Comparison of antibacterial activity in the hemocytes of different crustacean species.

Antibacterial activity in hemocytes of the squat lobster, Galathea strigosa, the Norway lobster, Nephrops norvegicus, the common shrimp, Crangon crangon, and the giant Antarctic isopod, Glyptonotus antarcticus, was investigated in vitro. For all species, the marine bacterium, Psychrobacter immobilis, was used as the test organism, although with G. antarcticus, the Gram positive bacteria, Planococcus citreus and BS 68 (an isolate from Antarctic waters), were also used. Hemocyte lysate supernatants (HLS) from all four species reduced the viable count of test bacteria over a period of 4 hr showing that their hemocytes contain factors able to neutralize bacteria in vitro. However, comparison of responses produced by serially diluted samples of HLS from G. strigosa, N. norvegicus and C. crangon, revealed that activity (per unit protein) is weaker than for Carcinus maenas. Using G. antarcticus, positive activity was also observed against P. citreus and BS 68; with the response effective against all of the bacteria at both 0 degree C and 20 degrees C. These results show that: (1) the hemocytes from a range of crustacean species contain factor(s) able to neutralize bacteria in vitro; (2) antibacterial potency varies from species to species; and (3) antibacterial immunity in at least one polar invertebrate functions at low temperature.

Anomalies in coral reef community metabolism and their potential importance in the reef CO2 source-sink debate.

It is not certain whether coral reefs are sources of or sinks for atmospheric CO2. Air-sea exchange of CO2 over reefs has been measured directly and inferred from changes in the seawater carbonate equilibrium. Such measurements have provided conflicting results. We provide community metabolic data that indicate that large changes in CO2 concentration can occur in coral reef waters via biogeochemical processes not directly associated with photosynthesis, respiration, calcification, and CaCO3 dissolution. These processes can significantly distort estimates of reef calcification and net productivity and obscure the contribution of coral reefs to global air-sea exchange of CO2. They may, nonetheless, explain apparent anomalies in the metabolic performance of reefs close to land and reconcile the differing experimental findings that have given rise to the CO2 debate.

Purification and characterization of a cysteine-rich 11.5-kDa antibacterial protein from the granular haemocytes of the shore crab, Carcinus maenas.

Extracts of the granular haemocytes of Carcinus maenas were subjected to ion-exchange chromatography and reverse-phase (RP)-HPLC to investigate the presence of an antibacterial protein of approximately 11 kDa. This protein was isolated, characterized and subjected to partial amino acid sequence analysis. It was found by mass spectrometry to have a molecular mass of 11 534 Da, to be cationic and hydrophobic and active only against marine Gram-positive bacteria. In addition its activity is stable after heating to 100 degrees C and is retained at concentrations as low as 10 microgram.mL-1. It has an unusual amino acid sequence, unlike any known antibacterial peptide described in the literature but bears a consensus disulphide domain signature, indicating that it might be a member of the four-disulphide core proteins. Partial cDNA sequence data has been obtained.

Spectrographic imaging. A bird's-eye view of the health of coral reefs.

Almost three-quarters of the world's coral reefs are thought to be deteriorating as a consequence of environmental stress. Until now, it has been possible to evaluate reef health only by field survey, which is labour-intensive and time-consuming. Here we map live coral cover from the air by remote imaging, a technique that will enable the state of shallow reefs to be monitored swiftly and over large areas.