Stocking Density for Nursery Production of Redclaw Crayfish,Cherax quadricarinatus,in a Recirculating System

Redclaw crayfish, Cherax quadricarinatus, early juveniles were reared at different stocking densities in a closed recirculation system using 12-L plastic containers as rearing tanks. Initial stocking densities were 1.0, 1.5, 2.0, 2.5, and 3.0 per liter (66, 89, 111, 133, and 156 crayfish/m², respectively). Rearing period was 42 days. Each density was tested with five replicates. Shelter (0.112 m²) was added to double the surface area of rearing tanks. Animals were fed ad libitum twice a day with a commercial diet containing 35% crude protein. There were no significant differences (P < 0.05) in length and specific growth rate (SGR) among stocking densities. Final weight and daily weight gain, however, were significantly higher at the density of 66 per m² (1.0 per liter). Total biomass at harvest increased with density. Survival was affected by stocking density from day 28 onward, decreasing with density from 62.7 ± 7.6% obtained at 66 crayfish/m² to 44.85 ± 8.18% at 156 crayfish/m².     

Multiple introductions of serotype O foot-and-mouth disease viruses into East Asia in 2010–2011

Foot-and-mouth disease virus (FMDV) is a highly contagious and genetically variable virus. Sporadic introductions of this virus into FMD-free countries may cause outbreaks with devastating consequences. In 2010 and 2011, incursions of the FMDV O/SEA/Mya-98 strain, normally restricted to countries in mainland Southeast Asia, caused extensive outbreaks across East Asia. In this study, 12 full genome FMDV sequences for representative samples collected from the People’s Republic of China (PR China) including the Hong Kong Special Administrative Region (SAR), the Republic of Korea, the Democratic People’s Republic of Korea, Japan, Mongolia and The Russian Federation were generated and compared with additional contemporary sequences from viruses within this lineage. These complete genomes were 8119 to 8193 nucleotides in length and differed at 1181 sites, sharing a nucleotide identity ≥ 91.0% and an amino acid identity ≥ 96.6%. An unexpected deletion of 70 nucleotides within the 5′-untranslated region which resulted in a shorter predicted RNA stem-loop for the S-fragment was revealed in two sequences from PR China and Hong Kong SAR and five additional related samples from the region. Statistical parsimony and Bayesian phylogenetic analysis provide evidence that these outbreaks in East Asia were generated by two independent introductions of the O/SEA/Mya-98 lineage sometime between August 2008 and March 2010. The rapid emergence of these viruses from Southeast Asia highlights the importance of adopting approaches to closely monitor the spread of this lineage that now poses a threat to livestock industries in other regions.     

Adaptation and evaluation of a rapid test for the diagnosis of sheep scrapie in samples of rectal mucosa.

In recent publications, it was shown that disease-associated prion protein (PrP(d)) accumulates in the lymphoid tissue of the rectal mucosa of a high proportion of scrapie-infected sheep at clinical and preclinical stages, regardless of several host factors; PrP(d) can also be detected in biopsy specimens of rectal mucosa, with an increased probability proportional to age or incubation period and with an efficiency almost identical to that of tonsil biopsies. Rectal biopsies have the advantages of providing higher numbers of lymphoid follicles and of being simpler to perform, which makes them suitable for scrapie screening in the field. In biopsy samples, PrP(d) could be demonstrated by immunohistochemical (IHC) and Western immunoblotting methods, and the purpose of the present study was to optimize and evaluate a "rapid test" for the diagnosis of scrapie in rectal biopsy samples. The HerdChek CWD (chronic wasting disease) antigen EIA (enzyme immunoassay) test was chosen and, once optimized, provided specificity and sensitivity figures of 99.2% and 93.5%, respectively, compared with IHC results in the same samples obtained at a postmortem. The sensitivity of the assay increased from 82.1%, when a single rectal mucosa sample was tested to 99.4% for those sheep in which 3 or more samples were analyzed. Similarly, sensitivity values of the HerdChek CWD antigen EIA test on biopsy samples increased from 95% to 100% for sheep subjected to 1 or 2 sequential biopsies 4 months apart, respectively. Thus, a preclinical diagnosis of scrapie in live sheep can be achieved by a combination of a simple sampling procedure, which can be repeated several times with no detrimental effect for the animals, and a rapid and efficient laboratory method.     

Sustained mahogany (Swietenia macrophylla) plantation heartwood increment

In a search for an increment-based rotation for plantation mahogany (Swietenia macrophylla King), heartwood volume per tree was regressed on DBH (trunk diameter outside bark at 1.4 m above the ground) and merchantable height measurements. We updated a previous study [Wadsworth, F.H., González González, E., Figuera Colón, J.C., Lugo Pérez, J., 2003. Fifty-nine year performance of planted big-leaf mahogany (S. macrophylla King) in Puerto Rico. In: Lugo, A. Figueroa Colón, J.C., Alayón, M. (Eds.), Big-leaf Mahogany, Genetics, Ecology, and Management. Springer-Verlag, New York, pp. 343–357] and determined heartwood volume increment in a plantation between the 40th and 69th years. Although DBH growth rate declined with age, that for heartwood increased throughout the entire 69 years. This, with expected growing value per unit of heartwood volume with tree size, presents incentives for long rotations.     

Yield and Osmotic Adjustment Capacity of Barley Under Terminal Water-Stress Conditions

This paper reports the influence of the osmotic adjustment capacity and turgor potential (TP) on tolerance to drought in 12 cultivated genotypes, six breeding lines and six cultivars of barley (Hordeum vulgare L.) under terminal water‐stress conditions. When the crops reached the flag leaf stage, half of the experimental plots in which they were grown were submitted to water stress treatment and the remainder maintained under optimal irrigation conditions. Differences were seen in the osmotic adjustment, relative water content (RWC) and water potential (WP) of the different genotypes. Two of the breeding lines showed the greatest osmotic adjustment capacities, maintaining their TPs better than the other genotypes studied. A positive, significant correlation was found between yield and osmotic adjustment capacity, RWC and WP under water‐stress conditions. Osmotic adjustment capacity and TP were linearly related, indicating that as water stress increases osmotic adjustment favours the maintenance of higher TPs. Significant correlations were found between osmotic adjustment capacity and grain filling rate and grain yield. Under conditions of terminal water stress, yield was negatively correlated with the number of days to ear emergence; no correlation was found between osmotic adjustment capacity and earliness. Early ear emergence, a good osmotic adjustment capacity and high RWC values all contributed to yield increases under terminal water‐stress conditions.     

Laboratory methods for the estimation of infiltration rate of soil crusts in the Tabernas Desert badlands

Soil crusting is a crucial factor for runoff generation in the Tabernas Desert badlands; however, very few methods have been developed for the measurement of infiltration in crusts, which are often distributed on steep slopes where experimental devices are very difficult to install, making measurement difficult. We have used the trickle irrigation (TI) method and mini-disk infiltrometers (MDI) in the laboratory to measure steady infiltration rate under nearly saturated condition and tensions, respectively, in soil crust samples removed from the field. Steady infiltration rate under tensions were performed at three water pressure heads (h=−0.5, −2.0, and −6.0 cm).Steady infiltration rate of soil crusts in the Tabernas Desert badlands ranged from 21.3 to 30.7 mm h⁻¹ measured by TI method. Steady infiltration rate under tensions decreased with increasing tensions; it was 9.9–18.4 mm h⁻¹, 0.4–5.7 mm h⁻¹, and 0.2–3.3 mm h⁻¹ at −0.5-, −2.0-, and −6.0-cm pressure heads, respectively. Steady infiltration rate measured by TI method and that at a tension of 0.5 cm by the MDI is consistent with the results from the previous simulated rainfall studies in the same soil crust surfaces, suggesting that the TI and MDI methods may be potentially a useful lab measurement for approximating field infiltration rate.     

Upper critical level of copper to alfalfa,in ten Chilean soils

A pot-experiment to determine the Cu upper critical level (UCL) in some representative Chilean soils using alfalfa plants as indicators was carried out at La Platina Experimental Station from 1988 to 1989. Those soils having an abundant clay fraction dominated by 2:1 minerals and/or high organic matter contents retained Cu very strongly showing low Cu toxicity and high Cu-UCL. Reversely, those soils having few clay minerals or abundant ones dominated by 1:1 minerals and/or low organic matter contents showed weak Cu retention giving pronounced toxic effects reflected by low Cu-UCL values. Growth depletion was related to increased Cu content in the aerial biomass reflecting an additional Cu uptake by roots and its translocation into the aerial part of the plants; normal plants were associated to normal Cu contents in tissues.

     

Prolamin Analysis of Progenies from Androgenetic Plants of Triticale

The present work reports results of the analysis of variability of prolamins in five breeding lines of triticale and 61 androgenetic progenies obtained from them by in vitro culture of the anthers. The phenotypic analysis of the prolamins showed heterogeneity even between seeds harvested from the same plant regenerated by in vitro culture. The variability of prolamins in this material could be, perhaps, explained under different hypotheses: unreduced microspores, embryo fusion. The percentage of androgenetic plants which generated uniform progenies for the prolamins was 14.7. The plants obtained by in vitro culture showed a significant increase of the phenotypic variability for both specific bands and patterns of prolamins as compared with the parental materials. Some plants showed missing groups of prolamins in their electrophoretic profiles, which completely affected specific regions of the proteinogram. This could be explained by gametoclonal variation based on either structural rearrangements, or aneuploidy affecting chromosomes carrying genes involved in the expression of prolamins.     

Cytotoxicity and antileishmanial activity of Annona muricata pericarp

Hexane, ethyl acetate and methanol extracts of Annona muricata pericarp were tested in vitro against Leishmania braziliensis and L. panamensis promastigotes, and against cell line U-937. The ethyl acetate extract was more active than the other extracts and even of Glucantime used as reference substance. Its fractionation led to the isolation of three acetogenins--annonacin, annonacin A and annomuricin A.     

Improving postharvest resistance in fruits by external application of trans-resveratrol

As it is well-known, one of the main problems of modern agriculture is the postharvest fruit losses due to pathogen's attack and natural senescence during storage. Well established solutions to improve this situation, such as, for example, storage under controlled conditions and the use of synthetic pesticides, are not free of problems due to human health risks and environmental effects caused by chemical pesticides. A new strategy to solve these problems consists of developing methods to improve the natural plant resistance by using, upon their identification, the plant's own defense molecules, in other words, applying methods based on the plant's own natural processes of pest suppression to control spoilage. This requires the identification of components of the natural defense response in plants, which, in turn, demands highly sensitive, fast, and versatile analytical methods especially for trace, nonvolatile, compounds. In this work a laser-based technique has been applied for screening the postharvest elicitation of resveratrol by Botrytis cinerea in grapes. Besides antifungal character, resveratrol is known to present important antioxidant properties, which could also have positive effects on fruit conservation during storage. Consequently, several experiments were carried out in which exogenous application of resveratrol to several fruits maintained their postharvest quality. The quality of both resveratrol-treated and untreated fruits has been studied by the assessment of the biochemical composition and sensory analysis. Indeed, the present work demonstrates that the external application of resveratrol does not alter the sensorial and biochemical properties of the fruit.