The First and The Second Mitotic Phases of Spermatogonial Stage in Xenopus laevis: Secondary Spermatogonia Which Have Differentiated after Completion of The First Mitotic Phase Acquire an Ability of Mitosis to Meiosis Conversion

Takamune, Kazufumi; Kawasaki, Toshihiro; Ukon, Shuji

doi:10.2108/zsj.18.577

Cited by 8 publications

(17 citation statements)

References 25 publications

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“…A, a; Takamune et al . ), it was difficult to get clear signals in these sections by in situ hybridization (data not shown). In contrast, we could observe clear signals by in situ hybridization in the sectioned specimen that had been fixed with 4% PFA (Fig.…”

Section: Resultsmentioning

confidence: 93%

“…The resulted cell cluster surrounded by the somatic Sertoli cells is called cyst (Kalt ; Takamune et al . ). Xenopus SSCs is believed to occur in the population of the largest germ cells (more than 22 μm in diameter) in the testis, which are called primary spermatogonia (PGs).…”

Section: Introductionmentioning

confidence: 97%

“…During Xenopus spermatogenesis, spermatogonium that has just initiated the differentiation into sperm undergoes mitotic divisions with a concomitant decrease in size and its progenies develop synchronously with formation of an interconnected bridge between cells. The resulted cell cluster surrounded by the somatic Sertoli cells is called cyst (Kalt 1976;Takamune et al 2001). Xenopus SSCs is believed to occur in the population of the largest germ cells (more than 22 lm in diameter) in the testis, which are called primary spermatogonia (PGs).…”

Section: Introductionmentioning

confidence: 99%

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Asymmetrical allocation ofJAK1mRNAduring spermatogonial stem cell division inXenopus laevis

et al. 2015

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During Xenopus spermatogenesis, each primary spermatogonium (PG), the largest single cell in the testis, undergoes mitotic divisions with a concomitant decrease in size to produce smaller differentiating spermatogonia. The spermatogonial stem cells (SSCs) occur in this PG population. Taking advantage of identifiable and isolatable properties of Xenopus SSCs, we examined JAK1 gene expression during the spermatogenesis because there have been reports on the important role of JAK/STAT pathway in regulating the status of SSCs in Drosophila and mouse. Surprisingly, in situ hybridization revealed the presence of JAK1 mRNA in the differentiating spermatogonia and primary spermatocytes as well as some PGs. Inhibition of JAK1 activity in the testis caused a decrease in percentage of BrdU-incorporating spermatogonia, suggesting that JAK1 was at least involved in regulation of spermatogonial proliferation. Interestingly, single cell reverse transcription-polymerase chain reaction (RT-PCR) clearly showed two different types of SSCs: SSCs with JAK1 mRNA (JAK1 + ) or without JAK1 mRNA (JAK1 À ). Since JAK1 À SSC level was increased by induction of testis regeneration, self-renewing SSCs were thought to be JAK1À . In addition, we found barrel-shaped PGs, in which JAK1 mRNA was localized asymmetrically to one half of the cell. The stainability with propidium iodide and morphology of two nuclei in the barrelshaped PG were similar to those of PG nucleus. Based on the above observations, we propose the hypothesis that JAK1 + SSC is preparing for production of PGs destined to differentiate (destined PGs) and the accumulated JAK1 mRNA in the SSC is distributed exclusively into the destined PGs through mitotic division.

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Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Asymmetrical allocation ofJAK1mRNAduring spermatogonial stem cell division inXenopus laevis

et al. 2015

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“…The presence of a large amount of Xtr may be disadvantageous for the early‐ and late‐secondary spermatogonia. Hitherto, we have identified the developmental stages of Xenopus spermatogenic cells by their morphology (Kalt 1976; Takamune et al . 1995, 2001).…”

Section: Discussionmentioning

confidence: 99%

Involvement of Xtr (Xenopus tudor repeat) in microtubule assembly around nucleus and karyokinesis during cleavage in Xenopus laevis

Hiyoshi¹,

Nakajo²,

Abe³

et al. 2005

Dev Growth Differ

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We have previously shown that the transcriptional product of the novel gene, Xenopus tudor repeat (Xtr), occurred exclusively in germline cells and early embryonic cells and that the putative Xtr contained plural tudor domains which are thought to play a role in the protein-protein interactions. To understand the role of Xtr, we produced an antibody against a polypeptide containing Xtr tudor domains as an antigen and investigated the distribution and the function of the Xtr. Immunoprecipitation/Western blot and immunohistochemical analyses indicated a similar occurrence of the Xtr to the mRNA except for a slightly different profile of its amount during spermatogenesis. In spite of a large amount of Xtr mRNA at late-secondary spermatogonial stage, the amount of Xtr was kept at a low level until this stage and increased after entering into the meiotic phase. Depletion of the Xtr function in the activated eggs by injection of the anti-Xtr antibody caused the inhibition both of microtubule assembly around nucleus and of karyokinesis progression after prophase, but not of the oscillation of H1 kinase activity. These results suggest that the karyokinesis of at least early embryonic cells are regulated by unique mechanisms in which the Xtr is involved.

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“…In Xenopus spermatogenesis, spermatogonium that has just started to differentiate into sperm (early secondary spermatogonium) undergoes mitotic divisions concomitant with a decrease in its size. Its progeny develop synchronously and form a cell cluster, a spermatocyst, surrounded by Sertoli cells (Kalt 1976; Takamune et al . 1995, 2001).…”

Section: Introductionmentioning

confidence: 99%

Functional demonstration of the ability of a primary spermatogonium as a stem cell by tracing a single cell destiny in Xenopus laevis

Kawasaki¹,

Imura

Nakada

et al. 2006

Dev Growth Differ

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In Xenopus, although primary spermatogonium (PG), the largest cell in the testis, is believed to be spermatogonial stem cell by histological observations, functional evidence has never been obtained. In the present study, we first indicated that culture of juvenile testis in a medium supplemented with follicle stimulating hormone resulted in no proliferation of PG. In this culture system, early secondary spermatogonia could undergo mitotic divisions with a concomitant decrease in their size, so that they became distinguishable in size from PG. Because the subcutaneous environment of juveniles permitted aggregates of the dissociated testicular cells to reconstruct the normal testis structure, we next inserted a genetically marked PG isolated from cultured testes into the aggregate and transplanted it subcutaneously. In this system, 73.9% of the aggregates contained a marked PG. When we observed the aggregates 12 weeks after transplantation, most aggregates (70.0%) contained marked PG that had self-renewed. Among these, fully growing aggregates contained many spermatogenic cells at the later developmental stage. These results suggested that isolated PG from the cultured testes had the ability as stem cells, and that purification of the spermatogenic stem cells became reliable in Xenopus.

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The First and The Second Mitotic Phases of Spermatogonial Stage in Xenopus laevis: Secondary Spermatogonia Which Have Differentiated after Completion of The First Mitotic Phase Acquire an Ability of Mitosis to Meiosis Conversion

Cited by 8 publications

References 25 publications

Asymmetrical allocation ofJAK1mRNAduring spermatogonial stem cell division inXenopus laevis

Asymmetrical allocation ofJAK1mRNAduring spermatogonial stem cell division inXenopus laevis

Involvement of Xtr (Xenopus tudor repeat) in microtubule assembly around nucleus and karyokinesis during cleavage in Xenopus laevis

Functional demonstration of the ability of a primary spermatogonium as a stem cell by tracing a single cell destiny in Xenopus laevis

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