Effect of Multiple Parasitic Infections on the Tolerance to Pollutant Contamination

Abstract

The horizontally-transmitted acanthocephalan parasite Polymorphus minutus and the vertically-transmitted microsporidian parasite Dictyocoela roeselum have both been shown to influence on the antitoxic responses of mono-infected Gammarus roeseli exposed to cadmium. The present study investigates the effect of this co-infection on the antitoxic defence responses of naturally infected females exposed to cadmium stress. Our results revealed that, depending on the cadmium dose, bi-infection induced only slight, significant increased cell damage in G. roeseli as compared to non-infection. In addition, the antitoxic defence pattern of cadmium-exposed bi-infected hosts was similar to the pattern of cadmium-exposed D. roeselum-infected hosts. Reduced glutathione concentrations, carotenoid levels and γ-glutamylcystein ligase activity decreased, while metallothionein concentrations increased. This similar pattern indicates that host physiology can be controlled to some extent by microsporidia under stress conditions. It supports the hypothesis of a disruption of acanthocephalan effects in the presence of microsporidia. However, the global negative effects of bi-infection on host condition should be tested on more biological models, since competition between parasites depends on life history trade-off.

Effect of multiple microsporidian infections and temperature stress on the heat shock protein 70 (hsp70) response of the amphipod Gammarus pulex

“…Sabotage of the host manipulation strategy of an acanthocephalan by a vertically transmitted microsporidian leading to decreased predation of the amphipod by the final host was reported by Haine et al [ 46 ]. On the biochemical level, the results of Gismondi et al [ 18 ] indicate a similar competitive effect of an acanthocephalan larvae and a vertically transmitted microsporidian, but only after cadmium exposure as additional stressor. Such a mutual influence between horizontally and vertically transmitted microsporidians (e.g.…”

“…On the other hand, vertically transmitted microsporidians often do not seem to affect the host populations when measuring mortality [ 5 ], but might have effects on behavior [ 9 ] or juvenile growth [ 15 , 16 ]. Additionally, microsporidian parasites can influence the response of their amphipod hosts to density dependent factors like food limitation and crowding [ 15 ] or environmental contamination with heavy metals [ 17 , 18 ]. If parasitized populations have to face additional stressors, the impact on parasitized individuals might be different compared to uninfected gammarids.…”

Biochemical and morphological responses in Chironomus riparius (Diptera, Chironomidae) larvae exposed to lead‐spiked sediment

“…The glycogen content increased according to the concentration of Pb in sediment. This result is quite surprising because glycogen depletion has often been reported in aquatic invertebrates after toxic stress [7,37]. Nevertheless, although Choi et al [7] observed a decrease of glycogen following 24 h of exposure to insecticide, they also noticed a rapid recovery of glycogen content after 48 h. As proposed by Servia et al [20], C. riparius larvae may be able to consume glycogen through their food supply.…”

Origin of the natural variation in the storage of dietary carotenoids in freshwater amphipod crustaceans

“…Such a stress could even be stronger when gammarids are suffering from additional environmental stressors, which are often prevalent in nature. For instance, parasitized Gammarus roeseli exhibited a strong depletion of circulating carotenoids and enhanced level of lipoperoxidation damages when exposed to pollutants [52,53]. Similar states of stress might be possible from environmental temperature changes when combined with pathogenic challenges [54].…”