Lipid and fatty acid composition of muscle and liver from wild and captive mature female broodstocks of white seabream, Diplodus sargus

Total lipids (TL), lipid classes, and their associated fatty acids from muscle and liver of captive and wild mature female broodstocks were investigated in order to estimate the fatty acid requirements of white seabream (Diplodus sargus). The results showed that the percentage of triacylglycerol was higher in liver and muscle of captive fish than in wild fish. The distribution of phospholipid classes in liver and muscle of both fish groups was similar, phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol being the predominant lipid classes. The general pattern of fatty acid distribution in total lipid of liver and muscle from captive and wild fish was similar. However, the relative percentage of specific fatty acids differed in captive and wild fish. The most noteworthy difference was the lower proportion of arachidonic acid (20:4n-6, AA) and the higher proportion of eicosapentaenoic acid (20:5n-3, EPA) in liver and muscle of captive fish with respect to those of wild fish. The proportion of docosahexaenoic acid (22:6n-3, DHA) did not differ between the two fish groups. The differences in EPA and AA proportions between captive and wild fish implied that captive fish presented a higher EPA/AA ratio and a lower DHA/EPA ratio than wild fish. In general terms, in both liver and muscle, the differences in fatty acid composition observed for TL were extended to all lipid classes. The results suggest that the different AA, EPA and DHA proportions in liver and muscle between captive and wild broodstocks are attributed to different levels of these fatty acids in broodstock diets.     

Changes in lipid class and fatty acid composition during development in white seabream (Diplodus sargus) eggs and larvae

To establish the changes which occur during embryogenesis and early larvae development, eggs, yolk-sac larvae (one day old larvae) and absorbed yolk-sac larvae (three day old larvae) of white sea bream were examined for lipid class and fatty acid composition. The development was characterized by a decrease in all lipid classes with the exception of phosphatidylserine (PS) and fatty free acids (FFA) which increased, and sphingomyelin (SM) which remained unchanged. The changes observed in lipid class content and the decrease in fatty acids in total lipid (TL) reflect the utilization and mobilization of lipids during both embryogenesis and early larvae development. Fluctuations in the relative composition of fatty acids in phosphatidylcholine (PC) during development suggest a selective bulk uptake and catabolism of fatty acids in this lipid class. Unlike PC, catabolism of triacylglycerol (TG) fatty acid appears to be non-selective. During development, the decrease in levels of polyunsaturated fatty acids (PUFA) eicosapentaenoic (20:5n-3, EPA) and docosahexaenoic (22:6n-3, DHA) in total lipid denotes their utilization as energy substrate by Diplodus sargus larvae.     

An immunocytochemical study of the pituitary gland of the white seabream (Diplodus sargus)

The adenohypophysis of the white seabream (Diplodus sargus) was studied using histochemical and immunocytochemical techniques. The adenohypophysis was composed of rostral pars distalis, proximal pars distalis and pars intermedia. Prolactin (anti-chum salmon prolactin positive) and adrenocorticotropic (anti-human ACTH positive) cells were found in the rostral pars distalis. Prolactin cells were organized into follicles, while ACTH cells were arranged in cords around neurohypophyseal tissue branches that penetrated the rostral pars distalis. In the proximal pars distalis, somatotropic (anti-chum salmon and anti-gilthead seabream growth hormone positive), gonadotropic (anti-chum salmon -gonadotrophin II and anti-carp -gonadotrophin II positive, but anti-chum salmon -gonadotrophin I negative) and thyrotropic (anti-human -thyrotropin positive) cells were observed. Growth hormone cells were restricted to the dorsal and ventral part of the proximal pars distalis. They were clustered or surrounded the neurohypophyseal branches. Only one type of gonadotrophin cell was identified and they were clustered or isolated in the proximal pars distalis. Scattered groups of thyrotropin cells were located throughout the proximal pars distalis. In the pars intermedia somatolactin (anti-chum salmon and anti-gilthead seabream somatolactin positive) and melanotropic (anti--melanotropic hormone positive) cells were localized. In addition, gonadotrophin cells surrounded the pars intermedia or distributed evenly between somatolactin and melanotropic hormone cells. Somatolactin cells were periodic acid-Schiff negative and surrounded the neurohypophyseal branches intermingled with melanotropic cells. These cells were also immunoreactive to anti-human ACTH antiserum.     

Age,growth and reproduction of the white seabream Diplodus sargus sargus (Linneaus, 1758) off the eastern coast of Algeria

The objective of this study was to determine the basic population‐specific parameters necessary for fish stock assessment in the area and to compare these with data from other Mediterranean regions. White seabream Diplodus sargus sargus (n = 449) were caught along the Algerian coast between December 2005 and December 2006. Total length ranged from 12.2 to 34.6 cm, representing age classes between 0 and 10 years. Validity of the otolith readings for estimating age and growth was supported using the back‐calculation method. The von Bertalanffy growth parameters for all fish were calculated as: TL = 36.3 cm, k = 0.154 year⁻¹, t₀ = −0.488 year. The growth performance index (φ) showed a relatively slow growth of the local population. The length‐weight relationship showed an isometric growth (b = 2.98; r = 0.98). Subspecies Diplodus sargus sargus was characterized as being a proterandric hermaphrodite. Overall ratio of males to females was 1 : 1.4, with males predominant in the smaller size intervals and females in the larger ones. The reproductive season extended from January to May, with a March–April peak in spawning activity. Fifty per cent maturity of the tested cohort was reached at a total length of 20.2 cm for males and 20.0 cm for females.     

Morphology of the tongue dorsal surface in white sea bream (Diplodus sargus sargus)

In the present study, the tongue dorsal surface of the white sea bream Diplodus sargus sargus (Linnaeus, 1758) (teleosts, Sparidae) was studied, to give a support to the knowledge of the anatomical characteristics of the oral cavity of a species with a future potential use in aquaculture. The feeding habits in captivity are one of the critical steps in the species of commercial interest, strictly related to the morphological characteristics of the oropharyngeal cavity. This study was undertaken, using light and scanning electron microscopy, to analyse the morphology of the dorsal tongue surface to show whether relationships are present between the anatomy and the nutritional habits and choices of this farmed species. Three zones, an apex, a body and a root, can be clearly distinguished, with a pouch partially covering the apex. In the pouch, cylindroid and mucosal ridges were observed. Along the whole tongue surface, from the apex to the root, on the medial and lateral parts, many papillae are present, with a fungiform, cylindroid and cone‐like aspect. Taste buds are showed on the dorsal surface of some papillae.     

The gonadal cycle of captive white bream, Diplodus sargus (L.)

A histological study was carried out to follow gonadal changes in captive white bream during the second and third years of life. All but one individual matured as a male. Spawning was found to occur in winter. Environmental factors are likely to have influenced the reproductive activity of the captive fish.     

Organogenesis of the digestive tract in the white seabream,Diplodus sargus. Histological and histochemical approaches

The ontogeny of the digestive tract of the white seabream, Diplodus sargus during the larval development up to day 45 post-hatching (dph) has been studied using histological and histochemical techniques. The oesophageal goblet cells appeared around 6 dph and contained neutral and acid mucosubstances (PAS/diastase-PAS and Alcian Blue pH 2.5 positive reactions). An incipient stomach can be distinguished from 2 dph but the first sign of gastric gland development was detected around 13-15 dph, increasing in number and size by 22-23 dph. Gastric glands were concentrated in the cardiac stomach region and they had a high content of protein rich in tyrosine, arginine and tryptophan. Acidophilic supranuclear inclusions related to pynocitosis of proteins, were already observed in the intestinal cells of the posterior intestine around 4-6 dph (exogenous feeding) and they were present until 25 dph. The intestinal mucous cells appeared between 15-18 dph and contained a mixture of neutral and acid mucosubstances/glycoconjugates, carboxylated ones being more abundant than the sulphated ones. The stomach and gastric glands were fully developed by the first month of life marking the beginning of digestive features characteristic of the juvenile stage. Around 4-6 dph, glycogen, proteins and neutral lipids were observed in the granular cytoplasm of hepatocytes. Strongly acidophilic zymogen granules were also present, at this time, in the basophilic cytoplasm of the exocrine pancreatic acinar cells and contained abundant proteins, especially rich in arginine, tyrosine and tryptophan.     

Basic characteristics of the population dynamic and state of exploitation of Moroccan white seabream Diplodus sargus cadenati (Sparidae) in the Canarian archipelago

Moroccan white seabream Diplodus sargus cadenati (n = 603) were caught off the Canary Islands from April 2000 to March 2001. Total length ranged from 46 to 404 mm. The subspecies was characterized as being dygynous with partial protandry. Overall ratio of males to females was 1 : 2.9. The reproductive season extended from December to May, with a peak in spawning activity in January–February. Fifty per cent maturity was reached at 201 mm total length in males and 216 mm in females. The length–weight relationship for all individuals was described by the following parameters: a = 0.000023, and b = 2.96, when length is given in millimeters and weight in grams. Fish of 0–12 years in age were found. The von Bertalanffy growth parameters for the entire population were: L_∞ = 467 mm, k = 0.143 year^?1 and t₀ = ?2.14 year. Growth parameters differed between males and females. For all fish, instantaneous rates of mortality were Z = 0.68 year^?1, M = 0.31 ± 0.6 year^?1 and F = 0.37 ± 0.6 year^?1; the exploitation ratio was E = 0.54 ± 0.9. Length at first capture for all individuals was 173 mm. The stock exploited above is an assumed optimum.     

The Atlantic-Mediterranean transition: discordant genetic patterns in two seabream species, Diplodus puntazzo (Cetti) and Diplodus sargus (L.)

Sparids are a group of demersal perciform fish of high commercial value, which have experienced an extensive radiation, particularly in the Mediterranean, where they occupy a variety of different niches. The present study focuses on two species: Diplodus sargus and D. puntazzo, presenting a wide distribution from the Mediterranean to the eastern Atlantic coasts. They display similar ecological behaviour and are evolutionary closely related. Both are highly appreciated in fisheries and D. puntazzo is currently under domestication process. However, little is know on their population structure and it is an open question whether any genetic differentiation exists at the geographic level. To address this issue we examined sequence variation of a portion of the mitochondrial DNA (mtDNA) control region in population samples of each of the two species collected over a wide geographic range. In addition to the mtDNA, analysis of nuclear loci (allozymes) was included in the study to compare patterns revealed by nuclear and mitochondrial markers. The studied samples covered an area from the eastern Mediterranean to the Portuguese coasts immediately outside the Gibraltar Strait. The two species revealed a level of sequence polymorphism remarkably different for the control region with the D. puntazzo and D. sargus showing 111 and 28 haplotypes, respectively. Such a difference was not detected with allozyme markers. The two species also showed large differences in their population structure. While D. puntazzo presented a marked genetic divergence between the Atlantic and Mediterranean samples, D. sargus showed little intraspecific differentiation. These results were supported using both mtDNA and allozyme markers, and were interpreted as the consequence of differences in the history of the two species such as fluctuations in the effective population size due to bottlenecks and expansions, possibly combined with present-day differences in levels of gene flow.     

Population structure,length–weight relationship and growth of white seabream,Diplodus sargus sargus (Linneaus, 1758), in Beymelek Lagoon,Turkey

The main objective of this study was to investigate the population structure, length–weight relationship (LWR) and growth of white seabream, Diplodus sargus sargus (L., 1758) in Beymelek Lagoon, Turkey. Samples were collected by gill‐ and trammel nets of various mesh sizes, February 2006 to January 2007. A total of 355 specimens (51 males; 34 females; 270 unidentified) were collected. Male to female ratio was 1.50 : 1. Ages ranged from 0 to 3 years; about 70% were juveniles. Most fish were between 13 and 16 cm in total length and below 90 g in weight. The LWR of all individuals was W = 0.0140 × L^3.1028. The von Bertalanffy growth equation was calculated as L_t = 39.9 × [1 – exp(?0.268 × (t + 1.753)] and the growth performance index (Φ′) was 6.056.     

The hypothalamo-hypophyseal system of the white seabream Diplodus sargus: immunocytochemical identification of arginine-vasotocin,isotocin, melanin-concentrating hormone and corticotropin-releasing factor

The distribution of the neurosecretory hormones vasotocin, isotocin and melanin-concentrating hormone and the hypophysiotropic hormone corticotropin-releasing factor was studied in the hypothalamo-hypophyseal system of the white seabream (Diplodus sargus) using immunocytochemical techniques. Magnocellular and parvocellular perikarya immunoreactive for arginine-vasotocin and isotocin were present in the nucleus preopticus. Perikarya immunoreactive for arginine-vasotocin extended more caudally with respect to isotocin-immunoreactive perikarya. Parvocellular perikarya were located at rostroventral levels and magnocellular perikarya in the dorsocaudal portion of the nucleus. Arginine-vasotocin and isotocin did not coexist in the same neuron. Fibres immunoreactive for arginine-vasotocin and isotocin innervated all areas of neurohypophysis and terminate close to corticotropic and melanotropic cells. Perikarya immunoreactive for melanin-concentrating hormone and corticotropin-releasing factor were observed in the nucleus lateralis tuberis, with a few neurons in the nucleus periventricularis posterior. In addition, melanin-concentrating hormone immunoreactive perikarya were detected in the nucleus recessus lateralis. The preoptic nucleus did not show immunoreactivity for these antisera. Fibres showing melanin-concentrating hormone and corticotropin-releasing factor immunoreactivity ended close to the melanotropic and somatolactotrophic cells of the pars intermedia, and close to the corticotrophic cells of the rostral pars distalis.     

Characterization of eight microsatellite markers in the white sea bream, Diplodus sargus (Teleostei, Sparidae)

The white sea bream, Diplodus sargus (Teleostei, Sparidae), is a species with a high commercial importance in Mediterranean aquaculture. There is currently little information available about the genetic characteristics of cultured populations. In this survey, we have developed eight polymorphic microsatellites for the white sea bream using an enriched genome library protocol. All of them were polymorphic in the 67 individuals tested, 32 of which were wild specimens, and 35 were individuals from a captive F(1) broodstock. These markers can potentially be useful tools for use in population genetic studies.     

Lipid and fatty acid composition of female gilthead seabream during their reproductive cycle: effects of a diet lacking n-3 HUFA

In female sea bream Sparus aurata fed a control diet (C), ovarian levels of neutral lipids (NL) and polar lipids (PL) remained constant between November and March, while a decrease in NL content was observed in liver and muscle. In the same period, liver PL content increased, while no changes were observed in muscle. Between March and June ovarian NL and PL showed a strong decrease, while NL remained constant in liver and muscle. When fish were fed a diet lacking in n-3 highly unsaturated fatty acids, n-3 HUFA (D), the pattern observed was similar to that found in the fish fed diet C, with the exception of liver NL, which increased between March and June. In general, the changes in fatty acid content, in both groups of fish, were highly influenced by the diet given to the broodstock, although these effects were greater on ovarian NL and PL than on liver and muscle lipids. Despite the fact that gilthead seabream females continue feeding during the spawning season, they probably make use of their liver and muscle reserves during the gonadal maturation process. Furthermore, the fatty acid composition of the broodstock diet was reflected in the body composition, especially in the ovaries.     

Lipid and fatty acid composition of the fat body during the female reproductive cycle of Labidura riparia (Insecta Dermaptera)

During the reproductive cycle of the female Labidura riparia, cytological observations show cyclical modifications of lipid droplets in the periovarian adipocyte. Fat body lipids and their constitutive fatty acids are analyzed. The lipids are predominantly triacylglycerols, which increase after adult ecdysis during vitellogenic and non-vitellogenic periods. Small amounts of diacylglycerols and phospholipids are found. Diacylglycerols increase during vitellogenesis and decrease during the non-vitellogenic period. Cytological modifications of lipid droplets are probably related to diacylglycerol fluctuations. Gas-liquid chromatography of fatty acid methyl esters shows oleic acid to be the predominant fatty acid in total lipids and triacylglycerols; unsaturated acids are approximately twice as abundant as saturated acids all along the reproductive cycle. Fatty acid composition of diacylglycerols and phospholipids differs from triacylglycerols and total lipids composition. Palmitic, stearic, oleic and linoleic acids represent the major fatty acids; their relative amounts vary during the different periods of the reproductive cycle. The correlations between fat body lipid changes and ovarian development were discussed and compared with observations made on other insect species. Accepted: 23 April 1997     

Lipid content and fatty acid composition in hypogeous organs ofHelleborus species (Ranunculaceae)

Root and rhizome of fourHelleborus species:H. viridis, H. odorus, H. niger, H. foetidus were examined throughout a two-year period in order to determine the variation of lipid content and fatty acid composition during the ontogenetic cycle. In the deciduous geophytesH. viridis andH. odorus subsp.laxus the lipid content reaches its maximum during the quiescent phase, whereas in the evergreen geophyteH. niger the lipid content is highest during the main growth period. In the chamaephyteH. foetidus lipid content is always very low and it does not show variation throughout the year. In all species the fatty acids detected in the neutral fraction are myristic, palmitic, stearic, oleic and linoleic acid. Palmitic and linoleic acid are always present in larger quantities. The pattern of the relative content of saturated/unsaturated fatty acids seems to be linked to the life form of these species.     

Genetic differentiation of Diplodus sargus (Pisces: Sparidae) populations in the south-west Mediterranean

Allozyme analysis of tissue samples of 1249 white sea bream Diplodus sargus from five localities of the south-west Mediterranean revealed a high degree of genetic polymorphism. The observed heterozygosity ranged from 0.4182 (Cape of Palos) to 0.3138 (Tabarca). Several populations were characterized by unique alleles. Examination of the spatial structure was performed using Nei's distances and F- statistics, and indicated genetic differences between groups. One group, which clustered Tabarca and Guardamar, could be explained by the small geographical distance between them. Mazarrón and Cape of Palos samples showed genetic divergence from other samples (Guardamar, Tabarca and Águilas) and this difference may be as a result of local current systems and larval dispersal.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 249–261.     

Digestive enzyme activities in larvae of sharpsnout seabream (Diplodus puntazzo)

The ontogenesis and specific activities of pancreatic and intestinal enzymes were investigated in sharpsnout sea bream, Diplodus puntazzo, during larval development until the end of weaning on day 50. The green-water technique was carried out for larval rearing in triplicate. Trypsin was first detected as early as hatching and sharply increased related to age and exogenous feeding until day 25, but a sharp decrease was observed towards the end of the experiment. Amylase was determined 2 days after hatching (DAH) and sharply increased to 10 DAH. Afterwards, slight decreases were found between 10 and 20 DAH and then slow alterations were continued until end of the experiment. Lipase was measured for the first time on day 4, and then slight increase was found to 25 DAH. After this date, slow variations were maintained until end of the experiment. Pepsin was firstly assayed 32 DAH related with stomach formation and sharply increased to 40 DAH. Then it was fluctuated until end of the experiment. Enzymes of brush border membranes, alkaline phosphatase and aminopeptidase N, showed similar pattern on specific activities during the first 10 days. Thereafter, while specific activity of alkaline phosphatase slightly decreased to 15 DAH and fluctuated until 20 DAH, aminopeptidase N activity slowly declined to 20 DAH. Afterwards, activity of alkaline phosphatase and aminopeptidase N were sharply increased to 30 DAH, showing maturation of the intestinal digestive process and also these activities continued to slight increase until end of the experiment. The specific activity of cytosolic peptidase, leucine-alanine peptidase sharply increased to on day 8, then suddenly declined to 12 DAH and further decreased until 20 DAH. After this date, in contrast to enzymes of brush border membranes, it sharply decreased to 25 DAH and continued to gradually decline until the end of the experiment. These converse expressions were indicative of a maturation of enterocytes and the transition to an adult mode of digestion.     

Isolation and characterization of nine polymorphic microsatellite markers in the two‐banded sea bream (Diplodus vulgaris) and cross‐species amplification in the white sea bream (Diplodus sargus) and the saddled bream (Oblada melanura)

We have developed nine new microsatellite markers for the two‐banded sea bream (Diplodus vulgaris) from an enriched genome library protocol. All these loci are polymorphic, with mean allelic diversity of 13 (range 5 –21), and expected and observed heterozygosities from 0.641 to 0.932 and 0.428 to 0.914, respectively. Cross‐species tests in two close‐related species of the genus Diplodus (D. sargus and O. melanura) revealed successful amplifications at 8 out of 9 loci, with mean allele number of 4.75 (range 2–8) and 5.50 (range 3 –10), respectively. These results are consistent with the close phylogenetic relationships between the three species, indicating this set of primers might prove useful for studying the levels of genetic diversity and population differentiation in these three species and in other phylogenetically close species of the genus Diplodus and Sparus.