Inhibition of the development of the reproductive tract in parasitized snails

Abstract

Myoblasts, muscle cells with the capacity to divide, have been detected in "Anlagen" of the male copulation organ of Lymnaea stagnalis. They only occur in the apical part of the penis. Here they could be found throughout life. Mitotic activity of these cells can be demonstrated by using an antiserum to a S-phase specific cell cycle marker, PCNA [see, e.g., Baserga (1991)l. The numberlpercentage of PCNA positive myoblasts is a good parameter for growth of this male copulation organ and hence also for inhibition of its growth and development as occurs in parasitized snails. In transplantation experiments, "Anlagen" of the copulation organ were used from snails 7-9 weeks after being parasitized as they can be excised in this stage and transplanted into either parasitized or nonparasitized snails. These experiments have indicated that humoral, parasitic excretorylsecretory factors can be responsible for the inhibition of growth and .differentiation of the copulation organ in parasitized snails as reflected by a relatively low number of PCNA positive myoblasts compared to the controls. Data obtained in in vitro experiments showed a significant decrease of the number of myoblasts in "Anlagen" cultured in the presence of parasitic E/S products. The fact that no significant effect was found on the relative low number of PCNA positive myoblasts is discussed. The effect of parasitic E/S products on these myoblasts appeared to be exerted in a direct way, not mediated by CNSderived factors or by factors from cells in the connective tissue sheath around the CNS. Although it appears possible to use transplantation and/or in vitro culturing of these "Anlagen" as a bioassay for identification of the parasitic factor@) responsible for the inhibitory effects on myoblasts, the methods are very laborious and do not seem very appropriate for testing many fractions of EIS products.

Aspects of body size and mate choice in the simultaneously hermaphroditic pond snail Lymnaea stagnalis

“…Koene, K. Montagne-Wajer and A. Ter Maat, data unpubl. ); parasitised individuals are often castrated (De Jong-Brink et al, 1999). Our observations of spontaneous matings show that animals of 18 mm are already able to mate as male as well as female.…”

Occurrence of Cruzia tentaculata Larvae in the Land Snail Megalobulimus abbreviatus—Influence of Natural Parasite Load on Snail Physiology

“…This gland is under the control of neuropeptides from the cerebral and right parietal ganglia (Moraes et al, 2010), and the frequent location of C. tentaculata larvae in the central nervous ganglia could interfere with the reproductive control carried out by this neuroendocrine complex of M. abbreviatus . The interference with the reproduction of Lymnaea stagnalis by Trichobilharzia ocellata cercariae could be through the neuroendocrine control functions of the cerebral ganglia of L. stagnalis (Schallig et al, 1991; de Jong-Brink et al, 1999; Hoek et al, 2005). However, no negative correlation was found between the number of cysts located specifically in the nerve ring and ovotestis weight or albumen gland volume in collected specimens of M. abbreviatus .…”