Plio-Pleistocene Glacial Deposits in Northeastern Nebraska: New Exposures and Interpretations

A field trip sponsored by the Nebraska Geological Society. Trip Leaders: Dr. M.R. Voorhies, University of Nebraska State Museum. & Dr. R.G. Goodwin, HWS Technologies Inc. Spring 1989 Recent interpretation of oxygen isotopic data for benthic and planktonic foraminifera recovered during ocean drilling programs suggest that world ice volume was greater than the ice volume of 18 thousand years ago (Late Wisconsinan) approximately 2.5 million years ago (Prentice and Matthews, Geology, November, 1988). This agrees well With biostratigraphic and paleoecologic interepretations drawn from sediment cores obtained from the Arctic Ocean Basin. The latter data suggest complete ice cover of the basin during the period 2.2-2.4 million years ago (Scott et at., G.S.A. Bulletin, February, 1989). John Boollstorff inferred that one or more glacial tills of the North American mid-continent were deposited at this time. BoeUstorff drew his conclusions primarily from subsurface samples and from volcanic ash horizons dated by the fisssion-track method. The purpose of this trip is to examine fossil-bearing outcrops of sand and gravel or silt that are associated With volcanic ash or glacial till and that provide information about the timing of glacier advance into northeastern Nebraska. The trip Will begin at the Knox County Court House, Center, Nebraska at noon on saturday May 6, 1989. Participants are responsible for providing their own transportation

Plio-Pleistocene Glacial Deposits in Northeastern Nebraska: New Exposures and Interpretations

A field trip sponsored by the Nebraska Geological Society. Trip Leaders: Dr. M.R. Voorhies, University of Nebraska State Museum. & Dr. R.G. Goodwin, HWS Technologies Inc. Spring 1989 Recent interpretation of oxygen isotopic data for benthic and planktonic foraminifera recovered during ocean drilling programs suggest that world ice volume was greater than the ice volume of 18 thousand years ago (Late Wisconsinan) approximately 2.5 million years ago (Prentice and Matthews, Geology, November, 1988). This agrees well With biostratigraphic and paleoecologic interepretations drawn from sediment cores obtained from the Arctic Ocean Basin. The latter data suggest complete ice cover of the basin during the period 2.2-2.4 million years ago (Scott et at., G.S.A. Bulletin, February, 1989). John Boollstorff inferred that one or more glacial tills of the North American mid-continent were deposited at this time. BoeUstorff drew his conclusions primarily from subsurface samples and from volcanic ash horizons dated by the fisssion-track method. The purpose of this trip is to examine fossil-bearing outcrops of sand and gravel or silt that are associated With volcanic ash or glacial till and that provide information about the timing of glacier advance into northeastern Nebraska. The trip Will begin at the Knox County Court House, Center, Nebraska at noon on saturday May 6, 1989. Participants are responsible for providing their own transportation

Pamphlet to Accompany Geologic Map GMC-34: Geologic Map of the O’Neill 1º x 2º Quadrangle, Nebraska, with Configuration Maps of Surfaces of Formations

This map is necessarily generalized. It is based primarily on data from 7.5’ surficial geologic quadrangle maps of the map area prepared by the authors principally from 1991 to 2000, from Voorhies (unpub. data, 1974), as well as data from test-hole drilling done across the quadrangle by the Conservation and Survey Division, University of Nebraska, and its cooperators over many years since the 1930s. For more detailed information, consult the geologic data files of the Conservation and Survey Division, School of Natural Resources, University of Nebraska-Lincoln. The quadrangle is mostly covered by vegetation and Holocene sediments. Limited good exposures of older sediments and bedrock occur usually in road cuts, in quarry and pit excavations, on valley sides, on stream and river cut banks, and in isolated erosional remnants on uplands. Users of this map should remember that the scale of the map is small and allows only a general picture of the geology of the quadrangle to be depicted. Users should check with the authors regarding specific sites and, if necessary, do field checks of these sites. As new data become available the authors intend to update the data sets used in preparation of this quadrangle text and maps and to issue refined versions, if necessary. The earliest geologic map that included part of the study area was published by Charles Lyell in 1845 (Diffendal, 1993). Other geologic maps at different scales that include all or parts of the map area are by Darton (1899, 1905), Condra (1908), Schulte (1952), Mendenhall (1953), Lampshire (1956), Burchett (1986), Weeks and Gutentag, (1981), Weeks and others (1988), Swinehart and others (1994), and Diffendal and Voorhies (1994). Geologic maps of adjacent areas in Nebraska and South Dakota include Burchett and others (1975), Burchett and others (1988), Diffendal (1991), and Souders (2000) for Nebraska and Stevenson and Carlson (1950, 1951), Baker and others (1952), Collins and French (1958), Schoon and Sevon (1958), Stevenson and others (1958), and Stevenson and others (1959) for parts of South Dakota. Detailed groundwater investigations and associated stratigraphic test drilling (of parts or all of the map area) were done by Darton (1905), Condra (1908), Reed (1944), Keech and Schreurs (1953, 1954), Cronin and Newport (1956), Reed (1957), Smith (1958), Newport (1959), Souders and Shaffer (1969), Souders (1976), Gutentag and Weeks (1980), Luckey and others (1981), Lawton and Hiergesell (1988), Weeks and others (1988), Pierce (1989), Rahn and David (1989), Burchett and Smith (1992), and Lackey and others (1995, 1998a, 1998b, 2000)

Modes of Metabolic Compensation during Mitochondrial Disease Using the Drosophila Model of ATP6 Dysfunction

Numerous mitochondrial DNA mutations cause mitochondrial encephalomyopathy: a collection of related diseases for which there exists no effective treatment. Mitochondrial encephalomyopathies are complex multisystem diseases that exhibit a relentless progression of severity, making them both difficult to treat and study. The pathogenic and compensatory metabolic changes that are associated with chronic mitochondrial dysfunction are not well understood. The Drosophila ATP61 mutant models human mitochondrial encephalomyopathy and allows the study of metabolic changes and compensation that occur throughout the lifetime of an affected animal. ATP61animals have a nearly complete loss of ATP synthase activity and an acute bioenergetic deficit when they are asymptomatic, but surprisingly we discovered no chronic bioenergetic deficit in these animals during their symptomatic period. Our data demonstrate dynamic metabolic compensatory mechanisms that sustain normal energy availability and activity despite chronic mitochondrial complex V dysfunction resulting from an endogenous mutation in the mitochondrial DNA. ATP61animals compensate for their loss of oxidative phosphorylation through increases in glycolytic flux, ketogenesis and Kreb's cycle activity early during pathogenesis. However, succinate dehydrogenase activity is reduced and mitochondrial supercomplex formation is severely disrupted contributing to the pathogenesis seen in ATP61 animals. These studies demonstrate the dynamic nature of metabolic compensatory mechanisms and emphasize the need for time course studies in tractable animal systems to elucidate disease pathogenesis and novel therapeutic avenues

Negative phenotypic and genetic associations between copulation duration and longevity in male seed beetles

Reproduction can be costly and is predicted to trade-off against other characters. However, while these trade-offs are well documented for females, there has been less focus on aspects of male reproduction. Furthermore, those studies that have looked at males typically only investigate phenotypic associations, with the underlying genetics often ignored. Here, we report on phenotypic and genetic trade-offs in male reproductive effort in the seed beetle, Callosobruchus maculatus. We find that the duration of a male's first copulation is negatively associated with subsequent male survival, phenotypically and genetically. Our results are consistent with life-history theory and suggest that like females, males trade-off reproductive effort against longevity

Robust Metabolic Responses to Varied Carbon Sources in Natural and Laboratory Strains of Saccharomyces cerevisiae

Understanding factors that regulate the metabolism and growth of an organism is of fundamental biologic interest. This study compared the influence of two different carbon substrates, dextrose and galactose, on the metabolic and growth rates of the yeast Saccharomyces cerevisiae. Yeast metabolic and growth rates varied widely depending on the metabolic substrate supplied. The metabolic and growth rates of a yeast strain maintained under long-term laboratory conditions was compared to strain isolated from natural condition when grown on different substrates. Previous studies had determined that there are numerous genetic differences between these two strains. However, the overall metabolic and growth rates of a wild isolate of yeast was very similar to that of a strain that had been maintained under laboratory conditions for many decades. This indicates that, at in least this case, metabolism and growth appear to be well buffered against genetic differences. Metabolic rate and cell number did not co-vary in a simple linear manner. When grown in either dextrose or galactose, both strains showed a growth pattern in which the number of cells continued to increase well after the metabolic rate began a sharp decline. Previous studied have reported that O2 consumption in S. cerevisiae grown in reduced dextrose levels were elevated compared to higher levels. Low dextrose levels have been proposed to induce caloric restriction and increase life span in yeast. However, there was no evidence that reduced levels of dextrose increased metabolic rates, measured by either O2 consumption or CO2 production, in the strains used in this study

Glial Hsp70 Protects K+ Homeostasis in the Drosophila Brain during Repetitive Anoxic Depolarization

Neural tissue is particularly vulnerable to metabolic stress and loss of ion homeostasis. Repetitive stress generally leads to more permanent dysfunction but the mechanisms underlying this progression are poorly understood. We investigated the effects of energetic compromise in Drosophila by targeting the Na+/K+-ATPase. Acute ouabain treatment of intact flies resulted in subsequent repetitive comas that led to death and were associated with transient loss of K+ homeostasis in the brain. Heat shock pre-conditioned flies were resistant to ouabain treatment. To control the timing of repeated loss of ion homeostasis we subjected flies to repetitive anoxia while recording extracellular [K+] in the brain. We show that targeted expression of the chaperone protein Hsp70 in glial cells delays a permanent loss of ion homeostasis associated with repetitive anoxic stress and suggest that this is a useful model for investigating molecular mechanisms of neuroprotection

Achieving temperature-size changes in a unicellular organism.

The temperature-size rule (TSR) is an intraspecific phenomenon describing the phenotypic plastic response of an organism size to the temperature: individuals reared at cooler temperatures mature to be larger adults than those reared at warmer temperatures. The TSR is ubiquitous, affecting >80% species including uni- and multicellular groups. How the TSR is established has received attention in multicellular organisms, but not in unicells. Further, conceptual models suggest the mechanism of size change to be different in these two groups. Here, we test these theories using the protist Cyclidium glaucoma. We measure cell sizes, along with population growth during temperature acclimation, to determine how and when the temperature-size changes are achieved. We show that mother and daughter sizes become temporarily decoupled from the ratio 2:1 during acclimation, but these return to their coupled state (where daughter cells are half the size of the mother cell) once acclimated. Thermal acclimation is rapid, being completed within approximately a single generation. Further, we examine the impact of increased temperatures on carrying capacity and total biomass, to investigate potential adaptive strategies of size change. We demonstrate no temperature effect on carrying capacity, but maximum supported biomass to decrease with increasing temperature