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Motility is an unreliable and unwieldly criterion for recognizing living zooplankton. Published accounts of the use of Neutral Red stain for live/dead differentiation prescribe sample preservation in formalin after colour intensification by acidification. However, Neutral Red is most soluble at these low (<6.8) pH values and it leaches from the material, thereby limiting the effective storage time. At pH higher than 8.0, Neutral Red is much less soluble, and we find that it can be ‘locked’ into the material by preservation in alkaline (pH 9.0) formalin. Under these conditions the stain is colourless but the intense magenta colour can be restored when required by acidification with acetic acid. This small modification greatly enhances the value of the vital staining technique, particularly when handling large numbers of samples or when working away from the laboratory. 相似文献
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Mark Coughlan Zsuzsanna TÓth Katrien J. J. Van Landeghem Stephen Mccarron Andrew J. Wheeler 《第四纪科学杂志》2020,35(7):907-919
The Wicklow Trough is one of several Irish Sea bathymetric deeps, yet unusually isolated from the main depression, the Western Trough. Its formation has been described as proglacial or subglacial, linked to the Irish Sea Ice Stream (ISIS) during the Last Glacial Maximum. The evolution of the Wicklow Trough and neighbouring deeps, therefore, help us to understand ISIS dynamics, when it was the main ice stream draining the former British–Irish Ice Sheet. The morphology and sub-seabed stratigraphy of the 18 km long and 2 km wide Wicklow Trough is described here from new multibeam echosounder data, 60 km of sparker seismic profiles and five sediment cores. At a maximum water depth of 82 m, the deep consists of four overdeepened sections. The heterogeneous glacial sediments in the Trough overlay bedrock, with indications of flank mass-wasting and subglacial bedforms on its floor. The evidence strongly suggests that the Wicklow Trough is a tunnel valley formed by time-transgressive erosional processes, with pressurised meltwater as the dominant agent during gradual or slow ice sheet retreat. Its location may be fault-controlled, and the northern end of the Wicklow Trough could mark a transition from rapid to slow grounded ice margin retreat, which could be tested with modelling. 相似文献
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Detecting genotoxicity using the Comet assay following chronic exposure of Manila clam Tapes semidecussatus to polluted estuarine sediments 总被引：1，自引：0，他引：1
Coughlan BM Hartl MG O'Reilly SJ Sheehan D Morthersill C van Pelt FN O'Halloran J O'Brien NM 《Marine pollution bulletin》2002,44(12):1359-1365
Sediments frequently cause damage to biota due to the accumulation of toxic compounds and the bioavailability of sediment-bound contaminants. Damage can be assessed using biomarkers, such as the degree of genotoxic impact following in vivo exposure to pollutants. Genotoxic damage, expressed as single-strand DNA breaks, was measured in cells isolated from haemolymph, gill and digestive gland from the clam Tapes semidecussatus, using the single cell gel electrophoresis (Comet assay). Clams were exposed for three weeks to sediment samples collected from a polluted site and a ‘clean’ reference site.
The level of DNA damage was assessed using an image analysis package and expressed as Tail Moment. Throughout the study, significant differences in DNA damage were recorded for each tissue type between clams exposed to the two sediment samples. We conclude that the Comet assay is a useful tool for the detection of DNA damage in clams chronically exposed to polluted sediments. 相似文献
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Hartl MG Coughlan BM Sheehan D Mothersill C van Pelt FN O'Reilly SJ Heffron JJ O'Halloran J O'Brien NM 《Marine environmental research》2004,57(4):295-310
We explore the use of the clam Tapes semidecussatus Reeves 1864 as an indicator for the presence of potentially genotoxic substances in estuarine sediments. The limitations associated with the interpretation of Comet assay data (expressed as % DNA in tail) in terms of clam reproductive state, size (age) and thermal exposure history following laboratory acclimation are discussed. Hatchery-reared clams, subjected to ambient temperature fluctuations during growth, were exposed in vivo under laboratory conditions for three weeks to sediment samples collected from a polluted site and a "clean" reference site. The DNA damage observed in haemocytes, gill and digestive gland cells was significantly higher in animals exposed to contaminated sediment compared to those exposed to sediment from the reference site. The extent of DNA damage recorded was not correlated with size (age). Spawning was not observed during the experiment. Nevertheless, clams with well-developed gonads showed a statistically higher degree of DNA damage in gill and digestive gland cells- but not haemocytes, demonstrating an increased sensitivity to potential genotoxic compounds, possibly caused by impaired DNA repair capacity due to reproductive activity. Furthermore, the degree of DNA damage in clams exposed to contaminated sediments was higher in autumn and winter compared to spring and summer, suggesting an effect of seasonal priming. 相似文献
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Matthias Fleischer Ayobami Abegunrin Daniel A. Hepp Stefan Kreiter Mark Coughlan Tobias Mörz 《Boreas: An International Journal of Quaternary Research》2023,52(1):78-98
A detailed stratigraphic and geotechnical investigation of the uppermost 50 m below the sea floor was carried out for parts of the German North Sea sector using combined information from shallow seismic reflection surveys, 50-m-long sediment cores and cone penetration tests covering an area of ~150 km2. While most recent studies concentrate on unusual features such as buried tunnel- or river-valleys, this study focused on the less well understood, regionally dominant sand units deposited after the retreat of the last glaciers in this region. We identified two sandy units which dominate the late- to post-Saalian geology: (i) the Upper Fluvial Member, believed to be derived from deposition of the Weser, Ems and Elbe palaeorivers as well as other tributaries of the Elbe Palaeovalley in the NE during the Saalian; and (ii) the Aeolian Member, which correlates with periglacial deposits of Weichselian age. Additionally, a Saalian Buried Valley Member believed to comprise fluvial deposit was also identified. Key stratigraphic units within the uppermost 50 m below the sea floor were also identified and mapped. Detailed geotechnical properties were obtained for each of the individual stratigraphic units. The regional extent of the Aeolian and Upper Fluvial Members was documented in the region west of the Elbe Palaeovalley and south of the Dogger Bank, where their geotechnical properties are important for foundation design. In conclusion, the study complements the established regional geotechno-stratigraphy and offers new and detailed publically accessible information beneficial for offshore wind farm development within the region. 相似文献
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B.M. Coughlan G.A. Moroney F.N.A.M. van Pelt N.M. O&#x;Brien J. Davenport J. O&#x;Halloran 《Marine pollution bulletin》2009,58(11):1680-1684
This study investigated the internal osmotic regulatory capabilities of the Manila clam (Ruditapes philippinarum) following in vivo exposure to a range of salinities. A second objective was to measure the health status of the Manila clam following exposure to different salinities using the neutral red retention (NRR) assay, and to compare results using a range of physiological saline solutions (PSS). On exposure to seawater of differing salinities, the Manila clam followed a pattern of an osmoconformer, although they seemed to partially regulate their circulatory haemolytic fluids to be hyperosmotic to the surrounding aqueous environment. Significant differences were found when different PSS were used, emphasizing the importance of using a suitable PSS to reduce additional osmotic stress. Using PSS in the NRR assay that do not exert additional damage to lysosomal membrane integrity will help to more accurately quantify the effects of exposure to pollutants on the organism(s) under investigation. 相似文献
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B. M. Coughlan M. G. J. Hartl S. J. O&#x;Reilly D. Sheehan C. Morthersill F. N. A. M. van Pelt J. O&#x;Halloran N. M. O&#x;Brien 《Marine pollution bulletin》2002,44(12)
Sediments frequently cause damage to biota due to the accumulation of toxic compounds and the bioavailability of sediment-bound contaminants. Damage can be assessed using biomarkers, such as the degree of genotoxic impact following in vivo exposure to pollutants. Genotoxic damage, expressed as single-strand DNA breaks, was measured in cells isolated from haemolymph, gill and digestive gland from the clam Tapes semidecussatus, using the single cell gel electrophoresis (Comet assay). Clams were exposed for three weeks to sediment samples collected from a polluted site and a ‘clean’ reference site.The level of DNA damage was assessed using an image analysis package and expressed as Tail Moment. Throughout the study, significant differences in DNA damage were recorded for each tissue type between clams exposed to the two sediment samples. We conclude that the Comet assay is a useful tool for the detection of DNA damage in clams chronically exposed to polluted sediments. 相似文献
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The sampler consists of a readily interchangeable nylon-mesh sleeve mounted on the suction of a submersible pump. The unit is compact and robust, with the mesh totally protected from external damage. Although designed primarily for use in the intakes and outfalls of power stations, this sampler and the variants described could find more general application. The incorporation of a submersible pump circumvents both the suction lift restriction and the problems associated with plankton travel through long lengths of hose that are inherent in previous designs. Less than 3% of the members of estuarine/inshore zooplankton so collected showed damage or had died within 48 hours of capture. 相似文献