2,212 research outputs found
Molecular characterisation of pelagic larvae and molecular biology of hydrothermal vent organisms
No full text
Genetics and marine pollution (review)
No full textThe development of cytogenetic methods applied to cells and tissues of marine invertebrates has been hampered by (1) a lack of in vitro cell lines, (2) inadequate karyotypic information (partly as a result of too few workers chasing too many organisms), and (3) the failure of their chromosomes to band satisfactorily. Compared to mammalian cytogenetics, our knowledge of marine invertebrates lags behind by several decades. With the current concern about mutagens in the marine environment, and the recognition that the cells of marine species have sensitivities to DNA-damaging agents similar to those of higher organisms, there is a need for methods which can be used (a) in environmental monitoring and (b) to screen potentially harmful substances in the laboratory. In the absence of in vitro cell lines, embryos and larvae have been used to provide a supply of dividing cells for mutation studies, although the advent of molecular methods has now brought with it the means to detect DNA damage without any need for the cells to be in a dividing state. Moreover, the use of FISH (Fluorescence In Situ Hybridisation) now makes it possible to study numerical and structural chromosomal aberrations with far greater accuracy than was previously possible. A new marine genotoxicity assay is described, based on the embryos and larvae of a tube-dwelling polychaete worm (Pomatoceros lamarkii), suitable for both laboratory studies and field monitoring. This new Pomatoceros assay provides, at the same time, a useful model for studying the consequences of adult exposure on the offspring. A novel application of marine cytogenetic research is the study of the evolutionary adaptations of invertebrates living in naturally polluted extreme environments viz. deep sea hydrothermal vents, which are typified by high levels of toxic heavy metals and radionuclides, substances known to inflict damage to DNA. Given these new methodological and conceptual advances, it is predicted that our understanding of the role played by mutation in the marine environment, both in an evolutionary and toxicological context, will increase dramatically over the next decade
Temperature/pressure tolerance of the first larval stage of Mirocaris fortunata from Lucky Strike hydrothermal vent field
No full textBackground and induced levels of DNA damage in Pacific deep-sea vent polychaetes: the case for avoidance
No full textChromosomal and nuclear characteristics of deep-sea hydrothermal-vent organisms: correlates of increased growth rate
No full textMarine invertebrate eco-genotoxicology: a methodological overview
No full textThe last 25 years have seen major advances in the field of mammalian genotoxicology, particularly with the advent of molecular methods, some of which have spilled over into the relatively new field of eco-genotoxicology, which aims to evaluate the impact of contaminants on the natural biota. Unlike mammalian genotoxicology, where the focus is centred on a limited number of model species, efforts in the marine field have generally lacked coordination and focus, with the result that progress has been somewhat slow and fragmented. However, it is recognized that at the DNA and chromosome levels, marine invertebrates express qualitatively similar types of induced damage to that found in higher organisms (e.g. point mutations, strand breaks and chromosomal aberrations). Given that many of these species (bivalve molluscs, crustaceans, polychaete worms, etc.) are linked directly or indirectly to the human food chain, this is an important reason why one should be concerned about their exposure to environmental mutagens and carcinogens, particularly as many of these organisms have the capacity to (i) transform these agents to biologically active metabolites and (ii) accumulate toxicants in their cells and tissues at concentrations several orders of magnitude above that found in the environment. This review covers the advantages and limitations of those cytogenetic and molecular assays that have been used to address the question of genotoxicity in the cells and early life stages of selected marine invertebrate species. It concludes with the recommendation for the adoption of standardized test procedures, leading to a tiered approach in future eco-genotoxicity testing
NVH characteristics of air-assisted direct injected (DI) spark ignition four-stroke engines
No full textMolecular and morphological identification of settlement-stage vent mussel larvae, Bathymodiolus azoricus (Bivalvia: Mytilidae), preserved in situ at active vent fields on the Mid-Atlantic Ridge
No full textThis paper describes the first successful attempt to trap and identify the larvae of a deep-sea vent organism using a combination of sediment traps and molecular analysis. During the European Union-funded MARVEL cruise in August and September 1997, sediment traps containing a high-salt DNA preservative were deployed around active black smoker chimneys on the newly discovered Rainbow vent field in an attempt to collect larval stages of the dominant vent bivalve Bathymodiolus azoricus. A total of 2,055 shelled mussel larvae was collected within a 2-week period, all of which were of identical size and shell morphology that indicated that they were at the settlement, prodissoconch II stage. Scanning electron microscopy of the shell hinge indicated that they belonged to the family Mytilidae, but it required molecular analysis to confirm their species identity. Polymerase chain reaction (PCR) amplification of the ITS2 region was performed on a subset of the larvae, and the resulting PCR products were cut with diagnostic restriction endonucleases to allow comparison with a DNA database based on adult specimens. The DNA restriction patterns typifying the Rainbow larvae were identical to those of adult B. azoricus from the Menez Gwen, Lucky Strike, and Rainbow vent sites and were significantly different from those that typified Bathymodiolus thermophilus (Pacific) and Bathymodiolus puteoserpentis (Snake Pit vent field on the Mid-Atlantic Ridge), which clearly points to the Rainbow larvae having their origin on that part of the ridge close to the Azores. These findings point to the value of sediment traps as a way to study the temporal and spatial aspects of larval settlement in deep-sea hydrothermal vent environments
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