16S rDNA clone library analysis was used to identify bacterial biodiversity in a variety of sea-ice microbial communities (SIMCO). DNA was extracted from seven Antarctic sea-ice samples and one Arctic sea-ice sample and 16S rDNA PCR-amplified using universal and Archaea-specific primers. Recombinant 16S rDNA clones were obtained and dereplicated using restriction fragment length polymorphism analysis (RFLP). After RFLP analysis, 100 distinct phylotypes (a unique clone or group of clones with sequence similarity of >0.98) were defined. From the clone libraries 16S rDNA sequences of bacterial and eukaryotic origin were detected, however Archaea were not detected either with universal or Archaea-specific 16S rDNA primer sets. Bacterial phylotypes grouped within the alpha and gamma proteobacteria, the Cytophaga-Flavobacterium-Bacteroides division, the Gram-Positive bacteria and the orders Chlamydiales and Verrucomicrobiales. The majority of bacterial phylotypes were affiliated with heterotrophic taxa and many grouped closely with cultivated genera and species. Eukaryotic clones were affiliated with a variety of autotrophic and heterotrophic nanoplankton and included a large number of chloroplast 16S rDNA genes. The findings of this investigation corroborated culture data indicating bacterial biodiversity increased in SIMCO displaying high levels of primary production, however the bacterial communities within SIMCO were highly heterogeneous at the genus/species-level between different samples. A comparison of Antarctic and Arctic SIMCO revealed certain sea-ice dwelling bacterial genera are common at both poles.

Experimental models of sepsis using endotoxin challenges, including studies with sensitized animals with D-galactosamine, have largely contributed to the basic rationale for innovative clinical trials in human septic shock, which have, to date, failed. The ability of these models to reproduce human disease has been highly discussed. We report here that the widely used D-galactosamine/LPS model does not account for septic shock. Treatment with YVAD-CMK, a potent tetrapeptide inhibitor of caspases of the interleukin (IL)-1beta converting enzyme (ICE) family, protects from LPS-induced liver apoptosis and mortality in D-galactosamine-sensitized mice when administered either before or up to 2 h after the lethal challenge. This curative effect is related to complete inhibition of caspase-3 activity in the liver. However, YVAD-CMK does not affect LPS-induced release of IL-1beta and does not protect from a lethal dose of LPS in unsensitized mice. These experiments demonstrate the difference between these two widely recognized experimental models of sepsis. LPS toxicity in D-galactosamine-treated mice, leading to blocked gene transcription, results from tumor necrosis factor (TNF)-alpha-induced caspase-3-dependent liver injury, not from the systemic inflammatory response. These results provide evidence that inhibitors of the ICE caspase family can prevent or even overcome the ongoing hepatic injury induced by TNF-alpha during sepsis, ischemia-reperfusion, or severe hepatitis.

In this study, we found that the denaturation of proteins during freezing is closely related to surface-induced denaturation. Several proteins with varying sensitivities to freezing were tested, and the results were compared with susceptibilities to surface denaturation in unfrozen aqueous solution. Also, the influence of the surfactant Tween 80 on the denaturation of each of the proteins was examined during freeze-thawing, as were the effects of Tween 80 and several other surfactants on the stability of lactate dehydrogenase. Proteins formed insoluble precipitates when they were subjected to a quench cooling by dipping in liquid nitrogen, although freezing followed by supercooling caused less precipitation. A strong correlation (r = 0.99) was observed between the tendency of a protein to freeze denature and its tendency to surface denature. Also, the addition of small amounts of surface-active agents protected proteins from both freeze- and surface-induced denaturation. Freeze-induced denaturation of IL-1ra at the ice-water interface during freeze-drying was effectively prevented by adding a small amount of Tween 80. These results suggest that the denaturation of proteins during freeze-thawing can be ascribed primarily to the increase in the area of the ice-water interface during freezing.

Freeze substitution is a process for low temperature dehydration and fixation of rapidly frozen cells that usually takes days to complete. New methods for freeze substitution have been developed that require only basic laboratory tools: a platform shaker, liquid nitrogen, a metal block with holes for cryotubes and an insulated container such as an ice bucket. With this equipment, excellent freeze substitution results can be obtained in as little as 90 min for cells of small volume such as bacteria and tissue culture cells. For cells of greater volume or that have significant diffusion barriers such as cuticles or thick cell walls, one can extend the time to 3 h or more with dry ice. The 3-h method works well for all manner of specimens, including plants and Caenorhabditis elegans as well as smaller samples. Here, we present the basics of the techniques and some results from Nicotiana leaves, C. elegans adult worms, Escherichia coli and baby hamster kidney tissue culture cells.

3,4-Methylenedioxymethamphetamine (MDMA or "Ecstasy") was first synthesised 80 years ago, but has recently received prominence as an illegally synthesised recreational drug of abuse. There is a widely held belief among misusers that it is safe. In the last 2-3 years there have been a number of reports of the drug producing severe acute toxicity and death and there are concerns that it may cause long term toxic damage to 5-hydroxytryptamine (5-HT) nerve terminals. There is a considerable literature on the acute pharmacological effects of MDMA in experimental animals, and this is reviewed. The drug produces both hyperthermia and the "serotonin syndrome", a series of behavioural changes which result from increased 5-HT function. Acute clinical toxicity problems following MDMA ingestion also include hyperthermia and the appearance of the serotonin syndrome. The hyperthermia appears to precipitate other severe clinical problems and the outcome can be fatal. In agreement with others, we suggest that the recent increase in the number of reports of MDMA toxicity probably results from the widespread use of the drug at all night dance parties or "raves". The phenomenon of amphetamine aggregation toxicity in mice was reported 40 years ago. If applicable to MDMA-induced toxicity in humans, all the conditions necessary to induce or enhance toxicity are present at raves: crowded conditions (aggregation), high ambient temperature, loud noise and dehydrated subjects. Administration of MDMA to rodents and non-human primates results in a long term neurotoxic decrease in 5-HT content in several brain regions and there is clear biochemical and histological evidence that this reflects neurodegeneration of 5-HT terminals. Unequivocal data demonstrating that similar changes occur in human brain do not exist, but limited and indirect clinical evidence gives grounds for concern. There are also data suggesting that long term psychiatric changes can occur, although there are problems of interpretation and these are reviewed. Suggestions for the rational treatment of the acute toxicity are made on the basis of both pharmacological studies in animals and current clinical practice. Cases presenting clinically are usually emergencies and unlikely to allow carefully controlled studies. Proposals include decreasing body temperature (possibly with ice), the use of dantrolene and anticonvulsant and sedative medication, particularly benzodiazepines. The use of neuroleptics requires care because of the theoretical risk of producing the neuroleptic malignant syndrome and the possibility of precipitating seizures. In rats, chlormethiazole antagonises the hyperthermia produced by MDMA and has been shown clinically to block MDMA-induced convulsive activity.

Inulin and oligofructose belong to a class of carbohydrates known as fructans. The main sources of inulin and oligofructose that are used in the food industry are chicory and Jerusalem artichoke. Inulin and oligofructose are considered as functional food ingredients since they affect the physiological and biochemical processes in rats and human beings, resulting in better health and reduction in the risk of many diseases. Experimental studies have shown their use as bifidogenic agents, stimulating the immune system of the body, decreasing the pathogenic bacteria in the intestine, relieving constipation, decreasing the risk of osteoporosis by increasing mineral absorption, especially of calcium, reducing the risk of atherosclerosis by lowering the synthesis of triglycerides and fatty acids in the liver and decreasing their level in serum. These fructans modulate the hormonal level of insulin and glucagon, thereby regulating carbohydrate and lipid metabolism by lowering the blood glucose levels; they are also effective in lowering the blood urea and uric acid levels, thereby maintaining the nitrogen balance. Inulin and oligofructose also reduce the incidence of colon cancer. The biochemical basis of these beneficial effects of inulin and oligofructose have been discussed. Oligofructose are non cariogenic as they are not used by Streptococcus mutans to form acids and insoluble glucans that are the main culprits in dental caries. Because of the large number of health promoting functions of inulin and oligofructose, these have wide applications in various types of foods like confectionery, fruit preparations, milk desserts, yogurt and fresh cheese, baked goods, chocolate, ice cream and sauces. Inulin can also be used for the preparation of fructose syrups.

Insects are the most diverse fauna on earth, with different species occupying a range of terrestrial and aquatic habitats from the tropics to the poles. Species inhabiting extreme low-temperature environments must either tolerate or avoid freezing to survive. While much is now known about the synthesis, biochemistry and function of the main groups of cryoprotectants involved in the seasonal processes of acclimatization and winter cold hardiness (ice-nucleating agents, polyols and antifreeze proteins), studies on the structural biology of these compounds have been more limited. The recent discovery of rapid cold-hardening, ice-interface desiccation and the daily resetting of critical thermal thresholds affecting mortality and mobility have emphasized the role of temperature as the most important abiotic factor, acting through physiological processes to determine ecological outcomes. These relationships are seen in key areas such as species responses to climate warming, forecasting systems for pest outbreaks and the establishment potential of alien species in new environments.

Interleukin 1beta-converting enzyme-like (ICE-like) proteases are important mediators of apoptosis in diverse cell types and organisms. However, the role of these proteases in apoptosis cannot be satisfactorily explained on the basis of the physiological functions of their known substrates. Here we show that the C-terminal 42 amino acid peptide of the retinoblastoma (Rb) protein, an important cell cycle regulator with a known anti-apoptotic function, is specifically cleaved off by an ICE-like protease in tumour necrosis factor (TNF)- and staurosporine-induced apoptosis. Cleavage of Rb induced by TNF was blocked in vivo and in vitro by two specific inhibitors of ICE-like proteases, and in vitro by a point mutation (Asp886 to Ala) within the ICE-like protease cleavage site of Rb, (883)DEAD(886). An antibody raised against the C-terminal 15 amino acid peptide of Rb recognized the full-length but not the cleaved form of Rb. The extent of Rb cleavage correlated directly with TNF-induced apoptosis in all tumour cell lines examined. Cleaved Rb bound cyclin D3 and inhibited the transcriptional activity of E2F-1, but failed to bind to the regulatory protein MDM2, which has been implicated in apoptosis. As Rb suppresses cell death and its C-terminus has important regulatory functions, our results suggest that Rb cleavage is an important event in apoptosis.

The last glacial cycle was characterized by substantial millennial-scale climate fluctuations, but the extent of any associated changes in global sea level (or, equivalently, ice volume) remains elusive. Highstands of sea level can be reconstructed from dated fossil coral reef terraces, and these data are complemented by a compilation of global sea-level estimates based on deep-sea oxygen isotope ratios at millennial-scale resolution or higher. Records based on oxygen isotopes, however, contain uncertainties in the range of +/-30 m, or +/-1 degrees C in deep sea temperature. Here we analyse oxygen isotope records from Red Sea sediment cores to reconstruct the history of water residence times in the Red Sea. We then use a hydraulic model of the water exchange between the Red Sea and the world ocean to derive the sill depth-and hence global sea level-over the past 470,000 years (470 kyr). Our reconstruction is accurate to within +/-12 m, and gives a centennial-scale resolution from 70 to 25 kyr before present. We find that sea-level changes of up to 35 m, at rates of up to 2 cm yr(-1), occurred, coincident with abrupt changes in climate.

In addition to stimulating IFN-gamma synthesis, IL-18 also possesses inflammatory effects by inducing synthesis of the proinflammatory cytokines TNF and IL-1beta and the chemokines IL-8 and macrophage inflammatory protein-1alpha. We hypothesized that neutralization of IL-18 would have a beneficial effect in lethal endotoxemia in mice. IL-1beta converting enzyme (ICE)-deficient mice, lacking the ability to process mature IL-18 and IL-1beta, were completely resistant to lethal endotoxemia induced by LPS derived from either Escherichia coli or Salmonella typhimurium. In contrast, both wild-type and IL-1beta-/- mice were equally susceptible to the lethal effects of LPS, implicating that absence of mature IL-18 or IFN-gamma but not IL-1beta in ICE-/- mice is responsible for this resistance. However, IFN-gamma-deficient mice were not resistant to S. typhimurium LPS, suggesting an IFN-gamma-independent role for IL-18. Anti-IL-18 Abs protected mice against a lethal injection of either LPS. Anti-IL-18 treatment also reduced neutrophil accumulation in liver and lungs. The increased survival was accompanied by decreased levels of IFN-gamma and macrophage inflammatory protein-2 in anti-IL-18-treated animals challenged with E. coli LPS, whereas IFN-gamma and TNF concentrations were decreased in treated mice challenged with S. typhimurium. In conclusion, neutralization of IL-18 during lethal endotoxemia protects mice against lethal effects of LPS. This protection is partly mediated through inhibition of IFN-gamma production, but mechanisms involving decreased neutrophil-mediated tissue damage due to the reduction of either chemokines (E. coli LPS) or TNF (S. typhimurium LPS) synthesis by anti-IL-18 treatment may also be involved.

Recent changes in Antarctic seabird populations may reflect direct and indirect responses to regional climate change. The best long-term data for high-latitude Antarctic seabirds (Adélie and Emperor penguins and snow petrels) indicate that winter sea-ice has a profound influence. However, some effects are inconsistent between species and areas, some in opposite directions at different stages of breeding and life cycles, and others remain paradoxical. The combination of recent harvest driven changes and those caused by global warming may produce rapid shifts rather than gradual changes.

IL-12 and IL-18 are IFN-gamma-inducing cytokines. In the present study, the role of endogenous IL-18 in the induction of IFN-gamma by IL-12 was investigated in mice. In the presence of a specific inhibitor of caspase-1 (also known as IL-1beta-converting enzyme, or ICE) IL-12-induced IFN-gamma from splenocytes was reduced by 85%. Using splenocytes from ICE-deficient mice, IL-12-induced IFN-gamma was reduced by 80%. However, the role of ICE was not through processing and release of IL-1beta. Neutralizing anti-IL-18 IgG reduced IL-12-induced IFN-gamma in splenocytes by 85%. Splenocytes cultured in vitro spontaneously released IL-18 into the extracellular compartment over time. Extracellular levels of IL-18 significantly correlated with IL-12-induced IFN-gamma and were reduced in cells obtained from ICE-deficient mice. In vivo, IL-12 administration increased circulating levels of IL-18 in wild-type mice but not in ICE-deficient mice. Both neutralization of IL-18 and ICE deficiency significantly reduced induction of circulating IFN-gamma in mice receiving IL-12. The IL-18 precursor was constitutively expressed in the livers and spleens of untreated mice. Furthermore, administration of IL-12 significantly increased liver-associated IL-18 levels. These data demonstrate that endogenous, ICE-cleaved IL-18 significantly contributes to induction of IFN-gamma by IL-12.

The water-selective pathway through the aquaporin-1 membrane channel has been visualized by fitting an atomic model to a 3.7-A resolution three-dimensional density map. This map was determined by analyzing images and electron diffraction patterns of lipid-reconstituted two-dimensional crystals of aquaporin-1 preserved in vitrified buffer in the absence of any additive. The aqueous pathway is characterized by a size-selective pore that is approximately 4.0 +/- 0.5A in diameter, spans a length of approximately 18A, and bends by approximately 25 degrees as it traverses the bilayer. This narrow pore is connected by wide, funnel-shaped openings at the extracellular and cytoplasmic faces. The size-selective pore is outlined mostly by hydrophobic residues, resulting in a relatively inert pathway conducive to diffusion-limited water flow. The apex of the curved pore is close to the locations of the in-plane pseudo-2-fold symmetry axis that relates the N- and C-terminal halves and the conserved, functionally important N76 and N192 residues.

The experiments recorded above show that in the case of antipneumococcus horse serum or purified antibody the arbitrary immunological procedure (37 degrees for 2 hours, overnight in the ice box) does not permit either the establishment of a true equilibrium or the precipitation of the maximum amount of antibody nitrogen. Analyses of such horse sera for antibody content should therefore be carried out at 0 degrees and the determinations should be allowed to stand in the cold for at least 24 hours in order to insure the completion of the reaction. It is believed that the similarity of the nitrogen: S III ratios in the specific precipitate, whether obtained from whole serum or from purified antibody, and the failure of added serum to influence the amount of nitrogen precipitated show that the absolute chemical method for the estimation of antibody actually measures antibody and not antibody plus a more or less indefinite amount of non-specific protein. An objection to the use of the method is thus shown to be unfounded.

A one-dimensional photochemical model was used to examine the effect of bolide impacts on the oxidation state of Earth's primitive atmosphere. The impact rate should have been high prior to 3.8 Ga before present, based on evidence derived from the Moon. Impacts of comets or carbonaceous asteroids should have enhanced the atmospheric CO/CO2 ratio by bringing in CO ice and/or organic carbon that can be oxidized to CO in the impact plume. Ordinary chondritic impactors would contain elemental iron that could have reacted with ambient CO2 to give CO. Nitric oxide (NO) should also have been produced by reaction between ambient CO2 and N2 in the hot impact plumes. High NO concentrations increase the atmospheric CO/CO2 ratio by increasing the rainout rate of oxidized gases. According to the model, atmospheric CO/CO2 ratios of unity or greater are possible during the first several hundred million years of Earth's history, provided that dissolved CO was not rapidly oxidized to bicarbonate in the ocean. Specifically, high atmospheric CO/CO2 ratios are possible if either: (1) the climate was cool (like today's climate), so that hydration of dissolved CO to formate was slow, or (2) the formate formed from CO was efficiently converted into volatile, reduced carbon compounds, such as methane. A high atmospheric CO/CO2 ratio may have helped to facilitate prebiotic synthesis by enhancing the production rates of hydrogen cyanide and formaldehyde. Formaldehyde may have been produced even more efficiently by photochemical reduction of bicarbonate and formate in Fe(++)-rich surface waters.

Laboratory data indicate that morphine decreases the numbier of peritoneal and alveolar macrophages (Mphi) and compromises their phagocytic capability for immune complexes and bacteria. We hypothesize that morphine decreases the number of, as well as compromises the phagocytic capability of, Mphi by programming their death. We studied the effect of morphine on Mphi apoptosis in vivo as well as in vitro. Peritoneal Mphi harvested from morphine-treated rats showed DNA fragmentation. Morphine enhanced murine Mphi (J 774.16) apoptosis in a dose-dependent manner. Human monocytes treated with morphine showed a classic ladder pattern in gel electrophoretic and end-labeling studies. Morphine promoted nitric oxide (NO) production both under basal and LPS-activated states. N(G)-nitro-L-arginine methyl ester (L-NAME) and N(G)-monomethyl-L-arginine monoacetate (L-NMMA), inhibitors of NO synthase, attenuated the morphine-induced generation of NO by Mphi. Morphine also enhanced Mphi mRNA expression of inducible NO synthase (iNOS). Since morphine-induced Mphi apoptosis was inhibited by L-NAME and L-NMMA, it appears that morphine-induced Mphi apoptosis may be mediated through the generation of NO. Morphine promoted the synthesis of Bax and p53 proteins by Mphi. Moreover, IL-converting enzyme (ICE)-1 inhibitor attenuated morphine-induced Mphi apoptosis. These studies suggest that morphine activates the induction phase of the apoptotic pathway through accumulation of p53. The effector phase of morphine-induced apoptosis appears to proceed through the accumulation of Bax and activation of ICE-1. The present study provides a basis for a hypothesis that morphine may be directly compromising immune function by promoting Mphi apoptosis in patients with opiate addiction.

At any point in time, net protein phosphorylation represents the contribution of protein kinase and protein phosphatase activities affecting a specific site on a given substrate. Preservation of phosphorylated proteins in neural tissues has traditionally included flash-freezing or fresh tissue processing following tissue isolation. Rapid heat inactivation of protein kinases and phosphatases by focused microwave irradiation sacrifice represents another method to preserve, in vivo, brain protein phosphorylation state. In this study, we compared preservation of the phosphorylation state of a variety of phosphoproteins in the brain following sacrifice of mice by decapitation, decapitation into liquid nitrogen and focused microwave irradiation. We found that microwave irradiation generally provided the highest and most consistent levels of protein phosphorylation, regardless of the substrates examined in striatum and hippocampus. In general, flash-freezing resulted in the least preservation of phospho-state with ERK1/2 and CREB showing almost complete dephosphorylation. When regions of freshly decapitated brains were homogenized and incubated on ice for 30 min, ERK1/2 phosphorylation was completely lost, whereas it was well preserved in microwaved samples left at room temperature for 2 h. Loss of ERK1/2 phosphorylation in the fresh samples could not be attributed to substrate proteolysis. Our results indicate that focused microwave irradiation sacrifice may be required to achieve biologically relevant data for the in vivo protein phosphorylation state of many phosphoproteins.

Despite recent advances in population genetic theory and empirical research, the extent of genetic differentiation among natural populations of animals remains difficult to predict. We reviewed studies of geographic variation in mitochondrial DNA in seabirds to test the importance of various factors in generating population genetic and phylogeographic structure. The extent of population genetic and phylogeographic structure varies extensively among species. Species fragmented by land or ice invariably exhibit population genetic structure and most also have phylogeographic structure. However, many populations (26 of 37) display genetic structure in the absence of land, suggesting that other barriers to gene flow exist. In these populations, the extent of genetic structure is best explained by nonbreeding distribution: almost all species with two or more population-specific nonbreeding areas (or seasons) have phylogeographic structure, and all species that are resident at or near breeding colonies year-round have population genetic structure. Geographic distance between colonies and foraging range appeared to have a weak influence on the extent of population genetic structure, but little evidence was found for an effect of colony dispersion or population bottlenecks. In two species (Galapagos petrel, Pterodroma phaeopygia, and Xantus's murrelet, Synthliboramphus hypoleucus), population genetic structure, and even phylogeographic structure, exist in the absence of any recognizable physical or nonphysical barrier, suggesting that other selective or behavioural processes such as philopatry may limit gene flow. Retained ancestral variation may be masking barriers to dispersal in some species, especially at high latitudes. Allopatric speciation undoubtedly occurs in this group, but reproductive isolation also appears to have evolved through founder-induced speciation, and there is strong evidence that parapatric and sympatric speciation occur. While many questions remain unanswered, results of the present review should aid conservation efforts by enabling managers to predict the extent of population differentiation in species that have not yet been studied using molecular markers, and, thus, enable the identification of management units and evolutionary significant units for conservation.

The permanent ice covers of Antarctic lakes in the McMurdo Dry Valleys develop liquid water inclusions in response to solar heating of internal aeolian-derived sediments. The ice sediment particles serve as nutrient (inorganic and organic)-enriched microzones for the establishment of a physiologically and ecologically complex microbial consortium capable of contemporaneous photosynthesis, nitrogen fixation, and decomposition. The consortium is capable of physically and chemically establishing and modifying a relatively nutrient- and organic matter-enriched microbial "oasis" embedded in the lake ice cover.

Bacteria and fungi are ubiquitous in the atmosphere. The diversity and abundance of airborne microbes may be strongly influenced by atmospheric conditions or even influence atmospheric conditions themselves by acting as ice nucleators. However, few comprehensive studies have described the diversity and dynamics of airborne bacteria and fungi based on culture-independent techniques. We document atmospheric microbial abundance, community composition, and ice nucleation at a high-elevation site in northwestern Colorado. We used a standard small-subunit rRNA gene Sanger sequencing approach for total microbial community analysis and a bacteria-specific 16S rRNA bar-coded pyrosequencing approach (4,864 sequences total). During the 2-week collection period, total microbial abundances were relatively constant, ranging from 9.6 x 10(5) to 6.6 x 10(6) cells m(-3) of air, and the diversity and composition of the airborne microbial communities were also relatively static. Bacteria and fungi were nearly equivalent, and members of the proteobacterial groups Burkholderiales and Moraxellaceae (particularly the genus Psychrobacter) were dominant. These taxa were not always the most abundant in freshly fallen snow samples collected at this site. Although there was minimal variability in microbial abundances and composition within the atmosphere, the number of biological ice nuclei increased significantly during periods of high relative humidity. However, these changes in ice nuclei numbers were not associated with changes in the relative abundances of the most commonly studied ice-nucleating bacteria.

Persistent organic pollutants (POPs) encompass an array of anthropogenic organic and elemental substances and their degradation and metabolic byproducts that have been found in the tissues of exposed animals, especially POPs categorized as organohalogen contaminants (OHCs). OHCs have been of concern in the circumpolar arctic for decades. For example, as a consequence of bioaccumulation and in some cases biomagnification of legacy (e.g., chlorinated PCBs, DDTs and CHLs) and emerging (e.g., brominated flame retardants (BFRs) and in particular polybrominated diphenyl ethers (PBDEs) and perfluorinated compounds (PFCs) including perfluorooctane sulfonate (PFOS) and perfluorooctanic acid (PFOA) found in Arctic biota and humans. Of high concern are the potential biological effects of these contaminants in exposed Arctic wildlife and fish. As concluded in the last review in 2004 for the Arctic Monitoring and Assessment Program (AMAP) on the effects of POPs in Arctic wildlife, prior to 1997, biological effects data were minimal and insufficient at any level of biological organization. The present review summarizes recent studies on biological effects in relation to OHC exposure, and attempts to assess known tissue/body compartment concentration data in the context of possible threshold levels of effects to evaluate the risks. This review concentrates mainly on post-2002, new OHC effects data in Arctic wildlife and fish, and is largely based on recently available effects data for populations of several top trophic level species, including seabirds (e.g., glaucous gull (Larus hyperboreus)), polar bears (Ursus maritimus), polar (Arctic) fox (Vulpes lagopus), and Arctic charr (Salvelinus alpinus), as well as semi-captive studies on sled dogs (Canis familiaris). Regardless, there remains a dearth of data on true contaminant exposure, cause-effect relationships with respect to these contaminant exposures in Arctic wildlife and fish. Indications of exposure effects are largely based on correlations between biomarker endpoints (e.g., biochemical processes related to the immune and endocrine system, pathological changes in tissues and reproduction and development) and tissue residue levels of OHCs (e.g., PCBs, DDTs, CHLs, PBDEs and in a few cases perfluorinated carboxylic acids (PFCAs) and perfluorinated sulfonates (PFSAs)). Some exceptions include semi-field studies on comparative contaminant effects of control and exposed cohorts of captive Greenland sled dogs, and performance studies mimicking environmentally relevant PCB concentrations in Arctic charr. Recent tissue concentrations in several arctic marine mammal species and populations exceed a general threshold level of concern of 1 part-per-million (ppm), but a clear evidence of a POP/OHC-related stress in these populations remains to be confirmed. There remains minimal evidence that OHCs are having widespread effects on the health of Arctic organisms, with the possible exception of East Greenland and Svalbard polar bears and Svalbard glaucous gulls. However, the true (if any real) effects of POPs in Arctic wildlife have to be put into the context of other environmental, ecological and physiological stressors (both anthropogenic and natural) that render an overall complex picture. For instance, seasonal changes in food intake and corresponding cycles of fattening and emaciation seen in Arctic animals can modify contaminant tissue distribution and toxicokinetics (contaminant deposition, metabolism and depuration). Also, other factors, including impact of climate change (seasonal ice and temperature changes, and connection to food web changes, nutrition, etc. in exposed biota), disease, species invasion and the connection to disease resistance will impact toxicant exposure. Overall, further research and better understanding of POP/OHC impact on animal performance in Arctic biota are recommended. Regardless, it could be argued that Arctic wildlife and fish at the highest potential risk of POP/OHC exposure and mediated effects are East Greenland, Svalbard and (West and South) Hudson Bay polar bears, Alaskan and Northern Norway killer whales, several species of gulls and other seabirds from the Svalbard area, Northern Norway, East Greenland, the Kara Sea and/or the Canadian central high Arctic, East Greenland ringed seal and a few populations of Arctic charr and Greenland shark.

BACKGROUND

Because people eat most of what they serve themselves, any contextual cues that lead them to over-serve should lead them to over-eat. In building on the size-contrast illusion, this research examines whether the size of a bowl or serving spoon unknowingly biases how much a person serves and eats.

METHODS

The 2 x 2 between-subjects design involved 85 nutrition experts who were attending an ice cream social to celebrate the success of a colleague in 2002. They were randomly given either a smaller (17 oz) or a larger (34 oz) bowl and either a smaller (2 oz) or larger (3 oz) ice cream scoop. After serving themselves, they completed a brief survey as their ice cream was weighed. The analysis was conducted in 2003.

RESULTS

Even when nutrition experts were given a larger bowl, they served themselves 31.0% more (6.25 vs 4.77 oz, F(1, 80) = 8.05, p < 0.01) without being aware of it. Their servings increased by 14.5% when they were given a larger serving spoon (5.77 vs 5.04 oz, F(1, 80)=2.70, p = 0.10).

CONCLUSIONS

People could try using the size of their bowls and possibly serving spoons to help them better control how much they consume. Those interested in losing weight should use smaller bowls and spoons, while those needing to gain weight--such as the undernourished or aged--could be encouraged to use larger ones. Epidemiologic implications are discussed.

Transformation of plasmid DNA into E. coli using the heat shock method is a basic technique of molecular biology. It consists of inserting a foreign plasmid or ligation product into bacteria. This video protocol describes the traditional method of transformation using commercially available chemically competent bacteria from Genlantis. After a short incubation in ice, a mixture of chemically competent bacteria and DNA is placed at 42 degrees C for 45 seconds (heat shock) and then placed back in ice. SOC media is added and the transformed cells are incubated at 37 degrees C for 30 min with agitation. To be assured of isolating colonies irrespective of transformation efficiency, two quantities of transformed bacteria are plated. This traditional protocol can be used successfully to transform most commercially available competent bacteria. The turbocells from Genlantis can also be used in a novel 3-minute transformation protocol, described in the instruction manual.

OBJECTIVE

To determine whether exposure to repetitive head impacts over a single season negatively affects cognitive performance in collegiate contact sport athletes.

METHODS

This is a prospective cohort study at 3 Division I National Collegiate Athletic Association athletic programs. Participants were 214 Division I college varsity football and ice hockey players who wore instrumented helmets that recorded the acceleration-time history of the head following impact, and 45 noncontact sport athletes. All athletes were assessed prior to and shortly after the season with a cognitive screening battery (ImPACT) and a subgroup of athletes also were assessed with 7 measures from a neuropsychological test battery.

RESULTS

Few cognitive differences were found between the athlete groups at the preseason or postseason assessments. However, a higher percentage of the contact sport athletes performed more poorly than predicted postseason on a measure of new learning (California Verbal Learning Test) compared to the noncontact athletes (24% vs 3.6%; p < 0.006). On 2 postseason cognitive measures (ImPACT Reaction Time and Trails 4/B), poorer performance was significantly associated with higher scores on several head impact exposure metrics.

CONCLUSIONS

Repetitive head impacts over the course of a single season may negatively impact learning in some collegiate athletes. Further work is needed to assess whether such effects are short term or persistent.