Fertilization 2: Polyspermic Fertilization

Mizushima, Shusei

doi:10.1007/978-981-10-3975-1_7

Cited by 12 publications

(13 citation statements)

References 173 publications

(228 reference statements)

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“…Birds also exhibit physiological polyspermy during fertilization (Harper, 1904;Patterson, 1910;Fofanova, 1965;Nakanishi et al, 1990;Waddington et al, 1998). In the Japanese quail, 100-200 sperm successively enter the egg cytoplasm during fertilization, a number that is markedly higher than that in newt and even other avian species (Mizushima, 2017). We previously reported a unique pattern of increase in [Ca 2+ ]i in quail eggs following microinjection of 2 ng of sperm protein extract, which is equivalent to 200 sperm (SE) (Mizushima et al, 2014).…”

Section: Introductionmentioning

confidence: 97%

Inositol-1,4,5-Trisphosphate Receptor-1 and -3 and Ryanodine Receptor-3 May Increase Ooplasmic Ca<sup>2+</sup> During Quail Egg Activation

et al. 2022

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We previously reported that egg activation in Japanese quail is driven by two distinct types of intracellular Ca 2+ ([Ca 2+ ]i): transient elevations in [Ca 2+ ]i induced by phospholipase Czeta 1 (PLCZ1) and long-lasting spiral-like Ca 2+ oscillations by citrate synthase (CS) and aconitate hydratase 2 (ACO2). Although the blockade of inositol 1,4,5-trisphosphate receptors (ITPRs) before microinjections of PLCZ1, CS, and ACO2 cRNAs only prevented transient increases in [Ca 2+ ]i, a microinjection of an agonist of ryanodine receptors (RYRs) induced spiral-like Ca 2+ oscillations, indicating the involvement of both ITPRs and RYRs in these events. In this study, we investigated the isoforms of ITPRs and RYRs responsible for the expression of the two types of [Ca 2+ ]i increases. RT-PCR and western blot analyses revealed that ITPR1, ITPR3, and RYR3 were expressed in ovulated eggs. These proteins were degraded 3 h after the microinjection of PLCZ1, CS, and ACO2 cRNAs, which is the time at which egg activation was complete. However, degradation of ITPR1 and ITPR3, but not RYR3, was initiated 30 min after a single injection of PLCZ1 cRNA, corresponding to the time of the initial Ca 2+ wave termination. In contrast, RYR3 degradation was observed 3 h after the microinjection of CS and ACO2 cRNAs. These results indicate that ITPRs and RYR3 differentially mediate increases in [Ca 2+ ]i during egg activation in Japanese quail, and that downregulation of ITPRs and RYR3-mediated events terminate the initial Ca 2+ wave and spiral-like Ca 2+ oscillations, respectively.

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Section: Introductionmentioning

confidence: 97%

Inositol-1,4,5-Trisphosphate Receptor-1 and -3 and Ryanodine Receptor-3 May Increase Ooplasmic Ca<sup>2+</sup> During Quail Egg Activation

et al. 2022

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“…In birds, successful fertilization requires multiple sperms to penetrate the inner PVL of the ovum and a low number of sperm on the PVL is associated with low fertilization success (Birkhead & Fletcher, ; Mizushima, ). Thus, our result indicates that F1 backcross mating pairs likely experience reduced fitness relative to intra‐subspecific pairs.…”

Section: Discussionmentioning

confidence: 99%

“…In birds, successful fertilization requires multiple sperms to penetrate the inner PVL of the ovum and a low number of sperm on the PVL is associated with low fertilization success (Birkhead & Fletcher, 1998;Mizushima, 2017 to intra-subspecific pairs. In future work, we would recommend that before sampling eggs to remove the PVL, they should be incubated for about a day to assess successful fertilization (following .…”

Section: Discussionmentioning

confidence: 99%

“…In birds, however, the ubiquity of polyspermic eggs and the existence of a well‐established method to examine the number of sperm that reach and penetrate the perivitelline layer (PVL) of the ovum (e.g., Hurley, Fanson, & Griffith, ) provides a unique and non‐invasive approach to the study of PMPZ barriers. Importantly, in birds, fertilization rate increases as the number of sperm incorporated into the egg is higher (Birkhead & Fletcher, ; Mizushima, ), but too many sperm increase the likelihood of early embryonic failure (Christensen, Fairchild, & Ort, ; Forstmeier & Ellegren, ). As such, either low or high numbers of sperm present on the egg PVL may be linked to reduced reproductive success.…”

Section: Introductionmentioning

confidence: 99%

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Differential sperm‐egg interactions in experimental pairings between two subspecies and their hybrids in a passerine bird

Hurley

Rowe

Griffith

2018

Ecology and Evolution

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Speciation research has largely overlooked reproductive barriers acting between copulation and the formation of the zygote (i.e., postmating, prezygotic [PMPZ] barriers), especially in internally fertilizing vertebrates. Nonetheless, it is becoming clear that PMPZ reproductive barriers can play a role in the formation and maintenance of species boundaries. We investigated sperm‐egg interactions in the recently diverged subspecies pairs of the long‐tailed finch, Poephila acuticauda acuticauda and P. a. hecki, to explore potential PMPZ barriers. Specifically, we compared the number of sperm reaching the perivitelline layer (PVL) of the ova, and hence the site of fertilization, in both intra‐ and inter‐subspecies pairings and pairings of F1 hybrid adults with one parental subspecies. Although we found no difference in PVL sperm number among intra‐ and inter‐subspecific pairs, a significantly lower number of sperm reached the site of fertilization in a backcross pairing. As low numbers of PVL sperm appear to be associated with low fertilization success in birds, our findings offer insight into the potential role of postcopulatory processes in limiting gene flow between the subspecies and may help explain the relatively narrow hybrid zone that exists in the wild in this species. Though further work is needed to gain a comprehensive understanding of the morphological, physiological, and molecular mechanisms underlying our results, our study supports the role of PMPZ reproductive barriers in avian speciation, even in recently diverged taxa, that may not yet be fully genetically incompatible.

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“…Polyspermy induces the formation of multipolar spindle assemblies that disrupt mitotic division, as well as the inheritance of an unviable number of chromosomes (Bianchi & Wright, ; Snook, Hosken, & Karr, ). While a few physiologically polyspermic species exist, including various reptiles and birds (Iwao, ; Mizushima, ), preventing polyspermy is generally necessary to ensure proper embryonic development. Accordingly, eggs have various mechanisms to prevent the entry of more than one sperm; the two most common are referred to as the fast and slow blocks (Jaffe & Gould, ; Wong & Wessel, ).…”

Section: Introductionmentioning

confidence: 99%

Ion channels and signaling pathways used in the fast polyspermy block

Wozniak

Carlson

2019

Molecular Reproduction Devel

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Fertilization of an egg by multiple sperms, polyspermy, is lethal to most sexually reproducing species. To combat the entry of additional sperm into already fertilized eggs, organisms have developed various polyspermy blocks. One such barrier, the fast polyspermy block, uses a fertilization‐activated depolarization of the egg membrane to electrically inhibit supernumerary sperm from entering the egg. The fast block is commonly used by eggs of oviparous animals with external fertilization. In this review, we discuss the history of the fast block discovery, as well as general features shared by all organisms that use this polyspermy block. Given the diversity of habitats of external fertilizers, the fine details of the fast block‐signaling pathways differ drastically between species, including the identity of the depolarizing ions. We highlight the known molecular mediators of these signaling pathways in amphibians and echinoderms, with a fine focus on ion channels that signal these fertilization‐evoked depolarizations. We also discuss the investigation for a fast polyspermy block in mammals and teleost fish, and we outline potential fast block triggers. Since the first electrical recordings made on eggs in the 1950s, the fields of developmental biology and electrophysiology have substantially matured, and yet we are only now beginning to discern the intricate molecular mechanisms regulating the fast block to polyspermy.

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Fertilization 2: Polyspermic Fertilization

Cited by 12 publications

References 173 publications

Inositol-1,4,5-Trisphosphate Receptor-1 and -3 and Ryanodine Receptor-3 May Increase Ooplasmic Ca<sup>2+</sup> During Quail Egg Activation

Inositol-1,4,5-Trisphosphate Receptor-1 and -3 and Ryanodine Receptor-3 May Increase Ooplasmic Ca<sup>2+</sup> During Quail Egg Activation

Differential sperm‐egg interactions in experimental pairings between two subspecies and their hybrids in a passerine bird

Ion channels and signaling pathways used in the fast polyspermy block

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