Organophosphate-resistant forms of acetylcholinesterases in two scallops--the Antarctic Adamussium colbecki and the Mediterranean Pecten jacobaeus

Seasonal antioxidant and biochemical properties of the Northern Adriatic Pecten jacobaeus

The present work is the first study of Mediterranean scallop (Pecten jacobaeus) biochemical properties, antioxidant defenses, and free radical scavengers during the yearly seasons in the Northern Adriatic, off Istria. Scallop nutrient reserves (glucose, triglyceride, and cholesterol) in four tissues under examination were positively correlated and were predominant in digestive gland and gonad. The muscle energy maxima were in correlation with the maximum fall gonosomatic index (GSI), when diatoms and coccolithophorids thrive. The decrease of GSI in summer might be related to the spawning or resorption of gametes. Summer also revealed elevated levels of glucose in gonad and digestive gland, while muscle glucose and cholesterol significantly varied in spring vs. winter samples. In relation to the diatom seasonal abundance, carotenoids, namely astaxanthin peaks were found in digestive gland, which, being stimulators of calcium transport over cell membranes, could have contributed to the high digestive gland levels of calcium in winter. In winter, total antioxidative status (TAS) of scallop tissues was 3-fold higher than in other seasons, particularly in digestive gland, having a significant correlation with magnesium, a regulatory tool in oxidative processes. The winter maxima of TAS and thiobarbituric acid reactive substances TBARS in relation to summer maxima of glutathione peroxidase and superoxide dismutase in digestive glands indicate to a decrease in antioxidant defense during cold months, and are related to the accumulation of lipid peroxidation products (such as malondialdehyde) in digestive gland of scallops. Although the increased susceptibility to oxidative stress could be attributed to winter temperature, other factors such as the gonad maturation, availability of food supply, and salinity might counteract that effect. The seawater alterations of salinity, temperature and water quality are in relation to the river Po influx, which is very likely to influence the physiological and biochemical responses of scallops in the Northern Adriatic.

Acetylthiocholine (ATC)--cleaving cholinesterase (ChE) activity as a potential biomarker of pesticide exposure in the Manila clam, Ruditapes philippinarum, of Korea

The acetylthiocholine (ATC) - cleaving cholinesterase (ChE) activity in Manila clam, which is widely distributed throughout the coastal environment of Korea, was assayed as a potentially useful biomarker of organophosphorous pesticides (OPs). A clear dose-response relationship was determined between inhibited ChE in adductor muscle of clams and four OPs (methidathion, chlorpyrifos, diazinon, IBP) which are heavily used OPs in Korea. The measured EC(50)-24 h values of methidathion, chlorpyrifos, diazinon, and IBP for Ruditapes philippinarum were 7.16 μg l(-1), 0.34 mg l(-1), 3.01 mg l(-1), and 3.41 mg l(-1), respectively. In field studies, ChE activity in Manila clams collected from 23 stations in the mid-western coastal region demonstrated spatial variation with statistical differences. These results suggest that ChE activity in R. philippinarum is a potential biomarker for assessing organophosphorous pesticide contamination in coastal environments.

Biochemical characterization of cholinesterases in Enchytraeus albidus and assessment of in vivo and in vitro effects of different soil properties, copper and phenmedipham

Enchytraeus albidus are important organisms of the soil biocenosis, used as standard test species in environmental risk assessment. The inhibition of cholinesterases (ChE) activity of several species has been widely used to assess the exposure and effects of anti-cholinesterase environmental contaminants. Several studies have shown the association between ChE activity inhibition and adverse effects on behaviour and survival. Extensive studies addressing survival and behavioural endpoints, as well as other biomarkers, have been done in E. albidus with different types of soil contaminants. The main objectives of this study were: (1) to characterize biochemically the ChE present in the soluble post-mitochondrial fraction of E. albidus whole body homogenates, using different substrates and selective inhibitors; (2) to assess the in vivo effects of copper, phenmedipham and different soil properties (pH, organic matter, clay) on the ChE activity; (3) to assess the in vitro effects of copper and phenmedipham on the ChE activity. The results suggest the presence of one ChE in the soluble post-mitochondrial fraction of E. albidus whole body homogenates, which displays properties of both acetylcholinesterase and pseudocholinesterase considering the typical mammalian enzymes. It is also shown that ChE activity is not inhibited by exposure to different soil properties and that copper and phenmedipham inhibited ChE activity both in in vivo and in in vitro conditions and therefore ChE inhibition seems to be a robust biomarker for this herbicide and this heavy metal. This study showed that ChE activity in E. albidus might be correlated to previously determined higher level effects like survival and reproduction, as well as avoidance behaviour.

prag01, a novel deltamethrin-resistance-associated gene from Culex pipiens pallens

The prag01 gene (GenBank accession no. EU073017) was cloned from Culex pipiens pallens. An open reading frame of 270 bp was found to encode a putative 89-amino-acid protein which has the highest homology with Culex quinquefasciatus and Anopheles funestus. Real-time quantitative PCR analysis demonstrated that the transcription level of prag01 gene in deltamethrin-resistant strain was 1.65-fold higher than in deltamethrin-susceptible strain of C. pipiens pallens. Overexpression of prag01 gene in the mosquito C6/36 cells showed better prolification than the cells with empty vector when treated by deltamethrin. Our data for the first time approved that prag01 gene might play some role in the development of deltamethrin resistance in C. pipiens pallens.

Cloning and characterization of myosin regulatory light chain (MRLC) gene from Culex pipiens pallens

Myosin regulatory light chain (MRLC) (GenBank accession no. DQ140391) was cloned from Culex pipiens pallens. An open reading frame (ORF) of 630 bps was found to encode a putative 210 amino acids protein which shows 73% similarity with myosin regulatory light chain of Gryllotalpa orientalis. Real-time quantitative PCR analysis demonstrated that the transcription level of MRLC in deltamethrin-resistant strain (DR-strain) was 4.08-fold higher than in deltamethrin-susceptible strain (DS-strain) of C. pipiens pallens. Over-expression of MRLC in Aedes albopictus C6/36 cells conferred protection against deltamethrin based on tritiated methyl tritiated thymidine ((3)H-TdR) incorporation assay. These results indicate that MRLC may be a potential cause of deltamethrin resistance in C. pipiens pallens.

Cloning and characterization of 40S ribosomal protein S4 gene from Culex pipiens pallens

The 40S ribosomal protein S4 gene (RPS4) has been cloned from Culex pipiens pallens. An open reading frame (ORF) of 789 bp was found to encode a putative 262 amino acid protein. The deduced amino acid sequence shares 96% and 91% identity with RPS4 genes from Aedes and Anopheles respectively. Transcript expression of RPS4 was determined by real-time PCR in all life stages of deltamethrin-susceptible and -resistant strains. The results demonstrated that this gene is expressed at all developmental stages. Meanwhile, in pupae and adults, RPS4 is overexpressed in deltamethrin-resistant strain than in -susceptible strain. Our data for the first time suggests that increased expression of the RPS4 gene may play some role in the development of deltamethrin resistance in C. pipiens pallens.