THE EFFECT OF BFTZ-F1 MUTATION ON MOTOR NEURON STRUCTURE AND FUNCTION IN DROSOPHILA.
Abstract
ABSTRACT
The fushi tarazu factor 1 or FTZ-F1 gene plays a vital role in the development of Drosophila melanogaster. BFTZ-F1 is an orphan nuclear receptor that mediates genetic and developmental responses to the steroid hormone 20-hydroxyecdysone (ecdysone). These developmental responses include the eversion of the head and the extension of the legs and wings occur during metamorphosis. These morphogenetic changes occur in wild type flies as a result of the regular and rhythmic contractions of the abdominal muscles. Mutations in the BFTZ-F1 gene result in a number of developmental defects; most mutants are characterized by defects in head eversion, leg and wing extension.
In these mutants, the contractions of the abdominal muscles are insufficient to generate the internal hydrostatic pressure necessary to drive head eversion, leg extension and wing extension (Fortier et al., 2003). The abdominal muscles of Drosophila melanogaster are innervated by specific motor neurons in the central nervous system (Thor and Thomas, 2002). Therefore, it is possible that the contractions of the abdominal muscles are weakened and insufficient in BFTZ-F1 mutants, because there is a deficiency in the motor neurons. Consequently, there would be inadequate innervation of the abdominal muscles.
Earlier results have supported the hypothesis that BFTZ-F1 affects the innervation of the abdominal muscles by motor neurons. The results have shown that the structure and function of the motor neurons are compromised in BFTZ-F1 mutants. Initial changes occurred in the motor neuron structure at 6 hours after puparium formation (APF). From 6 hrs APF to approximately 12 hrs APF, the distance between the two longitudinal nerve bundles decreases in the mutants, and eventually results in a collapse of the two bundles onto each other. Alternately, the collapse of the longitudinal nerve bundles may be a result of the loss of glial cells, which support and separate the nerve bundles. Crosses are now being generated to obtain flies that will allow for the observation of the glial cells in BFTZ-F1 mutants.
Description
Keywords
Drosophila, BFTZ-F1, motor, neuron, ecdysone, glial, cells