Comparative contributions of solution geochemistry, microbial metabolism and aquatic photosynthesis to the development of high pH in ephemeral wetlands in South East Australia.

The development of alkaline conditions in lakes and wetlands is common but the process of alkalinisation is not well elaborated. In this study we investigated causes of the seasonal alkalinisation of ephemeral wetlands in the South East of South Australia where pH values above 10 are frequently observed. This research combined field observations, geochemical analysis of wetland sediment and surface water, with mesocosm studies under controlled conditions. The results revealed a complex interplay between a number of different processes. A primary cause was attributed to sequestration of CO2 from the water column by plant photosynthesis, coupled with slow diffusion of CO2 from the air which led to its depletion in the water. Abundant plant growth also modified the water chemistry via uptake of nutrient elements, in particular calcium and magnesium and increased carbonate alkalinity in the water. Assessment of field results and geochemical modeling showed that low Ca/(HCO3(-) and CO3(-2)) ratios in the water, coupled with carbonate mineral (calcite, Mg substituted calcite, dolomite) precipitation and evapoconcentration, create a high alkalinity and pH (>9) baseline in many wetlands. The high baseline pH is then further increased by CO2 depletion due to photosynthesis. We could find no evidence that reduction of sulfate to sulfides by sulfur-reducing bacteria significantly contributed to the very high pH conditions.

Tobacco outlet density and demographics: analysing the relationships with a spatial regression approach.

OBJECTIVE: Studies of relationships between tobacco sales and socio-economic/sociodemographic characteristics are well documented. However, when analysing the data that are collected on geographic areas, the spatial effects are seldom considered, which could lead to potential misleading analytical results. This study addresses this concern by applying the spatial analysis method in studying how socio-economic factors and tobacco outlet density are related in New Jersey, USA. STUDY DESIGN: A spatial regression method applied to tobacco outlet and socio-economic data obtained in 2004 in New Jersey, USA. METHOD: This study assessed the association between tobacco outlet density and three demographic correlates - income, race and ethnicity - at the tract level of analysis for one state in the north-eastern USA. Data for 1938 residential census tracts in the state of New Jersey were derived from 2004 licences for 13,984 tobacco-selling retail outlets. Demographic variables were based on 2000 census data. When applying a regression model, the residuals of an ordinary least squared (OLS) estimation were found to exhibit strong spatial autocorrelation, which indicates that the estimates from the OLS model are biased and inferences based on the estimates might be misleading. A spatial lag model was employed to incorporate the potential spatial effects explicitly. RESULTS: Agreeing with the OLS residual autocorrelation test, the spatial lag model yields a significant coefficient of the added spatial effect, and fits the data better than the OLS model. In addition, the residuals of the spatial regression model are no longer autocorrelated, which indicates that the analysis produces more reliable results. More importantly, the spatial regression results indicate that tobacco companies attempt to promote physical availability of tobacco products to geographic areas with disadvantageous socio-economic status. In New Jersey, the percentage of Hispanics seems to be the dominant demographic factor associated with tobacco outlet distribution, followed by median household income and percentage of African Americans. CONCLUSION: This research applied a spatial analytical approach to assess the association between tobacco outlet density and sociodemographic characteristics in New Jersey at the census tract level. The findings support the common wisdom in the public health research domain that tobacco outlets are more densely distributed in socio-economically disadvantaged areas. However, incorporating the spatial effects explicitly in the analysis provides less biased and more reliable results than traditional methods.

The first report of disease in a basking shark (Cetorhinus maximus).

Few diseases have been reported in any species of shark and none in the basking shark (Cetorhinus maximus) despite the latter being the subject of targeted hunting for over two centuries. This is the first report to describe the clinical signs and gross and microscopical pathology in a diseased basking shark that was live-stranded on the east coast of Scotland. Pyogranulomatous meningoencephalitis was present together with multifocal, predominantly non-suppurative, myocarditis with myocyte necrosis, oedema and haemorrhage. Additionally, there was full thickness ulcerative and fibrinonecrotizing dermatitis with underlying granulomatous inflammation. The aetiology could not be determined, but the lesions were suggestive of an infectious process, possibly bacterial.

Brucella ceti associated pathology in the testicle of a harbour porpoise (Phocoena phocoena).

Brucellosis is reported increasingly in marine mammals and the marine species of Brucella are capable of causing community acquired zoonotic infections in humans as well as abortion in cattle as a result of experimental infection. This case report describes pathology associated with an isolate of Brucella ceti that was successfully cultured from, and immunolabelled in, the testis and epididymis of an adult sexually mature free-living harbour porpoise (Phocoena phocoena). This is the first report of such pathology in any species of cetacean, and suggests the potential for sexual transmission and/or sterility as sequelae to infection similar to those reported in terrestrial animals.

Bioaccumulation of persistent organic pollutants in female common dolphins (Delphinus delphis) and harbour porpoises (Phocoena phocoena) from western European seas: geographical trends, causal factors and effects on reproduction and mortality.

Concentrations of polychlorinated biphenyls (PCBs) in blubber of female common dolphins and harbour porpoises from the Atlantic coast of Europe were frequently above the threshold at which effects on reproduction could be expected, in 40% and 47% of cases respectively. This rose to 74% for porpoises from the southern North Sea. PCB concentrations were also high in southern North Sea fish. The average pregnancy rate recorded in porpoises (42%) in the study area was lower than in the western Atlantic but that in common dolphins (25%) was similar to that of the western Atlantic population. Porpoises that died from disease or parasitic infection had higher concentrations of persistent organic pollutants (POPs) than animals dying from other causes. Few of the common dolphins sampled had died from disease or parasitic infection. POP profiles in common dolphin blubber were related to individual feeding history while those in porpoises were more strongly related to condition.

Mass-dependent predation risk and lethal dolphin-porpoise interactions.

In small birds, mass-dependent predation risk (MDPR) is known to make the trade-off between avoiding starvation and avoiding predation dependent on individual mass. This occurs because carrying increased fat reserves not only reduces starvation risk but also results in a higher predation risk due to reduced escape flight performance and/or the increased foraging exposure needed to maintain a higher body mass. In principle, the theory of MDPR could also apply to any animal capable of storing energy reserves to reduce starvation and whose escape performance decreases with increasing mass. We used a unique situation along certain parts of coastal Britain, where harbour porpoises (Phocoena phocoena) are pursued and killed but crucially not eaten by bottlenose dolphins (Tursiops truncatus), to investigate whether a MDPR effect can occur in non-avian species. We show that where high levels of dolphin 'predation' occur, porpoises carry significantly less energy reserves than would otherwise be expected and this equates to reducing by approximately 37% the length of time that a porpoise could survive without feeding. These results provide the first evidence that a mass-dependent starvation-predation risk trade-off may be a general ecological principle that can apply to widely different animal types rather than, as is currently thought, only to birds.

Acute and chronic gas bubble lesions in cetaceans stranded in the United Kingdom.

The first evidence suggestive of in vivo gas bubble formation in cetacea, including eight animals stranded in the UK, has recently been reported. This article presents the pathologic findings from these eight UK-stranded cetaceans and two additional UK-stranded cetacean cases in detail. Hepatic gas-filled cavitary lesions (0.2-6.0 cm diameter) involving approximately 5-90% of the liver volume were found in four (two juvenile, two adult) Risso's dolphins (Grampus griseus), three (two adult, one juvenile) common dolphins (Delphinus delphis), an adult Blainville's beaked whale (Mesoplodon densirostris), and an adult harbour porpoise (Phocoena phocoena). Histopathologic examination of the seven dolphin cases with gross liver cavities revealed variable degrees of pericavitary fibrosis, microscopic, intrahepatic, spherical, nonstaining cavities (typically 50-750 microm in diameter) consistent with gas emboli within distended portal vessels and sinusoids and associated with hepatic tissue compression, hemorrhages, fibrin/organizing thrombi, and foci of acute hepato-cellular necrosis. Two common dolphins also had multiple and bilateral gross renal cavities (2.0-9.0 mm diameter) that, microscopically, were consistent with acute (n = 2) and chronic (n = 1) arterial gas emboli-induced renal infarcts. Microscopic, bubblelike cavities were also found in mesenteric lymph node (n = 4), adrenal (n = 2), spleen (n = 2), pulmonary associated lymph node (n = 1), posterior cervical lymph node (n = 1), and thyroid (n = 1). No bacterial organisms were isolated from five of six cavitated livers and one of one cavitated kidneys. The etiology and pathogenesis of these lesions are not known, although a decompression-related mechanism involving embolism of intestinal gas or de novo gas bubble (emboli) development derived from tissues supersaturated with nitrogen is suspected.

Ability of parents to recall the injuries of their young children.

OBJECTIVE: To estimate the ability of parents to recall the injuries of their children. DESIGN: Comparison of parent recall with computerized medical records. SETTING: A health maintenance organization in Washington State during 2003. SUBJECTS: Parents of children younger than 6 years. MAIN OUTCOME MEASURES: The ratio of recalled injuries to injuries in computerized data. RESULTS: Telephone interviews were completed with a parent of 1672 young children who had computerized medical data for at least one injury in the last year. Counting the three most recent treated injuries, the 1672 children had 1896 separate new injuries in the year before interview and parents recalled 1150 of these: recall ratio 0.61 (95% confidence interval (CI) 0.58 to 0.63). The recall ratio decreased from 0.82 (95% CI 0.79 to 0.85) for injuries one day before interview to 0.37 (95% CI 0.32 to 0.40) at 365 days before interview. For 341 major injuries the recall ratio was 0.80 (95% CI 0.76 to 0.84), for 202 minor injuries treated in an emergency department or hospital it was 0.77 (95% CI 0.71 to 0.82), for 597 minor injuries treated in urgent care it was 0.70 (95% CI 0.65 to 0.73), and for 756 minor injuries treated in a clinic it was 0.43 (95% CI 0.39 to 0.47). CONCLUSIONS: Recall decreased with time. Recall was best for major injuries, intermediate for minor injuries treated in a hospital, emergency department, or urgent care center, and worst for minor injuries treated in a clinic.

The uptake and partitioning of cadmium in two cultivars of potato (Solanum tuberosum L.).

The uptake and distribution of Cd in potatoes over the course of a growing season was investigated in two cultivars of potatoes that differed in tuber Cd concentration. Plants were grown in soil with supplemental Cd. The concentrations of Cd in different tissues varied greatly in the order roots>shoots>> tubers. After the initiation of tuber bulking, shoot growth ceased and the increase in total plant Cd was mostly due to accumulation in the tubers. The constancy of the Cd concentration in shoots suggested that import of Cd via the xylem must be matched by export in the phloem, which implied that Cd must have significant phloem mobility. It was found that the differences in tuber Cd between cultivars Wilwash and Kennebec were not due to differences in total uptake or growth, but to differences in Cd partitioning within the plant. This partitioning was specific to Cd and was not observed for a range of nutrient elements. Most of the differences in tuber Cd concentration between the cultivars could be accounted for by a 3-fold higher retention of Cd in the roots of cv. Wilwash. The involvement of root sequestration, and xylem and phloem pathways in the loading of Cd into tubers is considered.

A review of Brucella sp. infection of sea mammals with particular emphasis on isolates from Scotland.

Brucellae recovered from sea mammals were first reported in 1994. In the years since both culture and serological analysis have demonstrated that the infection occurs in a wide range of species of marine mammals inhabiting a vast amount of the world's oceans. Molecular studies have demonstrated that the isolates differ from those found amongst terrestrial animals and also distinguish between strains which have seals and cetaceans as their preferred hosts. At the phenotypic level seal and cetacean strains can also be differed with respect to their CO(2) requirement, primary growth on Farrells medium and metabolic activity on galactose. Two new species B. cetaceae and B. pinnipediae have been proposed as a result. This paper provides a review of Brucella in sea mammals and updates findings from the study of sea mammals from around the coast of Scotland.

Chronic meningoencephalitis associated with Brucella sp. infection in live-stranded striped dolphins (Stenella coeruleoalba).

A chronic, non-suppurative meningoencephalitis was found in three young striped dolphins (Stenella coeruleoalba) during routine neuropathological examination of marine mammals live-stranded on the Scottish coast. In all three dolphins the lesions were associated with the isolation of a Brucella sp. from the brain and with the immunohistochemical detection of brucella antigen. Moreover, antibodies to Brucella spp. were detected in the two dolphins that were subjected to serological examination. Immunohistochemical and serological examinations for morbillivirus antigen and antibodies, respectively, were negative in all cases. Although brucella infection of marine mammals has been extensively documented in recent years, its association with lesions and disease is less well recognized. The present report provides the first description of an association between Brucella sp. infection and neuropathological changes in a cetacean species.

Cytoplasmic acidification with butyric acid does not alter the ionic conductivity of plasmodesmata.

The effect of lowering cytoplasmic pH on the ionic conductivity of higher-plant plasmodesmata was investigated with corn (Zea mays L. cv. Black Mexican Sweet) suspension culture cells. Exposure to butyric acid decreased the cytoplasmic pH by 0.8 units. Intercellular communication was monitored by electrophysiological techniques that allowed the measurement of membrane resistances of sister cells and the electrical resistance of the plasmodesmata connecting them. The decrease in cytoplasmic pH did not affect the resistance of plasmodesmata, despite the fact that the butyric acid treatment more than doubled the concentration of cytoplasmic calcium. This is discussed in light of previous findings that increases in cytoplasmic calcium increase the electrical resistance of plasmodesmata.

Effect of membrane surface charge on nickel uptake by purified mung bean root protoplasts.

The influence of membrane surface charge on cation uptake was investigated in protoplasts prepared from roots of mung bean (Vigna radiata L.). Confocal laser scanning microscopy showed that a fluorescent trivalent cation accumulated to very high concentrations at the surface of the protoplasts when they were incubated in medium containing low concentrations of Ca or other cations, but that this accumulation could be completely reversed by suppression of membrane surface negativity by high cation concentrations. Influx of 63Ni was strongly reduced by a range of divalent cations. Increasing the Ca concentration in the medium from 25 microM to 10 mM inhibited 63Ni influx by more than 85%. 63Ni influx was also inhibited by 85% by reducing the pH from 7 to 4. Computation of the activity of Ni at the membrane surface under the various treatment conditions showed that Ni uptake was closely correlated with its activity at the membrane surface but not with its concentration in the bulk medium. It was concluded that the effects on Ni uptake of addition of monovalent, divalent and trivalent cations, and of variations in pH are all consistent with the proposition that the activity of Ni at the membrane surface is the major determinant of the rate of Ni influx into mung bean protoplasts. It is proposed that the surface charge on the plasma membrane will influence the membrane transport of most charged molecules into cells.

Characterization of two HKT1 homologues from Eucalyptus camaldulensis that display intrinsic osmosensing capability.

Plants have multiple potassium (K(+)) uptake and efflux mechanisms that are expressed throughout plant tissues to fulfill different physiological functions. Several different classes of K(+) channels and carriers have been identified at the molecular level in plants. K(+) transporters of the HKT1 superfamily have been cloned from wheat (Triticum aestivum), Arabidopsis, and Eucalyptus camaldulensis. The functional characteristics as well as the primary structure of these transporters are diverse with orthologues found in bacterial and fungal genomes. In this report, we provide a detailed characterization of the functional characteristics, as expressed in Xenopus laevis oocytes, of two cDNAs isolated from E. camaldulensis that encode proteins belonging to the HKT1 superfamily of K(+)/Na(+) transporters. The transport of K(+) in EcHKT-expressing oocytes is enhanced by Na(+), but K(+) was also transported in the absence of Na(+). Na(+) is transported in the absence of K(+) as has been demonstrated for HKT1 and AtHKT1. Overall, the E. camaldulensis transporters show some similarities and differences in ionic selectivity to HKT1 and AtHKT1. One striking difference between HKT1 and EcHKT is the sensitivity to changes in the external osmolarity of the solution. Hypotonic solutions increased EcHKT induced currents in oocytes by 100% as compared with no increased current in HKT1 expressing or uninjected oocytes. These osmotically sensitive currents were not enhanced by voltage and may mediate water flux. The physiological function of these osmotically induced increases in currents may be related to the ecological niches that E. camaldulensis inhabits, which are periodically flooded. Therefore, the osmosensing function of EcHKT may provide this species with a competitive advantage in maintaining K(+) homeostasis under certain conditions.

Kinetic analysis of boron transport in Chara.

The permeability of biological membranes to boric acid was investigated using the giant internodal cells of the charophyte alga Chara corallina (Klein ex Will. Esk. R.D. Wood). The advantage of this system is that it is possible to distinguish between membrane transport of boron (B) and complexing of B by plant cell walls. Influx of B was found to be rapid, with equilibrium between the intracellular and extracellular phases being established after approximately 24 h when the external concentration was 50 microM. The intracellular concentration at equilibrium was 55 microM, which is consistent with passive distribution of B across the membrane along with a small amount of internal complexation. Efflux of B occurred with a similar half-time to influx, approximately 3 h, which indicates that the intracellular B was not tightly complexed. The concentration dependence of short-term influx measured with 10B-enriched boric acid was biphasic. This was tentatively attributed to the operation of two separate transport systems, a facilitated system that saturates at 5 microM, and a linear component due to simple diffusion of B through the membrane. Vmax and Km for the facilitated transport system were 135 pmol m(-2) s(-1) and 2 microM, respectively. The permeability coefficient for boric acid in the Chara plasmalemma estimated from the slope of the linear influx component was 4.4 x 10(-7) cm s(-1) which is an order of magnitude lower than computed from the ether:water partition coefficient for B.