A study of the conjugate sperm of the dytiscid water beetles Dytiscus marginalis and Colymbetes fuscus

Mackie, John B.; Walker, Muriel H.

doi:10.1007/bf00221935

Cited by 34 publications

(20 citation statements)

References 13 publications

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“…assimilis spermatostyles indicates neutral glycosylated substances. Chemical analyses of Carabidae sperm bundles identified the presence of polysaccharides and proteins [27, 28], suggesting that the central rod of L . assimilis is also formed by neutral glycoproteins.…”

Section: Discussionmentioning

confidence: 99%

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Male reproductive system and spermatogenesis of Limodromus assimilis (Paykull 1790)

et al. 2017

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Based on advanced light and electron microscopy, we describe the male reproductive system and sperm development of Limodromus assimilis. The genital tract consists of pairs of uni-follicular testes, spermatic ducts with diverticula regions, seminal vesicles, accessory glands, an unpaired ejaculatory duct and an aedeagus containing an internal sac equipped with sclerotic scales. Based on their morphology, we draw conclusions about their functions. After spermatogenesis within the follicle, the spermatozoa become released from the sperm cysts. The single spermatozoa move into the diverticula of the vasa deferentia I. Here, they become attached to central rods (spermatostyles), forming secondary conjugates (spermiozeugmata). The coordinated flagella movement of the conjugates possibly improves sperm velocity. Using super-resolution microscopy, we identified highly condensed reticulate chromatin in the lancet-shaped spermatozoa heads and the mitochondrial derivates of the flagella, likely formed by genomic and mitochondrial DNA, respectively. The results show, for the first time, sperm bundle formation in a Platynini species mainly corresponding to that found in Pterostichini species.

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Section: Discussionmentioning

confidence: 99%

“…The double spermatozoa of Colymbetes fuscus (Linnaeus 1758) (Coleoptera: Dytiscidae) are connected via proteins and polysaccharides [27]. Proteins were also proven to be part of the spermatostyles and conjugation substance of Parachauliodes japonicus (McLachlan 1867) (Megaloptera: Corydalidae) and P .…”

Section: Introductionmentioning

confidence: 99%

Male reproductive system and spermatogenesis of Limodromus assimilis (Paykull 1790)

et al. 2017

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“…Other insects with sperm pairing include some species of burrowing water beetles (D.M. Higginson, unpublished data) and diving beetles (Auerbach, 1893; Ballowitz, 1895; Dallai & Afzelius, 1985; Mackie & Walker, 1974; Werner, 1983). Pairing has been reported in marine snails of the genus Turritella (Afzelius & Dallai, 1983), millipedes (Reger & Cooper, 1968), and the new world opossums (Biggers & Creed, 1962; Moore, 1996; Phillips, 1970; Selenka, 1887).…”

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confidence: 99%

Evolution of intra-ejaculate sperm interactions: do sperm cooperate?

2010

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Sperm are often considered to be individuals, in part because of their unique genetic identities produced as a result of synapsis during meiosis, and in part due to their unique ecology, being ejected away from the soma to continue their existence in a foreign environment. Selection at the level of individual sperm has been suggested to explain the evolution of two enigmatic sperm phenotypes: sperm heteromorphism, where more than one type of sperm is produced by a male, and sperm conjugation, where multiple sperm join together for motility and transport through the female reproductive tract before dissociation prior to fertilization. In sperm heteromorphic species, only one of the sperm morphs typically participates in fertilization, with the non-fertilizing "parasperm" being interpreted as reproductive altruists. Likewise, in species with sperm conjugation, high levels of sperm mortality have been suggested to be required for conjugate break-up and this has been considered evidence of kin-selected altruism. However, it is unclear if sperm possess the heritable variation in fitness (i.e. are individuals) required for the evolution of cooperation. We investigate the question of sperm individuality by focusing on how sperm morphology is determined and how sperm conjugates are formed. Concentrating on sperm conjugation, we discuss functional hypotheses for the evolutionary maintenance of this remarkable trait. Additionally, we speculate on the potential origins of sperm heteromorphism and conjugation, and explore the diversification and losses of these traits once they have arisen in a lineage. We find current evidence insufficient to support the concept of sperm control over their form or function. Thus, without additional evidence of haploid selection (i.e. sperm phenotypes that reflect their haploid genome and result in heritable differences in fitness), sperm heteromorphism and conjugation should be interpreted not as cooperation but rather as traits selected at the level of the male, much like other ejaculatory traits such as accessory gland proteins and ejaculate size.

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“…Electron microscopy studies in a variety of beetles have reported the presence of centriolar adjunct that could be masking the PCL [40–42]. Observing the internal structure of the PCL, which distinguishes it from the centriolar adjunct, requires non-standard electron microscopy techniques, such as high pressure freezing with freeze substitution.…”

Section: Discussionmentioning

confidence: 99%

Atypical centrioles are present in Tribolium sperm

Fishman

et al. 2017

Open Biol.

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Typical centrioles are made of microtubules organized in ninefold symmetry. Most animal somatic cells have two centrioles for normal cell division and function. These centrioles originate from the zygote, but because the oocyte does not provide any centrioles, it is surprising that the zygotes of many animals are thought to inherit only one centriole from the sperm. Recently, in the sperm of Drosophila melanogaster, we discovered a second centriolar structure, the proximal centriole-like structure (PCL), which functions in the zygote. Whether the sperm of other insects has a second centriolar structure is unknown. Here, we characterized spermiogenesis in the red flour beetle, Tribolium castaneum. Electron microscopy suggests that Tribolium has one microtubule-based centriole at the tip of the axoneme and a structure similar to the PCL, which lacks microtubules and lies in a cytoplasmic invagination of the nucleus. Immunostaining against the orthologue of the centriole/PCL protein, Ana1, also recognizes two centrioles near the nucleus during spermiogenesis: one that is microtubule-based at the tip of the axoneme, suggesting it is the centriole; and another that is more proximal and appears during early spermiogenesis, suggesting it is the PCL. Together, these findings suggest that Tribolium sperm has one microtubule-based centriole and one microtubule-lacking centriole.

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A study of the conjugate sperm of the dytiscid water beetles Dytiscus marginalis and Colymbetes fuscus

Cited by 34 publications

References 13 publications

Male reproductive system and spermatogenesis of Limodromus assimilis (Paykull 1790)

Male reproductive system and spermatogenesis of Limodromus assimilis (Paykull 1790)

Evolution of intra-ejaculate sperm interactions: do sperm cooperate?

Atypical centrioles are present in Tribolium sperm

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