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#MBT

2 public questions tagged with this topic.

Drosophila -l

Early development before MBT in Drosophila is governed by:

During early Drosophila development before cycle 14, zygotic genome remains largely quiescent with only minor early zygotic genes transcribed. Embryo relies entirely on maternal products loaded during oogenesis by nurse cells, including mRNAs for bicoid, nanos, dorsal, gurken, and histones supporting rapid mitoses. These maternal determinants drive syncytial divisions, nuclear migrations, axis establishment and positional information. Activation of gap genes, pair-rule genes and cellularization requires maternal gradient interpretation. Therefore early patterning, cleavage and axis specification before maternal-to-zygotic transition are governed by maternal genes inherited from oocyte.

Ref: Alberts et al., Molecular Biology of the Cell, 6th ed., Chapter 22: Maternal control of early development.

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Drosophila -l

Maternal-to-zygotic transition (MBT) in Drosophila occurs at:

Mid-blastula transition in Drosophila, also called maternal-to-zygotic transition, occurs at nuclear cycle 14 when embryo switches from maternal to zygotic genetic control. Early cycles are rapid, lacking gap phases and checkpoint regulation, dependent on maternally deposited mRNAs and proteins. At cycle 14, cell cycle lengthens dramatically, G2 phase appears, DNA replication checkpoint activates due to high nuclear-to-cytoplasmic ratio. Large-scale zygotic transcription initiates, maternal transcripts degraded via smaug and miR-309. Cellularization coincides with this transition, marking shift where developmental programs become governed by zygotic genome rather than maternal products.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 9: Maternal-to-zygotic transition cycle 14.

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