Artificial Reproduction and Larval Weaning of the Octopus(Octopus vulgaris Cuvier, 1797) in a Controlled Environment

L’interesse commerciale per lo sviluppo dell’allevamento del polpo (Octopus vulgaris Cuvier, 1797), nasce dal fatto che questo mollusco cefalopode ricopre un’importantissima nicchia nell’ambito del mercato ittico Italiano ed Europeo, essendo particolarmente amato dai consumatori in qualsiasi periodo dell’anno. Uno degli aspetti più evidenti e affascinanti dei cefalopodi è la moltitudine di display e colori che vengono prodotti sulla superficie della pelle. Le tonalità di colore che possono essere osservate, sono prodotte da cellule specializzate presenti sotto il derma che combinandosi tra loro non provocano cambiamenti solo a livello cromatico, ma anche tissutale, grazie all’attività della muscolatura del derma. Tutte queste componenti nella loro completezza conferiscono al polpo la capacità di poter spaziare attraverso un elevato numero di profili che prendono il nome di patterns, i quali non sono limitati alla sola colorazione della cute, ma anche a tutte quelle tipologie posturali e locomotorie che essi sono capaci di assumere. Al momento il polpo è considerato una specie innovativa per l’acquacoltura, in quanto presenta alcune caratteristiche biologiche molto interessanti quali: ciclo di vita breve, elevato tasso di accrescimento, elevato indice di conversione alimentare ed elevato tasso di fecondità. I risultati fino ad ora ottenuti in termini di svezzamento e sopravvivenza delle paralarve risultano tuttavia ancora insoddisfacenti per considerare il polpo come una vera nuova specie da allevare. L’obiettivo del presente studio è stato quello di mettere a punto un nuovo impianto per il mantenimento in ambiente controllato di adulti di Octopus vulgaris. Scegliendo il comportamento come indicatore dello stato di salute degli animali, sono state create le condizioni ambientali ottimali per favorirne la riproduzione spontanea ed ottenere paralarve vitali, con le quali eseguire prove di alimentazione in grado di garantirne la sopravvivenza.The interest in the development of the octopus breeding (Octopus vulgaris Cuvier, 1797), stems from the fact that this mollusk cephalopod covers a very important niche of the Italian and European market, being particularly appreciated by consumers in any period of the year. One of the most obvious and fascinating aspects of cephalopods is the multitude of displays and colors that are produced on the surface of the skin. The shades of color that can be observed, are produced by specialized cells present under the dermis that, when combined, do not cause changes only on the chromatic level, but also tissue, thanks to the activity of the musculature of the dermis. All these components in their entirety give the octopus the ability to be able to wander through a large number of profiles that take the name of patterns, which are not limited to the skin color only, but also to all those postural and locomotor types that they are able to hire. At the moment the octopus is considered an innovative species for aquaculture, as it has some very interesting biological characteristics such as: short life cycle, high growth rate, high food conversion index and high fertility rate. The results so far obtained in terms of weaning and survival of the paralarvae, however, are still unsatisfactory to consider the octopus as a real new species to breed. The objective of the present study was to develop a new plant for the maintenance in a controlled environment of adults of Octopus vulgaris. By choosing the behavior as an indicator of the state of health of the animals, optimal environmental conditions have been created to favor spontaneous reproduction and to obtain vital paralarvae, with which to perform feeding tests able to guarantee their survival

Gonadal Development in European Eel Populations of North Adriatic Lagoons at Different Silvering Stages

The European eel (Anguilla anguilla, Linnaeus 1758) is a catadromous fish with significant cultural, scientific, and commercial value. The protection of this species is particularly difficult because the biology of the eel life cycle remains unknown in many aspects. The European eel (A. anguilla) population has declined alarmingly over the past 30 years; this condition has led to questions about the long-term welfare of this species. This work aims to perform a histological analysis on gonad samples from European eels coming from four different lagoons of the North Adriatic at different stages of silvering, and to evaluate the maturation of the gonads. For this study, a total of 859 wild eels were captured from four different lagoons using the “lavoriero”. Subsequently, the biometric parameters were collected. Seventy-nine female eels were randomly selected, dissected, and the gonads were removed for histological analysis. Sections of 4 m were cut and stained with hematoxylin and eosin (H&E). Histological observations of germ cells at the light microscopy level allowed for the characterization of six steps of oocyte maturation. Valle di Comacchio had the highest levels of oocyte maturation, while Valle Ca’ Pasta had the lowest. Eels with silver index III had an oocyte maturation nearly equal to that of eels at stages IV and V of silvering. Considering the results, we can affirm that eels from North Adriatic lagoons have high oocyte maturation levels and high GSI value indices at silvering stage III. The following experimental work shows that the levels of oocyte maturation are higher even at lower silver index levels. It can be hypothesized that in these eels, the transition from yellow to silver eel occurs faster in relation to the high trophic availability in North Adriatic lagoons

FBR for Polyolefin Production in Gas Phase: Validation of a Two-phase Compartmentalized Model by Comparison with CFD

Two different modeling approaches are applied in this work to the simulation of fluidized bed reactors containing solid particles of Geldart A-B type and operated at conditions typically used for polyolefins production. On one side, a fully detailed computational fluid dynamics (CFD) model is developed, considering a 2D planar geometry and a multi-fluid description with kinetic theory of granular flows. On the other, a conventional three-phase, 1D compartmentalized model (SCM) is also developed, implementing the fluid dynamic description based on popular, semi-empirical relationships available in the literature. Given the huge difference of computational effort associated with the corresponding numerical solutions, our aim is to confirm the reliability of the simplified model by comparison with the results of the detailed CFD model. The comparison is carried out considering the fluidization of a bed of solid particles without reaction and solid injection or withdrawal, thus focusing on the steady-state fluid dynamic behavior of the expanded bed. Three different gas velocities and different monodisperse and polydisperse particle populations are analyzed. The results show that the oversimplified compartmentalized approach is capable to predict the solid mixing features established inside the reactor operated in bubbling fluidization regime with good reliability for non-reactive polyethylene particles. Average solid volume fractions are particularly close to the values predicted by the CFD model when monodisperse particles are considered inside the examined range of gas velocity values. A generally good agreement is also found when solids with broad size distribution are analyzed. Overall, these comparisons provide a meaningful validation of the simplified compartmentalized models: given their negligible computational demand and general versatility (complex kinetic schemes and single particle models are easily accounted for), they still represent an effective tool of industrial process design

Sexual behaviour and reproductive performance of the endangered European eel Anguilla anguilla (Linnaeus, 1758) based on direct observationsand paternity assignment in semi-natural conditions

European eel Anguilla anguilla is among the highly valued species for aquaculture. Since its peculiar biology, it is not yet possible to complete the whole life cycle in artificial conditions and its supply depends entirely on wild catches. In the last 50 years this species has suffered a population reduction of 99 % mainly due to overfishing. In a conservation perspective, it is of fundamental importance to improve the aquaculture production of European eel, to avoid the extinction of this species and preserve its residual genetic variability, allowing at the same time the fulfilling of costumers request without increasing its harvesting pressure. In this study we aimed to deepen the knowledge about the mechanisms at the basis of reproduction of the European eel in semi-natural conditions, through direct observation of spawning behaviour and through the paternity assignment using microsatellite markers. The systematic and prolonged observation of the reproductive behaviour of European eel and the contextual parentage analyses we carried out for the very first time in this species on 39 adults and 432 F1 randomly collected. We contributed to unravel the sexual behaviour of this species in the most common artificial reproduction conditions (polyandry), and define the precise courtship sequence until the release of gametes, and the male-male hierarchy in courtship. We characterized for the first time three main types of male: dominant (the first who starts the courtship, and the one with the majority of F1 assigned), subordinate (which starts the courtship only in a second time and with a minor percentage of F1 ascribed) and ineffective (which sometime appears totally disinterested to courtship and has few F1 or none). The evidences here produced represent an important attempt for developing good reproduction practices of the critically endangered European eel, providing a good starting point for its future aquaculture production

Comparison between detailed (CFD) and simplified models for the prediction of solid particle size distribution in fluidized bed reactors

This work is aimed at developing a simplified model suitable to effectively describe the fluidization behavior within fluidized beds with minimal computational efforts. The simplified model was validated through detailed CFD Euler-Euler simulations showing a good agreement in the case of large particles (about 450 micron) at all the gas velocities considered (20, 40, 61 cm/s). Slightly less accurate outcomes were observed for smaller particles (about 220 micron). This was due to the underestimation of the particle size effect on the fluidization behavior by the simplified approach

How to Turn an Electron Transfer Protein into a Redox Enzyme for Biosensing

Cytochrome c is a small globular protein whose main physiological role is to shuttle electrons within the mitochondrial electron transport chain. This protein has been widely investigated, especially as a paradigmatic system for understanding the fundamental aspects of biological electron transfer and protein folding. Nevertheless, cytochrome c can also be endowed with a non-native catalytic activity and be immobilized on an electrode surface for the development of third generation biosensors. Here, an overview is offered of the most significant examples of such a functional transformation, carried out by either point mutation(s) or controlled unfolding. The latter can be induced chemically or upon protein immobilization on hydrophobic self-assembled monolayers. We critically discuss the potential held by these systems as core constituents of amperometric biosensors, along with the issues that need to be addressed to optimize their applicability and response

Effects of environmental enrichment on the behavior of Octopus vulgaris in a recirculating aquaculture system

Octopus vulgaris is a commercially valuable species. It is overexploited in the natural envi-24 ronment and is considered to be an innovative species for aquaculture. However, large-scale farm-25 ing is generally designed only based on economic requirements, disregarding any form of enrich-26 ment that to induce the natural behavior of aquatic species. Although many studies have shown the 27 influence of environmental enrichment on terrestrial vertebrates, fish, and cephalopod mollusks, 28 information on the effect of environmental enrichment on the body patterns of O. vulgaris is limited. 29 Therefore, in this study, we assessed how different environmental conditions (Basic vs. Enriched) 30 affect sub-adults of O. vulgaris kept in recirculation systems, through qualitative–quantitative stud-31 ies of the main body patterns and their potential application in the commercial production of this 32 species. The results indicated that octopuses kept in the enriched environment showed several body 33 patterns and gained a significantly higher weight than those kept in the basic environment. The 34 body patterns displayed by the individuals kept in the basic environment were similar to those 35 exhibited under situations of hostility and inter/intra-specific conflict. Hence, the environment of 36 octopuses needs to be enriched, especially for the large-scale production of this species

Effects of Environmental Enrichment on the Behavior of Octopus vulgaris in a Recirculating Aquaculture System

Octopus vulgaris is a commercially valuable species. It is overexploited in the natural environment and is considered to be an innovative species for aquaculture. However, large-scale farming is generally designed only based on economic requirements, disregarding any form of enrichment that induces the natural behavior of aquatic species. Although many studies have shown the influence of environmental enrichment on terrestrial vertebrates, fish, and cephalopod mollusks, information on the effect of environmental enrichment on the body patterns of O. vulgaris is limited. Therefore, in this study, we assessed how different environmental conditions (Basic vs. Enriched) affect sub-adults of O. vulgaris kept in recirculation systems, through qualitative–quantitative studies of the main body patterns and their potential application in the commercial production of this species. The results indicated that octopuses kept in the enriched environment showed several body patterns and gained a significantly higher weight than those kept in the basic environment. The body patterns displayed by the individuals kept in the basic environment were similar to those exhibited under situations of hostility and inter/intra-specific conflict. Hence, the environment of octopuses needs to be enriched, especially for the large-scale production of this species

A detailed CFD analysis of flow patterns and single-phase velocity variations in spiral jet mills affected by caking phenomena

8siIn this work we present a method to investigate the fluid-dynamics of a 3D, real-scale spiral jet mill when caking is occurring. CFD simulations are employed to deeply study the pressure and the velocity fields of the gas phase when the nozzles inlet pressure and the chamber diameter are varied to mimic the condition generated by the aggregates formation during the micronizaton process. The computational model is built replicating the experimental observation consisting in the fact that most of the crusts form on the outer wall of the chamber. Simulations underline that caking causes the deterioration of the classification capabilities of the system if the gas mass flow rate is kept constant at nozzles, allowing larger particles for escaping the system. It is shown that it is possible to mitigate this phenomenon by gradually reducing the gas mass-flow rate to keep constant the nozzles absolute pressure. This keeps unchanged the fluid spin ratio and the classification characteristics when caking is advancing.openopenSabia, Carmine; Frigerio, Giovanni; Casalini, Tommaso; Cornolti, Luca; Martinoli, Luca; Buffo, Antonio; Marchisio, Daniele L.; Barbato, Maurizio C.Sabia, Carmine; Frigerio, Giovanni; Casalini, Tommaso; Cornolti, Luca; Martinoli, Luca; Buffo, Antonio; Marchisio, Daniele L.; Barbato, Maurizio C

Adsorbing surface strongly influences the pseudoperoxidase and nitrite reductase activity of electrode-bound yeast cytochrome c. The effect of hydrophobic immobilization

The Met80Ala and Met80Ala/Tyr67Ala variants of S. cerevisiae iso-1 cytochrome c (ycc) and their adducts with cardiolipin immobilized onto a gold electrode coated with a hydrophobic self-assembled monolayer (SAM) of decane-1-thiol were studied through cyclic voltammetry and surface-enhanced resonance Raman spectroscopy (SERRS). The electroactive species - containing a six-coordinate His/His axially ligated heme and a five-coordinate His/- heme stable in the oxidized and reduced state, respectively - and the pseudoperoxidase activity match those found previously for the wt species and are only slightly affected by CL binding. Most importantly, the reduced His/- ligated form of these variants is able to catalytically reduce the nitrite ion, while electrode-immobilized wt ycc and other His/Met heme ligated variants under a variety of conditions are not. Besides the pseudoperoxidase and nitrite reductase functions, which are the most physiologically relevant abilities of these constructs, also axial heme ligation and the equilibria between conformers are strongly affected by the nature - hydrophobic vs. electrostatic - of the non-covalent interactions determining protein immobilization. Also affected are the catalytic activity changes induced by a given mutation as well as those due to partial unfolding due to CL binding. It follows that under the same solution conditions the structural and functional properties of immobilized ycc are surface-specific and therefore cannot be transferred from an immobilized system to another involving different interfacial protein-SAM interactions