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Characterization Of A Saccharomyces Cerevisiae Strain Deleted For The Rad27 Gene; A Structural Homolog Of The Rad2 Nucleotide Excision Repair Gene, Michael S. Reagan, Wolfram Siede, Errol C. Friedberg

Biology Faculty Publications

No abstract provided.

Enhancer Trap Technique: A Novel Tool For Identification And Developmental Characterization Of Genes Of Drosophila, Amit Singh

Biology Faculty Publications

The classical technique of mutational screen for identification of genes controlling early development has now approached saturation. A new era in genetic identification and developmental characterization of genes in Drosophila has commenced with the advent of the enhancer trap technique. This technique involves mobilization of a P-lacZ vector to diverse chromosomal locations in the fruit fly genome to bring it under the regulation of developmentally expressed genes or their enhancer elements. The technique offers a strikingly elegant method of gaining entry into fruit fly genes.

Phylogenetic Reanalysis Of Strauch's Osteological Data Set For The Charadriiformes, Philip C. Chu

Biology Faculty Publications

Strauch's (1978) compatibility analysis of relationships among the shorebirds (Charadriiformes) was the first study to examine the full range of charadriiform taxa in a reproducible way. Subsequently Mickevich and Parenti (1980) leveled serious charges against Strauch's characters, method of phylogenetic inference, and results. To account for these charges, Strauch's characters were re-examined and recoded, and parsimony analyses were performed on the revised matrix. A parsimony analysis on 74 taxa from the revised matrix yielded 855 shortest trees, each length = 286 and consistency index = 0.385. In each shortest tree there were two major lineages, a lineage of sandpiper-like birds …

An Improved Method For Chemical Devitellinization Of X-Gal Stained Drosophila Embryos, Amit Singh, Madhuri Kango-Singh, P. Sinha

Biology Faculty Publications

In Drosophila developmental biological studies, X-gal staining is commonly employed to study the spatio-temporal expression of the lacZ reporter gene in the transformed flies or their embryos. Study of the lacZ pattern in embryos often suffers from the lack of an efficient and high yieldirrg technique for devitellinization of X-gal stained embryos. Devitellinization techniques employed during antibody staining, in situ hybridization or embryonic cuticular preparations generally do not give satisfactory results when used for similar purpose in X-gal stained embryos. This results in the flaky appearance of the blue stain. We present here an improved chemical devitellinization technique which gives …

Characterization Of A Mutant Strain Of Saccharomyces Cerevisiae With A Deletion Of The Rad27 Gene, A Structural Homolog Of The Rad2 Nucleotide Excision Repair Gene, Michael S. Reagan, Christopher Pittenger, Wolfram Siede, Errol C. Friedberg

Biology Faculty Publications

We have constructed a strain of Saccharomyces cerevisiae with a deletion of the YKL510 open reading frame, which was initially identified in chromosome XI as a homolog of the RAD2 nucleotide excision repair gene (A. Jacquier, P. Legrain, and B. Dujon, Yeast 8:121–132, 1992). The mutant strain exhibits increased sensitivity to UV light and to the alkylating agent methylmethane sulfonate but not to ionizing radiation. We have renamed the YKL510 open reading frame the RAD27 gene, in keeping with the accepted nomenclature for radiationsensitive yeast mutants. Epistasis analysis indicates that the gene is in the RAD6 group of genes, which …

A Preliminary Catalog Of The Lichen-Forming Fungi Of Nebraska, Robert S. Egan, Richard C. Witt, Yolanda E. Peck, John P. Goeden, Teresa L. Cherney

Biology Faculty Publications

A total of 438 lichen-forming taxa have been reported in the literature from Nebraska. Based on current taxonomic concepts and synonymy we recognized 312 lichen species in this catalog for the state. Published reports oflichen species citing specific collection localities are listed from only 31 counties. These records are concentrated in eastern Nebraska with the largest numbers of species listed from localities in Cass, Lancaster, Saunders, Richardson, and Sarpy counties

Hyla Albopunctata, Rafael O. De Sá

Biology Faculty Publications

Hyla albopunctata is a medium-sized species in the albopunctata group, adults range in size from 42-52 mm SVL (males average 47 mm and females 49 mm). The head is triangular in outline, always longer than wide. The snout is moderately long and acuminate in dorsal view, whereas in lateral view, it is acuminate and protrudes beyond the mandible to form an angle of 45 degrees over the mandible. The canthus rostralis is rounded and distinct, the loreal region is slightly concave, and the internarial region is slightly convex. The eyes are large, approximately twice the diameter of the tympanum. The …

Mechanisms For Soil Moisture Effects On Activity Of Nitrifying Bacteria, John M. Stark, M. K. Firestone

Biology Faculty Publications

Moisture may limit microbial activity in a wide range of environments including salt water, food, wood, biofilms, and soils. Low water availability can inhibit microbial activity by lowering intracellular water potential and thus reducing hydration and activity of enzymes. In solid matrices, low water content may also reduce microbial activity by restricting substrate supply. As pores within solid matrices drain and water films coating surfaces become thinner, diffusion path lengths become more tortuous, and the rate of substrate diffusion to microbial cells declines. We used two independent techniques to evaluate the relative importance of cytoplasmic dehydration versus diffusional limitations in …

Daughter Cells Of Saccharomyces Cerevisiae From Old Mothers Display A Reduced Life Span, Nicanor Austriaco, Brian K. Kennedy, Leonard Guarente

Biology Faculty Publications

The yeast Saccharomyces cerevisiae typically divides asymmetrically to give a large mother cell and a smaller daughter cell. As mother cells become old, they enlarge and produce daughter cells that are larger than daughters derived from young mother cells. We found that occasional daughter cells were indistinguishable in size from their mothers, giving rise to a symmetric division. The frequency of symmetric divisions became greater as mother cells aged and reached a maximum occurrence of 30% in mothers undergoing their last cell division. Symmetric divisions occurred similarly in rad9 and ste12 mutants. Strikingly, daughters from old mothers, whether they arose …

Second Intermediate Host-Specificity Of Haematoloechus Complexus And Haematoloechus Medioplexus (Digenea: Haematoloechidae), Scott D. Snyder, John J. Janovy

Biology Faculty Publications

Second intermediate host-specificity was examined for two species of the frog lung fluke genus Haematoloechus. Nine species of freshwater arthropods were exposed to cercariae of H. complexus and H. medioplexus. Metacercariae of H. complexus developed in all arthropod species used. Metacercariae of H. medioplexus developed only in anisopteran odonate naiads. This difference in host utilization may have epizootiological implications. The potential development of H. complexus in a greater number of arthropods than H. medioplexus may increase the chances of ingestion of H. complexus by an anuran host. The range of arthropods parasitized by H. complexus indicates that host-specificity …

Phylogenetic Analysis Of Segment 10 From African Horsesickness Virus And Cognate Genes From Other Orbiviruses, Rafael O. De Sá, Marla Zellner, Marvin J. Grubman

Biology Faculty Publications

Utilizing the reverse transcriptase-polymerase chain reaction (RT-PCR) procedure, we have synthesized full-length copies of segment 10 from African horsesickness virus (AHSV) serotypes 1,4 and 8. The genes were cloned, sequenced and compared with the sequence of the cognate gene from AHSV serotypes 3 and 9. Sequences were analyzed to assess evolutionary relationships among serotypes using cladistics. Based on this analysis the data support a close relationship between serotypes 4 and 9 and between serotypes 1 and 8 and a closer relationship of serotype 3 to the 4 and 9 group.

Terrapene Carolina Carolina, Joseph C. Mitchell, Rafael O. De Sá

Biology Faculty Publications

TERRAPENE CAROLINA CAROLINA (Eastern Box Turtle). REPRODUCTION. Female Terrapene carolina containing oviductal eggs have been recorded in Virginia from 26 May to 25 July (Mitchell, in press. The Reptiles of Virginia. Smithsonian Inst. Press, Washington, D.C.). Other reports of reproduction in Terrapene (see list in Ernst and McBreen 1991. Cat. Amer. Amphib. Rept. 512.1-512.13) indicate that nesting occurs in late spring and early summer throughout its range.

What Are Squirrels Hiding, Michael Steele, Peter D. Smallwood

Biology Faculty Publications

The half-eaten acorns of squirrels are clues to their complex relationship with oaks. The special relationship between squirrels and acorns is examined.

Nectar-Seeking Visits By Butterflies In A Tallgrass Prairie Remnant In Eastern Nebraska, Tanya Bray

Biology Faculty Publications

Stolley Prairie, a tallgrass virgin prairie remnant in eastern Nebraska, was visited 20 times between May 25 and August 14, 1988. Fifty-two species offorbs were observed in bloom during this period. Twenty-seven species of butterflies were observed and 21 species made 262 nectar-seeking visits to 21 plant species. While numbers offorbs in bloom did not strongly correlate with numbers of butterflies present, peaks of butterfly occurrence appeared to follow peaks of blossom abundance. The number of plant species utilized by a species of butterfly ranged from one to nine. Plants with an abundance of nectar such as common milkweed and …

Energy Conservation By Formation Swimming - Metabolic Evidence From Ducklings, Frank E. Fish

Biology Faculty Publications

No abstract provided.

Development And Application Of A Thermistor Current Meter, Carl M. Way, Albert J. Burky, Christine Miller-Way

Biology Faculty Publications

This report provides details for the construction of a hot-bead thermistor current meter which is capable of measuring water velocities on a millimeter spatial scale and for the construction of a compact and accurate calibration system. Hot-bead thermistor current meters can be built with response times of 200 ms capable of measuring velocities between 0.1 and 80 cm s-1. The construction of a sturdy probe for application in lotic systems such as high gradient Hawaiian streams was achieved by the use of heavy-duty acrylic tubing, small stainless steel gas-chromatography tubing, and flexible Tygon spaghetti tubing. An acrylic handle anchors the …

Considerations For Evaluating Ultraviolet Radiation-Induced Genetic Damage Relative To Antarctic Ozone Depletion, Deneb Karentz

Biology Faculty Publications

Springtime ozone depletion over the Antarctic results in increased UVB in local marine environments. It has been established that decreases in primary productivity occur with decreases in ozone concentrations, but the impact of increased UVB on the functioning and stability of the ecosystem has not yet been determined. Very little has been done to evaluate the potential for genetic damage caused by the increase in UVB, and this type of damage is most significant relative to the fitness and maintenance of populations. An essential problem in evaluating genotoxic effects is the lack of appropriate techniques to sample and quantify genetic …

Xenopus Laevis As A Model Organism, David C. Cannatella, Rafael O. De Sá

Biology Faculty Publications

Model organisms are often assumed to be representative of some more inclusive taxon of which the species is a part. This assumption leads to mistaken generalizations about the evolutionary and comparative significance of the data gathered. This paper reviews com? parative and evolutionary studies of Xenopus laevis and its relatives. Phylogenetic analysis of data from DNA sequences and morphology indicate that Xenopus is monophyletic and that Silurana is its sister group. The most basal lineages of Pipidae diverged prior to the breakup of Gondwana. The bizarre morphology of Xenopus is in part due to changes in the mode of meta? …

Bone As A Spring, Frank E. Fish

Biology Faculty Publications

No abstract provided.

Gal4 Disrupts A Repressing Nucleosome During Activation Of Gal1 Transcription In Vivo, Jeffrey D. Axelrod, Michael S. Reagan, John Majors

Biology Faculty Publications

Photofootprinting in vivo of GALl reveals an activation- dependent pattern between the UASG and the TATA box, in a sequence not required for transcriptional activation by GAL4. The pattern results from a nucleosome whose position depends on sequences within the UASG. In the wild-type gene, activation by GAL4 and derivatives disrupts this nucleosome. This activity is independent of interactions with DNA-bound core transcription factors and is proportional to the strength of the activator. Presence of the nucleosome correlates with low basal transcription levels under various conditions, suggesting a role in limiting basal expression. We propose a role for the GAL4 …

Ribosomal Dna And The Phylogeny Of Frogs, David M. Hills, Loren K. Ammerman, Michael T. Dixon, Rafael O. De Sá

Biology Faculty Publications

Phylogenetic analysis of 1656 aligned sites in the 28S ribosomal RNA gene of frogs supports some of the recently recognized higher groups of anurans but provides counter-support for others. The 28S rDNA data support the monophyly of the recently recognized Pipanura (me- sobatrachians plus neobatrachians), which in turn indicates paraphyly of archaeobatrachians. Me- sobatrachians (pelobatoids plus pipoids), which are either considered paraphyletic or weakly sup- ported as monophyletic in morphological analyses, also receive support as a monophyletic group from the 28S rDNA data. Hyloidea (=Bufonoidea), which is widely recognized but lacks morphological support, receives some molecular support as being monophyletic. …

Genotypic Diversity In Populations Of A Fungal Endophyte From Douglas-Fir, Timothy L. Mccutcheon, George C. Carroll, Suzanne Schwab

Biology Faculty Publications

Rhabdocline parkeri, an endophyte of Douglas fir, forms symptomless infections within single epidermal cells of healthy needles. Rhabdocline parkeri strains were isolated from trees growing in various habitats ranging from virgin old growth forests to a single young tree growing isolated in a meadow. Different genotypes of R. parkeri were distinguished by using the Random Amplified Polymorphic DNA (RAPD) technique. A significantly lower number of R. parkeri genotypes per unit foliage were isolated from trees within a 20-year-old managed stand and from an isolated tree than from old growth trees. Foliage from young trees (20 years old) in a stand …

Woody Vegetation Of A Disjunct Bur Oak (Quercus Macrocarpa) Forest In East-Central Nebraska, Debra Ann Beightol, Thomas B. Bragg

Biology Faculty Publications

Woody plant composition was assessed for three tree-size classes in two ravines of Oak Glen Wildlife Management Area, a disjunct oak forest in Seward County, Nebraska, using Importance Values (IV) obtained by the Point-Quarter method. Bur oak (Quercus macrocarpa Michx.) dominated the large-size class (>30 cm dbh) (IV = 258) but elms (Ulmus americana L. and U. rubra Muhl.) (IV = 130) dominated the forest in one ravine in the medium-size class (10-30cm dbh) and elm and hackberry (Celtis occidentalis L.) (IV = 114 and 27 respectively) dominated the small-size class (

Review Of American Wildflower Florilegium By Jean Andrews, David M. Sutherland

Biology Faculty Publications

This book is a collection of 50 watercolor paintings of American wildflowers ("florilegium" means, literally, "a gathering of flowers"). Accompanying each full-page painting is a summary of general information about the plant, including notes about its botanical classification, the etymology of its name, life history, distribution, description, flowering period, pollination, and propagation.

Floristic Diversity In Ten Tallgrass Prairie Remnants Of Eastern Nebraska, Judith F. Boettcher, Thomas B. Bragg, David M. Sutherland

Biology Faculty Publications

Ten eastern Nebraska tallgrass prairie remnants, varying in size from one to 18 ha, were studied or visited during the growing seasons from 1979 to 1993. A total of217 prairie plant species were recorded. Big bluestem (Andropogon gerardii), little bluestem (Andropogon scoparius), smooth brome (Bromus inermis subsp. inermis), New Jersey tea (Ceanothus herbaceus var. pubescens), false sunflower (Heliopsis helianthoides var. scabra), Kentucky bluegrass (Poa pratensis), and porcupine-grass (Stipa spartea) were prevalent in all the prairies although the specific floristic composition has been reported to vary depending on past management, topography, season of evaluation, and prairie size. Of the total species …

Morfología Y Moléculas: Bases Complementarias De La Sistemática Moderna, Rafael O. De Sá, David M. Hillis

Biology Faculty Publications

RESUMEN

El auge de las técnicas moleculares en las últimas dos décadas ha traído nuevos enfoques en los estudios sistemáticos. Aquí presentaremos una revisión del uso, las aplicaciones, y los problemas de las principales metodologías de trabajo. Cada una de estas técnicas es aplicable a algunos problemas e inapropiada para otros, y es importante entender las suposiciones y limitaciones de cada técnica. Concluimos que el uso combinado de los enfoques morfológicos y moleculares otorga mejor resolución a los problemas sistemáticos.

ABSTRACT

The development of molecular techniques during the last two decades has brought new approaches to the analysis of systematic …

The Nfiii/Oct-1 Binding Site Stimulates Adenovirus Dna Replication In Vivo And Is Functionally Redundant With Adjacent Sequences, Lianna K. Etchberger, P. Hearing

Biology Faculty Publications

The inverted terminal repeat (ITR) of adenovirus type 5 (Ad5) is 103 bp in length and contains the origin of DNA replication. Cellular transcription factors NFI/CTF and NFIII/OCT-1 bind to sites within the ITR and participate in the initiation of viral DNA replication in vitro. The ITR also contains multiple copies of two conserved sequence motifs that bind the cellular transcription factors SP1 and ATF. We have analyzed a series of viruses that carry deletions at the left terminus of Ad5. A virus carrying a deletion of the NFIII/OCT-1, SP1, and ATF sites within the ITR (mutant dl309-44/107) was wild …

Individualistic Perspectives On Plant Competition, Nancy J. Huntly

Biology Faculty Publications

No abstract provided.

Status Of Platanthera Praeclara Sheviak & Bowles (Western Prairie Fringed Orchid) In The Platte River Valley In Nebraska From Hamilton To Garden Counties, Tanya E. Bray, Barbara L. Wilson

Biology Faculty Publications

During June and July, 1991, a search for western prairie fringed orchid was conducted in the Platte River Valley in central and west-central Nebraska. No orchids were found in the 370 sites surveyed. Factors which may contribute to the scarcity of this orchid in the area surveyed include drought conditions in the previous three years; habitat alteration by draining, ditching, herbicide application, mowing for hay, crop cultivation and planting of non-native species for hay fields; invasion of the area by trees; and the presence of alkaline soils in some areas

Metabolite Production By Entomopathogenic Fungi, Donald W. Roberts, Raymond J. St. Leger, Sandeep Gupta

Biology Faculty Publications

The entomopathogenic fungi produce a wide assortment of metabolites, some of which are important to the host-specialization of this group of fungi. Very few entomopathogenic fungi have been examined in detail for their metabolites in the disease process. Nevertheless, it is clear that certain proteases and lipases are crucial to the invasion of insect cuticle by the fungus. These fungi have the unusual ability to hydrolyze branched alkanes. Also, they normally produce very active, broad-spectrum proteases. These are needed for penetration of the hydrophobic epicuticle and the highly proteinaceous cuticle of insects. Chitinases also are involved, but usually have only …