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Physiological Responses Of Resistant And Susceptible Barley, Hordeum Vulgare To The Russian Wheat Aphid, Diurpahis Noxia (Mordvilko), Andrea R. Gutsche, Tiffany M. Heng-Moss, Leon G. Higley, Gautam Sarath, Dolores W. Mornhinweg

Gautam Sarath Publications

Knowledge of the physiological responses of barley, Hordeum vulgare L., to the Russian wheat aphid, Diuraphis noxia (Mordvilko) (Hemiptera: Aphididae) is critical to understanding the defense response of barley to aphid injury and identifying resistance mechanisms. This study documented the impact of D. noxia feeding on resistant (‘Sidney’) and susceptible (‘Otis’) barley through chlorophyll fluorescence measurements, chlorophyll content, and carbon assimilation (A–C_i) curves recorded at 1, 3, 6, 10, and 13 days after aphid introduction. All chlorophyll fluorescence parameters evaluated were similar between aphid-infested and control plants for both cultivars. A–C_i curves showed that D. noxia feeding …

Improved Sugar Conversion And Ethanol Yield For Forage Sorghum (Sorghum Bicolor L. Moench) Lines With Reduced Lignin Contents, Bruce S. Dien, Gautam Sarath, Jeffrey F. Pedersen, Scott E. Sattler, Han Chen, Deanna L. Funnell-Harris, Nancy N. Nichols, Michael A. Cotta

Gautam Sarath Publications

Lignin is known to impede conversion of lignocellulose into ethanol. In this study, forage sorghum plants carrying brown midrib (bmr) mutations, which reduce lignin contents, were evaluated as bioenergy feedstocks.

Two Distinct Waxy Alleles Impact The Granule-Bound Starch Synthase In Sorghum, Scott E. Sattler, Jaswinder Singh, Eric J. Haas, Lining Guo, Gautam Sarath, Jeffrey F. Pedersen

Gautam Sarath Publications

The granule-bound starch synthase (GBSS) is the enzyme responsible for amylose synthesis in starch granules. Loss of GBSS activity results in starch granules containing mostly amylopectin and little or no amylose, a phenotype described as waxy.

Evolution Of Dna Polymerases: An Inactivated Polymerase-Exonuclease Module In Pol Ε&#;And A Chimeric Origin Of Eukaryotic Polymerases From Two Classes Of Archaeal Ancestors, Tahir Tahirov, Kira Makarova, Igor Rogozin, Youri Pavlov, Eugene Koonin

Papers in Evolution

Background: Evolution of DNA polymerases, the key enzymes of DNA replication and repair, is central to any reconstruction of the history of cellular life. However, the details of the evolutionary relationships between DNA polymerases of archaea and eukaryotes remain unresolved.
Results: We performed a comparative analysis of archaeal, eukaryotic, and bacterial B-family DNA polymerases, which are the main replicative polymerases in archaea and eukaryotes, combined with an analysis of domain architectures. Surprisingly, we found that eukaryotic Polymerase ε consists of two tandem exonuclease-polymerase modules, the active N-terminal module and a C-terminal module in which both enzymatic domains are inactivated. The …

Computational Prediction Of Novel Non-Coding Rnas In Arabidopsis Thaliana, Dandan Song, Yang Yang, Bin Yu, Binglian Zheng, Zhidong Deng, Bao-Liang Lu, Xuemei Chen, Tao Jiang

School of Biological Sciences: Faculty Publications

Background: Non-coding RNA (ncRNA) genes do not encode proteins but produce functional RNA molecules that play crucial roles in many key biological processes. Recent genome-wide transcriptional profiling studies using tiling arrays in organisms such as human and Arabidopsis have revealed a great number of transcripts, a large portion of which have little or no capability to encode proteins. This unexpected finding suggests that the currently known repertoire of ncRNAs may only represent a small fraction of ncRNAs of the organisms. Thus, efficient and effective prediction of ncRNAs has become an important task in bioinformatics in recent years. Among the available …

Ecological Models In Support Of Regulatory Risk Assessments Of Pesticides: Developing A Strategy For The Future [Short Communication], Valery E. Forbes, Udo Hommen, Pernille Thorbek, Fred Heimbach, Paul J. Van Den Brink, Jörn Wogram, Hans-Hermann Thulke, Volker Grimm

Valery Forbes Publications

This brief communication reports on the main findings of the LEMTOX workshop, held from September 9 to 12,2007, at the Helmholtz Centre for Environmental Research (UFZ) in Leipzig, Germany. The workshop brought together a diverse group of stakeholders from academia, regulatory authorities, contract research organizations, and industry, representing Europe, the United States, and Asia, to discuss the role of ecological modeling in risk assessments of pesticides, particularly under the European regulatory framework. The following questions were addressed: What are the potential benefits of using ecological models in pesticide registration and risk assessment? What obstacles prevent ecological modeling from being used …

The Amphipod Orchomenella Pinguis — A Potential Bioindicator For Contamination In The Arctic, Lis Bach, Valery E. Forbes, Ingela Dahllöf

Valery Forbes Publications

Indigenous organisms can be used as bioindicators for effects of contaminants, but no such bioindicator has been established for Arctic areas. Orchomenella pinguis is a benthic amphipod, ubiquitous in the Arctic and can be found in high numbers. We collected O. pinguis at sites with different contamination levels. Population characteristics (body length distribution, average dry weight and amphipod organic content) were related to sediment contaminant concentrations, in order to identify suitable endpoints for using this species as a bioindicator. We show that O. pinguis was prevalent in both clean and contaminated areas, easy to sample and that its population characteristics …

Arginine-Induced Germ Tube Formation In Candida Albicans Is Essential For Escape From Murine Macrophage Line Raw 264.7, Suman Ghosh, Dhammika H. M. L. P. Navarathna, David D. Roberts, Jake T. Cooper, Audrey L. Atkin, Thomas M. Petro, Kenneth W. Nickerson

School of Biological Sciences: Faculty Publications

The opportunistic fungal pathogen Candida albicans is a part of the normal flora but it also causes systemic candidiasis if it reaches the bloodstream. Upon being phagocytized by macrophages, an important component of innate immunity, C. albicans rapidly upregulates a set of arginine biosynthetic genes. Arginine, urea, and CO2 induced hyphae in a density-dependent manner in wild-type, cph1/cph1, and rim101/rim101 strains but not in efg1/efg1 or cph1/cph1 efg1/efg1 strains. Arginase (Car1p) converts arginine to urea, which in turn is degraded by urea amidolyase (Dur1,2p) to produce CO2, a signal for hyphal switching. We used a dur1,2/dur1,2 mutant (KWN6) and the …

Occurrence Of Trichosirocalus Horridus (Coleoptera: Curculionidae) On Native Cirsium Altissimum Versus Exotic C. Vulgare In North American Tallgrass Prairie, Masaru Takahashi, Svata M. Louda, Tom E. X. Miller, Charles W. O'Brien

School of Biological Sciences: Faculty Publications

Postrelease studies can provide data with which to evaluate expectations based on prerelease tests of biological control insects. In 2004, we observed Trichosirocalus horridus Panzer (Coleoptera: Curculionidae), the rosette weevil introduced into North America against Eurasian thistles, feeding on native tall thistle, Cirsium altissimum L. Spreng., in tallgrass prairie. In this study, we examined the rosette weevil's use of tall thistle, compared with its use of the co-occurring exotic bull thistle, C. vulgare (Savi) Tenore. For both thistle species, we quantified weevil frequency, abundance, and seasonal variation in incidence, using both timed observations at two sites over two growing seasons …

Impacts Of Insect Herbivory On Cactus Population Dynamics: Experimental Demography Across An Environmental Gradient, Tom E. X. Miller, Svata M. Louda, Karen A. Rose, James O. Eckberg

School of Biological Sciences: Faculty Publications

Understanding the role of consumers in plant population dynamics is important, both conceptually and practically. Yet, while the negative effects of herbivory on plant performance have been well documented, we know much less about how individuallevel damage translates to impacts on population growth or whether spatial variation in herbivory affects patterns of plant distribution. We studied the role of insect herbivory in the dynamics and distribution of the tree cholla cactus (Opuntia imbricata), a long-lived perennial plant, across an elevational gradient in central New Mexico, USA, from low-elevation grassland (1670 m) to a grassland–mountain transition zone (1720 m) …

Macroevolutionary Tests Of Pollination Syndromes: A Reply To Fenster Et Al., Stacey Dewitt Smith, Cécile Ané, David A. Baum

School of Biological Sciences: Faculty Publications

Studies of floral ecology and evolution are often centered on the idea that particular floral trait combinations, or syndromes, represent adaptations for particular pollinators. Despite the conceptual importance of pollination syndromes, few macroevolutionary studies have statistically examined the relationship between pollinators and floral traits. Using 15 species of Iochroma, Smith et al. applied phylogenetically structured correlation analyses to test the relationship between floral variation and pollination system, quantified in terms of the importance of major pollinator groups. This study revealed that pollinator shifts are tied to changes in nectar reward and floral display but are not significantly correlated with …

Natural History Note No Trade-Off Between Seed Size And Number In The Valley Oak Quercus Lobata, Walter D. Koenig, Johannes M.H. Knops, William J. Carmen, Richard D. Sage

School of Biological Sciences: Faculty Publications

We examined the relationship between acorn mass and number in valley oaks (Quercus lobata) over 4 years in central coastal California. Despite considerable variation in acorn size among both trees and years, trees produced acorns of the same size relative to other trees in different years. Across years, the relationship between acorn mass and acorn crop size was generally positive, even after controlling for environmental conditions and differences in individual tree size and quality. Life-history trade-offs in valley oaks are primarily between current and future reproduction and indirectly between concurrent growth and reproduction, not between seed size and …

Behavioral Response Of Dissimilatory Perchlorate-Reducing Bacteria To Different Electron Acceptors, Yvonne Sun, Ruth L. Gustavson, Nadia Ali, Karrie A. Weber, Lacey L. Westphal, John D. Coates

School of Biological Sciences: Faculty Publications

The response behavior of three dissimilatory perchlorate-reducing bacteria to different electron acceptors (nitrate, chlorate, and perchlorate) was investigated with two different assays. The observed response was speciesspecific, dependent on the prior growth conditions, and was inhibited by oxygen. We observed attraction toward nitrate when Dechloromonas aromatica strain RCB and Azospira suillum strain PS were grown with nitrate. When D. aromatica and Dechloromonas agitata strain CKB were grown with perchlorate, both responded to nitrate, chlorate, and perchlorate. When A. suillum was grown with perchlorate, the organism responded to chlorate and perchlorate but not nitrate. A gene replacement mutant in the perchlorate …

Physiological And Taxonomic Description Of The Novel Autotrophic, Metal Oxidizing Bacterium, Pseudogulbenkiania Sp. Strain 2002, Karrie A. Weber, David B. Hedrick, Aaron D. Peacock, J. Cameron Thrash, David C. White, Laurie A. Achenbach, John D. Coates

School of Biological Sciences: Faculty Publications

A lithoautotrophic, Fe(II) oxidizing, nitratereducing bacterium, strain 2002 (ATCC BAA-1479; =DSM 18807), was isolated as part of a study on nitrate-dependent Fe (II) oxidation in freshwater lake sediments. Here we provide an in-depth phenotypic and phylogenetic description of the isolate. Strain 2002 is a gram-negative, non-spore forming, motile, rod-shaped bacterium which tested positive for oxidase, catalase, and urease. Analysis of the complete 16S rRNA gene sequence placed strain 2002 in a clade within the family Neisseriaceae in the order Nessieriales of the Betaproteobacteria 99.3% similar to Pseudogulbenkiania subflava. Similar to P. sublfava, predominant whole cell fatty acids were …

Sex Effects On Life Span And Senescence In The Wild When Dates Of Birth And Death Are Unknown, Felix Zajitschek, Chad Brassil, Russell Bonduriansky, Robert C. Brooks

School of Biological Sciences: Faculty Publications

Males and females allocate and schedule reproductive effort in very different ways. Because the timing and amount of reproductive effort influence survival and thus the optimization of life histories, mortality and senescence are predicted to be sex specific. However, age-specific mortality rates of wild animals are often difficult to quantify in natural populations. Studies that report mortality rates from natural populations are, therefore, almost entirely confined to long-lived, easy-to-track species such as large mammals and birds. Here, we employ a novel approach using capture–mark–recapture data from a wild population of black field crickets (Teleogryllus commodus) to test for …

Blood Sampling Reduces Annual Survival In Cliff Swallows (Petrochelidon Pyrrhonota) -- La Toma De Muestras De Sangre Reduce La Supervivencia Anual En Petrochelidon Pyrrhonota, Charles R. Brown, Mary Bomberger Brown

School of Biological Sciences: Faculty Publications

Researchers commonly collect blood samples from wild birds, and most workers assume that blood sampling has no adverse effect on the birds’ survival. Few studies, however, have done controlled comparisons among bled and non-bled individuals and estimated survival using modern statistical methodology. We used a data set on Cliff Swallows (Petrochelidon pyrrhonota) that included 2,945 bled and 7,822 non-bled birds captured at the same times and sites in southwestern Nebraska from 1986 to 2006 to estimate annual survival and recapture probabilities of each group. Blood was collected with brachial venipuncture in amounts varying from 0.3% to 1.2% of …

Something Old, Something New, Something Borrowed; How The Thermoacidophilic Archaeon Sulfolobus Solfataricus Responds To Oxidative Stress, Walid S. Maaty, Blake Wiedenheft, Pavel Tarlykov, Nathan Schaff, Joshua Heinemann, Jim Robinson-Cox, Jacob Valenzuela, Amanda Dougherty, Paul H. Blum, C. Martin Lawrence, Trevor Douglas, Mark J. Young, Brian Bothner

School of Biological Sciences: Faculty Publications

To avoid molecular damage of biomolecules due to oxidation, all cells have evolved constitutive and responsive systems to mitigate and repair chemical modifications. Archaea have adapted to some of the most extreme environments known to support life, including highly oxidizing conditions. However, in comparison to bacteria and eukaryotes, relatively little is known about the biology and biochemistry of archaea in response to changing conditions and repair of oxidative damage. In this study transcriptome, proteome, and chemical reactivity analyses of hydrogen peroxide (H2O2) induced oxidative stress in Sulfolobus solfataricus (P2) were conducted. Microarray analysis of mRNA expression showed that 102 transcripts …

Long 3’-Utrs Target Wild-Type Mrnas For Nonsense-Mediated Mrna Decay In Saccharomyces Cerevisiae, Bessie W. Kebaara, Audrey L. Atkin

School of Biological Sciences: Faculty Publications

The nonsense-mediated mRNA decay (NMD) pathway,

present in most eukaryotic cells, is a specialized

pathway that leads to the recognition and rapid

degradation of mRNAs with premature termination

codons and, importantly, some wild-type

mRNAs. Earlier studies demonstrated that aberrant

mRNAs with artificially extended 3’-untranslated

regions (3’-UTRs) are degraded by NMD. However,

the extent to which wild-type mRNAs with long

3’-UTRs are degraded by NMD is not known.

We used a global approach to identify wild-type

mRNAs in Saccharomyces cerevisiae that have

longer than expected 3’-UTRs, and of these

mRNAs tested, 91% were degraded by NMD. We

demonstrate for the first …

Role Of Vapbc Toxin–Antitoxin Loci In The Thermal Stress Response Of Sulfolobus Solfataricus, Charlotte R. Cooper, Amanda J. Daugherty, Sabrina Tachdjian, Paul H. Blum, Robert M. Kelly

School of Biological Sciences: Faculty Publications

TA (toxin–antitoxin) loci are ubiquitous in prokaryotic microorganisms, including archaea, yet

their physiological function is largely unknown. For example, preliminary reports have suggested

that TA loci are microbial stress-response elements, although it was recently shown that knocking

out all known chromosomally located TA loci in Escherichia coli did not have an impact on

survival under certain types of stress. The hyperthermophilic crenarchaeon Sulfolobus solfataricus

encodes at least 26 vapBC (where vap is virulence-associated protein) family TA loci in its

genome. VapCs are PIN (PilT N-terminus) domain proteins with putative ribonuclease activity,

while VapBs are proteolytically labile proteins, which purportedly function …

Evolution And Pleiotropy Of Trithorax Function In Arabidopsis, Zoya Avramova

School of Biological Sciences: Faculty Publications

The SET domain-containing genes of the TRITHORAX family encode epigenetic factors that maintain the expression of targeted genes. Trithorax homologs have been found in both animals and plants. Since these are thought to have evolved multicellularity independently, common mechanisms of epigenetic regulation must be evolutionarily ancient and derived from a common ancestor. In addition, each lineage has evolved unique mechanisms to expand the original repertoire of epigenetic functions. Phylogenetic analysis of SET domain proteins has outlined some intriguing evolutionary trends. In plants, epigenetic gene silencing mechanisms have been aggressively pursued. In contrast, studies of epigenetic mechanisms maintaining active gene expression …

Costs And Benefits Of Freezing Behavior In The Harvestman Eumesosoma Roeweri (Arachnida, Opiliones), Marie-Claire Chelini, Rodrigo H. Willemart, Eileen Hebets

Eileen Hebets Publications

Animals present an enormous variety of behavioral defensive mechanisms, which increase their survival, but often at a cost. Several animal taxa reduce their chances of being detected and/or recognized as prey items by freezing (remaining completely motionless) in the presence of a predator. We studied costs and benefits of freezing in immature Eumesosoma roeweri (Opiliones, Sclerosomatidae). Preliminary observations showed that these individuals often freeze in the presence of the syntopic predatory spider Schizocosa ocreata (Araneae, Lycosidae). We verified that harvestmen paired with predators spent more time freezing than when alone or when paired with a conspecific. Then, we determined that …

Condition-Dependent Alternative Mating Tactics In A Sexually Cannibalistic Wolf Spider, Dustin J. Wilgers, Amy C. Nicholas, David H. Reed, Gail E. Stratton, Eileen Hebets

Eileen Hebets Publications

Condition-dependent male mating tactics often involve high-quality males capitalizing on the outcome of intersexual selection, whereas low-quality males use behaviors that circumvent female choice to achieve copulation. In the wolf spider Rabidosa punctulata, males display 2 distinct mating tactics: 1) “courtship”—consisting of visual and seismic components or 2) “direct mount”—consisting of males grappling/holding females until they assume a copulatory posture. We tested for condition-dependent tactic expression using both field-collected individuals (representing natural variation in body mass and condition) and individuals whose diet we manipulated in the laboratory (representing extreme divergences in body size and condition). Across both natural and …

Caenorhabditis Elegans Genomic Response To Soil Bacteria Predicts Environment-Specific Genetic Effects On Life History Traits, Joseph D. Coolon, Kenneth L. Jones, Timothy C. Todd, Bryanua C. Carr, Michael A. Herman

School of Biological Sciences: Faculty Publications

With the post-genomic era came a dramatic increase in high-throughput technologies, of which transcriptional profiling by microarrays was one of the most popular. One application of this technology is to identify genes that are differentially expressed in response to different environmental conditions. These experiments are constructed under the assumption that the differentially expressed genes are functionally important in the environment where they are induced. However, whether differential expression is predictive of functional importance has yet to be tested. Here we have addressed this expectation by employing Caenorhabditis elegans as a model for the interaction of native soil nematode taxa and …

The Nuclear Receptor Nhr-25 Cooperates With The Wnt/Β-Catenin Asymmetry Pathway To Control Differentiation Of The T Seam Cell In C. Elegans, Martina Hajduskova, Marek Jindra, Michael A. Herman, Masako Asahina

School of Biological Sciences: Faculty Publications

Asymmetric cell divisions produce new cell types during animal development. Studies in Caenorhabditis elegans have identified major signal-transduction pathways that determine the polarity of cell divisions. How these relatively few conserved pathways interact and what modulates them to ensure the diversity of multiple tissue types is an open question. The Wnt/β-catenin asymmetry pathway governs polarity of the epidermal T seam cell in the C. elegans tail. Here, we show that the asymmetry of T-seam-cell division and morphogenesis of the male sensory rays require NHR-25, an evolutionarily conserved nuclear receptor. NHR-25 ensures the neural fate of the T-seam-cell descendants in cooperation …

Origin And Ascendancy Of A Chimeric Fusion Gene: The Β/Δ-Globin Gene Of Paenungulate Mammals, Juan C. Opazo, Angela M. Sloan, Kevin L. Campbell, Jay F. Storz

Jay F. Storz Publications

The δ-globin gene (HBD) of eutherian mammals exhibits a propensity for recombinational exchange with the closely linked β-globin gene (HBB) and has been independently converted by the HBB gene in multiple lineages. Here we report the presence of a chimeric β/δ fusion gene in the African elephant (Loxodonta africana) that was created by unequal crossing-over between misaligned HBD and HBB paralogs. The recombinant chromosome that harbors the β/δ fusion gene in elephants is structurally similar to the ‘‘anti-Lepore’’ duplication mutant of humans (the reciprocal exchange product of the hemoglobin Lepore deletion mutant). However, the situation in …

Evolution Of Duplicated Β-Globin Genes And The Structural Basis Of Hemoglobin Isoform Differentiation In Mus, Amy M. Runck, Hideaki Moriyama, Jay F. Storz

Jay F. Storz Publications

The functional diversification of multigene families may be strongly influenced by mechanisms of concerted evolution such as interparalog gene conversion. The β-globin gene family of house mice (genus Mus) represents an especially promising system for evaluating the effects of gene conversion on the functional divergence of duplicated genes. Whereas the majority of mammalian species possess tandemly duplicated copies of the adult β-globin gene that are identical in sequence, natural populations of house mice are often polymorphic for distinct two-locus haplotypes that differ in levels of functional divergence between duplicated β-globin genes, HBB-T1 and HBB-T2. Here, we use a phylogenetic …

Microbiology Of Oil Fly Larvae, Kenneth Nickerson, Bradley A. Plantz

Kenneth Nickerson Papers

One animal beautifully adapted to the viscous asphalt of the La Brea tar pits is the oil fly Helaeomyia petrolei (Syn. Psilopa). As a normal part of its carnivorous existence the oil fly larval guts are filled with tar, with no adverse effects. Surface sterilized larvae 5 contained ca. 2 x 10 heterotrophic bacteria per larva. These bacteria have been identified as a mixture of enteric bacteria, most commonly Providencia rettgeri, and Acinetobacter spp. These bacteria were clearly growing because their numbers in the larval guts were 100 to 1,000 times greater than in free oil/asphalt. There is …

The Impact Of Co-Occurring Tree And Grassland Species On Carbon Sequestration And Potential Biofuel Production, Ramesh Laungani, Johannes Knops

School of Biological Sciences: Faculty Publications

We evaluated how three co-occurring tree and four grassland species influence potentially harvestable biofuel stocks and above- and belowground carbon pools. After 5 years, the tree Pinus strobus had 6.5 times the amount of aboveground harvestable biomass as another tree Quercus ellipsoidalis and 10 times that of the grassland species. P. strobus accrued the largest total plant carbon pool (1375 gCm -2 or 394 gCm -2 yr), while Schizachyrium scoparium accrued the largest total plant carbon pool among the grassland species (421 gCm -2 or 137 gCm -2 yr). Quercus ellipsoidalis accrued 850 gCm -2, Q. macrocarpa 370 gCm -2, …

Systematic Position Of Pseudocorynosoma And Andracantha (Acanthocephala, Polymorphidae) Based On Nuclear And Mitochondrial Gene Sequences, Martín García-Varela

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Species of Pseudocorynosoma are North and South American acanthocephalans that use waterfowl as definitive hosts and amphipods as intermediate hosts, whereas species of Andracantha occur in fish-eating birds with a worldwide distribution. Pseudocorynosoma and Andracantha were originally described as Corynosoma (now restricted to endoparasites of marine mammals). Morphologically, Andracantha is distinct from other genera of Polymorphidae in possessing 2 fields of spines on the trunk, whereas Corynosoma and Pseudocorynosoma have a single field. A recent phylogenetic hypothesis based on morphological characters suggested that Andracantha is closely related to Corynosoma, whereas Pseudocorynosoma was of uncertain phylogenetic position within the Polymorphidae. …

Rhabditid Nematode-Associated Ophthalmitis And Meningoencephalomyelitis In Captive Asian Horned Frogs (Megophrys Montana) [Case Reports], Denise M. Imai, Steven A. Nadler, Deena Brenner, Taryn A. Donovan, Allan P. Pessier

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Between 2006 and 2008, 4 captive Asian horned frogs (Megophrys montana) were diagnosed with ocular and neurologic disease associated with rhabditid nematodiasis. Mortality, either spontaneous or by humane euthanasia, was high (3/4, 75%). Gross and histologic findings included varying degrees of ulcerative keratitis, histiocytic uveitis and retinitis, meningoencephalomyelitis, and epidermal chromatophore (iridophore) hyperplasia with intralesional nematodes. Entry into the host was presumed to be by direct invasion of the skin and the cornea with migration through the optic nerve to the brain and spinal cord. One frog was diagnosed with rhabditid nematodiasis antemortem, and clinical signs and lesions …