Academic literature on the topic 'Scophthalmus'

Blood transcriptomics is emerging as a relevant tool to monitor the status of the immune system and assist in diagnosis, prognosis, treatment and pathogenesis studies of diseases. In fish pathology, the potential of transcriptome profiling of blood is still poorly explored. Here, RNA sequencing was applied to analyze the blood transcriptional profile of turbot (Scophthalmus maximus), the most important farmed flatfish. The study was conducted in healthy specimens and specimens parasitized by the myxozoan Enteromyxum scophthalmi, which causes one of the most devastating diseases in turbot aquaculture. The blood of healthy turbot showed a transcriptomic profile mainly related to erythrocyte gas transportation function, but also to antigen processing and presentation. In moderately infected turbot, the blood reflected a broad inhibition of the immune response. Particularly, down-regulation of the B cell receptor signaling pathway was shared with heavily parasitized fish, which showed larger transcriptomic changes, including the activation of the inflammatory response. Turbot response to enteromyxosis proved to be delayed, dysregulated and ineffective in stopping the infection. The study evinces that blood transcriptomics can contribute to a better understanding of the teleost immune system and serve as a reliable tool to investigate the physiopathological status of fish.

Four species of marine fishes, turbot Scophthalmus maeoticus, common sole Solea solea, shore rockling Gaidropsarus mediterraneus, and rusty blenny Parablennius sanguinolentus from Sinop coasts of the Black Sea were examined for ectoparasitic trichodinids. A total of four trichodinid species, Trichodina rectuncinata, T. ovonucleata, T. jadranica, and T. domerguei were described using the silver nitrate impregnation technique and morphologically studied. All morphometric data and photomicrographs of these trichodinids were presented along with details of their host preferences, prevalence and intensity of infestation. This study is the first report on the trichodinid ectoparasites on Scophthalmus maeoticus, Solea solea, Gaidropsarus mediterraneus, and Parablennius sanguinolentus in Türkiye. Moreover Trichodina rectuncinata is as a new record for Turkish fish parasite fauna.

An epidemiological cohort study of Enteromyxum scophthalmi in cultured turbot was performed on a farm in North Western Spain. Four different ongrowing stocks (A, B, C, D) were monitored monthly until market size. Fish from stocks C and D were divided into 2 subgroups, receiving filtered (CF and DF) or unfiltered (CUF and DUF) water. The lack of water filtration was positively associated with infection prevalence, as all fish kept in filtered water remained uninfected. Parasite abundance varied seasonally (P<0·05) in stock B and subgroup CUF. Infection was also associated (P<0·05) with host weight, and the highest prevalences and intensities were detected in 101–200 g and 201–300 g fish. Distribution pattern of E. scophthalmi in subgroups CUF and DUF had a variance higher than the mean, indicating overdispersion. The minimum period necessary for the first detection of the parasite and for the appearance of disease symptoms and mortality, varied depending on the stock and introduction date, although a long pre-patent period was always observed. Several factors, such as host density, parasite recruitment and parasite-induced fish mortality can contribute to the observed distribution pattern. Risk factors found to be associated with E. scophthalmi infection, including water quality and accumulation of infective stages in the culture tanks, should be considered when designing control strategies to prevent the introduction and spread of infective stages in the facilities.

A new Myxozoa species causing enteritis and death in cultured turbot, Scophthalmus maximus, is described at light and electron microscope levels. In addition, small subunit ribosomal RNA gene sequences (SSU rDNA) from the new species and from similar myxozoans were obtained and used for phylogenetic inference, as complementary criteria to resolve its taxonomic classification. The new parasite is closely related to Myxidium leei, another enteric histozoic species from marine fish. However, the ascription of M. leei to the genus Myxidium was based on weak morphological evidence and is not supported by our rDNA data analysis. A close relationship with Zschokkella, the other morphologically related myxozoan genus is also not supported. The combined morphological and molecular study results in the establishment of the new genus Enteromyxum to accommodate the new species E. scophthalmi, and the former M. leei, which is transferred to the new genus as Enteromyxum leei (Diamant, Lom & Dyková 1994) n. comb. This genus of marine, histozoic and enteric myxozoans includes significant parasite species for marine finfish culture.

Mestrado em Biologia Marinha<br>Foi efectuado um estudo em condições de produção intensiva para avaliar o efeito do fotoperíodo e da densidade no crescimento (peso fresco, ganho de peso, taxa de crescimento relativo, taxa de crescimento específico, factor de condição de Fulton e coeficiente de variação), utilização do alimento (taxa da eficiência alimentar, taxa da eficiência proteica, retenção proteica e retenção proteica liquida aparente), composição corporal (matéria seca, cinzas, proteína, lípidos e energia), produtividade e sobrevivência de pregados juvenis. Grupos de pregados foram mantidos em cinco fotoperíodos diferentes (LE0:24, LE3:21; LE6:18, LE9:15 e LE12:12) e duas densidades (densidades iniciais: 8 e 15 kg m-2) durante 45 dias. A sobrevivência dos pregados foi de 100% para todos os grupos experimentais. O crescimento, a utilização do alimento e a produtividade foram influenciados apenas pela densidade (este factor tem um efeito mais forte nos peixes). Os peixes criados na densidade mais baixa (8 kg m-2) apresentaram taxas de crescimento e ganhos de peso mais elevados e uma melhor utilização do alimento quando comparados com os peixes criados na densidade mais elevada (15 kg m-2). No entanto, a densidade mais elevada teve uma produtividade maior que a densidade mais baixa. Assim, os resultados sugerem que, das densidades estudadas, a densidade mais baixa (8 kg m-2) é a mais adequada para um bom crescimento e uma melhor utilização do alimento, no entanto em termos de produtividade a densidade mais elevada mostrou ser a mais favorável. Não foram observadas diferenças significativas na resposta do crescimento, da utilização do alimento e da produtividade ao fotoperíodo mas existe uma tendência para melhores resultados no fotoperíodo LE6:18. Os pregados criados no fotoperíodo LE6:18 e densidade 8 kg m-2 apresentaram bons valores de crescimento, sobrevivência, utilização do alimento e produtividade. Os resultados deste trabalho vão contribuir no futuro próximo para avaliar a possibilidade de usar esta espécie de uma maneira mais eficaz e rentável e também vão contribuir para um melhor conhecimento da biologia da espécie.<br>A study was carried out in conditions of intensive production to evaluate the effect of photoperiod and stocking density on growth (wet weight, weight gain, relative growth rate, specific growth rate, Fulton’s condition factor and coefficient of variation), feed utilization (feed efficiency ratio, protein efficiency ratio, protein retention and apparent net protein retention), body composition (dry matter, ash, protein, lipid and energy) productivity and survival of juvenile turbot. Groups of fish were reared at five different photoperiod regimes (LD0:24, LD3:21, LD6:18, LD9:15 and LD12:12) and two different stocking densities (initial densities: 8 and 15 kg m-2) for 45 days. Survival was 100% for all the experimental groups. Growth, feed utilization and productivity were only influenced by stocking density (this factor has a stronger effect on the fish). Fish held at the lowest density (8 kg m-2) showed higher growth rates, weight gains and better feed utilization than fish held at the highest density (15 kg m-2). Nonetheless, the highest density had higher productivity than the lowest density. Therefore, the results suggest that, from the densities tested, the lowest density (8 kg m-2) is the most adequate for a good growth, feed utilization, although in terms of productivity the highest density (15 kg m-2) is the most favourable. No significant differences in growth, feed utilization and productivity response to photoperiod were observed though there is a tendency for better results in the photoperiod LD6:18. Juvenile turbot reared at LD6:18 and 8 kg m-2 presented very good results in growth, survival, feed utilization and productivity. This work will contribute in the near future to evaluate the possibility of using this species in a way that can be more effective and more profitable and will also contribute to a better understanding of the species biology.

Mestrado em Biologia Marinha<br>O tratamento de água por ozonização tem demonstrado ser uma ferramenta útil na remoção de resíduos sólidos e estabilização da qualidade da água em sistemas de recirculação, assim como no controle de doenças, pelo que a sua relevância no contexto da piscicultura intensiva é consensualmente assumida. Contudo, as suas consequências a nível bioquímico, fisiológico e citogenético em peixes são ainda pouco conhecidas. Assim, o presente trabalho teve como objectivo investigar os efeitos da exposição a ozono em pregado (Scophthalmus maximus) através da avaliação do seu potencial genotóxico (teste de anomalias nucleares eritrociticas - ANE), de indicadores de stress (níveis plasmáticos de cortisol, glucose e lactato), de alterações nos parâmetros hematológicos (concentração de hemoglobina - Hb, contagem de eritrócitos e hemoglobina corpuscular média - HCM) e índices de condição fisiológica (factor de condição de Fulton – K, índice hepatossomático – IHS). Indivíduos com um peso médio de aproximadamente 75.0±1.41g foram submetidos a 6 horas diárias de exposição a água tratada com ozono (0.15 mg L-1) durante 3 dias consecutivos. Os peixes foram amostrados nos dias 1, 2 e 3, assim como 1 (R1) e 7 (R7) dias após o tratamento, de modo a avaliar a eventual de recuperação. Um grupo controlo foi mantido nas mesmas condições experimentais, mas sem exposição ao ozono. O teste t foi utilizado para avaliar a significância estatística das diferenças entre os grupos tratado e controlo a cada momento de amostragem. Foi detectada uma indução de ANE ao longo da exposição, indicando dano genético. Adicionalmente, este efeito clastogénico prolongou-se para além do período de exposição até ao dia R7. A concentração de glucose plasmática aumentou significativamente apenas no período pós-exposição (R1 e R7). Relativamente ao lactato plasmático, foram registados recorrentemente níveis mais baixos nos animais expostos, apesar dessa descida ter sido estatisticamente significativa apenas no primeiro dia de exposição e no dia R1. O cortisol plasmático aumentou significativamente apenas no primeiro dia de exposição, após o que se manteve inalterado até ao final da experiência. A concentração de Hb aumentou significativamente nos dias 1 e 3, assim como em R1, onde atingiu o nível máximo. Do modo semelhante, o nº de eritrócitos aumentou significativamente nos dias 2 e 3, mostrando um efeito prolongado até ao dia R1. Não se registaram alterações ao longo da experiência na HCM, assim como no factor K e IHS. Os resultados apontam claramente para uma condição de stress induzida pelo ozono, expressa num aumento inicial de cortisol plasmático e um aumento tardio da glicemia (período pós-exposição). A redução de lactato plasmático observada pode constituir um aumento compensatório do metabolismo aeróbico dos peixes expostos, o que está de acordo com o aparente aumento do transporte de oxigénio, expresso nos aumentos de Hb e nº de eritrócitos. Os custos metabólicos associados aos processos de reparação do ADN e desintoxicação do ozono e/ou seus subprodutos, assim como o desvio de energia para manutenção do metabolismo, podem ter repercussões negativas na taxa de crescimento do pregado. Globalmente, ficou demonstrado que os pregados juvenis não foram capazes de se adaptar completamente à exposição a água tratada com ozono em condições realistas, pelo que se sugere a interferência com a saúde dos peixes. Os presentes resultados contribuem para um conhecimento biológico da toxicidade do ozono e para o estabelecimento de margens de segurança na aquicultura em sistemas de recirculação. Apesar de o presente estudo ter sido desenhado para avaliar o impacto do ozono no contexto dos sistemas de recirculação em aquicultura, o risco para as populações aquáticas selvagens associado a descargas de efluentes (municipais e industriais) tratados com ozono não pode ser subestimado. Nesse sentido, assume particular importância o potencial genotóxico demonstrado, dada a relação causal já demonstrada em relação a malformações e lesões neoplásicas.<br>Ozonation is proven useful in recirculating systems promoting the removal of solid matter, the stabilization of water quality and disease control, being thus consensually assumed that it could find a relevant place in the intensive fish culture. Nevertheless, its biochemical, physiological and cytogenetic effects on fish are still largely unknown. Hence, this research investigated the effects of ozone exposure in turbot (Scophthalmus maximus) by assessing its genotoxic potential (erythrocytic nuclear abnormalities assay - ENA), general stress indicators (plasma cortisol, glucose and lactate), alterations on hematological parameters (hemoglobin concentration - Hb, red blood cell count - RBC, and mean cell hemoglobin - MCH) and physiological state indices (Fulton’s condition factor – K, hepatossomatic index - HSI). Turbot specimens with an average weight of approximately 75.0±1.41g were subjected to a daily 6-hr ozone (0.15 mg L-1) exposure, repeated for 3 consecutive days. In order to assess the potential recovery after ozone treatment, fish were also analyzed on 1- (R1) and 7-day (R7) post-treatment. A control group was kept under the same experimental conditions but without ozone exposure. The t-test was used to assess the statistical significance of differences between ozone-treated and control groups in each sampling moment. A significant induction on ENA frequency was recurrently detected along the exposure period, signalling genetic damage. Moreover, this clastogenic effect was prolonged beyond the exposure period up to day R7. Plasmatic concentrations of glucose increased significantly only on the post-treatment period (R1 and R7) and no statistically significance were observed during the ozone exposure. Concerning plasma lactate concentration, lower levels were regularly found in ozone treated fish in relation to the control, even though statistically significant differences were recorded only on the first day of treatment and on R1. Plasmatic levels of cortisol revealed a significant elevation on ozone group following 1 day exposure and afterwards no significant alterations were recorded up to the end of the experiment. The Hb concentration was significantly increased on days 1 and 3, as well as on day R1 where it reached the maximum level. Similarly, RBC were significantly increased on days 2 and 3, showing a prolonged effect on day R1. No significant alterations were observed along the experiment on MCH levels, as well as on K factor and HSI. The results clearly pointed out an ozone-induced stressful condition, expressed by an early plasma cortisol increase and a late hyperglycemia (posttreatment period). The lactate-lowering effect observed may constitute a compensatory increase of the aerobic capacity of fish, which is in line with the apparent improvement in oxygen transport expressed by increased Hb and RBC. The metabolic costs associated with DNA repair and detoxification of ozone and/or ozone by-products, as well as an increased expenditure of energy to sustain fish metabolism, allowing less energy for growth, can have negative repercussions on turbot growth performance. Taking into account the overall data, it was demonstrated that juvenile turbot were not able to fully adapt to ozonated water under realistic conditions (considering the tested ozone levels and the exposure duration) and thus, the interference with fish health is hypothesized. The present findings contribute to a biological based knowledge of ozone toxicity and to the establishment of safety margins in aquaculture practices adopted in recirculation systems, promoting sustainability and fish welfare. Though the present study was designed to assess the impacted of ozonated water in the context of recirculation aquaculture systems (RASs), the risk to wild aquatic populations resulting from discharges of ozone primarytreated effluents (municipal and industrial) cannot be overlooked. In this regard, the genotoxic potential demonstrated can assume particular importance due to causal linkage with malformations and neoplastic lesions.

Peripheral blood leucocytes of the turbot, Scophthalmus maximus, were characterised into 4 distinct groups following morphological, morphometric and histochemical examination. Total and differential cell counts were determined. Thrombocytes, the most abundant leucocyte type (52%), were highly mobile and encountered in several morphological forms. Granulocytes, representing 5.6% of the leucocyte population, histochemically most resembled the mammalian neutrophil. Both large and small lymphocytes (40.8%), were encountered. Monocytes were rarely observed (1.6%). Thrombocytes and monocytes were phagocytic in vitro at 12oc and 22oc, showing increased phagocytic activity at the higher temperature. The thymus was paired and consisted of a well developed outer cortex and an inner meduallary region. The spleen was bounded by a fibrous tissue capsule and contained a large volume of blood. Diffuse areas of red and white pulp, ellipsoids and melanomacrophage centres were apparent. Lymphocytes, thrombocytes and mature erythrocytes made up the cellular components. The kidney, located beneath the vertebral column contained haemopoietic tissue throughout. Excretory tubules were evident posteriorly. Cellular elements included developing granulocytes, large and small lymphocytes and melanomacrophages. Investigation of ontogenic development of the lymphoid tissue, from 24h post-hatch to the completion of metamorphosis (Day 63) revealed thymic, splenic and kidney rudiments all present at Day 4 with the first lymphoid cells appearing in thymus and kidney by Day 8. Splenic lymphoid cells and the development of areas of white pulp were apparent by Day 28. Differentiation of the thymus had occurred and melanomacrophage centres were seen in the spleen, completing structural lymphoid development by Day 63. Critical stages of lymphoid ontogeny were correlated with easily recognisable external morphological features. A study of the kinetics of carbon clearance by the reticuloendothelial system, revealed a phagocytic capacity in the spleen, kidney and heart. Splenic carbon was seen at 20min post injection, accumulating around ellipsoids and rising to a maximum level at 24h. By Day 5 carbon levels within phagocytes, by now more distant from the ellipsoids, had begun to decrease and carbon was seen within melanomacrophages. Levels of kidney carbon, present within large macrophage-like cells which increased in size forming larger aggregations, increased to a maximum at Day 3. Clearance appeared more rapid in the posterior kidney. Low level uptake was seen within the epicardium. Carbon uptake was not observed in the liver or gill. Kidney leucocyte migration in vitro was examined to a range of chemoattractants using a number of assays. 24h bacterial culture supernatants of Vibrio alginolyticus induced significant cellular responses. The under agarose assay demonstrated migration inhibition to 100%, 50% and 40% supernatant dilutions. Enhanced migration was detected to dilutions of 5-50% in the microchemotaxis chamber, being optimal at 20%. The leucocyte polarisation assay demonstrated cell orientation in response to I 00% culture filtrate and the capillary tube migration assay revealed cellular inhibition at concentrations of 10% &amp; SO%. Leukotriene B4 (LTB4) also induced migration in the filter-based assay, being optimal at to-7M. Cellular migration and orientation were observed in filter and polarisation assays to turbot serum, with normal and activated serum inducing elevated responses in the filter based assay. No response was detected by any of the assay systems to n-formylmethionyl-leucyl- phenylalanine (FMLP) or casein at any concentration tested. Results are discussed in relation to the cellular defence mechanisms of fish.

Ce mémoire présente la mise en évidence d'un gène codant pour une protéine de type MXR chez un poisson benthique, le turbot Scophthalmus maximus, l'évaluation de son expression constitutive dans plusieurs tissus et la mesure de son activité au sein d'hépatocytes en culture. Afin d 'étudier l'activité du système MXR dans les hépatocytes de turbot juvénile, un protocole de culture cellulaire en agrégats a été développé<br>Here we report the existence of a gene encoding a MXR-related protein in a benthic fish species, the turbot, Scophthalmus maximus, its constitutive expression in several tissues and the assessment of its activity in cultured fish hepatocytes. In order to study the activity of this system in juvenile turbot hepatocytes, a cell culture protocol was developped

The culture of turbot Scophthalmus maximus is currently conducted only in tanks, unlike many pelagic species which are also grown in net cages. Despite the demersal habit of this species, deep pelagic fish tanks are often used with little or no adaptations. A multidisciplinary study was conducted to establish the consequences of several management regimes, primarily a decrease in water depth, on more than a total of 40 biological, water quality and hydrodynamic parameters. Fish fitness, performance and behaviour, exit age distribution, flow visualization, flow velocity determination and water quality determination studies were conducted. Results were discussed in relation to optimal tank management strategies, suitable tank designs, or adaptations to existing designs. A statistical model was proposed. A decrease in water depth from 18 - 9 cm decreased dead volumes from 6.95 - 1.37 1. An increase in depth from 3 - 18 cm increased turbot specific growth rate by 0.44 % day-1 . Tank hydrodynamics had little influence on biological or water quality parameters, despite the large range of water depths relative to the size of the tanks. It was more probable that stocking density and biomass were the major influences on water quality and this in turn may have influenced fish performance. The advantages of reducing water depth in a culture tank were more numerous than the disadvantages.

To date, the structural significance of the skin of fish larvae in osmoregulation has received little attention and the evidence for salt secretion by cutaneous chloride cells is based largely on morphological observations. Thus, in the present study, a combination of microscopical and electrophysiological techniques were utilised to determine the role of the skin of early post-hatch turbot larvae in osmoregulation. A number of specialised structural features were revealed in the skin of the turbot larva with electron microscopy which would appear to provide some protection against the high osmotic and ionic gradients tending to dehydrate and salt load the body tissue and fluids. In the heterogenous epidermis, consisting of both transporting and non-transporting cells, only the shallow junctions between chloride cells and accessory cells were believed to permit ion influx and/or water loss via the paracellular pathway; the extensive junctions between adjacent pavement cells and pavement cells and neighbouring chloride cells effectively occluding the passage of ions and water through the extracellular space. Chloride cells were revealed in the skin and prebranchial epithelium of the turbot larva from hatching, but accessory cells, and thus "leaky" junctions, were only observed in association with the closely juxtaposed chloride cells in the prebranchial epithelium which, although densely packed, represented just a small area of the otherwise "tight" skin. Water and ion permeation through the external plasma membrane of the superficial pavement cells might further be impeded by the extracellular glycocalyx coat observed in TEM. In addition, the large numbers of mucous cells, which were a characteristic feature of the skin of the turbot larva, may produce a protective mucus coating of low permeability. The apparent "tightness" of the skin was reflected by the measurements of diffusional water permeability (Pdiff) from early stage larvae which suggested that the larvae of turbot were relative impermeable to water compared with the gills of adults. Nevertheless, the rates of water turnover were still sufficiently high that a net osmotic loss of water must be replaced by water uptake through drinking. The observation that the Pdiff of early stage turbot larvae increased with development substantiates earlier supposition that the drinking rates of larvae are a direct function of the permeability of the larva to water. A study of the chronology of chloride cell development utilising specific fluorochromes and electron microscopy revealed that the prebranchial chloride cells, which closely resembled the chloride cells described in the branchial epithelium of juveniles, were both numerous and well equipped to participate in active salt extrusion in turbot larvae even at hatching. In view of the early hypertrophy and proliferation of the prebranchial cells, their rapid increase in Na+,K+-ATPase binding sites, and the subsequent degeneration of the cutaneous chloride cells observed with larval development, it was concluded that the prebranchial chloride cells are the primary site for active ion excretion shortly after yolksac absorption. The potential importance of the cutaneous chloride cells in salt extrusion was also considered, but in view of the apparent lack of accessory cell associations and the small number of apical pits observed in SEM and TEM sections, questions were raised as to the significance of these cells in ion excretion. Measurements of the trans epithelial electrical potential (TEP) from early stage turbot using intracellular micro electrode techniques confirmed that the larvae of turbot maintain ionic gradients by the active extrusion of ions that enter into the body cavity down electrical or chemical gradients. The TEP was found to be largely the result of a Na+ diffusion potential with an additive electrogenic potential due to CI- transport, which was somehow functionally connected to Na+,K+ -ATPase. Furthermore, the concentration of Na+ in the external bathing medium was found to have a direct regulatory influence on the rate of CI- secretion, suggesting that the active secretion of Cl across the skin must be coupled to Na+. These conclusions are consistent with the current theories proposed for salt extrusion by the chloride cells in the adult teleost.

The analytical review was made on the basis of literature data, and archive material, and personal studies of the parasitofauna, which were carried out on the Azov-Black Sea branch of FGBNU "VNIRO" ("AzNIIRH"). The object of the research is parasitic organisms, which parasitize on the Black Sea Turbot - Kalkan. The results of the research prove that the parasitofauna of mature, wild flounder off the southern coast of the Crimean peninsula is represented by 4 species. No parasites are detected in juvenile flounder obtained in an industrial way in the conditions of the research base "Zavetnoe" of the Kerch department of the Azov-Black Sea branch of FGBNU "VNIRO" ("AzNIIRKh").