Chronotropic and inotropic effects of adenosine and AMP on the isolated systemic heart of Octopus vulgaris

The effect of adenosine on the function of the heart in Octopus vulgaris was studied using an isolated heart preparation. Bolus injections of adenosine or AMP (adenosine precursor) induced both positive chronotropic and inotropic effects. The maximum inotropic effect preceded the maximum chronotropic effect. The impermeable adenosine analogue 2-chloroadenosine elicited a similar effect, while the adenosine uptake blocker dipyridamole did not affect the adenosine response. These results suggest that adenosine acted extracellularly. The concentration-response curves of adenosine and AMP were also determined, by evaluating the effects on ventricular and coronary function. Under these conditions, the potent chronotropic effect elicited by both substances apparently masked or compensated for the inotropic effect, owing to the negative force-frequency relationship known to occur in the octopus heart. The AMP displayed a lower threshold than adenosine, suggesting an higher affinity for the purinergic receptors involved or a strict association between 5'-nucleotidase and the adenosine receptor on the plasma membrane

Urea Excretion and Arginase Activity as New Biomarkers for Nitrite Stress in Freshwater Aquatic Animals

Background: In recent years, the concern has been growing on increasing aquatic nitrite levels due to anthropogenic activities. Crustaceans and fish easily uptake nitrite via the chloride uptake system of gills. High nitrite body levels may interfere with nitric oxide (NO) production by nitric oxide synthase (NOS). The arginase, which catalyzes arginine conversion to ornithine and urea, is central to NO homeostasis. In vivo, changes in the arginase activity alter urea body levels and urea excretion and modulate NOS by altering arginine availability for NO synthesis. Excess arginase activity may uncouple NOS and induce oxidative stress. Methods: We tested muscle arginase activity and urea excretion in two fish species, zebrafish and convict cichlid, and the crustacean Yamato shrimp, under sub-lethal nitrite stress. Results: Exposure to nitrite (2 mM in the fish, 1 mM in the shrimp) significantly increased blood nitrite concentration in all species. Concomitantly, nitrite stress significantly increased arginase activity, urea excretion, and urea levels in the blood. In Yamato shrimp, urea levels also increased in muscle. Conclusion: Our results agree with the hypothesis that nitrite stress affects NO homeostasis by arginase stimulation and urea excretion. These parameters might function as markers of sub-lethal nitrite stress in freshwater fish and crustaceans

Presence of Gambusia affinis (Baird & Girard, 1853) in a freshwater ecosystem of Campania region (Italy)

The western mosquitofish, Gambusia affinis, is a small fish native to the southeastern United States. In the past century this species, and its congener, the eastern mosquitofish, Gambusia holbrooki, have been stocked in permanent and temporary waters throughout the world for mosquito control. These two species, very similar in appearance and biology, quickly became invasive with a strong ecological impact on ecosystems. They are considered responsible for the decline of several native amphibians and small fish in the Mediterranean region. Previous studies on European population conducted from Portugal to Greece reported the presence of only G. holbrooki in Italy, with report on Sicily (Catania) and Tuscany (Coltano) (Vidal, 2010). During an experimental trawl survey in 2010, samples of mosquito fishes were collected with nets from a pond near Cancello Arnone (Campania, Caserta, Italy). In order to define the Gambusia species, identification through dichotomous keys and DNA based methods were conducted. In particular, gonopodia morphology of preserved male individuals along with dorsal and anal fin rays were used to species differentiation (Walters and Feeman, 2000; Veenvliet, 2007), in our case giving uncertain results. For the molecular characterization, DNA from muscle tissue was isolated and two primer sets were used based on the conserved regions of the 12S and 16S rRNA loci as described by Kitano et al. (2007). PCR amplification and sequencing showed a 100% of maximum identity with G. affinis sequences in Genbank. These results, while contributing to unriddle the ambiguities in Gambusia taxonomy (see Vidal, 2010), call for further studies in order to define Gambusia affinis distribution in the Campania region and its impact on freshwater population

1,3-Butanediol Administration Increases β-Hydroxybutyrate Plasma Levels and Affects Redox Homeostasis, Endoplasmic Reticulum Stress, and Adipokine Production in Rat Gonadal Adipose Tissue

Ketone bodies (KBs) are an alternative energy source under starvation and play multiple roles as signaling molecules regulating energy and metabolic homeostasis. The mechanism by which KBs influence visceral white adipose tissue physiology is only partially known, and our study aimed to shed light on the effects they exert on such tissue. To this aim, we administered 1,3-butanediol (BD) to rats since it rapidly enhances β-hydroxybutyrate serum levels, and we evaluated the effect it induces within 3 h or after 14 days of treatment. After 14 days of treatment, rats showed a decrease in body weight gain, energy intake, gonadal-WAT (gWAT) weight, and adipocyte size compared to the control. BD exerted a pronounced antioxidant effect and directed redox homeostasis toward reductive stress, already evident within 3 h after its administration. BD lowered tissue ROS levels and oxidative damage to lipids and proteins and enhanced tissue soluble and enzymatic antioxidant capacity as well as nuclear erythroid factor-2 protein levels. BD also reduced specific mitochondrial maximal oxidative capacity and induced endoplasmic reticulum stress as well as interrelated processes, leading to changes in the level of adipokines/cytokines involved in inflammation, macrophage infiltration into gWAT, adipocyte differentiation, and lipolysis

Effects of four food dyes on development of three model species, Cucumis sativus, Artemia salina and Danio rerio: Assessment of potential risk for the environment

Food dyes, or color additives, are chemicals added to industrial food products and in domestic cooking to improve the perceived flavor and attractiveness. Of natural and synthetic origin, their safety has been long discussed, and concern for human safety is now clearly manifested by warnings added on products labels. Limited attention, however, has been dedicated to the effects of these compounds on aquatic flora and fauna. For this reason, the toxicity of four different commercially available food dyes (cochineal red E120, Ponceau red E124, tartrazine yellow E102 and blue Patent E131) was assessed on three different model organisms, namely Cucumis sativus, Artemia salina and Danio rerio that occupy diverse positions in the trophic pyramid. The evidence collected indicates that food dyes may target several organs and functions, depending on the species. C. sativus rate of germination was increased by E102, while root/shoot ratio was ∼20% reduced by E102, E120 and E124, seed total chlorophylls and carotenoids were 15–20% increased by E120 and 131, and total antioxidant activity was ∼25% reduced by all dyes. Mortality and low mobility of A. salina nauplii were increased by up to 50% in presence of E124, E102 and E131, while the nauplii phototactic response was significantly altered by E102, E120 and E124. Two to four-fold increases in the hatching percentages at 48 h were induced by E124, E102 and E131 on D. rerio, associated with the occurrence of 20% of embryos showing developmental defects. These results demonstrated that the food dyes examined are far from being safe for the aquatic organisms as well as land organisms exposed during watering with contaminated water. The overall information obtained gives a realistic snapshot of the potential pollution risk exerted by food dyes and of the different organism' ability to overcome the stress induced by contamination

Angitola lake sediments: preliminary data and biotic indices

The Angitola lake is an artificial basin located in Calabria Region, in South Italy, part of the “Natural Regional Park of Serre”. Its surface area is 1.96 km2 and it is approximately 3 km away from Sant’Eufemia gulf. The basin was created in 1966 by damming the homonymous river. Four major rivers enter the lake: three in the far southeast, the fourth, smaller and active only during the winter period, in the southwest area. The international Ramsar Convention includes the basin and surroundings; in light of the Rio Convention, its directives have been transposed in the “Birds Directive” (BD) and “Habitats Directive” (HD). The Angitola lake, entrusted to the WWF Calabria, is one of the 2299 Italian SIC (code IT9340086): this area significantly contributes in maintaining and restoring the endangered freshwater habitat listed in HD, in protecting biodiversity of the region and it is part of the Natura 2000 network. The present study is part of the Angitola FISH2O project (European Fisheries Fund/FEP code 02/BA/12) and it aimed to examine the benthic macro-invertebrates community of the southeast part of Angitola lake. The first 15 cm in depths of sediments have a very variable composition, from fine sand to mud (rich in organic matter). This variability can be explained by the different characteristic of the chosen sampling transepts. Fauna sampling, carried out by core drills and plankton nets, shows presence of Diptera and Tricoptera larvae and some Nematoda, Polichaeta and Mollusca. Preliminary conclusion is that the Angitola lake is a diversified environment in which areas with different anthropic interference are present. The benthic macro-invertebrates community might be involved by possible disturbances induced by chemicals (e.g. water pollution) and/or physical variations (e.g. high sedimentation). Medium and long-term investigations are imperative to protect and promote the lake biodiversity, to verify the effects of seasonal fluctuations and how these are related to human activities such as tourism, demographic increase and industrial activities

Probiotic modulation of the microbiota-gut-brain axis and behaviour in zebrafish

The gut microbiota plays a crucial role in the bi-directional gut–brain axis, a communication that integrates the gut and central nervous system (CNS) activities. Animal studies reveal that gut bacteria influence behaviour, Brain-Derived Neurotrophic Factor (BDNF) levels and serotonin metabolism. In the present study, we report for the first time an analysis of the microbiota–gut–brain axis in zebrafish (Danio rerio). After 28 days of dietary administration with the probiotic Lactobacillus rhamnosus IMC 501, we found differences in shoaling behaviour, brain expression levels of bdnf and of genes involved in serotonin signalling/metabolism between control and treated zebrafish group. In addition, in microbiota we found a significant increase of Firmicutes and a trending reduction of Proteobacteria. This study demonstrates that selected microbes can be used to modulate endogenous neuroactive molecules in zebrafish

Towards sustainable aquaculture systems: Biological and environmental impact of replacing fishmeal with Arthrospira platensis (Nordstedt) (spirulina)

Sustainable fish food production is crucial for aquaculture. Microalgae, such as spirulina (Arthrospira platensis), can supplement diet antioxidants or replace expensive fishmeal with high-quality proteins. In this study, we tested fish growth and wellbeing by feeding fish on a diet in which 5% of fishmeal was replaced by spirulina (SP5 diet). The low level of spirulina in the diet was intended as supplementation and was effective in ameliorating the redox state of a model fish species (juvenile Koi Carp, Cyprinus carpio L.) in a preliminary lab protocol in a six-week trial. When compared with both the control diet (no Spirulina) and a diet containing 30% spirulina replacing fishmeal (SP30 diet), SP5 was able to reduce the muscle levels of reactive oxygen species (ROS), oxidative damage, and susceptibility to oxidative stress, while increasing glutathione reductase and peroxidase activity. However, high production costs and impacts still limit the use of spirulina in fish diet. Recent studies focused on growing spirulina on urban or agro-industrial wastewater, with appropriate profiles for the alga growth. Therefore, in a circular economy context, a possibility still to be tested and exploited is feeding farmed fish with spirulina produced on output wastewater recirculated back from the same farming plant. Life Cycle Assessment (LCA) was applied to estimate the sustainability of such “circular” fish farming. The LCA ReCiPe Midpoint (H) impact assessment method was used. Firstly, the LCA environmental impacts associated with the production of spirulina grown on aquaculture wastewater as well as on the standard culture medium (Zarrouk medium) were assessed and compared by means of a “gate to gate” analysis. Then, the LCA impacts of an SP5 diet for fish, in which spirulina grown on aquaculture wastewater was used to replace 5% fishmeal (SP5ww), were compared to the diet containing spirulina grown on a standard medium (SP5st) and that one without spirulina (control diet). Results indicated that SP5ww was significantly less impacting, by avoiding the treatment and disposal of wastewater and the need for the highly impacting standard culture medium. In conclusion, the proposed approach for using spirulina in aquaculture represents a valid solution for aquaculture circular economy scenario while at the same time improving fish welfare

Probiotic modulation of the microbiota-gut-brain axis and behaviour in zebrafish

The gut microbiota plays a crucial role in the bi-directional gut–brain axis, a communication that integrates the gut and central nervous system (CNS) activities. Animal studies reveal that gut bacteria influence behaviour, Brain-Derived Neurotrophic Factor (BDNF) levels and serotonin metabolism. In the present study, we report for the first time an analysis of the microbiota–gut–brain axis in zebrafish (Danio rerio). After 28 days of dietary administration with the probiotic Lactobacillus rhamnosus IMC 501, we found differences in shoaling behaviour, brain expression levels of bdnf and of genes involved in serotonin signalling/metabolism between control and treated zebrafish group. In addition, in microbiota we found a significant increase of Firmicutes and a trending reduction of Proteobacteria. This study demonstrates that selected microbes can be used to modulate endogenous neuroactive molecules in zebrafish

Commercial Red Food Dyes Preparations Modulate the Oxidative State in Three Model Organisms (Cucumis sativus, Artemia salina, and Danio rerio)

The growing environmental spreading of food synthetic dyes and bio-colors have the potential for altering organisms’ redox states. Here, three model species for aquatic pollution trials, Cucumis sativus seeds, Artemia salina cysts, and Danio rerio embryos, were short-term exposed to a fixed concentration of the artificial red E124, and two red bio-colors, cochineal E120, and vegan red (VEGR). In the animal models, we evaluated the total reactive oxygen species (ROS) and the susceptibility to in vitro oxidative stress, and in C. sativus, H2O2 production and antioxidant capacity. We also measured organismal performance indices (routine oxygen consumption in the animal models, dark oxygen consumption, and photosynthetic efficiency in C. sativus). In C. sativus, only E124 increased ROS and affected dark oxygen consumption and photosynthetic efficiency, while all dyes enhanced the antioxidant defenses. In the A. salina nauplii, all dyes increased ROS, while E120 and E124 reduced the susceptibility to oxidative stress. In D. rerio, treatments did not affect ROS content, and reduced oxidative stress susceptibility. Our data show that red food dyes affect the redox state of the developing organisms, in which ROS plays a significant role. We suggest a potentially toxic role for red food dyes with environmentally relevant consequences