Contribution of cryptochromes and photolyases for insect life under sunlight.

The cryptochrome/photolyase (CRY/PL) family is essential for life under sunlight because photolyases repair UV-damaged DNA and cryptochromes are normally part of the circadian clock that controls the activity-sleep cycle within the 24-h day. In this study, we aim to understand how the lineage and habitat of an insect affects its CRY/PL composition. To this end, we searched the large number of annotated protein sequences of 340 insect species already available in databases for CRY/PLs.

The Gain and Loss of Cryptochrome/Photolyase Family Members during Evolution.

The cryptochrome/photolyase (CRY/PL) family represents an ancient group of proteins fulfilling two fundamental functions. While photolyases repair UV-induced DNA damages, cryptochromes mainly influence the circadian clock. In this study, we took advantage of the large number of already sequenced and annotated genes available in databases and systematically searched for the protein sequences of CRY/PL family members in all taxonomic groups primarily focusing on metazoans and limiting the number of species per taxonomic order to five.

Dopamine Signaling in Wake-Promoting Clock Neurons Is Not Required for the Normal Regulation of Sleep in .

Dopamine is a wake-promoting neuromodulator in mammals and fruit flies. In , the network of clock neurons that drives sleep/activity cycles comprises both wake-promoting and sleep-promoting cell types. The large ventrolateral neurons (l-LNs) and small ventrolateral neurons (s-LNs) have been identified as wake-promoting neurons within the clock neuron network.

Role of Rhodopsins as Circadian Photoreceptors in the Drosophila melanogaster.

Light profoundly affects the circadian clock and the activity levels of animals. Along with the systematic changes in intensity and spectral composition, over the 24-h day, light shows considerable irregular fluctuations (noise). Using light as the Zeitgeber for the circadian clock is, therefore, a complex task and this might explain why animals utilize multiple photoreceptors to entrain their circadian clock.

A New Rhodopsin Influences Light-dependent Daily Activity Patterns of Fruit Flies.

Rhodopsin 7 ( Rh7), a new invertebrate Rhodopsin gene, was discovered in the genome of Drosophila melanogaster in 2000, but its function has remained elusive. We generated an Rh7 null mutant ( Rh7) by P element-mediated mutagenesis and found that an absence of Rh7 had significant effects on fly activity patterns during light-dark (LD) cycles: Rh7 mutants exhibited less morning activity and a longer siesta than wild-type controls. Consistent with these results, we found that Rh7 appears to be expressed in a few dorsal clock neurons that have been previously implicated in the control of the siesta.

Drosophila Rhodopsin 7 can partially replace the structural role of Rhodopsin 1, but not its physiological function.

Rhodopsin 7 (Rh7), a new invertebrate Rhodopsin gene, was discovered in the genome of Drosophila melanogaster in 2000 and thought to encode for a functional Rhodopsin protein. Indeed, Rh7 exhibits most hallmarks of the known Rhodopsins, except for the G-protein-activating QAKK motif in the third cytoplasmic loop that is absent in Rh7. Here, we show that Rh7 can partially substitute Rh1 in the outer receptor cells (R1-6) for rhabdomere maintenance, but that it cannot activate the phototransduction cascade in these cells.

Rhodopsin 7-The unusual Rhodopsin in Drosophila.

Rhodopsins are the major photopigments in the fruit fly Drosophila melanogaster. Drosophila express six well-characterized Rhodopsins (Rh1-Rh6) with distinct absorption maxima and expression pattern. In 2000, when the Drosophila genome was published, a novel Rhodopsin gene was discovered: Rhodopsin 7 (Rh7).

The MAP kinase p38 is part of Drosophila melanogaster's circadian clock.

All organisms have to adapt to acute as well as to regularly occurring changes in the environment. To deal with these major challenges organisms evolved two fundamental mechanisms: the p38 mitogen-activated protein kinase (MAPK) pathway, a major stress pathway for signaling stressful events, and circadian clocks to prepare for the daily environmental changes. Both systems respond sensitively to light.

The ion transport peptide is a new functional clock neuropeptide in the fruit fly Drosophila melanogaster.

The clock network of Drosophila melanogaster expresses various neuropeptides, but a function in clock-mediated behavioral control was so far only found for the neuropeptide pigment dispersing factor (PDF). Here, we propose a role in the control of behavioral rhythms for the ion transport peptide (ITP), which is expressed in the fifth small ventral lateral neuron, one dorsal lateral neuron, and in only a few nonclock cells in the brain. Immunocytochemical analyses revealed that ITP, like PDF, is most probably released in a rhythmic manner at projection terminals in the dorsal protocerebrum.

Drosophila auditory organ genes and genetic hearing defects.

The Drosophila auditory organ shares equivalent transduction mechanisms with vertebrate hair cells, and both are specified by atonal family genes. Using a whole-organ knockout strategy based on atonal, we have identified 274 Drosophila auditory organ genes. Only four of these genes had previously been associated with fly hearing, yet one in five of the genes that we identified has a human cognate that is implicated in hearing disorders.

The circadian clock network in the brain of different Drosophila species.

Comparative studies on cellular and molecular clock mechanisms have revealed striking similarities in the organization of the clocks among different animal groups. To gain evolutionary insight into the properties of the clock network within the Drosophila genus, we analyzed sequence identities and similarities of clock protein homologues and immunostained brains of 10 different Drosophila species using antibodies against vrille (VRI), PAR-protein domain1 (PDP1), and cryptochrome (CRY). We found that the clock network of both subgenera Sophophora and Drosophila consists of all lateral and dorsal clock neuron clusters that were previously described in Drosophila melanogaster.

Antennal hearing in insects--new findings, new questions.

Mosquitoes, certain Drosophila species, and honey bees use Johnston's organ in their antennae to detect the wing-beat sounds of conspecifics. Recent studies on these insects have provided novel insights into the intricacies of insect hearing and sound communication, with main discoveries including transduction and amplification mechanisms as known from vertebrate hearing, functional and molecular diversifications of mechanosensory cells, and complex mating duets that challenge the frequency-limits of insect antennal ears. This review discusses these recent advances and outlines potential avenues for future research.

Using Drosophila for studying fundamental processes in hearing.

Apart from detecting sounds, vertebrate ears occasionally produce sounds. These spontaneous otoacoustic emissions are the most compelling evidence for the existence of the cochlear amplifier, an active force-generating process within the cochlea that resides in the motility of the hair cells. Insects have neither a cochlea nor hair cells, yet recent studies demonstrate that an active process that is equivalent to the cochlear amplifier occurs in at least some insect ears; like hair cells, the chordotonal sensory neurons that mediate hearing in Drosophila actively generate forces that augment the minute vibrations they transduce.