Life Sciences Commons^™

Phenotypic Correlates Of The Lianescent Growth Form: A Review, Tomasz P. Wyka, Jacek Oleksyn, Piotr Karolewski, Stefan A. Schnitzer

Biological Sciences Faculty Research and Publications

Background

As proposed by Darwin, climbers have been assumed to allocate a smaller fraction of biomass to support organs in comparison with self-supporting plants. They have also been hypothesized to possess a set of traits associated with fast growth, resource uptake and high productivity.

Scope

In this review, these hypotheses are evaluated by assembling and synthesizing published and unpublished data sets from across the globe concerning resource allocation, growth rates and traits of leaves, stems and roots of climbers and self-supporting species.

Conclusions

The majority of studies offer little support for the smaller allocation of biomass to stems or greater …

Facile Synthesis, Characterization, And Antimicrobial Activity Of Cellulose-Chitosan-Hydroxyapatite Composite Material: A Potential Material For Bone Tissue Engineering, Tamutsiwa M. Mututuvari, April Harkins, Chieu D. Tran

Clinical Lab Sciences Faculty Research and Publications

Hydroxyapatite (HAp) is often used as a bone-implant material because it is biocompatible and osteoconductive. However, HAp possesses poor rheological properties and it is inactive against disease-causing microbes. To improve these properties, we developed a green method to synthesize multifunctional composites containing: (1) cellulose (CEL) to impart mechanical strength; (2) chitosan (CS) to induce antibacterial activity thereby maintaining a microbe-free wound site; and (3) HAp. In this method, CS and CEL were co-dissolved in an ionic liquid (IL) and then regenerated from water. HAp was subsequently formed in situ by alternately soaking [CEL+CS] composites in aqueous solutions of CaCl_{2 …}

Multiple C-Terminal Tails Within A Single E. Coli Ssb Homotetramer Coordinate Dna Replication And Repair, Edwin Antony, Elizabeth Weiland, Quan Yuan, Carol M. Manhart, Binh Nguyen, Alexander G. Kozlov, Charles S. Mchenry, Timothy M. Lohman

Biological Sciences Faculty Research and Publications

Escherichia coli single-stranded DNA binding protein (SSB) plays essential roles in DNA replication, recombination and repair. SSB functions as a homotetramer with each subunit possessing a DNA binding domain (OB-fold) and an intrinsically disordered C-terminus, of which the last nine amino acids provide the site for interaction with at least a dozen other proteins that function in DNA metabolism. To examine how many C-termini are needed for SSB function, we engineered covalently linked forms of SSB that possess only one or two C-termini within a four-OB-fold “tetramer”. Whereas E. coli expressing SSB with only two tails can survive, expression …

Insights Into The Carboxyltransferase Reaction Of Pyruvate Carboxylase From The Structures Of Bound Product And Intermediate Analogs, Adam D. Lietzan, Martin St. Maurice

Biological Sciences Faculty Research and Publications

Pyruvate carboxylase (PC) is a biotin-dependent enzyme that catalyzes the MgATP- and bicarbonate-dependent carboxylation of pyruvate to oxaloacetate, an important anaplerotic reaction in central metabolism. The carboxyltransferase (CT) domain of PC catalyzes the transfer of a carboxyl group from carboxybiotin to the accepting substrate, pyruvate. It has been hypothesized that the reactive enolpyruvate intermediate is stabilized through a bidentate interaction with the metal ion in the CT domain active site. Whereas bidentate ligands are commonly observed in enzymes catalyzing reactions proceeding through an enolpyruvate intermediate, no bidentate interaction has yet been observed in the CT domain of PC. Here, we …

Liana Impacts On Carbon Cycling, Storage And Sequestration In Tropical Forests, Geertje M. Van Der Heijden, Stefan A. Schnitzer, Jennifer S. Powers, Oliver L. Phillips

Biological Sciences Faculty Research and Publications

Mature tropical forests sequester large quantities of atmospheric CO2, which they store as plant biomass. These forests are changing however, including an increase in liana abundance and biomass over recent decades in Neotropical forests. We ask here how this increase in lianas might impact the tropical forest carbon cycle and their capacity for carbon storage and sequestration. Lianas reduce tree growth, survival, and leaf productivity; however, lianas also invest significantly in leaf production, and the increase in lianas could conceivably offset liana‐induced reductions in tree canopy productivity with no adverse effects to the forest‐level canopy productivity. By contrast, lianas decrease …

Left–Right Dewlap Asymmetry And Phylogeography Of Anolis Lineatus On Aruba And Curaçao, Gabriel E.A. Gartner, Tony Gamble, Alexander L. Jaffe, Alexis Harrison, Jonathan B. Losos

Biological Sciences Faculty Research and Publications

Anolis lizards exhibit a remarkable degree of diversity in the shape, colour, pattern and size of their dewlaps. Asymmetry, where one side of the dewlap differs in pattern or colour from the other, has only been reported in one species, Anolis lineatus, and then on only one of the two islands from which it occurs. Given the importance of the dewlap in intra- and interspecific signalling, we expanded on previous work by (1) investigating whether the reported asymmetry actually occurs and, if so, whether it occurs on animals from both Aruba and Curaçao; (2) examining whether populations differ in …

Temporal And Spatial Requirements Of Drop-Dead Expression For Adult Survival In Drosophila Melanogaster, Christine Lynn Sansone

Dissertations (1934 -)

Mutations in the gene drop-dead (drd) cause diverse phenotypes in adult Drosophila melanogaster including early lethality, neurodegeneration, fragile tracheae, gut dysfunction, reduced body mass, and female sterility. The cause of early lethality and the function of the drd protein remain unknown. To elucidate a molecular function of DRD, the temporal and spatial requirements of the drd gene for survival were determined. drd expression was manipulated with the Gal4-UAS system, using UAS-RNAi transgenes and a UAS-drd transgene on a drd mutant background to knock down and rescue expression of drd, respectively.

To investigate the temporal requirements of drd expression for adult …

The Role Of Amp-Activated Protein Kinase In Mouse Oocyte Maturation And Subsequent Egg Activation, Ru Ya

Dissertations (1934 -)

Mammalian oogenesis begins during fetal development. Oocytes enter meiosis and arrest at prophase I before birth. Meiosis resumes after proper hormonal signaling, the oocyte completes meiosis I, and then ovulates in metaphase II, at which stage it arrests until fertilization occurs. Egg activation occurs upon sperm fertilization, which includes various physiological processes including calcium influx, release of cortical granules, and completion of meiosis II. However, egg activation can also occur without fertilization, which compromises the later embryonic development. The developmental period from prophase I to metaphase II is referred as oocyte maturation, and involves crucial dynamic change of the cytoskeleton …

Tonic And Phasic Smooth Muscle Contraction Is Not Regulated By The Pkcα - Cpi-17 Pathway In Swine Stomach Antrum And Fundus, Yu Zhang, Meghan E. Hermanson, Thomas J. Eddinger

Biological Sciences Faculty Research and Publications

Regulation of myosin light chain phosphatase (MLCP) via protein kinase C (PKC) and the 17 kDa PKC-potentiated inhibitor of myosin light chain phosphatase (CPI-17) has been reported as a Ca²⁺ sensitization signaling pathway in smooth muscle (SM), and thus may be involved in tonic vs. phasic contractions. This study examined the protein expression and spatial-temporal distribution of PKCα and CPI-17 in intact SM tissues. KCl or carbachol (CCh) stimulation of tonic stomach fundus SM generates a sustained contraction while the phasic stomach antrum generates a transient contraction. In addition, the tonic fundus generates greater relative force than phasic antrum …

A Requirement For Fatty Acid Oxidation In The Hormone-Induced Meiotic Maturation Of Mouse Oocytes, Deepa Valsangkar, Stephen Downs

Biological Sciences Faculty Research and Publications

We have previously shown that fatty acid oxidation (FAO) is required for AMP-activated protein kinase (PRKA)-induced maturation in vitro. In the present study, we have further investigated the role of this metabolic pathway in hormone-induced meiotic maturation. Incorporating an assay with ³H-palmitic acid as the substrate, we first examined the effect of PRKA activators on FAO levels. There was a significant stimulation of FAO in cumulus cell-enclosed oocytes (CEO) treated with 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) and RSVA405. In denuded oocytes (DO), AICAR stimulated FAO only in the presence of carnitine, the molecule that facilitates fatty acyl CoA entry into the …

Srs2 Prevents Rad51 Filament Formation By Repetitive Motion On Dna, Yupeng Qiu, Edwin Antony, Sultan Doganay, Hye Ran Koh, Timothy M. Lohman, Sua Myong

Biological Sciences Faculty Research and Publications

Srs2 dismantles presynaptic Rad51 filaments and prevents its re-formation as an anti-recombinase. However, the molecular mechanism by which Srs2 accomplishes these tasks remains unclear. Here we report a single-molecule fluorescence study of the dynamics of Rad51 filament formation and its disruption by Srs2. Rad51 forms filaments on single-stranded DNA by sequential binding of primarily monomers and dimers in a 5′–3′ direction. One Rad51 molecule binds to three nucleotides, and six monomers are required to achieve a stable nucleation cluster. Srs2 exhibits ATP-dependent repetitive motion on single-stranded DNA and this activity prevents re-formation of the Rad51 filament. The same activity of …

Are Lianas More Drought-Tolerant Than Trees? A Test For The Role Of Hydraulic Architecture And Other Stem And Leaf Traits, Masha T. Van Der Sande, Lourens Poorter, Stefan A. Schnitzer, Lars Markesteijn

Biological Sciences Faculty Research and Publications

Lianas are an important component of Neotropical forests, where evidence suggests that they are increasing in abundance and biomass. Lianas are especially abundant in seasonally dry tropical forests, and as such it has been hypothesized that they are better adapted to drought, or that they are at an advantage under the higher light conditions in these forests. However, the physiological and morphological characteristics that allow lianas to capitalize more on seasonal forest conditions compared to trees are poorly understood. Here, we evaluate how saplings of 21 tree and liana species from a seasonal tropical forest in Panama differ in cavitation …

A Substrate-Induced Biotin Binding Pocket In The Carboxyltransferase Domain Of Pyruvate Carboxylase, Adam D. Lietzan, Martin St. Maurice

Biological Sciences Faculty Research and Publications

Biotin-dependent enzymes catalyze carboxyl transfer reactions by efficiently coordinating multiple reactions between spatially distinct active sites. Pyruvate carboxylase (PC), a multifunctional biotin-dependent enzyme, catalyzes the bicarbonate- and MgATP-dependent carboxylation of pyruvate to oxaloacetate, an important anaplerotic reaction in mammalian tissues. To complete the overall reaction, the tethered biotin prosthetic group must first gain access to the biotin carboxylase domain and become carboxylated and then translocate to the carboxyltransferase domain, where the carboxyl group is transferred from biotin to pyruvate. Here, we report structural and kinetic evidence for the formation of a substrate-induced biotin binding pocket in the carboxyltransferase domain of …

Nonspecific, Reversible Inhibition Of Voltage-Gated Calcium Channels By Camkii Inhibitor Ck59, Andrew S. Kahrls, Michelle Mynlieff

Biological Sciences Faculty Research and Publications

Investigation of kinase-related processes often uses pharmacological inhibition to reveal pathways in which kinases are involved. However, one concern about using such kinase inhibitors is their potential lack of specificity. Here, we report that the calcium–calmodulin-dependent kinase II (CaMKII) inhibitor CK59 inhibited multiple voltage-gated calcium channels, including the L-type channel during depolarization in a dose-dependent manner. The use of another CaMKII inhibitor, cell-permeable autocamtide-2 related inhibitory peptide II (Ant-AIP-II), failed to similarly decrease calcium current or entry in hippocampal cultures, as shown by ratiometric calcium imaging and whole-cell patch clamp electrophysiology. Notably, inhibition due to CK59 was reversible; washout of …

Neurodegeneration In Drop-Dead Mutant Drosophila Melanogaster Is Associated With The Respiratory System But Not With Hypoxia, Christine Lynn Sansone, Edward M. Blumenthal

Biological Sciences Faculty Research and Publications

Mutations in the gene drop-dead (drd) cause diverse phenotypes in adult Drosophila melanogaster including early lethality, neurodegeneration, tracheal defects, gut dysfunction, reduced body mass, and female sterility. Despite the identification of the drd gene itself, the causes of early lethality and neurodegeneration in the mutant flies remain unknown. To determine the pattern of drd expression associated with the neurodegenerative phenotype, knockdown of drd with various Gal4 drivers was performed. Early adult lethality and neurodegeneration were observed upon knockdown of drd in the tracheal system with two independent insertions of the breathless-Gal4 driver and upon knockdown in the tracheal …

Roles Of Predicted Glycosyltransferases In The Biosynthesis Of The Rhizobium Etli Ce3 O Antigen, Kristylea J. Ojeda, Laurie Simonds, K. Dale Noel

Biological Sciences Faculty Research and Publications

The Rhizobium etli CE3 O antigen is a fixed-length heteropolymer. The genetic regions required for its synthesis have been identified, and the nucleotide sequences are known. The structure of the O antigen has been determined, but the roles of specific genes in synthesizing this structure are relatively unclear. Within the known O-antigen genetic clusters of this strain, nine open reading frames (ORFs) were found to contain a conserved glycosyltransferase domain. Each ORF was mutated, and the resulting mutant lipopolysaccharide (LPS) was analyzed. Tricine SDS-PAGE revealed stepwise truncations of the O antigen that were consistent with differences in mutant LPS sugar …

Inhibition Of Diuretic Stimulation Of An Insect Secretory Epithelium By A Cgmp-Dependent Protein Kinase, Kristen A. Ruka, Anna P. Miller, Edward M. Blumenthal

Biological Sciences Faculty Research and Publications

The rate of urine secretion by insect Malpighian tubules (MTs) is regulated by multiple diuretic and antidiuretic hormones, often working either synergistically or antagonistically. In the Drosophila melanogaster MT, only diuretic factors have been reported. Two such agents are the biogenic amine tyramine (TA) and the peptide drosokinin (DK), both of which act on the stellate cells of the tubule to increase transepithelial chloride conductance. In the current study, TA and DK signaling was quantified by microelectrode recording of the transepithelial potential in isolated Drosophila MTs. Treatment of tubules with cGMP caused a significant reduction in the depolarizing responses to …

Antifreeze Proteins In The Primary Urine Of Larvae Of The Beetle Dendroides Canadensis, Philip K. Nickell, Sandra Sass, Dawn Verleye, Edward M. Blumenthal, John G. Duman

Biological Sciences Faculty Research and Publications

To avoid freezing while overwintering beneath the bark of fallen trees, Dendroides canadensis (Coleoptera: Pyrochroidae) larvae produce a family of antifreeze proteins (DAFPs) that are transcribed in specific tissues and have specific compartmental fates. DAFPs and associated thermal hysteresis activity (THA) have been shown previously in hemolymph and midgut fluid, but the presence of DAFPs has not been explored in primary urine, a potentially important site that can contain endogenous ice-nucleating compounds that could induce freezing. A maximum mean THA of 2.65±0.33°C was observed in primary urine of winter-collected D. canadensis larvae. THA in primary urine increased significantly through autumn, …

Increasing Liana Abundance And Basal Area In A Tropical Forest: The Contribution Of Long‐Distance Clonal Colonization, Suzanne R. Yorke, Stefan A. Schnitzer, Joseph Mascaro, Susan G. Letcher, Walter P. Carson

Biological Sciences Faculty Research and Publications

Recent evidence suggests that liana abundance and biomass are increasing in Neotropical forests, representing a major structural change to tropical ecosystems. Explanations for these increases, however, remain largely untested. Over an 8‐yr period (1999–2007), we censused lianas in nine, 24 × 36 m permanent plots in old‐growth and selectively logged forest at La Selva Biological Station, Costa Rica to test whether: (1) liana abundance and basal area are increasing in this forest; (2) the increase is being driven by increased recruitment, decreased mortality, or both; and (3) long‐distance clonal colonization explains the increase in liana abundance and basal area. We …

Selenium Biotransformations In An Engineered Aquatic Ecosystem For Bioremediation Of Agricultural Wastewater Via Brine Shrimp Production, Radomir Schmidt, Prapakorn Tantoyotai, Sirine C. Fakra, Matthew A. Marcus, Soo In Yang, Ingrid J. Pickering, Gary S. BañUelos, Krassimira R. Hristova, John L. Freeman

Biological Sciences Faculty Research and Publications

An engineered aquatic ecosystem was specifically designed to bioremediate selenium (Se), occurring as oxidized inorganic selenate from hypersalinized agricultural drainage water while producing brine shrimp enriched in organic Se and omega-3 and omega-6 fatty acids for use in value added nutraceutical food supplements. Selenate was successfully bioremediated by microalgal metabolism into organic Se (seleno-amino acids) and partially removed via gaseous volatile Se formation. Furthermore, filterfeeding brine shrimp that accumulated this organic Se were removed by net harvest. Thriving in this engineered pond system, brine shrimp (Artemia franciscana Kellogg) and brine fly (Ephydridae sp.) have major ecological relevance as important food …

Confocal Imaging Of Transmembrane Voltage By Seer Of Di-8-Anepps, Carlo Manno, Lourdes Figueroa, Robert Fitts, Eduardo Rios

Biological Sciences Faculty Research and Publications

Imaging, optical mapping, and optical multisite recording of transmembrane potential (V_m) are essential for studying excitable cells and systems. The naphthylstyryl voltage-sensitive dyes, including di-8-ANEPPS, shift both their fluorescence excitation and emission spectra upon changes in V_m. Accordingly, they have been used for monitoring V_m in nonratioing and both emission and excitation ratioing modes. Their changes in fluorescence are usually much less than 10% per 100 mV. Conventional ratioing increases sensitivity to between 3 and 15% per 100 mV. Low sensitivity limits the value of these dyes, especially when imaged with low light systems …

Cns Control Of Glucose Metabolism: Response To Environmental Challenges, Deanna M. Arble, Darleen A. Sandoval

Biological Sciences Faculty Research and Publications

Over the last 15 years, considerable work has accumulated to support the role of the CNS in regulating postprandial glucose levels. As discussed in the first section of this review, the CNS receives and integrates information from afferent neurons, circulating hormones, and postprandially generated nutrients to subsequently direct changes in glucose output by the liver and glucose uptake by peripheral tissues. The second major component of this review focuses on the effects of external pressures, including high fat diet and changes to the light:dark cycle on CNS-regulating glucose homeostasis. We also discuss the interaction between these different pressures and how …

Complex Facilitation And Competition In A Temperate Grassland: Loss Of Plant Diversity And Elevated Co2 Have Divergent And Opposite Effects On Oak Establishment, Alexandra Wright, Stefan A. Schnitzer, Ian A. Dickie, Alex R. Gunderson, Gavriella A. Pinter, Scott A. Mangan, Peter B. Reich

Biological Sciences Faculty Research and Publications

Encroachment of woody vegetation into grasslands is a widespread phenomenon that alters plant community composition and ecosystem function. Woody encroachment is often the result of fire suppression, but it may also be related to changes in resource availability associated with global environmental change. We tested the relative strength of three important global change factors (CO₂ enrichment, nitrogen deposition, and loss of herbaceous plant diversity) on the first 3 years of bur oak (Quercus macrocarpa) seedling performance in a field experiment in central Minnesota, USA. We found that loss of plant diversity decreased initial oak survival but increased …

Synthetic Lethality Of Chk1 Inhibition Combined With P53 And/Or P21 Loss During A Dna Damage Response In Normal And Tumor Cells, Sofia Origanti, Shi-Rong Cai, A. Z. Munir, Lynn S. White, Helen Piwnica-Worms

Biological Sciences Faculty Research and Publications

Cell cycle checkpoints ensure genome integrity and are frequently compromised in human cancers. A therapeutic strategy being explored takes advantage of checkpoint defects in p53-deficient tumors in order to sensitize them to DNA-damaging agents by eliminating Chk1-mediated checkpoint responses. Using mouse models, we demonstrated that p21 is a key determinant of how cells respond to the combination of DNA damage and Chk1 inhibition (combination therapy) in normal cells as well as in tumors. Loss of p21 sensitized normal cells to the combination therapy much more than did p53 loss and the enhanced lethality was partially blocked by CDK inhibition. In …

Exogenous Delivery Of Chaperonin Subunit Fragment Apicct1 Modulates Mutant Huntingtin Cellular Phenotypes, Emily M. Sontag, Lukasz A. Joachimiak, Zhiqun Tan, Anthony Tomlinson, David E. Housman, Charles G. Glabe, Steven G. Potkin, Judith Frydman, Leslie M. Thompson

Biological Sciences Faculty Research and Publications

Aggregation of misfolded proteins is characteristic of a number of neurodegenerative diseases, including Huntington disease (HD). The CCT/TRiC (chaperonin containing TCP-1/TCP-1 ring) chaperonin complex can inhibit aggregation and cellular toxicity induced by expanded repeat Huntingtin (mHtt) fragments. The substrate-binding apical domain of CCT/TRiC subunit CCT1, ApiCCT1, is sufficient to inhibit aggregation of expanded repeat mHtt fragments in vitro, providing therapeutic promise for HD. However, a key hurdle in considering ApiCCT1 as a potential treatment is in delivery. Because ApiCCT1 has a region of similarity to the HIV Tat protein cell-transduction domain, we tested whether recombinant ApiCCT1 (ApiCCT1r) protein could enter …

A Transgenic Minipig Model Of Huntington's Disease, Monika Baxa, Marian Hruska-Plochan, Stefan Juhas, Petr Vodicka, Antonin Pavlok, Jana Juhasova, Atsushi Miyanohara, Tetsuya Nejime, Jiri Klima, Monika Macakova, Silvia Marsala, Andreas Weiss, Svatava Kubickova, Petra Musilova, Radek Vrtel, Emily M. Sontag, Leslie Thompson, Jan Schier, Hana Hansikova, David S. Howland, Elena Cattaneo, Marian Difiglia, Martin Marsala, Jan Motlik

Biological Sciences Faculty Research and Publications

Background: Some promising treatments for Huntington's disease (HD) may require pre-clinical testing in large animals. Minipig is a suitable species because of its large gyrencephalic brain and long lifespan. Objective: To generate HD transgenic (TgHD) minipigs encoding huntingtin (HTT)1–548 under the control of human HTT promoter. Methods: Transgenesis was achieved by lentiviral infection of porcine embryos. PCR assessment of gene transfer, observations of behavior, and postmortem biochemical and immunohistochemical studies were conducted. Results: One copy of the human HTT transgene encoding 124 glutamines integrated into chromosome 1 q24-q25 and successful germ line transmission occurred through successive generations (F0, F1, F2 …

The Conservation Status Of The World’S Reptiles, Tony Gamble

Biological Sciences Faculty Research and Publications

Effective and targeted conservation action requires detailed information about species, their distribution, systematics and ecology as well as the distribution of threat processes which affect them. Knowledge of reptilian diversity remains surprisingly disparate, and innovative means of gaining rapid insight into the status of reptiles are needed in order to highlight urgent conservation cases and inform environmental policy with appropriate biodiversity information in a timely manner. We present the first ever global analysis of extinction risk in reptiles, based on a random representative sample of 1500 species (16% of all currently known species). To our knowledge, our results provide the …

Suppression Of Chemically Induced And Spontaneous Mouse Oocyte Activation By Amp-Activated Protein Kinase, Ru Ya, Stephen Downs

Biological Sciences Faculty Research and Publications

Oocyte activation is an important process triggered by fertilization that initiates embryonic development. However, parthenogenetic activation can occur either spontaneously or with chemical treatments. The LT/Sv mouse strain is genetically predisposed to spontaneous activation. LT oocytes have a cell cycle defect and are ovulated at the metaphase I stage instead of metaphase II. A thorough understanding of the female meiosis defects in this strain remains elusive. We have reported that AMP-activated protein kinase (PRKA) has an important role in stimulating meiotic resumption and promoting completion of meiosis I while suppressing premature parthenogenetic activation. Here we show that early activation of …