Natural variation in the maternal and zygotic mRNA complements of the early embryo in Drosophila melanogaster.

Background: Maternal gene products supplied to the egg during oogenesis drive the earliest events of development in all metazoans. After the initial stages of embryogenesis, maternal transcripts are degraded as zygotic transcription is activated; this is known as the maternal to zygotic transition (MZT). Recently, it has been shown that the expression of maternal and zygotic transcripts have evolved in the Drosophila genus over the course of 50 million years.

A negative-feedback loop maintains optimal chemokine concentrations for directional cell migration.

Chemoattractant gradients frequently guide migrating cells. To achieve the most directional signal, such gradients should be maintained with concentrations around the dissociation constant (K) of the chemoreceptor. Whether this actually occurs in animals is unknown.

Effect of Larval Nutrition on Maternal mRNA Contribution to the Egg.

Embryonic development begins under the control of maternal gene products, mRNAs and proteins that the mother deposits into the egg; the zygotic genome is activated some time later. Maternal control of early development is conserved across metazoans. Gene products contributed by mothers are critical to many early developmental processes, and set up trajectories for the rest of development.