RESUMEN
Environmental impacts of wastes from large-scale, intensive aquaculture are substantial and can lead to complex ecosystem changes. The application of known and new technologies can capture inorganic nitrogen from water and reduce organic enrichment of sediments. Biological methods, including Integrated Multi-trophic Aquaculture are now gaining interest for increasing in situ removal of nitrogen and other nutrients at sea cage sites. Several studies on biological nitrogen removal through nitrification, denitrification and anaerobic ammonium oxidation (anammox) have been reported and a number of bacterial groups active in this regard have been described. Nevertheless, additional efforts need to be focused on remediation of aquaculture wastewater and marine sediments. Conventional treatment systems have several disadvantages. Development of more efficient reactor systems and a holistic, integrated approach to waste treatment would allow more environmentally balanced aquaculture practices.
Asunto(s)
Acuicultura , Biodegradación Ambiental , Eliminación de Residuos Líquidos/métodos , Nitritos/metabolismo , Nitrógeno/metabolismoRESUMEN
Numerous studies have investigated the reproduction mechanisms in mollusc species at a biochemical and physiological level; few have described these mechanisms at a molecular level, despite great commercial interest in several mollusc species. We investigated genes involved in gonad maturation of the marine scallop Argopecten purpuratus. A cDNA library was made from gonad tissue. After sequence analysis, 418 unique genes were characterized, of these, about 80% were of unknown function. Among the identified sequences, we analyzed the mRNA expression by real-time PCR of 7 genes involved in reproduction mechanisms, either directly: testis-specific serine/threonine-protein kinase (TSSK), vitellogenin (Vg), and spermatogenesis and centriole associated 1 (SCA) or indirectly: calcineurin A (CNA), centrin, RNA-specific adenosine deaminase (ADAR), and cytidine deaminase (CDA). The real-time PCR analyses were conducted on different tissues of mature and immature scallops (testis, ovary, immature gonad, gill, digestive gland and mantle). The genes studied, presented (1) a strong tissue-dependent expression pattern (higher expression in gonad tissues than in all other tissues) and (2) a sex- and maturation-specific expression pattern (except centrin). This is the first time that the expression of specific genes involved in reproduction mechanisms in a marine mollusc has been described at the molecular level.
Asunto(s)
Gametogénesis/genética , Gónadas/crecimiento & desarrollo , Pectinidae/crecimiento & desarrollo , Pectinidae/genética , Maduración Sexual/genética , Adenosina Desaminasa/genética , Animales , Calcineurina/genética , Proteínas de Unión al Calcio/genética , Proteínas Cromosómicas no Histona/genética , Citidina Desaminasa/genética , Femenino , Expresión Génica , Biblioteca de Genes , Masculino , Proteínas Serina-Treonina Quinasas/genética , ARN Mensajero/metabolismo , Proteínas de Unión al ARN , Reproducción/genética , Análisis de Secuencia de ADN , Espermatogénesis/genética , Testículo/enzimología , Vitelogeninas/genéticaRESUMEN
Lysosomes are known centers for sequestration of calcium and a variety of heavy metals in many invertebrate tissues, and as a result of this compartmentalization these organelles perform important detoxification roles in the animals involved. The present investigation uses a centrifugation method to isolate and purify hepatopancreatic lysosomes from the American lobster, Homarus americanus. Purified lysosomal preparations were used to characterize membrane transport mechanisms in these organelles for transferring and sequestering cytoplasmic copper following its absorption across the plasma membrane from dietary constituents. The copper-specific fluorescent dye, Phen Green, was employed to quantify transmembrane fluxes of this metal as has been recently used to investigate copper movements across hepatopancreatic mitochondrial and plasma membranes. Results indicated the presence of a vanadate-sensitive, calcium-stimulated, copper ATPase in the membranes of these organelles that displayed high affinity carrier-mediated transport kinetics and may significantly contribute to organismic copper homeostasis. Together with a putative bafilomycin-sensitive V-ATPase in the membrane of the same organelles, importing hydrogen ions into the organellar interior, this copper ATPase may function as part of a physiological mechanism for precipitate formation between metallic cations and anions. These ionic precipitate complexes may then act as a sink for excess metals and thereby reduce the circulating concentrations of these elements.
Asunto(s)
Cobre/metabolismo , Hepatopáncreas/citología , Hepatopáncreas/metabolismo , Lisosomas/metabolismo , Nephropidae/metabolismo , Animales , Transporte Biológico/efectos de los fármacos , Calcio/farmacología , Fluorescencia , Lisosomas/efectos de los fármacos , Masculino , Modelos Biológicos , Vanadatos/farmacología , Verapamilo/farmacologíaRESUMEN
Mechanisms of copper transport into purified mitochondrial suspensions prepared from the hepatopancreas of the Atlantic lobster Homarus americanus were investigated. Mitochondria were purified by combining methods of differential and Percoll-gradient centrifugation, and copper transport was studied using the copper-sensitive fluorescent dye Phen Green. Copper transport by this mitochondrial preparation was kinetically the sum of saturable and non-saturable transfer components. Addition of 500 micromol x l(-1) Ca2+ or 500 nmol x l(-1) Ruthenium Red abolished the non-saturable copper transport component, significantly (P<0.01) reduced the apparent binding affinity of the saturable transport component, but was without effect (P>0.05) on the apparent maximal transport velocity of the saturable transfer process. The antiport inhibitor diltiazem (500 micromol x l(-1)) acted as a mixed inhibitor of the saturable transport mechanism, but had no effect on the non-saturable component of transfer. These results suggest that the non-saturable copper influx process was probably by way of the well-known Ruthenium-Red-sensitive Ca2+ uniporter and that the saturable transport component was probably due to a combination of both the Na+-dependent, diltiazem-sensitive 1Ca2+/2Na+ antiporter and the Na+-independent, diltiazem-insensitive 1Ca2+/2H+ antiporter. A model is discussed relating these mitochondrial copper uptake processes to the transfer of metal ions across the epithelial brush-border membrane.