Drosophila duration

The very beginning of the first mitotic cell cycle of the mouse embryo seems to be controlled by the mechanisms characteristic for both meiotic and mitotic cell cycles. Active MAP kinase, its substrate p90rsk and the CSF activity itself could influence the cellular processes within the one-cell embryo. Indeed, we have observed that despite the entry into the interphase (as judged by the low activity of MPF) some proteins are actively phosphorylated as during the meiotic M phase (e.g. 35 kDa complex Howlett et al 1986, Szollosi et al 1993), the nuclei and the microtubule interphase network start to form only 1.5 hours after activation (Szollosi et al 1993). This delay in the phenomena characteristic for the interphase could be linked to the mixed meiotic/mitotic character of this early period. This delay probably allows the correct transformation of the sperm nucleus into the male pronucleus. In species like Xenopus or Drosophila the transitional period between the meiotic and the mitotic cell cycle control is probably much shorter since it is proportional to duration of the short first cell cycle of these rapidly cleaving embryos. Mammalian embryos are perhaps the most suitable to study this transition because of the exceptionally long first embryonic cell cycle. 

Kubiak I don t have any data about the differential regulation of duration of mitoses during development except for the 14th and 15th mitosis in Drosophila, where there is a difference (Foe Alberts 1983). 

Adaptation/disadaptation rates determine how phasic a response is (Moore, 1994). Some Drosophila ORNs show amuch slower rise and fall in firing frequency (de Bruyne et al., 2001) and could be considered more tonic. These different responses to onset and duration of stimuli are mimicked by diversity in their response at the end of stimulation (de Bruyne et al., 2001). Some ORNs show an... 

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