Biology Commons^™

Gene Expression Patterns Specific To The Regenerating Limb Of The Mexican Axolotl, James R. Monaghan, Antony Athippozhy, Ashley W. Seifert, Sri Putta, Arnold J. Stromberg, Malcolm Maden, David M. Gardiner, Stephen R. Voss

Biology Faculty Publications

Salamander limb regeneration is dependent upon tissue interactions that are local to the amputation site. Communication among limb epidermis, peripheral nerves, and mesenchyme coordinate cell migration, cell proliferation, and tissue patterning to generate a blastema, which will form missing limb structures. An outstanding question is how cross-talk between these tissues gives rise to the regeneration blastema. To identify genes associated with epidermis-nerve-mesenchymal interactions during limb regeneration, we examined histological and transcriptional changes during the first week following injury in the wound epidermis and subjacent cells between three injury types; 1) a flank wound on the side of the animal that …

Seed Dimorphism, Nutrients And Salinity Differentially Affect Seed Traits Of The Desert Halophyte Suaeda Aralocaspica Via Multiple Maternal Effects, Lei Wang, Jerry M. Baskin, Carol C. Baskin, J. Hans C. Cornelissen, Ming Dong, Zhenying Huang

Biology Faculty Publications

BACKGROUND: Maternal effects may influence a range of seed traits simultaneously and are likely to be context-dependent. Disentangling the interactions of plant phenotype and growth environment on various seed traits is important for understanding regeneration and establishment of species in natural environments. Here, we used the seed-dimorphic plant Suaeda aralocaspica to test the hypothesis that seed traits are regulated by multiple maternal effects.

RESULTS: Plants grown from brown seeds had a higher brown:black seed ratio than plants from black seeds, and germination percentage of brown seeds was higher than that of black seeds under all conditions tested. However, the coefficient …

Serotonin And Synaptic Transmission At Invertebrate Neuromuscular Junctions, Wen-Hui Wu, Robin L. Cooper

Biology Faculty Publications

The serotonergic system in vertebrates and invertebrates has been a focus for over 50 years and will likely continue in the future. Recently, genomic analysis and discovery of alternative splicing and differential expression in tissues have increased the knowledge of serotonin (5-HT) receptor types. Comparative studies can provide useful insights to the wide variety of mechanistic actions of 5-HT responsible for behaviors regulated or modified by 5-HT. To determine cellular responses and influences on neural systems as well as the efferent control of behaviors by the motor units, preparations amenable to detailed studies of synapses are beneficial as working models. …

The Acute And Chronic Effect Of Low Temperature On Survival, Heart Rate And Neural Function In Crayfish (Procambarus Clarkii) And Prawn (Macrobrachium Rosenbergii) Species, Yoo Sun Chung, Richard M. Cooper, Justin Graff, Robin L. Cooper

Biology Faculty Publications

The effect of acute and chronic cold exposure on heart rate (HR) and neuronal function in crayfish Procambarus clarkii and prawns Macrobrachium rosenbergii was addressed. This is particularly important since prawn farms of this species are used for aquaculture in varied climates world wide. The success of P. clarkii as an invasive species throughout the world may in part be due to their ability to acclimate to cold and warm habitats. A set of experiments was devised to address the physiological abilities of these species in managing rapid changes to cold environments as well as their ability to respond to …

Reproductive Characteristics Of A Populus Euphratica Population And Prospects For Its Restoration In China, Dechang Cao, Jingwen Li, Zhenying Huang, Carol C. Baskin, Jerry M. Baskin, Peng Hao, Weilei Zhou, Junqing Li

Biology Faculty Publications

Populus euphratica is a dominant tree in riparian ecosystems in arid areas of northwest China, but it fails to regenerate in these systems. This study evaluates causes for the failure of sexual and asexual regeneration of this species in the wild. P. euphratica disperses as many as 85743 seeds/m² during summer, and the seeds germinate to 92.0% in distilled water and to 60.8% on silt. However, very few seeds (3.6%) can germinate on unflooded soil. The seed-rain season is prolonged by temporal variability in seed dispersal among individuals, which ensures that seedling emergence can occur during favorable conditions (i.e., …

Skin Regeneration In Adult Axolotls: A Blueprint For Scar-Free Healing In Vertebrates, Ashley W. Seifert, James R. Monaghan, S. Randal Voss, Malcolm Maden

Biology Faculty Publications

While considerable progress has been made towards understanding the complex processes and pathways that regulate human wound healing, regenerative medicine has been unable to develop therapies that coax the natural wound environment to heal scar-free. The inability to induce perfect skin regeneration stems partly from our limited understanding of how scar-free healing occurs in a natural setting. Here we have investigated the wound repair process in adult axolotls and demonstrate that they are capable of perfectly repairing full thickness excisional wounds made on the flank. In the context of mammalian wound repair, our findings reveal a substantial reduction in hemostasis, …

Variable Effect Of Co-Infection On The Hiv Infectivity: Within-Host Dynamics And Epidemiological Significance, Diego F. Cuadros, Gisela García-Ramos

Biology Faculty Publications

BACKGROUND: Recent studies have implicated viral characteristics in accounting for the variation in the HIV set-point viral load (spVL) observed among individuals. These studies have suggested that the spVL might be a heritable factor. The spVL, however, is not in an absolute equilibrium state; it is frequently perturbed by immune activations generated by co-infections, resulting in a significant amplification of the HIV viral load (VL). Here, we postulated that if the HIV replication capacity were an important determinant of the spVL, it would also determine the effect of co-infection on the VL. Then, we hypothesized that viral factors contribute to …

The Bird Of Time: Cognition And The Avian Biological Clock, Vincent M. Cassone, David F. Westneat

Biology Faculty Publications

Avian behavior and physiology are embedded in time at many levels of biological organization. Biological clock function in birds is critical for sleep/wake cycles, but may also regulate the acquisition of place memory, learning of song from tutors, social integration, and time-compensated navigation. This relationship has two major implications. First, mechanisms of the circadian clock should be linked in some way to the mechanisms of all these behaviors. How is not yet clear, and evidence that the central clock has effects is piecemeal. Second, selection acting on characters that are linked to the circadian clock should influence aspects of the …

Environmentally Realistic Exposure To The Herbicide Atrazine Alters Some Sexually Selected Traits In Male Guppies, Kausalya Shenoy

Biology Faculty Publications

Male mating signals, including ornaments and courtship displays, and other sexually selected traits, like male-male aggression, are largely controlled by sex hormones. Environmental pollutants, notably endocrine disrupting compounds, can interfere with the proper functioning of hormones, thereby impacting the expression of hormonally regulated traits. Atrazine, one of the most widely used herbicides, can alter sex hormone levels in exposed animals. I tested the effects of environmentally relevant atrazine exposures on mating signals and behaviors in male guppies, a sexually dimorphic freshwater fish. Prolonged atrazine exposure reduced the expression of two honest signals: the area of orange spots (ornaments) and the …

Central And Peripheral Regulation Of Circadian Gastrointestinal Rhythms, Jaclyn Malloy

Theses and Dissertations--Biology

Circadian clocks are responsible for daily rhythms in gastrointestinal function which are vital for normal digestive rhythms and health. The present study examines the roles of the circadian pacemaker, the suprachiasmatic nuclei (SCN), and the sympathetic nervous system in regulation of circadian gastrointestinal rhythms in Mus musculus. Surgical ablation of the SCN abolishes circadian locomotor, feeding, and stool output rhythms when animals are presented with food ad libitum, while restricted feeding reestablishes these rhythms temporarily. In intact mice, chemical sympathectomy with 6- hydroxydopamine has no effect on feeding and locomotor rhythmicity, but attenuates stool output rhythms. Again, restricted …

The Biology And Management Of Brucellosis In Yellowstone Bison, John Joseph Treanor

Theses and Dissertations--Biology

Disease management along the boundaries of wildlife reserves is a growing conservation problem worldwide, as infected wildlife can migrate outside protected areas and pose a threat to livestock and human health. The bison Bison bison population in Yellowstone National Park has long been infected with Brucella abortus, the bacterium causing bovine brucellosis. Concern over migratory bison transmitting B. abortus to cattle herds on lands adjacent to Yellowstone has led to proposals for bison vaccination. Model simulations suggest that vaccination is unlikely to eradicate B. abortus from Yellowstone bison but could be an effective tool for reducing the level of …

Investigating The Ped Protein And Its Effect On Translational Control In Drosophila Melanogaster Spermatogenesis, David C. Keesling

Theses and Dissertations--Biology

Inactive mutants of the ped gene cause two phenotypes in Drosophila melanogaster: male sterility and the early translation of DHODH within spermatogenesis. Investigation of the PED amino acid sequence revealed an OTU domain and an ubiquitin interacting motif, suggesting that it is a member of the otubain sub-family of de-ubiqutinating enzymes. To test this, the putative active cysteine residue was mutated. Results show that this single cysteine residue is required for ped to confer male fertility. Purified wild type PED was also used to carry out in vitro deubiquitinating assays. These assays failed to show any ability for PED …

When Molecules And Morphology Clash: Revisiting Species Tree Reconstruction Of Ambystomatid Salamanders Using Multiple Nuclear Loci, Joshua Steven Williams

Theses and Dissertations--Biology

The analysis of diverse data sets can yield different phylogenetic estimates that challenge systematists to explain the source of discordance. The Ambystomatidae are a classic example of this phylogenetic conflict. Previous attempts to resolve the ambystomatid species tree using allozymic, morphological, and mitochondrial sequence data have yielded different estimates, making it unclear which data source best approximates ambystomatid phylogeny. We present the first multi-locus DNA sequencebased phylogenetic study of the Ambystomatidae. Because independent loci can contain discordant gene tree histories, concatenating unlinked loci into a single data matrix can lead to strongly supported and erroneous results. Therefore, we utilized a …

The Effects Of Spatial Configuration Of Populations On The Maintenance Of The Sexes In A Clonal Organism, Christopher Stieha

Theses and Dissertations--Biology

Despite the two-fold advantage to asexual reproduction and its prevalence in a variety of organisms, sexual reproduction is prevalent across all taxa. The maintenance of two sexes is required to ensure genetic diversity and to prevent “evolutionary dead ends,” especially in clonal organisms. Many mechanisms have been proposed for the maintenance of two sexes, ranging from environmental variation and stochasticity, parasites and predators, and mutation rates. Spatial configuration, the size and location of populations with respect to other populations, can allow two competitors to coexist when one would normally be lost. This is especially important when the two competitors are …

Ecosystem Impacts Of The Invasive Shrub Lonicera Maackii Are Influenced By Associations With Native Tree Species, Megan Marie Poulette

Theses and Dissertations--Biology

Invasive species are significant drivers of global environmental change, altering the stability and functioning of numerous ecosystems. The exotic shrub Lonicera maackii is an aggressive invader throughout much of the eastern United States. While much is known about its population and community impacts, little is known about effects on ecosystem processes.

This dissertation documents changes in ecosystem processes associated with L. maackii growing beneath three native tree species (Fraxinus quadrangulata, Quercus muehlenbergii, Carya ovata) in a savanna in Kentucky. Like many invasive plants, L. maackii litter decomposed and lost nitrogen (N) rapidly, especially in comparison with …

Empirical And Conceptual Approaches To Life-History Trade-Offs: The Size And Number Of Offspring In Broods Of A Parasitoid Wasp, Yoriko Saeki

Theses and Dissertations--Biology

Trade-offs in resource allocation underlie key life history traits of organisms. My dissertation focuses on the size-number trade-off in clonal broods of offspring using the polyembryonic wasp, Copidosoma bakeri parasitizing immature stages of the moth Agrotis ipsilon. I aim to characterize responses of wasp brood size and individual body mass by manipulating the environments in order to understand the allocation pattern in the size number trade-off. In reviewing the functional forms of trade-off relationships in relation to resource constraints, I distinguish among three main trade-off types based on graphical representations of the relationship between the trade-off variables: linear, convex …

Ecology Of Mating Patterns And Sexual Selection In Dickcissels Breeding In Managed Prairie, Bridget Frances Sousa

Theses and Dissertations--Biology

Males of many species have elaborate phenotypes that are absent in females and that are thought to be the result of sexual selection. Sexual selection requires: (i) variance in male mating success, (ii) variation in male phenotype, and (iii) covariation between male mating success and male phenotype. Environmental conditions influence these factors, and management practices that alter environmental conditions have the potential to shape mating patterns and sexual selection. I investigated the hypothesis that the frequency of fire, used to manage tallgrass prairie, affects the mating patterns and process of sexual selection in the organisms breeding in managed prairies.

I …

The Ecological And Evolutionary Effects Of Endocrine Disrupting Compounds On Sexually Selected Traits In Male Guppies, Kausalya Shenoy

Theses and Dissertations--Biology

Male mating signals convey important mate-quality information to females and are regulated by androgens. Endocrine disrupting compounds (EDCs) are chemicals that interfere with proper hormonal functioning in exposed animals, causing altered hormone levels and resulting in changed reproductive characteristics, including mating signals. Altered signals can have ecological implications by influencing population and community dynamics and evolutionary implications via trans-generational reduction in signal reliability leading to reduced preference and eventual loss of the signal trait. I examined the effects of exposure to environmentally relevant concentrations of atrazine, a widely used herbicide and EDC, on mating signals and behaviors in male guppies, …

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 …

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, …

Cooperative And Antagonistic Contributions Of Two Heterochromatin Proteins To Transcriptional Regulation Of The Drosophila Sex Determination Decision, Hui Li, Janel Rodriguez, Youngdong Yoo, Momin Mohammed Shareef, Ramakrishna Badugu, Jamila I. Horabin, Rebecca Kellum

Biology Faculty Publications

Eukaryotic nuclei contain regions of differentially staining chromatin (heterochromatin), which remain condensed throughout the cell cycle and are largely transcriptionally silent. RNAi knockdown of the highly conserved heterochromatin protein HP1 in Drosophila was previously shown to preferentially reduce male viability. Here we report a similar phenotype for the telomeric partner of HP1, HOAP, and roles for both proteins in regulating the Drosophila sex determination pathway. Specifically, these proteins regulate the critical decision in this pathway, firing of the establishment promoter of the masterswitch gene, Sex-lethal (Sxl). Female-specific activation of this promoter, Sxl(Pe), is essential to females, as it provides SXL …

Structure/Function Assessment Of Synapses At Motor Nerve Terminals, Andrew Fredericks Moser Johnstone, Kert Viele, Robin L. Cooper

Biology Faculty Publications

The release of transmitter at neuromuscular junctions (NMJ) of the opener muscle in crayfish is quantal in nature. This NMJ offers the advantage of being able to record quantal events at specific visually identified release sites, thus allowing measurement of the physiological parameters of vesicle release and its response to be directly correlated with synaptic structure.

These experiments take advantage of areas between the varicosities on the nerve terminal that we define as "stems." Stems were chosen as the region to study because of their low synaptic output due to fewer synaptic sites. Through 3D reconstruction from hundreds of serial …

Increased Population Sampling Confirms Low Genetic Divergence Among Pteropus (Chiroptera: Pteropodidae) Fruit Bats Of Madagascar And Other Western Indian Ocean Islands, Lauren M. Chan, Steven M. Goodman, Michael D. Nowak, David W. Weisrock, Anne D. Yoder

Biology Faculty Publications

Fruit bats of the genus Pteropus occur throughout the Austral-Asian region west to islands off the eastern coast of Africa. Recent phylogenetic analyses of Pteropus from the western Indian Ocean found low sequence divergence and poor phylogenetic resolution among several morphologically defined species. We reexamine the phylogenetic relationships of these taxa by using multiple individuals per species. In addition, we estimate population genetic structure in two well-sampled taxa occurring on Madagascar and the Comoro Islands (P. rufus and P. seychellensis comorensis). Despite finding a similar pattern of low sequence divergence among species, increased sampling provides insight into the phylogeographic history …

Membrane Potentials, Synaptic Responses, Neuronal Circuitry, Neuromodulation And Muscle Histology Using The Crayfish: Student Laboratory Exercises, Brittany Baierlein, Alison L. Thurow, Harold L. Atwood, Robin L. Cooper

Biology Faculty Publications

The purpose of this report is to help develop an understanding of the effects caused by ion gradients across a biological membrane. Two aspects that influence a cell's membrane potential and which we address in these experiments are: (1) Ion concentration of K⁺ on the outside of the membrane, and (2) the permeability of the membrane to specific ions. The crayfish abdominal extensor muscles are in groupings with some being tonic (slow) and others phasic (fast) in their biochemical and physiological phenotypes, as well as in their structure; the motor neurons that innervate these muscles are correspondingly different in …

Physiological Experimentation With The Crayfish Hindgut: A Student Laboratory Exercise, Ann S. Cooper, Bonnie Leksrisawat, Allison B. Gilberts, A. Joffre Mercier, Robin L. Cooper

Biology Faculty Publications

The purpose of the report is to describe dissection techniques for preparing the crayfish hindgut and to demonstrate how to make physiological recordings with a force transducer to monitor the strength of contraction. In addition, we demonstrate how to visually monitor peristaltic activity, which can be used as a bioassay for various peptides, biogenic amines and neurotransmitters. This preparation is amenable to student laboratories in physiology and for demonstrating pharmacological concepts to students. This preparation has been in use for over 100 years, and it still offers much as a model for investigating the generation and regulation of peristaltic rhythms …

Modeling Biological Membranes With Circuit Boards And Measuring Electrical Signals In Axons: Student Laboratory Exercises, Martha M. Robinson, Jonathan M. Martin, Harold L. Atwood, Robin L. Cooper

Biology Faculty Publications

This is a demonstration of how electrical models can be used to characterize biological membranes. This exercise also introduces biophysical terminology used in electrophysiology. The same equipment is used in the membrane model as on live preparations. Some properties of an isolated nerve cord are investigated: nerve action potentials, recruitment of neurons, and responsiveness of the nerve cord to environmental factors.

Engineering Proteins With Unique Characteristics For Diagnostics And Biosensors, Smita Joel

University of Kentucky Doctoral Dissertations

Proteins possess a broad range of structural and functional properties and, therefore, can be employed in a variety of biomedical applications. While a good number of protein-based biosensing systems and biosensors for target analytes have been developed, the search for versatile, highly sensitive and selective sensors with long term stability able to provide fast detection of target analytes continues to be a challenge. To that end, we now report the design and development of modified proteins with tailored characteristics and their further utilization in the development of biosensing systems.

We take advantage of binding proteins that undergo a change in …

The Role Of Co-Infection In The Spread Of Hiv In Sub-Saharan Africa, Diego Fernando Cuadros

Theses and Dissertations--Biology

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 a very low probability; further, a single estimation of heterosexual probability of HIV transmission fails to reproduce the variation associated with important biological cofactors. In particular, studies of HIV incidence suggest that co-infection with other infectious diseases influence the HIV transmission, and therefore might substantially vary the pattern of the spread of the infection. To assess the effect of co-infection on the spread of HIV, I developed and analyzed several mathematical and statistical models …

The Ecology Of Disturbances And Global Change In The Montane Grasslands Of The Nilgiris, South India, Madhusudan P. Srinivasan

University of Kentucky Doctoral Dissertations

Biodiversity rich regions worldwide face threats from various global change agents. This research quantifies environmental influences on vegetation, and the impacts of exotic woody plant invasion and anthropogenic nitrogen (N) deposition in a global biodiversity hotspot. The study was conducted in the montane grasslands of the Nilgiris, Western Ghats, and outlines potential management options for this region. Specifically, I examined (1) the role of environmental factors in influencing native plant distribution and ecosystem properties, (2) the status and impact of exotic shrub (Scotch broom, henceforth broom) invasion, (3) the role of disturbances in the success of broom, (4) the role …