Parasitofauna study of the brown trout, Salmo trutta (Pisces, Teleostei) from Corsica (Mediterranean island) rivers

Corsica is a Mediterranean island characterised by a great number of rivers. Salmonides are the main fishes which populate these rivers. Very appreciated by fishermen, Salmonides are represented by three species in the insular hydrographical network, among which an autochthonous species, the brown trout (Salmo trutta). In the present work, we have analysed the parasitofauna of this species. According to our knowledge, this research has never been carried out in Corsica. In a first step, we drew up an inventory of the parasites found in this freshwater fish. In a second step, we studied the differences which appeared in the composition of parasite communities of this species.

Ultrastructural study of the spermatozoon of Nicolla testiobliquum (Digenea, Opecoelidae) parasite of brown trout Salmo trutta (Pisces, Teleostei)

The present paper describes the spermatozoon of Nicolla testiobliquum (Digenea, Opecoelidae), an intestinal parasite of brown trout Salmo trutta, studied by transmission electron microscopy. The mature spermatozoon possess two axonemes of 9 + "1" pattern, two mitochondria, a nucleus, external ornamentation of the plasma membrane, spine-like bodies and cortical microtubules. A comparative study between N. testiobliquum and Nicolla wisniewskii shows mainly two different dispositions of the two mitochondria in these two species of a same genera. Moreover, the comparison of each of these spermatozoon features with others digeneans, in general, and other Opecoelidae in particular, is also presented. It appears that the organisation of the posterior part of the spermatozoon, the disposition of cortical microtubules and external ornamentation associated with spine-like bodies could be interesting elements for phylogeny.

Ultrastructural study of the spermatozoon of Pronoprymna ventricosa (Digenea, Baccigerinae), parasite of the twaite shad Alosa fallax Lacepede (Pisces, Teleostei)

In this paper, we describe the ultrastructural organisation of the spermatozoon of a Digenea Baccigerinae Pronoprymna ventricosa. This spermatozoon possesses the elements found in the others digeneans: two axonemes with 9 + "1" pattern, a mitochondrion, a nucleus, cortical microtubules and external ornamentations. However, this spermatozoon presents two particularities. The first is the presence of a single field of cortical microtubules disposed in the ventral side (mitochondrion side) of the spermatozoon. In the other digeneans, two fields of cortical microtubules are observed between the two axonemes. The second is the presence of external ornamentations not associated with cortical microtubules. These two points have, to our knowledge, never been described in another digenean. Moreover, a separation in two groups of the digenean spermatozoa is proposed in relation to the localisation of the external ornamentations. We propose to distinguish a first group exhibiting these elements in the proximal part of the spermatozoon and a second one with external ornamentations in a second part of the gamete.

SPERMIOGENESIS AND SPERMATOZOON ULTRASTRUCTURE OF NICOLLA WISNIEWSKII (DIGENEA: OPECOELIDAE), AN INTESTINAL PARASITE OF BROWN TROUT SALMO TRUTTA (PISCES: TELEOSTEI)

Spermiogenesis and ultrastructure of spermatozoon of Nicolla wisniewskii (Digenea, Opecoelidae), an intestinal parasite of Salmo trutta, were studied by electron microscopy. Spermiogenesis follows the general pattern found in the Digenea. It begins with the formation of a differentiation zone, including striated rootlets associated with 2 centrioles and an intercentriolar body. The flagella undergo a rotation of greater than 90 degrees. Then, their fusion with the median cytoplasmic process is proximodistal and asynchronous. A peculiarity was observed before the fusion of flagella, i.e., the attachment zones joined as 2 pairs by an electron-dense bridge. The mature spermatozoon is characterized by 2 axonemes, cortical microtubules, a nucleus, 2 mitochondria, external ornamentation, and spinelike bodies. At the posterior end of flagella, the spermatozoon is also characterized by the presence of a central element of the axoneme and without the 9 microtubule doublets. These results were compared with those of the other digeneans and, in particular, with other species of Opecoelidae. It appears that the number of cortical microtubules and their localization in the spermatozoon may be an interesting feature of their phylogeny.

ULTRASTRUCTURAL STUDY OF SPERMIOGENESIS AND THE SPERMATOZOON OF CREPIDOSTOMUM METOECUS (DIGENEA: ALLOCREADIIDAE), A PARASITE OF SALMO TRUTTA (PISCES: TELEOSTEI)

Spermiogenesis and the spermatozoon of Crepidostomum metoecus, an intestinal parasite of brown trout Salmo trutta, were studied by transmission electron microscopy. Spermiogenesis begins with the formation of a differentiation zone in front of 2 centrioles associated by an intercentriolar body. Each centriole is linked to a striated rootlet, and gives rise to a flagellum. The rotation of flagella is greater than 90 degrees; their fusion with the median cytoplasmic extension is proximodistal and asynchronous. The spermatozoon is formed after constriction of arched membranes. The spermatozoon possesses 2 axonemes of the 9 + "1" pattern, a nucleus, mitochondria, and glycogen. A major feature is the presence, in the anterior part, of external ornamentation and a lateral expansion associated with spinelike bodies. Another attribute is the presence of 2 mitochondria rather than just 1, as in most of the digenean spermatozoa. To our knowledge, this study is the first undertaken with a species of the Allocreadiidae.

Spermiogenesis and sperm ultrastructure of Deropristis Inflata Molin, 1859 (Digenea, Deropristidae), a parasite of Anguilla anguilla

To our knowledge, this paper describes the first ultrastructural results on spermiogenesis and the spermatozoon of a Digenea belonging to the family Deropristidae, Deropristis inflata. Spermiogenesis follows the usual pattern found in the digeneans, but a single noteworthy characteristic concerns the centriole, which presents a "prominent pear-shaped electron-dense region." Spermiogenesis in D. inflata begins with the formation of a differentiation zone. 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. inflata possesses five regions and presents all the features found in the digenean gamete. However, several characteristics allow us to distinguish the spermatozoon of D. inflata from other digenetic trematoda, namely the external ornamentations of the plasmic membrane, the anterior and posterior extremities. Furthermore, the distal part of the nucleus in front of those of the mitochondria appears such a distinctive criterion in the spermatozoon of this species. Our ultrastructural investigations produce new data on the reproduction of D. inflata, which may be useful for the understanding of the phylogenetic relationships in the Deropristidae family.

Spermiogenesis and sperm ultrastructure of Deropristis Inflata Molin, 1859 (Digenea, Deropristidae), a parasite of Anguilla anguilla

To our knowledge, this paper describes the first ultrastructural results on spermiogenesis and the spermatozoon of a Digenea belonging to the family Deropristidae, Deropristis inflata. Spermiogenesis follows the usual pattern found in the digeneans, but a single noteworthy characteristic concerns the centriole, which presents a "prominent pear-shaped electron-dense region." Spermiogenesis in D. inflata begins with the formation of a differentiation zone. 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. inflata possesses five regions and presents all the features found in the digenean gamete. However, several characteristics allow us to distinguish the spermatozoon of D. inflata from other digenetic trematoda, namely the external ornamentations of the plasmic membrane, the anterior and posterior extremities. Furthermore, the distal part of the nucleus in front of those of the mitochondria appears such a distinctive criterion in the spermatozoon of this species. Our ultrastructural investigations produce new data on the reproduction of D. inflata, which may be useful for the understanding of the phylogenetic relationships in the Deropristidae family.

Ultrastructure of spermiogenesis and the spermatozoon of Paramphistomum microbothrium [Fischoeder 1901] (Digenea: Paramphistomidae), a parasite of Bos taurus in Senegal

The ultrastructural study of spermiogenesis and the spermatozoon of Paramphistomum microbothrium gave evidence of some characteristics of this digenean. The intercentriolar body located between two striated roots and two centrioles exhibits a symmetric plane. The two external bands of this intercentriolar body are made up of a line of granules. The striated roots are about 3.7 microm long. During spermiogenesis, a flagellar rotation of 90 degrees is described. The spermatozoon is characterized in its anterior part by the existence of external ornamentations and a lateral expansion exhibiting a "spine-like body". Such a spine-like body has never been described before in a digenean. The region II of the spermatozoon is asymmetrical and also characterized by the absence of mitochondrion. The posterior end of this spermatozoon exhibits a nucleus and a few microtubules.

Ultrastructure of spermiogenesis and the spermatozoon of Paramphistomum microbothrium (Fischoeder 1901; Digenea, Paramphistomidae), a parasite of Bos taurus in Senegal

The ultrastructural study of spermiogenesis and the spermatozoon of Paramphistomum microbothrium gave evidence of some characteristics of this digenean. The intercentriolar body located between two striated roots and two centrioles exhibits a symmetric plane. The two external bands of this intercentriolar body are made up of a line of granules. The striated roots are about 3.7-microm long. During spermiogenesis, a flagellar rotation of 90 degrees is described. The spermatozoon is characterized in its anterior part by the existence of external ornamentations and a lateral expansion exhibiting a "spine-like body." Such a spine-like body has never been described before in a digenean. The region II of the spermatozoon is asymmetrical and also characterized by the absence of mitochondrion. The posterior end of this spermatozoon exhibits a nucleus and a few microtubules.

Influence of season and host age on wild boar parasites in Corsica using indicator species analysis

The indicator value (Ind Val) method which combines measures of fidelity and specificity has been used in a study on wild boar parasites in Corsica during 2001–2003. Because of its resilience to changes in abundance,IndValis a particularly effective tool for ecological bioindication. TheInd Valmethod showed how season can influence the occurrence of parasite species in the wild boar, and also identified parasites as bioindicators relative to host age. The randomization test identified five parasite species having a significant indicator value for the season (the ticks,Hyalomma aegyptiumandRhipicephalus sanguineus, the louse,Haematopinus suisand the nematodesGlobocephalus urosubulatusandAscaris suumand two indicator species of an age class (the nematodesG. urosubulatusandMetastrongylussp.). Data on species composition and infection levels would help improve the monitoring and management of parasitism in Suidae populations.

Ultrastructure of the spermatozoon of Bothriocephalus claviceps (Cestoda, Pseudophyllidea): a parasite of Anguilla anguilla (Fish, Teleostei)

The mature Bothriocephalus claviceps spermatozoon is filiform and tapered at both extremities. It contains two axonemes of unequal lengths of the 9+"1" pattern of the trepaxonemata. The anterior extremity exhibits an apical cone of an electron-dense material about 6.6 microm long by 0.2 microm wide at its base and a crest-like body making an angle of about 40 degrees with the spermatozoon axis. It is spiralized around the whole extremity of the spermatozoon. The nucleus is a cord of electron-dense material that interposes itself between the two axonemes. The cortical microtubules are of two types: hollow-centred and electron-dense centred. The cytoplasm is slightly electron dense and contains numerous electron-dense granules in regions III, IV, and V of the spermatozoon. The anterior and posterior extremities of the spermatozoon contain a single axoneme. The presence of an apical cone of the electron dense material has never, to our knowledge, been reported in the Pseudophyllidea. In addition, we show for the first time the existence of a crested body in the Bothriocephalidae.

Spermiogenesis and sperm ultrastructure of the pseudophyllidean cestode Triaenophorus nodulosus (Pallas, 1781)

Spermiogenesis and ultrastructure of the spermatozoon of the pseudophyllidean cestode Triaenophorus nodulosus (Pallas, 1781), a parasite of pike Esox lucius, has been studied by transmission electron microscopy. Spermiogenesis involves firstly the formation of a zone of differentiation with two centrioles associated with striated roots, and an intercentriolar body between them, subsequent growth of the two flagella of unequal length, and a formation of a median cytoplasmic process exhibiting patches of dense material. The nucleus penetrates into spermatid body after flagellar rotation and proximo-distal fusion has started. The mature spermatozoon of T. nodulosus is filiform and contains two axonemes of 9+"1" pattern of the Trepaxonemata, nucleus, cortical microtubules parallel to the spermatozoon axis, and electron-dense granules. The anterior extremity of the gamete contains a single centriole surrounded by numerous electron-dense tubular structures exhibiting spiral arrangement and giving rise to lateral projections, which correspond to the crested body. When the crested body disappears, the spiral pattern of electron-dense tubular structures is changed into a ring, persisting until the centriole of the second axonemes appears. This structure of the crested body of T. nodulosus is unique among the Eucestoda.

Ultrastructure of the spermatozoon of Raillietina (Raillietina) baeri (Cyclophyllidea, Davaineidae) an intestinal parasite of the multimammate rat, Mastomys huberti (Rodentia, Muridae)

The mature Raillietina (Raillietina) baeri spermatozoon exhibits an apical cone of electron-dense material about 2.5 microm long and 0.5 microm wide and two helicoidal crest-like bodies roughly 100-125 nm thick. The latter are of different lengths, spiralized and stand in an angle of about 50 degrees with the spermatozoon axis. The axoneme is of the 9 + "1" pattern and does not reach the posterior extremity of the gamete. The nucleus is an electron-dense cord coiled in a spiral around the axoneme. The cytoplasm exhibits a posterior densification and contains few small electron-dense granules in regions I, II and V of the spermatozoon. In regions III and IV, it is divided into irregular compartments by walls of electron-dense material. The cortical microtubules are spiralized and make an angle of 40-50 degrees to the spermatozoon axis. In this work, we describe, for the first time, a spermatozoon of a davaineidaean cestode parasitic of mammals. This has enabled us to show a wide apical cone, which has never been described before in a cyclophyllidean species the spermatozoon of which has two crest-like bodies.

ULTRASTRUCTURE OF SPERMIOGENESIS AND THE SPERMATOZOON OF MACRACANTHORHYNCHUS HIRUDINACEUS (PALLAS, 1781) (ACANTHOCEPHALA: ARCHIACANTHOCEPHALA), A PARASITE OF THE WILD BOAR SUS SCROFA

The present paper describes the ultrastructure of spermiogenesis and the spermatozoon of Macracanthorhynchus hirudinaceus, an acanthocephalan parasite of the wild boar Sus scrofa. At the beginning of spermatogenesis, spermatocytes exhibit synaptonemal complexes and 2 centrioles. In the spermatid, only 1 centriole remains, generating a flagellum with a 9+2 pattern. Another ultrastructural feature observed during the spermiogenesis of M. hirudinaceus is the condensation of the chromatin, forming a "honeycomb" structure in the old spermatid and a homogeneous, electron-dense structure in the spermatozoon. The mature spermatozoon of M. hirudinaceus presents a reversed anatomy, as has been described previously in other species of the Acanthocephala. The spermatozoon is divided into 2 parts: an axoneme, and a nucleocytoplasmic derivative. The spermatozoon flagellum exhibits a 9+2 or 9+0 pattern. The process of spermiogenesis and the ultrastructural organization of the spermatozoon of M. hirudinaceus are compared with available data regarding other acanthocephalan species.

Dicrocoelium hospes Looss, 1907 (Digenea, Dicrocoeliidae): spermiogenesis, mature spermatozoon and ultrastructural comparative study

This work describes the first ultrastructural results on spermiogenesis and on the mature spermatozoon of Dicrocoelium hospes (Trematoda, Digenea) collected in Bos indicus from Senegal (Africa). Examination of this species was processed by TEM. Spermiogenesis follows the general pattern found in the digenean, but reveals a particularity consisting of the appearance of glycogen granules in the late spermatids within the testes. The mature spermatozoon possesses five distinct regions and presents all features found in Digenea gametes: two axonemes, mitochondria, nucleus and parallel cortical microtubules. However, several characters allow us to distinguish D. hospes from other digenetic trematodes within the Dicrocoeliidae family. In fact, we observed several structures that are absent in the other species of Dicrocoeliidae studied until now, such as: a cytoplasmic expansion, extramembranar ornamentation, spine-like bodies and two parallel mitochondria in the mature sperm. Moreover, additional particular characteristics were observed in this species in both extremities of the spermatozoon. This work produced new data on the ultrastructure of this trematode family which may be useful for phylogenetic purposes.

Ultrastructure of the spermatozoon of the anoplocephalid cestode Gallegoides arfaai (Mobedi and Ghadirian, 1977) Tenora and Mas-Coma, 1978, an intestinal parasite of the wood mouse (Apodemus sylvaticus Linnaeus, 1758)

The present work involves an ultrastructural study of the mature spermatozoon of the anoplocephalid cestode Gallegoides arfaai (Mobedi and Ghadirian, 1977) Tenora and Mas-Coma, 1978, obtained from the small intestine of naturally infected wood mice, Apodemus sylvaticus Linnaeus, 1758 (Rodentia, Muridae). The mature spermatozoon of G. arfaai is a filiform cell, tapered at both ends and lacking mitochondria. It is characterized by the presence of a 1,000-nm-long apical cone and two 140-nm-thick crest-like bodies in its anterior extremity. The axoneme, of the 9 + '1' trepaxonematan pattern, lacks a periaxonemal sheath, and disorganization occurs at the level of the nuclear region of the sperm cell. The cortical microtubules form two to four fields according to the different regions of the male gamete. They are twisted at an angle of about 35 degrees , becoming parallel towards the posterior extremity of spermatozoon. The nucleus, spiralled around the axoneme, shows an irregular shape in both longitudinal and cross-sections. Numerous electron-dense granules were observed, which transform into an electron-dense material in the posterior extremity of the cell. Moreover, we describe for the first time the total length of the anterior region of sperm containing the helical crest-like bodies. This anterior extremity measures around 15 mum and presents two helical crest-like bodies of different lengths that describe 13-14 turns around the sperm body. Our ultrastructural results on the G. arfaai spermatozoon are compared with the ultrastructural organization of the spermatozoa of other previously studied species, with particular emphasis on the anoplocephalids.

Spermiogenesis and sperm ultrastructure of Diphterostomum brusinae (Digenea, Zoogonidae), a parasite of Diplodus annularis (Pisces, Teleostei)

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.