Spermatozoa ultrastructure of two basal pilidiophoran nemerteans, Hubrechtella juliae and Sonnenemertes cantelli (Nemertea, Pilidiophora)

Chernyshev, A. V.; Neznanova, S. Yu.; Yurchenko, Olga V.

doi:10.1016/j.micron.2020.102853

Cited by 6 publications

(4 citation statements)

References 16 publications

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“…In summary, our study rea rms previous interpretations of the evolution of substructures in nemertean sperm cells (Stricker and Folsom 1998;Döhren et al 2010;Chernyshev et al 2020;Yurchenko et al 2021). It also highlights the potential of sperm ultrastructure as a valuable source of characters for phylogenetic analyses.…”

Section: Discussionsupporting

confidence: 92%

“…In a previous study we provided evidence that several mitochondria per sperm cell are a potential autapomorphy of the Heteronemertea, or potentially of Pilidiophora, if our interpretation of light microscopical images in Franzen (1956) was con rmed (Döhren et al 2010). This has recently been done in a paper of Chernyshev et al (2020) who studied the sperm ultrastructure in Hubrechtella juliae and a basally branching heteronemertean, the valenciid Sonnenemertes cantelli Chernyshev, Abukawa and Kajihara, 2015. Sperm cells of all pilidiophoran species studied thus far possess at least three mitochondria, the majority of them ve mitochondria (Table 2).…”

Section: Pilidiophoramentioning

confidence: 99%

“…Recent research has indicated that at least at a generic level, functional constraints do not overpower phylogenetic signals (Valchi et al, 2023). In a recent paper Chernyshev et al (2020) provided some evidence that this applies to nemertean sperm even at higher taxonomic levels. To investigate whether this holds true at higher taxonomic levels, when additional data are added, we analyzed sperm ultrastructure in 12 nemertean species and lled a gap in knowledge by presenting the rst sperm ultrastructure in a reptant polystiliferan species, Par-adrepanophorus crassus (Quatrefages, 1846).…”

Section: Introductionmentioning

confidence: 99%

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Ultrastructure and phylogenetic significance of spermatozoa in Nemertea

Bartolomaeus,

Bronkars,

Adam

et al. 2023

Preprint

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Sperm ultrastructure is frequently employed as a source for phylogenetic inference due to the ease of accessing spermatozoa. Despite being unicellular, sperm cells exhibit a relatively high number of diverse characters and character states. Spermatozoa are subject to strong sexual selection as they are finely tuned for maximizing male reproductive success. Given this strong functional constraint, one might anticipate the emergence of convergent characters in line with similar modes of reproduction. As a result, it might be expected that sperm cells do not possess substantial phylogenetic signal, with functional constraints overshadowing any evolutionary heritage. To test this assumption, we conducted a study on sperm ultrastructure in 12 nemertean species, representing closely related groups and major nemertean lineages. We analyzed these data for their phylogenetic signal within the context of the most recent nemertean phylogenies. Our findings demonstrate that, at all systematic levels, functional constraints imposed by sexual selection or the mode of reproduction do not supersede the influence of historical constraints on sperm ultrastructure.

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Section: Discussionsupporting

confidence: 92%

Section: Pilidiophoramentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ultrastructure and phylogenetic significance of spermatozoa in Nemertea

Bartolomaeus,

Bronkars,

Adam

et al. 2023

Preprint

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show abstract

“…However, the axoneme located in proximity to the nucleus in early spermatogenic cells was also described from a few molluscan species (Chen, Rao, Ke, & Xu, 2006; Erkan & Sousa, 2002; Nicotra & Zappata, 1991; Reunov et al, 1999; Yurchenko et al, 2010). This pattern of axoneme location was also reported for other marine invertebrates with euspermatozoa (Au, Reunov, & Wu, 1998, 1999; Chernyshev, Neznanova, & Yurchenko, 2020) or paraspermatozoa (Eckelbarger et al, 1989a). Unlike the above‐mentioned studies, our examination of C .…”

Section: Discussionsupporting

confidence: 80%

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

Yurchenko

Борзых

Kalachev

2020

Journal of Morphology

Self Cite

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The process of spermatogenesis and spermatozoon morphology was characterized from a deep-sea bivalve, Calyptogena pacifica (Vesicomyidae, Pliocardiinae), a member of the superfamily Glossoidea, using light and electron microscopy. Spermatogenesis in C. pacifica is generally similar to that in shallow-water bivalves but, the development of spermatogenic cells in this species has also some distinguishing features. First proacrosomal vesicles are observed in early spermatocytes I. Although, early appearance of proacrosomal vesicles is well known for bivalves, in C. pacifica, these vesicles are associated with electron-dense material, which is located outside the limiting membrane of the proacrosomal vesicles and disappears in late spermatids. Another feature of spermatogenesis in C. pacifica is the localization of the axoneme and flagellum development. Early spermatogenic cells lack typical flagellum, while in spermatogonia, spermatocytes, and early spermatids, the axoneme is observed in the cytoplasm. In late spermatids, the axoneme is located along the nucleus, and the flagellum is oriented anteriorly. During sperm maturation, the bent flagellum is transformed into the typical posteriorly oriented tail. Spermatozoa of C. pacifica are of ect-aqua sperm type with a bullet-like head of about 5.8 μm in length and 1.8 μm in width, consisting of a well-developed dome-shaped acrosomal complex, an elongated barrel-shaped nucleus filled with granular chromatin, and a midpiece with mainly four rounded mitochondria. A comparative analysis has shown a number of common traits in C. pacifica and Neotrapezium sublaevigatum.

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Ultrastructure and phylogenetic significance of spermatozoa in Nemertea

Bartolomaeus,

Bronkars,

Adam

et al. 2024

Zoomorphology

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Sperm ultrastructure is frequently employed as a source for phylogenetic inference due to the ease of accessing spermatozoa. Despite being unicellular, sperm cells exhibit a relatively high number of diverse characters and character states. Spermatozoa are subject to strong sexual selection as they are finely tuned for maximizing male reproductive success. Given this strong functional constraint, one might anticipate the emergence of convergent characters in line with similar modes of reproduction. As a result, it might be expected that sperm cells do not possess substantial phylogenetic signal, with functional constraints overshadowing any evolutionary heritage. To test this assumption, we conducted a study on sperm ultrastructure in 11 nemertean species, representing closely related groups and major nemertean lineages. We analyzed these data for their phylogenetic signal within the context of the most recent nemertean phylogenies. Our findings demonstrate that, at all systematic levels, functional constraints imposed by sexual selection, or the mode of reproduction do not supersede the influence of historical constraints on sperm ultrastructure.

show abstract

Spermatozoa ultrastructure of two basal pilidiophoran nemerteans, Hubrechtella juliae and Sonnenemertes cantelli (Nemertea, Pilidiophora)

Cited by 6 publications

References 16 publications

Ultrastructure and phylogenetic significance of spermatozoa in Nemertea

Ultrastructure and phylogenetic significance of spermatozoa in Nemertea

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

Ultrastructure and phylogenetic significance of spermatozoa in Nemertea

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