Crassostrea Research Articles

Scientific research on exotic and native mollusk farming in Mexico ac-cording to SCOPUS

Objective: The objective of this study was to evaluate scientific productivity in this field through the database deposited in SCOPUS for Mexico. Design/methodology/approach: The genera and species of mollusks, currently cultivated or with cultivation potential, marine and freshwater, native and exotic, that have been studied are identified. The SCOPUS search was performed using the scientific name of the corresponding species in the publication title. The number of publications, the institutions that generated them, the SCOPUS theme of the study and the research funders were obtained. Results: There is an uneven growth, with a greater focus on abalone and octopus, while the genus Crassostrea, particularly the species C. gigas, leads the production of scientific articles. CIBNOR and IPN are the most relevant institutions in scientific production in molluscan aquaculture in Mexico. Limitations on study/implications: Despite the interest, advances in areas such as physiology, nutrition and reproduction have not been translated into efficient culture technologies in most cases. Findings/conclusions: These findings highlight the need to promote research and technological development in the aquaculture of native mollusks in Mexico, as well as to promote collaboration between academic research institutions and the production sector to overcome the challenges in the culture of these species

Oyster shell element composition as a proxy for environmental studies

The use of mollusks' shell as a proxy for long-term trend prediction in the variability of coastal zones has been used as an attempt to understand the consequences that environmental changes may cause to the functioning of coastal ecosystems. This study exploited the elemental concentration, elemental ratios and mineralogy of oyster shells of the genus Crassostrea to infer spatial variations in the environment of the animal's growth. Modern oyster shell samples of the Crassostrea brasiliana and Crassostrea mangle species were analyzed by neutron activation analysis, X-ray diffraction, X-ray fluorescence and Graphite Furnace Atomic Absorption Spectrometry. Data normalization by the enrichment factor relative to lanthanum (La), considered as a conservative element in seawater, and statistical multivariate analyses indicate that the elemental composition and trace element ratios differ when comparing oyster shells from different regions. The results showed that the performed analyses may be useful for the characterization of the environment in which oysters grow.

Borers and epizoans on oyster shells from the upper Tortonian, Lower Chelif Basin, NW Algeria

The three oyster lenses of the upper Tortonian of Djebel Touaka site which are described herein contain three species, Crassostrea gryphoides (Schlotheim), Ostrea lamellosa (Brocchi) and Hyotissa squarrosa (De Serre). The density of shell packing between the lenses is dissimilar. Most of the specimens are disarticulated and poorly fragmented; they exhibit a random distribution and orientation, without any distinct sorting. Bioerosion and encrustation are featured on both surfaces of left and right valves. The identified ichnogenera are Entobia (Bronn), Gastrochaenolites (Leymarie, 1842), Caulostrepsis (Clarke, 1908), Trypanites (Mägdefrau, 1932) and Maeandropolydora (Voigt, 1965). Encrusters are scared, represented by juvenile oysters/other bivalves, bryozoans and barnacles. The coexistence of borings on both sides of valves means that they probably occur not only while alive, but they keep happening after death. The oyster beds were deposited in a foreshore to shoreface environment, from the combined action of wave currents and sedimentation rate.

A historical and integrative taxonomic account of mangrove oyster species native to the Atlantic American coast: A re-evaluation of Brazilian Crassostrea species

The identification of native mangrove oyster species of the genus Crassostrea in Brazil is a recurring issue for specialists. Studies have recognized the presence of two species in the littoral zone: C. rhizophorae and C. gasar. However, other names may be used, such as C. mangle for C. rhizophorae and C. brasiliana or C. tulipa for C.gasar. As in most oyster taxonomic studies, their identification requires genetic evaluation for the precise determination of taxa. Moreover, previous revisions have proposed some morphological traits by which each species could be precisely identified, leading to a series of debates about the best model for species identity. The aim of this study was to apply an integrative taxonomic approach to native Crassostrea mangrove oyster species on the Brazilian coast to assert the correct species names, delimitations, and concise descriptions. Molecular tracing of cultivated specimens, along with wild specimens of Crassostrea collected from the Brazilian coast, was used to confirm the morphological identity of the taxa. The wild specimens were tentatively identified as either C. gasar or C. rhizophorae based on previous morphological revisions. PCR-RFLP and DNA analyses of the mitochondrial 16S gene mitochondrial rDNA from wild specimens were used to confirm taxa and re-evaluate morphological boundaries and descriptions of the species. We confirmed two patterns in the RFLP and sequence analyses: C. gasar and C. rhizophorae. Conchological and anatomical evaluations of 1006 identified Crassostrea specimens confirmed the inherent polymorphism between the native species, preventing reliable identification of the species by morphology alone. A clear exception, however, is found for specimens whose shell height is greater than 110 mm with internal view of white-colored valves and without an umbonal cavity, fitting the description of C. paraibanensis, which belongs to C. gasar. C. brasiliana and C. mangle are synonyms of C. gasar and C. rhizophorae, respectively. C. tulipa represents a species disconnected from any described mangrove oyster species from Atlantic seas. Conchological and anatomical descriptions of both species were improved to include the variability encountered.

Detecção de Cryptosporidium sp. em ostras de cultivo e estoque natural no estado do Maranhão, Brasil

ABSTRACT: This study detected Cryptosporidium spp. in cultivated oysters and the natural oyster stock of the state of Maranhão and determine the elective tissue(s) to examine this protozoan. For this purpose, 200 cultivated oysters were purchased from the municipality of Raposa and another 100 from Paço do Lumiar. Additionally, 100 oysters were extracted from the natural stock of the municipality of Primeira Cruz, thus making up a total of 400 oysters. They were grouped into 80 pools consisting of 5 oysters each. From each pool, the gills and visceral mass were removed to obtain 160 pools, 80 pools for the gill group and another 80 for the visceral mass group. Then, DNA was extracted from each pool using a commercial kit with modifications. Subsequently, the protozoan DNA was detected using nested polymerase chain reaction. With this technique, the DNA of the protozoan under investigation was detected in 2.5% (n = 2/80) of the pools containing gills, with 1.25% of the pools (n = 1/80) belonging to the cultivation group of oysters and the other 1.25% (n = 1/80) to the natural stock. With the results obtained in this study, it was concluded that the analyzed oysters of the genus Crassostrea, from cultivation and natural stock groups, found in the state of Maranhão, were contaminated by Cryptosporidium spp. and may become potential sources of infection in humans and other animals. In addition, the gills are the elective tissue for the study of Cryptosporidium spp. in oysters.

Biology and ecological functional of Genus Crassostrea (Bivalvia: Ostreidae): a review

The genus Crassostrea has an important role for community life in coastal and mangrove ecosystems. In this article, we try to review in detail the ecology, biology, and ecological functions of Crassostrea spp. Furthermore, we also review about 25 species of Crasostrea that exist in the world and also have a high level of adaptation. Based on ecological functional, Crassostrea acts as an efficient engineer of ecosystems, where in forming ecosystems, in nutrient cycling, in reducing anthropogenic eutrophication, shelter area, breeding grounds, and as a link between benthic-pelagic. In addition, high Crassostrea communities can form reefs and serve as ecologically important for diverse species.Keywords:Marine BivalvesCommunity Anthropogenic EcosystemsFunctional

Molecular and morphological evidence for the presence of a non-native oyster (genus Crassostrea) in the Persian Gulf

Oysters are widespread throughout the intertidal regions, and accurate identification and monitoring of their ecological status are still difficult due to their high level of plasticity. Anthropogenic activities facilitate oyster dispersal to new habitats through the shipping and elimination of existing barriers. In this study, a combination of morphological and molecular techniques was used to clarify the identity of an oyster species occurring along the Iranian coast of the Persian Gulf. Specimens were collected from the jetties of the ports and the rocky shores along the northern Persian Gulf. Oyster identification was carried out to the lowest possible taxonomic level based on shell morphology. The phylogenetic analysis was done using the cytochrome c oxidase subunit 1 (COI) fragments. Morphological results confirmed that studied samples belong to the genus Crassostrea and showed close to the Vietnamese (Crassostrea markushuberi) species. Molecular analysis reveals that species are a sister species to a clade containing Crassostrea zhanjiangensis and Crassostrea talonata. According to the relatively high genetic distances and lack of similarity in shell characteristics, the species is considered as distant sister species of C. zhanjiangensis and C. talonata. The results showed a non-native small size of oyster in the northern Persian Gulf, which might be a new species. The relative abundance of this species in the introduced location (Imam Khomeini port) may be linked to the high adaptation capability to the new environment.

Global controversy in oyster systematics and a newly described species from SE Asia (Bivalvia: Ostreidae: Crassostreinae)

The diversity of native oysters in many regions is overshadowed by the global dominance of a few economically important species. Here we describe the Muar Oyster, Crassostrea (Magallana) saidii sp. nov., first reported as an established local fishery renowned for exceptional and distinctive flavour over 160 years ago by British colonial officials in Malaysia, but as yet never formally named or described as a species. This new species has a subtle but clear morphological diagnosis dependent on three-dimensional characters, which has long been recognised by local fishers to differentiate the new species from co-occurring C. (M.) belcheri (G. B. Sowerby II, 1871). The Indo-Pacific clade Magallana Salvi & Mariottini, 2016 in Salvi and Mariottini 2017 is a phylogenetically distinct group that nonetheless cannot be morphologically separated from the broader genus Crassostrea Sacco, 1897. Fossils or species known only from shell specimens, though morphologically distinct species, cannot be classified as Magallana, Talonostrea Li & Qi, 1994, or Crassostrea s.s.; therefore, we revise these groups as sub-genera within Crassostrea. Our analysis of the COI barcoding fragment from previously published sequences of all available Magallana species found that gene is not sufficient to separate several economically important species, and revealed more than 5% of sequences in GenBank represent identification errors. The new species Crassostrea (Magallana) saidii sp. nov., which is genetically, morphologically, and gastronomically distinct, is known from only one population under potential threat from urbanisation. Many more global species of Magallana remain undescribed. The systematics of this group is critical to understand the diversity of global oysters, and to understand the sustainable use of species grown worldwide for centuries as our food.

Morphological and Mitochondrial DNA Analyses of Oysters in the Northern Bay of Bengal, Bangladesh

The geographic boundaries of many important habitat-building shallow estuarine oyster (Family Ostreidae) species are poorly understood, especially in subtropical and tropical waters. These keystone species often have extensive historical and extant ranges, in part because of their ability to adapt to diverse environmental conditions and the transfer and introduction of a few species worldwide for aquaculture production. In addition, oysters exhibit morphological plasticity additionally confounding species identification and taxonomy. Molecular techniques have led to significant improvements in oyster systematics and taxonomy but have not been applied to oysters from many tropical regions, including the coastal areas of the Indian Ocean such as Bangladesh. Because species' identification based on morphological traits alone, in this case primarily shell characteristics, were inadequate, phylogenetic analyses of mitochondrial cytochrome oxidase subunit I gene fragments was also done to confirm the identity of oyster specimens collected from Bangladesh coastal waters. Phylogenetic analyses of collected oyster samples confirmed the two monophyletic subclades of the Ostreidae family Crassostrea and Saccostrea, and five oyster lineages from the region of Bangladesh were identified: Crassostrea gryphoides, Crassostrea belcheri, Saccostrea cuccullata lineage B, S. cuccullata lineage F, and Saccostrea mordax. A new addition to the list of Crassostrea species, C. belcheri was found in Bangladesh, but C. belcheri, C. gryphoides, and S. cuccullata are considered “common” species in the neighboring states of India and Myanmar indicating a widespread distribution of these species along the entire coast of the Bay of Bengal. However, S. mordax, is a new record for the Bay of Bengal region including the coastal waters of Andaman and Nicobar Islands, and thus extends the geographical distribution of this species.

Anti-inflammatory Compounds from the Hydrolysate of Indian Marine Green Mussel (Perna viridis L)

Natural products offer a great hope in identifying bioactive compounds and their development into drugs to treat several diseases including inflammatory problems. Ocean has been considered as a rich source of such compounds with novel structures and important biological activities. Traditional medicine is widespread and natural compounds represent a large source of naturally occurring secondary metabolites that might lead to novel drugs. The ocean also offers the potential for producing metabolites, which may be different from the terrestrial organisms. Due to the complex nature and dynamic system in the ocean, the marine organisms have developed unique metabolic and physiologic capabilies that ensure their survival in extreme variations of pressure, salinity and temperature. Marine organisms, including mussel, have produced a variety of chemically interesting and biologically significant secondary metabolites. Some are expected to serve as lead compounds for drug development or pharmacological tools for basic life science studies. Marine animals can survive in an inimical environment surrounded by various pathogenic organisms, including human pathogens. They are also potential sources for bioactive compounds as observed in edible bivalves, such as Meretrix casta (Chemnitz), Polymesoda (Geloina) Polymesoda erosa (Solander), Perna viridis (Linnaeus), Crassostrea gryphoides (Schlothim), and Villorita cyprinoides (Grey). Recent studies conducted have shown that green mussels are an inexpensive source of protein for human consumption and possess some important complex potential bioactive compounds useful as medicines. Isolation of bioactive compounds like anti-inflammatory from marine sources has been receiving special attention among natural bioactive compounds because of their economic significance effectiveness and the increasing incidents of drug resistance lead to difficulties in the pharmacological field. The present study reviewed the anti-inflammatory compounds from the hydrolysate prepared from green mussel which will be identified and characterized for commercial use.

A diet rich in diatom improves the antibacterial capacity of Pacific oyster Crassostrea gigas by enhancing norepinephrine-regulated immunomodulation

Microalgae such as dinoflagellate and diatom are the major food source of bivalve species, and sufficient food intake contributes to the immunity and the growth of bivalves. In the present study, a monoamine oxidase gene (named as CgMAO), which is the rate-limiting enzyme of norepinephrine (NE) biosynthesis, was cloned from C. gigas. After the oysters were fed with a diet rich in diatom for 21 and 40 d, the NE contents in oyster serum, as well as the mRNA expression of CgMAO in oyster haemocytes, increased significantly compared with control group. Besides, the mRNA expression of cytokines CgTNF-1 and CgIL17-5 in haemocytes and the activities of immune-related enzymes (SOD and LYZ) in oyster serum also increased significantly after diatom feeding. These results collectively suggested that sufficient microalgae intake might significantly enhance the antibacterial capacity in oyster by prompting the biosynthesis of NE and triggering the subsequent antibacterial processes modulated by NE.

Miocene Rocks Around the Marádah Oasis, Central Sirt Basin, Libya: Facies Development and Implication on Stratigraphy

The Miocene rocks of the Marádah Formation have been stratigraphically investigated from four stratigraphical sections around the Marádah Oasis in the Central Sirt Basin of Libya. The field investigations led to the identification of two members, the lower Qarat Jahannam Member and the upper Ar Ráhlah Member. Fourteen sedimentary facies at the outcrop-scale representing a gradual development of sedimentation from a continental clastic witness in the southwestern outcrops to transitional estuarine, lagoonal, and beaches to the proximal offshore in the northern outcrops, were recognized. The results indicates that the accumulation of the Marádah Formation is transgressive in nature and corresponding to two phases of deposition which have been mentioned in the earlier studies.
 
 The first phase is continental-dominated facies in which cross-bedded sandstones and calcareous sands comprise most of the depositional sequence of the lower Qarat Jahannam Member at the southwestern outcrops. This phase, however, is characterized by extremely bioturbated laminated-shale conquered by Skolithos ichnofacies in the lower part of the upper Ar Ráhlah Member at the northern outcrops. This phase is providing further evidence that the contact between the two members is diachronous everywhere in the study area. The clastic-phase has thought to be deposited in the Lower Miocene (Aquitanian-Burdigalian) since the lower Qarat Jahannam Member rests on an erosional surface of submarine origin in the southwestern outcrops above a 0.5 m. thick of a nummulitic unit of the Oligocene Bu Hashish Formation.
 
 The second phase is marine-dominated facies in which a bioclastic limestone unit rich in thick and disarticulated oysters, including Crassostrea gryphoides (Schlottheim), characterizes the sediments of the Ar Ráhlah Member at the southwestern outcrops. This phase also includes the upper part of the latter member at the northern outcrops in which a detrital limestone unit rich in turritelline gastropods is overlying by thick-bedded calcarenites rich in disarticulated oysters, gastropods, irregular echinoids (notably, Clypeaster and Echinolampas), bryozoans, and celestite corals. The upper part of the Ar Ráhlah Member at the northern outcrops, nevertheless, is terminated by a quite hard dolomitic limestone and by a pretty soft dolomitic marly limestone. Both lithologies, however, are combined with medium-sized oysters, including Ostrea digitalina Fuchs, and pectinid bivalves. The second phase, however, is interpreted to be deposited in the Middle Miocene (Langhian and Serravallian) based on the total-stratigraphic range of the larger benthic foraminifera Borelis melo melo (Fichtel & Moll), which recovered from the studied washed residues, and the associated microfacies.

Yield Performance, Proximate Composition, Fatty Acid Profile and Economic Viability of Farmed Oyster (Crassostrea spp.) in Bangladesh

Oyster meat is consumed for its high nutritional value. Marine oysters (several species under the genus Crassostrea) have been commercially cultured long since around the world to satisfy the increased demand of oyster. Bangladesh has taken approaches to initiate oyster mariculture. Three pilot commercial oyster (Crassostrea spp.) farms were constructed by District Fisheries Office, Cox’s Bazar at Nunia Chara (NC – 21°28ˈ19.5" N, 91°57ˈ42.7" E), Chowfoldandy (CD – 21°30ˈ44.1" N, 92°01ˈ00.1" E) and Sonadia Island (SI – 21°30ˈ18.7" N, 91°53ˈ43.3" E) in Cox’s Bazar, Bangladesh. Live oysters were collected from the farm and taken to the laboratory maintaining cold chain to analyse proximate and fatty acids. Data on yield as well as cost-benefit were collected from the District Fisheries Office, Cox’s Bazar to analyse yield performance and economic viability. Biological yield was observed 19.9 ± 5.7 kg/m2 and economic yield was observed 11.3 ± 2.5 kg/m2 . Moisture, protein, lipid, carbohydrate, ash and fiber was found 79.2 ± 0.2%, 58.1 ± 2.1%, 10.2 ± 0.7%, 13.5 ± 1.4%, 12.3 ± 0.7% and 0.4 ± 0.0%, respectively, while moisture was determined in wet weight basis and rests were determined in dry weight basis. Saturated fatty acid, monounsaturated fatty acid, omega-3 fatty acid, omega-6 fatty acid and polyunsaturated fatty acid were observed 35.22 ± 10.91%, 13.77 ± 4.36%, 7.39 ± 4.00%, 43.62 ± 19.21, 51.01 ± 15.23% of total fatty acid, respectively. Annual net profit of the farms was found 34557 ± 5636 BDT and payback period was found 2.6 ± 0.4 years. Thus, oyster farming was found to be potential for high food value as well as an economically viable oyster farm enterprise.

Cytoprotective effects of fermented oyster extracts against oxidative stress-induced DNA damage and apoptosis through activation of the Nrf2/HO-1 signaling pathway in MC3T3-E1 osteoblasts.

Osteoblast damage by oxidative stress has been recognized as a cause of bone-related disease, including osteoporosis. Recently, we reported that fermented Pacific oyster (Crassostrea gigas) extracts (FO) inhibited osteoclastogenesis and osteoporosis, while promoting osteogenesis. However, since the beneficial potential of FO on osteoblasts is not well known, in the present study, we investigated the cytoprotective effect of FO against oxidative stress in MC3T3-E1 osteoblasts. Our results demonstrated that FO inhibited hydrogen peroxide (H2O2)-induced DNA damage and cytotoxicity through the rescue of mitochondrial function by blocking abnormal ROS accumulation. FO also prevented apoptosis by suppressing loss of mitochondrial membrane potential and cytosolic release of cytochrome c, decreasing the rate of Bax/Bcl-2 expression and reducing the activity of caspase-9 and caspase-3 in H2O2-stimulated MC3T3-E1 osteoblasts, suggesting that FO protected MC3T3-E1 osteoblasts from the induction of caspase dependent- and mitochondria-mediated apoptosis by oxidative stress. In addition, FO markedly promoted the activation of nuclear factor-erythroid-2-related factor 2 (Nrf2), which was associated with the enhanced expression of heme oxygenase-1 (HO-1). However, inhibiting the expression of HO-1 by artificially blocking the expression of Nrf2 using siRNA significantly eliminated the protective effect of FO, indicating that FO activates the Nrf2/HO-1 signaling pathway in MC3T3-E1 osteoblasts to protect against oxidative stress. Based on the present data, FO is thought to be useful as a potential therapeutic agent for the inhibition of oxidative stress in osteoblasts.

Comparative characterization of bacterial communities in digestive glands of Crassostrea gigas fed with different microalgal diets

The digestive glands of marine molluscs are colonized by a large number of microorganisms, and the structure and function of bacterial community could be severely affected by diets. Microalgae is the main food and energy sources for bivalves, while the impact of phytoplankton composition on the bacterial community as well as the health of bivalves are still not well understood. In the present study, the bacterial communities in digestive glands of oyster Crassostrea gigas fed with different diets were compared based on the high-throughput sequencing of partial 16S rRNA gene. There were significant differences of bacterial composition rather than diversity in digestive glands between the oysters fed with diatom dominant diet (Group N, mainly made up of Nitzschia closterium f.minutissima) and dinoflagellate dominant diet (Group P, mainly made up of Prorocentrum micans). The abundances of Prevotella, Vibronaceae, Ruminococcaceae, and Polaribacter were significantly higher in Group N (p < 0.05), and the abundances of Streptophyta and Acidimicrobiales were significantly higher in Group P (p < 0.05). According to the functional prediction results, the bacterial community in Group P displayed weaker capacities of Kdo2-lipid A biosynthesis as well as taurine degradation, and a stronger capacity of glycolysis compared with the bacterial community in Group N. The higher phylogenetic clustering degree of the bacterial community in Group P (p < 0.05) indicated the higher host selectivity on bacteria. These results suggested that the change of phytoplankton composition of diet would have large effects on bacterial communities in oyster digestive glands. The bacterial community in digestive glands of oysters living in dinoflagellate dominant waters would produce harmful impact to hosts. The present study provided a new perspective to explore the potential mechanism for the massive mortalities of oysters.

First report of detection of Toxoplasma gondii DNA in oysters (Crassostrea sp.) in the state of Maranhão.

The aim of this study was to report on detection of Toxoplasma gondii DNA in oysters (Crassostrea sp.) in the state of Maranhão. To conduct this study, 200 farmed oysters were acquired in the municipality of Raposa and 100 in Paço do Lumiar; and a further 100 oysters were taken from the natural stock in the municipality of Primeira Cruz. This total of 400 specimens sampled was divided into 80 pools composed of five animals each. The gills and visceral mass of each oyster were removed for DNA extraction (per pool of oysters), using a commercial kit. The nested PCR technique (with the primer SAG-1) was then used to investigate any presence of protozoa. This molecular technique demonstrated the presence of DNA of T. gondii in 2.5% of the pools of oysters (n = 2/80): these oysters were exclusively from farms. The results from this study allow the conclusion that oysters of the genus Crassostrea that are farmed in the state of Maranhão are capable of filtering oocysts of T. gondii and maintaining them in their tissues. They are therefore potential sources of contamination for humans and other animals.

Nonconsumptive predator effects on eastern oysters Crassostrea virginica across environmental and ecological gradients

Nonconsumptive predator effects on eastern oysters Crassostrea virginica across environmental and ecological gradients

MOLECULAR IDENTIFICATION OF CRYPTIC SPECIES OF OYSTERS (GENUS Crassostrea SACCO, 1897) IN THE NORTHEAST ATLANTIC COAST OF BRAZIL

Oysters of the genus Crassostrea Sacco, 1897 are widely distributed worldwide, being important extractive and cultivation resources in Brazil. Because they have high phenotypical plasticity and congeneric similarity, identifications based on shell morphology are not always safe. The goal of this study was to identify the oysters of the Bahia State, northeast Brazil, using the molecular tools Polymerase Chain Reaction, Restriction Fragment Length Polymorphism, DNA sequencing and phylogenetic analysis. Oysters were collected at 12 sampling stations, from October 2014 to March 2015 and included samples of rhizomes (aerial roots)/stems of the red mangrove Rhizophorae mangle L. and in the sediment near to the underground roots of this one, on berths, natural rock outcrops near the mangrove swamp and in three oyster crops. It was confirmed the presence of two species of oysters: Crassostrea rhizophorae (Guilding, 1828) and C. gasar (Deshayes, 1830) and that the latter was genetically identical to C. brasiliana reported in previous studies on the Brazilian coast. There was no co-occurrence of the two species on the same substrate, but these were found in nearby environments at two sampling points. Crassostrea rhizophorae was observed on the rhizomes/stems of R. mangle, as well as on artificial concrete walls (berths). The semi-buried oysters near R. mangle's subterranean roots and adhered to small rocks of a rocky outcrop were C. gasar, which was also the exclusive oyster of the crops.

Detection of Toxoplasma gondii in Crassostrea spp. oysters cultured in an estuarine region in eastern Amazon

The aim of the present study was to detect DNA of Toxoplasma gondii in Crassostrea spp. oysters cultured in the state of Pará, Brazil. A total of 400 oysters were directly collected from a fixed rack system. Gills, gastrointestinal tract (GIT) and intervalvular liquid were separated and grouped into pool samples of 10 animals, resulting in 40 samples each of gills, GIT and intervalvular liquid. DNA extraction was performed using a commercial kit, and T.gondii DNA was detected by nested PCR using the primers Toxo3 and Toxo4, which produced an amplification product of 155bp of the T.gondii gene B1. Nucleotide sequencing was performed for positive samples, and the obtained sequences were identified by comparison with sequences in GenBank. The DNA of T.gondii was detected in 5.8% (7/120) of the pool samples, of which 7.5% (3/40) was in the GIT, 5% (2/40) in the gills, and 5% (2/40) was in the intervalvular liquid. The obtained sequences presented 100% identity and overlap with T.gondii DNA sequences. This is the report of detection of T.gondii DNA in oysters from genus Crassostrea spp. originating from the state of Pará, eastern Amazon.

An Estimation of the Possible Migration Path of the Pacific Oyster (Crassostrea gigas) Along the Northern Coast of Patagonia

Fil: Worner, Stefania. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografia Naval; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina. Universidad de Buenos Aires; Argentina