Digital Commons Network^™

A Structural And Dynamic Model For The Assembly Of Replication Protein A On Single-Stranded Dna, Luke A. Yates, Ricardo J. Aramayo, Nilisha Pokhrel, Colleen C. Caldwell, Joshua A. Kaplan, Rajika L. Perera, Maria Spies, Edwin Antony, Xiaodong Zhang

Biological Sciences Faculty Research and Publications

Replication Protein A (RPA), the major eukaryotic single stranded DNA-binding protein, binds to exposed ssDNA to protect it from nucleases, participates in a myriad of nucleic acid transactions and coordinates the recruitment of other important players. RPA is a heterotrimer and coats long stretches of single-stranded DNA (ssDNA). The precise molecular architecture of the RPA subunits and its DNA binding domains (DBDs) during assembly is poorly understood. Using cryo electron microscopy we obtained a 3D reconstruction of the RPA trimerisation core bound with ssDNA (∼55 kDa) at ∼4.7 Å resolution and a dimeric RPA assembly on ssDNA. FRET-based solution studies …

A Force Sensor That Converts Fluorescence Signal Into Force Measurement Utilizing Short Looped Dna, Golam Mustafa, Cho-Ying Chuang, William A. Roy, Mohamed M. Farhath, Nilisha Pokhrel, Yue Ma, Kazuo Nagawawa, Edwin Antony, Matthew J. Comstock, Soumitra Basu, Hamza Balci

Biological Sciences Faculty Research and Publications

A force sensor concept is presented where fluorescence signal is converted into force information via single-molecule Förster resonance energy transfer (smFRET). The basic design of the sensor is a ~100 base pair (bp) long double stranded DNA (dsDNA) that is restricted to a looped conformation by a nucleic acid secondary structure (NAS) that bridges its ends. The looped dsDNA generates a tension across the NAS and unfolds it when the tension is high enough. The FRET efficiency between donor and acceptor (D&A) fluorophores placed across the NAS reports on its folding state. Three dsDNA constructs with different lengths were bridged …

Phosphate Removal And Recovery Using Immobilized Phosphatebinding Proteins, Kaushik Venkiteshwaran, Nilisha Pokhrel, Faten Hussein, Edwin Antony, Brooke K. Mayer

Biological Sciences Faculty Research and Publications

Progress towards a more circular phosphorus economy necessitates development of innovative water treatment systems which can reversibly remove inorganic phosphate (P_i) to ultra-low levels (<100 μg L⁻¹), and subsequently recover the P_i for reuse. In this study, a novel approach using the high-affinity E. coli phosphate binding protein (PBP) as a reusable P_i bio-adsorbent was investigated. PBP was expressed, extracted, purified and immobilized on NHS-activated Sepharose beads. The resultant PBP beads were saturated with P_i and exposed to varying pH (pH 4.7 to 12.5) and temperatures (25–45 °C) to induce P_i release. Increase in …

Distinct Proteostasis Circuits Cooperate In Nuclear And Cytoplasmic Protein Quality Control, Rahul S. Samant, Christine M. Livingston, Emily M. Sontag, Judith Frydman

Biological Sciences Faculty Research and Publications

Protein misfolding is linked to a wide array of human disorders, including Alzheimer’s disease, Parkinson’s disease and type II diabetes^1,2. Protective cellular protein quality control (PQC) mechanisms have evolved to selectively recognize misfolded proteins and limit their toxic effects^{3,4,5,6,7,8,9}, thus contributing to the maintenance of the proteome (proteostasis). Here we examine how molecular chaperones and the ubiquitin–proteasome system cooperate to recognize and promote the clearance of soluble misfolded proteins. Using a panel of PQC substrates with distinct characteristics and localizations, we define distinct chaperone and ubiquitination circuitries that execute quality control in the cytoplasm and nucleus. …

A Host–Parasite Model Explains Variation In Liana Infestation Among Co‐Occurring Tree Species, Marco D. Visser, Helene C. Muller-Laudau, Stefan A. Schnitzer, Hans De Kroon, Eelke Jongejans, S. Joseph Wright

Biological Sciences Faculty Research and Publications

1. Lianas are structural parasites of trees that reduce the growth, survival and reproduction of their hosts. Given that co‐occurring tree species differ strongly in the proportion of individuals that are infested by lianas (liana prevalence), lianas could differentially impact tree species and thereby influence tree community composition. Surprisingly, little is known about what governs variation in liana prevalence.
2. Here, we apply an approach inspired by disease ecology to investigate the dynamics of liana prevalence over 11 years on Barro Colorado Island, Panama. We followed the fate of 1,938 individual trees from 21 tree species, recording deaths and change in liana …

Testing Ecological Theory With Lianas, Stefan A. Schnitzer

Biological Sciences Faculty Research and Publications

Lianas constitute a diverse polyphyletic plant group that is advancing our understanding of ecological theory. Specifically, lianas are providing new insights into the mechanisms that control plant distribution and diversity maintenance. For example, there is now evidence that a single, scalable mechanism may explain local, regional, and pan‐tropical distribution of lianas, as well as the maintenance of liana species diversity. The ability to outcompete trees under dry, stressful conditions in seasonal forests provides lianas a growth advantage that, over time, results in relatively high abundance in seasonal forests and low abundance in aseasonal forests. Lianas may also gain a similar …

Agricultural Contamination Impacts Antibiotic Resistance Gene Abundances In River Bed Sediment Temporally, Rachelle E. Beattie, Michael P. Walsh, Mercedes Cecilia Cruz, L. Rex Mcaliley, Laurel Dodgen, Wei Zheng, Krassimira R. Hristova

Biological Sciences Faculty Research and Publications

Kewaunee County, Wisconsin is an agricultural area dominated by concentrated animal feeding operations and manure fertilized cropland. The objective of this study was to characterize chemical and antibiotic resistance gene (ARG) profiles of 20 surface water locations in Kewaunee County to better understand relationships between agricultural contamination and ARG abundance over one year. Surface water (n = 101) and bed sediment (n = 93) were collected from 20 sites during five timepoints between July 2016 and May 2017. Samples were analyzed for six genes (erm(B), tet(W), sul1, qnrA, intI1 and 16S rRNA) and water chemistry …

A Comprehensive Synthesis Of Liana Removal Experiments In Tropical Forests, Sergio Estrada-Villegas, Stefan A. Schnitzer

Biological Sciences Faculty Research and Publications

Lianas are a quintessential feature of tropical forests and are often perceived as being poorly studied. However, liana removal studies may be one of the most common experimental manipulations in tropical forest ecology. In this review, we synthesize data from 64 tropical liana removal experiments conducted over the past 90 yr. We explore the direction and magnitude of the effects of lianas on tree establishment, growth, survival, reproduction, biomass accretion, and plant and animal diversity in ecological and forestry studies. We discuss the geographical biases of liana removal studies and compare the various methods used to manipulate lianas. Overall, we …

Effects Of Lianas And Hurricane Wilma On Tree Damage In The Yucatan Peninsula, Mexico, Edgardo I. Garrido-Pérez, Juan Manuel Dupuy, Rafael Durán-García, Mario Ucan-May, Stefan A. Schnitzer, Gerhard Gerold

Biological Sciences Faculty Research and Publications

Climate change may increase the intensity of hurricanes (Emanuel 1987, 2003), and thus the size of disturbance in tropical forests. As a consequence, disturbance-specialist plants, such as lianas, may increase in abundance there (Phillips & Gentry 1994). Putz (1984) hypothesized that lianas create larger treefall gaps by connecting trees together and pulling down multiple trees during storms. This positive-feedback cycle may increase the prevalence of lianas in disturbed tropical forests (Schnitzer & Bongers 2002, Schnitzer & Carson 2001). Alternatively, Putz (1984) proposed that lianas tie and stabilize canopies together, resulting in less disturbance. Forest age may determine the role of …

Effects Of Elevated H+ And PI On The Contractile Mechanics Of Skeletal Muscle Fibres From Young And Old Men: Implications For Muscle Fatigue In Humans, Christopher W. Sundberg, Sandra K. Hunter, Todd A. Trappe, Carolyn S. Smith, Robert H. Fitts

Biological Sciences Faculty Research and Publications

The present study aimed to identify the mechanisms responsible for the loss in muscle power and increased fatigability with ageing by integrating measures of whole‐muscle function with single fibre contractile mechanics. After adjusting for the 22% smaller muscle mass in old (73–89 years, n = 6) compared to young men (20–29 years, n = 6), isometric torque and power output of the knee extensors were, respectively, 38% and 53% lower with age. Fatigability was ∼2.7‐fold greater with age and strongly associated with reductions in the electrically‐evoked contractile properties. To test whether cross‐bridge mechanisms could explain age‐related decrements in knee extensor …

Metabolic Comparison Of One-Anastomosis Gastric Bypass, Single-Anastomosis Duodenal-Switch, Roux-En-Y Gastric Bypass, And Vertical Sleeve Gastrectomy In Rat, Deanna M. Arble, Simon S. Evers, Nadajda Bozadjieva, Henriette Frikke-Schmidt, Andriy Myronovych, Alfor Lewis, Mouhamadoul Habib Toure, Randy J. Seeley

Biological Sciences Faculty Research and Publications

Background

One-anastomosis gastric bypass (OAGB) and single-anastomosis duodenal switch (SADS) have become increasingly popular weight loss strategies. However, data directly comparing the effectiveness of these procedures with Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (SG) are limited.

Objectives

To examine the metabolic outcomes of OAGB, SADS, RYGB, and SG in a controlled rodent model.

Setting

Academic research laboratory, United States.

Methods

Surgeries were performed in diet-induced obese Long-Evans rats, and metabolic outcomes were monitored before and for 15 weeks after surgery.

Results

All bariatric procedures induced weight loss compared with sham that lasted throughout the course of the study. …

Hepatic Glucagon-Receptor Signaling Enhances Insulin-Stimulated Glucose Disposal In Rodents, Teayoun Kim, Cassie L. Holleman, Shelly Nason, Deanna M. Arble, Nickki Ottaway, Joseph Chabenne, Christine Loyd, Jeong-A Kim, Darleen A. Sandoval, Daniel J. Drucker, Richard Dimarchi, Diego Perez-Tilve, Kirk M. Habegger

Biological Sciences Faculty Research and Publications

Glucagon receptor (GCGR) agonists cause hyperglycemia but also weight loss. However, GLP1R/GCGR mixed agonists do not exhibit the diabetogenic effects often attributed to GCGR activity. Thus, we sought to investigate the effect of glucagon agonism on insulin action and glucose homeostasis. Acute GCGR agonism induced immediate hyperglycemia, followed by improved glucose tolerance and enhanced glucose-stimulated insulin secretion. Moreover, acute GCGR agonism improved insulin tolerance in a dose-dependent manner in both lean and obese mice. Improved insulin tolerance was independent of GLP1R, FGF21, and hepatic glycogenolysis. Moreover, we observed increased glucose infusion rate, disposal, uptake, and suppressed endogenous glucose production during …

The Mitochondrial Single-Stranded Dna Binding Protein From S. Cerevisiae, Rim1, Does Not Form Stable Homo-Tetramers And Binds Dna As A Dimer Of Dimers, Saurabh P. Singh, Vandna Kukshal, Paolo De Bona, Edwin Antony, Roberto Galletto

Biological Sciences Faculty Research and Publications

Rim1 is the mitochondrial single-stranded DNA binding protein in Saccharomyces cerevisiae and functions to coordinate replication and maintenance of mtDNA. Rim1 can form homo-tetramers in solution and this species has been assumed to be solely responsible for ssDNA binding. We solved structures of tetrameric Rim1 in two crystals forms which differ in the relative orientation of the dimers within the tetramer. In testing whether the different arrangement of the dimers was due to formation of unstable tetramers, we discovered that while Rim1 forms tetramers at high protein concentration, it dissociates into a smaller oligomeric species at low protein concentrations. A …

Early Selection Of Bzip73 Facilitated Adaptation Of Japonica Rice To Cold Climates, Citao Liu, Shujun Ou, Bigang Mao, Jiuyou Tang, Wei Wang, Hongru Wang, Shouyun Cao, Michael Schläppi, Bingran Zhao, Guoying Xiao, Xiping Wang, Chengeai Chu

Biological Sciences Faculty Research and Publications

Cold stress is a major factor limiting production and geographic distribution of rice (Oryza sativa). Although the growth range of japonica subspecies has expanded northward compared to modern wild rice (O. rufipogon), the molecular basis of the adaptation remains unclear. Here we report bZIP73, a bZIP transcription factor-coding gene with only one functional polymorphism (+511 G>A) between the two subspecies japonica and indica, may have facilitated japonica adaptation to cold climates. We show the japonica version of bZIP73 (bZIP73^Jap) interacts with bZIP71 and modulates ABA levels and ROS homeostasis. Evolutionary and …

Energy Transduction In Nitrogenase, Lance C. Seefeldt, Brian M. Hoffman, John W. Peters, Simone Raugei, David N. Beratan, Edwin Antony, Dennis R. Dean

Biological Sciences Faculty Research and Publications

Nitrogenase is a complicated two-component enzyme system that uses ATP binding and hydrolysis energy to achieve one of the most difficult chemical reactions in nature, the reduction of N2 to NH3. One component of the Mo-based nitrogenase system, Fe protein, delivers electrons one at a time to the second component, the catalytic MoFe protein. This process occurs through a series of synchronized events collectively called the “Fe protein cycle”. Elucidating details of the events associated with this cycle has constituted an important challenge in understanding the nitrogenase mechanism. Electron delivery is a multistep process involving three metal clusters with intra- …

The Bidirectional Relationship Between Obstructive Sleep Apnea And Metabolic Disease, Sarah N. Framnes, Deanna M. Arble

Biological Sciences Faculty Research and Publications

Obstructive sleep apnea (OSA) is a common sleep disorder, effecting 17% of the total population and 40–70% of the obese population (1, 2). Multiple studies have identified OSA as a critical risk factor for the development of obesity, diabetes, and cardiovascular diseases (3–5). Moreover, emerging evidence indicates that metabolic disorders can exacerbate OSA, creating a bidirectional relationship between OSA and metabolic physiology. In this review, we explore the relationship between glycemic control, insulin, and leptin as both contributing factors and products of OSA. We conclude that while insulin and leptin action may contribute …

Poultry And Beef Meat As Potential Seedbeds For Antimicrobial Resistant Enterotoxigenic Bacillus Species: A Materializing Epidemiological And Potential Severe Health Hazard, Kamelia M. Osman, Ahmed Orabi, Anthony D. Kappell, Khalid S. Al-Maary, Ayman S. Mubarak, Turki M. Dawoud, Ihab M.I. Moussa, Hassan A. Hemeg, Ashgan M. Hessain, Hend M.Y. Yousef, Krassimira R. Hristova

Biological Sciences Faculty Research and Publications

Although Bacillus cereus is of particular concern in food safety and public health, the role of other Bacillus species was overlooked. Therefore, we investigated the presence of eight enterotoxigenic genes, a hemolytic gene and phenotypic antibiotic resistance profiles of Bacillusspecies in retail meat samples. From 255 samples, 124 Bacillus isolates were recovered, 27 belonged to B. cereusand 97 were non-B. cereus species. Interestingly, the non-B. cereus isolates carried the virulence genes and exhibited phenotypic virulence characteristics as the B. cereus. However, correlation matrix analysis revealed the B. cereus group positively …

Molecular Adaptations For Sensing And Securing Prey And Insight Into Amniote Genome Diversity From The Garter Snake Genome, Perry W. Perry, Daren C. Card, Joel W. Mcglothlin, Giulia I.M. Pasquesi, Richard H. Adams, Drew R. Schield, Nicole R. Hales, Andrew B. Corbin, Jeffery P. Demuth, Federico G. Hoffmann, Michael W. Vandewege, Ryan K. Schott, Nihar Bhattacharyya, Belinda S.W. Chang, Nicholas R. Casewell, Gareth Whiteley, Jacobo Reyes-Velasco, Stephen P. Mackessy, Tony Gamble, Kenneth B. Storey, Kyle K. Biggar, Courtney N. Passow, Chih-Horng Kuo, Suzanne E. Mcgaugh, Anne M. Bronikowski, A.P. Jason De Konig, Scott V. Edwards, Michael E. Pfrender, Patrick Minx, Edmund D. Brodie Iii, Edmund D. Brodie Jr., Wesley C. Warren, Todd A. Castoe

Biological Sciences Faculty Research and Publications

Colubridae represents the most phenotypically diverse and speciose family of snakes, yet no well-assembled and annotated genome exists for this lineage. Here, we report and analyze the genome of the garter snake, Thamnophis sirtalis, a colubrid snake that is an important model species for research in evolutionary biology, physiology, genomics, behavior, and the evolution of toxin resistance. Using the garter snake genome, we show how snakes have evolved numerous adaptations for sensing and securing prey, and identify features of snake genome structure that provide insight into the evolution of amniote genomes. Analyses of the garter snake and other squamate …

Stress Promotes Drug Seeking Through Glucocorticoid-Dependent Endocannabinoid Mobilization In The Prelimbic Cortex, Jayme R. Mcreynolds, Elizabeth M. Doncheck, Yan Li, Oliver Vranjkovic, Evan N. Graf, Daisuke Ogasawara, Benjamin F. Cravatt, David A. Baker, Qing-Song Liu, Cecilia J. Hillard, John R. Mantsch

Biological Sciences Faculty Research and Publications

Background

Clinical reports suggest that rather than directly driving cocaine use, stress may create a biological context within which other triggers for drug use become more potent. We hypothesize that stress-induced increases in corticosterone “set the stage” for relapse by promoting endocannabinoid-induced attenuation of inhibitory transmission in the prelimbic cortex (PL).

Methods

We have established a rat model for these stage-setting effects of stress. In this model, neither a stressor (electric footshock) nor stress-level corticosterone treatment alone reinstates cocaine seeking following self-administration and extinction, but each treatment potentiates reinstatement in response to an otherwise subthreshold cocaine priming dose (2.5 mg/kg, …

Xx/Xy Sex Chromosomes In The South American Dwarf Gecko (Gonatodes Humeralis), Tony Gamble, Erin Mckenna, Wyatt Meyer, Stuart V. Nielsen, Brendan J. Pinto, Daniel P. Scantlebury, Timothy E. Higham

Biological Sciences Faculty Research and Publications

Sex-specific genetic markers identified using restriction site-associated DNA sequencing, or RADseq, permits the recognition of a species’ sex chromosome system in cases where standard cytogenetic methods fail. Thus, species with male-specific RAD markers have an XX/XY sex chromosome system (male heterogamety) while species with female-specific RAD markers have a ZZ/ZW sex chromosome (female heterogamety). Here, we use RADseq data from 5 male and 5 female South American dwarf geckos (Gonatodes humeralis) to identify an XX/XY sex chromosome system. This is the first confidently known sex chromosome system in a Gonatodes species. We used a low-coverage de novo G. …

Response To Comment On “Plant Diversity Increases With The Strength Of Negative Density Dependence At The Global Scale”, Joseph A. Lamanna, Scott A. Mangan, Alfonso Alonso, Norman A. Bourg, Warren Y. Brockelman, Sarayudh Bunyavejchewin, Li-Wan Chang, Iyh-Min Chiang, George B. Chuyong, Keith Clay, Susan Cordell, Stuart J. Davies, Tucker J. Furniss, Christian P. Giardina, I. A.U. Nimal Gunatilleke, C. V. Savitri Gunatilleke, Fangliang He, Robert W. Howe, Stephen P. Hubbell, Chang-Fu Hsieh, Faith M. Inman-Narahari, David Janik, Daniel J. Johnson, David Kenfack, Lisa Korte, Kamil Král, Andrew J. Larson, James A. Lutz, Sean M. Mcmahon, William J. Mcshea, Hervé R. Memiaghe, Anuttara Nathalang, Vojtech Novotny, Perry S. Ong, David A. Orwig, Rebecca Ostertag, Geoffrey G. Parker, Richard P. Phillips, Lawren Sack, I-Fang Sun, J. Sebastián Tello, Duncan W. Thomas, Benjamin L. Turner, Dilys M. Vela Díaz, Tomáš Vrška, George D. Weiblen, Amy Wolf, Sandra Yap, Jonathan A. Myers

Biological Sciences Faculty Research and Publications

Hülsmann and Hartig suggest that ecological mechanisms other than specialized natural enemies or intraspecific competition contribute to our estimates of conspecific negative density dependence (CNDD). To address their concern, we show that our results are not the result of a methodological artifact and present a null-model analysis that demonstrates that our original findings—(i) stronger CNDD at tropical relative to temperate latitudes and (ii) a latitudinal shift in the relationship between CNDD and species abundance—persist even after controlling for other processes that might influence spatial relationships between adults and recruits.

Integrating Species Traits Into Species Pools, Marko J. Spasojevic, Christopher P. Catano, Joseph A. Lamanna, Jonathan A. Myers

Biological Sciences Faculty Research and Publications

Despite decades of research on the species‐pool concept and the recent explosion of interest in trait‐based frameworks in ecology and biogeography, surprisingly little is known about how spatial and temporal changes in species‐pool functional diversity (SPFD) influence biodiversity and the processes underlying community assembly. Current trait‐based frameworks focus primarily on community assembly from a static regional species pool, without considering how spatial or temporal variation in SPFD alters the relative importance of deterministic and stochastic assembly processes. Likewise, species‐pool concepts primarily focus on how the number of species in the species pool influences local biodiversity. However, species pools with similar …

A High-Throughput Screening Assay For Pyruvate Carboxylase, Brittney N. Wyatt, Leggy A. Arnold, Martin St. Maurice

Biological Sciences Faculty Research and Publications

Pyruvate carboxylase (PC) catalyzes the conversion of pyruvate to oxaloacetate (OAA), an important metabolic reaction in a wide range of organisms. Small molecules directed against PC would enable detailed studies on the metabolic role of this enzyme and would have the potential to be developed into pharmacological agents. Currently, specific and potentsmall molecule regulators of PC are unavailable. To assist in efforts to find, develop, and characterize small molecule effectors of PC, a novel fixed-time assay has been developed based on the reaction of OAA with the diazonium salt, Fast Violet B (FVB), which produces a colored adduct with …

Terrestrial Laser Scanning To Detect Liana Impact On Forest Structure, Sruthi M. Krishna Moorthy, Kim Calders, Manfredo Di Porcia E Brugnera, Hans Verbeeck, Stefan A. Schnitzer

Biological Sciences Faculty Research and Publications

Tropical forests are currently experiencing large-scale structural changes, including an increase in liana abundance and biomass. Higher liana abundance results in reduced tree growth and increased tree mortality, possibly playing an important role in the global carbon cycle. Despite the large amount of data currently available on lianas, there are not many quantitative studies on the influence of lianas on the vertical structure of the forest. We study the potential of terrestrial laser scanning (TLS) in detecting and quantifying changes in forest structure after liana cutting using a small scale removal experiment in two plots (removal plot and non-manipulated control …

Swimming Rhythm Generation In The Caudal Hindbrain Of The Lamprey, James T. Buchanan

Biological Sciences Faculty Research and Publications

The spinal cord has been well established as the site of generation of the locomotor rhythm in vertebrates, but studies have suggested that the caudal hindbrain in larval fish and amphibians can also generate locomotor rhythms. Here, we investigated whether the caudal hindbrain of the adult lamprey (Petromyzon marinus and Ichthyomyzon unicuspis) has the ability to generate the swimming rhythm. The hindbrain-spinal cord transition zone of the lamprey contains a bilateral column of somatic motoneurons that project via the spino-occipital (S-O) nerves to several muscles of the head. In the brainstem-spinal cord-muscle preparation, these muscles were found to …

Dynamic Sex Chromosomes In Old World Chameleons (Squamata: Chamaeleonidae), Stuart V. Nielsen, J. L. Banks, R. E. Diaz Jr., P. A. Trainor, Tony Gamble

Biological Sciences Faculty Research and Publications

Much of our current state of knowledge concerning sex chromosome evolution is based on a handful of ‘exceptional’ taxa with heteromorphic sex chromosomes. However, classifying the sex chromosome systems of additional species lacking easily identifiable, heteromorphic sex chromosomes is indispensable if we wish to fully understand the genesis, degeneration and turnover of vertebrate sex chromosomes. Squamate reptiles (lizards and snakes) are a potential model clade for studying sex chromosome evolution as they exhibit a suite of sex‐determining modes yet most species lack heteromorphic sex chromosomes. Only three (of 203) chameleon species have identified sex chromosome systems (all with female heterogamety, …

Dynamics Of E. Coli Single Stranded Dna Binding (Ssb) Protein-Dna Complexes, Edwin Antony, Timothy M. Lohman

Biological Sciences Faculty Research and Publications

Single stranded DNA binding proteins (SSB) are essential to the cell as they stabilize transiently open single stranded DNA (ssDNA) intermediates, recruit appropriate DNA metabolism proteins, and coordinate fundamental processes such as replication, repair and recombination. Escherichia coli single stranded DNA binding protein (EcSSB) has long served as the prototype for the study of SSB function. The structure, functions, and DNA binding properties of EcSSB are well established: The protein is a stable homotetramer with each subunit possessing an N-terminal DNA binding core, a C-terminal protein-protein interaction tail, and an intervening intrinsically disordered linker (IDL). EcSSB …

Tree Species Vary Widely In Their Tolerance For Liana Infestation: A Case Study Of Differential Host Response To Generalist Parasites, Marco D. Visser, Stefan A. Schnitzer, Helene C. Muller-Laudau, Eelke Jongejans, Hans De Kroon, Liza S. Comita, Stephen P. Hubbell, S. Joseph Wright

Biological Sciences Faculty Research and Publications

1. Lianas are structural parasites of trees and reduce individual host tree growth, survival and fecundity. Thus, liana infestation is expected to affect tree population growth rates, with potentially different effects in different species depending on the frequency of liana infestation and the impact of liana infestation on population growth rates. Previous studies have documented the myriad negative effects of lianas on trees and variation in liana infestation among tree species; however, no study has quantified the impact of liana infestation on individual tree species population growth rates. Lianas are increasing in abundance in multiple Neotropical sites, which may have profound …

Does Soil Moisture Availability Explain Liana Seedling Distribution Across A Tropical Rainfall Gradient?, Eric Manzane-Pinzon, Guillermo Goldstein, Stefan A. Schnitzer

Biological Sciences Faculty Research and Publications

Liana density tends to increase with decreasing rainfall and increasing seasonality. However, the pattern of liana distribution may be due to differences in soil water retention capacity, not rainfall and seasonality per se. We tested the effect of rainfall and soil substrate with respect to the distribution of liana seedlings in six sites across a rainfall gradient from the wet Atlantic to the dry Pacific in central Panama. Soils were either limestone, with low water-holding capacity, or laterite, with higher water-holding capacity. We sampled liana seedlings at each site using three 1 × 100 m transect. We found that …

Lianas Reduce Community-Level Canopy Tree Reproduction In A Panamanian Forest, Maria M. Garcia Leon, Laura Martinez Izquierdo, Filipe Niery Arantes Mello, Jennifer S. Powers, Stefan A. Schnitzer

Biological Sciences Faculty Research and Publications

1. Lianas are a key component of tropical forests, where they compete intensely with trees, reducing tree recruitment, growth and survival. One of the most important potential outcomes of liana competition is the reduction of tree reproduction; however, no previous study has experimentally determined the effects of lianas on tree reproduction beyond a single tree species.
2. We used a large‐scale liana removal experiment to quantify the effect of lianas on community‐level canopy and understorey tree and palm reproduction. In 2011, we removed lianas from eight 6,400‐m² plots (eight plots served as controls) and surveyed understorey tree reproduction in 2012, canopy …