Lysosomes as cellular markers of environmental pollution: Time‐ and dose‐dependent responses of the digestive lysosomal system of mussels after petroleum hydrocarbon exposure

Abstract

Lysosomes are cell organelles containing hydrolytic enzymes and involved in intracellular digestion. Numerous environmental contaminants can interfere with lysosomes, and the purpose of the present work was to quantify changes induced by petroleum hydrocarbons on the structure of the lysosomal system of mussel digestive cells. Mussels, Mytilus galloprovincialis Lmk., were exposed for three months to the water accommodated fraction (WAF) of two crude oils (URAL and MAYA) and of a lubricant oil. Three different exposure doses (0.6, 6, and 40% WAF) were used for each type of hydrocarbon and mussels were sampled at different time intervals (days 21,49, and 91). A stereological study, using an automated image analysis system, was made on sections stained for demonstration of P-glucuronidase activity and four parameters were calculated: lysosomal volume density, surface density, surface to volume ratio, and numerical density. The results indicate that the effect of the exposure dose on lysosomal structure is variable and there is no linear relationship of lysosomal changes with dose. Regarding the effect of the exposure time, two different responses were evidenced: (a) a short-term response (at day 21) with a decrease in size and numbers of lysosomes and (b) a long-term response (at days 49 and 91) with an increase in lysosomal size and a decrease in their numbers. The short-term response may be due to a disintegration process of the digestive cells with subsequent loss of lysosomes and could represent an adaptative response to hydrocarbon exposure. At long exposure times, lysosomal changes, apparently caused by fusion processes giving rise to enlarged lysosomes, correspond to a "general stress response." o 7995

The effect of sublethal lead exposure on the ultrastructure and on the distribution of acid phosphatase activity in chloragocytes of earthworms (Annelida, Oligochaeta)

“…Some toxicants may also stimulate the liberation of whole chloragocytes from the gut wall as noted by Fischer (1989) and Fischer and Moln~r (1992) in Eisenia foetida under paraquat exposure. The active excretion of xenobiotic-loaded lysosomes has also been suggested in other invertebrate systems, such as in the kidney and the digestive gland of molluscs exposed to both metals (George, 1983;Viarengo, 1989;Marig6mez et al, 1990b) and hydrocarbons (Cajaraville et al, 1990(Cajaraville et al, , 1995. In conclusion, the chloragocytes of oligochaetes may be considered as an efficient detoxification mechanism that first accumulates and immobilizes toxic metals and then eliminates them by the stimulation of chloragosome exocytosis or even extrusion of whole chloragocytes.…”

“…The occurrence of fusion events has been quantitatively demonstrated using stereological methods in terms of an increased size of lysosomes concomitant with a decrease in their numbers. These phenomena have been well documented in the lysosomal system of molluscan digestive cells upon exposure to metals (Marig6mez et al, 1989) or petroleum hydrocarbons (Lowe et al, 1981;Cajaraville et al, 1995).…”

The Distribution of the MusselMytilusSpecies Along the Norwegian Coast

“…Diverse sources of environmental stress (chemical pollution, salinity changes, elevated temperature, malnutrition, reproductive stress) are known to provoke an increase in the size of digestive cell lysosomes in mussels, often accompanied by increased enzyme activity and lysosome numbers, which may compromise intracellular digestion and detoxification capacity (Moore, 1985;1988;Lowe, 1988;Cajaraville et al, 1989;Marigómez et al, 1995;Domoutsidou and Dimitriadis, 2001;Garmendia et al, 2011a). These lysosomal structural changes (LSC) have been commonly determined by image analysis of digestive gland cryotome sections where β-glucuronidase is employed as lysosomal marker enzyme.…”

Assessment of the Water and Habitat Quality of a Mediterranean River (Kalamas, Epirus, Hellas), in Accordance with the EU Water Framework Directive

“…Biomonitoring is already widespread since it provides information on the water quality and ecology [5Ϫ7]. Biomonitoring includes both sublethal changes at the cellular or tissue level [8,9] and changes in community structure [10]. The use of changes in community structure commonly involves benthic invertebrates, since they are considered to be the most appropriate biotic indicator of water quality in EU countries, including Greece [5,6,11].…”