Life Sciences Commons^™

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, …

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 …

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 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 …

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 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 …

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 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. …

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.

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 …