Science.gov

Sample records for gigantic bivalve alatoconchidae

  1. Guadalupian (Middle Permian) giant bivalve Alatoconchidae from a mid-Panthalassan paleo-atoll complex in Kyushu, Japan: A unique community associated with Tethyan fusulines and corals.

    PubMed

    Isozaki, Yukio

    2006-03-01

    Unique new fossil assemblages containing the large bivalve family Alatoconchidae are recorded from the Guadalupian (Middle Permian) shallow marine limestone in Kamura, Kyushu. The large bivalves occur in the Neoschwagerina Zone and Lepidolina Zone. This discovery establishes that the biostratigraphic range of the family Alatoconchidae extends up to the top of the Lepidolina Zone (upper Capitanian of upper Guadalupian) i.e., to the end-Guadalupian extinction level. The largest Alatoconchidae in Kamura occurs in the Neoschwagerina Zone, the size of which is up to 50 cm long and 5 cm thick. Although details are still unknown, their morphology with a wing-like side projection of their valves appears very similar to that of Alatoconchidae that includes the well-known genus Shikamaia Ozaki. The bivalve-bearing Iwato Formation was derived from a mid-oceanic shallow marine carbonate build-up formed on a mid-oceanic paleo-seamount. The close association among the Alatoconchidae, typical Tethyan fusulines (Verbeekinidae) and rugose corals (Waagenophyllidae), plus their common extinction pattern suggests that the Alatoconchidae flourished in warm, shallow (photic) marine environments in low latitude areas in Panthalassa as well as Tethys. The extra-large size and double-layered shell with a translucent outer layer composed of prismatic calcite suggests that these bivalves may have hosted abundant photosynthetic algal symbionts to support their large-body metabolism.

  2. Guadalupian (Middle Permian) giant bivalve Alatoconchidae from a mid-Panthalassan paleo-atoll complex in Kyushu, Japan: A unique community associated with Tethyan fusulines and corals.

    PubMed

    Isozaki, Yukio

    2006-03-01

    Unique new fossil assemblages containing the large bivalve family Alatoconchidae are recorded from the Guadalupian (Middle Permian) shallow marine limestone in Kamura, Kyushu. The large bivalves occur in the Neoschwagerina Zone and Lepidolina Zone. This discovery establishes that the biostratigraphic range of the family Alatoconchidae extends up to the top of the Lepidolina Zone (upper Capitanian of upper Guadalupian) i.e., to the end-Guadalupian extinction level. The largest Alatoconchidae in Kamura occurs in the Neoschwagerina Zone, the size of which is up to 50 cm long and 5 cm thick. Although details are still unknown, their morphology with a wing-like side projection of their valves appears very similar to that of Alatoconchidae that includes the well-known genus Shikamaia Ozaki. The bivalve-bearing Iwato Formation was derived from a mid-oceanic shallow marine carbonate build-up formed on a mid-oceanic paleo-seamount. The close association among the Alatoconchidae, typical Tethyan fusulines (Verbeekinidae) and rugose corals (Waagenophyllidae), plus their common extinction pattern suggests that the Alatoconchidae flourished in warm, shallow (photic) marine environments in low latitude areas in Panthalassa as well as Tethys. The extra-large size and double-layered shell with a translucent outer layer composed of prismatic calcite suggests that these bivalves may have hosted abundant photosynthetic algal symbionts to support their large-body metabolism. PMID:25792767

  3. Gigantism

    MedlinePlus

    Gigantism; Pituitary giant; Overproduction of growth hormone; Growth hormone - excess production ... The most common cause of too much growth hormone release is a noncancerous (benign) tumor of the ...

  4. Pituitary gigantism.

    PubMed

    Daughaday, W H

    1992-09-01

    Pituitary gigantism is a rare condition whose association with McCune-Albright syndrome suggests that mutations in alpha-subunit of a Gs protein are an important cause of this condition. In addition to somatotroph adenoma, it is now recognized that somatotroph hyperplasia can also result from increased levels of growth hormone-releasing hormone. Transgenic rats with hypersomatotrophism are prone to renal and hepatic pathology. PMID:1521516

  5. [Gigantism: a mystery explained].

    PubMed

    Beckers, Alb

    2002-01-01

    Acromegaly was first described by Pierre Marie in 1886. Some years later, it became clear that acromegaly and gigantism share the same etiology: GH hypersecretion due to a pituitary adenoma, induces gigantism if already present during puberty, or an acromegalic if it appears only during the adulthood. During the XXth century, the disease has been well described and is now well controlled with several treatments. Recently, genetic alterations responsible for the disease have been elucidated. PMID:12371275

  6. Protobranch bivalves.

    PubMed

    Zardus, John D

    2002-01-01

    The subclass Protobranchia comprises more than 600 species of bivalves that occur throughout the world ocean. Mostly deposit feeders in soft sediments, they are abundant in the deep sea. Apomorphies that unite them as a group include gill structure, hinge conformation, shell microstructure, larval development, foot morphology, respiratory pigments, trophic mode and digestion. They are relatively small and highly conserved in form, originating in the Cambrian era. They may represent an ancestral, derived or paraphylectic group of the Bivalvia. The protobranchs include two orders, the Nuculoida and Solemyoida, which previously were classified separately in the subclasses Paleotaxodonta and Cryptodonta, respectively. They are of ecological interest and have a unique functional morphology. They feed mostly under the surface of the sediment with highly modified labial palps, but the degree to which they are selective in diet remains difficult to determine. They are important bioturbators in many soft-sediment assemblages; their feeding and locomotion affects sediment structure and community development. Solemyoids are unusual in inhabiting reducing environments and hydrocarbon seeps and in deriving their nutrition from endosymbiotic chemosynthetic bacteria. A variety of species of protobranchs are found in oceanic trenches, near hydrothermal vents, and in submarine caves. Protobranchs produce a lecithotrophic larval stage, the pericalymma, making their development unique among bivalves. The pericalymma remains in the plankton for a short time and presumably has low dispersal ability. Recruitment may be intermittent. Growth is rapid in post-larvae but decreases with age, though rates may not necessarily be slow, especially in continental shelf species. Life spans are commonly 1 to 2 decades, but deep-sea representatives may grow more slowly and live longer. Bottom fish, seastars and gastropods are their major predators and a few parasites and commensals have been

  7. The Pituitary in Gigantism.

    PubMed

    Scheithauer, Bernd W.; Kovacs, Kalman T.; Stefaneanu, Lucia; Horvath, Eva; Kane, Laurie A.; Young, William F.; Lloyd, Ricardo V.; Randall, Raymond V.; Davis, Dudley H.

    1995-01-01

    To compare the pituitary pathology of gigantism to that of acromegaly, 19 surgically resected lesions were studied from 10 males and 9 females, ages 13-49 (mean, 19 yr) with excessive height (>/=95th percentile), onset of disease prior to puberty, elevated growth hormone (GH) levels despite glucose suppression, and a pathologically confirmed GH-producing pituitary mass. One patient had MEN-I. The lesions included 18 adenomas and 1 case of pure hyperplasia. The median, mean, and range of serum GH and prolactin (PRL) levels were 64, 235, 5-1000 ng/mL and 47, 146, 29-770 ng/mL, respectively. Of the 8 adenoma specimens accompanied by nontumoral pituitary (i.e., tissue wherein the presence of hyperplasia was assessable), 3 (37%) demonstrated both. Of the 18 tumors, 78% were macroadenomas and 22% were grossly invasive; their immunophenotypes included GH (5%), GH and PRL (19%), and GHPRL and a glycoprotein hormone, usually TSH and/or a-subunit (76%). Of the 10 adenoma-containing lesions subject to electron microscopy (EM), 2 consisted of GH cells alone; 2 of mammosomatotroph (MS) cells alone; 1 of GH and MS cells; 1 of GH and PRL cells; 2 of GH, PRL, and MS cells; 1 of GH, PRL, and glycoprotein cells; and 1 was a subtype 3 adenoma. Ultrastructurally, GH cells and/or MS cells predominated in these lesions. Immuno-EM of one CH and PRL cell and of one GH-PR-MS tumor showed GH and PRL to be present not only in single cells but within the same granules. Nine of 12 adenoma-associated lesions subject to combined in situ hybridization (ISH) and immunostaining showed double labeling for PRL (or GH) mRNA and for GH (or PRL), respectively, features indicating MS differentiation. In the 4 lesions exhibiting hyperplasia, either alone (1) or in association with adenoma (3), EM showed MS cells in 3, and immuno-EM as well as combined immunohistochemistry and ISH showed double labeling for GH and PRL in both of the 2 cases studied. In summary, although in terms of their tinctorial

  8. A case of cerebral gigantism and hepatocarcinoma.

    PubMed

    Sugarman, G I; Heuser, E T; Reed, W B

    1977-06-01

    A 14-year-old boy, who had the physical and neurological characteristics of cerebral gigantism (Sotos syndrome), developed hepatocarcinoma. This tumor is rare in children and has never, to our knowledge, been recorded in a patient with cerebral gigantism. An autopsy was performed, the first we are aware of in a patient with cerebral gigantism without increased size in ventricles.

  9. Pituitary gigantism: Causes and clinical characteristics.

    PubMed

    Rostomyan, Liliya; Daly, Adrian F; Beckers, Albert

    2015-12-01

    Acromegaly and pituitary gigantism are very rare conditions resulting from excessive secretion of growth hormone (GH), usually by a pituitary adenoma. Pituitary gigantism occurs when GH excess overlaps with the period of rapid linear growth during childhood and adolescence. Until recently, its etiology and clinical characteristics have been poorly understood. Genetic and genomic causes have been identified in recent years that explain about half of cases of pituitary gigantism. We describe these recent discoveries and focus on some important settings in which gigantism can occur, including familial isolated pituitary adenomas (FIPA) and the newly described X-linked acrogigantism (X-LAG) syndrome. PMID:26585365

  10. Pituitary gigantism: Causes and clinical characteristics.

    PubMed

    Rostomyan, Liliya; Daly, Adrian F; Beckers, Albert

    2015-12-01

    Acromegaly and pituitary gigantism are very rare conditions resulting from excessive secretion of growth hormone (GH), usually by a pituitary adenoma. Pituitary gigantism occurs when GH excess overlaps with the period of rapid linear growth during childhood and adolescence. Until recently, its etiology and clinical characteristics have been poorly understood. Genetic and genomic causes have been identified in recent years that explain about half of cases of pituitary gigantism. We describe these recent discoveries and focus on some important settings in which gigantism can occur, including familial isolated pituitary adenomas (FIPA) and the newly described X-linked acrogigantism (X-LAG) syndrome.

  11. Pituitary Gigantism: A Case Report

    PubMed Central

    Bhattacharjee, Rana; Roy, Ajitesh; Goswami, Soumik; Selvan, Chitra; Chakraborty, Partha P.; Ghosh, Sujoy; Biswas, Dibakar; Dasgupta, Ranen; Mukhopadhyay, Satinath; Chowdhury, Subhankar

    2012-01-01

    Objective: To present a rare case of gigantism. Case Report: A 25-year-old lady presented with increased statural growth and enlarged body parts noticed since the age of 14 years, primary amenorrhea, and frontal headache for the last 2 years. She has also been suffering from non-inflammatory low back pain with progressive kyphosis and pain in the knees, ankles, and elbows for the last 5 years. There was no history of visual disturbance, vomiting, galactorrhoea, cold intolerance. She had no siblings. Family history was non-contributory. Blood pressure was normal. Height 221 cm, weight 138 kg, body mass index (BMI)28. There was coarsening of facial features along with frontal bossing and prognathism, large hands and feet, and small goitre. Patient had severe kyphosis and osteoarthritis of knees. Confrontation perimetry suggested bitemporal hemianopia. Breast and pubic hair were of Tanner stage 1. Serum insulin like growth factor-1 (IGF1) was 703 ng/ml with all glucose suppressedgrowth hormone (GH)values of >40 ng/ml. Prolactin was 174 ng/ml. Basal serum Lutenising Hormone (LH), follicle stimulating Hormone (FSH) was low. Oral glucose tolerance test (OGTT), liver and renal function tests, basal cortisol and thyroid profile, Calcium, phosphorus and Intact Parathyroid hormone (iPTH) were normal. Computed tomographyscan of brain showed large pituitary macroadenoma. Automated perimetry confirmed bitemporal hemianopia. A diagnosis of gigantism due to GH secreting pituitary macroadenoma with hypogonadotrophichypogonadism was made. Debulking pituitary surgery followed by somatostatin analogue therapy with gonadal steroid replacement had been planned, but the patient refused further treatment. PMID:23565401

  12. Dwarfism and gigantism in historical picture postcards.

    PubMed

    Enderle, A

    1998-05-01

    A collection of 893 historical picture postcards from 1900 to 1935, depicting dwarfs and giants, was analysed from medical and psychosocial viewpoints. In conditions such as 'bird headed dwarfism', achondroplasia, cretinism, so-called Aztecs or pinheads, Grebe chondrodysplasia, and acromegalic gigantism, the disorder could be diagnosed easily. In hypopituitary dwarfism, exact diagnosis was more difficult because of heterogeneity. The most common conditions depicted were pituitary dwarfism and achondroplasia. Most of those with gigantism had pituitary gigantism and acromegaly. Brothers and sisters or parents and their children provided evidence of mendelian inheritance of some of these disorders. The cards suggest that being put on show provided, at least in some cases, social benefits. PMID:9764085

  13. Butterflied bivalves as paleoenvironmental indicators

    SciTech Connect

    Allmon, R.A.

    1985-01-01

    Fossil bivalves are seldom preserved in a flat-open, yet still articulated position, or butterflied. A study of butterflied bivalves in the Delphi Station of the Hamilton Fm. suggests that this preservation mode is limited to one or possibly two sedimentary environments: deltaic and fluvial. Three parameters control the mode of preservation of fossil bivalves: 1) rate of sedimentation, 2) depth of bioturbation, and 3) time of ligament failure. Using these three parameters a model for the occurrence of butterflied bivalves can be constructed: bioturbation depth divided by sedimentation rate gives the disturbance time (DST), during which shells on one bedding plane would be subject to reworking. This can be seen as a time window into which ligament failure times - or disarticulation time (DAT) - can be fitted. If DATbivalves may be used as partial indicators of conditions prevailing in environments of deposition.

  14. Mechanisms of viral persistence within bivalves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fecal bacteria and waterborne enteric viruses bioconcentrate within bivalve shellfish. However while bacteria are readily purged, viruses tend to be retained within shellfish when bivalves are depurated. The US. Department of Agriculture Seafood Safety Laboratory has recently demonstrated that pha...

  15. Triangulation of the Gigantic Jets in 20 August 2014

    NASA Astrophysics Data System (ADS)

    Kang-Ming, P.; Hsu, R. R.; Su, H. T.; Chen, A. B. C.; Chou, J. K.; Chang, S. C.; Wu, Y. J.; Chien-Lun, H.; Yang, I. C.; Tsai, S. H.

    2015-12-01

    Coordinate optical observation campaigns on TLEs near Taiwan are held since 2011 with the aim to triangulate TLEs. Currently, there are four stations with baseline varying from 100 to 400 km between them. Our optical observation systems recorded 48 various types of TLEs on the night of 20 August 2014, with eight of them being gigantic jets that were recorded by at least two stations. Due to the length of baselines and the TLE occurring locations, the earth curvature needed to be taken into account by means of spherical trigonometry method. The preliminary results shows the gigantic jets occurred over the northern Taiwan and the accuracy of geolocation is less than 1 km and the accuracy of the retrieval height on the key structures is less than 0.5 km. The triangulation results of the eight events indicate most of these gigantic jets terminated at 80-90km, but one of the gigantic jets is likely extend to 100 km. Three of the eight gigantic jets occurred consequently after previous one with time interval of 500ms to more than 100s. The previous gigantic jet is likely to influence the consequent gigantic jet for usually the consequent gigantic jet has more beads structures in high altitude and one of the streamer column of a consequent gigantic jets at 55 -60 km is identified to re-bright, which is more than 100s after the previous gigantic jet.

  16. Gigantic Suprapubic Lymphedema: A Case Study

    PubMed Central

    Tanhaeivash, Roozbeh; Franiel, Tobias; Grimm, Marc-Oliver

    2016-01-01

    We present the first case study of idiopathic gigantic suprapubic lymphedema and buried penis treated with puboscrotal reconstruction in a patient with initial extreme obesity after an extensive weight reduction (120 kg). Massive localized lymphedema of the suprapubic region should be differentiated from the scrotal type. Severe lymphedema could not resolve on its own and weight reduction does not seem to be helpful in such cases. PMID:27574599

  17. Gigantic Suprapubic Lymphedema: A Case Study.

    PubMed

    Tanhaeivash, Roozbeh; Franiel, Tobias; Grimm, Marc-Oliver; Horstmann, Marcus

    2016-08-01

    We present the first case study of idiopathic gigantic suprapubic lymphedema and buried penis treated with puboscrotal reconstruction in a patient with initial extreme obesity after an extensive weight reduction (120 kg). Massive localized lymphedema of the suprapubic region should be differentiated from the scrotal type. Severe lymphedema could not resolve on its own and weight reduction does not seem to be helpful in such cases. PMID:27574599

  18. Toxic responses of bivalves to metal mixtures

    SciTech Connect

    Mathew, P.; Menon, N.R. )

    1992-02-01

    Although there is a growing body of information on the toxicity of individual heavy metals to economically important on the toxicity of individual heavy metals to economically important species of bivalves, literature on the lethal toxicity of metal mixtures to bivalves under controlled conditions is rather limited. In the present investigation the toxic effects of combinations of copper - mercury and copper - mercury and copper - cadmium at lethal levels of two marine bivalve species, Perna indica and Donax incarnatus, have been delineated.

  19. Gigantism and Its Implications for the History of Life.

    PubMed

    Vermeij, Geerat J

    2016-01-01

    Gigantism-very large body size-is an ecologically important trait associated with competitive superiority. Although it has been studied in particular cases, the general conditions for the evolution and maintenance of gigantism remain obscure. I compiled sizes and dates for the largest species in 3 terrestrial and 7 marine trophic and habitat categories of animals from throughout the Phanerozoic. The largest species (global giants) in all categories are of post-Paleozoic age. Gigantism at this level appeared tens to hundreds of millions of years after mass extinctions and long after the origins of clades in which it evolved. Marine gigantism correlates with high planktic or seafloor productivity, but on land the correspondence between productivity and gigantism is weak at best. All global giants are aerobically active animals, not gentle giants with low metabolic demands. Oxygen concentration in the atmosphere correlates with gigantism in the Paleozoic but not thereafter, likely because of the elaboration of efficient gas-exchange systems in clades containing giants. Although temperature and habitat size are important in the evolution of very large size in some cases, the most important (and rare) enabling circumstance is a highly developed ecological infrastructure in which essential resources are abundant and effectively recycled and reused, permitting activity levels to increase and setting the stage for gigantic animals to evolve. Gigantism as a hallmark of competitive superiority appears to have lost its luster on land after the Mesozoic in favor of alternative means of achieving dominance, especially including social organization and coordinated food-gathering.

  20. Fungal Cell Gigantism during Mammalian Infection

    PubMed Central

    Zaragoza, Oscar; García-Rodas, Rocío; Nosanchuk, Joshua D.; Cuenca-Estrella, Manuel; Rodríguez-Tudela, Juan Luis; Casadevall, Arturo

    2010-01-01

    The interaction between fungal pathogens with the host frequently results in morphological changes, such as hyphae formation. The encapsulated pathogenic fungus Cryptococcus neoformans is not considered a dimorphic fungus, and is predominantly found in host tissues as round yeast cells. However, there is a specific morphological change associated with cryptococcal infection that involves an increase in capsule volume. We now report another morphological change whereby gigantic cells are formed in tissue. The paper reports the phenotypic characterization of giant cells isolated from infected mice and the cellular changes associated with giant cell formation. C. neoformans infection in mice resulted in the appearance of giant cells with cell bodies up to 30 µm in diameter and capsules resistant to stripping with γ-radiation and organic solvents. The proportion of giant cells ranged from 10 to 80% of the total lung fungal burden, depending on infection time, individual mice, and correlated with the type of immune response. When placed on agar, giant cells budded to produce small daughter cells that traversed the capsule of the mother cell at the speed of 20–50 m/h. Giant cells with dimensions that approximated those in vivo were observed in vitro after prolonged culture in minimal media, and were the oldest in the culture, suggesting that giant cell formation is an aging-dependent phenomenon. Giant cells recovered from mice displayed polyploidy, suggesting a mechanism by which gigantism results from cell cycle progression without cell fission. Giant cell formation was dependent on cAMP, but not on Ras1. Real-time imaging showed that giant cells were engaged, but not engulfed by phagocytic cells. We describe a remarkable new strategy for C. neoformans to evade the immune response by enlarging cell size, and suggest that gigantism results from replication without fission, a phenomenon that may also occur with other fungal pathogens. PMID:20585557

  1. Fungal cell gigantism during mammalian infection.

    PubMed

    Zaragoza, Oscar; García-Rodas, Rocío; Nosanchuk, Joshua D; Cuenca-Estrella, Manuel; Rodríguez-Tudela, Juan Luis; Casadevall, Arturo

    2010-01-01

    The interaction between fungal pathogens with the host frequently results in morphological changes, such as hyphae formation. The encapsulated pathogenic fungus Cryptococcus neoformans is not considered a dimorphic fungus, and is predominantly found in host tissues as round yeast cells. However, there is a specific morphological change associated with cryptococcal infection that involves an increase in capsule volume. We now report another morphological change whereby gigantic cells are formed in tissue. The paper reports the phenotypic characterization of giant cells isolated from infected mice and the cellular changes associated with giant cell formation. C. neoformans infection in mice resulted in the appearance of giant cells with cell bodies up to 30 microm in diameter and capsules resistant to stripping with gamma-radiation and organic solvents. The proportion of giant cells ranged from 10 to 80% of the total lung fungal burden, depending on infection time, individual mice, and correlated with the type of immune response. When placed on agar, giant cells budded to produce small daughter cells that traversed the capsule of the mother cell at the speed of 20-50 m/h. Giant cells with dimensions that approximated those in vivo were observed in vitro after prolonged culture in minimal media, and were the oldest in the culture, suggesting that giant cell formation is an aging-dependent phenomenon. Giant cells recovered from mice displayed polyploidy, suggesting a mechanism by which gigantism results from cell cycle progression without cell fission. Giant cell formation was dependent on cAMP, but not on Ras1. Real-time imaging showed that giant cells were engaged, but not engulfed by phagocytic cells. We describe a remarkable new strategy for C. neoformans to evade the immune response by enlarging cell size, and suggest that gigantism results from replication without fission, a phenomenon that may also occur with other fungal pathogens.

  2. [Comparison of mitochondrial genomes of bivalves].

    PubMed

    SONG, Wen-Tao; GAO, Xiang-Gang; LI, Yun-Feng; LIU, Wei-Dong; LIU, Ying; HE, Chong-Bo

    2009-11-01

    The structure and organization of mitochondrial genomes of 14 marine bivalves and two freshwater bivalves were analyzed using comparative genomics and bioinformatics methods. The results showed that the organization and gene order of the mitochondrial genomes of these bivalve species studied were different from each other. The size, organization, gene numbers, and gene order of mitochondrial genomes in bivalves at different taxa were different. Phylogenetic analysis using the whole mitochondrial genomes and all the coding genes showed different results-- phylogenetic analysis conducted using the whole mitochondrial genomes was consistent with the existing classification and phylogenetic analysis conducted using all coding genes not consistent with the existing classification.

  3. [A case of cerebral gigantism with cerebellar atrophy].

    PubMed

    Kitazawa, K; Ikeda, M; Tsukagoshi, H

    1990-05-01

    A 37-year-old housewife, who had physical characteristics of cerebral gigantism, such as the tall stature, acromegaly, macrocephalia, high arched palate and antimongoloid slant, developed cerebellar ataxia and dysarthria. Her mother, uncle and grandmother were also reported to have slowly progressive gait disturbance. Her mother was also tall. Endocrinological studies failed to show any definite abnormality. CT and MRI revealed remarkable cerebellar atrophy. Though cerebral gigantism is often associated with clumsiness and incoordination, the etiology of the ataxia is poorly understood. This case indicates that the ataxia in cerebral gigantism may be, at least partly, caused by cerebellar atrophy. PMID:2401112

  4. Pyodermia chronica glutealis complicated by acromegalic gigantism.

    PubMed

    Nishijima, S; Kasahara, M; Suzuki, K; Kondoh, M; Tsubura, A

    1998-04-01

    We report a case of pyodermia chronica glutealis complicated by acromegalic gigantism associated with hyperprolactinemia. The serum prolactin, growth hormone, adrenocorticotropic hormone, and 11-deoxycortisol levels were elevated, but the estradiol and dehydroepiandrosterone-sulphate levels were within normal limits. However, the testosterone level was very low. Histopathologically, we found sinus tracts and scarring in a specimen from the buttocks. We could not immunohistochemically detect clear androgen, growth hormone, or prolactin receptors at any site. The patient was a man with a height of 197 cm and weight of 140 kg, he had clinical features of active acromegaly such as excessive sweating and increased thickness of soft tissue. He was also diagnosed with diabetes mellitus. Under such conditions, bacteria could easily grow and lesions might have been aggravated by the heavy pressure from his weight, a possible causes of his pyodermia chronica glutealis. PMID:9609982

  5. Hereditary Pituitary Hyperplasia with Infantile Gigantism

    PubMed Central

    Gläsker, Sven; Vortmeyer, Alexander O.; Lafferty, Antony R. A.; Hofman, Paul L.; Li, Jie; Weil, Robert J.; Zhuang, Zhengping

    2011-01-01

    Context: We report hereditary pituitary hyperplasia. Objective: The objective of the study was to describe the results of the clinical and laboratory analysis of this rare instance of hereditary pituitary hyperplasia. Design: The study is a retrospective analysis of three cases from one family. Setting: The study was conducted at the National Institutes of Health, a tertiary referral center. Patients: A mother and both her sons had very early-onset gigantism associated with high levels of serum GH and prolactin. Interventions: The condition was treated by total hypophysectomy. Main Outcome Measure(s): We performed clinical, pathological, and molecular evaluations, including evaluation basal and provocative endocrine testing, neuroradiological assessment, and assessment of the pituitary tissue by microscopic evaluation, immunohistochemistry, and electron microscopy. Results: All three family members had very early onset of gigantism associated with abnormally high serum levels of GH and prolactin. Serum GHRH levels were not elevated in either of the boys. The clinical, radiographic, surgical, and histological findings indicated mammosomatotroph hyperplasia. The pituitary gland of both boys revealed diffuse mammosomatotroph hyperplasia of the entire pituitary gland without evidence of adenoma. Prolactin and GH were secreted by the same cells within the same secretory granules. Western blot and immunohistochemistry demonstrated expression of GHRH in clusters of cells distributed throughout the hyperplastic pituitary of both boys. Conclusions: This hereditary condition seems to be a result of embryonic pituitary maldevelopment with retention and expansion of the mammosomatotrophs. The findings suggest that it is caused by paracrine or autocrine pituitary GHRH secretion during pituitary development. PMID:21976722

  6. Gigantism and Its Implications for the History of Life.

    PubMed

    Vermeij, Geerat J

    2016-01-01

    Gigantism-very large body size-is an ecologically important trait associated with competitive superiority. Although it has been studied in particular cases, the general conditions for the evolution and maintenance of gigantism remain obscure. I compiled sizes and dates for the largest species in 3 terrestrial and 7 marine trophic and habitat categories of animals from throughout the Phanerozoic. The largest species (global giants) in all categories are of post-Paleozoic age. Gigantism at this level appeared tens to hundreds of millions of years after mass extinctions and long after the origins of clades in which it evolved. Marine gigantism correlates with high planktic or seafloor productivity, but on land the correspondence between productivity and gigantism is weak at best. All global giants are aerobically active animals, not gentle giants with low metabolic demands. Oxygen concentration in the atmosphere correlates with gigantism in the Paleozoic but not thereafter, likely because of the elaboration of efficient gas-exchange systems in clades containing giants. Although temperature and habitat size are important in the evolution of very large size in some cases, the most important (and rare) enabling circumstance is a highly developed ecological infrastructure in which essential resources are abundant and effectively recycled and reused, permitting activity levels to increase and setting the stage for gigantic animals to evolve. Gigantism as a hallmark of competitive superiority appears to have lost its luster on land after the Mesozoic in favor of alternative means of achieving dominance, especially including social organization and coordinated food-gathering. PMID:26771527

  7. A Study in Bivalve Aging and Growth.

    ERIC Educational Resources Information Center

    Schlenker, Karl R.; Schlenker, Richard M.

    1998-01-01

    Describes how high school biology students use the clam to study the bivalve body plan anatomy. Employs an open-ended investigation format that is rich with measurement opportunities including body mass, valve mass, and volume. (DDR)

  8. Rostroconchia: A new class of bivalved mollusks

    USGS Publications Warehouse

    Pojeta, J.; Runnegar, B.; Morris, N.J.; Newell, N.D.

    1972-01-01

    Four Paleozoic bivalved genera are assigned to the new molluscan class Rostroconchia: Eopteria, Euchasma, Conocardium, and Pseudoconocardium. These mollusks have an uncoiled univalved larval shell; an untorted bivalved adult shell; no hinge teeth, ligament, or adductor muscles; and a fused, almost inflexible, hinge. Rostroconchians developed separately from the pelecypods through the ribeirioids, but are regarded as more closely related to the Pelecypoda and Scaphopoda than to other known classes of molllusks.

  9. Gigantism and Its Implications for the History of Life

    PubMed Central

    Vermeij, Geerat J.

    2016-01-01

    Gigantism—very large body size—is an ecologically important trait associated with competitive superiority. Although it has been studied in particular cases, the general conditions for the evolution and maintenance of gigantism remain obscure. I compiled sizes and dates for the largest species in 3 terrestrial and 7 marine trophic and habitat categories of animals from throughout the Phanerozoic. The largest species (global giants) in all categories are of post-Paleozoic age. Gigantism at this level appeared tens to hundreds of millions of years after mass extinctions and long after the origins of clades in which it evolved. Marine gigantism correlates with high planktic or seafloor productivity, but on land the correspondence between productivity and gigantism is weak at best. All global giants are aerobically active animals, not gentle giants with low metabolic demands. Oxygen concentration in the atmosphere correlates with gigantism in the Paleozoic but not thereafter, likely because of the elaboration of efficient gas-exchange systems in clades containing giants. Although temperature and habitat size are important in the evolution of very large size in some cases, the most important (and rare) enabling circumstance is a highly developed ecological infrastructure in which essential resources are abundant and effectively recycled and reused, permitting activity levels to increase and setting the stage for gigantic animals to evolve. Gigantism as a hallmark of competitive superiority appears to have lost its luster on land after the Mesozoic in favor of alternative means of achieving dominance, especially including social organization and coordinated food-gathering. PMID:26771527

  10. Late paleozoic fusulinoidean gigantism driven by atmospheric hyperoxia.

    PubMed

    Payne, Jonathan L; Groves, John R; Jost, Adam B; Nguyen, Thienan; Moffitt, Sarah E; Hill, Tessa M; Skotheim, Jan M

    2012-09-01

    Atmospheric hyperoxia, with pO(2) in excess of 30%, has long been hypothesized to account for late Paleozoic (360-250 million years ago) gigantism in numerous higher taxa. However, this hypothesis has not been evaluated statistically because comprehensive size data have not been compiled previously at sufficient temporal resolution to permit quantitative analysis. In this study, we test the hyperoxia-gigantism hypothesis by examining the fossil record of fusulinoidean foraminifers, a dramatic example of protistan gigantism with some individuals exceeding 10 cm in length and exceeding their relatives by six orders of magnitude in biovolume. We assembled and examined comprehensive regional and global, species-level datasets containing 270 and 1823 species, respectively. A statistical model of size evolution forced by atmospheric pO(2) is conclusively favored over alternative models based on random walks or a constant tendency toward size increase. Moreover, the ratios of volume to surface area in the largest fusulinoideans are consistent in magnitude and trend with a mathematical model based on oxygen transport limitation. We further validate the hyperoxia-gigantism model through an examination of modern foraminiferal species living along a measured gradient in oxygen concentration. These findings provide the first quantitative confirmation of a direct connection between Paleozoic gigantism and atmospheric hyperoxia.

  11. Ependimoma myxopapilar sacro gigante con osteolisis

    PubMed Central

    Ajler, Pablo; Landriel, Federico; Goldschmidt, Ezequiel; Campero, Álvaro; Yampolsky, Claudio

    2014-01-01

    Objetivo: la presentación de un caso de una paciente con un ependimoma sacro con extensa infiltración y destrucción ósea local. Descripción del caso: una mujer de 53 años acudió a la consulta por dolor lumbosacro y alteraciones sensitivas perineales y esfinterianas. La imágenes por Resonancia Magnética (IRM) y la Tomografía Axial Computada (TAC) mostraron una lesión expansiva gigante a nivel S2-S4 con extensa osteólisis e invasión de tejidos adyacentes. Se realizó una exéresis tumoral completa con mejoría del estatus funcional. La anatomía patológica informó ependimoma mixopapilar. Discusión: la extensión de la resección quirúrgica es el mejor predictor de buen pronóstico. El tratamiento radiante se reserva como opción adyuvante para las resecciones incompletas y recidiva tumoral. La quimioterapia sólo debería utilizarse en casos en que la cirugía y la radioterapia estén contraindicadas. Conclusión: Los ependimomas mixopapilares sacros con destrucción ósea y presentación intra y extradural son muy infrecuentes y deben ser tenidos en cuenta entre los diagnósticos diferenciales preoperatorios. Su resección total, siempre que sea posible, es la mejor alternativa terapéutica. PMID:25165615

  12. [Cryohypophysectomy in acromegaly and gigantism by the stereotaxic method].

    PubMed

    Mempel, E; Rap, Z; Jurkiewicz, J; Kuciński, L

    1985-01-01

    The authors report results of surgical treatment of 30 patients treated by cryohypophysectomy by the stereotactic method through the nose and sphenoid sinus in the years 1967-1979. The material included 28 cases of acromegaly and 2 cases of gigantism. The pathological manifestations in acromegaly and gigantism were analysed for demonstration which of them can regress after surgical treatment. The results of hormonal determinations, particularly the levels of growth hormone, 17-KS and hydroxysteroids, as well as blood glucose curves, were compared before and after cryohypophysectomy and their normalization was observed after the operation. There was principally no need for substitutive treatment after surgical treatment with the exception of 4 cases in which this treatment was given during several postoperative months. The indications to this method of therapy include cases of acromegaly and gigantism with presence of active intrasellar adenomas. Patients should be referred for treatment early before development of skeletal deformities. PMID:3912667

  13. Macrodystrophia Lipomatosa: An Unusual Cause of Localized Gigantism.

    PubMed

    Maheswari, S Uma; Sampath, V; Ramesh, A; Manoharan, K

    2016-01-01

    Macrodystrophia lipomatosa (MDL) is a rare congenital form of localized gigantism characterized by progressive overgrowth of all mesenchymal elements with a disproportionate increase in fibro adipose tissue. Here we report a case of 20 years old male who presented with history of painless gradual enlargement of entire left upper limb since childhood. Magnetic resonance imaging and histopathology confirmed the diagnosis of macrodystrophia lipomatosa. This condition has to be differentiated from other causes of localized gigantism, since these conditions differ in their course, prognosis, complications and treatment. PMID:27293271

  14. Macrodystrophia Lipomatosa: An Unusual Cause of Localized Gigantism

    PubMed Central

    Maheswari, S Uma; Sampath, V; Ramesh, A; Manoharan, K

    2016-01-01

    Macrodystrophia lipomatosa (MDL) is a rare congenital form of localized gigantism characterized by progressive overgrowth of all mesenchymal elements with a disproportionate increase in fibro adipose tissue. Here we report a case of 20 years old male who presented with history of painless gradual enlargement of entire left upper limb since childhood. Magnetic resonance imaging and histopathology confirmed the diagnosis of macrodystrophia lipomatosa. This condition has to be differentiated from other causes of localized gigantism, since these conditions differ in their course, prognosis, complications and treatment. PMID:27293271

  15. Macrodystrophia Lipomatosa: An Unusual Cause of Localized Gigantism.

    PubMed

    Maheswari, S Uma; Sampath, V; Ramesh, A; Manoharan, K

    2016-01-01

    Macrodystrophia lipomatosa (MDL) is a rare congenital form of localized gigantism characterized by progressive overgrowth of all mesenchymal elements with a disproportionate increase in fibro adipose tissue. Here we report a case of 20 years old male who presented with history of painless gradual enlargement of entire left upper limb since childhood. Magnetic resonance imaging and histopathology confirmed the diagnosis of macrodystrophia lipomatosa. This condition has to be differentiated from other causes of localized gigantism, since these conditions differ in their course, prognosis, complications and treatment.

  16. Hypothalamic mass and gigantism in neurofibromatosis: treatment with bromocriptine.

    PubMed

    Duchowny, M S; Katz, R; Bejar, R L

    1984-03-01

    A child with neurofibromatosis exhibited gigantism and acromegaly in association with a hypothalamic mass lesion. Bromocriptine, 5 mg daily, reduced somatic growth rate and restored biochemical homeostasis but had no effect on tumor growth. Radiation therapy arrested tumor enlargement and stabilized deteriorating visual function. PMID:6426370

  17. First observations of Gigantic Jets from Monsoon Thunderstorms over India

    NASA Astrophysics Data System (ADS)

    Singh, Rajesh; Maurya, Ajeet; Chanrion, Olivier; Neubert, Torsten; Cummer, Steven; Mlynarczyk, Janusz; Bór, József; Siingh, Devendraa; Cohen, Morris; Kumar, Sushil

    2016-04-01

    Gigantic Jets are electric discharges from thunderstorm cloud tops to the bottom of the ionosphere at ~80 km altitude. After their first discovery in 2001, relatively few observations have been reported. Most of these are from satellites at large distances and a few tens from the ground at higher spatial resolution. Here we report the first Gigantic Jets observed in India from two thunderstorm systems that developed over the land surface from monsoon activity, each storm producing two Gigantic Jets. The jets were recorded by a video camera system at standard video rate (20 ms exposure) at a few hundred km distance. ELF measurements suggest that the jets are of the usual negative polarity and that they develop in less than 40 ms, which is faster than most jets reported in the past. The jets originate from the leading edge of a slowly drifting convective cloud complex close to the highest regions of the clouds and carry ~25 Coulomb of charge to the ionosphere. One jet has a markedly horizontal displacement that we suggest is caused by a combination of close-range cloud electric fields at inception, and longer-range cloud fields at larger distances during full development. The Gigantic Jets are amongst the few that have been observed over land.

  18. Gigantism in sibling unrelated to multiple endocrine neoplasia: case report.

    PubMed

    Matsuno, A; Teramoto, A; Yamada, S; Kitanaka, S; Tanaka, T; Sanno, N; Osamura, R Y; Kirino, T

    1994-11-01

    The cases of gigantism sisters with somatotroph adenomas unrelated to multiple endocrine neoplasia (MEN) Type 1 are reported. The sisters grew rapidly since they were 5 or 6 years old and were diagnosed to have gigantism with pituitary adenoma by computed tomographic scan and magnetic resonance imaging. A serum endocrinological examination showed the elevated growth hormone values. After thyroxine-releasing hormone stimulation, growth hormone values exhibited a paradoxical rise. They were supposed to be unrelated to MEN Type 1, because analysis of the 11th chromosomes and the other endocrine functions were normal. They were operated on by the transphenoidal method. Immunohistochemical staining of both tumor specimens confirmed somatotroph adenomas. Pituitary adenoma associated with MEN Type 1 is a well-recognized entity. However, the sporadic occurrence of pituitary adenoma unrelated to MEN Type 1, especially in siblings, is extremely rare. Fifteen cases of pituitary adenomas in siblings were described in the literature. As for gigantism, only two brothers were reported. Our case of gigantism sisters is the second sporadic case. In our review of the isolated cases of pituitary adenoma in siblings described in the literature, 12 (70%) of 17 cases including ours are acromegaly or gigantism. This incidence is much higher than that of MEN Type 1 patients with pituitary adenomas. The cause of the familial occurrence of pituitary adenomas is still unclear, although autosomal recessive inheritance has been suggested. It has been stated that point mutations in codon 201 or 227 of the Gs alpha gene located in chromosome 20 were found in about 35 to 40% of somatotroph adenomas.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7838348

  19. Gigantism in sibling unrelated to multiple endocrine neoplasia: case report.

    PubMed

    Matsuno, A; Teramoto, A; Yamada, S; Kitanaka, S; Tanaka, T; Sanno, N; Osamura, R Y; Kirino, T

    1994-11-01

    The cases of gigantism sisters with somatotroph adenomas unrelated to multiple endocrine neoplasia (MEN) Type 1 are reported. The sisters grew rapidly since they were 5 or 6 years old and were diagnosed to have gigantism with pituitary adenoma by computed tomographic scan and magnetic resonance imaging. A serum endocrinological examination showed the elevated growth hormone values. After thyroxine-releasing hormone stimulation, growth hormone values exhibited a paradoxical rise. They were supposed to be unrelated to MEN Type 1, because analysis of the 11th chromosomes and the other endocrine functions were normal. They were operated on by the transphenoidal method. Immunohistochemical staining of both tumor specimens confirmed somatotroph adenomas. Pituitary adenoma associated with MEN Type 1 is a well-recognized entity. However, the sporadic occurrence of pituitary adenoma unrelated to MEN Type 1, especially in siblings, is extremely rare. Fifteen cases of pituitary adenomas in siblings were described in the literature. As for gigantism, only two brothers were reported. Our case of gigantism sisters is the second sporadic case. In our review of the isolated cases of pituitary adenoma in siblings described in the literature, 12 (70%) of 17 cases including ours are acromegaly or gigantism. This incidence is much higher than that of MEN Type 1 patients with pituitary adenomas. The cause of the familial occurrence of pituitary adenomas is still unclear, although autosomal recessive inheritance has been suggested. It has been stated that point mutations in codon 201 or 227 of the Gs alpha gene located in chromosome 20 were found in about 35 to 40% of somatotroph adenomas.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Microplastics in commercial bivalves from China.

    PubMed

    Li, Jiana; Yang, Dongqi; Li, Lan; Jabeen, Khalida; Shi, Huahong

    2015-12-01

    We investigated microplastic pollution in 9 commercial bivalves from a fishery market in China. Multiple types of microplastics, including fibers, fragments and pellets, occurred in the tissue of all bivalves. The number of total microplastics varied from 2.1 to 10.5 items/g and from 4.3 to 57.2 items/individual for bivalves. Scapharca subcrenata contained on average 10.5 items/g and exhibited the highest levels of microplastics by weight. Fibers were the most common microplastics and consisted of more than half of the total microplastics in each of the 8 species. In Alectryonella plicatula, pellets accounted for 60% of the total microplastics. The most common size class was less than 250 μm and accounted for 33-84% of the total microplastics calculated by species. Our results suggest that microplastic pollution was widespread and exhibited a relatively high level in commercial bivalves from China. More intensive investigations on microplastics should be conducted in seafood.

  1. A study of model bivalve siphonal currents

    USGS Publications Warehouse

    Monismith, Stephen G.; Koseff, Jeffrey R.; Thompson, Janet K.; O'Riordan, Catherine A.; Nepf, Heidi M.

    1990-01-01

    We carried out experiments studying the hydrodynamics of bivalve siphonal currents in a laboratory flume. Rather than use living animals, we devised a simple, model siphon pair connected to a pump. Fluorescence-based flow visualization was used to characterize siphon-jet flows for several geometric configurations and flow speeds. These measurements show that the boundary-layer velocity profile, siphon height, siphon pair orientation, and size of siphon structure all affect the vertical distribution of the excurrent flow downstream of the siphon pair and the fraction of excurrent that is refiltered. The observed flows may effect both the clearance rate of an entire population of siphonate bivalves as well as the efficiency of feeding of any individual. Our results imply that field conditions are properly represented in laboratory flume studies of phytoplankton biomass losses to benthic bivalves when the shear velocity and bottom roughness are matched to values found in the field. Numerical models of feeding by a bivalve population should include an effective sink distribution which is created by the combined incurrent-excurrent flow field. Near-bed flows need to be accounted for to properly represent these benthic-pelagic exchanges. We also present velocity measurements made with a laser-Doppler anemometer (LDA) for a single configuration (siphons flush with bed, inlet downstream) that show that the siphonal currents have a significant local effect on the properties of a turbulent boundary layer.

  2. Twin Explosions In Gigantic Dusty Potato Crisp

    NASA Astrophysics Data System (ADS)

    2006-05-01

    ESO's Very Large Telescope, equipped with the multi-mode FORS instrument, took an image of NGC 3190, a galaxy so distorted that astronomers gave it two names. And as if to prove them right, in 2002 it fired off, almost simultaneously, two stellar explosions, a very rare event. This beautiful edge-on spiral galaxy with tightly wound arms and a warped shape that makes it resemble a gigantic potato crisp lies in the constellation Leo ('the Lion') [1] and is approximately 70 million light years away. It is the dominant member of a small group of galaxies known as Hickson 44, named after the Canadian astronomer, Paul Hickson. In addition to NGC 3190 [2], Hickson 44 consists of one elliptical and two spiral galaxies. These are, however, slightly out of the field of view and therefore not visible here. ESO PR Photo 17/06 ESO PR Photo 17/06 The Spiral Galaxy NGC 3190 In 1982, Hickson published a catalogue of over 400 galaxies found in compact, physically-related groups of typically 4 to 5 galaxies per group (see the image of Robert's Quartet in ESO PR Photo 34/05 as another example). Such compact groups allow astronomers to study how galaxies dynamically affect each other, and help them test current ideas on how galaxies form. One idea is that compact groups of galaxies, such as Hickson 44, merge to form a giant elliptical galaxy, such as NGC 1316 (see ESO PR 17/00). Indeed, signs of tidal interactions are visible in the twisted dust lane of NGC 3190. This distortion initially misled astronomers into assigning a separate name for the southwestern side, NGC 3189, although NGC 3190 is the favoured designation. NGC 3190 has an 'Active Galactic Nucleus', and as such, the bright, compact nucleus is thought to host a supermassive black hole. In March 2002, a new supernova (SN 2002bo) was found in between the 'V' of the dust lanes in the southeastern part of NGC 3190. It was discovered independently by the Brazilian and Japanese amateur astronomers, Paulo Cacella and Yoji Hirose

  3. Bivalve grazing can shape phytoplankton communities

    USGS Publications Warehouse

    Lucas, Lisa; Cloern, James E.; Thompson, Janet K.; Stacey, Mark T.; Koseff, Jeffrey K.

    2016-01-01

    The ability of bivalve filter feeders to limit phytoplankton biomass in shallow waters is well-documented, but the role of bivalves in shaping phytoplankton communities is not. The coupled effect of bivalve grazing at the sediment-water interface and sinking of phytoplankton cells to that bottom filtration zone could influence the relative biomass of sinking (diatoms) and non-sinking phytoplankton. Simulations with a pseudo-2D numerical model showed that benthic filter feeding can interact with sinking to alter diatom:non-diatom ratios. Cases with the smallest proportion of diatom biomass were those with the fastest sinking speeds and strongest bivalve grazing rates. Hydrodynamics modulated the coupled sinking-grazing influence on phytoplankton communities. For example, in simulations with persistent stratification, the non-sinking forms accumulated in the surface layer away from bottom grazers while the sinking forms dropped out of the surface layer toward bottom grazers. Tidal-scale stratification also influenced vertical gradients of the two groups in opposite ways. The model was applied to Suisun Bay, a low-salinity habitat of the San Francisco Bay system that was transformed by the introduction of the exotic clam Potamocorbula amurensis. Simulation results for this Bay were similar to (but more muted than) those for generic habitats, indicating that P. amurensis grazing could have caused a disproportionate loss of diatoms after its introduction. Our model simulations suggest bivalve grazing affects both phytoplankton biomass and community composition in shallow waters. We view these results as hypotheses to be tested with experiments and more complex modeling approaches.

  4. A gigantic feathered dinosaur from the lower cretaceous of China.

    PubMed

    Xu, Xing; Wang, Kebai; Zhang, Ke; Ma, Qingyu; Xing, Lida; Sullivan, Corwin; Hu, Dongyu; Cheng, Shuqing; Wang, Shuo

    2012-04-04

    Numerous feathered dinosaur specimens have recently been recovered from the Middle-Upper Jurassic and Lower Cretaceous deposits of northeastern China, but most of them represent small animals. Here we report the discovery of a gigantic new basal tyrannosauroid, Yutyrannus huali gen. et sp. nov., based on three nearly complete skeletons representing two distinct ontogenetic stages from the Lower Cretaceous Yixian Formation of Liaoning Province, China. Y. huali shares some features, particularly of the cranium, with derived tyrannosauroids, but is similar to other basal tyrannosauroids in possessing a three-fingered manus and a typical theropod pes. Morphometric analysis suggests that Y. huali differed from tyrannosaurids in its growth strategy. Most significantly, Y. huali bears long filamentous feathers, thus providing direct evidence for the presence of extensively feathered gigantic dinosaurs and offering new insights into early feather evolution.

  5. Management of type 2 diabetes mellitus associated with pituitary gigantism.

    PubMed

    Ali, Omar; Banerjee, Swati; Kelly, Daniel F; Lee, Phillip D K

    2007-01-01

    Pituitary gigantism, a condition of endogenous growth hormone (GH) hypersecretion prior to epiphyseal closure, is a rare condition. In the adult condition of GH excess, acromegaly, the occurrence of type 2 diabetes mellitus (T2DM) and diabetic ketoacidosis (DKA) have been reported, with resolution following normalization of GH levels. We report the case of a 16-year-old male with pituitary gigantism due to a large invasive suprasellar adenoma who presented with T2DM and DKA. Despite surgical de-bulking, radiotherapy and medical treatment with cabergoline and pegvisomant, GH and insulin-like growth factor-I (IGF-I) levels remained elevated. However, the T2DM and recurrent DKA were successfully managed with metformin and low-dose glargine insulin, respectively. We review the pathophysiology of T2DM and DKA in growth hormone excess and available treatment options. PMID:17629784

  6. Metals bioaccumulation in two edible bivalves and health risk assessment.

    PubMed

    El-Shenawy, Nahla S; Loutfy, Naglaa; Soliman, Maha F M; Tadros, Menerva M; Abd El-Azeez, Ahmed A

    2016-03-01

    Our aim was to quantify the bioaccumulation of 13 metals in two edible bivalves (Ruditapes decussatus and Paphia undulata) in Lake Timsah, Egypt. A potential human health risk assessment was conducted to evaluate the hazards from bivalve consumption. Fe, Al, Zn, and Sr had the highest concentrations in the bivalve samples. The levels of Cd were much lower than the maximum permissible level, while Pb concentrations in the two bivalves were nearly two times the permissible level. The extent of bioaccumulation factor was site- and species-specific. For low and high bivalve-consuming groups, the estimated daily intake of Pb and Cd ranged from 0.01 to 0.76 μg/kg/day. For low and high bivalve-consuming groups, hazard quotients (HQs) for metals were found to be less than 1 for both bivalve species, except for Co in the high-consuming group. In conclusion, even though there was no apparent risk to bivalve consumers from being exposed to single metals, there is a risk from being exposed to the 13 studied metals together, especially for high bivalve-consuming groups such as fishermen.

  7. In-situ bioassays using caged bivalves

    SciTech Connect

    Salazar, M.H.; Salazar, S.M.

    1995-12-31

    It is important to make the distinction between chemical measurements to assess bioaccumulation potential versus biological measurements to assess potential bioeffects because bioaccumulation is not a bioeffect. Caging provides a unique opportunity to make synoptic measurements of each and facilitates making these measurements over space and time. Measuring bioaccumulation in resident and transplanted bivalves has probably been the most frequently used form of an in-situ bioassay because bivalves concentrate chemicals in their tissues. They are also easy to collect, cage, and measure. The authors have refined bivalve bioassay methods by minimizing the size range of test animals, making repetitive measurements of the same individuals, and standardizing test protocols for a variety of applications. They are now attempting to standardize criteria for accepting and interpreting data in the same way that laboratory bioassays have been standardized. Growth measurements can serve two purposes in this assessment strategy: (1) An integrated biological response endpoint that is easily quantifiable and with significance to the population, and (2) A means of calibrating bioaccumulation by assessing the relative health and physiological state of tissues that have accumulated the chemicals. In general, the authors have found the highest bioconcentration factors associated with the highest growth rates, the highest concentrations ({micro}g/g) of chemicals in juvenile mussels, and the highest chemical content ({micro}g/animal) in adult mussels. Without accounting for possible dilution of chemical concentrations by tissue growth or magnification through degrowth, contaminant concentrations can be misleading. Examples are provided for the Sudbury River in Massachusetts (Elliptio complanata), San Diego Bay (Mytilus galloprovincialis), and the Harbor Island Superfund Site in Puget Sound (Mytilus trossulus).

  8. Hereditary Gigantism-the biblical giant Goliath and his brothers.

    PubMed

    Donnelly, Deirdre E; Morrison, Patrick J

    2014-05-01

    The biblical giant Goliath has an identifiable family tree suggestive of autosomal dominant inheritance. We suggest that he had a hereditary pituitary disorder possibly due to the AIP gene, causing early onset and familial acromegaly or gigantism. We comment on the evidence within the scriptures for his other relatives including a relative with six digits and speculate on possible causes of the six digits. Recognition of a hereditary pituitary disorder in the biblical Goliath and his family sheds additional information on his and other family members' battles with David and his relatives.

  9. Proteus syndrome: A rare cause of gigantic limb.

    PubMed

    Chakrabarti, Nandini; Chattopadhyay, Chandan; Bhuban, Majhi; Pal, Salil Kumar

    2014-04-01

    A congenital disorder with variable manifestations, including partial gigantism of the hands and feet with hypertrophy of soles, nevi, hemihypertrophy, gynecomastia, macrocephaly and other skull abnormalities, and abdominal lipomatosis. The cause is unknown, although a genetic origin, generally of autosomal-dominant transmission, has been conjectured. Symptoms can be treated, but there is no known cure. We present the case of a young male with grotesque overgrowth of the right lower limb, splenomegaly and multiple nevi. Angiography revealed venous malformation within the limb. The findings are in conformity to the criteria for the Proteus syndrome. PMID:24860761

  10. Hereditary Gigantism-the biblical giant Goliath and his brothers

    PubMed Central

    Donnelly, Deirdre E; Morrison, Patrick J

    2014-01-01

    The biblical giant Goliath has an identifiable family tree suggestive of autosomal dominant inheritance. We suggest that he had a hereditary pituitary disorder possibly due to the AIP gene, causing early onset and familial acromegaly or gigantism. We comment on the evidence within the scriptures for his other relatives including a relative with six digits and speculate on possible causes of the six digits. Recognition of a hereditary pituitary disorder in the biblical Goliath and his family sheds additional information on his and other family members’ battles with David and his relatives. PMID:25075136

  11. Hereditary Gigantism-the biblical giant Goliath and his brothers.

    PubMed

    Donnelly, Deirdre E; Morrison, Patrick J

    2014-05-01

    The biblical giant Goliath has an identifiable family tree suggestive of autosomal dominant inheritance. We suggest that he had a hereditary pituitary disorder possibly due to the AIP gene, causing early onset and familial acromegaly or gigantism. We comment on the evidence within the scriptures for his other relatives including a relative with six digits and speculate on possible causes of the six digits. Recognition of a hereditary pituitary disorder in the biblical Goliath and his family sheds additional information on his and other family members' battles with David and his relatives. PMID:25075136

  12. The Oldest Recorded Case of Acromegaly and Gigantism in Iran.

    PubMed

    Najjari, Mohsen

    2015-10-01

    Here we commemorate the character and academic authority of Prof. Zabiholah Gorban (1903-2006), the founder of Shiraz medical school. No doubt, in the scope of history of contemporary medicine, he has been efficient and effective. With respect to this fact, his article on a rare case described in Acta anatomica published in Iran in 1966, entitled (Observations on a giant skeleton) is browsed and reviewed. A case named Siah Khan with combined acromegaly and gigantism that appears to have letters to say still after nearly half a century. PMID:26443258

  13. The Oldest Recorded Case of Acromegaly and Gigantism in Iran.

    PubMed

    Najjari, Mohsen

    2015-10-01

    Here we commemorate the character and academic authority of Prof. Zabiholah Gorban (1903-2006), the founder of Shiraz medical school. No doubt, in the scope of history of contemporary medicine, he has been efficient and effective. With respect to this fact, his article on a rare case described in Acta anatomica published in Iran in 1966, entitled (Observations on a giant skeleton) is browsed and reviewed. A case named Siah Khan with combined acromegaly and gigantism that appears to have letters to say still after nearly half a century.

  14. Cambrian bivalved arthropod reveals origin of arthrodization.

    PubMed

    Legg, David A; Sutton, Mark D; Edgecombe, Gregory D; Caron, Jean-Bernard

    2012-12-01

    Extant arthropods are diverse and ubiquitous, forming a major constituent of most modern ecosystems. Evidence from early Palaeozoic Konservat Lagerstätten indicates that this has been the case since the Cambrian. Despite this, the details of arthropod origins remain obscure, although most hypotheses regard the first arthropods as benthic predators or scavengers such as the fuxianhuiids or megacheirans ('great-appendage' arthropods). Here, we describe a new arthropod from the Tulip Beds locality of the Burgess Shale Formation (Cambrian, series 3, stage 5) that possesses a weakly sclerotized thorax with filamentous appendages, encased in a bivalved carapace, and a strongly sclerotized, elongate abdomen and telson. A cladistic analysis resolved this taxon as the basal-most member of a paraphyletic grade of nekto-benthic forms with bivalved carapaces. This grade occurs at the base of Arthropoda (panarthropods with arthropodized trunk limbs) and suggests that arthrodization (sclerotization and jointing of the exoskeleton) evolved to facilitate swimming. Predatory and fully benthic habits evolved later in the euarthropod stem-lineage and are plesiomorphically retained in pycnogonids (sea spiders) and euchelicerates (horseshoe crabs and arachnids). PMID:23055069

  15. Phylogeny and diversification patterns among vesicomyid bivalves.

    PubMed

    Decker, Carole; Olu, Karine; Cunha, Regina L; Arnaud-Haond, Sophie

    2012-01-01

    Vesicomyid bivalves are among the most abundant and diverse symbiotic taxa in chemosynthetic-based ecosystems: more than 100 different vesicomyid species have been described so far. In the present study, we investigated the phylogenetic positioning of recently described vesicomyid species from the Gulf of Guinea and their western Atlantic and Pacific counterparts using mitochondrial DNA sequence data. The maximum-likelihood (ML) tree provided limited support for the recent taxonomic revision of vesicomyids based on morphological criteria; nevertheless, most of the newly sequenced specimens did not cluster with their morphological conspecifics. Moreover, the observed lack of geographic clustering suggests the occurrence of independent radiations followed by worldwide dispersal. Ancestral character state reconstruction showed a significant correlation between the characters "depth" and "habitat" and the reconstructed ML phylogeny suggesting possible recurrent events of 'stepwise speciation' from shallow to deep waters in different ocean basins. This is consistent with genus or species bathymetric segregation observed from recent taxonomic studies. Altogether, our results highlight the need for ongoing re-evaluation of the morphological characters used to identify vesicomyid bivalves.

  16. Phylogeny and Diversification Patterns among Vesicomyid Bivalves

    PubMed Central

    Decker, Carole; Olu, Karine; Cunha, Regina L.; Arnaud-Haond, Sophie

    2012-01-01

    Vesicomyid bivalves are among the most abundant and diverse symbiotic taxa in chemosynthetic-based ecosystems: more than 100 different vesicomyid species have been described so far. In the present study, we investigated the phylogenetic positioning of recently described vesicomyid species from the Gulf of Guinea and their western Atlantic and Pacific counterparts using mitochondrial DNA sequence data. The maximum-likelihood (ML) tree provided limited support for the recent taxonomic revision of vesicomyids based on morphological criteria; nevertheless, most of the newly sequenced specimens did not cluster with their morphological conspecifics. Moreover, the observed lack of geographic clustering suggests the occurrence of independent radiations followed by worldwide dispersal. Ancestral character state reconstruction showed a significant correlation between the characters “depth” and “habitat” and the reconstructed ML phylogeny suggesting possible recurrent events of ‘stepwise speciation’ from shallow to deep waters in different ocean basins. This is consistent with genus or species bathymetric segregation observed from recent taxonomic studies. Altogether, our results highlight the need for ongoing re-evaluation of the morphological characters used to identify vesicomyid bivalves. PMID:22511920

  17. Nutritional strategies of the hydrothermal ecosystem bivalves

    NASA Astrophysics Data System (ADS)

    Le Pennec, Marcel; Donval, Anne; Herry, Angèle

    Studies of deep-sea hydrothermal bivalves have revealed that the species, which are strictly dependent upon the interstitial fluid emissions, derive their food indirectly via symbiotic relationships with chemosynthetic bacteria present in their gill tissues. As the gill plays the main trophic role, structural and ultrastructural modifications occur in the digestive tract. Scanning and transmission electron microscope studies reveal that the digestive system of species belonging to the genera Calyptogena, Bathymodiolus and Bathypecten have anatomical differences. In Calyptogena, the reduction of several parts of the digestive tract and the stomach content which is either empty or full, according to the various species examined indicate that the digestive system is hardly if at all functional. In Bathymodiolus, the labial palps are well developed, the stomach is always full with particles and the two cellular types, digestive and secretory, are present in the digestive gland. All these characteristics indicate that the digestive system is functional. In Bathypecten, the digestive tract is well developed and it seems that it plays the main trophic role. We conclude that the nutritional strategies of the hydrothermal vents bivalves are quite varied. They range from a normal trophic process, through a mixotrophic diet, to one based purely on chemoautotrophic bacteria. The strategy of each species is adapted to and influences its distribution.

  18. Cambrian bivalved arthropod reveals origin of arthrodization

    PubMed Central

    Legg, David A.; Sutton, Mark D.; Edgecombe, Gregory D.; Caron, Jean-Bernard

    2012-01-01

    Extant arthropods are diverse and ubiquitous, forming a major constituent of most modern ecosystems. Evidence from early Palaeozoic Konservat Lagerstätten indicates that this has been the case since the Cambrian. Despite this, the details of arthropod origins remain obscure, although most hypotheses regard the first arthropods as benthic predators or scavengers such as the fuxianhuiids or megacheirans (‘great-appendage’ arthropods). Here, we describe a new arthropod from the Tulip Beds locality of the Burgess Shale Formation (Cambrian, series 3, stage 5) that possesses a weakly sclerotized thorax with filamentous appendages, encased in a bivalved carapace, and a strongly sclerotized, elongate abdomen and telson. A cladistic analysis resolved this taxon as the basal-most member of a paraphyletic grade of nekto-benthic forms with bivalved carapaces. This grade occurs at the base of Arthropoda (panarthropods with arthropodized trunk limbs) and suggests that arthrodization (sclerotization and jointing of the exoskeleton) evolved to facilitate swimming. Predatory and fully benthic habits evolved later in the euarthropod stem-lineage and are plesiomorphically retained in pycnogonids (sea spiders) and euchelicerates (horseshoe crabs and arachnids). PMID:23055069

  19. Dynamics of sheet nacre formation in bivalves.

    PubMed

    Rousseau, Marthe; Meibom, Anders; Gèze, Marc; Bourrat, Xavier; Angellier, Martine; Lopez, Evelyne

    2009-03-01

    Formation of nacre (mother-of-pearl) is a biomineralization process of fundamental scientific as well as industrial importance. However, the dynamics of the formation process is still not understood. Here, we use scanning electron microscopy and high spatial resolution ion microprobe depth-profiling to image the full three-dimensional distribution of organic materials around individual tablets in the top-most layer of forming nacre in bivalves. Nacre formation proceeds by lateral, symmetric growth of individual tablets mediated by a growth-ring rich in organics, in which aragonite crystallizes from amorphous precursors. The pivotal role in nacre formation played by the growth-ring structure documented in this study adds further complexity to a highly dynamical biomineralization process.

  20. Phylogenetic conservatism of extinctions in marine bivalves.

    PubMed

    Roy, Kaustuv; Hunt, Gene; Jablonski, David

    2009-08-01

    Evolutionary histories of species and lineages can influence their vulnerabilities to extinction, but the importance of this effect remains poorly explored for extinctions in the geologic past. When analyzed using a standardized taxonomy within a phylogenetic framework, extinction rates of marine bivalves estimated from the fossil record for the last approximately 200 million years show conservatism at multiple levels of evolutionary divergence, both within individual families and among related families. The strength of such phylogenetic clustering varies over time and is influenced by earlier extinction history, especially by the demise of volatile taxa in the end-Cretaceous mass extinction. Analyses of the evolutionary roles of ancient extinctions and predictive models of vulnerability of taxa to future natural and anthropogenic stressors should take phylogenetic relationships and extinction history into account.

  1. Hemocyanin respiratory pigment in bivalve mollusks

    SciTech Connect

    Morse, M.P.; Meyhoefer, E.; Otto, J.J.; Kuzirian, A.M.

    1986-03-14

    Hemocyanins, high molecular weight oxygen-binding proteins, were identified in two species of protobranch bivalve mollusks, Acila castrensis and Yoldia limatula. Although hemocyanins have been reported in chitons, gastropods, and cephalopods, they have not been observed in the Class Bivalvia. In A. castrensis the dissociation products of hemocyanin, characterized by gel electrophoresis, had a subunit molecular weight of approximately 250K. Negatively stained preparations of extracted hemocyanin formed protein aggregates in the shape of cylinders measuring 35 by 38 nanometers. X-ray microanalysis of hemocyanin aggregates in thin sections of Y. limatula demonstrated the presence of copper in the molecules. The discovery of hemocyanin in the protobranchs reinforces the primitive nature of the taxon and is further evidence that the major molluscan classes have a common ancestry. 14 references, 3 figures.

  2. Avian-style respiration allowed gigantism in pterosaurs.

    PubMed

    Ruxton, Graeme

    2014-08-01

    Powered flight has evolved three times in the vertebrates: in the birds, the bats and the extinct pterosaurs. The largest bats ever known are at least an order of magnitude smaller than the largest members of the other two groups. Recently, it was argued that different scaling of wingbeat frequencies to body mass in birds and bats can help explain why the largest birds are larger than the largest bats. Here, I extend this argument in two ways. Firstly, I suggest that different respiratory physiologies are key to understanding the restriction on bat maximum size compared with birds. Secondly, I argue that a respiratory physiology similar to birds would have been a prerequisite for the gigantism seen in pterosaurs. PMID:24855669

  3. Avian-style respiration allowed gigantism in pterosaurs.

    PubMed

    Ruxton, Graeme

    2014-08-01

    Powered flight has evolved three times in the vertebrates: in the birds, the bats and the extinct pterosaurs. The largest bats ever known are at least an order of magnitude smaller than the largest members of the other two groups. Recently, it was argued that different scaling of wingbeat frequencies to body mass in birds and bats can help explain why the largest birds are larger than the largest bats. Here, I extend this argument in two ways. Firstly, I suggest that different respiratory physiologies are key to understanding the restriction on bat maximum size compared with birds. Secondly, I argue that a respiratory physiology similar to birds would have been a prerequisite for the gigantism seen in pterosaurs.

  4. Immunotoxicological effects of environmental contaminants on marine bivalves.

    PubMed

    Renault, T

    2015-09-01

    Coastal areas are complex environments frequently contaminated by numerous pollutants that represent a potential threat to marine organisms, especially bivalves. These pollutants may have major ecological consequences. Although effects of different environmental contaminants on the immune system in marine bivalves have been already reported, a few of reviews summarizes these effects. The main purpose of this chapter relies on summarizing recent body of data on immunotoxicity in bivalves subjected to contaminants. Immune effects of heavy metals, pesticides, HAP, PCB and pharmaceuticals are presented and discussed and a particular section is devoted to nanoparticle effects. A large body of literature is now available on this topic. Finally, the urgent need of a better understanding of complex interactions between contaminants, marine bivalves and infectious diseases is noticed.

  5. Gigantism caused by growth hormone secreting pituitary adenoma.

    PubMed

    Rhee, Noorisaem; Jeong, Kumi; Yang, Eun Mi; Kim, Chan Jong

    2014-06-01

    Gigantism indicates excessive secretion of growth hormones (GH) during childhood when open epiphyseal growth plates allow for excessive linear growth. Case one involved a 14.7-year-old boy presented with extreme tall stature. His random serum GH level was 38.4 ng/mL, and failure of GH suppression was noted during an oral glucose tolerance test (OGTT; nadir serum GH, 22.7 ng/mL). Magnetic resonance imaging (MRI) of the brain revealed a 12-mm-sized pituitary adenoma. Transsphenoidal surgery was performed and a pituitary adenoma displaying positive immunohistochemical staining for GH was reported. Pituitary MRI scan was performed 4 months after surgery and showed recurrence/residual tumor. Medical treatment with a long-acting somatostatin analogue for six months was unsuccessful. As a result, secondary surgery was performed. Three months after reoperation, the GH level was 0.2 ng/mL and insulin-like growth factor 1 was 205 ng/mL. Case two involved a 14.9-year-old boy, who was referred to our department for his tall stature. His basal GH level was 9.3 ng/mL, and failure of GH suppression was reported during OGTT (nadir GH, 9.0 ng/mL). Pituitary MRI showed a 6-mm-sized pituitary adenoma. Surgery was done and histopathological examination demonstrated a pituitary adenoma with positive staining for GH. Three months after surgery, the GH level was 0.2 ng/mL and nadir GH during OGTT was less than 0.1 ng/mL. Pituitary MRI scans showed no residual tumor. We present two cases of gigantism caused by a GH-secreting pituitary adenoma with clinical and microscopic findings. PMID:25077093

  6. Methodology of growing gigantic sapphire for GSLW project

    NASA Astrophysics Data System (ADS)

    Abgaryan, Artoush A.; Hartounian, Gomidas

    2005-09-01

    In our present world the Crystal Growth Technology does not have the necessary and sufficient conditions to manufacture large sizes; especially in the Sapphire Crystal world. We have a theoretical and methodological development for growing gigantic Sapphire Crystal Lenses. Our gigantic Sapphire Crystal Lenses have a unique optical characteristic which will be used in the Global System of Laser Weapons (GSLW); hence solving one of the crucial problems in the Relay Mirror System; where it captures the Laser beam from the earth surface, cleaning the beam in the Satellite and redirecting the laser energy to the precise desired target. Developed and solution for the temperature and heat-elasticity fields in growth systems are considered theoretical, in order to assess their effects on the optical symmetry of the growing crystal. The process is modeled using three-dimensional curvilinear coordinates to describe a closed, low-strain heat-elasticity system, with allowance made for the temperature variations of the thermal properties of the multilayer growth system, and nonlinear and unsteady-state process with arbitrary boundary conditions. The results presented as plots of the strain, stress, displacement, and temperature fields; demonstrate the potential of the method for designing new growth units and improving the existing ones and suggesting that crystals, in general, without frustration of optical symmetry can, in principle, be grown. In order to solve generalized problem for large optics. It is required to have super and correct mathematical computing calculations, and using basic fundamental laws of nature regarding optical symmetry in the crystal, and discovering the radical "new wave method" for crystal growth technology.

  7. Gigantism caused by growth hormone secreting pituitary adenoma

    PubMed Central

    Rhee, Noorisaem; Jeong, Kumi; Yang, Eun Mi

    2014-01-01

    Gigantism indicates excessive secretion of growth hormones (GH) during childhood when open epiphyseal growth plates allow for excessive linear growth. Case one involved a 14.7-year-old boy presented with extreme tall stature. His random serum GH level was 38.4 ng/mL, and failure of GH suppression was noted during an oral glucose tolerance test (OGTT; nadir serum GH, 22.7 ng/mL). Magnetic resonance imaging (MRI) of the brain revealed a 12-mm-sized pituitary adenoma. Transsphenoidal surgery was performed and a pituitary adenoma displaying positive immunohistochemical staining for GH was reported. Pituitary MRI scan was performed 4 months after surgery and showed recurrence/residual tumor. Medical treatment with a long-acting somatostatin analogue for six months was unsuccessful. As a result, secondary surgery was performed. Three months after reoperation, the GH level was 0.2 ng/mL and insulin-like growth factor 1 was 205 ng/mL. Case two involved a 14.9-year-old boy, who was referred to our department for his tall stature. His basal GH level was 9.3 ng/mL, and failure of GH suppression was reported during OGTT (nadir GH, 9.0 ng/mL). Pituitary MRI showed a 6-mm-sized pituitary adenoma. Surgery was done and histopathological examination demonstrated a pituitary adenoma with positive staining for GH. Three months after surgery, the GH level was 0.2 ng/mL and nadir GH during OGTT was less than 0.1 ng/mL. Pituitary MRI scans showed no residual tumor. We present two cases of gigantism caused by a GH-secreting pituitary adenoma with clinical and microscopic findings. PMID:25077093

  8. Gigantism caused by growth hormone secreting pituitary adenoma.

    PubMed

    Rhee, Noorisaem; Jeong, Kumi; Yang, Eun Mi; Kim, Chan Jong

    2014-06-01

    Gigantism indicates excessive secretion of growth hormones (GH) during childhood when open epiphyseal growth plates allow for excessive linear growth. Case one involved a 14.7-year-old boy presented with extreme tall stature. His random serum GH level was 38.4 ng/mL, and failure of GH suppression was noted during an oral glucose tolerance test (OGTT; nadir serum GH, 22.7 ng/mL). Magnetic resonance imaging (MRI) of the brain revealed a 12-mm-sized pituitary adenoma. Transsphenoidal surgery was performed and a pituitary adenoma displaying positive immunohistochemical staining for GH was reported. Pituitary MRI scan was performed 4 months after surgery and showed recurrence/residual tumor. Medical treatment with a long-acting somatostatin analogue for six months was unsuccessful. As a result, secondary surgery was performed. Three months after reoperation, the GH level was 0.2 ng/mL and insulin-like growth factor 1 was 205 ng/mL. Case two involved a 14.9-year-old boy, who was referred to our department for his tall stature. His basal GH level was 9.3 ng/mL, and failure of GH suppression was reported during OGTT (nadir GH, 9.0 ng/mL). Pituitary MRI showed a 6-mm-sized pituitary adenoma. Surgery was done and histopathological examination demonstrated a pituitary adenoma with positive staining for GH. Three months after surgery, the GH level was 0.2 ng/mL and nadir GH during OGTT was less than 0.1 ng/mL. Pituitary MRI scans showed no residual tumor. We present two cases of gigantism caused by a GH-secreting pituitary adenoma with clinical and microscopic findings.

  9. Geography of end-Cretaceous marine bivalve extinctions.

    PubMed

    Raup, D M; Jablonski, D

    1993-05-14

    Analysis of the end-Cretaceous mass extinction, based on 3514 occurrences of 340 genera of marine bivalves (Mollusca), suggests that extinction intensities were uniformly global; no latitudinal gradients or other geographic patterns are detected. Elevated extinction intensities in some tropical areas are entirely a result of the distribution of one extinct group of highly specialized bivalves, the rudists. When rudists are omitted, intensities at those localities are statistically indistinguishable from those of both the rudist-free tropics and extratropical localities.

  10. Geography of end-Cretaceous marine bivalve extinctions

    NASA Technical Reports Server (NTRS)

    Raup, David M.; Jablonski, David

    1993-01-01

    Analysis of the end-Cretaceous mass extinction, based on 3514 occurrences of 340 genera of marine bivalves (Mollusca), suggests that extinction intensities were uniformly global; no latitudinal gradients or other geographic patterns are detected. Elevated extinction intensities in some tropical areas are entirely a result of the distribution of one extinct group of highly specialized bivalves, the rudists. When rudists are omitted, intensities at those localities are statistically indistinguishable from those of both the rudist-free tropics and extratropical localities.

  11. Ecological drivers and habitat associations of estuarine bivalves

    PubMed Central

    Tunberg, Björn G.; Johnston, Cora A.; Barshis, Daniel J.

    2015-01-01

    Community composition of the infaunal bivalve fauna of the St. Lucie Estuary and southern Indian River Lagoon, eastern Florida was sampled quarterly for 10 years as part of a long-term benthic monitoring program. A total of 38,514 bivalves of 137 taxa were collected and identified. We utilized this data, along with sediment samples and environmental measurements gathered concurrently, to assess the community composition, distribution, and ecological drivers of the infaunal bivalves of this estuary system. Salinity had the strongest influence on bivalve assemblage across the 15 sites, superseding the influences of sediment type, water turbidity, temperature and other environmental parameters. The greatest diversity was found in higher salinity euhaline sites, while the greatest abundance of individual bivalves was found in medium salinity mixohaline sites, the lowest diversity and abundances were found in the low salinity oligohaline sites, demonstrating a strong positive association between salinity and diversity/abundance. Water management decisions for the estuary should incorporate understanding of the role of salinity on bivalve diversity, abundance, and ecosystem function. PMID:26587338

  12. Isotopic fingerprints of bacterial chemosymbiosis in the bivalve Loripes lacteus

    NASA Astrophysics Data System (ADS)

    Dreier, A.; Stannek, L.; Blumenberg, M.; Taviani, M.; Sigovini, M.; Wrede, C.; Thiel, V.; Hoppert, M.

    2012-04-01

    Metazoans with chemosynthetic bacterial endosymbionts are widespread in marine habitats and respective endosymbioses are known from seven recent animal phyla. However, little is known about endosymbioses in fossil settings and, hence, ecological significance in earth history. In the presented project, we investigate the ancient and recent bivalve fauna living at marine sedimentary oxic/anoxic interfaces. Two bivalve species collected from the same benthic environment - a Mediterranean lagoon - were studied in detail. The diet of Loripes lacteus is based on thiotrophic gill symbionts whereas Venerupis aureus is a filter feeding bivalve without symbionts. The presence of three key enzymes from sulfur oxidation (APS-reductase), carbon fixation (RubisCO) and assimilation of nitrogen (glutamine synthetase [GS]) were detected by immunofluorescence in symbionts of Loripes and/or by activity tests in living specimens. In search of biosignatures associated with thiotrophic chemosymbionts that might be suitable for detection of chemosymbiotic diets in recent and fossil bivalve shells, we analyzed the isotopic composition of shell lipids (δ13C) and the bulk organic matrix of the shell (δ13C, δ15N, δ34S). We could show that the combined δ15N and δ13C values from shell extracts are stable in subfossil (Pleistocene) bivalve specimens, as long as the isotopic data is "calibrated" with respective signatures from a filter feeding bivalve sampled from the same site or lithostratigraphic bed.

  13. Bivalves: From individual to population modelling

    NASA Astrophysics Data System (ADS)

    Saraiva, S.; van der Meer, J.; Kooijman, S. A. L. M.; Ruardij, P.

    2014-11-01

    An individual based population model for bivalves was designed, built and tested in a 0D approach, to simulate the population dynamics of a mussel bed located in an intertidal area. The processes at the individual level were simulated following the dynamic energy budget theory, whereas initial egg mortality, background mortality, food competition, and predation (including cannibalism) were additional population processes. Model properties were studied through the analysis of theoretical scenarios and by simulation of different mortality parameter combinations in a realistic setup, imposing environmental measurements. Realistic criteria were applied to narrow down the possible combination of parameter values. Field observations obtained in the long-term and multi-station monitoring program were compared with the model scenarios. The realistically selected modeling scenarios were able to reproduce reasonably the timing of some peaks in the individual abundances in the mussel bed and its size distribution but the number of individuals was not well predicted. The results suggest that the mortality in the early life stages (egg and larvae) plays an important role in population dynamics, either by initial egg mortality, larvae dispersion, settlement failure or shrimp predation. Future steps include the coupling of the population model with a hydrodynamic and biogeochemical model to improve the simulation of egg/larvae dispersion, settlement probability, food transport and also to simulate the feedback of the organisms' activity on the water column properties, which will result in an improvement of the food quantity and quality characterization.

  14. Microplastics in bivalves cultured for human consumption.

    PubMed

    Van Cauwenberghe, Lisbeth; Janssen, Colin R

    2014-10-01

    Microplastics are present throughout the marine environment and ingestion of these plastic particles (<1 mm) has been demonstrated in a laboratory setting for a wide array of marine organisms. Here, we investigate the presence of microplastics in two species of commercially grown bivalves: Mytilus edulis and Crassostrea gigas. Microplastics were recovered from the soft tissues of both species. At time of human consumption, M. edulis contains on average 0.36 ± 0.07 particles g(-1) (wet weight), while a plastic load of 0.47 ± 0.16 particles g(-1) ww was detected in C. gigas. As a result, the annual dietary exposure for European shellfish consumers can amount to 11,000 microplastics per year. The presence of marine microplastics in seafood could pose a threat to food safety, however, due to the complexity of estimating microplastic toxicity, estimations of the potential risks for human health posed by microplastics in food stuffs is not (yet) possible.

  15. Analysis of marine bivalves and sediments

    SciTech Connect

    Zeisler, R.; Stone, S.F.

    1986-01-01

    Recently, environmental monitoring has been complemented by programs for systematic and controlled long-term storage of environmental samples; i.e., environmental specimen banking (ESB). In the US a pilot ESB program is currently expanding to become past of several environmental and human health monitoring projects. The National Status and Trends (NS and T) program on the marine environment, administrated by the National Oceanic and Atmospheric Administration (NOAA), is one of these projects and has initialized new investigations within the ESB research program. This research includes all steps of the ESB operation, with special emphasis on quality assurance in the selection, collection, preparation, storage, and analysis of marine samples according to validated procedures. A unique sequence of instrumental analytical methods involving x-ray fluorescence and neutron activation analysis procedures has been employed for the determination of 44 elements in marine bivalves. The individual procedures are an x-ray fluorescence method based on backscatter with fundamental parameter corrections, prompt gamma activation analysis, and neutron activation analysis with instrumental and radiochemical procedures. This analytical approach has been expanded to include the analysis of sediments and fish tissues.

  16. Burrowing behaviour of robotic bivalves with synthetic morphologies.

    PubMed

    Germann, D P; Carbajal, J P

    2013-12-01

    Several bivalve species burrow into sandy sediments to reach their living position. There are many hypotheses concerning the functional morphology of the bivalve shell for burrowing. Observational studies are limited and often qualitative and should be complemented by a synthetic approach mimicking the burrowing process using a robotic emulation. In this paper we present a simple mechatronic set-up to mimic the burrowing behaviour of bivalves. As environment we used water and quartz sand contained in a glass tank. Bivalve shells were mathematically modelled on the computer and then materialized using a 3D printer. The burrowing motion of the shells was induced by two external linear motors. Preliminary experiments did not expose any artefacts introduced to the burrowing process by the set-up. We tested effects of shell size, shape and surface sculpturing on the burrowing performance. Neither the typical bivalve shape nor surface sculpture did have a clear positive effect on burrowing depth in the performed experiments. We argue that the presented method is a valid and promising approach to investigate the functional morphology of bivalve shells and should be improved and extended in future studies. In contrast to the observation of living bivalves, our approach offers complete control over the parameters defining shell morphology and motion pattern. The technical set-up allows the systematic variation of all parameters to quantify their effects. The major drawback of the built set-up was that the reliability and significance of the results was limited by the lack of an optimal technique to standardize the sediment state before experiments.

  17. Marine diatoms sustain growth of bivalves in a Mediterranean lagoon

    NASA Astrophysics Data System (ADS)

    Pernet, Fabrice; Malet, Nathalie; Pastoureaud, Annie; Vaquer, André; Quéré, Claudie; Dubroca, Laurent

    2012-02-01

    Carbon stable isotopes and fatty acids were measured in the suspended particulate organic matter (POM) of the Thau lagoon to study its qualitative temporal changes in relation to environmental factors and to identify the food sources of bivalves over a one-yr-cycle in relation to their growth. Reciprocally, the impact of shellfish farming on POM was also studied. Oysters and mussels were sampled and measured for biometry, stable isotopes and fatty acid composition. Water samples were collected at two sites, both inside and outside of the shellfish farming area, to determine concentrations in POM, chlorophyll a (Chl a) and stable isotopes. Carbon isotopes and fatty acids in bivalves reflected seasonal changes in food sources, which varied consistently with the environment. Seasonal changes in δ13C and fatty acids in the bivalves suggested that dietary phytoplankton contribution varied according to season. Terrestrial organic matter and bacteria can contribute to the diet of bivalves during non-bloom periods. Mussels seemed to rely more on diatoms and less on terrestrial organic matter and bacteria than oysters did, particularly when phytoplankton biomass was low during the summer. Although one- and two-yr-old oysters showed similar δ13C, their fatty acid dynamics differed slightly. Periods of high growth rate in bivalves were mainly fuelled by diatoms, thus highlighting the importance of seasonal blooms of microphytoplankton during the critical period of bivalve growth and gamete production. Although there was no significant effect of shellfish farms on Chl a and POM δ13C, consistent differences indicate that stable isotopes could be used successfully to investigate the effects of bivalve aquaculture.

  18. Metabolites of saxitoxin analogues in bivalves contaminated by Gymnodinium catenatum.

    PubMed

    Vale, Paulo

    2010-01-01

    Bivalve metabolites of saxitoxin analogues, not present in microalgae, were recently described as an important toxin fraction in mussels contaminated by Alexandrium tamarense. These possess very low fluorescence, and require mass spectrometry detection. HILIC-MS was implemented to look for these metabolites in bivalves contaminated during Gymnodinium catenatum blooms at the Portuguese coast. The presence of M1 was tentatively identified in several bivalves, ranging from estuarine (Mytilus galloprovinciallis, Cerastoderma edule and Ruditapes decussatus) to oceanic habitat (Donax trunculus and Ensis spp.). It was hypothesized that M1 could contribute to an important fraction of the profile of STX analogues. M1 was more abundant in estuarine bivalves that retain longer PSP toxins, in the following order: mussels>cockles>clams. These data highlight that the study by fluorimetry alone of the carbamoyl, N-sulfocarbamoyl, and decarbamoyl families is manifestly insufficient to fully understand toxin dynamics in bivalves feeding on G. catenatum without a proper study of hydroxybenzoate and hydroxylated M-toxins.

  19. Atmospheric oxygen and the evolution of insect gigantism

    NASA Astrophysics Data System (ADS)

    Dudley, R.

    2003-04-01

    Geophysical analyses suggest the presence of a late Paleozoic oxygen pulse beginning in the late Devonian and continuing through to the late Carboniferous. During this time, atmospheric oxygen levels increased to values potentially as high as 35% relative to the contemporary value of 21%. Widespread gigantism in late Paleozoic insects and other arthropods is consistent with enhanced oxygen flux within diffusion-limited tracheal systems, and thus with relaxation of constraints on maximum insect body size. Because total atmospheric pressure increases with increased oxygen partial pressure, concurrently hyperdense conditions would have augmented aerodynamic force production in early forms of flying insects. Hyperoxia of the late Paleozoic atmosphere may also have physiologically facilitated the initial evolution of insect flight metabolism. By the late Permian, evolution of decompositional microbial and fungal communities together with disequilibrium in rates of carbon deposition gradually reduced oxygen concentrations to values possibly as low as 15%. The disappearance of giant insects by the end of the Permian is consistent with extinction of these taxa for reasons of asphyxiation on a geological time scale. In modern selection experiments with Drosophila flies, substantial plasticity in body size can be evoked under conditions of variable oxygen. In particular, moderate hyperbaria (and thus hyperoxia) evokes a 20% increase in adult body size over merely five generations, suggesting ready capacity for evolutionary responses by insects to fluctuating atmospheric oxygen.

  20. Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs.

    PubMed

    Erickson, Gregory M; Makovicky, Peter J; Currie, Philip J; Norell, Mark A; Yerby, Scott A; Brochu, Christopher A

    2004-08-12

    How evolutionary changes in body size are brought about by variance in developmental timing and/or growth rates (also known as heterochrony) is a topic of considerable interest in evolutionary biology. In particular, extreme size change leading to gigantism occurred within the dinosaurs on multiple occasions. Whether this change was brought about by accelerated growth, delayed maturity or a combination of both processes is unknown. A better understanding of relationships between non-avian dinosaur groups and the newfound capacity to reconstruct their growth curves make it possible to address these questions quantitatively. Here we study growth patterns within the Tyrannosauridae, the best known group of large carnivorous dinosaurs, and determine the developmental means by which Tyrannosaurus rex, weighing 5,000 kg and more, grew to be one of the most enormous terrestrial carnivorous animals ever. T. rex had a maximal growth rate of 2.1 kg d(-1), reached skeletal maturity in two decades and lived for up to 28 years. T. rex's great stature was primarily attained by accelerating growth rates beyond that of its closest relatives.

  1. [Active acromegaly and gigantism: some clinical characteristics of 50 patients].

    PubMed

    Pumarino, H; Oviedo, S; Michelsen, H; Campino, C

    1991-08-01

    50 patients with autonomous growth hormone excess (48 with adult acromegaly and 2 with gigantism) were studied between 1966 to 1986 (2.38 pts/year). Characteristic clinical presentation, an increase in growth hormone (GH) uninhibited by glucose, and/or hyperphosphemia and hyperhydroxiprolinuria were present in all patients. No cases of hypercalcemia were recorded. Phosphemia was increased in 55.8%, alkaline phosphatases in 61.7%, calciuria in 26.9% and hydroxyprolinuria in 74.2% of the patients. Basal GH was over 5 ng/ml (89.9 DS +/- 170.9) in 42 pts, and in 37 was not suppressed after glucose administration, 38% had an increased (paradoxical response) and 62% a flat response (less than 50% change of basal values). TRH test was performed in 14 patients, 8 presented an increase in GH titer. Hyperprolactinemia was seen in 4 of 12 patients in whom this hormone was measured. The size of the sella turcica was increased in 93%, and although the larger sellar size correlated to higher levels of GH, correlation was not significant. 20% of the pts had rheumatological disease, 14% goiter, 12% cardiac disease, 26.5% had diastolic hypertension and 4% renal lithiasis (hypercalciuric pts). 38% had hyperglycemia with a diabetic glucose tolerance test and 18% had non-diabetic abnormal glucose tolerance test. PMID:1844771

  2. Gigantic Surface Lifetime of an Intrinsic Topological Insulator

    NASA Astrophysics Data System (ADS)

    Neupane, Madhab; Xu, Su-Yang; Ishida, Yukiaki; Jia, Shuang; Fregoso, Benjamin M.; Liu, Chang; Belopolski, Ilya; Bian, Guang; Alidoust, Nasser; Durakiewicz, Tomasz; Galitski, Victor; Shin, Shik; Cava, Robert J.; Hasan, M. Zahid

    2015-09-01

    The interaction between light and novel two-dimensional electronic states holds promise to realize new fundamental physics and optical devices. Here, we use pump-probe photoemission spectroscopy to study the optically excited Dirac surface states in the bulk-insulating topological insulator Bi2Te2Se and reveal optical properties that are in sharp contrast to those of bulk-metallic topological insulators. We observe a gigantic optical lifetime exceeding 4 μ s (1 μ s =10-6 s ) for the surface states in Bi2Te2Se , whereas the lifetime in most topological insulators, such as Bi2Se3 , has been limited to a few picoseconds (1 ps =10-12 s ). Moreover, we discover a surface photovoltage, a shift of the chemical potential of the Dirac surface states, as large as 100 mV. Our results demonstrate a rare platform to study charge excitation and relaxation in energy and momentum space in a two-dimensional system.

  3. Classifying bivalve larvae using shell pigments identified by Raman spectroscopy.

    PubMed

    Thompson, Christine M; North, Elizabeth W; Kennedy, Victor S; White, Sheri N

    2015-05-01

    Because bivalve larvae are difficult to identify using morphology alone, the use of Raman spectra to distinguish species could aid classification of larvae collected from the field. Raman spectra from shells of bivalve larvae exhibit bands that correspond to polyene pigments. This study determined if the types of shell pigments observed in different species could be unique enough to differentiate larvae using chemotaxonomic methods and cluster analysis. We collected Raman spectra at three wavelengths from 25 samples of bivalve larvae representing 16 species and four taxonomic orders. Grouping spectra within general categories based on order/family relationships successfully classified larvae with cross-validation accuracies ≥92% for at least one wavelength or for all wavelengths combined. Classifications to species were more difficult, but cross-validation accuracies above 86% were observed for 7 out of 14 species when tested using species groups within orders/families at 785 nm. The accuracy of the approach likely depends on the composition of species in a sample and the species of interest. For example, high classification accuracies (85-98%) for distinguishing spectra from Crassostrea virginica larvae were achieved with a set of bivalve larvae occurring in the Choptank River in the Chesapeake Bay, USA, whereas as lower accuracies (70-92%) were found for a set of C. virginica larvae endemic to the Northeast, USA. In certain systems, use of Raman spectra appears to be a promising method for assessing the presence of certain bivalves in field samples and for validating high-throughput image analysis systems for larval bivalve studies. PMID:25757826

  4. Why might they be giants? Towards an understanding of polar gigantism.

    PubMed

    Moran, Amy L; Woods, H Arthur

    2012-06-15

    Beginning with the earliest expeditions to the poles, over 100 years ago, scientists have compiled an impressive list of polar taxa whose body sizes are unusually large. This phenomenon has become known as 'polar gigantism'. In the intervening years, biologists have proposed a multitude of hypotheses to explain polar gigantism. These hypotheses run the gamut from invoking release from physical and physiological constraints, to systematic changes in developmental trajectories, to community-level outcomes of broader ecological and evolutionary processes. Here we review polar gigantism and emphasize two main problems. The first is to determine the true strength and generality of this pattern: how prevalent is polar gigantism across taxonomic units? Despite many published descriptions of polar giants, we still have a poor grasp of whether these species are unusual outliers or represent more systematic shifts in distributions of body size. Indeed, current data indicate that some groups show gigantism at the poles whereas others show nanism. The second problem is to identify underlying mechanisms or processes that could drive taxa, or even just allow them, to evolve especially large body size. The contenders are diverse and no clear winner has yet emerged. Distinguishing among the contenders will require better sampling of taxa in both temperate and polar waters and sustained efforts by comparative physiologists and evolutionary ecologists in a strongly comparative framework.

  5. Biology of the sauropod dinosaurs: the evolution of gigantism

    PubMed Central

    Sander, P Martin; Christian, Andreas; Clauss, Marcus; Fechner, Regina; Gee, Carole T; Griebeler, Eva-Maria; Gunga, Hanns-Christian; Hummel, Jürgen; Mallison, Heinrich; Perry, Steven F; Preuschoft, Holger; Rauhut, Oliver W M; Remes, Kristian; Tütken, Thomas; Wings, Oliver; Witzel, Ulrich

    2011-01-01

    The herbivorous sauropod dinosaurs of the Jurassic and Cretaceous periods were the largest terrestrial animals ever, surpassing the largest herbivorous mammals by an order of magnitude in body mass. Several evolutionary lineages among Sauropoda produced giants with body masses in excess of 50 metric tonnes by conservative estimates. With body mass increase driven by the selective advantages of large body size, animal lineages will increase in body size until they reach the limit determined by the interplay of bauplan, biology, and resource availability. There is no evidence, however, that resource availability and global physicochemical parameters were different enough in the Mesozoic to have led to sauropod gigantism. We review the biology of sauropod dinosaurs in detail and posit that sauropod gigantism was made possible by a specific combination of plesiomorphic characters (phylogenetic heritage) and evolutionary innovations at different levels which triggered a remarkable evolutionary cascade. Of these key innovations, the most important probably was the very long neck, the most conspicuous feature of the sauropod bauplan. Compared to other herbivores, the long neck allowed more efficient food uptake than in other large herbivores by covering a much larger feeding envelope and making food accessible that was out of the reach of other herbivores. Sauropods thus must have been able to take up more energy from their environment than other herbivores. The long neck, in turn, could only evolve because of the small head and the extensive pneumatization of the sauropod axial skeleton, lightening the neck. The small head was possible because food was ingested without mastication. Both mastication and a gastric mill would have limited food uptake rate. Scaling relationships between gastrointestinal tract size and basal metabolic rate (BMR) suggest that sauropods compensated for the lack of particle reduction with long retention times, even at high uptake rates. The

  6. Biology of the sauropod dinosaurs: the evolution of gigantism.

    PubMed

    Sander, P Martin; Christian, Andreas; Clauss, Marcus; Fechner, Regina; Gee, Carole T; Griebeler, Eva-Maria; Gunga, Hanns-Christian; Hummel, Jürgen; Mallison, Heinrich; Perry, Steven F; Preuschoft, Holger; Rauhut, Oliver W M; Remes, Kristian; Tütken, Thomas; Wings, Oliver; Witzel, Ulrich

    2011-02-01

    The herbivorous sauropod dinosaurs of the Jurassic and Cretaceous periods were the largest terrestrial animals ever, surpassing the largest herbivorous mammals by an order of magnitude in body mass. Several evolutionary lineages among Sauropoda produced giants with body masses in excess of 50 metric tonnes by conservative estimates. With body mass increase driven by the selective advantages of large body size, animal lineages will increase in body size until they reach the limit determined by the interplay of bauplan, biology, and resource availability. There is no evidence, however, that resource availability and global physicochemical parameters were different enough in the Mesozoic to have led to sauropod gigantism. We review the biology of sauropod dinosaurs in detail and posit that sauropod gigantism was made possible by a specific combination of plesiomorphic characters (phylogenetic heritage) and evolutionary innovations at different levels which triggered a remarkable evolutionary cascade. Of these key innovations, the most important probably was the very long neck, the most conspicuous feature of the sauropod bauplan. Compared to other herbivores, the long neck allowed more efficient food uptake than in other large herbivores by covering a much larger feeding envelope and making food accessible that was out of the reach of other herbivores. Sauropods thus must have been able to take up more energy from their environment than other herbivores. The long neck, in turn, could only evolve because of the small head and the extensive pneumatization of the sauropod axial skeleton, lightening the neck. The small head was possible because food was ingested without mastication. Both mastication and a gastric mill would have limited food uptake rate. Scaling relationships between gastrointestinal tract size and basal metabolic rate (BMR) suggest that sauropods compensated for the lack of particle reduction with long retention times, even at high uptake rates. The

  7. Slow DNA loss in the gigantic genomes of salamanders.

    PubMed

    Sun, Cheng; López Arriaza, José R; Mueller, Rachel Lockridge

    2012-01-01

    Evolutionary changes in genome size result from the combined effects of mutation, natural selection, and genetic drift. Insertion and deletion mutations (indels) directly impact genome size by adding or removing sequences. Most species lose more DNA through small indels (i.e., ~1-30 bp) than they gain, which can result in genome reduction over time. Because this rate of DNA loss varies across species, small indel dynamics have been suggested to contribute to genome size evolution. Species with extremely large genomes provide interesting test cases for exploring the link between small indels and genome size; however, most large genomes remain relatively unexplored. Here, we examine rates of DNA loss in the tetrapods with the largest genomes-the salamanders. We used low-coverage genomic shotgun sequence data from four salamander species to examine patterns of insertion, deletion, and substitution in neutrally evolving non-long terminal repeat (LTR) retrotransposon sequences. For comparison, we estimated genome-wide DNA loss rates in non-LTR retrotransposon sequences from five other vertebrate genomes: Anolis carolinensis, Danio rerio, Gallus gallus, Homo sapiens, and Xenopus tropicalis. Our results show that salamanders have significantly lower rates of DNA loss than do other vertebrates. More specifically, salamanders experience lower numbers of deletions relative to insertions, and both deletions and insertions are skewed toward smaller sizes. On the basis of these patterns, we conclude that slow DNA loss contributes to genomic gigantism in salamanders. We also identify candidate molecular mechanisms underlying these differences and suggest that natural variation in indel dynamics provides a unique opportunity to study the basis of genome stability. PMID:23175715

  8. An evolutionary cascade model for sauropod dinosaur gigantism--overview, update and tests.

    PubMed

    Sander, P Martin

    2013-01-01

    Sauropod dinosaurs are a group of herbivorous dinosaurs which exceeded all other terrestrial vertebrates in mean and maximal body size. Sauropod dinosaurs were also the most successful and long-lived herbivorous tetrapod clade, but no abiological factors such as global environmental parameters conducive to their gigantism can be identified. These facts justify major efforts by evolutionary biologists and paleontologists to understand sauropods as living animals and to explain their evolutionary success and uniquely gigantic body size. Contributions to this research program have come from many fields and can be synthesized into a biological evolutionary cascade model of sauropod dinosaur gigantism (sauropod gigantism ECM). This review focuses on the sauropod gigantism ECM, providing an updated version based on the contributions to the PLoS ONE sauropod gigantism collection and on other very recent published evidence. The model consist of five separate evolutionary cascades ("Reproduction", "Feeding", "Head and neck", "Avian-style lung", and "Metabolism"). Each cascade starts with observed or inferred basal traits that either may be plesiomorphic or derived at the level of Sauropoda. Each trait confers hypothetical selective advantages which permit the evolution of the next trait. Feedback loops in the ECM consist of selective advantages originating from traits higher in the cascades but affecting lower traits. All cascades end in the trait "Very high body mass". Each cascade is linked to at least one other cascade. Important plesiomorphic traits of sauropod dinosaurs that entered the model were ovipary as well as no mastication of food. Important evolutionary innovations (derived traits) were an avian-style respiratory system and an elevated basal metabolic rate. Comparison with other tetrapod lineages identifies factors limiting body size. PMID:24205267

  9. Gigantism and Acromegaly Due to Xq26 Microduplications and GPR101 Mutation

    PubMed Central

    Trivellin, G.; Daly, A.F.; Faucz, F.R.; Yuan, B.; Rostomyan, L.; Larco, D.O.; Schernthaner-Reiter, M.H.; Szarek, E.; Leal, L.F.; Caberg, J.-H.; Castermans, E.; Villa, C.; Dimopoulos, A.; Chittiboina, P.; Xekouki, P.; Shah, N.; Metzger, D.; Lysy, P.A.; Ferrante, E.; Strebkova, N.; Mazerkina, N.; Zatelli, M.C.; Lodish, M.; Horvath, A.; de Alexandre, R. Bertollo; Manning, A.D.; Levy, I.; Keil, M.F.; de la Luz Sierra, M.; Palmeira, L.; Coppieters, W.; Georges, M.; Naves, L.A.; Jamar, M.; Bours, V.; Wu, T.J.; Choong, C.S.; Bertherat, J.; Chanson, P.; Kamenický, P.; Farrell, W.E.; Barlier, A.; Quezado, M.; Bjelobaba, I.; Stojilkovic, S.S.; Wess, J.; Costanzi, S.; Liu, P.; Lupski, J.R.; Beckers, A.; Stratakis, C.A.

    2015-01-01

    BACKGROUND Increased secretion of growth hormone leads to gigantism in children and acromegaly in adults; the genetic causes of gigantism and acromegaly are poorly understood. METHODS We performed clinical and genetic studies of samples obtained from 43 patients with gigantism and then sequenced an implicated gene in samples from 248 patients with acromegaly. RESULTS We observed microduplication on chromosome Xq26.3 in samples from 13 patients with gigantism; of these samples, 4 were obtained from members of two unrelated kindreds, and 9 were from patients with sporadic cases. All the patients had disease onset during early childhood. Of the patients with gigantism who did not carry an Xq26.3 microduplication, none presented before the age of 5 years. Genomic characterization of the Xq26.3 region suggests that the microduplications are generated during chromosome replication and that they contain four protein-coding genes. Only one of these genes, GPR101, which encodes a G-protein–coupled receptor, was overexpressed in patients’ pituitary lesions. We identified a recurrent GPR101 mutation (p.E308D) in 11 of 248 patients with acromegaly, with the mutation found mostly in tumors. When the mutation was transfected into rat GH3 cells, it led to increased release of growth hormone and proliferation of growth hormone–producing cells. CONCLUSIONS We describe a pediatric disorder (which we have termed X-linked acrogigantism [X-LAG]) that is caused by an Xq26.3 genomic duplication and is characterized by early-onset gigantism resulting from an excess of growth hormone. Duplication of GPR101 probably causes X-LAG. We also found a recurrent mutation in GPR101 in some adults with acromegaly. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and others.) PMID:25470569

  10. An Evolutionary Cascade Model for Sauropod Dinosaur Gigantism - Overview, Update and Tests

    PubMed Central

    Sander, P. Martin

    2013-01-01

    Sauropod dinosaurs are a group of herbivorous dinosaurs which exceeded all other terrestrial vertebrates in mean and maximal body size. Sauropod dinosaurs were also the most successful and long-lived herbivorous tetrapod clade, but no abiological factors such as global environmental parameters conducive to their gigantism can be identified. These facts justify major efforts by evolutionary biologists and paleontologists to understand sauropods as living animals and to explain their evolutionary success and uniquely gigantic body size. Contributions to this research program have come from many fields and can be synthesized into a biological evolutionary cascade model of sauropod dinosaur gigantism (sauropod gigantism ECM). This review focuses on the sauropod gigantism ECM, providing an updated version based on the contributions to the PLoS ONE sauropod gigantism collection and on other very recent published evidence. The model consist of five separate evolutionary cascades (“Reproduction”, “Feeding”, “Head and neck”, “Avian-style lung”, and “Metabolism”). Each cascade starts with observed or inferred basal traits that either may be plesiomorphic or derived at the level of Sauropoda. Each trait confers hypothetical selective advantages which permit the evolution of the next trait. Feedback loops in the ECM consist of selective advantages originating from traits higher in the cascades but affecting lower traits. All cascades end in the trait “Very high body mass”. Each cascade is linked to at least one other cascade. Important plesiomorphic traits of sauropod dinosaurs that entered the model were ovipary as well as no mastication of food. Important evolutionary innovations (derived traits) were an avian-style respiratory system and an elevated basal metabolic rate. Comparison with other tetrapod lineages identifies factors limiting body size. PMID:24205267

  11. An evolutionary cascade model for sauropod dinosaur gigantism--overview, update and tests.

    PubMed

    Sander, P Martin

    2013-01-01

    Sauropod dinosaurs are a group of herbivorous dinosaurs which exceeded all other terrestrial vertebrates in mean and maximal body size. Sauropod dinosaurs were also the most successful and long-lived herbivorous tetrapod clade, but no abiological factors such as global environmental parameters conducive to their gigantism can be identified. These facts justify major efforts by evolutionary biologists and paleontologists to understand sauropods as living animals and to explain their evolutionary success and uniquely gigantic body size. Contributions to this research program have come from many fields and can be synthesized into a biological evolutionary cascade model of sauropod dinosaur gigantism (sauropod gigantism ECM). This review focuses on the sauropod gigantism ECM, providing an updated version based on the contributions to the PLoS ONE sauropod gigantism collection and on other very recent published evidence. The model consist of five separate evolutionary cascades ("Reproduction", "Feeding", "Head and neck", "Avian-style lung", and "Metabolism"). Each cascade starts with observed or inferred basal traits that either may be plesiomorphic or derived at the level of Sauropoda. Each trait confers hypothetical selective advantages which permit the evolution of the next trait. Feedback loops in the ECM consist of selective advantages originating from traits higher in the cascades but affecting lower traits. All cascades end in the trait "Very high body mass". Each cascade is linked to at least one other cascade. Important plesiomorphic traits of sauropod dinosaurs that entered the model were ovipary as well as no mastication of food. Important evolutionary innovations (derived traits) were an avian-style respiratory system and an elevated basal metabolic rate. Comparison with other tetrapod lineages identifies factors limiting body size.

  12. The early ELF signals of the gigantic jets captured by the Taiwan ground observation network

    NASA Astrophysics Data System (ADS)

    Chen, A. B. C.; Huang, P. H.; Su, H. T.; Hsu, R. R.

    2015-12-01

    The in-cloud ignition process of gigantic jets and blue jets receives attentions and discussions in the past years. The polarity and the position of their breakdown were proposed by Krehbiel et al. [2008] but no concrete observational evidence to support it directly. ELF spectrogram is a good tool to explore the electric activities, but traditional spectrograms are generated by a Fourier transform which obtain the frequency information through an integration operation. However the integration greatly limits the lowest frequency revealed by spectrogram and buries the important transient features. In this study, we applied a new but widely-used method, the Hilbert-Huang transform (HHT), to explore the spectrogram. Instead of the integration, HHT obtains the frequency information by differentiating on the phase angle, and become a powerful tool to reveal the fast frequency variation associated with transient luminous events. More than 100 transient luminous events including 25 gigantic jets observed by Taiwan ground optical observation network were analyzed. The results indicate that approximately 70% of gigantic jets can identify a rapid frequency variation in the interval of 300-600 milliseconds before main surge discharge, and this early feature can not find a clear corresponding amplitude variation in its sferic. Since this early signal can not be identified from the traditional Fourier spectrogram, but clear in-cloud lightning was registered correspondingly by the ground optical observation. In contrast to gigantic jets, this feature of early frequency change can be seen only in less than 30% of sprites and elves. These observational evidences are able to provide new constraints on the early discharge process of gigantic jets in clouds.

  13. Discharge processes, electric field, and electron energy in ISUAL-recorded gigantic jets

    NASA Astrophysics Data System (ADS)

    Kuo, Cheng-Ling; Chou, J. K.; Tsai, L. Y.; Chen, A. B.; Su, H. T.; Hsu, R. R.; Cummer, S. A.; Frey, H. U.; Mende, S. B.; Takahashi, Y.; Lee, L. C.

    2009-04-01

    This article reports the first high time resolution measurements of gigantic jets from the Imager of Sprites and Upper Atmospheric Lightning (ISUAL) experiment. The velocity of the upward propagating fully developed jet stage of the gigantic jets was ˜107 m s-1, which is similar to that observed for downward sprite streamers. Analysis of spectral ratios for the fully developed jet emissions gives a reduced E field of 400-655 Td and average electron energy of 8.5-12.3 eV. These values are higher than those in the sprites but are similar to those predicted by streamer models, which implies the existence of streamer tips in fully developed jets. The gigantic jets studied here all contained two distinct photometric peaks. The first peak is from the fully developed jet, which steadily propagates from the cloud top (˜20 km) to the lower ionosphere at ˜90 km. We suggest that the second photometric peak, which occurs ˜1 ms after the first peak, is from a current wave or potential wave-enhanced emissions that originate at an altitude of ˜50 km and extend toward the cloud top. We propose that the fully developed jet serves as an extension of the local ionosphere and produces a lowered ionosphere boundary. As the attachment processes remove the charges, the boundary of the local ionosphere moves up. The current in the channel persists and its contact point with the ionosphere moves upward, which produces the upward surging trailing jets. Imager and photometer data indicate that the lightning activity associated with the gigantic jets likely is in-cloud, and thus the initiation of the gigantic jets is not directly associated with cloud-to-ground discharges.

  14. Gigantic self-confined pahoehoe inflated lava flows in Argentina

    NASA Astrophysics Data System (ADS)

    Pasquare', G.; Bistacchi, A.

    2007-05-01

    The largest lava flows on Earth are pahoehoe basalts emplaced by inflation, a process which can change lava lobes initially a few decimetres thick into large lava sheets several metres thick. Inflation involves the initial formation of a thin, solidified, viscoelastic crust, under which liquid lava is continually added. This thermally efficient endogenous growth process explains the spread of huge volumes of lava over large, almost flat areas, as in the sheet flows which characterise the distal portions of Hawaiian volcanoes or some continental flood basalt provinces. Long, narrow, inflated pahoehoe flows have occasionally been described, either emplaced along pre-existing river channels or confined within topographic barriers. In this contribution we present previously unknown inflated pahoehoe lava flows following very long, narrow pathways over an almost flat surface, with no topographic confinement. Lava, which erupted in Late Quaternary times from the eastern tip of a 60 km long volcanic fissure in Argentina, formed several discrete flows extending as far as 180 km from the source. This fissure was characterized by a long-lasting and complex activity. Alkali-basaltic lava flows were emitted at the two extremities of the fissure system. In the intermediate section of the fissure, the Payun Matru, a great trachitic composite volcano, developed, giving rise to a large caldera which produced large pyroclastic flows. Alkali-basalts predate and postdate the trachitic activity, in fact at the end of the trachitic activity, new basaltic lava flows (mainly aa) were emitted from both ends of the fissure. We studied in details the youngest of the gigantic flows (Pampas Onduladas lava flow), which progressively develops through differing thermally-efficient flow mechanisms. The flow created a large shield volcanic structure at the eastern tip of the E-W fissure and spread to the E forming a very large and thick inflated pahoehoe sheet flow. Leaving the flanks of the

  15. A context dependent role for DNA methylation in bivalves.

    PubMed

    Gavery, Mackenzie R; Roberts, Steven B

    2014-05-01

    The function of DNA methylation in species such as bivalves where the limited amount of DNA methylation is predominantly found in gene bodies remains unclear. An emerging possible explanation is that the role of gene body DNA methylation is dependent on gene function, a potential phenomenon that has arisen from selective pressure on lineage-specific life history traits. In genes contributing to phenotypes that benefit from increased plasticity, the absence of DNA methylation could contribute to stochastic transcriptional opportunities and increased transposable element activity. In genes where regulated control of activity is essential, DNA methylation may also play a role in targeted, predictable genome regulation. Here, we review the current knowledge concerning DNA methylation in bivalves and explore the putative role of DNA methylation in both an evolutionary and ecological context.

  16. Sequential determination of biological and pollutant elements in marine bivalves

    SciTech Connect

    Zeisler, R.; Stone, S.F.; Sanders, R.W.

    1988-12-15

    A unique sequence of instrumental methods has been employed to obtain concentrations for 44 elements in marine bivalve tissue. The techniques used were (1) X-ray fluorescence, (2) prompt gamma activation analysis, and (3) neutron activation analysis. It is possible to use a single subsample and follow it nondestructively through the three instrumental analysis techniques. A final radiochemical procedure for tin was also applied after completing the instrumental analyses. Comparison of results for elements determined by more than one technique in sequence showed good agreement, as did results from certified reference material samples analyzed along with the samples. The concentrations found in the bivalve samples ranged from carbon at more than 50% dry weight down to gold at several microgram per kilogram.

  17. Bioaccumulation of nitroarenes in bivalves at Osaka Bay, Japan.

    PubMed

    Uno, Seiichi; Tanaka, Hiroyuki; Miki, Shizuho; Kokushi, Emiko; Ito, Kazuki; Yamamoto, Masataka; Koyama, Jiro

    2011-01-01

    This paper reports for the first time the detection and occurrence of nitroarenes (NPAHs) in marine organisms. Mussels and oysters collected from Osaka Bay, Japan, had total NPAHs concentrations that ranged from 2380 to 24,688 pg/g dry and 2672 to 25,961 pg/g dry, respectively. Relatively higher concentrations were detected in sampling sites located near the central district and suburbs of Osaka City implying that the most probable sources of NPAHs in the two bivalves are exhaust gases and smokes emitted by automobiles and industrial plants. Bivalves had relatively higher residues of 1-nitronaphthalene, 2-nitronaphthalene, 3-nitrophenanthrene, and 9-nitrophenanthrenes. Residues of 2-nitrofluorene, 1-nitropyrene, 4-nitropyrenes, and 6-nitrochrysene were much lower compared to nitronaphthalenes and nitrophenanthrenes. Inter-species differences was only observed for 2-nitronaphthalene with oysters exhibiting significantly higher residues than mussels. PMID:21420130

  18. Modeling the carbon isotope composition of bivalve shells (Invited)

    NASA Astrophysics Data System (ADS)

    Romanek, C.

    2010-12-01

    The stable carbon isotope composition of bivalve shells is a valuable archive of paleobiological and paleoenvironmental information. Previous work has shown that the carbon isotope composition of the shell is related to the carbon isotope composition of dissolved inorganic carbon (DIC) in the ambient water in which a bivalve lives, as well as metabolic carbon derived from bivalve respiration. The contribution of metabolic carbon varies among organisms, but it is generally thought to be relatively low (e.g., <10%) in shells from aquatic organism and high (>90%) in the shells from terrestrial organisms. Because metabolic carbon contains significantly more C-12 than DIC, negative excursions from the expected environmental (DIC) signal are interpreted to reflect an increased contribution of metabolic carbon in the shell. This observation contrasts sharply with modeled carbon isotope compositions for shell layers deposited from the inner extrapallial fluid (EPF). Previous studies have shown that growth lines within the inner shell layer of bivalves are produced during periods of anaerobiosis when acidic metabolic byproducts (e.g., succinic acid) are neutralized (or buffered) by shell dissolution. This requires the pH of EPF to decrease below ambient levels (~7.5) until a state of undersaturation is achieved that promotes shell dissolution. This condition may occur when aquatic bivalves are subjected to external stressors originating from ecological (predation) or environmental (exposure to atm; low dissolved oxygen; contaminant release) pressures; normal physiological processes will restore the pH of EPF when the pressure is removed. As a consequence of this process, a temporal window should also exist in EPF at relatively low pH where shell carbonate is deposited at a reduced saturation state and precipitation rate. For example, EPF chemistry should remain slightly supersaturated with respect to aragonite given a drop of one pH unit (6.5), but under closed conditions

  19. Bivalves build their shells from amorphous calcium carbonate

    NASA Astrophysics Data System (ADS)

    Jacob, D. E.; Wirth, R.; Soldati, A. L.; Wehrmeister, U.

    2012-04-01

    One of the most common shell structures in the bivalve class is the prism and nacre structure. It is widely distributed amongst both freshwater and marine species and gives cultured pearls their sought-after lustre. In freshwater bivalves, both shell structures (prism and nacre) consist of aragonite. Formation of the shell form an amorphous precursor phase is a wide-spread strategy in biomineralization and presents a number of advantages for the organisms in the handling of the CaCO3 material. While there is already evidence that larval shells of some mollusk species use amorphous calcium carbonate (ACC) as a transient precursor phase for aragonite, the use of this strategy by adult animals was only speculated upon. We present results from in-situ geochemistry, Raman spectroscopy and focused-ion beam assisted TEM on three species from two different bivalve families that show that remnants of ACC can be found in shells from adult species. We show that the amorphous phase is not randomly distributed, but is systematically found in a narrow zone at the interface between periostracum and prism layer. This zone is the area where spherulitic CaCO3- structures protrude from the inner periostracum to form the initial prisms. These observations are in accordance with our earlier results on equivalent structures in freshwater cultured pearls (Jacob et al., 2008) and show that the original building material for the prisms is amorphous calcium carbonate, secreted in vesicles at the inner periostracum layer. Quantitative temperature calibrations for paleoclimate applications using bivalve shells are based on the Mg-Ca exchange between inorganic aragonite (or calcite) and water. These calibrations, thus, do not take into account the biomineral crystallization path via an amorphous calcium carbonate precursor and are therefore likely to introduce a bias (a so-called vital effect) which currently is not accounted for. Jacob et al. (2008) Geochim. Cosmochim. Acta 72, 5401-5415

  20. Ocean Acidification Has Multiple Modes of Action on Bivalve Larvae

    PubMed Central

    Waldbusser, George G.; Hales, Burke; Langdon, Chris J.; Haley, Brian A.; Schrader, Paul; Brunner, Elizabeth L.; Gray, Matthew W.; Miller, Cale A.; Gimenez, Iria; Hutchinson, Greg

    2015-01-01

    Ocean acidification (OA) is altering the chemistry of the world’s oceans at rates unparalleled in the past roughly 1 million years. Understanding the impacts of this rapid change in baseline carbonate chemistry on marine organisms needs a precise, mechanistic understanding of physiological responses to carbonate chemistry. Recent experimental work has shown shell development and growth in some bivalve larvae, have direct sensitivities to calcium carbonate saturation state that is not modulated through organismal acid-base chemistry. To understand different modes of action of OA on bivalve larvae, we experimentally tested how pH, PCO2, and saturation state independently affect shell growth and development, respiration rate, and initiation of feeding in Mytilus californianus embryos and larvae. We found, as documented in other bivalve larvae, that shell development and growth were affected by aragonite saturation state, and not by pH or PCO2. Respiration rate was elevated under very low pH (~7.4) with no change between pH of ~ 8.3 to ~7.8. Initiation of feeding appeared to be most sensitive to PCO2, and possibly minor response to pH under elevated PCO2. Although different components of physiology responded to different carbonate system variables, the inability to normally develop a shell due to lower saturation state precludes pH or PCO2 effects later in the life history. However, saturation state effects during early shell development will carry-over to later stages, where pH or PCO2 effects can compound OA effects on bivalve larvae. Our findings suggest OA may be a multi-stressor unto itself. Shell development and growth of the native mussel, M. californianus, was indistinguishable from the Mediterranean mussel, Mytilus galloprovincialis, collected from the southern U.S. Pacific coast, an area not subjected to seasonal upwelling. The concordance in responses suggests a fundamental OA bottleneck during development of the first shell material affected only by

  1. Ocean Acidification Has Multiple Modes of Action on Bivalve Larvae.

    PubMed

    Waldbusser, George G; Hales, Burke; Langdon, Chris J; Haley, Brian A; Schrader, Paul; Brunner, Elizabeth L; Gray, Matthew W; Miller, Cale A; Gimenez, Iria; Hutchinson, Greg

    2015-01-01

    Ocean acidification (OA) is altering the chemistry of the world's oceans at rates unparalleled in the past roughly 1 million years. Understanding the impacts of this rapid change in baseline carbonate chemistry on marine organisms needs a precise, mechanistic understanding of physiological responses to carbonate chemistry. Recent experimental work has shown shell development and growth in some bivalve larvae, have direct sensitivities to calcium carbonate saturation state that is not modulated through organismal acid-base chemistry. To understand different modes of action of OA on bivalve larvae, we experimentally tested how pH, PCO2, and saturation state independently affect shell growth and development, respiration rate, and initiation of feeding in Mytilus californianus embryos and larvae. We found, as documented in other bivalve larvae, that shell development and growth were affected by aragonite saturation state, and not by pH or PCO2. Respiration rate was elevated under very low pH (~7.4) with no change between pH of ~ 8.3 to ~7.8. Initiation of feeding appeared to be most sensitive to PCO2, and possibly minor response to pH under elevated PCO2. Although different components of physiology responded to different carbonate system variables, the inability to normally develop a shell due to lower saturation state precludes pH or PCO2 effects later in the life history. However, saturation state effects during early shell development will carry-over to later stages, where pH or PCO2 effects can compound OA effects on bivalve larvae. Our findings suggest OA may be a multi-stressor unto itself. Shell development and growth of the native mussel, M. californianus, was indistinguishable from the Mediterranean mussel, Mytilus galloprovincialis, collected from the southern U.S. Pacific coast, an area not subjected to seasonal upwelling. The concordance in responses suggests a fundamental OA bottleneck during development of the first shell material affected only by

  2. Ocean Acidification Has Multiple Modes of Action on Bivalve Larvae.

    PubMed

    Waldbusser, George G; Hales, Burke; Langdon, Chris J; Haley, Brian A; Schrader, Paul; Brunner, Elizabeth L; Gray, Matthew W; Miller, Cale A; Gimenez, Iria; Hutchinson, Greg

    2015-01-01

    Ocean acidification (OA) is altering the chemistry of the world's oceans at rates unparalleled in the past roughly 1 million years. Understanding the impacts of this rapid change in baseline carbonate chemistry on marine organisms needs a precise, mechanistic understanding of physiological responses to carbonate chemistry. Recent experimental work has shown shell development and growth in some bivalve larvae, have direct sensitivities to calcium carbonate saturation state that is not modulated through organismal acid-base chemistry. To understand different modes of action of OA on bivalve larvae, we experimentally tested how pH, PCO2, and saturation state independently affect shell growth and development, respiration rate, and initiation of feeding in Mytilus californianus embryos and larvae. We found, as documented in other bivalve larvae, that shell development and growth were affected by aragonite saturation state, and not by pH or PCO2. Respiration rate was elevated under very low pH (~7.4) with no change between pH of ~ 8.3 to ~7.8. Initiation of feeding appeared to be most sensitive to PCO2, and possibly minor response to pH under elevated PCO2. Although different components of physiology responded to different carbonate system variables, the inability to normally develop a shell due to lower saturation state precludes pH or PCO2 effects later in the life history. However, saturation state effects during early shell development will carry-over to later stages, where pH or PCO2 effects can compound OA effects on bivalve larvae. Our findings suggest OA may be a multi-stressor unto itself. Shell development and growth of the native mussel, M. californianus, was indistinguishable from the Mediterranean mussel, Mytilus galloprovincialis, collected from the southern U.S. Pacific coast, an area not subjected to seasonal upwelling. The concordance in responses suggests a fundamental OA bottleneck during development of the first shell material affected only by

  3. Host specificity and population dynamics of a sponge-endosymbiotic bivalve.

    PubMed

    Tsubaki, Remi; Kato, Makoto

    2012-09-01

    We assessed the host-use pattern of the sponge-endosymbiotic bivalve Vulsella vulsella and its demographic consequences in an inland sea in Okinawa Island, Japan. Vulsella vulsella utilized only one massive globular sponge species Spongia sp. as a host, and no Spongia sp. without V. vulsella were found. Individual sponges contained 9-248 live bivalves and 0-222 dead bivalves. The densities of live and dead bivalves in individual sponges were approximately constant irrespective of sponge size, indicating that available space is very scarce inside each sponge. The size distribution of bivalves was skewed to small, young individuals less than 30 mm in shell height, although the estimated largest possible size was 106 mm. The bivalve population at each sampling date was composed of three yearly cohorts, and recruitment of juveniles occurred in the summer. The bivalves became sexually mature as males within one year after recruitment and changed sex from male to female as they grew. The size and sex distributions of the bivalve were largely similar among sponges regardless of sponge size, suggesting that the recruitment, growth, longevity, and sex change of the bivalve were strictly regulated, probably by the high water temperature and strong waves generated by typhoons in summer months.

  4. Relating Productivity Events to Holocene Bivalve Shell Growth Rates

    NASA Astrophysics Data System (ADS)

    Huntley, J. W.; Krause, R. A.; Kowalewski, M.; Romanek, C. S.; Kaufman, D. S.; Simoes, M. G.

    2007-12-01

    The growth rate of a bivalve can be influenced by many environmental factors that can change during the life of the organism. In this contribution we present initial data from a millennium scale chronology to assess the relationship between ontogenetic growth in the bivalve Semele casali and paleoenvironmental conditions preserved in the shell using growth increment analysis, radiocarbon-calibrated amino acid racemization dating techniques, stable isotopes (C and O) and high spatial resolution (125-150 samples per cm of shell profile) trace element (Ba, Mn) analysis (LA-ICPMS). Time-averaged specimens of S. casali were dredged from two sites at 10 meters and 30 meters depth along the inner continental shelf at Ubatuba Bay in the Southeast Brazilian Bight, an area influenced by productivity pulses triggered by coastal runoff events and coastal upwelling. Seventy-five individual valves were dated using amino acid racemization (aspartic acid). Dates were calculated using an expanded version of a previously published relationship (Barbour Wood et al., 2006 Quaternary Research 323- 331) between aspartic acid ratios and AMS radiocarbon dates of twelve S. casali individuals from the same sampling locations. The resulting time series has complete coverage for the past three thousand years at centennial resolution. From this time series, a sub-sample of dated valves was selected for more detailed growth increment, stable isotope and high-resolution trace element (Ba/Ca and Mn/Ca) analyses. Oceanic productivity is expressed differentially in the trace element profiles of S. casali with elevated Ba/Ca and Mn/Ca ratios capturing nutrient input through coastal runoff events while elevated Ba/Ca and depressed Mn/Ca ratios represent input through coastal upwelling. Fluctuations in Ba/Ca and Mn/Ca are not correlated to fluctuations in relative growth throughout the ontogeny of an individual bivalve, nor are they expected to be as periods of increased productivity are transient

  5. A gigantic nothosaur (Reptilia: Sauropterygia) from the Middle Triassic of SW China and its implication for the Triassic biotic recovery.

    PubMed

    Liu, Jun; Hu, Shi-Xue; Rieppel, Olivier; Jiang, Da-Yong; Benton, Michael J; Kelley, Neil P; Aitchison, Jonathan C; Zhou, Chang-Yong; Wen, Wen; Huang, Jin-Yuan; Xie, Tao; Lv, Tao

    2014-01-01

    The presence of gigantic apex predators in the eastern Panthalassic and western Tethyan oceans suggests that complex ecosystems in the sea had become re-established in these regions at least by the early Middle Triassic, after the Permian-Triassic mass extinction (PTME). However, it is not clear whether oceanic ecosystem recovery from the PTME was globally synchronous because of the apparent lack of such predators in the eastern Tethyan/western Panthalassic region prior to the Late Triassic. Here we report a gigantic nothosaur from the lower Middle Triassic of Luoping in southwest China (eastern Tethyan ocean), which possesses the largest known lower jaw among Triassic sauropterygians. Phylogenetic analysis suggests parallel evolution of gigantism in Triassic sauropterygians. Discovery of this gigantic apex predator, together with associated diverse marine reptiles and the complex food web, indicates global recovery of shallow marine ecosystems from PTME by the early Middle Triassic. PMID:25429609

  6. A gigantic nothosaur (Reptilia: Sauropterygia) from the Middle Triassic of SW China and its implication for the Triassic biotic recovery

    PubMed Central

    Liu, Jun; Hu, Shi-xue; Rieppel, Olivier; Jiang, Da-yong; Benton, Michael J.; Kelley, Neil P.; Aitchison, Jonathan C.; Zhou, Chang-yong; Wen, Wen; Huang, Jin-yuan; Xie, Tao; Lv, Tao

    2014-01-01

    The presence of gigantic apex predators in the eastern Panthalassic and western Tethyan oceans suggests that complex ecosystems in the sea had become re-established in these regions at least by the early Middle Triassic, after the Permian-Triassic mass extinction (PTME). However, it is not clear whether oceanic ecosystem recovery from the PTME was globally synchronous because of the apparent lack of such predators in the eastern Tethyan/western Panthalassic region prior to the Late Triassic. Here we report a gigantic nothosaur from the lower Middle Triassic of Luoping in southwest China (eastern Tethyan ocean), which possesses the largest known lower jaw among Triassic sauropterygians. Phylogenetic analysis suggests parallel evolution of gigantism in Triassic sauropterygians. Discovery of this gigantic apex predator, together with associated diverse marine reptiles and the complex food web, indicates global recovery of shallow marine ecosystems from PTME by the early Middle Triassic. PMID:25429609

  7. A gigantic nothosaur (Reptilia: Sauropterygia) from the Middle Triassic of SW China and its implication for the Triassic biotic recovery

    NASA Astrophysics Data System (ADS)

    Liu, Jun; Hu, Shi-Xue; Rieppel, Olivier; Jiang, Da-Yong; Benton, Michael J.; Kelley, Neil P.; Aitchison, Jonathan C.; Zhou, Chang-Yong; Wen, Wen; Huang, Jin-Yuan; Xie, Tao; Lv, Tao

    2014-11-01

    The presence of gigantic apex predators in the eastern Panthalassic and western Tethyan oceans suggests that complex ecosystems in the sea had become re-established in these regions at least by the early Middle Triassic, after the Permian-Triassic mass extinction (PTME). However, it is not clear whether oceanic ecosystem recovery from the PTME was globally synchronous because of the apparent lack of such predators in the eastern Tethyan/western Panthalassic region prior to the Late Triassic. Here we report a gigantic nothosaur from the lower Middle Triassic of Luoping in southwest China (eastern Tethyan ocean), which possesses the largest known lower jaw among Triassic sauropterygians. Phylogenetic analysis suggests parallel evolution of gigantism in Triassic sauropterygians. Discovery of this gigantic apex predator, together with associated diverse marine reptiles and the complex food web, indicates global recovery of shallow marine ecosystems from PTME by the early Middle Triassic.

  8. A gigantic nothosaur (Reptilia: Sauropterygia) from the Middle Triassic of SW China and its implication for the Triassic biotic recovery.

    PubMed

    Liu, Jun; Hu, Shi-Xue; Rieppel, Olivier; Jiang, Da-Yong; Benton, Michael J; Kelley, Neil P; Aitchison, Jonathan C; Zhou, Chang-Yong; Wen, Wen; Huang, Jin-Yuan; Xie, Tao; Lv, Tao

    2014-01-01

    The presence of gigantic apex predators in the eastern Panthalassic and western Tethyan oceans suggests that complex ecosystems in the sea had become re-established in these regions at least by the early Middle Triassic, after the Permian-Triassic mass extinction (PTME). However, it is not clear whether oceanic ecosystem recovery from the PTME was globally synchronous because of the apparent lack of such predators in the eastern Tethyan/western Panthalassic region prior to the Late Triassic. Here we report a gigantic nothosaur from the lower Middle Triassic of Luoping in southwest China (eastern Tethyan ocean), which possesses the largest known lower jaw among Triassic sauropterygians. Phylogenetic analysis suggests parallel evolution of gigantism in Triassic sauropterygians. Discovery of this gigantic apex predator, together with associated diverse marine reptiles and the complex food web, indicates global recovery of shallow marine ecosystems from PTME by the early Middle Triassic.

  9. Gigantic Cosmic Corkscrew Reveals New Details About Mysterious Microquasar

    NASA Astrophysics Data System (ADS)

    2004-10-01

    Making an extra effort to image a faint, gigantic corkscrew traced by fast protons and electrons shot out from a mysterious microquasar paid off for a pair of astrophysicists who gained new insights into the beast's inner workings and also resolved a longstanding dispute over the object's distance. Microquasar SS 433 VLA Image of Microquasar SS 433 CREDIT: Blundell & Bowler, NRAO/AUI/NSF (Click on Image for Larger Version) The astrophysicists used the National Science Foundation's Very Large Array (VLA) radio telescope to capture the faintest details yet seen in the plasma jets emerging from the microquasar SS 433, an object once dubbed the "enigma of the century." As a result, they have changed scientists' understanding of the jets and settled the controversy over its distance "beyond all reasonable doubt," they said. SS 433 is a neutron star or black hole orbited by a "normal" companion star. The powerful gravity of the neutron star or black hole draws material from the stellar wind of its companion into an accretion disk of material tightly circling the dense central object prior to being pulled onto it. This disk propels jets of fast protons and electrons outward from its poles at about a quarter of the speed of light. The disk in SS 433 wobbles like a child's top, causing its jets to trace a corkscrew in the sky every 162 days. The new VLA study indicates that the speed of the ejected particles varies over time, contrary to the traditional model for SS 433. "We found that the actual speed varies between 24 percent to 28 percent of light speed, as opposed to staying constant," said Katherine Blundell, of the University of Oxford in the United Kingdom. "Amazingly, the jets going in both directions change their speeds simultaneously, producing identical speeds in both directions at any given time," Blundell added. Blundell worked with Michael Bowler, also of Oxford. The scientists' findings have been accepted by the Astrophysical Journal Letters. SS 433 New VLA

  10. The acromegaly--gigantism syndrome. Report of four cases treated surgically.

    PubMed

    Zampieri, P; Scanarini, M; Sicolo, N; Andrioli, G; Mingrino, S

    1983-12-01

    Four cases of growth-hormone-secreting pituitary adenoma, with associated aspects of acromegaly and gigantism, are reported in patients aged 12-26. All of the patients had macroadenomas and were treated surgically, three by the transsphenoidal approach and one with a transfrontal craniotomy. Histologic examination revealed eosinophilic adenomas in three of the cases and a mixed eosinophilic--chromophobe adenoma in one, all with cellular irregularities (mitosis and cellular and nuclear polymorphism), local invasivity, or both. Because surgical treatment did not produce complete normalization of growth hormone levels, radiotherapy followed the operations in all four cases. In our opinion, the treatment of acromegalic gigantism poses more therapeutic problems than that of simple acromegaly, with combined treatment (surgical, radiation, and medical) often being necessary. PMID:6648790

  11. [A multicenter clinical trial of SMS 201-995 (octreotide acetate) in acromegaly and gigantism].

    PubMed

    Shimatsu, A; Imura, H; Irie, M; Nakagawa, S; Goto, Y; Shimizu, N; Takeda, R; Kato, Y; Saito, S; Ibayashi, H

    1989-07-20

    Sixty-four patients with active acromegaly and three patients with gigantism were treated with the long acting somatostatin analog SMS 201-995 (50-500 micrograms, sc, every 6-12 h or 150-880 micrograms daily by intermittent sc infusion, for up to 114 weeks). The fasting plasma GH levels were significantly suppressed (less than 50% of the values before treatment) in 49 patients and became normal in 18 patients. Suppression of GH secretion was associated with normalization of plasma somatomedin-C levels (14 out of 30 cases) and significant clinical improvement such as disappearance of headache and decrease of excessive sweating. Shrinkage of pituitary tumors as determined by computed tomography and/or magnetic resonance imaging studies occurred in 11 out of 40 cases. Side effects were minimal and tolerable. SMS 201-995 appears to be an effective agent for the treatment of acromegaly and gigantism. PMID:2684694

  12. Cope's Rule and Romer's theory: patterns of diversity and gigantism in eurypterids and Palaeozoic vertebrates.

    PubMed

    Lamsdell, James C; Braddy, Simon J

    2010-04-23

    Gigantism is widespread among Palaeozoic arthropods, yet causal mechanisms, particularly the role of (abiotic) environmental factors versus (biotic) competition, remain unknown. The eurypterids (Arthropoda: Chelicerata) include the largest arthropods; gigantic predatory pterygotids (Eurypterina) during the Siluro-Devonian and bizarre sweep-feeding hibbertopterids (Stylonurina) from the Carboniferous to end-Permian. Analysis of family-level originations and extinctions among eurypterids and Palaeozoic vertebrates show that the diversity of Eurypterina waned during the Devonian, while the Placodermi radiated, yet Stylonurina remained relatively unaffected; adopting a sweep-feeding strategy they maintained their large body size by avoiding competition, and persisted throughout the Late Palaeozoic while the predatory nektonic Eurypterina (including the giant pterygotids) declined during the Devonian, possibly out-competed by other predators including jawed vertebrates. PMID:19828493

  13. IMPORTANCE OF MATERNAL TRANSFER OF THE PHOTOREACTIVE POLYCYCLIC AROMATIC HYDROCARBON FLUORANTHENE FROM BENTHIC ADULT BIVALVES TO THEIR PELAGIC LARVAE

    EPA Science Inventory

    Laboratory experiments were conducted to determine if maternal transfer of polycyclic aromatic hydrocarbons (PAHs) from benthic adult bivalves could result in phototoxicity to their pelagic larvae when exposed to ultraviolet light (UV). In these experiments, adult bivalves were e...

  14. Cerebral gigantism associated with jaw cyst basal cell naevoid syndrome in two families.

    PubMed

    Cramer, H; Niederdellmann, H

    1983-01-01

    We report 9 subjects from 2 families with the syndrome of cerebral gigantism, seven of the patients also had jaw cyst basal cell naevoid syndrome. Neurological, radiological, somatic and biochemical features of this hitherto unreported association are described. Neurological symptoms included mild hydrocephalus, ventricular malformation, cerebellar syndrome, intracranial calcification, oculomotor disturbances, EEG abnormalities and rarely, mild peripheral nervous disorders. A disturbance of calcium metabolism appears to be a prominent feature of the genetically determined nonprogressive syndrome.

  15. Starvation reveals the cause of infection-induced castration and gigantism.

    PubMed

    Cressler, Clayton E; Nelson, William A; Day, Troy; McCauley, Edward

    2014-10-01

    Parasites often induce life-history changes in their hosts. In many cases, these infection-induced life-history changes are driven by changes in the pattern of energy allocation and utilization within the host. Because these processes will affect both host and parasite fitness, it can be challenging to determine who benefits from them. Determining the causes and consequences of infection-induced life-history changes requires the ability to experimentally manipulate life history and a framework for connecting life history to host and parasite fitness. Here, we combine a novel starvation manipulation with energy budget models to provide new insights into castration and gigantism in the Daphnia magna-Pasteuria ramosa host-parasite system. Our results show that starvation primarily affects investment in reproduction, and increasing starvation stress reduces gigantism and parasite fitness without affecting castration. These results are consistent with an energetic structure where the parasite uses growth energy as a resource. This finding gives us new understanding of the role of castration and gigantism in this system, and how life-history variation will affect infection outcome and epidemiological dynamics. The approach of combining targeted life-history manipulations with energy budget models can be adapted to understand life-history changes in other disease systems. PMID:25143034

  16. Ecological explanations to island gigantism: dietary niche divergence, predation, and size in an endemic lizard.

    PubMed

    Runemark, Anna; Sagonas, Kostas; Svensson, Erik I

    2015-08-01

    Although rapid evolution of body size on islands has long been known, the ecological mechanisms behind this island phenomenon remain poorly understood. Diet is an important selective pressure for morphological divergence. Here we investigate if selection for novel diets has contributed to the multiple independent cases of island gigantism in the Skyros wall lizard (Podarcis gaigeae) and if diet, predation, or both factors best explain island gigantism. We combined data on body size, shape, bite force, and realized and available diets to address this. Several lines of evidence suggest that diet has contributed to the island gigantism. The larger islet lizards have relatively wider heads and higher bite performance in relation to mainland lizards than would be expected from size differences alone. The proportions of consumed and available hard prey are higher on islets than mainland localities, and lizard body size is significantly correlated with the proportion of hard prey. Furthermore, the main axis of divergence in head shape is significantly correlated with dietary divergence. Finally, a model with only diet and one including diet and predation regime explain body size divergence equally well. Our results suggest that diet is an important ecological factor behind insular body size divergence, but could be consistent with an additional role for predation. PMID:26405734

  17. Ecological explanations to island gigantism: dietary niche divergence, predation, and size in an endemic lizard.

    PubMed

    Runemark, Anna; Sagonas, Kostas; Svensson, Erik I

    2015-08-01

    Although rapid evolution of body size on islands has long been known, the ecological mechanisms behind this island phenomenon remain poorly understood. Diet is an important selective pressure for morphological divergence. Here we investigate if selection for novel diets has contributed to the multiple independent cases of island gigantism in the Skyros wall lizard (Podarcis gaigeae) and if diet, predation, or both factors best explain island gigantism. We combined data on body size, shape, bite force, and realized and available diets to address this. Several lines of evidence suggest that diet has contributed to the island gigantism. The larger islet lizards have relatively wider heads and higher bite performance in relation to mainland lizards than would be expected from size differences alone. The proportions of consumed and available hard prey are higher on islets than mainland localities, and lizard body size is significantly correlated with the proportion of hard prey. Furthermore, the main axis of divergence in head shape is significantly correlated with dietary divergence. Finally, a model with only diet and one including diet and predation regime explain body size divergence equally well. Our results suggest that diet is an important ecological factor behind insular body size divergence, but could be consistent with an additional role for predation.

  18. Starvation reveals the cause of infection-induced castration and gigantism.

    PubMed

    Cressler, Clayton E; Nelson, William A; Day, Troy; McCauley, Edward

    2014-10-01

    Parasites often induce life-history changes in their hosts. In many cases, these infection-induced life-history changes are driven by changes in the pattern of energy allocation and utilization within the host. Because these processes will affect both host and parasite fitness, it can be challenging to determine who benefits from them. Determining the causes and consequences of infection-induced life-history changes requires the ability to experimentally manipulate life history and a framework for connecting life history to host and parasite fitness. Here, we combine a novel starvation manipulation with energy budget models to provide new insights into castration and gigantism in the Daphnia magna-Pasteuria ramosa host-parasite system. Our results show that starvation primarily affects investment in reproduction, and increasing starvation stress reduces gigantism and parasite fitness without affecting castration. These results are consistent with an energetic structure where the parasite uses growth energy as a resource. This finding gives us new understanding of the role of castration and gigantism in this system, and how life-history variation will affect infection outcome and epidemiological dynamics. The approach of combining targeted life-history manipulations with energy budget models can be adapted to understand life-history changes in other disease systems.

  19. The triangulation of the gigantic jets observed by the optical observation network in Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, Alfred B.; Huang, Chien-Fong; Peng, Kang-Ming; Su, Han-Tzong; Hsu, Rue-Ron

    2015-04-01

    The optical triangulation of sprites and elves by the multiple sites has been done in the past decades, but the similar observation on gigantic jets has never been reported yet. A ground optical observation network consisting of four stations at Kimen, Penghu, Tainan, and Taitung (from west to east) has been established in Taiwan since 2012. Each station equipped with two sets of Watec low-light sensitivity cameras, and the elevation and azimuth of the observation can be fully remote controlled to point toward the on-going convection system in the vicinity of Taiwan. In summer 2014, more than 6 gigantic jets were captured by at least two stations successfully. The triangulation and ULF sferics of these interesting events provides an excellent chance to explore the spatial and temporal evolution of the jets in different phases. In this presentation, this ground observation network will be introduced, the detail evolution of the recorded gigantic jets is presented. The preliminary result implies that the jets may not pop from the cloudtop straightforwardly, and some twists occur during the propagation of the jets. A more complicated analysis of the tomography for the advanced triangulation will be mentioned, too.

  20. Cardiac and metabolic effects of chronic growth hormone and insulin-like growth factor I excess in young adults with pituitary gigantism.

    PubMed

    Bondanelli, Marta; Bonadonna, Stefania; Ambrosio, Maria Rosaria; Doga, Mauro; Gola, Monica; Onofri, Alessandro; Zatelli, Maria Chiara; Giustina, Andrea; degli Uberti, Ettore C

    2005-09-01

    Chronic growth hormone (GH)/insulin-like growth factor I (IGF-I) excess is associated with considerable mortality in acromegaly, but no data are available in pituitary gigantism. The aim of the study was to evaluate the long-term effects of early exposure to GH and IGF-I excess on cardiovascular and metabolic parameters in adult patients with pituitary gigantism. Six adult male patients with newly diagnosed gigantism due to GH secreting pituitary adenoma were studied and compared with 6 age- and sex-matched patients with acromegaly and 10 healthy subjects. Morphologic and functional cardiac parameters were evaluated by Doppler echocardiography. Glucose metabolism was assessed by evaluating glucose tolerance and homeostasis model assessment index. Disease duration was significantly longer (P<.05) in patients with gigantism than in patients with acromegaly, whereas GH and IGF-I concentrations were comparable. Left ventricular mass was increased both in patients with gigantism and in patients with acromegaly, as compared with controls. Left ventricular hypertrophy was detected in 2 of 6 of both patients with gigantism and patients with acromegaly, and isolated intraventricular septum thickening in 1 patient with gigantism. Inadequate diastolic filling (ratio between early and late transmitral flow velocity<1) was detected in 2 of 6 patients with gigantism and 1 of 6 patients with acromegaly. Impaired glucose metabolism occurrence was higher in patients with acromegaly (66%) compared with patients with gigantism (16%). Concentrations of IGF-I were significantly (P<.05) higher in patients with gigantism who have cardiac abnormalities than in those without cardiac abnormalities. In conclusion, our data suggest that GH/IGF-I excess in young adult patients is associated with morphologic and functional cardiac abnormalities that are similar in patients with gigantism and in patients with acromegaly, whereas occurrence of impaired glucose metabolism appears to be higher in

  1. Cardiac and metabolic effects of chronic growth hormone and insulin-like growth factor I excess in young adults with pituitary gigantism.

    PubMed

    Bondanelli, Marta; Bonadonna, Stefania; Ambrosio, Maria Rosaria; Doga, Mauro; Gola, Monica; Onofri, Alessandro; Zatelli, Maria Chiara; Giustina, Andrea; degli Uberti, Ettore C

    2005-09-01

    Chronic growth hormone (GH)/insulin-like growth factor I (IGF-I) excess is associated with considerable mortality in acromegaly, but no data are available in pituitary gigantism. The aim of the study was to evaluate the long-term effects of early exposure to GH and IGF-I excess on cardiovascular and metabolic parameters in adult patients with pituitary gigantism. Six adult male patients with newly diagnosed gigantism due to GH secreting pituitary adenoma were studied and compared with 6 age- and sex-matched patients with acromegaly and 10 healthy subjects. Morphologic and functional cardiac parameters were evaluated by Doppler echocardiography. Glucose metabolism was assessed by evaluating glucose tolerance and homeostasis model assessment index. Disease duration was significantly longer (P<.05) in patients with gigantism than in patients with acromegaly, whereas GH and IGF-I concentrations were comparable. Left ventricular mass was increased both in patients with gigantism and in patients with acromegaly, as compared with controls. Left ventricular hypertrophy was detected in 2 of 6 of both patients with gigantism and patients with acromegaly, and isolated intraventricular septum thickening in 1 patient with gigantism. Inadequate diastolic filling (ratio between early and late transmitral flow velocity<1) was detected in 2 of 6 patients with gigantism and 1 of 6 patients with acromegaly. Impaired glucose metabolism occurrence was higher in patients with acromegaly (66%) compared with patients with gigantism (16%). Concentrations of IGF-I were significantly (P<.05) higher in patients with gigantism who have cardiac abnormalities than in those without cardiac abnormalities. In conclusion, our data suggest that GH/IGF-I excess in young adult patients is associated with morphologic and functional cardiac abnormalities that are similar in patients with gigantism and in patients with acromegaly, whereas occurrence of impaired glucose metabolism appears to be higher in

  2. Spikey bivalves: intra-periostracal crystal growth in anomalodesmatans.

    PubMed

    Checa, Antonio G; Harper, Elizabeth M

    2010-12-01

    The external shell surfaces of most anomalodesmatan bivalves are studded with small spikes, particularly at the posterior end. We have studied the morphology, mode of growth, and distribution among taxa of these spikes. In this study we found that spikes vary widely in morphology, from acute spikes to flat plaques. Optical and electron microscopy has revealed that the periostraca of Laternula, Myadora, and Thraciopsis consist of an outer dense layer and an inner translucent layer. The dense layer grows at the expense of the inner layer as it progresses toward the shell edge. The spikes begin to grow in the free periostracum, within the translucent periostracal layer, immediately below the dense layer. With growth, they push the dense periostracal layer upward but without penetrating it. Those parts of the spike in contact with this layer cease to grow, which explains the typical conical shape of spikes. When fully grown, spikes reach the base of the translucent layer, becoming incorporated into the outer shell layer. Scanning electron microscopy and electron backscatter diffraction analysis reveal that the spikes of Lyonsia norwegica and Lyonsiella abyssicola are prisms of aragonite composed of twinned crystals, with the c-axis vertical. A survey of the occurrence of spikes within the anomalodesmatans shows that they are present in all but a few families. Elsewhere within the closely related palaeoheterodonts, intra-periostracal calcification is also known in Neotrigonia and unionids, which indicates that this character may be plesiomorphic for these bivalves. The present data do not support the homology of spikes in other bivalve groups (e.g., veneroids) or in the aplacophorans or polyplacophorans.

  3. Spikey bivalves: intra-periostracal crystal growth in anomalodesmatans.

    PubMed

    Checa, Antonio G; Harper, Elizabeth M

    2010-12-01

    The external shell surfaces of most anomalodesmatan bivalves are studded with small spikes, particularly at the posterior end. We have studied the morphology, mode of growth, and distribution among taxa of these spikes. In this study we found that spikes vary widely in morphology, from acute spikes to flat plaques. Optical and electron microscopy has revealed that the periostraca of Laternula, Myadora, and Thraciopsis consist of an outer dense layer and an inner translucent layer. The dense layer grows at the expense of the inner layer as it progresses toward the shell edge. The spikes begin to grow in the free periostracum, within the translucent periostracal layer, immediately below the dense layer. With growth, they push the dense periostracal layer upward but without penetrating it. Those parts of the spike in contact with this layer cease to grow, which explains the typical conical shape of spikes. When fully grown, spikes reach the base of the translucent layer, becoming incorporated into the outer shell layer. Scanning electron microscopy and electron backscatter diffraction analysis reveal that the spikes of Lyonsia norwegica and Lyonsiella abyssicola are prisms of aragonite composed of twinned crystals, with the c-axis vertical. A survey of the occurrence of spikes within the anomalodesmatans shows that they are present in all but a few families. Elsewhere within the closely related palaeoheterodonts, intra-periostracal calcification is also known in Neotrigonia and unionids, which indicates that this character may be plesiomorphic for these bivalves. The present data do not support the homology of spikes in other bivalve groups (e.g., veneroids) or in the aplacophorans or polyplacophorans. PMID:21183444

  4. A novel filtering mutualism between a sponge host and its endosymbiotic bivalves.

    PubMed

    Tsubaki, Remi; Kato, Makoto

    2014-01-01

    Sponges, porous filter-feeding organisms consisting of vast canal systems, provide unique substrates for diverse symbiotic organisms. The Spongia (Spongia) sp. massive sponge is obligately inhabited by the host-specific endosymbiotic bivalve Vulsella vulsella, which benefits from this symbiosis by receiving protection from predators. However, whether the host sponge gains any benefit from this association is unclear. Considering that the bivalves exhale filtered water into the sponge body rather than the ambient environment, the sponge is hypothesized to utilize water exhaled by the bivalves to circulate water around its body more efficiently. We tested this hypothesis by observing the sponge aquiferous structure and comparing the pumping rates of sponges and bivalves. Observations of water currents and the sponge aquiferous structure revealed that the sponge had a unique canal system enabling it to inhale water exhaled from bivalves, indicating that the host sponge adapted morphologically to receive water from the bivalves. In addition, the volume of water circulating in the sponge body was dramatically increased by the water exhaled from bivalves. Therefore, this sponge-bivalve association can be regarded as a novel mutualism in which two filter-feeding symbionts promote mutual filtering rates. This symbiotic association should be called a "filtering mutualism".

  5. GREEN CRAB (CARCINUS MAENAS LINNAEUS) CONSUMPTION RATES ON AND PREY PREFERENCES AMONG FOUR BIVALVE PREY SPECIES

    EPA Science Inventory

    The European green crab, Carcinus maenas, is a recent invader to Pacific Northwest (PNW) estuaries with a voracious appetite, especially for bivalves. To assess their potential impact, we estimated green crab consumption rates on four PNW bivalve species, Yaquina oyster (Ostrea ...

  6. A Novel Filtering Mutualism between a Sponge Host and Its Endosymbiotic Bivalves

    PubMed Central

    Tsubaki, Remi; Kato, Makoto

    2014-01-01

    Sponges, porous filter-feeding organisms consisting of vast canal systems, provide unique substrates for diverse symbiotic organisms. The Spongia (Spongia) sp. massive sponge is obligately inhabited by the host-specific endosymbiotic bivalve Vulsella vulsella, which benefits from this symbiosis by receiving protection from predators. However, whether the host sponge gains any benefit from this association is unclear. Considering that the bivalves exhale filtered water into the sponge body rather than the ambient environment, the sponge is hypothesized to utilize water exhaled by the bivalves to circulate water around its body more efficiently. We tested this hypothesis by observing the sponge aquiferous structure and comparing the pumping rates of sponges and bivalves. Observations of water currents and the sponge aquiferous structure revealed that the sponge had a unique canal system enabling it to inhale water exhaled from bivalves, indicating that the host sponge adapted morphologically to receive water from the bivalves. In addition, the volume of water circulating in the sponge body was dramatically increased by the water exhaled from bivalves. Therefore, this sponge-bivalve association can be regarded as a novel mutualism in which two filter-feeding symbionts promote mutual filtering rates. This symbiotic association should be called a “filtering mutualism”. PMID:25330073

  7. [The Microsculpture of Glochidia of Some Anodontine Bivalves (Unionidae)].

    PubMed

    Sayenko, E M

    2016-01-01

    Glochidia of three freshwater anodontine bivalves: Kunashiria Starobogatov in Zatrawkin, 1983, Sinanodonta Modell, 1944, from the Far East, and Anodonta Lamarck, 1799, were investigated by scanning electron microscopy. Data on the microsculpture of the outer surface of glochidial valves are given. Among the three genera discussed, the glochidia of Anodonta are the largest, with a loose-looped outer microsculpture and numerous granules. The glochidia of Kunashiria and Sinanodonta differ by the valve height--length proportions and some details of the outer microsculpture: glochidia of Kunashiria have a tight-looped outer sculpture while the glochidia of Sinanodonta have a loose-net outer sculpture. PMID:27396177

  8. Lower Oligocene bivalves of Ramanian Stage from Kachchh, Gujarat, India

    NASA Astrophysics Data System (ADS)

    Kachhara, R. P.; Jodhawat, R. L.; Devi, K. Bigyapati

    2012-04-01

    Marine Oligocene sequences in India outcrop only in western part of Kachchh. Earlier researchers have recognized the Oligocene strata under the Nari Series (Nagappa 1959; Chatterji and Mathur 1966). The Nari Series has a type area in Pakistan. It has two subdivisions - the Lower Nari (Lower Oligocene) and the Upper Nari (Upper Oligocene). It seems that there is no valid proof about the age of the Lower Nari due to lack of proper fauna (Eames 1975), and according to Pascoe (1962), the Upper Nari slightly transgress into Aquitanian (Lower Miocene), therefore, one has to be very cautious. Biswas and Raju (1971) reclassified the Oligocene strata of Kachchh and lithostratigraphically clubbed them as the Maniyara Fort Formation with type section along the Bermoti stream. This Formation has four members. The lower three members correspond to the Ramanian Stage (Lower Oligocene, Biswas 1971, 1973) while the uppermost to the Waiorian Stage (Upper Oligocene, Biswas 1965, 1971, 1973). The Ramanian Stage is characterized by large forams especially Nummulites fichteli, Nummulites fichteli intermedius, Lepidocyclina ( Eulepidina) dialata and Operculina sp. Several ostracods are also known to occur. Megafauna include bivalves, gastropods, echinoids, corals, mammals and reptiles. Concerning bivalves earlier researchers have recorded a few taxa namely Trisidos semitorta (Lamarck), Cubitostrea angulata (J de C Sowerby), Pecten ( Amussiopecten) labadyei d'Archiac and Haime, Periglypta puerpera (Linne') var. aglaurae Brongniart, Ostrea fraasi Mayer Eymer and listed Pecten laevicostatus J de C Sowerby, Callista pseudoumbonella Vredenburg and Clementia papyracea (Gray) from Kachchh as against overall 42 forms from the Nari Series as a whole (Vredenburg 1928). This tempted us to make an attempt to collect bivalve fauna systematically which are occurring prolifically in the Ramanian Stage. In the present work, for this purpose, sections are worked out around Lakhpat (23°50'N; 68°47'E

  9. Toxic dinoflagellates and Vibrio spp. act independently in bivalve larvae.

    PubMed

    De Rijcke, M; Van Acker, E; Nevejan, N; De Schamphelaere, K A C; Janssen, C R

    2016-10-01

    Harmful algal blooms (HABs) and marine pathogens - like Vibrio spp. - are increasingly common due to climate change. These stressors affect the growth, viability and development of bivalve larvae. Little is known, however, about the potential for interactions between these two concurrent stressors. While some mixed exposures have been performed with adult bivalves, no such work has been done with larvae which are generally more sensitive. This study examines whether dinoflagellates and bacteria may interactively affect the viability and immunological resilience of blue mussel Mytilus edulis larvae. Embryos were exposed to environmentally relevant concentrations (100, 500, 2500 & 12,500 cells ml(-1)) of a dinoflagellate (Alexandrium minutum, Alexandrium ostenfeldii, Karenia mikimotoi, Protoceratium reticulatum, Prorocentrum cordatum, P. lima or P. micans), a known pathogen (Vibrio coralliilyticus/neptunius-like isolate or Vibrio splendidus; 10(5) CFU ml(-1)), or both. After five days of exposure, significant (p < 0.05) adverse effects on larval viability and larval development were found for all dinoflagellates (except P. cordatum) and V. splendidus. Yet, despite the individual effect of each stressor, no significant interactions were found between the pathogens and harmful algae. The larval viability and the phenoloxidase innate immune system responded independently to each stressor. This independence may be related to a differential timing of the effects of HABs and pathogens.

  10. The miRNA biogenesis in marine bivalves

    PubMed Central

    Rosani, Umberto; Pallavicini, Alberto

    2016-01-01

    Small non-coding RNAs include powerful regulators of gene expression, transposon mobility and virus activity. Among the various categories, mature microRNAs (miRNAs) guide the translational repression and decay of several targeted mRNAs. The biogenesis of miRNAs depends on few gene products, essentially conserved from basal to higher metazoans, whose protein domains allow specific interactions with dsRNA. Here, we report the identification of key genes responsible of the miRNA biogenesis in 32 bivalves, with particular attention to the aquaculture species Mytilus galloprovincialis and Crassostrea gigas. In detail, we have identified and phylogenetically compared eight evolutionary conserved proteins: DROSHA, DGCR8, EXP5, RAN, DICER TARBP2, AGO and PIWI. In mussels, we recognized several other proteins participating in the miRNA biogenesis or in the subsequent RNA silencing. According to digital expression analysis, these genes display low and not inducible expression levels in adult mussels and oysters whereas they are considerably expressed during development. As miRNAs play an important role also in the antiviral responses, knowledge on their production and regulative effects can shed light on essential molecular processes and provide new hints for disease prevention in bivalves. PMID:26989613

  11. Magnetosome-containing bacteria living as symbionts of bivalves.

    PubMed

    Dufour, Suzanne C; Laurich, Jason R; Batstone, Rebecca T; McCuaig, Bonita; Elliott, Alexander; Poduska, Kristin M

    2014-12-01

    Bacteria containing magnetosomes (protein-bound nanoparticles of magnetite or greigite) are common to many sedimentary habitats, but have never been found before to live within another organism. Here, we show that octahedral inclusions in the extracellular symbionts of the marine bivalve Thyasira cf. gouldi contain iron, can exhibit magnetic contrast and are most likely magnetosomes. Based on 16S rRNA sequence analysis, T. cf. gouldi symbionts group with symbiotic and free-living sulfur-oxidizing, chemolithoautotrophic gammaproteobacteria, including the symbionts of other thyasirids. T. cf. gouldi symbionts occur both among the microvilli of gill epithelial cells and in sediments surrounding the bivalves, and are therefore facultative. We propose that free-living T. cf. gouldi symbionts use magnetotaxis as a means of locating the oxic-anoxic interface, an optimal microhabitat for chemolithoautotrophy. T. cf. gouldi could acquire their symbionts from near-burrow sediments (where oxic-anoxic interfaces likely develop due to the host's bioirrigating behavior) using their superextensile feet, which could transfer symbionts to gill surfaces upon retraction into the mantle cavity. Once associated with their host, however, symbionts need not maintain structures for magnetotaxis as the host makes oxygen and reduced sulfur available via bioirrigation and sulfur-mining behaviors. Indeed, we show that within the host, symbionts lose the integrity of their magnetosome chain (and possibly their flagellum). Symbionts are eventually endocytosed and digested in host epithelial cells, and magnetosomes accumulate in host cytoplasm. Both host and symbiont behaviors appear important to symbiosis establishment in thyasirids.

  12. Deployed bivalves (oysters and clams) as indicators of estuarine condition

    SciTech Connect

    Ringwood, A.H.; Holland, A.F.; Keppler, C.; Wert, M.; Hyland, J.

    1995-12-31

    Hatchery-reared bivalves, oysters (Crassostrea virginica) and clams (Mercenaria mercenaria), were deployed simultaneously at reference and degraded sites in SC estuaries for approximately 1 month. Juvenile bivalves with endogenously high growth rates were used because effects on growth can be detected in a short time frame. The effects on growth and bioaccumulation of metal contaminants, as well as two biochemical indices (expression of metallothioneins, MT, and multi-xenobiotic transporting proteins, {at}R) were evaluated. Metal concentrations of sediments were also measured. Adverse effects on growth of both species were observed at degraded sites. However, oysters tended to grow more rapidly than clams, and adverse effects on oysters were more pronounced than in clams. Many of the sediments were characterized by elevated concentrations of multiple metals (Cu, Pb, Cr, etc.). However, increases in metal concentrations of oyster tissues were observed primarily with Cu, suggesting that many of the other metals had low bioavailability. There was little evidence of bioconcentration of any metals in clams. There was a significant correlation between sediment Cu and Cu in oyster tissues, but not in clams. Alterations in MT and MXR expression were also observed in oysters deployed at degraded sites. These studies suggest that oysters may be better in-situ indicators of habitat condition because they have more rapid growth rates and greater bioaccumulation potentials.

  13. Toxic dinoflagellates and Vibrio spp. act independently in bivalve larvae.

    PubMed

    De Rijcke, M; Van Acker, E; Nevejan, N; De Schamphelaere, K A C; Janssen, C R

    2016-10-01

    Harmful algal blooms (HABs) and marine pathogens - like Vibrio spp. - are increasingly common due to climate change. These stressors affect the growth, viability and development of bivalve larvae. Little is known, however, about the potential for interactions between these two concurrent stressors. While some mixed exposures have been performed with adult bivalves, no such work has been done with larvae which are generally more sensitive. This study examines whether dinoflagellates and bacteria may interactively affect the viability and immunological resilience of blue mussel Mytilus edulis larvae. Embryos were exposed to environmentally relevant concentrations (100, 500, 2500 & 12,500 cells ml(-1)) of a dinoflagellate (Alexandrium minutum, Alexandrium ostenfeldii, Karenia mikimotoi, Protoceratium reticulatum, Prorocentrum cordatum, P. lima or P. micans), a known pathogen (Vibrio coralliilyticus/neptunius-like isolate or Vibrio splendidus; 10(5) CFU ml(-1)), or both. After five days of exposure, significant (p < 0.05) adverse effects on larval viability and larval development were found for all dinoflagellates (except P. cordatum) and V. splendidus. Yet, despite the individual effect of each stressor, no significant interactions were found between the pathogens and harmful algae. The larval viability and the phenoloxidase innate immune system responded independently to each stressor. This independence may be related to a differential timing of the effects of HABs and pathogens. PMID:27554394

  14. Flexible digestion strategies and trace metal assimilation in marine bivalves

    USGS Publications Warehouse

    Decho, Alan W.; Luoma, Samuel N.

    1996-01-01

    Pulse-chase experiments show that two marine bivalves take optimal advantage of different types of particulate food by varying food retention time in a flexible two-phase digestive system. For example, carbon is efficiently assimilated from bacteria by subjecting nearly all the ingested bacteria to prolonged digestion. Prolonging digestion also enhances assimilation of metals, many of which are toxic in minute quantities if they are biologically available. Detritus-feeding aquatic organisms have always lived in environments naturally rich in particle-reactive metals. We suggest that avoiding excess assimilation of metals could be a factor in the evolution of digestion strategies. We tested that suggestion by studying digestion of particles containing different Cr concentrations. We show that bivalves are capable of modifying the digestive processing of food to reduce exposure to high, biologically available, Cr concentrations. The evolution of a mechanism in some species to avoid high concentrations of metals in food could influence how effects of modern metal pollution are manifested in marine ecosystems.

  15. The miRNA biogenesis in marine bivalves.

    PubMed

    Rosani, Umberto; Pallavicini, Alberto; Venier, Paola

    2016-01-01

    Small non-coding RNAs include powerful regulators of gene expression, transposon mobility and virus activity. Among the various categories, mature microRNAs (miRNAs) guide the translational repression and decay of several targeted mRNAs. The biogenesis of miRNAs depends on few gene products, essentially conserved from basal to higher metazoans, whose protein domains allow specific interactions with dsRNA. Here, we report the identification of key genes responsible of the miRNA biogenesis in 32 bivalves, with particular attention to the aquaculture species Mytilus galloprovincialis and Crassostrea gigas. In detail, we have identified and phylogenetically compared eight evolutionary conserved proteins: DROSHA, DGCR8, EXP5, RAN, DICER TARBP2, AGO and PIWI. In mussels, we recognized several other proteins participating in the miRNA biogenesis or in the subsequent RNA silencing. According to digital expression analysis, these genes display low and not inducible expression levels in adult mussels and oysters whereas they are considerably expressed during development. As miRNAs play an important role also in the antiviral responses, knowledge on their production and regulative effects can shed light on essential molecular processes and provide new hints for disease prevention in bivalves. PMID:26989613

  16. Spermatozoan ultrastructure in the trigonioid bivalve Neotrigonia margaritacea Lamarck (Mollusca): Comparison with other bivalves, especially Trigonioida and Unionoida

    NASA Astrophysics Data System (ADS)

    Healy, J. M.

    1996-06-01

    Spermatozoa of the trigonioid bivalve Neotrigonia margaritacea (Lamarck) (Trigoniidae, Trigonioida) are examined ultrastructurally. A cluster of discoidal, proacrosomal vesicles (between 9 to 15 in number) constitutes the acrosomal complex at the nuclear apex. The nucleus is short (2.4 2.6 μm long, maximum diameter 2.2 μm), blunt-conical in shape, and exhibits irregular lacunae within its contents. Five or sometimes four round mitochondria are impressed into shallow depressions in the base of the nucleus as is a discrete centriolar fossa. The mitochondria surround two orthogonally arranged centrioles to form, collectively, the midpiece region. The distal centriole, anchored by nine satellite fibres to the plasma membrane, acts as a basal body to the sperm flagellum. The presence of numerous proacrosomal vesicles instead of a single, conical acrosomal vesicle sets Neotrigonia (and the Trigonioida) apart from other bivalves, with the exception of the Unionoida which are also known to exhibit this multivesicular condition. Spermatozoa of N. margaritacea are very similar to those of the related species Neotrigonia bednalli (Verco) with the exception that the proacrosomal vesicles of N. margaritacea are noticeably larger than those of N. bednalli.

  17. Metabolic dominance of bivalves predates brachiopod diversity decline by more than 150 million years.

    PubMed

    Payne, Jonathan L; Heim, Noel A; Knope, Matthew L; McClain, Craig R

    2014-05-22

    Brachiopods and bivalves feed in similar ways and have occupied the same environments through geological time, but brachiopods were far more diverse and abundant in the Palaeozoic whereas bivalves dominate the post-Palaeozoic, suggesting a transition in ecological dominance 250 Ma. However, diversity and abundance data alone may not adequately describe key changes in ecosystem function, such as metabolic activity. Here, we use newly compiled body size data for 6066 genera of bivalves and brachiopods to calculate metabolic rates and revisit this question from the perspective of energy use, finding that bivalves already accounted for a larger share of metabolic activity in Palaeozoic oceans. We also find that the metabolic activity of bivalves has increased by more than two orders of magnitude over this interval, whereas brachiopod metabolic activity has declined by more than 50%. Consequently, the increase in bivalve energy metabolism must have occurred via the acquisition of new food resources rather than through the displacement of brachiopods. The canonical view of a mid-Phanerozoic transition from brachiopod to bivalve dominance results from a focus on taxonomic diversity and numerical abundance as measures of ecological importance. From a metabolic perspective, the oceans have always belonged to the clams.

  18. Two-Compartment Kinetic Modeling of Radiocesium Accumulation in Marine Bivalves under Hypothetical Exposure Regimes.

    PubMed

    Pan, Ke; Tan, Qiao-Guo; Wang, Wen-Xiong

    2016-03-01

    Interpreting the variable concentrations of (137)Cs in the field biological samples requires mechanistic understanding of both environmental and biological behavior of (137)Cs. In this study, we used a two-compartment model to estimate and compare the (137)Cs biokinetics in three species of subtropical marine bivalves. Significant interspecific difference of (137)Cs biokinetics was observed among oysters, mussels, and scallops. There was considerable (137)Cs assimilation from phytoplankton in the bivalves, but the calculated trophic transfer factors were generally between 0.04 and 0.4. We demonstrated a major efflux of radiocesium in the scallops (with a rate constant of 0.207 d(-1)), whereas the efflux was comparable between oysters and mussels (0.035-0.038 d(-1)). A two-compartment kinetic model was developed to simulate the (137)Cs accumulation in the three bivalves under four hypothetical exposure regimes. We showed that the bivalves respond differently to the exposure regimes in terms of time to reach equilibrium, equilibrium concentration, and maximum concentration. Bivalves suffering more frequent intermittent exposure may have higher maximum concentrations than those receiving less frequent exposure. The interspecific difference of (137)Cs accumulation in bivalves has important implications for biomonitoring and implementing management techniques. This study represents one of the first attempts to combine both dissolved and dietary pathways to give a realistic simulation of (137)Cs accumulation in marine bivalves under dynamic exposure regimes.

  19. Metabolic dominance of bivalves predates brachiopod diversity decline by more than 150 million years

    PubMed Central

    Payne, Jonathan L.; Heim, Noel A.; Knope, Matthew L.; McClain, Craig R.

    2014-01-01

    Brachiopods and bivalves feed in similar ways and have occupied the same environments through geological time, but brachiopods were far more diverse and abundant in the Palaeozoic whereas bivalves dominate the post-Palaeozoic, suggesting a transition in ecological dominance 250 Ma. However, diversity and abundance data alone may not adequately describe key changes in ecosystem function, such as metabolic activity. Here, we use newly compiled body size data for 6066 genera of bivalves and brachiopods to calculate metabolic rates and revisit this question from the perspective of energy use, finding that bivalves already accounted for a larger share of metabolic activity in Palaeozoic oceans. We also find that the metabolic activity of bivalves has increased by more than two orders of magnitude over this interval, whereas brachiopod metabolic activity has declined by more than 50%. Consequently, the increase in bivalve energy metabolism must have occurred via the acquisition of new food resources rather than through the displacement of brachiopods. The canonical view of a mid-Phanerozoic transition from brachiopod to bivalve dominance results from a focus on taxonomic diversity and numerical abundance as measures of ecological importance. From a metabolic perspective, the oceans have always belonged to the clams. PMID:24671970

  20. Clinical and genetic characterization of pituitary gigantism: an international collaborative study in 208 patients.

    PubMed

    Rostomyan, Liliya; Daly, Adrian F; Petrossians, Patrick; Nachev, Emil; Lila, Anurag R; Lecoq, Anne-Lise; Lecumberri, Beatriz; Trivellin, Giampaolo; Salvatori, Roberto; Moraitis, Andreas G; Holdaway, Ian; Kranenburg-van Klaveren, Dianne J; Chiara Zatelli, Maria; Palacios, Nuria; Nozieres, Cecile; Zacharin, Margaret; Ebeling, Tapani; Ojaniemi, Marja; Rozhinskaya, Liudmila; Verrua, Elisa; Jaffrain-Rea, Marie-Lise; Filipponi, Silvia; Gusakova, Daria; Pronin, Vyacheslav; Bertherat, Jerome; Belaya, Zhanna; Ilovayskaya, Irena; Sahnoun-Fathallah, Mona; Sievers, Caroline; Stalla, Gunter K; Castermans, Emilie; Caberg, Jean-Hubert; Sorkina, Ekaterina; Auriemma, Renata Simona; Mittal, Sachin; Kareva, Maria; Lysy, Philippe A; Emy, Philippe; De Menis, Ernesto; Choong, Catherine S; Mantovani, Giovanna; Bours, Vincent; De Herder, Wouter; Brue, Thierry; Barlier, Anne; Neggers, Sebastian J C M M; Zacharieva, Sabina; Chanson, Philippe; Shah, Nalini Samir; Stratakis, Constantine A; Naves, Luciana A; Beckers, Albert

    2015-10-01

    Despite being a classical growth disorder, pituitary gigantism has not been studied previously in a standardized way. We performed a retrospective, multicenter, international study to characterize a large series of pituitary gigantism patients. We included 208 patients (163 males; 78.4%) with growth hormone excess and a current/previous abnormal growth velocity for age or final height >2 s.d. above country normal means. The median onset of rapid growth was 13 years and occurred significantly earlier in females than in males; pituitary adenomas were diagnosed earlier in females than males (15.8 vs 21.5 years respectively). Adenomas were ≥10 mm (i.e., macroadenomas) in 84%, of which extrasellar extension occurred in 77% and invasion in 54%. GH/IGF1 control was achieved in 39% during long-term follow-up. Final height was greater in younger onset patients, with larger tumors and higher GH levels. Later disease control was associated with a greater difference from mid-parental height (r=0.23, P=0.02). AIP mutations occurred in 29%; microduplication at Xq26.3 - X-linked acrogigantism (X-LAG) - occurred in two familial isolated pituitary adenoma kindreds and in ten sporadic patients. Tumor size was not different in X-LAG, AIP mutated and genetically negative patient groups. AIP-mutated and X-LAG patients were significantly younger at onset and diagnosis, but disease control was worse in genetically negative cases. Pituitary gigantism patients are characterized by male predominance and large tumors that are difficult to control. Treatment delay increases final height and symptom burden. AIP mutations and X-LAG explain many cases, but no genetic etiology is seen in >50% of cases. PMID:26187128

  1. Clinical and genetic characterization of pituitary gigantism: an international collaborative study in 208 patients.

    PubMed

    Rostomyan, Liliya; Daly, Adrian F; Petrossians, Patrick; Nachev, Emil; Lila, Anurag R; Lecoq, Anne-Lise; Lecumberri, Beatriz; Trivellin, Giampaolo; Salvatori, Roberto; Moraitis, Andreas G; Holdaway, Ian; Kranenburg-van Klaveren, Dianne J; Chiara Zatelli, Maria; Palacios, Nuria; Nozieres, Cecile; Zacharin, Margaret; Ebeling, Tapani; Ojaniemi, Marja; Rozhinskaya, Liudmila; Verrua, Elisa; Jaffrain-Rea, Marie-Lise; Filipponi, Silvia; Gusakova, Daria; Pronin, Vyacheslav; Bertherat, Jerome; Belaya, Zhanna; Ilovayskaya, Irena; Sahnoun-Fathallah, Mona; Sievers, Caroline; Stalla, Gunter K; Castermans, Emilie; Caberg, Jean-Hubert; Sorkina, Ekaterina; Auriemma, Renata Simona; Mittal, Sachin; Kareva, Maria; Lysy, Philippe A; Emy, Philippe; De Menis, Ernesto; Choong, Catherine S; Mantovani, Giovanna; Bours, Vincent; De Herder, Wouter; Brue, Thierry; Barlier, Anne; Neggers, Sebastian J C M M; Zacharieva, Sabina; Chanson, Philippe; Shah, Nalini Samir; Stratakis, Constantine A; Naves, Luciana A; Beckers, Albert

    2015-10-01

    Despite being a classical growth disorder, pituitary gigantism has not been studied previously in a standardized way. We performed a retrospective, multicenter, international study to characterize a large series of pituitary gigantism patients. We included 208 patients (163 males; 78.4%) with growth hormone excess and a current/previous abnormal growth velocity for age or final height >2 s.d. above country normal means. The median onset of rapid growth was 13 years and occurred significantly earlier in females than in males; pituitary adenomas were diagnosed earlier in females than males (15.8 vs 21.5 years respectively). Adenomas were ≥10 mm (i.e., macroadenomas) in 84%, of which extrasellar extension occurred in 77% and invasion in 54%. GH/IGF1 control was achieved in 39% during long-term follow-up. Final height was greater in younger onset patients, with larger tumors and higher GH levels. Later disease control was associated with a greater difference from mid-parental height (r=0.23, P=0.02). AIP mutations occurred in 29%; microduplication at Xq26.3 - X-linked acrogigantism (X-LAG) - occurred in two familial isolated pituitary adenoma kindreds and in ten sporadic patients. Tumor size was not different in X-LAG, AIP mutated and genetically negative patient groups. AIP-mutated and X-LAG patients were significantly younger at onset and diagnosis, but disease control was worse in genetically negative cases. Pituitary gigantism patients are characterized by male predominance and large tumors that are difficult to control. Treatment delay increases final height and symptom burden. AIP mutations and X-LAG explain many cases, but no genetic etiology is seen in >50% of cases.

  2. Formación y evolución de planetas gigantes

    NASA Astrophysics Data System (ADS)

    Benvenuto, O. G.; Brunini, A.

    Presentamos el estado actual del trabajo que estamos realizando en el estudio de la formación de planetas gigantes. Detallamos los algoritmos numéricos necesarios para realizar este tipo de cálculo. Presentamos algunos resultados de la formación de objetos con masas de hasta una docena de veces la del planeta Júpiter, resaltando las principales caracteríticas. Finalmente detallamos los problemas que pensamos abordar en un futuro cercano en este tema de investigación.

  3. Velocidades radiales de estrellas gigantes rojas y blue stragglers en cúmulos abiertos

    NASA Astrophysics Data System (ADS)

    González, J. F.; Lapasset, E.

    Se presentan mediciones de las estrellas más brillantes en los campos de los cúmulos abiertos NGC 6530, NGC 2516, NGC 3114, Cr 223 y NGC 2437. Mediante correlaciones cruzadas se obtiene la velocidad de unas 25 gigantes rojas con el objeto de derivar la velocidad media de cada asociación. En base a los espectros obtenidos de los blue stragglers se discuten sus principales características y su probabilidad de pertenencia. Finalmente, se presentan las observaciones para cinco nuevas binarias espectroscópicas detectadas.

  4. Vínculos observacionais para o processo-S em estrelas gigantes de Bário

    NASA Astrophysics Data System (ADS)

    Smiljanic, R. H. S.; Porto de Mello, G. F.; da Silva, L.

    2003-08-01

    Estrelas de bário são gigantes vermelhas de tipo GK que apresentam excessos atmosféricos dos elementos do processo-s. Tais excessos são esperados em estrelas na fase de pulsos térmicos do AGB (TP-AGB). As estrelas de bário são, no entanto, menos massivas e menos luminosas que as estrelas do AGB, assim, não poderiam ter se auto-enriquecido. Seu enriquecimento teria origem em uma estrela companheira, inicialmente mais massiva, que evolui pelo TP-AGB, se auto-enriquece com os elementos do processo-s e transfere material contaminado para a atmosfera da atual estrela de bário. A companheira evolui então para anã branca deixando de ser observada diretamente. As estrelas de bário são, portanto, úteis como testes observacionais para teorias de nucleossíntese pelo processo-s, convecção e perda de massa. Análises detalhadas de abundância com dados de alta qualidade para estes objetos são ainda escassas na literatura. Neste trabalho construímos modelos de atmosferas e, procedendo a uma análise diferencial, determinamos parâmetros atmosféricos e evolutivos de uma amostra de dez gigantes de bário e quatro normais. Determinamos seus padrões de abundância para Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, Sm, Eu e Gd, concluindo que algumas estrelas classificadas na literatura como gigantes de bário são na verdade gigantes normais. Comparamos dois padrões médios de abundância, para estrelas com grandes excessos e estrelas com excessos moderados, com modelos teóricos de enriquecimento pelo processo-s. Os dois grupos de estrelas são ajustados pelos mesmos parâmetros de exposição de nêutrons. Tal resultado sugere que a ocorrência do fenômeno de bário com diferentes intensidades não se deve a diferentes exposições de nêutrons. Discutimos ainda efeitos nucleossintéticos, ligados ao processo-s, sugeridos na literatura para os elementos Cu, Mn, V e Sc.

  5. A new Rosalina (foraminifera) parasitic on a bivalve

    USGS Publications Warehouse

    Todd, R.

    1965-01-01

    In a collection of pelecypods from deep water off the west coast of Africa, several specimens of a new species of the foraminifer, Rosalina, are attached to the umbonal area of the bivalve. In addition, numerous attachment scars are observed on the exterior surface with interconnected penetration scars on the interior surface of the valves. It is speculated that the foraminifer made the partial or complete penetration of the clam shell in connection with its search for calcium carbonate for shell-building. From the nature of the scars on the interior of the valves, it is clear that the clam was alive, because there are mounded up shell deposits around some of the openings and others are completely sealed shut by shell material deposited by the clam. ?? 1965.

  6. Selectivity of end-Cretaceous marine bivalve extinctions.

    PubMed

    Jablonski, D; Raup, D M

    1995-04-21

    Analyses of the end-Cretaceous or Cretaceous-Tertiary mass extinction show no selectivity of marine bivalve genera by life position (burrowing versus exposed), body size, bathymetric position on the continental shelf, or relative breadth of bathymetric range. Deposit-feeders as a group have significantly lower extinction intensities than suspension-feeders, but this pattern is due entirely to low extinction in two groups (Nuculoida and Lucinoidea), which suggests that survivorship was not simply linked to feeding mode. Geographically widespread genera have significantly lower extinction intensities than narrowly distributed genera. These results corroborate earlier work suggesting that some biotic factors that enhance survivorship during times of lesser extinction intensities are ineffectual during mass extinctions.

  7. Selectivity of end-Cretaceous marine bivalve extinctions

    NASA Technical Reports Server (NTRS)

    Jablonski, D.; Raup, D. M.

    1995-01-01

    Analyses of the end-Cretaceous or Cretaceous-Tertiary mass extinction show no selectivity of marine bivalve genera by life position (burrowing versus exposed), body size, bathymetric position on the continental shelf, or relative breadth of bathymetric range. Deposit-feeders as a group have significantly lower extinction intensities than suspension-feeders, but this pattern is due entirely to low extinction in two groups (Nuculoida and Lucinoidea), which suggests that survivorship was not simply linked to feeding mode. Geographically widespread genera have significantly lower extinction intensities than narrowly distributed genera. These results corroborate earlier work suggesting that some biotic factors that enhance survivorship during times of lesser extinction intensities are ineffectual during mass extinctions.

  8. Reproductive investment in the intertidal bivalve Macoma balthica

    NASA Astrophysics Data System (ADS)

    Honkoop, P. J. C.; Van der Meer, J.; Beukema, J. J.; Kwast, D.

    1999-05-01

    Bivalve eggs generally contain large amounts of lipids which, in comparison with proteins and carbohydrates, have high energy contents and are thus costly in energetic terms. As lipid contents vary between species, comparisons of reproductive investments should not only include numbers and sizes of eggs, but also their energy content. We estimated the investment in egg material of mature females of the Baltic tellin Macoma balthica (L.) in terms of both mass and energy content. All mass below a minimum body mass (below which no eggs are produced) was defined as structural mass. This threshold amounts to a body mass index (BMI) of 5.6 (ash-free dry mass per cubic shell length in mg cm -3). More than half (55%) of the mass above the structural mass was invested in egg material and 45% in extra somatic tissue and tissue for production and storage of gametes. This means that the amount of eggs spawned ranged from 0 (at BMI = 5.6 mg cm -3) to 33% of the total ash-free dry mass (at a high BMI value of 14 mg cm -3). Eggs contained a relatively large amount of lipids, about 30% of their ash-free dry mass, whereas non-egg material contained only about 7% lipids. Eggs of two other bivalves in the Wadden Sea, the cockle Cerastoderma edule and the mussel Mytilus edulis, were smaller and contained only about 11% and 20% lipids, respectively. Energy content of M. balthica eggs amounted to ˜0.006 J, in the other two species to ˜0.002 J. The function of the more expensive eggs in M. balthica may be related to its early spawning in spring, causing slower larval development until first feeding.

  9. Life history traits to predict biogeographic species distributions in bivalves

    NASA Astrophysics Data System (ADS)

    Montalto, V.; Rinaldi, A.; Sarà, G.

    2015-10-01

    Organismal fecundity ( F) and its relationship with body size (BS) are key factors in predicting species distribution under current and future scenarios of global change. A functional trait-based dynamic energy budget (FT-DEB) is proposed as a mechanistic approach to predict the variation of F and BS as function of environmental correlates using two marine bivalves as model species ( Mytilus galloprovincialis and Brachidontes pharaonis). Validation proof of model skill (i.e., degree of correspondence between model predictions and field observations) and stationarity (i.e., ability of a model generated from data collected at one place/time to predict processes at another place/time) was provided to test model performance in predicting the bivalve distribution throughout the 22 sites in the Central Mediterranean Sea under local conditions of food density and body temperature. Model skill and stationarity were tested through the estimate of commission (i.e., proportion of species' absences predicted present) and omission (i.e., proportion of presences predicted absent) errors of predictions by comparing mechanistic predicted vs. observed F and BS values throughout the study area extrapolated by lab experiments and literature search. The resulting relationship was reliable for both species, and body size and fecundity were highly correlated in M. galloprovincialis compared to B. pharaonis; FT-DEB showed correct predictions of presence in more than 75 % of sites, and the regression between BS predicted vs. observed was highly significant in both species. Whilst recognising the importance of biotic interactions in shaping the distribution of species, our FT-DEB approach provided reliable quantitative estimates of where our species had sufficient F to support local populations or suggesting reproductive failure. Mechanistically, estimating F and BS as key traits of species life history can also be addressed within a broader, scale-dependent context that surpasses the

  10. Life history traits to predict biogeographic species distributions in bivalves.

    PubMed

    Montalto, V; Rinaldi, A; Sarà, G

    2015-10-01

    Organismal fecundity (F) and its relationship with body size (BS) are key factors in predicting species distribution under current and future scenarios of global change. A functional trait-based dynamic energy budget (FT-DEB) is proposed as a mechanistic approach to predict the variation of F and BS as function of environmental correlates using two marine bivalves as model species (Mytilus galloprovincialis and Brachidontes pharaonis). Validation proof of model skill (i.e., degree of correspondence between model predictions and field observations) and stationarity (i.e., ability of a model generated from data collected at one place/time to predict processes at another place/time) was provided to test model performance in predicting the bivalve distribution throughout the 22 sites in the Central Mediterranean Sea under local conditions of food density and body temperature. Model skill and stationarity were tested through the estimate of commission (i.e., proportion of species' absences predicted present) and omission (i.e., proportion of presences predicted absent) errors of predictions by comparing mechanistic predicted vs. observed F and BS values throughout the study area extrapolated by lab experiments and literature search. The resulting relationship was reliable for both species, and body size and fecundity were highly correlated in M. galloprovincialis compared to B. pharaonis; FT-DEB showed correct predictions of presence in more than 75 % of sites, and the regression between BS predicted vs. observed was highly significant in both species. Whilst recognising the importance of biotic interactions in shaping the distribution of species, our FT-DEB approach provided reliable quantitative estimates of where our species had sufficient F to support local populations or suggesting reproductive failure. Mechanistically, estimating F and BS as key traits of species life history can also be addressed within a broader, scale-dependent context that surpasses the

  11. Evolutionary implications of endosymbiont diversity within lucinid bivalves

    NASA Astrophysics Data System (ADS)

    Garcia, A. M.; Thiessen, M.; Aronowsky, A.; Anderson, L.; Bao, H.; Engel, A.

    2007-12-01

    Bacterial endosymbiosis is widespread among Bivalvia. Symbiosis between lucinid bivalves and sulfur-oxidizing (thiotrophic) bacteria has received recent attention, as lucinids are one of the geologically oldest extant bivalve clades to possess endosymbionts. However, the ecological and evolutionary relationships between host and symbiont are poorly understood, and reconstructing the evolutionary history and geological significance of lucinid endosymbiosis requires additional knowledge and characterization of endosymbiont ecology and taxonomic diversity. Our goal was to characterize the bacterial diversity of a modern lucinid habitat in order to evaluate possible lucinid endosymbiont diversity. Host organisms ( Lucinisca nassula and Phacoides pectinatus) and sediment cores were collected from geochemically reducing and sulfide-rich sea grass beds. PCR amplification and sequencing of bacterial 16S rRNA genes from the sediment cores retrieved 13 major taxonomic groups, including equally dominant Chloroflexi, Delta-, and Gammaproteobacteria, and rare Bacteroides, Acidobacteria, Spirochaetes, and Firmicutes. Less than 2% of the sequences were affiliated with uncultured gammaproteobacterial symbiont groups, but were not closely related to the sequences retrieved from the lucinid gills. Moreover, our analyses uncovered multiple gene sequence populations within an individual, as well as across individuals within the same sampling site. Additional habitat-host-symbiont diversity from three other lucinid taxa and from six geographically distinct habitat sites is also expanding the previously understood diversity of thiotrophic endosymbionts, and specifically that the lucinid symbionts are probably not a monophyletic species. These data suggest that thiotrophic bacteria are recruitable for endosymbiosis and are widely distributed in reducing marine environments. But, because of the diversity of bacteria in any one habitat, symbionts may be metabolically and physiologically

  12. Life history traits to predict biogeographic species distributions in bivalves.

    PubMed

    Montalto, V; Rinaldi, A; Sarà, G

    2015-10-01

    Organismal fecundity (F) and its relationship with body size (BS) are key factors in predicting species distribution under current and future scenarios of global change. A functional trait-based dynamic energy budget (FT-DEB) is proposed as a mechanistic approach to predict the variation of F and BS as function of environmental correlates using two marine bivalves as model species (Mytilus galloprovincialis and Brachidontes pharaonis). Validation proof of model skill (i.e., degree of correspondence between model predictions and field observations) and stationarity (i.e., ability of a model generated from data collected at one place/time to predict processes at another place/time) was provided to test model performance in predicting the bivalve distribution throughout the 22 sites in the Central Mediterranean Sea under local conditions of food density and body temperature. Model skill and stationarity were tested through the estimate of commission (i.e., proportion of species' absences predicted present) and omission (i.e., proportion of presences predicted absent) errors of predictions by comparing mechanistic predicted vs. observed F and BS values throughout the study area extrapolated by lab experiments and literature search. The resulting relationship was reliable for both species, and body size and fecundity were highly correlated in M. galloprovincialis compared to B. pharaonis; FT-DEB showed correct predictions of presence in more than 75 % of sites, and the regression between BS predicted vs. observed was highly significant in both species. Whilst recognising the importance of biotic interactions in shaping the distribution of species, our FT-DEB approach provided reliable quantitative estimates of where our species had sufficient F to support local populations or suggesting reproductive failure. Mechanistically, estimating F and BS as key traits of species life history can also be addressed within a broader, scale-dependent context that surpasses the

  13. Magnetosome-containing bacteria living as symbionts of bivalves

    PubMed Central

    Dufour, Suzanne C; Laurich, Jason R; Batstone, Rebecca T; McCuaig, Bonita; Elliott, Alexander; Poduska, Kristin M

    2014-01-01

    Bacteria containing magnetosomes (protein-bound nanoparticles of magnetite or greigite) are common to many sedimentary habitats, but have never been found before to live within another organism. Here, we show that octahedral inclusions in the extracellular symbionts of the marine bivalve Thyasira cf. gouldi contain iron, can exhibit magnetic contrast and are most likely magnetosomes. Based on 16S rRNA sequence analysis, T. cf. gouldi symbionts group with symbiotic and free-living sulfur-oxidizing, chemolithoautotrophic gammaproteobacteria, including the symbionts of other thyasirids. T. cf. gouldi symbionts occur both among the microvilli of gill epithelial cells and in sediments surrounding the bivalves, and are therefore facultative. We propose that free-living T. cf. gouldi symbionts use magnetotaxis as a means of locating the oxic–anoxic interface, an optimal microhabitat for chemolithoautotrophy. T. cf. gouldi could acquire their symbionts from near-burrow sediments (where oxic–anoxic interfaces likely develop due to the host's bioirrigating behavior) using their superextensile feet, which could transfer symbionts to gill surfaces upon retraction into the mantle cavity. Once associated with their host, however, symbionts need not maintain structures for magnetotaxis as the host makes oxygen and reduced sulfur available via bioirrigation and sulfur-mining behaviors. Indeed, we show that within the host, symbionts lose the integrity of their magnetosome chain (and possibly their flagellum). Symbionts are eventually endocytosed and digested in host epithelial cells, and magnetosomes accumulate in host cytoplasm. Both host and symbiont behaviors appear important to symbiosis establishment in thyasirids. PMID:24914799

  14. Protozoan parasites of bivalve molluscs: literature follows culture.

    PubMed

    Fernández Robledo, José A; Vasta, Gerardo R; Record, Nicholas R

    2014-01-01

    Bivalve molluscs are key components of the estuarine environments as contributors to the trophic chain, and as filter -feeders, for maintaining ecosystem integrity. Further, clams, oysters, and scallops are commercially exploited around the world both as traditional local shellfisheries, and as intensive or semi-intensive farming systems. During the past decades, populations of those species deemed of environmental or commercial interest have been subject to close monitoring given the realization that these can suffer significant decline, sometimes irreversible, due to overharvesting, environmental pollution, or disease. Protozoans of the genera Perkinsus, Haplosporidium, Marteilia, and Bonamia are currently recognized as major threats for natural and farmed bivalve populations. Since their identification, however, the variable publication rates of research studies addressing these parasitic diseases do not always appear to reflect their highly significant environmental and economic impact. Here we analyzed the peer- reviewed literature since the initial description of these parasites with the goal of identifying potential milestone discoveries or achievements that may have driven the intensity of the research in subsequent years, and significantly increased publication rates. Our analysis revealed that after initial description of the parasite as the etiological agent of a given disease, there is a time lag before a maximal number of yearly publications are reached. This has already taken place for most of them and has been followed by a decrease in publication rates over the last decade (20- to 30- year lifetime in the literature). Autocorrelation analyses, however, suggested that advances in parasite purification and culture methodologies positively drive publication rates, most likely because they usually lead to novel molecular tools and resources, promoting mechanistic studies. Understanding these trends should help researchers in prioritizing research

  15. Pinna nobilis: A big bivalve with big haemocytes?

    PubMed

    Matozzo, V; Pagano, M; Spinelli, A; Caicci, F; Faggio, C

    2016-08-01

    The fan mussel Pinna nobilis (Linnaeus, 1758) is one of the biggest bivalves worldwide. Currently, no updated information is available in the literature concerning the morpho-functional aspects of haemocytes from this bivalve species. Consequently, in this study, we characterised P. nobilis haemocytes from both a morphological and functional point of view. The mean number of haemocytes was about 5 (×10(5)) cells mL haemolymph(-1), and the cell viability was about 92-100%. Two haemocyte types were distinguished under the light microscope: granulocytes (51.6%), with evident cytoplasmic granules, and hyalinocytes (48.4%), with a few granules. The granules of the granulocytes were mainly lysosomes, as indicated by the in vivo staining with Neutral Red. Haemocytes were further distinguished in basophils (83.75%), acidophils (14.75%) and neutrophils (1.5%). After adhesion to slides and fixation, the cell diameter was approximately 10 μm for granulocytes and 7 μm for hyalinocytes. The granulocytes and hyalinocytes were both positive to the Periodic Acid-Schiff reaction for carbohydrates. Only granulocytes were able to phagocytise yeast cells. The phagocytic index (6%) increased significantly up to twofold after preincubation of yeast in cell-free haemolymph, suggesting that haemolymph has opsonising properties. In addition, haemocytes produce superoxide anion and acid and alkaline phosphatases. Summarising, this preliminary study indicates that both the granulocytes and hyalinocytes circulate in the haemolymph of P. nobilis and that they are active immunocytes. PMID:27346153

  16. Protozoan Parasites of Bivalve Molluscs: Literature Follows Culture

    PubMed Central

    Fernández Robledo, José A.; Vasta, Gerardo R.; Record, Nicholas R.

    2014-01-01

    Bivalve molluscs are key components of the estuarine environments as contributors to the trophic chain, and as filter –feeders, for maintaining ecosystem integrity. Further, clams, oysters, and scallops are commercially exploited around the world both as traditional local shellfisheries, and as intensive or semi–intensive farming systems. During the past decades, populations of those species deemed of environmental or commercial interest have been subject to close monitoring given the realization that these can suffer significant decline, sometimes irreversible, due to overharvesting, environmental pollution, or disease. Protozoans of the genera Perkinsus, Haplosporidium, Marteilia, and Bonamia are currently recognized as major threats for natural and farmed bivalve populations. Since their identification, however, the variable publication rates of research studies addressing these parasitic diseases do not always appear to reflect their highly significant environmental and economic impact. Here we analyzed the peer– reviewed literature since the initial description of these parasites with the goal of identifying potential milestone discoveries or achievements that may have driven the intensity of the research in subsequent years, and significantly increased publication rates. Our analysis revealed that after initial description of the parasite as the etiological agent of a given disease, there is a time lag before a maximal number of yearly publications are reached. This has already taken place for most of them and has been followed by a decrease in publication rates over the last decade (20– to 30– year lifetime in the literature). Autocorrelation analyses, however, suggested that advances in parasite purification and culture methodologies positively drive publication rates, most likely because they usually lead to novel molecular tools and resources, promoting mechanistic studies. Understanding these trends should help researchers in prioritizing

  17. Influence of trematode parasitism on the growth of a bivalve host in the field.

    PubMed

    Taskinen, J

    1998-04-01

    Trematode-induced gigantism of molluscs, enhanced growth of trematode-parasitised individuals, has been observed in many laboratory studies. This study reports the effect of the sterilising trematode, Rhipidicotyle fennica, on the growth of the freshwater clam Anodonta piscinalis under field conditions. In addition to single infections (prevalence 44%), a few clams (3%) were infected with both R. fennica and Rhipidicotyle campanula. Parasite-induced gigantism was not found; parasites lowered host growth. The decreased in growth was correlated with the quantity of parasite material. Clams with double infections grew the least, although they did not differ significantly from hosts with a heavy single species infection. The growth of the experimental clams was lower than that of undisturbed control clams. Trematode-induced gigantism of molluscs in the field, in general, remains undemonstrated.

  18. Bioaccumulation of 210Po in common gastropod and bivalve species from the northern Gulf.

    PubMed

    Uddin, S; Bebhehani, M

    2014-06-01

    This study sets the baseline for the concentration of the natural-series radionuclide polonium-210 in two species of gastropods and four species of bivalves that are common to the Northern Arabian/Persian Gulf. (210)Po is primarily absorbed from water and via ingestion of detrital material by gastropoda and bivalves. This concentrated (210)Po can then be passed along to the next trophic level of the marine food web. The lowest (210)Po concentration was measured in the gastropod Stomatella auricular (10.36-12.39Bq kg(-1)dry) and the highest in the bivalve Marica marmorata (193.51-215.60Bq kg(-1)dry). The measured concentration factor for these molluscs in the northern Gulf varied between 4.8 and 115×10(3), values very similar to the IAEA recommended value for bivalves and gastropods of 2×10(4).

  19. Experimental herpes-like viral infections in marine bivalves: demonstration of interspecies transmission.

    PubMed

    Arzul, I; Renault, T; Lipart, C

    2001-08-22

    Since 1972, herpes-like virus infections have been reported in several marine bivalve species around the world. Viral detection was often associated with high mortality rates in larvae and spat. To determine whether a single virus is able to infect different bivalve host species, we carried out experimental transmission assays. As a first step, 8 assays were performed to infect axenic Crassostrea gigas larvae with virus from infected C. gigas larvae using a previously described protocol. The protocol appeared reliable and PCR was confirmed as a powerful technique for detecting viral DNA in experimentally infected oysters. The defined protocol was then applied to infect different bivalve species. Interspecies viral transmission was demonstrated under laboratory conditions. The same phenomenon may occur in private hatcheries and may be promoted by intensive rearing conditions. This hypothesis is reinforced by reports of concomitant mortalities in the larvae of several bivalve species and by the first molecular analysis of infected larval samples.

  20. Bioconcentration and biotransformation of [¹⁴C]methoxychlor in the brackish water bivalve Corbicula japonica.

    PubMed

    Masuda, Minoru; Ohyama, Kazutoshi; Hayashi, Osamu; Satsuma, Koji; Sato, Kiyoshi

    2011-09-01

    To obtain basic information on the metabolic fate of xenobiotics in the brackish water, bivalve Corbicula japonica, bioconcentration and biotransformation experiments were performed using methoxychlor (MXC) as a model compound. Bivalves were exposed to [ring-U-¹⁴C]MXC (10 µg L⁻¹) for 28 days under semi-static conditions followed by a 14-day depuration phase. The ¹⁴C concentration in the bivalves rapidly increased and reached a steady state after exposure for 7 days (BCFss = 2010); however, it rapidly decreased with a half-life of 2.2 days in the depuration phase. Mono- and bis-demethylated MXC, and their corresponding sulphate conjugates, were identified as minor metabolites. No glycoside conjugates (including glucuronide and glucoside) were detected. Despite this biotransformation system, bivalves were found to excrete retained MXC mostly unchanged although its relatively hydrophobic nature.

  1. Molecular and isotopic composition of lipids in modern and fossil bivalve shells: Records of paleoenvironmental change?

    SciTech Connect

    CoBabe, E.A.

    1995-12-31

    Suites of lipids residing in situ in modern and fossil bivalve shells offer new possibilities for the study of paleoecology and paleoclimatology. Distributions of carbon isotopic compositions of modem shell lipids suggests that many of these compounds, including alkanes, sterols, fatty acids, ketones and phytadienes, are derived from the bivalves and not directly from the surrounding environment. The occurrence of fatty acids in modem and fossil shell material opens up the possibility that saturation levels of these compounds may be used as paleothermometers. To date, the utility of fatty acids in paleoclimate studies has been limited because of the swift breakdown of these compounds in sediment. However, initial results indicate that fatty acids in bivalve shells retain their original structure for at least several million years. Comparison of modem bivalve shell fatty acids from tropical, temperate and polar nearshore marine systems will be presented, along with analogous fossil data.

  2. Bioaccumulation of 210Po in common gastropod and bivalve species from the northern Gulf.

    PubMed

    Uddin, S; Bebhehani, M

    2014-06-01

    This study sets the baseline for the concentration of the natural-series radionuclide polonium-210 in two species of gastropods and four species of bivalves that are common to the Northern Arabian/Persian Gulf. (210)Po is primarily absorbed from water and via ingestion of detrital material by gastropoda and bivalves. This concentrated (210)Po can then be passed along to the next trophic level of the marine food web. The lowest (210)Po concentration was measured in the gastropod Stomatella auricular (10.36-12.39Bq kg(-1)dry) and the highest in the bivalve Marica marmorata (193.51-215.60Bq kg(-1)dry). The measured concentration factor for these molluscs in the northern Gulf varied between 4.8 and 115×10(3), values very similar to the IAEA recommended value for bivalves and gastropods of 2×10(4). PMID:24675441

  3. High pressure processing of bivalve shellfish and HPP's potential use as a virus intervention

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bivalve shellfish readily bioconcentrate pathogenic microbes and substance, such as algal and dinoflagulate toxins, fecal viruses and bacteria, and naturally present vibrio bacteria. High pressure processing (HPP) is currently used as an intervention for Vibrio vulnificus bacteria within molluscan ...

  4. Draft Genome Sequence of the New Pathogen for Bivalve Larvae Vibrio bivalvicida

    PubMed Central

    Dubert, Javier; Spinard, Edward J.; Gomez-Chiarri, Marta

    2016-01-01

    Vibrio bivalvicida is a novel pathogen of bivalve larvae responsible for recent vibriosis outbreaks affecting shellfish hatcheries. Here, we announce the draft genome sequence of V. bivalvicida 605T and describe potential virulence factors. PMID:27056224

  5. A gigantic coronal jet ejected from a compact active region in a coronal hole

    NASA Technical Reports Server (NTRS)

    Shibata, K.; Nitta, N.; Strong, K. T.; Matsumoto, R.; Yokoyama, T.; Hirayama, T.; Hudson, H.; Ogawara, Y.

    1994-01-01

    A gigantic coronal jet greater than 3 x 10(exp 5) km long (nearly half the solar radius) has been found with the soft X-ray telescope (SXT) on board the solar X-ray satellite, Yohkoh. The jet was ejected on 1992 January 11 from an 'anemone-type' active region (AR) appearing in a coronal hole and is one of the largest coronal X-ray jets observed so far by SXT. This gigantic jet is the best observed example of many other smaller X-ray jets, because the spatial structures of both the jet and the AR located at its base are more easily resolved. The range of apparent translational velocities of the bulk of the jet was between 90 and 240 km s(exp -1), with the corresponding kinetic energy estimated to be of order of 10(exp 28) ergs. A detailed analysis reveals that the jet was associated with a loop brightening (a small flare) that occurred in the active region. Several features of this observation suggest and are consistent with a magnetic reconnection mechanism for the production of such a 'jet-loop-brightening' event.

  6. Implications of an avian-style respiratory system for gigantism in sauropod dinosaurs.

    PubMed

    Perry, Steven F; Christian, Andreas; Breuer, Thomas; Pajor, Nadine; Codd, Jonathan R

    2009-10-01

    In light of evidence for avian-like lungs in saurischian dinosaurs, the physiological implications of cross-current gas exchange and voluminous, highly heterogeneous lungs for sauropod gigantism are critically examined. At 12 ton the predicted body temperature and metabolic rate of a growing sauropod would be similar to that of a bird scaled to the same body weight, but would increase exponentially as body mass increases. Although avian-like lung structure would be consistent with either a tachymetabolic-endothermic or a bradymetabolic-gigantothermic model, increasing body temperature requires adjustments to avoid overheating. We suggest that a unique sauropod structure/function unit facilitated the evolution of gigantism. This unit consisted of (1) a reduction in metabolic rate below that predicted by the body temperature, akin to thermal adaptation as seen in extant squamates, (2) presence of air-filled diverticula in the long neck and in the visceral cavity, and (3) low activity of respiratory muscles coupled with the high efficiency of cross-current gas exchange.

  7. Are sick individuals weak competitors? Competitive ability of snails parasitized by a gigantism-inducing trematode.

    PubMed

    Seppälä, Otto; Karvonen, Anssi; Kuosa, Marja; Haataja, Maarit; Jokela, Jukka

    2013-01-01

    Parasitized individuals are often expected to be poor competitors because they are weakened by infections. Many trematode species, however, although extensively exploiting their mollusc hosts, also induce gigantism (increased host size) by diverting host resources towards growth instead of reproduction. In such systems, alternatively to reduced competitive ability due to negative effects of parasitism on host performance, larger size could allow more efficient resource acquisition and thus increase the relative competitive ability of host individuals. We addressed this hypothesis by testing the effect of a trematode parasite Diplostomum pseudospathaceum on the competitive ability of its snail host Lymnaea stagnalis. We experimentally examined the growth of snails kept in pairs in relation to their infection status and intensity of resource competition (i.e. food availability). We found that parasitized snails grew faster and their reproduction was reduced compared to unparasitized individuals indicating parasite-induced gigantism. However, growth of the snails was faster when competing with parasitized individuals compared to unparasitized snails indicating reduced competitive ability due to parasitism. The latter effect, however, was relatively weak suggesting that the effects of the parasite on snail physiology may partly override each other in determining competitive ability. PMID:24205383

  8. Pituitary gigantism presenting with depressive mood disorder and diabetic ketoacidosis in an Asian adolescent.

    PubMed

    Kuo, Sheng-Fong; Chuang, Wen-Yu; Ng, Sohching; Chen, Chih-Hung; Chang, Chen-Nen; Chou, Chi-Hsiang; Weng, Wei-Chieh; Yeh, Chih-Hua; Lin, Jen-Der

    2013-01-01

    Hyperglycemia is seldom described in young patients with pituitary gigantism. Here, we describe the case of a 17-year-old Taiwanese boy who developed depressive mood disorder and diabetic ketoacidosis (DKA) at the presentation of pituitary gigantism. The boy complained of lethargy and dysphoric mood in June 2008. He presented at the emergency department with epigastralgia and dyspnea in January 2009. Results of laboratory tests suggested type 1 diabetes mellitus with DKA. However, serum C-peptide level was normal on follow-up. Although he had no obvious features of acral enlargement, a high level of insulin-like growth factor 1 was detected, and a 75 g oral glucose suppression test showed no suppression of serum growth hormone levels. A pituitary macroadenoma was found on subsequent magnetic resonance imaging. The pituitary adenoma was surgically removed, followed by gamma-knife radiosurgery, and Sandostatin long-acting release treatment. He was then administered metformin, 500 mg twice daily, and to date, his serum glycohemoglobin has been <7%. PMID:23729615

  9. Are sick individuals weak competitors? Competitive ability of snails parasitized by a gigantism-inducing trematode.

    PubMed

    Seppälä, Otto; Karvonen, Anssi; Kuosa, Marja; Haataja, Maarit; Jokela, Jukka

    2013-01-01

    Parasitized individuals are often expected to be poor competitors because they are weakened by infections. Many trematode species, however, although extensively exploiting their mollusc hosts, also induce gigantism (increased host size) by diverting host resources towards growth instead of reproduction. In such systems, alternatively to reduced competitive ability due to negative effects of parasitism on host performance, larger size could allow more efficient resource acquisition and thus increase the relative competitive ability of host individuals. We addressed this hypothesis by testing the effect of a trematode parasite Diplostomum pseudospathaceum on the competitive ability of its snail host Lymnaea stagnalis. We experimentally examined the growth of snails kept in pairs in relation to their infection status and intensity of resource competition (i.e. food availability). We found that parasitized snails grew faster and their reproduction was reduced compared to unparasitized individuals indicating parasite-induced gigantism. However, growth of the snails was faster when competing with parasitized individuals compared to unparasitized snails indicating reduced competitive ability due to parasitism. The latter effect, however, was relatively weak suggesting that the effects of the parasite on snail physiology may partly override each other in determining competitive ability.

  10. GaAs-oxide interface states - Gigantic photoionization via Auger-like process

    NASA Technical Reports Server (NTRS)

    Lagowski, J.; Kazior, T. E.; Gatos, H. C.; Walukiewicz, W.; Siejka, J.

    1981-01-01

    Spectral and transient responses of photostimulated current in MOS structures were employed for the study of GaAs-anodic oxide interface states. Discrete deep traps at 0.7 and 0.85 eV below the conduction band were found with concentrations of 5 x 10 to the 12th/sq cm and 7 x 10 to the 11th/sq cm, respectively. These traps coincide with interface states induced on clean GaAs surfaces by oxygen and/or metal adatoms (submonolayer coverage). In contrast to surfaces with low oxygen coverage, the GaAs-thick oxide interfaces exhibited a high density (about 10 to the 14th/sq cm) of shallow donors and acceptors. Photoexcitation of these donor-acceptor pairs led to a gigantic photoionization of deep interface states with rates 1000 times greater than direct transitions into the conduction band. The gigantic photoionization is explained on the basis of energy transfer from excited donor-acceptor pairs to deep states.

  11. [Long-term treatment of acromegaly and gigantism with octreotide (SMS 201-995)].

    PubMed

    Shimatsu, A; Imura, H; Irie, M; Nakagawa, S; Goto, Y; Shimizu, N; Takeda, R; Kato, Y; Saito, S; Ibayashi, H

    1992-02-20

    Twenty-one patients with active acromegaly and two patients with pituitary gigantism were treated with the long-acting somatostatin analogue octreotide (100-600 micrograms/day, sc, two or three times daily or 300-1500 micrograms daily by intermittent sc infusion) for 9-63 months. There was rapid clinical improvement. The fasting plasma GH levels were significantly suppressed (less than 50% of the values before treatment) in 17 patients and were normalized (less than 5 ng/ml) in 6 patients (27.3%). Plasma IGF-I levels were lowered by 50% and were normalized in 7 out of 18 cases. The effect of octreotide on pituitary tumor size was evaluated in 13 patients. In 4 cases, the shrinkage of the pituitary tumor was detected by computed tomographic scans and/or magnetic resonance imaging studies. The drug was generally well tolerated. However, there were probably newly formed gallstones in two patients during the therapy. Our study suggests that octreotide is an effective and relatively safe new approach for treating active acromegaly and gigantism. PMID:1592144

  12. Pituitary gigantism presenting with depressive mood disorder and diabetic ketoacidosis in an Asian adolescent.

    PubMed

    Kuo, Sheng-Fong; Chuang, Wen-Yu; Ng, Sohching; Chen, Chih-Hung; Chang, Chen-Nen; Chou, Chi-Hsiang; Weng, Wei-Chieh; Yeh, Chih-Hua; Lin, Jen-Der

    2013-01-01

    Hyperglycemia is seldom described in young patients with pituitary gigantism. Here, we describe the case of a 17-year-old Taiwanese boy who developed depressive mood disorder and diabetic ketoacidosis (DKA) at the presentation of pituitary gigantism. The boy complained of lethargy and dysphoric mood in June 2008. He presented at the emergency department with epigastralgia and dyspnea in January 2009. Results of laboratory tests suggested type 1 diabetes mellitus with DKA. However, serum C-peptide level was normal on follow-up. Although he had no obvious features of acral enlargement, a high level of insulin-like growth factor 1 was detected, and a 75 g oral glucose suppression test showed no suppression of serum growth hormone levels. A pituitary macroadenoma was found on subsequent magnetic resonance imaging. The pituitary adenoma was surgically removed, followed by gamma-knife radiosurgery, and Sandostatin long-acting release treatment. He was then administered metformin, 500 mg twice daily, and to date, his serum glycohemoglobin has been <7%.

  13. Assessing the potential of the European Atlantic sturgeon Acipenser sturio to control bivalve invasions in Europe.

    PubMed

    Ferreira-Rodriguez, N; Gessner, J; Pardo, I

    2016-08-01

    This pilot study explored the potential of juvenile European Atlantic sturgeon Acipenser sturio to feed on two invasive bivalve species, the Asian clam Corbicula fluminea and the Eurasian zebra mussel Dreissena polymorpha. Preliminary results indicate that native A. sturio were feeding on D. polymorpha at a very limited rate and their potential to prevent the establishment of invasive bivalve species, in new and previously invaded areas, is considered limited. PMID:27238016

  14. The isotopic biosignatures of photo- vs. thiotrophic bivalves: are they preserved in fossil shells?

    PubMed

    Dreier, A; Loh, W; Blumenberg, M; Thiel, V; Hause-Reitner, D; Hoppert, M

    2014-09-01

    Symbiont-bearing and non-symbiotic marine bivalves were used as model organisms to establish biosignatures for the detection of distinctive symbioses in ancient bivalves. For this purpose, the isotopic composition of lipids (δ13C) and bulk organic shell matrix (δ13C, δ34S, δ15N) from shells of several thiotrophic, phototrophic, or non-symbiotic bivalves were compared (phototrophic: Fragum fragum, Fragum unedo, Tridacna maxima; thiotrophic: Codakia tigerina, Fimbria fimbriata, Anodontia sp.; non-symbiotic: Tapes dorsatus, Vasticardium vertebratum, Scutarcopagia sp.). ∆13C values of bulk organic shell matrices, most likely representing mainly original shell protein/chitin biomass, were depleted in thio- and phototrophic bivalves compared to non-symbiotic bivalves. As the bulk organic shell matrix also showed a major depletion of δ15N (down to -2.2 ‰) for thiotrophic bivalves, combined δ13C and δ15N values are useful to differentiate between thio-, phototrophic, and non-symbiotic lifestyles. However, the use of these isotopic signatures for the study of ancient bivalves is limited by the preservation of the bulk organic shell matrix in fossils. Substantial alteration was clearly shown by detailed microscopic analyses of fossil (late Pleistocene) T. maxima and Trachycardium lacunosum shell, demonstrating a severe loss of quantity and quality of bulk organic shell matrix with time. Likewise, the composition and δ13C-values of lipids from empty shells indicated that a large part of these compounds derived from prokaryotic decomposers. The use of lipids from ancient shells for the reconstruction of the bivalve's life style therefore appears to be restricted.

  15. Assessing the potential of the European Atlantic sturgeon Acipenser sturio to control bivalve invasions in Europe.

    PubMed

    Ferreira-Rodriguez, N; Gessner, J; Pardo, I

    2016-08-01

    This pilot study explored the potential of juvenile European Atlantic sturgeon Acipenser sturio to feed on two invasive bivalve species, the Asian clam Corbicula fluminea and the Eurasian zebra mussel Dreissena polymorpha. Preliminary results indicate that native A. sturio were feeding on D. polymorpha at a very limited rate and their potential to prevent the establishment of invasive bivalve species, in new and previously invaded areas, is considered limited.

  16. Influence of intertidal recreational fisheries and 'bouchot' mussel culture on bivalve recruitment.

    PubMed

    Toupoint, Nicolas; Barbier, Pierrick; Tremblay, Réjean; Archambault, Philippe; McKindsey, Christopher W; Winkler, Gesche; Meziane, Tarik; Olivier, Frédéric

    2016-06-01

    In coastal environments, fishing and aquaculture may be important sources of disturbance to ecosystem functioning, the quantification of which must be assessed to make them more sustainable. In the Chausey Archipelago, France, recreational fishing and commercial shellfish farming are the only two evident anthropogenic activities, dominated by bivalve hand-raking and 'bouchot' mussel culture, respectively. This study evaluates the impact of both activities on bivalve recruitment dynamics by comparing primary recruitment intensity (short-term effect) and recruitment efficiency (medium-term effect) by sampling bivalves in reference (undisturbed) and disturbed (i.e. subjected to hand-raking or in 'bouchot' mussel culture areas) parcels throughout and at the end of the recruitment season, respectively. Specific hypotheses evaluated were that (H1) bivalve hand-raking negatively affects bivalve recruitment and that (H2) 'bouchot' mussel culture promotes bivalve recruitment. Patterns in bivalve community structure in reference parcels (i.e. natural pattern) differed between initial and final recruitment, underlining the great importance of early post-settlement processes, particularly secondary dispersal. Primary recruitment intensity was inhibited in hand-raking parcels whereas it was promoted in 'bouchot' mussel culture parcels, but the effect on recruitment efficiency was muted for both activities due to post-settlement processes. Nevertheless, the importance of effects that occur during the first step of recruitment should not be ignored as they may affect bivalve communities and induce immediate consequences on the trophic web through a cascade effect. Finally, it is highlighted that hand-raking damages all life stages of the common cockle Cerastoderma edule, one of the major target species, suggesting that this activity should be managed with greater caution than is currently done. PMID:27039134

  17. Influence of intertidal recreational fisheries and 'bouchot' mussel culture on bivalve recruitment.

    PubMed

    Toupoint, Nicolas; Barbier, Pierrick; Tremblay, Réjean; Archambault, Philippe; McKindsey, Christopher W; Winkler, Gesche; Meziane, Tarik; Olivier, Frédéric

    2016-06-01

    In coastal environments, fishing and aquaculture may be important sources of disturbance to ecosystem functioning, the quantification of which must be assessed to make them more sustainable. In the Chausey Archipelago, France, recreational fishing and commercial shellfish farming are the only two evident anthropogenic activities, dominated by bivalve hand-raking and 'bouchot' mussel culture, respectively. This study evaluates the impact of both activities on bivalve recruitment dynamics by comparing primary recruitment intensity (short-term effect) and recruitment efficiency (medium-term effect) by sampling bivalves in reference (undisturbed) and disturbed (i.e. subjected to hand-raking or in 'bouchot' mussel culture areas) parcels throughout and at the end of the recruitment season, respectively. Specific hypotheses evaluated were that (H1) bivalve hand-raking negatively affects bivalve recruitment and that (H2) 'bouchot' mussel culture promotes bivalve recruitment. Patterns in bivalve community structure in reference parcels (i.e. natural pattern) differed between initial and final recruitment, underlining the great importance of early post-settlement processes, particularly secondary dispersal. Primary recruitment intensity was inhibited in hand-raking parcels whereas it was promoted in 'bouchot' mussel culture parcels, but the effect on recruitment efficiency was muted for both activities due to post-settlement processes. Nevertheless, the importance of effects that occur during the first step of recruitment should not be ignored as they may affect bivalve communities and induce immediate consequences on the trophic web through a cascade effect. Finally, it is highlighted that hand-raking damages all life stages of the common cockle Cerastoderma edule, one of the major target species, suggesting that this activity should be managed with greater caution than is currently done.

  18. Microcystin accumulation in freshwater bivalves from Lake Taihu, China, and the potential risk to human consumption.

    PubMed

    Chen, Jun; Xie, Ping

    2007-05-01

    The potential risk through ingestion of microcystins (MC) in contaminated mollusks has not been well studied. The present paper studied seasonal changes of MC content (determined by liquid chromatography-mass spectrometry) in various organs of three species of bivalves (Cristaria plicata, Hyriopsis cumingii, and Lamprotula leai) in Lake Taihu, China, where toxic cyanobacterial blooms occurred. Coinciding with peaks of seston MC (maximum, 5.7 microg/L) and MC in cyanobacterial blooms (maximum, 0.534 mg/g), most organs showed sharp MC peaks during the summer, indicating both fast uptake and fast depuration by bivalves. Because hepatopancreas and intestine had considerably higher MC content than other organs, they are the most dangerous for human consumption. Both the present and previous studies show that the hepatopancreatic MC and total tissue MC often are correlated in various aquatic invertebrates. During the peak of the cyanobacterial blooms, C. plicata had higher hepatopancreatic MC content than the other bivalves, whereas H. cumingii had higher intestinal MC content than the other bivalves. Estimated daily intakes for humans from the consumption of whole tissues of the three bivalves were 0.48 to 0.94 microg MC-LR equivalent/kg body weight (12- to 23.5-fold the tolerable daily intake value proposed by the World Health Organization), which indicates a high risk for humans consuming these bivalves.

  19. Bivalve fouling of nuclear power plant service-water systems. Volume 1. Correlation of bivalve biological characteristics and raw-water system design

    SciTech Connect

    Neitzel, D.A.; Johnson, K.I.; Page, T.L.; Young, J.S.; Daling, P.M.

    1984-12-01

    Fouling of raw-water systems in nuclear power plants in the US can affect the safe operation of a power plant. This report describes correlations between the biology of bivalve organisms and the design and operation of power plants that allow bivalves to enter and reside in nuclear power plants. Discussions are focused on safety-related raw-water systems subject to fouling by the Asiatic clam (Corbicula fluminea), the blue mussel (Mytilus edulis), and the American oyster (Crassostrea virginica). Score sheets to rate fouling potential of power plant systems and components are provided.

  20. Strontium and barium incorporation into freshwater bivalve shells

    NASA Astrophysics Data System (ADS)

    Zhao, Liqiang; Schöne, Bernd R.

    2015-04-01

    Despite strong vital control, trace elements of bivalve shells can potentially serve as proxies of environmental change. However, to reconstruct past environments with the geochemical properties of the shells and determine the degree to which the element levels are biologically influenced, it is essential to experimentally determine the relationship between environmental variables and the element composition of the shells. In particular, the trace element geochemistry of freshwater bivalve shells has so far received little attention. Here, we present a controlled laboratory experiment that aimed at providing a better understanding of the influence of changing environmental variables on the incorporation of trace elements into freshwater bivalve shells. Under controlled conditions, Asian clams Corbicula fluminea were reared for 5 weeks in three sets of experiments: (1) different water temperature (10, 16, and 22° C) and different food levels (an equally mixed Scenedesmu quadricanda and Chlorella vulgaris at rations of 0.4, 2, 4, and 8 × 104 cells ml-1 d-1); (2) different water temperature (10, 16, and 22° C) and different element levels (Sr, Ba); (3) five sediment types (sand, slightly muddy sand, muddy sand, slightly sandy mud and mud). In the first set of experiments, shell Sr/Ca showed a significantly negative correlation with temperature, where Sr/Ca decreased linearly by about 1.6 to 2.1% per 1° C, but responded far more weakly to food availability. On the other hand, temperature and food availability affected shell Ba/Ca ratios, which potentially confounds the interpretation of Ba/Ca variations. Moreover, shell Sr/Ca and Ba/Ca exhibited a clearly negative dependence on shells growth rate that varied significantly among combinations of temperature and food availability. In the second set of experiments, shell Sr/Ca and Ba/Ca were positively and linearly related to water Sr/Ca and Ba/Ca for all temperatures. However, significantly negative effects of

  1. Anoxic survival potential of bivalves: (arte)facts.

    PubMed

    de Zwaan, Albertus; Babarro, Jose M F; Monari, Marta; Cattani, Otello

    2002-03-01

    The anoxic survival time of the bivalves Chamelea gallina, Cerastoderma edule and Scapharca inaequivalvis from two different ecosystems and differing anoxia tolerances was studied in static (closed) and flow-through systems. The antibiotics chloramphenicol, penicillin and polymyxin were added, and molybdate (specific inhibitor of the process of sulfate reduction). Survival in (near) anoxic seawater of Chamelea was studied in a static system by comparing untreated seawater with autoclaved seawater and untreated clams with clams incubated in well-aerated seawater, containing the broad-spectrum antibiotic chloramphenicol, prior to the anoxic survival test. With untreated clams and natural seawater (median mortality time 2.4 days) a decrease in pH and exponential accumulation of sulfide and ammonium was observed in the anoxic medium, indicating excessive growth of (sulfate reducing) bacteria. In sterilized seawater LT50 (2.1 days) was not significantly different and again considerable amounts of ammonium and sulfide accumulated. However, pre-treatment of clams with chloramphenicol resulted in an increase of LT50 (11.0 days) by approximately fivefold. Accumulation of ammonium and sulfide was retarded, but was finally even stronger than in the medium containing untreated clams. Median mortality times were 2.5 and 2.4 days for Chamelea and 2.7 and 2.9 days for Cerastoderma for static and flow-through incubations, respectively. Addition of chloramphenicol increased strongly survival time in both systems with corresponding values of 11.0 and 16.3 days for Chamelea, and 6.4 and 6.5 days for Cerastoderma. LT50 of Scapharca in anoxic seawater was 14.4 days. Chloramphenicol and penicillin increased median survival time to 28.5 and 28.7 days, respectively, whereas polymyxin displayed no effect (LT50=13.6 days). Molybdate added to artificial sulfate free seawater blocked biotic sulfide formation, but did not improve survival time (LT50=13.7 days). Overall the results indicate

  2. Anoxic survival potential of bivalves: (arte)facts.

    PubMed

    de Zwaan, Albertus; Babarro, Jose M F; Monari, Marta; Cattani, Otello

    2002-03-01

    The anoxic survival time of the bivalves Chamelea gallina, Cerastoderma edule and Scapharca inaequivalvis from two different ecosystems and differing anoxia tolerances was studied in static (closed) and flow-through systems. The antibiotics chloramphenicol, penicillin and polymyxin were added, and molybdate (specific inhibitor of the process of sulfate reduction). Survival in (near) anoxic seawater of Chamelea was studied in a static system by comparing untreated seawater with autoclaved seawater and untreated clams with clams incubated in well-aerated seawater, containing the broad-spectrum antibiotic chloramphenicol, prior to the anoxic survival test. With untreated clams and natural seawater (median mortality time 2.4 days) a decrease in pH and exponential accumulation of sulfide and ammonium was observed in the anoxic medium, indicating excessive growth of (sulfate reducing) bacteria. In sterilized seawater LT50 (2.1 days) was not significantly different and again considerable amounts of ammonium and sulfide accumulated. However, pre-treatment of clams with chloramphenicol resulted in an increase of LT50 (11.0 days) by approximately fivefold. Accumulation of ammonium and sulfide was retarded, but was finally even stronger than in the medium containing untreated clams. Median mortality times were 2.5 and 2.4 days for Chamelea and 2.7 and 2.9 days for Cerastoderma for static and flow-through incubations, respectively. Addition of chloramphenicol increased strongly survival time in both systems with corresponding values of 11.0 and 16.3 days for Chamelea, and 6.4 and 6.5 days for Cerastoderma. LT50 of Scapharca in anoxic seawater was 14.4 days. Chloramphenicol and penicillin increased median survival time to 28.5 and 28.7 days, respectively, whereas polymyxin displayed no effect (LT50=13.6 days). Molybdate added to artificial sulfate free seawater blocked biotic sulfide formation, but did not improve survival time (LT50=13.7 days). Overall the results indicate

  3. Trace Element Uptake in Marine Bivalve Shells Constraints from Field- and Laboratory Studies

    NASA Astrophysics Data System (ADS)

    Klünder, M.; Hippler, D.; Witbaard, R.; Frei, D.; Immenhauser, A.

    2006-12-01

    There is an increasing interest in the use of the trace element signatures recorded in calcium carbonate skeletons of marine organisms as archives of past and present environmental conditions, such as temperature, salinity or nutrition level. Because of their global occurrence in the modern and ancient oceans, the trace element chemistry of bivalve shells might be used as a potential proxy for present and past environmental conditions. If the composition of bivalve shells, for instance, can be shown to represent the environment in which they lived, then shells can be used to investigate conditions in the lifetime of the animal. And as the shell material is sequentially deposited, an understanding of the internal shell structure will enable time- resolution of the analyses. Therefore, the trace element signature of bivalve shells may provide an important record of climate changes and global geochemical cycles. One of the difficulties of using the trace element signatures of bivalve shells as proxies for environmental conditions is that little is known about the mechanisms by which the trace elements are incorporated into the shells. There has been quite an amount of research into the use of bivalve shell chemistry as proxy for one or more environmental parameters, but there are relatively few datasets in which both bivalve shells and the water in which the animals lived have been analysed. It is as yet not clear to what extent the trace element incorporation into bivalve shells is governed by biological processes, like growth rate and metabolism of the animals, or by physical and crystal chemical parameters. An added difficulty is that the existing data do suggest that trace element uptake in bivalve shells may be species specific. Therefore, studies that investigate the relationships between the content of these elements in the shells and the ambient water and the possible incorporation mechanisms are needed if the potential that bivalve shells offer as

  4. Familial gigantism.

    PubMed

    Herder, Wouter W de

    2012-01-01

    Familial GH-secreting tumors are seen in association with three separate hereditary clinical syndromes: multiple endocrine neoplasia type 1, Carney complex, and familial isolated pituitary adenomas. PMID:22584702

  5. Different carbon sources affect PCB accumulation by marine bivalves.

    PubMed

    Laitano, M V; Silva Barni, M F; Costa, P G; Cledón, M; Fillmann, G; Miglioranza, K S B; Panarello, H O

    2016-02-01

    Pampean creeks were evaluated in the present study as potential land-based sources of PCB marine contamination. Different carbon and nitrogen sources from such creeks were analysed as boosters of PCB bioaccumulation by the filter feeder bivalve Brachidontes rodriguezii and grazer limpet Siphonaria lessoni. Carbon of different source than marine and anthropogenic nitrogen assimilated by organisms were estimated through their C and N isotopic composition. PCB concentration in surface sediments and mollusc samples ranged from 2.68 to 6.46 ng g(-1) (wet weight) and from 1074 to 4583 ng g(-1) lipid, respectively, reflecting a punctual source of PCB contamination related to a landfill area. Thus, despite the low flow of creeks, they should not be underestimated as contamination vectors to the marine environment. On the other hand, mussels PCB bioaccumulation was related with the carbon source uptake which highlights the importance to consider this factor when studying PCB distribution in organisms of coastal systems.

  6. Different carbon sources affect PCB accumulation by marine bivalves.

    PubMed

    Laitano, M V; Silva Barni, M F; Costa, P G; Cledón, M; Fillmann, G; Miglioranza, K S B; Panarello, H O

    2016-02-01

    Pampean creeks were evaluated in the present study as potential land-based sources of PCB marine contamination. Different carbon and nitrogen sources from such creeks were analysed as boosters of PCB bioaccumulation by the filter feeder bivalve Brachidontes rodriguezii and grazer limpet Siphonaria lessoni. Carbon of different source than marine and anthropogenic nitrogen assimilated by organisms were estimated through their C and N isotopic composition. PCB concentration in surface sediments and mollusc samples ranged from 2.68 to 6.46 ng g(-1) (wet weight) and from 1074 to 4583 ng g(-1) lipid, respectively, reflecting a punctual source of PCB contamination related to a landfill area. Thus, despite the low flow of creeks, they should not be underestimated as contamination vectors to the marine environment. On the other hand, mussels PCB bioaccumulation was related with the carbon source uptake which highlights the importance to consider this factor when studying PCB distribution in organisms of coastal systems. PMID:26606107

  7. Permian nonmarine bivalve zonation of the East European platform

    NASA Astrophysics Data System (ADS)

    Silantiev, V. V.

    2014-01-01

    New finds and revision of available collections of nonmarine bivalves provided grounds for development of a zonal scale for terrestrial sequences of the Permian System based on species belonging to the genus Palaeomutela Amalitzky, 1891, which are characterized by regular changes in the structure of the shell hinge. The scale includes two parallel zonal successions that are based on the stratigraphic distribution and evolutionary trends of two morphological lineages of the genus. The zonal succession based on development of the P. umbonata group (dwellers of mobile waters and silty-psammitic substrates) includes 11 range zones: stegocephalum, ovatiformis, umbonata, quadriangularis, krotowi, wohrmani, numerosa, ulemensis, keyserlingi, curiosa, golubevi. The zonal succession based on development of the P. castor group (dwellers of calm waters and silty-pelitic substrates) includes eight range zones: larae, castor, olgae, doratioformis, marposadica, fischeri, obunca, amalitzkyi. The proposed zonal units are correlated with scales based on ostracod, fish, and tetrapod fossils. New species Palaeomutela golubevi sp. nov. and P. amalitzkyi sp. nov. are described with the extended diagnosis of the genus Palaeomutela.

  8. Giant bivalves (Tridacna gigas) as recorders of ENSO variability

    NASA Astrophysics Data System (ADS)

    Welsh, Kevin; Elliot, Mary; Tudhope, Alexander; Ayling, Bridget; Chappell, John

    2011-07-01

    We compare monthly resolved oxygen isotope records derived from a giant bivalve shell, Tridacna gigas and massive Porites corals collected along the northern coast of Papua New Guinea. This intercomparison study demonstrates that δ 18O profiles obtained from these different aragonite-secreting organisms collected from within a 30 km range are correlated in great detail and record the timing and amplitude of seasonal and interannual (ENSO-related) variations in sea surface temperature (SST) and water isotopic composition which is closely related to rainfall. Furthermore, the T. gigas record is shown to be close to isotopic equilibrium with the local sea-water, in contrast to the corals which are approximately - 4‰ offset. These results reveal that living and fossil T. gigas clam shells have the potential to yield reliable records of past changes in seasonality and ENSO variability, as well as mean climate conditions. In particular, since the non-porous shells are generally more resistant to diagenesis than coral skeletons, they may provide robust estimates of past tropical climate for periods and locations where unaltered corals are absent.

  9. Changing restoration rules: exotic bivalves interact with residence time and depth to control phytoplankton productivity

    USGS Publications Warehouse

    Lucas, Lisa V.; Thompson, Janet K.

    2012-01-01

    Non-native species are a prevalent ecosystem stressor that can interact with other stressors to confound resource management and restoration. We examine how interactions between physical habitat attributes and a particular category of non-native species (invasive bivalves) influence primary production in aquatic ecosystems. Using mathematical models, we show how intuitive relationships between phytoplankton productivity and controllable physical factors (water depth, hydraulic transport time) that hold in the absence of bivalves can be complicated—and even reversed—by rapid bivalve grazing. In light-limited environments without bivalves, shallow, hydrodynamically “slow” habitats should generally have greater phytoplankton biomass and productivity than deeper, “faster” habitats. But shallower, slower environments can be less productive than deeper, faster ones if benthic grazing is strong. Moreover, shallower and slower waters exhibit a particularly broad range of possible productivity outcomes that can depend on whether bivalves are present. Since it is difficult to predict the response of non-native bivalves to habitat restoration, outcomes for new shallow, slow environments can be highly uncertain. Habitat depth and transport time should therefore not be used as indicators of phytoplankton biomass and production where bivalve colonization is possible. This study provides for ecosystem management a particular example of a broad lesson: abiotic ecosystem stressors should be managed with explicit consideration of interactions with other major (including biotic) stressors. We discuss the applicability and management implications of our models and results for a range of aquatic system types, with a case study focused on the Sacramento-San Joaquin Delta (California, USA). Simple mathematical models like those used here can illuminate interactions between ecosystem stressors and provide process-based guidance for resource managers as they develop strategies

  10. Determining provenance of marine metal pollution in French bivalves using Cd, Zn and Pb isotopes

    NASA Astrophysics Data System (ADS)

    Shiel, Alyssa E.; Weis, Dominique; Cossa, Daniel; Orians, Kristin J.

    2013-11-01

    Cadmium, Zn and Pb isotopic compositions (MC-ICP-MS) and elemental concentrations (HR-ICP-MS) have been used to distinguish between natural and anthropogenic sources of these metals in bivalves collected from the coastlines of France (English Channel, Atlantic and Mediterranean coasts). The Cd isotopic signatures (δ114Cd = -1.08‰ to -0.52‰) exhibited by bivalves from the coastlines of France, excluding those from NE France, are within the range of those exhibited by bivalves from the USA East coast (δ114Cd = -1.20‰ to -0.54‰). This indicates the high prevalence of industry, as well as the low natural contributions of Cd from North Atlantic waters in both regions. Thus, the significance of anthropogenic Cd sources is similar. These significant anthropogenic contributions are identified for bivalves with a large range in tissue Cd concentrations. Importantly, French bivalves from the Gironde estuary and Marennes-Oléron basin (regions of historic and modern importance for oyster farming, respectively) exhibited the highest Cd levels of the study. Their Cd isotopic signatures indicate historical smelting emissions remain the primary Cd source despite the cessation of local smelting activities in 1986 and subsequent remedial efforts. No significant variability is observed in the δ66Zn values of the French bivalves (∼0.53‰), with the exception of the much heavier compositions exhibited by oysters from the polluted Gironde estuary (1.19-1.27‰). Lead isotopes do not fractionate during processing like Cd and Zn. They can, therefore, be used to identify emissions from industrial processes and the consumption of unleaded gasoline and diesel fuel as metal sources to French bivalves. Cadmium and Zn isotopes are successfully used here as tracers of anthropogenic processing emissions and are combined with Pb isotope "fingerprinting" techniques to identify metal sources.

  11. First evidence of immunomodulation in bivalves under seawater acidification and increased temperature.

    PubMed

    Matozzo, Valerio; Chinellato, Andrea; Munari, Marco; Finos, Livio; Bressan, Monica; Marin, Maria Gabriella

    2012-01-01

    Water acidification, temperature increases and changes in seawater salinity are predicted to occur in the near future. In such a global climate change (GCC) scenario, there is growing concern for the health status of both wild and farmed organisms. Bivalve molluscs, an important component of coastal marine ecosystems, are at risk. At the immunological level, the ability of an organism to maintain its immunosurveillance unaltered under adverse environmental conditions may enhance its survival capability. To our knowledge, only a few studies have investigated the effects of changing environmental parameters (as predicted in a GCC scenario) on the immune responses of bivalves. In the present study, the effects of both decreased pH values and increased temperature on the important immune parameters of two bivalve species were evaluated for the first time. The clam Chamelea gallina and the mussel Mytilus galloprovincialis, widespread along the coast of the Northwestern Adriatic Sea, were chosen as model organisms. Bivalves were exposed for 7 days to three pH values (8.1, 7.7 and 7.4) at two temperatures (22 and 28°C). Three independent experiments were carried out at salinities of 28, 34 and 40 PSU. The total haemocyte count, Neutral Red uptake, haemolymph lysozyme activity and total protein levels were measured. The results obtained demonstrated that tested experimental conditions affected significantly most of the immune parameters measured in bivalves, even if the variation pattern of haemocyte responses was not always linear. Between the two species, C. gallina appeared more vulnerable to changing pH and temperature than M. galloprovincialis. Overall, this study demonstrated that climate changes can strongly affect haemocyte functionality in bivalves. However, further studies are needed to clarify better the mechanisms of action of changing environmental parameters, both individually and in combination, on bivalve haemocytes.

  12. A gigantic, exceptionally complete titanosaurian sauropod dinosaur from southern Patagonia, Argentina.

    PubMed

    Lacovara, Kenneth J; Lamanna, Matthew C; Ibiricu, Lucio M; Poole, Jason C; Schroeter, Elena R; Ullmann, Paul V; Voegele, Kristyn K; Boles, Zachary M; Carter, Aja M; Fowler, Emma K; Egerton, Victoria M; Moyer, Alison E; Coughenour, Christopher L; Schein, Jason P; Harris, Jerald D; Martínez, Rubén D; Novas, Fernando E

    2014-01-01

    Titanosaurian sauropod dinosaurs were the most diverse and abundant large-bodied herbivores in the southern continents during the final 30 million years of the Mesozoic Era. Several titanosaur species are regarded as the most massive land-living animals yet discovered; nevertheless, nearly all of these giant titanosaurs are known only from very incomplete fossils, hindering a detailed understanding of their anatomy. Here we describe a new and gigantic titanosaur, Dreadnoughtus schrani, from Upper Cretaceous sediments in southern Patagonia, Argentina. Represented by approximately 70% of the postcranial skeleton, plus craniodental remains, Dreadnoughtus is the most complete giant titanosaur yet discovered, and provides new insight into the morphology and evolutionary history of these colossal animals. Furthermore, despite its estimated mass of about 59.3 metric tons, the bone histology of the Dreadnoughtus type specimen reveals that this individual was still growing at the time of death. PMID:25186586

  13. Molecular design of TiO2 for gigantic red shift via sublattice substitution.

    PubMed

    Shao, Guosheng; Deng, Quanrong; Wan, Lin; Guo, Meilan; Xia, Xiaohong; Gao, Yun

    2010-11-01

    The effects of 3d transition metal doping in TiO2 phases have been simulated in detail. The results of modelling indicate that Mn has the biggest potential among 3d transition metals, for the reduction of energy gap and the introduction of effective intermediate bands to allow multi-band optical absorption. On the basis of theoretical formulation, we have incorporated considerable amount of Mn in nano-crystalline TiO2 materials. Mn doped samples demonstrate significant red shift in the optical absorption edge, with a secondary absorption edge corresponding to theoretically predicted intermediate bands/states. The gigantic red shift achievable in Mn-doped TiO2 is expected to extend the useful TiO2 functionalities well beyond the UV threshold via the optical absorption of both visible and infrared photon irradiance.

  14. Giants among larges: how gigantism impacts giant virus entry into amoebae.

    PubMed

    Rodrigues, Rodrigo Araújo Lima; Abrahão, Jônatas Santos; Drumond, Betânia Paiva; Kroon, Erna Geessien

    2016-06-01

    The proposed order Megavirales comprises the nucleocytoplasmic large DNA viruses (NCLDV), infecting a wide range of hosts. Over time, they co-evolved with different host cells, developing various strategies to penetrate them. Mimiviruses and other giant viruses enter cells through phagocytosis, while Marseillevirus and other large viruses explore endocytosis and macropinocytosis. These differing strategies might reflect the evolution of those viruses. Various scenarios have been proposed for the origin and evolution of these viruses, presenting one of the most enigmatic issues to surround these microorganisms. In this context, we believe that giant viruses evolved independently by massive gene/size gain, exploring the phagocytic pathway of entry into amoebas. In response to gigantism, hosts developed mechanisms to evade these parasites. PMID:27039270

  15. A gigantic, exceptionally complete titanosaurian sauropod dinosaur from southern Patagonia, Argentina.

    PubMed

    Lacovara, Kenneth J; Lamanna, Matthew C; Ibiricu, Lucio M; Poole, Jason C; Schroeter, Elena R; Ullmann, Paul V; Voegele, Kristyn K; Boles, Zachary M; Carter, Aja M; Fowler, Emma K; Egerton, Victoria M; Moyer, Alison E; Coughenour, Christopher L; Schein, Jason P; Harris, Jerald D; Martínez, Rubén D; Novas, Fernando E

    2014-09-04

    Titanosaurian sauropod dinosaurs were the most diverse and abundant large-bodied herbivores in the southern continents during the final 30 million years of the Mesozoic Era. Several titanosaur species are regarded as the most massive land-living animals yet discovered; nevertheless, nearly all of these giant titanosaurs are known only from very incomplete fossils, hindering a detailed understanding of their anatomy. Here we describe a new and gigantic titanosaur, Dreadnoughtus schrani, from Upper Cretaceous sediments in southern Patagonia, Argentina. Represented by approximately 70% of the postcranial skeleton, plus craniodental remains, Dreadnoughtus is the most complete giant titanosaur yet discovered, and provides new insight into the morphology and evolutionary history of these colossal animals. Furthermore, despite its estimated mass of about 59.3 metric tons, the bone histology of the Dreadnoughtus type specimen reveals that this individual was still growing at the time of death.

  16. Early descriptions of acromegaly and gigantism and their historical evolution as clinical entities.

    PubMed

    Mammis, Antonios; Eloy, Jean Anderson; Liu, James K

    2010-10-01

    Giants have been a subject of fascination throughout history. Whereas descriptions of giants have existed in the lay literature for millennia, the first attempt at a medical description was published by Johannes Wier in 1567. However, it was Pierre Marie, in 1886, who established the term "acromegaly" for the first time and established a distinct clinical diagnosis with clear clinical descriptions in 2 patients with the characteristic presentation. Multiple autopsy findings revealed a consistent correlation between acromegaly and pituitary enlargement. In 1909, Harvey Cushing postulated a “hormone of growth" as the underlying pathophysiological trigger involved in pituitary hypersecretion in patients with acromegaly. This theory was supported by his observations of clinical remission in patients with acromegaly in whom he had performed hypophysectomy. In this paper, the authors present some of the early accounts of acromegaly and gigantism, and describe its historical evolution as a medical and surgical entity. PMID:20887119

  17. Intraspecific competition and high food availability are associated with insular gigantism in a lizard

    NASA Astrophysics Data System (ADS)

    Pafilis, Panayiotis; Meiri, Shai; Foufopoulos, Johannes; Valakos, Efstratios

    2009-09-01

    Resource availability, competition, and predation commonly drive body size evolution. We assess the impact of high food availability and the consequent increased intraspecific competition, as expressed by tail injuries and cannibalism, on body size in Skyros wall lizards ( Podarcis gaigeae). Lizard populations on islets surrounding Skyros (Aegean Sea) all have fewer predators and competitors than on Skyros but differ in the numbers of nesting seabirds. We predicted the following: (1) the presence of breeding seabirds (providing nutrients) will increase lizard population densities; (2) dense lizard populations will experience stronger intraspecific competition; and (3) such aggression, will be associated with larger average body size. We found a positive correlation between seabird and lizard densities. Cannibalism and tail injuries were considerably higher in dense populations. Increases in cannibalism and tail loss were associated with large body sizes. Adult cannibalism on juveniles may select for rapid growth, fuelled by high food abundance, setting thus the stage for the evolution of gigantism.

  18. Early descriptions of acromegaly and gigantism and their historical evolution as clinical entities.

    PubMed

    Mammis, Antonios; Eloy, Jean Anderson; Liu, James K

    2010-10-01

    Giants have been a subject of fascination throughout history. Whereas descriptions of giants have existed in the lay literature for millennia, the first attempt at a medical description was published by Johannes Wier in 1567. However, it was Pierre Marie, in 1886, who established the term "acromegaly" for the first time and established a distinct clinical diagnosis with clear clinical descriptions in 2 patients with the characteristic presentation. Multiple autopsy findings revealed a consistent correlation between acromegaly and pituitary enlargement. In 1909, Harvey Cushing postulated a “hormone of growth" as the underlying pathophysiological trigger involved in pituitary hypersecretion in patients with acromegaly. This theory was supported by his observations of clinical remission in patients with acromegaly in whom he had performed hypophysectomy. In this paper, the authors present some of the early accounts of acromegaly and gigantism, and describe its historical evolution as a medical and surgical entity.

  19. Pituitary tumor with gigantism, acromegaly and preclinical Cushing's disease diagnosed from the 10th row.

    PubMed

    Tourtelot, John B; Vesely, David L

    2013-08-01

    A 7'3" basketball player was noted to have 2 to 3 times thicker tissue in his hands than 6'10" players by an endocrinologist sitting 10 rows above the player in a basketball arena. This led to the diagnosis of pituitary gigantism where the history revealed that he was 7'3" at 15 years of age. At age 19 when the acryl enlargement was noted, a diagnostic workup revealed elevated growth hormones and insulin-like growth factor 1 (IGF-1) with a 2 × 1.3 cm pituitary tumor. His history suggested that his epiphyseal plates had closed at age 15, and because he continued to produce IGF-1, he now has acromegaly. His elevated adrenocorticotropic hormone (ACTH) before surgery suggests that he also had preclinical Cushing's disease. After pituitary transsphenoidal surgery, all acryl enlargement in hands and ligaments disappeared. His growth hormone, IGF-1 and ACTH returned to normal 2 weeks after surgery. PMID:23462247

  20. Gigantic directional asymmetry of luminescence in multiferroic CuB 2O 4

    NASA Astrophysics Data System (ADS)

    Toyoda, S.; Abe, N.; Arima, T.

    2016-05-01

    In multiferroic materials, luminescence intensities can be direction dependent, i.e., different between the opposite propagating directions of emitted light. However, the effect has not been thought to be used for technological applications, since only small directional asymmetry has been reported so far. Here we show that the effect is robust in multiferroic CuB2O4 . The luminescence intensity changes by about 70 % between the opposite directions of the emission, which is about 100 times larger than the previously reported values. We demonstrate that such a gigantic directional asymmetry of luminescence can be applied to the imaging of canted antiferromagnetic domains. The observation of the effect and its application to magnetic domain imaging are important for a deeper understanding of light-matter interactions as well as technological applications such as optical reading techniques for magnetic memory devices.

  1. ecCNO solar neutrinos: A challenge for gigantic ultra-pure liquid scintillator detectors

    NASA Astrophysics Data System (ADS)

    Villante, F. L.

    2015-03-01

    Neutrinos produced in the Sun by electron capture reactions on 13N, 15O and 17F, to which we refer as ecCNO neutrinos, are not usually considered in solar neutrino analysis since the expected fluxes are extremely low. The experimental determination of this sub-dominant component of the solar neutrino flux is very difficult but could be rewarding since it provides a determination of the metallic content of the solar core and, moreover, probes the solar neutrino survival probability in the transition region at Eν ∼ 2.5 MeV. In this Letter, we suggest that this difficult measure could be at reach for future gigantic ultra-pure liquid scintillator detectors, such as LENA.

  2. Pituitary tumor with gigantism, acromegaly and preclinical Cushing's disease diagnosed from the 10th row.

    PubMed

    Tourtelot, John B; Vesely, David L

    2013-08-01

    A 7'3" basketball player was noted to have 2 to 3 times thicker tissue in his hands than 6'10" players by an endocrinologist sitting 10 rows above the player in a basketball arena. This led to the diagnosis of pituitary gigantism where the history revealed that he was 7'3" at 15 years of age. At age 19 when the acryl enlargement was noted, a diagnostic workup revealed elevated growth hormones and insulin-like growth factor 1 (IGF-1) with a 2 × 1.3 cm pituitary tumor. His history suggested that his epiphyseal plates had closed at age 15, and because he continued to produce IGF-1, he now has acromegaly. His elevated adrenocorticotropic hormone (ACTH) before surgery suggests that he also had preclinical Cushing's disease. After pituitary transsphenoidal surgery, all acryl enlargement in hands and ligaments disappeared. His growth hormone, IGF-1 and ACTH returned to normal 2 weeks after surgery.

  3. Giants among larges: how gigantism impacts giant virus entry into amoebae.

    PubMed

    Rodrigues, Rodrigo Araújo Lima; Abrahão, Jônatas Santos; Drumond, Betânia Paiva; Kroon, Erna Geessien

    2016-06-01

    The proposed order Megavirales comprises the nucleocytoplasmic large DNA viruses (NCLDV), infecting a wide range of hosts. Over time, they co-evolved with different host cells, developing various strategies to penetrate them. Mimiviruses and other giant viruses enter cells through phagocytosis, while Marseillevirus and other large viruses explore endocytosis and macropinocytosis. These differing strategies might reflect the evolution of those viruses. Various scenarios have been proposed for the origin and evolution of these viruses, presenting one of the most enigmatic issues to surround these microorganisms. In this context, we believe that giant viruses evolved independently by massive gene/size gain, exploring the phagocytic pathway of entry into amoebas. In response to gigantism, hosts developed mechanisms to evade these parasites.

  4. The Early ULF Signal of the Gigantic Jets Revealed By Hilbert-Huang Transform

    NASA Astrophysics Data System (ADS)

    Huang, Po-Hsun; Bing-Chih Chen, Alfred

    2015-04-01

    The conventional Fourier analysis on the sferics in ULF and VLF bandpasses has been done for years. Several phenomena e.g. whistler and Schumann resonance have been well studied by the Fourier spectrum comprehensively. But the Fourier analysis is computed by an integration over time, therefore, the temporal resolution is smoothed, and limited not only by the sampling rate but also the size of the integration window. The instantaneous frequency can't be obtained through this conventional approach. We introduce the Hilbert-Huang transform (HHT) instead of Fourier transform to analyze the sferics of TLEs recorded at Lulin observatory. The Hilbert-Huang transform decomposes a signal into so-called intrinsic mode functions (IMF), and derive instantaneous frequency data by differentiating the phase angle yielded by Hilbert transform. Our analysis of HHT on several gigantic jets recorded by ground observation surprisingly revealed an early signal of frequency-change during the phase of the leading jet, and this early signal can not be identified by Fourier analysis. In the phase of leading jet, the amplitude of the sferics remains a constant and no significant features are recognized in the recorded waveform, but an obvious frequency change about 100-200 millisecond prior to the main discharge of the full development jets (FDJs), which can be clearly recognized in the HHT spectra of all observed gigantic jets. From a further simulation, this frequency change is confirmed to come from the nature of the discharge, not an alias or a false signal generated by the analysis method. This early signal may implies an in-cloud discharge process which is suggested by Krehbiel et al. [2008

  5. Can Oxygen Set Thermal Limits in an Insect and Drive Gigantism?

    PubMed Central

    Verberk, Wilco C. E. P.; Bilton, David T.

    2011-01-01

    Background Thermal limits may arise through a mismatch between oxygen supply and demand in a range of animal taxa. Whilst this oxygen limitation hypothesis is supported by data from a range of marine fish and invertebrates, its generality remains contentious. In particular, it is unclear whether oxygen limitation determines thermal extremes in tracheated arthropods, where oxygen limitation may be unlikely due to the efficiency and plasticity of tracheal systems in supplying oxygen directly to metabolically active tissues. Although terrestrial taxa with open tracheal systems may not be prone to oxygen limitation, species may be affected during other life-history stages, particularly if these rely on diffusion into closed tracheal systems. Furthermore, a central role for oxygen limitation in insects is envisaged within a parallel line of research focussing on insect gigantism in the late Palaeozoic. Methodology/Principal Findings Here we examine thermal maxima in the aquatic life stages of an insect at normoxia, hypoxia (14 kPa) and hyperoxia (36 kPa). We demonstrate that upper thermal limits do indeed respond to external oxygen supply in the aquatic life stages of the stonefly Dinocras cephalotes, suggesting that the critical thermal limits of such aquatic larvae are set by oxygen limitation. This could result from impeded oxygen delivery, or limited oxygen regulatory capacity, both of which have implications for our understanding of the limits to insect body size and how these are influenced by atmospheric oxygen levels. Conclusions/Significance These findings extend the generality of the hypothesis of oxygen limitation of thermal tolerance, suggest that oxygen constraints on body size may be stronger in aquatic environments, and that oxygen toxicity may have actively selected for gigantism in the aquatic stages of Carboniferous arthropods. PMID:21818347

  6. Antimicrobial activities of two edible bivalves M. meretrix and M. casta.

    PubMed

    Sugesh, S; Mayavu, P

    2013-01-01

    The marine invertebrates become one of hot spot for the lead of antimicrobial compounds. Two species of commercially available and edible bivalves (M. meretrix and M. casta) were assayed for antimicrobial activity against 10 bacterial pathogens and 6 fungal pathogens and its biochemical composition. The bivalves were extracted with three different solvent systems respectively methanol, ethanol and acetic acid. All the three extracts of both the species M. meretrix and M. casta showed highest antibacterial activities against S. aureus, E. coli, B. substillus, K. pneumonia, P. fleuroscence and V. cholera. In present investigation the methanolic extract of the two bivalve species of M. meretrix and M. casta was showed inhibition activities against all pathogenic fungal forms. The two bivalve extracts showed high amounts of protein content, which made the variation up to 160-180 microg mg(-1) (wet weight). Both samples had low amount of carbohydrates 4.77-5.77 microg mg(-1) and lipids 0.11-0.17 microg mg(-1), respectively. The results of thin layer chromatography were revealed that presence of pink color spots it clearly indicates the presence of amino acid or peptides in bivalve's samples. Presuming that the antimicrobial compounds were proteins or peptides. In SDS-PAGE on 12% gel, the crude proteins M. meretrix and M. casta showed 5-6 bands ranging from 45-223 kDa. They represent potential pharmacological leads perhaps possessing novel and uncharacterized mechanisms of action that might ultimately benefit the ongoing global search for clinically useful antimicrobial agents.

  7. Dioxins/furans and PCBs in bivalves and sediments from NOAA national status and trends program

    SciTech Connect

    Wade, T.; Gardinali, P.; Jackson, T.; Sericano, J.; Chambers, L.

    1995-12-31

    As part of the National Oceanic and Atmospheric Administration (NOAA), National Status and Trends (NS and T) Mussel Watch Program 55 bivalves and 7 sediment samples were analyzed for 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD and PCDF) and planar PCBs. Bivalve samples were collected from selected US East Gulf and West coast sites, while the sediment samples were all from the Gulf coast. Sediment concentrations for 2,3,7,8-tetrachloro dibenzo-p-dioxin and dibenzofuran (TCDD and TCDF) ranged from 0.35 to 25 pg/g and 0.42 to 140 pg/g, respectively. The 2,3,7,8-TCDD and 2,3,7,8-TCDF represent only a small percentage of the total PCDD and PCDF in the sediments which is the case for most sediment. The concentration of TCDD and TCDF in bivalves ranged from not detected (ND) to 25 pg/g and ND to 140 pg/g, respectively. Most bivalve samples, in contrast to the sediment contained low proportions of the higher molecular weight PCDDs and PCDFs. The relative toxicological importance of 2,3,7,8-TCDD, 2,3,7,8-TCDF and dioxin-like PCB to the bivalves from different locations will be compared based on toxicity equivalency factors.

  8. Mercury accumulation in marine bivalves: influences of biodynamics and feeding niche.

    PubMed

    Pan, Ke; Wang, Wen-Xiong

    2011-10-01

    Differences in the accumulation of mercury (Hg) in five species of marine bivalves, including scallops Chlamys nobilis, clams Ruditapes philippinarum, oysters Saccostrea cucullata, green mussels Perna viridis, and black mussels Septifer virgatus, were investigated. The bivalves displayed different patterns of Hg accumulation in terms of the body concentrations of methylmercury (MeHg) and total Hg (THg), as well as the ratio of MeHg to THg. Parameters of the biodynamics of the accumulation of Hg(II) and MeHg could reflect the species-dependent Hg concentrations in the bivalves. With the exception of black mussels, we found a significant relationship between the efflux rates of Hg(II) and the THg concentrations in the bivalves. The interspecific variations in the MeHg to THg ratio were largely controlled by the relative difference between the elimination rates of Hg(II) and MeHg. Stable isotope (δ(13)C) analysis indicated that the five bivalve species had contrasting feeding niches, which may also affect the Hg accumulation.

  9. Modification in digestive processing strategies to reduce toxic trace metal uptake in a marine bivalve

    SciTech Connect

    Decho, A.W.; Luoma, S.N.

    1994-12-31

    Bivalves possess two major digestion pathways for processing food particles: a rapid ``intestinal`` pathway where digestion is largely extracellular; and a slower ``glandular`` pathway where digestion is largely intracellular. The slower glandular pathway often results in more efficient absorption of carbon but also more efficient uptake of certain metals (e.g. Cr associated with bacteria). In the bivalve Potamocorbula amurensis, large portions (> 90%) of bacteria are selectively routed to the glandular pathway. This results in efficient C uptake but also efficient uptake of associated Cr. The authors further determined if prolonged exposure to Cr-contaminated bacteria would result in high Cr uptake by animals or whether mechanisms exist to reduce Cr exposure and uptake. Bivalves were exposed to natural food + added bacteria (with or without added Cr) for a 6-day period, then pulse-chase experiments were conducted to quantify digestive processing and % absorption efficiencies (%AE) of bacterial Cr. Bivalves compensate at low (2--5 ug/g sed) Cr by reducing overall food ingestion, while digestive processing of food remains statistically similar to controls. At high Cr (200--500 ug/g sed) there are marked decreases in % bacteria processed by glandular digestion. This results in lower overall %AE of Cr. The results suggest that bivalves under natural conditions might balance efficient carbon sequestration against avoiding uptake of potentially toxic metals associated the food.

  10. Organohalogenated contaminants in sediments and bivalves from the Northern Arabian Gulf.

    PubMed

    Ali, Nadeem; Ali, Lulwa Naseer; Eqani, Syed Ali Musstjab Akber Shah; Ismail, Iqbal Mohammad Ibrahim; Malarvannan, Govindan; Kadi, Mohammad W; Al-Badry Basahi, Jalal Mohammed; Covaci, Adrian

    2015-12-01

    Several classes of Organohalogenated contaminants (OHCs) were determined in sediments and bivalves collected from Kuwait coast. The levels and profile of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) were compared in both sediments and bivalves. PCB-153 and -138 were the major contributors towards total OHCs followed by DDT and its metabolites (DDTs). The higher contribution of DDTs (~40%) and BDE-47 (~15%) in bivalves as compared to that in associated sediments indicated high biota-sediment accumulation factors (BSAF). Higher BSAF (values for heavier PCBs, DDTs and PBDEs) also indicated their high accumulation potential from sediment into associated biota at most of the studied locations. Overall, OHCs in sediments and bivalves measured in current study were lower than those reported in the literature worldwide. Most of the sediment concentrations of OHCs (ng/g, dry weight) were in the range of permissible guideline values proposed by Canadian Sediment Quality Guidelines (CSQGs), with few exceptions for DDTs (5 ng/g) and PCBs (22.7 ng/g). Similarly, 10% of bivalve samples contained high levels (ng/g, lipid weight) of PCBs (300) and DDTs (150) and were above the set safety benchmarks. This study establishes baseline for future monitoring programs.

  11. Trace Fossil Evidence of Trematode-Bivalve Parasite-Host Interactions in Deep Time.

    PubMed

    Huntley, John Warren; De Baets, Kenneth

    2015-01-01

    Parasitism is one of the most pervasive phenomena amongst modern eukaryotic life and yet, relative to other biotic interactions, almost nothing is known about its history in deep time. Digenean trematodes (Platyhelminthes) are complex life cycle parasites, which have practically no body fossil record, but induce the growth of characteristic malformations in the shells of their bivalve hosts. These malformations are readily preserved in the fossil record, but, until recently, have largely been overlooked by students of the fossil record. In this review, we present the various malformations induced by trematodes in bivalves, evaluate their distribution through deep time in the phylogenetic and ecological contexts of their bivalve hosts and explore how various taphonomic processes have likely biased our understanding of trematodes in deep time. Trematodes are known to negatively affect their bivalve hosts in a number of ways including castration, modifying growth rates, causing immobilization and, in some cases, altering host behaviour making the host more susceptible to their own predators. Digeneans are expected to be significant agents of natural selection. To that end, we discuss how bivalves may have adapted to their parasites via heterochrony and suggest a practical methodology for testing such hypotheses in deep time.

  12. Distribution, abundance, and habitat associations of a large bivalve (Panopea generosa) in a eutrophic, fjord estuary

    USGS Publications Warehouse

    Mcdonald, P. Sean; Essington, Timothy E.; Davis, Jonathan P.; Galloway, Aaron W.E.; Stevick, Bethany C.; Jensen, Gregory C.; Vanblaricom, Glenn R.; Armstrong, David A.

    2015-01-01

    Marine bivalves are important ecosystem constituents and frequently support valuable fisheries. In many nearshore areas, human disturbance—including declining habitat and water quality—can affect the distribution and abundance of bivalve populations, and complicate ecosystem and fishery management assessments. Infaunal bivalves, in particular, are frequently cryptic and difficult to detect; thus, assessing potential impacts on their populations requires suitable, scalable methods for estimating abundance and distribution. In this study, population size of a common benthic bivalve (the geoduck Panopea generosa) is estimated with a Bayesian habitat-based model fit to scuba and tethered camera data in Hood Canal, a fjord basin in Washington state. Densities declined more than two orders of magnitude along a north—south gradient, concomitant with patterns of deepwater dissolved oxygen, and intensity and duration of seasonal hypoxia. Across the basin, geoducks were most abundant in loose, unconsolidated, sand substrate. The current study demonstrates the utility of using scuba, tethered video, and habitat models to estimate the abundance and distribution of a large infaunal bivalve at a regional (385-km2) scale.

  13. What's in a Shell? - Interactions of Chemistry and Structure at Submicron Levels in Bivalve Shells

    NASA Astrophysics Data System (ADS)

    Jacob, D. E.; Piazolo, S.; Trimby, P.

    2014-12-01

    The wide geographical distribution of bivalve shells makes them much favoured paleoclimate proxy archives. However, they are amongst the materials most affected by physiological effects, making the correct deciphering of these archives a challenging task. Shell building plans are usually hierarchic, thus optimizing mechanical properties. However, different structures common to certain bivalve families, such as the prism-nacre or the crossed-lamellar structures, are assembled from very different building blocks. These structural differences coincide with chemical and crystallographic differences suggesting critically different formation mechanisms within the bivalve class. Most importantly some bivalves form their shells from amorphous calcium carbonate that crystallizes in situ once assembled into the shell. We present new correlated multi-scale structural and compositional data for different shell bivalve shell structures such as nacre-prism, cross-lamellar intermediate structures. Data are obtained using EBSD, FIB-assisted TEM and Transmission Kikuchi Diffraction combined with Nano-SIMS and Raman Microspectrometry and suggest that formation from amorphous phases is widespread and results in different calcium carbonate polymorphs to be present in the shell with distinct chemical compositions. The results highlight the complex nature of the biomaterials, which has consequences for the precision and accuracy of paleotemperature calculations.

  14. Modeling bivalve diversification: the effect of interaction on a macroevolutionary system

    NASA Technical Reports Server (NTRS)

    Miller, A. I.; Sepkoski, J. J. Jr; Sepkoski JJ, J. r. (Principal Investigator)

    1988-01-01

    The global diversification of the class Bivalvia has historically received two conflicting interpretations. One is that a major upturn in diversification was associated with, and a consequence of, the Lake Permian mass extinction. The other is that mass extinctions have had little influence and that bivalves have experienced slow but nearly steady exponential diversification through most of their history, unaffected by interactions with other clades. We find that the most likely explanation lies between these two interpretations. Through most of the Phanerozoic, the diversity of bivalves did indeed exhibit slow growth, which was not substantially altered by mass extinctions. However, the presence of "hyperexponential bursts" in diversification during the initial Ordovician radiation and following the Late Permian and Late Cretaceous mass extinctions suggests a more complex history in which a higher characteristic diversification rate was dampened through most of the Phanerozoic. The observed pattern can be accounted for with a two-phase coupled (i.e., interactive) logistic model, where one phase is treated as the "bivalves" and the other phase is treated as a hypothetical group of clades with which the "bivalves" might have interacted. Results of this analysis suggest that interactions with other taxa have substantially affected bivalve global diversity through the Phanerozoic.

  15. Persistent free radical ESR signals in marine bivalve tissues

    SciTech Connect

    Mehlorn, R.J.; Mendez, A.T.; Higashi, R.; Fan, T.

    1992-08-01

    Freeze-dried homogenates of the oyster Crassostrea rhizophorae collected from waters in Puerto Rico near urban and industrial sites as well as at relatively pristine locations yielded electron spin resonance (ESR) spectra characteristic of free radicals as well as spectral components of transition metal ions, dominated by manganese. The magnitudes of these ESR signals and the concentrations of trace elements (determined by X-ray fluorescence) varied considerably among oyster samples, masking any potential correlation with polluted waters. Laboratory studies were initiated to identify the factors controlling the magnitudes of the tissue free radical ESR signals. Another mollusc, Mytilus californianus collected at the Bodega Marine laboratory in northern California, was fractionated into goneds and remaining tissue. Freeze-dried homogenates of both fractions exhibited ESR signals that increased gradually with time. ESR signals were observed in freeze-dried perchloric acid (PCA) precipitates of the homogenates, delipidated PCA precipitates, and in chloroform extracts of these precipitates. Acid hydrolysis to degrade proteins to amino acids produced a residue, which yielded much larger ESR free radical signals after freeze-drying. Freshly thawed homogenates of Crassostrea rhizophorae also exhibited ESR signals. A laboratory model of copper stress in Crassostrea rhizophorae was developed to study the effect of this transition metal on dssue free radicals. Preliminary results suggested that sublethal copper exposure had little effect on tissue fire radicals, except possibly for a signal enhancement in an oyster fraction that was enriched in kidney granules. Since kidney granules are known to accumulate heavy metals in mussels and probably other marine bivalves, this signal enhancement may prove to be an indicator of free radical processes associated with heavy metal deposition in molluscs.

  16. Zebra mussel infestation of unionid bivalves (Unionidae) in North America

    USGS Publications Warehouse

    Schloesser, Don W.; Nalepa, Thomas F.; Mackie, Gerald L.

    1996-01-01

    In 1989, zebra mussels received national attention in North America when they reached densities exceeding 750,000/m2 in a water withdrawal facility along the shore of western Lake Erie of the Laurentian Great Lakes. Although water withdrawal problems caused by zebra mussels have been of immediate concern, ecological impacts attributed to mussels are likely to be the more important long-term issue for surface waters in North America. To date, the epizoic colonization (i.e., infestation) of unionid bivalve mollusks by zebra mussels has caused the most direct and severe ecological impact. Infestation of and resulting impacts caused by zebra mussels on unionids in the Great Lakes began in 1988. By 1990, mortality of unionids was occurring at some locations; by 1991, extant populations of unionids in western Lake Erie were nearly extirpated; by 1992, unionid populations in the southern half of Lake St. Clair were extirpated; by 1993, unionids in widely separated geographic areas of the Great Lakes and the Mississippi River showed high mortality due to mussel infestation. All infested unionid species in the Great Lakes (23) have become infested and exhibited mortality within two to four years after heavy infestation began. Data indicate that mean zebra mussel densities >5,000–6,000/m2 and infestation intensities >100-200/unionid in the presence of heavy zebra mussel recruitment results in near total mortality of unionids. At present, all unionid species in rivers, streams, and akes that sympatrically occur with zebra mussels have been infested and, in many locations, negatively impacted by zebra mussels. We do not know the potential consequences of infestation on the 297 unionid species found in North America, but believe zebra mussels pose an immediate threat to the abundance and diversity of unionids.

  17. Distribution of organotin compounds in the bivalves of the Aegean Sea, Greece.

    PubMed

    Chandrinou, S; Stasinakis, A S; Thomaidis, N S; Nikolaou, A; Wegener, J W

    2007-02-01

    Five bivalve species--Mytilus galloprovinciallis (Mediterranean mussels), Venus gallina (stripped venus), Modiola barbatus L. (bearded horse mussels), Pecten jacobeus (scallops) and Callista chione (hard clams)--were collected from seven areas in Aegean Sea, Greece, between August 2001 and January 2003 and analyzed for organotins (OTs). The concentrations (as geometric means) found were 17.1 ng g-1 for tributyltin (TBT), 18.8 ng g-1 for dibutytltin (DBT), 7.8 ng g-1 for monobutyltin (MBT) and 13.0 ng g-1 for triphenyltin (TPhT) (wet weight), which are at similar or lower levels than those reported worldwide. Studying OTs distribution between different bivalve species, lower concentrations were observed in mediterranean mussels, possibly due to their growth in water column (grown on sea net pens in mussel farms), in contrast to the free-ranging species, collected from fishing grounds. Concentrations of the OTs in the examined bivalves varied seasonally. PMID:17067676

  18. Approaches for evaluating the effects of bivalve filter feeding on nutrient dynamics in Puget Sound, Washington

    USGS Publications Warehouse

    Konrad, Christopher P.

    2014-01-01

    Marine bivalves such as clams, mussels, and oysters are an important component of the food web, which influence nutrient dynamics and water quality in many estuaries. The role of bivalves in nutrient dynamics and, particularly, the contribution of commercial shellfish activities, are not well understood in Puget Sound, Washington. Numerous approaches have been used in other estuaries to quantify the effects of bivalves on nutrient dynamics, ranging from simple nutrient budgeting to sophisticated numerical models that account for tidal circulation, bioenergetic fluxes through food webs, and biochemical transformations in the water column and sediment. For nutrient management in Puget Sound, it might be possible to integrate basic biophysical indicators (residence time, phytoplankton growth rates, and clearance rates of filter feeders) as a screening tool to identify places where nutrient dynamics and water quality are likely to be sensitive to shellfish density and, then, apply more sophisticated methods involving in-situ measurements and simulation models to quantify those dynamics.

  19. Independent phylogenetic origins of methanotrophic and chemoautotrophic bacterial endosymbioses in marine bivalves.

    PubMed Central

    Distel, D L; Cavanaugh, C M

    1994-01-01

    The discovery of bacterium-bivalve symbioses capable of utilizing methane as a carbon and energy source indicates that the endosymbionts of hydrothermal vent and cold seep bivalves are not restricted to sulfur-oxidizing chemoautotrophic bacteria but also include methanotrophic bacteria. The phylogenetic origin of methanotrophic endosymbionts and their relationship to known symbiotic and free-living bacteria, however, have remained unexplored. In situ localization and phylogenetic analysis of a symbiont 16S rRNA gene cloned from the gills of a recently described deep-sea mussel species demonstrate that this symbiont represents a new taxon which is closely related to free-living, cultivable Type I methanotrophic bacteria. This symbiont is distinct from known chemoautotrophic symbionts. Thus, despite compelling similarities between the symbioses, chemoautotrophic and methanotrophic symbionts of marine bivalves have independent phylogenetic origins. Images PMID:8144459

  20. A comparative study on the effects of barite, ilmenite and bentonite on four suspension feeding bivalves.

    PubMed

    Strachan, Maia F; Kingston, Paul F

    2012-10-01

    The impact of drilling mud components on the filtration activity and survival of bivalve molluscs was investigated by exposing them to suspensions of 'standard' barite, finely milled barite, ilmenite and bentonite in sea water. Introduction of the components stimulated filtration activity in all four bivalves. In addition, the introduction of standard barite and ilmenite both had lethal effects, with none of the bivalves surviving the full duration of the experiments. In-vivo observations of the gill surfaces provided direct evidence of physical damage caused by the administration of barite and ilmenite. A marked difference between filtration activity and survival of animals dosed with 'standard' barite and 'fine' barite suggests that the observed effects were primarily caused by physical interference with gill function. The results also suggest that the use of fine barite in offshore drilling may provide a more favourable environmental impact profile than the use of ilmenite.

  1. Arsenic and trace metals in commercially important bivalves, Anadara granosa and Paphia undulata

    SciTech Connect

    Mat, I. )

    1994-06-01

    The semi-culture of marine bivalves particularly Anadara granosa is of considerable economic importance in Malaysia. Currently, about 4-5000 ha of mudflats along the west coast are utilized for this purpose. Therefore, contamination of the highly productive mudflats with heavy metals tend to be accumulated in the filter feeding organisms such as bivalve molluscs which often serve as important environmental sinks of heavy metals. Bivalve molluscs, A. granosa and Paphia undulata are commercially important seafoods and popular among the locals in Malaysia. With this point in mind, it is intended to evaluate the concentration levels of arsenic as well as trace metals (Co, Cu, Ni, Cd, Zn, Cr and Pb) in both species derived from retail outlets in the city of Kuala Lumpur. Although this analysis may not indicate the site of capture but may act as a direct check on the contamination of seafoods available to the consumers. 17 refs., 2 tabs.

  2. Characterization of the mantle transcriptome in bivalves: Pecten maximus, Mytilus edulis and Crassostrea gigas.

    PubMed

    Yarra, Tejaswi; Gharbi, Karim; Blaxter, Mark; Peck, Lloyd S; Clark, Melody S

    2016-06-01

    The calcareous shells secreted by bivalve molluscs display diverse and species specific structural compositions, which indicates possible divergent biomineralization processes. Thus, studying multiple mollusc species will provide a more comprehensive understanding of shell formation. Here, the transcriptomes of the mantle tissues responsible for shell deposition were characterized in three commercially relevant bivalve species. Using high-throughput sequencing and bioinformatics tools, de novo transcriptome assemblies of mantle tissues were generated for the mussel Mytilus edulis, the oyster Crassostrea gigas and the scallop Pecten maximus. These transcriptomes were annotated, and contigs with similarity to proteins known to have shell formation roles in other species were identified. Comparison of the shell formation specific proteins in the three bivalves indicates the possibility of species specific shell proteins.

  3. Pathogenic marine microbes influence the effects of climate change on a commercially important tropical bivalve.

    PubMed

    Turner, Lucy M; Alsterberg, Christian; Turner, Andrew D; Girisha, S K; Rai, Ashwin; Havenhand, Jonathan N; Venugopal, M N; Karunasagar, Indrani; Godhe, Anna

    2016-08-31

    There is growing evidence that climate change will increase the prevalence of toxic algae and harmful bacteria, which can accumulate in marine bivalves. However, we know little about any possible interactions between exposure to these microorganisms and the effects of climate change on bivalve health, or about how this may affect the bivalve toxin-pathogen load. In mesocosm experiments, mussels, Perna viridis, were subjected to simulated climate change (warming and/or hyposalinity) and exposed to harmful bacteria and/or toxin-producing dinoflagellates. We found significant interactions between climate change and these microbes on metabolic and/or immunobiological function and toxin-pathogen load in mussels. Surprisingly, however, these effects were virtually eliminated when mussels were exposed to both harmful microorganisms simultaneously. This study is the first to examine the effects of climate change on determining mussel toxin-pathogen load in an ecologically relevant, multi-trophic context. The results may have considerable implications for seafood safety.

  4. Labelling and Marketing of Bivalve and Gastropod Molluscs Retailed in Sardinia, Italy Between 2009 and 2013

    PubMed Central

    2015-01-01

    The aim of the present survey was to investigate the correct enforcement of the Community rules on the labelling and marketing of bivalve and gastropod molluscs retailed in Sardinia, Italy between 2009 and 2013. A total of 1500 packages and labels for live bivalve and gastropod molluscs were considered. A total of 375 labels (25%) presented non-compliance concerning the wrong trade name and additional wrong or missing information. The highest percentage of anomalous labels has been detected in small-scale retail shops (35%) and open-air markets (25%) compared with the big retailing chains (20%). The 5% of packages were not in compliance with the European Community rules on packaging of bivalve and gastropod molluscs. The high percentage of non-compliance with the European regulations on labelling results is a strong limitation for the consumers and highlights the need to improve the control system about labelling of seafood products. PMID:27800397

  5. A comparative study on the effects of barite, ilmenite and bentonite on four suspension feeding bivalves.

    PubMed

    Strachan, Maia F; Kingston, Paul F

    2012-10-01

    The impact of drilling mud components on the filtration activity and survival of bivalve molluscs was investigated by exposing them to suspensions of 'standard' barite, finely milled barite, ilmenite and bentonite in sea water. Introduction of the components stimulated filtration activity in all four bivalves. In addition, the introduction of standard barite and ilmenite both had lethal effects, with none of the bivalves surviving the full duration of the experiments. In-vivo observations of the gill surfaces provided direct evidence of physical damage caused by the administration of barite and ilmenite. A marked difference between filtration activity and survival of animals dosed with 'standard' barite and 'fine' barite suggests that the observed effects were primarily caused by physical interference with gill function. The results also suggest that the use of fine barite in offshore drilling may provide a more favourable environmental impact profile than the use of ilmenite. PMID:22831859

  6. Bivalves from the latest Jurassic-earliest Cretaceous hydrocarbon seep carbonates from central Spitsbergen, Svalbard.

    PubMed

    Hryniewicz, Krzysztof; Little, Crispin T S; Nakrem, Hans Arne

    2014-09-02

    The bivalve fauna from the latest Jurassic-earliest Cretaceous hydrocarbon seep deposits from central Spitsbergen, Svalbard comprises at least 17 species, four of which belong to chemosymbiotic taxa often found at seeps. These are the solemyid Solemya (Petrasma) cf. woodwardiana; Nucinella svalbardensis sp. nov., which belongs to a group of large Nucinella species known from seeps and deep water environments; the lucinid bivalve, Tehamatea rasmusseni sp. nov., included in a genus widely distributed in other Jurassic-Cretaceous seeps; and Cretaxinus hurumi gen. et sp. nov., which is the oldest known thyasirid and is discussed in relation to other large seep-restricted genera in this family. The remaining species in the fauna belong to 'background' genera known from coeval normal marine sediments, mostly from the Boreal area. These include the nuculid Dacromya chetaensis, two new malletiids (Mesosaccella rogovi sp. nov. and M. toddi sp. nov.), the oxytomiid Oxytoma octavia, at least three Buchia species, at least two pectinids, including Camptonectes (Costicamptonectes) aff. milnelandensis and Camptonectes (Camptochlamys) clatrathus, the limid Pseudolimea arctica, the arcticid Pseudotrapezium aff. groenlandicum, and the pholadomyid Goniomya literata. The large number of 'background' species in the bivalve fauna is probably a reflection of the shallow-water setting of the Svalbard seeps. This might also explain the lack of the seep-restricted modiomorphid bivalve Caspiconcha from the fauna. With solemyids, Nucinella, lucinids and thyasirids, the latest Jurassic-earliest Cretaceous bivalve seep fauna of Svalbard contains typical representatives of the Mesozoic bivalve seep faunas, both long established and young evolutionary colonists.

  7. A Gray-purple Mass on the Floor of the Mouth: Gigantic Mucogingival Pyogenic Granuloma in a Teenage Patient

    PubMed Central

    Brunet-LLobet, Lluís; Miranda-Rius, Jaume; Lahor-Soler, Eduard; Mrina, Ombeni; Nadal, Alfons

    2014-01-01

    Pyogenic granuloma is defined as a benign neoplasm of vascular phenotype. This case describes the clinical and histopathological features of a gigantic mucogingival pyogenic granuloma, in a 14-year-old healthy black boy. This exophytic gray-purple mass, related to a toothpick injury, had more than twelve-month evolution on the anterior mandible involving lingual area besides to the floor of the mouth pressing the right salivary duct. Conservative excision was performed, followed by uncomplicated healing with no recurrence in two years. The histopathological examination reported a pyogenic granuloma (lobular capillary haemangioma). The authors provide a discussion of the presurgical differential diagnosis of the lesion. This case report presents an extremely uncommon location of a gigantic pyogenic granuloma, involving mucogingival complex and affecting the salivary outflow. This clinical manuscript may shed light on the controversies about possible mechanisms inducing oral pyogenic granuloma. PMID:24987485

  8. Acromegalic gigantism with low serum level of growth hormone and elevated serum insulin-like growth factor-I.

    PubMed

    Miyazaki, R; Yoshida, T; Sakane, N; Yasuda, T; Umekawa, T; Kondo, M; Shimatsu, A; Hizuka, N; Sano, T

    1995-03-01

    In a case of acromegalic gigantism with hyperprolactinemia is reported, the basal serum growth hormone (GH) levels ranged from 1.2 to 1.9 ng/ml. Serum GH response to either insulin-induced hypoglycemia or GH-releasing hormone was blunted. Frequent blood sampling showed non-pulsatile GH secretion. Serum prolactin and insulin-like growth factor-I (IGF-I) levels were elevated. After unsuccessful surgery, bromocriptine treatment normalized serum prolactin without affecting serum GH and IGF-I levels. Combined administration of octreotide with bromocriptine reduced serum GH and IGF-I levels. In this case, non-pulsatile GH secretion and enhanced tissue sensitivity to GH may induce hypersecretion of IGF-I and cause clinical acromegalic gigantism. PMID:7787324

  9. Mussel watch - measurements of chemical pollutants in bivalves as one indicator of coastal environmental quality

    SciTech Connect

    Farrington, J.W.; Davis, A.C.; Tripp, B.W.; Phelps, D.K.; Galloway, W.B.

    1987-01-01

    The utility of the bivalve sentinel organism approach to monitoring for some chemicals of environmental concern in coastal and estuarine areas has been evaluated by regional and national programs and by smaller-scale research efforts during the past 15 years. The extent and severity of coastal contamination by chemicals such as polychlorinated biphenyls, chlorinated pesticides, trace metals, and plutonium was assessed in several bivalve sentinel organism programs. Advantages and limitations of this approach are presented and discussed briefly within the context of both national and international efforts.

  10. Arsenic in benthic bivalves of San Francisco Bay and the Sacramento/San Joaquin River Delta

    USGS Publications Warehouse

    Johns, C.; Luoma, S.N.

    1990-01-01

    Arsenic concentrations were determined in fine-grained, oxidized, surface sediments and in two benthic bivalves, Corbicula sp. and Macoma balthica, within San Francisco Bay, the Sacramento/San Joaquin River Delta, and selected rivers not influenced by urban or industrial activity. Arsenic concentrations in all samples were characteristic of values reported for uncontaminated estuaries. Small temporal fluctuations and low arsenic concentrations in bivalves and sediments suggest that most inputs of arsenic are likely to be minor and arsenic contamination is not widespread in the Bay.

  11. GaAs-oxide interface states - A gigantic photoionization effect and its implications to the origin of these states

    NASA Technical Reports Server (NTRS)

    Lagowski, J.; Walukiewicz, W.; Kazior, T. E.; Gatos, H. C.; Siejka, J.

    1981-01-01

    Gigantic photoionization was discovered on GaAs-oxide interfaces leading to the discharge of deep surface states with rates exceeding 1000 times those of photoionization transitions to the conduction band. It exhibits a peak similar to acceptor-donor transitions and is explained as due to energy transfer from photo-excited donor-acceptor pairs to deep surface states. This new process indicates the presence of significant concentrations of shallow donor and acceptor levels not recognized in previous interface models.

  12. Polyostotic fibrous dysplasia with gigantism and huge pelvic tumor: a rare case of McCune-Albright syndrome.

    PubMed

    Sakayama, Kenshi; Sugawara, Yoshifumi; Kidani, Teruki; Fujibuchi, Taketsugu; Kito, Katsumi; Tanji, Nozomu; Nakamura, Atsushi

    2011-06-01

    We report a rare case of polyostotic fibrous dysplasia on endocrine hyperfunction with elevated human growth hormone and normal serum level of prolactin. There were some differential points of gender, gigantism, endocrine function, and GNAS gene from McCune-Albright syndrome. Malignant transformation was suspected in the pelvic tumor from imaging because rapid growth of the tumor by imaging was observed; however, no malignant change occurred in this case. PMID:20878436

  13. Efficacy, safety, and pharmacokinetics of sustained-release lanreotide (lanreotide Autogel) in Japanese patients with acromegaly or pituitary gigantism.

    PubMed

    Shimatsu, Akira; Teramoto, Akira; Hizuka, Naomi; Kitai, Kazuo; Ramis, Joaquim; Chihara, Kazuo

    2013-01-01

    The somatostatin analog lanreotide Autogel has proven to be efficacious for treating acromegaly in international studies and in clinical practices around the world. However, its efficacy in Japanese patients has not been extensively evaluated. We examined the dose-response relationship and long-term efficacy and safety in Japanese patients with acromegaly or pituitary gigantism. In an open-label, parallel-group, dose-response study, 32 patients (29 with acromegaly, 3 with pituitary gigantism) received 5 injections of 60, 90, or 120 mg of lanreotide Autogel over 24 weeks. Four weeks after the first injection, 41% of patients achieved serum GH level of <2.5 ng/mL and insulin-like growth factor-I (IGF-I) level was normalized in 31%. Values at Week 24 were 53% for GH and 44% for IGF-I. Dose-dependent decreases in serum GH and IGF-I levels were observed with dose-related changes in pharmacokinetic parameters. In an open-label, long-term study, 32 patients (30 with acromegaly, 2 with pituitary gigantism) received lanreotide Autogel once every 4 weeks for a total of 13 injections. Dosing was initiated with 90 mg and adjusted according to clinical responses at Weeks 16 and/or 32. At Week 52, 47% of patients had serum GH levels of <2.5 ng/mL and 53% had normalized IGF-I level. In both studies, acromegaly symptoms improved and treatment was generally well tolerated although gastrointestinal symptoms and injection site induration were reported. In conclusion, lanreotide Autogel provided early and sustained control of elevated GH and IGF-I levels, improved acromegaly symptoms, and was well tolerated in Japanese patients with acromegaly or pituitary gigantism. PMID:23337477

  14. Efficacy, safety, and pharmacokinetics of sustained-release lanreotide (lanreotide Autogel) in Japanese patients with acromegaly or pituitary gigantism.

    PubMed

    Shimatsu, Akira; Teramoto, Akira; Hizuka, Naomi; Kitai, Kazuo; Ramis, Joaquim; Chihara, Kazuo

    2013-01-01

    The somatostatin analog lanreotide Autogel has proven to be efficacious for treating acromegaly in international studies and in clinical practices around the world. However, its efficacy in Japanese patients has not been extensively evaluated. We examined the dose-response relationship and long-term efficacy and safety in Japanese patients with acromegaly or pituitary gigantism. In an open-label, parallel-group, dose-response study, 32 patients (29 with acromegaly, 3 with pituitary gigantism) received 5 injections of 60, 90, or 120 mg of lanreotide Autogel over 24 weeks. Four weeks after the first injection, 41% of patients achieved serum GH level of <2.5 ng/mL and insulin-like growth factor-I (IGF-I) level was normalized in 31%. Values at Week 24 were 53% for GH and 44% for IGF-I. Dose-dependent decreases in serum GH and IGF-I levels were observed with dose-related changes in pharmacokinetic parameters. In an open-label, long-term study, 32 patients (30 with acromegaly, 2 with pituitary gigantism) received lanreotide Autogel once every 4 weeks for a total of 13 injections. Dosing was initiated with 90 mg and adjusted according to clinical responses at Weeks 16 and/or 32. At Week 52, 47% of patients had serum GH levels of <2.5 ng/mL and 53% had normalized IGF-I level. In both studies, acromegaly symptoms improved and treatment was generally well tolerated although gastrointestinal symptoms and injection site induration were reported. In conclusion, lanreotide Autogel provided early and sustained control of elevated GH and IGF-I levels, improved acromegaly symptoms, and was well tolerated in Japanese patients with acromegaly or pituitary gigantism.

  15. Polyostotic fibrous dysplasia with gigantism and huge pelvic tumor: a rare case of McCune-Albright syndrome.

    PubMed

    Sakayama, Kenshi; Sugawara, Yoshifumi; Kidani, Teruki; Fujibuchi, Taketsugu; Kito, Katsumi; Tanji, Nozomu; Nakamura, Atsushi

    2011-06-01

    We report a rare case of polyostotic fibrous dysplasia on endocrine hyperfunction with elevated human growth hormone and normal serum level of prolactin. There were some differential points of gender, gigantism, endocrine function, and GNAS gene from McCune-Albright syndrome. Malignant transformation was suspected in the pelvic tumor from imaging because rapid growth of the tumor by imaging was observed; however, no malignant change occurred in this case.

  16. Peculiarities of the geologic structure of gigantic gas fields of the western Siberian oil and gas province

    SciTech Connect

    Belyi, N.

    1991-03-01

    The Western Siberian Oil and Gas Province is a unique one regarding the concentration of natural gas resources in Mesozoic terrigenous formations. Discovery of gigantic natural gas fields makes it possible to provide high level of gas production for future prospects. The USSR has enormous potential possibilities for discoveries of new natural gas fields onshore, as well as offshore. At present, three gigantic gas fields have been developed, namely Medvezhie, Urongoi, and Yamburg. The first one has been in operation for 18 years. In the Mesozoic section, three productive complexes can be noticed: Upper Cretaceous, Lower Cretaceous, and Jurassic. The Upper Cretaceous production complex is mostly explored, with unique gas resources containing mainly methane having been discovered. The Lower Cretaceous production complex is characterized by considerable lithofaceous uniformity of reservoirs. Gas pools of this complex contain considerable quantities of condensate quite often having oil rims. The Jurassic production complex, which is characterized by its complicated structure and considerable changeability of the filtration properties, is less studied. Study of the geological structural peculiarities of the gigantic gas fields of Western Siberia gives us the possibility to find new approval for the development and exploration of gas fields.

  17. Gravity combined with laser-scan in Grotta Gigante: a benchmark cave for gravity studies

    NASA Astrophysics Data System (ADS)

    Pivetta, Tommaso; Braitenberg, Carla

    2014-05-01

    Laser scanning has become one of the most important topographic techniques in the last decades, due to its ability to reconstruct complex surfaces with high resolution and precision and due to its fast acquisition time. Recently a laser-scan survey has been acquired (Fingolo et al., 2011) in the "Grotta Gigante" cave near Trieste, Italy, the biggest cave worldwide according to the Guinness Awards. In this paper this survey is used to obtain a 3D discretization of the cave with prisms. Then through this new model, with the densities derived from campaign measurements, the exact gravimetric effect of the structure was computed (Nagy et al., 2000) and compared with the gravity observation at the surface. The transition from the cloud of laser-scan points to the prism model was carried out by different computer elaborations; first of all the reduction of the data density through an averaging process that allows to pass from over 10000 points/m2 to less than 10points/m2. Then the whole dataset was filtered from the outliers by the means of a simple quadratic surface that fit the data (Turner, 1999). The reduced data points should be divided into the 2 surfaces of top and bottom, that are used to define the prisms. This step was performed using the local regression method (Loess) to calculate a surface located halfway between top and bottom points. Once the top and bottom interfaces were obtained it was possible to get the final prism representation and calculate the gravity signal. The observed Bouguer field is explained very well by our model and the residuals are used to evaluate possible secondary caves. The final prism model together with the gravity database on surface and inside the cave form a perfect benchmark to test forward and inverse potential field algorithms. References Fingolo M., Facco L., Ceccato A., Breganze C., Paganini P., Cezza M., Grotta Gigante di Trieste. Tra realtà virtuale e rilievi 3D ad alta risoluzione, Veneto Geologi, 75, pp.21-25, 2011

  18. Bivalve effects on the food web supporting delta smelt—A long-term study of bivalve recruitment, biomass, and grazing rate patterns with varying freshwater outflow

    USGS Publications Warehouse

    Crauder, Jeff S.; Thompson, Janet K.; Parchaso, Francis; Anduaga, Rosa I.; Pearson, Sarah A.; Gehrts, Karen; Fuller, Heather; Wells, Elizabeth

    2016-01-21

    At the few stations where Potamocorbula and Corbicula co-occur, it appears that they did not hinder each other’s growth. Both bivalves had large animals at D4, where Corbicula size increased coincident with the presence of Potamocorbula in 1987. Corbicula were observed in wet years prior to Potamocorbula’sinvasion at D7 (Grizzly Bay) and were capable of growing to significant size in wet years (> 20 mm in 1986). 

  19. Bivalve effects on the food web supporting delta smelt—A long-term study of bivalve recruitment, biomass, and grazing rate patterns with varying freshwater outflow

    USGS Publications Warehouse

    Crauder, Jeff S.; Thompson, Janet K.; Parchaso, Francis; Anduaga, Rosa I.; Pearson, Sarah A.; Gehrts, Karen; Fuller, Heather; Wells, Elizabeth

    2016-01-01

    At the few stations where Potamocorbula and Corbicula co-occur, it appears that they did not hinder each other’s growth. Both bivalves had large animals at D4, where Corbicula size increased coincident with the presence of Potamocorbula in 1987. Corbicula were observed in wet years prior to Potamocorbula’sinvasion at D7 (Grizzly Bay) and were capable of growing to significant size in wet years (> 20 mm in 1986). 

  20. A 12-year-old girl presenting with bilateral gigantic Burkitt's lymphoma of the breast.

    PubMed

    Lingohr, Philipp; Eidt, Sebastian; Rheinwalt, Karl Peter

    2009-05-01

    The female breast rarely constitutes the primary localization for non-Hodgkin's lymphoma (NHL). The incidence of primary breast lymphoma (PBL) lies between 0.04 and 1.1% for all breast tumors and 1.7-2.2% for all extranodal NHL. Mostly it occurs during the child-bearing period, during pregnancy or lactation. In general, children between the ages of 8 and 10 years are most frequently affected by Burkitt's lymphoma. Methods for classification, detection and especially treatment of this condition continue being a subject of discussions and research. We present and evaluate the rare case of a 12-year-old girl with bilateral gigantic breast tumors treated during a surgical mission with "Doctors without borders" (MSF, "médecins sans frontiers") in the zone of civil war in the Democratic Republic of Congo. The monstrous bilateral breast hypertrophy, symmetrical, rapidly growing, consequently ulcerating and severely bleeding had to be treated by bilateral mastectomy as a salvage procedure. Examinations through histopathology was not feasible and other facilities like ultrasound, CT, MRI and further laboratory examinations were not available.. The patient died 27 days after the surgical procedure. The histological result received by later examination in Germany showed a bilateral high malignant B cell lymphoma (Burkitt lymphoma) of the breast.

  1. Respiratory evolution facilitated the origin of pterosaur flight and aerial gigantism.

    PubMed

    Claessens, Leon P A M; O'Connor, Patrick M; Unwin, David M

    2009-01-01

    Pterosaurs, enigmatic extinct Mesozoic reptiles, were the first vertebrates to achieve true flapping flight. Various lines of evidence provide strong support for highly efficient wing design, control, and flight capabilities. However, little is known of the pulmonary system that powered flight in pterosaurs. We investigated the structure and function of the pterosaurian breathing apparatus through a broad scale comparative study of respiratory structure and function in living and extinct archosaurs, using computer-assisted tomographic (CT) scanning of pterosaur and bird skeletal remains, cineradiographic (X-ray film) studies of the skeletal breathing pump in extant birds and alligators, and study of skeletal structure in historic fossil specimens. In this report we present various lines of skeletal evidence that indicate that pterosaurs had a highly effective flow-through respiratory system, capable of sustaining powered flight, predating the appearance of an analogous breathing system in birds by approximately seventy million years. Convergent evolution of gigantism in several Cretaceous pterosaur lineages was made possible through body density reduction by expansion of the pulmonary air sac system throughout the trunk and the distal limb girdle skeleton, highlighting the importance of respiratory adaptations in pterosaur evolution, and the dramatic effect of the release of physical constraints on morphological diversification and evolutionary radiation.

  2. Respiratory Evolution Facilitated the Origin of Pterosaur Flight and Aerial Gigantism

    PubMed Central

    Claessens, Leon P. A. M.; O'Connor, Patrick M.; Unwin, David M.

    2009-01-01

    Pterosaurs, enigmatic extinct Mesozoic reptiles, were the first vertebrates to achieve true flapping flight. Various lines of evidence provide strong support for highly efficient wing design, control, and flight capabilities. However, little is known of the pulmonary system that powered flight in pterosaurs. We investigated the structure and function of the pterosaurian breathing apparatus through a broad scale comparative study of respiratory structure and function in living and extinct archosaurs, using computer-assisted tomographic (CT) scanning of pterosaur and bird skeletal remains, cineradiographic (X-ray film) studies of the skeletal breathing pump in extant birds and alligators, and study of skeletal structure in historic fossil specimens. In this report we present various lines of skeletal evidence that indicate that pterosaurs had a highly effective flow-through respiratory system, capable of sustaining powered flight, predating the appearance of an analogous breathing system in birds by approximately seventy million years. Convergent evolution of gigantism in several Cretaceous pterosaur lineages was made possible through body density reduction by expansion of the pulmonary air sac system throughout the trunk and the distal limb girdle skeleton, highlighting the importance of respiratory adaptations in pterosaur evolution, and the dramatic effect of the release of physical constraints on morphological diversification and evolutionary radiation. PMID:19223979

  3. Commissioning of the gigantic anaerobic sludge digesters at the wastewater treatment plant of Athens.

    PubMed

    Gikas, P

    2008-02-01

    The pre-commissioning strategy, the start-up procedure and the analytical data obtained during the commissioning period for the first of the four new anaerobic gigantic digesters, with active volume of 10,000 m3 each, are presented in this paper. The digester was initially filled up with water, and the temperature was raised to 36 +/- 1 degrees C. Then, a total amount of 1,860 m3 of digested primary sludge was transferred, in four equal daily batches, into the digester from neighbouring digesters, performing routine operation. Following this, the digester was gradually fed with fresh primary thickened sludge, up to the point that the retention time reached approximately 20 d. A number of significant operational parameters (pH, alkalinity, total and volatile solids concentration, volatile fatty acids concentration, biogas production rate and composition) were monitored several times per day, and the appropriate adjustments were performed in order to achieve stable operation. The time duration of the whole process was about two and a half months. Later on, the digester was supplied with a mixture of primary and biological sludge.

  4. Discovery of gigantic molecular nanostructures using a flow reaction array as a search engine.

    PubMed

    Zang, Hong-Ying; de la Oliva, Andreu Ruiz; Miras, Haralampos N; Long, De-Liang; McBurney, Roy T; Cronin, Leroy

    2014-04-28

    The discovery of gigantic molecular nanostructures like coordination and polyoxometalate clusters is extremely time-consuming since a vast combinatorial space needs to be searched, and even a systematic and exhaustive exploration of the available synthetic parameters relies on a great deal of serendipity. Here we present a synthetic methodology that combines a flow reaction array and algorithmic control to give a chemical 'real-space' search engine leading to the discovery and isolation of a range of new molecular nanoclusters based on [Mo(2)O(2)S(2)](2+)-based building blocks with either fourfold (C4) or fivefold (C5) symmetry templates and linkers. This engine leads us to isolate six new nanoscale cluster compounds: 1, {Mo(10)(C5)}; 2, {Mo(14)(C4)4(C5)2}; 3, {Mo(60)(C4)10}; 4, {Mo(48)(C4)6}; 5, {Mo(34)(C4)4}; 6, {Mo(18)(C4)9}; in only 200 automated experiments from a parameter space spanning ~5 million possible combinations.

  5. Lower limb gigantism, lymphedema, and painful varicosities following a thigh vascular access graft.

    PubMed

    Thompson, Michael; Mathuram Thiyagarajan, Umasankar; Akoh, Jacob A

    2014-07-01

    Prosthetic arteriovenous grafts (AVGs) are associated with greater morbidity than autogenous arteriovenous fistulas (AVFs), but their use is indicated when AVF formation is not possible. This report adds to the literature a case of lower limb gigantism, painful varicosities, and lymphedema following long-term use of AVG in the upper thigh. The patient's past medical history included renal transplantation on the same side well before the AVG was inserted and right leg deep vein thrombosis. Suspicion of AVG thrombosis was excluded by Doppler ultrasound, which demonstrated an access flow of 1700 mL/min. A computed tomography (CT) scan of the abdomen and pelvis did not identify the cause of her symptoms. Whereas functional incompetence of the iliac vein valve might be responsible for the varicosities, the extent of hypertrophy in this case raises the suspicion of lymphatic blockage possibly secondary to groin dissection undertaken at the time of graft insertion, in addition to the previous dissection at the time of transplantation. This case highlights the need for minimal groin dissection during AVG insertion, particularly in patients with a history of previous abdominopelvic surgery. PMID:24467313

  6. Discovery of gigantic molecular nanostructures using a flow reaction array as a search engine

    PubMed Central

    Zang, Hong-Ying; de la Oliva, Andreu Ruiz; Miras, Haralampos N.; Long, De-Liang; McBurney, Roy T.; Cronin, Leroy

    2014-01-01

    The discovery of gigantic molecular nanostructures like coordination and polyoxometalate clusters is extremely time-consuming since a vast combinatorial space needs to be searched, and even a systematic and exhaustive exploration of the available synthetic parameters relies on a great deal of serendipity. Here we present a synthetic methodology that combines a flow reaction array and algorithmic control to give a chemical ‘real-space’ search engine leading to the discovery and isolation of a range of new molecular nanoclusters based on [Mo2O2S2]2+-based building blocks with either fourfold (C4) or fivefold (C5) symmetry templates and linkers. This engine leads us to isolate six new nanoscale cluster compounds: 1, {Mo10(C5)}; 2, {Mo14(C4)4(C5)2}; 3, {Mo60(C4)10}; 4, {Mo48(C4)6}; 5, {Mo34(C4)4}; 6, {Mo18(C4)9}; in only 200 automated experiments from a parameter space spanning ~5 million possible combinations. PMID:24770632

  7. Evolución de planetas gigantes y posibilidades de su detección directa

    NASA Astrophysics Data System (ADS)

    Brunini, A.; Benvenuto, O. G.

    Desde la reciente detección de planetas gigantes orbitando estrellas cercanas de tipo solar por medio de efecto Doppler, uno de los principales problemas, en cuanto al estudio de los sistemas planetarios extrasolares, se refiere a la posibilidad de obtener evidencia directa de su existencia. Esto parece ser factible gracias a que en un futuro cercano entrarán en operación algunos telescopios especialmente adecuados a estos propósitos. Por tal motivo, hemos comenzado desde hace un tiempo un esfuerzo en cuanto al estudio de la evolución planetaria. A tales efectos hemos adaptado el código de evolución estelar de nuestro Observatorio al caso planetario. Las principales diferencias entre el caso estelar y el planetario se encuentran en la ecuación de estado. A tales fines hemos incluído la reciente ecuación de estado de Saumon, Chabrier y Van Horn, las opacidades radiativas de Guillot et al., procesos de quema de Deuterio, etc. También se ha considerado la posible existencia de fases de hielo y roca en el interior planetario. Por el momento hemos despreciado los efectos de la rotación planetaria. Con este código hemos computado la evolución de planetas con masas desde 10 hasta 0.3 masas de Júpiter. Utilizando nuestros resultados numéricos discutimos la detectabilidad de estos objetos en condiciones realistas.

  8. Discovery of gigantic molecular nanostructures using a flow reaction array as a search engine.

    PubMed

    Zang, Hong-Ying; de la Oliva, Andreu Ruiz; Miras, Haralampos N; Long, De-Liang; McBurney, Roy T; Cronin, Leroy

    2014-01-01

    The discovery of gigantic molecular nanostructures like coordination and polyoxometalate clusters is extremely time-consuming since a vast combinatorial space needs to be searched, and even a systematic and exhaustive exploration of the available synthetic parameters relies on a great deal of serendipity. Here we present a synthetic methodology that combines a flow reaction array and algorithmic control to give a chemical 'real-space' search engine leading to the discovery and isolation of a range of new molecular nanoclusters based on [Mo(2)O(2)S(2)](2+)-based building blocks with either fourfold (C4) or fivefold (C5) symmetry templates and linkers. This engine leads us to isolate six new nanoscale cluster compounds: 1, {Mo(10)(C5)}; 2, {Mo(14)(C4)4(C5)2}; 3, {Mo(60)(C4)10}; 4, {Mo(48)(C4)6}; 5, {Mo(34)(C4)4}; 6, {Mo(18)(C4)9}; in only 200 automated experiments from a parameter space spanning ~5 million possible combinations. PMID:24770632

  9. Discovery of gigantic molecular nanostructures using a flow reaction array as a search engine

    NASA Astrophysics Data System (ADS)

    Zang, Hong-Ying; de La Oliva, Andreu Ruiz; Miras, Haralampos N.; Long, De-Liang; McBurney, Roy T.; Cronin, Leroy

    2014-04-01

    The discovery of gigantic molecular nanostructures like coordination and polyoxometalate clusters is extremely time-consuming since a vast combinatorial space needs to be searched, and even a systematic and exhaustive exploration of the available synthetic parameters relies on a great deal of serendipity. Here we present a synthetic methodology that combines a flow reaction array and algorithmic control to give a chemical ‘real-space’ search engine leading to the discovery and isolation of a range of new molecular nanoclusters based on [Mo2O2S2]2+-based building blocks with either fourfold (C4) or fivefold (C5) symmetry templates and linkers. This engine leads us to isolate six new nanoscale cluster compounds: 1, {Mo10(C5)}; 2, {Mo14(C4)4(C5)2}; 3, {Mo60(C4)10}; 4, {Mo48(C4)6}; 5, {Mo34(C4)4}; 6, {Mo18(C4)9}; in only 200 automated experiments from a parameter space spanning ~5 million possible combinations.

  10. The properties of a gigantic jet reflected in a simultaneous sprite: Observations interpreted by a model

    NASA Astrophysics Data System (ADS)

    Neubert, T.; Chanrion, O.; Arnone, E.; Zanotti, F.; Cummer, S.; Li, J.; Füllekrug, M.; Soula, S.; van der Velde, O.

    2011-12-01

    Thunderstorm clouds may discharge directly to the ionosphere in spectacular luminous jets - the largest electric discharges of our planet. The properties of these “giants,” such as their polarity, conductivity, and currents, have been predicted by models, but are poorly characterized by measurements. A recent observation of a giant, fortuitously illuminated by an unusual sprite discharge in the mesosphere, allows us to study their electric properties and effects on the atmosphere-ionosphere. We show from a first-principles model of the combined giant and sprite event that the observations are consistent with the nature of the giant being a leader in the stratosphere of line charge density ˜0.8 mCm-1 and of multiple streamers in the mesosphere. It is further shown that the giant modifies the free electron content of the lower ionosphere because of electric field-driven ionization, electron attachment and detachment processes. This is the first time that sprites are used for sounding the properties of the mesosphere. The results presented here will allow evaluation of theories for jet and gigantic jets and of their influence on the atmosphere and ionosphere.

  11. A gigantic new dinosaur from Argentina and the evolution of the sauropod hind foot.

    PubMed

    González Riga, Bernardo J; Lamanna, Matthew C; Ortiz David, Leonardo D; Calvo, Jorge O; Coria, Juan P

    2016-01-01

    Titanosauria is an exceptionally diverse, globally-distributed clade of sauropod dinosaurs that includes the largest known land animals. Knowledge of titanosaurian pedal structure is critical to understanding the stance and locomotion of these enormous herbivores and, by extension, gigantic terrestrial vertebrates as a whole. However, completely preserved pedes are extremely rare among Titanosauria, especially as regards the truly giant members of the group. Here we describe Notocolossus gonzalezparejasi gen. et sp. nov. from the Upper Cretaceous of Mendoza Province, Argentina. With a powerfully-constructed humerus 1.76 m in length, Notocolossus is one of the largest known dinosaurs. Furthermore, the complete pes of the new taxon exhibits a strikingly compact, homogeneous metatarsus--seemingly adapted for bearing extraordinary weight--and truncated unguals, morphologies that are otherwise unknown in Sauropoda. The pes underwent a near-progressive reduction in the number of phalanges along the line to derived titanosaurs, eventually resulting in the reduced hind foot of these sauropods. PMID:26777391

  12. Change in the immunophenotype of a somatotroph adenoma resulting in gigantism

    PubMed Central

    Thawani, Jayesh P.; Bailey, Robert L.; Burns, Carrie M.; Lee, John Y. K.

    2014-01-01

    Background: Examining the pathologic progression of a pituitary adenoma from the point of a prepubescent child to an adult with gigantism affords us an opportunity to consider why patients may develop secretory or functioning tumors and raises questions about whether therapeutic interventions and surveillance strategies could be made to avoid irreversible phenotypic changes. Case Description: A patient underwent a sublabial transsphenoidal resection for a clinically non-functioning macroadenoma in 1999. He underwent radiation treatment and was transiently given growth hormone (GH) supplementation as an adolescent. His growth rapidly traversed several percentiles and he was found to have elevated GH levels. The patient became symptomatic and was taken for a second neurosurgical procedure. Pathology and immunohistochemical staining demonstrated a significantly higher proportion of somatotroph cells and dense granularity; he was diagnosed with a functional somatotroph adenoma. Conclusions: While it is likely that the described observations reflect the manifestations of a functional somatotroph adenoma in development, it is possible that pubertal growth, GH supplementation, its removal, or radiation therapy contributed to the described endocrine and pathologic changes. PMID:25396071

  13. A gigantic new dinosaur from Argentina and the evolution of the sauropod hind foot

    PubMed Central

    González Riga, Bernardo J.; Lamanna, Matthew C.; Ortiz David, Leonardo D.; Calvo, Jorge O.; Coria, Juan P.

    2016-01-01

    Titanosauria is an exceptionally diverse, globally-distributed clade of sauropod dinosaurs that includes the largest known land animals. Knowledge of titanosaurian pedal structure is critical to understanding the stance and locomotion of these enormous herbivores and, by extension, gigantic terrestrial vertebrates as a whole. However, completely preserved pedes are extremely rare among Titanosauria, especially as regards the truly giant members of the group. Here we describe Notocolossus gonzalezparejasi gen. et sp. nov. from the Upper Cretaceous of Mendoza Province, Argentina. With a powerfully-constructed humerus 1.76 m in length, Notocolossus is one of the largest known dinosaurs. Furthermore, the complete pes of the new taxon exhibits a strikingly compact, homogeneous metatarsus—seemingly adapted for bearing extraordinary weight—and truncated unguals, morphologies that are otherwise unknown in Sauropoda. The pes underwent a near-progressive reduction in the number of phalanges along the line to derived titanosaurs, eventually resulting in the reduced hind foot of these sauropods. PMID:26777391

  14. A Thermodynamic, kinematic and microphysical analysis of a jet and gigantic jet-producing Florida thunderstorm

    NASA Astrophysics Data System (ADS)

    Lazarus, S. M.; Splitt, M. E.; Brownlee, James; Spiva, Nicholas; Liu, Ningyu

    2015-08-01

    This paper presents a meteorological analysis of a storm that produced two jets, four gigantic jets (GJ), and a starter, which were observed by two radars as well as the Kennedy Space Center 4-Dimensional Lightning Surveillance System on 3 August 2013 in Central Florida. The work is the first application of dual polarization data to a jet-producing storm and is the fifth case related to a tropical disturbance. The storm environment is consistent with the moist tropical paradigm that characterizes about three quarters of the surface and aircraft observed jet and GJ events. The most unstable (MU) convective available potential energy is not unusual for Florida summer convection and is below the climatological mean for these events. An unusual speed shear layer is located near the storm equilibrium level (EL) and the storm exhibits a tilted structure with CGs displaced upshear. The turbulence, as measured by the eddy dissipation rate, is extreme near the storm top during the event window, consistent with the GJ mixing hypothesis. The individual events are collocated with, and track along, the center axis of the divergent outflow at the EL and occur within the region of the coldest GOES IR temperatures—placing the events within the overshoot. The dual polarization data indicate a deep graupel column, extending above the mixed phase layer, to a 13 km altitude.

  15. Lower limb gigantism, lymphedema, and painful varicosities following a thigh vascular access graft.

    PubMed

    Thompson, Michael; Mathuram Thiyagarajan, Umasankar; Akoh, Jacob A

    2014-07-01

    Prosthetic arteriovenous grafts (AVGs) are associated with greater morbidity than autogenous arteriovenous fistulas (AVFs), but their use is indicated when AVF formation is not possible. This report adds to the literature a case of lower limb gigantism, painful varicosities, and lymphedema following long-term use of AVG in the upper thigh. The patient's past medical history included renal transplantation on the same side well before the AVG was inserted and right leg deep vein thrombosis. Suspicion of AVG thrombosis was excluded by Doppler ultrasound, which demonstrated an access flow of 1700 mL/min. A computed tomography (CT) scan of the abdomen and pelvis did not identify the cause of her symptoms. Whereas functional incompetence of the iliac vein valve might be responsible for the varicosities, the extent of hypertrophy in this case raises the suspicion of lymphatic blockage possibly secondary to groin dissection undertaken at the time of graft insertion, in addition to the previous dissection at the time of transplantation. This case highlights the need for minimal groin dissection during AVG insertion, particularly in patients with a history of previous abdominopelvic surgery.

  16. A predatory bivalved euarthropod from the Cambrian (Stage 3) Xiaoshiba Lagerstätte, South China

    PubMed Central

    Yang, Jie; Ortega-Hernández, Javier; Lan, Tian; Hou, Jin-bo; Zhang, Xi-guang

    2016-01-01

    Bivalved euarthropods represent a conspicuous component of exceptionally-preserved fossil biotas throughout the Lower Palaeozoic. However, most of these taxa are known from isolated valves, and thus there is a limited understanding of their morphological organization and palaeoecology in the context of early animal-dominated communities. The bivalved euarthropod Clypecaris serrata sp. nov., recovered from the Cambrian (Stage 3) Hongjingshao Formation in Kunming, southern China, is characterized by having a robust first pair of raptorial appendages that bear well-developed ventral-facing spines, paired dorsal spines on the trunk, and posteriorly oriented serrations on the anteroventral margins of both valves. The raptorial limbs of C. serrata were adapted for grasping prey employing a descending stroke for transporting it close the mouth, whereas the backwards-facing marginal serrations of the bivalved carapace may have helped to secure the food items during feeding. The new taxon offers novel insights on the morphology of the enigmatic genus Clypecaris, and indicates that the possession of paired dorsal spines is a diagnostic trait of the Family Clypecarididae within upper stem-group Euarthropoda. C. serrata evinces functional adaptations for an active predatory lifestyle within the context of Cambrian bivalved euarthropods, and contributes towards the better understanding of feeding diversity in early ecosystems. PMID:27283406

  17. Draft Genome Sequence of the Emerging Bivalve Pathogen Vibrio tubiashii subsp. europaeus.

    PubMed

    Spinard, Edward J; Dubert, Javier; Nelson, David R; Gomez-Chiarri, Marta; Barja, Juan L

    2016-07-28

    Vibrio tubiashii subsp. europaeus is a bivalve pathogen isolated during episodes of mortality affecting larval cultures in different shellfish hatcheries. Here, we announce the draft genome sequence of the type strain PP-638 and describe potential virulence factors, which may provide insight into the mechanism of pathogenicity.

  18. Filter-feeding bivalves can remove avian influenza viruses from water and reduce infectivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Avian influenza (AI) viruses are transmitted within wild aquatic bird populations through an indirect fecal-oral route involving fecal-contaminated water. In this study, the influence of filter-feeding bivalves, Corbicula fluminea, on the infectivity of AI virus in water was examined. A single cla...

  19. Characterization of the endosymbiont of a deep-sea bivalve, Calyptogena soyoae.

    PubMed Central

    Kim, Y W; Yasuda, M; Yamagishi, A; Oshima, T; Ohta, S

    1995-01-01

    We have purified DNA from gill tissue of a marine bivalve, Calyptogena soyoae, collected from the deep-sea cold seep communities in Sagami Bay, Japan. An rRNA gene was amplified, cloned, and sequenced. In situ hybridization revealed that the sequence is that of a bacterial endosymbiont within the gill of C. soyoae. PMID:7574622

  20. Draft Genome Sequence of the Emerging Bivalve Pathogen Vibrio tubiashii subsp. europaeus

    PubMed Central

    Spinard, Edward J.; Dubert, Javier; Gomez-Chiarri, Marta; Barja, Juan L.

    2016-01-01

    Vibrio tubiashii subsp. europaeus is a bivalve pathogen isolated during episodes of mortality affecting larval cultures in different shellfish hatcheries. Here, we announce the draft genome sequence of the type strain PP-638 and describe potential virulence factors, which may provide insight into the mechanism of pathogenicity. PMID:27469949

  1. Consumption of freshwater bivalves by muskrats in the Green River, Kentucky

    USGS Publications Warehouse

    Hersey, Kimberly Asmus; Clark, Joseph D.; Layzer, James B.

    2013-01-01

    Muskrats (Ondatra zibethicus) are known to prey on freshwater bivalves (mussels and clams) and can negatively impact imperiled mussel species. However, factors that influence muskrat predation on bivalves are poorly understood. We evaluated the feeding ecology of muskrats in the Green River, Kentucky, by using stable isotope analysis of muskrat hair samples and by monitoring bivalve shell deposition at muskrat middens. Bayesian mixing-model analysis of stable isotope δ15N and δ13C ratios revealed that the median muskrat biomass derived from bivalves was 51.4% (5th and 95th percentiles were 39.1 to 63.4%, respectively), a much higher dietary proportion than previously reported. Shell depositions by muskrats at middens decreased with the availability of seasonal emergent vegetation, suggesting that the consumption of animal matter is in response to a scarcity of plant foods, perhaps exacerbated by the altered flow regimes on the Green River. Our results add to the growing body of evidence that muskrats have the potential to impact mussel population growth and recovery in some environments.

  2. DETERMINATION OF LETHAL DISSOLVED OXYGEN LEVELS FOR SELECTED MARINE AND ESTUARINE FISHES, CRUSTACEANS AND A BIVALVE

    EPA Science Inventory

    The objective of this study was to provide a database of the incipient lethal concentrations for reduced dissolved oxygen (DO) for selected marine and estuarine species including 12 species of fish, 9 crustaceans, and 1 bivalve. All species occur in the Virginian Province, USA, w...

  3. Shell growth and environmental control of methanophyllic Thyasirid bivalves from Svalbard cold seeps

    NASA Astrophysics Data System (ADS)

    Carroll, Michael; Åström, Emmelie; Ambrose, William; Locke, William; Oliver, Graham; Hong, Wei-Li; Carroll, JoLynn

    2016-04-01

    The analysis of molluscan shell material (sclerochronology) can provide information about an organism's age, growth history, and environmental conditions during its lifetime. Bivalve molluscs are common members of hydrothermal vents and methane cold seeps communities where, supported by chemosynthetic symbionts, they can reach high density and biomass. But little is known about methane-associated bivalve populations inhabiting high-Arctic cold seeps, and sclerochronological analysis of methane-influenced bivalves is rare. We measured growth rates and elemental and isotopic shell signatures in a newly discovered species of bivalve (Thyasiridae) from cold seeps at 350-390m depth southwest of Svalbard. First discovered in 2014, recently described shells of Thyasira capitanea sp.nov. were found at 2 independent seep systems in Storfjordrenna. Mean shell carbon isotopic ratios from inorganic δ13C (mean = -4.8‰) and organic δ13C (mean = -26.9‰) fractions clearly indicate a methane influenced habitat and food source for these organisms. Shell mineral ratios (Li/Ca, Mg/Ca, Mn/Ca, Fe/Ca, Sr/Ca, Ba/Ca, Pb/Ca) sampled along the axis of growth with laser-ablated ICP-MS exhibit variability through time and between sites, suggesting that concentrations of these elements that may be affected by methane emissions. The mineralogical data also elucidates the internal pattern of shell deposition and growth checks, and combined with the isotopic and growth rate data, enables us to interpret the temporal history of methane release from these locations.

  4. Cadmium-induced changes in trace element bioaccumulation and proteomics perspective in four marine bivalves.

    PubMed

    Liu, Fengjie; Wang, Da-Zhi; Wang, Wen-Xiong

    2012-06-01

    Bivalves are employed widely as biomonitors of metal pollution and proteomics has increasingly been applied to solve ecotoxicological issues. This study aimed to investigate the effects of Cd exposure on the bioaccumulation of other trace elements and reveal the molecular mechanisms using proteomics technologies. The results showed that Cd exposure resulted in remarkable changes in body concentrations of Zn, Cu, Ag, Co, Ni, Pb, and Se in four marine bivalves (scallop Chlamys nobilis, clam Ruditapes philippinarum, mussel Perna viridis, and oyster Saccostrea cucullata). Generally, the bivalves exposed to higher Cd concentration accumulated higher concentrations of Zn, Cu, and Se, but a lower concentration of Co. The accumulation of Ag, Ni, and Pb was specific for different species. The data strongly suggest that the influences of one metal exposure on the bioaccumulation of other metals/metalloids need to be considered in interpreting body concentrations of the elements in the biomonitors. Cd exposure had little effect on bivalve proteomes, and the identified proteins were insufficient to explain the observed disruption of trace element metabolism. However, protein expression signatures composed of the altered proteins could distinguish the clams and the mussels with different body Cd levels. The strong up-regulation of galectin in Cd-exposed oysters indicated the protein as a novel biomarker in environmental monitoring.

  5. Estimation of density-dependent mortality of juvenile bivalves in the Wadden Sea.

    PubMed

    Andresen, Henrike; Strasser, Matthias; van der Meer, Jaap

    2014-01-01

    We investigated density-dependent mortality within the early months of life of the bivalves Macoma balthica (Baltic tellin) and Cerastoderma edule (common cockle) in the Wadden Sea. Mortality is thought to be density-dependent in juvenile bivalves, because there is no proportional relationship between the size of the reproductive adult stocks and the numbers of recruits for both species. It is not known however, when exactly density dependence in the pre-recruitment phase occurs and how prevalent it is. The magnitude of recruitment determines year class strength in bivalves. Thus, understanding pre-recruit mortality will improve the understanding of population dynamics. We analyzed count data from three years of temporal sampling during the first months after bivalve settlement at ten transects in the Sylt-Rømø-Bay in the northern German Wadden Sea. Analyses of density dependence are sensitive to bias through measurement error. Measurement error was estimated by bootstrapping, and residual deviances were adjusted by adding process error. With simulations the effect of these two types of error on the estimate of the density-dependent mortality coefficient was investigated. In three out of eight time intervals density dependence was detected for M. balthica, and in zero out of six time intervals for C. edule. Biological or environmental stochastic processes dominated over density dependence at the investigated scale.

  6. Forever competent: deep-sea bivalves are colonized by their chemosynthetic symbionts throughout their lifetime.

    PubMed

    Wentrup, Cecilia; Wendeberg, Annelie; Schimak, Mario; Borowski, Christian; Dubilier, Nicole

    2014-12-01

    Symbiotic bivalves at hydrothermal vents and cold seeps host chemosynthetic bacteria intracellularly in gill cells. In bivalves, the gills grow continuously throughout their lifetime by forming new filaments. We examined how newly developed gill tissues are colonized in bivalves with horizontal and vertical symbiont transmission (Bathymodiolus mussels versus a vesicoymid clam) using fluorescence in situ hybridization and transmission electron microscopy. Symbiont colonization was similar in mussels and clams and was independent of the transmission modes. Symbionts were absent in the growth zones of the gills, indicating that symbionts colonize newly formed gill filaments de novo after they are formed and that gill colonization is a continuous process throughout the host's lifetime. Symbiont abundance and distribution suggested that colonization is shaped by the developmental stage of host cells. Self-infection, in which new gill cells are colonized by symbionts from ontogenetically older gill tissues, may also play a role. In mussels, symbiont infection led to changes in gill cell structure similar to those described from other epithelial cells infected by intracellular pathogens, such as the loss of microvilli. A better understanding of the factors that affect symbiont colonization of bivalve gills could provide new insights into interactions between intracellular bacteria and epithelial tissues.

  7. Pattern and process of diversification in an ecologically diverse epifaunal bivalve group Pterioidea (Pteriomorphia, Bivalvia).

    PubMed

    Tsubaki, Remi; Kameda, Yuichi; Kato, Makoto

    2011-01-01

    The pterioid bivalves (superfamily Pterioidea) are epifaunal filter feeders that attach to various substrata, including rocks, corals, gorgonians, and sponges. An intriguing question is how different substratum types have affected the diversification of pterioid bivalves. To elucidate the evolutionary pathway of Pterioidea, we conducted a phylogenetic analysis of 49 individuals belonging to 18 pterioid and 5 outgroup species using 18S and 28S ribosomal RNA genes. The results supported the monophyly of superfamily Pterioidea and recovered three major clades within Pterioidea: Malleus, Pteria and Electroma (Pterelectroma) zebra and the rest. This result contradicts the current circumscription of the pterioid families, Pteriidae, Malleidae, and Isognomonidae, and suggests that hinge morphology, which has long been used as a diagnostic character, does not reflect phylogenetic relationships. The monophyly of most genera, however, was confirmed. Mapping substrata types on the phylogenetic tree indicated that the ancestors of pterioid bivalves were epifaunal on rocks, and that epizoic life on sessile cnidarians had a single origin. Although we could not ascertain whether endozoic life in sponges evolved once or twice, our results suggest that colonization of biotic substrata resulted in diversification and morphological and ecological adaptation to epi-/endozoic life. We estimated that the genus Pteria has diversified since the late Cretaceous in response to gorgonian diversification. These results emphasize the importance of substratum shifts in speciation and diversification of pterioid bivalves.

  8. Dynamic Energy Budget model parameter estimation for the bivalve Mytilus californianus: Application of the covariation method

    NASA Astrophysics Data System (ADS)

    Matzelle, A.; Montalto, V.; Sarà, G.; Zippay, M.; Helmuth, B.

    2014-11-01

    Dynamic Energy Budget (DEB) models serve as a powerful tool for describing the flow of energy through organisms from assimilation of food to utilization for maintenance, growth and reproduction. The DEB theory has been successfully applied to several bivalve species to compare bioenergetic and physiological strategies for the utilization of energy. In particular, mussels within the Mytilus edulis complex (M. edulis, M. galloprovincialis, and M. trossulus) have been the focus of many studies due to their economic and ecological importance, and their worldwide distribution. However, DEB parameter values have never been estimated for Mytilus californianus, a species that is an ecological dominant on rocky intertidal shores on the west coast of North America and which likely varies considerably from mussels in the M. edulis complex in its physiology. We estimated a set of DEB parameters for M. californianus using the covariation method estimation procedure and compared these to parameter values from other bivalve species. Model parameters were used to compare sensitivity to environmental variability among species, as a first examination of how strategies for physiologically contending with environmental change by M. californianus may differ from those of other bivalves. Results suggest that based on the parameter set obtained, M. californianus has favorable energetic strategies enabling it to contend with a range of environmental conditions. For instance, the allocation fraction of reserve to soma (κ) is among the highest of any bivalves, which is consistent with the observation that this species can survive over a wide range of environmental conditions, including prolonged periods of starvation.

  9. EMBATTLED BIVALVES: BIOGEOGRAPHIC DISTRIBUTIONS AND ABUNDANCES FROM THE BEAUFORT SEA TO THE GULF OF CALIFORNIA

    EPA Science Inventory

    As part of an EPA/USGS project to predict the relative vulnerability of near-coastal species to climate change, we have synthesized in a web-based tool, the Coastal Biogeographic Risk Analysis Tool (CBRAT), the biogeographic distributions and abundances of bivalves, found in dept...

  10. Estimation of density-dependent mortality of juvenile bivalves in the Wadden Sea.

    PubMed

    Andresen, Henrike; Strasser, Matthias; van der Meer, Jaap

    2014-01-01

    We investigated density-dependent mortality within the early months of life of the bivalves Macoma balthica (Baltic tellin) and Cerastoderma edule (common cockle) in the Wadden Sea. Mortality is thought to be density-dependent in juvenile bivalves, because there is no proportional relationship between the size of the reproductive adult stocks and the numbers of recruits for both species. It is not known however, when exactly density dependence in the pre-recruitment phase occurs and how prevalent it is. The magnitude of recruitment determines year class strength in bivalves. Thus, understanding pre-recruit mortality will improve the understanding of population dynamics. We analyzed count data from three years of temporal sampling during the first months after bivalve settlement at ten transects in the Sylt-Rømø-Bay in the northern German Wadden Sea. Analyses of density dependence are sensitive to bias through measurement error. Measurement error was estimated by bootstrapping, and residual deviances were adjusted by adding process error. With simulations the effect of these two types of error on the estimate of the density-dependent mortality coefficient was investigated. In three out of eight time intervals density dependence was detected for M. balthica, and in zero out of six time intervals for C. edule. Biological or environmental stochastic processes dominated over density dependence at the investigated scale. PMID:25105293

  11. Estimating the distribution of harvested estuarine bivalves with natural-history-based habitat suitability models

    EPA Science Inventory

    Habitat suitability models are useful to forecast how environmental change may affect the abundance or distribution of species of concern. In the case of harvested bivalves, those models may be used to estimate the vulnerability of this valued ecosystem good to natural or human-...

  12. BIVALVE BIOGEOGRAPHIC DISTRIBUTIONS, ABUNDANCES, AND CLIMATE VULNERABILITY FROM THE BEAUFORT SEA TO THE GULF OF CALIFORNIA

    EPA Science Inventory

    As part of an U.S. EPA/USGS project to predict the relative vulnerability of near-coastal species to climate change along the Pacific Coast, we have synthesized the biogeographic distributions and abundances of bivalves found in depths <200 m. We have included the twelve &ldqu...

  13. Freshwater bivalve mollusca (unionidae, sphaeriidae, corbiculidae) of the Savannah River Plant, South Carolina

    SciTech Connect

    Britton, J.C.; Fuller, S.L.H.

    1980-11-01

    A guide to freshwater bivalve molluscs found at the Savannah River Plant is presented. A dichotomous taxonomic key is provided to common forms and to unreported species whose geographic distributions include nearby localities. Discussions of ecology, life history, larval hosts, and other pertinent information is provided. (ACR)

  14. Burrowing criteria and burrowing mode adjustment in bivalves to varying geoenvironmental conditions in intertidal flats and beaches.

    PubMed

    Sassa, Shinji; Watabe, Yoichi; Yang, Soonbo; Kuwae, Tomohiro

    2011-01-01

    The response of bivalves to their abiotic environment has been widely studied in relation to hydroenvironmental conditions, sediment types and sediment grain sizes. However, the possible role of varying geoenvironmental conditions in their habitats remains poorly understood. Here, we show that the hardness of the surficial intertidal sediments varies by a factor of 20-50 due to suction development and suction-induced void state changes in the essentially saturated states of intertidal flats and beaches. We investigated the response of two species of bivalves, Ruditapes philippinarum and Donax semigranosus, in the laboratory by simulating such prevailing geoenvironmental conditions in the field. The experimental results demonstrate that the bivalve responses depended strongly on the varying geoenvironmental conditions. Notably, both bivalves consistently shifted their burrowing modes, reducing the burrowing angle and burial depth, in response to increasing hardness, to compensate for the excessive energy required for burrowing, as explained by a proposed conceptual model. This burrowing mode adjustment was accompanied by two burrowing criteria below or above which the bivalves accomplished vertical burrowing or failed to burrow, respectively. The suitable and fatal conditions differed markedly with species and shell lengths. The acute sensitivities of the observed bivalve responses to geoenvironmental changes revealed two distinctive mechanisms accounting for the adult-juvenile spatial distributions of Ruditapes philippinarum and the behavioral adaptation to a rapidly changing geoenvironment of Donax semigranosus. The present results may provide a rational basis by which to understand the ensuing, and to predict future, bivalve responses to geoenvironmental changes in intertidal zones.

  15. Larval supply of predator and prey: temporal mismatch between crabs and bivalves after a severe winter in the Wadden Sea

    NASA Astrophysics Data System (ADS)

    Strasser, Matthias; Günther, Carmen-Pia

    2001-08-01

    Enhanced bivalve recruitment after severe winters is a well-known phenomenon in the coastal North Sea. By comparing the bivalve larval abundances in the northern Wadden Sea after a severe (1995/96), a moderate (1996/97) and a mild (1997/98) winter we found no evidence for the hypothesis that high bivalve recruitment after severe winters is caused by enhanced larval supply. Total and peak abundances of all bivalve larvae as well as of each of four separate species Ensis americanus, Mytilus edulis, Cerastoderma edule and Mya arenaria were three to six times lower after the severe than after the mild winter. In Macoma balthica total and peak abundances after the severe winter were only slightly higher than after the moderate winter. The larvae of the epibenthic predator Carcinus maenas appeared in lower numbers and six to eight weeks later after the severe winter than after the moderate and the mild winter. Since the bivalve larvae appeared without, or with less, delay after the severe winter, there was a temporal mismatch between Carcinus and the bivalves, supporting the hypothesis that reduced epibenthic predation is an important factor in high bivalve recruitment after severe winters.

  16. Cellular physiological assessment of bivalves after chronic exposure to spilled Exxon Valdez crude oil using a novel molecular diagnostic biotechnology.

    PubMed

    Downs, Craig A; Shigenaka, Gary; Fauth, John E; Robinson, Charles E; Huang, Arnold

    2002-07-01

    The objective of this study was to determine the cellular physiological status of the bivalves Mya arenaria and Mytilus trossulus in an area experiencing a 10-yr chronic exposure of spilled Exxon Valdez crude oil in Prince William Sound. Bivalves were collected from well-characterized oiled and unoiled sites. We used a novel biotechnology (Environmental Cellular Diagnostic System) to determine (i) if bivalves were physiologically stressed, (ii) the nature of the altered physiological state, and (iii) whether the bivalves were responding to an exposure of polyaromatic hydrocarbons (PAH). Molecular diagnostic analysis indicated that bivalves at the oiled site were experiencing both oxidative and xenobiotic stress, resulting in increased protein turnover and chaperone activity. Bivalves from the impacted area were responding specifically to a PAH-xenobiotic exposure and accumulating protein-PAH adducts. Finally, species-specific responses were observed that could be related to the habitat preferences of each species. We conclude that bivalves inhabiting a site impacted by crude oil from the 1989 Exxon Valdez spill showed clear indications of cellular physiological stress. PMID:12144276

  17. Cellular physiological assessment of bivalves after chronic exposure to spilled Exxon Valdez crude oil using a novel molecular diagnostic biotechnology.

    PubMed

    Downs, Craig A; Shigenaka, Gary; Fauth, John E; Robinson, Charles E; Huang, Arnold

    2002-07-01

    The objective of this study was to determine the cellular physiological status of the bivalves Mya arenaria and Mytilus trossulus in an area experiencing a 10-yr chronic exposure of spilled Exxon Valdez crude oil in Prince William Sound. Bivalves were collected from well-characterized oiled and unoiled sites. We used a novel biotechnology (Environmental Cellular Diagnostic System) to determine (i) if bivalves were physiologically stressed, (ii) the nature of the altered physiological state, and (iii) whether the bivalves were responding to an exposure of polyaromatic hydrocarbons (PAH). Molecular diagnostic analysis indicated that bivalves at the oiled site were experiencing both oxidative and xenobiotic stress, resulting in increased protein turnover and chaperone activity. Bivalves from the impacted area were responding specifically to a PAH-xenobiotic exposure and accumulating protein-PAH adducts. Finally, species-specific responses were observed that could be related to the habitat preferences of each species. We conclude that bivalves inhabiting a site impacted by crude oil from the 1989 Exxon Valdez spill showed clear indications of cellular physiological stress.

  18. Depth-related gradients in community structure and relatedness of bivalves and isopods in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Brandt, Angelika; Linse, Katrin; Ellingsen, Kari E.; Somerfield, Paul J.

    2016-05-01

    Despite increased research over the last decade, diversity patterns in Antarctic deep-sea benthic taxa and their driving forces are only marginally known. Depth-related patterns of diversity and distribution of isopods and bivalves collected in the Atlantic sector of the Southern Ocean are analysed. The data, sampled by epibenthic sledge at 40 deep-sea stations from the upper continental slope to the hadal zone (774-6348 m) over a wide area of the Southern Ocean, comprises 619 species of isopods and 81 species of bivalves. There were more species of isopods than bivalves in all samples, and species per station varied from 2 to 85 for isopods and from 0 to 18 for bivalves. Most species were rare, with 72% of isopod species restricted to one or two stations, and 45% of bivalves. Among less-rare species bivalves tended to have wider distributions than isopods. The species richness of isopods varied with depth, showing a weak unimodal curve with a peak at 2000-4000 m, while the richness of bivalves did not. Multivariate analyses indicate that there are two main assemblages in the Southern Ocean, one shallow and one deep. These overlap over a large depth-range (2000-4000 m). Comparing analyses based on the Sørensen resemblance measure and Γ+ (incorporating relatedness among species) indicates that rare species tend to have other closely related species within the same depth band. Analysis of relatedness among species indicates that the taxonomic variety of bivalves tends to decline at depth, whereas that of isopods is maintained. This, it is speculated, may indicate that the available energy at depth is insufficient to maintain a range of bivalve life-history strategies.

  19. First respiration estimates of cold-seep vesicomyid bivalves from in situ total oxygen uptake measurements.

    PubMed

    Decker, Carole; Caprais, Jean-Claude; Khripounoff, Alexis; Olu, Karine

    2012-04-01

    Vesicomyid bivalves are one of the most abundant symbiont-bearing species inhabiting deep-sea reducing ecosystems. Nevertheless, except for the hydrothermal vent clam Calyptogena magnifica, their metabolic rates have not been documented, and only assessed with ex situ experiments. In this study, gathering benthic chamber measurements and biomass estimation, we give the first in situ assessment of the respiration rate of these bivalves. The giant pockmark Regab, located at 3160m depth along the Congo-Angola margin, is a cold-seep site characterised by dense assemblages of two species of vesicomyids: Christineconcha regab and Laubiericoncha chuni with high dominance of C. regab. Two sites with dense aggregates of vesicomyids were selected to measure total oxygen uptake (TOU), and methane fluxes using IFREMER's benthic chamber CALMAR deployed by the ROV Quest 4000 (MARUM). Photographs were taken and bivalves were sampled using blade corers to estimate density and biomass. Total oxygen uptake was higher at Site 2 compared to Site 1 (respectively 492 mmol.m(-2).d(-1) and 332 mmol.m(-2).d(-1)). However, given vesicomyid densities and biomass, mean oxygen consumption rates were similar at both sites (1.9 to 2.5 μmol.g total dry mass(-1).h(-1) at the Site 1 and 1.8 to 2.3 μmol.g total dry mass(-1).h(-1) at Site 2). These respiration rates are higher than published ex situ estimates for cold-seep or hydrothermal vent bivalves. Although methane fluxes at the base of sulphide production were clearly higher at Site 2 (14.6 mmol.m(-2).d(-1)) than at Site 1 (0.3 mmol.m(-2).d(-1)), they do not seem to influence the respiration rates of these bivalves associated to sulphide-oxidizing symbionts. PMID:22578572

  20. First respiration estimates of cold-seep vesicomyid bivalves from in situ total oxygen uptake measurements.

    PubMed

    Decker, Carole; Caprais, Jean-Claude; Khripounoff, Alexis; Olu, Karine

    2012-04-01

    Vesicomyid bivalves are one of the most abundant symbiont-bearing species inhabiting deep-sea reducing ecosystems. Nevertheless, except for the hydrothermal vent clam Calyptogena magnifica, their metabolic rates have not been documented, and only assessed with ex situ experiments. In this study, gathering benthic chamber measurements and biomass estimation, we give the first in situ assessment of the respiration rate of these bivalves. The giant pockmark Regab, located at 3160m depth along the Congo-Angola margin, is a cold-seep site characterised by dense assemblages of two species of vesicomyids: Christineconcha regab and Laubiericoncha chuni with high dominance of C. regab. Two sites with dense aggregates of vesicomyids were selected to measure total oxygen uptake (TOU), and methane fluxes using IFREMER's benthic chamber CALMAR deployed by the ROV Quest 4000 (MARUM). Photographs were taken and bivalves were sampled using blade corers to estimate density and biomass. Total oxygen uptake was higher at Site 2 compared to Site 1 (respectively 492 mmol.m(-2).d(-1) and 332 mmol.m(-2).d(-1)). However, given vesicomyid densities and biomass, mean oxygen consumption rates were similar at both sites (1.9 to 2.5 μmol.g total dry mass(-1).h(-1) at the Site 1 and 1.8 to 2.3 μmol.g total dry mass(-1).h(-1) at Site 2). These respiration rates are higher than published ex situ estimates for cold-seep or hydrothermal vent bivalves. Although methane fluxes at the base of sulphide production were clearly higher at Site 2 (14.6 mmol.m(-2).d(-1)) than at Site 1 (0.3 mmol.m(-2).d(-1)), they do not seem to influence the respiration rates of these bivalves associated to sulphide-oxidizing symbionts.

  1. The use of bivalves as rapid, real-time indicators of aquatic pollution

    SciTech Connect

    Markich, S.J.

    1995-12-31

    The ability of bivalves to filter large volumes of water on a daily basis, combined with the relatively high permeability of their cell membranes, make them valuable organisms to use in the contemporary detection of pollution. Bivalves are well known to respond to chemical contaminants by isolating their soft tissues from the aquatic medium by valve closure. The sensory acuity (via specialized sensory regions including the osphradium) and associated repertoire of this behavioral response can be employed to assess subtle effects exerted by chemical contaminants, such as complex effluents, that may ultimately influence the survival of these organisms. As hazard assessment tools, behavioral studies reflect sublethal toxicity and often yield a highly sensitive estimate of the lowest observable effect concentration (LOEC). Moreover, valve movement behavior has been identified as one of the more sensitive biological early warning measures to a variety of aquatic contaminants, in comparison with those used in other aquatic animal phyla. Therefore, the valve movement behavior of both freshwater (Hyridella depressa, Velesunio angasi and V. ambiguus) and marine (Mytilus edulis) bivalves was continuously monitored, using an on-line computer based data acquisition system, during exposure to either trace metals (e.g. Cu, Cd, Mn and U) or complex effluents (ie treated sewage effluent and acid leachate derived from contaminated Sydney Harbour sediments), in the context of using the valve movement behavior of the bivalve species to indicate the biological significance of exposure to the above-mentioned pollutants. The results indicate that several components of the valve movement behavior of each bivalve provide quantifiable and ecologically interpretable sub-lethal endpoints for the rapid and sensitive evaluation of waters containing either complex effluents or elevated levels of trace metals.

  2. An overview of chemosynthetic symbioses in bivalves from the North Atlantic and Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Duperron, S.; Gaudron, S. M.; Rodrigues, C. F.; Cunha, M. R.; Decker, C.; Olu, K.

    2012-11-01

    Deep-sea bivalves found at hydrothermal vents, cold seeps and organic falls are sustained by chemosynthetic bacteria which ensure part or all of their carbon nutrition. These symbioses are of prime importance for the functioning of the ecosystems. Similar symbioses occur in other bivalve species living in shallow and coastal reduced habitats worldwide. In recent years, several deep-sea species have been investigated from continental margins around Europe, West Africa, East America, the Gulf of Mexico, and from hydrothermal vents on the Mid-Atlantic Ridge. In parallel, numerous more easily accessible shallow marine species were studied. We here provide a summary of the current knowledge available on chemosymbiotic bivalves in the area ranging west-to-east from the Gulf of Mexico to Marmara Sea, and north-to-south from the Arctic to the Gulf of Guinea. Characteristics of symbioses in 51 species from the area are summarized for each of the five bivalve families documented to harbor chemosynthetic symbionts (Mytilidae, Vesicomyidae, Solemyidae, Thyasiridae and Lucinidae), and compared among families with special emphasis on ecology, life cycle, and connectivity. Chemosynthetic symbioses are a major adaptation to ecosystems and habitats exposed to reducing conditions, yet relatively little is known regarding their diversity and functioning apart from a few "model species" on which effort has focused over the last 30 yr. In the context of increasing concern about biodiversity and ecosystems, and increasing anthropogenic pressure on Oceans, we advocate for a better assessment of bivalve symbioses diversity in order to evaluate the capacities of these remarkable ecological and evolutionary units to withstand environmental change

  3. An overview of chemosynthetic symbioses in bivalves from the North Atlantic and Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Duperron, S.; Gaudron, S. M.; Rodrigues, C. F.; Cunha, M. R.; Decker, C.; Olu, K.

    2013-05-01

    Deep-sea bivalves found at hydrothermal vents, cold seeps and organic falls are sustained by chemosynthetic bacteria that ensure part or all of their carbon nutrition. These symbioses are of prime importance for the functioning of the ecosystems. Similar symbioses occur in other bivalve species living in shallow and coastal reduced habitats worldwide. In recent years, several deep-sea species have been investigated from continental margins around Europe, West Africa, eastern Americas, the Gulf of Mexico, and from hydrothermal vents on the Mid-Atlantic Ridge. In parallel, numerous, more easily accessible shallow marine species have been studied. Herein we provide a summary of the current knowledge available on chemosymbiotic bivalves in the area ranging west-to-east from the Gulf of Mexico to the Sea of Marmara, and north-to-south from the Arctic to the Gulf of Guinea. Characteristics of symbioses in 53 species from the area are summarized for each of the five bivalve families documented to harbor chemosynthetic symbionts (Mytilidae, Vesicomyidae, Solemyidae, Thyasiridae and Lucinidae). Comparisons are made between the families, with special emphasis on ecology, life cycle, and connectivity. Chemosynthetic symbioses are a major adaptation to ecosystems and habitats exposed to reducing conditions. However, relatively little is known regarding their diversity and functioning, apart from a few "model species" on which effort has focused over the last 30 yr. In the context of increasing concern about biodiversity and ecosystems, and increasing anthropogenic pressure on oceans, we advocate a better assessment of the diversity of bivalve symbioses in order to evaluate the capacities of these remarkable ecological and evolutionary units to withstand environmental change.

  4. Generally detected genes in comparative transcriptomics in bivalves: toward the identification of molecular markers of cellular stress response.

    PubMed

    Miao, Jingjing; Chi, Luping; Pan, Luqing; Song, Ying

    2015-01-01

    The specificity and representativeness of protein-coding genes identified by transcriptomics as biomarkers for environmental toxicological stress is crucial. We extracted the differential gene expression profile data from 49 published comparative transcriptomic studies of bivalves from January 2004 till November 2014 performed in 15 different bivalve species. Among the studies, 77 protein-coding genes were frequently detected when we use threefold of the average detection frequency as cut-off. Cellular organization and communication, protein and energy metabolism, stress response are the main functional classes of these proteins. We consider if these protein-coding genes represent common cellular stress responses of bivalves.

  5. Increase in tracheal investment with beetle size supports hypothesis of oxygen limitation on insect gigantism.

    PubMed

    Kaiser, Alexander; Klok, C Jaco; Socha, John J; Lee, Wah-Keat; Quinlan, Michael C; Harrison, Jon F

    2007-08-01

    Recent studies have suggested that Paleozoic hyperoxia enabled animal gigantism, and the subsequent hypoxia drove a reduction in animal size. This evolutionary hypothesis depends on the argument that gas exchange in many invertebrates and skin-breathing vertebrates becomes compromised at large sizes because of distance effects on diffusion. In contrast to vertebrates, which use respiratory and circulatory systems in series, gas exchange in insects is almost exclusively determined by the tracheal system, providing a particularly suitable model to investigate possible limitations of oxygen delivery on size. In this study, we used synchrotron x-ray phase-contrast imaging to visualize the tracheal system and quantify its dimensions in four species of darkling beetles varying in mass by 3 orders of magnitude. We document that, in striking contrast to the pattern observed in vertebrates, larger insects devote a greater fraction of their body to the respiratory system, as tracheal volume scaled with mass1.29. The trend is greatest in the legs; the cross-sectional area of the trachea penetrating the leg orifice scaled with mass1.02, whereas the cross-sectional area of the leg orifice scaled with mass0.77. These trends suggest the space available for tracheae within the leg may ultimately limit the maximum size of extant beetles. Because the size of the tracheal system can be reduced when oxygen supply is increased, hyperoxia, as occurred during late Carboniferous and early Permian, may have facilitated the evolution of giant insects by allowing limbs to reach larger sizes before the tracheal system became limited by spatial constraints.

  6. Optical and radio signatures of negative gigantic jets: Cases from Typhoon Lionrock (2010)

    NASA Astrophysics Data System (ADS)

    Huang, Sung-Ming; Hsu, Rue-Rou; Lee, Li-Jou; Su, Han-Tzong; Kuo, Cheng-Ling; Wu, Chun-Chieh; Chou, Jung-Kuang; Chang, Shu-Chun; Wu, Yen-Jung; Chen, Alfred B.

    2012-08-01

    On 31 August 2010, more than 100 transient luminous events were observed to occur over Typhoon Lionrock when it passed at ˜210 km to the southwest of the NCKU site in Taiwan. Among them, 14 negative gigantic jets (GJs) with clear recognizable morphologies and radio frequency signals are analyzed. These GJs are all found to have negative discharge polarity and thus are type I GJs. Morphologically, they are grouped into three forms: tree-like, carrot-like, and a new intermediate type called tree-carrot-like GJs. The ULF and ELF/VLF band signals of these events contain clear signatures associated with GJ development stages, including the initiating lightning, the leading jet, the fully developed jet, and the trailing jet. Though the radio waveform for each group of GJs always contains a fast descending pulse linked with the surge current upon the GJ-ionosphere contact, the detailed waveforms actually vary substantially. Cross analysis of the optical and radio frequency signals for these GJs indicates that a large surge current moment (CM) (>60 kA-km) appears to be essentially associated with the tree-like GJs. In contrast, the carrot-like and the tree-carrot-like GJs are both related to a surge CM less than 36 kA-km, and a continuing CM less than 27 kA-km further separates the carrot-like GJs from the tree-carrot-like GJs. Furthermore, on the peak CM versus charge moment change diagram for the initiating lightning, different groups of GJs seem to exhibit different trends. This feature suggests that the eventual forms of negative GJs may have been determined at the initiating lightning stage.

  7. New color images of sprites, halos and gigantic jets from the International Space Station

    NASA Astrophysics Data System (ADS)

    Yair, Y.; Rubanenko, L.; Mezuman, K.; Elhalel, G.; Pariente, M.; Glickman-Pariente, M.; Ziv, B.; Takahashi, Y.; Inoue, T.

    2012-12-01

    During July-August 2011, Expedition 28/29 JAXA astronaut Satoshi Furukawa conducted TLE observations from the International Space Station in conjunction with the "Cosmic Shore" program produced by NHK. An EMCCD normal video-rate color TV camera was used to conduct directed observations from the Earth-pointing Copula module. The target selection was based on the methodology developed for the MEIDEX sprite campaign on board the space shuttle Columbia in January 2003 (Ziv et al., 2004). We used the Aviation Weather Center (http://aviationweather.gov) daily significant weather forecast maps (SIGWX) to select regions with high probability for convective activity and thunderstorm such that they were within the camera FOV as deduced from the ISS trajectory and distance to the limb (2240 km). For increasing the chance for successful observations, only storms with predicted "Frequent Cb" and cloud tops above 45 Kft (~14 km) were selected. Additionally, we targeted tropical storms and hurricanes over the oceans. The observation geometry was pre-determined and uploaded daily to the ISS with pointing options to limb, oblique or nadir, based on the predicted location of the storm with regards to the ISS. The pointing angle was rotated in real-time according to visual eyesight by the astronaut. We present results of 10 confirmed TLEs: 8 sprites, 1 sprite halo and 1 gigantic jet, out of <2 hours of video. Sprites tend to appear in a single frame simultaneously with maximum lightning brightness. Unique images (a) from nadir of a sprite horizontally displaced form the lightning light and (b) from oblique view of a sprite halo, enable the calculation of dimensions and volumes occupied by these TLEs. Since time stamping on the ISS images was accurate within 1 s, matching with ELF and WWLLN data for the parent lightning location is limited. Nevertheless, the results prove that the ISS is an ideal platform for lightning and TLE observations, and careful operational procedures greatly

  8. Similarity Analysis of the Streamer Zone of Blue Jets and Gigantic Blue Jets

    NASA Astrophysics Data System (ADS)

    Gennady, M.; Popov, N. A.; Shneider, M.

    2015-12-01

    Multiple observations of Blue Jets (BJ) and Gigantic Blue Jets (GBJ) show that BJ emits a fan of streamers similar to a laboratory leader. Moreover, in the exponential atmosphere those long streamers grow preferentially upward, producing a narrow cone confined by the aperture angle. Petrov and Petrova [1999] and Pasko and George [2002] noticed that BJ are similar to the streamer zone of a leader (streamer corona) and conducted modeling studies based on the streamers fractal structure. Objective of this paper is to study the fractal dimension of the bunch of streamer channels emitted by BJ, at different altitude and under the varying reduced electric field. This similarity analysis has been done in three steps: First we described the dendritic structure of streamers in corona discharge applying the fractal theory by Popov [2002]. Then using this model and the data from existing laboratory experiments we obtained that the fractal dimension of the branching streamer channels D=2. We estimated next the packing factor of the streamers using the kinetic simulations that describe development of a group of streamers that propagate in a discharge gap while interact with each other. Finally the model was used to analyze some GBJ images available from the literature. The model output includes evaluation of the total number of streamer channels in the GBJs along with estimates of the aperture angle and of the average distance between the brunches. In addition the analysis allows us to obtain the mean streamer velocity for the studied GBJs and check the velocity against the observations. V.P. Pasko and J.J. George, J. Geophys. Res. 107, 1458, 2002 N.I. Petrov and G.N. Petrova, Tech Phys. Lett., 44, 472, 1999 N.A. Popov, Plasma Phys. Reports, 28, 615, 2002.

  9. Microbiological monitoring of bivalves from the Ria Formosa Lagoon (south coast of Portugal): a 20 years of sanitary survey.

    PubMed

    Almeida, Catarina; Soares, Florbela

    2012-02-01

    The microbiological pollution of coastal waters is a major problem, especially in shellfish areas. This article shows the faecal contamination in bivalves from the Ria Formosa Lagoon (south coast of Portugal) along 20 years (1990-2009). The highest values of Escherichia coli in bivalves were obtained during the 90s, related with the discharge of untreated wastewaters and agricultural runoff. In the 2000s contamination levels decreased, with 83% of the population already served by new or remodelled sewage treatment plants. The highest levels were found in bivalves close to the largest city, where punctual and diffuse contamination sources still exist. Bivalves from the less impacted site showed the lowest contamination, an area with more water renewal. Seasonally, the highest levels were in autumn and winter, due to the runoff of waters from rainfall. These were opposite to those in spring and summer, when the highest temperatures and salinity showed a bactericidal effect. PMID:22197556

  10. Multi-scale distribution and dynamics of bivalve larvae in a deep atoll lagoon (Ahe, French Polynesia).

    PubMed

    Thomas, Y; Garen, P; Bennett, A; Le Pennec, M; Clavier, J

    2012-01-01

    Bivalve larvae and hydrographic parameters were sampled over a range of spatio-temporal scales in a deep atoll lagoon. Bivalve larvae abundances were very high throughout the year: 18,550 m(-3) in average. Larvae were (i) concentrated at mid-depth with nocturnal ascent and diurnal descent, (ii) heterogeneously dispersed at the lagoon scale, (iii) subject to day-to-day variation in abundance and (iv) transferred between different parts of the lagoon providing evidence of intra-lagoonal connectivity. The primacy of physical factors was seen on large spatial scale with the diluting effect of water renewal and transfers by hydrodynamics. On smaller spatial scale, the primacy of biological processes was recognised, with larval swimming activity leading to dial vertical migration correlated with food concentration. Variations in larval abundance were driven by bivalve reproductive activity correlated with meteorological conditions (i.e. windy periods). Finally, relationship between bivalve larvae patterns and pearl oyster (Pinctada margaritifera) settlement structuring is discussed.

  11. New records and a new species of bivalve (Mollusca: Bivalvia) from Miocene hydrocarbon seep deposits, North Island, New Zealand.

    PubMed

    Saether, Kristian P; Jingeng, Sha; Little, Crispin T S; Campbell, Kathleen A

    2016-01-01

    Fourteen bivalve taxa belonging to 11 families are present in at least 13 early to middle Miocene hydrocarbon seep deposits in the East Coast Basin, North Island, New Zealand. Among these are at least three new species, one of which, Semeloidea (s. l.) bexhavenensis sp. nov. (Lasaeidae), is described here. New distribution data are recorded for bivalve species in the families Limidae, Propeamussiidae, Malleidae and Solemyidae. Additional morphological details of Gigantidas coseli (Mytilidae) and Pratulum quinarium (Cardiidae) are provided based upon previously unrecorded internal shell features. Palaeoecological analysis indicates that bivalves utilized a broad range of modes of life and niches within the New Zealand Miocene seep environment, and no more than ca. 30% of these bivalve species were likely to have been obligate to seeps. PMID:27615822

  12. Microbiological monitoring of bivalves from the Ria Formosa Lagoon (south coast of Portugal): a 20 years of sanitary survey.

    PubMed

    Almeida, Catarina; Soares, Florbela

    2012-02-01

    The microbiological pollution of coastal waters is a major problem, especially in shellfish areas. This article shows the faecal contamination in bivalves from the Ria Formosa Lagoon (south coast of Portugal) along 20 years (1990-2009). The highest values of Escherichia coli in bivalves were obtained during the 90s, related with the discharge of untreated wastewaters and agricultural runoff. In the 2000s contamination levels decreased, with 83% of the population already served by new or remodelled sewage treatment plants. The highest levels were found in bivalves close to the largest city, where punctual and diffuse contamination sources still exist. Bivalves from the less impacted site showed the lowest contamination, an area with more water renewal. Seasonally, the highest levels were in autumn and winter, due to the runoff of waters from rainfall. These were opposite to those in spring and summer, when the highest temperatures and salinity showed a bactericidal effect.

  13. New records and a new species of bivalve (Mollusca: Bivalvia) from Miocene hydrocarbon seep deposits, North Island, New Zealand.

    PubMed

    Saether, Kristian P; Jingeng, Sha; Little, Crispin T S; Campbell, Kathleen A

    2016-01-01

    Fourteen bivalve taxa belonging to 11 families are present in at least 13 early to middle Miocene hydrocarbon seep deposits in the East Coast Basin, North Island, New Zealand. Among these are at least three new species, one of which, Semeloidea (s. l.) bexhavenensis sp. nov. (Lasaeidae), is described here. New distribution data are recorded for bivalve species in the families Limidae, Propeamussiidae, Malleidae and Solemyidae. Additional morphological details of Gigantidas coseli (Mytilidae) and Pratulum quinarium (Cardiidae) are provided based upon previously unrecorded internal shell features. Palaeoecological analysis indicates that bivalves utilized a broad range of modes of life and niches within the New Zealand Miocene seep environment, and no more than ca. 30% of these bivalve species were likely to have been obligate to seeps.

  14. Acromegaly and gigantism in the medical literature. Case descriptions in the era before and the early years after the initial publication of Pierre Marie (1886).

    PubMed

    de Herder, Wouter W

    2009-01-01

    In 1886 Pierre Marie used the term "acromegaly" for the first time and gave a full description of the characteristic clinical picture. However several others had already given clear clinical descriptions before him and sometimes had given the disease other names. After 1886, it gradually became clear that pituitary enlargement (caused by a pituitary adenoma) was the cause and not the consequence of acromegaly, as initially thought. Pituitary adenomas could be found in the great majority of cases. It also became clear that acromegaly and gigantism were the same disease but occurring at different stages of life and not different diseases as initially thought. At the end of the 19th and beginning of the 20th century most information was derived from case descriptions and post-mortem examinations of patients with acromegaly or (famous) patients with gigantism. The stage was set for further research into the pathogenesis, diagnosis and therapy of acromegaly and gigantism. PMID:18683056

  15. Gigantic solitary fibrous tumour of extra-peritoneal space. A case report and review of the literature.

    PubMed

    Guzel, Tomasz; Dąbrowski, Bohdan; Mazurkiewicz, Michał; Makiewicz, Marcin; Krasnoębski, Ireneusz W

    2014-07-01

    Solitary fibrous tumour (SFT) is a rare soft tissue tumour which belongs to fibroblastic/myofibroblastic group of tumours. The most often it appears in pleura, also in pericardium, internal organs, peritoneum and extraperitoenal space. SFT was first described as a new type of pleura's tumour by Klemperer and Rabin in 1931. The histogenesis of SFT's has been discussed for years suggesting its mesothelial origin. Recently, SFT has been classified as a mesenchymal fibroblastic tumour. We report a very rare case of 71-year old man suffering from gigantic solitary fibrous tumour of extraperitoneal space who underwent curative surgery in the Department of General, Gastroenterological and Oncologic Surgery in 2011.

  16. Trophic Dynamics of Filter Feeding Bivalves in the Yangtze Estuarine Intertidal Marsh: Stable Isotope and Fatty Acid Analyses.

    PubMed

    Wang, Sikai; Jin, Binsong; Qin, Haiming; Sheng, Qiang; Wu, Jihua

    2015-01-01

    Benthic bivalves are important links between primary production and consumers, and are essential intermediates in the flow of energy through estuarine systems. However, information on the diet of filter feeding bivalves in estuarine ecosystems is uncertain, as estuarine waters contain particulate matter from a range of sources and as bivalves are opportunistic feeders. We surveyed bivalves at different distances from the creek mouth at the Yangtze estuarine marsh in winter and summer, and analyzed trophic dynamics using stable isotope (SI) and fatty acid (FA) techniques. Different bivalve species had different spatial distributions in the estuary. Glauconome chinensis mainly occurred in marshes near the creek mouth, while Sinonovacula constricta preferred the creek. Differences were found in the diets of different species. S. constricta consumed more diatoms and bacteria than G. chinensis, while G. chinensis assimilated more macrophyte material. FA markers showed that plants contributed the most (38.86 ± 4.25%) to particular organic matter (POM) in summer, while diatoms contributed the most (12.68 ± 1.17%) during winter. Diatoms made the largest contribution to the diet of S. constricta in both summer (24.73 ± 0.44%) and winter (25.51 ± 0.59%), and plants contributed no more than 4%. This inconsistency indicates seasonal changes in food availability and the active feeding habits of the bivalve. Similar FA profiles for S. constricta indicated that the bivalve had a similar diet composition at different sites, while different δ13C results suggested the diet was derived from different carbon sources (C4 plant Spartina alterniflora and C3 plant Phragmites australis and Scirpus mariqueter) at different sites. Species-specific and temporal and/or spatial variability in bivalve feeding may affect their ecological functions in intertidal marshes, which should be considered in the study of food webs and material flows in estuarine ecosystems.

  17. Trophic Dynamics of Filter Feeding Bivalves in the Yangtze Estuarine Intertidal Marsh: Stable Isotope and Fatty Acid Analyses

    PubMed Central

    Wang, Sikai; Jin, Binsong; Qin, Haiming; Sheng, Qiang; Wu, Jihua

    2015-01-01

    Benthic bivalves are important links between primary production and consumers, and are essential intermediates in the flow of energy through estuarine systems. However, information on the diet of filter feeding bivalves in estuarine ecosystems is uncertain, as estuarine waters contain particulate matter from a range of sources and as bivalves are opportunistic feeders. We surveyed bivalves at different distances from the creek mouth at the Yangtze estuarine marsh in winter and summer, and analyzed trophic dynamics using stable isotope (SI) and fatty acid (FA) techniques. Different bivalve species had different spatial distributions in the estuary. Glauconome chinensis mainly occurred in marshes near the creek mouth, while Sinonovacula constricta preferred the creek. Differences were found in the diets of different species. S. constricta consumed more diatoms and bacteria than G. chinensis, while G. chinensis assimilated more macrophyte material. FA markers showed that plants contributed the most (38.86 ± 4.25%) to particular organic matter (POM) in summer, while diatoms contributed the most (12.68 ± 1.17%) during winter. Diatoms made the largest contribution to the diet of S. constricta in both summer (24.73 ± 0.44%) and winter (25.51 ± 0.59%), and plants contributed no more than 4%. This inconsistency indicates seasonal changes in food availability and the active feeding habits of the bivalve. Similar FA profiles for S. constricta indicated that the bivalve had a similar diet composition at different sites, while different δ13C results suggested the diet was derived from different carbon sources (C4 plant Spartina alterniflora and C3 plant Phragmites australis and Scirpus mariqueter) at different sites. Species-specific and temporal and/or spatial variability in bivalve feeding may affect their ecological functions in intertidal marshes, which should be considered in the study of food webs and material flows in estuarine ecosystems. PMID:26261984

  18. The known and unknown sources of reactive oxygen and nitrogen species in haemocytes of marine bivalve molluscs.

    PubMed

    Donaghy, Ludovic; Hong, Hyun-Ki; Jauzein, Cécile; Choi, Kwang-Sik

    2015-01-01

    Reactive oxygen and nitrogen species (ROS and RNS) are naturally produced in all cells and organisms. Modifications of standard conditions alter reactive species generation and may result in oxidative stress. Because of the degradation of marine ecosystems, massive aquaculture productions, global change and pathogenic infections, oxidative stress is highly prevalent in marine bivalve molluscs. Haemocytes of bivalve molluscs produce ROS and RNS as part of their basal metabolism as well as in response to endogenous and exogenous stimuli. However, sources and pathways of reactive species production are currently poorly deciphered in marine bivalves, potentially leading to misinterpretations. Although sources and pathways of ROS and RNS productions are highly conserved between vertebrates and invertebrates, some uncommon pathways seem to only exist in marine bivalves. To understand the biology and pathobiology of ROS and RNS in haemocytes of marine bivalves, it is necessary to characterise their sources and pathways of production. The aims of the present review are to discuss the currently known and unknown intracellular sources of reactive oxygen and nitrogen species in marine bivalve molluscs, in light of terrestrial vertebrates, and to expose principal pitfalls usually encountered.

  19. Spatial and Temporal Examination of Bivalve Communities in Several Estuaries of Southern California and Northern Baja California, MX.

    PubMed

    Novoa, Anai; Talley, Theresa S; Talley, Drew M; Crooks, Jeffrey A; Reyns, Nathalie B

    2016-01-01

    A combination of historical bivalve surveys spanning 30-50 years and contemporary sampling were used to document the changes in bivalve community structure over time at four southern California and one northern Baja California estuaries. While there are limitations to the interpretation of historic data, we observed generally similar trends of reduced total bivalve species richness, losses of relatively large and/or deeper-dwelling natives, and gains of relatively small, surface dwelling introduced species across the southern California estuaries, despite fairly distinct bivalve communities. A nearly 50-year absence of bivalves from two wetlands surveyed in a Baja California estuary continued. A combination of site history and current characteristics (e.g., location, depth) likely contributes to maintenance of distinct communities, and both episodic and gradual environmental changes likely contribute to within-estuary temporal shifts (or absences). We highlight future research needed to determine mechanisms underlying patterns so that we can better predict responses of bivalve communities to future scenarios, including climate change and restoration. PMID:26840744

  20. Spatial and Temporal Examination of Bivalve Communities in Several Estuaries of Southern California and Northern Baja California, MX.

    PubMed

    Novoa, Anai; Talley, Theresa S; Talley, Drew M; Crooks, Jeffrey A; Reyns, Nathalie B

    2016-01-01

    A combination of historical bivalve surveys spanning 30-50 years and contemporary sampling were used to document the changes in bivalve community structure over time at four southern California and one northern Baja California estuaries. While there are limitations to the interpretation of historic data, we observed generally similar trends of reduced total bivalve species richness, losses of relatively large and/or deeper-dwelling natives, and gains of relatively small, surface dwelling introduced species across the southern California estuaries, despite fairly distinct bivalve communities. A nearly 50-year absence of bivalves from two wetlands surveyed in a Baja California estuary continued. A combination of site history and current characteristics (e.g., location, depth) likely contributes to maintenance of distinct communities, and both episodic and gradual environmental changes likely contribute to within-estuary temporal shifts (or absences). We highlight future research needed to determine mechanisms underlying patterns so that we can better predict responses of bivalve communities to future scenarios, including climate change and restoration.

  1. Spatial and Temporal Examination of Bivalve Communities in Several Estuaries of Southern California and Northern Baja California, MX

    PubMed Central

    Crooks, Jeffrey A.; Reyns, Nathalie B.

    2016-01-01

    A combination of historical bivalve surveys spanning 30–50 years and contemporary sampling were used to document the changes in bivalve community structure over time at four southern California and one northern Baja California estuaries. While there are limitations to the interpretation of historic data, we observed generally similar trends of reduced total bivalve species richness, losses of relatively large and/or deeper-dwelling natives, and gains of relatively small, surface dwelling introduced species across the southern California estuaries, despite fairly distinct bivalve communities. A nearly 50-year absence of bivalves from two wetlands surveyed in a Baja California estuary continued. A combination of site history and current characteristics (e.g., location, depth) likely contributes to maintenance of distinct communities, and both episodic and gradual environmental changes likely contribute to within-estuary temporal shifts (or absences). We highlight future research needed to determine mechanisms underlying patterns so that we can better predict responses of bivalve communities to future scenarios, including climate change and restoration. PMID:26840744

  2. Proteomic Profiling of Cytosolic Glutathione Transferases from Three Bivalve Species: Corbicula fluminea, Mytilus galloprovincialis and Anodonta cygnea

    PubMed Central

    Martins, José Carlos; Campos, Alexandre; Osório, Hugo; da Fonseca, Rute; Vasconcelos, Vítor

    2014-01-01

    Suspension-feeding bivalves are considered efficient toxin vectors with a relative insensitivity to toxicants compared to other aquatic organisms. This fact highlights the potential role of detoxification enzymes, such as glutathione transferases (GSTs), in this bivalve resistance. Nevertheless, the GST system has not been extensively described in these organisms. In the present study, cytosolic GSTs isoforms (cGST) were surveyed in three bivalves with different habitats and life strategies: Corbicula fluminea, Anodonta cygnea and Mytilus galloprovincialis. GSTs were purified by glutathione-agarose affinity chromatography, and the collection of expressed cGST classes of each bivalve were identified using a proteomic approach. All the purified extracts were also characterized kinetically. Results reveal variations in cGST subunits collection (diversity and properties) between the three tested bivalves. Using proteomics, four pi-class and two sigma-class GST subunits were identified in M. galloprovincialis. C. fluminea also yielded four pi-class and one sigma-class GST subunits. For A. cygnea, two mu-class and one pi-class GST subunits were identified, these being the first record of GSTs from these freshwater mussels. The affinity purified extracts also show differences regarding enzymatic behavior among species. The variations found in cGST collection and kinetics might justify diverse selective advantages for each bivalve organism. PMID:24473139

  3. Measurement of filtration rates by infaunal bivalves in a recirculating flume

    USGS Publications Warehouse

    Cole, B.E.; Thompson, J.K.; Cloern, J.E.

    1992-01-01

    A flume system and protocol for measuring the filtration rate of infaunal bivalves is described. Assemblages of multi-sized clams, at natural densities and in normal filter-feeding positions, removed phytoplankton suspended in a unidirectional flow of water. The free-stream velocity and friction velocity of the flow, and bottom roughness height were similar to those in natural estuarine waters. Continuous variations in phytoplankton (Chroomonas salinay) cell density were used to measure the filtration rate of the suspension-feeding clam Potamocorbula amurensis for periods of 2 to 28 h. Filtration rates of P. amurensis varied from 100 to 580 liters (gd)-1 over a free-stream velocity range of 9 to 25 cm s-1. Phytoplankton loss rates were usually constant throughout the experiments. Our results suggest that suspension-feeding by infaunal bivalves is sensitive to flow velocity. ?? 1992 Springer-Verlag.

  4. Trace metals in water, sediment and bivalves of a tropical estuary, west coast of India.

    PubMed

    Parvez Al-Usmani, S M; Jagtap, T G; Patil, D N

    2015-10-15

    Trace metal pollution was studied in water, sediment and three selected bivalves in Mandovi and Chapora estuaries of Goa. The trace metal in water and sediment of Mandovi was higher than in Chapora. The concentration in the tissues was in the range of 1205.2-2506.7 ppm for Paphia malabarica, 1906.2-2802.6 ppm for Perna viridis and 778.7-1607.5 ppm for Saccostrea cucullata in Mandovi estuary. Tha values for Chapora were 199.4-625.8 ppm for P. malabarica, 812.6-1220.2 for P. viridis and 392.5-418.6 ppm for S. cucullata. The anthropogenic input of metal in Mandovi estuary appears to be mainly responsible for the high accumulation of trace metals. These bivalves have potential to serve as indicator for metal contamination in seafood of Goa.

  5. On the evolutionary ecology of symbioses between chemosynthetic bacteria and bivalves.

    PubMed

    Roeselers, Guus; Newton, Irene L G

    2012-04-01

    Mutualistic associations between bacteria and eukaryotes occur ubiquitously in nature, forming the basis for key ecological and evolutionary innovations. Some of the most prominent examples of these symbioses are chemosynthetic bacteria and marine invertebrates living in the absence of sunlight at deep-sea hydrothermal vents and in sediments rich in reduced sulfur compounds. Here, chemosynthetic bacteria living in close association with their hosts convert CO(2) or CH(4) into organic compounds and provide the host with necessary nutrients. The dominant macrofauna of hydrothermal vent and cold seep ecosystems all depend on the metabolic activity of chemosynthetic bacteria, which accounts for almost all primary production in these complex ecosystems. Many of these enigmatic mutualistic associations are found within the molluscan class Bivalvia. Currently, chemosynthetic symbioses have been reported from five distinct bivalve families (Lucinidae, Mytilidae, Solemyidae, Thyasiridae, and Vesicomyidae). This brief review aims to provide an overview of the diverse physiological and genetic adaptations of symbiotic chemosynthetic bacteria and their bivalve hosts.

  6. Paleoenvironmental and paleoclimatic significance of freshwater bivalves in the Upper Jurassic Morrison Formation, Western Interior, USA

    NASA Astrophysics Data System (ADS)

    Good, Steven C.

    2004-05-01

    Freshwater unionid bivalves are spatially and temporally distributed throughout the Morrison depositional basin, and locally dominate the biomass of many aquatic depositional environments. Two bivalve assemblages are identified. Within-channel assemblages are death assemblages that have been transported and may represent mixed assemblages from multiple communities. These assemblages are predominately disarticulated, in current stable orientations, and composed of higher stream velocity ecophenotypes (medium size, lanceolate form, and very thick shells). The floodplain-pond assemblages are disturbed neighborhood assemblages in the mudstones inhabited during life. The bivalves are predominately articulated, variable in size, and composed of low stream velocity ecophenotypes (large maximum sizes, ovate shell shapes, and thinner shells). The glochidial parasitic larval stage of unionid bivalves provides an effective means of dispersing species throughout drainage basins. These larvae attach to fish and are carried through the fluvial drainage where the larvae detach and establish new bivalve communities. Preliminary paleobiogeographic analyses are drawn at the genus level because of the need to reevaluate bivalve species of the Morrison. Unio spp. and Vetulonaia spp. are widespread throughout the Morrison depositional basin, but Hadrodon spp. are restricted to the eastern portion of the Colorado Plateau during Salt Wash Member deposition, suggesting that Salt Wash drainage was isolated from other contemporaneous regions of the basin. Bivalves from five localities in the Morrison Formation were thin-sectioned for growth band analysis. Growth bands of modern unionid bivalves are produced when the valves are forced to close. Closure can produce annual growth bands in response to seasonal variation, such as temperature-induced hibernation, or precipitation-induced aestivation or turbidity. Pseudoannual growth bands form from non-cyclical events such as predation attacks or

  7. Detection of genotoxic substances in bivalve molluscs from the Saguenay Fjord (Canada), using the SOS chromotest.

    PubMed

    White, P A; Blaise, C; Rasmussen, J B

    1997-08-14

    Few studies have employed bioassays to investigate the accumulation of genotoxins in aquatic biota that inhabit areas contaminated with industrial and municipal wastes. This study employed the SOS Chromotest, a short-term bacterial genotoxicity assay, to investigate the presence of genotoxins in bivalve molluscs from the Saguenay Fjord (Canada). Genotoxicity analyses were performed on dichloromethane extracts of Mya arenaria and Mytilus edulis collected downstream from several aluminum refineries and forestry products industries known to produce and release genotoxic substances. The results confirmed that bivalve molluscs inhabiting downstream regions are contaminated with both direct-acting and pro-genotoxic substances. In several cases, SOS response induction factors exceeded 3.0. The results failed to reveal a clear downstream trend of decreasing genotoxicity with increasing distance from the presumed industrial sources(s). A significant relationship (r2 = 0.61, p < 0.007) between a demographic variable (population near shoreline) and lipid-corrected genotoxic potency suggest that the accumulated direct-acting genotoxins may be of municipal origin. Significant relationships between tissue extract genotoxicity (r2 = 0.75, p < 0.003) and tissue PAH contamination (r2 = 0.77, p < 0.0001) and drainage basin area suggests that the bivalves are accumulating airborne contaminants deposited on the surface of the relevant drainage basins. In spite of contamination with genotoxic PAHs, the addition of rat liver microsomal enzymes reduced the genotoxic potency of all samples investigated (31-94% decrease). The results also revealed a significant relationship between tissue extract genotoxicity and PAH concentration (r2 = 0.72, p < 0.0005). Further analyses confirmed that a variable portion (7-97%) of the S9-activated tissue extract genotoxicity can be attributed to the detected PAHs. Although the sources, identity and effects of genotoxins accumulated by bivalves of the

  8. Alkylphenols and polycyclic aromatic hydrocarbons in eastern Mediterranean Spanish coastal marine bivalves.

    PubMed

    Bouzas, Alberto; Aguado, Daniel; Martí, Nuria; Pastor, José Manuel; Herráez, Rosa; Campins, Pilar; Seco, Aurora

    2011-05-01

    This paper reports the first results on alkylphenol pollution in edible bivalves from the Spanish coast. Two sampling campaigns (July 2006 and July 2007) were carried out to determine the concentration of nonylphenol (NP), octylphenol (OP), and eight polycyclic aromatic hydrocarbons (PAHs) in wild mussels (Mytilus galloprovincialys) and clams (Donax trunculus) at 14 sampling sites along the eastern Mediterranean Spanish coast. The results show that NP is the predominant alkylphenol, being the port of Valencia the most polluted area (up to 147 μg/kg wet weight in clams). Moving away from the ports the concentration of NP in bivalves decreased. OP concentration was below its detection limit in most of the studied areas and its maximum concentration (6 μg/kg w/w) was measured in clams from the port of Sagunto. The presence of low levels of PAHs was observed in most of the studied areas. The total PAHs concentration (i.e., sum of the eight measured PAHs) achieved a maximum value of 10.09 μg/kg w/w in the north coast of Valencia city. The distribution pattern of the individual PAHs showed that both pollution sources petrogenic and pyrolytic were present in the sampled areas. Fluoranthene was the most abundant PAH in mussels while benzo(b)fluoranthene in clams. The maximum concentration of 10 μg/kg w/w for benzo(a)pyrene established by the European Commission was never reached, indeed sampled bivalves showed concentrations 10 times lower than this reference value. Thus, they can be considered safe for human consumption. Despite the low contamination levels, the results show an overall pollution of bivalves by alkylphenol and PAHs as well as an increment in the number of polluted areas from 2006 to 2007. Thus, periodical sampling campaigns should be carried out to monitor the long-term tendency of these toxic and persistent pollutants.

  9. Detection of the pufferfish toxin tetrodotoxin in European bivalves, England, 2013 to 2014.

    PubMed

    Turner, A D; Powell, A; Schofield, A; Lees, D N; Baker-Austin, C

    2015-01-15

    We report the first detection of tetrodotoxins (TTX) in European bivalve shellfish. We demonstrate that TTX is present within the temperate waters of the United Kingdom, along the English Channel, and can accumulate in filter-feeding molluscs. The toxin is heat-stable and thus it cannot be eliminated during cooking. While quantified concentrations were low in comparison to published minimum lethal doses for humans, the results demonstrate that the risk to shellfish consumers should not be discarded.

  10. Bivalves and gastropods from the middle Campanian Anacacho limestone, South Central Texas

    USGS Publications Warehouse

    Elder, W.P.

    1996-01-01

    The Anacacho Limestone was deposited during the Campanian and represents two depositional intervals, one of early Campanian and one of middle Campanian age. These two intervals correspond to periods of major eustatic sea level rise. This study focuses on the molluscan paleontology of the middle Campanian interval in the eastern part of the Anacacho exposure belt in Medina County, Texas. Molluscan assemblages in this area are indicative of inner to mid-shelf environments. No significant reef components are present. These eastern Anacacho deposits are interpreted to represent more offshore, deeper water environments than those to the southwest, where reef and lagoonal deposits have been reported. Analysis of the macrofossil components from these eastern localities has expanded the number of invertebrate species known from the Anacacho Limestone by nearly three-fold. This increase in diversity, based on a small amount of new work, suggests that many more taxa are yet to be identified, particularly in the western part of the exposure belt in Uvalde and Kinney Counties. This paper documents the bivalve and gastropod fauna, discussing and illustrating 24 bivalve taxa and 11 gastropod species. Two new bivalve species are named, Panopea anacachoensis new species and Spondylus siccus new species, and two potentially new gastropod species are identified but not named herein due to inadequate material. This paper expands the distribution of many eastern Gulf Coast and Atlantic Coast taxa westward into Texas and shows strong ties between the Anacacho fauna and that of the Campanian Tar Heel and Bladen Formations of the Black Creek Group in North Carolina. The taxonomic ties between these two areas probably reflect the thorough documentation of the North Carolina fauna, which is the best documented Campanian bivalve fauna in the Gulf or Atlantic Coast regions.

  11. Dinophysis caudata generated lipophilic shellfish toxins in bivalves from the Nanji Islands, East China Sea

    NASA Astrophysics Data System (ADS)

    Jiang, Tao; Xu, Yixiao; Li, Yang; Qi, Yuzao; Jiang, Tianjiu; Wu, Feng; Zhang, Fan

    2014-01-01

    A 12-month program of monitoring potentially toxic microalgae (that produce lipophilic shellfish toxins; LSTs) and their toxins in bivalves was conducted from April 2006 to March 2007 in the Nanji Islands, East China Sea. Two Dinophysis species, D. caudata and D. acuminata, were identified, and D. caudata was found to be the dominant species. D. caudata was detected in water samples between April and June 2006, and between February and March 2007. It reached its highest abundances in May, with a mean abundance of 1.38×102 cells/L in surface water and 1.25×102 cells/L in bottom water (<10 m deep). The temporal distribution of D. caudata was associated with the occurrence of LSTs in bivalve samples, which mostly occurred at the same time as D. caudata blooms, between April and July 2006. All of the cultured bivalves sampled between April and June were contaminated with LSTs, with an average toxicity of 85 μg okadaic acid (OA) eq./100 g meat, which was four times higher than the Chinese regulatory limit (20 μg OA eq./100 g meat). Ten out of fifteen wild samples (66.7%) collected during the same period were positive for LSTs, and contained an average LST toxicity of 45 μg OA eq./100 g meat (more than twice the regulatory value). Cultured Patinopecten yessoensis collected on 15 May 2006 had the highest toxicity, 320 μg OA eq./100 g meat, and relatively high toxicities (80 to 160 μg OA eq./100 g meat) were found in bivalves until the end of July.

  12. Bioaccumulation of selected metals in bivalves (Unionidae) and Phragmites australis inhabiting a municipal water reservoir.

    PubMed

    Rzymski, Piotr; Niedzielski, Przemysław; Klimaszyk, Piotr; Poniedziałek, Barbara

    2014-05-01

    Urbanization can considerably affect water reservoirs by, inter alia, input, and accumulation of contaminants including metals. Located in the course of River Cybina, Maltański Reservoir (Western Poland) is an artificial shallow water body built for recreation and sport purposes which undergoes restoration treatment (drainage) every 4 years. In the present study, we demonstrate an accumulation of nine metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in water, sediment, three bivalve species (Anodonta anatina, Anodonta cygnea, Unio tumidus), and macrophyte Phragmites australis collected before complete drainage in November 2012. The mean concentrations of metals in the sediment, bivalves, and P. australis (roots and leaves) decreased in the following order: Fe > Mn > Zn > Cu > Cr > Ni > Pb > Co > Cd. A considerably higher bioconcentration of metals was observed in samples collected from the western and southern sites which undergo a higher degree of human impact. Sediments were found to be a better indicator of metal contamination than water samples. Interspecific differences in levels of metal accumulation were found between investigated unionids. U. tumidus accumulated higher levels of Cr, positively correlated with ambient concentrations, predisposing this species as a potential bioindicator of this metal in aquatic environments. On the other hand, species of Anodonta genus demonstrated higher accumulation of Cu and Cd. Positive correlations were found between Pb content in the sediments and tissues of all three bivalve species. In P. australis, metals were largely retained in roots except for Cd and Pb for which higher concentrations were found in leaves suggesting additional absorption of these metals from aerial sources. P. australis and bivalve from the Maltański Reservoir may be a potential source of toxic metals for animals feeding upon them and contribute to further contamination in the food chain.

  13. Chemosynthetic bacteria found in bivalve species from mud volcanoes of the Gulf of Cadiz.

    PubMed

    Rodrigues, Clara F; Webster, Gordon; Cunha, Marina R; Duperron, Sébastien; Weightman, Andrew J

    2010-09-01

    As in other cold seeps, the dominant bivalves in mud volcanoes (MV) from the Gulf of Cadiz are macrofauna belonging to the families Solemyidae (Acharax sp., Petrasma sp.), Lucinidae (Lucinoma sp.), Thyasiridae (Thyasira vulcolutre) and Mytilidae (Bathymodiolus mauritanicus). The delta(13)C values measured in solemyid, lucinid and thyasirid specimens support the hypothesis of thiotrophic nutrition, whereas isotopic signatures of B. mauritanicus suggest methanotrophic nutrition. The indication by stable isotope analysis that chemosynthetic bacteria make a substantial contribution to the nutrition of the bivalves led us to investigate their associated bacteria and their phylogenetic relationships based on comparative 16S rRNA gene sequence analysis. PCR-denaturing gradient gel electrophoresis analysis and cloning of bacterial 16S rRNA-encoding genes confirmed the presence of sulfide-oxidizing symbionts within gill tissues of many of the studied specimens. Phylogenetic analysis of bacterial 16S rRNA gene sequences demonstrated that most bacteria were related to known sulfide-oxidizing endosymbionts found in other deep-sea chemosynthetic environments, with the co-occurrence of methane-oxidizing symbionts in Bathymodiolus specimens. This study confirms the presence of several chemosynthetic bivalves in the Gulf of Cadiz and further highlights the importance of sulfide- and methane-oxidizing symbionts in the trophic ecology of macrobenthic communities in MV.

  14. Lincoln Park shoreline erosion control project: Monitoring for surface substrate, infaunal bivalves and eelgrass, 1993

    SciTech Connect

    Antrim, L.D.; Thom, R.M.; Gardiner, W.W.

    1993-09-01

    In 1988, the US Army Corps of Engineers and the City of Seattle placed material on the upper beach at Lincoln Park, in West Seattle, Washington. The fill served to mitigate shoreline erosion that had caused undercutting and collapse of the seawall in several places. A series of pre- and post-construction studies have been conducted to assess the impacts to marine biota of fill placement and movement of surface substrate. This study was designed to monitor infaunal bivalves and eelgrass from intertidal areas in and adjacent to the area of original fill placement. Findings from this survey were compared to previous survey results to determine (1) if recruitment of infaunal bivalves to the fill area has occurred, (2) if infaunal bivalve densities outside the fill area are stable, and (3) if eelgrass distribution and abundance have remained stable along the adjacent shoreline. To maximize comparability of findings from this survey with previous studies, sampling techniques, transects, and tidal elevations were consistent with previous studies at this site.

  15. Environmental regulation of bivalve growth in the southern Barents Sea: A combined ecological and geochemical approach

    NASA Astrophysics Data System (ADS)

    Carroll, M. L.; Johnson, B. J.; Henkes, G. A.; McMahon, K. W.; Voronkov, A.; Ambrose, W. G., Jr.; Denisenko, S. G.

    2009-04-01

    Ecological and geochemical analyses of bivalve shells provide potentially complimentary information on patterns and drivers of natural variability in Arctic marine populations, yet are rarely considered together. We analyzed growth rates and shell geochemistry of the Greenland Smooth Cockle (Serripes groenlandicus) from the southern Barents Sea between 1882 and 1968. Growth, stable isotope (oxygen and carbon), and trace elemental (Mg, Sr, Ba, Mn) patterns were linked to environmental variations on weekly to decadal scales. Standardized growth rates exhibited multi-year periodicity inversely related to the North Atlantic Oscillation Index (NAO) and positively related to river discharge. Up to 60% of the interannual variability in Ba/Ca could be explained by variations in river discharge at stations closest to the rivers, but the relationship disappeared at a more distant location. Stable isotope data (18O, 13C), and Sr/Ca patterns suggest that bivalve growth ceases at elevated temperatures during the fall and recommences at the coldest temperatures in the early spring, implying that food, rather than temperature, is the primary driver of the annual growth cycle. Combining annually-integrated growth results and higher resolution geochemical results thus elucidated the annual growth cycle of an Arctic bivalve and mechanisms of biophysical coupling over a range of temporal and spatial scales.

  16. Shell disturbances and butyltins burden in commercial bivalves collected from the Bizerta lagoon (northern Tunisia).

    PubMed

    Kefi, Ferdaous Jaafar; Lahbib, Youssef; Abdallah, Lamia Gargouri Ben; El Menif, Najoua Trigui

    2012-11-01

    Shell disturbances and soft tissues butyltin burden were investigated in commercial bivalves Lithophaga lithophaga, Mytilus galloprovincialis, Solen marginatus and Crassostrea gigas from the Bizerta lagoon. Shell disturbances were found in all bivalves, being scarce in S. marginatus. In the internal valve of L. lithophaga, burrowing annelids and sipunculids living inside galleries were observed, while in the external valve, brown-blackish or white stains were found. In M. galloprovincialis, a yellowish mass located at the shell anterior side was found fixed firmly to the pearly layer by a hard brownish structure covering some annelid elliptic eggs. In the internal shell layer of some specimens collected in April, embryos belonging to tubiculous annelids at various developmental stages were observed. In C. gigas, shell thickening was revealed in some specimens corresponding to white doughy deposits at the internal valve and between shell layers. In S. marginatus, only one specimen showing a cavity at the posterior site was found. Total butyltin concentrations in the studied bivalves varied between 30 and 245 ng/g dry weight with tributyltin (TBT) being the predominant compound. The highest concentration was recorded in L. lithophaga collected from the Bizerta Bay and the lowest concentration in S. marginatus from Maghraoua. This study provided baseline data that could serve for long-term monitoring of TBT pollution in Tunisia, since legislation to reduce the use of TBT-based antifouling paints has not been introduced yet.

  17. Stress detection in bivalve mollusk using non-invasive bioelectric monitoring of myoneural behavior

    SciTech Connect

    Morgan, E.L.; Hardison, B.S.; Dawson, V.K.; Waller, D.; Waller, W.T.; Dickson, K.L.; Allen, H.J.

    1995-12-31

    Few studies have demonstrated cause-and-effect linkages between extrinsic environmental factors and intrinsic bioelectric action potentials of bivalve mollusk using non-invasive, non-destructive approaches. A non-invasive, external probe configuration and detection system, similar to one used previously with native unionids, was developed for continuously monitoring bioelectric activities of clams and mussels. Using remote probes and differential amplifiers, bioelectric activities were recorded for cardiac, adductor, siphon and foot responses using a computer equipped with integrating software. To test if remote, non-invasive probes would detect similar information to that recorded by invasive needle electrodes, two individuals of zebra mussel (Dreissenia polymorpha), and Asiatic clam (Corbicula fluminea) were each configured with two sets of probes. One set was inserted between the valves and along the inside surface of the shelf; the other set was positioned remotely about the outside margins of the valves. Signal validation was made by simultaneously recording bioelectric responses for the same animal from both sets of probes. In preliminary stress tests monitored bivalves were subjected to changes in temperatures over 2 to 3 hr intervals from ambient to potentially lethal levels (20 to 30 C for zebra, 25 C to 40 C for corbicula). Dramatic increases resulted in both number and amplitude of cardiac events as temperature increased. Planned studies will use this approach to evaluate bivalve myoneural behavior patterns in response to chemical and non-chemical stimuli.

  18. Bivalve larvae testing of ocean and in-bay sediments using porewater and elutriates

    SciTech Connect

    Griffin, D.; Targgart, L.

    1995-12-31

    Toxicity of marine sediments is commonly tested using bivalve larval tests. The tests are performed on elutriates, which are prepared by mixing the sediment sample with seawater, and allowing the mixture to settle. The supernatant is separated and tested. Test results appeared to vary depending on the grain-size of the sediments. A study was performed to compare the effects of sediment grain-size on elutriate and porewater toxicity using the bivalve larvae test. Sediments were sampled from two sites: one in San Francisco Bay and one off the coast of San Francisco in the open ocean. From each site, two areas were sampled, one that was potentially impacted by a point-source discharge and another that was free from any discharge impacts. The bay sediments were fine-grained, and the ocean sediments were coarse grained. Porewater from each sample was extracted by centrifugation, and elutriates were prepared using a 4:1 sediment: seawater ratio. Each of the porewater and elutriate samples were tested using the ASTM Standard Guide for Conducting Static Acute Toxicity Tests with Saltwater Bivalves. The results show differences in toxicity that appear to be related to sediment grain-size. The results of this study further imply that dredge material test results should be interpreted with caution when fine-grained sediments are tested. Normalization of the results to grain-size may be appropriate.

  19. Pathogenic marine microbes influence the effects of climate change on a commercially important tropical bivalve

    PubMed Central

    Turner, Lucy M.; Alsterberg, Christian; Turner, Andrew D.; Girisha, S. K.; Rai, Ashwin; Havenhand, Jonathan N.; Venugopal, M. N.; Karunasagar, Indrani; Godhe, Anna

    2016-01-01

    There is growing evidence that climate change will increase the prevalence of toxic algae and harmful bacteria, which can accumulate in marine bivalves. However, we know little about any possible interactions between exposure to these microorganisms and the effects of climate change on bivalve health, or about how this may affect the bivalve toxin-pathogen load. In mesocosm experiments, mussels, Perna viridis, were subjected to simulated climate change (warming and/or hyposalinity) and exposed to harmful bacteria and/or toxin-producing dinoflagellates. We found significant interactions between climate change and these microbes on metabolic and/or immunobiological function and toxin-pathogen load in mussels. Surprisingly, however, these effects were virtually eliminated when mussels were exposed to both harmful microorganisms simultaneously. This study is the first to examine the effects of climate change on determining mussel toxin-pathogen load in an ecologically relevant, multi-trophic context. The results may have considerable implications for seafood safety. PMID:27576351

  20. Analysis of synonymous codon usage patterns in sixty-four different bivalve species

    PubMed Central

    De Moro, Gianluca; Venier, Paola; Pallavicini, Alberto

    2015-01-01

    Synonymous codon usage bias (CUB) is a defined as the non-random usage of codons encoding the same amino acid across different genomes. This phenomenon is common to all organisms and the real weight of the many factors involved in its shaping still remains to be fully determined. So far, relatively little attention has been put in the analysis of CUB in bivalve mollusks due to the limited genomic data available. Taking advantage of the massive sequence data generated from next generation sequencing projects, we explored codon preferences in 64 different species pertaining to the six major evolutionary lineages in Bivalvia. We detected remarkable differences across species, which are only partially dependent on phylogeny. While the intensity of CUB is mild in most organisms, a heterogeneous group of species (including Arcida and Mytilida, among the others) display higher bias and a strong preference for AT-ending codons. We show that the relative strength and direction of mutational bias, selection for translational efficiency and for translational accuracy contribute to the establishment of synonymous codon usage in bivalves. Although many aspects underlying bivalve CUB still remain obscure, we provide for the first time an overview of this phenomenon in this large, commercially and environmentally important, class of marine invertebrates. PMID:26713259

  1. Bivalve and barnacle larvae distribution driven by water temperature in a Mediterranean lagoon.

    PubMed

    Ziadi, Boutheina; Dhib, Amel; Turki, Souad; Aleya, Lotfi

    2015-05-01

    The objective of this study was to explore the relationships between the distribution of some meroplanktonic species and water temperature. Meroplankton larvae abundance of bivalves, and barnacles and water temperature fluctuations were studied from February 2011 to January 2012 at five stations in Ghar El Melh lagoon (GML) Mediterranean Sea, northern Tunisia). According to redundancy analysis (RDA), a significant difference was found in the distribution of larvae among the seasons (F = 10.28, p < 0.001); summer and autumn appear to be the period of bivalve larvae development, whereas the arrival of barnacle larvae coincided with winter and spring. The generalized additive models (GAMs) show strong correlation of bivalve larvae with high temperature (F = 23.2; p < 0.001) and the affinity of barnacle larvae to low temperature values (F = 8.41; p = 0.004). This environmental parameter accounted for 26 % of the deviance in variability in larvae abundance. The development process of many generations of larvae may therefore have been predetermined by temperature.

  2. Food availability and sex reversal in Mytella charruana, an introduced bivalve in the southeastern United States.

    PubMed

    Stenyakina, A; Walters, L J; Hoffman, E A; Calestani, C

    2010-03-01

    We studied the reproductive biology of Mytella charruana to determine the potential reproductive success of this newly introduced bivalve species from Central/South America. We analyzed gonad morphology, gametogenesis, and the sex ratios of introduced populations throughout a 12 month period. In the non-native habitat M. charruana shows the same strategy of gametogenesis that had been observed in its native environment, which is an opportunistic type of gonadal cycle with gametes produced throughout the year. Instead, the spawning period of M. charruana along the southeastern US coast is extended compared to that found in the native environment. We determined the minimum size (shell length) of sexually reproductive mussels to be 1.25 cm. Interestingly, throughout the year the population samples were typically composed of a higher proportion of females. The female to male sex ratio varied within a wide range from 1:0 to 1:3.3. Upon this discovery we tested the effects of food availability on the gametogenesis of adult animals. The sex ratio of mussels collected from different locations and maintained in the laboratory with or without food changed toward a male-bias under starvation conditions within a month. This is the first study directly showing that food availability can trigger sex reversal in an adult bivalve. According to our data this mussel species will likely continue to spread along the east coast of the US. Moreover, M. charruana may prove to be a model organism in the study of alternative sexuality in bivalves.

  3. Explosive demographic expansion by dreissenid bivalves as a possible result of astronomical forcing

    NASA Astrophysics Data System (ADS)

    Harzhauser, M.; Mandic, O.; Kern, A. K.; Piller, W. E.; Neubauer, T. A.; Albrecht, C.; Wilke, T.

    2013-12-01

    Human induced range expansions of invasive dreissenid bivalves are of great concern. However, the underlying biological processes are only poorly understood, partly due to the lack of information on natural expansion events. Here we use the extinct bivalve species Sinucongeria primiformis as a model organism for testing natural (i.e. pre-Anthropocene) blooms of dreissenid species in a lacustrine system of Lake Pannon during the Tortonian (~ 10.5 Myr; late Miocene). A total of 600 samples from a consecutive core were evaluated for the relative abundance of this pavement-forming mollusc, which cover about eight millennia of late Miocene time with a decadal resolution. Our data indicate that the settlement by bivalves in the offshore environment was limited mainly by bottom water oxygenation, which follows predictable and repetitive patterns through time. These population fluctuations might be related to solar cycles: successful dreissenid settlement is recurring in a frequency known as the lower and upper Gleissberg cycles with 50-80 and 90-120 yr periods. These cycles appear to control regional wind patterns, which are directly linked to water mixing of the lake. This is modulated by the even more prominent 500 yr cycle, which seems to be the most important pacemaker for Lake Pannon hydrology.

  4. Explosive demographic expansion by dreissenid bivalves as a possible result of astronomical forcing

    NASA Astrophysics Data System (ADS)

    Harzhauser, M.; Mandic, O.; Kern, A. K.; Piller, W. E.; Neubauer, T. A.; Albrecht, C.; Wilke, T.

    2013-07-01

    Human induced range expansions of invasive dreissenid bivalves are of great concern. However, the underlying biological processes are only poorly understood, partly due to the lack of information on natural expansion events. Here we use the extinct bivalve species Sinucongeria primiformis as a model organism for testing natural (i.e. non-Anthropocene) blooms of dreissenid species in a lacustrine system of Lake Pannon during the Tortonian (~10.5 Myr; Late Miocene). 600 samples from a consecutive core were evaluated for the relative abundance of this pavement-forming mollusc, which cover about 8 millennia of Late Miocene time with a decadal resolution. Our data indicate that the settlement by bivalves in the offshore environment was limited mainly by bottom water oxygenation, which follows predictable and repetitive patterns through time. These population fluctuations might be related to solar cycles: successful dreissenid settlement is re-occurring in a frequency known as the lower and upper Gleissberg cycles with a 50-80 and 90-120 yr period. These cycles appear to control regional wind patterns, which are directly linked to water mixing of the lake. This is modulated by the even more prominent 500 yr cycle, which seems to be the most important pacemaker for Lake Pannon hydrology.

  5. Predicting growth and mortality of bivalve larvae using gene expression and supervised machine learning.

    PubMed

    Bassim, Sleiman; Chapman, Robert W; Tanguy, Arnaud; Moraga, Dario; Tremblay, Rejean

    2015-12-01

    It is commonly known that the nature of the diet has diverse consequences on larval performance and longevity, however it is still unclear which genes have critical impacts on bivalve development and which pathways are of particular importance in their vulnerability or resistance. First we show that a diet deficient in essential fatty acid (EFA) produces higher larval mortality rates, a reduced shell growth, and lower postlarval performance, all of which are positively correlated with a decline in arachidonic and eicosapentaenoic acids levels, two EFAs known as eicosanoid precursors. Eicosanoids affect the cell inflammatory reactions and are synthesized from long-chain EFAs. Second, we show for the first time that a deficiency in eicosanoid precursors is associated with a network of 29 genes. Their differential regulation can lead to slower growth and higher mortality of Mytilus edulis larvae. Some of these genes are specific to bivalves and others are implicated at the same time in lipid metabolism and defense. Several genes are expressed only during pre-metamorphosis where they are essential for muscle or neurone development and biomineralization, but only in stress-induced larvae. Finally, we discuss how our networks of differentially expressed genes might dynamically alter the development of marine bivalves, especially under dietary influence.

  6. Pathogenic marine microbes influence the effects of climate change on a commercially important tropical bivalve.

    PubMed

    Turner, Lucy M; Alsterberg, Christian; Turner, Andrew D; Girisha, S K; Rai, Ashwin; Havenhand, Jonathan N; Venugopal, M N; Karunasagar, Indrani; Godhe, Anna

    2016-01-01

    There is growing evidence that climate change will increase the prevalence of toxic algae and harmful bacteria, which can accumulate in marine bivalves. However, we know little about any possible interactions between exposure to these microorganisms and the effects of climate change on bivalve health, or about how this may affect the bivalve toxin-pathogen load. In mesocosm experiments, mussels, Perna viridis, were subjected to simulated climate change (warming and/or hyposalinity) and exposed to harmful bacteria and/or toxin-producing dinoflagellates. We found significant interactions between climate change and these microbes on metabolic and/or immunobiological function and toxin-pathogen load in mussels. Surprisingly, however, these effects were virtually eliminated when mussels were exposed to both harmful microorganisms simultaneously. This study is the first to examine the effects of climate change on determining mussel toxin-pathogen load in an ecologically relevant, multi-trophic context. The results may have considerable implications for seafood safety. PMID:27576351

  7. Impact of particulate pollutant metals on larval and adult bivalve molluscs

    SciTech Connect

    Gilbert, T.R.; Robinson, W.E. ); Morse, M.P. . Marine Science Lab.)

    1982-10-25

    Our investigations of the effects of pollutants on bivalve molluscs have continued with studies with in the following areas: bioaccumulation of trace metals in adult sea scallops exposed to dissolved and particulate forms of the metals, SEM/EDXA studies of phosphoritic concretions in the kidneys of adult sea scallops (Placopecten magellanicus), documentation of the normal embryonic and larval development, including shell formation, in surf clams (Spisula solidissima), evaluation of the toxicity of dissolved silver to the gametes and larvae of surf clams at several stages of development, and examination of the effects of turbid suspensions on the feeding efficiency of larval Mercenaria mercenaria. The overall goal of our work is twofold. First, we are striving to gain an understanding of the pathways by which metals are transported within bivalve molluscs. The production of metallothioneins and metal-rich inorganic concretions have been documented for a number of bivalves. The ways in which of metal-rich matrices in membrane-limited vesicles as an intermediate step, is one area of investigation. Second, we are examining the relative sensitivities of the gamete and of early life stages of these organisms to stresses induced by exposure to energy-related pollutants. 46 refs., 12 figs., 8 tabs.

  8. Trace element ratios in bivalve shells as records of environmental conditions

    NASA Astrophysics Data System (ADS)

    Tynan, S.; Opdyke, B.; Welch, S.; Beavis, S.

    2007-12-01

    Stable isotope and trace element data from the carbonate of both marine and freshwater bivalves are proving to be useful tools in studies of palaeoclimate and environmental change. However, much of the work already done has shown that the trace element ratios in bivalve shells exhibit a complex relationship with the ambient environment and caution must be exercised when attempting to use them as environmental proxies. This work examines the feasibility of using the trace element ratios Mg/Ca, Sr/Ca, Ba/Ca and Mn/Ca of the shells of a number of different species of bivalves as records of the temperature and salinity of their ambient aquatic environment. The species analysed were the estuarine oysters Saccostrea glomerata, Ostrea angasi, and Crassostrea gigas, an estuarine mussel, Mytilus galloprovincialis, and the freshwater mussel Velesunio ambiguus. The estuarine shells were taken from monitoring experiments conducted over a period of 12 months at two different field sites. Freshwater shells were collected wild, from locations close to water monitoring stations. Preliminary results show distinct variations in the Mg/Ca of O. angasi shells with an apparent seasonal pattern. V. ambiguus shells show clear patterns in Mn/Ca, linked to environmental variations.

  9. Evaluation of γ-radiation-induced DNA damage in two species of bivalves and their relative sensitivity using comet assay.

    PubMed

    Praveen Kumar, M K; Shyama, S K; Sonaye, B S; Naik, U Roshini; Kadam, S B; Bipin, P D; D'costa, A; Chaubey, R C

    2014-05-01

    Ionizing radiation is known to induce genetic damage in diverse groups of organisms. Under accidental situations, large quantities of radioactive elements get released into the environment and radiation emitted from these radionuclides may adversely affect both the man and the non-human biota. The present study is aimed (a) to know the genotoxic effect of gamma radiation on aquatic fauna employing two species of selected bivalves, (b) to evaluate the possible use of 'Comet assay' for detecting genetic damage in haemocytes of bivalves as a biomarker for environmental biomonitoring and also (c) to compare the relative sensitivity of two species of bivalves viz. Paphia malabarica and Meretrix casta to gamma radiation. The comet assays was optimized and validated using different concentrations (18, 32 and 56 mg/L) of ethyl methanesulfonate (EMS), a direct-acting reference genotoxic agent, to which the bivalves were exposed for various times (24, 48 and 72 h). Bivalves were irradiated (single acute exposure) with 5 different doses (viz. 2, 4, 6, 8 and 10 Gy) of gamma radiation and their genotoxic effects on the haemocytes were studied using the comet assay. Haemolymph was collected from the adductor muscle at 24, 48 and 72 h of both EMS-exposed and irradiated bivalves and comet assay was carried out using standard protocol. A significant increase in DNA damage was observed as indicated by an increase in % tail DNA damage at different concentrations of EMS and all the doses of gamma radiation as compared to controls in both bivalve species. This showed a dose-dependent increase of genetic damage induced in bivalves by EMS as well as gamma radiation. Further, the highest DNA damage was observed at 24h. The damage gradually decreased with time, i.e. was smaller at 48 and 72 h than at 24h post irradiation in both species of bivalves. This may indicate repair of the damaged DNA and/or loss of heavily damaged cells as the post irradiation time advanced. The present study

  10. Gigantic lateral spreading of mountains in the epicentral area of the expected Tokai earthquake, central Japan

    NASA Astrophysics Data System (ADS)

    Chigira, Masahiro; Nakamura, Takeshi

    2010-05-01

    Lateral spreading of mountains is not only a degradation process itself but also it could become the background of a catastrophic landslide that occurs at its spreading rims. We found gigantic lateral spreading behind the Yui landsllide area, which is located along the Pacific Sea coast in the epicentral area of the expected Tokai earthquake, central Japan. The Yui landslide area is located on a socially very important place, where are major lifelines connecting east and west Japan: Tokaido railway, Tokaido Shinkansen, and Tomei highway. The Yui landslide area comprises many landslide units and has been causing many catastrophs. The lateral spreading is characterized by NS-trending multiple ridges and linear depressions as long as 1 to 2 km and up to 60 m deep. These features are observable on the aerial photographs and are clearly identified by using airborne laser scanner. Mountains subjected to the lateral spreading is 3 km wide in EW and 6 km long in NS and are 250 to 500 m high above sea level. These morphological features suggest that the NS trending ridges spread laterally to EW and their central parts settled down like the way by which horsts and grabens are made. The ridges are underlain by Miocene beds consisting of the alternating beds of mudstone and sandstone in the lower part and of sandstone and conglomerate in the upper part. The spreading ridge occupies the axial part of a NS-trending syncline, which has a half wave length longer than 2 km and comprises minor folds with a wavelength on the order of hundred meters. This structure, synclinorium, suggests that there could be decollements along the enveloping surface of the minor folds and that the lateral spreading could have a low-angle slip surface along the enveloping surface of the minor folds. There are many landslides along the side slopes of the laterally spread ridges and they have been moving many times by rainstorms and also by earthquakes. The movements are recorded since 1781, but the

  11. Gigantic landslides versus glacial deposits: on origin of large hummock deposits in Alai Valley, Northern Pamir

    NASA Astrophysics Data System (ADS)

    Reznichenko, Natalya

    2015-04-01

    As glaciers are sensitive to local climate, their moraines position and ages are used to infer past climates and glacier dynamics. These chronologies are only valid if all dated moraines are formed as the result of climatically driven advance and subsequent retreat. Hence, any accurate palaeoenvironmental reconstruction requires thorough identification of the landform genesis by complex approach including geomorphological, sedimentological and structural landform investigation. Here are presented the implication of such approach for the reconstruction of the mega-hummocky deposits formation both of glacial and landslide origin in the glaciated Alai Valley of the Northern Pamir with further discussion on these and similar deposits validity for palaeoclimatic reconstructions. The Tibetan Plateau valleys are the largest glaciated regions beyond the ice sheets with high potential to provide the best geological record of glacial chronologies and, however, with higher probabilities of the numerous rock avalanche deposits including those that were initially considered of glacial origin (Hewitt, 1999). The Alai Valley is the largest intermountain depression in the upper reaches of the Amudarja River basin that has captured numerous unidentified extensive hummocky deposits descending from the Zaalai Range of Northern Pamir, covering area in more than 800 km2. Such vast hummocky deposits are usually could be formed either: 1) glacially by rapid glacial retreat due to the climate signal or triggered a-climatically glacial changes, such as glacial surge or landslide impact, or 2) during the landslide emplacement. Combination of sediment tests on agglomerates forming only in rock avalanche material (Reznichenko et al., 2012) and detailed geomorphological and sedimentological descriptions of these deposits allowed reconstructing the glacial deposition in the Koman and Lenin glacial catchments with identification of two gigantic rock avalanches and their relation to this glacial

  12. The 45-kb unit of major urinary protein gene organization is a gigantic imperfect palindrome.

    PubMed

    Bishop, J O; Selman, G G; Hickman, J; Black, L; Saunders, R D; Clark, A J

    1985-07-01

    The multigene family which codes for the mouse major urinary proteins consists of about 35 genes. Most of these are members of two distinct groups, group 1 and group 2. The group 1 and group 2 genes are organized in head-to-head pairs within 12 to 15 remarkably uniform chromosomal units or domains about 45 kilobase pairs (kb) in size. The 45-kb units are located on chromosome 4, and many of them are adjacent to each other. We propose that the 45-kb unit is a unit both of organization and of evolutionary change. In this study the homologies within the unit were observed by examining, in an electron microscope, heteroduplex and foldback structures made from cloned major urinary protein genes. These show that the 45-kb unit is a gigantic imperfect palindrome. Each arm of the palindrome contains two regions of inverted symmetry of 9.5 and 4.5 kb separated by a 3-kb nonsymmetrical region. We argue that the nonsymmetrical regions arose by a series of deletion events in the two arms of the palindrome. The center of the 45-kb unit is an 8-kb sequence without inverted symmetry flanked by the 9.5-kb regions, which contain the 4-kb genes and their immediate 5' and 3' flanking regions. The junction between adjacent 45-kb units is a 2- to 4-kb sequence without inverted symmetry flanked by the 4.5-kb regions. Some of the 45-kb units are arranged as direct tandem repeats. Others appear to be in inverted orientation with respect to a neighboring unit. Cloned major urinary protein genes show few incidences of the repetitive elements B1, B2, R, and MIF. Two elements, a B1 and an R, may be a constant feature of the 45-kb units. If so, in those cases in which the units are in tandem array, both of these elements will occur with a 45-kb periodicity. A comparison of corresponding parts of different 45-kb units shows that they differ because of a number of deletion or insertion events, particularly in the regions 3' to the genes.

  13. Size, distribution and sediment biodeposition of prolific bivalves in small estuaries

    NASA Astrophysics Data System (ADS)

    Callaway, Ruth; Grenfell, Suzanne; Bertelli, Chiara; Mendzil, Anouska; Moore, Jon

    2014-10-01

    The growth and distribution of bivalves in estuaries is generally driven by access to food, hydrodynamic forces and sedimentary conditions that facilitate recruitment and allow persistent settlement. Factors such as site elevation or sediment properties have a significant impact, but there are few studies quantifying the relative importance of different factors in an entire estuary. We carried out an estuary-wide survey of the cockle Cerastoderma edule L. by sampling 343 sites in a small estuary, the Burry Inlet in South Wales, UK. We determined the extent to which site elevation, as an indicator for the duration of feeding, sediment properties and position inside the estuary, explained variation in the size and density of the bivalve. We also analysed the production of faeces and pseudo-faeces per cockle. The population consisted almost entirely of 1-year old cockles, the average size was 14.7 ± 2.7 mm and the average density was 56 ± 189 cockles 0.1 m-2 (mean ± SD). Altogether 37% of the variation in size was explained by two factors: elevation of site (15%) and amount of clay & silt in sediments (22%). Variation in density appeared to play no significant role in determining size. Density was significantly linked to sediment properties (32%) and position inside the estuary (4%). Sediment biodeposition, the amount of material discharged per cockle, was 0.032 ± 0.017 g dry weight, the whole population thereby producing an estimated 387 tonnes of faeces and pseudo-faeces in the entire estuary per day. The study confirmed that access to food is a principal driver of growth, but the relatively small proportion of the variation in size explained by site elevation highlights that other factors play an important role. Sediment characteristics in particular were of importance to variation in size as well as density. It seems plausible that sediment properties were a proxy for factors such as bedload movement and exposure, which are more likely causal factors for

  14. Uncharted waters: Bivalves of midway atoll and integrating mathematics into biology education

    NASA Astrophysics Data System (ADS)

    McCully, Kristin M.

    To protect and conserve the Earth's biodiversity and ecosystem services, it is important not only to understand and conserve species and ecosystems, but also to instill an understanding and appreciation for biodiversity and ecosystem services in the next generations of both scientists and citizens. Thus, this dissertation combines research into the ecology and identity of large bivalves at Midway Atoll in the Northwestern Hawaiian Islands (NWHI) with research on pedagogical strategies for integrating mathematics into undergraduate biology education. The NWHI is one of the few remaining large, mainly intact, predator-dominated coral reef ecosystems and one of the world's largest marine protected areas. Previous bivalve studies focused on the black-lipped pearl oyster, Pinctada margaritifera, which was heavily harvested in the late 1920s, has not recovered, and is now a candidate species for restoration. First, I combined remote sensing, geographic information systems, SCUBA, and mathematical modeling to quantify the abundance, spatial distributions, and filtration capacity of large epifaunal bivalves at Midway Atoll. These bivalves are most abundant on the forereef outside the atoll, but densities are much lower than reported on other reefs, and Midway's bivalves are unlikely to affect plankton abundance and productivity inside the lagoon. Second, I used molecular techniques and phylogenetic reconstructions to identify pearl oysters (Pinctada) from Midway Atoll as P. maculata , a species not previously reported in Hawaii. As a small morphologically cryptic species, P. maculata may be a native species that has not been collected previously, a native species that has been identified incorrectly as the morphologically similar P. radiata, or it may be a recent introduction or natural range extension from the western Pacific. Finally, I review science education literature integrating mathematics into undergraduate biology curricula, and then present and evaluate a

  15. Museum Preserved Bivalves as Indicators of Long-term Trends in Methylmercury Concentrations

    NASA Astrophysics Data System (ADS)

    Luengen, A. C.; Foslund, H. M.; Greenfield, B. K.

    2015-12-01

    Despite the many efforts to reduce mercury concentrations in the environment, there are relatively few datasets on long-term trends in mercury in biota, especially for the bioavailable form, methylmercury (MeHg). This study used museum preserved bivalves (stored in ethanol) to look at MeHg trends in the Asian date mussel Musculista senhousia and the Asian clam Potamocorbula amurensis, collected from San Francisco Bay, California between 1975 and 2012. For each sampling date, 4 to 15 individuals were obtained from museum collections (N = 156 total specimens), freeze-dried, weighed, homogenized, digested, and individually analyzed for MeHg using trace metal clean techniques. The bivalves were also analyzed for δ13C and δ15N to look for changes in food web structure. P. amurensis specimens were only available from 1988 to 2012, and an increase in MeHg was observed during that time. In contrast, M. senhousia specimens were available for the entire 37 year period and exhibited a significant decline in MeHg in the southern reach of the estuary (South Bay). The median MeHg concentration in M. senhousia was highest at 239 ng/g dw in October 1975. That year was the last year of operations for the New Almaden Mercury Mining District, which drained into South Bay. By the 1990s, MeHg concentrations in M. senhousia dropped significantly to a median of 37 ng/g dw. Isotopic δ15N values did not support a hypothesis of reduced trophic position causing the MeHg decline. Over the study duration, δ15N increased in M. senhousia, which we attributed to a baseline shift. We also observed a decline in δ13C since 2000, which may represent a shift in bivalve carbon towards greater utilization of planktonic sources. To validate the use of museum specimens, we ran a preservation study, where we collected fresh bivalves, fixed them in ethanol or formalin, and then transferred them to ethanol for long-term storage. Although MeHg concentrations increased after 1 week, they stabilized over

  16. Tracing Cd, Zn and Pb pollution sources in bivalves using isotopes

    NASA Astrophysics Data System (ADS)

    Shiel, A. E.; Weis, D. A.; Orians, K. J.

    2010-12-01

    In a multi-tracer study, Cd, Zn and Pb isotopes (MC-ICP-MS) and elemental concentrations (HR-ICP-MS) are evaluated as tools to distinguish between natural and anthropogenic sources of these metals in bivalves from western Canada (British Columbia), the eastern USA, Hawaii and France. High Cd concentrations found in BC oysters have elicited economic and health concerns. The source of these high Cd levels is unknown but thought to be largely natural. High Cd levels in BC oysters are largely attributed to the natural upwelling of Cd-rich intermediate waters in the North Pacific as the δ114/110Cd (-0.69 to -0.09‰) and δ66/64Zn (0.28 to 0.36‰) values of BC oysters fall within the range reported for North Pacific seawater. Different contributions from anthropogenic sources account for the variability of Cd isotopic compositions of BC oysters; the lightest of these oysters are from the BC mainland. These oysters also have Pb isotopic compositions that reflect primarily anthropogenic sources (e.g., leaded and unleaded automotive gasoline and smelting of Pb ores, potentially historical). On the contrary, USA East Coast bivalves exhibit relatively light Cd isotopic compositions (δ114/110Cd = -1.20 to -0.54‰; lighter than reported for North Atlantic seawater) due to the high prevalence of industry on this coast. The Pb isotopic compositions of these bivalves indicate contributions from the combustion of coal. The large variability of environmental health among coastal areas in France is reflected in the broad range of Cd isotopic compositions exhibited by French bivalves (δ114/110Cd = -1.08 to -0.20‰). Oysters and mussels from the Marennes-Oléron basin and Gironde estuary have the lightest Cd isotopic compositions of the French oysters consistent with significant historical Cd emissions from the now-closed proximal Zn smelter. In these bivalves, significant declines in the Cd levels between 1984/7 and 2004/5 are not accompanied by a significant shift in the Cd

  17. Assessment of ametryn contamination in river water, river sediment, and mollusk bivalves in São Paulo state, Brazil.

    PubMed

    Jacomini, Analu Egydio; de Camargo, Plínio Barbosa; Avelar, Wagner Eustáquio Paiva; Bonato, Pierina Sueli

    2011-04-01

    São Paulo state, Brazil, is one of the main areas of sugar cane agriculture in the world. Herbicides, in particular, ametryn, are extensively used in this extensive area, which implies that this herbicide is present in the environment and can contaminate the surface water by running off. Thereby, residues of ametryn were analyzed in samples of river water an river sediment and in freshwater bivalves obtained from the rivers Sapucaí, Pardo and Mogi-Guaçu in São Paulo State, Brazil. Samples were taken in the winter of 2003 and 2004 in two locations in each river. The specimens of freshwater bivalves collected and analyzed were Corbicula fluminea, an exotic species, and Diplodon fontaineanus, a native species. Additionally, the evaluation of the ability of bioconcentration and depuration of ametryn by the freshwater bivalve Corbicula fluminea was also performed. Ametryn concentrations in the samples were measured by liquid chromatography coupled to mass spectrometry. Residues of ametryn in water (50 ng/L) and in freshwater bivalves (2-7 ng/g) were found in the Mogi-Guaçu River in 2004, and residues in river sediments were found in all rivers in 2003 and 2004 (0.5-2 ng/g). The observation of the aquatic environment through the analysis of these matrixes, water, sediment, and bivalves, revealed the importance of the river sediment in the accumulation of the herbicide ametryn, which can contaminate the biota.

  18. Validating the Incorporation of 13C and 15N in a Shorebird That Consumes an Isotopically Distinct Chemosymbiotic Bivalve

    PubMed Central

    van Gils, Jan A.; Ahmedou Salem, Mohamed Vall

    2015-01-01

    The wealth of field studies using stable isotopes to make inferences about animal diets require controlled validation experiments to make proper interpretations. Despite several pleas in the literature for such experiments, validation studies are still lagging behind, notably in consumers dwelling in chemosynthesis-based ecosystems. In this paper we present such a validation experiment for the incorporation of 13C and 15N in the blood plasma of a medium-sized shorebird, the red knot (Calidris canutus canutus), consuming a chemosymbiotic lucinid bivalve (Loripes lucinalis). Because this bivalve forms a symbiosis with chemoautotrophic sulphide-oxidizing bacteria living inside its gill, the bivalve is isotopically distinct from ‘normal’ bivalves whose food has a photosynthetic basis. Here we experimentally tested the hypothesis that isotope discrimination and incorporation dynamics are different when consuming such chemosynthesis-based prey. The experiment showed that neither the isotopic discrimination factor, nor isotopic turnover time, differed between birds consuming the chemosymbiotic lucinid and a control group consuming a photosynthesis-based bivalve. This was true for 13C as well as for 15N. However, in both groups the 15N discrimination factor was much higher than expected, which probably had to do with the birds losing body mass over the course of the experiment. PMID:26458005

  19. A gigantic Bezymianny-type event at the beginning of modern volcan Popocatepetl

    NASA Astrophysics Data System (ADS)

    Robin, Claude; Boudal, Christian

    1987-03-01

    The history of volcan Popocatepetl can be divided into two main periods: the formation of a large primitive volcano — approximatively 30 km wide — on which is superimposed a modern cone (6-8 km in diameter and 1700m high). A major event of Bezymianny type marks the transition between these two dissimilar periods. The activity of the primitive volcano was essentially effusive and lasted several hundred thousands of years. The total volume of products ejected by the volcano is of the order of 500-600 km 3. Its last differentiated magmas are dacitic. A gigantic debris flow (D.F.) spread on the southern side is related to the Bezymianny-type event which destroyed the summit area of the ancient edifice. An elliptical caldera ( ⋍ 6.5 × 11 km wide) was formed by the landslide. Its deposits, with a typical hummocky surface, cover 300 km 2 for a volume of 28-30 km 3. Numerous outcrops belonging to this debris flow show "slabs" of more or less fractured and dislocated rocks that come from the primitive volcano. These deposits are compared to two studied debris flows of similar extent and volume: the Mount Shasta and Colima's D.F. This eruption takes a major place in the volcanologic and magmatic history of Popocatepetl: pyroclastic products of surge-type with "laminites" and crude layers, ashflows, and pumiceous airfall layers are directly related to this event and begin the history of the modern volcano probably less than 50,000 years ago. In addition, a second andesitic and dacitic phase rose both from the central vent — forming the basis of modern Popo — and from lateral vents. The terminal cone is characterized by long periods of construction by lava flows alternating with phases of destruction, the duration of these episodes being 1000 to 2000 years. The cone is composed of two edifices: the first, volcan El Fraile, began with effusive activity and was partly destroyed by three periods of intense explosive activity. The first period occurred prior to 10

  20. Successful endovascular treatment of a ruptured gigantic pseudoaneurysm of the common iliac artery secondarily complicated by infection.

    PubMed

    Georgakarakos, Efstratios I; Nikolopoulos, Evagelos S; Karanikas, Michael A; Mantatzis, Michalis; Lazarides, Miltos K

    2013-06-01

    We report our experience with a case of emergent endovascular treatment of a large ruptured pseudoaneurysm of the common iliac artery. A 65-year-old male was admitted to the surgical department in hypovolemic shock, due to active retroperitoneal bleeding. A computerized tomography scan with intravenous contrast revealed a ruptured gigantic pseudoaneurysm of the right common iliac artery, with a maximal diameter of 7 cm and retroperitoneal hematoma. An intraoperative angiogram revealed active extravasation through the neck of the pseudoaneurysm, which was successfully sealed with the placement of a stent graft (Medtronic Endurant(®))limb component. Infection of the pseudoaneurysm sac after one month was successfully treated with catheter drainage. No shortterm relapse occurred. Endovascular management should be part of the basic surgical armamentarium on emergent basis, since it provides a fast and safe solution, especially when a patient's co-morbitities preclude open management and hemodynamic and anatomical status allows endovascular treatment. PMID:22983544

  1. System of gigantic valleys northwest of Tharsis, Mars: Latent catastrophic flooding, northwest watershed, and implications for northern plains ocean

    USGS Publications Warehouse

    Dohm, J.M.; Anderson, R.C.; Baker, V.R.; Ferris, J.C.; Hare, T.M.; Strom, R.G.; Rudd, L.P.; Rice, J. W.; Casavant, R.R.; Scott, D.H.

    2000-01-01

    Mars Orbiter Laser Altimeter (MOLA) reveals a system of gigantic valleys to the northwest of the huge martian shield volcano, Arsia Mons, in the western hemisphere of Mars. These newly identified northwestern slope valleys (NSVs) potentially signify previously undocumented martian catastrophic floods and may corroborate the northern ocean hypotheses. These features, which generally correspond spatially to gravity lows, were previously obscurred in Mariner and Viking Orbiter imagery by veneers of materials, including volcanic lava flows and air fall deposits. Geologic investigations of the Tharsis region suggest that the NSVs were mainly carved prior to the construction of Arsia Mons and its associated Late Hesperian and Amazonian age lava flows, concurrent with the early development of the outflow channels that debouch into Chryse Planitia.

  2. Cyproheptadine-mediated inhibition of growth hormone and prolactin release from pituitary adenoma cells of acromegaly and gigantism in culture.

    PubMed

    Ishibashi, M; Fukushima, T; Yamaji, T

    1985-08-01

    The effect of cyproheptadine on growth hormone (GH) and prolactin (Prl) secretion from cultured pituitary adenoma cells of acromegaly and pituitary gigantism was studied. When varying doses of cyproheptadine ranging from 0.01 to 1 microM were added to the incubation media, GH secretion was consistently inhibited and a dose-response relationship was observed between the cyproheptadine concentrations and the amounts of GH released into the media. In pituitary adenomas which concurrently produced and secreted Prl, cyproheptadine likewise suppressed Prl release in a dose-related manner. This effect of cyproheptadine was not blocked by coincubation with serotonin. Similarly, coincubation with a dopaminergic antagonist, haloperidol, failed to reverse the inhibitory action produced by cyproheptadine. When coincubated with dopamine, cyproheptadine further inhibited GH and Prl secretion. These results suggest that cyproheptadine possesses a direct action on human somatotroph adenoma cells to inhibit GH and Prl secretion by an unknown mechanism that is different from serotonergic and dopaminergic systems. PMID:2994332

  3. PBDEs, hydroxylated PBDEs and methoxylated PBDEs in bivalves from Beijing markets.

    PubMed

    Liu, Xitao; Jiao, Ying; Lin, Chunye; Sun, Ke; Zhao, Ye

    2014-09-01

    The structural analogues of polybrominated diphenyl ethers (PBDEs), hydroxylated PBDEs (OH-PBDEs) and methoxylated PBDEs (MeO-PBDEs) have been attracting increasing concern in recent years. Five bivalve species (blue mussel, short-necked clam, surf clam, ark shell and razor clam) were collected from Beijing markets, and the concentrations of seven PBDEs, four OH-PBDEs and fourteen MeO-PBDEs in the bivalves were measured. The seasonal variations of these three types of polybrominated compound in blue mussels were also monitored. The results indicate that the levels of ΣPBDEs in this study were comparable to those in short-necked clams from Liaodong Bay, China, with BDE47 as the dominant congener. For the ortho-MeO-PBDEs, 6-MeO-BDE47 was found at higher concentrations than the others, while for the meta- and para-MeO-PBDEs, 4'-MeO-BDE17 was found at higher concentrations. 6-OH-BDE-47 was the most abundant congener among the 4 measured OH-PBDEs, followed by 6-OH-BDE-137 and 6-OH-BDE-85. The levels of OH-PBDEs and MeO-PBDEs in bivalves from Beijing markets were much lower than the corresponding compounds in blue mussels from the Baltic Sea. In the blue mussels collected in April, June and September of 2012, apparent seasonal variations were observed for these three types of polybrominated compounds, but the acidic components displayed different trends from the neutral components, with PBDEs and MeO-PBDEs showing the highest concentrations in June, while OH-PBDEs had the lowest concentrations in June. This difference in seasonal variations between the neutral components and the acidic components may be explained by their different sources and transformation/elimination mechanisms.

  4. Bivalve shells as high resolution biomineral archives of early Pleistocene seasonality

    NASA Astrophysics Data System (ADS)

    Crippa, Gaia; Angiolini, Lucia; Leng, Melanie

    2016-04-01

    Bivalves are among the best tools for palaeoclimatic and palaeoenvironmental reconstructions because they are known to precipitate their shells in isotopic equilibrium with the seawater in which they live. Also, the analysis of their shell microstructure shows that these organisms modify their shell fabric in response to environmental variations forming growth lines. However, diagenetic processes may alter fossil bivalve shell microstructure and shell isotopic composition; for this reason it is important to perform screening tests to check if the shell is pristine and thus confidently identify biogenic calcium carbonate as a reliable proxy of primary seawater chemistry. Here, we performed a detailed study of the microstructure of ten aragonite bivalves shells belonging to Glycymeris insubrica, Glycymeris inflata and Arctica islandica, collected from the lower Pleistocene Arda River marine succession (northern Italy), to check their preservation for subsequent sclerochemical stable isotope analyses (δ18O, δ13C). To assess shell preservation 4 different screening techniques were used: Scanning Electron Microscopy (SEM), Catholuminescence (CL), X-Ray Powder Diffraction (XRD) and Feigl's solution. Shells of species of Glycymeris, under SEM, show an outer crossed lamellar layer, an inner irregular and cone complex crossed lamellar layer and an irregular simple prismatic pallial myostracum; all the layers are penetrated by cylindrical tubules. Arctica islandica has an outer homogenous/crossed lamellar/crossed acicular layer, an inner fine complex crossed lamellar layer and an irregular simple prismatic pallial myostracum. The comparative analysis with recent fabrics shows a consistent pattern for species of both Glycymeris and Arctica genera, the recent and fossils shell microstructures being almost identical. Analyses at CL, XRD and Feigl's solution support that these fossil species have a non luminescent shells composed of pure aragonite. The excellent preservation

  5. P-glycoprotein and its inducible expression in three bivalve species after exposure to Prorocentrum lima.

    PubMed

    Huang, Lu; Liu, Su-Li; Zheng, Jian-Wei; Li, Hong-Ye; Liu, Jie-Sheng; Yang, Wei-Dong

    2015-12-01

    P-glycoprotein (P-gp or ABCB1) belongs to the family of ATP-binding cassette (ABC) transporters responsible for multixenobiotic resistance (MXR) in aquatic organisms. To provide more information of P-gp in shellfish, in this study, complete cDNA of P-gp in three bivalve species including Ruditapes philippinarum, Scapharca subcrenata and Tegillarca granosa were cloned and its expressions in gill, digestive gland, adductor muscle and mantle of the three bivalves were detected after exposure to Prorocentrum lima, a toxogenic dinoflagellate. The complete sequences of R. philippinarum, S. subcrenata and T. granosa P-gp showed high homology with MDR/P-gp/ABCB proteins from other species, having a typical sequence organization as full transporters from the ABCB family. Phylogenetic analyses revealed that the amino acid sequences of P-gp from S. subcrenata and T. granosa had a closest relationship, forming an independent branch, then grouping into the other branch with Mytilus californianus, Mytilus galloprovincialis and Crassostrea gigas. However, P-gp sequences from R. philippinarum were more similar to the homologs from the more distantly related Aplysia californica than to homologs from S. subcrenata and T. granosa, suggesting that bivalves P-gp might have different paralogs. P-glycoprotein expressed in all detected tissues but there were large differences between them. After exposure to P. lima, the expression of P-gp changed in the four tissues in varying degrees within the same species and between different species, but the changes in mRNA and protein level were not always synchronous.

  6. Detection of the oyster herpesvirus in commercial bivalve in northern California, USA: conventional and quantitative PCR.

    PubMed

    Burge, Colleen A; Strenge, Robyn E; Friedman, Carolyn S

    2011-04-01

    The ostreid herpesvirus (OsHV-1) and related oyster herpesviruses (OsHV) are associated with world-wide mortalities of larval and juvenile bivalves. To quantify OsHV viral loads in mollusc tissues, we developed a SYBR Green quantitative PCR (qPCR) based on the A-region of the OsHV-1 genome. Reaction efficiency and precision were demonstrated using a plasmid standard curve. The analytical sensitivity is 1 copy per reaction. We collected Crassostrea gigas, C. sikamea, C. virginica, Ostrea edulis, O. lurida, Mytilus galloprovincialis, and Venerupis phillipinarum from Tomales Bay (TB), and C. gigas from Drakes Estero (DE), California, U.S.A., and initially used conventional PCR (cPCR) to test for presence of OsHV DNA. Subsequently, viral loads were quantified in selected samples of all tested bivalves except O. lurida. Copy numbers were low in each species tested but were significantly greater in C. gigas (p < 0.0001) compared to all other species, suggesting a higher level of infection. OsHV DNA was detected with cPCR and/or qPCR and confirmed by sequencing in C. gigas, C. sikamea, C. virginica, O. edulis, M. galloprovincialis, and V phillipinarum from TB and C. gigas from DE. These data indicate that multiple bivalve species may act as reservoirs for OsHV in TB. A lack of histological abnormalities in potential reservoirs requires alternative methods for their identification. Further investigation is needed to determine the host-parasite relationship for each potential reservoir, including characterization of viral loads and their relationship with infection (via in situ hybridization), assessments of mortality, and host responses. PMID:21648239

  7. P-glycoprotein and its inducible expression in three bivalve species after exposure to Prorocentrum lima.

    PubMed

    Huang, Lu; Liu, Su-Li; Zheng, Jian-Wei; Li, Hong-Ye; Liu, Jie-Sheng; Yang, Wei-Dong

    2015-12-01

    P-glycoprotein (P-gp or ABCB1) belongs to the family of ATP-binding cassette (ABC) transporters responsible for multixenobiotic resistance (MXR) in aquatic organisms. To provide more information of P-gp in shellfish, in this study, complete cDNA of P-gp in three bivalve species including Ruditapes philippinarum, Scapharca subcrenata and Tegillarca granosa were cloned and its expressions in gill, digestive gland, adductor muscle and mantle of the three bivalves were detected after exposure to Prorocentrum lima, a toxogenic dinoflagellate. The complete sequences of R. philippinarum, S. subcrenata and T. granosa P-gp showed high homology with MDR/P-gp/ABCB proteins from other species, having a typical sequence organization as full transporters from the ABCB family. Phylogenetic analyses revealed that the amino acid sequences of P-gp from S. subcrenata and T. granosa had a closest relationship, forming an independent branch, then grouping into the other branch with Mytilus californianus, Mytilus galloprovincialis and Crassostrea gigas. However, P-gp sequences from R. philippinarum were more similar to the homologs from the more distantly related Aplysia californica than to homologs from S. subcrenata and T. granosa, suggesting that bivalves P-gp might have different paralogs. P-glycoprotein expressed in all detected tissues but there were large differences between them. After exposure to P. lima, the expression of P-gp changed in the four tissues in varying degrees within the same species and between different species, but the changes in mRNA and protein level were not always synchronous. PMID:26539802

  8. Molecular Characterization of RXR (Retinoid X Receptor) Gene Isoforms from the Bivalve Species Chlamys farreri

    PubMed Central

    Bao, Zhenmin; Guo, Huihui; Zhang, Yueyue; Jiao, Wenqian; Zhang, Lingling; Wang, Shi; He, Yan; Hu, Xiaoli

    2013-01-01

    Background Bivalves are among the oldest classes of invertebrates, and they exhibit diverse types of sexual patterning. However, our current understanding of the mechanisms of sex determination and differentiation in bivalves remains very limited. The retinoid X receptors (RXRs), which are members of the nuclear receptor family, are involved in sex differentiation in many organisms. Results In the present study, four full-length RXR-encoding cDNAs (CfRXRs) named CfRXRa, CfRXRb, CfRXRc and CfRXRd were retrieved from Zhikong scallop (Chlamys farreri). The four RXRs exhibited the conserved five-domain structure of nuclear receptor superfamily members and differed from each other only in the T-box of the C domain. The three variants, designated T (+4), T (+20) and T (+24), contained insertions of 4, 20 and 24 amino acids, respectively. The entire CfRXR gene is composed of eight exons and seven introns, and the four isoforms are generated via alternative mRNA splicing. Expression analysis showed that all four isoforms were expressed in both the testis and the ovary during the differentiation stage, whereas no expression was detected in the growth, mature or resting stages. This result suggests that CfRXRs are involved in germ cell differentiation in both sexes. The expression of the four isoforms was also detected in other tissues examined, including mantle, gill, digestive gland, and adductor muscle of sexually mature male and female Zhikong scallops, implying the multiple biological functions of CfRXRs. Conclusion Our study presents the first report of RXR isoforms in bivalves. Further investigation of the functional roles of different RXR isoforms may provide deep insights into the regulatory mechanism of sex differentiation in C. farreri. PMID:24066133

  9. Dispersal, environmental niches and oceanic-scale turnover in deep-sea bivalves.

    PubMed

    McClain, Craig R; Stegen, James C; Hurlbert, Allen H

    2012-05-22

    Patterns of beta-diversity or distance decay at oceanic scales are completely unknown for deep-sea communities. Even when appropriate data exist, methodological problems have made it difficult to discern the relative roles of environmental filtering and dispersal limitation for generating faunal turnover patterns. Here, we combine a spatially extensive dataset on deep-sea bivalves with a model incorporating ecological dynamics and shared evolutionary history to quantify the effects of environmental filtering and dispersal limitation. Both the model and empirical data are used to relate functional, taxonomic and phylogenetic similarity between communities to environmental and spatial distances separating them for 270 sites across the Atlantic Ocean. This study represents the first ocean-wide analysis examining distance decay as a function of a broad suite of explanatory variables. We find that both strong environmental filtering and dispersal limitation drive turnover in taxonomic, functional and phylogenetic composition in deep-sea bivalves, explaining 26 per cent, 34 per cent and 9 per cent of the variation, respectively. This contrasts with previous suggestions that dispersal is not limiting in broad-scale biogeographic and biodiversity patterning in marine systems. However, rates of decay in similarity with environmental distance were eightfold to 44-fold steeper than with spatial distance. Energy availability is the most influential environmental variable evaluated, accounting for 3.9 per cent, 9.4 per cent and 22.3 per cent of the variation in functional, phylogenetic and taxonomic similarity, respectively. Comparing empirical patterns with process-based theoretical predictions provided quantitative estimates of dispersal limitation and niche breadth, indicating that 95 per cent of deep-sea bivalve propagules will be able to persist in environments that deviate from their optimum by up to 2.1 g m(-2) yr(-1) and typically disperse 749 km from their natal site.

  10. Improving management support tools for reintroducing bivalve species (eastern oyster [Crassostrea virginica Gmelin]) in urban estuaries.

    PubMed

    Ravit, Beth; Cooper, Keith; Buckley, Brian; Comi, Meredith; McCandlish, Elizabeth

    2014-10-01

    Successful reintroduction of "ecologically extinct" bivalve species into anthropogenically impaired urban estuaries is problematic when employing existing management tools used in estuaries where bivalves are present (GIS-based restoration models, expanding existing shellfish beds, placement of shell substrate, physical oceanographic parameters). A significant management challenge is appropriate site selection. We are proposing the inclusion of a biological parameter (evaluation of tissue histopathology) in an inexpensive and rapid site selection model to inform management decision making and identify sites with the greatest potential for reintroduction success. Use of biological biomarkers is not a new concept, but it is important that they be included in a multitiered management approach to bivalve reintroduction. This Case Study tested adult Eastern Oysters (Crassostrea virginica Gmelin) from locations that supported comparable short-term survival rates by evaluating growth and tissue health and/or disease. Biomarkers indicated oyster tissues at one site were normal, the female:male sex ratio was 50:50, and female oysters were in spawning condition. Conversely, oyster tissues at the second site exhibited multiple abnormalities, samples were 100% male, and the incidence of disease was high. Using the biomarker tool, we evaluated 4 additional sites where oysters exhibited short-term (1 year) survival. At 2 locations, we observed chronic health impacts that would preclude reintroduction, including samples from one site where a wild population was surviving. We also analyzed tissue and shell heavy metal contents. Soft tissue metal concentrations in Meadowlands samples were at the high range of scientific literature values, averaging 1.1% of total body weight, whereas tissue metal concentrations at the Keyport site were within acceptable ranges. Although initial survival and growth rates at both locations were comparable, site-specific urban stressors reduced oyster

  11. Distribution of persistent toxic substances in benthic bivalves from the inshore areas of the Yellow Sea.

    PubMed

    Liu, Wen X; Hu, Jing; Chen, Jiang L; Fan, Yong S; Xing, Baoshan; Tao, Shu

    2008-01-01

    A baseline survey of trace metals and organic pollutants in bivalves from the coastal areas of the Yellow Sea (China) showed the the concentrations of Cd and Pb in the bivalves from more than 85 and 73%, respectively, of the total sites (30 sites in all) exceeded the low limits of the national quality standards for marine organisms. At three sites, the contents of Cd in three species were even higher than the median limit, and a similar case with Pb occurred at another site. The tissue concentrations of As at four sites and of Hg at one site were above the low and the median limits, respectively, of the quality standards. At 43% of all sites, the levels of petroleum hydrocarbons were higher than the low limit of the quality standards, and the tissue concentrations at two sites even went beyond the median limit at one site and the high limit at the other. The concentrations of phthalate esters and polycyclic aromatic hydrocarbons (PAHs) in the collected bivalves were not high, as shown by peak values of 305 and 302 ng/g, respectively. The contents of polychlorinated biphenyls for all the species were much lower than the low limit of the quality standards. The compositional properties and isomeric ratios of PAHs indicated various pyrolytic procedures as the dominant origins. The sites with higher tissue contents of DDT and its metabolites (DDTs) over the low or the median quality limit were located mainly in the South Yellow Sea. The fractions and specific ratios of DDTs suggested that new inputs of DDT existed at two sites in the North Yellow Sea, and the potential sources involved technical DDT, technical dicofol, and their mixture.

  12. Aggressive tumor growth and clinical evolution in a patient with X-linked acro-gigantism syndrome.

    PubMed

    Naves, Luciana A; Daly, Adrian F; Dias, Luiz Augusto; Yuan, Bo; Zakir, Juliano Coelho Oliveira; Barra, Gustavo Barcellos; Palmeira, Leonor; Villa, Chiara; Trivellin, Giampaolo; Júnior, Armindo Jreige; Neto, Florêncio Figueiredo Cavalcante; Liu, Pengfei; Pellegata, Natalia S; Stratakis, Constantine A; Lupski, James R; Beckers, Albert

    2016-02-01

    X-linked acro-gigantism (X-LAG) syndrome is a newly described disease caused by microduplications on chromosome Xq26.3 leading to copy number gain of GPR101. We describe the clinical progress of a sporadic male X-LAG syndrome patient with an Xq26.3 microduplication, highlighting the aggressive natural history of pituitary tumor growth in the absence of treatment. The patient first presented elsewhere aged 5 years 8 months with a history of excessive growth for >2 years. His height was 163 cm, his weight was 36 kg, and he had markedly elevated GH and IGF-1. MRI showed a non-invasive sellar mass measuring 32.5 × 23.9 × 29.1 mm. Treatment was declined and the family was lost to follow-up. At the age of 10 years and 7 months, he presented again with headaches, seizures, and visual disturbance. His height had increased to 197 cm. MRI showed an invasive mass measuring 56.2 × 58.1 × 45.0 mm, with compression of optic chiasma, bilateral cavernous sinus invasion, and hydrocephalus. His thyrotrope, corticotrope, and gonadotrope axes were deficient. Surgery, somatostatin analogs, and cabergoline did not control vertical growth and pegvisomant was added, although vertical growth continues (currently 207 cm at 11 years 7 months of age). X-LAG syndrome is a new genomic disorder in which early-onset pituitary tumorigenesis can lead to marked overgrowth and gigantism. This case illustrates the aggressive nature of tumor evolution and the challenging clinical management in X-LAG syndrome. PMID:26607152

  13. On the shoulders of giants: Harvey Cushing's experience with acromegaly and gigantism at the Johns Hopkins Hospital, 1896-1912.

    PubMed

    Pendleton, Courtney; Adams, Hadie; Salvatori, Roberto; Wand, Gary; Quiñones-Hinojosa, Alfredo

    2011-03-01

    A review of Dr. Cushing's surgical cases at Johns Hopkins Hospital revealed new information about his early operative experience with acromegaly. Although in 1912 Cushing published selective case studies regarding this work, a review of all his operations for acromegaly during his early years has never been reported. We uncovered 37 patients who Cushing treated with surgical intervention directed at the pituitary gland. Of these, nine patients who presented with symptoms of acromegaly, and one with symptoms of gigantism were selected for further review. Two patients underwent transfrontal 'omega incision' approaches, and the remaining eight underwent transsphenoidal approaches. Of the 10 patients, 6 were male. The mean age was 38.0 years. The mean hospital stay was 39.4 days. There was one inpatient death during primary interventions (10%) and three patients were deceased at the time of last follow-up (33%). The mean time to death, calculated from the date of the primary surgical intervention, and including inpatient and outpatient deaths, was 11.3 months. The mean time to last follow-up, calculated from the day of discharge, was 59.3 months. At the time of last follow-up, two patients reported resolution of headache; four patients reported continued visual deficits, and two patients reported ongoing changes in mental status. This review analyzes the outcomes for 10 patients who underwent surgical intervention for acromegaly or gigantism, and offers an explanation for Cushing's transition from the transfrontal "omega incision" to the transsphenoidal approach while practicing at the Johns Hopkins Hospital. PMID:20821269

  14. On the shoulders of giants: Harvey Cushing's experience with acromegaly and gigantism at the Johns Hopkins Hospital, 1896-1912.

    PubMed

    Pendleton, Courtney; Adams, Hadie; Salvatori, Roberto; Wand, Gary; Quiñones-Hinojosa, Alfredo

    2011-03-01

    A review of Dr. Cushing's surgical cases at Johns Hopkins Hospital revealed new information about his early operative experience with acromegaly. Although in 1912 Cushing published selective case studies regarding this work, a review of all his operations for acromegaly during his early years has never been reported. We uncovered 37 patients who Cushing treated with surgical intervention directed at the pituitary gland. Of these, nine patients who presented with symptoms of acromegaly, and one with symptoms of gigantism were selected for further review. Two patients underwent transfrontal 'omega incision' approaches, and the remaining eight underwent transsphenoidal approaches. Of the 10 patients, 6 were male. The mean age was 38.0 years. The mean hospital stay was 39.4 days. There was one inpatient death during primary interventions (10%) and three patients were deceased at the time of last follow-up (33%). The mean time to death, calculated from the date of the primary surgical intervention, and including inpatient and outpatient deaths, was 11.3 months. The mean time to last follow-up, calculated from the day of discharge, was 59.3 months. At the time of last follow-up, two patients reported resolution of headache; four patients reported continued visual deficits, and two patients reported ongoing changes in mental status. This review analyzes the outcomes for 10 patients who underwent surgical intervention for acromegaly or gigantism, and offers an explanation for Cushing's transition from the transfrontal "omega incision" to the transsphenoidal approach while practicing at the Johns Hopkins Hospital.

  15. Aggressive tumor growth and clinical evolution in a patient with X-linked acro-gigantism syndrome.

    PubMed

    Naves, Luciana A; Daly, Adrian F; Dias, Luiz Augusto; Yuan, Bo; Zakir, Juliano Coelho Oliveira; Barra, Gustavo Barcellos; Palmeira, Leonor; Villa, Chiara; Trivellin, Giampaolo; Júnior, Armindo Jreige; Neto, Florêncio Figueiredo Cavalcante; Liu, Pengfei; Pellegata, Natalia S; Stratakis, Constantine A; Lupski, James R; Beckers, Albert

    2016-02-01

    X-linked acro-gigantism (X-LAG) syndrome is a newly described disease caused by microduplications on chromosome Xq26.3 leading to copy number gain of GPR101. We describe the clinical progress of a sporadic male X-LAG syndrome patient with an Xq26.3 microduplication, highlighting the aggressive natural history of pituitary tumor growth in the absence of treatment. The patient first presented elsewhere aged 5 years 8 months with a history of excessive growth for >2 years. His height was 163 cm, his weight was 36 kg, and he had markedly elevated GH and IGF-1. MRI showed a non-invasive sellar mass measuring 32.5 × 23.9 × 29.1 mm. Treatment was declined and the family was lost to follow-up. At the age of 10 years and 7 months, he presented again with headaches, seizures, and visual disturbance. His height had increased to 197 cm. MRI showed an invasive mass measuring 56.2 × 58.1 × 45.0 mm, with compression of optic chiasma, bilateral cavernous sinus invasion, and hydrocephalus. His thyrotrope, corticotrope, and gonadotrope axes were deficient. Surgery, somatostatin analogs, and cabergoline did not control vertical growth and pegvisomant was added, although vertical growth continues (currently 207 cm at 11 years 7 months of age). X-LAG syndrome is a new genomic disorder in which early-onset pituitary tumorigenesis can lead to marked overgrowth and gigantism. This case illustrates the aggressive nature of tumor evolution and the challenging clinical management in X-LAG syndrome.

  16. The ecological role of bivalve shellfish aquaculture in the estuarine environment: A review with application to oyster and clam culture in West Coast (USA) estuaries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aquaculture is viewed as a potential mechanism to meet the growing demand for seafood around the world. The future of bivalve shellfish aquaculture in the U.S. hinges on sustainable practices on the part of industry and a more consistent regulatory regime. Bivalve shellfish aquaculture is a recent...

  17. [Nutrition and biological value of food parts of a trade bivalve mollusk Anadara broughtoni].

    PubMed

    Tabakaeva, O V; Tabakaev, A V

    2015-01-01

    Currently, the human diet includes different new products of seafishing, including non-fish--bivalves and gastropods, holothurias, echinoderms, jellyfishes that demands careful studying of their chemical composition. The purpose of the study was to determine the nutritional and biological value of all soft parts of the burrowing bivalve MOLLUSK Anadara broughtoni from the Far East region. It was established thatfood parts of a bivalve were significantly flooded (water content--73.5-84.2%), with the minimum water content in the adductor and maximum in the mantle. Dry solids are presented by organic (89-93%) and mineral (7-11%) components. Organic components consist of protein (14.6-20.7%), lipids (1.8-2.3%), carbohydrates (2.1-2.6%). The analysis of amino-acid composition of proteins of food parts of the mollusk of Anadara broughtonishowed the presence of all essential amino acids with slight differences in their content depending on the localization of the protein. All edible parts have tryptophan as the limiting amino acid. Muscle proteins have maximum level of lysine, methionine, cysteine, phenylalanine and tyrosine; mantle proteins--leucine, isoleucine and threonine; adductor proteins--valine, phenylalanine, tyrosine, methionine and cysteine. Predominant nonessential amino acids forproteins of all food pieces are glycine, aspartic acid, glutamic acid, arginine. The coefficient of amino-acid score differences of adductor protein (31.7%) is less than the same of cloak by 3.7%. The indicator "biological value" is maximal for adductor (68.3%), but the differenceformuscle is only 0.83%. Mantle proteins are characterized by minimum biological value (64.6%). The coefficient of utility of amino acid composition of protein is maximalfor muscle (57.83%), and values for a cloak and an adductor differ slightly (55.81 and 55.96%). Taurine content in food parts of a mollusk Anadara broughtoni is rather high compared to with other bivalve mollusks of the Far East region

  18. Bivalve growth rate and isotopic variability across the Barents Sea Polar Front

    NASA Astrophysics Data System (ADS)

    Carroll, Michael L.; Ambrose, William G.; Locke V, William L.; Ryan, Stuart K.; Johnson, Beverly J.

    2014-02-01

    Analysis of bivalve shell increments provides a means to reconstruct long-term patterns in growth histories and assess factors that regulate marine ecosystems, while tissue stable isotopes are indicators of food sources and trophic dynamics. We examined shell growth patterns and tissue stable isotopic composition (δ13C and δ15N) of the hairy cockle (Ciliatocardium ciliatum) in the northwest Barents Sea to evaluate the influence of different water masses and the Polar Front on growth rates and food sources and to assess the influence of climatic variability on ecological processes over seasonal to decadal scales. Shell growth rates were highest in Atlantic water, intermediate in Arctic water, and lowest at the Polar Front. Temporal patterns of ontogenetically-adjusted growth (SGI) were negatively correlated with the Atlantic Multidecadal Oscillation (AMO), local precipitation and ice-free days. The highest growth occurred during colder periods with more sea ice, while lower growth was associated with warmer periods and less sea ice. Stable isotope values of lipid-extracted tissues from Atlantic water cockles were enriched in δ13C by up to 2.1‰ and δ15N by 1.5‰ compared to animals from Arctic waters. Distinct seasonal and water mass variations in stable isotopic values reflect spatial and temporal variability in food supplies to the bivalves in this region on small spatial scales. Overall, Atlantic waters supported the highest growth rates, the most complex trophic webs, and the greatest sensitivity to interannual variability in environmental conditions. Bivalves from Arctic waters were the most distinct of the three groups in their response to regional climate forcing and local environmental manifestations of those conditions. The Polar Front exhibits growth and isotopic characteristics predominantly of the Atlantic domain. These results demonstrate that integrating results of sclerochronological and stable isotopic analyses of benthic bivalves provide

  19. Host-parasite interactions: Marine bivalve molluscs and protozoan parasites, Perkinsus species.

    PubMed

    Soudant, Philippe; E Chu, Fu-Lin; Volety, Aswani

    2013-10-01

    This review assesses and examines the work conducted to date concerning host and parasite interactions between marine bivalve molluscs and protozoan parasites, belonging to Perkinsus species. The review focuses on two well-studied host-parasite interaction models: the two clam species, Ruditapes philippinarum and R. decussatus, and the parasite Perkinsus olseni, and the eastern oyster, Crassostrea virginica, and the parasite Perkinsus marinus. Cellular and humoral defense responses of the host in combating parasitic infection, the mechanisms (e.g., antioxidant enzymes, extracellular products) employed by the parasite in evading host defenses as well as the role of environmental factors in modulating the host-parasite interactions are described.

  20. Differential production of active oxygen species in photo-symbiotic and non-symbiotic bivalves.

    PubMed

    Nakayama, K; Maruyama, T

    1998-01-01

    We investigated the generation of active oxygen species in the bivalves, Crassostrea gigas, Fulvia mutica and Tridacna crocea in order to understand the defensive mechanisms in giant clams that allow a stable association with symbiotic zooxanthellae. C. gigas produced active oxygens, superoxide anion and nitric oxide upon stimulation by phorbol myristate acetate. F. mutica generated a little amount of superoxide anion and nitric oxide, and contained significant phenoloxidase activity which catalyzes formation of quinones. T. crocea did not generate any apparent active oxygen species or quinones. The importance of lacking rapid cytotoxic responses consisting of active oxygen species to foreign organisms in the symbiotic clam is discussed.

  1. [Nutrition and biological value of food parts of a trade bivalve mollusk Anadara broughtoni].

    PubMed

    Tabakaeva, O V; Tabakaev, A V

    2015-01-01

    Currently, the human diet includes different new products of seafishing, including non-fish--bivalves and gastropods, holothurias, echinoderms, jellyfishes that demands careful studying of their chemical composition. The purpose of the study was to determine the nutritional and biological value of all soft parts of the burrowing bivalve MOLLUSK Anadara broughtoni from the Far East region. It was established thatfood parts of a bivalve were significantly flooded (water content--73.5-84.2%), with the minimum water content in the adductor and maximum in the mantle. Dry solids are presented by organic (89-93%) and mineral (7-11%) components. Organic components consist of protein (14.6-20.7%), lipids (1.8-2.3%), carbohydrates (2.1-2.6%). The analysis of amino-acid composition of proteins of food parts of the mollusk of Anadara broughtonishowed the presence of all essential amino acids with slight differences in their content depending on the localization of the protein. All edible parts have tryptophan as the limiting amino acid. Muscle proteins have maximum level of lysine, methionine, cysteine, phenylalanine and tyrosine; mantle proteins--leucine, isoleucine and threonine; adductor proteins--valine, phenylalanine, tyrosine, methionine and cysteine. Predominant nonessential amino acids forproteins of all food pieces are glycine, aspartic acid, glutamic acid, arginine. The coefficient of amino-acid score differences of adductor protein (31.7%) is less than the same of cloak by 3.7%. The indicator "biological value" is maximal for adductor (68.3%), but the differenceformuscle is only 0.83%. Mantle proteins are characterized by minimum biological value (64.6%). The coefficient of utility of amino acid composition of protein is maximalfor muscle (57.83%), and values for a cloak and an adductor differ slightly (55.81 and 55.96%). Taurine content in food parts of a mollusk Anadara broughtoni is rather high compared to with other bivalve mollusks of the Far East region

  2. Soundscapes and Larval Settlement: Larval Bivalve Responses to Habitat-Associated Underwater Sounds.

    PubMed

    Eggleston, David B; Lillis, Ashlee; Bohnenstiehl, DelWayne R

    2016-01-01

    We quantified the effects of habitat-associated sounds on the settlement response of two species of bivalves with contrasting habitat preferences: (1) Crassostrea virginicia (oyster), which prefers to settle on other oysters, and (2) Mercenaria mercenaria (clam), which settles on unstructured habitats. Oyster larval settlement in the laboratory was significantly higher when exposed to oyster reef sound compared with either off-reef or no-sound treatments. Clam larval settlement did not vary according to sound treatments. Similar to laboratory results, field experiments showed that oyster larval settlement in "larval housings" suspended above oyster reefs was significantly higher compared with off-reef sites.

  3. Comparative sensitivity of European native (Anodonta anatina) and exotic (Corbicula fluminea) bivalves to mercury

    NASA Astrophysics Data System (ADS)

    Oliveira, Patrícia; Lopes-Lima, Manuel; Machado, Jorge; Guilhermino, Lúcia

    2015-12-01

    Pollution is believed to be an important factor modulating the competition between exotic invasive bivalves and their native competitors. Thus, the objective of the present study was to compare the sensitivity of the European native Anodonta anatina and the exotic invasive species Corbicula fluminea to mercury, a ubiquitous environmental contaminant of high concern. In laboratory acute bioassays, adult organisms of both species were exposed independently to mercury for 96 h (31-500 μg/L). The criteria indicative of toxicity were mortality and biomarkers of oxidative stress and damage, neurotoxicity, and energy production changes. Mercury induced mortality in A. anatina (72 h-LC10 and 72 h-LC50 of 14.0 μg/L and 49.6 μg/L, respectively) but not in C. fluminea. The ability of C. fluminea to maintaining the shell closed for considerable periods of time when exposed to high concentrations of mercury and the effective activation (up to 63 μg/L) of mechanisms against the oxidative stress caused by mercury may have contributed to its relatively low sensitivity. In the range of concentrations tested, mercury had no significant effects on the other parameters analysed in C. fluminea. Overall, the findings of the present study, suggest that in real scenarios of competition between C. fluminea and A. anatina populations, the presence of mercury may modulate the process, acting in favour of the exotic species because it is less sensitive to this environmental contaminant than the native bivalve. The results of the present study highlight the need of further investigation on the effects of mercury on the competition between exotic invasive species and their native competitors, especially the effects potentially induced by long-term exposure to low concentrations of this metal, the mechanisms involved in the tolerance to mercury-induced stress, and the potential post-exposure recovery of both exotic invasive and native bivalves. This knowledge is most important for

  4. Abundance not linked to survival across the end-Cretaceous mass extinction: patterns in North American bivalves.

    PubMed

    Lockwood, Rowan

    2003-03-01

    Ecological studies suggest that rare taxa are more likely to go extinct than abundant ones, but the influence of abundance on survivorship in the fossil record has received little attention. An analysis of Late Maastrichtian bivalve subgenera from the North American Coastal Plain found no evidence that survivorship is tied to abundance across the end-Cretaceous mass extinction (65 million years ago), regardless of abundance metric or spatial scale examined. The fact that abundance does not promote survivorship in end-Cretaceous bivalves suggests that the factors influencing survivorship during mass extinctions in the fossil record may differ from those operating during intervals of background extinction.

  5. Multi-residue method for the analysis of pharmaceuticals and some of their metabolites in bivalves.

    PubMed

    Alvarez-Muñoz, D; Huerta, B; Fernandez-Tejedor, M; Rodríguez-Mozaz, S; Barceló, D

    2015-05-01

    A fast, simple and robust method has been developed for the simultaneous determination of 23 pharmaceuticals (including some major metabolites) in bivalve mollusks. The analytes belong to eight different therapeutic groups: antibiotics, psychiatric drugs, analgesics/anti-inflammatories, tranquilizer, calcium channel blockers, diuretic, and prostatic hyperplasia. The method is based on pressurized liquid extraction (PLE) followed by solid phase extraction clean-up (SPE), and ultra performance liquid chromatography-triple quadrupole mass spectrometry (UHPL-MS/MS) for the identification and quantification of the target analytes. It has been developed and validated in three different species of bivalves: Crassostrea gigas (Pacific oyster), Mytilus galloprovincialis (Mediterranean mussel), and Chamelea gallina (striped venus clam). The majority of the compounds were extracted with a recovery between 40 and 115%. The developed analytical method allowed the determination of the compounds in the lower ng/g concentration levels. The relative standard deviation was under 12% for the intra-day and 20% inter-day analyses, respectively. Finally, the method was applied to oyster, clam and mussel samples collected from the Ebro delta, Spain. The most ubiquitous compounds detected were the psychiatric drug venlanfaxine and the antibiotic azithromycin, with the highest concentrations found in mussel (2.7ng/g dw) and oyster (3.0ng/g dw), respectively. To the best of our knowledge, this is the first time that azithromycin has been reported in environmental samples of marine biota. PMID:25703000

  6. Mass mortalities in bivalve populations: A review of the edible cockle Cerastoderma edule (L.)

    NASA Astrophysics Data System (ADS)

    Burdon, Daryl; Callaway, Ruth; Elliott, Michael; Smith, Tim; Wither, Andrew

    2014-10-01

    Mass mortalities in bivalve populations have long been of particular concern, especially when the species supports a commercial fishery or is of conservation interest. Here we consider the evidence of mass mortalities of the edible cockle, Cerastoderma edule (L.). Through the construction of a conceptual model eight potential factors (or groups of factors) which may cause mass mortalities are identified and reviewed. These include: food limitation; density; oxygen depletion and organic loadings; temperature and salinity; parasites, pathogens and commensals; toxicants and other persistent pollutants; predation, and changes in sediment, suspended solids, topography and bathymetry. The interplay between factors in recognized and discussed based on evidence mainly from the published literature relating to temperate edible cockle beds. Anecdotal evidence is also reported from a structured survey of site-specific evidence provided by fisheries managers in England and Wales. Case studies from the UK and Europe indicate that there is often no single, clear generic cause of mass mortalities in cockle populations. The importance of linked site-specific scientific investigations and laboratory-based experiments to fill the gaps in our current understanding of mass mortalities in bivalve species is highlighted as necessary to take account of both local extrinsic and intrinsic factors.

  7. Filter-feeding bivalves can remove avian influenza viruses from water and reduce infectivity

    PubMed Central

    Faust, Christina; Stallknecht, David; Swayne, David; Brown, Justin

    2009-01-01

    Avian influenza (AI) viruses are believed to be transmitted within wild aquatic bird populations through an indirect faecal–oral route involving contaminated water. This study examined the influence of filter-feeding bivalves, Corbicula fluminea, on the infectivity of AI virus in water. Clams were placed into individual flasks with distilled water inoculated 1:100 with a low pathogenic (LP) AI virus (A/Mallard/MN/190/99 (H3N8)). Viral titres in water with clams were significantly lower at 24 and 48 h post-inoculation compared to LPAI-infected water without clams. To determine whether clams affected the infectivity of AI viruses, 18 wood ducks (Aix sponsa) were divided into test groups and inoculated with a variety of treatments of clam supernatants, whole clams and water exposed to a high pathogenic (HP) AI (A/whooper swan/Mongolia/244/05 (H5N1)). None of the wood ducks inoculated with HPAI-infected water that was filtered by clams or that was inoculated with or fed tissue from these clams exhibited morbidity or mortality. All wood ducks exposed to either HPAI-infected water without clams or the original viral inoculum died. These results indicate that filter-feeding bivalves can remove and reduce the infectivity of AI viruses in water and demonstrate the need to examine biotic environmental factors that can influence AI virus transmission. PMID:19656788

  8. Ultrastructure of the Interlamellar Membranes of the Nacre of the Bivalve Pteria hirundo, Determined by Immunolabelling.

    PubMed

    Osuna-Mascaró, Antonio J; Cruz-Bustos, Teresa; Marin, Frédéric; Checa, Antonio G

    2015-01-01

    The current model for the ultrastructure of the interlamellar membranes of molluscan nacre imply that they consist of a core of aligned chitin fibers surrounded on both sides by acidic proteins. This model was based on observations taken on previously demineralized shells, where the original structure had disappeared. Despite other earlier claims, no direct observations exist in which the different components can be unequivocally discriminated. We have applied different labeling protocols on non-demineralized nacreous shells of the bivalve Pteria. With this method, we have revealed the disposition and nature of the different fibers of the interlamellar membranes that can be observed on the surface of the nacreous shell of the bivalve Pteria hirundo by high resolution scanning electron microscopy (SEM). The minor chitin component consists of very thin fibers with a high aspect ratio and which are seemingly disoriented. Each fiber has a protein coat, which probably forms a complex with the chitin. The chitin-protein-complex fibers are embedded in an additional proteinaceous matrix. This is the first time in which the sizes, positions and distribution of the chitin fibers have been observed in situ.

  9. Titanium dioxide nanoparticles as carrier facilitate bioaccumulation of phenanthrene in marine bivalve, ark shell (Scapharca subcrenata).

    PubMed

    Tian, Shengyan; Zhang, Yaodan; Song, Chunzheng; Zhu, Xiaoshan; Xing, Baoshan

    2014-09-01

    To evaluate the impact of titanium dioxide nanoparticles (nTiO2) on the uptake of hydrophobic organic chemicals by marine bivalves, we conducted a comparative bioaccumulation study by exposing clam, Scapharca subcrenata, to phenanthrene (Phe) in the presence and absence of nTiO2. The large surface area of nTiO2 resulted in adsorption of co-existing Phe in aqueous solution to form nTiO2-Phe complexes. Accumulation of nTiO2 was not observed in clams at exposed concentration (500 μg/L) in this study. However, enhanced uptake of Phe by clams was observed in the presence of nTiO2, with ku and BAFs values being 2 and 1.7 times higher than that of Phe alone, respectively. The enhanced uptake can be explained by ingestion of nTiO2-Phe complexes into the gut and subsequent desorption of Phe there. Therefore, nTiO2 as a carrier facilitated the uptake of Phe by marine bivalves.

  10. Assessment and Molecular Characterization of Human Intestinal Parasites in Bivalves from Orchard Beach, NY, USA

    PubMed Central

    Tei, Freda F.; Kowalyk, Steven; Reid, Jhenelle A.; Presta, Matthew A.; Yesudas, Rekha; Mayer, D.C. Ghislaine

    2016-01-01

    Bivalves have been shown to be carriers of the human intestinal parasites Cryptosporidium parvum and Toxoplasma gondii. The goal of this study is to determine the prevalence of protozoan parasites in mollusks of New York City using a polymerase chain reaction (PCR)-based assay. Four species of mollusks, Mya arenaria, Geukensia demissa, Crassostrea virginica, and Mytilis edulis, were collected from Orchard Beach, NY in the fall of 2014, totaling 159 specimens. Each individual mollusk was dissected to harvest the digestive gland, the mantle, the gills, the foot and the siphon. The tissues were assayed for the presence of Cryptosporidium parvum, Giardia lamblia, and Toxoplasma gondii DNA by using primers that target parasite-specific genes. C. parvum was found at a prevalence of 50%, 11.3%, and 1%, respectively, in Mya arenaria, G. demissa, and Mytilis edulis. C. parvum DNA was detected in all the tissues of these bivalve species, except the gills. Furthermore, G. lamblia was detected in Mya arenaria, G. demissa, Crassostrea virginica and Mytilis edulis at a prevalence of 37.5%, 4.5%, 60%, and 20.6%, respectively, while T. gondii DNA was not detected. PMID:27043590

  11. Proteomic research in bivalves: towards the identification of molecular markers of aquatic pollution.

    PubMed

    Campos, Alexandre; Tedesco, Sara; Vasconcelos, Vitor; Cristobal, Susana

    2012-07-19

    Biomonitoring of aquatic environment and assessment of ecosystem health play essential roles in the development of effective strategies for the protection of the environment, human health and sustainable development. Biomarkers of pollution exposure have been extensively utilized in the last few decades to monitor the health of organisms and hence assess environmental status. However, the use of single biomarkers against biotic or abiotic stressors may be limited by the lack of sensitivity and specificity. Therefore, more recently, the search for novel biomarkers has been focused on the application of OMICS methodologies. Environmental proteomics focuses on the analysis of an organism's proteome and the detection of changes in the level of individual proteins/peptides in response to environmental stressors. Proteomics can provide a more robust approach for the assessment of environmental stress and therefore exposure to pollutants. This review aims to summarize the proteomic research in bivalves, a group of sessile and filter feeding organisms that play an important function as "sentinels" of the aquatic environment. A description of the main proteomic methodologies is provided. The current knowledge in bivalves' toxicology, achieved with proteomics, is reported describing the main biochemical markers identified. A brief discussion regarding future challenges in this area of research emphasizing the development of more descriptive gene/protein databases that could support the OMICs approaches is presented.

  12. Bioavailability of Cd, Cr, and Zn to bivalves in south San Francisco Bay

    SciTech Connect

    Lee, B.G.; Luoma, S.N.; Geen, A. van

    1995-12-31

    The bioavailability of Cd, Cr, and Zn to benthic bivalves (Potamocorbular amurensis and Macoma balthica) is affected by the type of natural particles the animals ingest, and the concentration and speciation of dissolved metals. During a spring phytoplankton bloom in south San Francisco Bay dissolved Cd and Zn concentrations decreased to about half of pre-bloom concentrations. The concentrations of particulate Cd and Zn concentrations increased due to preferential uptake of these metals by phytoplankton. Assimilation of Cd was more efficient when clams ate pure phytoplankton (80% for M. balthica and 29% for P. amurensis) than when they were exposed to inorganic-dominated particles. M. balthica and P. amurensis assimilated 72% and 42% of Zn associated with the particles during the bloom. Assimilation of Cr was low (<6%) and particle type had little effect on its availability. Accumulation of Cd via the dissolved route was low in high salinity waters (15 ppt). Metal bioaccumulation in the bivalves was modeled using the experimentally determined physiological parameters. The results were compared to metal concentrations in clams from the Bay. The model suggested that the clams accumulated Cd and Zn at higher rates during the phytoplankton bloom, although dissolved metal concentrations in the water column were reduced.

  13. Ocean acidification increases cadmium accumulation in marine bivalves: a potential threat to seafood safety

    NASA Astrophysics Data System (ADS)

    Shi, Wei; Zhao, Xinguo; Han, Yu; Che, Zhumei; Chai, Xueliang; Liu, Guangxu

    2016-01-01

    To date, the effects of ocean acidification on toxic metals accumulation and the underlying molecular mechanism remains unknown in marine bivalve species. In the present study, the effects of the realistic future ocean pCO2 levels on the cadmium (Cd) accumulation in the gills, mantle and adductor muscles of three bivalve species, Mytilus edulis, Tegillarca granosa, and Meretrix meretrix, were investigated. The results obtained suggested that all species tested accumulated significantly higher Cd (p < 0.05) in the CO2 acidified seawater during the 30 days experiment and the health risk of Cd (based on the estimated target hazard quotients, THQ) via consumption of M. meretrix at pH 7.8 and 7.4 significantly increased 1.21 and 1.32 times respectively, suggesting a potential threat to seafood safety. The ocean acidification-induced increase in Cd accumulation may have occurred due to (i) the ocean acidification increased the concentration of Cd and the Cd2+/Ca2+ in the seawater, which in turn increased the Cd influx through Ca channel; (ii) the acidified seawater may have brought about epithelia damage, resulting in easier Cd penetration; and (iii) ocean acidification hampered Cd exclusion.

  14. Steady-state model of biota sediment accumulation factor for metals in two marine bivalves

    SciTech Connect

    Thomann, R.V.; Mahony, J.D.; Mueller, R.

    1995-11-01

    A model of the biota sediment accumulation factor (BSAF) is developed to relate the ratio of metal concentrations in two marine bivalves (Crassostrea virginica and Mytilus edulis) to sediment metal concentration. A generalized metal BSAF can be approximated by a simple relationship that is a function of sediment to water column partitioning, the bioconcentration factor (BCF), the depuration rate, the metal assimilation efficiency from food, the bivalve feeding rate, and the growth rate. Analyses of Mussel Watch data indicate that the medium BSAF across stations varies by about three orders of magnitude from Zn, Cd, and Cu at the highest levels of BSAF = 1 to 10, while Cr has the lowest BSAF at 0.01. Total Hg is about 1.0 and Ni and Pb are approximately 0.1. Calibration of the model indicates that the food route of metal accumulation is significant for all metals but specially for Zn, Cd, Cu, and Hg where virtually all of the observed BSAF is calculated to be due to ingestion of metal from food in the overlying water. These results indicate a potential significance of the metal-binding protein metallothionein, which results in relatively high binding of metal and resulting low depuration rates.

  15. Multi-residue method for the analysis of pharmaceuticals and some of their metabolites in bivalves.

    PubMed

    Alvarez-Muñoz, D; Huerta, B; Fernandez-Tejedor, M; Rodríguez-Mozaz, S; Barceló, D

    2015-05-01

    A fast, simple and robust method has been developed for the simultaneous determination of 23 pharmaceuticals (including some major metabolites) in bivalve mollusks. The analytes belong to eight different therapeutic groups: antibiotics, psychiatric drugs, analgesics/anti-inflammatories, tranquilizer, calcium channel blockers, diuretic, and prostatic hyperplasia. The method is based on pressurized liquid extraction (PLE) followed by solid phase extraction clean-up (SPE), and ultra performance liquid chromatography-triple quadrupole mass spectrometry (UHPL-MS/MS) for the identification and quantification of the target analytes. It has been developed and validated in three different species of bivalves: Crassostrea gigas (Pacific oyster), Mytilus galloprovincialis (Mediterranean mussel), and Chamelea gallina (striped venus clam). The majority of the compounds were extracted with a recovery between 40 and 115%. The developed analytical method allowed the determination of the compounds in the lower ng/g concentration levels. The relative standard deviation was under 12% for the intra-day and 20% inter-day analyses, respectively. Finally, the method was applied to oyster, clam and mussel samples collected from the Ebro delta, Spain. The most ubiquitous compounds detected were the psychiatric drug venlanfaxine and the antibiotic azithromycin, with the highest concentrations found in mussel (2.7ng/g dw) and oyster (3.0ng/g dw), respectively. To the best of our knowledge, this is the first time that azithromycin has been reported in environmental samples of marine biota.

  16. Contrasting metal detoxification in polychaetes, bivalves and fish from a contaminated bay.

    PubMed

    Fan, Wenhong; Xu, Zhizhen; Wang, Wen-Xiong

    2015-02-01

    Jinzhou Bay in Bohai, Northern China, is historically contaminated with metals, but the organisms living in such contaminated environments are much less well studied. In this study, we contrasted the different subcellular and detoxification responses of polychaetes, bivalves and fish collected from different contaminated sites in Jinzhou Bay. In polychaete Neanthes japonica, metal-rich granule (MRG) was the main biologically detoxified metal compartment, and metallothionein-like protein (MTLP) detoxified a relatively smaller fraction of accumulated metals. The importance of MRG increased whereas that of MTLP decreased with increasing metal bioaccumulation. Detoxification in the two bivalves was similar to that in the polychaetes. However, the MRG appeared to play only a minor role in metal binding and detoxification in the gills and livers of fish, whereas MTLP was the dominating detoxification pool. Cellular debris was an important pool binding with metals in the three marine animals. Our study highlighted the contrasting cellular binding and detoxification among different marine organisms living in contaminated environments.

  17. Origins, bottlenecks, and present-day diversity: patterns of morphospace occupation in marine bivalves.

    PubMed

    Huang, Shan; Roy, Kaustuv; Jablonski, David

    2015-03-01

    It has long been known that species should not be distributed randomly in morphospace (a multidimensional trait space), even under simple models of evolution. However, recent studies suggest that position in morphospace can affect aspects of evolution such as the durations of clades and the species richness of their constituent taxa. Here we investigate the dynamics of morphospace occupancy in living and fossil marine bivalves using shell size and aspect ratio, two functionally important traits. Multiple lines of evidence indicate that the center of a family's morphospace today represents a location where taxonomic diversity is maximized, apparently owing to lower extinction rates. Within individual bivalve families, species with narrow geographic ranges are distributed throughout the morphospace but widespread species, which are generally expected to be extinction resistant, tend to be concentrated near the center. The morphospace centers of most species-rich families today (defined as the median value for all species in the family) tend to be close to the positions of the family founders, further suggesting an association between position in morphospace and net diversification rates. However, trajectories of individual subclades (genera) are inconsistent with the center of morphospace being an evolutionary attractor.

  18. Ocean acidification increases cadmium accumulation in marine bivalves: a potential threat to seafood safety.

    PubMed

    Shi, Wei; Zhao, Xinguo; Han, Yu; Che, Zhumei; Chai, Xueliang; Liu, Guangxu

    2016-01-21

    To date, the effects of ocean acidification on toxic metals accumulation and the underlying molecular mechanism remains unknown in marine bivalve species. In the present study, the effects of the realistic future ocean pCO2 levels on the cadmium (Cd) accumulation in the gills, mantle and adductor muscles of three bivalve species, Mytilus edulis, Tegillarca granosa, and Meretrix meretrix, were investigated. The results obtained suggested that all species tested accumulated significantly higher Cd (p < 0.05) in the CO2 acidified seawater during the 30 days experiment and the health risk of Cd (based on the estimated target hazard quotients, THQ) via consumption of M. meretrix at pH 7.8 and 7.4 significantly increased 1.21 and 1.32 times respectively, suggesting a potential threat to seafood safety. The ocean acidification-induced increase in Cd accumulation may have occurred due to (i) the ocean acidification increased the concentration of Cd and the Cd(2+)/Ca(2+) in the seawater, which in turn increased the Cd influx through Ca channel; (ii) the acidified seawater may have brought about epithelia damage, resulting in easier Cd penetration; and (iii) ocean acidification hampered Cd exclusion.

  19. Bivalve Omics: State of the Art and Potential Applications for the Biomonitoring of Harmful Marine Compounds

    PubMed Central

    Suárez-Ulloa, Victoria; Fernández-Tajes, Juan; Manfrin, Chiara; Gerdol, Marco; Venier, Paola; Eirín-López, José M.

    2013-01-01

    The extraordinary progress experienced by sequencing technologies and bioinformatics has made the development of omic studies virtually ubiquitous in all fields of life sciences nowadays. However, scientific attention has been quite unevenly distributed throughout the different branches of the tree of life, leaving molluscs, one of the most diverse animal groups, relatively unexplored and without representation within the narrow collection of well established model organisms. Within this Phylum, bivalve molluscs play a fundamental role in the functioning of the marine ecosystem, constitute very valuable commercial resources in aquaculture, and have been widely used as sentinel organisms in the biomonitoring of marine pollution. Yet, it has only been very recently that this complex group of organisms became a preferential subject for omic studies, posing new challenges for their integrative characterization. The present contribution aims to give a detailed insight into the state of the art of the omic studies and functional information analysis of bivalve molluscs, providing a timely perspective on the available data resources and on the current and prospective applications for the biomonitoring of harmful marine compounds. PMID:24189277

  20. Sperm transfer and reproductive biology in species of hermaphroditic bivalves (Galeommatoidea: Montacutidae).

    PubMed

    Fox, Thomas H; Jespersen, Ase; Lützen, Jørgen

    2007-11-01

    The histology of the reproductive organs is studied in the protandric hermaphroditic Tellimya ferruginosa. In NW Europe the species reproduces from May through August. Sperm transfer takes place when mature testis follicles are transplanted to the gills or walls of the mantle cavity in recipient hermaphroditic or female bivalves. Transplantation is accompanied by histological changes and sperm cells are released when transplants perish with age. Details are given on the reproduction in Montacuta percompressa which takes place from March through October in North Carolina, USA. All shelled bivalves are females and it is postulated that spermatogenic bodies attached to gills or other surfaces in the female's mantle cavity and previously considered to be dwarf males arise from transplanted larval gonads. The ultrastructure of the euspermatozoa and/or the anucleate paraspermatozoa is described in T. ferruginosa, T. tenella, and M. percompressa. The sperm of the first two species share a number of significant apomorphies with those of another montacutid, Brachiomya stigmatica. In the simultaneous hermaphroditic M. substriata the nucleate paraspermatozoa associate with the euspermatozoa to form spherical spermatozeugmata that are stored in the testis.

  1. Sodium sulfate impacts feeding, specific dynamic action, and growth rate in the freshwater bivalve Corbicula fluminea.

    PubMed

    Soucek, David John

    2007-08-01

    Sodium sulfate is a ubiquitous salt that reaches toxic concentrations due to mining and other industrial activities, yet is currently unregulated at the Federal level in the United States. Previous studies have documented reduced growth of clams downstream of sulfate-dominated effluents, altered bioenergetics in filter-feeding invertebrates, and interactions between sulfate and other toxicants. Therefore, the purpose of this study was to determine if sodium sulfate affects the bioenergetics of the filter-feeding, freshwater bivalve, Corbicula fluminea, and the mechanism by which the effects are elicited. In addition to measuring effects on feeding, respiration and growth rates, I evaluated the relative sensitivity of a green algae consumed by clams to determine if top-down or bottom-up effects might be exhibited under field conditions. This study demonstrated that sodium sulfate had no effect on basal metabolic rates, but significantly reduced the feeding, post-feeding metabolic, and growth rates of C. fluminea. The proposed mechanism for these impacts is that filtering rates are reduced upon exposure, resulting in reduced food consumption and therefore, preventing increased metabolic rates normally associated with post-feeding specific dynamic action (SDA). In the field, these effects may cause changes in whole stream respiration rates and organic matter dynamics, as well as alter uptake rates of other food-associated contaminants like selenium, the toxicity of which is known to be antagonized by sulfate, in filter-feeding bivalves.

  2. Ultrastructure of the Interlamellar Membranes of the Nacre of the Bivalve Pteria hirundo, Determined by Immunolabelling

    PubMed Central

    Osuna-Mascaró, Antonio J.; Cruz-Bustos, Teresa; Marin, Frédéric; Checa, Antonio G.

    2015-01-01

    The current model for the ultrastructure of the interlamellar membranes of molluscan nacre imply that they consist of a core of aligned chitin fibers surrounded on both sides by acidic proteins. This model was based on observations taken on previously demineralized shells, where the original structure had disappeared. Despite other earlier claims, no direct observations exist in which the different components can be unequivocally discriminated. We have applied different labeling protocols on non-demineralized nacreous shells of the bivalve Pteria. With this method, we have revealed the disposition and nature of the different fibers of the interlamellar membranes that can be observed on the surface of the nacreous shell of the bivalve Pteria hirundo by high resolution scanning electron microscopy (SEM). The minor chitin component consists of very thin fibers with a high aspect ratio and which are seemingly disoriented. Each fiber has a protein coat, which probably forms a complex with the chitin. The chitin-protein-complex fibers are embedded in an additional proteinaceous matrix. This is the first time in which the sizes, positions and distribution of the chitin fibers have been observed in situ. PMID:25909912

  3. Temporal Patterns in Bivalve Excurrent Flow Under Varying Ambient Flow Conditions

    NASA Astrophysics Data System (ADS)

    Delavan, S. K.; Webster, D. R.

    2008-11-01

    The predator-prey relationship between blue crabs (Callinectes sapidus) and bivalve clams (Mercenaria mercenaria) is mediated by the transport of metabolites released by the prey (clams) and transported downstream as a passive scalar. This study focuses on how the prey behavior contributes to the information available within the odorant plume. Clams may modify factors such as excurrent flux, flow unsteadiness, and siphon height and diameter. A Particle Image Velocimetry (PIV) system has been used to quantify the temporal patterns in the excurrent jet of the bivalve siphon under varying ambient flow conditions. According to a spectral analysis of siphon excurrent velocity time records, there is a low frequency periodic component that could contribute to the mixing of clam metabolites through the generation of persistent jet vorticies. Also, fractal analysis of the velocity time records shows that as the ambient velocity increases the excurrent velocity becomes more correlated and less random. These results suggest that for high ambient flow a low frequency periodicity may be sufficient to promote the mixing and dilution of metabolites. In contrast, for low ambient flow more random siphon excurrent velocity may be required to reduce the amount of information available to predators in the downstream odorant plume.

  4. Metals and organotins in multiple bivalve species in a one-off global survey.

    PubMed

    Larsen, Martin M; Strand, Jakob; Christensen, Jan H; Vorkamp, Katrin; Hansen, Asger B; Andersen, Ole

    2011-06-01

    The Galathea 3 expedition circumnavigated the globe in 2006-2007 and collected marine samples from six continents. Bivalves were collected from harbours, other impacted locations and reference sites, and samples from 57 sites were analyzed for metals and 47 for organotins, to assess current contamination levels on a global scale. Metal concentrations in nine bivalve species were normalised to the Mytilidae family using conversion factors based on cosampled species and literature bioconcentration factors. The lowest metal and tributyltin concentrations were below background assessment concentrations (BACs) agreed in the Oslo-Paris convention (OSPAR) for the North Sea, and at most harbours the concentrations were orders of magnitude above BACs. The lowest concentrations of Cd and Pb measured here suggest that the BACs should be lower in a worldwide context. The sources of metals were classified according to human impact using principal component analysis. High relative concentrations of Hg, Pb and P were source indicators for industrial activity and land use; Zn, organotins, Cd and Cu for shipping activities, and V for oil spills. Generally the concentration levels at reference sites were low, but not always lower than expected impacted areas. The most contaminated areas were harbours, where especially Copenhagen, St Croix and Sydney, can be considered hotspots of tributyltin as well as a number of metals.

  5. Delineating copper accumulation pathways for the freshwater bivalve Corbicula using stable copper isotopes

    USGS Publications Warehouse

    Croteau, M.-N.; Luoma, S.N.

    2005-01-01

    Delineation of metal uptake routes in aquatic invertebrates is critical for characterizing bioaccumulation dynamics and assessing risks associated with metal exposure. Here we demonstrate that Cu stable isotopic ratios can be manipulated in both exposure media and algae to determine the efflux rate constant (ke) and to estimate Cu assimilation efficiency (AE) from ingested food in a freshwater bivalve (Corbicula fluminea). The Cu AE in Corhicula fed 65Cu-spiked Cryptomonas ozolini was 38%. Copper uptake routes had no significant influence on efflux; ke, of 0.004 per day characterized the slowest component of efflux following short-term exposures to 65Cu in water or in both food and water. Incorporation of the physiological parameters for dietary and dissolved uptake as well as rate constants of loss into a bioaccumulation model allowed for assessing the relative contribution of water and food as Cu sources. At [65Cu 2+] of 6.7 ??g/L, Corbicula accumulated twice as much Cu from diet as from water. In most freshwater systems, the dietary pathway is likely to act as the major Cu uptake route for Corbicula. Extrapolation of our laboratory results to the San Francisco Bay-Delta (California, USA) indicated that our biodynamic model and the laboratory-derived parameters for dietary 65Cu uptake provided a realistic representation of the processes involved in Cu accumulation by the bivalve Corbicula. ?? 2005 SETAC.

  6. Ocean acidification increases cadmium accumulation in marine bivalves: a potential threat to seafood safety

    PubMed Central

    Shi, Wei; Zhao, Xinguo; Han, Yu; Che, Zhumei; Chai, Xueliang; Liu, Guangxu

    2016-01-01

    To date, the effects of ocean acidification on toxic metals accumulation and the underlying molecular mechanism remains unknown in marine bivalve species. In the present study, the effects of the realistic future ocean pCO2 levels on the cadmium (Cd) accumulation in the gills, mantle and adductor muscles of three bivalve species, Mytilus edulis, Tegillarca granosa, and Meretrix meretrix, were investigated. The results obtained suggested that all species tested accumulated significantly higher Cd (p < 0.05) in the CO2 acidified seawater during the 30 days experiment and the health risk of Cd (based on the estimated target hazard quotients, THQ) via consumption of M. meretrix at pH 7.8 and 7.4 significantly increased 1.21 and 1.32 times respectively, suggesting a potential threat to seafood safety. The ocean acidification-induced increase in Cd accumulation may have occurred due to (i) the ocean acidification increased the concentration of Cd and the Cd2+/Ca2+ in the seawater, which in turn increased the Cd influx through Ca channel; (ii) the acidified seawater may have brought about epithelia damage, resulting in easier Cd penetration; and (iii) ocean acidification hampered Cd exclusion. PMID:26795597

  7. Cloning and expression of MDR transporters from marine bivalves, and their potential use in biomonitoring.

    PubMed

    Feldstein, Tamar; Nelson, Nathan; Mokady, Ofer

    2006-07-01

    Multidrug resistance transporters (MDRs) are excellent candidates for molecular-level biomonitoring - they function in exporting xenobiotic compounds and their expression is inducible. However, currently available MDR sequence information from aquatic invertebrates is partial and mostly biased towards the conserved ATPase domain. In the present study, two genes belonging to the MDR/TAP (ABCB) family were cloned and characterized from the bivalve Brachidontes pharaonis, which thrives in rocky environments along the Israeli Mediterranean coast. One of these is a complete sequence of a 'half'ABCB, probably belonging to the ABCB10 subfamily, while the second is a 'full'ABCB1 transporter. A quantitative RT-PCR protocol for biomonitoring was tested in laboratory experiments. Bivalves exposed to diesel showed significant increase in B1 expression levels, while the expression of B10 was suppressed. These results suggest that B. pharaonis features an MDR1 homologue that is induced by pollution and may serve as a sentinel organism for routine biomonitoring programs. However, our findings also exemplify that not all MDRs are equally suitable for this purpose and sequence information must be expanded beyond the ATPase domain for correct classification of cloned genes.

  8. A kinetic approach to assess oxidative metabolism related features in the bivalve Mya arenaria.

    PubMed

    González, Paula Mariela; Abele, Doris; Puntarulo, Susana

    2012-12-01

    Electron paramagnetic resonance uses the resonant microwave radiation absorption of paramagnetic substances to detect highly reactive and, therefore, short-lived oxygen and nitrogen centered radicals. Previously, steady state concentrations of nitric oxide, ascorbyl radical (A·) and the labile iron pool (LIP) were determined in digestive gland of freshly collected animals from the North Sea bivalve Mya arenaria. The application of a simple kinetic analysis of these data based on elemental reactions allowed us to estimate the steady state concentrations of superoxide anion, the rate of A· disappearance and the content of unsaturated lipids. This analysis applied to a marine invertebrate opens the possibility of a mechanistic understanding of the complexity of free radical and LIP interactions in a metabolically slow, cold water organism under unstressed conditions. This data can be further used as a basis to assess the cellular response to stress in a simple system as the bivalve M. arenaria that can then be compared to cells of higher organisms. PMID:22829190

  9. Pathways of food uptake in native (Unionidae) and introduced (Corbiculidae and Dreissenidae) freshwater bivalves

    USGS Publications Warehouse

    Nichols, S. Jerrine; Silverman, Harold; Dietz, Thomas H.; Lynn, John W.; Garling, Donald L.

    2005-01-01

    Nineteen species of adult freshwater bivalves were able to use water currents generated from within the mantle cavity to move non-suspended algae into the shell through non-siphon areas such as the anterior shell valve edge and the mid-ventral point of the shell. This was in addition to, and not in replacement of, uptake of planktonic algae through the inhalant siphon. Algae obtained from both the non-inhalant siphon areas and the inhalant siphon were equally captured and transferred to the stomach. Pseudofecal release was also more complex than typically stated. Pseudofeces were released from the inhalant siphon (as expected), plus from the anterior shell margin, and at the mid-point along the ventral shell edge (non-dreissenids). Pseudofeces that settled near the ventral shell margin was accessible for future uptake back into the mantle cavity. There were no species or body size differences in ability to capture food from non-planktonic sources. The extent to which natural populations utilize benthic food resources remains to be determined. However, our study demonstrates that bivalve communities are very adaptable in accessing a variety of food resources from both suspended material in the water column, as well as organic material from the sediments.

  10. Evaluation of the effects of candidate molluscicides on two nontarget bivalves

    USGS Publications Warehouse

    Waller, D.L.; Marking, L.L.; Rach, J.J.

    1992-01-01

    A variety of molluscicides have been proposed for use in control of zebra mussels (Dreissena polymorpha), but their effect on nontarget aquatic organisms has not been evaluated. Standard methods were adapted for assessing the toxicity of candidate molluscicides to two nontarget bivalves. Fingernail clams, Musculium transversum, and the fawnfoot mussel, Truncilla donaciformis, were selected to represent the two families of native bivalves. Test organisms were collected from pools 6 to 9 of the Upper Mississippi River near La Crosse, WI. Static acute toxicity tests were conducted for 48 hours followed by a 96-hour monitoring period in untreated water to more fully assess survival and mortality. Toxicity data were analyzed by probit analysis to give LC sub(50) values and 95% confidence limits. The same chemicals as those tested at Ohio State University were evaluated against zebra mussels. Results from these studies and those conducted at Ohio State University will be used to evaluate the effectiveness of chemicals in zebra mussel control and their potential hazard to nontarget organisms.

  11. Assessment and Molecular Characterization of Human Intestinal Parasites in Bivalves from Orchard Beach, NY, USA.

    PubMed

    Tei, Freda F; Kowalyk, Steven; Reid, Jhenelle A; Presta, Matthew A; Yesudas, Rekha; Mayer, D C Ghislaine

    2016-04-01

    Bivalves have been shown to be carriers of the human intestinal parasites Cryptosporidium parvum and Toxoplasma gondii. The goal of this study is to determine the prevalence of protozoan parasites in mollusks of New York City using a polymerase chain reaction (PCR)-based assay. Four species of mollusks, Mya arenaria, Geukensia demissa, Crassostrea virginica, and Mytilis edulis, were collected from Orchard Beach, NY in the fall of 2014, totaling 159 specimens. Each individual mollusk was dissected to harvest the digestive gland, the mantle, the gills, the foot and the siphon. The tissues were assayed for the presence of Cryptosporidium parvum, Giardia lamblia, and Toxoplasma gondii DNA by using primers that target parasite-specific genes. C. parvum was found at a prevalence of 50%, 11.3%, and 1%, respectively, in Mya arenaria, G. demissa, and Mytilis edulis. C. parvum DNA was detected in all the tissues of these bivalve species, except the gills. Furthermore, G. lamblia was detected in Mya arenaria, G. demissa, Crassostrea virginica and Mytilis edulis at a prevalence of 37.5%, 4.5%, 60%, and 20.6%, respectively, while T. gondii DNA was not detected. PMID:27043590

  12. [Detection of norovirus RNA in bivalve molluscs by using bacteria-culture-employed method (A3T method)].

    PubMed

    Akiba, Tetsuya; Tanaka, Tatsuya; Nagano, Miyuki; Mori, Kohji; Hayashi, Yukinao; Obata, Hiromi; Chiba, Takashi; Ikuta, Yasuhisa; Kamiya, Yoriko; Nakama, Akiko; Hosaka, Mitsugu; Kai, Akemi

    2010-01-01

    Norovirus (NV) RNA has rarely been detected in foods despite the use of highly sensitive methods such as RT-PCR and real-time RT-PCR. In the modified method (A3T method) reported previously, a bacterial culture process was introduced into the standard protocol for NV detection to remove some inhibitor(s) present in food ingredients. To confirm the efficiency of the A3T method and to examine NV contamination in bivalve molluscs, we tried to detect NV RNA in bivalve molluscs on the market and in oyster samples associated with foodborne outbreaks by using the standard method and the A3T method. NV RNAs were detected in 20 samples (18.0%) of 111 bivalve molluscs, including oysters, on the market by use of the A3T method, while only one sample (0.9%) was positive according to the standard method. NV RNA was also detected in 10 of 35 oyster samples related to foodborne outbreaks by the A3T method. Those results show that the A3T method is suitable for the detection of NV in bivalve molluscs in general laboratories.

  13. Lineage tracing of the bivalve shell field with special interest in the descendants of the 2d blastomere.

    PubMed

    Mohri, Masakuni; Hashimoto, Naoki; Wada, Hiroshi

    2016-03-01

    By evolving bilaterally separated shell plates, bivalves acquired a unique body plan in which their soft tissues are completely protected by hard shell plates. In this unique body plan, mobility between the separated shell plates is provided by novel structures such as a ligament and adductor muscles. As a first step towards understanding how the bivalve body plan was established, we investigated the development of the separated shell plates and ligament. Over 100 years ago, it was hypothesized that the development of separated shell plates is tightly linked with the unique cell cleavage (division) pattern of bivalves during development, wherein each bilateral daughter cell of the 2d descendant 2d(1121) develops into one of the bilateral shell fields. In this study, we tested this hypothesis by tracing the cell lineages of the Japanese purple mussel Septifer virgatus. Although the shell fields were found to be exclusively derived from the bilateral descendant cells of 2d: 2d(11211) and 2d(11212), the descendants of these cells were not restricted to shell fields alone, nor were they confined to the left or right side of the shell field based on their lineage. Our study demonstrated that ligament cells are also derived from 2d(11211) and 2d(11212), indicating that the ligament cells emerged as a subpopulation of shell field cells. This also suggests that the establishment of the novel developmental system for the ligament cells was critical for the evolution of the unique body plan of bivalves.

  14. Comparison of the accumulation of polycyclic aromatic hydrocarbons (PAHs) in bivalves and sediments in San Francisco Bay, California

    SciTech Connect

    Jenkins, K.D.; Pendergast, J.; Means, J.C.; McMillin, D.J.; Gala, W.R.; Folwarkow, S.

    1994-12-31

    Accumulation of non-polar organic chemicals into the lipids of aquatic organisms and into the organic carbon of sediments are controlled by the same physical/chemical characteristic of a chemical, the octanol-water partition coefficient. Although theoretically the monitoring of non-polar organic chemicals in aquatic organisms and sediments could be redundant, environmental factors such as metabolism, biodegradation, historical sediment deposits, etc. can cause the chemical profiles of aquatic organisms and sediments to be quite different. A comparison of the polycyclic aromatic hydrocarbons (PAHs) profile in sediments and in bivalves exposed to the overlying water for 90 days at several stations near refinery discharges in San Francisco Bay was performed. Concentrations of all classes of PAHs were enriched in the sediments relative to the bivalves even after normalizing for organic carbon and lipids. The PAH profile in the sediments contained a higher proportion of high MW PAHs and non-substituted PAHs than was observed in the bivalves. Given the low capacity of bivalves to metabolize PAHs, other factors, such as differential solubility and bioavailability, must be important to explain this variation in partitioning of PAH classes between sediments and tissues.

  15. Combining bioaccumulation and coping mechanism to enhance long-term site-specific risk assessment for zinc susceptibility of bivalves.

    PubMed

    Chen, Bo-Ching; Chen, Wei-Yu; Ju, Yun-Ru; Tsai, Jeng-Wei; Jou, Li-John; Singh, Sher; Liao, Chung-Min

    2011-07-01

    The purpose of this study is to conduct a long-term site-specific risk assessment for zinc (Zn) susceptibility of bivalves, green mussel Perna viridis and hard clam Ruditapes philippinarum, based on published experimental data by linking the biologically-based damage assessment model with the subcellular partitioning concept. A comprehensive risk modeling framework was developed to predict susceptibility probability of two bivalve species exposed to waterborne Zn. The results indicated that P. viridis accumulates more Zn toxicity, whereas both toxic potency and the recovery rate of Zn are higher for R. philippinarum. We found that negative linear correlations exist in elimination-recovery and elimination-detoxification relationships, whereas a positive linear correlation was observed in recovery-detoxification relationships for bivalves exposed to waterborne Zn. Simulation results showed that the spatial differences of susceptibility primarily resulted from the variation of waterborne Zn concentration under field conditions. We found that R. philippinarum is more susceptible of Zn than P. viridis under the same exposure condition. Results also suggested that Zn posed no significant susceptibility risk to two bivalve species in Taiwan. We suggested that these two species can be used to biomonitor the water quality on Taiwan coastal areas.

  16. Biochemical and behavioural responses of the endobenthic bivalve Scrobicularia plana to silver nanoparticles in seawater and microalgal food.

    PubMed

    Buffet, Pierre-Emmanuel; Pan, Jin-Fen; Poirier, Laurence; Amiard-Triquet, Claude; Amiard, Jean-Claude; Gaudin, Pierre; Risso-de Faverney, Christine; Guibbolini, Marielle; Gilliland, Douglas; Valsami-Jones, Eugenia; Mouneyrac, Catherine

    2013-03-01

    Because of their bactericidal effects, Ag nanoparticles (Ag NPs) have promising industrial development but could lead to potential ecological risks. The aim of this study was to examine the uptake and effect of silver (soluble or as lactate Ag NPs of 40 nm) at low concentrations (10 μg L(-1)) in the endobenthic bivalve Scrobicularia plana exposed, for 14 days, directly (water) or via the diet (microalgae). The stability of Ag NPs in seawater was examined using dynamic light scattering. Release of soluble Ag from Ag NPs in the experimental media was quantified by using diffusive gradient in thin film. Bioaccumulation of Ag in bivalves was measured by electrothermal atomic absorption spectrometry. Behavioural and biochemical biomarkers were determined in bivalves. Aggregation of Ag NPs and the release of soluble Ag from Ag NPs were observed in the experimental media. For both forms of Ag, bioaccumulation was much more important for waterborne than for dietary exposure. The response of oxidative stress biomarkers (catalase, glutathion S-transferase, superoxide dismutase) was more important after dietary than waterborne exposure to Ag (soluble and NPs). These defences were relatively efficient since they led to a lack of response of damage biomarkers. Burrowing was not affected for bivalves exposed directly or through the diet to both Ag forms but feeding behaviour was impaired after 10 days of dietary exposure. Since no differences of responses to Ag either soluble or nanoparticulate were observed, it seems that labile Ag released from Ag NPs was mainly responsible for toxicity.

  17. A striking parallel between cardiolipin fatty acid composition and phylogenetic belonging in marine bivalves: a possible adaptative evolution?

    PubMed

    Kraffe, E; Grall, J; Le Duff, M; Soudant, P; Marty, Y

    2008-10-01

    Thirty-five species of marine mollusk bivalves were analyzed for their fatty acid (FA) composition of cardiolipin (Ptd(2)Gro). All species showed a Ptd(2)Gro with strong selectivity for only a few polyunsaturated fatty acids, but three characteristic FA profiles emerged, with clear parallels to bivalve phylogeny. A first group of 12 species belonging to the Eupteriomorphia subgroup (Filibranchia) was characterized by a Ptd(2)Gro almost exclusively composed of 22:6n-3, whereas in the four Filibranchia Pteriomorph species analyzed, this FA was combined with substantial proportions of 18:2n-6 and 18:3n-3. Finally, a third group of 20 species, all belonging to the Heterodonta subclass, possessed Ptd(2)Gro containing predominantly both 22:6n-3 and 20:5n-3. Polyunsaturated FA moieties and arrangements in the Ptd(2)Gro of some marine species investigated in other classes of the mollusk phylum (Gastropoda, Polyplacophora) were found to be different. The present results suggest that the specific Ptd(2)Gro FA compositions in bivalves are likely to be controlled and conserved in species of the same phylogenetic group. Functional significances of the evolution of this mitochondrial lipid structure in bivalves are discussed. PMID:18716818

  18. Improvement of urban lake water quality by removal of Escherichia coli through the action of the bivalve Anodonta californiensis.

    PubMed

    Ismail, Niveen S; Dodd, Hanna; Sassoubre, Lauren M; Horne, Alexander J; Boehm, Alexandria B; Luthy, Richard G

    2015-02-01

    High levels of fecal indicator bacteria, such as Escherichia coli, can be indicative of poor water quality. The use of shellfish to reduce eutrophication has been proposed, but application of bivalves to reduce bacterial levels has not been extensively reported. Removal of E. coli by the native freshwater mussel Anodonta californiensis was studied using laboratory batch systems and field-based flow-through systems. Batch systems were utilized to determine the fate and inactivation of E. coli after uptake by the mussel. Batch experiments demonstrated that uptake patterns followed first order kinetics and E. coli was inactivated with less than 5% of the initial colonies recoverable in fecal matter or tissue. Flow-through systems located at an urban impaired lake in San Francisco, CA were utilized to determine uptake kinetics under environmentally relevant conditions. The bivalves maintained a 1-log removal of E. coli for the duration of exposure. The calculated uptake rates can be used in conjunction with hydrologic models to determine the number of bivalves needed to maintain removal of E. coli in different freshwater systems. The outcomes of this study support the use of native freshwater bivalves to achieve the co-benefits of rehabilitating a freshwater ecosystem and improving water quality via reduction of E. coli in contaminated freshwater systems.

  19. Contrasting behavioral and feeding strategies recorded by tidal-flat bivalve trace fossils from the Upper Carboniferous of eastern Kansas

    USGS Publications Warehouse

    Mangano, M.G.; Buatois, L.A.; West, R.R.; Maples, C.G.

    1998-01-01

    Upper Carboniferous tidal-flat deposits near Waverly, eastern Kansas (Stull Shale Member, Kanwaka Shale Formation), host abundant and very well-preserved trace fossils attributed to the activity of burrowing bivalves. Thin shell lenses with an abundant bivalve fauna area associated with the ichnofossil-bearing beds and afford an unusual opportunity to relate trace fossils to their makers. Two distinctive life and feeding strategies can be reconstructed on the basis of trace fossil analysis and functional morphology. Lockeria siliquaria hyporeliefs commonly are connected with vertical to inclined, truncated endichnial shafts in the absence of horizontal locomotion traces. These structures record vertical and oblique displacement through the sediment, and suggest relatively stable domiciles rather than temporary resting traces as typically considered. Crowded bedding surfaces displaying cross-cutting relationships between specimens of L. siliquaria and differential preservation at the top (concave versus convex epireliefs) record a complex history of successive events of colonization, erosion, deposition, and recolonization (time-averaged assemblages). Irregujlar contours of some large hypichnia indicate the cast of the foot, while other outlines closely match the anterior area of Wilkingia, its suggested tracemaker. Relatively stable, vertical to inclined life positions and dominanit vertical mobility suggest a filter-feeding strategy. Moreover, the elongate shell and pallial sinus of Wilkingia providfe a strong independent line of evidence for an opisthosiphonate, moderately deep-tier inhabitant. Wilingia may represent a pioneer attempt at siphon-feeding in the late Paleozoic, preceding the outcome of the Mesozoic infaunal radiation. A second strategy is represented by Lockeia ornata and association locomotionm and locomotion/feding structures. Lockeia ornata is commonly connected with chevron locomotion traces that record the bifurcated foot of a protobranch

  20. The Ghost in the Shell : Local and Remote Forcing of a Coastal Bivalve Inhabiting the Humboldt Current System

    NASA Astrophysics Data System (ADS)

    Gosselin, M.

    2014-12-01

    The external skeleton of mollusc bivalves, the shell, can furnish a recording of the environmental changes to which the organisms and population are exposed during their lives. The bivalve's growth is subjected to the thermocline variability; which itself is affected by environmental and climatic events. A highly variable environment such as the Humboldt current system (HCS) requires tools capable of recording its variations over a wide range of periodicities. Upwelling, Coastal trapped waves (CTWs), El Niño Southern Oscillation, and Pacific decadal oscillation events contribute to this environmental and climatic variability. The thermocline depth is modified by these different events at their own time-scales (respectively, daily to weekly, intraseasonally, interseasonally to interannually, and on a decadal scale). The thermocline variation translates into changes in Sea surface temperature (SST) and in the qualitative and quantitative productivity of phytoplankton. These two environmental factors are critical to bivalve growth.The sclerochronological (increment width) and sclerochemical (δ18O and δ13C) study consisted on the analysis of the Chilean bivalve Eurhomalea rufa, collected in 2005, as a recorder of the environmental HCS variability. The calibration step identified daily, monthly, and annual marks in the growth patterns of E. rufa. The results confirmed that the thermocline variability mainly drives the bivalve's activity and led to the establishment of a paleotemperature equation. Moreover, periodogram and wavelet analyses exposed the respective impacts of each environmental event from daily to interannual periodicities. In particular, the growth pattern of E. rufa follows SST variability at an intraseasonal periodicity (~ 60 days) which is remotely induced by CTWs. CTWs are generated by Kelvin oceanic waves, which are formed primarily by eastward equatorial Pacific winds (e.g. Shaffer et al. 1997; Montecino and Lange 2009).Sclerochronological studies

  1. Influences of organic matter and calcification rate on trace elements in aragonitic estuarine bivalve shells

    USGS Publications Warehouse

    Takesue, R.K.; Bacon, C.R.; Thompson, J.K.

    2008-01-01

    A suite of elements (B, Na, Mg, S, K, Ca, V, Mn, Cr, Sr, and Ba) was measured in aragonitic shells of the estuarine bivalve Corbula amurensis, the Asian clam, using the Sensitive High-Resolution Ion MicroProbe with Reverse Geometry (SHRIMP RG). Our initial intent was to explore potential geochemical proxy relationships between shell chemistry and salinity (freshwater inflow) in northern San Francisco Bay (SFB). In the course of this study we observed variations in shell trace element to calcium ([M]/Ca) ratios that could only be attributed to internal biological processes. This paper discusses the nature and sources of internal trace element variability in C. amurensis shells related to the shell organic fraction and shell calcification rates. The average organic content of whole C. amurensis shells is 19%. After treating whole powdered shells with an oxidative cleaning procedure to remove organic matter, shells contained on average 33% less total Mg and 78% less total Mn. Within our analytical uncertainty, Sr and Ba contents were unchanged by the removal of organic matter. These results show that aragonitic C. amurensis shells have a large component of non-lattice-bound Mg and Mn that probably contribute to the dissimilarity of [M]/Ca profiles among five same-sized shells. Non-lattice-bound trace elements could complicate the development and application of geochemical proxy relationships in bivalve shells. Because B, Ba and Sr occur exclusively in shell aragonite, they are good candidates for external proxy relationships. [M]/Ca ratios were significantly different in prismatic and nacreous aragonite and in two valves of the same shell that had different crystal growth rates. Some part of these differences can be attributed to non-lattice-bound trace elements associated with the organic fraction. The differences in [M]/Ca ratios were also consistent with the calcification rate-dependent ion transport model developed by Carr?? et al. [Carr?? M., Bentaleb I

  2. Subcellular compartmentalization of Cd and Zn in two bivalves. II. Significance of trophically available metal (TAM)

    USGS Publications Warehouse

    Wallace, W.G.; Luoma, S.N.

    2003-01-01

    This paper examines how the subcellular partitioning of Cd and Zn in the bivalves Macoma balthica and Potamocorbula amurensis may affect the trophic transfer of metal to predators. Results show that the partitioning of metals to organelles, 'enzymes' and metallothioneins (MT) comprise a subcellular compartment containing trophically available metal (TAM; i.e. metal trophically available to predators), and that because this partitioning varies with species, animal size and metal, TAM is similarly influenced. Clams from San Francisco Bay, California, were exposed for 14 d to 3.5 ??g 1-1 Cd and 20.5 ??g 1-1 Zn, including 109Cd and 65Zn as radiotracers, and were used in feeding experiments with grass shrimp Palaemon macrodatylus, or used to investigate the subcellular partitioning of metal. Grass shrimp fed Cd-contaminated P. amurensis absorbed ???60% of ingested Cd, which was in accordance with the partitioning of Cd to the bivalve's TAM compartment (i.e. Cd associated with organelles, 'enzymes' and MT); a similar relationship was found in previous studies with grass shrimp fed Cd-contaminated oligochaetes. Thus, TAM may be used as a tool to predict the trophic transfer of at least Cd. Subcellular fractionation revealed that ???34% of both the Cd and Zn accumulated by M. balthica was associated with TAM, while partitioning to TAM in P. amurensis was metal-dependent (???60% for TAM-Cd%, ???73% for TAM-Zn%). The greater TAM-Cd% of P. amurensis than M. balthica is due to preferential binding of Cd to MT and 'enzymes', while enhanced TAM-Zn% of P. amurensis results from a greater binding of Zn to organelles. TAM for most species-metal combinations was size-dependent, decreasing with increased clam size. Based on field data, it is estimated that of the 2 bivalves, P. amurensis poses the greater threat of Cd exposure to predators because of higher tissue concentrations and greater partitioning as TAM; exposure of Zn to predators would be similar between these species.

  3. A Large Metabolic Carbon Ccontribution to the δ13C Record in Marine Aragonitic Bivalve Shells

    NASA Astrophysics Data System (ADS)

    Gillikin, D. P.; Lorrain, A.; Dehairs, F.

    2006-12-01

    The stable carbon isotopic signature archived in bivalve shells was originally thought to record the δ13C of seawater dissolved inorganic carbon (δ13C-DIC). However, more recent studies have shown that the incorporation of isotopically light metabolic carbon (M) significantly affects the δ13C signal recorded in biogenic carbonates. To assess the M contribution to Mercenaria mercenaria shells collected in North Carolina, USA, we sampled seawater δ13C-DIC, tissue, hemolymph and shell δ13C. We found up to a 4‰ decrease through ontogeny in shell δ13C in a 23 year old individual. There was no correlation between shell height or age and tissue δ13C. Thus, the ontogenic decrease observed in the shell δ13C could not be attributed to changes in food sources as the animal ages leading to more negative metabolic CO2, since this would require a negative relationship between tissue δ13C and shell height. Hemolymph δ13C, on the other hand, did exhibit a negative relationship with height, but the δ13C values were more positive than expected, indicating that hemolymph may not be a good proxy of extrapallial fluid δ13C. Nevertheless, the hemolymph data indicate that respired CO2 does influence the δ13C of internal fluids and that the amount of respired CO2 is related to the age of the bivalve. The percent metabolic C incorporated into the shell (%M) was significantly higher (up to 37%) than has been found in other bivalve shells, which usually contain less than 10 %M. Attempts to use shell biometrics to predict %M could not explain more than ~60% of the observed variability. Moreover, there were large differences in the %M between different sites. Thus, the metabolic effect on shell δ13C cannot easily be accounted for to allow reliable δ13C-DIC reconstructions. However, there does seem to be a common effect of size, as all sites had indistinguishable slopes between the %M and shell height (+0.19% per mm of shell height).

  4. Qualitative and quantitative assessment of viral contamination in bivalve molluscs harvested in Italy.

    PubMed

    Suffredini, Elisabetta; Lanni, Luigi; Arcangeli, Giuseppe; Pepe, Tiziana; Mazzette, Rina; Ciccaglioni, Gianni; Croci, Luciana

    2014-08-01

    Bivalve molluscs are a well documented source of viral infection. Further data on shellfish viral contamination are needed to implement European Regulations with sanitary measures more effective against viral pathogens. To this aim, 336 samples of bivalve molluscs (185 mussels, 66 clams, 23 oysters and 62 samples from other species) collected in harvesting areas of class A and B of four Italian Regions were analyzed for qualitative and quantitative determination of hepatitis A virus (HAV) and Norovirus (NoV) GI and GII, using real time RT-PCR. The results showed a wide diffusion of viral contamination in the shellfish production areas considered. HAV prevalence was low (0.9%) with contamination levels that varied from 5 to 7 × 10(2)copies/g. On the contrary, NoV showed a high prevalence (51.5%), with a large variability according to the group considered (e.g. 47.8% for Crassostrea in Veneto, 79.7% for Mytilus in Campania, 84.6% for Tapes in Sardinia). NoV contamination affected class A and class B production areas to a different extent, with a statistically significant difference in both contamination prevalence (22.1% vs. 66.3%; p<0.0001) and quantity (average contamination level of 3.1 × 10(2) vs. 1.9 × 10(3) copies/g; p<0.05). The different species analyzed from class B harvesting areas (Mytilus, Tapes/Ruditapes and Crassostrea) showed a NoV prevalence respectively of 70.3%, 66.0% and 47.8% but comparable NoV contamination levels (between 8.4 × 10(2) and 4.9 × 10(3)copies/g). Other two bivalve species considered in the study (Donax spp. and Solen spp.) showed a relevant NoV presence (40.0% and 34.4% of samples). Finally, samples analyzed before and after commercial purification treatment showed a decrease of contamination prevalence after the treatment, but inconsistent results were recorded on NoV levels. The data obtained, together with other quantitative information to estimate consumer exposure, in association with studies on dose-response and on the

  5. [Composition and structure of the macrofauna associated with beds of two bivalve species in Cubagua Island, Venezuela].

    PubMed

    Hernández-Avila, Iván; Tagliafico, Alejandro; Rago, Nestor

    2013-06-01

    Bivalve aggregations constitute a microhabitat for a wide variety of organisms in intertidal, subtidal and deep-water marine benthic habitats. Increase in density of bivalve beds could offer more crevices and substratum for the associated fauna, affecting community composition. Beds of the Atlantic Pearl Oyster (Pinctada imbricata) and the Turkey Wing (Arca zebra) of contrasting population densities were evaluated to determine the composition and structure of the associated macrofauna of three taxa (Crustacea Decapoda, Mollusca and Echinodermata). We evaluated plots of three levels of bed density in both species, the associated fauna were identified and counted. Other species were collected by qualitative samples. Univariate and multivariate descriptors were tested comparing the associated fauna between the beds of two species at three levels of density. In these beds a total of 104 species belonging to 58 families were recorded. Mithraculus forceps (Majidae), Crucibulum auricula (Calyptraeidae) and Ophiotrix angulata (Ophiothrichidae) were the most common species found in these assemblages. The medium and high-density bivalve beds exhibited greater species number, abundance, Shannon diversity, evenness, taxonomic diversity, and taxonomic distinctness of associated fauna, than low-density bivalve beds. Moreover, multivariate analysis detected different assemblages of associated fauna between beds with different densities. Additionally, similarities were found in the communities of macrofauna in both beds of P imbricata and Area zebra. Our results suggest that bivalve aggregations at Cubagua Island provide additional habitat for macrofauna living in other shallow habitats such as Thalassia beds, corals and rocky environments. Bed density, associated with topographic complexity, represents an important factor for the composition and complexity of the associated fauna. PMID:23885582

  6. Occurrence of pharmaceuticals and endocrine disrupting compounds in macroalgaes, bivalves, and fish from coastal areas in Europe.

    PubMed

    Álvarez-Muñoz, D; Rodríguez-Mozaz, S; Maulvault, A L; Tediosi, A; Fernández-Tejedor, M; Van den Heuvel, F; Kotterman, M; Marques, A; Barceló, D

    2015-11-01

    The occurrence and levels of PhACs, Endocrine Disrupting and related Compounds (EDCs) in seafood from potential contaminated areas in Europe has been studied. Macroalgae (Saccharina latissima and Laminaria digitata), bivalves (Mytilus galloprovincialis, Mytilus spp., Chamalea gallina and Crassostrea gigas) and fish (Liza aurata and Platichthys flesus) from Portugal, Spain, Italy, Netherlands, and Norway were analysed following 4 different analytical protocols depending on the organism and target group of contaminants. The results revealed the presence of 4 pharmaceutical compounds in macroalgae samples, 16 in bivalves and 10 in fish. To the best of our knowledge, this is the first time that PhACs have been detected in marine fish and in macroalgae. Besides, this is also the first time that dimetridazole, hydrochlorothiazide and tamsulosin have been detected in biota samples. The highest levels of PhACs corresponded to the psychiatric drug velanfaxine (up to 36.1 ng/g dry weight (dw)) and the antibiotic azithromycin (up to 13.3 ng/g dw) in bivalves from the Po delta (Italy). EDCs were not detected in macroalgae samples, however, the analysis revealed the presence of 10 EDCs in bivalves and 8 in fish. The highest levels corresponded to the organophosphorus flame retardant tris(2-butoxyethyl)phosphate (TBEP) reaching up to 98.4 ng/g dw in mullet fish from the Tagus estuary. Bivalves, in particular mussels, have shown to be good bioindicator organisms for PhACs and fish for EDCs. Taking into consideration the concentrations and frequencies of detection of PhACs and EDCs in the seafood samples analysed, a list of candidates' compounds for priorization in future studies has been proposed.

  7. Biologically Induced Deposition of Fine Suspended Particles by Filter-Feeding Bivalves in Land-Based Industrial Marine Aquaculture Wastewater

    PubMed Central

    Zhou, Yi; Zhang, Shaojun; Liu, Ying; Yang, Hongsheng

    2014-01-01

    Industrial aquaculture wastewater contains large quantities of suspended particles that can be easily broken down physically. Introduction of macro-bio-filters, such as bivalve filter feeders, may offer the potential for treatment of fine suspended matter in industrial aquaculture wastewater. In this study, we employed two kinds of bivalve filter feeders, the Pacific oyster Crassostrea gigas and the blue mussel Mytilus galloprovincialis, to deposit suspended solids from marine fish aquaculture wastewater in flow-through systems. Results showed that the biodeposition rate of suspended particles by C. gigas (shell height: 8.67±0.99 cm) and M. galloprovincialis (shell height: 4.43±0.98 cm) was 77.84±7.77 and 6.37±0.67 mg ind−1•d−1, respectively. The total solid suspension (TSS) deposition rates of oyster and mussel treatments were 3.73±0.27 and 2.76±0.20 times higher than that of the control treatment without bivalves, respectively. The TSS deposition rates of bivalve treatments were significantly higher than the natural sedimentation rate of the control treatment (P<0.001). Furthermore, organic matter and C, N in the sediments of bivalve treatments were significantly lower than those in the sediments of the control (P<0.05). It was suggested that the filter feeders C. gigas and M. galloprovincialis had considerable potential to filter and accelerate the deposition of suspended particles from industrial aquaculture wastewater, and simultaneously yield value-added biological products. PMID:25250730

  8. Biologically induced deposition of fine suspended particles by filter-feeding bivalves in land-based industrial marine aquaculture wastewater.

    PubMed

    Zhou, Yi; Zhang, Shaojun; Liu, Ying; Yang, Hongsheng

    2014-01-01

    Industrial aquaculture wastewater contains large quantities of suspended particles that can be easily broken down physically. Introduction of macro-bio-filters, such as bivalve filter feeders, may offer the potential for treatment of fine suspended matter in industrial aquaculture wastewater. In this study, we employed two kinds of bivalve filter feeders, the Pacific oyster Crassostrea gigas and the blue mussel Mytilus galloprovincialis, to deposit suspended solids from marine fish aquaculture wastewater in flow-through systems. Results showed that the biodeposition rate of suspended particles by C. gigas (shell height: 8.67 ± 0.99 cm) and M. galloprovincialis (shell height: 4.43 ± 0.98 cm) was 77.84 ± 7.77 and 6.37 ± 0.67 mg ind(-1) • d(-1), respectively. The total solid suspension (TSS) deposition rates of oyster and mussel treatments were 3.73 ± 0.27 and 2.76 ± 0.20 times higher than that of the control treatment without bivalves, respectively. The TSS deposition rates of bivalve treatments were significantly higher than the natural sedimentation rate of the control treatment (P < 0.001). Furthermore, organic matter and C, N in the sediments of bivalve treatments were significantly lower than those in the sediments of the control (P < 0.05). It was suggested that the filter feeders C. gigas and M. galloprovincialis had considerable potential to filter and accelerate the deposition of suspended particles from industrial aquaculture wastewater, and simultaneously yield value-added biological products. PMID:25250730

  9. Biologically induced deposition of fine suspended particles by filter-feeding bivalves in land-based industrial marine aquaculture wastewater.

    PubMed

    Zhou, Yi; Zhang, Shaojun; Liu, Ying; Yang, Hongsheng

    2014-01-01

    Industrial aquaculture wastewater contains large quantities of suspended particles that can be easily broken down physically. Introduction of macro-bio-filters, such as bivalve filter feeders, may offer the potential for treatment of fine suspended matter in industrial aquaculture wastewater. In this study, we employed two kinds of bivalve filter feeders, the Pacific oyster Crassostrea gigas and the blue mussel Mytilus galloprovincialis, to deposit suspended solids from marine fish aquaculture wastewater in flow-through systems. Results showed that the biodeposition rate of suspended particles by C. gigas (shell height: 8.67 ± 0.99 cm) and M. galloprovincialis (shell height: 4.43 ± 0.98 cm) was 77.84 ± 7.77 and 6.37 ± 0.67 mg ind(-1) • d(-1), respectively. The total solid suspension (TSS) deposition rates of oyster and mussel treatments were 3.73 ± 0.27 and 2.76 ± 0.20 times higher than that of the control treatment without bivalves, respectively. The TSS deposition rates of bivalve treatments were significantly higher than the natural sedimentation rate of the control treatment (P < 0.001). Furthermore, organic matter and C, N in the sediments of bivalve treatments were significantly lower than those in the sediments of the control (P < 0.05). It was suggested that the filter feeders C. gigas and M. galloprovincialis had considerable potential to filter and accelerate the deposition of suspended particles from industrial aquaculture wastewater, and simultaneously yield value-added biological products.

  10. Apoptosis and histopathological lesions in parasite-infected species of bivalve molluscs.

    PubMed

    Abdel Aziz, Ahmed

    2009-12-01

    Apoptosis (programmed cell death) is an important mechanism for preservation of a healthy and balanced immune system in vertebrates. Little is known, however, about how apoptosis processes regulate invertebrate immune system. Thus, the present histopathological study was performed to search for the level of apoptosis on hemocytes of three bivalve species namely, Macoma edentula, Hiatula rupelliana and Gastrana fraglis in the Timsah Lake infected with branchial Rickettsia-like parasites and ciliated parasites in the digestive gland. Microscopically, special to elongated intracytoplasmic Rickettsia-like colonies were observed in the base of gill filaments of the clams. Histologically, the distribution and shapes of apoptotic cells were classified into three main types. The aggregation of apoptotic cells were observed in the apical and the basal parts of the ciliated cells lining the gill epithelium. These results provide a first insight into apoptotic processes in mollusc immune cells.

  11. Transfection of eggs in the bivalve mollusc Chamelea gallina (Bivalvia, Veneridae).

    PubMed

    Guerra, R; Esponda, P

    2006-04-01

    Eggs from the bivalve mollusc Chamelea gallina were transfected in vitro. The p-GeneGrip gene construction that expresses the green fluorescent protein (GFP) was employed. It was necessary to remove the jelly coat which covers the egg surface for a successful transfection, and then 44.2% of gametes appeared transfected after using naked DNA. On the other hand, cationic liposomes (Lipofectamine) and neutral lipids (GenePORTER) were employed as gene vectors. After the employ of Lipofectamine 35.6% of eggs were transfected and 41.4% after using GenePORTER. Fluorescence analysis showed that the foreign gene appeared principally located in the egg cytoplasm, but laser confocal microscopy showed that it was also present in the nucleus. Furthermore, PCR analysis demonstrated that the foreign DNA appeared in the DNA extracted from the treated eggs. This simple method for the transfection of mollusc eggs would be interesting for future biotechnological applications in species of commercial interest. PMID:17283962

  12. Assessment of the metal bioaccumulation in three species of freshwater bivalves.

    PubMed

    Waykar, Bhalchandra; Shinde, Satish Madhukar

    2011-09-01

    The metal concentration and body burden of three species of fresh water bivalves, Parreysia cylindrica, Parreysia corrugata and Corbicula striatella were estimated in laboratory experiment after exposure to chronic concentration of arsenic (0.1719 ppm), cadmium (0.23 ppm), copper (0.13 ppm), mercury (0.06 ppm), lead (2.4 ppm) and zinc (5.1 ppm) separately up to 30 days. Dry weight of each animal was used to calculate metal concentrations (μg/g) and the metal body burden (μg/individual). It was observed that zinc, lead and copper concentration and metal body burden was highest in the Corbicula striatella, mercury and arsenic was highest in Parreysia corrugata and cadmium was highest in Parreysia cylindrica. Therefore, Corbicula striatella is being proposed as sentinel organism for monitoring of zinc, lead and copper, Parreysia corrugata for mercury and arsenic, and Parreysia cylindrica for cadmium in fresh water ecosystem.

  13. Mucus-exopolymer utilization by two bivalves with different feeding strategies

    SciTech Connect

    Decho, A.W.; Luoma, S.N. )

    1990-01-09

    The utilization and absorption efficiencies of bacterial exopolymer secretaions were examined using two bivalves from San Francisco Bay, which exhibit different feeding strategies. Macoma balthica is primarily a deposit-feeder, exhibiting relatively slow gut-passage time (4-12 hrs). Theasian clam Potamocorbula amurensis is a suspension-feeder and exhibits a relatively fast gut-passage time (15-0- min). [sup 14]C-exopolymer was readily utilized both animals and with similar absorption efficiencies (40-70%). It appears that this bacterial exopolymer represents an easily utilized food resource for both animals. The adsorption of heavy metals to the exopolymer and their subsequent uptake by animals are currently under investigation. Their role as an agent in transferring heavy metals to deposit- and suspension-feeding animals will be discussed.

  14. The effects of carbamazepine on macroinvertebrate species: Comparing bivalves and polychaetes biochemical responses.

    PubMed

    Freitas, Rosa; Almeida, Ângela; Pires, Adília; Velez, Cátia; Calisto, Vânia; Schneider, Rudolf J; Esteves, Valdemar I; Wrona, Frederick J; Figueira, Etelvina; Soares, Amadeu M V M

    2015-11-15

    In the present study, the bivalve Scrobicularia plana and the polychaete Diopatra neapolitana were exposed to an increasing carbamazepine (CBZ) concentration gradient. Both species are among the most widely used bioindicators, and CBZ is one of the most commonly found drugs in the aquatic environment. After a chronic exposure (28 days), the results obtained revealed that CBZ induced biochemical alterations in both species. Our findings demonstrated that S. plana and D. neapolitana reduced the CBZ accumulation rate at higher CBZ concentrations, probably due to their capacity to decrease their feeding rates at stressful conditions. Nevertheless, this defence mechanism was not enough to prevent both species from oxidative stress. In fact, S. plana and D. neapolitana were not able to efficiently activate their antioxidant defence mechanisms which resulted in the increase of lipid peroxidation, especially at the highest CBZ concentrations. Comparing both species, it seems that S. plana was the most sensitive species since stronger biochemical alterations were observed in this species.

  15. Physiological status and intersex in the endobenthic bivalve Scrobicularia plana from thirteen estuaries in northwest France.

    PubMed

    Tankoua, O Fossi; Amiard-Triquet, C; Denis, F; Minier, C; Mouneyrac, C; Berthet, B

    2012-08-01

    The bivalve Scrobicularia plana, an important species for the structure and functioning of estuarine and coastal mudflats, was studied in thirteen sites from NW France differing by their degree of contamination to document the presence of reproduction impairments (intersex, sex ratio, gonadosomatic indices) in relation to the condition revealed by using hepatosomatic and condition indices. In agreement with recent studies in other European estuaries, intersex was revealed in all the studied estuaries, including sites the chemical and ecological status of which is considered "good" according to the criteria of the European Water Framework Directive. The presence of endocrine disrupting chemicals (EDCs) could result in such disturbances. Our results re-inforce the concern linked to the subtle effects of EDCs, which are active at very low doses, often in the absence of any major sign of toxicity. However at this stage, no clear link may be established between intersex and population effects.

  16. Ultrastructure of the mature spermatozoon of the bivalve Scapharca broughtoni (Mollusca: Bivalvia: Arcidae).

    PubMed

    Zhu, Jun-Quan; Dahms, Hans-Uwe; Yang, Wan-Xi

    2008-12-01

    The ultrastructure of mature spermatozoa of the giant clam bivalve Scapharca broughtoni was investigated by transmission electron microscopy for the first time. The mature spermatozoon consists of a head which is composed of a cone-shaped acrosome, a round nucleus, and a tail region. A subacrosomal space contains an axial rod and a basal plate, the latter lying between the acrosome and the nucleus. Although the nucleus lacks an anterior invagination, an inverted shallow V-shaped posterior invagination is present within the nucleus. Within the middle portion of the spermatozoon lie five spherical mitochondria while the long whip-like end portion is composed of an axoneme with the typical 9+2 structure. Our conclusion is that the spermatozoon of S. broughtoni is of the type I anacrosomal "aquasperm", and the morphology of acrosome and nucleus are an adaptation to external fertilization.

  17. Assessment of metal contamination in coastal sediments, seawaters and bivalves of the Mediterranean Sea coast, Egypt.

    PubMed

    El-Sorogy, Abdelbaset S; Attiah, Abdullah

    2015-12-30

    In order to assess metal contamination on the Mediterranean coast of Egypt, 45 sediment samples, seawaters and bivalve specimens were collected from Rosetta coastal area for Mg, Al, K, Fe, Sr, Zn, Pb, Mn, As, Ce, Ni, Cr and Zr analyses by Inductively Coupled Plasma-Mass Spectrometer. The Enrichment Factor (EF), the Geoaccumulation Index (Igeo) and the Contamination Factor (CF) indicated that the coastal sediments of Rosetta area were severely enriched, strongly polluted with As, Pb and very highly contaminated with As, Pb, Ni, Ce, mostly as a result of anthropogenic inputs. Comparison with other samples from the Arabian Gulf, Red Sea and abroad coasts suggested that the studied samples have higher concentrations of Fe, Pb, As, Zn and Ni. The natural sources of heavy metals in the study area are attributed to weathering and decomposition of mountain ranges of the Sudan and Ethiopia, while the anthropogenic ones are the metals produced from industrial, sewage, irrigation and urban runoff.

  18. Assessment of metal contamination in coastal sediments, seawaters and bivalves of the Mediterranean Sea coast, Egypt.

    PubMed

    El-Sorogy, Abdelbaset S; Attiah, Abdullah

    2015-12-30

    In order to assess metal contamination on the Mediterranean coast of Egypt, 45 sediment samples, seawaters and bivalve specimens were collected from Rosetta coastal area for Mg, Al, K, Fe, Sr, Zn, Pb, Mn, As, Ce, Ni, Cr and Zr analyses by Inductively Coupled Plasma-Mass Spectrometer. The Enrichment Factor (EF), the Geoaccumulation Index (Igeo) and the Contamination Factor (CF) indicated that the coastal sediments of Rosetta area were severely enriched, strongly polluted with As, Pb and very highly contaminated with As, Pb, Ni, Ce, mostly as a result of anthropogenic inputs. Comparison with other samples from the Arabian Gulf, Red Sea and abroad coasts suggested that the studied samples have higher concentrations of Fe, Pb, As, Zn and Ni. The natural sources of heavy metals in the study area are attributed to weathering and decomposition of mountain ranges of the Sudan and Ethiopia, while the anthropogenic ones are the metals produced from industrial, sewage, irrigation and urban runoff. PMID:26563548

  19. The Presence of Histamine and a Histamine Receptor in the Bivalve Mollusc, Crassostrea virginica

    PubMed Central

    Harrison, Jarreau; LaFleur, Kisha; Mantone, Daniel; Boisette, Beatrix; Harris, Ave; Catapane, Edward J.; Carroll, Margaret A.

    2015-01-01

    Histamine, a biogenic amine, is a neurotransmitter in neurons and sensory receptors in invertebrates. Histamine has rarely been reported in bivalves. We used HPLC with pre-column derivatization using 2,3-naphthalenedicarboxaldehyde (NDA) as a fluorescent labeling agent to measure histamine in ganglia, and peripheral tissues of the oyster Crassostrea virginica. We also used Western Blot technique to look for the presence of a histamine receptor in the mantle rim. HPLC results found histamine present in ng amounts in both the cerebral and visceral ganglia, as well as the mantle rim and other peripheral tissues of C. virginica. The study confirms and quantifies histamine as an endogenous biogenic amine in C. virginica in the nervous system and innervated organs. Western Blot technique also identified a histamine H2-like receptor present in sensory tissue of the oyster's mantle rim. PMID:26120600

  20. [FTIR spectroscopic study on natural aragonitic ceramics-bivalve shells of Hyriopsis cumingii].

    PubMed

    Ding, Shi-lei; Zhang, Gang-sheng

    2006-12-01

    The two shell layers, i. e. , the ligament (HCL) and the inner nacreous layers (HCN) from bivalve shells of Hyriopsis cumingii, both composed of aragonite by powder XRD analysis, w ere comparatively analyzed by FT IR spectrometry. The results show that: (1) the features of vz and v3 bands of aragonite are clearly different between the two shell layers, as the v2 band of HCN aragonite shows a 6. 5 cm(-1) blue-shift, but the vs band shows a 22. 7 cm(-1) red-shift compared to that of HCL aragonite; (2) the full width at half maximum of v1 and v3 bands of HCN aragonite is nearly doubled compared to that of HCL aragonite; (3) however, the features of v1 and v4 bands are independent on shell layers. It is suggested that the anisotropic frequency shifts of the aragonite in HCN and HCL perhaps result from the size effects of aragonite crystals.

  1. Scale-up of ecological experiments: Density variation in the mobile bivalve Macomona liliana

    USGS Publications Warehouse

    Schneider, D.C.; Walters, R.; Thrush, S.; Dayton, P.

    1997-01-01

    At present the problem of scaling up from controlled experiments (necessarily at a small spatial scale) to questions of regional or global importance is perhaps the most pressing issue in ecology. Most of the proposed techniques recommend iterative cycling between theory and experiment. We present a graphical technique that facilitates this cycling by allowing the scope of experiments, surveys, and natural history observations to be compared to the scope of models and theory. We apply the scope analysis to the problem of understanding the population dynamics of a bivalve exposed to environmental stress at the scale of a harbour. Previous lab and field experiments were found not to be 1:1 scale models of harbour-wide processes. Scope analysis allowed small scale experiments to be linked to larger scale surveys and to a spatially explicit model of population dynamics.

  2. Response of the freshwater bivalve Anodonta grandis to Cd near the Canadian Water Quality Guideline

    SciTech Connect

    Stewart, A.R.; Malley, D.F. |

    1994-12-31

    The bivalve population inhabiting Lake 382 in the Experimental Lakes Area, northwestern Ontario, receiving experimental additions of cadmium (Cd) near the Canadian Water Quality Guideline (CWQG) was monitored for effects during 1987 to 1992. the purpose of the study was to determine if the CWQG of 0.2 {mu}g Cd/L would adequately protect the biota of the Precambrian Shield Lakes. Mussels accumulated Cd to whole body levels 30X background. Cd levels in the mussels did not plateau by the end of 1992 and continues to increase. Metal-binding proteins metallothioneins (MTs) were induced in all tissues to levels significantly higher than in tissues of mussels from a pristine lake. Although mussel growth rates differed from site to site within Lake 382, there was no change in growth rates with the addition of Cd.

  3. Biodepuration of petroleum-derived polynuclear aromatic hydrocarbons from a bivalve mollusc

    SciTech Connect

    Tanacredi, J.T.

    1988-01-01

    Two species of bivalves, Mya arenaria and Mercenaria mercenaria were analyzed to identify and quantify nine polynuclear aromatic hydrocarbons attributable to either natural environmental accumulation, or attributable to exposure in controlled laboratory aquarium system, respectively. Extracts from naturally occurring (e.g. Jamaica bay) and laboratory maintained organism samples were characterized using a 9-PAH reference exposure standard. The results clearly show that in-vitro exposed Mercenaria mercenaria sampled over a 45-day depuration period, do not depurate the 9-PAH's but rather bioaccumulate them at detectable levels. Due to the commercial importance of these clam species for human consumption, and the fact that these PAH's are toxic, mutagenic and carcinogenic, the practice of clam depuration and clam relaying must be re-evaluated in light of potential public health implications.

  4. Bivalve network reveals latitudinal selectivity gradient at the end-Cretaceous mass extinction

    PubMed Central

    Vilhena, Daril A.; Harris, Elisha B.; Bergstrom, Carl T.; Maliska, Max E.; Ward, Peter D.; Sidor, Christian A.; Strömberg, Caroline A. E.; Wilson, Gregory P.

    2013-01-01

    Biogeographic patterns of survival help constrain the causal factors responsible for mass extinction. To test whether biogeography influenced end-Cretaceous (K-Pg) extinction patterns, we used a network approach to delimit biogeographic units (BUs) above the species level in a global Maastrichtian database of 329 bivalve genera. Geographic range is thought to buffer taxa from extinction, but the number of BUs a taxon occurred in superseded geographic range as an extinction predictor. Geographically, we found a latitudinal selectivity gradient for geographic range in the K-Pg, such that higher latitude BUs had lower extinction than expected given the geographic ranges of the genera, implying that (i) high latitude BUs were more resistant to extinction, (ii) the intensity of the K-Pg kill mechanism declined with distance from the tropics, or (iii) both. Our results highlight the importance of macroecological structure in constraining causal mechanisms of extinction and estimating extinction risk of taxa.

  5. Pan-Svalbard growth rate variability and environmental regulation in the Arctic bivalve Serripes groenlandicus

    NASA Astrophysics Data System (ADS)

    Carroll, Michael L.; Ambrose, William G.; Levin, Benjamin S.; Locke V, William L.; Henkes, Gregory A.; Hop, Haakon; Renaud, Paul E.

    2011-11-01

    Growth histories contained in the shells of bivalves provide continuous records of environmental and biological information over lifetimes spanning decades to centuries, thereby linking ecosystem responses to both natural and anthropogenic climatic variations over a range of scales. We examined growth rates and temporal growth patterns of 260 individuals of the circumpolar Greenland Smooth Cockle ( Serripes groenlandicus) collected between 1997 and 2009 from 11 sites around the Svalbard Archipelago. These sites encompass a range of oceanographic and environmental conditions, from strongly Atlantic-influenced conditions on the west coast to high-Arctic conditions in northeast Svalbard. Absolute growth was up to three times greater at the most strongly Atlantic-influenced locations compared to the most Arctic-influenced areas, and growth performance was highest at sites closest to the West Spitsbergen Current. We also developed growth chronologies up to 34 years in length extending back to 1974. Standardized growth indices (SGI) exhibited substantial inter-site variability, but there were also common temporal features including steadily increasing growth from the late 1980's to the mid-1990's followed by a marked shift from relatively greater to poorer growth in the mid-1990's and from 2004 to 2008. This pattern was consistent with phase-shifts in large-scale climatic drivers. Interannual variability in SGI was also related to local manifestations of the large-scale drivers, including sea temperature and sea ice extent. The temporal growth pattern at Rijpfjorden, on northeast Svalbard, was broadly representative (R = 0.81) of the entire dataset. While there were site-related differences in the specific relationships between growth and environmental parameters, the aggregated dataset indicated an overriding regional driver of bivalve growth: the Arctic Climate Regime Index (ACRI). These results demonstrate that sclerochronological proxies can be useful retrospective

  6. Impact of seawater carbonate chemistry on the calcification of marine bivalves

    NASA Astrophysics Data System (ADS)

    Thomsen, J.; Haynert, K.; Wegner, K. M.; Melzner, F.

    2015-07-01

    Bivalve calcification, particularly of the early larval stages, is highly sensitive to the change in ocean carbonate chemistry resulting from atmospheric CO2 uptake. Earlier studies suggested that declining seawater [CO32-] and thereby lowered carbonate saturation affect shell production. However, disturbances of physiological processes such as acid-base regulation by adverse seawater pCO2 and pH can affect calcification in a secondary fashion. In order to determine the exact carbonate system component by which growth and calcification are affected it is necessary to utilize more complex carbonate chemistry manipulations. As single factors, pCO2 had no effects and [HCO3-] and pH had only limited effects on shell growth, while lowered [CO32-] strongly impacted calcification. Dissolved inorganic carbon (CT) limiting conditions led to strong reductions in calcification, despite high [CO32-], indicating that [HCO3-] rather than [CO32-] is the inorganic carbon source utilized for calcification by mytilid mussels. However, as the ratio [HCO3-] / [H+] is linearly correlated with [CO32-] it is not possible to differentiate between these under natural seawater conditions. An equivalent of about 80 μmol kg-1 [CO32-] is required to saturate inorganic carbon supply for calcification in bivalves. Below this threshold biomineralization rates rapidly decline. A comparison of literature data available for larvae and juvenile mussels and oysters originating from habitats differing substantially with respect to prevailing carbonate chemistry conditions revealed similar response curves. This suggests that the mechanisms which determine sensitivity of calcification in this group are highly conserved. The higher sensitivity of larval calcification seems to primarily result from the much higher relative calcification rates in early life stages. In order to reveal and understand the mechanisms that limit or facilitate adaptation to future ocean acidification, it is necessary to better

  7. Bivalves as indicators of environmental variation and potential anthropogenic impacts in the southern Barents Sea.

    PubMed

    Carroll, Michael L; Johnson, Beverly J; Henkes, Gregory A; McMahon, Kelton W; Voronkov, Andrey; Ambrose, William G; Denisenko, Stanislav G

    2009-01-01

    Identifying patterns and drivers of natural variability in populations is necessary to gauge potential effects of climatic change and the expected increases in commercial activities in the Arctic on communities and ecosystems. We analyzed growth rates and shell geochemistry of the circumpolar Greenland smooth cockle, Serripes groenlandicus, from the southern Barents Sea over almost 70 years between 1882 and 1968. The datasets were calibrated via annually-deposited growth lines, and growth, stable isotope (delta(18)O, delta(13)C), and trace elemental (Mg, Sr, Ba, Mn) patterns were linked to environmental variations on weekly to decadal scales. Standardized growth indices revealed an oscillatory growth pattern with a multi-year periodicity, which was inversely related to the North Atlantic Oscillation Index (NAO), and positively related to local river discharge. Up to 60% of the annual variability in Ba/Ca could be explained by variations in river discharge at the site closest to the rivers, but the relationship disappeared at a more distant location. Patterns of delta(18)O, delta(13)C, and Sr/Ca together provide evidence that bivalve growth ceases at elevated temperatures during the fall and recommences at the coldest temperatures in the early spring, with the implication that food, rather than temperature, is the primary driver of bivalve growth. The multi-proxy approach of combining the annually integrated information from the growth results and higher resolution geochemical results yielded a robust interpretation of biophysical coupling in the region over temporal and spatial scales. We thus demonstrate that sclerochronological proxies can be useful retrospective analytical tools for establishing a baseline of ecosystem variability in assessing potential combined impacts of climatic change and increasing commercial activities on Arctic communities. PMID:19394657

  8. Using transplanted bivalves to assess oil exposure and effects in Delaware Bay

    SciTech Connect

    Salazar, M.; Salazar, S.; Mearns, A.; Venosa, A.; Eberhart, B.

    1995-12-31

    To evaluate the effectiveness of bioremediation, the US EPA oiled intertidal plots in Delaware Bay and monitored oil degradation rates. This controlled release of oil was also used to test the utility of transplanted bivalves in assessing oil spills and to evaluate the extent and potential effects of the release. Measuring the accumulation of oil in bivalve tissues was used to estimate exposure and the extent of contamination. Growth was used to estimate potential bioeffects. Approximately 1,800 mussels and 1,200 oysters were transplanted to 11 intertidal sites. Five treatment sites were within 1 meter of the lower end of the oiled plots. A total of six sites were used as controls, three on either side of the oiled plots at 5, 10, and 100 m. Samples were taken on Day 0, 2, 15, and 28 to estimate the rate of bioaccumulation. All of the mussels died within the first week of exposure; oysters exhibited over 95% survival but growth was minimal. The authors found a statistically significant difference in tissue weights when comparing treatment sites with control sites. The total concentration of polynuclear aromatic hydrocarbons (PAHs) in tissues of oysters nearest the oiled plots increased by a factor of four after an exposure period of two days. PAH concentrations in control oysters nearest the mouth of the bay increased slightly but the differences were not statistically significant. The control oysters nearest the head of the bay received an intermediate dose which was depurated by the end of the 28-day experiment. PAHs in the oysters nearest the oiled plots approached but did not return to background levels by the end of the test.

  9. Bivalves as indicators of environmental variation and potential anthropogenic impacts in the southern Barents Sea

    PubMed Central

    Carroll, Michael L.; Johnson, Beverly J.; Henkes, Gregory A.; McMahon, Kelton W.; Voronkov, Andrey; Ambrose, William G.; Denisenko, Stanislav G.

    2009-01-01

    Identifying patterns and drivers of natural variability in populations is necessary to gauge potential effects of climatic change and the expected increases in commercial activities in the Arctic on communities and ecosystems. We analyzed growth rates and shell geochemistry of the circumpolar Greenland smooth cockle, Serripes groenlandicus, from the southern Barents Sea over almost 70 years between 1882 and 1968. The datasets were calibrated via annually-deposited growth lines, and growth, stable isotope (δ18O, δ13C), and trace elemental (Mg, Sr, Ba, Mn) patterns were linked to environmental variations on weekly to decadal scales. Standardized growth indices revealed an oscillatory growth pattern with a multi-year periodicity, which was inversely related to the North Atlantic Oscillation Index (NAO), and positively related to local river discharge. Up to 60% of the annual variability in the Ba/Ca could be explained by variations in river discharge at the site closest to the rivers, but the relationship disappeared at a more distant location. Patterns of δ18O, δ13C, and Sr/Ca together provide evidence that bivalve growth ceases at elevated temperatures during the fall and recommences at the coldest temperatures in the early spring, with the implication that food, rather than temperature, is the primary driver of bivalve growth. The multi-proxy approach of combining the annually integrated information from the growth results and higher resolution geochemical results yielded a robust interpretation of biophysical coupling in the region over temporal and spatial scales. We thus demonstrate that sclerochronological proxies can be useful retrospective analytical tools for establishing a baseline of ecosystem variability in assessing potential combined impacts of climatic change and increasing commercial activities on Arctic communities. PMID:19394657

  10. The biological importance of glutathione peroxidase and peroxiredoxin backup systems in bivalves during peroxide exposure.

    PubMed

    Trevisan, Rafael; Mello, Danielle Ferraz; Uliano-Silva, Marcela; Delapedra, Gabriel; Arl, Miriam; Dafre, Alcir Luiz

    2014-10-01

    Organic peroxide elimination in eukaryotes essentially depends on glutathione peroxidase (GPx) and peroxiredoxin (Prx) enzymes, which are supported by their respective electron donors, glutathione (GSH) and thioredoxin (Trx). This system depends on the ancillary enzymes glutathione reductase (GR) and thioredoxin reductase (TrxR) to maintain GSH and Trx in their reduced state. This study discusses the biological importance of GR and TrxR in supporting GPx and Prx during cumene hydroperoxide (CHP) exposure in brown mussel Perna perna. ZnCl2 or 1-chloro-2,4-dinitrobenze (CDNB) was used to decrease GR and TrxR activities in gills, as already reported with mammals and bivalves. ZnCl2 exposure lowered GR activity (28%), impaired the in vivo CHP decomposition and decreased the survival rates under CHP exposure. CDNB decreased GR (54%) and TrxR (73%) activities and induced glutathione depletion (99%), promoting diminished peroxide elimination and survival rates at a greater extent than ZnCl2. CDNB also increased the susceptibility of hemocytes to CHP toxicity. Despite being toxic and causing mortality at longer exposures, short (2 h) exposure to CHP promoted an up regulation of GSH (50 and 100 μM CHP) and protein-thiol (100 μM CHP) levels, which was blocked by ZnCl2 or CDNB pre-exposure. Results highlight the biological importance of GSH, GR and TrxR in supporting GPx and Prx activities, contributing to organic peroxides elimination and mussel survival under oxidative challenges. To our knowledge, this is the first work that demonstrates, albeit indirectly, the biological importance of GPx/GR/GSH and Prx/TrxR/Trx systems on in vivo organic peroxide elimination in bivalves.

  11. Organochlorine accumulation on a highly consumed bivalve (Scrobicularia plana) and its main implications for human health.

    PubMed

    Grilo, T F; Cardoso, P G; Pato, P; Duarte, A C; Pardal, M A

    2013-09-01

    Contamination by polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) was investigated along a spatial gradient in water, sediments and in commercially important bivalve species Scrobicularia plana, from Ria de Aveiro (Portugal). Organochlorines dissolved in water were below detection limit and concerning suspended particulate matter, only PCBs were quantified, ranging from 3.8 to 5.8 ng∙g(-1) DW (Σ13PCBs). There was a distinct spatial gradient regarding PCB accumulation in sediments. The highest concentrations were found in deeper layers and closest to the pollution source, decreasing gradually along a 3 km area. Contamination in sediments exceeded the Canadian and Norwegian sediment quality guidelines, inducing potential toxic effects in related biota. PCBs tended to bioaccumulate throughout S. plana lifespan but with different annual rates along the spatial gradient. The maximum values were found in older individuals up to 3+ years old, reaching 19.4 ng∙g(-1) DW. HCB concentrations were residual and no bioaccumulation pattern was evident. Congeners 138, 153 and 180 were the most accumulated due to their abundance and long-term persistence in the environment. In the inner area of the Laranjo Bay (0.6 km(2)), the species was able to remove up to 0.4 g of PCBs annually from sediments into their own tissues, which is consequently free for trophic transfer (biomagnification). Concerning human health, and despite the high concentrations found in sediments, PCB levels in bivalves do not exceed the limit established by the European Union for fishery products and are largely below tolerable daily intake. Although PCBs in Scrobicularia plana are present at low levels, their impact to human health after consumption over many years might be harmful and should be monitored in future studies.

  12. Record of seasonal body fluid composition in Black Clam (Bivalve) using clumped isotope thermometric approach

    NASA Astrophysics Data System (ADS)

    Rahman, H.; Naidu, P. K.; Ghosh, P.

    2012-12-01

    Application of clumped isotope thermometry (Ghosh et al., 2006) is highly debated while resolving the issue of kinetic effect during biogenic carbonate precipitation. Mollusks are particularly attractive target to study the kinetic effect (Eiler, 2011) in the biological system owing to its incremental growth ring patterns. This allows understanding the role of environmental parameters other than temperature driving the distribution of heavier isotopologues. Guo et al., (2010) indicated role of pH in driving the distribution of heavier isotopolgues in the carbonates. We investigated here clumped isotopic composition of Black Calm (bivalve shell) caught live from a location in Southern Indian Estuary. The region experiences large change in seasonal condition. The physical environmental parameters at that location were monitored for last 3 years at monthly interval. The salinity, temperature, pH information are available for all the months when mollusc growth bands are deposited. The bottom water of estuary, where bivalve thrives experience maximum temperature of 32°C during November and December, while temperature during Monsoon months (July, August) drops lows to 26°C. Initial results on clumped isotope thermometry on the growth bands precipitated suggests that during the time in a year when pH level is alkaline i.e. 8.0±0.2 there is large consistency between actual temperature and estimated temperature using clumped isotope based thermometry. While the pH drops towards acidic i.e. 6.8±0.1 lower temperature estimates compared to actual was recorded. The effect of metabolic rate and body temperature variability is not been investigated as suggested in case of land snails based clumped isotope thermometry (Zaarur et al., 2011). Mollusc shell can be used to trace the composition of environmental water while pH variation is minimal. In this presentation analyses of more shell specimen and explore the role of pH and osmo-regulation in mollusc determining the clumped

  13. Clarifying phylogenetic relationships and the evolutionary history of the bivalve order Arcida (Mollusca: Bivalvia: Pteriomorphia).

    PubMed

    Combosch, David J; Giribet, Gonzalo

    2016-01-01

    The systematics of the bivalve order Arcida constitutes an unresolved conundrum in bivalve systematics. The current definition of Arcida encompasses two superfamilies: Limopsoidea, which includes the recent families Philobryidae and Limopsidae, and Arcoidea, which encompasses the families Arcidae, Cucullaeidae, Noetiidae, Glycymerididae and Parallelodontidae. This classification, however, is controversial particularly with respect to the position and taxonomic status of Glycymerididae. Previous molecular phylogenies were limited either by the use of only a single molecular marker or by including only a few limopsoid and glycymeridid taxa. The challenging nature of Arcida taxonomy and the controversial results of some of the previous studies, prompted us to use a broad range of taxa (55 species), three nuclear markers (18S rRNA, 28S rRNA and histone H3) and a wide range of algorithmic approaches. This broad but stringent approach led to a number of results that differ significantly from previous studies. We provide the first molecular evidence that supports the separation of Arcoidea from Limopsoidea, although the exact position of Glycymerididae remains unresolved, and the monophyly of Limopsoidea is algorithm-dependent. In addition, we present the first time-calibrated evolutionary tree of Arcida relationships, indicating a significant increase in the diversification of arcidan lineages at the beginning of the Cretaceous, around 140Ma. The monophyly of Arcida, which has been supported previously, was confirmed in all our analyses. Although relationships among families remain somehow unresolved we found support for the monophyly of most arcidan families, at least under some analytical conditions (i.e., Glycymerididae, Noetiidae, Philobryidae, and Limopsidae). However, Arcidae, and particularly Arcinae, remain a major source of inconsistency in the current system of Arcida classification and are in dire need of taxonomic revision.

  14. Emerging and endemic types of Ostreid herpesvirus 1 were detected in bivalves in China.

    PubMed

    Bai, Changming; Wang, Chongming; Xia, Junyang; Sun, Hailin; Zhang, Shuai; Huang, Jie

    2015-01-01

    Viral infection caused by Ostreid herpesvirus 1 (OsHV-1) is one of the proximate causes of mass mortalities of cultivated bivalves around the world. The emergence and spread of different variants of OsHV-1 accompanied by different epidemiological characteristics have been reported frequently in different countries around the world. In this paper, we present a study of the detection of OsHV-1 DNA and their variations from 1599 samples over 18 species collected in 27 aquaculture sites and two food markets during 2001-2013 in China. All of the samples were examined by a nested PCR assay targeting the C2/C6 fragment of OsHV-1 followed by sequencing. Our results showed 338 individuals (21.1%) of seven species sampled from 14 (14/27=51.9%) sites and the two food markets were positive for viral DNA. Sequencing of 289 PCR products revealed 24 virus types. No shared virus type was found among different countries with 47 types (23 in Japan, 16 in France, 2 in South Korea and 1 in each country of Australia, USA, Ireland, New Zealand, Mexico and China) identified in previous studies. As previously reported, two main phylogenetic groups were identified by phylogenetic analysis based on the 71 virus types; within which 6 separate clades were identified. Our results also demonstrated that two clades were associated with abnormal mortalities of the scallop, Chlamys farrier and the calm, Scapharca broughtonii in China. These findings indicated that cultivated bivalves may face potential threats from OsHV-1 types found in our study. PMID:25483846

  15. Impact of sample pretreatment on the measured element concentrations in the bivalve Arctica islandica

    NASA Astrophysics Data System (ADS)

    Krause-Nehring, Jacqueline; Klügel, Andreas; Nehrke, Gernot; Brellochs, Bernd; Brey, Thomas

    2011-07-01

    Correlating metal to calcium (Me/Ca) ratios of marine biogenic carbonates, such as bivalve shells, to environmental parameters has led to contradictory results. Biogenic carbonates represent complex composites of organic and inorganic phases. Some elements are incorporated preferentially into organic phases, and others are incorporated into inorganic phases. Chemical sample pretreatment to remove the organic matrix prior to trace element analysis may increase the applicability of the investigated proxy relationship, though its efficiency and side effects remain questionable. We treated inorganic calcium carbonate and bivalve shell powder (Arctica islandica) with eight different chemical treatments including H2O2, NaOH, NaOCl, and acetone and analyzed the effects on (1) Me/Ca ratios (Sr/Ca, Mg/Ca, Ba/Ca, and Mn/Ca), (2) organic matter (≈N) content, and (3) mineralogical composition of the calcium carbonate. The different treatments (1) cause element and treatment specific changes of Me/Ca ratios, (2) vary in their efficiency to remove organic matter, and (3) can even alter the phase composition of the calcium carbonate (e.g., formation of Ca(OH)2 during NaOH treatment). Among all examined treatments there were none without any side effects. In addition, certain Me/Ca changes we observed upon chemical treatment contradict our expectations that lattice-bound elements (Sr and Ba) should not be affected, whereas non-lattice-bound elements (Mg and Mn) should decrease upon removal of the organic matrix. For instance, we observe that NaOCl treatment did not alter Sr/Ca ratios but caused unexpected changes of the Mg/Ca ratios. The latter demonstrates that the buildup of complex biogenic composites like the shell of Arctica islandica are still poorly understood.

  16. Emerging and endemic types of Ostreid herpesvirus 1 were detected in bivalves in China.

    PubMed

    Bai, Changming; Wang, Chongming; Xia, Junyang; Sun, Hailin; Zhang, Shuai; Huang, Jie

    2015-01-01

    Viral infection caused by Ostreid herpesvirus 1 (OsHV-1) is one of the proximate causes of mass mortalities of cultivated bivalves around the world. The emergence and spread of different variants of OsHV-1 accompanied by different epidemiological characteristics have been reported frequently in different countries around the world. In this paper, we present a study of the detection of OsHV-1 DNA and their variations from 1599 samples over 18 species collected in 27 aquaculture sites and two food markets during 2001-2013 in China. All of the samples were examined by a nested PCR assay targeting the C2/C6 fragment of OsHV-1 followed by sequencing. Our results showed 338 individuals (21.1%) of seven species sampled from 14 (14/27=51.9%) sites and the two food markets were positive for viral DNA. Sequencing of 289 PCR products revealed 24 virus types. No shared virus type was found among different countries with 47 types (23 in Japan, 16 in France, 2 in South Korea and 1 in each country of Australia, USA, Ireland, New Zealand, Mexico and China) identified in previous studies. As previously reported, two main phylogenetic groups were identified by phylogenetic analysis based on the 71 virus types; within which 6 separate clades were identified. Our results also demonstrated that two clades were associated with abnormal mortalities of the scallop, Chlamys farrier and the calm, Scapharca broughtonii in China. These findings indicated that cultivated bivalves may face potential threats from OsHV-1 types found in our study.

  17. Hepatitis A and E Viruses in Wastewaters, in River Waters, and in Bivalve Molluscs in Italy.

    PubMed

    Iaconelli, M; Purpari, G; Della Libera, S; Petricca, S; Guercio, A; Ciccaglione, A R; Bruni, R; Taffon, S; Equestre, M; Fratini, M; Muscillo, M; La Rosa, Giuseppina

    2015-12-01

    Several studies have reported the detection of hepatitis A (HAV) and E (HEV) virus in sewage waters, indicating a possibility of contamination of aquatic environments. The objective of the present study was to assess the occurrence of HAV and HEV in different water environments, following the route of contamination from raw sewage through treated effluent to the surface waters receiving wastewater discharges . Bivalve molluscan shellfish samples were also analyzed, as sentinel of marine pollution. Samples were tested by RT-PCR nested type in the VP1/2A junction for HAV, and in the ORF1 and ORF2 regions for HEV. Hepatitis A RNA was detected in 12 water samples: 7/21 (33.3%) raw sewage samples, 3/21 (14.3%) treated sewage samples, and 2/27 (7.4%) river water samples. Five sequences were classified as genotype IA, while the remaining 7 sequences belonged to genotype IB. In bivalves, HAV was detected in 13/56 samples (23.2%), 12 genotype IB and one genotype IA. Whether the presence of HAV in the matrices tested indicates the potential for waterborne and foodborne transmission is unknown, since infectivity of the virus was not demonstrated. HEV was detected in one raw sewage sample and in one river sample, both belonging to genotype 3. Sequences were similar to sequences detected previously in Italy in patients with autochthonous HEV (no travel history) and in animals (swine). To our knowledge, this is the first detection of HEV in river waters in Italy, suggesting that surface water can be a potential source for exposure .

  18. Herbivory and Body Size: Allometries of Diet Quality and Gastrointestinal Physiology, and Implications for Herbivore Ecology and Dinosaur Gigantism

    PubMed Central

    Clauss, Marcus; Steuer, Patrick; Müller, Dennis W. H.; Codron, Daryl; Hummel, Jürgen

    2013-01-01

    Digestive physiology has played a prominent role in explanations for terrestrial herbivore body size evolution and size-driven diversification and niche differentiation. This is based on the association of increasing body mass (BM) with diets of lower quality, and with putative mechanisms by which a higher BM could translate into a higher digestive efficiency. Such concepts, however, often do not match empirical data. Here, we review concepts and data on terrestrial herbivore BM, diet quality, digestive physiology and metabolism, and in doing so give examples for problems in using allometric analyses and extrapolations. A digestive advantage of larger BM is not corroborated by conceptual or empirical approaches. We suggest that explanatory models should shift from physiological to ecological scenarios based on the association of forage quality and biomass availability, and the association between BM and feeding selectivity. These associations mostly (but not exclusively) allow large herbivores to use low quality forage only, whereas they allow small herbivores the use of any forage they can physically manage. Examples of small herbivores able to subsist on lower quality diets are rare but exist. We speculate that this could be explained by evolutionary adaptations to the ecological opportunity of selective feeding in smaller animals, rather than by a physiologic or metabolic necessity linked to BM. For gigantic herbivores such as sauropod dinosaurs, other factors than digestive physiology appear more promising candidates to explain evolutionary drives towards extreme BM. PMID:24204552

  19. Herbivory and body size: allometries of diet quality and gastrointestinal physiology, and implications for herbivore ecology and dinosaur gigantism.

    PubMed

    Clauss, Marcus; Steuer, Patrick; Müller, Dennis W H; Codron, Daryl; Hummel, Jürgen

    2013-01-01

    Digestive physiology has played a prominent role in explanations for terrestrial herbivore body size evolution and size-driven diversification and niche differentiation. This is based on the association of increasing body mass (BM) with diets of lower quality, and with putative mechanisms by which a higher BM could translate into a higher digestive efficiency. Such concepts, however, often do not match empirical data. Here, we review concepts and data on terrestrial herbivore BM, diet quality, digestive physiology and metabolism, and in doing so give examples for problems in using allometric analyses and extrapolations. A digestive advantage of larger BM is not corroborated by conceptual or empirical approaches. We suggest that explanatory models should shift from physiological to ecological scenarios based on the association of forage quality and biomass availability, and the association between BM and feeding selectivity. These associations mostly (but not exclusively) allow large herbivores to use low quality forage only, whereas they allow small herbivores the use of any forage they can physically manage. Examples of small herbivores able to subsist on lower quality diets are rare but exist. We speculate that this could be explained by evolutionary adaptations to the ecological opportunity of selective feeding in smaller animals, rather than by a physiologic or metabolic necessity linked to BM. For gigantic herbivores such as sauropod dinosaurs, other factors than digestive physiology appear more promising candidates to explain evolutionary drives towards extreme BM. PMID:24204552

  20. Gigantic enhancement in the dielectric properties of polymer-based composites using core/shell MWCNT/amorphous carbon nanohybrids

    NASA Astrophysics Data System (ADS)

    Guo, Qikai; Xue, Qingzhong; Sun, Jin; Dong, Mingdong; Xia, Fujun; Zhang, Zhongyang

    2015-02-01

    Novel core/shell structured multi-walled carbon nanotube/amorphous carbon (MWCNT@AC) nanohybrids were successfully prepared using a simple and novel method. Subsequently, the MWCNT@AC nanohybrids were used as fillers to enhance the dielectric properties of poly(vinylidene fluoride) (PVDF) based composites. It is found that the dielectric constant of the MWCNT@AC/PVDF composites can reach 5910 (the dielectric loss is ~2), which is considerably better than that of MWCNT/PVDF composites. The uniform amorphous carbon shell provides an insulative layer between adjacent MWCNTs in the polymer matrix, which not only prevents the direct contact of MWCNTs but also improves the dispersibility of the MWCNTs. Therefore, a surprising number of microcapacitors could be formed in the composites before the formation of a conductive network, leading to a gigantic enhancement in the dielectric properties. Our strategy provides a new approach to fabricate excellent dielectric materials for energy storage capacitors. In addition, the design concept used in this work can be extended to other carbon materials.

  1. Expression of metallothionein-human growth hormone fusion genes in transgenic mice results in disproportionate skeletal gigantism.

    PubMed

    Wolf, E; Rapp, K; Brem, G

    1991-01-01

    Transgenic mice harbouring mouse metallothionein I-human growth hormone (MT-hGH) fusion genes were produced using the microinjection technique. The bones of adult MT-hGH transgenic mice, which continuously expressed high levels of hGH in their serum, and age-matched controls lacking detectable concentrations of hGH were measured microscopically. In addition to analyzing absolute skeletal dimensions, measurements were related to the cube root of the maximum body weight of the same animal. Absolute values obtained from transgenic mice were significantly higher than those obtained from controls for most of the defined measurements. However, the increase in skeletal dimensions was mostly not as pronounced as the increase in body weight and all bones were not affected to the same extent. There was no significant correlation between the serum GH concentration in individual mice and their degree of bony overgrowth. A disproportionate skeletal gigantism in MT-hGH transgenic mice may result from time differences in epiphyseal union of various bones of both sexes as well as differences in mechanical bone loading due to a drastically increased body weight. Individual concentrations of locally produced tissue insulin-like growth factor I (IGF I) might also play a role. Possible effects of these factors are discussed. The results presented in this study show that MT-hGH transgenic mice provide a powerful tool for the investigation of hormonal regulation of bone growth. PMID:1938045

  2. Gigantic enhancement in the dielectric properties of polymer-based composites using core/shell MWCNT/amorphous carbon nanohybrids.

    PubMed

    Guo, Qikai; Xue, Qingzhong; Sun, Jin; Dong, Mingdong; Xia, Fujun; Zhang, Zhongyang

    2015-02-28

    Novel core/shell structured multi-walled carbon nanotube/amorphous carbon (MWCNT@AC) nanohybrids were successfully prepared using a simple and novel method. Subsequently, the MWCNT@AC nanohybrids were used as fillers to enhance the dielectric properties of poly(vinylidene fluoride) (PVDF) based composites. It is found that the dielectric constant of the MWCNT@AC/PVDF composites can reach 5910 (the dielectric loss is ∼2), which is considerably better than that of MWCNT/PVDF composites. The uniform amorphous carbon shell provides an insulative layer between adjacent MWCNTs in the polymer matrix, which not only prevents the direct contact of MWCNTs but also improves the dispersibility of the MWCNTs. Therefore, a surprising number of microcapacitors could be formed in the composites before the formation of a conductive network, leading to a gigantic enhancement in the dielectric properties. Our strategy provides a new approach to fabricate excellent dielectric materials for energy storage capacitors. In addition, the design concept used in this work can be extended to other carbon materials.

  3. Herbivory and body size: allometries of diet quality and gastrointestinal physiology, and implications for herbivore ecology and dinosaur gigantism.

    PubMed

    Clauss, Marcus; Steuer, Patrick; Müller, Dennis W H; Codron, Daryl; Hummel, Jürgen

    2013-01-01

    Digestive physiology has played a prominent role in explanations for terrestrial herbivore body size evolution and size-driven diversification and niche differentiation. This is based on the association of increasing body mass (BM) with diets of lower quality, and with putative mechanisms by which a higher BM could translate into a higher digestive efficiency. Such concepts, however, often do not match empirical data. Here, we review concepts and data on terrestrial herbivore BM, diet quality, digestive physiology and metabolism, and in doing so give examples for problems in using allometric analyses and extrapolations. A digestive advantage of larger BM is not corroborated by conceptual or empirical approaches. We suggest that explanatory models should shift from physiological to ecological scenarios based on the association of forage quality and biomass availability, and the association between BM and feeding selectivity. These associations mostly (but not exclusively) allow large herbivores to use low quality forage only, whereas they allow small herbivores the use of any forage they can physically manage. Examples of small herbivores able to subsist on lower quality diets are rare but exist. We speculate that this could be explained by evolutionary adaptations to the ecological opportunity of selective feeding in smaller animals, rather than by a physiologic or metabolic necessity linked to BM. For gigantic herbivores such as sauropod dinosaurs, other factors than digestive physiology appear more promising candidates to explain evolutionary drives towards extreme BM.

  4. Dorsal resection of a thoracic hemivertebra in a 4-year-old boy with endochondral gigantism. A case report.

    PubMed

    Zarghooni, Kourosh; Sobotrke, Rolf; Schmidt, Heinrich; Rollinghoff, Marc; Siewe, Jan; Eysel, Peer

    2010-10-01

    The authors present what appears to be the first case of congenital kyphosis due to a T12 hemivertebra in a four-year-old boy with endochondral gigantism syndrome of unknown origin. Because of his overgrowth, the patient had severe medical and orthopaedic problems and was almost immobile. Prior to surgery, he experienced a rapidly progressive thoracolumbar kyphosis to 600 (T10-L2). MRI of the brain and spine showed critical protraction of the spinal cord and myelopathy from compression at T12. Single-stage posterior resection of the hemivertebra with spinal shortening and dorsal transpedicular instrumentation of T10-L2 was performed. Although the bone tissue was cartilaginous and dysplastic, 420 (30%) correction was achieved along with decompression of the spinal canal. The patient experienced no neurological impairment post-operatively. At follow-up examination 1.5 year after surgery, the patient's movement disorder had improved markedly and he was able to stand and walk. This very rare case demonstrates that single-stage posterior hemivertebra resection and transpedicular instrumentation for correction of congenital kyphosis can be a safe and effective procedure even in a very challenging case.

  5. Predation as the primary selective force in recurrent evolution of gigantism in Poecilozonites land snails in Quaternary Bermuda.

    PubMed

    Olson, Storrs L; Hearty, Paul J

    2010-12-23

    During the last half million years, pulses of gigantism in the anagenetic lineage of land snails of the subgenus Poecilozonites on Bermuda were correlated with glacial periods when lower sea level resulted in an island nearly an order of magnitude larger than at present. During those periods, the island was colonized by large vertebrate predators that created selection pressure for large size and rapid growth in the snails. Extreme reduction in land area from rising seas, along with changes in ecological conditions at the onset of interglacial episodes, marked extinction events for large predators, after which snails reverted to much smaller size. The giant snails were identical in morphology during the last two glacials when the predators included a large flightless rail Rallus recessus (marine isotope stages (MIS) 4-2) and a crane Grus latipes and a duck Anas pachysceles (MIS 6). In a preceding glacial period (MIS 10), when the fauna also included the tortoise Hesperotestudo bermudae, the snails were not only large, but the shells were much thicker, presumably to prevent crushing by tortoises. Evolution of Poecilozonites provides an outstanding example of dramatic morphological change in response to environmental pressures in the absence of cladogenesis. PMID:20554560

  6. Oxygen Isotopes in Bivalve Shells record Hydrological Changes in the Siberian Land-Shelf Connection on Annual Timescales

    NASA Astrophysics Data System (ADS)

    Mueller-Lupp, T.; Bauch, H. A.; Erlenkeuser, H.

    2003-04-01

    It is now widely accepted that changes in surface ocean hydrology at northern high latitudes is a major forcing mechanism that can strongly perturbate a particular climate mode. Given the variability on subdecadal and on centennial to millennial timescales, the dispersal and fate of arctic riverine water discharge and its role on the ice regime as well as on surface water properties are central issues in the understanding of Holocene climate change in the arctic marginal seas, the Arctic Ocean, and beyond. Oxygen isotope profiles from living and fossil bivalves were investigated in order to trace modern and past hydrographical changes in the strongly coupled land-shelf system of the Laptev Sea. Detailed oxygen isotope measurements were executed on the shells along their axis of maximum growth and provide an isotopic record of hydrological and environmental changes for the lifespan of the individual bivalves. The oxygen isotopic records exhibit amplitude cycles interpreted as recording annual cycles. Based on the well-known relationship between the oxygen isotope ratio in the bivalves carbonate, the temperature and the isotopic composition of water, it is possible to relate phases of more negative (lighter) oxygen isotope values indicating summer and more positive (heavier) oxygen isotope values indicating the winter season. The main forcing factor of the oxygen isotope variations is the variability of the isotopic composition of the bottom water. Measurements of the oxygen isotope ratio in surface and bottom waters of the Laptev Sea show a linear relation of salinity and oxygen isotope ratio of the water with a coefficient of 0.50 per mill per salinity unit and document the mixing of freshwater and seawater. The oxygen isotope cycles from growing profiles of the living bivalves indicate a correspondence to seasonal hydrographic changes and can be compared with runoff data and circulation patterns in the Laptev Sea. Given the seasonal cycles in living bivalves

  7. Influence of food on the assimilation of selected metals in tropical bivalves from the New Caledonia lagoon: qualitative and quantitative aspects.

    PubMed

    Hédouin, Laetitia; Metian, Marc; Lacoue-Labarthe, Thomas; Fichez, Renaud; Teyssié, Jean-Louis; Bustamante, Paco; Warnau, Michel

    2010-01-01

    The present study aimed at examining the influence of food quality and quantity on the assimilation efficiency (AE) of metals in two abundant bivalves in the New Caledonia lagoon, the oyster Isognomon isognomon and the clam Gafrarium tumidum. Bivalves were exposed via their food to the radiotracers of three metals of concern in New Caledonia ((54)Mn, (57)Co and (65)Zn) under different feeding conditions (phytoplankton species, cell density, and cell-associated metal concentration). When bivalves were fed Heterocapsa triquetra, Emiliania huxleyi and Isochrysis galbana, AE of Mn, Co and Zn was strongly influenced by the phytoplankton species and by the metal considered. In contrast, when fed one given phytoplankton species previously exposed to different concentrations of Co, phytoplankton-associated Co load had no influence on the AE and on the retention time of the metal in both bivalves. Metals ingested with I. galbana displayed generally the highest AE in both bivalve species, except for Mn in clams for which the highest AE was observed for H. triquetra. Influence of food quantity was investigated by exposing bivalves to different cell densities of I. galbana (5 x 10(3), 10(4) or 5 x 10(4) cell ml(-1)). As for food quality, food quantity was found to influence AE of Mn, Co and Zn, the highest AE being observed when bivalves were fed the lowest cell density. Overall, results indicate that the two bivalve species are able to adjust their feeding strategies according to the food conditions prevailing in their environment.

  8. Bivalve vulnerability is enhanced by parasites through the deficit of metallothionein synthesis: A field monitoring on cockles (Cerastoderma edule)

    NASA Astrophysics Data System (ADS)

    Baudrimont, M.; de Montaudouin, X.; Palvadeau, A.

    2003-05-01

    The effect of the parasite Labratrema minimus (digenean trematode) on metallothioneins (MTs) biosynthesis by the cockle Cerastoderma edule (bivalve) was investigated. An in situ monitoring allowed to describe and compare monthly variations of MTs concentrations in cockles with and without L. minimus in a site free of metai pollution (Banc d'Arguin, Arcachon Bay, France). These concentrations are correlated with the reproductive cycle of the bivalve: (I) in spent cockles, MTs concentrations are higher in infected cockles. probably due to host tissue lysis: (2) during maturation, MTs biosynthesis increases in all cockles. However, concentrations are lower in parasitized individuals in relation with castration by parasites. Therefore, parasite infection in cockles, which can affect 100% of individuals, may contribute to a higher vulnerability of organisms to metal contamination.

  9. The mismatch between bioaccumulation in field and laboratory environments: Interpreting the differences for metals in benthic bivalves.

    PubMed

    Belzunce-Segarra, Maria J; Simpson, Stuart L; Amato, Elvio D; Spadaro, David A; Hamilton, Ian L; Jarolimek, Chad V; Jolley, Dianne F

    2015-09-01

    Laboratory-based bioaccumulation and toxicity bioassays are frequently used to predict the ecological risk of contaminated sediments in the field. This study investigates the bioassay conditions most relevant to achieving environmentally relevant field exposures. An identical series of metal-contaminated marine sediments were deployed in the field and laboratory over 31 days. Changes in metal concentrations and partitioning in both sediments and waters were used to interpret differences in metal exposure and bioaccumulation to the benthic bivalve Tellina deltoidalis. Loss of resuspended sediments and deposition of suspended particulate matter from the overlying water resulted in the concentrations of Cu, Pb and Zn (major contaminants) becoming lower in the 1-cm surface layer of field-deployed sediments. Lower exchange rates of overlying waters in the laboratory resulted in higher dissolved metal exposures. The prediction of metal bioaccumulation by the bivalves in field and laboratory was improved by considering the metal partitioning within the surface sediments.

  10. A diagnostic molecular marker for zebra mussels (Dreissena polymorpha) and potentially co-occurring bivalves: mitochondrial COI.

    PubMed

    Baldwin, B S; Black, M; Sanjur, O; Gustafson, R; Lutz, R A; Vrijenhoek, R C

    1996-03-01

    We report diagnostic differences in the nucleotide sequences of a 710-bp fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) from the zebra mussel (Dreissena polymorpha) and potentially co-occurring bivalves: the quagga mussel (Dreissena bugensis); the Asiatic clam (Corbicula fluminea), the dark false mussel (Mytilopsis leucophaeata), and the wedge clam (Rangia cuneata). The COI sequence of the deep-water "profunda" phenotype of the quagga mussel was nearly identical to that of shallow-water quagga mussels. Restriction fragment length polymorphisms (RFLPs) in this portion of COI produced species-specific differences in fragment numbers and sizes that could be used as diagnostic markers to distinguish the free-living larvae produced by these bivalves.

  11. Genetic analysis of durable resistance to Magnaporthe oryzae in the rice accession Gigante Vercelli identified two blast resistance loci.

    PubMed

    Urso, Simona; Desiderio, Francesca; Biselli, Chiara; Bagnaresi, Paolo; Crispino, Laura; Piffanelli, Pietro; Abbruscato, Pamela; Assenza, Federica; Guarnieri, Giada; Cattivelli, Luigi; Valè, Giampiero

    2016-02-01

    Rice cultivars exhibiting durable resistance to blast, the most important rice fungal disease provoking up to 30 % of rice losses, are very rare and searching for sources of such a resistance represents a priority for rice-breeding programs. To this aim we analyzed Gigante Vercelli (GV) and Vialone Nano (VN), two temperate japonica rice cultivars in Italy displaying contrasting response to blast, with GV showing a durable and broad-spectrum resistance, whereas VN being highly susceptible. An SSR-based genetic map developed using a GV × VN population segregating for blast resistance identified two blast resistance loci, localized to the long arm of chromosomes 1 and 4 explaining more than 78 % of the observed phenotypic variation for blast resistance. The pyramiding of two blast resistance QTLs was therefore involved in the observed durable resistance in GV. Mapping data were integrated with information obtained from RNA-seq expression profiling of all classes of resistance protein genes (resistance gene analogs, RGAs) and with the map position of known cloned or mapped blast resistance genes to search candidates for the GV resistant response. A co-localization of RGAs with the LOD peak or the marker interval of the chromosome 1 QTL was highlighted and a valuable tool for selecting the resistance gene during breeding programs was developed. Comparative analysis with known blast resistance genes revealed co-positional relationships between the chromosome 1 QTL with the Pi35/Pish blast resistance alleles and showed that the chromosome 4 QTL represents a newly identified blast resistance gene. The present genetic analysis has therefore allowed the identification of two blast resistance loci in the durable blast-resistant rice cultivar GV and tools for molecular selection of these resistance genes.

  12. Stable isotopes in bivalves as indicators of nutrient source in coastal waters in the Bocas del Toro Archipelago, Panama.

    PubMed

    Graniero, Lauren E; Grossman, Ethan L; O'Dea, Aaron

    2016-01-01

    To examine N-isotope ratios ((15)N/(14)N) in tissues and shell organic matrix of bivalves as a proxy for natural and anthropogenic nutrient fluxes in coastal environments, Pinctada imbricata, Isognomon alatus, and Brachidontes exustusbivalves were live-collected and analyzed from eight sites in Bocas del Toro, Panama. Sites represent a variety of coastal environments, including more urbanized, uninhabited, riverine, and oceanic sites. Growth under differing environmental conditions is confirmed by δ (18)O values, with open ocean Escudo de Veraguas shells yielding the highest average δ (18)O (-1.0‰) value and freshwater endmember Rio Guarumo the lowest (-1.7‰). At all sites there is no single dominant source of organic matter contributing to bivalve δ (15)N and δ (13)C values. Bivalve δ (15)N and δ (13)C values likely represent a mixture of mangrove and seagrass N and C, although terrestrial sources cannot be ruled out. Despite hydrographic differences between end-members, we see minimal δ (15)N and δ (13)C difference between bivalves from the river-influenced Rio Guarumo site and those from the oceanic Escudo de Veraguas site, with no evidence for N from open-ocean phytoplankton in the latter. Populated sites yield relative (15)N enrichments suggestive of anthropogenic nutrient input, but low δ (15)N values overall make this interpretation equivocal. Lastly, δ (15)N values of tissue and shell organic matrix correlate significantly for pterioideans P. imbricata and I. alatus. Thus for these species, N isotope studies of historical and fossil shells should provide records of ecology of past environments. PMID:27547578

  13. Suspended material availability and filtration-biodeposition processes performed by a native and invasive bivalve species in streams

    USGS Publications Warehouse

    Atkinson, C.L.; First, M.R.; Covich, A.P.; Opsahl, S.P.; Golladay, S.W.

    2011-01-01

    Unionid mussels are among the most threatened group of freshwater organisms globally. They are known for their ability to filter food particles from flowing and standing waters. However, invasive bivalve species, such as the Asian clam (Corbicula fluminea) in North America, have the potential to overlap in feeding and potentially out-compete the native species. Yet, the feeding preferences of unionid mussels and C. fluminea are incompletely understood. We hypothesized that Elliptio crassidens (native) and C. fluminea (invasive) would select for specific organic components present within seston. We examined changes in seston (dry mass and ash-free dry mass) resulting from bivalve feeding activity for three size classes of material that were isolated using gravimetric filtration. The treatments were also sub-sampled for flow cytometry (FC) which separated the suspended materials in the stream water into five categories: detritus, heterotrophic bacteria, picoautotrophs, nanoautotrophs, and heterotrophic nanoeukaryotes. Our results indicated that both species of bivalve showed preferences for organic and living materials. E. crassidens preferentially filtered nanoeukaryotes, whose decreases were associated with an increase in bacteria. In contrast, C. fluminea preferred smaller materials through selective filtration of picoautotrophs. In addition, both species increased the concentration of large materials toward the end of the experiment because of the suspension of their pseudofeces biodeposits. To our knowledge, this study is the first to examine grazing by bivalve species on natural stream particulate matter using FC. Our results suggest that native and non-native mussels have different functional roles, which has important implications for organic matter processing and food webs in streams. ?? 2011 Springer Science+Business Media B.V.

  14. The effects of the adult density of Macoma balthica on the recruitment of juvenile bivalves: a field experiment

    NASA Astrophysics Data System (ADS)

    Richards, M.; Edwards, F.; Huxham, M.

    2002-02-01

    Populations of intertidal bivalves are patchily distributed at a variety of scales, and the distributions of adults and juveniles are often different. Adult-juvenile interactions may help explain this patchiness. In this study, the effects of different densities of adult Macoma balthica (L.) on the numbers of re-locating juvenile M. balthica and Cerastoderma edule (L.) were examined. Two field experiments were conducted, which established three densities of adult M. balthica (reflecting the range of values found on the study site) and allowed recruitment of bivalves into experimental plots for two tidal cycles. Both experiments were run at peak summer arrival of juveniles at this site. The first was open to predators, the second was protected from larger epibenthic and avian predators by cages. The mean number of juvenile C. edule found in the high-density treatment was significantly lower than in the other density treatments in the first (open) experiment. There was also evidence of density-dependent predation by Carcinus maenas (L.). There were no significant effects of adult M. balthica density on the numbers of juvenile bivalves in the caged experiment. These results were compared with those from a small-scale field survey, which showed a negative correlation between juvenile M. balthica ≤1.6 mm and individuals ≥1.6 mm. Our study suggests that densities of M. balthica ≥1.6 mm may have an impact on the numbers of juvenile bivalves (in particular, C. edule) re-locating at this site, but that this effect is not the result of direct adult-juvenile interactions, but is caused indirectly by density-dependent predation by C. maenas.

  15. Stable isotopes in bivalves as indicators of nutrient source in coastal waters in the Bocas del Toro Archipelago, Panama.

    PubMed

    Graniero, Lauren E; Grossman, Ethan L; O'Dea, Aaron

    2016-01-01

    To examine N-isotope ratios ((15)N/(14)N) in tissues and shell organic matrix of bivalves as a proxy for natural and anthropogenic nutrient fluxes in coastal environments, Pinctada imbricata, Isognomon alatus, and Brachidontes exustusbivalves were live-collected and analyzed from eight sites in Bocas del Toro, Panama. Sites represent a variety of coastal environments, including more urbanized, uninhabited, riverine, and oceanic sites. Growth under differing environmental conditions is confirmed by δ (18)O values, with open ocean Escudo de Veraguas shells yielding the highest average δ (18)O (-1.0‰) value and freshwater endmember Rio Guarumo the lowest (-1.7‰). At all sites there is no single dominant source of organic matter contributing to bivalve δ (15)N and δ (13)C values. Bivalve δ (15)N and δ (13)C values likely represent a mixture of mangrove and seagrass N and C, although terrestrial sources cannot be ruled out. Despite hydrographic differences between end-members, we see minimal δ (15)N and δ (13)C difference between bivalves from the river-influenced Rio Guarumo site and those from the oceanic Escudo de Veraguas site, with no evidence for N from open-ocean phytoplankton in the latter. Populated sites yield relative (15)N enrichments suggestive of anthropogenic nutrient input, but low δ (15)N values overall make this interpretation equivocal. Lastly, δ (15)N values of tissue and shell organic matrix correlate significantly for pterioideans P. imbricata and I. alatus. Thus for these species, N isotope studies of historical and fossil shells should provide records of ecology of past environments.

  16. Stable isotopes in bivalves as indicators of nutrient source in coastal waters in the Bocas del Toro Archipelago, Panama

    PubMed Central

    Grossman, Ethan L.; O’Dea, Aaron

    2016-01-01

    To examine N-isotope ratios (15N/14N) in tissues and shell organic matrix of bivalves as a proxy for natural and anthropogenic nutrient fluxes in coastal environments, Pinctada imbricata, Isognomon alatus, and Brachidontes exustusbivalves were live-collected and analyzed from eight sites in Bocas del Toro, Panama. Sites represent a variety of coastal environments, including more urbanized, uninhabited, riverine, and oceanic sites. Growth under differing environmental conditions is confirmed by δ18O values, with open ocean Escudo de Veraguas shells yielding the highest average δ18O (−1.0‰) value and freshwater endmember Rio Guarumo the lowest (−1.7‰). At all sites there is no single dominant source of organic matter contributing to bivalve δ15N and δ13C values. Bivalve δ15N and δ13C values likely represent a mixture of mangrove and seagrass N and C, although terrestrial sources cannot be ruled out. Despite hydrographic differences between end-members, we see minimal δ15N and δ13C difference between bivalves from the river-influenced Rio Guarumo site and those from the oceanic Escudo de Veraguas site, with no evidence for N from open-ocean phytoplankton in the latter. Populated sites yield relative 15N enrichments suggestive of anthropogenic nutrient input, but low δ15N values overall make this interpretation equivocal. Lastly, δ15N values of tissue and shell organic matrix correlate significantly for pterioideans P. imbricata and I. alatus. Thus for these species, N isotope studies of historical and fossil shells should provide records of ecology of past environments. PMID:27547578

  17. What Lies Beneath: Sub-Articular Long Bone Shape Scaling in Eutherian Mammals and Saurischian Dinosaurs Suggests Different Locomotor Adaptations for Gigantism

    PubMed Central

    Bonnan, Matthew F.; Wilhite, D. Ray; Masters, Simon L.; Yates, Adam M.; Gardner, Christine K.; Aguiar, Adam

    2013-01-01

    Eutherian mammals and saurischian dinosaurs both evolved lineages of huge terrestrial herbivores. Although significantly more saurischian dinosaurs were giants than eutherians, the long bones of both taxa scale similarly and suggest that locomotion was dynamically similar. However, articular cartilage is thin in eutherian mammals but thick in saurischian dinosaurs, differences that could have contributed to, or limited, how frequently gigantism evolved. Therefore, we tested the hypothesis that sub-articular bone, which supports the articular cartilage, changes shape in different ways between terrestrial mammals and dinosaurs with increasing size. Our sample consisted of giant mammal and reptile taxa (i.e., elephants, rhinos, sauropods) plus erect and non-erect outgroups with thin and thick articular cartilage. Our results show that eutherian mammal sub-articular shape becomes narrow with well-defined surface features as size increases. In contrast, this region in saurischian dinosaurs expands and remains gently convex with increasing size. Similar trends were observed in non-erect outgroup taxa (monotremes, alligators), showing that the trends we report are posture-independent. These differences support our hypothesis that sub-articular shape scales differently between eutherian mammals and saurischian dinosaurs. Our results show that articular cartilage thickness and sub-articular shape are correlated. In mammals, joints become ever more congruent and thinner with increasing size, whereas archosaur joints remained both congruent and thick, especially in sauropods. We suggest that gigantism occurs less frequently in mammals, in part, because joints composed of thin articular cartilage can only become so congruent before stress cannot be effectively alleviated. In contrast, frequent gigantism in saurischian dinosaurs may be explained, in part, by joints with thick articular cartilage that can deform across large areas with increasing load. PMID:24130690

  18. What lies beneath: sub-articular long bone shape scaling in eutherian mammals and saurischian dinosaurs suggests different locomotor adaptations for gigantism.

    PubMed

    Bonnan, Matthew F; Wilhite, D Ray; Masters, Simon L; Yates, Adam M; Gardner, Christine K; Aguiar, Adam

    2013-01-01

    Eutherian mammals and saurischian dinosaurs both evolved lineages of huge terrestrial herbivores. Although significantly more saurischian dinosaurs were giants than eutherians, the long bones of both taxa scale similarly and suggest that locomotion was dynamically similar. However, articular cartilage is thin in eutherian mammals but thick in saurischian dinosaurs, differences that could have contributed to, or limited, how frequently gigantism evolved. Therefore, we tested the hypothesis that sub-articular bone, which supports the articular cartilage, changes shape in different ways between terrestrial mammals and dinosaurs with increasing size. Our sample consisted of giant mammal and reptile taxa (i.e., elephants, rhinos, sauropods) plus erect and non-erect outgroups with thin and thick articular cartilage. Our results show that eutherian mammal sub-articular shape becomes narrow with well-defined surface features as size increases. In contrast, this region in saurischian dinosaurs expands and remains gently convex with increasing size. Similar trends were observed in non-erect outgroup taxa (monotremes, alligators), showing that the trends we report are posture-independent. These differences support our hypothesis that sub-articular shape scales differently between eutherian mammals and saurischian dinosaurs. Our results show that articular cartilage thickness and sub-articular shape are correlated. In mammals, joints become ever more congruent and thinner with increasing size, whereas archosaur joints remained both congruent and thick, especially in sauropods. We suggest that gigantism occurs less frequently in mammals, in part, because joints composed of thin articular cartilage can only become so congruent before stress cannot be effectively alleviated. In contrast, frequent gigantism in saurischian dinosaurs may be explained, in part, by joints with thick articular cartilage that can deform across large areas with increasing load.

  19. What lies beneath: sub-articular long bone shape scaling in eutherian mammals and saurischian dinosaurs suggests different locomotor adaptations for gigantism.

    PubMed

    Bonnan, Matthew F; Wilhite, D Ray; Masters, Simon L; Yates, Adam M; Gardner, Christine K; Aguiar, Adam

    2013-01-01

    Eutherian mammals and saurischian dinosaurs both evolved lineages of huge terrestrial herbivores. Although significantly more saurischian dinosaurs were giants than eutherians, the long bones of both taxa scale similarly and suggest that locomotion was dynamically similar. However, articular cartilage is thin in eutherian mammals but thick in saurischian dinosaurs, differences that could have contributed to, or limited, how frequently gigantism evolved. Therefore, we tested the hypothesis that sub-articular bone, which supports the articular cartilage, changes shape in different ways between terrestrial mammals and dinosaurs with increasing size. Our sample consisted of giant mammal and reptile taxa (i.e., elephants, rhinos, sauropods) plus erect and non-erect outgroups with thin and thick articular cartilage. Our results show that eutherian mammal sub-articular shape becomes narrow with well-defined surface features as size increases. In contrast, this region in saurischian dinosaurs expands and remains gently convex with increasing size. Similar trends were observed in non-erect outgroup taxa (monotremes, alligators), showing that the trends we report are posture-independent. These differences support our hypothesis that sub-articular shape scales differently between eutherian mammals and saurischian dinosaurs. Our results show that articular cartilage thickness and sub-articular shape are correlated. In mammals, joints become ever more congruent and thinner with increasing size, whereas archosaur joints remained both congruent and thick, especially in sauropods. We suggest that gigantism occurs less frequently in mammals, in part, because joints composed of thin articular cartilage can only become so congruent before stress cannot be effectively alleviated. In contrast, frequent gigantism in saurischian dinosaurs may be explained, in part, by joints with thick articular cartilage that can deform across large areas with increasing load. PMID:24130690

  20. Field chronobiology of a molluscan bivalve: how the moon and sun cycles interact to drive oyster activity rhythms.

    PubMed

    Tran, Damien; Nadau, Arnaud; Durrieu, Gilles; Ciret, Pierre; Parisot, Jean-Paul; Massabuau, Jean-Charles

    2011-05-01

    The present study reports new insights into the complexity of environmental drivers in aquatic animals. The focus of this study was to determine the main forces that drive mollusc bivalve behavior in situ. To answer this question, the authors continuously studied the valve movements of permanently immersed oysters, Crassostrea gigas, during a 1-year-long in situ study. Valve behavior was monitored with a specially build valvometer, which allows continuously recording of up to 16 bivalves at high frequency (10 Hz). The results highlight a strong relationship between the rhythms of valve behavior and the complex association of the sun-earth-moon orbital positions. Permanently immersed C. gigas follows a robust and strong behavior primarily driven by the tidal cycle. The intensity of this tidal driving force is modulated by the neap-spring tides (i.e., synodic moon cycle), which themselves depend of the earth-moon distance (i.e., anomalistic moon cycle). Light is a significant driver of the oysters' biological rhythm, although its power is limited by the tides, which remain the predominant driver. More globally, depending where in the world the bivalves reside, the results suggest their biological rhythms should vary according to the relative importance of the solar cycle and different lunar cycles associated with tide generation. These results highlight the high plasticity of these oysters to adapt to their changing environment.

  1. Polycyclic Aromatic Hydrocarbons in Sediments and Bivalves on the Pacific Coast of Japan: Influence of Tsunami and Fire

    PubMed Central

    Onozato, Mayu; Nishigaki, Atsuko; Okoshi, Kenji

    2016-01-01

    Surface sediments and at least one edible bivalve species (Ruditapes philippinarum, Mytilus galloprovincialis, and Crassostrea gigas) were collected from each of seven intertidal sites in Japan in 2013. The sites had experienced varying levels of tsunami and fire disturbance following the major earthquake of 2011. Eight polycyclic aromatic hydrocarbons (PAHs) were identified and analyzed by gas chromatography–mass spectrometry. Total sediment PAH concentration (CT), the sum of the average concentrations of the eight PAHs, was 21–1447 μg kg-1-dry. Relative to the average level of one type of PAH in sediments collected around Japan in 2002 (benzo[a]pyrene = 21 μg kg-1-dry), five of the seven sites showed concentrations significantly lower than this average in 2013. The CTs for the three bivalves (134–450 μg kg-1-dry) were within the range of the previous reports (2.2–5335 μg kg-1-dry). The data suggest that the natural disaster did not increase PAH concentrations or affect the distribution within sediment or bivalves in Tohoku district. Although PAH concentrations at the sites pose no risk to human health, the findings highlight that the observed PAH levels derive from pre- rather than post-quake processes. PMID:27232189

  2. Temporal fluctuations of silver, copper and zinc in the bivalve Macoma balthica at five stations in South San Francisco Bay

    USGS Publications Warehouse

    Luoma, S.N.; Cain, D.; Johansson, C.

    1985-01-01

    Concentrations of Cu, Ag and Zn were measured in the soft tissues of the estuarine bivalve Macoma balthica in South San Francisco Bay at near-monthly intervals for periods of two to three years at four stations, and eight years at a metal-enriched station. The amplitude and frequency of fluctuations differed among stations and among metals. Fluctuations were greatest at stations with the greatest metal enrichment and with the least dilution and flushing of wastes. A consistent seasonal pattern of fluctuation in Cu and Ag concentrations was evident in M. balthica at the metal-enriched station. These seasonal changes in tissue metal concentrations appeared to be affected by metal inputs, hydrologic processes that may affect both metal concentrations and bioavailability, and seasonal changes in the weight of the bivalve. The contributions of each of these interacting factors could not be determined quantitatively. At the metal-enriched station significant variation in the amplitude of seasonal fluctuations was also evident from year to year. Interpretation of metal concentrations in bivalves from estuaries will require careful consideration of the processes which affect metal dynamics in these complex environments. ?? 1985 Dr W. Junk Publishers.

  3. A comparative study on effects of heterotrophic microbial activity on the stability of bivalve and coral carbonate during early diagenesis.

    NASA Astrophysics Data System (ADS)

    Lange, Skadi M.; Krause, Stefan; Immenhauser, Adrian; Ritter, Ann-Christin; Gorb, Stanislav N.; Kleinteich, Thomas; Treude, Tina

    2016-04-01

    Following deposition and shallow burial, marine biogenic carbonates are exposed to an environment that is geochemically affected by a manifold of bacterial metabolic redox processes. To allow for comparison of potential microbe-mediated alteration effects on carbonates, we used aragonitic bivalve shell samples and porous aragonitic coral fragments for incubation experiments in oxic- and anoxic seawater media. The media contained marine sediment slurries or bacterial cultures to mimic the natural processes in vitro. The results for anoxic experimental media containing bivalve shell samples or coral fragments displayed considerable changes in carbonate-system parameters (pH, AT, CA, DIC) and divalent-cation ratios (Mg/Ca, Mg/Sr, Sr/Ca) over time. Furthermore, incubated bivalve shell samples were altered in morphology, elemental composition and isotopic signature. Coral-fragment bearing oxic incubations were run at two temperature regimes and divalent-cation ratios of the high-temperature bacterial medium displayed withdrawal of Ca2+ and Sr2+ from the medium, thus indicating microbe-induced secondary aragonite precipitation. Analyses of coral fragments include electron-microprobe mapping and X-ray microtomography to resolve elemental sample composition and pore-space alteration features, respectively. Up to this point our results indicate that heterotrophic bacterial activity has the potential to affect surficial or open pore space in carbonate archives by increasing rates of alteration relative to sterile environments.

  4. [Community structure of bivalves and gastropods in roots of red mangrove Rhizophora mangle (Rhizophoraceae) in isla Larga, Mochima Bay, Venezuela].

    PubMed

    Acosta Balbas, Vanessa; Betancourt Tineo, Rafael; Prieto Arcas, Antulio

    2014-06-01

    The Rhizophora mangle roots form a complex ecosystem where a wide range of organisms are permanently established, reproduce, and find refuge. In this study, we assessed the diversity of bivalves and gastropods that inhabit red mangrove roots, in isla Larga, Mochima, Venezuela Sucre state. Bimonthly collections were made from January 2007 to May 2008, in four study areas denominated: South, North, East and West. In each area, five mangrove roots were sampled, and the specimens were obtained. We analyzed a total of 180 roots and a total of 35 bivalve species and 25 gastropod species were found. The most abundant bivalves were: Isognomon alatus, Isognomon bicolor, Ostrea equestris, Crassostrea rhizophorae and Brachidontes exustus; among gastropods, the most common where: Littorina angulifera, (Cymatium pileare and Diodora cayenensis. The months with the highest abundances and number of individuals for both groups were January and July 2007, and March 2008. The mangrove ecosystem in isla Larga, presented a number of individuals and species higher than those reported for other regions in Venezuela and the Caribbean.

  5. Polycyclic Aromatic Hydrocarbons in Sediments and Bivalves on the Pacific Coast of Japan: Influence of Tsunami and Fire.

    PubMed

    Onozato, Mayu; Nishigaki, Atsuko; Okoshi, Kenji

    2016-01-01

    Surface sediments and at least one edible bivalve species (Ruditapes philippinarum, Mytilus galloprovincialis, and Crassostrea gigas) were collected from each of seven intertidal sites in Japan in 2013. The sites had experienced varying levels of tsunami and fire disturbance following the major earthquake of 2011. Eight polycyclic aromatic hydrocarbons (PAHs) were identified and analyzed by gas chromatography-mass spectrometry. Total sediment PAH concentration (CT), the sum of the average concentrations of the eight PAHs, was 21-1447 μg kg-1-dry. Relative to the average level of one type of PAH in sediments collected around Japan in 2002 (benzo[a]pyrene = 21 μg kg-1-dry), five of the seven sites showed concentrations significantly lower than this average in 2013. The CTs for the three bivalves (134-450 μg kg-1-dry) were within the range of the previous reports (2.2-5335 μg kg-1-dry). The data suggest that the natural disaster did not increase PAH concentrations or affect the distribution within sediment or bivalves in Tohoku district. Although PAH concentrations at the sites pose no risk to human health, the findings highlight that the observed PAH levels derive from pre- rather than post-quake processes. PMID:27232189

  6. A Holistic Approach to the Conservation and Propagation of Freshwater, Brackish and Estuarine Bivalves for Ecosystem Services.

    NASA Astrophysics Data System (ADS)

    Kreeger, D.

    2005-05-01

    Shellfish restoration is increasingly valued in estuaries such as Chesapeake Bay where oyster populations are known to function as living biofilters, performing critical ecosystem services. Less studied are the services rendered by other suspension-feeding bivalves that reside in fringing marshes around these estuaries, in brackish and freshwater tidal portions, and in freshwater tributaries. The potential benefits contributed by other native bivalves will be discussed with two case studies from the Delaware basin. These are the ribbed mussel (Geukensia demissa ), which is abundant in brackish and marine tidal marshes, and the unionid mussel (Elliptio complanata ), which is abundant in many rivers of the system. Ribbed mussels are abundant enough to filter a large portion of the tidal prism flushing marshes, facilitating the role that these systems play as a sink for suspended solids and nutrients. Similarly, data from the lower Brandywine River suggests that a vestigial community of freshwater unionids remains sufficiently abundant to have a measurable beneficial effect on water quality by removing more than 25 metric tons of suspended particulates per year. Hence, the conservation and propagation of freshwater unionids can yield benefits that extend beyond current interest that is focused on protecting their biodiversity. Future efforts to protect or reclaim water quality and ecosystem integrity may benefit by a basin-wide, holistic approach that promotes integrated "biofiltration services" by native bivalves living from the headwaters to the coastal shelf.

  7. Field chronobiology of a molluscan bivalve: how the moon and sun cycles interact to drive oyster activity rhythms.

    PubMed

    Tran, Damien; Nadau, Arnaud; Durrieu, Gilles; Ciret, Pierre; Parisot, Jean-Paul; Massabuau, Jean-Charles

    2011-05-01

    The present study reports new insights into the complexity of environmental drivers in aquatic animals. The focus of this study was to determine the main forces that drive mollusc bivalve behavior in situ. To answer this question, the authors continuously studied the valve movements of permanently immersed oysters, Crassostrea gigas, during a 1-year-long in situ study. Valve behavior was monitored with a specially build valvometer, which allows continuously recording of up to 16 bivalves at high frequency (10 Hz). The results highlight a strong relationship between the rhythms of valve behavior and the complex association of the sun-earth-moon orbital positions. Permanently immersed C. gigas follows a robust and strong behavior primarily driven by the tidal cycle. The intensity of this tidal driving force is modulated by the neap-spring tides (i.e., synodic moon cycle), which themselves depend of the earth-moon distance (i.e., anomalistic moon cycle). Light is a significant driver of the oysters' biological rhythm, although its power is limited by the tides, which remain the predominant driver. More globally, depending where in the world the bivalves reside, the results suggest their biological rhythms should vary according to the relative importance of the solar cycle and different lunar cycles associated with tide generation. These results highlight the high plasticity of these oysters to adapt to their changing environment. PMID:21539422

  8. Polychlorinated dibenzo-p-dioxins and dibenzofurans detected in bivalve samples from the NOAA National Status and Trends Program.

    PubMed

    Wade, Terry L; Sweet, Stephen T; Sericano, José L; Defreitas, Debra A; Lauenstein, Gunnar G

    2014-04-30

    Bivalve samples from 142 sites were analyzed to determine the concentration and toxicity equivalents (TEQ) of dioxins and furans (D/F) as part of the NOAA National Status and Trends Program. The total concentration of 17 D/F ranged from not detected to 203 pg/g wet weight of tissue. Octachlorinated dibenzo-p-dioxin, OCDD, had a concentration range from not detected to 189 pg/g and a mean concentration of 8.65 pg/g. OCDD was the dominant D/F compound detected and accounted for, on average, over 70% of the total D/F concentration. The TEQ (compared to 2,3,7,8-TCDD) ranged from 0.12 to 7.32 pg TEQ/g. The TEQ for 39% of the bivalves analyzed were below 0.238 pg TEQ/g. TEQ above human consumption advisory concentration of 1.2 pg TEQ/g were found in 9.3% of the samples analyzed. TEQ for D/F indicate very limited human health concerns from consumption of bivalves at most of the locations sampled. PMID:24095200

  9. [Community structure of bivalves and gastropods in roots of red mangrove Rhizophora mangle (Rhizophoraceae) in isla Larga, Mochima Bay, Venezuela].

    PubMed

    Acosta Balbas, Vanessa; Betancourt Tineo, Rafael; Prieto Arcas, Antulio

    2014-06-01

    The Rhizophora mangle roots form a complex ecosystem where a wide range of organisms are permanently established, reproduce, and find refuge. In this study, we assessed the diversity of bivalves and gastropods that inhabit red mangrove roots, in isla Larga, Mochima, Venezuela Sucre state. Bimonthly collections were made from January 2007 to May 2008, in four study areas denominated: South, North, East and West. In each area, five mangrove roots were sampled, and the specimens were obtained. We analyzed a total of 180 roots and a total of 35 bivalve species and 25 gastropod species were found. The most abundant bivalves were: Isognomon alatus, Isognomon bicolor, Ostrea equestris, Crassostrea rhizophorae and Brachidontes exustus; among gastropods, the most common where: Littorina angulifera, (Cymatium pileare and Diodora cayenensis. The months with the highest abundances and number of individuals for both groups were January and July 2007, and March 2008. The mangrove ecosystem in isla Larga, presented a number of individuals and species higher than those reported for other regions in Venezuela and the Caribbean. PMID:25102639

  10. Polychlorinated dibenzo-p-dioxins and dibenzofurans detected in bivalve samples from the NOAA National Status and Trends Program.

    PubMed

    Wade, Terry L; Sweet, Stephen T; Sericano, José L; Defreitas, Debra A; Lauenstein, Gunnar G

    2014-04-30

    Bivalve samples from 142 sites were analyzed to determine the concentration and toxicity equivalents (TEQ) of dioxins and furans (D/F) as part of the NOAA National Status and Trends Program. The total concentration of 17 D/F ranged from not detected to 203 pg/g wet weight of tissue. Octachlorinated dibenzo-p-dioxin, OCDD, had a concentration range from not detected to 189 pg/g and a mean concentration of 8.65 pg/g. OCDD was the dominant D/F compound detected and accounted for, on average, over 70% of the total D/F concentration. The TEQ (compared to 2,3,7,8-TCDD) ranged from 0.12 to 7.32 pg TEQ/g. The TEQ for 39% of the bivalves analyzed were below 0.238 pg TEQ/g. TEQ above human consumption advisory concentration of 1.2 pg TEQ/g were found in 9.3% of the samples analyzed. TEQ for D/F indicate very limited human health concerns from consumption of bivalves at most of the locations sampled.

  11. Impact of seawater carbonate chemistry on the calcification of marine bivalves

    NASA Astrophysics Data System (ADS)

    Thomsen, J.; Haynert, K.; Wegner, K. M.; Melzner, F.

    2015-01-01

    Bivalve calcification, particular of the early larval stages is highly sensitive to the change of ocean carbonate chemistry resulting from atmospheric CO2 uptake. Earlier studies suggested that declining seawater [CO32-] and thereby lowered carbonate saturation affect shell production. However, disturbances of physiological processes such as acid-base regulation by adverse seawater pCO2 and pH can affect calcification in a secondary fashion. In order to determine the exact carbonate system component by which growth and calcification are affected it is necessary to utilize more complex carbonate chemistry manipulations. As single factors, pCO2 had no and [HCO3-] and pH only limited effects on shell growth, while lowered [CO32-] strongly impacted calcification. Dissolved inorganic carbon (CT) limiting conditions led to strong reductions in calcification, despite high [CO32-], indicating that [HCO3-] rather than [CO32-] is the inorganic carbon source utilized for calcification by mytilid mussels. However, as the ratio [HCO3-] / [H+] is linearly correlated with [CO32-] it is not possible to differentiate between these under natural seawater conditions. Therefore, the availability of [HCO3-] combined with favorable environmental pH determines calcification rate and an equivalent of about 80 μmol kg-1 [CO32-] is required to saturate inorganic carbon supply for calcification in bivalves. Below this threshold biomineralization rates rapidly decline. A comparison of literature data available for larvae and juvenile mussels and oysters originating from habitats differing substantially with respect to prevailing carbonate chemistry conditions revealed similar response curves. This suggests that the mechanisms which determine sensitivity of calcification in this group are highly conserved. The higher sensitivity of larval calcification seems to primarily result from the much higher relative calcification rates in early life stages. In order to reveal and understand the

  12. Sr/Ca and Mg/Ca in Aragonitic Bivalves: Do They Record Temperature?

    NASA Astrophysics Data System (ADS)

    Gillikin, D. P.; Ulens, H.; Dehairs, F.; Baeyens, W.; Navez, J.; Andre, L.; Keppens, E.; Calmars Group,.

    2003-12-01

    The chemical or isotopic composition of calcareous skeletons have long been recognized as archives of past and present environmental conditions. Oxygen isotopes (d18O) of biogenic carbonates are a powerful proxy of SST, however, although usually dominated by SST, salinity (SSS) also significantly effects the oxygen isotopic signal recorded in the carbonate. This has led researchers to explore new proxies, which are independent of SSS. Generally, Sr/Ca and Mg/Ca of seawater remains unchanged above salinities of 10 and marine animals will commonly live in habitats that do not fluctuate below this salinity. To solve the issue of SSS complicating paleotemperature records, these "new" proxies must be at least as reliable as d18O. If an environmental control is dominant, the proxies should be reproducible between specimens growing under the same field conditions. Both Sr and Mg have been used as paleotemperature proxies in corals and foraminifera, whereas a fewer attempts have been made to use these proxies in bivalves. Some report a clear seasonal periodicity in Sr/Ca profiles of bivalves, which covaries with d18O (i.e., temperature), whereas others have found no clear periodicity. We test the robustness of these proxies by analyzing the shell material from three species of aragonitic clams from around the world using a LA-ICP-MS. Three individuals of M. mercenaria from North Carolina, USA, three individuals of Saxidomus giganteus from Washington, USA and one Arctica islandica from Norway have been analyzed. As expected, there is excellent reproducibility of d18O between specimens (both M. mercenaria and S. giganteus) indicating external environmental conditions control this proxy (i.e. SST and SSS). Preliminary data analysis show that Sr and Mg are not reproducible between specimens from the same site nor do they exhibit a clear seasonal cyclicity, indicating individual metabolic effects (i.e., vital effects) dominate the incorporation of these elements. A. islandica

  13. Ocean Acidification at High Latitudes: Potential Effects on Functioning of the Antarctic Bivalve Laternula elliptica

    PubMed Central

    Cummings, Vonda; Hewitt, Judi; Van Rooyen, Anthony; Currie, Kim; Beard, Samuel; Thrush, Simon; Norkko, Joanna; Barr, Neill; Heath, Philip; Halliday, N. Jane; Sedcole, Richard; Gomez, Antony; McGraw, Christina; Metcalf, Victoria

    2011-01-01

    Ocean acidification is a well recognised threat to marine ecosystems. High latitude regions are predicted to be particularly affected due to cold waters and naturally low carbonate saturation levels. This is of concern for organisms utilising calcium carbonate (CaCO3) to generate shells or skeletons. Studies of potential effects of future levels of pCO2 on high latitude calcifiers are at present limited, and there is little understanding of their potential to acclimate to these changes. We describe a laboratory experiment to compare physiological and metabolic responses of a key benthic bivalve, Laternula elliptica, at pCO2 levels of their natural environment (430 µatm, pH 7.99; based on field measurements) with those predicted for 2100 (735 µatm, pH 7.78) and glacial levels (187 µatm, pH 8.32). Adult L. elliptica basal metabolism (oxygen consumption rates) and heat shock protein HSP70 gene expression levels increased in response both to lowering and elevation of pH. Expression of chitin synthase (CHS), a key enzyme involved in synthesis of bivalve shells, was significantly up-regulated in individuals at pH 7.78, indicating L. elliptica were working harder to calcify in seawater undersaturated in aragonite (ΩAr = 0.71), the CaCO3 polymorph of which their shells are comprised. The different response variables were influenced by pH in differing ways, highlighting the importance of assessing a variety of factors to determine the likely impact of pH change. In combination, the results indicate a negative effect of ocean acidification on whole-organism functioning of L. elliptica over relatively short terms (weeks-months) that may be energetically difficult to maintain over longer time periods. Importantly, however, the observed changes in L. elliptica CHS gene expression provides evidence for biological control over the shell formation process, which may enable some degree of adaptation or acclimation to future ocean acidification scenarios. PMID:21245932

  14. A Mixed-Ligand Approach for a Gigantic and Hollow Heterometallic Cage {Ni64 RE96 } for Gas Separation and Magnetic Cooling Applications.

    PubMed

    Chen, Wei-Peng; Liao, Pei-Qin; Yu, Youzhu; Zheng, Zhiping; Chen, Xiao-Ming; Zheng, Yan-Zhen

    2016-08-01

    Nanosized aggregations of metal ions shielded by organic ligands possessing both exquisite structural aesthetics and intriguing properties are fundamentally interesting. Three isostructural gigantic transition-metal-rare-earth heterometallic coordination cages are reported, abbreviated as {Ni64 RE96 } (RE=Gd, Dy, and Y) and obtained by a mixed-ligand approach, each possessing a cuboidal framework made of 160 metal ions and a nanosized spherical cavity in the center. Along with the structural novelty, these hollow cages show highly selective adsorptions for CO2 over CH4 or N2 at ambient temperatures. Moreover, the gadolinium analogue exhibits large magnetocaloric effect at ultralow temperatures.

  15. A Mixed-Ligand Approach for a Gigantic and Hollow Heterometallic Cage {Ni64 RE96 } for Gas Separation and Magnetic Cooling Applications.

    PubMed

    Chen, Wei-Peng; Liao, Pei-Qin; Yu, Youzhu; Zheng, Zhiping; Chen, Xiao-Ming; Zheng, Yan-Zhen

    2016-08-01

    Nanosized aggregations of metal ions shielded by organic ligands possessing both exquisite structural aesthetics and intriguing properties are fundamentally interesting. Three isostructural gigantic transition-metal-rare-earth heterometallic coordination cages are reported, abbreviated as {Ni64 RE96 } (RE=Gd, Dy, and Y) and obtained by a mixed-ligand approach, each possessing a cuboidal framework made of 160 metal ions and a nanosized spherical cavity in the center. Along with the structural novelty, these hollow cages show highly selective adsorptions for CO2 over CH4 or N2 at ambient temperatures. Moreover, the gadolinium analogue exhibits large magnetocaloric effect at ultralow temperatures. PMID:27345594

  16. Oxygen Isotopes in Bivalve Shells Record Hydrological Changes in the Siberian Land-Shelf Connection on Annual Timescales

    NASA Astrophysics Data System (ADS)

    Mueller-Lupp, T.; Bauch, H. A.; Erlenkeuser, H.

    2002-12-01

    It is now widely accepted that changes in surface ocean hydrology at northern high latitudes is a major forcing mechanism that can strongly perturbate a particular climate mode. Given the variability on subdecadal and on centennial to millennial timescales, the dispersal and fate of arctic riverine water discharge and its role on the ice regime as well as on surface water properties are central issues in the understanding of Holocene climate change in the arctic marginal seas, the Arctic Ocean, and beyond. Oxygen isotope profiles from living and fossil bivalves were investigated in order to trace modern and past hydrographical changes in the strongly coupled land-shelf system of the Laptev Sea. Detailed oxygen isotope measurements were executed on the shells along their axis of maximum growth and provide an isotopic record of hydrological and environmental changes for the lifespan of the individual bivalves. The oxygen isotopic records exhibit amplitude cycles interpreted as recording annual cycles. Based on the well-known relationship between the carbonate δ18O, temperature and the isotopic composition of water, it is possible to relate phases of more negative (lighter) δ18O values indicating summer and more positive (heavier) δ18O values indicating the winter season. The main forcing factor of the δ18O variations is the variability of the isotopic composition of the bottom water. Measurements of δ18O in surface and bottom waters of the Laptev Sea show a linear relation of salinity and water δ18O with a coefficient of 0.50 \\permil salinity-1 and document the mixing of freshwater and seawater. The δ18O cycles from growing profiles of the living bivalves indicate a correspondence to seasonal hydrographic changes and can be compared with runoff data and circulation patterns in the Laptev Sea. Given the seasonal cycles in living bivalves, oxygen isotope profiles of fossil, radiocarbon-dated, and well-preserved bivalve shells from sediment cores are used to

  17. Commensal associations and benthic habitats shape macroevolution of the bivalve clade Galeommatoidea.

    PubMed

    Li, Jingchun; Ó Foighil, Diarmaid; Strong, Ellen E

    2016-07-13

    The great diversity of marine life has been shaped by the interplay between abiotic and biotic factors. Among different biotic interactions, symbiosis is an important yet less studied phenomenon. Here, we tested how symbiotic associations affected marine diversification, using the bivalve superfamily Galeommatoidea as a study system. This superfamily contains large numbers of obligate commensal as well as free-living species and is therefore amenable to comparative approaches. We constructed a global molecular phylogeny of Galeommatoidea and compared macroevolutionary patterns between free-living and commensal lineages. Our analyses inferred that commensalism/sediment-dwelling is likely to be the ancestral condition of Galeommatoidea and that secondary invasions of hard-bottom habitats linked to the loss of commensalism. One major clade containing most of the free-living species exhibits a 2-4 times higher diversification rate than that of the commensals, likely driven by frequent niche partitioning in highly heterogeneous hard-bottom habitats. However, commensal clades show much higher within-clade morphological disparity, likely promoted by their intimate associations with diverse hosts. Our study highlights the importance of interactions between different ecological factors in shaping marine macroevolution and that biotic factors cannot be ignored if we wish to fully understand processes that generate marine biodiversity. PMID:27383818

  18. The packaging problem: bivalve prey selection and prey entry techniques of the octopus Enteroctopus dofleini.

    PubMed

    Anderson, Roland C; Mather, Jennifer A

    2007-08-01

    Many predators face a complex step of prey preparation before consumption. Octopuses faced with bivalve prey use several techniques to penetrate the shells to gain access to the meat inside. When given prey of mussels Mytilus trossulus, Manila clams Venerupis philippinarum, and littleneck clams Protothaca staminea, Enteroctopus dofleini solved the problem differently. They pulled apart V. philippinarum and M. trossulus, which had the thinnest shells and the least pulling resistance. P. staminea were eaten after the shells had been chipped or had been penetrated by drilling, presumably to inject a toxin. Likely because of these differences, octopuses consumed more V. philippinarum and M. trossulus than P. staminea when the mollusks were given to them either 1 species at a time or all together. However, when the shells were separated and the penetration problem removed, the octopuses predominantly chose P. staminea and nearly ignored M. trossulus. When V. philippinarum were wired shut, octopuses switched techniques. These results emphasize that octopuses can learn on the basis of nonvisual information and monitor their body position to carry out feeding actions.

  19. Polonium-210 in marine mussels (bivalve molluscs) inhabiting the southern coast of India.

    PubMed

    Khan, M Feroz; Wesley, S Godwin; Rajan, M P

    2014-12-01

    The present study focused on the determination of the alpha-emitter, (210)Po, in two species of marine mussels (bivalve molluscs) commonly available in the southern coastal region of India. The brown mussel, Perna indica was collected from the west coast and the green mussel, Perna viridis from the east coast. The concentration of (210)Po was related to the allometry (length of shell, wet/dry weight of shell/soft tissue) of the mussels and significant results were found. The study period focused on three seasons namely, pre-monsoon, monsoon and post-monsoon for a 1-year period (2010-2011). The results revealed higher activity levels in smaller-sized mussels compared to larger ones. Marked variation in (210)Po activity concentration was noted in the whole-body soft tissues between seasons and sampling site (p < 0.05). The dose rate assessment for mussels was performed using the ERICA Assessment tool. The chronic exposure to mussels due to (210)Po was found to be lesser than the global benchmark dose rate of 10 μGy h(-1). The effective ingestion dose to adults who intake mussels was estimated to be in the range 5.1-34.9 μSv y(-1). The measurement contributes to the furthering of knowledge of (210)Po, since no data exist in this region.

  20. Mass mortality in bivalves and the intricate case of the Pacific oyster, Crassostrea gigas.

    PubMed

    Barbosa Solomieu, Valérie; Renault, Tristan; Travers, Marie-Agnès

    2015-10-01

    Massive mortality outbreaks in cultured bivalves have been reported worldwide and they have been associated with infection by a range of viral and bacterial pathogens. Due to their economic and social impact, these episodes constitute a particularly sensitive issue in Pacific oyster (Crassostrea gigas) production. Since 2008, mortality outbreaks affecting C. gigas have increased in terms of intensity and geographic distribution. Epidemiologic surveys have lead to the incrimination of pathogens, specifically OsHV-1 and bacteria of the Vibrio genus, in particular Vibrio aestuarianus. Pathogen diversity may partially account for the variability in the outcome of infections. Host factors (age, reproductive status...) including their genetic background that has an impact on host susceptibility toward infection, also play a role herein. Finally, environmental factors have significant effects on the pathogens themselves, on the host and on the host-pathogen interaction. Further knowledge on pathogen diversity, classification, and spread, may contribute toward a better understanding of this issue and potential ways to mitigate the impact of these outbreaks. PMID:26210497

  1. Stable metal isotopes reveal copper accumulation and loss dynamics in the freshwater bivalve Corbucula

    USGS Publications Warehouse

    Croteau, M.-N.; Luoma, S.N.; Topping, B.R.; Lopez, C.B.

    2004-01-01

    Characterization of uptake and loss dynamics is critical to understanding risks associated with contaminant exposure in aquatic animals. Dynamics are especially important in addressing questions such as why coexisting species in nature accumulate different levels of a contaminant. Here we manipulated copper (Cu) stable isotopic ratios (as an alternative to radioisotopes) to describe for the first time Cu dynamics in a freshwater invertebrate, the bivalve Corbicula fluminea. In the laboratory, Corbicula uptake and loss rate constants were determined from an environmentally realistic waterborne exposure to 65Cu (5.7 ??g L-1). That is, we spiked deionized water with Cu that was 99.4% 65Cu. Net tracer uptake was detectable after 1 day and strongly evident after 4 days. Thus, short-term exposures necessary to determine uptake dynamics are feasible with stable isotopes of Cu. In Corbicula, 65Cu depuration was biphasic. An unusually low rate constant of loss (0.0038 d-1) characterized the slow component of efflux, explaining why Corbicula strongly accumulates copper in nature. We incorporated our estimates of rate constants for dissolved 65Cu uptake and physiological efflux into a bioaccumulation model and showed that dietary exposure to Cu is likely an important bioaccumulation pathway for Corbicula.

  2. Respiratory response to combined heat and hypoxia in the marine bivalves Pecten maximus and Mytilus spp.

    PubMed

    Artigaud, Sébastien; Lacroix, Camille; Pichereau, Vianney; Flye-Sainte-Marie, Jonathan

    2014-09-01

    Coastal ecosystems are increasingly disturbed by the increase of mean sea surface temperature and expansion of hypoxic areas. The objectives of the present work were to describe and compare the respiratory responses to combined heat and hypoxia in two bivalve species (Pecten maximus and Mytilus spp.) living in two contrasted coastal habitats (subtidal and intertidal, respectively). Results were consistent with the vertical zonation of both species. Mytilus spp. seemed to cope better with a temperature increase than P. maximus, which was found to be outside of its optimal thermal window at 25°C. Concerning respiratory responses to hypoxia at a given temperature, P. maximus displayed greater oxyregulation capacity that was maintained over a larger range of O2 levels, as compared to Mytilus spp. When acclimation temperatures increased, both species showed a decrease in their oxyregulation capacities alongside a reduction in aerobic performance, especially in P. maximus. The comparison between species suggests that subtidal species, such as P. maximus, might be more vulnerable to a combination of heat and hypoxia than intertidal species, such as Mytilus spp. Lastly, this study highlighted the utility of segmented linear models to estimate PcO2 and regulation percentages in marine organisms exposed to hypoxia.

  3. The Shell of the Invasive Bivalve Species Dreissena polymorpha: Biochemical, Elemental and Textural Investigations.

    PubMed

    Immel, Françoise; Broussard, Cédric; Catherinet, Bastien; Plasseraud, Laurent; Alcaraz, Gérard; Bundeleva, Irina; Marin, Frédéric

    2016-01-01

    The zebra mussel Dreissena polymorpha is a well-established invasive model organism. Although extensively used in environmental sciences, virtually nothing is known of the molecular process of its shell calcification. By describing the microstructure, geochemistry and biochemistry/proteomics of the shell, the present study aims at promoting this species as a model organism in biomineralization studies, in order to establish a bridge with ecotoxicology, while sketching evolutionary conclusions. The shell of D. polymorpha exhibits the classical crossed-lamellar/complex crossed lamellar combination found in several heterodont bivalves, in addition to an external thin layer, the characteristics of which differ from what was described in earlier publication. We show that the shell selectively concentrates some heavy metals, in particular uranium, which predisposes D. polymorpha to local bioremediation of this pollutant. We establish the biochemical signature of the shell matrix, demonstrating that it interacts with the in vitro precipitation of calcium carbonate and inhibits calcium carbonate crystal formation, but these two properties are not strongly expressed. This matrix, although overall weakly glycosylated, contains a set of putatively calcium-binding proteins and a set of acidic sulphated proteins. 2D-gels reveal more than fifty proteins, twenty of which we identify by MS-MS analysis. We tentatively link the shell protein profile of D. polymorpha and the peculiar recent evolution of this invasive species of Ponto-Caspian origin, which has spread all across Europe in the last three centuries. PMID:27213644

  4. Cross-habitat interactions among bivalve species control community structure on intertidal flats.

    PubMed

    Donadi, Serena; van der Heide, Tjisse; van der Zee, Els M; Eklöf, Johan S; van de Koppel, Johan; Weerman, Ellen J; Piersma, Theunis; Olff, Han; Eriksson, Britas Klemens

    2013-02-01

    Increasing evidence shows that spatial interactions between sedentary organisms can structure communities and promote landscape complexity in many ecosystems. Here we tested the hypothesis that reef-forming mussels (Mytilus edulis L.), a dominant intertidal ecosystem engineer in the Wadden Sea, promote abundances of the burrowing bivalve Cerastoderma edule L. (cockle) in neighboring habitats at relatively long distances coastward from mussel beds. Field surveys within and around three mussel beds showed a peak in cockle densities at 50-100 m toward the coast from the mussel bed, while cockle abundances elsewhere in the study area were very low. Field transplantation of cockles showed higher survival of young cockles (2-3 years old) and increased spat fall coastward of the mussel bed compared to within the bed and to areas without mussels, whereas growth decreased within and coastward of the mussel bed. Our measurements suggest that the observed spatial patterns in cockle numbers resulted from (1) inhibition effects by the mussels close to the beds due to preemptive algal depletion and deteriorated sediment conditions and (2) facilitation effects by the mussels farther away from the beds due to reduction of wave energy. Our results imply that these spatial, scale-dependent interactions between reef-forming ecosystem engineers and surrounding communities of sedentary benthic organisms can be an important determinant of the large-scale community structure in intertidal ecosystems. Understanding this interplay between neighboring communities of sedentary species is therefore essential for effective conservation and restoration of soft-bottom intertidal communities.

  5. Cytomorphology and PCNA expression pattern in bivalves Mytilus galloprovincialis and Cerastoderma edule with haemic neoplasia.

    PubMed

    Carella, Francesca; Figueras, Antonio; Novoa, Beatriz; De Vico, Gionata

    2013-07-01

    Haemic neoplasia (HN) is a pathologic condition reported in several bivalve species in different geographic areas. In this study we describe the cytomorphological features and the proliferative behaviour, assessed by the proliferating cell nuclear antigen (PCNA), of HN in common cockle Cerastoderma edule and Mediterranean mussel Mytilus galloprovicialis. In mussels the presence of at least 5 types of atypical haemocytes was detected, including A- and B-type cells, previously described in M. edulis and Mytilus sp., with predominance of A-type cells in early phases of the disease and B-type cells in more advanced stages. PCNA immunostaining was positive for 97 to 100% of the neoplastic cells, with both cytoplasmic (A cells) and nuclear patterns (B cells). Conversely, in C. edule there was no distinctive morphological cell sub-population, and staining atypical haemocytes with PCNA (range 93 to 100%) showed nuclear expression in early phases of disease and cytoplasmic expression in more advanced stages. The above findings suggest distinct histo-pathogenetic pathways for HN in mussels and common cockles.

  6. An evaluation of the relative sensitivity of two marine bivalve mollusc species using the Comet assay.

    PubMed

    Cheung, Victoria V; Depledge, Michael H; Jha, Awadhesh N

    2006-07-01

    The aim of this study was to (a) evaluate the potential for the 'Comet assay' to be used as a method for detecting genetic damage in the common cockle Cerastoderma edule; and (b) to compare the relative sensitivity with Mytilus edulis as the bivalve widely used as a sentinel species in biomonitoring studies. In vitro validation studies were carried out on haemocytes from each species using hydrogen peroxide (H2O2), a known oxidant and the induced DNA damage was measured using the Comet assay. On exposure to 0, 100, 500 and 1000 microM H2O2, a significant concentration-dependent increase was observed in both species. Use of an additional concentration of 5000 microM H2O2 showed that while DNA damage could be assessed in M. edulis at this concentration, only a few cells from C. edule were amenable to measurements owing to extensive DNA damage ("hedgehog cells"). The evidence also suggested that the cells from C. edule are more sensitive to oxidative damage induced by H2O2 when compared with M. edulis. Bearing in mind that sediments are the ultimate sink for many contaminants, this study demonstrates the potential application of sediment-dwelling C. edule as a useful biomonitoring species.

  7. Zachsia zenkewitschi (Teredinidae), a Rare and Unusual Seagrass Boring Bivalve Revisited and Redescribed.

    PubMed

    Shipway, J R; O'Connor, R; Stein, D; Cragg, S M; Korshunova, T; Martynov, A; Haga, T; Distel, D L

    2016-01-01

    The sea-grass borer Zachsia zenkewitschi belongs to a group of economically and ecologically important bivalves, commonly referred to as shipworms. The sole recognized representative of the genus Zachsia, this species displays an unusual life history and reproductive strategy that is now understood to include: environmental sex determination of free swimming larvae, extreme sexual and size dimorphism between males and females, internal fertilization, maintenance of often large harems of male dwarfs within a specialized cavity of the female mantle, and complex maternal care of larvae in specialized brood pouches within the gill. It is also the only shipworm species known to burrow in sea grass rhizomes rather than terrestrial wood. Although Z. zenkewitschi is rare and little studied, understanding of its biology and anatomy has evolved substantially, rendering some aspects of its original description inaccurate. Moreover, no existing type specimens are known for this species. In light of these facts, we designate a neotype from among specimens recently collected at the type location, and undertake a re-description of this species, accounting for recent reinterpretation of its life history and functional anatomy. PMID:27171209

  8. Environmental versus biological controls on multi-proxy records from bivalve shell carbonate

    NASA Astrophysics Data System (ADS)

    Hippler, D.; Kluender, M. H.; Witbaard, R.; Buhl, D.; Richter, D.; Frei, D.; Immenhauser, A.

    2007-12-01

    Field experiments on different bivalve species have been conducted in the Dutch Wadden Sea near the Netherlands Institute for Sea Research (NIOZ) to investigate the environmental and biological controls on the fractionation pattern of different stable isotope systems (18O/16O, 26Mg/24Mg, 44Ca/42Ca) and elemental/calcium ratios, and their reliability as geochemical proxies for high- resolution palaeoclimate reconstructions. Our study includes various individuals of the blue mussel, Mytilus edulis and juveniles of the ocean quahog, Arctica islandica. Our study is completed using samples from growth experiments on young Arcitca's which were also performed at the NIOZ laboratory. These individuals were cultured in five temperature controlled basins, ranging from 1 to 12° Celcius. The third sample set analysed was collected at several sites in the Baltic Sea characterised by salinities lower than 15 permil. Our data shows that both species deposit their shells in isotopic equilibrium with ambient seawater. Trace element ratios in Mytilus edulis further indicate that Mg/Ca may indeed provide a reliable palaeothermometer. In contrast, Calcium and magnesium isotope fractionation is obviously controlled by biological processes. However, environmental signals (e.g. temperature, salinity) are well recorded in the shells. Therefore, the combined approach could give new insights into biomineralization processes. This is a contribution to EuroCLIMATE project 04 ECLIM FP08 CASIOPEIA.

  9. The packaging problem: bivalve prey selection and prey entry techniques of the octopus Enteroctopus dofleini.

    PubMed

    Anderson, Roland C; Mather, Jennifer A

    2007-08-01

    Many predators face a complex step of prey preparation before consumption. Octopuses faced with bivalve prey use several techniques to penetrate the shells to gain access to the meat inside. When given prey of mussels Mytilus trossulus, Manila clams Venerupis philippinarum, and littleneck clams Protothaca staminea, Enteroctopus dofleini solved the problem differently. They pulled apart V. philippinarum and M. trossulus, which had the thinnest shells and the least pulling resistance. P. staminea were eaten after the shells had been chipped or had been penetrated by drilling, presumably to inject a toxin. Likely because of these differences, octopuses consumed more V. philippinarum and M. trossulus than P. staminea when the mollusks were given to them either 1 species at a time or all together. However, when the shells were separated and the penetration problem removed, the octopuses predominantly chose P. staminea and nearly ignored M. trossulus. When V. philippinarum were wired shut, octopuses switched techniques. These results emphasize that octopuses can learn on the basis of nonvisual information and monitor their body position to carry out feeding actions. PMID:17696656

  10. Bioaccumulation of polycyclic aromatic hydrocarbons in bivalves from Sugarland Run and the Potomac River

    SciTech Connect

    Barber, T.R.; Lauren, D.J.; Dimitry, J.A. |

    1995-12-31

    A bioaccumulation study was conducted following a release of Fuel Oil {number_sign}2 into Sugarland Run, a small northern Virginia stream. Caged clams (Corbicula sp.) were placed in 3 downstream locations and 2 upstream reference areas for an exposure period of approximately 28 days. In addition, resident clams from the Potomac River were sampled at the start of the study and at 4 and 8 weeks. Chemical fingerprinting techniques were employed to identify spill-related polycyclic aromatic hydrocarbons (PAHs) and to differentiate these compounds from background sources of contamination. The greatest concentration of spill-related PAHs (2 and 3-ring compounds) were measured in clams placed immediately downstream of the spill site, and tissue concentrations systematically decreased with distance from the spill site. PAHs that were not related to Fuel Oil {number_sign}2 were found in all clams and accounted for up to 90% of the total body burden at downstream locations. Furthermore, the highest concentrations of 4-, 5-, and 6-ring PAH were found at the upstream reference location, and indicated an important source of PAHs into the environment. Body burdens measured in this study were compared to ambient concentrations reported for bivalves from a variety of environments. Tissue concentrations were also compared to concentrations that have been reported to cause adverse biological effects.

  11. The evolutionary origins of the southern ocean Philobryid bivalves: hidden biodiversity, ancient persistence.

    PubMed

    Jackson, Jennifer A; Linse, Katrin; Whittle, Rowan; Griffiths, Huw J

    2015-01-01

    Philobryids (Bivalvia: Arcoida) are one of the most speciose marine bivalve families in the Southern Ocean and are common throughout the Southern Hemisphere. Considering this diversity and their brooding reproductive mode (limiting long-distance dispersal), this family may have been present in the Southern Ocean since its inception. However Philobrya and Adacnarca appear only in the Quaternary fossil record of the Antarctic, suggesting a much more recent incursion. Molecular dating provides an independent means of measuring the time of origin and radiation of this poorly known group. Here we present the first combined molecular and morphological investigation of the Philobryidae in the Southern Ocean. Two nuclear loci (18S and 28S) were amplified from 35 Southern Ocean Adacnarca and Philobrya specimens, with a combined sequence length of 2,282 base pairs (bp). Adacnarca specimens (A. nitens and A. limopsoides) were resolved as a strongly supported monophyletic group. Genus Philobrya fell into two strongly supported groups ('sublaevis' and 'magellanica/wandelensis'), paraphyletic with Adacnarca. The A. nitens species complex is identified as at least seven morpho-species through morphological and genetic analysis of taxon clustering. Phylogenetic analyses resolve Philobryidae as a strongly supported monophyletic clade and sister taxon to the Limopsidae, as anticipated by their classification into the superfamily Limopsoidea. Bayesian relaxed clock analyses of divergence times suggest that genus Adacnarca radiated in the Southern Ocean from the Early Paleogene, while P. sublaevis and P. wandelensis clades radiated in the late Miocene, following the formation of the Antarctic Circumpolar Current.

  12. Biogeophysical interactions between behavior of crabs, bivalves and birds and intertidal geoenvironmental variability

    NASA Astrophysics Data System (ADS)

    Sassa, S.; Watabe, Y.; Yang, S.; Kuwae, T.

    2011-12-01

    Tidal flats and beaches are vital elements in the sustainability of coastal environments since they foster rich natural ecosystems. Previous research in the fields of oceanology and ecology has been directed to understanding the diversity of ecosystems and their linkage with oceanic environments involving waves and tides. Here, we show that such oceanic environments yield marked geoenvironmental changes at the edge of the ocean where the diversity of creatures live. Our series of field observations/surveys and controlled laboratory experiments demonstrated that the tide and swash induced dynamics of suction, i.e. negative pore water pressure relative to atmospheric pressure, bring about a variety of changes in behavior, in terms of both burrowing and foraging, of crabs, bivalves and birds, and were responsible for the suitable and critical conditions for their survival and adaptations. The present results reveal and highlight the importance of the biogeophysical interactions between such diverse creatures and intertidal geoenvironmental variability at the edge of the ocean, and may thus facilitate conservation and restoration of habitats with rich natural ecosystems in intertidal zones.

  13. Influence of acid-soluble proteins from bivalve Siliqua radiata ligaments on calcium carbonate crystal growth

    NASA Astrophysics Data System (ADS)

    Huang, Zeng-Qiong; Zhang, Gang-Sheng

    2016-08-01

    In vitro biomimetic synthesis of calcium carbonate (CaCO3) in the presence of shell proteins is a heavily researched topic in biomineralization. However, little is known regarding the function of bivalve ligament proteins in the growth of CaCO3 crystals. In this study, using fibrous protein K58 from Siliqua radiata ligaments or coverslips as substrates, we report the results of our study of CaCO3 precipitation in the presence or absence of acid-soluble proteins (ASP) from inner ligament layers. ASP can disturb the controlling function of K58 or a coverslip on the crystalline phase, resulting in the formation of aragonite, calcite, and vaterite. In addition, we identified the following four primary components from ASP by mass spectroscopy: alkaline phosphatase (ALP), ABC transporter, keratin type II cytoskeletal 1 (KRT 1), and phosphate ABC transporter, phosphate-binding protein (PstS). Further analysis revealed that the first three proteins and especially ALP, which is important in bone mineralisation, could affect the polymorphism and morphology of CaCO3 crystals by trapping calcium ions in their domains. Our results indicate that ALP may play an important role in the formation of aragonite in S. radiata ligaments. This paper may facilitate our understanding of the biomineralization process.

  14. Draft Genome of the Pearl Oyster Pinctada fucata: A Platform for Understanding Bivalve Biology

    PubMed Central

    Takeuchi, Takeshi; Kawashima, Takeshi; Koyanagi, Ryo; Gyoja, Fuki; Tanaka, Makiko; Ikuta, Tetsuro; Shoguchi, Eiichi; Fujiwara, Mayuki; Shinzato, Chuya; Hisata, Kanako; Fujie, Manabu; Usami, Takeshi; Nagai, Kiyohito; Maeyama, Kaoru; Okamoto, Kikuhiko; Aoki, Hideo; Ishikawa, Takashi; Masaoka, Tetsuji; Fujiwara, Atushi; Endo, Kazuyoshi; Endo, Hirotoshi; Nagasawa, Hiromichi; Kinoshita, Shigeharu; Asakawa, Shuichi; Watabe, Shugo; Satoh, Nori

    2012-01-01

    The study of the pearl oyster Pinctada fucata is key to increasing our understanding of the molecular mechanisms involved in pearl biosynthesis and biology of bivalve molluscs. We sequenced ∼1150-Mb genome at ∼40-fold coverage using the Roche 454 GS-FLX and Illumina GAIIx sequencers. The sequences were assembled into contigs with N50 = 1.6 kb (total contig assembly reached to 1024 Mb) and scaffolds with N50 = 14.5 kb. The pearl oyster genome is AT-rich, with a GC content of 34%. DNA transposons, retrotransposons, and tandem repeat elements occupied 0.4, 1.5, and 7.9% of the genome, respectively (a total of 9.8%). Version 1.0 of the P. fucata draft genome contains 23 257 complete gene models, 70% of which are supported by the corresponding expressed sequence tags. The genes include those reported to have an association with bio-mineralization. Genes encoding transcription factors and signal transduction molecules are present in numbers comparable with genomes of other metazoans. Genome-wide molecular phylogeny suggests that the lophotrochozoan represents a distinct clade from ecdysozoans. Our draft genome of the pearl oyster thus provides a platform for the identification of selection markers and genes for calcification, knowledge of which will be important in the pearl industry. PMID:22315334

  15. Structure and classification of haemocytes in the bivalve mollusc Meretrix meretrix

    NASA Astrophysics Data System (ADS)

    Zhang, Yanyan; Ren, Sulian; Wang, Dexiu; Song, Weibo

    2006-04-01

    Light and electron microscopic studies were carried out in order to characterize haemocytes in the bivalve molluse Meretrix meretrix. According to nucleus and cytoplasm characters, four types of haemocytes were recognized: agranular haemocytes, lymphoid haemocyte, large granular and small granular haemocytes. Agranular hamocyte is the main cell type, accounting for 75%. It is agranular with rich organelles in cytoplasm, including mitochondria, golgi body and endoplasmic reticulum. Glycogen deposits were usually found in this cell type. The number of lymphoid haemocyte accounts for 1% 2%. This cell type is agranular and shows a high ratio of nucleus to cytoplasm. A few organelles were found. High electrondense granules with diameters of 0.2 0.5 μm and rich organelles were found in small granular haemocyte. The proportion of this cell type is about 15%. Rich granules of high electron-dense with diameters of 0.8 2.4 μm were found in large granular haemocyte. The proportion of this cell type is about 10%, and the quantity of organelles is the least.

  16. Structure and classification of haemocytes in the bivalve mollusc Meretrix meretrix

    NASA Astrophysics Data System (ADS)

    Yanyan, Zhang; Sulian, Ren; Dexiu, Wang; Weibo, Song

    2006-04-01

    Light and electron microscopic studies were carried out in order to characterize haemocytes in the bivalve molluse Meretrix meretrix. According to nucleus and cytoplasm characters, four types of haemocytes were recognized: agranular haemocytes, lymphoid haemocyte, large granular and small granular haemocytes. Agranular hamocyte is the main cell type, accounting for 75%. It is agranular with rich organelles in cytoplasm, including mitochondria, golgi body and endoplasmic reticulum. Glycogen deposits were usually found in this cell type. The number of lymphoid haemocyte accounts for 1%-2%. This cell type is agranular and shows a high ratio of nucleus to cytoplasm. A few organelles were found. High electrondense granules with diameters of 0.2-0.5 μm and rich organelles were found in small granular haemocyte. The prop