Concurrent panel session 2: Health challenges facing Las Vegas

Moderator: Marcia Turner, NSHE Health Science System Scribe: Candace Griffith, UNLV Department of Sociology Conference white paper & Full summary of panel session, 8 page

Ploidy Variation in Multinucleate Cells Changes Under Stress

Ploidy variation is found in contexts as diverse as solid tumors, drug resistance in fungal infection, and normal development. Altering chromosome or genome copy number supports adaptation to fluctuating environments but is also associated with fitness defects attributed to protein imbalances. Both aneuploidy and polyploidy can arise from multinucleate states after failed cytokinesis or cell fusion. The consequences of ploidy variation in syncytia are difficult to predict because protein imbalances are theoretically buffered by a common cytoplasm. We examined ploidy in a naturally multinucleate fungus, Ashbya gossypii. Using integrated lac operator arrays, we found that chromosome number varies substantially among nuclei sharing a common cytoplasm. Populations of nuclei range from 1N to \u3e4N, with different polyploidies in the same cell and low levels of aneuploidy. The degree of ploidy variation increases as cells age. In response to cellular stress, polyploid nuclei diminish and haploid nuclei predominate. These data suggest that mixed ploidy is tolerated in these syncytia; however, there may be costs associated with variation as stress homogenizes the genome content of nuclei. Furthermore, the results suggest that sharing of gene products is limited, and thus there is incomplete buffering of ploidy variation despite a common cytosol

Unified one-fluid formulation for incompressible flexible solids and multiphase flows: Application to hydrodynamics using the immersed structural potential method (ISPM)

In this paper, we present a two-dimensional computational framework for the simulation of fluid-structure interaction problems involving incompressible flexible solids and multiphase flows, further extending the application range of classical immersed computational approaches to the context of hydrodynamics. The proposed method aims to overcome shortcomings such as the restriction of having to deal with similar density ratios among different phases or the restriction to solve single-phase flows. First, a variation of classical immersed techniques, pioneered with the immersed boundary method (IBM), is presented by rearranging the governing equations, which define the behaviour of the multiple physics involved. The formulation is compatible with the “one-fluid” formulation for two-phase flows and can deal with large density ratios with the help of an anisotropic Poisson solver. Second, immersed deformable structures and fluid phases are modelled in an identical manner except for the computation of the deviatoric stresses. The numerical technique followed in this paper builds upon the immersed structural potential method developed by the authors, by adding a level set–based method for the capturing of the fluid-fluid interfaces and an interface Lagrangian-based meshless technique for the tracking of the fluid-structure interface. The spatial discretisation is based on the standard marker-and-cell method used in conjunction with a fractional step approach for the pressure/velocity decoupling, a second-order time integrator, and a fixed-point iterative scheme. The paper presents a wide d range of two-dimensional applications involving multiphase flows interacting with immersed deformable solids, including benchmarking against both experimental and alternative numerical schemes

Heterogeneity in Mitochondrial Morphology and Membrane Potential Is Independent of the Nuclear Division Cycle in Multinucleate Fungal Cells

In the multinucleate filamentous fungus Ashbya gossypii, nuclei divide asynchronously in a common cytoplasm. We hypothesize that the division cycle machinery has a limited zone of influence in the cytoplasm to promote nuclear autonomy. Mitochondria in cultured mammalian cells undergo cell cycle-specific changes in morphology and membrane potential and therefore can serve as a reporter of the cell cycle state of the cytoplasm. To evaluate if the cell cycle state of nuclei in A. gossypii can infl

PCBs, Mercury and Organochlorine Concentrations in Lake Trout, Walleye, and Whitefish from Selected tribal fisheries of the upper Great Lakes Region

The purpose of this study was to determine the concentrations of environmental contaminants in the edible portion of fish tissue consumed by Ojibwa residing in the Upper Great Lakes region. Lake trout, whitefish, and walleye were collected from Lake Superior, Lake Huron, Lake Michigan, and selected inland lakes. These fish were harvested by either commercial fishing or spearfishing techniques and analyzed for environmental contaminants. Samples were pooled by species and location of collection and were analyzed as composites. The concentrations of congener-specific polychlorinated biphenyl (PCB), total mercury, and 17 other organochlorine compounds of the pooled samples were determined using gas chromatographic and atomic absorption techniques. Differences were noted in both the concentration and composition of contaminants depending on the geographic location of collection and the species examined. Lake trout and whitefish contained higher concentrations of organochlorine compounds than did walleye; and samples from Lakes Michigan and Huron had much higher concentrations than did Lake Superior fish. Conversely, mercury was much higher in walleye (580 ppb) when compared with lake trout (117 ppb) and whitefish (10 ppb). Several PCB congeners were commonly found in all fish samples; these included PCBs 138 + 163, 153, 66 + 95, 118, 77 + 110, 180, and 101. Lake trout accumulated the highly chlorinated PCB congeners, whereas walleye and whitefish accumulated certain lower tri- and tetrachlorobiphenyl congeners. In conclusion, the fish harvested and consumed by Ojibwa tribal members contained both mercury and organochlorine compounds. The concentrations of contaminants found in fish tissue differed among species and sampling sites. Consequently, it is imperative to sample fish that best represent those being consumed by tribal members and to continue long-term monitoring of fish from ceded waters. Therefore, risk assessment and risk management strategies need to take into account geographic location of the fish and unique preparation methods and to be directed at the contaminant(s) of concern for given locations

Concentrations and Frequencies of Polychlorinated Biphenyl Congeners in a Native American Population who Consumes Great Lakes Fish

OBJECTIVE: Polychlorinated biphenyl congener profiles were examined in serum samples from 61 Native American (Ojibwa) volunteers who regularly consumed fish harvested from the Great Lakes region. A total of 93 peaks are reported which represent 126 individual chlorobiphenyls. RESULTS: When ranked by frequency, 13 peaks comprising single or co-eluting chlorobiphenyls occurred in all 61 samples (a frequency of 100%). These included chlorobiphenyls 138 + 158 + 163, 105 + 132 + 153, 180, 118, 196 + 203, 74, 182 + 187, 199, 183, 114 + 134, 195 + 208, 206, and 194. These 13 peaks also occurred at concentrations higher than those of all other measured chlorobiphenyls, except for the addition of the peak containing chlorobiphenyls 170 and 190, which was below detection in 15% of the samples and ranked fifth in average concentration. The highly chlorinated chlorobiphenyls resembled human serum profiles previously reported in the literature. METHODS: Individual chlorobiphenyls were identified using a gas chromatograph equipped with a 60-meter DB-5 capillary column and electron capture detection. CONCLUSION: When compared to other human residue analyses for fish-eating populations, the Ojibwa samples contained higher proportions of lightly chlorinated and labile chlorobiphenyls such as 8, 16 + 32, 17, 18, 25, 41 + 64 + 71, 33, 52, 110, and 129. These proportions were similar to those found in carp, whitefish, or whitefish livers harvested from the Great Lakes region. These data indicate that regular meals of lower trophic level fish, such as whitefish from the Great Lakes, may distort steady-state human chlorobiphenyl profiles with respect to certain lightly chlorinated or labile chlorobiphenyls

Environmental Contaminants and Cholinesterase Activity in the Brain of Fisher (Martes pennanti) Harvested in Northern Wisconsin

The fisher (Martes pennanti), a member of Mustelidae, was once common in the northern forested region of the upper Great Lakes, including Wisconsin. Fishers are medium sized carnivores (2.5 kg for females; 6.5 kg for males) which feed on a wide range of food items (Powell and Zielinski 1994; Powell 1993; Gilbert and Keith, unpublished data) and require closed canopy forests with large diameter trees for den sites (Powell 1994, Thomasma et al 1991, 1994, Wright and Gilbert in prep). Fishers were extirpated from Wisconsin in the 1920’s due to a combination of over-harvest and habitat destruction (Pils 1983, Powell 1994). From 1956 to 1963 fishers were translocated from New York and Minnesota into Wisconsin in order to reestablish a self sustaining population and to achieve porcupine (Erethizon dorsatum) control. Kohn and Creed (1983) concluded that this reestablishment was successful. In 1985 the fisher was designated a game species and the first trapping season in 50 years was established. Harvests initially occurred over a portion of northern Wisconsin but now include the entire northern part of the state