The Histopathology of the Infection of Tilapia rendalli and Hypostomus regani (Osteichthyes) by Lasidium Larvae of Anodontites trapesialis (Mollusca, Bivalvia)

It is described the histopathology of the infection of Tilapia rendalli (Osteichthyes, Perciformes, Cichlidae) and Hypostomus regani (Osteichthyes, Siluriformes, Loricariidae) by lasidium larvae of Anodontites trapesialis (Mollusca, Bivalvia, Mycetopodidae). The larvae were encysted within the epidermis of the host, being surrounded by a thin hyaline membrane, 3-6 µm thick, of parasite origin. A proliferative host cell reaction did not occur. The histopathology of the infection shows that the lesions induced by the parasites are minimal. However, the numerous small lesions produced by the release of the larvae may provide optimal conditions for the infection by opportunistic pathogens, namely fungus, which may eventually cause the death of the host.

The influence of hydrocortisone on cellular defence mechanisms of Biomphalaria glabrata

Since the internal defense system of mollusks consists of cellular and humoral mechanisms, we examined the role of hydrocortisone in mollusks defense cells and the influence of this steroid on the development of Schistosoma mansoni in its intermediary host. Hydrocortisone had an immunosuppressive action in Biomphalaria glabrata, as reflected in the reduced number of defense cells and the altered cell physiology. Histopathological analysis showed that hydrocortisone facilitated the intramolluscan development of S. mansoni, by reducing the extent of the inflammatory response, seen as a greater number of viable sporocysts with no surrounding hemocytes.

Response of the Pacific oyster Crassostrea gigas, Thunberg 1793, to pesticide exposure under experimental conditions.

Pesticide run-off into the ocean represents a potential threat to marine organisms, especially bivalves living in coastal environments. However, little is known about the effects of environmentally relevant concentrations of pesticides at the individual level. In this study, the suppression subtractive hybridisation technique was used to discover the main physiological function affected by a cocktail of three pesticides (lindane, metolachlor and carbofuran) in the Pacific oyster Crassostrea gigas. Two oyster populations exposed to different pollution levels in the wild were investigated. The pesticide concentrations used to induce stress were close to those found in the wild. In a time course experiment, the expression of three genes implicated in iron metabolism and oxidative stress as well as that of two ubiquitous stress proteins was examined. No clear regulation of gene or protein expression was found, potentially due to a low-dose effect. However, we detected a strong site- and organ-specific response to the pesticides. This study thus (1) provides insight into bivalve responses to pesticide pollution at the level of the transcriptome, which is the first level of response for organisms facing pollution, and (2) raises interesting questions concerning the importance of the sites and organs studied in the toxicogenomic field.

Angiostrongylus costaricensis and experimental infection of Sarasinula marginata II: elimination routes

Angiostrongylus costaricensis intermediate hosts are terrestrial mollusks mostly belonging to the Veronicellidae family. In the present investigation we focused on the mechanisms of larval expulsion from Sarasinula marginata infected with A. costaricensis. Twenty-five mollusks were individually infected with 5000 L1 and sacrificed at 30 min and 1, 2, 4, 6, and 8 h post-infection and at days 1, 2, 4, 5, 6, 8, 10, 11, 12, 14, 15, 16, 20, 21, 22, 25, 26, 28, and 30 post-infection; the mollusks were then fixed and stained. Diverse organs involved throughout the course of the migratory routes of larvae from oral penetration on were specified and the mechanisms of larval access to the fibromuscular layer through the kidney, rectum, and vascular system were defined. The elimination of L3, derived from oral and/or cutaneous infections, appears to depend on granulomas located close to the excretory ducts of mucous cells.

Activity of Euphorbia splendens var. hislopii N.E.B. (Euphorbiaceae) latex against Lymnaea columella (Say, 1817) (Pulmonata: Lymnaeidae), intermediate host of Fasciola hepatica, Linnaeus, 1758 (Trematoda: Fasciolidae). 2: limited field-testing

The molluscicidal evaluation of Euphorbia splendens var. hislopii (Crown of thorns) against Lymnaea columella snails, intermediate host of Fasciola hepatica, in irrigation ditches of the Pisciculture Station at Universidade Federal Rural do Rio de Janeiro, was studied under limited field conditions. An aqueous solution of the latex at 5 mg/l was tested in two irrigation ditches (experimental and control ditches), after initial sampling of the snail population present. Twenty-four hours after application of the product, it was verified that 97.4% of free L. columella snails and 100% of snails of the same species captive in cages and used as sentinels at three points equidistant from the application site in the experimental ditch, died. For Biomphalaria tenagophila and Melanoides tuberculata snails, present in the experimental ditch, the mortality was 100%, for the species Pomacea spp. the mortality was 40%. No mortality was verified in the free mollusks, or in the sentinels in the ditch used as control. E. splendens var. hislopii latex is thus an efficient natural molluscicide, which may be used as an alternative control agent against L. columella.

Primary culture of the region of the amebocyte-producing organ of the snail Biomphalaria glabrata, the intermediate host of Schistosoma mansoni

Biomphalaria glabrata snails are major hosts for the digenetic trematoda Schistosoma mansoni, the causative agent of human schistosomiasis. The success or failure of the infection will be dependent on the mobilization of the molluskan internal defense system, where a major role will be played by circulating hemocytes produced by the APO (amebocyte-producing organ) of the snail. In this report, the primary culture of the APO region of B. glabrata was obtained for the first time, as well as a control culture of the ovotestis. Three different cell populations migrated easily from the explants in culture, with no need of any dispersion agent. The cells grew in suspension at an incubation temperature of 15ºC and the cultures were maintained viable for up to two weeks. Two of these cell populations obtained resembled cell types known to be present in the hemolymph of Biomphalaria. The availability of APO cells in culture may contribute to a better understanding of the internal defense in mollusks, in general, as well as the specific response of B. glabrata to S. mansoni infection.

Proteolytic activity in the adult and larval stages of the human roundworm parasite Angiostrongylus costaricensis

Angiostrongylus costaricensis is a nematode that causes abdominal angiostrongyliasis, a widespread human parasitism in Latin America. This study aimed to characterize the protease profiles of different developmental stages of this helminth. First-stage larvae (L1) were obtained from the faeces of infected Sigmodon hispidus rodents and third-stage larvae (L3) were collected from mollusks Biomphalaria glabrata previously infected with L1. Adult worms were recovered from rodent mesenteric arteries. Protein extraction was performed after repeated freeze-thaw cycles followed by maceration of the nematodes in 40 mM Tris base. Proteolysis of gelatin was observed by zymography and found only in the larval stages. In L3, the gelatinolytic activity was effectively inhibited by orthophenanthroline, indicating the involvement of metalloproteases. The mechanistic class of the gelatinases from L1 could not be precisely determined using traditional class-specific inhibitors. Adult worm extracts were able to hydrolyze haemoglobin in solution, although no activity was observed by zymography. This haemoglobinolytic activity was ascribed to aspartic proteases following its effective inhibition by pepstatin, which also inhibited the haemoglobinolytic activity of L1 and L3 extracts. The characterization of protease expression throughout the A. costaricensis life cycle may reveal key factors influencing the process of parasitic infection and thus foster our understanding of the disease pathogenesis.

Levels of PSP toxins in bivalves exposed to natural blooms of Alexandrium minutum in Catalan harbours

The development, validation, comparison and evaluation of analytical methods for marine toxins rely on the availability of toxic material. Within the project JACUMAR PSP, our interest is mainly focused on autochthonous bivalve species with the toxic profile of Alexandrium minutum, since this is the principal species involved regionally in PSP outbreaks. Mussels and oysters were exposed during few days in the harbor of Vilanova i la Geltrú, to blooms reaching a maximum A. minutum concentration of 200,000 cells L-1 in 2008, and 40,000 and 800,000 cells L-1, in 2009. Mussels, oysters and clams were exposed to one bloom of 22,000 cells L-1 in the harbor of Cambrils in 2009. In all situations higher toxic levels analyzed by HPLC-FD with postcolumn oxidation were observed in mussels (i.e. 1,200-2,500 μg eq. STX kg-1) than in oysters (i.e. 60-800 μg eq. STX kg-1) exposed to the same bloom. Blooms with higher concentrations of A. minutum did not correspond to higher levels of PSP toxins in bivalves. These differences may be explained by differences in A. minutum population dynamics, toxin production or in the physiological state or behaviour of shellfish. These results confirm that mussels concentrate more PSP toxins from A. minutum than oysters and clams.

Filogeografia de Brachidontes puniceus (GMELIN, 1791) no Arquipelago de Cabo Verde

A espécie Brachidontes puniceus (Gmelin, 1791) é um bivalve pertencente a família Mytilidae, habita fissuras rochosas e lagoas de marés. Trata-se de uma espécie que tem uma distribuição restrita à costa ocidental africana e arquipélago de Cabo Verde (desde a Mauritânia até Angola) existindo um registo incerto na ilha de Natal. Tendo como objectivo fazer uma análise filogeográfica baseada em sequências parciais do gene mitocondrial citocromo oxidase subunidade I (cox1), amostraram-se as ilhas de Santo Antão, São Vicente, Santa Luzia, São Nicolau, Sal, Boavista, Maio e Santiago. Foram sequenciadas 115 amostras obtendo um total de 37 haplótipos, sendo 6 destes partilhados entre ilhas. A rede de haplótipos apresenta uma configuração em estrela, com um haplótipo central presente em todas as ilhas, rodeado por haplótipos raros e pouco distintos entre si. A variabilidade haplotípica detectada foi alta (65-89%) e a variabilidade nucleotídica baixa (0.14-0.35%). A variância genética entre pares de ilhas não foi estatisticamente significativa, o que indica que não há diferenças genéticas entre as ilhas (P>0.69). Os valores significativos dos testes de neutralidade (R2 = 0.0169, D* = -2.54), as análises de variância molecular e a distribuição em estrela dos haplótipos sugerem uma expansão populacional rápida de B. puniceus em Cabo Verde. O desenvolvimento planctotrófico das larvas e o tempo que estas passam na coluna de água, constitui um factor de dispersão para a espécie, sendo provavelmente o factor chave que impede a diferenciação genética entre ilhas.

A estação arqueológica de Salamansa (ilha de São Vicente, República de Cabo Verde)

Apresentam‑se os principais resultados obtidos nas duas missões arqueológicas patrocinadas pelo Centro Português de Actividades Subaquáticas (CPAS) à ilha de São Vicente (República de Cabo Verde), em 1998 e em 2005. Em 1998, confirmou‑se o efectivo interesse arqueológico do sítio, localizado sobre o mar, em local abrigado da vasta baía de Salamansa, situada na parte setentrional da ilha, tendo‑se registado a respectiva extensão e estratigrafia e procedido à colheita de amostras para datação. Embora os resultados dessa campanha tivessem sido publicados, indicando estação de carácter habitacional, revelada pela notável acumulação de conchas, acompanhada de abundantes fragmentos de cerâmicas manuais, de produção africana, mantinha‑se indefinida a sua verdadeira natureza. Impunha‑se, assim, proceder à escavação integral da área que ainda subsistia da estação — sujeita de forma contínua a forte erosão marinha — bem como à colheita de novos materiais para datação, de forma a confirmar as conclusões preliminares anteriormente obtidas, objectivos que se concretizaram em 2005. Deste modo, foi possível concluir que, contrariando a hipótese, de início considerada, de poder corresponder a um testemunho da ocupação da ilha em época anterior à chegada dos Portugueses — hipótese que já as primeiras datas de radiocarbono contradiziam — se trata de um sítio onde uma unidade habitacional construída por muros de pedra seca, de planta ortogonal, revela inspiração europeia, aliás sublinhada pelos materiais exumados, onde estão representados produtos com tal origem, como cachimbos de caulino, vidros, faianças portuguesas, e projécteis de armas de fogo, a par de objectos oriundos do Extremo Oriente, num quadro dominado pelas produções cerâmicas africanas. Esta situação evidencia um estabelecimento cuja ocupação se centrou no século XVII, conforme indicam os materiais recolhidos e os resultados das datações obtidas, francamente aberto aos contactos de longa distância, apesar do isolamento do local escolhido. Os restos faunísticos recolhidos, com a presença deburro e de boi, sugerem um estacionamento sedentário, sendo a alimentação assegurada essencialmente pela captura de tartarugas, pela pesca e pela recolecção de moluscos marinhos (especialmente grandes lapas) e complementada pelo consumo de cabra, que poderia ser doméstica ou caçada, dado o estado selvagem a que retornou ali esta espécie. na última parte do trabalho, discutem‑se as diversas hipóteses susceptíveis de explicar esta estação — desde um entreposto comercial relacionado com a exploração agro‑pecuária da ilha de Santo Antão, passando por pequeno estabelecimento especializado de apoio à navegação, com a produção de carne salgada de tartaruga, até ter constituído refúgio relacionado com a intensa pirataria vigente à época no arquipélago, tendo presente os elementos históricos conhecidos, que, aliás, indicam que o início da ocupação permanente de São Vicente só se produziu a partir da segunda década do século XIX. Seja como for, a forte componente cultural africana revelada pelo espólio destes primeiros ocupantes da ilha expressa‑se também pelos rituais que terão envolvido o abandono do estabelecimento, com o enterramento de dois vasos emborcados sob o chão da habitação explorada, e a deposição de uma pequena taça, nas mesmas circunstâncias, junto à parede da mesma, do lado externo.

La paleolaguna de Otuma como potencial para la reconstrucción de las condiciones paleoceanográficas de Pisco.

Se describe la geomorfología del relieve de la paleolaguna de Otuma y se evalúa la preservación de sus registros calcáreos y su potencialidad para la reconstrucción paleoceanográfica y paleoecológica. Un pequeño acantilado marino y una plataforma de abrasión de suave pendiente con predominancia de arena y grava, sugieren un fondo submareal somero de 3,5 m de profundidad a 80 m de distancia de la orilla. La distribución de los registros calcáreos in situ, sobre el fondo de la paleolaguna sugiere un patrón de zonación ecológica. La abundancia de Argopecten purpuratus en los conchales demuestra su dominancia y la presencia de un antiguo y muy productivo banco natural de concha de abanico con una estructura de tallas 40 -140 mm. La preservación de las conchas permitió el análisis de sus anillos o líneas de crecimiento y la reconstruccion de sus ritmos y patrones de crecimiento que son valiosos para la reconstrucción de la variabilidad ambiental.

Chemical labelling of oyster shells used for time-calibrated high-resolution Mg/Ca ratios: A tool for estimation of past seasonal temperature variations

The geochemical compositions of biogenic carbonates are increasingly used for palaeoenvironmental reconstructions. The skeletal delta O-18 temperature relationship is dependent on water salinity, so many recent studies have focused on the Mg/Ca and Sr/Ca ratios because those ratios in water do not change significantly on short time scales. Thus, those elemental ratios are considered to be good palaeotemperature proxies in many biominerals, although their use remains ambiguous in bivalve shells. Here, we present the high-resolution Mg/Ca ratios of two modern species of juvenile and adult oyster shells, Crassostrea gigas and Ostrea edulis. These specimens were grown in controlled conditions for over one year in two different locations. In situ monthly Mn-marking of the shells has been used for day calibration. The daily Mg/Ca.ratios in the shell have been measured with an electron microprobe. The high frequency Mg/Ca variation of all specimens displays good synchronism with lunar cycles, suggesting that tides strongly influence the incorporation of Mg/Ca into the shells. Highly significant correlation coefficients (0.70<R<0.83, p<0.0001) between the Mg/Ca ratios and the seawater temperature are obtained only for juvenile C. gigas samples, while metabolic control of Mg/Ca incorporation and lower shell growth rates preclude the use of the Mg/Ca ratio in adult shells as a palaeothermometer. Data from three juvenile C. gigas shells from the two study sites are selected to establish a relationship: T = 3.77Mg/Ca + 1.88, where T is in degrees C and Mg/Ca in mmol/mol. (c) 2012 Elsevier B.V. All rights reserved.

Biodiversidad marina en la isla Lobos de Tierra, Perú. 2011

Entre el 29 de setiembre y 3 de octubre 2011, se determinó la estructura de las comunidades, en términos de abundancia relativa, riqueza y diversidad y relación con el medio ambiente de la isla Lobos de Tierra (noreste de isla Rata, El Ñopo y La Grama). En los cálculos de diversidad específi ca se usó métodos uni y multivariados para hacer comparaciones en los lugares estudiados. En la zona mesolitoral se registró alta riqueza específi ca asociada a comunidades de fondos duros destacando el noreste de isla Rata con 58 especies. El grupo dominante fue moluscos en todas las zonas de estudio, sobresaliendo Tegula corvus y Acanthopleura echinata con mayores niveles de abundancia (296 a 412 ind.m-2). El índice de diversidad (H’) promedio por estación mostró valores >1,5 bits/ind en todas las zonas, con valores de dominancia y equitatividad <1,0. En el submareal, la riqueza fue de 124 especies. Los crustáceos y poliquetos tuvieron la mayor riqueza de especies y densidad. Los principales representantes fueron Gammarus sp. (26.607 ind.m-2), Spionidae (2.227 ind.m-2) y Diopatra rhizoicola (2.073 ind.m-2). El índice de diversidad promedio fue 2,2 bits, valor considerado de alta diversidad. La fauna íctica submareal estuvo conformada por 16 especies, destacando los géneros Auchenionchus y Labrisomus y en el intermareal se registraron 7 especies destacando Tomicodon chilensis. Se detectaron 24 especies de macroalgas: Rhodophyta (16 especies), Chlorophyta (5 especies) y Phaeophyta (3 especies), predominó Caulerpa fi liformis (submareal) y Gymnogongrus furcellatus (intermareal).

Evaluación poblacional de Chondracanthus chamissoi (C. Agardh 1820) en las bahías de Pisco y Paracas, Otoño 2010.

Entre mayo y junio 2010, se desarrolló la evaluación poblacional de la macroalga Chondracanthus chamissoi “yuyo” de las praderas en las bahías de Pisco y Paracas. Las biomasas medias fluctuaron entre 2,2 y 67,0 g.m-2, con promedio de 43,6 g.m-2. Se estimó una biomasa total de 211,96 toneladas (±56,8%); de los cuales 179,74 t correspondieron a Atenas; 30,1 t a Puerto Nuevo y 2,1 t a Playa Lobería. El sustrato de fijación estuvo compuesto, principalmente, por piedras, conchuela y arena media. En las praderas de Atenas ocupó la mayor parte del área evaluada, en las praderas de Puerto Nuevo y Playa Lobería se encontraron reducidas, respecto al 2007. Se encontró ejemplares entre 1 y 25 cm de longitud. El peso total individual varió de 0,1 a 94,6 g. Se registró biodiversidad asociada conformada por moluscos. Las condiciones oceanográficas se registraron normales, lo que permite suponer que la disminución poblacional respondería a las actividades de extracción.

A preliminary catalogue of natural substances of opistobranch molluscs from Western Mediterranean and near Atlantic

A list of opisthobranch molluscs species from the western Mediterranean and nearby Atlantic is presented. These species have natural products that are of interest because of their chemical structure, origin and/or function in benthic ecosystems. This review contains data on the origin and activity of these molecules, collection sites of the animals, and their bibliographic references. A discussion of these subjects is also included.