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Dynamics of endoreplication during Drosophila posterior scutellar macrochaete development.

Kawamori A, Shimaji K, Yamaguchi M - PLoS ONE (2012)

Bottom Line: We also found that the timing of endoreplication differs, depending on the type of macrochaete.Moreover, endocycling in shaft cells of both the left and right sides of pSC bristle lineages occurs in the same pattern, indicating that the process is synchronized for specific types of macrochaete.Our findings suggest that endocycling in macrochaete cell lineages can be a model for understanding mechanisms of endoreplication at the single-cell level.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto, Japan.

ABSTRACT
Endoreplication is a variant type of DNA replication, consisting only of alternating G1 and S phases. Many types of Drosophila tissues undergo endoreplication. However, the timing and the extent to which a single endocycling macrochaete undergoes temporally programmed endoreplication during development are unclear. Here, we focused on the dynamics of endoreplication during posterior scutellar (pSC) macrochaete development. Quantitative analyses of C values in shaft cells and socket cells revealed a gradual rise from 8C and 4C at 8 hours after pupal formation (APF) to 72C and 24C at 29 hours APF, respectively. The validity of the values was further confirmed by the measurement of DNA content with a confocal laser microscope. BrdU incorporation assays demonstrated that shaft cells undergo four rounds of endoreplication from 18 to 29.5 hours APF. In contrast, socket cells undergo two rounds of endoreplication during the same period. Statistical analyses showed that the theoretical C values, based on BrdU assays, nearly coincide with the actually measured C values in socket cells, but not in shaft cells after 22 hours APF. These analyses suggest that socket cells undergo two rounds of endoreplication. However, the mechanism of endoreplication in the shaft cells may change from 22 hours APF, suggesting the possibility that shaft cells undergo two or four rounds of endoreplication during the periods. We also found that the timing of endoreplication differs, depending on the type of macrochaete. Moreover, endocycling in shaft cells of both the left and right sides of pSC bristle lineages occurs in the same pattern, indicating that the process is synchronized for specific types of macrochaete. Our findings suggest that endocycling in macrochaete cell lineages can be a model for understanding mechanisms of endoreplication at the single-cell level.

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Dynamics of endoreplication in aSC shaft and socket cells from 26.5 to 29 hours APF.(A) Dynamics of BrdU incorporation in aSC shaft and socket cells from 26.5 to 29 hours APF. Wild type pupae were grown until 26.5, 27, 27.5, 28, 29, 29.5 hours APF and BrdU assays were carried out. BrdU signals were counted in shaft and socket cells of aSC bristle lineages in both the left and right sides of a thorax. The Y axis indicates the % of BrdU incorporation in shaft and socket cells in left and right sides of a thorax. n = 23, 17, 18, 17, 4, 11 or n = , 23, 21, 21, 14, 5, 10 or n = 23, 16, 18, 16, 5, 11 or n = 23, 19, 20, 14, 5, 12 corresponds to sample numbers at 26.5, 27, 27.5, 28, 29, 29.5 hours APF for left aSC shaft, right aSC shaft, left aSC socket cells or right aSC socket cells, respectively. (B) Endoreplication is synchronized in aSC shaft cells. The Y axis indicates % of pupae in which BrdU signals were simultaneously detected in aSC shaft cells of both left and right sides of a thorax.
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pone-0038714-g006: Dynamics of endoreplication in aSC shaft and socket cells from 26.5 to 29 hours APF.(A) Dynamics of BrdU incorporation in aSC shaft and socket cells from 26.5 to 29 hours APF. Wild type pupae were grown until 26.5, 27, 27.5, 28, 29, 29.5 hours APF and BrdU assays were carried out. BrdU signals were counted in shaft and socket cells of aSC bristle lineages in both the left and right sides of a thorax. The Y axis indicates the % of BrdU incorporation in shaft and socket cells in left and right sides of a thorax. n = 23, 17, 18, 17, 4, 11 or n = , 23, 21, 21, 14, 5, 10 or n = 23, 16, 18, 16, 5, 11 or n = 23, 19, 20, 14, 5, 12 corresponds to sample numbers at 26.5, 27, 27.5, 28, 29, 29.5 hours APF for left aSC shaft, right aSC shaft, left aSC socket cells or right aSC socket cells, respectively. (B) Endoreplication is synchronized in aSC shaft cells. The Y axis indicates % of pupae in which BrdU signals were simultaneously detected in aSC shaft cells of both left and right sides of a thorax.

Mentions: To examine whether endocycling is synchronized in other types of macrochaetes, we examined the timing of S phase in the left and right sides of aSC shaft and socket cells by carrying out BrdU incorporation assays at 30 minute intervals from 26.5 to 29 hours APF (Note that N.D. at 28.5 hours APF). The results showed that 90% of BrdU incorporations were observed at 29 and 29.5 hours APF in shaft cells of both the left and right side of the thorax (Fig. 6A). We also found that the timings of the endoreplication at these time points are almost the same in both left and right sides of an adult thorax (Fig. 6B). These results support the idea that endocycling in shaft cells is synchronized in specific types of macrochaetes.


Dynamics of endoreplication during Drosophila posterior scutellar macrochaete development.

Kawamori A, Shimaji K, Yamaguchi M - PLoS ONE (2012)

Dynamics of endoreplication in aSC shaft and socket cells from 26.5 to 29 hours APF.(A) Dynamics of BrdU incorporation in aSC shaft and socket cells from 26.5 to 29 hours APF. Wild type pupae were grown until 26.5, 27, 27.5, 28, 29, 29.5 hours APF and BrdU assays were carried out. BrdU signals were counted in shaft and socket cells of aSC bristle lineages in both the left and right sides of a thorax. The Y axis indicates the % of BrdU incorporation in shaft and socket cells in left and right sides of a thorax. n = 23, 17, 18, 17, 4, 11 or n = , 23, 21, 21, 14, 5, 10 or n = 23, 16, 18, 16, 5, 11 or n = 23, 19, 20, 14, 5, 12 corresponds to sample numbers at 26.5, 27, 27.5, 28, 29, 29.5 hours APF for left aSC shaft, right aSC shaft, left aSC socket cells or right aSC socket cells, respectively. (B) Endoreplication is synchronized in aSC shaft cells. The Y axis indicates % of pupae in which BrdU signals were simultaneously detected in aSC shaft cells of both left and right sides of a thorax.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368872&req=5

pone-0038714-g006: Dynamics of endoreplication in aSC shaft and socket cells from 26.5 to 29 hours APF.(A) Dynamics of BrdU incorporation in aSC shaft and socket cells from 26.5 to 29 hours APF. Wild type pupae were grown until 26.5, 27, 27.5, 28, 29, 29.5 hours APF and BrdU assays were carried out. BrdU signals were counted in shaft and socket cells of aSC bristle lineages in both the left and right sides of a thorax. The Y axis indicates the % of BrdU incorporation in shaft and socket cells in left and right sides of a thorax. n = 23, 17, 18, 17, 4, 11 or n = , 23, 21, 21, 14, 5, 10 or n = 23, 16, 18, 16, 5, 11 or n = 23, 19, 20, 14, 5, 12 corresponds to sample numbers at 26.5, 27, 27.5, 28, 29, 29.5 hours APF for left aSC shaft, right aSC shaft, left aSC socket cells or right aSC socket cells, respectively. (B) Endoreplication is synchronized in aSC shaft cells. The Y axis indicates % of pupae in which BrdU signals were simultaneously detected in aSC shaft cells of both left and right sides of a thorax.
Mentions: To examine whether endocycling is synchronized in other types of macrochaetes, we examined the timing of S phase in the left and right sides of aSC shaft and socket cells by carrying out BrdU incorporation assays at 30 minute intervals from 26.5 to 29 hours APF (Note that N.D. at 28.5 hours APF). The results showed that 90% of BrdU incorporations were observed at 29 and 29.5 hours APF in shaft cells of both the left and right side of the thorax (Fig. 6A). We also found that the timings of the endoreplication at these time points are almost the same in both left and right sides of an adult thorax (Fig. 6B). These results support the idea that endocycling in shaft cells is synchronized in specific types of macrochaetes.

Bottom Line: We also found that the timing of endoreplication differs, depending on the type of macrochaete.Moreover, endocycling in shaft cells of both the left and right sides of pSC bristle lineages occurs in the same pattern, indicating that the process is synchronized for specific types of macrochaete.Our findings suggest that endocycling in macrochaete cell lineages can be a model for understanding mechanisms of endoreplication at the single-cell level.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto, Japan.

ABSTRACT
Endoreplication is a variant type of DNA replication, consisting only of alternating G1 and S phases. Many types of Drosophila tissues undergo endoreplication. However, the timing and the extent to which a single endocycling macrochaete undergoes temporally programmed endoreplication during development are unclear. Here, we focused on the dynamics of endoreplication during posterior scutellar (pSC) macrochaete development. Quantitative analyses of C values in shaft cells and socket cells revealed a gradual rise from 8C and 4C at 8 hours after pupal formation (APF) to 72C and 24C at 29 hours APF, respectively. The validity of the values was further confirmed by the measurement of DNA content with a confocal laser microscope. BrdU incorporation assays demonstrated that shaft cells undergo four rounds of endoreplication from 18 to 29.5 hours APF. In contrast, socket cells undergo two rounds of endoreplication during the same period. Statistical analyses showed that the theoretical C values, based on BrdU assays, nearly coincide with the actually measured C values in socket cells, but not in shaft cells after 22 hours APF. These analyses suggest that socket cells undergo two rounds of endoreplication. However, the mechanism of endoreplication in the shaft cells may change from 22 hours APF, suggesting the possibility that shaft cells undergo two or four rounds of endoreplication during the periods. We also found that the timing of endoreplication differs, depending on the type of macrochaete. Moreover, endocycling in shaft cells of both the left and right sides of pSC bristle lineages occurs in the same pattern, indicating that the process is synchronized for specific types of macrochaete. Our findings suggest that endocycling in macrochaete cell lineages can be a model for understanding mechanisms of endoreplication at the single-cell level.

Show MeSH
Related in: MedlinePlus