–NO₃^? = 3.22 ± 0.11 mg/L). Heterotrophic bacteria (6.6 ± 3.4 × 10⁵ CFU/ml) and chlorophyll‐α concentration (108.5 ± 80.2 μg/L) showed a similar development pattern, indicating a strong relationship between bacteria and microalgae during cultivation. Vibrio spp. concentrations were low (1.24 ± 1.42 × 10³ CFU/ml). It was shown that the photo‐heterotrophic system could be used in hypersaline conditions, typical of semi‐arid regions, to consistently produce between 12.1 and 14.7 t/ha in 15 weeks.     

Histomorphological changes between short and long days in ovary guanacos (Lama guanicoe)

This is the first morpho-histological comparison of guanaco ovaries between reproductive (long-days) and non-reproductive (short-days) seasons, and oestrogen receptor-alpha (ERα) and beta (ERβ) detection. Different stages of follicle development were found in the cortical area, but no corpus luteum was detected. The size and frequency of antral follicles and large atretic follicles were higher in long-day ovaries than short-days, consistent with ovarian activity in this season. Differential expression of ERα and ERβ was observed in follicles at different stages of development between short and long days. These data reveal histological and molecular differences between reproductive and non-reproductive seasons of guanaco ovaries.     

Comparative efficacy of two single-dose bacterins in the control of Mycoplasma hyopneumoniae in swine raised under commercial conditions in Brazil

A field study was conducted in Brazil to evaluate the efficacy of single vaccination of pigs with two bacterins to prevent Mycoplasma hyopneumoniae lung lesions. The first (T1) treatment group (174 pigs) was injected with 2 mL of saline solution; group T2 (177 pigs) with 2 mL of bacterin A, and group T3 (174 pigs) with 2 mL of bacterin B. On days-on-test (DOT) 0, 35, 66, 97 and 125, blood samples and tonsil swabs were collected from selected pigs for antibody determination (indirect ELISA) and PCR assay for the presence of M. hyopneumoniae. Pigs were slaughtered on DOT 126-129 and lung lesions were scored blindly. Bacterin A vaccinated pigs had significantly (P < or = 0.05) lower lung lesion scores (0.2%) than bacterin B (0.4%) or saline-treated pigs (1.2%); there was also a significantly lower (P < or = 0.05) number of pigs with lung lesions (27.1%), than bacterin B (38.2%) or saline-treated (55.4%) pigs. The two vaccines had similar (P>0.05) results in terms of mean weight gain, average daily weight gain, feed efficiency, frequency of PCR positives, and there was similar antibody conversion (ELISA). It was concluded that although the productivity parameters and antibody conversions were similar, bacterin A was more effective in preventing and reducing the severity of lung lesions than bacterin B.     

Conservation tillage: Short- and long-term effects on soil carbon fractions and enzymatic activities under Mediterranean conditions

Short- and long-term field experiments are necessary to provide important information about how soil carbon sequestration is affected by soil tillage system; such systems can also be useful for developing sustainable crop production systems. In this study, we evaluated the short- and long-term effects of conservation tillage (CT) on soil organic carbon fractions and biological properties in a sandy clay loam soil. Both trials consisted of rainfed crop rotation systems (cereal–sunflower–legumes) located in semi-arid SW Spain. In both trials, results were compared to those obtained using traditional tillage (TT). Soil samples were taken in flowering and after harvesting of a pea crop and collected at three depths (0–5, 5–10 and 10–20 cm). The soil organic carbon fractions were measured by the determination of total organic carbon (TOC), active carbon (AC) and water soluble carbon (WSC). Biological status was evaluated by the measurement of soil microbial biomass carbon (MBC) and enzymatic activities [dehydrogenase activity (DHA), o-diphenol oxidase activity (DphOx), and β-glucosidase activity (β-glu)].The contents of AC and MBC in the long-term trial and contents of AC in the short-term trial were higher for CT than TT at 0–5 cm depth for both sampling periods. Furthermore, DHA and β-glucosidase values in the July sampling were higher in the topsoil under conservation management in both trials (short- and long-term). The parameters studied tended to decrease as depth increased for both tillage system (TT and CT) and in both trials with the exception of the DphOx values, which tended to be higher at deeper layers.Values of DHA and β-glu presented high correlation coefficients (r from 0.338 to 0.751, p ≤ 0.01) with AC, WSC and TOC values in the long-term trial. However, there was no correlation between either TOC or MBC and the other parameters in the short-term trial. In general, only stratification ratios of AC were higher in CT than in TT in both trials. The results of this study showed that AC content was the most sensitive and reliable indicator for assessing the impact of different soil management on soil quality in the two experiments (short- and long-term).Conservation management in dryland farming systems improved the quality of soil under our conditions, especially at the surface layers, by enhancing its storage of organic matter and its biological properties, mainly to long-term.     

Microhabitat effects on herbaceous nutrient concentrations at the community and species level in Mediterranean open woodlands: the role of species composition

The presence of a woody canopy in open oak woodlands affects not only the nutrition but also the species composition of the herbaceous community. Yet, the contribution of both effects (changes in nutrient concentrations and species composition) to total resources that are captured by the herbaceous community is not well understood. We assessed the mineral nutrition (N, P, K and Ca) of three herbaceous species and the herbaceous community as well as the species composition in contrasting microhabitats (beneath trees, beneath a leguminous shrub and in open spaces). Both trees and shrubs increased the nutrient concentrations of the herbaceous species that were studied, except for Taraxacum officinale. Their effects were less consistent when the entire community was considered and depended upon the nutrient being analysed. Species richness and N, P and K concentrations were positively associated, suggesting that more nutrients are captured by the herbaceous community as diversity increases. Our results suggest a close relationship between species composition and nutritional value at the community level that may explain the discrepancies observed between both levels of analysis (species vs. community). Thus, farm-level strategies based on the whole herbaceous community may overlook processes operating at the species level, which can be relevant to achieve sustainable management.     

A monolithic photovoltaic-photoelectrochemical device for hydrogen production via water splitting

Direct water electrolysis was achieved with a novel, integrated, monolithic photoelectrochemical-photovoltaic design. This photoelectrochemical cell, which is voltage biased with an integrated photovoltaic device, splits water directly upon illumination; light is the only energy input. The hydrogen production efficiency of this system, based on the short-circuit current and the lower heating value of hydrogen, is 12.4 percent.     

Effect of cropping systems and crop successions on fumonisin levels in corn from Northern Paraná State,Brazil

In this study the effect of different cropping systems and crop successions was evaluated on natural Fusarium sp. contamination and fumonisin levels in corn. The cropping systems consisted of a conventional and no-tillage area cultivated with corn in the summer following either oats or fallow in the winter (2006 and 2007 growing seasons). In addition, the effect of applying nitrogen fertilizer (0, 22.5, 45.0, 90.0 and 90.0 kg ha⁻¹ nitrogen supplemented with potassium oxide) on fumonisin contamination was evaluated in the 2006 growing season. Fusarium sp. was detected in 90% samples in 2006 and in 100% samples in 2007. In both growing seasons, no-till corn following oats showed the highest mean fumonisin levels and differed significantly (P < 0.05) from all the others (2006) and from conventional till corn following either oats or fallow in the winter (2007). Fumonisin levels ranged from 0.13 to 19.52 μg g⁻¹ (mean 6.97 μg g⁻¹) and from 3.70 to 7.75 μg g⁻¹ (mean 6.29 μg g⁻¹) in no-till corn following oats from the 2006 and 2007 growing seasons, respectively. Plots treated with 0 kg ha⁻¹ and 22.5 kg ha⁻¹ nitrogen showed the highest mean fumonisin levels and differed significantly from those with 45.0 and 90 kg ha⁻¹ nitrogen. Fumonisin levels correlated negatively (P < 0.05) with the nitrogen fertilization rates. Although no-till is advantageous from a soil conservation standpoint, it may enhance the potential for fumonisin contamination in corn.     

Genomic characterization of H1N2 swine influenza viruses in Italy

Three subtypes (H1N1, H1N2, and H3N2) are currently diffused worldwide in pigs. The H1N2 subtype was detected for the first time in Italian pigs in 1998. To investigate the genetic characteristics and the molecular evolution of this subtype in Italy, we conducted a phylogenetic analysis of whole genome sequences of 26 strains isolated from 1998 to 2010. Phylogenetic analysis of HA and NA genes showed differences between the older (1998-2003) and the more recent strains (2003-2010). The older isolates were closely related to the established European H1N2 lineage, whereas the more recent isolates possessed a different NA deriving from recent human H3N2 viruses. Two other reassortant H1N2 strains have been detected: A/sw/It/22530/02 has the HA gene that is closely related to H1N1 viruses; A/sw/It/58769/10 is an uncommon strain with an HA that is closely related to H1N1 and an NA similar to H3N2 SIVs. Amino acid analysis revealed interesting features: a deletion of two amino acids (146-147) in the HA gene of the recent isolates and two strains isolated in 1998; the presence of the uncommon aa change (N66S), in the PB1-F2 protein in strains isolated from 2009 to 2010, which is said to have contributed to the increased virulence. These results demonstrate the importance of pigs as mixing vessels for animal and human influenza and show the presence and establishment of reassortant strains involving human viruses in pigs in Italy. These findings also highlighted different genomic characteristics of the NA gene the recent Italian strains compared to circulating European viruses.     

Performance of Prunus rootstocks for apricot in Mediterranean conditions

The influence of five rootstocks (Evrica, Krymsk^® 86, Torinel, PAC 00-08 and PADAC 01-47) on flowering, fruit set, trunk cross-sectional area, yield efficiency and fruit quality parameters of apricot cultivars (Prunus armeniaca L.) grown in a Mediterranean agro-climatic environment was evaluated. The five rootstocks were grafted with ‘E-101’ and ‘E-404’ apricot cvs., and established in an experimental orchard in the Region of Murcia (South-eastern of Spain) in 2004. Rootstock had no significant influence on the number of flowers but affected fruit set. Evrica, PAC 00-08 and PADAC 01-47, induced a higher percentage of fruit set on the apricot cultivar ‘E-101’. The greatest TCSA was exhibited with Torinel, Evrica and PADAC 01-47. The yield efficiency was significantly greater on PADAC 01-47, because of its higher yield and cumulative production compared with the other rootstocks. Thus, differences in precocity among rootstocks became evident, PADAC 01-47 being the most efficient rootstock for the first bearing years. The fruit quality traits were also significantly affected by rootstocks. In the case of ‘E-101’, the highest fruit weight was induced by Evrica, Krymsk^® 86 and Torinel. In relation to fruit size, the smallest equatorial, suture and polar diameters were produced by fruit on PADAC 01-47 for both cultivars. The highest firmness was induced by PAC 00-08 for ‘E-101’, while in ‘E-404’ the highest firmness was induced by PADAC 01-47. The colour of fruit was also affected by the rootstock. The brightest coloured skin (high L* values) was found on Evrica, PADAC 01-47, Torinel and Krymsk^® 86. The fruit weight was positively correlated with pulp yield and negatively correlated with TCSA. According to these results, higher fruit quality was found on PADAC 01-47 and Evrica.