Several nutritional studies have found a direct effect of several vitamins in chondrogenic and osteogenic development during early life stages of marine fish species. In the present study, the effect of vitamin A (VA) in gilthead sea bream skeletogenesis was evaluated by means of four different dietary regimes (enriched rotifers) containing increasing levels of total VA (75, 109, 188 and 723 ng total VA mg − 1 DW). Dietary treatments were offered to larvae during the rotifer-feeding phase (4-20 days after hatching), while later all groups were fed with Artemia nauplii and weaned onto the same inert diet. Different dietary doses of VA affected gilthead sea bream larval growth, survival, performance (maturation of the digestive system) and quality (incidence of skeletal deformities). Higher levels of dietary VA than those included in the commercial emulsion for rotifer enrichment led to different levels and typologies of skeletal deformities, indicating that gilthead sea bream larvae were very sensitive to small increases in dietary VA. The degree of ossification was affected by the level of VA in enriched rotifers: the higher amount of VA in the diet, the higher number of skeletal pieces ossified (R = 0.585, P = 0.04). Dietary VA affected the normal process of bone formation and skeletogenesis, the skeletal structures mostly affected by high amounts of dietary VA were those from the cranial skeleton (splanchnocranium), vertebral centrums and caudal fin complex. The premaxilla, maxilla and dentary bones were the cranial structures affected by dietary VA levels, resulting in a large incidence of animals with compressed snout. Dietary VA also affected the normal development of the opercular complex, and a dose-response dependant effect was observed in relation to the incidence of specimens with incomplete operculum. Body shape was also affected by the level of dietary VA, increasing the incidence of specimens with lordosis, kyphosis and/or scoliosis with the dose of VA, being the prehaemal and caudal vertebrae the most affected regions of the vertebral column with this kind of abnormalities. The caudal fin complex was the most affected region of the skeleton affected by dietary treatments as seen by the high incidence of skeletal deformities in fish fed different doses of dietary VA. Deformities affected all skeletal elements composing the caudal fin, although the most affected ones were, in order of importance, the epurals, hypurals, parahypural, neural arch and uroneurals. Differences in sensitivity to dietary VA amongst caudal fin skeletal elements might be due to their differential ontogenetic development and differences in the exposure time to VA. An excess of dietary VA also accelerated the intramembranous ossification process of vertebral centrums leading to one or two supranumerary vertebrae, and a high incidence of fused and compressed vertebral centrums. The sensibility of the developing skeletal structures to dietary VA levels should incline us to test lower doses of VA in live preys enrichments during ear...

The effects of different levels of vitamin A (VA) in Senegalese sole larval performance and development were evaluated by means of a dietary dose-response experiment using enriched Artemia metanauplii as a carrier of this micronutrient. Larvae were fed from 6 to 27 days post hatch (dph) with enriched Artemia containing graded levels of total VA (1.3, 2.1, 4.5 and 12.9 µg VA mg − 1 DW). The content of VA in live prey directly affected its accumulation in larvae and early juveniles. Retinyl palmitate accumulated during larval ontogeny, whereas retinol showed the opposite trend, decreasing from hatching until 41 dph and then remaining constant until the end of the study.

No abstract

North American brine shrimp Artemia franciscana have been exported worldwide since the 1950s for use in aquarium trade and fish farming. Aquaculture is expanding along the Mediterranean coast, leading to the release of A. franciscana into native Artemia populations. A. franciscana was first detected in 1981 in Portugal and has since spread to saltworks along the East Atlantic flyway used by shorebirds. Once A. franciscana becomes established in a locality, native Artemia tend to disappear. To test whether migratory shorebirds can disperse invasive and native Artemia between wetlands, we extracted Artemia cysts from feces and pellets collected at Castro Marim (Portugal) and Cadiz Bay (Spain) during southward migration. We found that large numbers of viable eggs of A. franciscana and native Artemia parthenogenetica were dispersed by Redshank Tringa totanus, Blacktailed Godwit Limosa limosa, and other shorebirds migrating through the Iberian Peninsula. This is the most extensive field demonstration to date that invertebrates can disperse readily via gut passage through birds.

The hypersaline environments and salterns present in the western Mediterranean region (including Italy, southern France, the Iberian Peninsula and Morocco) contain autochthonous forms of the brine shrimp Artemia, with parthenogenetic diploid and tetraploid strains coexisting with the bisexual species A. salina. Introduced populations of the American brine shrimp A. franciscana have also been recorded in these Mediterranean environments since the 1980s. Based on brine shrimp cyst samples collected in these countries from 1980 until 2002, we were able to establish the present distribution of autochthonous brine shrimps and of A. franciscana, which is shown to be an expanding invasive species. The results obtained show that A. franciscana is now the dominant Artemia species in Portuguese salterns, along the French Mediterranean coast and in Cadiz bay (Spain). Co-occurrence of autochthonous (parthenogenetic) and American brine shrimp populations was observed in Morocco (Mar Chica) and France (Aigues Mortes), whereas A. franciscana was not found in Italian cyst samples. The results suggest these exotic A. franciscana populations originate as intentional or non-intentional inoculations through aquacultural (hatchery effluents) or pet market activities, and suggest that the native species can be rapidly replaced by the exotic species.

Functional males that are produced occasionally in some asexual taxacalled 'rare males' -raise considerable evolutionary interest, as they might be involved in the origin of new parthenogenetic lineages. Diploid parthenogenetic Artemia produce rare males, which may retain the ability to mate with females of related sexual lineages. Here, we (i) describe the frequency of male progeny in populations of diploid parthenogenetic Artemia, (ii) characterize rare males morphologically, (iii) assess their reproductive role, using cross-mating experiments with sexual females of related species from Central Asia and characterize the F1 hybrid offspring viability and (iv) confirm genetically both the identity and functionality of rare males using DNA barcoding and microsatellite loci. Our result suggests that these males may have an evolutionary role through genetic exchange with related sexual species and that diploid parthenogenetic Artemia is a good model system to investigate the evolutionary transitions between sexual species and parthenogenetic strains.

The hypersaline environments and salterns present in the western Mediterranean region (including Italy, southern France, the Iberian Peninsula and Morocco) contain autochthonous forms of the brine shrimp Artemia, with parthenogenetic diploid and tetraploid strains coexisting with the bisexual species A. salina. Introduced populations of the American brine shrimp A. franciscana have also been recorded in these Mediterranean environments since the 1980s. Based on brine shrimp cyst samples collected in these countries from 1980 until 2002, we were able to establish the present distribution of autochthonous brine shrimps and of A. franciscana, which is shown to be an expanding invasive species. The results obtained show that A. franciscana is now the dominant Artemia species in Portuguese salterns, along the French Mediterranean coast and in Cadiz bay (Spain). Co-occurrence of autochthonous (parthenogenetic) and American brine shrimp populations was observed in Morocco (Mar Chica) and France (Aigues Mortes), whereas A. franciscana was not found in Italian cyst samples. The results suggest these exotic A. franciscana populations originate as intentional or non-intentional inoculations through aquacultural (hatchery effluents) or pet market activities, and suggest that the native species can be rapidly replaced by the exotic species.

Biosynthesis of long-chain PUFAs (LC-PUFAs) in vertebrates involves sequential desaturation and elongation of C 18 PUFA, linoleic acid (LOA; 18:2n-6), and ␣ -linolenic acid (LNA; 18:3n-3) ( 1 ). Synthesis of arachidonic acid (ARA; 20:4n-6) and EPA (20:5n-3) from LOA and LNA, respectively, utilizes the same enzymes and pathways. The pre dominant pathway involves ⌬ 6 desaturation of LOA or LNA to 18:3n-6/18:4n-3 that are elongated to 20:3n-6/20:4n-3 followed by ⌬ 5 desaturation to ARA/EPA ( 1 ), but an alternative pathway with initial elongation of LOA or LNA followed by ⌬ 8 desaturation, an inherent ability of some ⌬ 6 desaturases, may be possible ( 2 ). Biosynthesis of DHA (22:6n-3) from EPA can also occur by two pathways. First, the so-called "Sprecher pathway" involves two sequential elongation steps from EPA to 24:5n-3 and a subsequent ⌬ 6 desaturation to 24:6n-3, followed by peroxisomal chain shortening ( 3 ). Second, a more direct pathway has been postulated in some marine fi sh that involves elongation of EPA to docosapentaenoic acid (22:5n-3) followed by ⌬ 4 desaturation to DHA ( 4,5 ).Dietary PUFAs are essential in fi sh, although requirements vary with species ( 6, 7 ). Generally, C 18 PUFAs can satisfy essential FA requirements of freshwater and salmonid species, but most marine fi sh have a requirement for LC-PUFAs such as EPA and DHA ( 8 ). Differing essential FA requirements have been linked to differences in the complement of fatty acyl desaturase (Fads) and elongase of very longchain FA (Elovl) genes ( 9-31 ). Thus, the dependence of Abstract Currently existing data show that the capability for long-chain PUFA (LC-PUFA) biosynthesis in teleost fi sh is more diverse than in other vertebrates. Such diversity has been primarily linked to the subfunctionalization that teleostei fatty acyl desaturase (Fads)2 desaturases have undergone during evolution. We previously showed that Chirostoma estor , one of the few representatives of freshwater atherinopsids, had the ability for LC-PUFA biosynthesis from C 18 PUFA precursors, in agreement with this species having unusually high contents of DHA. The particular ancestry and pattern of LC-PUFA biosynthesis activity of C. estor make this species an excellent model for study to gain further insight into LC-PUFA biosynthetic abilities among teleosts. The present study aimed to characterize cDNA sequences encoding fatty acyl elongases and desaturases, key genes involved in the LC-PUFA biosynthesis. Results show that C. estor expresses an elongase of very long-chain FA (Elovl)5 elongase and two Fads2 desaturases displaying ⌬ 4 and ⌬ 6/ ⌬ 5 specifi cities, thus allowing us to conclude that these three genes cover all the enzymatic abilities required for LC-PUFA biosynthesis from C 18 PUFA. In addition, the specifi cities of the C. estor Fads2 enabled us to propose potential evolutionary patterns and mechanisms for subfunctionalization of Fads2 among fi sh lineages. -GA-2010-276916, LONGFA). Additional funding was obtained from CONACYT, Mexico (INSAM FOINS 102/201...