[Ingen Titel]

We compared the ultrastructure of spermatozoa from the bivalves Anomalocardia brasiliana and Tivela mactroides (Veneridae). The spermatozoa of both species were of the ectaquasperm type in which the head contains a curved nucleus with a short cone-shaped acrosome. An invagination penetrated almost the entire length of the acrosome. The midpiece contained a pair of orthogonally arranged centrioles surrounded by spherical mitochondria and the flagellum had the typical 9 + 2 structure The spermatozoa of A. brasiliana had a slightly curved nucleus while those of T. mactroides had a long, prominently curved nucleus. The mitochondria were equally distributed around die centrioles in the midpiece of A. brasiliana spermatozoa, but asymmetrically in the midpiece of T. mactroides spermatozoa. There were six mitochondria and glycogen clusters in the middle piece of the T. mactroides spermatozoon. The presence of glycogen clusters and die higher number of mitochondria, in comparison with Anomalocardia brasiliana, could extend the longevity of the Tivela mactroides spermatozoa. An increase in sperm life expectancy implies in an increase in the probability of finding eggs and accomplishing fertilization. The glycogen clusters and the higher mitochondria number possibly correspond to an adaptive advantage to the bivalves in turbulent waters.1234293302Amaral, C., Arruda, E.P., Rizzo, A.E., (2005) Manual de Identificação Dos Invertebrados Marinhos da Região Sudeste-Sul Do Brasil., 1, p. 288. , Universidade de São Paulo Press, São PauloAnderson, W.A., Personne, P., The localization of glycogen in the spermatozoa of various invertebrate and vertebrate species (1970) The Journal of Cell Biology, 44, pp. 29-51Anderson, W.A., Personne, P., Molluscan spermatozoon - Dynamic aspects of its structure and function (1976) American Zoologist, 16, pp. 293-313Arruda, E.P., Amaral, C.Z., Spatial distribution of mollusks in the intertidal zone of sheltered beaches in southeastern of Brazil (2003) Revista Brasileira de Zoologia, 20, pp. 291-300Arruda, E.P., Domaneschi, O., Amaral, C.Z., Mollusk feeding guilds on sandy beaches in São Paulo State, Brazil (2003) Marine Biology, 143, pp. 691-701Bernard, R.T.F., Hodgson, A.N., The fine structure of the sperm and spermatid differentiation in the brown mussel Perna perna (1985) South African Journal of Zoology, 20, pp. 5-9Eckelbarger, K.J., Bieler, R., Mikkelsen, P.M., Ultrastructure of sperm development and mature sperm morphology in three species of commensal bivalves (Mollusca: Galeommatoidea) (1990) Journal of Morphology, 205, pp. 63-75Erkan, M., Sousa, M., Fine structural study of the spermatogenic cycle in Pitar rudis and Chamelca gallina (Mollusca, Bivalvia, Veneridae) (2002) Tissue & Cell, 34, pp. 262-272Etchevers, S.L., Notas ecológicas y cuantificación de la población de guacuco (1976) Tivela Mactroides, 15, pp. 57-64. , (Born, 1778) (Bivalvia-Veneridae), en la ensenada de La Guardia, Isla de Margarita, Venezuela. Boletin del Instituto Oceanografico de la Universidad de OrienteFranzén, A., Comparative morphological investigations into the spermiogenesis among Mollusca (1955) Zoologische Bijdragen Uppsala, 30, pp. 399-456Franzén, A., On spermiogenesis, morphology of the spermatozoon, and biology of fertilization among invertebrates (1956) Zoologische Bijdragen Uppsala, 31, pp. 355-482Franzén, A., Sperm structure with regard to fertilization biology and phylogenetics (1977) Verhandlungen der Deutschen Zoologischen Gesellschaft, pp. 123-138Franzén, A., Ultrastructural studies of spermatozoa in three bivalve species with notes on evolution of elongated sperm nucleus in primitive spermatozoa (1983) Gamete Research, 7, pp. 199-214Garrido, O., Gallardo, C.S., Ultrastnicture of sperms in bivalve mollusks of the Mytilidae family (1996) Invertebrate Reproduction & Development, 29, pp. 95-102Gharagozlou, I.D., Pochon-Masson, J., Etude comparative infrastructurale du spermatozoide chez les palourdes de France (1971) Archives de Zoologie Experimentale et Generale, 112, pp. 805-817Guerra, R., Campos, B., Esponda, P., Analysis of the spermatozoa of four bivalves with particular reference to the acrosome and plasma membrane glycoproteins (1994) J.SUBMICROSC.CYTOL.PATHOL., 26 (4), pp. 489-495Guerra, R., Sousa, M., Torres, A., Oliveira, E., Baldaia, L., Fine structure of acrosome biogenesis and of mature sperm in the bivalve mollusks Glycymeris sp. (Pteriomorphia) and Eurhomalea rufa (Heterodonta) (2003) Helgoland Marine Research, 57, pp. 7-12Gwo, J.C., Yang, W.T., Sheu, Y.T., Cheng, H.Y., Spermotozoan morphology of four species of bivalve (Heterodonta, Veneridae) from Taiwan (2002) Tissue & Cell, 34, pp. 39-43Healy, J.M., Sperm ultrastructure in the marine bivalve families Carditidae and Crassatellidae and its bearing on unification of the Crassatelloidea with the Carditoidea (1995) Zoologica Scripta, 24, pp. 21-28Healy, J.M., Comparative spermatozoal ultrastructure and its taxonomie and phylogenetic significance in the bivalve order Veneroida (1995) Advances in Spermatozoal Phylogeny and Taxonomy., 166, pp. 155-166. , Jamieson, B.CM., J. Ausio, and J.-L. JUSTINE (eds.) Mémoires du Museum National d' Histoire NaturelleHealy, J.M., Buckland-Nicks, J.A., Jamieson, B.G.M., Spermatozoal ultrastructure of spiny oysters (Spondylidae, Bivalvia) including a comparison with other bivalves (2001) Invertebrate Reproduction & Development, 40, pp. 27-37Healy, J.M., Mikkelsen, P.M., Bieler, R., Sperm ultrastructure in Glauconome plankta and its relevance to the affinities of the Glauconomidae (Bivalvia: Heterodonta) (2006) Invertebrate Reproduction & Development, 49, pp. 29-39Hodgson, A.N., Bernard, R.T.F., Van Der Horst, G., Comparative spermatology of three species of Donax (Bivalvia) from South Africa (1990) Journal of Molluscan Studies, 56, pp. 257-265Introíni, G.O., Magalhães, C.A., Aguiar Jr., O., Quaresma, A.J.C., Lino-Neto, J., Recco-Pimentel, S.M., Spermatozoan morphology of Brachidontes dancinianus and B. solisianus (Bivalvia, Mytilidae) from the southern Brazilian coast (2004) Invertebrate Reproduction & Development, 46, pp. 149-158Intróini, G.O., Magalhães, C.A., Fortunato, H., Reccopimentel, S.M., Comparison of the spermatozoan morphology of Isognomon bicolor and Isognomon alatus (Mollusca, Bivalvia, Isognomonidae) (2009) Tissue & Cell, 41, pp. 67-74Johnson, M.J., Casse, N., Le Pennec, M., Spermatogenesis in the endosymbiont-bearing bivalve Loripes lucinalis (Veneroida: Lucinidae) (1996) Molecular Reproduction & Development, 45, pp. 476-484Komaru, A., Konishi, K., Ultrastructure of biflagellate spermatozoa in the freshwater clam, Corhicula leana (Prime) (1996) Invertebrate Reproduction & Development, 29, pp. 193-197Matos, E., Matos, P., Casal, G., Azevedo, C., Ultraestnitura do espermatozóide de Protothaca pectorina (Lamark) (Mollusca, Bivalvia) do litoral norte do Brasil (1997) Revista Brasileira de Zoologia, 14, pp. 779-783Mclachlan, A., Dugan, J.E., Defeo, O., Ansell, A.D., Hubbard, D.M., Jaramillo, E., Penchaszadeh, P.E., Beach clam fisheries (1996) Oceanography and Marine Biology: An Annual Review, 34, pp. 163-232Narchi, W., Comparative study of the functional morphology of Anomalocardia brasiliana (Gmelin, 1791) and Tivela mactroides (1972) Bulletin of Marine Science, 22, pp. 643-670. , (Born, 1778) (Bivalvia, Veneridae)Nicotra, A., Zappata, S., Ultrastructure of the mature sperm and spermiogenesis in Callista chione (Mollusca, Bivalvia) (1991) Invertebrate Reproduction & Development, 20, pp. 213-218Park, C.K., Park, J.J., Lee, J.Y., Lee, J.S., Spermatogenesis and sperm ultrastructure of the equilateral venus Gomphina veneriformis (Bivalvia: Veneridae) (2002) Korean Journal of Electron Microscopy, 32, pp. 303-310Pochon-Masson, J., Gharagozlou, I.D., Particularite morphologique de l'acrosome dans le spermatozoide de Tapes decussatus L. (Mollusque lamellibranche) (1970) Annales des Sciences Naturelles, Zoologie, 12, pp. 171-180Prieto, A.S., (1980) Contribuición A la Ecologia de Tivela Mactroides, 29, pp. 323-328. , Born, 1778: aspectos reprodutivos. Boletim do Instituto OceanográficoPrieto, A.S., (1983) Ecologia de Tivela Mactroides, 22, pp. 7-19. , Born, 1778 (Mollusca, Bivalvia) en playa Güiria (Sucre, Venezuela). Boletin del Instituto Oceanografico de Venezuela de la Universidad de OrienteReunov, A.A., Hodgson, A.N., Ultrastructure of the spermatozoa of five species of South African bivalves (Mollusca), and an examination of early spermatogenesis (1994) Journal of Morphology, 219, pp. 275-283Rouse, G.W., Jamieson, B.G.M., An ultrastructural study of the spermatozoa of the polychaetes Eurythoe complanata (Amphinomidae), Clymenella laseroni and Micromaldane laseroni (Maldanidae) with definition of sperm types in relation to reproductive biology (1987) Journal of Submicroscopic Cytology, 19, pp. 573-584Schaeffer-Novelli, Y., (1980) Análise Populacional de Anomalocardia Brasiliana, 29, pp. 351-355. , (Gmelin, 1791), na Praia do Saco da Ribeira, Ubatuba, Estado de São Paulo. Boletim do Instituto OceanográficoSoares, H.A., Schaeffer-Novelli, Y., Mandelli, J.R., (1982) Berbigão Anomalocardia Brasiliana, 9, pp. 21-38. , (Gmelin, 1791), bivalve comestível da região da Ilha do Cardoso, Estado de São Paulo, Brasil: aspectos biológicos de interesse para a pesca comercial. Boletim do Instituto de PescaSousa, M., Oliveira, E., An ultrastructural study of Crassostrea angulata (Mollusca, Bivalvia) spermatogenesis (1994) Marine Biology, 120, pp. 545-551Sousa, M., Guerra, R., Oliveira, E., Torres, A., Comparative PTA staining of molluscan spermatozoa (1998) Journal of Submicroscopic Cytology and Pathology, 30 (1), pp. 183-187Ying, X.L., Yang, W.X., Dahms, H.U., Un, Z.H., Chai Spermatozoa, X.L., And spermatogenesis in the northern quahaug Mercenaria mercenaria (Mollusca, Bivalvia) (2008) Helgoland Marine Research, 62 (4), pp. 321-32

Comparison Of The Spermatozoan Morphology Of Isognomon Bicolor And Isognomon Alatus (mollusca, Bivalvia, Isognomonidae)

In this study we used transmission and scanning electron microscopy to examine the spermatozoan structure of Isognomon bicolor and Isognomon alatus. The spermatozoa of both species were of the primitive or ect-aquasperm type. The acrosomal morphologies were essentially similar but the top of the acrosomal vesicle in I. bicolor sperm had a slightly flattened edge whereas the apex of the acrosomal vesicle of I. alatus sperm had a rounded outline. This difference suggested that acrosomal morphology could be an important character for taxonomic differentiation. In the present work, the results demonstrated that the gamete ultrastructure of the two distinct species I. alatus, from Panama, and I. bicolor, from the southeastern region of Brazil, were similar to the other studied species of the superfamily Pterioidea. © 2008 Elsevier Ltd. All rights reserved.4116774Anderson, W.A., Personne, P., The localization of glycogen in the spermatozoa of various invertebrate and vertebrate species (1970) J. Cell Biol., 44, pp. 29-51Anderson, W.A., Personne, P., The molluscan spermatozoon: dynamic aspects of its structure and function (1976) Am. Zoologist, 16, pp. 293-313Bernard, R.T.F., Hodgson, A.N., The fine structure of the sperm and spermatid differentiation in the brown mussel Perna perna (1985) South Afr. J. Zool., 20, pp. 5-9Bernard, R.T.F., Davies, B.R., Hodgson, A.N., Reproduction in a brackish water mytilid: gametogenesis and embryonic development (1988) The Veliger, 30, pp. 278-290Domaneschi, O., Martins, C.M., Isognomon bicolor (C.B. Adams) (Bivalvia, Isognomonidae): primeiro registro para o Brasil, redescrição da espécie e considerações sobre a ocorrência e distribuição de Isognomon na costa brasileira (2002) Rev. Bras. Zool., 19, pp. 611-627Erkan, M., Sousa, M., Fine structural study of the spermatogenic cycle in Pitar rudis and Chamelea gallina (Mollusca, Bivalvia, Veneridae) (2002) Tissue Cell, 34, pp. 262-272Ferreira, A.A., 2003. Estrutura, ultra-estrutura e citoquímica da espermatogênese, dos dutos e ovidutos do lagarto Tropidurus itambere durante o ciclo reprodutivo. Doctoral thesis. UNICAMP, BrazilFranzén, A., Sperm structure with regard to fertilization biology and phylogenetics (1977) Verh. Dtsch. Zool. Ges., pp. 123-138Fricker, M., Hollinshead, M., White, N., Vaux, D., Interphase nuclei of many mammalian cell types contain deep, dynamic, tubular membrane-bound invaginations of the nuclear envelope (1997) J. Cell Biol., 136, pp. 531-544Garrido, O., Gallardo, C.S., Ultrastructure of sperms in bivalve molluscs of the Mytilidae family (1996) Invert. Reprod. Dev., 29 (2), pp. 95-102Giribet, G., Wheller, W., On bivalve phylogeny: a high-level analysis of the Bivalvia (Mollusca) based on combined morphology and DNA sequence data (2002) Invert. Biol., 121, pp. 271-324Guerra, R., Campos, B., Esponda, P., Analysis of the spermatozoa of four bivalves with particular reference to the acrosome and plasma membrane glycoproteins (1994) J. Submicrosc. Cytol. Pathol., 26, pp. 489-495Gwo, J.C., Chang, H.H., Jong, K.J., Ultrastructure of the spermatozoa of the small abalone, Sulculus diversicolor supertexa (Mollusca, Gastropoda, Haliotidae) (1997) J. Submicrosc. Cytol. Pathol., 29, pp. 239-244Gwo, J.C., Yang, W.T., Sheu, Y.T., Cheng, H.Y., Spermotozoan morphology of four species of bivalve (Heterodonta, Veneridae) from Taiwan (2002) Tissue Cell, 34, pp. 39-43Healy, J.M., Spermiogenesis and spermatozoa in the relict bivalve genus Neotrigonia: relevance to trigonioid relationships, particularly Unionoidea (1989) Mar. Biol., 103, pp. 75-85Healy, J.M., Sperm ultrastructure in the marine bivalve families Carditidae and Crassatellidae and its bearing on unification of the Crassatelloidea with the Carditoidea (1995) Zool. Scripta, 24, pp. 21-28Healy, J.M., Keys, J.L., Daddow, L.Y.M., Comparative sperm ultrastructure in pteriomorphian bivalves with special reference to phylogenetic and taxonomic implications (2000) The Evolutionary Biology of the Bivalvia, 177, pp. 169-190. , Harper E.M., Taylor J.D., and Crame J.A. (Eds), Geological Society, Special Publications, LondonHealy, J.M., Buckland-Nicks, J.A., Jamieson, B.G.M., Spermatozoal ultrastructure of spiny oysters (Spondylidae, Bivalvia) including a comparison with other bivalves (2001) Invert. Reprod. Dev., 40, pp. 27-37Johnson, N., Krebs, M., Boudreau, R., Giorgi, G., Legros, M., Larabell, C., Actin-filled nuclear invaginations indicate degree of cell de-differentiation (2003) Differentiation, 71, pp. 414-424Reunov, A.A., Hodgson, A.N., Ultrastructure of the spermatozoa of five species of South African bivalves (Mollusca), and an examination of early spermatogenesis (1994) J. Morphol., 219, pp. 275-283Souza, M., Oliveira, E., An ultrastructural study of Crassostrea angulata (Mollusca, Bivalvia) spermatogenesis (1994) Mar. Biol., 120, pp. 545-551Tëmkin, I., 2004. A new system for Pteroidea (Mollusca: Bivalvia). In Molluscan Megadiversity: Sea, Land and Freshwater: World Congress of Malacology, Perth, Western Australia. 11-16 July 2004, p. 145Tëmkin, I., Morphological perspective on classification and evolution of Recent Pterioidea (2006) Zool. J. Linnean Soc., 148, pp. 253-312Thielley, M., Weppe, M., Herbaut, C., Ultrastructural study of gametogenesis in the French Polynesian black pearl oyster Pinctada margaritifera (Mollusca, Bivalvia), I - spermatogenesis (1993) J. Shellfish Res., 12, pp. 41-47Yonge, C.M., Form and habit in species of Malleus (including the "hammer oysters") with comparative observations on Isognomon isognomon (1968) Biol. Bull., 135, pp. 378-40

Sperm Ultrastructure Of Mytella (bivalvia) Populations From Distinct Habitats Along The Northern Coast Of São Paulo State, Brazil

Ultrastructural analyses of bivalve spermatozoa are relevant in studies that aim to identify taxonomic traits for the purposes of discriminating species and conducting phylogenetic studies. In the present work, spermatozoa of mussel specimens of the genus Mytella, collected from two populations living in distinct habitats, were examined by electron microscopy. The objective was to identify sperm ultrastructural taxonomic traits that could be used to differentiate Mytella species. The specimens were from populations that live in intertidal zones on the southeast coast of Brazil, either buried in muddy-sand sediment or anchored to rocky substrates. The acrosomal vesicle was conical and long, the axial rod extended from the nucleus to the acrosome, the nucleus was an oblate spheroid with a condensed chromatin, the intermediate portion contained mitochondria encircling a pair of centrioles, and there was a single flagellum. The sperm was of a primitive type. The spermatozoon ultrastructure did not distinguish the specimens buried in muddy-sand sediment from those anchored to rocky substrates. The data suggest that the specimens analyzed, despite living in distinct habitats, belong to the same species, which conchological analyses identified as M. Charruana. The presence of an axial rod in their sperm cells supports the inclusion of M. Charruana in the subfamily Mytilinae.343103111Bernard, R.T.F., Hodgson, A.N., The fine structure of the sperm and spermatid differentiation in the brown mussel Perna perna (1985) South African Journal of Zoology, 20, pp. 5-9Boudreaux, M.L., Walters, L.J., Mytella charruana (Bivalvia: Mytilidae): A new, invasive bivalve in Mosquito Lagoon, Florida (2006) Nautilus, 120, pp. 34-36Carranza, A., Defeo, O., Beck, M., Castilla, J.C., Linking fisheries management and conservation in bioengineering species: The case of South American mussels (Mytilidae) (2009) Reviews in Fish Biology and Fisheries, 19, pp. 349-366Endo, S., Silver methenamine and phosphotungstic acid staining of the acrosome of Mytilus edulis (1976) Experimental Cell Research, 100, pp. 71-78Erkan, M., Sousa, M., Fine structural study of the spermatogenic cycle in Pitar rudis and Chamelea gallina (Mollusca, Bivalvia, Veneridae) (2002) Tissue and Cell, 34, pp. 262-272Franzén, A., Ultrastructural studies of spermatozoa in three bivalve species with notes on evolution of elongated sperm nucleus in primitive spermatozoa (1983) Gamete Research, 7, pp. 199-214Garrido, O., Gallardo, C.S., Ultrastructure of sperms in bivalve molluscs of the Mytilidae family (1996) Invertebrate Reproduction and Development, 29, pp. 95-102Gorbushin, A.M., The enigma of mud snail shell growth: Asymmetrical competition or character displacement? (1996) Oikos, 77, pp. 85-92Guerra, R., Campos, B., Esponda, P., Analysis of the spermatozoa of four bivalves with particular reference to the acrosome and plasma membrane glycoproteins (1994) Journal of Submicroscopic Cytology and Pathology, 26, pp. 489-495Gwo, J.C., Yang, W.T., Sheu, Y.T., Cheng, H.Y., Spermatozoan morphology of four species of bivalves (Heterodonta, Veneridae) from Taiwan (2002) Tissue and Cell, 34, pp. 39-43Healy, J.M., Sperm ultrastructure in the marine bivalve families Carditidae and Crassatellidae and its bearing on unification of the Crassatelloidea with the Carditoidea (1995) Zoologica Scripta, 24, pp. 21-28Healy, J.M., Molluscan sperm ultrastructure: Correlation with taxonomic units within the Gastropoda, Cephalopoda and Bivalvia (1996) Origin and Evolutionary Radiation of the Mollusca, pp. 99-113. , (ed. J. Taylor), Oxford University PressHealy, J.M., Keys, J.L., Daddow, L.Y.M., Comparative sperm ultrastructure in pteriomorphian bivalves with special reference to phylogenetic and taxonomic implications (2000) The Evolutionary Biology of the Bivalvia, 177, pp. 169-190. , (Eds EM Harper, JD Taylor, JA Crame). Geological Society, London, Special PublicationsHealy, J.M., Buckland-Nicks, J.A., Jamieson, B.G.M., Spermatozoal ultrastructure of spiny oysters (Spondylidae, Bivalvia) including a comparison with other bivalves (2001) Invertebrate Reproduction and Development, 40, pp. 27-37Healy, J.M., Mikkelsen, P.M., Bieler, R., Sperm ultrastructure in Hemidonax pictus (Hemidonacidae, Bivalvia, Mollusca): Comparison with other heterodonts, especially, Cardiidae, Donacidae and Crassatelloidea (2008) Zoological Journal of the Linnean Society, 153, pp. 325-347Hodgson, A.N., Bernard, R.T.F., van der Horst, G., Comparative spermatology of three species of Donax (Bivalvia) from South Africa (1990) Journal of Molluscan Studies, 56, pp. 257-265Introíni, G.O., Magalhães, C.A., Aguiar-Jr, O., Quaresma, A.J.C., Lino-Neto, J., Recco-Pimentel, S.M., Spermatozoan morphology of Brachidontes darwinianus and Brachidontes solisianus (Bivalvia, Mytilidae) from the southern Brazilian coast (2004) Invertebrate Reproduction and Development, 46, pp. 149-158Introíni, G.O., Magalhães, C.A., Fortunato, H., Recco-Pimentel, S.M., Comparison of the spermatozoan morphology of Isognomon bicolor and Isognomon alatus (Mollusca, Bivalvia, Isognomonidae) (2009) Tissue and Cell, 41, pp. 67-74Kafanov, A.I., Drozdov, A.L., Comparative sperm morphology and phylogenetic classif ication of recent Mytiloidea (Bivalvia) (1998) Malacologia, 39, pp. 129-139Komaru, A., Konishi, K., Ultrastructure of biflagellate spermatozoa in the freshwater clam, Corbicula leana (Prime) (1996) Invertebrate Reproduction and Development, 29, pp. 193-197Oliveira, M.E.G.C., Russo, C.A.M., Lazoski, C., Vianna, P.R.F.G., Solé-Cava, A.M., Genetic variation and population structure of two species of neo-tropical mud-mussels (Mytella spp) (2005) Genetics and Molecular Research, 4, pp. 197-202Rambourg, A., Hernandez, W., Leblond, C.P., Detection of complex carbohydrates in the Golgi apparatus of rat cells (1969) Journal of Cell Biology, 40, pp. 395-414Reunov, A.A., Hodgson, A.N., Ultrastructure of the spermatozoa of five species of South African bivalves (Mollusca), and an examination of early spermatogenesis (1994) Journal of Morphology, 219, pp. 275-283Reunov, A.A., Au, D.W.T., Wu, R.S.S., Spermatogenesis of the green-lipped mussel Perna viridis with dual patterns of acrosome and tail development in spermatids (1999) Helgoland Marine Research, 53, pp. 62-69Rios, E.C., (1994) Seashells of Brazil, , Fundação Universidade do Rio Grande, Rio Grande, BrazilSousa, M., Guerra, R., Oliveira, E., Torres, A., Comparative PTA staining of molluscan spermatozoa (1998) Journal of Submicroscopic Cytology and Pathology, 30, pp. 183-187Sousa, M., Oliveira, E., An ultrastructural study of Crassostrea angulata (Mollusca, Bivalvia) spermatogenesis (1994) Marine Biology, 120, pp. 545-551Villarroel, M.E., Stuardo, J., Morfología del estomago y partes blandas en Mytella strigata (Bivalvia: Mytilidae) (1995) Malacologia, 36, pp. 1-14Wada, S.K., Collier, J.R., Dan, J.C., Studies on the acrosome. V. An egg-membrane lysin from the acrosomes of Mytilus edulis spermatozoa (1956) Experimental Cell Research, 10, pp. 168-18

Spermatozoan Morphology Of Brachidontes Darwinianus And Brachidontes Solisianus (bivalvia, Mytilidae) From The Southern Brazilian Coast

Numerous investigations have demonstrated the usefulness of sperm morphology in evaluating molluscan phylogeny. In this work we used transmission and scanning electron microscopy to study the structure of mature spermatozoa from two bivalves, Brachidontes darwinianus and Brachidontes solisianus, and compared them with those of other bivalves, particularly other mytilids. These two species have a wide geographic distribution and are particularly abundant in the intertidal zone of many rocky shores along the Brazilian coast, often in areas with strong water currents. B. darwinianus occurs from the state of Rio de Janeiro, Brazil, to Patagonia, in Argentina, whereas B. solisianus is distributed from Mexico to Uruguay. The spermatozoa of both species were of the primitive or ect-aquasperm form. In both species the spermatozoan head contained an spheroidal nucleus capped by a conical acrosome with an anterior extension. No actin was detected in the subacrosomal region. However, immunocytochemical staining identified actin throughout the nucleus of the sperm of both species. The chromatin was strongly electron-dense, homogenous and compact. The nuclei contained randomly distributed, electron-lucent regions formed by invaginations of the nuclear envelope. These invaginations were detected by E-PTA staining for glycoproteins at low pH. The mid-piece region consisted of five spherical mitochondria grouped in a ring around a pair of short cylindrical centrioles. The flagellum exhibited the typical 9+2 microtubule structure (9 double outer tubules + 2 single central tubules). These findings, together with conchological characteristics, can be used to distinguish between B. darwinianus and B. solisianus. The only marked difference in the morphology of spermatozoa from these two species was the longer anterior extension of the acrosomal vesicle in B. solisianus. This elongated acrosome may facilitate penetration of the jelly coat and cytoplasm of large oocytes and could increase the efficiency of fertilization. The resulting enhanced reproductive success could account for the wider geographic distribution of B. solisianus. © 2004 Balaban.462-3149158Berger, E.M., Population genetics of marine gastropods and bivalves (1983) The Mollusca, 6, pp. 563-596. , W.D. Russel-Hunter (ed.), Academic Press, LondonBernard, R.T.F., Hodgson, A.N., The fine structure of the sperm and spermatid differentiation in the brown mussel Perna perna (1985) South Afr. J. Zool., 20, pp. 5-9Bernard, R.T.F., Davies, B.R., Hodgson, A.N., Reproduction in a brackish-water mytilid: Gametogenesis and embryonic development (1988) The Veliger, 30, pp. 278-290Chichvarkhin, A.Y., Letter to the editor (2002) Mol. Phylogen. Evol., 22, pp. 330-332Distel, D.L., Phylogenetic relationships among Mytilidae (Bivalvia): 18S rRNA data suggest convergence in Mytilid body plans (2000) Mol. 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