Physiology and lipid metabolism of Littorina saxatilis infected with trematodes

Abstract

Physiological and biochemical alterations in Littorina saxatilis infected with larval trematodes were investigated and compared with the metabolism of non-parasitized snails. Oxygen consumption rates of infected snails differed from those of non-infected controls in medium sized individuals (30 to 130 mg) but not in very large infected individuals (> 200 mg). Small snails (0.5 to 8.5 mg) were seldom infected by parasites, and this size-class consisted only of non-infected specimens. The specific oxygen consumption rate of infected snails was not dependent on their mass and remained constant over the size ranges investigated. Alterations in the snail metabolism appeared to be connected to injuries to digestive gland tissues caused by the parasites. The glycogen concentration and fatty acids of neutral lipids and phospholipids in the digestive gland were determined. Infected snails differed from uninfected snails in the complete absence of glycogen in digestive gland and had proportionally higher quantities of eicosenoic (20:1) acid in the total phospholipids. It remains unclear whether infection by trematodes activates enzymes in the snail's digestive gland to synthesize eicosenoic (20:1) acid, or whether the sporocysts themselves possess these enzymes. The role of phospholipid fatty acids in the regulation and maintenance of the parasite's metabolism is briefly considered. Biochemical alterations observed in the fatty acid composition may have an adaptive significance, by helping to stabilize the host-parasite system. KEY WORDS: Littorina saxatilis · Metabolism · Trematodes · Digestive gland · Phospholipids · Fatty acids Resale or republication not permitted without written consent of the publisherDis Aquat Org 60: [223][224][225][226][227][228][229][230][231] 2004 tems of Lymnaea stagnalis and cause castration and gigantism in this species (De Jong-Brink 1995). Trematode parasitism does not have a significant effect on the growth rate of Littorina saxatilis but stunts growth in Littorina obtusata, and enhances growth rate and size at maturity in Onoba aculeus (Gorbushin & Levakin 1999). Infected Littorina littorea either show reduced growth, or the parasites do not effect growth rates (Mouritsen et al. 1999). Co-adaptivity within the host-parasite system has been suggested as an explanation for gigantism in parasitized individuals of longlived snail species (Minchella 1985). According to Curtis et al. (2000), however, the oversized snails in long-lived Ilyanassa obsoleta were the result of greater age rather than of faster growth induced by parasites. Thus it is probable that the co-adaptivity theory is not always valid. Most likely, parasites have different effects on growth rate in different species.With regards to energy metabolism, several studies have shown that alterations in oxygen consumption rates in poikilothermic animals induced by parasitic invasion are inconsistent. For example,the presence of larval trematodes in Physa occidentalis induced higher requirements for oxygen in the host (H...

Rates of energy and phosphorus metabolism in Littorina snails (gastropoda)

“…1 fall within a nar row temperature range and were approximated by the same equation R = (0.0013 ± 0.0004) DWt 0.835 ± 0.053 (n = 61, r 2 = 0.81). Previous data on oxygen consump tion by L. saxatilis from the Atlantic and White Sea (Aldridge, Russell Hunter, and McMahon, 1995;Arakelova, Chebotareva, and Zabelinskii, 2004) indi cated that, according to low regression coefficients b (0.17 and 0.46, respectively), this parameter was only slightly dependent on body weight. The above coeffi cients are significantly lower than the accepted allom etric index characterizing the rate of physiological (Aldridge, Russell Hunter, and McMahon, 1995) and 7°С (Sokolova, Bock, and Pörtner, 2000) are adjusted to 15 and 12°C, respectively, using temperature correction factors q for mollusks (Alimov, 1981).…”

“…The total fresh and dry body weights of L. saxatilis snails were calculated by previously derived equations of the form W = f(L) (Arakelova, Chebotareva, and Zabelinskii, 2004): W = 0.429L 2.78 (n = 29, r 2 = 0.99), DWt = 0.052L 2.68 (n = 20, r 2 = 0.98), where W and DWt are the total fresh weight and the dry body weight without shell (mg), respectively. These val ues were used to calculate physiological parameters.…”

“…Studies on the energy metabolism of littoral mol lusks often involve analysis of compensatory reactions, which are characteristic of organisms inhabiting the upper littoral zone and exposed to abrupt fluctuations of various environmental factors (Aldridge, Russell Hunter, and McMahon, 1995;Sokolova, Bock, and Pörtner, 2000;Larade and Storey, 2002;Arakelova, Chebotareva, and Zabelinskii, 2004). Energy metabo lism is directly connected with other physiological processes, and its analysis can provide an insight into metabolism of the organism as a whole, based on the quantitative assessment of the fluxes of biogenic ele ments in it (Sterner and Elser, 2002).…”

Assessment of the Lipid Composition and Some Components of the Antioxidant System in Blue Mussels Mytilus Edulis Experimentally Infected With Himasthla Elongata Metacercariae

“…Среди многообразия аспектов во взаи-моотношениях «паразит -хозяин» актуальным остается вопрос о влиянии паразитов на био-химический статус хозяина. Достаточно под-робно описаны метаболические модификации, вызванные инвазией трематод, у брюхоногих моллюсков [Lunetta, Vernberg, 1971;Thompson, 1983;Fried et al, 1993a, б;Arakelova et al, 2004Arakelova et al, , 2007Vorontsova et al, 2010;Gornowicz et al, 2013;Tyutin, Izvekova, 2013], однако исследо-вания биохимических параметров двуствор-чатых моллюсков, зараженных трематодами, фактически отсутствуют. Считается, что пато-генное воздействие метацеркарий трематод на организм второго промежуточного хозяина минимально [Bower et al, 1994;Laruelle et al, 2002], поскольку в большинстве случаев ме-тацеркарии представляют собой покоящуюся стадию, «ожидающую» попадания в организм окончательного хозяина [Werding, 1969].…”

“…При этом известно, что внедрение паразита инду-цирует значительные метаболические пере-стройки в организме хозяина, инициируя фор-мирование активных форм кислорода (АФК) и тем самым вызывая окислительный стресс и активацию антиоксидантной системы (АОС) [Vorontsova et al, 2010;Gornowicz et al, 2013;Tyutin, Izvekova, 2013]. В связи с этим с помо-щью биохимических маркеров, в том числе по-казателей, отражающих работу АОС, а также состав липидов и их жирных кислот (которые служат основной мишенью для действия АФК), можно оценить влияние паразитарной инвазии на организм промежуточного хозяина [Fried, Bradford, 1984;Fried et al, 1995;Arakelova et al, 2004Arakelova et al, , 2007Руднева и др., 2004;Vorontsova et al, 2010;Gornowicz et al, 2013].…”