Low concentrations of methaemoglobin in marine fishes of the Great Barrier Reef, Australia

1997 ◽  
Vol 48 (4) ◽  
pp. 303 ◽  
Author(s):  
Rufus M. G. Wells ◽  
John Baldwin ◽  
Roger S. Seymour
Keyword(s):  
Great Barrier Reef ◽  
Marine Fish ◽  
High Water ◽  
Barrier Reef ◽  
Multiple Wavelength ◽  
Low Concentrations ◽  
Derivative Method ◽  
In Captivity ◽  
Total Haemoglobin ◽  
High Concentrations

Concentrations of methaemoglobin (the oxidized non-functional ferric form of haemoglobin) in the blood of marine fish are poorly documented. Although high concentrations have been reported for fish maintained in captivity, baseline values for wild populations are unknown. Two techniques, the cyanide derivative method and the multiple wavelength method, were used to determine methaemoglobin concentrations in blood samples from 25 species of marine teleosts and elasmobranchs captured on the Australian Great Barrier Reef. Although methaemoglobin generally accounted for less than 2% of total haemoglobin, systematic errors occurred when these two standard methods, developed for mammalian blood, were applied to the blood of some fish species. Most problems arose from reactions of various blood components with the reagents used in the cyanide derivative method. Consequently, the multiple wavelength method generally was more reliable for estimating methaemoglobin in the blood of marine fish. The low methaemoglobin concentrations in fish studied on the Great Barrier Reef indicate high water quality and healthy physiological condition.

scholarly journals Cross-shelf distribution patterns of tropical juvenile cephalopods sampled with light-traps

1995 ◽  
Vol 46 (4) ◽  
pp. 707 ◽  
Author(s):  
NA Moltschaniwskyj ◽  
PJ Doherty
Keyword(s):  
Great Barrier Reef ◽  
Distribution Patterns ◽  
Present Knowledge ◽  
Outer Shelf ◽  
Barrier Reef ◽  
Light Traps ◽  
Coral Sea ◽  
Reef Environments ◽  
High Concentrations ◽  
Abundant Genus

This paper describes the cephalopod genera caught with light-traps at different locations and depths in the waters of the central Great Barrier Reef (GBR). Multiple stations were sampled in four locations: (I) the coastal GBR Lagoon, (2) inter-reef passages (Magnetic and Palm), (3) near-reef environments (Keeper, Helix, Faraday and Myrmidon) ranging from mid- to outer-shelf locations, and (4) the Coral Sea. A total of 13 cephalopod genera was caught from monthly cruises conducted from October to January of 1990-91 and 1991-92. Octopus, the most abundant juvenile cephalopod, was present in relatively high numbers at all shelf locations; few were caught in the Coral Sea. Photololigo, the most abundant squid, was rarely caught outside the GBR Lagoon. In contrast, Sthenoteuthis, the second most abundant squid, was caught at all locations. Deep samples from most locations were dominated by Octopus. Abralia was found only near the bottom of the GBR Lagoon; in contrast, Euprymna, the fourth most abundant genus, was collected only at the surface. Cephalopod communities from the GBR Lagoon had higher abundances of Octopus, Photololigo and Abralia compared with communities from the three other areas. Reef passages and reef locations shared similar communities, with the squid component dominated by Sthenoteuthis. Very low numbers of cephalopods were caught in the Coral Sea by light attraction. High concentrations of cephalopods detected in the middle of the GBR Lagoon are consistent with present knowledge about oceanographic processes over this shelf.

Effect of terrestrial and marine humics on copper speciation in an estuary in the Great Barrier Reef Lagoon

1988 ◽  
Vol 39 (1) ◽  
pp. 19 ◽  
Author(s):  
GB Jones ◽  
FG Thomas
Keyword(s):  
Great Barrier Reef ◽  
Humic Substances ◽  
Coastal Waters ◽  
River Estuary ◽  
Barrier Reef ◽  
Wet Season ◽  
Reef Lagoon ◽  
Copper Speciation ◽  
High Concentrations ◽  
Monsoonal Season

Studies carried out over several years on a tropical estuary, the Ross River Estuary, have shown that copper speciation is influenced by both terrestrial and marine humic substances. While terrestrial humic substances are mobilized by high freshwater runoff in the monsoonal season, Trichodesmium blooms mobilize high concentrations of marine humics to the inshore zone and increase labile forms of copper. The marine humics are more soluble than the terrestrial humics and persist in coastal waters of the Great Barrier Reef lagoon for many months prior to the wet season.

scholarly journals Biogenicity inferred from microbialite geochemistry

2004 ◽  
Vol 25 (1) ◽  
pp. 34 ◽  
Author(s):  
Gregory E Webb ◽  
Balz S Kamber
Keyword(s):  
Rare Earth ◽  
Trace Metals ◽  
Rare Earth Elements ◽  
Great Barrier Reef ◽  
Carbonate Rocks ◽  
Metal Cations ◽  
Microbial Processes ◽  
Barrier Reef ◽  
Carbonate Minerals ◽  
High Concentrations

Microbes utilise and/or concentrate diverse metal cations, whose detection may become a potent tool for reconstructing microbial processes and, in particular, for establishing the genesis of ancient carbonate rocks that were produced by microbes. Such rocks, termed microbialites, consist of trapped and bound sediment and, importantly, carbonate minerals precipitated as accidental byproducts of metabolic or decay processes within biofilms. Where trace metals are predictably incorporated into microbialites, they may reflect biofilm processes and allow interpretation of preserved carbonates. Holocene (about 5-6,000 years old) microbialites that formed in reef cavities in the Great Barrier Reef (GBR) faithfully incorporated high concentrations of rare earth elements and yttrium proportional to their abundance in shallow seawater. Ancient microbialites display similar behaviour.

Nitrogen ecophysiology of Heron Island, a subtropical coral cay of the Great Barrier Reef, Australia

2004 ◽  
Vol 31 (5) ◽  
pp. 517 ◽  
Author(s):  
Susanne Schmidt ◽  
William C. Dennison ◽  
Gordon J. Moss ◽  
George R. Stewart
Keyword(s):  
Uric Acid ◽  
Great Barrier Reef ◽  
High Capacity ◽  
Reef Coral ◽  
Gaseous Ammonia ◽  
Barrier Reef ◽  
15N Labelling ◽  
N Nutrition ◽  
High Concentrations ◽  
A Site

Coral cays form part of the Australian Great Barrier Reef. Coral cays with high densities of seabirds are areas of extreme nitrogen (N) enrichment with deposition rates of up to 1000 kg N ha–1 y–1. The ways in which N sources are utilised by coral cay plants, N is distributed within the cay, and whether or not seabird-derived N moves from cay to surrounding marine environments were investigated. We used N metabolite analysis, 15N labelling and 15N natural abundance (δ15N) techniques. Deposited guano-derived uric acid is hydrolysed to ammonium (NH4+) and gaseous ammonia (NH3). Ammonium undergoes nitrification, and nitrate (NO3–) and NH4+ were the main forms of soluble N in the soil. Plants from seabird rookeries have a high capacity to take up and assimilate NH4+, are able to metabolise uric acid, but have low rates of NO3– uptake and assimilation. We concluded that NH4+ is the principal source of N for plants growing at seabird rookeries, and that the presence of NH4+ in soil and gaseous NH3 in the atmosphere inhibits assimilation of NO3–, although NO3– is taken up and stored. Seabird guano, Pisonia forest soil and vegetation were similarly enriched in 15N suggesting that the isotopic enrichment of guano (δ15N 9.9‰) carries through the forest ecosystem. Soil and plants from woodland and beach environments had lower δ15N (average 6.5‰) indicating a lower contribution of bird-derived N to the N nutrition of plants at these sites. The aquifer under the cay receives seabird-derived N leached from the cay and has high concentrations of 15N-enriched NO3– (δ15N�7.9‰). Macroalgae from reefs with and without seabirds had similar δ15N values of 2.0–3.9‰ suggesting that reef macroalgae do not utilise 15N-enriched seabird-derived N as a main source of N. At a site beyond the Heron Reef Crest, macroalgae had elevated δ15N of 5.2‰, possibly indicating that there are locations where macroalgae access isotopically enriched aquifer-derived N. Nitrogen relations of Heron Island vegetation are compared with other reef islands and a conceptual model is presented.

Neutrophil Elastase Potentiates Cathepsin G-lnduced Platelet Activation

1992 ◽  
Vol 68 (05) ◽  
pp. 570-576 ◽  
Author(s):  
Mary A Selak
Keyword(s):  
Neutrophil Elastase ◽  
Cell Activation ◽  
Thromboxane A2 ◽  
Creatine Phosphate ◽  
Dense Granule ◽  
Cathepsin G ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Low Concentrations ◽  
High Concentrations

SummaryWe have previously demonstrated that human neutrophil cathepsin G is a strong platelet agonist that binds to a specific receptor. This work describes the effect of neutrophil elastase on cathepsin G-induced platelet responses. While platelets were not activated by high concentrations of neutrophil elastase by itself, elastase enhanced aggregation, secretion and calcium mobilization induced by low concentrations of cathepsin G. Platelet aggregation and secretion were potentiated in a concentration-dependent manner by neutrophil elastase with maximal responses observable at 200 nM. Enhancement was observed when elastase was preincubated with platelets for time intervals of 10–60 s prior to addition of a low concentration of cathepsin G and required catalytically-active elastase since phenylmethanesulphonyl fluoride-inhibited enzyme failed to potentiate cell activation. Neutrophil elastase potentiation of platelet responses induced by low concentrations of cathepsin G was markedly inhibited by creatine phosphate/creatine phosphokinase and/or indomethacin, indicating that the synergism between elastase and cathepsin G required the participation of ADP and thromboxane A2. On the other hand, platelet responses were not attenuated by the PAF antagonist BN 52021, signifying that PAF-acether did not play a role in elastase potentiation. At higher concentrations porcine pancreatic elastase exhibits similar effects to neutrophil elastase, demonstrating that the effect of elastase was not unique to the neutrophil protease. While neutrophil elastase failed to alter the ability of cathepsin G to hydrolyze a synthetic chromogenic substrate, preincubation of platelets with elastase increased the apparent affinity of cathepsin G binding to platelets. In contrast to their effect on cathepsin G-induced platelet responses, neither neutrophil nor pancreatic elasatse potentiated aggregation or dense granule release initiated by ADP, PAF-acether, arachidonic acid or U46619, a thromboxane A2 mimetic. Moreover, unlike its effect on cathepsin G, neutrophil elastase inhibited thrombin-induced responses. The current observations demonstrate that elastase can potentiate platelet responses mediated by low concentrations of cathepsin G, suggesting that both enzymes may function synergistically to activate platelets under conditions where neutrophil degranulation occurs.

In Vitro Effects of Ethanol on Rabbit Platelet Aggregation, Secretion of Granule Contents, and Cyclic AMP Levels in the Presence of Prostacyclin

1989 ◽  
Vol 61 (02) ◽  
pp. 254-258 ◽  
Author(s):  
Margaret L Rand ◽  
Peter L Gross ◽  
Donna M Jakowec ◽  
Marian A Packham ◽  
J Fraser Mustard
Keyword(s):  
Cyclic Amp ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Inhibitory Effects ◽  
Low Concentrations ◽  
Rabbit Platelets ◽  
High Concentrations ◽  
In Vitro Effects ◽  
Aggregation Of Platelets

SummaryEthanol, at physiologically tolerable concentrations, inhibits platelet responses to low concentrations of collagen or thrombin, but does not inhibit responses of washed rabbit platelets stimulated with high concentrations of ADP, collagen, or thrombin. However, when platelet responses to high concentrations of collagen or thrombin had been partially inhibited by prostacyclin (PGI2), ethanol had additional inhibitory effects on aggregation and secretion. These effects were also observed with aspirin- treated platelets stimulated with thrombin. Ethanol had no further inhibitory effect on aggregation of platelets stimulated with ADP, or the combination of ADP and epinephrine. Thus, the inhibitory effects of ethanol on platelet responses in the presence of PGI2 were very similar to its inhibitory effects in the absence of PGI2, when platelets were stimulated with lower concentrations of collagen or thrombin. Ethanol did not appear to exert its inhibitory effects by increasing cyclic AMP above basal levels and the additional inhibitory effects of ethanol in the presence of PGI2 did not appear to be brought about by further increases in platelet cyclic AMP levels.

Aggregation of Cat Platelets in Vitro

1970 ◽  
Vol 23 (03) ◽  
pp. 601-620 ◽  
Author(s):  
Th. B Tschopp
Keyword(s):  
Adenosine Monophosphate ◽  
Blood Collection ◽  
Base Line ◽  
Reversible Aggregation ◽  
Low Concentrations ◽  
Irreversible Aggregation ◽  
High Concentrations ◽  
Two Phases ◽  
Improved Technique

SummaryAggregation of cat platelets in the citrated plasma is examined by means of Born’s absorptiometer. A marked tendency of the platelets of this species to spontaneous aggregation necessitated first of all the development of an improved technique of blood collection.A hypothesis according to which 5-HT is released from the platelets, explains the absence of oscillations on the base line of the absorptiometer, the absence of platelet swelling, when ADP is added, and the effect of stirring on the aggregation curves in cat PRP. The average volume of cat platelets amounts to 10.46 μ3 when directly fixed in the blood, when fixed from PRP to 12.17 μ3, when fixed from stirred PRP to 13.51 μ3.In low concentrations (0.3-2 μM) ADP produce reversible aggregation; in narrowly restricted, individually dissimilar mean concentrations irreversible aggregation in two phases and in high concentrations, irreversible aggregation in one phase. Like ADP serotonin produces 2 phase irreversible aggregation in concentrations of 3-10 μM, but unlike ADP, the aggregation velocity decreases again with high 5-HT concentrations (>100 μM). Adrenaline does not produce aggregation and it is likely that adenosine and adenosine monophosphate inhibit the aggregation by serotonin but not by ADP. Species differences in the aggregation of human, rabbit and cat platelets are discussed.

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