Multiparametric Semi-quantitative Scoring System for the histological evaluation of marine fish larval and juvenile quality

Gilthead seabream (GSB - Sparus aurata) and European seabass (ESB - Dicentrarchus labrax) are two of the most farmed fish species in EU. However, production of sea bream/bass in the EU has remained stagnant for the last decade and the Mediterranean EU aquaculture faces significant sustainability challenges. In consideration of this, and as it is largely recognized that the success of marine aquaculture strictly depends on the production of good quality larvae/juveniles, in this paper the authors put forward an original standardized tool for the histological assessment of GSB and ESB larva/juveniles. This tool promptly allows to highlight problems in marine fish larval batches because of managerial practices, suggesting to fish farmers which direction take to resolve them. A Multiparametric Semi-quantitative Scoring System (scoring range 1–5) has been originally developed for larval/juvenile histological evaluation and it includes 18 descriptors related to 6 organ districts. The values of each descriptor can be summarized in two indexes: the CHI (Cumulative Histological Index), giving general information about the quality of a fish batch in that precise moment and the OCV (Organ condition value) showing the general condition of each organ and by the individual descriptors. The paper purposes are to describe the MSSS, the criteria established for the score attribution and to supply some indications for the use of the tool

Rumen fermentation parameters and papillae development in Simmental growing bulls with divergent residual feed intake

Residual feed intake (RFI), a widespread index used to measure animal feed efficiency, is influenced by various individual biological factors related to inter-animal variation that need to be assessed. Herein, 30 Simmental bulls, raised under the same farm conditions, were divided on the basis of RFI values into a high efficient group (HE, RFI = − 1.18 ± 0.33 kg DM/d, n = 15) and a low efficient group (LE, RFI = 0.92 ± 0.35 kg DM/d, n = 15). Subsequently, bulls were slaughtered at an average BW of 734 ± 39.4 kg. Their ruminal fermentation traits were analysed immediately after slaughtering and after 24 h of in vitro incubation. Furthermore, ruminal micro-biota composition and ruminal papillae morphology were examined. The LE group exhibited a higher propionate concentration as a percentage of total volatile fatty acids (17.3 vs 16.1%, P = 0.04) in the rumen fluid collected during slaughtering, which was also confirmed after in vitro fermentation (16.6 vs 15.4% respectively for LE and HE, P = 0.01). This phenomenon resulted in a significant alteration in the acetate−to−propionate ratio (A:P) with higher values for the HE group, both after slaughter (4.01 vs 3.66, P = 0.02) and after in vitro incubation (3.78 vs 3.66, P = 0.02). Methane production was similar in both groups either as absolute production (227 vs 218 mL for HE and LE, respectively) or expressed as a percentage of total gas (approximately 22%). Even if significant differences (P < 0.20) in the relative abundance of some bacterial genera were observed for the two RFI groups, no significant variations were observed in the alpha (Shannon index) and beta (Bray–Curtis index) diversity. Considering the papillae morphology, the LE subjects have shown higher length values (6.26 vs 4.90 mm, P < 0.01) while HE subjects have demonstrated higher papillae density (46.4 vs 40.5 n/cm2, P = 0.02). Histo-morphometric analysis did not reveal appreciable modifications in the total papilla thickness, boundaries or surface between the experimental groups. In conclusion, our results contribute to efforts to analyse the factors affecting feed efficiency at the ruminal level. Propionate production, papillae morphology and a few bacterial genera certainly play a role in this regard, although not a decisive one

Monogenean Sparicotyle chrysophrii: The major pathogen of the Mediterranean gilthead seabream aquaculture

Following the intensification of the Mediterranean aquaculture over the years, Sparicotyle (syn. Microcotyle) chrysophrii (van Beneden and Hesse, 1863; Microcotylidae, Monogenea) became one of the most pathogenic ectoparasites for the gilthead seabream (Sparus aurata L.) aquaculture. It has demonstrated a remarkable versatility to expand over its known host range, accomplish an efficient transfer between the wild and farmed sparid populations over wide geographic areas, and establish itself as the most detrimental gilthead seabream pathogen. Even though the incidence of S. chrysophrii is closely monitored in marine aquaculture system throughout the Mediterranean, there is a general lack of recent and publicly available data on its epidemiology. Being considered as a parasite whose proliferation is expected to increase under global warming conditions, such lack of data additionally humpers the implementation of integrated pest management strategy at national and Mediterranean level. While EU scientific initiatives greatly contributed to our understanding of S. chrysophrii biology, ecology and sparicotylosis treatment and pathogenesis, there is more ahead to elucidate about the mitigation of the diseases, particularly towards the development of genomic selection breeding programs of parasite-resilient gilthead seabream, omic-based screening of novel drug targets and reversed vaccinology

Intestinal morpho-physiology and innate immune status of European sea bass (Dicentrarchus labrax) in response to diets including a blend of two marine microalgae, Tisochrysis lutea and Tetraselmis suecica

The aim of this study was to investigate the effects of replacing graded levels of dietary fish meal by a blend of two marine microalgae Tisochrysis lutea and Tetraselmis suecica on intestinal morpho-physiology and innate immune response in European sea bass. Two complete diets were formulated to be iso-nitrogenous and isolipidic and prepared by including a blend of the two microalgae, to replace approximately 15 and 45% fish meal protein of the control diet. A fourth diet, where the microalgae mix was substituted by soybean meal, was also prepared. Each diet was offered until visual satiety over 105 days to triplicated groups of European sea bass (204 \ub1 12.7 g), kept in a recirculating marine water system. The humoral and cellular innate immune parameters of E. sea bass were affected by the dietary treatment. Fish fed the microalgae-containing or the soybean rich diets, showed a significantly greater villi height, while the thickness of intestinal epithelium was significantly reduced in fish fed the soybean meal-rich diet. The activity of the brush border membrane enzymes, maltase, sucrase-isomaltase, \u3b3-glutamil transferase and alkaline phosphatase was not affected by dietary treatment but changed in different intestinal tracts. The genes sucrase-isomaltase, peptide transporter 1, sodium/potassium-transporting ATPase and aminopeptidase N were overexpressed in the pyloric and proximal region of the intestine of fish fed the microalgae-including diets. In conclusion, a blend of dried marine microalgae Tisochrysis lutea and Tetraselmis suecica as alternative ingredients to dietary fish meal did not hamper gut digestive-absorptive functions of E. sea bass. Moreover, it resulted in enhanced non-specific immune response, suggesting an effective role as an immunostimulant ingredien

Geometric properties of galactic discs with clumpy episodes

A scenario for the formation of the bi-modality in the chemical space [α/Fe] vs [Fe/H] of the Milky Way was recently proposed in which α-enhanced stars are produced early and quickly in clumps. Besides accelerating the enrichment of the medium with α-elements, these clumps scatter the old stars, converting in-plane to vertical motion, forming a geometric thick disc. In this paper, by means of a detailed analysis of the data from smooth particle hydrodynamical simulations, we investigate the geometric properties (in particular of the chemical thick disc) produced in this scenario. For mono-age populations we show that the surface radial density profiles of high-[α/Fe] stars are well described by single exponentials, while that of low-[α/Fe] stars require broken exponentials. This break is sharp for young populations and broadens for older ones. The position of the break does not depend significantly on age. The vertical density profiles of mono-age populations are characterized by single exponentials, which flare significantly for low-[α/Fe] stars but only weakly (or not at all) for high-[α/Fe] stars. For low-[α/Fe] stars, the flaring level decreases with age, while for high-[α/Fe] stars it weakly increases with age (although with large uncertainties). All these properties are in agreement with observational results recently reported for the Milky Way, making this a plausible scenario for the formation of the Galactic thick disc

Box/peanut-shaped bulges in action space

Abstract We introduce the study of box/peanut (B/P) bulges in the action space of the initial axisymmetric system. We explore where populations with different actions end up once a bar forms and a B/P bulge develops. We find that the density bimodality due to the B/P bulge (the X-shape) is better traced by populations with low radial, $\rm J_{R,0}$, or vertical, $\rm J_{z,0}$, actions, or high azimuthal action, $\rm J_{\phi ,0}$. Generally populations separated by $\rm J_{R,0}$ have a greater variation in bar strength and vertical heating than those separated by $\rm J_{z,0}$. While the bar substantially weakens the initial vertical gradient of $\rm J_{z,0}$, it also drives a strikingly monotonic vertical profile of $\rm J_{R,0}$. We then use these results to guide us in assigning metallicity to star particles in a pure N-body model. Because stellar metallicity in unbarred galaxies depends on age as well as radial and vertical positions, the initial actions are particularly well suited for assigning metallicities. We argue that assigning metallicities based on single actions, or on positions, results in metallicity distributions inconsistent with those observed in real galaxies. We therefore use all three actions to assign metallicity to an N-body model by comparing with the actions of a star-forming, unbarred simulation. The resulting metallicity distribution is pinched on the vertical axis, has a realistic vertical gradient and has a stronger X-shape in metal-rich populations, as found in real galaxies

Bending waves excited by irregular gas inflow along warps

Gaia has revealed clear evidence of bending waves in the vertical kinematics of stars in the solar neighbourhood. We study bending waves in two simulations, one warped, with the warp due to misaligned gas inflow, and the other unwarped. We find slow, retrograde bending waves in both models, with the ones in the warped model having larger amplitudes. We also find fast, prograde bending waves. Prograde bending waves in the unwarped model are very weak, in agreement with the expectation that these waves should decay on short, approximately crossing, time-scales, due to strong winding. However, prograde bending waves are much stronger for the duration of the warped model, pointing to irregular gas inflow along the warp as a continuous source of excitation. We demonstrate that large-amplitude bending waves that propagate through the solar neighbourhood give rise to a correlation between the mean vertical velocity and the angular momentum, with a slope consistent with that found by Gaia. The bending waves affect populations of all ages, but the sharpest features are found in the young populations, hinting that short-wavelength waves are not supported by the older, kinematically hotter, populations. Our results demonstrate the importance of misaligned gas accretion as a recurrent source of vertical perturbations of disc galaxies, including in the Milky Way

Comparative Therapeutic Effects of Natural Compounds Against Saprolegnia spp. (Oomycota) and Amyloodinium ocellatum (Dinophyceae)

The fish parasites Saprolegnia spp. (Oomycota) and Amyloodinium ocellatum (Dinophyceae) cause important losses in freshwater and marine aquaculture industry, respectively. The possible adverse effects of compounds used to control these parasites in aquaculture resulted in increased interest on the search for natural products with antiparasitic activity. In this work, eighteen plant-derived compounds (2′,4′-Dihydroxychalcone; 7-Hydroxyflavone; Artemisinin; Camphor (1R); Diallyl sulfide; Esculetin; Eucalyptol; Garlicin 80%; Harmalol hydrochloride dihydrate; Palmatine chloride; Piperine; Plumbagin; Resveratrol; Rosmarinic acid; Sclareolide; Tomatine, Umbelliferone, and Usnic Acid) have been tested in vitro. Sixteen of these were used to determine their effects on the gill cell line G1B (ATCC®CRL-2536™) and on the motility of viable dinospores of Amyloodinium ocellatum, and thirteen were screened for inhibitory activity against Saprolegnia spp. The cytotoxicity results on G1B cells determined that only two compounds (2′,4′-Dihydroxychalcone and Tomatine) exhibited dose-dependent toxic effects. The highest surveyed concentrations (0.1 and 0.01 mM) reduced cell viability by 80%. Upon lowering the compound concentration the percentage of dead cells was lower than 20%. The same two compounds revealed to be potential antiparasitics by reducing in a dose-dependent manner the motility of A. ocellatum dinospores up to 100%. With respect to Saprolegnia, a Minimum Inhibitory Concentration was found for Tomatine (0.1 mM), Piperine and Plumbagin (0.25 mM), while 2′,4′-Dihydroxychalcone considerably slowed down mycelial growth for 24 h at a concentration of 0.1 mM. Therefore, this research allowed to identify two compounds, Tomatine and 2′,4′-Dihydroxychalcone, effective against both parasites. These compounds could represent promising candidates for the treatment of amyloodiniosis and saprolegniosis in aquaculture. Nevertheless, further in vitro and in vivo tests are required in order to determine concentrations that are effective against the considered pathogens but at the same time safe for hosts, environment and consumers