Spermatological characters of Acanthobothrium crassicolle Wedl, 1855 (Tetraphyllidea, Onchobothriidae), a parasite of the common stingray Dasyatis pastinaca

We describe the spermiogenesis process and the ultrastructural characters of the spermatozoon of Acanthobothrium crassicolle by means of transmission electron microscopy, including cytochemical analysis for glycogen. Spermiogenesis in A.crassicolle begins with the formation of the differentiation zone that contains two centrioles associated with striated rootlets and an intercentriolar body. The latter is formed by one electron-dense layer. The centrioles develop into two free flagella that first grow orthogonally to a median cytoplasmic process and then undergo flagellar rotation becoming parallel to that median cytoplasmic process. After flagellar rotation only one of the flagella completes its growth and both short and long flagella undergo proximodistal fusion with the median cytoplasmic process. In the final stages of spermiogenesis, the nucleus becomes filiform and migrates into the spermatid body. Later, the ring of arched membranes constricts and the spermatozoon is liberated from the residual cytoplasm. The ultrastructural organization of the spermatozoon of A.crassicollefollows the general pattern of spermatozoa of the other Tetraphyllidea-Onchobothriidae species, but exhibits some differences. It is filiform, tapered at both extremities and lacks mitochondrion. It contains two axonemes of unequal length showing the 9 + “1” pattern of Trepaxonemata, a nucleus, parallel cortical microtubules and electron-dense granules of glycogen. The anterior extremity of the male gamete contains a single crested body surrounding a thin and long apical cone. This type of apical cone has never been described in a tetraphyllidean spermatozoon. Another particularity is the presence of a single electron-dense microtubule at the vertex of the crested body.publishe

Ultrastructure des spermatozoïdes mûrs de trois Bucephalidae (Prosorhynchus longisaccatus, Rhipidocotyle khalili et Bucephalus margaritae) et implications phylogénétiques.

International audienceWe describe here the mature spermatozoa of three species of bucephalids, namely Bucephalus margar-itae, Rhipidocotyle khalili and Prosorhynchus longisaccatus. This study provides the first ultrastructural data on the genera Bucephalus and Rhipidocotyle and enabled us to confirm the model of the mature spermatozoon in the Bucephalinae. The spermatozoon exhibits two axonemes with the 9 + ''1'' pattern of the Trepaxonemata, one of which is very short, lateral expansion, external ornamentation of the plasma membrane located in the anterior extremity of the spermatozoon and associated with cortical microtubules, spine-like bodies, a mitochondrion, and a nucleus. The maximum number of cortical microtubules is located in the anterior part of the spermatozoon. However, more studies are needed to elucidate if spine-like bodies are present in all the Bucephalinae or not. In the Prosorhynchinae, the mature spermatozoon exhibits a similar ultrastructural pattern. Some differences are observed, particularly the ax-oneme lengths and the arrangement of the spine-like bodies. The posterior extremity of the spermatozoon in the Bucephalinae exhibits only the nucleus, but prosorhynchines have microtubules.Dans cette étude, nous décrivons les spermatozoïdes mûrs de trois espèces de bucephalidés, à savoir Bucephalus margaritae, Rhipidocotyle khalili et Prosorhynchus longisaccatus. Ces premières données ultrastructurales pour les genres Bucephalus et Rhipidocotyle nous ont permis de confirmer le modèle du spermatozoïde chez les Bucephalinae. Le spermatozoïde comprend deux axonèmes de type 9 + ‘‘1’’ des Trepaxonemata, l’un d’entre eux étant très court, une expansion latérale, une ornementation externe de la membrane plasmique située au niveau de l’extrémité antérieure du spermatozoïde et associée avec des microtubules corticaux, des corps en forme d’épines, une mitochondrie et un noyau. Le nombremaximum de microtubules corticaux est situé dans la partie antérieure du spermatozoïde. Toutefois, des études supplémentaires seraient nécessaires pour vérifier si les corps en forme d’épines sont présents chez tous les Bucephalinae. Chez les Prosorhynchinae, le spermatozoïde mûr présente une structure similaire. Quelques différences sont toutefois observées, notamment au niveau de la longueur des axonèmes et de la disposition des corps en forme d’épines. L’extrémité postérieure du spermatozoïde chez les Bucephalidae est caractérisée par la présence du noyau seul, alors que les Prosorhynchinae ont des microtubules

Sperm characters of the digenean Nephrotrema truncatum (Troglotrematidae): a kidney parasite of Crocidura russula (Soricidae) and their phylogenetic significance

Spermatological characteristics of the troglotrematid digenean Nephrotrema truncatum, a parasite of the shrew Crocidura russula, have been investigated by means of transmission electron microscopy. The ultrastructural study reveals that the mature spermatozoon of N. truncatum exhibits many ultrastructural characters previously described in most gorgoderoideans. These are two axonemes of the 9+'1' trepaxonematan pattern, four attachment zones, a lateral expansion, an external ornamentation of the plasma membrane associated with spine-like bodies and cortical microtubules, and in the posterior part of the anterior spermatozoon region, two bundles of parallel cortical microtubules with the maximum number located in the anterior part of the spermatozoon, a nucleus, two mitochondria, and granules of glycogen. The obtained results are compared with those of other digeneans, particularly the Gorgoderoidea. The sperm cells gorgoderoideans are of type IV, characterised by a 9+'1' pattern of axonemes, the presence of an external ornamentation associated with cortical microtubules and located in the posterior area of the anterior extremity, the presence of two bundles of cortical microtubules, the maximum number of cortical microtubules located in the anterior region of the spermatozoon, and the presence of generally two mitochondria. However, dicrocoeliids and troglotrematids have spermatozoa with ornamentation of the plasma membrane and lateral expansions

Collyricloides massanae (Digenea: Collyriclidae): spermatozoon ultrastructure and phylogenetic importance

The spermatological characteristics of Collyricloides massanae (Digenea: Collyriclidae), a parasite of Apodemus sylvaticus caught in France, were studied by means of transmission electron microscopy. The mature sperm of C. massanae presents two axonemes of different lengths with the 9 + ''1'' pattern of the Trepaxonemata, two bundles of parallel cortical microtubules, external ornamentation of the plasma membrane, spine-like bodies, one mitochondrion, a nucleus and granules of glycogen. An analysis of spermatological organisation emphasised some differences between the mature spermatozoon of C. massanae and those reported in the Gorgoderoidea species studied to date, specially belonging to the families Dicrocoeliidae, Paragonimidae and Troglotrematidae. The ultrastructural criteria described in C. massanae such as the morphology of both anterior and posterior spermatozoon extremities, the association ''external ornamentation + cortical microtubules'', the type 2 of external ornamentation and the spine-like bodies would allow us to bring closer the Collyriclidae to Microphalloidea. However, further ultrastructural and molecular studies are needed particularly in the unexplored taxa in order to fully resolve the phylogenetic position of the Collyriclidae

First spermatological study in the Atractotrematidae (Digenea, Haploporoidea): the case of Atractotrema sigani, intestinal parasite of Siganus lineatus

The ultrastructural organization of the mature spermatozoon of the digenean Atractotrema sigani(from Siganus lineatus off New Caledonia) was investigated by transmission electron microscopy. The male gamete of A. sigani exhibits the general morphology described in digeneans with the presence of two axonemes of different lengths showing the 9 + '1' pattern of the Trepaxonemata, a nucleus, two mitochondria, two bundles of parallel cortical microtubules, external ornamentation, spine-like bodies and granules of glycogen. However, the mature spermatozoon of A. sigani has some specific characters such as the morphology of its anterior region and the submembranous electron-dense material. Although similar structures have been reported in some digenean species, the presence of a submembranous electron-dense material describing a complete ring is reported here for the first time in the mature spermatozoon of A. sigani. In addition, sperm characteristics are compared between the Haploporoidea and their supposed close superfamilies, and possible phylogenetic implications of these findings for the Digenea are discussed

Ultrastructural study of spermiogenesis and the spermatozoon of the proteocephalidean cestode Barsonella lafoni de Chambrier et al., 2009, a parasite of the catfish Clarias gariepinus (Burchell, 1822) (Siluriformes, Clariidae)

Spermiogenesis in the proteocephalidean cestode Barsonella lafoni de Chambrier et al., 2009 shows typical characteristics of the type I spermiogenesis. These include the formation of distal cytoplasmic protrusions forming the differentiation zones, lined by cortical microtubules and containing two centrioles. An electron-dense material is present in the apical region of the differentiation zone during the early stages of spermiogenesis. Each centriole is associated to a striated rootlet, being separated by an intercentriolar body. Two free and unequal flagella originate from the centrioles and develop on the lateral sides of the differentiation zone. A median cytoplasmic process is formed between the flagella. Later these flagella rotate, become parallel to the median cytoplasmic process and finally fuse proximodistally with the latter. It is interesting to note that both flagellar growth and rotation are asynchronous. Later, the nucleus enlarges and penetrates into the spermatid body. Finally, the ring of arching membranes is strangled and the young spermatozoon is detached from the residual cytoplasm. The mature spermatozoon presents two axonemes of the 9 +"1" trepaxonematan pattern, crested body, parallel nucleus and cortical microtubules, and glycogen granules. Thus, it corresponds to the type II spermatozoon, described in almost all Proteocephalidea. The anterior extremity of the gamete is characterized by the presence of an apical cone surrounded by the lateral projections of the crested body. An arc formed by some thick and parallel cortical microtubules appears at the level of the centriole. They surround the centriole and later the first axoneme. This arc of electron-dense microtubules disorganizes when the second axoneme appears, and then two parallel rows of thin cortical microtubules are observed. The posterior extremity of the male gamete exhibits some cortical microtubules. This type of posterior extremity has never been described in proteocephalidean cestodes. The ultrastructural features of the spermatozoon/spermiogenesis of the Proteocephalidea species are analyzed and compared

A New Species of Cucullanus (Nematoda: Cucullaninae, Cucullanidae) from Mugil curema (Mugilidae) in Senegal (West Africa)

International audienceThe presence of Cucullanid nematodes was investigated in 10 individuals of Mugil bananensis, 115 Mugil cephalus, 109 Mugil curema, 89 Liza dumerili, 37 Liza falcipinnis, and 40 Liza grandisquamis, all collected from the Saloum estuary in Senegal, West Africa. Cucullanids were found only in intestines removed from M. curema and were identified using light microscopy. The results showed that 13 individuals of Mugil curema were found to be parasitized by 22 adult nematodes of a species new to science, Cucullanus djilorensis n. sp. (prevalence 11.9%, intensity 1.7). This species differs from all other species of the genus Cucullanus by a number of features including the form of the esophagus, the number and distribution of caudal papillae, the position of the excretory pore, and the length of the spicules. Cucullanus djilorensis n. sp. is the first species of the genus described from an estuarine fish in West Africa