The Drosophila melanogaster mutation, bemused, is a new allele of pumilio: Insights into understanding the role of translational regulation in the maintenance of proper neuronal excitability
Schweers, Brett Alan
Doctor of Philosophy
Maintenance of proper neuronal excitability is vital to proper nervous system function. Genes involved in regulation of neuronal excitability can be isolated with mutant screens to identify flies exhibiting behavioral abnormalities. A subset of these behavioral mutants exhibits defective motor neuron excitability, which can be monitored with electrophysiological methods. Application of this approach has allowed us to identify a P-element insertion mutant, called bemused (bem), which exhibits female sterility, sluggishness, and increased motor neuron excitability. The bem P-element is located in the large intron of the previously characterized translational repressor gene pumilio (pum). Here, by several criteria, I show that bem is a new allele of pum. First, ovary specific expression of pum partially rescues bem female sterility. Second, pum null mutations fail to complement bem female sterility, behavioral defects, and neuronal hyper-excitability. Third, heads from bem flies exhibit greatly reduced levels of Pum protein and the absence of two of the pum transcripts. I also show that two previously identified pum mutants exhibit neuronal hyper-excitability, and that over-expression of pum in the nervous system reduces neuronal excitability which is the opposite phenotype to pum loss of function. Furthermore, I report that bem hyper-excitability is suppressed by reduced gene dosage hunchback (hb) suggesting that translational repression of hb by pum may be important to the maintenance of neuronal excitability. Collectively, these findings describe a new role of pum in the regulation of neuronal excitability and may afford the opportunity to study the role of translational regulation in the maintenance of proper neuronal excitability.
Molecular biology; Neurosciences; Genetics