Life Sciences Commons^™

The Cell Division Gene Ftsz2 Of Sinorhizobium Meliloti Is Expressed At High Levels In Host Plant Medicago Truncatula Nodules In The Absence Of Sini, Muhamad Ali K. Shakhatreh, Jayne B. Robinson

Biology Faculty Publications

In this study, we investigated the role of quorum sensing (QS) in expression of the Sinorhizobium meliloti cell division gene ftsZ2 in free-living cells and within nodules of its host plant, Medicago truncatula. Using a ftsZ2 promoter reporter fusion, we were able to track the expression of this gene in wild-type S. meliloti cells and QS mutant backgrounds in planta. Our findings revealed that expression of ftsZ2 in free-living cells was changed or reduced in sinI mutant cells compared with wild-type cells while expression in planta was substantially higher in the absence of sinI. The results further clarify the involvement …

Patterns Of Gene Expression In Microarrays And Expressed Sequence Tags From Normal And Cataractous Lenses, Konstantinos Sousounis, Panagiotis A. Tsonis

Biology Faculty Publications

In this contribution, we have examined the patterns of gene expression in normal and cataractous lenses as presented in five different papers using microarrays and expressed sequence tags. The purpose was to evaluate unique and common patterns of gene expression during development, aging and cataracts.

Lens Regeneration In Axolotl: New Evidence Of Developmental Plasticity, Rinako Suetsugu-Maki, Nobuyasu Maki, Saulius Sumanas, Jie Zhu, Katia Del Rio-Tsonis, Panagiotis A. Tsonis

Biology Faculty Publications

Background: Among vertebrates lens regeneration is most pronounced in newts, which have the ability to regenerate the entire lens throughout their lives. Regeneration occurs from the dorsal iris by transdifferentiation of the pigment epithelial cells. Interestingly, the ventral iris never contributes to regeneration. Frogs have limited lens regeneration capacity elicited from the cornea during pre-metamorphic stages. The axolotl is another salamander which, like the newt, regenerates its limbs or its tail with the spinal cord, but up until now all reports have shown that it does not regenerate the lens.

Conservation Of The Three-Dimensional Structure In Non-Homologous Or Unrelated Proteins, Konstantinos Sousounis, Carl E. Haney, Jin Cao, Bharath Sunchu, Panagiotis A. Tsonis

Biology Faculty Publications

In this review, we examine examples of conservation of protein structural motifs in unrelated or non-homologous proteins. For this, we have selected three DNA-binding motifs: the histone fold, the helix-turn-helix motif, and the zinc finger, as well as the globin-like fold. We show that indeed similar structures exist in unrelated proteins, strengthening the concept that three-dimensional conservation might be more important than the primary amino acid sequence.

Detection Of Mycobacterium Ulcerans In The Environment Predicts Prevalence Of Buruli Ulcer In Benin, Heather R. Williamson, Mark Eric Benbow, Lindsay P. Cambell, Christian R. Johnson, Ghislain Sopoh, Yves Barogui, Richard W. Merritt, Pamela L. C. Small

Biology Faculty Publications

Background: Mycobacterium ulcerans is the causative agent of Buruli ulcer (BU), a destructive skin disease found predominantly in sub-Saharan Africa and south-eastern Australia. The precise mode(s) of transmission and environmental reservoir(s) remain unknown, but several studies have explored the role of aquatic invertebrate species. The purpose of this study was to investigate the environmental distribution of M. ulcerans in south-eastern Australia.

An Improved Competitive Inhibition Enzymatic Immunoassay Method For Tetrodotoxin Quantification, James P. Strange, Becky L. Williams, Susannah S. French

Biology Faculty Publications

Quantifying tetrodotoxin (TTX) has been a challenge in both ecological and medical research due to the cost, time and training required of most quantification techniques. Here we present a modified Competitive Inhibition Enzymatic Immunoassay for the quantification of TTX, and to aid researchers in the optimization of this technique for widespread use with a high degree of accuracy and repeatability.

Improved Ex Vivo Method For Microbiocidal Activity Across Vertebrate Species, Susannah S. French, Lorin A. Neuman-Lee

Biology Faculty Publications

The field of ecoimmunology is currently undergoing rapid expansion, whereby biologists from a wide range of ecological disciplines are increasingly interested in assessing immunocompetence in their study organisms. One of the key challenges to researchers is determining what eco-immune measures to use in a given experiment. Moreover, there are limitations depending on study species, requirements for specific antibodies, and relevance of the methodology to the study organism. Here we introduce an improved ex vivo method for microbiocidal activity across vertebrate species. The utility of this assay is that it determines the ability of an organism to remove a pathogen that …

Interfamily Variation In Amphibian Early Life-History Traits: Raw Material For Natural Selection?, Gareth R. Hopkins, Brian G. Gall, Susannah S. French, Edmund D. Brodie Jr.

Biology Faculty Publications

The embryonic development and time to hatching of eggs can be highly adaptive in some species, and thus under selective pressure. In this study, we examined the underlying interfamily variation in hatching timing and embryonic development in a population of an oviparous amphibian, the rough-skinned newt (Taricha granulosa). We found significant, high variability in degree of embryonic development and hatching timing among eggs from different females. Patterns of variation were present regardless of temperature.We also could not explain the differences among families by morphological traits of the females or their eggs. This study suggests that the variation necessary for natural …

Widespread Triploidy In Western North American Aspen (Populus Tremuloides), Karen E. Mock, Colin M. Callahan, M. Nurul Islam-Faridi, John D. Shaw, Hardeep S. Rai, Stewart C. Sanderson, Carol A. Rowe, Ronald J. Rye, Michael D. Madritch, Richard S. Gardner, Paul G. Wolf

Biology Faculty Publications

We document high rates of triploidy in aspen (Populus tremuloides) across the western USA (up to 69% of genets), and ask whether the incidence of triploidy across the species range corresponds with latitude, glacial history (as has been documented in other species), climate, or regional variance in clone size. Using a combination of microsatellite genotyping, flow cytometry, and cytology, we demonstrate that triploidy is highest in unglaciated, drought-prone regions of North America, where the largest clone sizes have been reported for this species. While we cannot completely rule out a low incidence of undetected aneuploidy, tetraploidy or duplicated loci, our …

Methodological Tools, Ethan P. White, Xiao Xiao, J. B. Nick, Richard M. Sibly

Biology Faculty Publications

Methodological approaches for comparing metabolic theory predictions to empirical data fall into two general categories: 1) determining if the general functional form of a relationship predicted by the theory is valid; and 2) determining whether the observed values of the parameters match the specific quantitative predictions made by the theory. Both of these categories of analysis rely on being able to accurately determine the best fitting form of a model with the same general functional form as that of MTE, so we will begin by discussing how this has typically been done using OLS regression on appropriately transformed data. Potential …

Investigating Human Impact In The Environment With Faded Scaffolded Inquiry Supported By Technologies, D. T. Longhurst, M. Longhurst, A. M. Duffy, Paul G. Wolf

Biology Faculty Publications

Teaching science as inquiry is advocated in all national science education documents and by leading science and science teaching organizations. In addition to teaching science as inquiry, we recognize that learning experiences need to connect to students’ lives. This article details how we use a sequence of faded scaffolded inquiry supported by technologies to engage students meaningfully in science connected to their lives and schoolyards. In this approach, more teacher guidance is provided earlier in the inquiry experiences before this is faded later in the sequence, as students are better prepared to complete successful inquiries. The sequence of inquiry experiences …

Direct Fitness Correlates And Thermal Consequences Of Facultative Aggregation In A Desert Lizard, Alison R. Davis Rabosky, Ammon Corl, Heather E.M. Liwanag, Yann Surget-Groba, Barry Sinervo

Biology Faculty Publications

Social aggregation is a common behavioral phenomenon thought to evolve through adaptive benefits to group living. Comparing fitness differences between aggregated and solitary individuals in nature – necessary to infer an evolutionary benefit to living in groups – has proven difficult because communally-living species tend to be obligately social and behaviorally complex. However, these differences and the mechanisms driving them are critical to understanding how solitary individuals transition to group living, as well as how and why nascent social systems change over time. Here we demonstrate that facultative aggregation in a reptile (the Desert Night Lizard, Xantusia vigilis) confers …

Reproducible Hairy Root Transformation And Spot-Inoculation Methods To Study Root Symbioses Of Pea, Scott R. Clemow, Lindsey Clairmont, Lene H. Madsen, Frédérique C. Guinel

Biology Faculty Publications

Pea has lagged behind other model legumes in the molecular study of nodulation and mycorrhizae-formation because of the difficulty to transform its roots and its poor growth on agar plates. Here we describe for pea 1) a transformation technique which permits the complementation of two known non-nodulating pea mutants, 2) a rhizobial inoculation method which allows the study of early cellular events giving rise to nodule primordia, and 3) a targeted fungal inoculation method which allows us to study short segments of mycorrhizal roots assured to be infected. These tools are certain to advance our knowledge of pea root symbioses.

Protein Trap Lines Of Drosophila To Demonstrate Spatio-Temporal Localization Of Proteins In An Undergraduate Lab, Oorvashi Roy Puli, Amit Singh

Biology Faculty Publications

The objective of this teaching note is to generate a laboratory exercise, which allows students to get a hands-on experience of a cell biology technique. The short duration of the laboratory classes is the biggest challenge with the development of a cell biology lab for an undergraduate curriculum. Therefore, it is necessary to design a laboratory exercise that enables the students to carry out cell biological assays in the desired time. This laboratory exercise focuses on tracking protein expression levels along a spatial (space) and temporal (time) axis in developing Drosophila melanogaster organ primordium. Here we use the protein trap …

Quantitative Comparison Of Cis-Regulatory Element (Cre) Activities In Transgenic Drosophila Melanogaster, William A. Rogers, Thomas M. Williams

Biology Faculty Publications

Gene expression patterns are specified by cis-regulatory element (CRE) sequences, which are also called enhancers or cis-regulatory modules. A typical CRE possesses an arrangement of binding sites for several transcription factor proteins that confer a regulatory logic specifying when, where, and at what level the regulated gene(s) is expressed. The full set of CREs within an animal genome encodes the organism′s program for development¹, and empirical as well as theoretical studies indicate that mutations in CREs played a prominent role in morphological evolution^2-4. Moreover, human genome wide association studies indicate that genetic variation in CREs …

Molecular Systematics Of The Middle American Genus Hypopachus (Anura: Microhylidae), Eli Greenbaum, Eric N. Smith, Rafael O. De Sá

Biology Faculty Publications

We present the first phylogenetic study on the widespread Middle American microhylid frog genus Hypopachus. Partial sequences of mitochondrial (12S and 16S ribosomal RNA) and nuclear (rhodopsin) genes (1275 bp total) were analyzed from 43 samples of Hypopachus, three currently recognized species of Gastrophryne, and seven arthroleptid, brevicipitid and microhylid outgroup taxa. Maximum parsimony (PAUP), maximum likelihood (RAxML) and Bayesian inference (MrBayes) optimality criteria were used for phylogenetic analyses, and BEAST was used to estimate divergence dates of major clades. Population-level analyses were conducted with the programs NETWORK and Arlequin. Results confirm the placement of Hypopachus …

Heart And Ventilatory Measures In Crayfish During Copulation, Richard M. Cooper, Heidi Schapker Finucane, Megan Adami, Robin L. Cooper

Biology Faculty Publications

Monitoring heart rate (HR) and ventilatory rate (VR) during defined sensory stimuli and during aggressive and submissive social interactions has provided additional information of a crayfish's physiological state which is not achieved by behavioral observations. In this study, the HR and VR of crayfish were monitored before, during and after the act of copulation in both heterosexual partners. The female crayfish abruptly reduces HR and VR during copulation but the male maintains HR and VR. After separation from copulation the female HR and VR are elevated, potentially paying back the O₂ debt. The tight relationship with HR and VR …

Minimal Structural Requirements Of Alkyl Γ-Lactones Capable Of Antagonizing The Cocaine-Induced Motility Decrease In Planarians, Debra Baker, Sean Deats, Peter Boor, James Pruitt, Oné R. Pagán

Biology Faculty Publications

We recently reported that the natural cyclic lactone, parthenolide, and related analogs prevent the expression of behavioral effects induced by cocaine in planarians and that parthenolide’s γ-lactone ring is required for this effect. In the present work, we tested a series of alkyl γ-lactones with varying chain length (1–8 carbons) to determine their ability to antagonize the planarian motility decrease induced by 200 μM cocaine. Alkyl lactones with up to a 4-carbon alkyl chain did not affect planarian motility or antagonized the cocaine-induced motility decrease; only the compound γ-nonalactone (a γ-lactone with a 5-carbon chain) was able to prevent the …

Laboratory Diagnosis Of Clostridium Difficile Infection: Can Molecular Amplification Methods Move Us Out Of Uncertainty?, Fred C. Tenover, Ellen Jo Baron, Lance R. Peterson, David Persing

Biology Faculty Publications

The laboratory diagnosis of Clostridium difficile infection (CDI) continues to be challenging. Recent guidelines from professional societies in the United States note that enzyme immunoassays for toxins A and B do not have adequate sensitivity to be used alone for detecting CDI, yet the optimal method for diagnosing this infection remains unclear. Nucleic acid amplification tests (NAATs) that target chromosomal toxin genes (usually the toxin B gene, tcdB) show high sensitivity and specificity, provide rapid results, and are amenable to both batch and on-demand testing, but these tests were not universally recommended for routine use in the recent guidelines. …

Linking Fruit Traits To Variation In Predispersal Vertebrate Seed Predation, Insect Seed Predation, And Pathogen Attack, Noelle G. Beckman, Helene C. Muller-Landau

Biology Faculty Publications

The importance of vertebrates, invertebrates, and pathogens for plant communities has long been recognized, but their absolute and relative importance in early recruitment of multiple coexisting tropical plant species has not been quantified. Further, little is known about the relationship of fruit traits to seed mortality due to natural enemies in tropical plants. To investigate the influences of vertebrates, invertebrates, and pathogens on reproduction of seven canopy plant species varying in fruit traits, we quantified reductions in fruit development and seed germination due to vertebrates, invertebrates, and fungal pathogens through experimental removal of these enemies using canopy exclosures, insecticide, and …

Loss-Of-Function Of Constitutive Expresser Of Pathogenesis Related Genes5 Affects Potassium Homeostasis In Arabidopsis Thaliana, Monica Borghi, Ana Rus, David E. Salt

Biology Faculty Publications

Here, we demonstrate that the reduction in leaf K+ observed in a mutant previously identified in an ionomic screen of fast neutron mutagenized Arabidopsis thaliana is caused by a loss-of-function allele of CPR5, which we name cpr5-3. This observation establishes low leaf K+ as a new phenotype for loss-of-function alleles of CPR5. We investigate the factors affecting this low leaf K+ in cpr5 using double mutants defective in salicylic acid (SA) and jasmonic acid (JA) signalling, and by gene expression analysis of various channels and transporters. Reciprocal grafting between cpr5 and Col-0 was used to determine the relative importance of …

Activation Of Jnk Signaling Mediates Amyloid-Ss- Dependent Cell Death, Meghana Tare, Rohan Modi, Jaison Nainaparampil, Oorvashi Roy Puli, Shimpi Bedi, Pedro Fernandez-Funez, Madhuri Kango-Singh, Amit Singh

Biology Faculty Publications

Background: Alzheimer's disease (AD) is an age related progressive neurodegenerative disorder. One of the reasons for Alzheimer's neuropathology is the generation of large aggregates of Aß42 that are toxic in nature and induce oxidative stress, aberrant signaling and many other cellular alterations that trigger neuronal cell death. However, the exact mechanisms leading to cell death are not clearly understood.

Methodology/Principal Findings: We employed a Drosophila eye model of AD to study how Aß42 causes cell death. Misexpression of higher levels of Aß42 in the differentiating photoreceptors of fly retina rapidly induced aberrant cellular phenotypes and cell death. We found that …

No Evidence Of Association Between Hiv-1 And Malaria In Populations With Low Hiv-1 Prevalence, Diego F. Cuadros, Adam J. Branscum, Gisela García-Ramos

Biology Faculty Publications

BACKGROUND: The geographic overlap between HIV-1 and malaria has generated much interest in their potential interactions. A variety of studies have evidenced a complex HIV-malaria interaction within individuals and populations that may have dramatic effects, but the causes and implications of this co-infection at the population level are still unclear. In a previous publication, we showed that the prevalence of malaria caused by the parasite Plasmodium falciparum is associated with HIV infection in eastern sub-Saharan Africa. To complement our knowledge of the HIV-malaria co-infection, the objective of this work was to assess the relationship between malaria and HIV prevalence in …

Effect Of Variable Transmission Rate On The Dynamics Of Hiv In Sub-Saharan Africa, Diego F. Cuadros, Phillip H. Crowley, Ben Augustine, Sarah L. Stewart, Gisela García-Ramos

Biology Faculty Publications

BACKGROUND: The cause of the high HIV prevalence in sub-Saharan Africa is incompletely understood, with heterosexual penile-vaginal transmission proposed as the main mechanism. Heterosexual HIV transmission has been estimated to have a very low probability; but effects of cofactors that vary in space and time may substantially alter this pattern.

METHODS: To test the effect of individual variation in the HIV infectiousness generated by co-infection, we developed and analyzed a mathematical sexual network model that simulates the behavioral components of a population from Malawi, as well as the dynamics of HIV and the co-infection effect caused by other infectious diseases, …

Origin Of Amphibian And Avian Chromosomes By Fission, Fusion, And Retention Of Ancestral Chromosomes, Stephen R. Voss, D. Kevin Kump, Srikrishna Putta, Nathan Pauly, Anna Reynolds, Rema J. Henry, Saritha Basa, John A. Walker, Jeramiah J. Smith

Biology Faculty Publications

Amphibian genomes differ greatly in DNA content and chromosome size, morphology, and number. Investigations of this diversity are needed to identify mechanisms that have shaped the evolution of vertebrate genomes. We used comparative mapping to investigate the organization of genes in the Mexican axolotl (Ambystoma mexicanum), a species that presents relatively few chromosomes (n = 14) and a gigantic genome (>20 pg/N). We show extensive conservation of synteny between Ambystoma, chicken, and human, and a positive correlation between the length of conserved segments and genome size. Ambystoma segments are estimated to be four to 51 times longer than homologous …

Disseminated Neoplasia And Clam Populations In A Canadian National Park-Kouchibouguac National Park., S. Anne Boettger, M J. Abgrall, N Taraska, L Leblanc, E Tremblay

Biology Faculty Publications

No abstract provided.

Disseminated Neoplasia In Mya Arenaria Linked To Chronic Heavy Metal Pollution., S. Anne Boettger, N G. Taraska, J Joseph, C W. Walker

Biology Faculty Publications

No abstract provided.

The Role Of Crassostrea Virginica Hemocytes In Shell Formation: Ex Vivo Mineral Deposition By Cultured Hemocytes, Emily A. Untener, Douglas C. Hansen, Karolyn Hansen

Biology Faculty Publications

Abstract of Technical Paper Presented at the 103rd Annual Meeting National Shellfisheries Association Baltimore, Maryland March 27–31, 2011

The Cellular Model Of Eastern Oyster (Grassostrea Virginica) Shell Formation, Andrew S. Mount, Neeraj V. Gohad, Karolyn Hansen, Mary Beth Johnstone, Douglas C. Hansen

Biology Faculty Publications

No abstract provided.

Survival, Breeding Frequency, And Migratory Orientation In The Jefferson Salamander, Ambystoma Jeffersonianum, Stephen P. De Lisle, Kristine L. Grayson

Biology Faculty Publications

Accurate estimates of demographic parameters, such as survival and breeding frequency, are necessary for the conservation and management of animal populations. Additionally, life-history data are required for gaining an empirical understanding of the ecology of natural populations. We monitored a population of Jefferson Salamanders (Ambystoma jeffersonianum) breeding in a permanent mountain-top pond at the southern limit of this species’ geographic range in Virginia over four years. We used closed multistate mark-recapture models with Pollock's robust design to estimate the demographic parameters of this population. Additionally, we used point-of-capture data to compare the orientation of migrations into and out …