Venera Ferrito

Assessment of environmental stress in Parablennius sanguinolentus (Pallas, 1814) of the Sicilian Ionian coast.

The blenny Parablennius sanguinolentus was selected as a useful bioindicator of environmental pollution. Chemical parameters in water and sediments from three different sampling sites along the Sicilian Ionian coast were determined and metal concentrations in fish muscle were measured. DNA fragmentation and oxidation in erythrocytes and hepatocytes was determined by the Comet assay and HSP70 expression levels were evaluated in the liver. The results show an increased level of chromium in sediments and high polycyclic aromatic hydrocarbon (PAH) concentrations in water at one site. The bioaccumulation of metals in muscle tissue shows high concentrations of lead in some samples. A high percentage of DNA damage in blood and liver cells, as well as high hepatic levels of HSP70, were found in all the sites. The results demonstrate the usefulness of an integrated chemical and biological approach for the determination of environmental stress.

Morphological and genetic variation in four Italian populations of Lebias fasciata (Teleostei, Cyprinodontidae)

Abstract Morphological and genetic analyses in four Italian populations of Lebias fasciata were carried out in order to assess the level of differentiation among populations. Fourteen meristic and 23 morphometric characters, relative to the skull, vertebral column, and the rays of the dorsal and anal fins were examined. In addition, variations at seven gene loci were investigated by allozyme electrophoresis. Both morphological and genetic results showed a noteworthy differentiation among the four populations which reflects their high degree of isolation. Allozyme results indicated that genetic variation is consistent with geographical distribution of these populations, while morphological differentiation cannot be interpreted biogeographically. The lack of dispersion phases in the life cycle of L. fasciata and its limited potential for gene flow account for the genetic divergence among populations. The inconsistency between morphological and genetic results for the two Sicilian populations may account for appreciable environmental (non‐genetic) influences on the morphological characters examined, which may obscure any enzyme‐morphological relation.

DNA barcoding and COI sequence variation in Mediterranean lanternfishes larvae

Abstract The potential use of Cytochrome c Oxidase I (COI)-DNA barcode sequences for the molecular identification of lanternfish larvae from the Sicilian Channel was investigated at two levels: at an interspecific level by confirming species identification based on morphological characters; and at an intraspecific level to test for the presence of geographical variation of COI-DNA sequences. A reference library of COI sequences was constructed starting from unambiguously identified specimens. Neighbor-joining analysis based on K2P genetic distances formed non-overlapping clusters for all species (Myctophum punctatum, Ceratoscopelus maderensis, Hygophum benoiti, Electrona risso and Lobianchia dofleini) with a 100% bootstrap support for each. Additional COI sequences of lanternfishes from Atlantic Ocean and Balearic Sea samples deposited in BOLD system database were included in the dataset. The present analysis allowed the identification of unknown fish larvae and indicated that there is a relative congruence between morphological and molecular identification approaches. Our preliminary data in Myctophidae species confirm that COI gene can be used as an efficient species-specific marker that is also useful for assessing the geographical provenance of larvae. This information will likely be applicable to the investigation of the population structure in these poorly studied species.

Genetic divergence among and within four Italian populations of Aphanius fasciatus (Teleostei, Cyprinodontiformes)

Due to the natural fragmentation of its habitats, Aphanius fasciatus, a Cyprininodontid living in coastal brackish‐water habitats, is distributed discontinuously with considerable isolation of its populations, and characterized by a high degree of osteological and genetic differentiation among them. The genetic relationships in four different Italian populations were studied using the control region (D‐loop) mitochondrial DNA sequence and the polymorphisms generated by RAPD‐PCR. The results revealed a well‐defined genetic structuring, that was also confirmed by the high Gst and Fst values, and a close relationship between the populations of Ganzirri and Lesina, as well as the isolation of the other two Sicilian populations. Moreover, with respect to the mitochondrial DNA analyses, the total genetic variance was higher among populations, but lower in the case of the RAPD polymorphisms.

Body shape variation and colour change during growth in a protogynous fish

Protogynous sequential hermaphroditism is very common in marine fish. Despite a large number of studies on various aspects of sequential hermaphroditism in fish, the relationship between body shape and colour during growth in dichromatic species has not been assessed. Using geometric morphometrics, the present study explores the relationship between growth, body shape and colouration in Coris julis (L. 1758), a small protogynous labrid species with distinct colour phases. Results show that body shape change during growth is independent of change in colour phase, a result which can be explained by the biology of the species and by the social control of sex change. Also, during growth the body grows deeper and the head has a steeper profile. It is hypothesized that a deeper body and a steeper profile might have a function in agonistic interactions between terminal phase males and that the marked chromatic difference between colour phases allows the lack of strict interdependence of body shape and colour during growth.

Traditional and geometric morphometrics detect morphological variation of lower pharyngeal jaw inCoris julis(Teleostei, Labridae)

Abstract In the present study, variation in the morphology of the lower pharyngeal element between two Sicilian populations of the rainbow wrasse Coris julis has been explored by the means of traditional morphometrics for size and geometric morphometrics for shape. Despite close geographical distance and probable high genetic flow between the populations, statistically significant differences have been found both for size and shape. In fact, one population shows a larger lower pharyngeal element that has a larger central tooth. Compared to the other population, this population also has medially enlarged lower pharyngeal jaws with a more pronounced convexity of the medial-posterior margin. The results are discussed in the light of a possible more pronounced durophagy of this population.

Effect of natural confinement on the gill cell types and bony elements of Lebias fasciata (Teleostei, Cyprinodontidae): A morphological and immunohistochemical analysis

Abstract Histochemical and immunohistochemical techniques were used to investigate the effect of stress from heavy metals on the respiratory epithelia of the cyprinodont Lebias fasciata living in confined natural environments with different degrees of pollution (brackish swamps of Faro‐Ganzirri and Lesina). This effect was evaluated on cytokeratins and calcium‐binding proteins, with particular reference to the presence of neuronal nitric oxide synthase in the cells of the diffuse neuroendocrine system (DNS). A morphometric examination was also performed to identify possible cranio‐facial and vertebral anomalies; however, the results were negative for all specimens from the two environments. Regarding the presence of heavy metals, only slight differences were found between the two environments, except for the higher concentration of aluminum in the Lesina swamp. In the gills of individuals from the latter environment, the epithelium presented a morphologically and immunohistochemically modified structure, with a concomitant over‐production of mucus; this acts as a barrier to oxygen diffusion, causing strong hypoxia. Therefore, it is hypothesized that the high number of DNS cells and nerve fibers im‐munopositive to nNOS in the respiratory epithelium of Lebias fasciata specimens from lesina is a local reaction to hypoxia.

Pharyngeal and oral jaw differentiation in five populations of Lebias fasciata (Teleostei, Cyprinodontidae)

Abstract The degree of osteological differentiation of the pharyngeal and oral jaws in five populations of Lebias fasciata was studied. Fourteen morphometric and meristic osteological characters were examined. The results allowed us to differentiate the five populations of L. fasciata and particularly that of Manzonara, living in the Salso river and showing a more evident osteological differentiation. It is probable that the observed morphological differentiation among populations of L. fasciata could be a result of their isolation and that the characters examined could represent partially or totally fixed genetic adaptations.

Osteological and molecular analysis of three Sicilian populations of Aphanius fasciatus (Teleostei, Cyprinodontidae)

Abstract The study of three Sicilian populations of Aphanius fasciatus was carried out by examining the mitochondrial control region and the morphology of the bony elements of the skull and vertebral column. The osteological and molecular data obtained indicate a marked differentiation between the populations examined resulting from their isolation, even if the dendrograms of the two approaches are dissimilar. Molecular investigations show that populations are characterized by haplotypes that are well defined in relation to the limited gene flow; while the osteological investigation may account for appreciable environmental influences on the morphological characters.

A COI Nonsynonymous Mutation as Diagnostic Tool for Intraspecific Discrimination in the European Anchovy Engraulis encrasicolus (Linnaeus)

The European anchovy, Engraulis encrasicolus, is currently one of the principal target species for commercial fisheries in Europe. In this study, the mitochondrial Control Region (CR) and the Cytochrome Oxidase I (COI) mitochondrial gene were analyzed in 74 specimens of E. encrasicolus from four localities in the central Mediterranean. In both populations, the two markers revealed the presence of two main haplogroups, A and B, already detected in previous investigations of different classes of molecular markers. Both CR and COI markers consistently identified two haplogroups. The COI sequence analysis identified a non-synonymous transversion (T to G) at position 116 of the translated sequence, resulting in an amino acid change. All COI sequences of haplogroup A had an amino acid sequence with alanine in this position, while serine was present in the same position in haplogroup B. The two haplogroups A and B were also discriminated by the variable number of TACA elements at the 5’-end of the mitochondrial CR. The selection tests applied to the COI dataset revealed that codon 116 was not under positive selection, that seven amino acid changes were under purifying selection, and that two amino acids were under episodic positive selection.