PubMed Health⌕ Search

Biomedical subjects

F Rob Jackson

Publications and source records attributed to F Rob Jackson.

5 recordsLinked to original sources
PubMed2003

A role for CK2 in the Drosophila circadian oscillator.

The posttranslational modification of clock proteins is critical for the function of circadian oscillators. By genetic analysis of a Drosophila melanogaster circadian clock mutant known as Andante, which has abnormally long circadian periods, we show that casein kinase 2 (CK2) has a role in determining period length. Andante is a mutation of the gene encoding the beta subunit of CK2 and is predicted to perturb CK2beta subunit dimerization. It is associated with reduced beta subunit levels, indicative of a defect in alpha:beta association and production of the tetrameric alpha2:beta2 holoenzyme. Consistent with a direct action on the clock mechanism, we show that CK2beta is localized within clock neurons and that the clock proteins Period (Per) and Timeless (Tim) accumulate to abnormally high levels in the Andante mutant. Furthermore, the nuclear translocation of Per and Tim is delayed in Andante, and this defect accounts for the long-period phenotype of the mutant. These results suggest a function for CK2-dependent phosphorylation in the molecular oscillator.

Active Transport, Cell Nucleus↗
PubMed2003

Targeted ablation of CCAP neuropeptide-containing neurons of Drosophila causes specific defects in execution and circadian timing of ecdysis behavior.

Insect growth and metamorphosis is punctuated by molts, during which a new cuticle is produced. Every molt culminates in ecdysis, the shedding of the remains of the old cuticle. Both the timing of ecdysis relative to the molt and the actual execution of this vital insect behavior are under peptidergic neuronal control. Based on studies in the moth, Manduca sexta, it has been postulated that the neuropeptide Crustacean cardioactive peptide (CCAP) plays a key role in the initiation of the ecdysis motor program. We have used Drosophila bearing targeted ablations of CCAP neurons (CCAP KO animals) to investigate the role of CCAP in the execution and circadian regulation of ecdysis. CCAP KO animals showed specific defects at ecdysis, yet the severity and nature of the defects varied at different developmental stages. The majority of CCAP KO animals died at the pupal stage from the failure of pupal ecdysis, whereas larval ecdysis and adult eclosion behaviors showed only subtle defects. Interestingly, the most severe failure seen at eclosion appeared to be in a function required for abdominal inflation, which could be cardioactive in nature. Although CCAP KO populations exhibited circadian eclosion rhythms, the daily distribution of eclosion events (i.e., gating) was abnormal. Effects on the execution of ecdysis and its circadian regulation indicate that CCAP is a key regulator of the behavior. Nevertheless, an unexpected finding of this work is that the primary functions of CCAP as well as its importance in the control of ecdysis behaviors may change during the postembryonic development of Drosophila.

Amino Acid Sequence↗
PubMed2002

Drosophila fragile X protein, DFXR, regulates neuronal morphology and function in the brain.

Mental retardation is a pervasive societal problem, 25 times more common than blindness for example. Fragile X syndrome, the most common form of inherited mental retardation, is caused by mutations in the FMR1 gene. Fragile X patients display neurite morphology defects in the brain, suggesting that this may be the basis of their mental retardation. Drosophila contains a single homolog of FMR1, dfxr (also called dfmr1). We analyzed the role of dfxr in neurite development in three distinct neuronal classes. We find that DFXR is required for normal neurite extension, guidance, and branching. dfxr mutants also display strong eclosion failure and circadian rhythm defects. Interestingly, distinct neuronal cell types show different phenotypes, suggesting that dfxr differentially regulates diverse targets in the brain.

Amino Acid Sequence↗