Are U,Ni, and Hg an Environmental Risk within a RCRA/CERCLA Unit on the U.S. Department of Energy's Savannah River Site?

The U.S. Department of Energy's Savannah River Site (SRS) is a former nuclear weapon production facility. From 1954–1985, releases of Al, Cu, Cr, Hg, Ni, Pb, U, and Zn were discharged into the Tims Branch-Steed Pond water system. This study investigates whether metal concentrations in Tims Branch's sediment, biofilm, and other biota exceed screening level risk calculations to determine if remedial actions should be pursued for the Contaminants of Potential Concern (U, Ni, Hg). Transfer factors (TFs) were calculated to determine metal concentration changes throughout lower trophic levels and results were compared with sediment benchmarks to create hazard quotients (HQs) to assess risk and a scientific-management decision point. Most TFs for Ni and U from lower to higher trophic level biota were <1, suggesting no biomagnifications; however HQs > 1 and cumulative distributions showed the majority of the samples exceeded action levels. Elevated TFs and HQs > 1 in the upper trophic levels for Hg indicated a high degree of bioavailability and biomagnification. Monte Carlo resampling analyses supported these empirical results. This system should continue to be closely monitored to ensure that contamination does not move off the SRS.     

A Spatially Explicit Model to Predict Radiocesium Body Burdens of White-Tailed Deer on the U.S. Department of Energy's Savannah River Site

We developed a spatially explicit exposure model to interpolate and predict radiocesium (¹³⁷Cs) body burdens found in white-tailed deer (Odocoileus virginianus) on the U.S. Department of Energy's (USDOE) Savannah River Site (SRS) to gain insight into and differentiate between the main contributing sources of this radionuclide for use in harvest management strategies that focus on minimizing human risk. Hunting has been allowed from permanent stands as a mechanism to manage the deer herd since 1965. All animals are monitored in the field for gross beta and gamma activity levels, providing a spatially explicit dataset. The models described here use the relative locations of the hunt-stands to predict ¹³⁷Cs exposure distributions. We used kriging to create an interpolation surface using average white-tailed deer body burdens. Cross-validations of the kriged surfaces differentiated between sources of ¹³⁷Cs and where deer reside on the SRS. The kriged surfaces, coupled with additional regression analyses, provide a comprehensive assessment of deer's ¹³⁷Cs body burdens with predictive capability that quantifies the scale at which such investigations can be conducted. Although the models are local in scale, the methods presented here can be used as a template for other large areas that are being monitored for radioactive fallout.     

Selective male mortality in the red imported fire ant, Solenopsis invicta

Males in polygyne populations of Solenopsis invicta are primarily sterile diploids and thought to not express the Gp-9 gene coding for a pheromone-binding protein affecting complex social behavior. We examined an aspect of the breeding system hitherto not considered--male Gp-9 genotypes in relation to sperm stored in queens. Four sites with varying frequencies of sympatric monogyne and polygyne colonies were sampled, including sexuals, workers, and broods from four colonies. Most queens were heterozygotes storing B sperm. Although predicted to be common, only 14 of 504 males were B or BB genotypes, suggesting strong selection. Increased frequency of polygyne colonies at each site paralleled increases in queens with b sperm (1.9-32.8%) and of noninseminated queens. The presence of both B and b sperm in 1.9-18.9% of queens, genotype profiles of colonies, and genotypes of offspring from individual queens suggest some frequency of multiple mating. The bb genotype, rather than an obligate, developmental lethal, was present in some queens and common in alates, workers, and brood. Selective mortality of sexuals may affect multiple aspects of the breeding system, including female-mediated dispersal, mating success, and gene flow.     

Comparative vegetative anatomy and systematics of the Oncidiinae (Maxillarieae, Orchidaceae)

Subtribe Oncidiinae comprises a vegetatively heterogeneous assemblage of species that has persistently been incapable of organization. Anatomy was considered to be a possible means to resolve the perplexity of relationships amongst the constituent taxa. The consistent occurrence of a foliar hypodermis, homogeneous mesophyll, conical silica bodies in stegmata, and ubiquitous fibre bundles in leaves provides a matrix for linking the taxa, as do the parenchymatous pith and O-thickened endodermal cell walls in roots. However, the strict consensus of the 40 genera studied was completely unresolved, suggesting that vegetative characters alone are insufficient to assess the relationships amongst these taxa, a conclusion also reached for the remainder of Maxillarieae.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 152 , 91–107.     

The dynamics of food,alcohol and cigarette consumption in Russia during transition

This paper presents evidence on the impact of individual as well as regional characteristics on the dynamics of fat, protein, alcohol and cigarette consumption, and on the diversity of the diet in Russia between 1994 and 2005. All those aspects of nutritional behavior are important inputs to the production of health. A dynamic panel data model is used to estimate demand functions for fat, protein, alcohol, cigarettes and diversity of the diet. The results suggest the existence of strong habits in drinking and smoking, and the absence of habits in fat and protein consumption. We also found evidence of habit formation for food diversity. Comparing nutritional behavior of younger and older consumers, we find significant differences in the demand for fat and cigarettes. Older consumers seem to be more persistent in their drinking and smoking behavior. Similarly, men show higher habit persistence for alcohol and cigarette consumption. The results also suggest that among individual determinants, especially education, income and employment have statistically significant impacts on consumption behavior. Regarding the macroeconomic variables, economic growth is negatively related to protein consumption, while regional unemployment rate is negatively affecting the demand for protein and food diversity. Finally, Russian consumers react to the price changes of alcohol, cigarettes, fat and protein as suggested by theory. Consumer demand for food diversity responds negatively to price changes of alcohol and cigarettes, but positively to the price of fat.     

A Comparison of Field and Molecular Techniques for Sexing Beavers

Abstract: The traditional method of sex identification in beavers (Castor canadensis) by external palpation can be inaccurate. We tested 2 genetic methods for determining sex in beavers, the zinc-finger DNA marker and the Y chromosome-specific sex determining region (SRY) marker. The SRY marker identified sex correctly in 57 of 67 (85%) beavers, whereas the zinc-finger technique was successful less often in only 48 of 67 (72%) animals. Sex was correctly assigned by palpation for 21 of 27 beavers (78%). Beaver studies in which accurate sex identification is critical may benefit by verifying the sex of individuals using one or both of these molecular markers.     

Effects of in situ phosphorus enrichment on the benthos in a subalpine karst stream and implications for bioassessment in nature reserves

Park managers in nature reserves need scientifically defensible and operationally feasible ecological indicators to better manage protected areas for both nature conservation and tourism. Such needs are much more urgent in karst aquatic ecosystems where spectacular natural scenic wonders attract millions of visitors to natural areas with streams and lakes that are particularly vulnerable to nutrient pollution. To identify a set of biotic indicators of phosphorus (P) pollution in a karst stream, we conducted an in situ P enrichment experiment in a nearly pristine karst stream located at a UNESCO world heritage site in China. Our results show that both benthic algal assemblages and macroinvertebrates were sensitive to P enrichment. Changes in diatoms (e.g., Achnanthidium minutissimum, Delicata delicatula) and macroinvertebrates (e.g., collectors) were indicative of P enrichment. The color change of travertine bryophyte beds from creamy white to green was largely due to increase in filamentous green algae such as Zygnema sp., which may provide a visual cue for P enrichment and pollution. Our findings, in conjunction with further studies that directly link these indicators with human disturbance (e.g., tourist activities) throughout the park, could improve the operation of park managers in minimizing tourist-induced nutrient pollution and in operationalizing these indicators in the current environmental monitoring and assessment program.     

Adolescence as a vulnerable period to alter rodent behavior

Induction of HIF-1α by oxygen limitation promotes increased phosphorylation and catalytic depression of mitochondrial pyruvate dehydrogenase (PDH) and an enhanced glycolytic poise in cells. Cobalt chloride and desferrioxamine are widely used as mimics for hypoxia because they increase the levels of HIF-1α. We evaluated the ability of these agents to elicit selected physiological responses to hypoxia as a means to metabolically precondition mammalian cells, but without the detrimental effects of hypoxia. We show that, while CoCl₂ does increase HIF-1α in a dose-dependent manner, it unexpectedly and strikingly decreases PDH phosphorylation at E1α sites 1, 2, and 3 (Ser²⁹³, Ser³⁰⁰, and Ser²³², respectively) in HepG2 cells. This same effect is also observed for site 1 in mouse NIH/3T3 fibroblasts and J774 macrophages. CoCl₂ unexpectedly decreases the mRNA expression for PDH kinase-2 in HepG2 cells, which likely explains the dephosphorylation of PDH observed. And nor does desferrioxamine promote the expected increase in PDH phosphorylation. Dimethyloxaloylglycine (a prolyl hydroxylase inhibitor) performs better in this regard, but failed to promote the stronger effects seen with hypoxia. Consequently, CoCl₂ and desferrioxamine are unreliable mimics of hypoxia for physiological events downstream of HIF-1α stabilization. Our study demonstrates that mimetic chemicals must be chosen with caution and evaluated thoroughly if bona fide cellular outcomes are to be promoted with fidelity.     

Protective effects of osmolytes in cryopreserving adherent neuroblastoma (Neuro-2a) cells

A simple method to cryopreserve adherent monolayers of neuronal cells is currently not available, but the development of this technique could facilitate numerous applications in the field of biomedical engineering, cell line development, and drug screening. However, complex tissues of some exceptional animals survive freezing in nature. These animals are known to accumulate several small molecular weight solutes prior to freezing. Following a similar strategy, we investigated the effects of osmolytes such as trehalose, proline, and sucrose as additives to the traditional cryoprotectant dimethyl sulfoxide (Me₂SO) in modulating the cryopreservation outcome of mouse neuroblastoma (Neuro-2a) cells. Neuro-2a cells adhered to cell culture plates were incubated for 24 h at varying concentrations of trehalose, proline, sucrose and combinations of these compounds. Cells were cryopreserved for 24 h and cell viability post-freezing and thawing was quantified by trypan blue exclusion assay. On average, only 13.5% of adherent cells survived freezing in the presence of 10% Me₂SO alone (control). Pre-incubation of cells with medium containing both trehalose and proline severely decreased cell proliferation, but increased cell recovery to about 53% of control. Furthermore, characterization using Raman microspectroscopy revealed that the addition of both trehalose and proline to 10% Me₂SO substantially increased the size, and altered the nature, of ice crystals formed during freezing. Our results suggest that pre-incubation of Neuro-2a cells with trehalose and proline in combination provides cell protection along with alterations of ice structure in order to increase cell survival post-freezing.