Fig 8 - uploaded by Antonio Villalba
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Schematic representation of the steps of P. olseni encapsulation by clam (R. decussatus and R. philippinarum) hemocytes according to the studies of Montes et al. (1995a, b, 1996, 1997). ROS: Reactive oxygen species.
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... sections is much less frequent than in the oyster C. virginica infected by P. marinus (Casas 2002). Montes et al. (1995aMontes et al. ( , b, 1996Montes et al. ( , 1997) clearly demonstrated that P. olseni induced a specific cellular response in clams, R. decussatus and R. philippinarum. The major steps of this immune reaction are sketched in Fig. 8. hemocytes according to the studies of Montes et al. (1995aMontes et al. ( , b, 1996Montes et al. ( , 1997. ROS: Reactive oxygen ...
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... In the early studies, the haemocytes were characterised mainly by morphological and cytochemical criteria, such as the size, nucleus/cytoplasm (N/C) ratio, cytoplasmic complexity and enzyme content (36,37). More recent trends for identifying haemolymph cell types are focused on flow cytometry, tool that allows determining the size and granularity of haemocytes (38). Most studies have classified bivalve haemocytes into two main groups: granulocytes, cells with granules in the cytoplasm and typically a low N/C ratio, and hyalinocytes (or agranulocytes), cells containing few or no granules within the cytoplasm and a higher N/C ratio (19,21,36,39) (Figure 1). ...
Bivalve molluscs stand out for their ecological success and their key role in the functioning of aquatic ecosystems, while also constituting a very valuable commercial resource. Both ecological success and production of bivalves depend on their effective immune defence function, in which haemocytes play a central role acting as both the undertaker of the cellular immunity and supplier of the humoral immunity. Bivalves have different types of haemocytes, which perform different functions. Hence, identification of cell subpopulations and their functional characterisation in immune responses is essential to fully understand the immune system in bivalves. Nowadays, there is not a unified nomenclature that applies to all bivalves. Characterisation of bivalve haemocyte subpopulations is often combined with 1) other multiple parameter assays to determine differences between cell types in immune-related physiological activities, such as phagocytosis, oxidative stress and apoptosis; and 2) immune response to different stressors such as pathogens, temperature, acidification and pollution. This review summarises the major and most recent findings in classification and functional characterisation of the main haemocyte types of bivalve molluscs.
... The mortality for several marine molluscs from parasite infections, particurly apicomplexan have been reported as early as 1900s, for examples the Perkinsus spp. infestations in the clam population of Southern Portugal and North Western Spain [8][9][10], the Nemaptosis sp. infestations in the adductor muscles of Meretrix meretrix from the Arabian Gulf [11], in coastal regions of Korea, Japan and China [12][13][14], for the oyster industry [15][16]; gregarine Nematopsis sp. ...
This study describes the apicomplexa as well as other parasites infecting organs/tissues of the hard clam Meretrix meretrix Linnaeus, from Merambong Shoal, Western Johor Straits, Malaysia. Samples were collected randomly by hand picking, in November and December 2013. Histological techniques were performed, stained using Masson's Trichrome protocol and observed under light microscope. The results showed that gonad and gill were the most infected organs followed by digestive gland, intestine and adductor muscle. No pathology condition was observed in the mantle. Histophatological examination showed that the gregarine, Nematopsis, unidentified coccidian and Perkinsus were found in the gill and gonad, and also in the numerous hemocytes. Other pathological conditions such as bacteria-like inclusion and intracellular bacteria were also observed in the same organs. Further investigations are needed particularly on other molluscs present at the study area. Understanding the morphology and pathology of parasites infecting mollusks are very important for management of the resources.
... In vitro studies have shown that viability, proliferation, virulence-factor expression, and metabolic activities of P. marinus are all affected by temperature (Dungan and Hamilton, 1995; Gauthier and Vasta, 1995; Volety and Chu, 1997; Chu et al., 2003; Soudant et al., 2005; Ford and Chintala, 2006) and by salinity (Burreson et al., 1994; O'Farrell et al., 2000; La Peyre et al., 2006). Although less studied than P. marinus, viability, metabolic activity and proliferation of P. olseni are also influenced by temperature and salinity (Soudant et al., 2005; La Peyre et al., 2006, 2008). Additionally, both temperature and salinity have a marked influence on in vitro zoosporulation of Perkinsus spp. ...
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.
... Schéma hypothétique des étapes du processus de phagocytose (adaptéde Campbell et Reece, 2007;Soudant et al., 2008et Parham, 2009). ...
For fifteen years, summer mortalities have been observed in wild and farmed populations of European abalone, Haliotis tuberculata, along the north French coast. These mortalities are attributed to the bacterial species Vibrio harveyi and occur in sexually mature animals, when the seawater temperature exceeds 17°C.A multifactorial approach to the study of this host-parasite interaction was done during this thesis, in order to specify the intrinsic abalone conditions in vibriosis mortalities, the infectious cycle of V. harveyi in European abalone and the role of temperature in the fulfillment of this infectious cycle, and finally the physiological response of abalone, at cellular and molecular level, when exposed to V. harveyi.The main results showed a differential gene expression between resistant and susceptible abalone during exposure to V. harveyi, indicating the importance of the physiological status of the host, in survival to vibriosis. This hypothesis is supplemented by the susceptibility of sexually immature abalone at 19°C to this disease, usually resistant, and exposed to manipulation stressor. Moreover, the study of the portal of entry and the dynamics of infection by V. harveyi in European abalone revealed a particular tropism of this vibrio pathogen for gill tissues, in the earlier hours of contact, and its invasion into the circulatory system from the first 24 hours of contact. The study of the response of abalone hemocyte and gill metabolism, at the cellular and molecular level, in the earlier hours of contact, shows 1/ a genesis of oxidative stress in gills of susceptible abalone, and 2/ an alteration of hemocyte functions, which may constitute one of the major strategies of virulence in V. harveyi.
... Debido a su trascendencia económica, especialmente en los EE.UU, sumado a su amplia distribución geográfica, esta enfermedad ha sido objeto del mayor esfuerzo investigador entre las enfermedades de moluscos de todo el mundo. Varias revisiones minuciosas de la información disponible sobre esta enfermedad han precedido a la presente (Fisher 1996; VillAlbA et al. 2004; VillAlbA 2008). ...
... Perkinsus olseni is a protozoan parasite affecting commercially important molluscs worldwide and associated with mass mortalities in clam populations, in particular in coastal regions of southern Portugal (Ruano & Cachola 1986;Azevedo 1989b;Villalba 2008) where bivalve harvests account for 86.97% and 99.39% of the weight and number, respectively, of total collections in Portugal (IPI-MAR 2003). Among several bivalve species caught the carpet-shell clam, Ruditapes decussatus L., and the wedge shell clam, Donax (Serrula) trunculus L., constitute important fishing resources because of their high economic value (Ruano & Cachola 1986;Ruano 1997). ...
A aquicultura é uma das atividades agrícolas que mais cresce no mundo, e o Brasil se destaca neste cenário pelo seu grande potencial na produção de organismos aquáticos. O clima tropical, a disponibilidade de recursos hídricos, espécies nativas são alguns dos fatores que favorecem a atividade em nosso país, onde o estudo da aquicultura vem ganhando cada vez mais espaço. Desta forma, a presente obra visa contribuir com o conhecimento aquícola agregando textos das diferentes subáreas da aquicultura. Do cultivo de macroalgas ao potencial de moluscos para aquariofilia; da ranicultura à bioinvasão ocasionada pela aquicultura; da preservação promovida pelos cultivos de pequena escala às inovações tecnológicas para o desenvolvimento aquícola; dos entraves atuais da carcinicultura ao estudo dos organismos associados às ostras. Desejamos uma boa leitura!
Tecnologias em geral como por exemplo a Inteligência Artificial, sempre parece algo do futuro, coisas de filme científico, algo imaterial ou inalcançável para alguns de nós meros mortais. De forma mais simples do que nosso imaginário conduz, essas tecnologias já não fazem parte do futuro na aquicultura e sim do nosso presente. Exemplos claros de como essas tecnologias podem ser ou já são aplicados no setor aquícola são apresentados nesse capítulo, de forma equilibrada entre a generalização, para quem não é da área, mas tem curiosidade e interesse, e a particularização do tema em um nível maior de detalhes, para aqueles que já não querem ficar na superfície da informação. Tudo isso está contido no conceito da indústria 4.0, ou agricultura de precisão onde é feita uma breve contextualização antes dos interessantes exemplos do capítulo. E o mais relevante para as perspectivas atuais dessas tecnologias para o desenvolvimento da aquicultura brasileira, uma discussão do exigente mercado de trabalho e a direção que os técnicos profissionais devem seguir para compor esse grupo interdisciplinar no trabalho que não é mais caracterizado por um indivíduo e sim uma equipe desenvolvedora dos problemas que porventura são demandadas pelas empresas.
This study describes the parasites and pathological condition of infected organ of the green mussel Perna viridis from Merambong Shoal, Western Johor Straits, Malaysia. Samples were collected randomly in November and December 2013. Histopathology techniques using Masson’s Trichrome staining protocol were performed and the thin sections were observed under light microscope. Result showed that gonad was the most infected organ followed by the digestive tubule, adductor muscle, intestine and mantle tissue. The parasites (apicomplexa) such as spore-like Nematopsis, macrogamont-like coccidian, mature oocyst-like coccidian, unidentified coccidian and protozoan were found in the adductor muscle, gonad and mantle. Meanwhile, the pathological conditions were found in all infected organs except the gill, such as particular melanin deposits in cytoplasm, Rickettsia-like or Chlamydiae organism and bacteria-like inclusions. Haemocytic infiltrations were found in the surrounding connective tissues of all infected organs. However, these light infections are not causing morbidity and mortalityof the green mussel P.viridis. This study provides baseline information on health profile of the green mussel P.viridis. Further investigations are needed particularly on parasite species identification and their ecology. Understanding of the morphology and pathology of parasites infecting mollusks are very important for management of the resources.
