Biology Commons^™

Testis Size Increases With Colony Size In Cliff Swallows, Charles R. Brown, Mary Bomberger Brown

School of Biological Sciences: Faculty Publications

By using a sample of more than 800 male cliff swallows (Petrochelidon pyrrhonota) that died during a rare climatic event in our Nebraska study area in 1996, we investigated how testis size was related to body size, age, parasite load, a bird’s past colony-size history, and spleen size. Testis volume in-creased with body size. After correcting for body size, testis volume was lowest for birds age 1 and 2 years but did not vary with age for males 3 years old or more. Birds occupying parasite-free (fumigated) colonies had significantly larger testes than did birds at non-fumigated sites. …

Brief Communications: Rapid And Costly Ageing In Wild Male Flies, Russell Bonduriansky, Chad Brassil

School of Biological Sciences: Faculty Publications

Ageing (senescence) has never been demonstrated convincingly in any insect in the wild, where mean life-spans are probably much shorter than in the laboratory¹, and most evidence for senescence in other wild animals (such as mammals) is limited to their reduced survival with age². Here we show that ageing is detectable in wild populations of a very short-lived insect, the antler fly (Protopiophila litigata), and causes debilitating and costly effects that force a decline not only in survival probability, but also in the reproductive rate of males. Our findings argue against the possibility of …

Contributions To The Mammalogy Of Mongolia, With A Checklist Of The Species Of The Country, David S. Tinnin, Jon L. Dunnum, Jorge A. Salazar-Bravo, Nyamsuren Batsaikhan, M. Scott Burt, Scott Lyell Gardner, Terry L. Yates

Harold W. Manter Laboratory of Parasitology: Faculty Publications

We present accounts for 40 species of mammals collected from 15 localities in the Mongolian People's Republic. Accounts include taxonomic, morphometric, reproductive and ecological information, as well as trap effort and success. In addition, we include a brief history of mammalogical work within Mongolia, a taxonomically updated species list for the country, and a list of institutions with holdings of Mongolian mammals.

Effects Of Herbivory On The Reproductive Effort Of 4 Prairie Perennials, Erica Spotswood, Kate L. Bradley, Johannes M. H. Knops

School of Biological Sciences: Faculty Publications

Background: Herbivory can affect every aspect of a plant's life. Damaged individuals may show decreased survivorship and reproductive output. Additionally, specific plant species (legumes) and tissues (flowers) are often selectively targeted by herbivores, like deer. These types of herbivory influence a plant's growth and abundance. The objective of this study was to identify the effects of leaf and meristem removal (simulated herbivory within an exclosure) on fruit and flower production in four species (Rhus glabra, Rosa arkansana, Lathyrus venosus, and Phlox pilosa) which are known targets of deer herbivory.

Results: Lathyrus never flowered or went to …

Species Richness, Latitude, And Scale-Sensitivity, S. Kathleen Lyons, Michael R. Willig

School of Biological Sciences: Faculty Publications

The latitudinal gradient of species richness is well documented for a variety of taxa in both terrestrial and aquatic environs. Moreover, a number of recent attempts to assess the effects of scale on the relationship have concluded that the latitudinal pattern is scale-invariant. Nonetheless, the power of those approaches is predicated on precise knowledge of the forms of the latitudinal gradient, the area relationship, and their interaction. We used a model developed by J. Pastor, A. Downing, and H. E. Erickson for assessing the effects of scale on the productivity–diversity gradient to avoid such complications. More specifically, for 253 sets …

Stability Of Mrna In The Hyperthermophilic Archaeon Sulfolobus Solfataricus, Elisabetta Bini, Vidula Dikshit, Kristi Dirksen, Melissa Drozda, Paul H. Blum

School of Biological Sciences: Faculty Publications

Archaea-like bacteria are prokaryotes but, in contrast, use eukaryotic-like systems for key aspects of DNA, RNA, and protein metabolism. mRNA is typically unstable in bacteria and stable in eukaryotes, but little information is available about mRNA half-lives in archaea. Because archaea are generally insensitive to antibiotics, examination of mRNA stability in the hyperthermophile, Sulfolobus solfataricus, required the identification of transcription inhibitors for half-life determinations. An improved lacS promoter-dependent in vitro transcription system was used to assess inhibitor action. Efficient inhibitors were distinguished as blocking both lacSp transcription in vitro and the incorporation of ³H-uracil into bulk RNA in …

Conformational Strictness Required For Maximum Activity And Stability Of Bovine Pancreatic Ribonuclease A As Revealed By Crystallographic Study Of Three Phe120 Mutants At 1.4 Å Resolution, Eri Chatani, Rikimaru Hayashi, Hideaki Moriyama, Tatzuo Ueki

School of Biological Sciences: Faculty Publications

The replacement of Phe120 with other hydrophobic residues causes a decrease in the activity and thermal stability in ribonuclease A (RNase A). To explain this, the crystal structures of wild-type RNase A and three mutants—F120A, F120G, and F120W—were analyzed up to a 1.4 Å resolution. Although the overall backbone structures of all mutant samples were nearly the same as that of wild-type RNase A, except for the C-terminal region of F120G with a high B-factor, two local conformational changes were observed at His119 in the mutants. First, His119 of the wild-type and F120W RNase A adopted an A position, whereas …

Predicting Risk To Biodiversity As A Function Of Aquifer Pressure In Gab Mound Springs, A. J. Tyre, Brigitte Tenhumberg, H.P. Possingham

School of Biological Sciences: Faculty Publications

Plants and aquatic invertebrates endemic to mound springs of the Great Artesian Basin (GAB) of Australia are of national biodiversity significance. Springs occur in groups, and current survey data suggest that local extinction and recolonisation within a group does occur naturally. Mound spring fauna are therefore good examples of true metapopulations, and any study of the environmental impacts on these systems must take this into account. Use of GAB water leads to drawdown of the pressure in the aquifer. This can potentially impact mound spring flora and fauna in two ways. First, as pressure decreases, so does flow from spring …

Determining Differences In The Spatial Distribution Of Forest Structure On The Kaibab Plateau: Implications For Forest Management And The Northern Goshawk, Ryan S. Miller

Other Publications in Wildlife Management

The Kaibab Plateau, in North Central Arizona, has undergone extensive change in the last 100 years due to land management practices such as logging, road building, and fire suppression. The northern goshawk (Accipiter gentilis) has been a center of controversy, due to the potential effects of silvicultural practices on goshawk breeding habitat (Reynolds-1983, Bloom et al 1986, Kennedy 1989, Crocker-Bedford 1990). Current and past research efforts on the Kaibab Plateau have mapped Goshawk nesting territories and temporal change in nesting behavior and success. However, these research efforts have not determined how long-term spatial changes in land-use activities that have influenced …

Mean Time To Extinction Of A Metapopulation With An Allee Effect, Chad Brassil

School of Biological Sciences: Faculty Publications

The incorporation of Allee effects into a simple metapopulation extinction model reveals a large non-linear reduction in mean time to extinction with small changes in an Allee limit. The extent of this reduction is dependent on the level of migration in the metapopulation. With small amounts of migration, small changes in the Allee limit result in large changes in the meantime to extinction. With higher levels of migration, the mean time to extinction is not as sensitive to changes in the Allee limit, becoming more similar to the single population case. The metapopulation modeled here is a set of nine …

Microsatellite Analysis Of Female Mating Behaviour In Lek-Breeding Sage Grouse, Katy Semple, Robert K. Wayne, Robert M. Gibson

School of Biological Sciences: Faculty Publications

We used microsatellite DNA markers to genotype chicks in 10 broods of lek-breeding sage grouse, Centrocercus urophasianus, whose mothers’ behaviour was studied by radio tracking and observing leks. Previous behavioural studies suggested that almost all matings are performed by territorial males on leks and that multiple mating is rare. Two broods (20%) were sired by more than one male. Genetic analyses of the broods of eight females that visited an intensively studied lek were consistent with behavioural observations. Four females observed mating produced singly sired broods and males other than the individual observed copulating were excluded as sires for most …

Secreted Euryarchaeal Microhalocins Kill Hyperthermophilic Crenarchaea, Cynthia Haseltine, Tiffany Hill, Rafael Montalvo-Rodriguez, Samantha K. Kemper, Richard F. Shand, Paul H. Blum

School of Biological Sciences: Faculty Publications

Few antibiotics targeting members of the archaeal domain are currently available for genetic studies. Since

bacterial antibiotics are frequently directed against competing and related organisms, archaea by analogy

might produce effective antiarchaeal antibiotics. Peptide antibiotic (halocin) preparations from euryarchaeal

halophilic strains S8a, GN101, and TuA4 were found to be toxic for members of the hyperthermophilic

crenarchaeal genus Sulfolobus. No toxicity was evident against representative bacteria or eukarya. Halocin S8

(strain S8a) and halocin R1 (strain GN101) preparations were cytostatic, while halocin A4 (strain TuA4)

preparations were cytocidal. Subsequent studies focused on the use of halocin A4 preparations and Sulfolobus …

Biodiversity And Decomposition In Experimental Grassland Ecosystems, Johannes M. H. Knops, David A. Wedin, David Tilman

School of Biological Sciences: Faculty Publications

We examined the impact of biodiversity on litter decomposition in an experiment that manipulated plant species richness. Using biomass originating from the experimental species richness gradient and from a species used as a common substrate, we measured rates of decomposition in litterbags in two locations: in situ in the experiment plots and in an adjacent common garden. This allowed us to separate the effects of litter quality and decomposition location on decomposition. We found that plant species richness had a significant, but minor negative effect on the quality (nitrogen concentration) of the biomass. Neither litter type nor location had a …

A Synopsis Of The Ferns And Fern Allies Of Nebraska, With Maps Of Their Distribution, Steven B. Rolfsmeier, Robert B. Kaul, David M. Sutherland

School of Biological Sciences: Faculty Publications

An annotated list and country-by-country distribution maps are presented for the 32 species of ferns and fern allies native to Nebraska, based upon field and herbarium studies and critical evaluation of the literature. Native to the state are Isoëtes melanopoda, Selaginella rupestris, five species of Equisetum, and 25 species in 18 genera of ferns. Three native species are here verified for the first time, based upon recent collections: Matteuccia struthiopteris var. pensylvanica, Ophioglossum engelmannii, and Pellacaglabella ssp. glabella. Isoëtes melanopoda was rediscovered in 2000, the first record since 1941. Rejected are published reports of …

Plant Quality And Spider Predation Affects Grasshoppers (Acrididae): Food-Quality-Dependent Compensatory Mortality, Mark A. Oedekoven, Anthony Joern

School of Biological Sciences: Faculty Publications

For insect herbivores, population responses reflect interactions among multiple factors, including abiotic conditions, food plant availability, and biotic interactions guided by food limitation and natural enemies. In this set of field experiments, we evaluated the interactive, dynamic effects of limited food supply and predation from wolf spiders (Lycosidae) on mortality in Ageneotettix deorum, a common grasshopper (Acrididae) from North American sandhills grasslands. We attempted to determine whether the combined effects of food availability and spider predation on mortality were (1) noncompensatory, with the effects of each factor summing to determine ultimate population size, or (2) compensatory, where the effect …

Pyoveridine Production By Pseudomonas Aeruginosa Exposed To Metals Or An Oxidative Stress Agent, Kim-Hien Thi Dao, Katherine E. Hamer, Christine L. Clark, Lawrence G. Harshman

School of Biological Sciences: Faculty Publications

Siderophores are low molecular mass compounds used by many microorganisms to scavenge dissolved iron, which is typically rare in environments. Pseudomonas aeruginosa (PAO1) was exposed to metals and methyl viologen in low-iron medium in order to monitor the abundance of a specific siderophore (pyoverdine) and monitor growth over time. In this study it was discovered that cadmium can stimulate pyoverdine abundance. Cadmium may interact with and sequester the Fur regulatory protein, which represses siderophore synthesis under conditions of iron sufficiency. Mercury did not stimulate pyoverdine production at concentrations that strongly inhibited bacterial growth, suggesting that pyoverdine production is not governed …

Analysis Of Intraguild Predation With A Consideration Of Adaptive Foraging, Toshinori Okuyama

School of Biological Sciences: Dissertations, Theses, and Student Research

Identification of interactive units in food webs is particularly important in population and community ecology. Intraguild predation has gained much attention recently with the recognition of its prevalence in the field, although its significance has not been fully studied. Nature contains much more complex interactions than a simple food chain. Yet, much theory still focuses on the trophic levels connected in a single linear chain. In this thesis, I study intraguild predation including the consideration of animal behavior whose importance is also often neglected in population and community ecology.

First, the concepts of intraguild predation and animal behavior are introduced. …

Pyoverdine Production By Pseudomonas Aeruginosa Exposed To Metals Or An Oxidative Stress Agent, Kim-Hien Thi Dao, Katherine E. Hamer, Christine L. Clark, Lawrence G. Harshman

School of Biological Sciences: Faculty Publications

Siderophores are low molecular mass compounds used by many microorganisms to scavenge dissolved iron, which is typically rare in environments. Pseudomonas aeruginosa (PAO1) was exposed to metals and methyl viologen in low-iron medium in order to monitor the abundance of a specific siderophore (pyoverdine) and monitor growth over time. In this study it was discovered that cadmium can stimulate pyoverdine abundance. Cadmium may interact with and sequester the Fur regulatory protein, which represses siderophore synthesis under conditions of iron sufficiency. Mercury did not stimulate pyoverdine production at concentrations that strongly inhibited bacterial growth, suggesting that pyoverdine production is not governed …

Coordinate Transcriptional Control In The Hyperthermophilic Archaeon Sulfolobus Solfataricus, Cynthia Haseltine, Rafael Montalvo-Rodriguez, Elisabetta Bini, Audrey Carl, Paul H. Blum

School of Biological Sciences: Faculty Publications

The existence of a global gene regulatory system in the hyperthermophilic archaeon Sulfolobus solfataricus is

described. The system is responsive to carbon source quality and acts at the level of transcription to coordinate

synthesis of three physically unlinked glycosyl hydrolases implicated in carbohydrate utilization. The specific

activities of three enzymes, an a-glucosidase (malA), a b-glycosidase (lacS), and an a-amylase, were reduced

4-, 20-, and 10-fold, respectively, in response to the addition of supplementary carbon sources to a minimal

sucrose medium. Western blot analysis using anti-a-glucosidase and anti-b-glycosidase antibodies indicated

that reduced enzyme activities resulted exclusively from …

Bacterial Growth State Distinguished By Single-Cell Protein Profiling: Does Chlorination Kill Coliforms In Municipal Effluent?, David Rockabrand, Teresa Austin, Robyn Kaiser, Paul H. Blum

School of Biological Sciences: Faculty Publications

Municipal effluent is the largest reservoir of human enteric bacteria. Its public health significance, however,

depends upon the physiological status of the wastewater bacterial community. A novel immunofluorescence

assay was developed and used to examine the bacterial growth state during wastewater disinfection. Quantitative

levels of three highly conserved cytosolic proteins (DnaK, Dps, and Fis) were determined by using

enterobacterium-specific antibody fluorochrome-coupled probes. Enterobacterial Fis homologs were abundant

in growing cells and nearly undetectable in stationary-phase cells. In contrast, enterobacterial Dps homologs

were abundant in stationary-phase cells but virtually undetectable in growing cells. The range of variation in

the abundance of …

Roles Of Dnak And Rpos In Starvation-Induced Thermotolerance Of Escherichia Coli, David Rockabrand, Kevin Livers, Tess Austin, Robyn Kaiser, Debra Jensen, Richard Burgess, Paul H. Blum

School of Biological Sciences: Faculty Publications

DnaK is essential for starvation-induced resistance to heat, oxidation, and reductive division in Escherichia coli. Studies reported here indicate that DnaK is also required for starvation-induced osmotolerance, catalase activity, and the production of the RpoS-controlled Dps (PexB) protein. Because these dnaK mutant phenotypes closely resemble those of rpoS (o³⁸) mutants, the relationship between DnaK and RpoS was evaluated directly during growth and starvation at 30°C in strains with genetically altered DnaK content. A starvation-specific effect of DnaK on RpoS abundance was observed. During carbon starvation, DnaK deficiency reduced RpoS levels threefold, while DnaK excess increased RpoS levels …

Molecular Characterization Of The Α-Glucosidase Gene (Mala) From The Hyperthermophilic Archaeon Sulfolobus Solfataricus, Michael Rolfsmeier, Cynthia Haseltine, Elisabetta Bini, Amy Clark, Paul H. Blum

School of Biological Sciences: Faculty Publications

Acidic hot springs are colonized by a diversity of hyperthermophilic organisms requiring extremes of temperature and pH for growth. To clarify how carbohydrates are consumed in such locations, the structural gene (malA) encoding the major soluble α-glucosidase (maltase) and flanking sequences from Sulfolobus solfataricus were cloned and characterized. This is the first report of an α-glucosidase gene from the archaeal domain. malA is 2,083 bp and encodes a protein of 693 amino acids with a calculated mass of 80.5 kDa. It is flanked on the 5’ side by an unusual 1-kb intergenic region. Northern blot analysis of the …

Relationship Between Yeast Polyribosomes And Upf Proteins Required For Nonsense Mrna Decay, Audrey L. Atkin, Laura R. Schenkman, Margot Eastham, Jeffrey N. Dahlseid, Michael J. Lelivelt, Michael R. Culbertson

School of Biological Sciences: Faculty Publications

In yeast, the accelerated rate of decay of nonsense mutant mRNAs, called nonsense-mediated mRNA decay, requires three proteins, Upf1p, Upf2p, and Upf3p. Single, double, and triple disruptions of the UPF genes had nearly identical effects on nonsense mRNA accumulation, suggesting that the encoded proteins function in a common pathway. We examined the distribution of epitope-tagged versions of Upf proteins by sucrose density gradient fractionation of soluble lysates and found that all three proteins co-distributed with 80 S ribosomal particles and polyribosomes. Treatment of ly-sates with RNase A caused a coincident collapse of polyribosomes and each Upf protein into frac-tions containing …

A Re-Evaluation Of Hotspot Settlement In Lekking Sage Grouse, Robert M. Gibson

School of Biological Sciences: Faculty Publications

Recent analyses of avian leks have come to conflicting conclusions concerning the role of male settlement on female traffic hotspots. This issue was re-examined in the sage grouse, Centrocercus urophasianus, using data on prenesting movements of radio-tagged females and the dispersion of lekking males collected during a 10-year field study. As expected with hotspot settlement, leks were preferentially located in areas through which females traveled between wintering and nesting ranges before mating. In addition, the distribution of males among leks was related proximately to variation in numbers of females visiting each lek during the mating period and ultimately to …

Female Choice In Sage Grouse: The Roles Of Attraction And Active Comparison, Robert M. Gibson

School of Biological Sciences: Faculty Publications

Previous studies of female choice in sage grouse Centrocercus urophasianus have implicated both the acoustic quality and repetition rate of the stereotyped strut display as putative cues for female choice. Stages in the choice process at which specific components of male courtship display influence female decisions were investigated using field observations of female premating behavior. Females visited a subset of territorial males and then actively chose one of these as a mate. The order in which males were visited suggested that females searched until an acceptable mate was found, rather than employing a “best-of-n” tactic. Numbers of females visiting a …

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 …

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 …

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 …

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 …

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 …