This study describes defense functions of the insect neuropeptide sericotropin, which is recognized as an agent that stimulates silk production in some lepidopteran larvae. Sericotropin, expressed in brain tissue of the wax moth Galleria mellonella in all developmental stages, is not expressed in silk glands, indicating its tissue specificity. Fluorescence microscopy confirmed the presence of sericotropin in the brain-subesophageal complex being predominantly and densely distributed under the plasmatic membrane and in axonal parts of neurons. Injection of venom from Habrobracon hebetor and topical application of the entomopathogenic nematode (EPN) Steinernema carpocapsae with symbiotic bacteria Xenorhabdus spp. into or onto G. mellonella larvae resulted in upregulation of the sericotropin gene and peptide, suggesting a role for sericotropin in defense and immunity. Accordingly, two synthetic fragments of sericotropin killed entomotoxic Xenorhabdus spp. bacteria in a disc diffusion antimicrobial test. Further, total metabolism, monitored by carbon dioxide production, significantly decreased after application of either venom or EPN, probably because of muscle impairment by the venom and serious cell damage caused by EPN, especially in the midgut. Both venom and EPN upregulated expression of genes encoding antimicrobial peptides gallerimycin and galiomicin in Galleria brain; however, they downregulated prophenoloxidase and phenoloxidase activity in hemolymph. These results suggest that sericotropin is a multifunctional peptide that plays an important role in G. mellonella defense and immunity.
- MeSH
- hlístice fyziologie MeSH
- interakce hostitele a parazita imunologie MeSH
- larva účinky léků metabolismus parazitologie MeSH
- můry účinky léků metabolismus parazitologie MeSH
- neuropeptidy genetika metabolismus MeSH
- regulace genové exprese účinky léků MeSH
- vosí jedy toxicita MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
This study examined the effect of two natural toxins (a venom from the parasitic wasp Habrobracon hebetor and destruxin A from the entomopathogenic fungus Metarhizium anisopliae), and one pathogen (the entomopathogenic fungus Isaria fumosorosea) on the activity of basic digestive enzymes in the midgut of the cockroach Periplaneta americana. Simultaneously, the role of adipokinetic hormones (AKH) in the digestive processes was evaluated. The results showed that all tested toxins/pathogens elicited stress responses when applied into the cockroach body, as documented by an increase of AKH level in the central nervous system. The venom from H. hebetor showed no effect on digestive enzyme activities in the ceca and midgut in vitro. In addition, infection by I. fumosorosea caused a decrease in activity of all enzymes in the midgut and a variable decrease in activity in the ceca; application of AKHs did not reverse the inhibition. Destruxin A inhibited the activity of all enzymes in the midgut but none in the ceca in vitro; application of AKHs did reverse this inhibition, and no differences between both cockroach AKHs were found. Overall, the results demonstrated the variable effect of the tested toxins/pathogens on the digestive processes of cockroaches as well as the variable ability of AKH to counteract these effects.
- MeSH
- aktivace enzymů MeSH
- depsipeptidy toxicita MeSH
- gastrointestinální trakt enzymologie MeSH
- hmyzí hormony farmakologie MeSH
- kyselina pyrrolidonkarboxylová analogy a deriváty farmakologie MeSH
- oligopeptidy farmakologie MeSH
- Periplaneta účinky léků enzymologie MeSH
- vosí jedy toxicita MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The effect of Habrobracon hebetor venom and the role of the adipokinetic hormone (AKH) in poisoned adult females of the firebug Pyrrhocoris apterus were studied 24 and 48h after treatments. Venom application elicited total neuromuscular paralysis in firebugs, but the co-application of venom and Pyrap-AKH significantly reduced paralysis (up to 3.2 times) compared to the application of venom only. Although the mechanisms of their action are unknown, both agents might affect neuromuscular junctions. Venom application significantly increased the expression of both P. apterus Akh genes (Pyrap-Akh 5.4 times and Peram-Cah-II 3.6 times), as well as the level of AKHs in the central nervous system (2.5 times) and haemolymph (3.0 times). In the haemolymph, increased AKH levels might have led to the mobilization of stored lipids, which increased 1.9 times, while the level of free carbohydrates remained unchanged. Total metabolism, monitored by carbon dioxide production, significantly declined in paralysed P. apterus individuals (1.4 times and 1.9 times, 24 and 48h after the treatment, respectively), probably because of a malfunction of the muscular system. The results suggest an active role of AKH in the defence mechanism against the stress elicited by neuromuscular paralysis, and the possible involvement of this hormone in neuronal/neuromuscular signalling.
- MeSH
- alostáza MeSH
- biologické markery metabolismus MeSH
- centrální nervový systém účinky léků metabolismus MeSH
- energetický metabolismus účinky léků MeSH
- hemolymfa účinky léků metabolismus MeSH
- Heteroptera účinky léků fyziologie MeSH
- hmyzí hormony agonisté genetika fyziologie sekrece MeSH
- hrudník MeSH
- injekce MeSH
- kinetika MeSH
- kyselina pyrrolidonkarboxylová agonisté analogy a deriváty MeSH
- nervosvalové spojení účinky léků fyziologie MeSH
- neuropeptidy agonisté analýza genetika fyziologie sekrece MeSH
- oligopeptidy agonisté genetika fyziologie sekrece MeSH
- paralýza chemicky indukované veterinární MeSH
- upregulace účinky léků MeSH
- vosí jedy antagonisté a inhibitory izolace a purifikace toxicita MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
Alergické reakce na včelí a vosí jed představují závažný klinický problém, protože ty, které jsou způsobené časným (IgE zprostředkovaným) typem přecitlivělosti, mají často velmi těžký průběh. U pacientů je nutné nejen správně reakci diagnostikovat, ale vzhledem k tomu, že se reakce při dalším žihadle může opakovat, naučit pacienty poskytování neodkladné první pomoci. Jedinou dosud známou léčbou těchto alergických stavů je podávání specifické alergenové imunoterapie (AIT).
