EELS

The Elopomorpha (eels and relatives) is a morphologically diverse group of predominantly marine teleost fishes comprising about 1000 species placed in 25 families. It is one of the three major living teleost lineages along with the Osteoglossomorpha and Clupeocephala. Among a few morphological synapomorphies that have been offered as evidence for the monophyly of the Elopomorpha, the remarkable leptocephalus larvae stand out. Several studies aiming at reconstructing the elopomorph phylogeny using morphological or molecular characters led to inconsistent results. In this study, we have tested previous hypotheses regarding inter-and intra-relationships of the Elopomorpha using a multi-locus dataset composed of three nuclear and three mitochondrial genes. Our analyses were based on likelihood phylogenetic reconstruction methods using different character-weighting data matrices and gene partition schemes to assess reliability of our findings. Our results confirm the respective monophyly of the Elopomorpha, Osteoglossomorpha and Clupeocephala. The majority of our analyses identify the Elopomorpha as the sister group of a clade containing the rest of the Teleostei. Within the Elopomorpha, the Elopiformes is the sister group of the remaining taxa. The Albuliformes sensu Forey et al. (1996) and the Notacanthiformes are never sister-taxa in our phylogenetic trees, in contradiction with the recent mitogenomic hypothesis and current classification. Our results place the Notacanthiformes as the sister group of the Anguilliformes, including Saccopharyngiformes. Among anguilliforms, the families Congridae and Muraenesocidae are not monophyletic. The recently discovered anguilliform ''living fossil'' family Protanguillidae is not the sister group of the remaining Anguilliformes, instead, the sister group of the Synaphobranchidae. Based on the results presented here, we propose a revised classification for the Elopomorpha, comprised of four orders, including a resurrected Notacanthiformes but surrendering the Saccopharyngiformes. Within Anguilliformes, we recognized four monophyletic suborders named Protanguilloidei, Muraenoidei, Anguilloidei, and Congroidei.

Anguilliformes are an ecologically diverse group of predominantly marine fishes whose members are easily recognized by their extremely elongate bodies, and universal lack of pelvic fins. Recent studies based on mitochondrial loci, including full mitogenomes, have called into question the monophyly of both the Anguilliformes, which appear to be paraphyletic without the inclusion of the Saccopharyngiformes (gulper eels and allies), as well as other more commonly known eel families (e.g., Congridae, Serrivomeridae). However, no study to date has investigated anguilliform interrelationships using nuclear loci. Here we present a new phylogenetic hypothesis for the Anguilliformes based on five markers (the nuclear loci Early Growth Hormone 3, Myosin Heavy Polypeptide 6 and Recombinase Activating Gene 1, as well as the mitochondrial genes Cytochrome b and Cytochrome Oxidase I). Our sampling spans 148 species and includes 19 of the 20 extant families of anguilliforms and saccopharyngiforms. Maximum likelihood analysis reveals that saccopharyngiform eels are deeply nested within the anguilliforms, and supports the non-monophyly of Congridae and Nettastomatidae, as well as that of Derichthyidae and Chlopsidae. Our analyses suggest that Protanguilla may be the sister group of the Synaphobranchidae, though the recent hypothesis that this species is the sister group to all other anguilliforms cannot be rejected. The molecular phylogeny, time-calibrated using a Bayesian relaxed clock approach and seven fossil calibration points, reveals a Late Cretaceous origin of this expanded anguilliform clade (stem age $116 Ma, crown age $99 Ma). Most major (family level) lineages originated between the end of the Cretaceous and Early Eocene, suggesting that anguilliform radiation may have been facilitated by the recovery of marine ecosystems following the KP extinction.

Dichlorvos (2,2-dichlorovinyl dimethyl phosphate, DDVP) is an organophosphorus (OP) insecticide and acaricide extensively used to treat external parasitic infections of farmed fish. In previous studies we have demonstrated the importance of the glutathione (GSH) metabolism in the resistance of the European eel (Anguilla anguilla L.) to thiocarbamate herbicides. The present work studied the effects of the antioxidant and glutathione pro-drug N-acetyl-l-cysteine (NAC) on the survival of a natural population of A. anguilla exposed to a lethal concentration of dichlorvos, focusing on the glutathione metabolism and the enzyme activities of acetylcholinesterase (AChE) and caspase-3 as biomarkers of neurotoxicity and induction of apoptosis, respectively. Fish pre-treated with NAC (1 mmol kg −1 , i.p.) and exposed to 1.5 mg l −1 (the 96-h LC 85 ) of dichlorvos for 96 h in a static-renewal system achieved an increase of the GSH content, GSH/GSSG ratio, hepatic glutathione reductase (GR), glutathione S-transferase (GST), glutamate:cysteine ligase (GCL), and ␥-glutamyl transferase (␥GT) activities, which ameliorated the glutathione loss and oxidation, and enzyme inactivation, caused by the OP pesticide. Although NAC-treated fish presented a higher survival and were two-fold less likely to die within the study period of 96 h, Cox proportional hazard models showed that hepatic GSH/GSSG ratio was the best explanatory variable related to survival. Hence, tolerance to a lethal concentration of dichlorvos can be explained by the individual capacity to maintain and improve the hepatic glutathione redox status. Impairment of the GSH/GSSG ratio can lead to excessive oxidative stress and inhibition of caspase-3-like activity, inducing cell death by necrosis, and, ultimately, resulting in the death of the organism. We therefore propose a reconsideration of the individual effective dose or individual tolerance concept postulated by Gaddum 50 years ago for the log-normal dose-response relationship. In addition, as NAC increased the tolerance to dichlorvos, it could be a potential antidote for OP poisoning, complementary to current treatments.

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Mastacembelocleidus gen. n. (Monogenoidea: Dactylogyridae) is proposed to include two species collected and redescribed from spiny eels (Mastacembelidae) in India and Iraq: Mastacembelocleidus bam (Tripathi, 1959) comb. n. (syn. Ancyrocephalus bam Tripathi, 1959) from the gills of Macrognathus pancalus (new host record) and Macrognathus aculeatus (Synbranchiformes: Mastacembelidae) from Lucknow, India; and Mastacembelocleidus heteranchorus (Kulkarni, 1969) comb. n. (syn. Urocleidus heteranchorus Kulkarni, 1969) from the gills of Mastacembelus armatus from Lucknow, India, and Mastacembelus mastacembelus (new host record) from the environs of Erbil, Iraq (new locality record). Urocleidus rhyncobdelli Jain, 1959, Haliotrema tandani Agrawal et Singh, 1982 and Urocleidus raipurensis Dubey, Gupta et Agarwal, 1992 are considered junior subjective synonyms of M. bam.

Dichlorvos (2,2-dichlorovinyl dimethyl phosphate, DDVP) is an organophosphorus (OP) insecticide and acaricide extensively used to treat external parasitic infections of farmed fish. In previous studies we have demonstrated the importance of the glutathione (GSH) metabolism in the resistance of the European eel (Anguilla anguilla L.) to thiocarbamate herbicides. The present work studied the effects of the antioxidant and glutathione pro-drug N-acetyl-l-cysteine (NAC) on the survival of a natural population of A. anguilla exposed to a lethal concentration of dichlorvos, focusing on the glutathione metabolism and the enzyme activities of acetylcholinesterase (AChE) and caspase-3 as biomarkers of neurotoxicity and induction of apoptosis, respectively. Fish pre-treated with NAC (1 mmol kg −1 , i.p.) and exposed to 1.5 mg l −1 (the 96-h LC 85 ) of dichlorvos for 96 h in a static-renewal system achieved an increase of the GSH content, GSH/GSSG ratio, hepatic glutathione reductase (GR), glutathione S-transferase (GST), glutamate:cysteine ligase (GCL), and ␥-glutamyl transferase (␥GT) activities, which ameliorated the glutathione loss and oxidation, and enzyme inactivation, caused by the OP pesticide. Although NAC-treated fish presented a higher survival and were two-fold less likely to die within the study period of 96 h, Cox proportional hazard models showed that hepatic GSH/GSSG ratio was the best explanatory variable related to survival. Hence, tolerance to a lethal concentration of dichlorvos can be explained by the individual capacity to maintain and improve the hepatic glutathione redox status. Impairment of the GSH/GSSG ratio can lead to excessive oxidative stress and inhibition of caspase-3-like activity, inducing cell death by necrosis, and, ultimately, resulting in the death of the organism. We therefore propose a reconsideration of the individual effective dose or individual tolerance concept postulated by Gaddum 50 years ago for the log-normal dose-response relationship. In addition, as NAC increased the tolerance to dichlorvos, it could be a potential antidote for OP poisoning, complementary to current treatments.

The freshwater eels have fascinated biologists because of their spectacular long-distance migrations between their freshwater habitats and their spawning areas far out in the ocean . Recent progress on the molecular phylogeny of freshwater eels suggests that they originated in the tropics (4), and information on the reproductive ecology and recruitment of tropical species will provide new insight into the evolution of the spawning migration of the freshwater eels (5, 6). However, the larvae (leptocephali) of the many sympatric tropical species are morphologically similar , so they are impossible to identify, and their spawning areas are thus virtually unknown. Recently, however, we have collected small leptocephali from around Sulawesi, Indonesia, and have used species-specific genetic markers to identify them as larvae of Anguilla celebesensis and A. borneensis, which provides the first definitive information about the general spawning areas of these tropical eels. Moreover, the discovery of a spawning area of A. celebesensis in Tomini Bay and the presence of small specimens of two species in the Celebes Sea indicate that, in contrast to the long migrations made by temperate eels, tropical eels make much shorter migrations to spawn in areas near their freshwater habitats. This difference in migratory behavior may reflect an evolutionary cline among freshwater eels that extends from tropical to temperate regions.

Naobranchia Hesse, 1863 is a genus of the family Lernaeopodidae. This report presents an illustrated description of the adult female and male of a new species of this genus collected from the gill filaments of Muraenesox bagio (Hamilton) (pike conger) caught off the coast of Richards Bay, KwaZulu-Natal, South Africa. Its morphological features were examined using light and scanning electron microscopy. Characteristic features of the female Naobranchia kabatana n. sp. include egg-sacs situated along most the length of the trunk, cephalothorax and trunk of about equal lengths, and eggsacs, lacking distinct sclerotised bands, which meet at the posterior end of the body and usually obscure the abdomen and caudal rami in ovigerous specimens. The male has no division into the cephalothorax and trunk, resulting in an unsegmented body with a prominent genito-abdominal papilla in a subterminal position.

The sperm of European eel shows a high density and the time of spermatozoa motility is very short after activation with sea water. These characteristics make difficult the sperm handling and its quality assessment. Several diluents were previously described for the Japanese eel obtaining over 3 weeks’ conservation times under refrigeration, but they rendered bad results in the European species. In the present study, several diluents were developed taking as basis the P1 medium, and using different dilution ratios (1 : 50, 1 : 100) and two pH (6.5, 8.5). The effect of the addition of bovine serum albumin (BSA, 2% w/v) was also evaluated. At 24 h, undiluted samples already showed significant lower motility and viability than sperm samples diluted in the different media. The results for diluents with pH 6.5 and 8.5 were different. Spermatozoa diluted in media at pH 6.5 cannot be activated at 24 h, while samples diluted in the diluents with pH 8.5 and added with BSA did not show significant differences with respect to the fresh sperm motility until 48 h. The viability (percentage of alive cells) did not show differences until 1 week, independent of the dilution ratio. After 1 week, the motility was approximately 30% in the media containing BSA, which presented no differences for head size of the spermatozoa (perimeter and area) until 72 h and 1 week, respectively. In conclusion, the combination of one medium having similar physico-chemical characteristics to the seminal plasma, including pH 8.5, and supplemented with BSA can be used in different dilution ratios for the sperm’s short-term storage, preserving its motility capacity.

The effects of aqueous extracts from a cyanobacteria species, Anabaena spiroides, on fish (Odontesthes argentinensis), crab (Callinectes sapidus), and purified eel acetylcholinesterase (AChE) activity were studied. In vitro concentrations of A. spiroides aqueous extract that inhibited 50% of enzyme activity (IC50) were 23.0, 17.2, and 45.0 mg/L of lyophilized cyanobacteria for eel, fish, and crab AChE, respectively. Eel AChE inhibition follows pseudo-first-order kinetics, the same expected for organophosphorus pesticides. Inhibition of purified eel AChE using mixtures of bioxidized malathion and aqueous extract of A. spiroides showed a competitive feature (p Ͻ 0.05), suggesting that the toxin(s) could be structurally similar to an organophosphorus pesticide and that toxins present in the aqueous extract inhibit the active site of the enzyme. The inhibition recovery assays using 2-PAM (0.3 mM) showed that (1) bioxidized malathion inhibited 27.0 Ϯ 1.1% of crab and 36.5 Ϯ 0.1% of eel AChE activities; (2) with bioxidized malathion ϩ 2-PAM the registered inhibition was 13.2 Ϯ 2.1% and 3.7 Ϯ 0.5% in crab and eel AChE, respectively; (3) the aqueous extract from A. spiroides inhibited 17.4 Ϯ 2.2% and 59.9 Ϯ 0.5% of crab and eel AChE activity, respectively; and (4) aqueous extract ϩ 2-PAM inhibited 22.3 Ϯ 2.6 and 61.5 Ϯ 0.2% of crab and eel AChEs. The absence of enzyme activity recovery after 2-PAM exposure could imply that the enzyme aging process was extremely quick.

The expression of the recombinant diphtheria toxin mutant CRM197 in bacteria other than Corynebacterium diphtheriae has proven to be difficult. Here we propose a new and alternative procedure for the production of full-length CRM197 in Escherichia coli. The present study relates specifically to the expression of an artificial sequence and to a method for the isolation and purification of the corresponding protein. In particular, a synthetic gene coding for CRM197, bearing a short histidine tag and optimized for E. coli codon usage, was cloned in the pET9a vector. Accordingly, the over-expression of the protein was simply induced with arabinose in E. coli BL21AI. The recombinant protein was insoluble and always found inside protein aggregates, which were solubilised using urea. Surprisingly, the expression of CRM197, devoid of the short tag, always failed. Following a refolding step, the his-tagged CRM197 was purified by affinity and gel-filtration chromatography and the purity of the final preparation reached 95%. Interestingly, the recombinant protein features DNase activity, indicating that the presence of the tag is not affecting its biochemical properties. However, the removal of the synthetic tag could be easily obtained by incubating the target protein with a proper quantity of a commercial enterokinase.

Several extracts of the leaves and fruits of Juglans regia L. were assessed for their neuroprotective effects through antioxidant and anti-cholinesterase methods. Anticholinesterase activity was determined against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), the enzymes vital for Alzheimer's disease, at 50, 100 and 200 mg ml 21 . Antioxidant activity was tested using radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH), N,N-dimethyl-p-phenylenediamine (DMPD), superoxide (SO), nitric oxide (NO) and hydrogen peroxide (H 2 O 2 ) radicals, as well as ferric ion-chelating capacity, ferric-and phosphomolybdenum-reducing antioxidant power at 500, 1000 and 2000 mg ml 21 . Total phenol and flavonoid quantification of the extracts was calculated. The extracts scavenged DPPH radical in varying degrees; however, they did not scavenge DPMD and H 2 O 2 . Only the dichloromethane and water extracts were able to quench SO (10.09^1.38%) and NO (24.09^2.19%) radicals, respectively, at low level. The extracts showed either low or no BChE inhibition and no AChE inhibition.

The natural reproductive ecology of freshwater eels remained a mystery even after some of their offshore spawning areas were discovered approximately 100 years ago. In this study, we investigate the spawning ecology of freshwater eels for the first time using collections of eggs, larvae and spawning-condition adults of two species in their shared spawning area in the Pacific. ovaries of female Japanese eel and giant mottled eel adults were polycyclic, suggesting that freshwater eels can spawn more than once during a spawning season. The first collection of Japanese eel eggs near the West mariana Ridge where adults and newly hatched larvae were also caught shows that spawning occurs during new moon periods throughout the spawning season. The depths where adults and newly hatched larvae were captured indicate that spawning occurs in shallower layers of 150-200 m and not at great depths. This type of spawning may reduce predation and facilitate reproductive success.

Contamination of aquatic systems is a major environmental stress that can interfere with predator-prey interactions, altering prey or predator behavior differentially. We determined toxicity parameters of the fungicide trifloxystrobin (TFS) and examined its effects on predation rate, using a fish predator (Synbranchus marmoratus) and four anuran tadpole species as prey (Rhinella arenarum, Physalaemus santafecinus, Leptodactylus latrans, and Elachistocleis bicolor). TFS was not equally toxic to the four tadpole species, E. bicolor being the most sensitive species, followed by P. santafecinus, R. arenarum, and L. latrans. Predation rates were evaluated using different treatments that combined predator and prey exposed or not to this fungicide. TFS would alter the outcome of eel-tadpole interaction by reducing prey movements; thus, prey detection would decrease and therefore tadpole survival would increase. In addition, eels preyed selectively upon non-exposed tadpoles avoiding the exposed ones almost all throughout the period evaluated. Predation rate differed among prey species; such differences were not due to TFS exposure, but to interspecific differences in behavior. The mechanism that would explain TFS-induced reduction in predation rates remains unclear; however, what is clear is that sublethal TFS concentrations have the potential to alter prey behavior, thereby indirectly altering predator-prey interactions. In addition, we consider that predator-prey relationships are measurable responses of toxicant exposure and provide ecological insight into how contaminants modify predator-prey interactions.

The concentrations of six polychlorobiphenyl (PCB) congeners in sediments and four classes of biotic species of the aquatic food chain were investigated in a freshwater lake near Amsterdam. Despite the low concentrations of the contaminants in the sediment, significant amounts of PCBs were found in plankton, macro-invertebrates and fish. The composition of the PCB mixtures found in the various organisms cannot be explained in terms of simple partitioning of the PCB congeners between sediment, water, and organisms, tn addition to bioconcentration, it is likely that biomagnification via consumption of contaminated food also contributed significantly to the total PCB concentrations. This is most pronounced for the higher trophic food-chain organisms. Studying bioaccumulation processes by monitoring just one type of organism is probably not very suitable, due to the pronounced differences in accumulation patterns demonstrated for the different organisms. In addition, significant differences were found in the accumulation of the six PCBs in the various biotic samples. This indicates that the fate of mixtures of PCBs is determined by the fate of the individual congeners and therefore cannot be monitored in terms of total PCBs concentrations.

This review focuses on recent developments in the molecular biology of ion and water transporter genes in fish and the potential role of their products in osmoregulation in both freshwater and seawater environments. In particular details of isoforms of various ATPases, co-transporters, exchangers and ion channels in the eel as well as other teleost species are described. Many of the teleost transporter isoforms discovered so far, appear to occur as twin or duplicate copies compared to their homologous counterparts in higher vertebrates, although these duplicate isoforms often have distinct tissue-specific and developmental stage-dependent expression patterns. The possible meaning of this information will be examined in relation to the fish genome duplication debate. ᮊ

Individual specialisation can lead to the exploitation of different trophic and habitat resources and the production of morphological variability within a population. Although the ecological causes of this phenomenon are relatively well known, its consequences on individual fitness are less recognised. We have investigated the extent of individual specialisation in resource use and trophic morphology and its fitness consequences through a combination of tagging-recapture, stable isotope analyses and telemetry. The European eel (Anguilla anguilla) was the model species as it displays significant variability in head shape. Independent to their body length, individuals with broader heads displayed a significantly higher trophic position (d 15 N) than individuals with narrower heads. This corresponded with a significantly higher proportion of prey fish in their diet compared with invertebrates and was associated with the use of a habitat niche located further from the river bank. The European eel therefore provides a rare empirical example of individual specialisation in resource use and trophic morphology in a natural population occurring at a very small spatial scale. Individuals with intermediate head morphology displayed lower body condition (a proxy of fitness) than individuals with extreme head morphology (i.e. narrower and broader headed individuals), demonstrating the existence of disruptive selection associated with individual specialisation.

The PCB contamination of fish from the Gironde Estuary (France) was investigated. PCB distribution differed between lean, low-fat and high-fat species. A process of biomagnification was observed in the Gironde estuarine fish assemblage. Health concerns about fish flesh contamination were revealed.

The goal of this study was to investigate how the eyes of different species of moray eel evolved to cope with limitations to vision imposed on them by the photic environments in which they reside. The comparative retinal histological structures and visual pigment characteristics including opsin gene sequences, of four species of moray eel inhabiting diverse habitats (i.e., shallow-water species, Rhinomuraena quaesita and Gymnothorax favagineus, and deep-sea species, Gymnothorax reticularis and Strophidon sathete) were examined. The histological sections showed that retinal layer structures of R. quaestia are significantly different from those of the other three species which likely reflects the effects of distribution depth on the structures. The maximal absorbance wavelength (k max ) of photoreceptor cells, as measured by microspectrophotometry (MSP), showed a close correlation between the k max and the intensity/spectral quality of the light environment where each species lives. The spectra-shift, between shallow and deepsea species, observed in the rods cells results from amino acid substitution in Rh1 gene, while that in cones most likely results from differential expression of multiple Rh2 genes.

The present study investigated the levels, profiles and human health risk of organophosphorus flame retardants and plasticizers (PFRs) in wild European eels (Anguilla anguilla) from freshwater bodies in the highly populated and industrial Flanders region (Belgium). Yellow eels (n ¼ 170) were collected at 26 locations between 2000 and 2009 and for each site, muscle samples of 3-10 eels were pooled and analyzed (n ¼26). Muscle lipid percentages varied widely between 2.4% and 21%, with a median value of 10%. PFRs were detected in all pooled samples in the order of tris-2-chloroisopropyl phosphate (TCIPP) 4triphenyl phosphate (TPHP)42-ethylhexyl diphenyl phosphate (EHDPHP) 4 tris-2-butoxyethyl phosphate (TBOEP) 4tris-2-chloroethyl phosphate (TCEP) 4tris-1,3-dichloro-2-propyl phosphate (TDCIPP). The median sum PFR concentration for all 26 sites was 44 ng/g lw (8.4 ng/g ww), and levels ranged between 7.0 and 330 ng/g lw (3.5 and 45 ng/g ww). Levels and profiles of PFRs in eels showed that sampling locations and river basin catchments are possible drivers of spatial variation in the aquatic environment. Median PFR concentrations were lower than those of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs).

In this work we describe the synthesis and biological evaluation of the tacrine-1,4-dihydropyridine (DHP) hybrids (3-11). These multipotent molecules are the result of the juxtaposition of an acetylcholinesterase inhibitor (AChEI) such as tacrine and a 1,4-DHP such as nimodipine . Compounds 3-11 are very selective and potent AChEIs and show an excellent neuprotective profile and a moderate Ca 2+ channel blockade effect. Consequently, these molecules are new potential drugs for the treatment of Alzheimer's disease.

A new nematode species, Philometra genypteri sp. n. (Philometridae), is described from male and female specimens found in the ovary of red cusk-eel, Genypterus chilensis (Guichenot) (Ophidiidae, Ophidiiformes), from the eastern South Pacific Ocean off the coast of northern Chile. Based on light and scanning electron microscopy examination, the new species differs from most other gonad-infecting Philometra spp. in the length of spicules (126-135 μm), a gubernaculum with dorsal lamella-like structures on its distal end, and the number and arrangement of genital papillae in the male. From a few congeneric, gonad-infecting species with unknown males, it can be distinguished by some morphological and biometrical features found in gravid female (absence of caudal projections, length of firststage larvae or oesophagus, moderately developed anterior oesophageal inflation) and by the host type (fish family) and geographical distribution. P. genypteri is the first philometrid species reported from a fish belonging to the order Ophidiiformes and the second nominal species of Philometra recorded from marine fishes of the eastern South Pacific.

The present study investigated the levels, profiles and human health risk of organophosphorus flame retardants and plasticizers (PFRs) in wild European eels (Anguilla anguilla) from freshwater bodies in the highly populated and industrial Flanders region (Belgium). Yellow eels (n ¼ 170) were collected at 26 locations between 2000 and 2009 and for each site, muscle samples of 3-10 eels were pooled and analyzed (n ¼26). Muscle lipid percentages varied widely between 2.4% and 21%, with a median value of 10%. PFRs were detected in all pooled samples in the order of tris-2-chloroisopropyl phosphate (TCIPP) 4triphenyl phosphate (TPHP)42-ethylhexyl diphenyl phosphate (EHDPHP) 4 tris-2-butoxyethyl phosphate (TBOEP) 4tris-2-chloroethyl phosphate (TCEP) 4tris-1,3-dichloro-2-propyl phosphate (TDCIPP). The median sum PFR concentration for all 26 sites was 44 ng/g lw (8.4 ng/g ww), and levels ranged between 7.0 and 330 ng/g lw (3.5 and 45 ng/g ww). Levels and profiles of PFRs in eels showed that sampling locations and river basin catchments are possible drivers of spatial variation in the aquatic environment. Median PFR concentrations were lower than those of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs).

in plasma thyroid hormones were observed, indicating no or moderate change of the thyrotropic axis during silvering. Similarly, the somatotropic axis was not activated, as shown by pituitary growth hormone expression (protein and mRNA) and plasma levels. In addition, we studied the effects of chronic treatments of female yellow eels with thyroid hormone (thyroxine, T4) and sex steroids (T and E2) on biometrical parameters characteristics of silvering. T induced an increase in eye size and a reduction of digestive tract, whereas T4 and E2 had no effect. These hormonal profi les and experimental data lead to the conclusion that eel silvering should be considered as an onset of puberty rather than a 'genuine' metamorphosis.

The aim of the present study was to assess the environmental quality of Orbetello lagoon (Tyrrhenian coast, Italy), using a biomonitoring method based on measuring organochlorinated pollutants in the Anguilla anguilla, chosen as sentinel organism, and remote sensing data obtained by elaboration of Landsat 7 Enhanced Thematic Mapper (ETM) data of 2002. Polychlorinated biphenyls and organochlorine pesticides were determined by gas chromatography/mass spectrometry in muscle of European eels captured in seven sites having different levels of pollution in Orbetello lagoon. Remote sensing data and chemical analysis showed the Albegna river as a probable vehicle of pesticides (hexachlorocyclohexanes).

Que la Tesis Doctoral titulada: "Study of male reproductive physiology and sperm conservation in the European eel (Anguilla anguilla, Ll.)" ha sido realizada por el Licenciado en Ciencias Biológicas D. David Sánchez Peñaranda en el Departamento de Ciencia Animal bajo su dirección y que, una vez revisado y comprobado el trabajo, consideran que reúne los requisitos necesarios para la obtención del grado de Doctor, por lo que autoriza su presentación.

Identifying factors and processes influencing natural mortality is fundamental to the understanding of population dynamics. Metabolic theory of ecology and experimental studies at the cross-species level suggest the existence of general patterns linking natural mortality to body mass and temperature. However, there is scant evidence that similar relationships also hold at the intra-specific scale, possibly because of the relatively narrow range of sizes and temperatures experienced by most species and the effect of local adaptation, which can obscure links between temperature and vital rates. In this sense, the European eel Anguilla anguilla, a panmictic species with a wide distribution range, provides a paradigmatic case. We compiled data published in the past 30 years on eel mortality during the continental phase of the life cycle for 15 eel stocks and calibrated a general model for mortality, considering the effects of body mass, temperature, stock density and gender. Estimated activation energy (E = 1.2 eV) was at the upper extreme reported for metabolic reactions. Estimated mortality rates (ranging between 0.02 year -1 at 8°C, low density and 0.47 year -1 at 18°C, high density for a body mass of 100 g) were appreciably lower than those of most fishes, most likely due to the exceptionally low energy-consuming metabolism of eel.

Since the 1980s, the eel population has been decreasing dangerously. Persistent Organic Pollutants (POPs) such as Polychlorinated Biphenyls (PCBs) are one of the suspected causes of this decline. A preliminary study of PCB contamination carried out on different fish from the Gironde estuary (southwest of France, Europe) has shown a relatively high level of contamination of eel muscles. In order to characterize the contamination level of PCBs and PBDEs (PolyBrominated Diphenyl-Ethers) in eels from this estuary more than 240 eels were collected during the years 2004-2005 in the Gironde estuarine system, from glass eels to silver eels. Individual European eels were grouped according to length and localization sites. The results have shown a low contamination level of glass eels: respectively 28 ± 11 ng g À1 dw for PCBs and 5 ± 3 ng g À1 dw for PBDEs. The contamination level in eels (expressed in ng g À1 dw) increases from glass eels to silver eels up to 3399 ng g À1 dw of PCBs for the most contaminated silver eel. Such levels of PCBs similar to those observed in Northern Europe, could raise sanitary problems connected with the World Health Organization (WHO) recommendations. These results are worrying for the local people who regularly eat eels caught in the Gironde estuary.

In this work we describe the synthesis and biological evaluation of the tacrine-1,4-dihydropyridine (DHP) hybrids (3-11). These multipotent molecules are the result of the juxtaposition of an acetylcholinesterase inhibitor (AChEI) such as tacrine and a 1,4-DHP such as nimodipine . Compounds 3-11 are very selective and potent AChEIs and show an excellent neuprotective profile and a moderate Ca 2+ channel blockade effect. Consequently, these molecules are new potential drugs for the treatment of Alzheimer's disease.

A new polypore, Perenniporia tibetica, collected in Xizang (Tibet), southwestern China, is described and illustrated on the basis of morphological and molecular characters. Perenniporia tibetica is characterized by an annual growth habit, resupinate basidiocarps with a creambuff to pinkish-buff pore surface and white to cream-colored rhizomorphs, a dimitic hyphal system with slightly dextrinoid and distinctly cyanophilous skeletal hyphae, and basidiospores that are ellipsoid, truncate or not, strongly dextrinoid, and cyanophilous, 6.7-8.7 9 5.3-6.8 lm. Its preliminary phylogenetic relationships are inferred based on sequence data from the ribosomal ITS and LSU regions, both suggesting that P. tibetica forms a distinct lineage in the genus Perenniporia.

The complete coding sequences were determined for four putative vesiculoviruses isolated from fish. Sequence alignment and phylogenetic analysis based on the predicted amino acid sequences of the five main proteins assigned tench rhabdovirus and grass carp rhabdovirus together with spring viraemia of carp and pike fry rhabdovirus to a lineage that was distinct from the mammalian vesiculoviruses. Perch rhabdovirus, eel virus European X, lake trout rhabdovirus 903/87 and sea trout virus were placed in a second lineage that was also distinct from the recognised genera in the family Rhabdoviridae. Establishment of two new rhabdovirus genera, ''Perhabdovirus'' and ''Sprivivirus'', is discussed.

Mastacembelocleidus gen. n. (Monogenoidea: Dactylogyridae) is proposed to include two species collected and redescribed from spiny eels (Mastacembelidae) in India and Iraq: Mastacembelocleidus bam (Tripathi, 1959) comb. n. (syn. Ancyrocephalus bam Tripathi, 1959) from the gills of Macrognathus pancalus (new host record) and Macrognathus aculeatus (Synbranchiformes: Mastacembelidae) from Lucknow, India; and Mastacembelocleidus heteranchorus (Kulkarni, 1969) comb. n. (syn. Urocleidus heteranchorus Kulkarni, 1969) from the gills of Mastacembelus armatus from Lucknow, India, and Mastacembelus mastacembelus (new host record) from the environs of Erbil, Iraq (new locality record). Urocleidus rhyncobdelli Jain, 1959, Haliotrema tandani Agrawal et Singh, 1982 and Urocleidus raipurensis Dubey, Gupta et Agarwal, 1992 are considered junior subjective synonyms of M. bam.

The one-stripe spiny eel, Macrognathus aral (Bloch and Schneider), has been gaining importance not only as a food fish but also as an aquarium fish for its body shape and behaviour. The overall M:F ratio recorded 1:0.27, both the males and females were mostly mature in May-August. The peak values of gonado somatic ratio (GSR) attained during May for males (1.3) and August forfemales (12.4) indicating that the fish have only one breeding season during summer. The range of ova diameter was found to vary from 0.3 to 1.4 mm, the absolute fecundity ranged from 250 (21.6 cm/27.4 g) to 5220.1 (27.2 cm/66.3 g) while relative fecundity ranged from 9.1 to 128.9. The 50% maturity is attained in length group of 10.1-14 cm for males and 14.1-18 cm for females. The species is a moderately fecund, isochronal spawner and having a restricted breeding season. The relationship between fecundity and body weight and length has also been discussed.

The aim of this study was to determine the lens crystallin diversity of degenerative eyes from the rice eel (Monopterus albus) and walking catfish (Clarias batrachus) as compared to that of zebrafish (Danio rerio) by using comparative proteomics methodologies. We endeavored to investigate the evolution of vertebrate lenses particularly concerning the functional loss of lenses in degenerative eyes of rice eels and catfishes living under an environment of perpetual darkness. Fish lenses were collected and homogenized to extract total soluble proteins. The protein mixtures were separated by one- and two-dimensional gel electrophoresis (1D or 2D gel), plus the newer gel-free shotgun proteomic strategy, followed by in-gel digestion and subjection of the digested protein bands or spots to liquid chromatography coupled with tandem mass spectrometry. The proteomics data were analyzed and compared based on the proteomics databank of zebrafish. The soluble lens protein solutions of three pisc...