Spermatozoa morphology changes during reproduction and first observation of acrosomal contact in two dioecious species of Macrobiotidae (Tardigrada: Eutardigrada)

Sugiura, Kenta; Matsumoto, Midori

doi:10.1017/s0967199420000490

Cited by 7 publications

(14 citation statements)

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“…than in M. shonaicus, suggesting that the longer heads and tails of Paramacrobiotus sp. spermatozoa enhanced their movement [14]. It has been con rmed that the morphology and motility of spermatozoa work in cooperation during swimming [28].…”

Section: Discussionmentioning

confidence: 96%

“…Generally, the shapes of gametes should have some functional signi cance for e cient and certain reproduction. A previous study hinted at the existence of gamete morphological interference at the phase of fertilization in some species [14]. In addition, the exible and extraordinarily long acrosome has the potential to facilitate aggregation on the egg surface.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, observations of mating behaviours have revealed that the spermatozoa of the two species are rst ejaculated into the environment, after which they swim to the mating female and are stored in her spermatheca; then, oviposition occurs [13,15]. The morphologies of the spermatozoa have been well reported not only in these two species but also in other species belonging to the same family, Macrobiotidae [10,14,16,17,18,19,20]. Reports have demonstrated that the spermatozoa have a tail, an in ated or rod-shaped midpiece, a coiled nucleus and an acrosome.…”

Section: Introductionmentioning

confidence: 99%

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Morphological differences in tardigrade spermatozoa induce variation in gamete motility

Sugiura¹,

Shiba²,

Inaba³

et al. 2022

BMC Zool

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Background Fertilization is an event at the beginning of ontogeny. Successful fertilization depends on strategies for uniting female and male gametes that developed throughout evolutionary history. In some species of tardigrades, investigations of reproduction have revealed that released spermatozoa swim in the water to reach a female, after which the gametes are stored in her body. The morphology of the spermatozoa includes a coiled nucleus and a species-specific-length acrosome. Although the mating behaviour and morphology of tardigrades have been reported, the motility of male gametes remains unknown. Here, using a high-speed camera, we recorded the spermatozoon motilities of two tardigrades, Paramacrobiotus sp. and Macrobiotus shonaicus, which have longer and shorter spermatozoa, respectively. Results The movement of spermatozoa was faster in Paramacrobiotus sp. than in M. shonaicus, but the beat frequencies of the tails were equal, suggesting that the long tail improved acceleration. In both species, the head part consisting of a coiled nucleus and an acrosome did not swing, in contrast to the tail. The head part of Paramacrobiotus sp. spermatozoa swung harder during turning; in contrast, the tail of M. shonaicus moved more widely than the head. Finally, after mating, the spermatozoa that reached the female aggregated around the cloaca while waiting to enter her body in both tested species. Conclusions This study provides results for the first observations and analyses of individual spermatozoon motility in tardigrades. A comparison of the spermatozoon movements of the two tardigrades suggested that the motilities of the male gametes were affected by morphological differences, where the longer spermatozoa swam faster and the shorter ones showed more stable swimming. Swimming was mainly induced by tail movement, but the long head of Paramacrobiotus sp. spermatozoa might be especially important for turning. In addition, observations of mated female cloacae suggested that the head parts of the spermatozoa were required for aggregation around the cloaca of a mated female.

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Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Morphological differences in tardigrade spermatozoa induce variation in gamete motility

Sugiura¹,

Shiba²,

Inaba³

et al. 2022

BMC Zool

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“…There are currently detailed descriptions of sexual interaction for four gonochoristic species, representing two eutardigrade families (reviewed in Sugiura & Matsumoto, 2021c ). These studies all point to a key role of semiochemicals in male and/or ejaculate attraction, and of female behavior in ejaculate intake (Bartel & Hohberg, 2020 ; Bingemer et al, 2016 ; Sugiura et al, 2019 ; Sugiura & Matsumoto, 2021a , 2021b ).…”

Section: Introductionmentioning

confidence: 99%

First insights into female sperm storage duration in tardigrades

Vecchi

Chartrain

Puro

et al. 2022

Ecology and Evolution

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Female sperm storage is ubiquitous in the animal kingdom and it has been shown to be linked to several evolutionary processes, from postcopulatory sexual selection to dispersal. Here we report, for the first time, long‐term sperm storage in females of the tardigrade Macrobiotus polonicus . Females, isolated after a short contact with a male, were able to use the stored sperm for up to 5 weeks (mean of 2 weeks), which translates to a considerable proportion of female post‐mating longevity under controlled laboratory conditions (60% on average). Our study provides the first insights into the duration of sperm storage, an underexplored feature of the reproductive biology of tardigrades. Additionally, we discuss important considerations for reproductive studies on these non‐model animals.

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Section: Introductionmentioning

confidence: 99%

Morphological Differences In Tardigrade Spermatozoa Induce Variation In Gamete Motility

Sugiura¹,

Shiba²,

Inaba³

et al. 2021

Preprint

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BackgroundFertilization is an event at the beginning of ontogeny. Successful fertilization depends on strategies for uniting female and male gametes that developed throughout evolutionary history. In tardigrades, investigations of reproduction have revealed that released spermatozoa swim in the water to reach a female, after which the gametes are stored in her body. The morphology of the spermatozoa includes a coiled nucleus and a species-specific-length acrosome. Although the mating behaviour and morphology of tardigrades have been reported, the motility of male gametes remains unknown. Here, using a high-speed camera, we recorded the spermatozoon motilities of two tardigrades, Paramacrobiotus sp. and Macrobiotus shonaicus, which have longer and shorter spermatozoa, respectively.ResultsThe movement of spermatozoa was faster in Paramacrobiotus sp. than in M. shonaicus, but the beat frequencies of the tails were equal, suggesting that the long tail improved acceleration. In both species, the head part consisting of a coiled nucleus and an acrosome did not swing, in contrast to the tail. The head part of Paramacrobiotus sp. spermatozoa swung harder during turning; in contrast, the tail of M. shonaicus moved more widely than the head. Finally, after mating, the spermatozoa that reached the female aggregated around the cloaca while waiting to enter her body in both tested species.ConclusionsThis study provides results for the first observations and analyses of individual spermatozoon motility in tardigrades. A comparison of the spermatozoon movements of the two tardigrades suggested that the motilities of the male gametes were affected by morphological differences, where the longer spermatozoa swam faster and the shorter ones showed more stable swimming. Swimming was mainly induced by tail movement, but the long head of Paramacrobiotus sp. spermatozoa might be especially important for turning. In addition, observations of mated female cloacae suggested that the head parts of the spermatozoa were required for aggregation around the cloaca of a mated female.

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Spermatozoa morphology changes during reproduction and first observation of acrosomal contact in two dioecious species of Macrobiotidae (Tardigrada: Eutardigrada)

Cited by 7 publications

References 19 publications

Morphological differences in tardigrade spermatozoa induce variation in gamete motility

Morphological differences in tardigrade spermatozoa induce variation in gamete motility

First insights into female sperm storage duration in tardigrades

Morphological Differences In Tardigrade Spermatozoa Induce Variation In Gamete Motility

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