BIOL 3530 Lecture 6: Chapter 4
7 Oct 2016
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Document Summary
Mosaic development depends upon localized cytoplasmic factors while regulative development depends upon cell-cell interactions. In some invertebrates, cell fate is often specified at the single cell level, not in groups of cells, and does not rely upon positional information. This process results from asymmetric cell division to distribute the cytoplasm unequally and allow determination of different cell fates. Examination of developmental processes in distantly related species allows comparison. Small nematodes that are 1 mm long and 70 um in diameter. The adult hermaphrodite (some males) undergo rapid development. The egg has a 50 um diameter which forms a polar body after fertilization, nuclear fusion occurs followed by a set pattern of cleavage. The normal pattern of cell division has been mapped. The first larval stage (l1) arises at 20 hours after fertilization. Technique: gene silencing by rna interference and micrornas. The enzyme dicer chops dsrna into 21-23 lengths which unwind into single stranded short interfering.
