The present paper describes the characteristic ultrastructural features of spermiogenesis and the spermatozoon of Monorchis parvus (Trematoda, Digenea, Monorchiidae). This spermiogenesis is characterized by a flagellar rotation of about 120 degrees and the formation of a novel ultrastructural element: a centriolar extension. It nevertheless follows the general pattern of digeneans. It begins with the formation of a differentiation zone, comprising striated rootlets associated with two centrioles and an intercentriolar body. The mature spermatozoon presents features allowing the distinction between M. parvus and other digenetic trematodes. It possesses an original anterior extremity. The two central elements of the axonemes appear prior to the peripheral doublets. The external ornamentations of the cell membrane are formed parallel to the central elements. Another peculiarity of the male gamete is the presence of two mitochondria. M. parvus, therefore, differs distinctly from other digenetic trematodes.

This paper constitutes the first ultrastructural study of spermiogenesis and the spermatozoon of a Digenea belonging to the family Zoogonidae, Diphterostomum brusinae. Spermiogenesis follows the general pattern found in the digeneans. It begins with the formation of a differentiation zone in the spermatid. The two centrioles give rise to flagella. These two flagella undergo a rotation of 90 degrees and fuse with the median cytoplasmic process. The proximo-distal fusion occurs at the level of attachment zones. The mature spermatozoon of D. brusinae presents all the features found in the digeneans gametes: two axonemes, mitochondrion, nucleus and two bundles of parallel cortical microtubules. Nevertheless, several characteristics distinguish the spermatozoon of D. brusinae from other digeneans, in particular the external ornamentations of the plasma membrane and the anterior and posterior extremities. The description of the ultrastructural features of reproduction in this species would contribute to the understanding of the phylogenetic relationships in the Zoogonidae family.

The spatial distribution of parasite communities from teleost fishes (Diplodus vulgaris, Mullus surmuletus, Pagellus erythrinus, Phycis phycis, Scorpaena scrofa and Symphodus tinca) was studied in the Bonifacio Strait Marine Reserve (Corsica Island) with different protection levels. Canonical correspondence analysis was used to study spatial patterns and to quantify the importance of site influence on parasite communities. To supplement these results, we used the indicator species analysis (Indval) to identify parasite species as bioindicators of a given ecosystem. Moreover, fish spatial distribution in the marine reserve was evaluated in order to link parasite species occurrence and fish abundance. Several parasite species were associated with a specific site, and some of them were considered as site bioindicators, especially in the western part of the protected area (Bruzzi and Moines Islands). However, the relative abundance of fish followed a different spatial pattern. Stronger fish abundance was observed in the eastern part of the reserve (Lavezzi Islands). The parasite species were correlated to sites inside as well outside the reserve. The parasite distribution seemed not to be influenced by the protection status of the site. Furthermore, in our study, most of the parasite species were not linked to a site. The most important factor influencing their distribution was host specificity. This suggested that the parasite life traits history remained a fundamental determinant in the community composition.

Among all available species, fish are a powerful model for risk-benefit assessments to study the effects of contaminants on human health. Gilthead seabream (Sparus aurata, Linnaeus 1758) and european seabass (Dicentrarchus labrax, Linnaeus 1758) are two species of great economic importance, representing very large production volumes in the Mediterranean. The objective of this study is (1) to analyze the concentrations of Trace Elements (TE) between wild and cultured seabream and seabass specimens, (2) to compare the determined concentrations with other studies, and (3) to increase the data about the potential risks to human health. Our results point to significant intra- and interspecies-specific differences between wild and cultured fish for several trace elements. Several strong and moderate inter-elemental correlations in fish muscle were observed through correlation analysis. In our study, the mean levels of trace elements were still below the standard safety values for fish intended for human consumption. The same results were reached for all the parameters analyzed (international legal limits, estimated weekly intake, provisional tolerable weekly intake, target hazard quotient, target cancer risk), with trace element levels in fish below those that could pose a risk to human health. Consequently, these fish can be considered safe for human consumption. A better understanding of the levels of trace elements in fish would also better inform consumers about the potential risks of exposure to contaminants.

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This study was conducted to evaluate the antibacterial activity of Inula graveolens and Santolina corsica essential oils on Staphylococcus aureus and investigate their effects at the cellular level. The mode of inhibition of both essential oils against S. aureus ATCC 6538P (CIP 53.156) was assessed by determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The effects of time and treatment dose on cell viability were determined by time-kill and bacteriolysis assays. Marked structural changes were observed by transmission electron microscopy (TEM). A bactericidal mode of inhibition was established for both essential oils, which rapidly reduced the cell viability of S. aureus at their MIC (5 mg.ml(-1)). No lysis occurred after treatments with the MIC and eight times the MIC of each essential oil. Invaginations of the plasmic membrane with thickenings of the cell wall as well as an aggregation of the cytoplasmic contents were observed in S. aureus cells treated with the MIC of both essential oils. These results suggest that the cytoplasmic membrane and the cell wall are involved in the toxic action of Inula graveolens and Santolina corsica essential oils.

An assessment of classical and emerging trace element contamination was conducted on gonads of the sea urchin Paracentrotus lividus (Lamarck, 1819), in Corsica (Western Mediterranean). The aim of this study was to evaluate the contamination levels at different sites by following the seasonal variation of 22 trace elements. The sea urchins analyzed were taken in 2017 from reference and more impacted sites in four Corsican areas. The results obtained shown the importance of biotic factors such as gender, reproduction and the way of life. Variations have been highlighted with lower trace element concentrations during the summer season. This is mainly due to a dilution phenomenon resulting from gametogenesis. The pollution index (TEPI) was determined and highlighted differences in contamination levels at the various sites. This work could provide additional support for other tools for the diagnosis and monitoring of coastal water quality. It provides useful new data to enable managers to act at the source and reduce degradation in order to improve the ecological quality of marine waters.

Ultrastructure of mature spermatozoon of Anisocoelium capitellatum is described with transmission electron microscopy. The description gave evidence of some characteristics of this digenean. The male gamete presents features allowing the distinction between A. capitellatum and other digenetic trematodes. It is characterized by original anterior and posterior extremities. The peripheral doublets appear prior to the central cores in the anterior extremity of axoneme. In the distal part of the spermatozoon, these ultrastructural features are also the first elements disappearing in the axoneme 1 and the last remaining in the axoneme 2. Another important peculiarity of the spermatozoon is the presence of three mitochondria.