Comparative study of sperm ultrastructure of Donax hanleyanus and Donax gemmula (Bivalvia: Donacidae)

Abstract

Introíni, G.O., Passos, F.D. and Recco-Pimentel, S.M. 2013. Comparative study of sperm ultrastructure of Donax hanleyanus and Donax gemmula (Bivalvia: Donacidae). -Acta Zoologica (Stockholm) 94: 261-266.The ultrastructure of bivalve spermatozoa can be species-specific and often provides important taxonomic traits for systematic reviews and phylogenetic reconstructions. Young individuals of the Donacidae species Donax hanleyanus are often identified as samples of Donax gemmula. Hence, the spermatozoa ultrastructure of both species was described in the present work, aiming to identify characters that could be useful for further taxonomic and phylogenetic analyses. D. hanleyanus and D. gemmula spermatozoa were different especially in relation to acrosomal characteristics and chromatin condensation. The spermatozoon produced by D. hanleyanus had a nucleus (exhibiting granular chromatin with a rope-like appearance) capped by a long and conical acrosomal vesicle, which extended itself outward beyond the anterior nuclear fossa. Otherwise, the nucleus of the sperm cell of D. gemmula showed well-compacted chromatin, and its acrosome, which was partially inserted into the anterior nuclear fossa, had a bubble-like tip. In conclusion, the conspicuous ultra-structural differences found between the spermatozoan morphologies were helpful for the discrimination of the species. In conclusion, our results suggest that analyses of sperm ultrastructure of the bivalves in the family Donacidae can be valuable to investigate their taxonomic relatedness. The present results also contribute to assess the monophyletic status of the family.

Ultrastructural aspects of spermatogenesis in Calyptogena pacifica Dall 1891 (Vesicomyidae; Bivalvia)

“…soyoae ) degree of chromatin condensation. We have extrapolated the conclusion by Introíni et al (2013) onto pleocardiins species. However, the question of how widely this phenomenon occurs in the subfamily Pleocardiinae or the family Vesicomyidae is still to be clarified after studying a wider range of species.…”

“…According to this statement, such division is possible in the Pleocardiinae whose species have a medium (C. pacifica) or high (P. soyoae) degree of chromatin condensation. We have extrapolated the conclusion by Introíni et al (2013) onto pleocardiins species.…”

“…Besides, the incomplete condensation of chromatin observed in spermatozoa of C. pacifica in the present study, incomplete condensation can also be found in the illustration for H. pictus spermatozoa already published by Healy and coauthors (see figure 1b in Healy et al, 2008). Introíni, Passos, and Recco-Pimentel (2013), after analyzing their own and literature data as regards the level of chromatin condensation in spermatozoa of Donax species (Bivalvia: Cardiida), came to a conclusion that there are two degrees of chromatin condensation: medium and high. The authors suggest that the medium degree of chromatin condensation is indicative of keeping at maturity the characteristics of an immature stage such as, in particular, development of neotenous spermatozoa.…”

“…The midpiece of spermatozoa in C. pacifica contains four or rarely five mitochondria. The varying number of mitochondria is a frequently occurring phenomenon in bivalves (e.g., Gladyshev & Drozdov, 2002;Healy, 1996;Introíni et al, 2013;Keys & Healy, 1999) and in Venerida species (supplementary online material, Table S1). Four or five mitochondria were found in Coecella chinensis (Kim & Lee, 2019), Pitar rudis (Erkan & Sousa, 2002), Paphia philippiana (as P. exarata) (Chen et al, 2006), Arctica islandica, and N. sublaevigatum (Healy et al, 2020).…”

Conformação gonadal, caracterização histoquímica e ultraestrutural da gônada masculina e espermatozoides em espécies de águas-vivas (Cubozoa e Scyphozoa, Medusozoa, Cnidaria)

“…A espermiotaxonomia vem sendo utilizada como critério de suporte para inferências filogenéticas por diversos autores em vários grupos dentro de Metazoa (Franzén 1956) como Trematoda -Platyhelminthes (Jamieson and Daddow 1982), Polychaeta e Oligochaeta -Annelida (Jamieson 1983;Rota and Lupetti 1997), Decapoda -Crustacea (Jamieson 1994;Guinot et al 1997;Benetti et al 2008;Buranelli and Mantelatto 2012) e Gastropoda e Bivalvia -Mollusca (Introíni et al 2013;Giménez 2013). Em Cnidaria trabalhos como os de Miller (1983) No nível de microscopia de luz pode-se observar a morfologia geral do espermatozoide de Cnidaria é composto por cabeça redonda-ovalada, cônica ou alongada, peça intermediária visível com um flagelo ancorado à parte posterior (Franzén 1956;Harrison and Jamieson 1988).…”