Biology Commons^™

Characterization Of The Rcf1 Q-X3-R-X-R-X3-Q Motif And Its Role In Supporting Oxidative Phosphorylation Enzyme Complexes, Joshua Garlich

Dissertations (1934 -)

Mitochondrial respiratory complexes are critical components of cellular energy production that require tight regulation to ensure optimal function. Rcf1 and Rcf2 are mitochondrial proteins that can physically associate with the yeast respiratory complexes III and IV, and the higher-ordered III-IV respiratory supercomplex that also contains the ADP/ATP translocase, AAC. Rcf1 can physically associate with both complex III and IV independently, and can be chemically crosslinked to AAC, indicating a close physical proximity to a predominant regulator of energy flux within the cell. It was therefore hypothesized that Rcf1, through its physical association with complexes III and IV, and its close …

Danger Signals, Inflammasomes, And The Intricate Intracellular Lives Of Chlamydiae, M. A. Pettengill, A. A. Sater, R. Coutinho-Silva, David M. Ojcius

All Dugoni School of Dentistry Faculty Articles

Chlamydiae are obligate intracellular bacterial pathogens, and as such are sensitive to alterations in the cellular physiology of their hosts. Chlamydial infections often cause pathologic consequences due to prolonged localized inflammation. Considerable advances have been made in the last few years regarding our understanding of how two key inflammation-associated signaling pathways influence the biology of

Design Of Drug Nano-Carriers For Study Of Multidrug Resistance In Single Live Cells, Pavan Kumar Cherukuri

Chemistry & Biochemistry Theses & Dissertations

Multidrug resistance (MDR) exists in both prokaryotic and eukaryotic cells. MDR is responsible for ineffective treatment of a wide range of diseases, such as infections and cancer. The ATP-binding cassette (ABC) membrane transporters (efflux pumps) are one of the largest and most diverse super-families of membrane proteins found in all living organisms, ranging from bacteria to humans. All ABC transporters share a common structure of four core domains; two transmembrane domains (TMD) with variable sequence and topology and two nucleotide-binding domains (NBD) with conserved sequences. Conventional methods for the study of the efflux functions are radioactively labeled substrates and fluorescent …

Talin2-Mediated Traction Force Drives Matrix Degradation And Cell Invasion, Lei Qi, Naser Jafari, Xiang Li, Zaozao Chen, Liqing Li, Vesa P. Hytönen, Benjamin T. Goult, Chang-Guo Zhan, Cai Huang

Markey Cancer Center Faculty Publications

Talin binds to β-integrin tails to activate integrins, regulating cell migration, invasion and metastasis. There are two talin genes, TLN1 and TLN2, encoding talin1 and talin2, respectively. Talin1 regulates focal adhesion dynamics, cell migration and invasion, whereas the biological function of talin2 is not clear and, indeed, talin2 has been presumed to function redundantly with talin1. Here, we show that talin2 has a much stronger binding to β-integrin tails than talin1. Replacement of talin2 Ser339 with Cys significantly decreased its binding to β1-integrin tails to a level comparable to that of talin1. Talin2 localizes at invadopodia and is indispensable …

Foraging Behavior Of Tetramorium Caespitum In An Urban Environment: The Effect Of Food Quality On Foraging, Nicole A. Crofton, Sabrina R. D'Mello, Nene S. Sy

Student Publications

Animals' foraging strategies are directly related to their fitness. Proposed models of optimal foraging assume that animals strategize in terms of maximizing benefits over the cost of acquiring resources. Ants are social insects that are comparable in biomass to humans inhabiting the plant. As such, it is crucial to understand the foraging strategies of such an influential member of the ecosystem. With the ever-increasing rate of urbanization and human encroachment, it is even more important to consider the foraging patterns of species inhabiting urban areas. In this study we investigate optimal foraging strategies in the pavement ant, Tetramorium caespitum. Specifically, …

Pharmacogenetic Discovery In Calgb (Alliance) 90401 And Mechanistic Validation Of A Vac14 Polymorphism That Increases Risk Of Docetaxel-Induced Neuropathy, Daniel L. Hertz, Kouros Owzar, Sherrie Lessans, Claudia Wing, Chen Jiang, William Kevin Kelly, Jai Patel, Susan Halabi, Yoichi Furukawa, Heather E. Wheeler, Alexander B. Sibley, Cameron Lassiter, Lois Weisman, Dorothy Watson, Stefanie D. Krens, Flora Mulkey, Cynthia L. Renn, Eric J. Small, Phillip G. Febbo, Ivo Shterev, Deanna L. Kroetz, Paula N. Friedman, John F. Mahoney, Michael A. Carducci, Michael J. Kelley, Yusuke Nakamura, Michiaki Kubo, Susan G. Dorsey, M. Eileen Dolan, Michael J. Morris, Howard L. Mcleod

Biology: Faculty Publications and Other Works

Purpose

Discovery of single nucleotide polymorphisms (SNPs) that predict a patient's risk of docetaxel-induced neuropathy would enable treatment individualization to maximize efficacy and avoid unnecessary toxicity. The objectives of this analysis were to discover SNPs associated with docetaxel-induced neuropathy and mechanistically validate these associations in preclinical models of drug-induced neuropathy.

Experimental Design

A genome-wide association study was conducted in metastatic castrate-resistant prostate cancer patients treated with docetaxel, prednisone and randomized to bevacizumab or placebo on CALGB 90401. SNPs were genotyped on the Illumina HumanHap610-Quad platform followed by rigorous quality control. The inference was conducted on the cumulative dose at occurrence …

Correlation Analysis Of Enzyme Activities And Deconstruction Of Ammonia-Pretreated Switchgrass By Bacterial-Fungal Communities, Abhiney Jain, H. Sandra Pelle, J. Michael Henson

Biology Faculty Publications

The mixed microbial communities that occur naturally on lignocellulosic feedstocks can provide feedstock-specific enzyme mixtures to saccharify lignocelluloses. Bacterial-fungal communities were enriched from switchgrass bales to deconstruct ammonia-pretreated switchgrass (DSG). Correlation analysis was carried out to elucidate the relationship between microbial decomposition of DSG by these communities, enzymatic activities produced and enzymatic saccharification of DSG using these enzyme mixtures. Results of the analysis showed that β glucosidase activities and xylosidase activities limited the extent of microbial deconstruction and enzymatic saccharification of DSG. The results also underlined the importance of ligninase activity for the enzymatic saccharification of pretreated lignocellulosic feedstock. The …

Covering Ground: A Look At Movement Patterns And Random Walk Behavior In Aquilonastra Sea Stars, Amanda C. Lohmann, Dennis Evangelista, Lindsay D. Waldrop, Christopher L. Mah, Tyson L. Hedrick

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The paths animals take while moving through their environments affect their likelihood of encountering food and other resources; thus, models of foraging behavior abound. To collect movement data appropriate for comparison with these models, we used time-lapse photography to track movements of a small, hardy, and easy-to-obtain organism, Aquilonastra anomala sea stars. We recorded the sea stars in a tank over many hours, with and without a food cue. With food present, they covered less distance, as predicted by theory; this strategy would allow them to remain near food. We then compared the paths of the sea stars to three …

The Urea Carboxylase And Allophanate Hydrolase Activities Of Urea Amidolyase Are Functionally Independent, Yi Lin, Cody J. Boese, Martin St. Maurice

Biological Sciences Faculty Research and Publications

Urea amidolyase (UAL) is a multifunctional biotin-dependent enzyme that contributes to both bacterial and fungal pathogenicity by catalyzing the ATP-dependent cleavage of urea into ammonia and CO₂. UAL is comprised of two enzymatic components: urea carboxylase (UC) and allophanate hydrolase (AH). These enzyme activities are encoded on separate but proximally related genes in prokaryotes while, in most fungi, they are encoded by a single gene that produces a fusion enzyme on a single polypeptide chain. It is unclear whether the UC and AH activities are connected through substrate channeling or other forms of direct communication. Here, we use …

Destabilization Of The Ornithine Decarboxylase Mrna Transcript By The Rna-Binding Protein Tristetraprolin, Shannon L. Nowotarski, Sofia Origanti, Suzanne Sass-Kuhn, Lisa M. Shantz

Biological Sciences Faculty Research and Publications

Ornithine decarboxylase (ODC) is the first and usually rate-limiting enzyme in the polyamine biosynthetic pathway. In a normal physiological state, ODC is tightly regulated. However, during neoplastic transformation, ODC expression becomes upregulated. The studies described here show that the ODC mRNA transcript is destabilized by the RNA-binding protein tristetraprolin (TTP). We show that TTP is able to bind to the ODC mRNA transcript in both non-transformed RIE-1 cells and transformed Ras12V cells. Moreover, using mouse embryonic fibroblast cell lines that are devoid of a functional TTP protein, we demonstrate that in the absence of TTP both ODC mRNA stability and …

Lack Of Interaction Between Erbb2 And Insulin Receptor Substrate Signaling In Breast Cancer, Sarah M. Farabaugh, Bonita T. Chan, Xiaojiang Cui, Robert Dearth, Adrian V. Lee

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Background: ErbB2 Receptor Tyrosine Kinase 2 (ErbB2, HER2/Neu) is amplified in breast cancer and associated with poor prognosis. Growing evidence suggests interplay between ErbB2 and insulin-like growth factor (IGF) signaling. For example, ErbB2 inhibitors can block IGF-induced signaling while, conversely, IGF1R inhibitors can inhibit ErbB2 action. ErbB receptors can bind and phosphorylate insulin receptor substrates (IRS) and this may be critical for ErbBmediated anti-estrogen resistance in breast cancer. Herein, we examined crosstalk between ErbB2 and IRSs using cancer cell lines and transgenic mouse models.

Methods: MMTV-ErbB2 and MMTV-IRS2 transgenic mice were crossed to create hemizygous MMTV-ErbB2/MMTVIRS2 bigenic mice. Signaling crosstalk …

A Francisella-Like Endosymbiont In The Gulf Coast Tick Evolved From A Mammalian Pathogen, Jonathan G. Gerhart, Abraham S. Moses, Rahul Raghavan

Biology Faculty Publications and Presentations

Ticks (order Ixodida) vector pathogenic bacteria that cause diseases in humans and other mammals. They also contain bacteria that are closely related to pathogens but function as endosymbionts that provide nutrients that are missing from mammalian blood—their sole food source. For instance, mammalian pathogens such as Coxiella burnetii and Francisella tularensis, as well as Coxiella-like and Francisella-like endosymbionts (CLEs and FLEs, respectively) occur in ticks worldwide. However, it is not clear whether the pathogens evolved from symbionts or symbionts from pathogens. Recent studies have indicated that C. burnetii likely originated from a tick-associated ancestor, but the origins …

Presence, Absence, And Roosting Ecology Of The Southeastern Myotis And Rafinesque's Big-Eared Bat In The Cache River National Wildlife Refuge, Samuel Andrew Schratz

Student Theses and Dissertations

Four bat species, 2 of special concern, the southeastern myotis (Myotis austroriparius), and Rafinesque’s big-eared bat (Corynorhinus rafinesquii) and 2 threatened and endangered species may occur in one of Arkansas’ largest bottomland hardwood forests, the Cache River National Wildlife Refuge. However, inventory of bat species throughout the refuge is lacking and management plans may not be adequate in promoting the conservation of bats. My goal was to inventory the bats of the Cache River National Wildlife Refuge and determine roosting habits of the southeastern myotis and Rafinesque’s big-eared bat. During summers 2014 and 2015, surveys were conducted throughout the refuge. …

Feralisation Targets Different Genomic Loci To Domestication In The Chicken, M. Johnsson, Eben Gering, P. Willis, S. Lopez, L. Van Dorp, G. Hellenthal, R. Henriksen, U. Friberg, D. Wright

Biology Faculty Articles

Feralisation occurs when a domestic population recolonizes the wild, escaping its previous restricted environment, and has been considered as the reverse of domestication. We have previously shown that Kauai Island's feral chickens are a highly variable and admixed population. Here we map selective sweeps in feral Kauai chickens using whole-genome sequencing. The detected sweeps were mostly unique to feralisation and distinct to those selected for during domestication. To ascribe potential phenotypic functions to these genes we utilize a laboratory-controlled equivalent to the Kauai population—an advanced intercross between Red Junglefowl and domestic layer birds that has been used previously for both …

Comparative Population Genomics And Speciation Of Snakes Across The North American Deserts, Edward A. Myers

Dissertations, Theses, and Capstone Projects

Understanding the process of speciation is of central interest to evolutionary biologists. Speciation can be studied using a phylogeographic approach, by identifying regions that promote lineage divergence, addressing whether speciation has occurred with gene flow, and when extended to multiple taxa, addressing if the same patterns of speciation are shared across codistributed groups with different ecologies. Here I examine the comparative phylogeographic histories and population genomics of thirteen snake taxa that are widely distributed and co-occur across the arid southwest of North America. I first quantify the degree to which these species groups have a shared history of population divergence …

Computerized Classification Of Surface Spikes In Three-Dimensional Electron Microscopic Reconstructions Of Viruses, Younes Benkarroum

Dissertations, Theses, and Capstone Projects

The purpose of this research is to develop computer techniques for improved three-dimensional (3D) reconstruction of viruses from electron microscopic images of them and for the subsequent improved classification of the surface spikes in the resulting reconstruction. The broader impact of such work is the following.

Influenza is an infectious disease caused by rapidly-changing viruses that appear seasonally in the human population. New strains of influenza viruses appear every year, with the potential to cause a serious global pandemic. Two kinds of spikes – hemagglutinin (HA) and neuraminidase (NA) – decorate the surface of the virus particles and these proteins …

The Regulation Of The Phosphatidate Phosphatase Gene Pah1 And Its Regulatory Role On Cell Homeostasis, Goldie Libby Sherr

Dissertations, Theses, and Capstone Projects

The Saccharomyces cerevisiae gene, PAH1, encodes a phosphatidate (PA) phosphatase that plays a fundamental role in lipid metabolism. PA phosphatases are key enzymes that catalyze the PA dephosphorylation reaction to form diacylglycerides, the first step in the synthesis of triacylglycerols. Pah1p, one of the main PA phosphatases in yeast, has not only emerged as a key player in lipid biosynthetic pathways, but also acts as an important regulator of nuclear membrane biogenesis, the transcriptional regulation of many inositol-sensitive upstream activating sequence (UAS_INO)containing genes needed for phospholipid synthesis, vacuole homeostasis, and lipid droplet formation. Due to its …

Sweating The Small Stuff: Linking Plankton To Climate Change, Brian Kim '18 Makes Conncetions, Stephen Collins

Colby Magazine

It takes an expansive mind to connect microscopic marine copepods (certain crustacean plankton) unwittingly chomping on floating microplastics with a bigger picture: the planet’s carbon pump and global climate change. But that’s what Brian Kim ’18 decided to investigate during Jan Plan, working with Bigelow Lab Senior Research Scientist David Fields.

Red Flour Beetle, Tribolium Castaneum, Development On Rice Fractions And Oviposition Preference, Brook A. Hale

Student Theses and Dissertations

The red flour beetle (RFB), Tribolium castaneum (Herbst), is a stored-product insect commonly found in rice mills. To understand how RFBs develop on different types of rice fractions occurring in a rice mill, I conducted three studies. I examined egg to adult development on nine rice fractions (rough rice, rice hulls, paddy rice dust, brown rice, rice bran, milled broken kernels, milled whole kernels, milled rice dust and rice flour) and identified brown rice, bran, milled kernels and rice flour were best for development. A second study examined neonate adult development using rice fractions and temperature as variables and found …

Weighted-Samgsr: Combining Significance Analysis Of Microarray-Gene Set Reduction Algorithm With Pathway Topology-Based Weights To Select Relevant Genes, Suyan Tian, Howard H. Chang, Chi Wang

Biostatistics Faculty Publications

Background: It has been demonstrated that a pathway-based feature selection method that incorporates biological information within pathways during the process of feature selection usually outperforms a gene-based feature selection algorithm in terms of predictive accuracy and stability. Significance analysis of microarray-gene set reduction algorithm (SAMGSR), an extension to a gene set analysis method with further reduction of the selected pathways to their respective core subsets, can be regarded as a pathway-based feature selection method.

Methods: In SAMGSR, whether a gene is selected is mainly determined by its expression difference between the phenotypes, and partially by the number of pathways to …

A Novel Qtl Associated With Dwarf Bunt Resistance In Idaho 444 Winter Wheat, Jianli Chen, Mary J. Guttieri, Junli Zhang, David Hole, Edward Souza, Blair Goates

Green Canyon Environmental Research Area, Logan Utah

Dwarf bunt [Tilletia controversa J.G. Kühn [as ‘contraversa’], in Rabenhorst, Hedwigia 13: 188 (1874)] is a destructive disease of wheat (Triticum aestivum L.) that reduces grain yield and quality. A number of distinct genes conferring resistance to dwarf bunt have been used by breeding programs for nearly 100 years. However, few markers were identified that can be used in selection of dwarf bunt resistance. A recombinant inbred line (RIL) population derived from the bunt-resistant germplasm, Idaho 444 (IDO444), and the susceptible cultivar, Rio Blanco, was evaluated for phenotypic reaction to dwarf bunt inoculation in four trials in …

Nitrogen Loading Leads To Increased Carbon Accretion In Both Invaded And Uninvaded Coastal Wetlands, Jason P. Martina, William S. Currie, Deborah E. Goldberg, Kenneth J. Elgersma

Faculty Work

Gaining a better understanding of carbon (C) dynamics across the terrestrial and aquatic landscapes has become a major research initiative in ecosystem ecology. Wetlands store a large portion of the global soil C, but are also highly dynamic ecosystems in terms of hydrology and N cycling, and are one of the most invaded habitats worldwide. The interactions between these factors are likely to determine wetland C cycling, and specifically C accretion rates. We investigated these interactions using MONDRIAN, an individual-based model simulating plant growth and competition and linking these processes to N and C cycling. We simulated the effects of …

Transitions In Morphologies, Fluid Regimes, And Feeding Mechanisms During Development Of The Medusa Lychnorhiza Lucerna, Renato M. Nagata, André C. Morandini, Sean Colin, Alvaro E. Migotto, John H. Costello

Arts & Sciences Faculty Publications

The early ontogeny of scyphomedusae involves morphological and functional transitions in body plans that affect the predators' propulsive and feeding strategies. We applied highspeed videography digital particle image velocimetry (DPIV), and dye visualization techniques to evaluate alterations in swimming and feeding mechanisms during ontogeny of the rhizostome medusa Lychnorhiza lucerna Haeckel, 1880 (Scyphozoa, Rhizostomeae). During early ontogeny the ephyral mouth lips develop into complex filtering structures along the oral arms. The viscous environments (Reynolds number < 100) experienced by ephyrae constrain the feeding mechanisms that transport fluid during ephyral bell pulsations. In contrast, adult medusan fluid flows are dominated by inertial forces, and bell pulsations effectively transport fluids and entrained prey toward the oral arms. The oral arm surfaces are covered by motile epidermal cilia that drive these entrained flows through filtering gaps in the oral arms where food particles are retained. In addition to this process within the oral arms, vortices generated during bell pulsation flow downstream along the outside of the medusae and continuously transport prey toward the exterior oral arm surfaces. Although calanoid copepods are capable of escape velocities that greatly exceed L. lucerna's feeding current speeds, copepods often fail to detect the predator's feeding currents or inadvertently jump into medusan capture surfaces during failed escape attempts. Consequently, the comparatively weak predator feeding currents successfully capture a portion of the copepods encountered by swimming medusae. These results clarify the processes that enable rhizostome medusae to play key roles as consumers in tropical and subtropical coastal environments.

Dissection Of Molecular Assembly Dynamics By Tracking Orientation And Position Of Single Molecules In Live Cells, Shalin B. Mehta, Molly Mcquilken, Patrick J. La Riviere, Patricia Occhipinti, Amitabh Verma, Rudolf Oldenbourg, Amy Gladfelter, Tomomi Tani

Dartmouth Scholarship

Regulation of order, such as orientation and conformation, drives the function of most molecular assemblies in living cells but remains difficult to measure accurately through space and time. We built an instantaneous fluorescence polarization microscope, which simultaneously images position and orientation of fluorophores in living cells with single-molecule sensitivity and a time resolution of 100 ms. We developed image acquisition and analysis methods to track single particles that interact with higher-order assemblies of molecules. We tracked the fluctuations in position and orientation of molecules from the level of an ensemble of fluorophores down to single fluorophores. We tested our system …

Fhf-Independent Conduction Of Action Potentials Along The Leak-Resistant Cerebellar Granule Cell Axon, Katarzyna Dover, Christopher Marra, Sergio Solinas, Marko Popovic, Sathyaa Subramaniyam, Dejan Zecevic, Egidio D'Angelo, Mitchell Goldfarb

Publications and Research

Neurons in vertebrate central nervous systems initiate and conduct sodium action potentials in distinct subcellular compartments that differ architecturally and electrically. Here, we report several unanticipated passive and active properties of the cerebellar granule cell’s unmyelinated axon. Whereas spike initiation at the axon initial segment relies on sodium channel (Nav)-associated fibroblast growth factor homologous factor (FHF) proteins to delay Nav inactivation, distal axonal Navs show little FHF association or FHF requirement for high-frequency transmission, velocity and waveforms of conducting action potentials. In addition, leak conductance density along the distal axon is estimated as o1% that of somatodendritic membrane. The faster …

Different Roads Lead To Rome: Integrative Taxonomic Approaches Lead To The Discovery Of Two New Lizard Lineages In The Liolaemus Montanus Group (Squamata: Liolaemidae), Cesar Aguilar, Perry L. Wood Jr., Mark C. Belk, Mike H. Duff, Jack W. Sites Jr.

Faculty Publications

Integrative taxonomy (IT) is becoming a preferred approach to delimiting species boundaries by including different empirical criteria. IT methods can be divided into two types of procedures both of which use multiple kinds of evidence: step-by-step approaches test hypotheses by sequential evaluation in a hypothetic-deductive framework, while model-based procedures delimit groups based on statistical information criteria. In this study we used a step-by-step approach and a Gaussian clustering (GC) method to test species boundaries in the northernmost species of the Liolaemus montanus group. We used different methods based on mitochondrial and nuclear DNA sequence data, morphological measures and niche envelope …

The Spatial Distribution And Density Of The Emerald Ash Borer Infestation In Rock Island And Moline, Il, Kendall Smith, Victoria Lason, Tierney Brosius, Michael Reisner

Celebration of Learning

The Emerald Ash Borer (EAB) Agrilus planipennis Fairmaire (Copleoptera: Buprestidae) is a destructive colonizer of ash trees that arrived in the United States in 2002. Since then, EAB has been detected in 22 states and two Canadian provinces, and has proven to be a complicated management issue for many cities including Rock Island. The purpose of this study was to determine the spatial distribution and density of the EAB infestation in Rock Island, Ill and to identify potential correlations between host larval densities and visual symptoms. A continuation of spatial distribution was determined through a tree survey examining specific species …

Traversing Swanton Road, 23rd Ed., James A. West

Academic, Government & Associated Organizational Research Resources

Situated at the northwest end of Santa Cruz County and occupying circa 30 square miles of sharply contrasted terrain, the Scott Creek Watershed concentrates within its geomorphological boundaries, at least 10-12% of California's flora, both native and introduced. Incorporated within this botanical overview but technically not part of the watershed sensustrictu, are the adjacent environs, ranging from the coastal strand up through the Western Terrace to the ocean draining ridge tops..... with the Arroyo de las Trancas/Last Chance Ridge defining the western/northwestern boundary and the Molino Creek divide, the southern demarcation. Paradoxically, the use/abuse that the watershed has sustained over …

The Transcriptional Repressor Icer Binds To Multiple Loci Throughout The Genome, Carlos A. Molina, Luis C. Muñiz

Department of Biology Faculty Scholarship and Creative Works

The events culminating in ovulation are controlled by the cyclical actions of hormones such as Follical Stimulating Hormone (FSH) and Luteinizing Hormone (LH). The secondary messenger, cyclic AMP (cAMP) conveys the intracellular activity of these hormones. It is well established that a family of transcription factors facilitate cAMP mediated gene expression, yet it remains unknown how these factors directly affect ovulation. One of these factors, Inducible cAMP Early Repressor (ICER) has been implicated in the transcriptional regulation of cAMP inducible genes during folliculogenesis and ovulation. In order to better determine the role of ICER in ovarian function we have identified …

Sperm Morphometrics, Spermatogenesis, And Testicular Cycle Of The Rough Greensnake (Opheodrys Aestivus), John Douglas Konvalina

Student Theses and Dissertations

Spermatogenesis in ophidians is understudied, with little information on the rough greensnake, Opheodrys aestivus available. A cell wheel showing the chronological development of germ cell stages for this species was constructed. Sperm morphometrics were completed and compared with those of Nerodia rhombifer, the diamondback watersnake. Both species had similar sperm head length, while Opheodrys aestivus had significantly longer total sperm length. Total sperm length was positively correlated (r = 0.997, p < 0.001) with sperm tail length. Seminiferous tubule diameter and seminiferous tubule epithelial height were measured from Arkansas (AR) specimens and compared with those of Alabama (AL) specimens and AR measurements were found to be significantly greater in length. Future studies of O. aestivus need to investigate the testicular cycle in other parts of its geographic distribution to see if the monthly pattern is consistent and sperm morphometrics should be examined for other species within the family Colubridae.