Life Sciences Commons^™

Multiple Members Of A Third Subfamily Of P-Type Atpases Identified By Genomic Sequences And Ests, Margaret S. Halleck, Deepti Pradhan, Christie Blackman, Charlotte A. Berkes, Partrick Williamson, Robert A. Schlegel

Biology Faculty Publications

The Saccharomyces cerevisiae genome contains five P-type ATPases divergent from both of the well-known subfamilies of these membrane ion transporters. This newly recognized third subfamily can be further divided into four classes of genes with nearly equal relatedness to each other. Genes of this new subfamily are also present and expressed in multicellular organisms such as Caenorhabditis elegans and mammals; some, but not all, can be assigned to the classes identified in yeast. Different classes of genes and different genes within a class are expressed differentially in tissues of the mouse. The recently cloned gene for the mammalian aminophospholipid translocase …

Seedling Development In Species Of Chamaesyce (Euphorbiaceae) With Erect Growth Habits, W. John Hayden, Olga Troyanskaya

Biology Faculty Publications

Seedling development is described for Chamaesyce hirta, C. hypericifolia, and C. mesembrianthemifolia as discerned by light microscopy and scanning electron microscopy. Although these species ultimately develop erect to ascending growth habits, epicotyl development is limited to the production of a single pair ofleaves located immediately superjacent to and decussate with the cotyledons. The shoot system develops from one or more buds located in the axils of the cotyledons. In all respects, seedling ontogeny is very similar to that of previously studied prostrate species of Chamaesyce. Evidence from seedling ontogeny thus contradicts a hypothesis concerning homologies of plant …

Assembly Of The Herpes Simplex Virus Capsid: Preformed Triplexes Bind To The Nascent Capsid, Juliet V. Spencer, William W. Newcomb, Darrell R. Thomsen, Fred L. Homa, Jay C. Brown

Biology Faculty Publications

The herpes simplex virus type 1 (HSV-1) capsid is a T=16 icosahedral shell that forms in the nuclei of infected cells. Capsid assembly also occurs in vitro in reaction mixtures created from insect cell extracts containing recombinant baculovirus-expressed HSV-1 capsid proteins. During capsid formation, the major capsid protein, VP5, and the scaffolding protein, pre-VP22a, condense to form structures that are extended into procapsids by addition of the triplex proteins, VP19C and VP23. We investigated whether triplex proteins bind to the major capsid-scaffold protein complexes as separate polypeptides or as preformed triplexes. Assembly products from reactions lacking one triplex protein were …

Host Plant Alters The Shape Of The Functional Response Of An Aphid Predator (Coleoptera: Coccinellidae), Frank J. Messina, J. B. Hanks

Biology Faculty Publications

The response of the lady beetle Propylea quatuordecimpunctata (L.) to the density of the Russian wheat aphid, Diuraphis noxia (Mordvilko), was measured in petri dish arenas as well as on plants with divergent leaf architectures. Logistic regression was used to distinguish the shape of the functional response (type II or III), and nonlinear least-squares regression was used to estimate attack coefficients (a) and handling times (Th). In dishes, the behavior of both beetle larvae and adults closely conformed to a type II response. Estimates of a and Th on whole plants were considerably different from those obtained from dishes, and …

Altered Trafficking Of Mutant Connexin32, Suzanne M. Deschênes, Jessica L. Walcott, Tamara L. Wexler, Steven S. Scherer, Kenneth H. Fischbeck

Biology Faculty Publications

We examined the cellular localization of nine different connexin32 (Cx32) mutants associated with X-linked Charcot–Marie–Tooth disease (CMTX) in communication-incompetent mammalian cells. Cx32 mRNA was made, but little or no protein was detected in one class of mutants. In another class of mutants, Cx32 protein was detectable in the cytoplasm and at the cell surface, where it appeared as plaques and punctate staining. Cx32 immunoreactivity in a third class of mutants was restricted to the cytoplasm, where it often colocalized with the Golgi apparatus. Our studies suggest that CMTX mutations have a predominant effect on the trafficking of Cx32 protein, resulting …

Inhibition Of Axonal Growth By Brefeldin A In Hippocampal Neurons In Culture, Mark Jareb, Gary Banker

Biology Faculty Publications

The outgrowth of neuronal processes involves a great increase in the surface area of the cell. The supply of membrane material necessarily must be coordinated with the demands for neurite growth. The selective growth of only one or two neurites at any given time during the development of polarity raises the possibility that the production of materials by the soma is limiting for growth (Dotti and Banker, 1987; Dotti et al., 1988; Goslin and Banker, 1990). To examine the role of the availability of membrane components during the development of polarity and axonal elongation, we treated neurons with brefeldin A, …

Recovery Of Rna Polymerase Ii Synthesis Following Dna Damage In Mutants Of Saccharomyces Cerevisiae Defective In Nucleotide Excision Repair, Michael S. Reagan, Errol C. Friedberg

Biology Faculty Publications

We have measured the kinetics of the recovery of mRNA synthesis in the inducible GAL10 and RNR3 genes after exposure of yeast cells to ultraviolet (UV) radiation. Such recovery is abolished in mutant strains defective in nucleotide excision repair (NER) of DNA, including a rad23 mutant. Mutants defective in the RAD7 or RAD16 genes, which are required for the repair of the non-transcribed strand but not the transcribed strand of transcriptionally active genes, show slightly faster recovery of RNA synthesis than wild-type strains. A strain deleted of the RAD26 gene, which is known to be required for strand-specific NER in …

Evolutionary Constraints On Population Structure: The Parasites Of Fundulus Zebrinus (Pisces: Cyprinodontidae) In The South Platte River Of Nebraska, John J. Janovy Jr., Scott D. Snyder, Richard E. Clopton

Biology Faculty Publications

Population and community descriptor values (parasites per host, prevalence per parasite species, variance/mean ratios, species density, and diversity indices) for the 7-species parasite community of 61 relatively homogeneous samples of Fundulus zebrinus (Pisces: Cyprinodontidae) in the South Platte River of Nebraska, U.S.A., taken over a 14-yr period, are reported. South Platte River streamflow fluctuates over two orders of magnitude on several time scales-monthly, annually, and over multiple year wet-dry cycles. Relatively homogeneous sampling of a single host species with several parasite species provided a system that allowed assessment of the contribution of evolved parasite life cycles to population structure in …

Nebraska's Flying Mammals, Patricia W. Freeman, Kenneth N. Geluso, J. Scott Altenbach

Biology Faculty Publications

They flit around at dusk in crazy patterns. They fly around street lights and dive at rocks thrown in the air. They have high-pitched squeaks and turn up in unexpected places. They have strange, little faces and bizarre ears. They have soft fur and a thin rubbery membrane across their long fingers. They are bats, Nebraska's only flying mammals.

Bats are mysterious. Is it because they come out at night and we come out in the daytime? Maybe it is because we associate flying with birds, not mammals. Bats are dark and foreboding, not brightly colored. At first, these mysterious …

Revision Of The Cerrado Hemicryptophytic Chamaesyce Of Boissier's "Pleiadeniae" (Euphorbiaceae), Mark P. Simmons, W. John Hayden

Biology Faculty Publications

The species of Chamaesyce classified by Boissier as the "Pleiadeniae'" are revised in light of presently available collections. Six species are accepted and new combinations are proposed for C. nana, C. setosa, C. tamanduana, and C. viscoides. Although these herbaceous perennials of cerrado vegetation of Brazil, northern Argentina, and adjacent countries are distinctive ecologically and geographically, cladistic analysis does not support their recognition as a monophyletic group.

Analysis Of Gene Expression During Embryonic Development In Mulberry Silkworm Bombyx Mori, Amit Singh, K. P. Gopinathan

Biology Faculty Publications

We have developed a method for dechorionation and devitellinization of the silkworm eggs without damage, to facilitate the analysis of gene expression during embryonic development of Bombyx mori. Making use of antibodies available from heterologous systems, the spatio-temporal expression patterns of peroxidase and proliferating cell nuclear antigen have been directly visualized in whole mount embryos at various stages of development without the need for generating transformed ·lines carrying specific reporter constructs. The B. mori system, previously unamenable for such studies, could thus serve as an attractive model for molecular analysis of insect development.

The attention lavished on Drosophila melanogaster as …

The Roles Of Harsh And Fluctuating Conditions In The Dynamics Of Cological Communities, P Chesson, Nancy J. Huntly

Biology Faculty Publications

Harsh conditions (e.g., mortality and stress) reduce population growth rates directly; secondarily, they may reduce the intensity of interactions between organisms. Near-exclusive focus on the secondary effect of these forms of harshness has led ecologists to believe that they reduce the importance of ecological interactions, such as competition, and favor coexistence of even ecologically very similar species. By examining both the costs and the benefits, we show that harshness alone does not lessen the importance of species interactions or limit their role in community structure. Species coexistence requires niche differences, and harshness does not in itself make coexistence more likely. …

Assignment Of Fragile Site 8e (Fra8e) To Human Chromosome Band 8q24.11 Adjacent To The Hereditary Multiple Exostoses 1 Gene And Two Overlapping Langer-Giedion Syndrome Deletion Endpoints, April L. Hill, Y. Harada, E. Takahashi, J. Hou, M. J. Wagner, D. E. Wells

Biology Faculty Publications

The distamycin A inducible fragile site, FRA8E, Fra(8) (q24.11) has been previously mapped to 8q24.11, proximal to the MYC gene, by fluorescent in situ hybridization (Takahasi et al., 1991). This fragile site has been shown to be present in about 1 out of every 140 healthy Japanese individuals (Takahasi et al., 1988). To more precisely map FRA8E, we have used cosmids isolated from the Langer-Giedion chromosomal region (LGCR) for FISH analysis. Langer-Giedion syndrome (LGS) is a contiguous gene syndrome characterized by chromosome deletions in Sq24.11 (Ludecke et al., 1991). One of the genes known to be involved in the etiology …

Description Of Tadpoles Of Three Species Of Scinax (Anura: Hylidae), Rafael O. De Sá, Rocjard Wassersig, Arturo I. Kehr

Biology Faculty Publications

Larval morphological characteristics have been used to cluster species of Scinax in seven species groups and to support the monophyly of some of these groups. However, our present knowledge of Scinax tadpoles is incomplete; currently, tadpoles of only 21 of the approximately 80 recognized species have been described. Herein, we describe and illustrate the external morphology and oral disc characteristics of larval Scinax berthae, S. nebulosa, and S. boesemani. The presence of a "labial arm" supporting the P3 tooth row in S. boesemani, and its absence from S. nebulosa, is discussed in the light of our limited knowledge of tadpoles …

The Tadpole Of Pseudis Minuta (Anura: Pseudidae), An Apparent Case Of Heterochrony, Rafael O. De Sá, Esteban O. Lavilla

Biology Faculty Publications

The external morphology, oral disc, and coloration pattern of the larva of Pseudis minuta are described. Tadpoles are mostly bottom dwellers that have a small, terminal oral disc with a labial tooth row formula 1(1-1)/(1-1)2. Internal oral anatomy is characterized using scanning electron microscopy, representing the only description available for the family Pseudidae. The coloration pattern of P. minuta tadpoles is compared with that of other pseudids. Pseudis minuta larvae do not exhibit the ontogenetic coloration change reported for P. paradoxa. Considering larval coloration, larval size, and reports of adult size, acceleration or hypermorphosis are suggested as possible heterochronic mechanisms …

Description Of The Tadpole Of Atelopus Tricolor, E. O. Lavilla, Rafael O. De Sá, Ignacio De La Riva

Biology Faculty Publications

Tadpoles of Atelopus belong to the gastromyzophorous guild of exotrophic larvae (Altig and Johnston, 1989), and are characterized by the presence of a conspicuous abdominal sucker and an expanded oral disc. The larvae of several Atelopus species have been described previously: A. varius (Starrett, 1967); A. certus, A. ignescens, and A. spumarius (Duellman and Lynch, 1969); A. cruciger (Mebs, 1980); A. flavescens (Lescure, 1981); A. peruensis (Gray and Cannatella, 1985); and A. subornatus (Lynch, 1986). These represent about 15% of the known species in the genus (Frost, 1985; Duellman, 1993). Although Atelopus tricolor was originally described at the beginning of …

Evidence That Elevated C02 Levels And Indirectly Increase Rhizosphere Denitrifier Activity, John M. Stark, D. Smart, K. Ritchie, Bruce Bugbee

Biology Faculty Publications

We examined the influence of elevated CO2 concentration on denitrifier enzyme activity in wheat rhizoplanes by using controlled environments and solution culture techniques. Potential denitrification activity was from 3 to 24 times higher on roots that were grown under an elevated CO2 concentration of 1,000 micromoles of CO2 mol-1 than on roots grown under ambient levels of CO2. Nitrogen loss, as determined by a nitrogen mass balance, increased with elevated CO2 levels in the shoot environment and with a high NO3- concentration in the rooting zone. These results indicated that aerial CO2 concentration can play a role in rhizosphere denitrifier …

Connexin32 And X-Linked Charcot-Marie-Tooth Disease, Kenneth H. Fischbeck, Suzanne M. Deschênes, Linda Jo Bone, Steven S. Scherer

Biology Faculty Publications

This paper deals with the genetic defect responsible for the X-linked form of Charcot-Marie-Tooth disease.Mutations in the gap junction geneconnexin32(Cx32) cause the X-linked form of Charcot–Marie–Tooth disease, an inherited demyelinating neuropathy.

External Morphology Of The Chorion Of The Annual Fishes Cynolebias (Cyprinodontiformes: Rivulidae), Marcelo Loureiro, Rafael O. De Sá

Biology Faculty Publications

Members of the family Rivulidae (killifishes) inhabit temporary bodies of freshwater in South and Central America (one species is also found in North America). The most remarkable characteristic of the family Rivulidae is that species have an annual life cycle with a drought-resistant egg during the dry season. Parenti's (1981) analysis of the order Cyprinodontiformes considered a single genus, Cynolebias, whereas Cos- ta's (1990) phylogenetic analysis of the family Rivulidae separates Cynolebias from Cynopoecilus. One of Costa's synapomorphies to separate Cynopoecilus is the unique structure of their egg's chorion, which is shared with Leptolebias and Campellolebias.

Taking Root, W. John Hayden

Biology Faculty Publications

The brief description of mangrove reproduction in John N. Cole's "Off Key, Out of Reach" [A Sense of Place, July-August] contains an error.

Mutagenicity Of Acridines In A Reversion Assay Based On Tetracycline Resistance In Plasmid Pbr322 In Escherichia Coli, George R. Hoffman, Suzanne M. Deschênes, Teresa Manyin, Robert P. P. Fuchs

Biology Faculty Publications

The mutagenicity of a series of acridine compounds was studied in an assay based on the reversion of mutations in the tetracycline-resistance gene (tet) of plasmid pBR322 in Escherichia coli. Mutations that restore the tetracycline-resistant phenotype were detected in tetracycline-sensitive strains carrying mutant plasmids. Mutations that revert by +2, +1, −1, and −2 frameshift mutations and by base-pair substitutions were used to analyze the mutagenicity of two simple acridines, two acridine mustards, and a nitroacridine. The simple acridines (9-aminoacridine and quinacrine) effectively induced −1 frameshifts and weakly induced +1 frameshifts. The acridine mustards (quinacrine mustard and ICR-191) …

Interactions Involving The Human Rna Polymerase Ii Transcription/Nucleotide Excision Repair Complex Tfiih, The Nucleotide Excision Repair Protein Xpg, And Cockayne Syndrome Group B (Csb) Protein, Narayan Iyer, Michael S. Reagan, Kou-Juey Wu, Bertram Canagarajah, Errol C. Friedberg

Biology Faculty Publications

The human basal transcription factor TFIIH plays a central role in two distinct processes. TFIIH is an obligatory component of the RNA polymerase II (RNAP II) transcription initiation complex. Additionally, it is believed to be the core structure around which some if not all the components of the nucleotide excision repair (NER) machinery assemble to constitute a nucleotide excision repairosome. At least two of the subunits of TFIIH (XPB and XPD proteins) are implicated in the disease xeroderma pigmentosum (XP). We have exploited the availability of the cloned XPB, XPD, p62, p44, and p34 genes (all …

Behavioral Basis Of Second Intermediate Host Specificity Among Four Species Of Haematoloechus (Digenea: Haematoloechidae), Scott D. Snyder, John J. Janovy Jr.

Biology Faculty Publications

Cercarial behavior patterns were examined in four species of frog lung flukes (Haematoloechus spp.). Cercariae of Haematoloechus complexus, Haematoloechus medioplexus, Haematoloechus longiplexus, and Haematoloechus varioplexus were exposed to three species of experimental arthropods and an inanimate control. The number of cercariae attached to an experimental host at 5 min postexposure was recorded. Haematoloechus longiplexus and H. complexus cercariae attached to experimental hosts at higher rates than cercariae of H. medioplexus and H. varioplexus. Cercariae of H. longiplexus attached to experimental hosts in approximately the same numbers as H. complexus, but H. longiplexus penetrated only damselfly naiads, …

Topographically Specific Effects Of Elf-1 On Retinal Axon Guidance In Vitro And Retinal Axon Mapping In Vivo, Masaru Nakamoto

Biology Faculty Publications

Topographic maps, which maintain the spatial order of neurons in the order of their axonal connections, are found throughout the nervous system. In the visual retinotectal projection, ELF-1, a ligand in the tectum, and its receptors in the retina show complementary gradients in expression and binding, indicating they may be positional labels for map development. Here we show that ELF-1 acts as a repellent axon guidance factor in vitro. In vivo, when the tectal ELF-1 pattern is modified by retroviral overexpression, retinal axons avoid ectopic ELF-1 patches and map to abnormally anterior positions. All these effects were seen on axons …

Hyla Multifasciata, Rafael O. De Sá

Biology Faculty Publications

Hyla multifasciata is a medium to large species in the albopunctata species group, adults ranging in size from 42 - 61 mm SVL (mean male SVL = 48 mm, mean female SVL = 53 mm). The head is longer than wide. The snout is rounded in dorsal view, whereas in lateral view it is rounded and protrudes slightly beyond the mandible. The canthus rostralis is rounded and distinct, the loreal region is concave, and the internarial region is convex. The eyes are large, approximately twice the diameter of the tympanum. The tympanum is separated from the eye by a distance …

Características De La Osificación Craneal En Phyllomedusa Boliviana (Anura: Hylidae), Rafael O. De Sá, E. O. Lavilla

Biology Faculty Publications

RESUMEN. Dentro de la familia Hylidae disponemos de información sobre las secuencias de osificación craneal para menos del 4.0% de sus miembros. El presente trabajo describe la secuencia de osificación craneal de Phyllomedusa boliviana. El patrón general de osificación es similar a lo reportado para otras especies de la familia, pero existen algunas diferencias importantes tales como la osificación tardía de los próoticos y la osificación premetamórfica de neopalatino, vómer, cuadrado-yugal, pterigoides y columela. El lento desarrollo ulterior de la osificación resulta en juveniles con cráneos extensamente cartilaginosos.

ABSTRACT. Characteristics of the cranial ossification in Phyllomedusa …

A Revision Of Discocarpus (Euphorbiaceae), Sheila M. Hayden, W. John Hayden

Biology Faculty Publications

As revised here, Discocarpus is interpreted to consist of three neotropical species: D. essequeboensis Klotzsch, D. gentryi S. M. Hayden, which is described and named herein as new to science, and D. spruceanus Müll. Arg. One previously accepted name, D. brasiliensis Klotzsch ex Müll. Arg., is reduced to synonymy of D. essequeboensis. Lecto-types are proposed for the two species previously described. One species is newly excluded from Discocarpus, as are three others, following previous literature. Foliar anatomy is described with a focus on epidermal sclereids, which are shown to occur on both epidermides. Evidence presented supports close relationships …

Leptodactylus Silvanimbus (Amphibia: Anura: Leptodactylidae): Natural History Notes, Advertisement Call, And Relationships, W. Ronald Heyer, Rafael O. De Sá, James R. Mccranie, Larry David Wilson

Biology Faculty Publications

In July 1995, we visited two of the three previously known localities for Leprodactylus silvanimbus in Departamento de Ocotepeque, Honduras. We found a new breeding site for the species, recorded its advertisement call, and collected and observed its adults and larvae. The purpose of this paper is to present the results of these new findings and to comment on the relationships L. silvanimbus.

Mutations In Trans-Acting Factors Affecting Mrna Decapping In Saccharomyces Cereviciae, Lianna K. Etchberger, C. A. Stevens, A. Stevens, R. Parker

Biology Faculty Publications

The decay of several yeast mRNAs occurs by a mechanism in which deadenylation precedes decapping and subsequent 5'-to-3' exonucleolytic decay. In order to identify gene products required for this process of mRNA turnover, we screened a library of temperature-sensitive strains for mutants with altered mRNA degradation. We identified seven mutations in four genes that inhibited mRNA turnover. Two mutations were alleles of the XRN1 5'-to-3' exoribonuclease known to degrade mRNAs following decapping. One mutation defined a new gene, termed DCP1, which in subsequent work was demonstrated to encode a decapping enzyme or a necessary component of a decapping complex. The …

Fate Of Biological Control Introductions: Monitoring An Australian Fungal Pathogen Of Grasshoppers In North America, Michael J. Bidochka, Scott R. A. Walsh, Mark E. Ramos, Raymond J. St. Leger, Julie Cl Silver, Donald W. Roberts

Biology Faculty Publications

In North America there are two generally recognized pathotypes (pathotypes 1 and 2) of the fungus Entomophaga grylli which show host-preferential infection of grasshopper subfamilies. Pathotype 3, discovered in Austra- lia,hasabroadergrasshopperhostrangeandwasconsidered to be a good biocontrol agent. Between 1989 and 1991 patho- type3wasintroducedattwofieldsitesinNorthDakota.Since resting spores are morphologically indistinguishable among pathotypes, we used pathotype-specific DNA probes to con- firm pathotype identification in E. grylli-infected grasshop- pers collected at the release sites in 1992, 1993, and 1994. In 1992, up to 23% of E. grylli-infected grasshoppers of the subfamilies Melanoplinae, Oedipodinae, and Gomphocerinae were infected by pathotype 3,with no infections >1 km …