[The role of microsporidia in the disturbance of the hormonal balance in the infected insects].
Since investigations of Fisher and Sanborn (1964), the most popular point of view on pathological alterations in the development of insects is the statement that microsporidians can produce and secrete the insect juvenile hormone in infected tissues. We suppose that the juvenilizing effect of microsoporidian infection may be a consequence of stress induced by the protozoan invasion. To our opinion, microsporidians can not be a source of juvenile hormone in parasitized insects because of several reasons. 1. The juvenilizing effect of infection may be explained by other reason, that is the stress effect of invasion. 2. Until now nobody can find juvenile hormone in microsporidians. 3. An increase of juvenile hormone titre either alters non-metabolic activity of fat body or alters it in a way that is not favorable for microsporidias. 4. Some effects of the microsporidian infection more resemble an action of ecdysone, but not juvenile hormone. Hypothesis of parasitic stress can explain this, while hypothesis of production JH by microsporidians can not. 5. An effect of invasion by parasites of other systematic groups onto the hormone balance is of the same type. But nobody thinks that other parasites can produce juvenile hormone. Nevertheless it is clear that a high titre of the juvenile hormone is favorable for the microsporidian infection in larvae, especially the last instars. The most descriptions of microsporidian infections are related with this age of insects. Juvenilizing effect of Nosema implantant in the work of Fisher and Sanborn (1964) may be easily explained by decreasing of JH-esterase activity. But in this case the decrease of JH-esterase activity after the implantation of infected tissue in a healthy insect should be explained. We suppose that this fact witness the existence of stress-factor produced by damaged cells of fat body that can enter the healthy cells of fat body and inhibit the activity of JH-esterases.
Seleznev
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KV
D000818:Animals; D006728:Hormones / Q000378:metabolism*; D006790:Host-Parasite Interactions / Q000502:physiology*; D007313:Insecta / Q000469:parasitology*; D007605:Juvenile Hormones / Q000378:metabolism; D016814:Microsporidia / Q000472:pathogenicity / Q000502:physiology*
D006728:Hormones; D007605:Juvenile Hormones