Long-term Effects of the Larval Photoperiod on the Subsequent Growth of Shi Drum Umbrina cirrosa L. Specimens and the Fillet Texture at Commercial Size

Three groups of shi drum Umbrina cirrosa L. were reared with different photoperiod regimes: 24L, 12L:12D and 16L:8D (natural photoperiod) during the larval period and then all of them were transferred to a natural photoperiod. At 11.8 and 20 months of age, the body growth and the muscle parameters reached the highest values in the 24L and 12L:12D groups. The 16L:8D group showed the lowest growth. When comparing 24L with 12L:12D, the highest number of white fibres was found in the 24L group, whereas the greatest fibres size was reached in the 12L:12D group. Commercial size (28-30 cm; 290-340 g) was reached at 20 months of age in the 24L and 12L:12D groups, but at 23 months in the 16L:8D group. When comparing the three groups at the commercial stage, the larval photoperiod effect was still observed, such that the highest fibres number was again found in the 24L group, whereas the greatest fibres size was reached in the 12L:12D group. The highest values of textural hardness were observed in the 16L:8D and 24L groups. A nutritional analysis was carried out in the 16L:8D group, which showed the following percentage values: 2.66, 21.2, 74.4, and 1.46 of fat, protein, moisture and ash, respectively.0,591

Profile of Innate Immunity in Gilthead Seabream Larvae Reflects Mortality upon Betanodavirus Reassortant Infection and Replication

Historically, gilthead seabream (Sparus aurata) has been considered a fish species resistant to nervous necrosis virus (NNV) disease. Nevertheless, mortality in seabream hatcheries, associated with typical clinical signs of the viral encephalopathy and retinopathy (VER) disease has been confirmed to be caused by RGNNV/SJNNV reassortants. Because of this, seabream larvae at 37 and 86 days post-hatching (dph) were infected by immersion with RGNNV/SJNNV and SJNNV/RGNNV reassortants under laboratory conditions, and mortality, viral replication and immunity were evaluated. Our results show that gilthead seabream larvae, mainly those at 37 dph, are susceptible to infection with both NNV reassortant genotypes, with the highest impact from the RGNNV/SJNNV reassortant. In addition, viral replication occurs at both ages (37 and 86 dph) but the recovery of infective particles was only confirmed in 37 dph larvae,; this value was also highest with the RGNNV/SJNNV reassortant. Larvae immunity, including the expression of antiviral, inflammatory and cell-mediated cytotoxicity genes, was affected by NNV infection. Levels of the natural killer lysin (Nkl) peptide were increased in SJNNV/RGNNV-infected larvae of 37 dph, though hepcidin was not. Our results demonstrate that the seabream larvae are susceptible to both NNV reassortants, though mainly to RGNNV/SJNNV, in an age-dependent manner.Versión del editor2,46

Effects of oral administration of 17α-ethynylestradiol on male seabream Sparus aurata L.

The effects of 17α-ethynylestradiol (EE2) on immature and mature males of the gilthead seabream (Sparus aurata L.) were studied. Gilthead seabream specimens were fed for 1 month with diets containing EE2 (5, 50, 125, 200 μg/g food). EE2 exposure altered the appetite, survival and digestive system in immature fish, and caused changes in the gonadal development, growth, survival, and some somatic indexes in mature males. The highest EE2 doses showed acute toxic effects (50% mortality) and liver injury. Gonad size was also drastically reduced

Reservoirs of Red-Spotted Grouper Nervous Necrosis Virus (RGNNV) in Squid and Shrimp Species of Northern Alboran Sea

The production of the aquaculture industry has increased to be equal to that of the world fisheries in recent years. However, aquaculture production faces threats such as infectious diseases. Betanodaviruses induce a neurological disease that affects fish species worldwide and is caused by nervous necrosis virus (NNV). NNV has a nude capsid protecting a bipartite RNA genome that consists of molecules RNA1 and RNA2. Four NNV strains distributed worldwide are discriminated according to sequence homology of the capsid protein encoded by RNA2. Since its first description over 30 years ago, the virus has expanded and reassortant strains have appeared. Preventive treatments prioritize the RGNNV (red-spotted grouper nervous necrosis virus) strain that has the highest optimum temperature for replication and the broadest range of susceptible species. There is strong concern about the spreading of NNV in the mariculture industry through contaminated diet. To surveil natural reservoirs of NNV in the western Mediterranean Sea, we collected invertebrate species in 2015 in the Alboran Sea. We report the detection of the RGNNV strain in two species of cephalopod mollusks (Alloteuthis media and Abralia veranyi), and in one decapod crustacean (Plesionika heterocarpus). According to RNA2 sequences obtained from invertebrate species and reported to date in the Mediterranean Sea, the strain RGNNV is predominant in this semienclosed sea. Neither an ecosystem- nor host-driven distribution of RGNNV were observed in the Mediterranean basin.Versión del edito

Transcription of histones H1 and H2B is regulated by several immune stimuli in gilthead seabream and European sea bass

Histones (H1 to H4) are the primary proteins which mediate the folding of DNA into chromatin; however, and in addition to this function, histones have been also related to antimicrobial peptides (AMPs) activity in vertebrates, in fact, mammalian H1 is mobilized as part as the anti-viral immune response. In fish, histones with AMP activity have been isolated and characterized mainly from skin and gonads. One of most threatening pathogens for wild and cultured fish species nowadays is nodavirus (NNV), which target tissues are the brain and retina, but it is also able to colonize the gonad and display vertical transmission. Taking all this into account we have identified the h1 and h2b coding sequences in Eu- ropean sea bass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata) fish species and studied their pattern of expression under naïve conditions and NNV in vivo infection. The data obtained prompted us to study their role on the immune response of gonad and head-kidney leucocytes upon viral (NNV), bacteria (Vibrio anguillarumor Photobacteriumdamselae), pathogen-associated molecular patterns (PAMPs) or mitogens stimulation. The h1 and h2b genes are expressed in a wide range of tissues and their expression is modify by infection or other immune stimuli, but further studies will be needed to determine the significance of these changes. These results suggest that h1 expression is related to the immune response against NNV in the brain, while h2b transcription seems to be more important in the head-kidney. Moreover, the potential role of histones as anti-viral agents is suggested and further characterization is in progress

Detection of Red-spotted grouper nervous necrosis virus (RGNNV) in shrimp and squid of the Mediterranean Sea

The quest for sustainable fisheries and procurement of food supply has increased aquaculture production up to the world fisheries capture. Viral encephalopathy and retinopathy (VER), also known as viral nervous necrosis (VNN), is caused by nervous necrosis virus (NNV) and results in high mortality of larvae and juveniles of continuous increasing amount of fish species. The disease causes vacuolation and necrosis of the central nervous system. The virus has a nude capsid protecting a bipartite RNA genome that consists of positive stranded molecules RNA1 and RNA2. Four NNV genotype strains distributed worldwide are discriminated according to sequence homology of the capsid protein encoded by RNA2. Preventive treatments prioritize the RGNNV (Redspotted grouper nervous necrosis virus) genotype that has the highest optimum temperature for replication and the broadest range of susceptible species. A flow of NNV between wild and cultured fish had been demonstrated, and reservoirs of NNV have been reported in invertebrates, raising concern on the spreading of NNV in the mariculture industry through contaminated food. The present study aimed to contribute in the surveillance of reservoirs of NNV in invertebrates of the unexplored western Mediterranean Sea. We report the detection of the RGNNV strain in two species of squid (Alloteuthis media and Abralia veranyi), and in one shrimp (Plesionika heterocarpus) collected in 2015 in the Alboran Sea. According to RNA2 sequences obtained from invertebrates and reported to date in the Mediterranean Sea, the strain RGNNV is predominant in this semi-enclosed sea. Our results suggest that RGNNV distribution is apparently independent of host species and ecosystem, and similar between invertebrates and fish species that feed on invertebrates, calling for an increase in surveillance of NNV reservoirs in the wild.European Association of Fish Pathologists. PathoVe

Severe Natural Outbreak of Cryptocaryon irritans in Gilthead Seabream Produces Leukocyte Mobilization and Innate Immunity at the Gill Tissue

The protozoan parasite Cryptocaryon irritans causes marine white spot disease in a wide range of fish hosts, including gilthead seabream, a very sensitive species with great economic importance in the Mediterranean area. Thus, we aimed to evaluate the immunity of gilthead seabream after a severe natural outbreak of C. irritans. Morphological alterations and immune cell appearance in the gills were studied by light microscopy and immunohistochemical staining. The expression of several immune-related genes in the gills and head kidney were studied by qPCR, including inflammatory and immune cell markers, antimicrobial peptides (AMP), and cell-mediated cytotoxicity (CMC) molecules. Serum humoral innate immune activities were also assayed. Fish mortality reached 100% 8 days after the appearance of the C. irritans episode. Gill filaments were engrossed and packed without any space between filaments and included parasites and large numbers of undifferentiated and immune cells, namely acidophilic granulocytes. Our data suggest leukocyte mobilization from the head kidney, while the gills show the up-regulated transcription of inflammatory, AMPs, and CMC-related molecules. Meanwhile, only serum bactericidal activity was increased upon infection. A potent local innate immune response in the gills, probably orchestrated by AMPs and CMC, is triggered by a severe natural outbreak of C. irritans.Versión del editor2,46

Regional asymmetry of metabolic and antioxidant profile in the sciaenid fish shi drum (Umbrina cirrosa) white muscle. Response to starvation and refeeding.

The objective of the present study is to characterize the metabolic and antioxidant profile of white muscle of shi drum in two sites of the body, anterior dorsal (AM) and posterior dorsal (PM) portions. In addition, it will be analyzed the possible effect of starvation and a subsequent refeeding, with two different protocols, pair feeding and ad libitum. Activities of key enzymes of intermediary metabolism and of antioxidant enzymes, as well as lipid peroxidation, as an index of oxidative stress, were evaluated. The results indicate the existence of a regional asymmetry of the metabolic capacities of the white muscle of shi drum, which is likely related to the different contribution to swimming of the body regions examined. Starvation induces a metabolic depression that is more marked in those activities that support burst swimming in PM, while those activities supporting maintenance requirements are conserved. The greatest energy demands during starvation appear to lie in AM, which showed the highest oxidative metabolism rate. The increased use of fatty acids as energy source for AM leads to oxidative stress. A period of more than four weeks of refeeding for full restoration of metabolic capacities in AM is needed, probably related to the higher muscle mass located in this region. On the contrary, all enzyme activities in PM returned to control levels in both refeeding protocols, but pair feeding seems to be advantageous since compensatory growth has been taking place without signs of oxidative stress. This work was addressed to gain knowledge on the physiology of a promising fish species in aquaculture like shi drum. The results displayed here show how the starving and further re-feeding events could generate oxidative stress situations characterized by high lipid peroxidation levels which may influence negatively on the quality of the edible part of the fish. This study opens an interesting field on this fish species which deserves being investigated in the future.Versión del edito