Evaluation of the immune response in rainbow trout fry,Oncorhynchus mykiss (Walbaum), after waterborne exposure to Flavobacterium psychrophilum and/or hydrogen peroxide

The immune response in rainbow trout fry against Flavobacterium psychrophilum was elucidated using an immersion‐based challenge with or without prior exposure to hydrogen peroxide (H₂O₂). Samples were taken from the head kidney 4, 48, 125 and 192 h after immersion, and the regulation of several genes was examined. Bacterial load was assessed based on the presence of 16S rRNA and correlated with gene expression, and the levels of specific antibodies in the blood were measured 50 days post‐infection. Separately, both H₂O₂ and F. psychrophilum influenced gene expression, and pre‐treatment with H₂O₂ influenced the response to infection with F. psychrophilum. Pre‐treatment with H₂O₂ also affected correlation between gene regulation and pathogen load for several genes. A delay in antibody production in H₂O₂‐treated fish in the early phase of infection was indicated, but H₂O₂ exposure did not affect antibody levels 50 days post‐infection. An increasing amount of F. psychrophilum 16S rRNA was found in the head kidneys of infected fish pre‐treated with H₂O₂ relative to the F. psychrophilum group. The results show that a single pre‐treatment with H₂O₂ impairs the response against F. psychrophilum and may intensify infection.     

Associations between lobster phyllosoma and gelatinous zooplankton in relation to oceanographic properties in the northern Gulf of Mexico

Lobster phyllosoma are known to associate with large cnidarian medusae; however, direct quantitative observations are difficult because gelatinous zooplankton are extremely fragile, and the phyllosoma easily detach from their host when sampled by plankton nets. We provide the first large scale quantitative information of the distribution of this association using an in situ imaging system, with synoptic measurements of water column properties. All phyllosoma were identified as slipper lobsters (Scyllarus chacei) and were associated with previously unreported “hosts” such as small hydromedusae, doliolids, and siphonophores in the northern Gulf of Mexico. Along the shelf, phyllosoma were more likely to be present at greater depths and higher salinities. Approximately 30% of the 347 lobster phyllosoma imaged were attached to at least one gelatinous organism, and salinity and depth were positively related to the probability of attachment on 30 October, but did not show a significant relationship for the other days of sampling. Many of the phyllosoma were larger than the gelatinous organisms to which they were attached, and some gelatinous zooplankton showed damage likely from feeding by the phyllosoma. In this coastal environment, gelatinous zooplankton tended to be more abundant in the same offshore region where phyllosoma occurred, so these gelatinous “hosts” may provide a steady food supply in the more oligotrophic waters on the outer shelf. Similar complex interactions among zooplankton may influence the life histories of other species, hindering our ability to forecast ecosystem level processes until the population level consequences of species interactions are fully understood.     

Choice preference of diets with different protein levels depending on water temperature in Nile tilapia

This study tested a choice feeding model for Nile tilapia that allowed the selection of a higher or lower protein content in the diet depending on water temperature. Nile tilapia were reared in twelve 200-L tanks for 63 days with 12 fish (body weight 38 g/fish at start) per tank. Two temperatures (22 or 30°C) and two color combinations (yellow and red each) for a two-component diet containing 30% (low) and a 38% (high) crude protein content based on dry matter were used. High water temperature (30 vs. 22°C) resulted in a significantly higher feed rate (1.93 ± 0.123 and 1.26 ± 0.100%, respectively), body weight gain (39.3 ± 4.29 and 4.75 ± 0.66 g, respectively), final body weight (70.3 ± 9.31 and 43.0 ± 7.49 g, respectively), and feed efficiency (55.4 ± 6.09 and 14.6 ± 2.86%, respectively), as well as protein efficiency ratio (1.687 ± 0.186 and 0.450 ± 0.087, respectively), regardless of color codes. No significant differences of color codes on growth parameters, body composition, and fatty acid profile were seen. Higher water temperature (30 vs. 22°C) only had an effect on percentage-specific fatty acids of total fatty acids of the whole body (biggest difference: C16:0, 20.5 ± 1.00 and 17.4 ± 1.11%, respectively). Therefore, water temperature clearly influences growth and fatty acid composition of the body.     

Pharmacokinetics and bioavailability of flumequine and oxolinic acid after various routes of administration to Atlantic salmon in seawater

The present preclinical study was performed to investigate the pharmacokinetics of flumequine in Atlantic salmon (Salmo salar L.) in seawater after administration of different doses and dosage formulations. Flumequine was administered intravenously (dose 4.9 mg/kg fish) and orally from the drug delivery system Aqualets as Apoquin 5 g/kg (dose 25 mg/kg) and 10 g/kg (dose 50 mg/kg), respectively. Experiments were carried out with oxolinic acid administered in the same way for the purpose of comparing the two compounds. The seawater temperature was 5±0.2°C in all experiments.

The pharmacokinetic calculations showed that the distribution half-life for flumequine was and for oxolinic acid . The drugs were absorbed rapidly, and flumequine reached a plasma concentration of C_max = 2.26 μg/ml after a single oral dose of 25 mg/kg, whereas oxolinic acid reached C_max = 0.99 μg/ml. The apparent bioavailability of flumequine was found to be 40–45%, whereas the apparent bioavailability of oxolinic acid varied from 25% at a dose of 50 mg to 40% at a dose of 25 mg/kg body weight of fish. The distribution profile of flumequine in the various compartment of fish appeared to be different from that of oxolinic acid. After a single oral dose (25 mg/kg) the areas under the concentration-time curves showed that flumequine was 2.3 times more concentrated in plasma and 2.6 times more concentrated in liver compared to oxolinic acid. In muscle the difference was less pronounced, flumequine being 1.4 times more concentrated than oxolinic acid.     

In Vitro Evaluation of Antioxidant Potential of the Invasive Seagrass Halophila stipulacea

Marine organisms with fast growth rates and great biological adaptive capacity might have biotechnological interests, since ecological competitiveness might rely on enhanced physiological or biochemical processes’ capability promoting protection, defense, or repair intracellular damages. The invasive seagrass Halophila stipulacea, a non-indigenous species widespread in the Mediterranean Sea, belongs to this category. This is the premise to investigate the biotechnological interest of this species. In this study, we investigated the antioxidant activity in vitro, both in scavenging reactive oxygen species and in repairing damages from oxidative stress on the fibroblast human cell line WI-38. Together with the biochemical analysis, the antioxidant activity was characterized by the study of the expression of oxidative stress gene in WI-38 cells in presence or absence of the H. stipulacea extract. Concomitantly, the pigment pool of the extracts, as well as their macromolecular composition was characterized. This study was done separately on mature and young leaves. Results indicated that mature leaves exerted a great activity in scavenging reactive oxygen species and repairing damages from oxidative stress in the WI-38 cell line. This activity was paralleled to an enhanced carotenoids content in the mature leaf extracts and a higher carbohydrate contribution to organic matter. Our results suggest a potential of the old leaves of H. stipulacea as oxidative stress damage protecting or repair agents in fibroblast cell lines. This study paves the way to transmute the invasive H. stipulacea environmental threat in goods for human health.     

Coordinated Regulation of Cold Induced Sweetening in Tetraploid Potato Families by Isozymes of UDP-Glucose Pyrophosphorylase and Vacuolar Acid Invertase

Past investigations have suggested that both UGPase and AcInv activities can be used as markers to screen genetically diverse potato clones for cold induced sweetening resistance (CIS-R). The goal of this study was to define their cooperative interaction in regulating sweetening. Inter- and intra-ploidy hybridizations of good (G) and poor (P) processing 24 or 48 chromosome potato clones were used to create 24 potato families. Potatoes were field grown and 460 progeny (≤20 each family) were stored for five months in the cold (4 C). Tubers from each progeny plant were evaluated for cold induced sweetening resistance (CIS-R) and correlated with the percentage of A-II isozymes of UDP-glucose pyrophosphorylase (UGPase; EC 2.7.7.9); and acid invertase activity (AcInv; EC 3.2.1.26). Each progeny was given a CIS-R score of 1–10 (1-most resistance, 10 least resistance). The families were grouped into four classes based on (1) high or low AcInv activity (low being a SA of 0.30 or less) (2) high or low percentage of A-II isozymes (low being 50% or less), and (3) CIS-R score. In high AcInv families, CIS-R was low regardless of the percentage of A-II isozymes present. In low AcInv activity families, there was a trend for average chip color to improve as the percentage of A-II isozymes increased from 0% to 40%. This increase in CIS-R in low AcInv families is likely due to the kinetic properties unique to the A-II forms of UGPase (principally UGP5) which limit the formation of sucrose via sucrose-6-phosphate synthase (SPS; EC 2.4.1.14). Lower concentrations of sucrose can lead to a decrease in reducing sugar production via vacuolar AcInv and lighter chip and fry colors. In selecting tetraploid parents, for the development of processing potato clones with improved CIS-R, it is recommended they have a basal AcInv SA of 0.30 or less and have A-II isozymes of UGPase.     

Augmenting Anti-Cancer Natural Products with a Small Molecule Adjuvant

Aquatic microbes produce diverse secondary metabolites with interesting biological activities. Cytotoxic metabolites have the potential to become lead compounds or drugs for cancer treatment. Many cytotoxic compounds, however, show undesirable toxicity at higher concentrations. Such undesirable activity may be reduced or eliminated by using lower doses of the cytotoxic compound in combination with another compound that modulates its activity. Here, we have examined the cytotoxicity of four microbial metabolites [ethyl N-(2-phenethyl) carbamate (NP-1), Euglenophycin, Anabaenopeptin, and Glycolipid 652] using three in vitro cell lines [human breast cancer cells (MCF-7), mouse neuroblastoma cells (N2a), and rat pituitary epithelial cells (GH4C1)]. The compounds showed variable cytotoxicity, with Euglenophycin displaying specificity for N2a cells. We have also examined the modulatory power of NP-1 on the cytotoxicity of the other three compounds and found that at a permissible concentration (125 µg/mL), NP-1 sensitized N2a and MCF-7 cells to Euglenophycin and Glycolipid 652 induced cytotoxicity.     

Transgenic mice with a reduced core body temperature have an increased life span

Reduction of core body temperature has been proposed to contribute to the increased life span and the antiaging effects conferred by calorie restriction (CR). Validation of this hypothesis has been difficult in homeotherms, primarily due to a lack of experimental models. We report that transgenic mice engineered to overexpress the uncoupling protein 2 in hypocretin neurons (Hcrt-UCP2) have elevated hypothalamic temperature. The effects of local temperature elevation on the central thermostat resulted in a 0.3 degrees to 0.5 degrees C reduction of the core body temperature. Fed ad libitum, Hcrt-UCP2 transgenic mice had the same caloric intake as their wild-type littermates but had increased energy efficiency and a greater median life span (12% increase in males; 20% increase in females). Thus, modest, sustained reduction of core body temperature prolonged life span independent of altered diet or CR.     

Onset and progression in inherited ALS determined by motor neurons and microglia

Dominant mutations in superoxide dismutase cause amyotrophic lateral sclerosis (ALS), a progressive paralytic disease characterized by loss of motor neurons. With the use of mice carrying a deletable mutant gene, expression within motor neurons was shown to be a primary determinant of disease onset and of an early phase of disease progression. Diminishing the mutant levels in microglia had little effect on the early disease phase but sharply slowed later disease progression. Onset and progression thus represent distinct disease phases defined by mutant action within different cell types to generate non-cell-autonomous killing of motor neurons; these findings validate therapies, including cell replacement, targeted to the non-neuronal cells.     

Genetic properties influencing the evolvability of gene expression

Identifying the properties of gene networks that influence their evolution is a fundamental research goal. However, modes of evolution cannot be inferred solely from the distribution of natural variation, because selection interacts with demography and mutation rates to shape polymorphism and divergence. We estimated the effects of naturally occurring mutations on gene expression while minimizing the effect of natural selection. We demonstrate that sensitivity of gene expression to mutations increases with both increasing trans-mutational target size and the presence of a TATA box. Genes with greater sensitivity to mutations are also more sensitive to systematic environmental perturbations and stochastic noise. These results provide a mechanistic basis for gene expression evolvability that can serve as a foundation for realistic models of regulatory evolution.