The impacts of intensive mining on terrestrial and aquatic ecosystems: A case of sediment pollution and calcium decline in cool temperate Tasmania, Australia.

Mining causes extensive damage to aquatic ecosystems via acidification, heavy metal pollution, sediment loading, and Ca decline. Yet little is known about the effects of mining on freshwater systems in the Southern Hemisphere. A case in point is the region of western Tasmania, Australia, an area extensively mined in the 19th century, resulting in severe environmental contamination. In order to assess the impacts of mining on aquatic ecosystems in this region, we present a multiproxy investigation of the lacustrine sediments from Owen Tarn, Tasmania. This study includes a combination of radiometric dating (14C and 210Pb), sediment geochemistry (XRF and ICP-MS), pollen, charcoal and diatoms. Generalised additive mixed models were used to test if changes in the aquatic ecosystem can be explained by other covariates. Results from this record found four key impact phases: (1) Pre-mining, (2) Early mining, (3) Intense mining, and (4) Post-mining. Before mining, low heavy metal concentrations, slow sedimentation, low fire activity, and high biomass indicate pre-impact conditions. The aquatic environment at this time was oligotrophic and dystrophic with sufficient light availability, typical of western Tasmanian lakes during the Holocene. Prosperous mining resulted in increased burning, a decrease in landscape biomass and an increase in sedimentation resulting in decreased light availability of the aquatic environment. Extensive mining at Mount Lyell in the 1930s resulted in peak heavy metal pollutants (Pb, Cu and Co) and a further increase in inorganic inputs resulted in a disturbed low light lake environment (dominated by Hantzschia amphioxys and Pinnularia divergentissima). Following the closure of the Mount Lyell Co. in 1994 CE, Ca declined to below pre-mining levels resulting in a new diatom assemblage and deformed diatom valves. Therefore, the Owen Tarn record demonstrates severe sediment pollution and continued impacts of mining long after mining has stopped at Mt. Lyell Mining Co.

Physiological condition differentially affects the behavior and survival of two populations of sockeye salmon during their freshwater spawning migration.

Recently, a segment of the Adams-Shuswap sockeye salmon (Oncorhynchus nerka) population initiated freshwater migration several weeks earlier than historically recorded, resulting in high mortality rates. The comigrating Chilko population maintained their historic river entry timing and did not experience elevated mortality. To test the hypothesis that population-specific differences in physiological condition would differentially influence behavior and survival when exposed to fisheries capture stress, we physiologically sampled individuals from both populations at the onset of the freshwater phase of their reproductive migration and tracked the remainder of their migrations using radio telemetry. Adams-Shuswap individuals had slower migration rates and were less likely to reach natal subwatersheds relative to Chilko individuals. Metabolic and osmoregulatory impairment was related to mortality for Adams-Shuswap individuals but not for Chilko individuals. Similarly, physiological condition correlated with migration rate for Adams-Shuswap but not Chilko fish. Survival to natal subwatersheds was 1.9 times higher for Chilko relative to Adams-Shuswap, a result that did not emerge until individuals approached natal subwatersheds several days after the stressor was applied. We conclude that physiological condition differentially affects the behavior and survival of these two populations, which may be a consequence of the early-entry phenomenon by a segment of the Adams-Shuswap population.

Phenotypic stability of articular chondrocytes in vitro: the effects of culture models, bone morphogenetic protein 2, and serum supplementation.

Numerous in vitro culture models have been developed for the investigation of chondrocyte and cartilage biology. In this study, we investigated the stability of the chondrocytic phenotype in monolayer, aggregate, pellet, and explant culture models and assessed the effects of recombinant human bone morphogenetic protein 2 (rhBMP-2) and serum supplementation on the phenotype in each model. Phenotypic effects were assessed by analyses of procollagen type II, aggrecan, (V + C)- fibronectin, and procollagen type I messenger RNA expression. In monolayer cultures, we noted a characteristic loss of procollagen type II and induction of procollagen type I expression. The aggregate and pellet culture models supported matrix protein gene expression profiles more reflective of in vivo levels. In explant cultures, expression of matrix protein genes was consistently depressed. Treatment with rhBMP-2 significantly increased the expression of procollagen type II and aggrecan in monolayer cultures; however, other models showed comparatively little response. Similarly, serum supplementation significantly down-regulated procollagen type II and aggrecan expression in monolayer cultures but had less effect on gene expression in the other models. Serum supplementation increased procollagen type I expression in monolayer and aggregate cultures. These results suggest that the influence of exogenous BMP-2 and serum on expression of chondrocyte-specific matrix protein genes is influenced by aspects of substrate attachments, cellular morphology, and/or cytoskeletal organization. Finally, the analyses of fibronectin expression suggest that V and C region alternative splicing in chondrocytes is linked to the establishment of a three-dimensional multicellular complex.

Effects of cryopreservation procedures on the cytology and fertilization rate of in vitro-matured bovine oocytes.

The survival and developmental capacity of bovine oocytes after cryopreservation are greatly impaired, possibly due to organelle damage caused by freezing procedures. Distributions of chromosomes, microtubules, and microfilaments in bovine oocytes matured in vitro were examined after cooling, ethylene glycol (EG) exposure, or freezing. Oocytes were incubated after treatment for 20 min or 1 or 3 h, fixed, and evaluated using specific fluorescent probes. Abnormal cytological features increased over control levels after cooling or EG exposure and rewarming. Changes observed in oocytes during prefreezing manipulations included chromosome dispersal and clumping, microtubule depolymerization and alteration of spindle structure, and formation of craters and discontinuity in cytoskeletal actin staining. Freezing also led to an increase in the occurrence of cytological abnormalities. Less than 31% of frozen-thawed oocytes contained a normal chromosome arrangement 3 h postthaw (versus 90% of controls). Only 7-14% of frozen-thawed oocytes had normal spindles (versus 59-71% of controls). Normal distribution of filamentous actin was observed in less than 30% of oocytes postthaw (versus 62-89% of controls). These results indicate that the steps in a conventional freezing procedure cause irreversible alterations in multiple cytological components of bovine oocytes, demonstrating the need for improved strategies for preventing cellular damage during cryopreservation procedures.

Monocyte activation in platelet concentrates.

BACKGROUND AND OBJECTIVES: Cytokines in platelet concentrates contribute to febrile transfusion reactions. Activated monocytes are a major source of inflammatory cytokines, however the role of monocytes in cytokine production in platelet concentrates has not been clarified. This study undertook to quantitate monocytes, determine whether monocyte activation occurs and identify an association with IL-6 and IL-1beta concentrations in platelet concentrates. MATERIALS AND METHODS: 17 platelet concentrates were analysed for total leucocyte and monocyte counts, CD14 and CD16 monocyte-associated antigen expression and IL-1beta and IL-6 measurements on days 1, 2, 3, 4 and 5. RESULTS: Monocytes in all platelet concentrates expressed increased levels of CD14 and CD16 from day 1 of storage. 10/17 platelet concentrates had elevated IL-6 levels by day 3. Platelet concentrates with IL-6 levels above 15 pg/ml on day 5 had monocyte counts between 0.14 and 15.6 x 10(6)/unit on day 1, while those with IL-6 levels below 15 pg/ml had low monocyte counts of < 0.01 to 1.2 x 10(6)/unit on day 1. CONCLUSION: Monocytes present in platelet concentrates exhibit features of activation. Monocyte activation is present following the preparation of platelet concentrates, implicating the manufacturing process in its development. Increased IL-6 and IL-1beta levels during platelet concentrate storage are commonly associated with a higher monocyte count. However, no direct association could be identified between the extent of monocyte activation and the level of cytokine release.