Effect of weak static and low-frequency alternating magnetic fields on the fission and regeneration of the planarian dugesia (Girardia) tigrina.

The effect of weak static (DC) and alternating (AC) magnetic fields (MFs), as well as combined (AC/DC) collinear MFs on the intensity of morphogenesis processes in the planarian Dugesia (Girardia) tigrina has been studied. It was found that combined MFs produce a stimulating effect on the fission and regeneration of planarians. Both components of the combined MFs, the direct (DC) and the alternating (AC), are important in the realization of the effects of weak MFs. The practically complete absence of one of the components (DC) reverses the sign of the effect. It was shown that the presence of concomitant background MFs does not substantially influence the effects of combined MFs with a very small AC component (100 nT). The effect of the "zero" field is significant and comparable in magnitude with the effects of combined MFs at effective frequencies. Narrow zones of effective amplitudes (in the region of tens and hundreds of nT) of the AC component of the combined MFs, with the DC component close to the value of the geomagnetic field were found, which alternate with regions where the response of the biological object to the influence is absent.

Effects of neuropeptide F on regeneration in Girardia tigrina (Platyhelminthes).

The effects of neuropeptide F (NPF; from Moniezia expansa) on the regeneration of Girardia tigrina were studied. The animals were decapitated and incubated in water (control) or NPF. The dynamics of the proliferation of the neoblasts in the developing tissue were studied during the course of regeneration by monitoring the mitotic index (MI). The effects of incubation in FMRFamide and GYIRFamide on the MI were also tested. The course of cephalic regeneration was followed with in vivo computer-assisted morphometry for up to 7 days. The development of the regenerating nervous system and the musculature was visualised by immunostaining with a primary antiserum to the C-terminal decapeptide of NPF (YFAIIGRPRFa) and tetramethylrhodamine-isothiocyanate-conjugated phalloidin, which stains F-actin in muscle filaments. The study showed that NPF had a stimulatory effect on the mitotic activity of the neoblasts. FMRFamide and GYIRFamide did not have this effect. NPF also stimulated the growth of the regenerating head and the growing nervous system and musculature. NPF is postulated to have a morphogenetic action in the regenerating animals.