Global distribution and genetic discontinuities of mangroves - emerging patterns in the evolution of Rhizophora

Mangroves are often described as a group of plants with common features and common origins based mostly on their broad distributional patterns, together with an erroneous view of comparable abilities in long-distance dispersal. However, whilst mangroves have common needs to adapt to rigorous environmental constraints associated with regular seawater inundation, individual taxa have developed different strategies and characteristics. Since mangroves are a genetically diverse group of mostly flowering plants, they may also have evolved at quite different geological periods, dispersed at different rates from different locations and developed different adaptive strategies. Current distributions of individual taxa show numerous instances of unusual extant distribution which demonstrate finite dispersal limitations, especially across open water. Our preliminary assessment of broad distribution and discontinuities reveals important patterns. Discontinuities, in the absence of current dispersal barriers, may be explained by persistent past barriers. As we learn more about discontinuities, we are beginning to appreciate their immense implications and what they might tell us about past geological conditions and how these might have influenced the distribution and evolution of mangroves. In this article, we describe emerging patterns in genetic relationships and distributions based on both current knowledge and preliminary results of our studies of molecular and morphometric characteristics of Rhizophora species in the Indo West Pacific region.

Different mineralization styles in a volcanic-hosted ore deposit: the fluid and isotopic signatures of the Mt Morgan Au-Cu deposit, Australia

Quantitative laser ablation (LA)-ICP-MS analyses of fluid inclusions, trace element chemistry of sulfides, stable isotope (S), and Pb isotopes have been used to discriminate the formation of two contrasting mineralization styles and to evaluate the origin of the Cu and Au at Mt Morgan. The Mt Morgan Au-Cu deposit is hosted by Devonian felsic volcanic rocks that have been intruded by multiple phases of the Mt Morgan Tonalite, a low-K, low-Al2O3 tonalite-trondhjemite-dacite (TTD) complex. An early, barren massive sulfide mineralization with stringer veins is conforming to VHMS sub-seafloor replacement processes, whereas the high-grade Au-Cu. ore is associated with a later quartz-chalcopyrite-pyrite stock work mineralization that is related to intrusive phases of the Tonalite complex. LA-ICP-MS fluid inclusion analyses reveal high As (avg. 8850 ppm) and Sb (avg. 140 ppm) for the Au-Cu mineralization and 5 to 10 times higher Cu concentration than in the fluids associated with the massive pyrite mineralization. Overall, the hydrothermal system of Mt Morgan is characterized by low average fluid salinities in both mineralization styles (45-80% seawater salinity) and temperatures of 210 to 270 degreesC estimated from fluid inclusions. Laser Raman Spectroscopic analysis indicates a consistent and uniform array Of CO2-bearing fluids. Comparison with active submarine hydrothermal vents shows an enrichment of the Mt Morgan fluids in base metals. Therefore, a seawater-dominated fluid is assumed for the barren massive sulfide mineralization, whereas magmatic volatile contributions are implied for the intrusive related mineralization. Condensation of magmatic vapor into a seawater-dominated environment explains the CO2 occurrence, the low salinities, and the enriched base and precious metal fluid composition that is associated with the Au-Cu. mineralization. The sulfur isotope signature of pyrite and chalcopyrite is composed of fractionated Devonian seawater and oxidized magmatic fluids or remobilized sulfur from existing sulfides. Pb isotopes indicate that Au and Cu. originated from the Mt Morgan intrusions and a particular volcanic strata that shows elevated Cu background. (C) 2002 Elsevier Science B.V. All rights reserved.

Numerical modelling of contaminant transport in coastal aquifers

This paper employs a two-dimensional variable density flow and transport model to investigate the transport of a dense contaminant plume in an unconfined coastal aquifer. Experimental results are also presented to show the contaminant plume in a freshwater-seawater flow system. Both the numerical and experimental results suggest that the neglect of the seawater interface does not noticeably affect the horizontal migration rate of the plume before it reaches the interface. However, the contaminant will travel further seaward and part of the solute mass will exit under the sea if the higher seawater density is not included. If the seawater density is included, the contaminant will travel upwards towards the beach along the freshwater-saltwater interface as shown experimentally. Neglect of seawater density, therefore, will result in an underestimate of solute mass rate exiting around the coastline. (C) 2002 IMACS. Published by Elsevier Science B.V. All rights reserved.

Dinoflagellate symbiosis: strategies and adaptations for the aquisition and fixation of inorganic carbon

Dinoflagellates exist in symbiosis with a number of marine invertebrates including giant clams, which are the largest of these symbiotic organisms. The dinoflagellates (Symbiodinium sp.) live intercellularly within tubules in the mantle of the host clam. The transport of inorganic carbon (Ci) from seawater to Symbiodinium (=zooxanthellae) is an essential function of hosts that derive the majority of their respiratory energy from the photosynthate exported by the zooxanthellae. Immunolocalisation studies show that the host has adapted its physiology to acquire, rather than remove CO2, from the haemolymph and clam tissues. Two carbonic anhydrase (CA) isoforms (32 and 70 kDa) play an essential part in this process. These have been localised to the mantle and gill tissues where they catalyse the interconversion of HCO3- to CO2, which then diffuses into the host tissues. The zooxanthellae exhibit a number of strategies to maximise Ci acquisition and utilisation. This is necessary as they express a form II Rubisco that has poor discrimination between CO2 and O-2. Evidence is presented for a carbon concentrating mechanism (CCM) to overcome. this disadvantage. The CCM incorporates the presence of a light-activated CA activity, a capacity to take up both HCO3- and CO2, an ability to accumulate an elevated concentration of Ci within the algal cell, and localisation of Rubisco to the pyrenoid. These algae also express both external and intracellular CAs, with the intracellular isoforms being localised to the thylakoid lumen and pyrenoid. These results have been incorporated into a model that explains the transport of Ci from seawater through the clam to the zooxanthellae.

Occurrence of immature Culicoides molestus (Skuse) (Diptera : Ceratopogonidae) in relation to habitat characteristics

Analysis of beach sites on the Gold Coast, Australia, found that 14 physical and chemical habitat characteristics differed significantly between sites where numerous immatures of the canal biting midge, Culicoides molestus (Skuse), were found and sites where no midge immatures occurred. Five of the chemical factors found to reliably distinguish C. molestus habitat are major components of seawater, while another, electrical conductivity, is related to the concentration of seawater components. Calcium was the only one of the six primary components of seawater that was not a statistically significant correlate of C. molestus habitation by sand analysis. It is likely that a causative variable in occurrence of immatures is the concentration of seawater present in canals, because larvae are found where seawater component concentration is low in relation to uninhabited sites of similar appearance.

DNA vaccine coding for the full-length infectious Kunjin virus RNA protects mice against the New York strain of West Nile virus

A plasmid DNA directing transcription of the infectious full-length RNA genome of Kunjin (KUN) virus in vivo from a mammalian expression promoter was used to vaccinate mice intramuscularly. The KUN viral cDNA encoded in the plasmid contained the mutation in the NS1 protein (Pro-250 to Leu) previously shown to attenuate KUN virus in weanling mice. KUN virus was isolated from the blood of immunized mice 3-4 days after DNA inoculation, demonstrating that infectious RNA was being transcribed in vivo; however, no symptoms of virus-induced disease were observed. By 19 days postimmunization, neutralizing antibody was detected in the serum of immunized animals. On challenge with lethal doses of the virulent New York strain of West Nile (WN) or wild-type KUN virus intracerebrally or intraperitoneally, mice immunized with as little as 0.1-1 mug of KUN plasmid DNA were solidly protected against disease. This finding correlated with neutralization data in vitro showing that serum from KUN DNA-immunized mice neutralized KUN and WN,viruses with similar efficiencies. The results demonstrate that delivery of an attenuated but replicating KUN virus via a plasmid DNA vector may provide an effective vaccination strategy against virulent strains of WN virus.

Epitope-blocking enzyme-linked immunosorbent assays for detection of West Nile virus antibodies in domestic mammals

We evaluated the ability of epitope-blocking enzyme-linked immunosorbent assays (ELISAs) to detect West Nile virus (WNV) antibodies in domestic mammals. Sera were collected from experimentally infected horses, cats, and pigs at regular intervals and screened in ELISAs and plaque reduction neutralization tests. The diagnostic efficacies of these techniques were similar.

Deviance and marginal occupations: the case of taxi drivers

The taxi industry provides a strategic site to explore workplace deviance in low supervision, low status, occupational settings. Despite this theoretical opportunity and the objective importance of the taxi industry worldwide, very little is known about deviance among taxi drivers. Making use of interview data, this exploratory study maps out forms of workplace deviance and the explanations given for them by a sample of male taxi drivers. Major illegal activities reported included speeding, driving unsafe vehicles, taking drugs, and fraud. Theories pertaining to worker alienation, stress management, victim precipitation, and social control were relevant to the rationalizations some of the drivers provided to account for their illegal behaviors. We conclude that the occupational culture of taxi drivers and the structure of the taxi industry facilitate the forms of deviance reported here.

Detection of West Nile Virus Infection in birds in the United States by blocking ELISA and immunohistochemistry

A blocking ELISA targeting an immunodominant West Nile epitope on the West Nile Virus NS1 protein was assessed for the detection of West Nile-specific antibodies in blood samples collected from 584 sentinel chickens and 238 wild birds collected in-New Jersey from May-December 2000. Ten mallard ducks (Anas platyrhynchos) experimentally infected with West Nile virus and six uninfected controls were also tested. The ELISA proved specific in detecting WNV antibodies in 9/10 chickens and 4/4 wild birds previously confirmed as positive by Plaque Reduction Neutralization test (PRNT) at the Center for Disease Control, Division of Vector Borne Diseases, Fort Collins, CO, USA (CDC). Nine out of the ten experimentally infected mallard ducks also tested positive for WN antibodies in the blocking ELISA, while 6/6 uninfected controls did not. Additionally, 1705 wild birds, collected in New Jersey from December 2000-November 2001 and Long Island, New York between November 1999 and August 2001 were also tested for WN antibodies by the blocking ELISA. These tests identified 30 positive specimens, 12 of which had formalin-fixed tissues available to allow detection of WN specific viral antigen in various tissues by WNV-specific immunohistochemistry. Our results indicate that rapid and specific detection of antibodies to WN virus in sera from a range of avian species by blocking ELISA is an effective strategy for WN Virus surveillance in avian hosts. In combination with detection of WN-specific antigens in tissues by immunohistochemistry (IHC) the blocking ELISA will also be useful for confirming WN infection in diseased birds.

IL-10 Mediates Suppression of the CD8 T Cell IFN-γ Response to a Novel Viral Epitope in a Primed Host

Priming to Ag can inhibit subsequent induction of an immune response to a new epitope incorporated into that Ag, a phenomenon referred to as original antigenic sin. In this study, we show that prior immunity to a virus capsid can inhibit subsequent induction of the IFN-gamma effector T cell response to a novel CD8-restricted antigenic epitope associated with the virus capsid. Inhibition does not involve Ab to the virus capsid, as it is observed in animals lacking B cells. CD8-restricted virus-specific T cell responses are not required, as printing to virus without CTL induction is associated with inhibition. However, IL-10(-/-) mice, in contrast to IL-10(+/+) mice, generate CD8 T cell and Ab responses to novel epitopes incorporated into a virus capsid, even when priming to the capsid has resulted in high titer Ab to the capsid. Furthermore, capsid-primed mice, unable to mount a response to a novel epitope in the capsid protein, are nevertheless able to respond to the same novel epitope delivered independently of the capsid. Thus, inhibition of responsiveness to a novel epitope in a virus-primed animal is a consequence of secretion of IL-10 in response to presented Ag, which inhibits local generation of new CD8 IFN-gamma-secreting effector T cells. Induction of virus- or tumor Ag-specific CD8 effector T cells in the partially Ag-primed host may thus be facilitated by local neutralization of IL-10.

Effects of herbicides diuron and atrazine on corals of the Great Barrier Reef, Australia

In response to recent reports of contamination of the nearshore marine environment along the Queensland coast by herbicides (including areas inside the Great Barrier Reef Marine Park), an ecotoxicological assessment was conducted of the impact of the herbicides diuron and atrazine on scleractinian corals. Pulse-amplitude modulated (PAM) chlorophyll fluorescence techniques were used to assess the herbicide effects on the symbiotic dinoflagellates within the tissues (in hospite) of 4 species of coral (Acropora formosa, Montipora digitata, Porites cylindrica, Seriatopora hystrix) in static toxicity tests, and in freshly isolated symbiotic dinoflagellates from Stylophora pistillata. Using change in the effective quantum yield (DeltaF/F-m') as an effect criterion, diuron (no observable effect concentration, NOEC = 0.3 mug 1(-1); lowest observable effect concentration, LOEC = 1 mug 1(-1); median effective concentration, EC50 4 to 6 mug 1(-1)) was found to be more toxic than atrazine (NOEC = 1 mug 1(-1), LOEC = 3 mug 1(-1), EC50 40 to 90 mug 1(-1)) in short-term (10 h) toxicity tests. In the tests with isolated algae, significant reductions in DeltaF/F-m' were recorded as low as 0.25 mug 1(-1) diuron (LOEC, EC50 = 5 mug 1(-1)). Time-course experiments indicated that the effects of diuron were rapid and reversible. At 10 mug 1(-1) diuron, DeltaF/F-m' was reduced by 25% in 20 to 30 min, and by 50% in 60 to 90 min. Recovery of DeltaF/F-m' in corals exposed to 10 mug 1(-1) diuron and then transferred to running seawater was slower, returning to within 10% of control values inside 1 to 7 h. The effect of a reduction in salinity (35 to 27%) on diuron toxicity (at 1 and 3 mug 1(-1) diuron) was tested to examine the potential consequences of contaminated coastal flood plumes inundating inshore reefs. DeltaF/F-m' was reduced in the diuron-exposed corals, but there was no significant interaction between diuron and reduced salinity seawater within the 10 h duration of the test. Exposure to higher (100 and 1000 mug 1(-1)) diuron concentrations for 96 h caused a reduction in DeltaF/F-m' the ratio variable to maximal fluorescence (F,1F.), significant loss of symbiotic dinoflagellates and pronounced tissue retraction, causing the corals to pale or bleach. The significance of the results in relation to diuron contamination of the coastal marine environment from terrestrial sources (mainly agricultural) and marine sources (antifouling paints) are discussed.