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Asymmetrical allocation of JAK 1 mRNA during spermatogonial stem cell division in Xenopus laevis
Author(s) -
Hyakutake Keiichiro,
Kawasaki Toshihiro,
Zhang JiDong,
Kubota Hiroshi,
Abe SinIchi,
Takamune Kazufumi
Publication year - 2015
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/dgd.12219
Subject(s) - xenopus , biology , spermatogenesis , population , messenger rna , microbiology and biotechnology , gene , endocrinology , genetics , demography , sociology
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 ( SSC s) occur in this PG population. Taking advantage of identifiable and isolatable properties of Xenopus SSC s, we examined JAK 1 gene expression during the spermatogenesis because there have been reports on the important role of JAK / STAT pathway in regulating the status of SSC s in Drosophila and mouse. Surprisingly, in situ hybridization revealed the presence of JAK 1 mRNA in the differentiating spermatogonia and primary spermatocytes as well as some PG s. Inhibition of JAK 1 activity in the testis caused a decrease in percentage of BrdU‐incorporating spermatogonia, suggesting that JAK 1 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 SSC s: SSC s with JAK 1 mRNA ( JAK 1 + ) or without JAK 1 mRNA ( JAK 1 − ). Since JAK 1 − SSC level was increased by induction of testis regeneration, self‐renewing SSC s were thought to be JAK 1 − . In addition, we found barrel‐shaped PG s, in which JAK 1 mRNA was localized asymmetrically to one half of the cell. The stainability with propidium iodide and morphology of two nuclei in the barrel‐shaped PG were similar to those of PG nucleus. Based on the above observations, we propose the hypothesis that JAK 1 + SSC is preparing for production of PG s destined to differentiate (destined PG s) and the accumulated JAK 1 mRNA in the SSC is distributed exclusively into the destined PG s through mitotic division.