TAIMAN (TAI), the only insect ortholog of mammalian Steroid Receptor Coactivators (SRCs), is a critical modulator of ecdysone and juvenile hormone (JH) signaling pathways, which govern insect development and reproduction. The modulatory effect is mediated by JH-dependent TAI's heterodimerization with JH receptor Methoprene-tolerant and association with the Ecdysone Receptor complex. Insect hormones regulate insect physiology and development in concert with abiotic cues, such as photo- and thermoperiod. Here we tested the effects of JH and ecdysone signaling on the circadian clock by a combination of microsurgical operations, application of hormones and hormone mimics, and gene knockdowns in the linden bug Pyrrhocoris apterus males. Silencing taiman by each of three non-overlapping double-strand RNA fragments dramatically slowed the free-running period (FRP) to 27-29 hours, contrasting to 24 hours in controls. To further corroborate TAIMAN's clock modulatory function in the insect circadian clock, we performed taiman knockdown in the cockroach Blattella germanica. Although Blattella and Pyrrhocoris lineages separated ~380 mya, B. germanica taiman silencing slowed the FRP by more than 2 hours, suggesting a conserved TAI clock function in (at least) some insect groups. Interestingly, the pace of the linden bug circadian clock was neither changed by blocking JH and ecdysone synthesis, by application of the hormones or their mimics nor by the knockdown of corresponding hormone receptors. Our results promote TAI as a new circadian clock modulator, a role described for the first time in insects. We speculate that TAI participation in the clock is congruent with the mammalian SRC-2 role in orchestrating metabolism and circadian rhythms, and that TAI/SRCs might be conserved components of the circadian clock in animals.
- MeSH
- buněčná membrána MeSH
- cirkadiánní hodiny * genetika MeSH
- cirkadiánní rytmus genetika MeSH
- ekdyson genetika MeSH
- hmyz MeSH
- juvenilní hormony genetika MeSH
- savci MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- ekdyson MeSH
- juvenilní hormony MeSH
EFLamide (EFLa) is a neuropeptide known for a long time from crustaceans, chelicerates and myriapods. Recently, EFLa-encoding genes were identified in the genomes of apterygote hexapods including basal insect species. In pterygote insects, however, evidence of EFLa was limited to partial sequences in the bed bug (Cimex), migratory locust and a few phasmid species. Here we present identification of a full length EFLa-encoding transcript in the linden bug, Pyrrhocoris apterus (Heteroptera). We created complete null mutants allowing unambiguous anatomical location of this peptide in the central nervous system. Only 2-3 EFLa-expressing cells are located very close to each other near to the surface of the lateral protocerebrum with dense neuronal arborization. Homozygous null EFLa mutants are fully viable and do not have any visible defect in development, reproduction, lifespan, diapause induction or circadian rhythmicity. Phylogenetic analysis revealed that EFLa-encoding transcripts are produced by alternative splicing of a gene that also produces Prohormone-4. However, this Proh-4/EFLa connection is found only in Hemiptera and Locusta, whereas EFLa-encoding transcripts in apterygote hexapods, chelicerates and crustaceans are clearly distinct from Proh-4 genes. The exact mechanism leading to the fused Proh-4/EFLa transcript is not yet determined, and might be a result of canonical cis-splicing, cis-splicing of adjacent genes (cis-SAG), or trans-splicing.
- Klíčová slova
- Alternative splicing, CRISPR/Cas9, EFLamide, In silico peptide prediction, Null mutant, TRH,
- MeSH
- fylogeneze MeSH
- Heteroptera genetika metabolismus MeSH
- hmyzí proteiny chemie genetika metabolismus MeSH
- hormon uvolňující thyreotropin genetika metabolismus MeSH
- neuropeptidy chemie genetika metabolismus MeSH
- sekvence aminokyselin MeSH
- sekvenční seřazení MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- hmyzí proteiny MeSH
- hormon uvolňující thyreotropin MeSH
- neuropeptidy MeSH
Evidence accumulates that the functional plasticity of insulin and insulin-like growth factor signaling in insects could spring, among others, from the multiplicity of insulin receptors (InRs). Their multiple variants may be implemented in the control of insect polyphenism, such as wing or caste polyphenism. Here, we present a comprehensive phylogenetic analysis of insect InR sequences in 118 species from 23 orders and investigate the role of three InRs identified in the linden bug, Pyrrhocoris apterus, in wing polymorphism control. We identified two gene clusters (Clusters I and II) resulting from an ancestral duplication in a late ancestor of winged insects, which remained conserved in most lineages, only in some of them being subject to further duplications or losses. One remarkable yet neglected feature of InR evolution is the loss of the tyrosine kinase catalytic domain, giving rise to decoys of InR in both clusters. Within the Cluster I, we confirmed the presence of the secreted decoy of insulin receptor in all studied Muscomorpha. More importantly, we described a new tyrosine kinase-less gene (DR2) in the Cluster II, conserved in apical Holometabola for ∼300 My. We differentially silenced the three P. apterus InRs and confirmed their participation in wing polymorphism control. We observed a pattern of Cluster I and Cluster II InRs impact on wing development, which differed from that postulated in planthoppers, suggesting an independent establishment of insulin/insulin-like growth factor signaling control over wing development, leading to idiosyncrasies in the co-option of multiple InRs in polyphenism control in different taxa.
- Klíčová slova
- decoy of insulin receptor, gene structure, insects, insulin receptor, insulin signaling, wing polyphenism,
- MeSH
- biologická evoluce * MeSH
- duplikace genu MeSH
- Heteroptera genetika růst a vývoj MeSH
- hmyz anatomie a histologie genetika MeSH
- křídla zvířecí anatomie a histologie růst a vývoj MeSH
- receptor inzulinu genetika MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- Názvy látek
- receptor inzulinu MeSH
Circadian clocks are synchronized with the external environment by light and temperature. The effect of these cues on behavior is well-characterized in Drosophila, however, little is known about synchronization in non-model insect species. Therefore, we explored entrainment of locomotor activity by light and temperature in the linden bug Pyrrhocoris apterus (Heteroptera), an insect species with a strong seasonal response (reproductive diapause), which is triggered by both photoperiod and thermoperiod. Our results show that either light or temperature cycles are strong factors entraining P. apterus locomotor activity. Pyrrhocoris is able to be partially synchronized by cycles with temperature amplitude as small as 3°C and more than 50% of bugs is synchronized by 5°C steps. If conflicting zeitgebers are provided, light is the stronger signal. Linden bugs lack light-sensitive (Drosophila-like) cryptochrome. Notably, a high percentage of bugs is rhythmic even in constant light (LL) at intensity ∼400 lux, a condition which induces 100% arrhythmicity in Drosophila. However, the rhythmicity of bugs is still reduced in LL conditions, whereas rhythmicity remains unaffected in constant dark (DD). Interestingly, a similar phenomenon is observed after temperature cycles entrainment. Bugs released to constant thermophase and DD display weak rhythmicity, whereas strong rhythmicity is observed in bugs released to constant cryophase and DD. Our study describes the daily and circadian behavior of the linden bug as a response to photoperiodic and thermoperiodic entraining cues. Although the molecular mechanism of the circadian clock entrainment in the linden bug is virtually unknown, our study contributes to the knowledge of the insect circadian clock features beyond Drosophila research.
- Klíčová slova
- Pyrrhocoris apterus, circadian clock, constant light, entrainment, photoperiod, synchronization, temperature compensation, thermoperiod,
- Publikační typ
- časopisecké články MeSH
Cold tolerance is often one of the key components of insect fitness, but the association between climatic conditions and supercooling capacity is poorly understood. We tested 16 lines originating from geographically different populations of the linden bug Pyrrhocoris apterus for their cold tolerance, determined as the supercooling point (SCP). The supercooling point was generally well explained by the climatic conditions of the population's origin, as the best predictor-winter minimum temperature-explained 85% of the average SCP variation between populations. The supercooling capacity of P. apterus is strongly correlated with climatic conditions, which support the usage of SCP as an appropriate metric of cold tolerance in this species.
- Klíčová slova
- cold tolerance, diapause, overwintering, supercooling point,
- Publikační typ
- časopisecké články MeSH
Several biogenic amines, including controversial presence of norepinephrine (NE), were identified by the high performance liquid chromatography equipped with electrospray ionisation mass spectrometry in brain complexes of adult females of Pyrrhocoris apterus. Quantitative analysis was performed by the high performance liquid chromatography coupled to electrochemical detector. Levels of NE, dopamine (DA), octopamine (OA) and 5-hydroxytryptamine (5-HT) in brain complexes were measured in reproductive vs. diapause females. In field collected samples, levels of NE and DA were significantly higher in reproductive (May) than in non-reproductive (Sep, Oct, Feb) females. In laboratory females, NE is higher in long day photoperiod (reproduction) than in short day photoperiod (diapause) already from the first week of the adult age, while DA shows differences between the two contrasting photoperiods only from the second week of the adult age. No association between reproductive status and levels of OA and 5-HT was found.
- Klíčová slova
- Adult diapause, Brain complex, Dopamine, Insects, Mass spectrometry, Norepinephrine,
- MeSH
- chromatografie kapalinová MeSH
- dopamin metabolismus MeSH
- Heteroptera metabolismus MeSH
- hmotnostní spektrometrie s elektrosprejovou ionizací metody MeSH
- katecholaminy metabolismus MeSH
- mozek metabolismus MeSH
- noradrenalin metabolismus MeSH
- oktopamin metabolismus MeSH
- roční období MeSH
- rozmnožování MeSH
- Tilia parazitologie MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- dopamin MeSH
- katecholaminy MeSH
- noradrenalin MeSH
- oktopamin MeSH
