Sensitivity to magnetic fields is dependent on the intensity and color of light in several animal species. The light-dependent magnetoreception working model points to cryptochrome (Cry) as a protein cooperating with its co-factor flavin, which possibly becomes magnetically susceptible upon excitation by light. The type of Cry involved and what pair of magnetosensitive radicals are responsible is still elusive. Therefore, we developed a conditioning assay for the firebug Pyrrhocoris apterus, an insect species that possesses only the mammalian cryptochrome (Cry II). Here, using the engineered Cry II null mutant, we show that: (i) vertebrate-like Cry II is an essential component of the magnetoreception response, and (ii) magnetic conditioning continues even after 25 h in darkness. The light-dependent and dark-persisting magnetoreception based on Cry II may inspire new perspectives in magnetoreception and cryptochrome research.
- MeSH
- Sensation MeSH
- Insecta MeSH
- Cryptochromes * genetics MeSH
- Magnetic Fields * MeSH
- Darkness MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Nearly all organisms evolved endogenous self-sustained timekeeping mechanisms to track and anticipate cyclic changes in the environment. Circadian clocks, with a periodicity of about 24 h, allow animals to adapt to day-night cycles. Biological clocks are highly adaptive, but strong behavioral rhythms might be a disadvantage for adaptation to weakly rhythmic environments such as polar areas [1, 2]. Several high-latitude species, including Drosophila species, were found to be highly arrhythmic under constant conditions [3-6]. Furthermore, Drosophila species from subarctic regions can extend evening activity until dusk under long days. These traits depend on the clock network neurochemistry, and we previously proposed that high-latitude Drosophila species evolved specific clock adaptations to colonize polar regions [5, 7, 8]. We broadened our analysis to 3 species of the Chymomyza genus, which diverged circa 5 million years before the Drosophila radiation [9] and colonized both low and high latitudes [10, 11]. C. costata, pararufithorax, and procnemis, independently of their latitude of origin, possess the clock neuronal network of low-latitude Drosophila species, and their locomotor activity does not track dusk under long photoperiods. Nevertheless, the high-latitude C. costata becomes arrhythmic under constant darkness (DD), whereas the two low-latitude species remain rhythmic. Different mechanisms are behind the arrhythmicity in DD of C. costata and the high-latitude Drosophila ezoana, suggesting that the ability to maintain behavioral rhythms has been lost more than once during drosophilids' evolution and that it might indeed be an evolutionary adaptation for life at high latitudes.
- MeSH
- Circadian Clocks genetics physiology MeSH
- Circadian Rhythm physiology MeSH
- Drosophila physiology MeSH
- Drosophilidae genetics physiology MeSH
- Phenotype MeSH
- Photoperiod MeSH
- Adaptation, Physiological physiology MeSH
- Cryptochromes physiology MeSH
- Locomotion physiology MeSH
- Altitude MeSH
- Neurons physiology MeSH
- Motor Activity physiology MeSH
- Drosophila Proteins metabolism MeSH
- Darkness MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Circadian clocks orchestrate daily activity patterns and free running periods of locomotor activity under constant conditions. While the first often depends on temperature, the latter is temperature-compensated over a physiologically relevant range. Here, we explored the locomotor activity of the temperate housefly Musca domestica Under low temperatures, activity was centered round a major and broad afternoon peak, while high temperatures resulted in activity throughout the photophase with a mild midday depression, which was especially pronounced in males exposed to long photoperiods. While period (per) mRNA peaked earlier under low temperatures, no temperature-dependent splicing of the last per 3' end intron was identified. The expression of timeless, vrille, and Par domain protein 1 was also influenced by temperature, each in a different manner. Our data indicated that comparable behavioral trends in daily activity distribution have evolved in Drosophila melanogaster and M. domestica, yet the behaviors of these two species are orchestrated by different molecular mechanisms.
- MeSH
- 3' Untranslated Regions genetics MeSH
- Time Factors MeSH
- Circadian Rhythm genetics MeSH
- Drosophila melanogaster genetics MeSH
- Exons genetics MeSH
- Photoperiod MeSH
- Phylogeny MeSH
- Genes, Insect * MeSH
- Introns genetics MeSH
- Physical Conditioning, Animal MeSH
- Cryptochromes genetics MeSH
- RNA, Messenger genetics metabolism MeSH
- Houseflies MeSH
- Motor Activity MeSH
- Promoter Regions, Genetic genetics MeSH
- Gene Expression Regulation MeSH
- RNA Splicing genetics MeSH
- Temperature * MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
Cryptochromes are a ubiquitous group of blue-light absorbing flavoproteins that in the mammalian retina have an important role in the circadian clock. In birds, cryptochrome 1a (Cry1a), localized in the UV/violet-sensitive S1 cone photoreceptors, is proposed to be the retinal receptor molecule of the light-dependent magnetic compass. The retinal localization of mammalian Cry1, homologue to avian Cry1a, is unknown, and it is open whether mammalian Cry1 is also involved in magnetic field sensing. To constrain the possible role of retinal Cry1, we immunohistochemically analysed 90 mammalian species across 48 families in 16 orders, using an antiserum against the Cry1 C-terminus that in birds labels only the photo-activated conformation. In the Carnivora families Canidae, Mustelidae and Ursidae, and in some Primates, Cry1 was consistently labeled in the outer segment of the shortwave-sensitive S1 cones. This finding would be compatible with a magnetoreceptive function of Cry1 in these taxa. In all other taxa, Cry1 was not detected by the antiserum that likely also in mammals labels the photo-activated conformation, although Western blots showed Cry1 in mouse retinal cell nuclei. We speculate that in the mouse and the other negative-tested mammals Cry1 is involved in circadian functions as a non-light-responsive protein.
- MeSH
- Immune Sera chemistry MeSH
- Canidae physiology MeSH
- Cone Opsins genetics MeSH
- Retinal Cone Photoreceptor Cells physiology radiation effects ultrastructure MeSH
- Circadian Rhythm physiology radiation effects MeSH
- Gene Expression MeSH
- Phylogeny * MeSH
- Hominidae physiology MeSH
- Immunohistochemistry MeSH
- Protein Conformation MeSH
- Cryptochromes chemistry genetics MeSH
- Magnetic Fields MeSH
- Ursidae physiology MeSH
- Mustelidae physiology MeSH
- Protein Domains MeSH
- Birds physiology MeSH
- Mammals classification physiology MeSH
- Light MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The ability to perceive geomagnetic fields (GMFs) represents a fascinating biological phenomenon. Studies on transgenic flies have provided evidence that photosensitive Cryptochromes (Cry) are involved in the response to magnetic fields (MFs). However, none of the studies tackled the problem of whether the Cry-dependent magnetosensitivity is coupled to the sole MF presence or to the direction of MF vector. In this study, we used gene silencing and a directional MF to show that mammalian-like Cry2 is necessary for a genuine directional response to periodic rotations of the GMF vector in two insect species. Longer wavelengths of light required higher photon fluxes for a detectable behavioral response, and a sharp detection border was present in the cyan/green spectral region. Both observations are consistent with involvement of the FADox, FAD(•-) and FADH(-) redox forms of flavin. The response was lost upon covering the eyes, demonstrating that the signal is perceived in the eye region. Immunohistochemical staining detected Cry2 in the hemispherical layer of laminal glia cells underneath the retina. Together, these findings identified the eye-localized Cry2 as an indispensable component and a likely photoreceptor of the directional GMF response. Our study is thus a clear step forward in deciphering the in vivo effects of GMF and supports the interaction of underlying mechanism with the visual system.
- MeSH
- Phenotype MeSH
- Photoreceptor Cells, Invertebrate metabolism radiation effects MeSH
- Cryptochromes metabolism MeSH
- Magnetic Fields * MeSH
- Compound Eye, Arthropod radiation effects MeSH
- Cockroaches metabolism radiation effects MeSH
- Ultraviolet Rays MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
It has been suggested that weak 50/60 Hz [extremely low frequency (ELF)] magnetic fields (MF) could affect circadian biorhythms by disrupting the clock function of cryptochromes (the "cryptochrome hypothesis," currently under study). That hypothesis is based on the premise that weak (Earth strength) static magnetic fields affect the redox balance of cryptochromes, thus possibly their signaling state as well. An appropriate method for testing this postulate could be real time or short-term study of the circadian clock function of retinal cryptochromes under exposure to the static field intensities that elicit the largest redox changes (maximal "low field" and "high field" effects, respectively) compared to zero field. Positive results might encourage further study of the cryptochrome hypothesis itself. However, they would indicate the need for performing a similar study, this time comparing the effects of only slight intensity changes (low field range) in order to explore the possible role of the proximity of metal structures and furniture as a confounder under the cryptochrome hypothesis.
- MeSH
- Circadian Clocks physiology MeSH
- Cryptochromes physiology MeSH
- Magnetic Fields * MeSH
- Retina physiology MeSH
- Signal Transduction MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The role of the Syn-CRY cryptochrome from the cyanobacterium Synechocystis sp. PCC 6803 has been a subject of research for more than a decade. Recently we have shown that photolyase, showing strong homology with Syn-CRY is required for Photosystem II repair by preventing accumulation of DNA lesions under UV-B (Vass et al. 2013). Here we investigated if Syn-CRY is also involved in PSII repair, either via removal of DNA lesions or other mechanism? The Δsll1629 mutant lacking Syn-CRY lost faster the PSII activity and D1 protein during UV-B or PAR than the WT. However, no detectable damages in the genomic DNA were observed. The transcript levels of the UV-B and light stress indicator gene psbA3, encoding D1, are comparable in the two strains showing that Δsll1629 cells are not defective at the transcriptional level. Nevertheless 2D protein analysis in combination with mass spectrometry showed a decreased accumulation of several, mostly cytoplasmic, proteins including PilA1 and bicarbonate transporter SbtA. Δsll1629 cells exposed to high light also showed a limitation in de novo assembly of PSII. It is concluded that Syn-CRY is required for efficient restoration of Photosystem II activity following UV-B and PAR induced photodamage. This effect is not caused by retardation of DNA repair, instead the synthesis of new D1 (and D2) subunit(s) and/or the assembly of the Photosystem II reaction center complex is likely affected due to the lack of intracellular CO2, or via a so far unidentified pathway that possibly includes the PilA1 protein.
- MeSH
- Bacterial Proteins genetics metabolism MeSH
- DNA, Bacterial genetics MeSH
- Photosystem II Protein Complex genetics metabolism MeSH
- Cryptochromes genetics metabolism MeSH
- DNA Repair * MeSH
- DNA Damage MeSH
- Gene Expression Regulation, Bacterial MeSH
- Light * MeSH
- Synechocystis genetics metabolism radiation effects MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The linden bug Pyrrhocoris apterus exhibits a robust diapause response to photoperiod. Photoperiod strongly affected basal levels of circadian gene transcripts in the gut, via the neuroendocrine system. Cryptochrome 2 (cry2) mRNA level was much higher in diapause promoting short days (SD) than in reproduction promoting long days (LD), while Par Domain Protein 1 (Pdp1) mRNA level was higher in LD than in SD. The effect of photoperiod on gene expression was mediated by the neurosecretory cells of the pars intercerebralis (PI) and the juvenile hormone (JH) producing corpus allatum (CA). In LD-females, CA ablation resulted in SD-like levels of gene transcripts, while PI ablation had little effect. Conversely, in SD-females, CA ablation had only a little effect, while PI ablation resulted in LD-like levels of gene transcripts. Thus, the CA is responsible for LD-like characteristics of gene expression in reproducing females and the PI is responsible for SD-like characteristics of gene expression in diapausing females. A simultaneous ablation of both PI and CA revealed two roles of PI in SD-females: (1) inhibition of CA, and (2) weak CA-independent stimulation of cry2 mRNA. Overall, our results indicate that peripheral circadian gene expression in the gut reflects the physiological state of females (with respect to diapause or reproduction) rather than the external light-dark cycle.
- MeSH
- Circadian Rhythm MeSH
- Corpora Allata physiology MeSH
- Gastrointestinal Tract metabolism MeSH
- Heteroptera metabolism MeSH
- Genes, Insect MeSH
- Insect Proteins genetics metabolism MeSH
- Cryptochromes genetics metabolism MeSH
- Ovary physiology MeSH
- Gene Expression Regulation * MeSH
- Animals MeSH
- Check Tag
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
In temperate regions, the shortening day length informs many insect species to prepare for winter by inducing diapause. The adult diapause of the linden bug, Pyrrhocoris apterus, involves a reproductive arrest accompanied by energy storage, reduction of metabolic needs, and preparation to withstand low temperatures. By contrast, nondiapause animals direct nutrient energy to muscle activity and reproduction. The photoperiod-dependent switch from diapause to reproduction is systemically transmitted throughout the organism by juvenile hormone (JH). Here, we show that, at the organ-autonomous level of the insect gut, the decision between reproduction and diapause relies on an interaction between JH signaling and circadian clock genes acting independently of the daily cycle. The JH receptor Methoprene-tolerant and the circadian proteins Clock and Cycle are all required in the gut to activate the Par domain protein 1 gene during reproduction and to simultaneously suppress a mammalian-type cryptochrome 2 gene that promotes the diapause program. A nonperiodic, organ-autonomous feedback between Par domain protein 1 and Cryptochrome 2 then orchestrates expression of downstream genes that mark the diapause vs. reproductive states of the gut. These results show that hormonal signaling through Methoprene-tolerant and circadian proteins controls gut-specific gene activity that is independent of circadian oscillations but differs between reproductive and diapausing animals.
- MeSH
- Circadian Clocks physiology MeSH
- Photoperiod MeSH
- Heteroptera genetics metabolism MeSH
- Genes, Insect physiology MeSH
- Insect Proteins biosynthesis genetics MeSH
- Cryptochromes biosynthesis genetics MeSH
- Methoprene metabolism MeSH
- Signal Transduction physiology MeSH
- Intestines metabolism MeSH
- Transcription Factors biosynthesis genetics MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
