Life Sciences Commons^™

Reproductive Structure And Organogenesis In A Cottonwood, Populus Deltoides (Salicaceae), Robert B. Kaul

School of Biological Sciences: Faculty Publications

The organogenesis of inflorescences, flowers, and fruits was followed for two years in a male and a female tree of eastern cottonwood, Populus deltoides. Soon after anthesis, an inflorescence for the next year is initiated as a continuation of the apical meristem in most axillary buds of the extension shoot of the current year. Bract and then floral primordia arise helically, and by the end of summer all floral appendages are evident. Individual perianth parts are evident early in ontogeny but not at anthesis; they are vascularized independently by distal traces of discrete vascular strands that also serve the …

Repeatability Of Maximal Aerobic Performance In Belding’S Ground Squirrels, Spermophilus Beldingi, M. A. Chappell, Gwendolyn C. Bachman, J. P. Odell

School of Biological Sciences: Faculty Publications

1. The repeatability of a trait is a critical factor in determining how that trait is affected by natural selection. We examined the repeatability of a key physiological trait, maximum oxygen consumption (VO_2max), in a wild population of Belding’s Ground Squirrels, Spermophilus beldingi. VO_2max is an integrated measure of organismal metabolic performance. It can be intuitively related to fitness because it sets an upper limit to sustainable power output during ecologically important activites such as locomotion and thermoregulatory heat production.

2. We used respirometry to determine VO_2max during exercise and thermogenesis. Exercise VO …

Introduction From The Changing Prairie: North American Grasslands, Anthony Joern, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

Preserving remaining North American grasslands requires a multiability approach. In this book, we investigate three aspects of an admittedly larger problem: (1) how we as humans perceive grasslands; (2) the ecology of grasslands, in order to define the framework within which conservation and preservation efforts must operate; and (3) conservation issues. Additional sociological, economic, philosophical, and cultural considerations will provide important additional insights to preserving and managing grasslands, but are not included here. By restricting our focus to only three issues, we feel that we can provide a basic, but appropriate, understanding of grassland ecosystems for the prairie enthusiast. This …

Purification, Characterization, And Submitochondrial Localization Of A 58-Kilodalton Nad(P)H Dehydrogenase, Michael H. Luethy, Jay J. Thelen, Andrew F. Knudten, Thomas Elthon

School of Biological Sciences: Faculty Publications

An NADH dehydrogenase activity from red beet (Beta vulgaris 1.) root mitochondria was purified to a 58-kD protein doublet. An immunologically related dehydrogenase was partially purified from maize (Zea mays L. 873) mitochondria to a 58-kD protein doublet, a 45-kD protein, and a few other less prevalent proteins. Polyclonal antibodies prepared against the 58-kD protein of red beet roots were found to immunoprecipitate the NAD(P)H dehydrogenase activity. The antibodies cross-reacted to similar proteins in mitochondria from a number of plant species but not to rat liver mitochondrial proteins. The polyclonal antibodies were used in conjunction with maize mitochondrial fractionation to …

Getting The Lay Of The Land: Introducing North American Native Grasslands, Anthony Joern, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

The expected catastrophic extinction of species (already under way in many places) will alter the planet’s biological diversity so profoundly that, at the known rate of extinction, it will take millions of years to recover. Yet few ecologists study extinction. Indeed, very little ecology deals with any processes that last more than a few years, involve more than a handful of species, and cover an area of more than a few hectares. The temporal, spatial and organizational scales of most ecological studies are such that one can read entire issues of major journals and see no hint of impending catastrophe. …

Preface From The Changing Prairie: North American Grasslands, Kathleen H. Keeler, Anthony Joern

School of Biological Sciences: Faculty Publications

North American grasslands have figured prominently in our North American heritage. Prairies first provided significant barriers to westward expansion, and then offered both economic and sociological opportunity, as well as heartache, for settlers. Many artists have gained significant inspiration from the beauty as well as the harshness of this region and its biota. And because of ideal climate and soil conditions, these grasslands have provided the agricultural foundation of which much of the economic growth and stability of the United States has historically depended.

Yet many see North American prairies as beautiful only when manipulated or exploited: Green croplands or …

Syrphids As Natural Enemies Of Cereal Aphids In Germany: Aspects Of Their Biology And Efficacy In Different Years And Regions, Brigitte Tenhumberg, Hans-Michael Poehling

School of Biological Sciences: Faculty Publications

An evaluation was made of the influence of aphidophagous syrphid larvae on the population dynamics of cereal aphids in winter wheat in Germany, using both field records and published information. The peak density of aphid populations was significantly dependent on aphid abundance at the time syrphid larvae became active, a fact indicating the high predation potential of the beneficials as well as the importance of synchronization. The level of aphid infestation was generally lower in southern than in northern Germany. This difference may result from syrphid larvae being 2-3 weeks earlier in southern Germany, when aphid numbers were only half …

The Majority Of Yeast Upf1 Co-Localizes With Polyribosomes In The Cytoplasm, Audrey L. Atkin, Nicola Altamura, Peter Leeds, Michael R. Culbertson

School of Biological Sciences: Faculty Publications

In Saccharomyces cerevisiae the UPF1 protein is required for nonsense-mediated mRNA

decay, the accelerated turnover of mRNAs containing a nonsense mutation. Several lines

of evidence suggest that translation plays an important role in the mechanism of

nonsense mRNA decay, including a previous report that nonsense mRNAs assemble in

polyribosomes. In this study we show that UPF1 and ribosomal protein Li co-localize in

the cytoplasm and that UPF1 co-sediments with polyribosomes. To detect UPF1, three

copies of the influenza hemagglutinin epitope were placed at the C-terminus. The tagged

protein, UPF1-3EP, retains 86% (± 5%) of function. Using immunological detection, we

found …

Estimating Predatory Efficiency Of Episyrphus Balteatus (Diptera: Syrphidae) In Cereal Fields, Brigitte Tenhumberg

School of Biological Sciences: Faculty Publications

A model was developed to estimate the effect of predation by Episyrphus balteatus larvae on aphid populations in fields of winter wheat. Feeding rate of syrphid larvae was estimated from experiments in field cages using a Holling type-III function. During larval development, syrphids consumed a maximum of 396 aphids, which is only half the potential feeding rate reported from laboratory experiments. The lower consumption rate in the field may be attributed to the additional time required by the predators to find prey. Isoclines derived from the model were used to estimate the abundance of syrphid larvae necessary to prevent further …

Rna Determinants Of Junction Site Selection In Rna Virus Recombinants And Defective Interfering Rnas, K. Andrew White, Thomas Jack Morris

School of Biological Sciences: Faculty Publications

RNA recombination plays an important role in the diversification and evolution of RNA viruses. Most of these events are believed to be mediated by an actively copying viral replicase switching from a donor template to an acceptor template, where it resumes synthesis. In addition, Intramolecular replicase-mediated events (I.e., rearrangements) can lead to the generation of replicable deleted forms of a viral genome, termed defective interfering (DI) RNAs. To gain further insight into the recombination process, the effect of various primary and secondary structures on recombination site selection in vivo was examined using plant RNA tombusviruses. The effect of sequence Identity …

Isolation, Sequencing, And Analysis Of A 14-3-3 Brain Protein Homolog From Pea (Pisum Sativum L.), Bratislav Stankovic, Ana Garit-Stankovic, Christopher M. Smith, Eric Davies

School of Biological Sciences: Faculty Publications

Initially identified as acidic, homodimeric proteins abundantly and preferentially present in mammalian brain neurotransmitter complexes, the eukaryotic 14-3-3 homologs appear to be ubiquitous and highly conserved among highly diverse organisms, including Xenopus, Drosophila, and Saccharomyces (Aitken et al., 1992). They have also been isolated, cloned, and sequenced from various plants, such as Arabidopsis (Lu et al., 1992), Oenotkera, Spinacea (Hirsch et al., 1992), Zea (De Vetten et al., 1992), Lycopersicon (Laughner et al., 19941, Hordeum (Brandt et al., 19921, and Oyza (Kidou et al., 1993). Although there are no available sequence data in the GenBank (version 94-5), immunoprecipitation experiments suggest …

Submaximal Oviposition Rates In A Mymarid Parasitoid: Choosiness Should Not Be Ignored, Amos Bouskila, Ian C. Robertson, Michael E. Robinson, Bernard D. Roitberg, Brigitte Tenhumberg, Andrew J. Tyre, Ed Vanranden

School of Biological Sciences: Faculty Publications

Cronin and Strong (1993a, b) examined the oviposition behavior of Anagarus delicatus Dozier (Hymenoptera: Mymaridae), an egg parasitoid of the leafhopper Prokelisia marginate Van Duzee (Homoptera: Delphacidae). They reported oviposition rates that were lower than predicted if the rate of egg-laying was maximized. Cronin and Strong (1993a) considered, and subsequently rejected, several “rules of thumb” (Stephens and Krebs 1986) as explanations for the observed patterns of patch departure. They observed that hosts on leaves experience density-independent mortality due to leaf senescence. Based on that, they advanced the hypothesis that submaximal oviposition rates in A. delicatus are best explained as risk-spreading …

Population Processes, Kathleen H. Keeler, Anthony Joern

School of Biological Sciences: Faculty Publications

Within the prairies, myriad populations of plants, insects, small mammals, and other organisms form distinct levels of organization. The physical forces of weather and fire and the complex networks of species interactions control each species’s structure and dynamics and determine its abundance or rarity. Variation in population dynamics and interactions over time and space determine the distribution and abundance of species, and ultimately the composition and dynamics of entire prairie communities.

To the casual observer, plant populations on prairies may seem quite static, like museums containing a diverse collection of specimens that can be seen again and again on repeated …