Dosinia Exoleta Research Articles

Studi Komparasi Kuantitas Bivalvia pada Zona Intertidal di Pantai Ntana Kabupaten Bima sebagai Upaya Penyusunan Brosur Konservasi

Bivalves belong to the Phylum mollusca. Bivalve are found and live in the Intertidal area. Ntana Beach is the easiest area and has the most interaction with human activities, because this area is a transitional area between aquatic ecosystems and land ecosystems. This study aims to: 1) identify the types of bivalves that make up the Intertidal zone on the Ntana coast, Bima Regency; 2) analyzing the abundance, diversity index, and evenness of Bivalvia in the Intertidal zone on the Ntana coast, Bima Regency; 3) describe the population of bivalve species that dominate the Intertidal zone on the Ntana coast, Bima Regency; 4) analyzing the abundance of bivalves in the sandy, muddy and rocky substrate areas on the Ntana beach, Bima Regency; 5) analyzing the diversity of bivalve species in the area of ​​sandy substrate, muddy substrate, and coral substrate on the Ntana beach, Bima Regency; 6) knowing the differences in the dominance of Bivalvia in the sandy, muddy and rocky substrate areas on the Ntana beach, Bima Regency; and 7) to develop research results on a comparative study of the quantity of bivalves in the intertidal zone on the Ntana coast, Bima district as an effort to prepare a conservation brochure. This type of research is descriptive comparative. Sampling used a 1x1 M plot. The results showed that as many as 540 individual bivalves consisting of 15 species were found on the Ntana beach, Bima district. 15 species of bivalves found include Anadara antiquata, Anadara granosa, Anadara brasilliana, Panopea generosa, Fausta pultenei, Dosina crebra, Eurytellina alternate, Dosina discus, Nactula acuta, Gafrarium divaricatum, Dosinia exoleta, Caestoderma edule, Gafrarium disparm, Cyclocardia ventricosa, and Crassostrea gigas. The abundance on sandy and silty substrates is categorized as moderate, whereas on coral substrates it is categorized as low. Species diversity on rocky substrates is less, whereas on muddy and sandy substrates each has a fairly high level of species diversity. The evenness value on sandy and muddy substrates is close to zero (0), so that the evenness of Bivalvia species on both substrates is not evenly distributed. There are no species that dominate other species because D <0.5. The average value of the brochure validation test is 75.4%, with this result, the brochures that have been compiled are in the good category and do not need to be revised.

Terminal-Repeat Retrotransposons in Miniature (TRIMs) in bivalves

Terminal repeat retrotransposons in miniature (TRIMs) are small non-autonomous LTR retrotransposons consisting of two terminal direct repeats surrounding a short internal domain. The detection and characterization of these elements has been mainly limited to plants. Here we present the first finding of a TRIM element in bivalves, and among the first known in the kingdom Animalia. Class Bivalvia has high ecological and commercial importance in marine ecosystems and aquaculture, and, in recent years, an increasing number of genomic studies has addressed to these organisms. We have identified biv-TRIM in several bivalve species: Donax trunculus, Ruditapes decussatus, R. philippinarum, Venerupis corrugata, Polititapes rhomboides, Venus verrucosa, Dosinia exoleta, Glycymeris glycymeris, Cerastoderma edule, Magallana gigas, Mytilus galloprovincialis. biv-TRIM has several characteristics typical for this group of elements, exhibiting different variations. In addition to canonically structured elements, solo-TDRs and tandem repeats were detected. The presence of this element in the genome of each species is <1%. The phylogenetic analysis showed a complex clustering pattern of biv-TRIM elements, and indicates the involvement of horizontal transfer in the spreading of this element.

In vivo oral bioavailability of Pb sequestered in metal rich granules in bivalves

The present study was designed to evaluate in vivo the oral bioavailability of lead (Pb) present in the marine bivalve Dosinia exoleta. This infaunal clam, despite inhabiting in clean areas, presents Pb concentrations that are over the 1.5 mg kg−1 wet weight limit for human consumption set by the European Commission. However, Pb is accumulated in this clam in the form of metal rich granules, and it has been shown to be unavailable for trophic transfer to a marine decapod, so it was hypothesised that it might be unavailable for human consumers as well. Twelve Sprague Dawley rats were fed during 14 days with a diet including control mussels (Mytilus galloprovincialis), D. exoleta, or mussels enriched in Pb to the same levels as those found in D. exoleta. Pb accumulation in different rat tissues (blood, bone, kidneys and liver) was analysed. It was observed that Pb assimilation from D. exoleta was about half of Pb assimilation from M. galloprovincialis, and absolute bioavailabilities were around 2% for M. galloprovincialis and 1% for D. exoleta. These results suggest that it might be possible to increase the limit for human consumption for this bivalve to 3 mg kg−1 wet weight without representing an increase in the risk for consumers.

Subcellular distribution and trophic transfer of Pb from bivalves to the common prawn Palaemon serratus

The edible clam Dosinia exoleta has been reported to accumulate high contents of lead (Pb) in soft tissues disregarding the levels of Pb in the environment. This is due to the retention of Pb in the form of metal rich granules (MRG) in their kidneys throughout the mollusc lifespan. The potential for trophic transfer of Pb in this form to predators is expected to be low, since metals in the form of MRG are generally supposed to be trophically unavailable, but this assumption is based on studies with other metals (Ag, Cd, Cu or Zn) and has not been demonstrated with Pb until now. This study was designed to test if the Pb present in D. exoleta in the form of MRG is available to a decapod consumer, the common prawn Palaemon serratus, in comparison with a mussel diet showing a different subcellular distribution of Pb. As hypothesised, despite the high Pb concentrations (15µgg−1ww) offered to the prawns as D. exoleta tissues, Pb was almost completely unavailable for trophic transfer, and the prawns fed with this diet during 28 days showed the same Pb accumulation as prawns fed with a control diet with a much lower Pb concentration. On the contrary, individuals fed with mussel tissues containing the same Pb concentrations as the diet based on D. exoleta tissues showed 10 times higher Pb bioaccumulation, corresponding to a trophic transfer factor of 1.1%. Subcellular fractionation experiments revealed that the fraction of Pb in the form of MRG was much lower for the mussel, confirming, as observed for other metals, that MRG-associated Pb is not available for trophic transfer to decapod crustaceans.

Evolutionary dynamics of rDNA clusters in chromosomes of five clam species belonging to the family Veneridae (Mollusca, Bivalvia).

The chromosomal changes accompanying bivalve evolution are an area about which few reports have been published. To improve our understanding on chromosome evolution in Veneridae, ribosomal RNA gene clusters were mapped by fluorescent in situ hybridization (FISH) to chromosomes of five species of venerid clams (Venerupis corrugata, Ruditapes philippinarum, Ruditapes decussatus, Dosinia exoleta, and Venus verrucosa). The results were anchored to the most comprehensive molecular phylogenetic tree currently available for Veneridae. While a single major rDNA cluster was found in each of the five species, the number of 5S rDNA clusters showed high interspecies variation. Major rDNA was either subterminal to the short arms or intercalary to the long arms of metacentric or submetacentric chromosomes, whereas minor rDNA signals showed higher variability. Major and minor rDNAs map to different chromosome pairs in all species, but in R. decussatus one of the minor rDNA gene clusters and the major rDNA cluster were located in the same position on a single chromosome pair. This interspersion of both sequences was confirmed by fiber FISH. Telomeric signals appeared at both ends of every chromosome in all species. FISH mapping data are discussed in relation to the molecular phylogenetic trees currently available for Veneridae.

Lead accumulation in extracellular granules detected in the kidney of the bivalveDosinia exoleta

Populations of the marine molluscan bivalve Dosinia exoleta in Galicia (northwest Spain) present lead (Pb) concentrations above the limit for human consumption. Accordingly, its collection for human consumption was forbidden since 2008. The high bioaccumulation of Pb in this species is surprising given that Pb concentrations are not very high in its environment and that other bivalve infaunal species inhabiting the same areas do not show such high Pb contents. This study reports the discovery and description of extracellular granules present in the kidney tubule lumina of this species. Large granules (20−200 µm) mainly composed of calcium phosphate represent between 50% and 75% of the dry weight of the kidneys. Metal analysis revealed that from 78 to 98% of the Pb body burden was present in the kidney, and from 87% to 92% of this Pb within the kidney was contained in metal rich granules. Most of the zinc in these bivalves was also found to be associated with these kidney granules, while other metals, such as copper and cadmium, were associated with other kidney fractions. This study confirms that the high Pb concentrations observed in D. exoleta, and the relationship of Pb concentration with individual size, are due to the inclusion of Pb in kidney granules that accumulate in the kidney lumen over the course of the bivalve's life.

Norovirus, hepatitis A virus and enterovirus presence in shellfish from high quality harvesting areas in Portugal

This is the first report on the screening of shellfish from Portugal for the presence of human enteropathogenic viruses. Approximately 2000 shellfish ( Curbicula fluminea, Ruditapes decussatus, Tellina crassa, Spisula solida, Dosinia exoleta, Ensis spp., Mytilus spp., Ostrea edulis and Cerastoderma edule), organized in 49 batches, were collected between March 2008 and February 2009. They were tested for norovirus (NoV), hepatitis A virus (HAV) and enterovirus (EV) by RT-PCR followed by nucleotide sequencing. Bacterial contamination was also evaluated by Escherichia coli counts. Viral contamination was detected throughout the year in all shellfish species and in all collection areas, independently of their harvesting areas classification. Overall, 67% of all analyzed batches were contaminated by at least one of the studied viruses while the simultaneous presence of two and three viruses was detected in 22% and 6% batches, respectively. Of the three viruses, NoV was detected in 37% of the batches, followed by EV in 35%, and HAV in 33%. Nucleotide sequencing of the NoV and HAV RT-PCR products demonstrated that all strains belonged to NoV genotype GII.4 and HAV subgenotype 1B. The presence of NoV and HAV in shellfish from “A class” harvesting areas of Portugal can represent a potential health risk.

Lead concentrations and size dependence of lead accumulation in the clamDosinia exoletafrom shellfish extraction areas in the Galician Rías (NW Spain)

To protect public health, the European Commission established maximum levels of certain contaminants permitted in foodstuffs. The maximum amount of lead allowed in bivalve mollusc is 1.5 µg g−1 wet weight. In the Galician Rías, which are important areas of shellfish production in Spain, high levels of lead have been detected in the commercial bivalve Dosinia exoleta (Veneridae). Given the environmental and socio-economical problems this could represent, Pb concentration was tested in D. exoleta from two Rías, and the relation of lead accumulation with body size studied in detail. Implications for fisheries management are also discussed in this paper. Results showed a strong dependence of Pb accumulation on body size, with lead concentrations increasing exponentially with shell length. Larger animals presented a 5-fold increase in lead concentrations above the maximum permitted level. The size limit (length beyond which D. exoleta should not be extracted for commercial purposes) was initially established at 40 mm; but a more comprehensive geographical study of Pb concentrations in individuals from 35 to 40 mm long revealed that this size limit was not protective enough, and 35 mm is proposed as a safer limit.

Surface spreading of synaptonemal complexes in the clam Dosinia exoleta (Mollusca, Bivalvia)

There are only a few reports on the chromosomal location of DNA sequences in bivalve species, none of them using meiotic chromosomes. Mitotic chromosomes of the clam Dosinia exoleta were analysed by means of Giemsa, silver and fluorochrome staining and fluorescent in situ hybridization (FISH) with 18S + 28S rDNA and telomeric probes. A technique for surface spreading of synaptonemal complexes (SCs) of Dosinia exoleta was developed for the first time in a bivalve species. Silver and DAPI/PI staining and SC-FISH were also applied to the study of the meiotic chromosomes of this clam. The diploid chromosome number in this species is 38 and the karyotype is composed of 11 pairs of metacentric and eight pairs of submetacentric chromosomes. 18S + 28S rDNA clusters map to the subtelomeric region of the short arm of one metacentric chromosome pair whereas telomeric signals appear at both ends of every chromosome.

Molecular characterization of the bivalves Mya arenaria, Mya truncata and Hiatella arctica.

Well-preserved bivalve adult forms are generally easily recognizable, but planktonic or damaged samples (crushed organisms in sediments or digested bivalves in predator guts) are far more difficult to identify. 3,18 Molecular approaches may overcome some of these problems. In this paper, we report new PCR-based tests for the identification of three bivalve species within the Myoidae order: Mya arenaria, Mya truncata, and Hiatella arctica based on the internal transcribed spacer (ITS-1) ribosomal DNA region located between the 18S and 5.8S ribosomal RNA genes. Marine bivalves were collected between 1998 and 2000 on the East and West coasts of Scotland, and identified by morphology. Individuals from the following species, which are taxonomically close and commonly found on the coasts of UK, were used in this study: Cerastoderma edule (Linnaeus, 1758), Dosinia exoleta (Linnaeus, 1758), Hiatella arctica (Linnaeus, 1767), Mya arenaria Linnaeus, 1758, Mya truncata Linnaeus, 1758, Mytilus edulis (Linnaeus, 1758), and Venerupis senegalensis (Gmelin, 1791). DNA was extracted from whole Hiatella arctica specimens, whereas for bigger bivalves, such as the Mya species, Cerastoderma edule, Dosinia exoleta, and Venerupis senegalensis, we have used only some parts of the animal (foot or gills). Tissues were digested and DNA was extracted by using a DNeasy Tissue kit (QIAGEN Ltd, Crawley, UK) using the protocol recommended by the manufacturer. Purified DNA samples were stored at ‐ 20°C until needed. A PCR reaction (using previously published ITS2 and ITS5 primers 20 ) was performed on different bivalve species. Unfortunately, bands of 550 bp were amplified from DNA extracted for all the species tested in this study even when the Tm was raised to 56°C instead of 48°C, as recommended 20 (data not shown) and, therefore, could not be used to specifically identify Mya species according to the size of the amplified DNA. Since only a few sequences have been published for these organisms and none are so far in the GenBank for Mya species, we sequenced amplified products from two different Mya species and representatives of Hiatella arctica. DNA fragments were excised from ethidium bromidestained agarose gels using the QIAquick gel extraction kit (QIAGEN Ltd, Crawley, UK) and were sequenced on an ABI 310 DNA sequencer from Applied Biosystems (Warrington, UK) using the Big Dye Terminator kit. Sequences were aligned using the MultiAlin software. 19 Sequences can be retrieved on