Life Sciences Commons^™

Colony Survivorship In Pogonomyrmex Occidentalis, Western Harvester Ant, In Western Nebraska, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

Little is known about the life span of individual ant colonies (Keeler, 1981), even though the dynamics of some species, such as harvester ants, are crucial to the structure of plant and animal communities (e.g., Brown et al., 1979). This note reports the results of 10 years of observations on a population of harvester ants.

Fifty-six mounds of Pogonomyrmex occidentalis Cresson (Hymenoptera: Formicidae), western harvester ant, were permanently marked with aluminum tags in August 1977. The site, about 1 ha just south of the University of Nebraska's Cedar Point Biological Station, Keith Co., Nebraska, was within a pasture subject to …

Foraging Behavior And Switching By The Grasshopper Sparrow Ammodramus Savannarum Searching For Multiple Prey In A Heterogeneous Environment, Anthony Joern

School of Biological Sciences: Faculty Publications

Switching among four alternative grasshopper species by the grasshop- per sparrow (Ammodramus savannarum) through frequency-dependent predation was ex- amined. Grasshoppers were presented against a heterogeneous natural background in an outdoor aviary where total density was held constant but relative density of each grasshopper species varied. Switching among prey, primarily between two of the four species, and inter-bird variability in switching was observed. Species-specific prefer- ences and interactions among the alternative grasshopper species affected the final diet choice as one grasshopper species was always preferentially selected and another disregarded independent of changes in relative density. Attributes of avian foraging behavior, including: …

Cupular Structure In Paleotropical Castanopsis (Fagaceae), Robert B. Kaul

School of Biological Sciences: Faculty Publications

The structure and some developmental aspects of the cupules of 22 species of paleotropical Castanopsis are discussed and illustrated. Some species have cupules massively invested with strong, sharp spines, but others are less spiny, and some are nearly smooth. Most cupular armament results from spines produced axillary to the valvular scales and basally adnate to them. Columns of scales straddling the sutures between the cupular valves do not become spines, but the numerous scales elsewhere on the valves become somewhat spiny with age. Dehiscence in the spiny-valved species is mostly along the sutures. The smooth cupules of some species have …

Dna Sequencing, Lyle R. Middendorf, John A. Brumbaugh

School of Biological Sciences: Faculty Publications

To sequence long strands of DNA, cloned strands having lengths longer than 100 bases are, in one embodiment, marked on one end with biotin. These strands are divided into 4 aliquots and each aliquot: (1) is uniquely chemically treated to randomly terminate the strands at the non-biotinylated end at a selected type of base; and (2) is moved continuously by electrophoresis through a different one of four identical channels. In the one embodiment, the strands are randomly terminated at a selected base type and they are moved into avidin, which due to high affinity, combines with the biotin marked ends …

Continuous, On-Line Dna Sequencing Using Oligodeoxynucleotide Primers With Multiple Fluorophores, John A. Brumbaugh, Lyle R. Middendorf, Daniel L. Grone, J. L. Ruth

School of Biological Sciences: Faculty Publications

A method for sequencing DNA by using a difluoresceinated primer and laser excitation is described. Dideoxy protocols have been determined that provide sequences for 600 bases starting with base 1 with <1% error in a single load. Electrophoresis is at 20 W and the bands are detected 24 cm from the bottom of the loading well with a scanning fluorescence detector. Bands are imaged on a TV screen in two dimensions. The sequences can be read from the TV screen manually or semiautomatically by using a simple software program. The system allows more bases to be read with a lower error rate than any other reported automated sequencing method.

Effect Of Biotin Limitation On The Conversion Of Xylose To Ethanol And Xylitol By Pachysolen Tannophilus And Candida Guilliermondii, Hung Lee, Audrey L. Atkin, Maria F.S. Barbosa, Delbert R. Dorscheid, Henry Schneider

School of Biological Sciences: Faculty Publications

The relative amount of ethanol and xylitol accumulated in aerobic batch cultures of Pachysolen tannophilus and Candida guilliermondii on D-xylose depended on the extent of limitation by biotin. In high biotin media P. tannophilus favored ethanol production over that of xylitol while C. guilliermondii favored xylitol formation. However, as the extent of biotin limitation increased, the ratio of ethanol to xylitol produced by both organisms increased. The results are of interest in efforts to control such ratios.

Extremely Large And Slowly Processed Precursors To The Euglena Light-Harvesting Chlorophyll A/B Binding Proteins Of Photosystem Ii, Arnon Rikin, Steven D. Schwartzbach

School of Biological Sciences: Faculty Publications

Antibody to the Euglena light-harvesting chlorophyll a/b binding protein of photosystem II (LHCPII) immunoprecipitated 207-, 161-, 122-, and 110-kDa proteins from total Euglena proteins pulse-labeled for 10 min with [₃₅S]sulfate. The 25.6- and 27.2-kDa LHCPII were barely detectable in the immunoprecipitate. During a 40-min chase with unlabeled sulfate, the amount of radioactivity in the high molecular mass proteins decreased, and the amount of radioactivity in the 25.6- and 27.2-kDa LHCPII increased with kinetics consistent with a precursor-product relationship. The half-life of the high molecular mass proteins was ≈20 min. The major proteins immunoprecipitated from a nuclease-treated rabbit reticulocyte …

Patterns Of Resource Use By A Drosophilid (Diptera) Leaf Miner On A Native Crucifer, S. K. Collinge, Svata M. Louda

School of Biological Sciences: Faculty Publications

Distribution and damage of Scaptomyza nigrita Wheeler on its host (bittercress, Cardamine cordifolia A. Gray), a native perennial crucifer, were examined over two growing seasons in relation to leaf position. Concentrations of defensive compounds (glucosinolates) and of nutritive compounds (total nitrogen, free amino acids, soluble carbohydrates) were also examined. The fly-host plant relationship was studied in sun and shade habitats at two sites. Oviposition and leaf-mining damage were concentrated on the lower central leaves of a stem in both habitats. These mature leaves have lower glucosinolate concentrations than new leaves. Adult densities and larval feeding damage were consistently and significantly …

Can We Guarantee The Safety Of Genetically Engineered Organisms In The Environment?, Kathleen H. Keeler, Frances E. Sharples

School of Biological Sciences: Faculty Publications

Can we guarantee the safety of genetically engineered organisms in the environment? To anticipate my remarks, the answer to the title question is “No, we cannot guarantee the safety of genetically engineered organisms released into the environment.” Indeed, it is a tenet of the scientific method that nothing can be proved, only disproved. Thus, we can never show that a release will be safe. We could only show that it would be unsafe, if that were the case. However, if the question is posed differently, for example, can we safely release genetically engineered organisms into the environment?, the answer is …