Developmental Biology Quiz

Summary Title: Developmental Biology of Drosophila and Insects

Drosophila:

• Drosophila is highly suited to genetic experimentation due to its small size and short life cycle of 2 weeks.
• Techniques have been developed for constructing stocks and carrying out mutagenesis screens.
• Developmental biology research on Drosophila started with mutagenesis to produce mutants with interesting-looking phenotypes, then the genes were cloned and the expression patterns studied.
• Drosophila is a holometabolous insect, meaning it undergoes an abrupt and complete metamorphosis.
• Much of the adult body is formed from the imaginal discs and the abdominal histoblasts, which are present as undifferentiated buds in the larva.

Insects:

• All adult and larval insects are built up of an anteroposterior sequence of segments which fall into the three principal body regions of head, thorax, and abdomen.
• The head may consist of as many as six segments, and all of these develop a pair of legs on the ventral side.
• Drosophila follows the general insect pattern except that it does not display the procephalic head segments even in the embryo.
• During early development, the most important repeating units are the parasegments.

Embryonic Development:

• Oocytes are fertilized before the first meiotic division, and the initiation of maturation depends on a Major Sperm Protein released from nearby sperm.
• An early sign of polarization is the appearance of a smooth posterior cortical region, while the remainder of the egg cortex becomes ruffled.
• The first cleavage forms an anterior AB and posterior P1 cell, and the final P cell (P4) is the germ cell precursor.
• Maternal components are sufficient to direct development up to about 26 cells.
• The egg contains RNA-rich P-granules, which concentrate in the posterior during the cytoplasmic rearrangement period.
• The complete cell lineage of embryo, larva, and adult has been determined by direct observation.
• The “official” germ layers are ectoderm, mesoderm, and endoderm.
• The spatial disposition of the determinants is controlled by the PAR system.
• Formation of the entire pharynx is dependent on the zygotically expressed gene pha-4.
• The Wnt-like signaling affects the ratio of POP-1 and SYS-1 in the two daughters, operating many more times in C.