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At least 19 recordsLinked to original sources
PubMed2001

Ultrastructural characterisation of Marteilia species (Paramyxea) from Ostrea edulis, Mytilus edulis and Mytilus galloprovincialis in Europe.

A focused ultrastructural study of Marteilia spp. found in cultured Ostrea edulis, Mytilus edulis and Mytilus galloprovincialis from France and Spain was conducted with emphasis placed on haplosporosomes, striated plate-like inclusions and spore wall morphology. Two types of haplosporosome were identified, sphaeroid and oblate, which were common to the parasite in all 3 host species. A total of 492 haplosporosomes were measured; those from the Marteilia sp. in Mytilus spp. were marginally smaller than those in Ostrea edulis. Spore wall morphology was found to vary depending on the state of maturity of the parasite--the more mature the parasite, the thicker the wall surrounding it. It is suggested that the current criteria used to distinguish M. maurini from M. refringens are invalid and that M. maurini was relegated to a junior synonym of M. refringens.

Animals↗
PubMed2005

Local adaptation and species segregation in two mussel (Mytilus edulis x Mytilus trossulus) hybrid zones.

Few marine hybrid zones have been studied extensively, the major exception being the hybrid zone between the mussels Mytilus edulis and Mytilus galloprovincialis in southwestern Europe. Here, we focus on two less studied hybrid zones that also involve Mytilus spp.; Mytilus edulis and Mytilus trossulus are sympatric and hybridize on both western and eastern coasts of the Atlantic Ocean. We review the dynamics of hybridization in these two hybrid zones and evaluate the role of local adaptation for maintaining species boundaries. In Scandinavia, hybridization and gene introgression is so extensive that no individuals with pure M. trossulus genotypes have been found. However, M. trossulus alleles are maintained at high frequencies in the extremely low salinity Baltic Sea for some allozyme genes. A synthesis of reciprocal transplantation experiments between different salinity regimes shows that unlinked Gpi and Pgm alleles change frequency following transplantation, such that post-transplantation allelic composition resembles native populations found in the same salinity. These experiments provide strong evidence for salinity adaptation at Gpi and Pgm (or genes linked to them). In the Canadian Maritimes, pure M. edulis and M. trossulus individuals are abundant, and limited data suggest that M. edulis predominates in low salinity and sheltered conditions, whereas M. trossulus are more abundant on the wave-exposed open coasts. We suggest that these conflicting patterns of species segregation are, in part, caused by local adaptation of Scandinavian M. trossulus to the extremely low salinity Baltic Sea environment.

Adaptation, Biological↗
PubMed1990

Interaction of immunoactive monokines (interleukin 1 and tumor necrosis factor) in the bivalve mollusc Mytilus edulis.

Mytilus edulis has been the subject of recent studies to determine whether the relationship between the immune and neuroendocrine systems seen in vertebrates also exists in invertebrates. The effects of mammalian monokines were studied in Mytilus immunocytes previously shown to produce and react to opioid peptides. These invertebrate cells respond to interleukin 1 (IL-1) and tumor necrosis factor (TNF), both in vitro and in vivo, in a manner similar to that of human granulocytes. As in the mammalian monokine network, the effect of IL-1 on the immunocytes is brought about, at least in part, by its stimulatory effect on the formation of TNF. In addition, the presence of immunoreactive IL-1 and TNF in Mytilus hemolymph was demonstrated.

Animals↗
PubMed1990

A neuroimmunoregulatory-like mechanism responding to stress in the marine bivalve Mytilus edulis.

Mytilus edulis has been the subject of recent studies to determine whether the relationship between the immune and nervous systems seen in vertebrates also exists in invertebrates. In the present study the effects of experimentally induced "stressful" stimuli on immunoactive hemocytes were studied in this mollusc. This subpopulation of invertebrate blood cells, resembling vertebrate granulocytes, has been previously shown to produce and react to opioid peptides. Their activation, like that of vertebrate immunocytes, expresses itself in distinctive conformational changes preceding cellular mobilization. The cellular response to "stress" observed is the same as that to the administration of exogenous mammalian opioid peptides. This strongly suggests that under the conditions of stressful stimuli, the immune/defense system can be altered by endogenous neuropeptides. The involvement of opioids in neuroimmunoregulatory phenomena appears to have a long evolutionary history.

Animals↗
PubMed2003

Stress on stress response of wild mussels, Mytilus edulis and Mytilus trossulus, as an indicator of ecosystem health.

Mussels' health as indicated by the survival time of 50% of sampled animals (LT(50)) when maintained in air at 15 degrees C was examined at three sites in Halifax Harbour with expected differing levels of contamination. Condition and gonad indices, lipid content and the body burden of polycyclic aromatic compounds (PACs) were compared with this stress response in 60 groups of mussels covering two species. At each sampling time, the bioaccumulation of PACs, lipid content and condition indices were higher within Mytilus edulis and Mytilus trossulus displaying shorter survival than at the other sites. M. edulis was generally more tolerant than M. trossulus (for n=11, LT(50) of 9.3 and 7.9 days), with indications of shorter and later gonad development in M. trossulus. Minimum and maximum tolerance was apparent in June and October (LT(50) spanning 3-14 days), respectively. Our results indicate that the stress on stress response provides a simple and sensitive indicator of environmental health, which could be integrated with mussel watch studies.

Animals↗
PubMed2002

A molecular, morphometric and mechanical comparison of the structural elements of byssus from Mytilus edulis and Mytilus galloprovincialis.

Marine mussels are renowned for their ability to produce an extra-organismic tendon-like structure that can withstand the wave forces associated with the intertidal habitat. Initial characterization of byssal properties has focused on Mytilus edulis, with few detailed comparisons with other mussels. M. galloprovincialis, a closely related species, provides an opportunity for a thorough comparison. Three full-length cDNA clones encoding the byssal collagens, precollagen D (preCol-D), preCol-NG and preCol-P, were isolated from M. galloprovincialis. Comparisons with M. edulis preCol-D, preCol-NG and preCol-P reveal a 91.3 %, 88.6 % and 90.1 % identity with the cDNA and an 89.0 %, 88.1 % and 89.0 % identity with the deduced protein sequences, respectively. Key elements are maintained between the species: in particular, modeled bends in the collagen helix due to breaks in the Gly-X-Y pattern and the location of cysteine and putative 3,4-dihydroxyphenylalanine (DOPA) residues. A potentially important difference between the two is that, in all cases, M. galloprovincialis byssal collagens contain additional histidine residues in their flanking domains. The significance of this may lie in the ability of M. galloprovincialis to utilize more metal chelate cross-links, which have been implicated in byssal thread stability. M. edulis threads are typically twice the length and diameter of M. galloprovincialis threads and appear to contain nearly 10 % more collagen. These differences are maintained even when the different thread portions are compared. Despite differences in a number of parameters, most notably that whole M. galloprovincialis threads are stiffer, threads whether whole or separated into proximal and distal portions, have similar mechanical behaviors. It is apparent from this comparison that M. galloprovincialis and M. edulis are seemingly interchangeable models for byssal research.

Adaptation, Physiological↗
PubMed2003

Assessing pollution in coastal ecosystems: a preliminary survey using the micronucleus test in the mussel Mytilus edulis.

Mussels Mytilus edulis were sampled at increasing distances from urban effluents in two very different locations, Gijon (northern Spain, Europe, 43 degrees N) and Puerto Madryn (Argentina, South America, 43 degrees S), and from an industry effluent in Puerto Madryn. The micronucleus test was performed on branchial cells. For the three situations, a statistically significant negative association was found between the distance of sampling site from the effluent and the mean number of micronuclei per 1000 cell counts, in a range of distances as short as 300m. The micronucleus test in Mytilidae, here revealed to be sensitive enough to monitor urban pollution, is proposed for routine surveys of pollution as a bioindicator of choice for coastal ecosystems.

Animals↗
PubMed1999

Uptake of arsenic-betaines by the mussel Mytilus edulis.

Mussels (Mytilus edulis) were exposed to trimethyl(carboxymethyl)arsonium bromide (arsenobetaine, C-1 betaine), trimethyl(2-carboxyethyl)arsonium bromide (C-2 betaine), or trimethyl(3-carboxypropyl)arsonium bromide (C-3 betaine). Arsenic was accumulated by the mussels in all cases but the efficiency of uptake decreased with the number of methylene units in the carboxyalkyl group. Arsenobetaine (C-1 betaine) was the most readily accumulated, followed by the C-2 betaine (70% as efficient as arsenobetaine) and the C-3 betaine (approximately 7%). Chromatographic analysis (HPLC-ICPMS) of extracts of the mussels demonstrated that the arsenic compounds were accumulated unchanged. A 46-day depuration period which followed exposure did not significantly reduce the arsenic concentration in any of the three groups. Comparison with previous data on accumulation of arsenic compounds by M. edulis indicates that uptake may be influenced by the presence of a quaternary arsonium group and the zwitterionic nature of the arsenic-betaines.

Animals↗
PubMed2004

Differential segregation patterns of sperm mitochondria in embryos of the blue mussel (Mytilus edulis).

In Mytilus, females carry predominantly maternal mitochondrial DNA (mtDNA) but males carry maternal mtDNA in their somatic tissues and paternal mtDNA in their gonads. This phenomenon, known as doubly uniparental inheritance (DUI) of mtDNA, presents a major departure from the uniparental transmission of organelle genomes. Eggs of Mytilus edulis from females that produce exclusively daughters and from females that produce mostly sons were fertilized with sperm stained with MitoTracker Green FM, allowing observation of sperm mitochondria in the embryo by epifluorescent and confocal microscopy. In embryos from females that produce only daughters, sperm mitochondria are randomly dispersed among blastomeres. In embryos from females that produce mostly sons, sperm mitochondria tend to aggregate and end up in one blastomere in the two- and four-cell stages. We postulate that the aggregate eventually ends up in the first germ cells, thus accounting for the presence of paternal mtDNA in the male gonad. This is the first evidence for different behaviors of sperm mitochondria in developing embryos that may explain the tight linkage between gender and inheritance of paternal mitochondrial DNA in species with DUI.

Animals↗
PubMed1979

5-HT induced accumulation of 3',5'-AMP and the phosphorylation of paramyosin in the ABRM of Mytilus edulis.

In Mytilus edulis 5-Ht induced relaxation of a muscle in catch is preceded by an increase in 3',5'-AMP content. In vitro two proteins of the contractile apparatus are phosphorylated by 3',5'-AMP dependent protein kinases. The 295000 dalton protein cannot be identified, the other one is paramyosin. Phosphorylated paramyosin inhibits actomyosin ATPase of smooth mollusc muscles at low and high Ca++ concentrations.

Actomyosin↗
PubMed1978

[Innervation of the anterior byssus retractor muscle (ABRM) in Mytilus edulis L. and in Mytilus galloprovincialis Lmk. V. Cytochemical localization of cholinesterase activities (author's transl)].

Specific and non specific cholinesterase activities were demonstrated in the ABRM of Mytilus edulis L. and Mytilus galloprovincialis L. by means of different techniques. The results were found identical for both species: neuromuscular junctions "en grappe"-type scarely distributed within the ABRM, contain AChE. According to the histochemical inhibition tests, (a) the eserine inhibits AChE activity of the ABRM with a level of 5-10(-5) M or higher, (b) the ChE non specific activities are inhibited by iso-OMPA level between 5.10(-5) to 10(-4) M. The histo- and cytochemical observations were completed by showing the existence of neuromuscular junctions containing small clear vesicles: they probably are the morphological support for ACh presence. Moreover, specific and non specific ChE activities were localized in the glio-interstitial cells. AChE precipitates were developed along the ABRM sarcolemma, some muscle mitochondria and in the intercellular spaces remain enigmatic.

Animals↗
PubMed2003

Microcosm tributyltin bioaccumulation and multibiomarker assessment in the blue mussel Mytilus edulis.

Blue mussels, Mytilus edulis, were exposed to two different concentrations of tributyltin (TBT) in seawater, 1,000 ng Sn/L (C1 experiment) and 10 ng Sn/L (C2 experiment), for 4 d, in order to evaluate the bioaccumulation of TBT by mussels Mytilus edulis in microcosms and to test the ability of a multimarkers analysis to determine the effects of TBT on the biochemical parameters in mussels. Tissue burdens of Mytilus edulis were 204 +/- 7 and 2,120 +/- 4 ng Sn/g TBT after the 4-d tests for the C2 and C1 experiments, respectively. Analyses of dissected organs and/or tissues demonstrated that TBT accumulated to the greatest extent in gills in the C1 experiment and in the digestive gland in the C2 experiment. Bioconcentration factors (BCFs) were 12,100 +/- 300 and 2,000 +/- 10 for mussels exposed in the C2 and C1 experiments, respectively. The four biomarkers used in this work were acetylcholinesterase (AChE), glutathione S-transferase (GST), catalase (CAT) activities, and thiobarbituric acid-reactive substances (TBARS) contents. No significant changes were observed in the measured enzyme activities or in TBARS concentration after the 4-d TBT exposure.

Acetylcholinesterase↗
PubMed1979

Histochemical detection of monoamine oxidase activity in smooth muscle and epithelial tissues of Mytilus edulis L. and Mytilus galloprovincialis Lmk.

Monoamine oxidase (MAO) activity was detected in the glio-interstitial tissue of the anterior byssus retractor muscle (ABRM) of Mytilus by the use of either dopamine or 5-HT as substrate and nitro blue tetrazolium salt as an electron receptor. Both substrates gave superimposable patterns. However, dopamine reactivity was very weak. Discrete but clear MAO activity was detected in the periphery of the smooth muscle cell, i.e., at the level of the peripherally localized mitochondria. The presence of MAO in the epithelium of the buccal palps was also demonstrated. These histochemical observations can be correlated with certain ultrastructural aspects, in particular the presence electron dense organelles profiles in glio-interstitial cells. This MAO activity is discussed in relationship with the high 5-HT content of ABRM and the control of its relaxation. Pigment formation and/or collagen tanning are discussed in terms of a possible relationship with inactivation of biogenic amines. These results complement previous data concerning the glio-interstitial tissue found in close association with muscle and nerve structures.

Animals↗
PubMed2003

The influence of temperature and dose on antibacterial peptide response against lipopolysaccharide in the blue mussel, Mytilus edulis.

Blue mussels (Mytilus edulis) were inoculated with two different doses of lipopolysaccharides (LPS) or phosphate-saline (PS) buffer under different temperature conditions (6 and 20 degrees C). The activity of the antibacterial peptide fraction, purified through reverse phase chromatography from mussel haemolyph, was compared at different time intervals after the inoculation. The activity was determined as the minimal peptide concentration that inhibited growth of the Gram-negative bacteria Escherichia coli D21, by using radial diffusion assay. The antibacterial activity for mussels inoculated with LPS changed over time, both at 6 and 20 degrees C, but those inoculated with PS-buffer did not. The response was enhanced within a time course of 3h. The higher temperature did increase the inhibitory activity and made the mussel respond at an earlier stage, in comparison to that at 6 degrees C. At 20 degrees C, mussels inoculated with 10 microg of LPS responded faster than those inoculated with 0.1 microg of LPS. In addition, cytotoxic effects of LPS on mussel haemocytes were investigated in vitro, using a colorimetric assay. The survival index (SI%) for haemocytes decreased with 76% at 6 degrees C but increased with 100% at 20 degrees C, irrespective of the dose of LPS. This indicated that LPS did not influence the viability of the haemocytes but the high temperature increased their metabolic state. Likely, antibacterial response was provoked by LPS in a dose-dependent manner and favoured by higher metabolic state of the haemocytes, elicited at higher temperature. These results provide important considerations for variability in the internal defence of mussels and consequently, also the retention of viable human pathogens in mussels.

Animals↗
PubMed1981

Decrease in the number of high-affinity opiate binding sites during the aging process in Mytilus edulis (Bivalvia).

As Mytilus edulis (Bivalvia) ages, the number of stereospecific opiate binding sites in the visceral ganglia significantly decreases. The number of high-affinity etorphine sites decreased by 30%; the number of naloxone sites decreased by 23%. The affinity of the ligands did not vary with age. In addition, the augmentation by opioids of dopamine levels in the visceral ganglia was less in older animals and was accompanied by a reduced sensitivity of the ganglia to etorphine and DAMA (D-Ala2,Met5-enkephalin-amide).

Aging↗
PubMed2005

Comparison of ELISA and LC-MS analyses for yessotoxins in blue mussels (Mytilus edulis).

Blue mussels (Mytilus edulis) collected from Flødevigen Bay, Norway, in 2001 and 2002 were analysed for yessotoxins (YTXs) by ELISA and yessotoxin (YTX), 45-hydroxyYTX, and carboxyYTX by LC-MS. Results from the two methods were compared to evaluate the ELISA. The response in the ELISA was 3-13 times higher than LC-MS, probably due to the antibodies binding to other YTX analogues not included in the LC-MS analysis. Nevertheless, the correlation between ELISA and LC-MS was good, with r2 values> or =0.8. The results indicate that the ELISA is a reliable method for estimating the total level of YTXs in mussels, and are consistent with extensive metabolism of algal YTXs in mussels. YTX was a minor component in the blue mussels at all times compared to 45-hydroxyYTX and especially carboxyYTX, except when the P. reticulatum bloom occurred. The results also indicate the presence of significant amounts of YTX analogues in addition to those measured by LC-MS. All samples below 4 mg/kg by ELISA were below the current EU regulatory limit of 1 mg/kg by LC-MS. Therefore, we propose using ELISA as a screening tool with a cut-off limit at 4 mg/kg for negative samples, whereas samples above this limit would be reanalyzed by LC-MS.

Animals↗
PubMed2001

Effects of acid mine drainage from an abandoned copper mine, Britannia Mines, Howe Sound, British Columbia, Canada, on transplanted blue mussels (Mytilus edulis).

Juvenile mussels (Mytilus edulis) were transplanted to Howe Sound, British Columbia, Canada, along an apparent pollution gradient of acid mine drainage (AMD) from an abandoned copper (Cu) mine. Cages containing 75 mussels each were placed at a total of 15 stations and were exposed to concentrations of dissolved Cu in surface waters ranging from 5 to 1009 micrograms/l for a period of 41 days. Mussels located at stations closer to the source of AMD at the mouth of Britannia Creek bioaccumulated higher concentrations of Cu and zinc (Zn) in their tissues. Mussel growth was adversely affected by Cu tissue concentrations above 20 micrograms/g dry wt., while declines in survival and condition index occurred in mussels that bioaccumulated greater than 40 micrograms/g dry wt. Cu. Tissue Zn concentrations (117-192 micrograms/g dry wt.) were likely not high enough to have a direct impact on mussel health. Reduced survival of transplanted mussels was supported by an absence of natural mussels in contaminated areas. Phytoplankton was also severely reduced in areas contaminated by mine waters. Based on the weight of evidence, AMD from the Britannia mine had a deleterious impact on mussel survival in a zone extending at least 2.1 km to the north and 1.7 km to the south of Britannia Creek on the east shore of Howe Sound.

Animals↗