Immunostimulatory effect of salmon prolactin on expression of Toll-like receptors in <Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis> infected with <Emphasis Type="Italic">Piscirickettsia salmonis</Emphasis>

In aquaculture, antibiotics are the traditional treatment used against bacterial infections. However, their use has increasingly come into question given their effects on fish and, possibly, on human health. Consequently, there is interest in developing alternative treatments aimed at stimulating the innate immune response of fish, which is the first line of defense against pathogens. In relation to this, the Toll-like receptors (TLR) aid in the selective identification of pathogens. The present study evaluated immunostimulatory activity of prolactin (PRL) hormone on expression levels of TLR1, 9, and 22, MyD88, and IL-1β during in vitro infection with the fish pathogen Piscirickettsia salmonis, in primary cultures of Oncorhynchus mykiss head kidney cells. Results indicated that PRL increased expression of TLRs and MyD88 during the first hours of bacterial infection, while a constant increase in expression was found for IL-1β. These findings suggest that PRL indirectly modulates expression of TLRs by activating expression of suppressors of cytokine signaling, thereby regulating immune response over long periods of time during bacterial infection.     

Combined and individual effects of a nucleopolyhedrovirus and azadirachtin on the mortality and maize-leaf consumption of Spodoptera frugiperda

The combined and alone effects of azadirachtin (AZA) and Spodoptera frugiperda multicapsid nucleopolyhedrovirus (SfMNPV) on the mortality and food consumption of third instar S. frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) were evaluated under laboratory conditions using maize leaf bioassays. The LC₅₀ values for SfMNPV and AZA were determined to be 1.30x10⁶ viral occlusion bodies (OBs)/ml and 6.54 mg l ^-1 at 192 h and 144 h after treatment, respectively. These LC₅₀ values were estimated for 4 days of continuous exposure. Although the interaction of SfMNPV with AZA increased the percentage of mortality observed in most of the cases, only one mixture (1x10⁶ OBs/ml + 5 mg l ^-1) resulted in a synergistic effect on mortality of S. frugiperda. Application of SfMNPV (1x10⁶ OBs/ml), AZA (0.5, 0.1 or 0.25 mg l ^-1) or SfMNPV–AZA mixtures resulted in a significant reduction in the maize-leaf piece consumption of larvae treated in the third instar across the experiment, by onefold, 2–5-fold, and 2–3-fold, respectively, compared with the control. However, the interaction of two SfMNPV–AZA mixtures (1x10⁶ OBs/ml + 5 mg l ^-1 and 1x10⁶ OBs/ml + 10 mg l ^-1) did not reduce the food consumption compared with AZA alone. It was concluded that SfMNPV–AZA mixtures require validation to determine whether this mixture may offer a valuable means of improving the efficacy of the SfMNPV.     

Root proliferation in native perennial grasses of arid Patagonia,Argentina

Pappophorum vaginatum is the most abundant C4perennial grass desirable to livestock in rangelands of northeastern Patagonia,Argentina.We hypothesized that(1)defoliation reduce net primary productivity,and root length density and weight in the native species,and(2)root net primary productivity,and root length density and weight,are greater in P.vaginatum than in the other,less desirable,native species(i.e.,Aristida spegazzinii,A.subulata and Sporobolus cryptandrus).Plants of all species were either exposed or not to a severe defoliation twice a year during two growing seasons.Root proliferation was measured using the cylinder method.Cylindrical,iron structures,wrapped up using nylon mesh,were buried diagonally from the periphery to the center on individual plants.These structures,initially filled with soil without any organic residue,were dug up from the soil on 25April 2008,after two successive defoliations in mid-spring 2007.During the second growing season(2008–2009),cylinders were destructively harvested on 4 April 2009,after one or two defoliations in midand/or late-spring,respectively.Roots grown into the cylinders were obtained after washing the soil manually.Defoliation during two successive years did reduce the study variables only after plants of all species were defoliated twice,which supported the first hypothesis.The greater root net primary productivity,root length density and weight in P.vaginatum than in the other native species,in support of the second hypothesis,could help to explain its greater abundance in rangelands of Argentina.     

Changes in cell wall polysaccharides and cell wall degrading enzymes during ripening of Fragaria chiloensis and Fragaria ×ananassa fruits

Chilean strawberry (Fragaria chiloensis) is arising as a new fruit crop that can diversify the world supply of berries. Fruit softening is thought to be linked to an extensive modification of pectin and hemicellulosic cell wall fractions which in turn is determined to a great extent by the action of some cell wall-modifying enzymes. The objective of this work was to compare cell wall changes and the enzyme activities of pectin methylesterase (PME), polygalacturonase (PG), endoglucanase (EGase), α-arabinofuranosidase (AFase), β-galactosidase (βGal), and β-xylosidase (βXyl) between F. chiloensis and Fragaria ×ananassa (cv. Chandler) at three fruit developmental stages: large green (LG), turning (T) and ripe (R). A rapid decrease in fruit firmness between LG and T stages was observed in both species; nevertheless firmness reduction in F. chiloensis was steeper than in F. ×ananassa. This could be related to a faster loss of HCl-soluble polymers (HSP fraction) presented in F. chiloensis fruit. However, commercial F. ×ananassa showed a greater depolymerization of HSP polymers than F. chiloensis. With the exception of PME, the activity of all assayed enzymes was higher in F. chiloensis than in F. ×ananassa fruits. The role of PG and EGase seems to be central in both species: these enzymes are correlated to the decrease in the content of HSP and NaOH-soluble polymers (NSP fraction), respectively. In addition, activity levels of βGal and βXyl were significantly correlated with fruit firmness reduction in F. chiloensis and F. ×ananassa, respectively.     

Antifungal activity of extracts of Rosmarinus officinalis and Thymus vulgaris against Aspergillus flavus and A. ochraceus

The antifungal activity of ethanolic extracts of Rosmarinus officinalis and Thymus vulgaris were tested against strains of Aspergillus flavus and A. ochraceus, since these two species are common contaminants of cereals and grains and are able to produce and accumulate mycotoxins. The methodology used is based on measuring the inhibition halos produced by discs impregnated with the extracts and establishing their Minimum Inhibitory Concentration (MIC) as well as the Minimum Fungicide Concentration (MFC). The results obtained suggest that the assayed extracts affect the proper development of A. flavus and A. ochraceus; leading to a lower MIC (1200 ppm) and MFC (2400 ppm) for T. vulgaris extract against A. ochraceus than against A. flavus. The results show, that the extracts of Rosmarinus officinalis and Thymus vulgaris used at low concentrations could have significant potential for the biological control of fungi in foodstuffs.     

Kernel Microstructure of Latin American Races of Maize and Their Thermal and Rheological Properties

Seventy‐one races of maize representing races from Latin America were analyzed for microstructural features such as the degree of compaction of the endosperm cell bodies, starch granule size and morphology, and hard‐soft endosperm relationship. Flours were analyzed using rapid visco analysis and differential scanning calorimetry. Compaction grade was the most important microstructural feature of the maize kernels that related to thermal and rheological properties. Highly compact kernels developed low peak and final viscosities; small, polygonal starch granules; and required more time and higher temperature to gelatinize. The opposite was the case for less compact kernels. This indicates that the characteristic protein matrix of highly compact kernels represents a physical barrier to water migration into the granules, retarding the gelatinization process.     

Streptococcosis on a red tilapia, Oreochromis sp., farm: a case study

A commercial red tilapia farm was diagnosed with Streptococcus agalactiae infection using histopathology, microbiology and immunohistochemistry. One hundred fish were randomly taken from different weight/age groups including broodstock, market fish (larger than 150 g), on-growing fish between 20 and 150 g, juveniles and larvae. Fish were clinically examined, anaesthetised and necropsied. Samples were taken from brain, liver, spleen, eyes and kidney for microbiology. All organs were processed for histopathology and an indirect immunoperoxidase test (IIP). Organs from wild fish and birds found in close proximity to the farm were also sampled for microbiology and IIP. The prevalence of lesions or infection found by IIP, histopathology and microbiology was 16%, 29% and 7% respectively. Clinical disease, lesions or infection were not seen in larvae or juveniles. By contrast, infection and disease were found in fish larger than 20 g, suggesting that the condition was linked to the intensive culture conditions of broodstock, on-growing and market fish. S. agalactiae was not found in wild fish, or in birds, by microbiology and IIP.     

Growth and performance of the whiteleg shrimp Penaeus vannamei (Boone) cultured in low‐salinity water with different stocking densities and acclimation times

We evaluated the performance of whiteleg shrimp Penaeus vannamei (Boone, 1931) in response to different stocking densities and acclimation periods. Shrimp postlarvae were acclimated from seawater (30 g L^?1) to low‐salinity well water (<1.0 g L^?1) at a constant hourly reduction rate of 40, 60, 80 and 100 h. After acclimation to low‐salinity well water, postlarvae from each acclimation time treatment were stocked in three replicate tanks at densities of 50, 100, 150 or 200 shrimps m^?2 for 12 weeks of growth. Salinity averaged <1.0 g L^?1 for each growth study. The different treatments resulted in significant differences in both the final body weight and the survival rate (SR). Shrimp acclimated for 100 h showed substantially improved survival (83%) relative to shrimp acclimated for shorter periods. Shrimp yields for all cultured periods ranged from 0.32 kg m^?2 in tanks stocked at 50 m^?2 to 1.14 kg m^?2 in tanks stocked at 200 m^?2. We conclude that whiteleg shrimp can be successfully grown in low‐salinity well water, and that the growth, production output and SRs are significantly higher when shrimp are acclimated for longer periods.     

Mycosporine-Like Amino Acids from Marine Resource

In the last 10 years, a great number of publications (both regular papers and reviews) have been published on the interesting molecules—mycosporine-like amino acids (MAAs). Despite significant advances in the research of MAAs, current overviews in the recent publications involving MAA research still need reporting. The aim of this Special Issue is to join, as an interdisciplinary approach, the photochemical and photobiological aspects, with emphasis on new natural resources to obtain both algae and zooplankton MAAs, advances in methodology of extraction and chemical identification of new MAAs. Finally, this Special Issue reviews the bioactivities of MAAs including UVR screen, antioxidant, immunostimulant, growth factor, DNA protection, inhibition of collagenase, elastase and hyaluronidase, and anti-photoaging, among others, and their potential use as nutracosmeceutic molecules (i.e., oral and topic photoprotector).