Life Sciences Commons^™

Flexibility In The Patterning And Control Of Axial Locomotor Networks In Lamprey, James T. Buchanan

Biological Sciences Faculty Research and Publications

In lower vertebrates, locomotor burst generators for axial muscles generally produce unitary bursts that alternate between the two sides of the body. In lamprey, a lower vertebrate, locomotor activity in the axial ventral roots of the isolated spinal cord can exhibit flexibility in the timings of bursts to dorsally-located myotomal muscle fibers versus ventrally-located myotomal muscle fibers. These episodes of decreased synchrony can occur spontaneously, especially in the rostral spinal cord where the propagating body waves of swimming originate. Application of serotonin, an endogenous spinal neurotransmitter known to presynaptically inhibit excitatory synapses in lamprey, can promote decreased synchrony of dorsal–ventral …

A New Genus Of Miniaturized And Pug-Nosed Gecko From South America (Sphaerodactylidae: Gekkota), Tony Gamble, Juan D. Daza, Guarino R. Colli, Laurie J. Vitt, Aaron M. Bauer

Biological Sciences Faculty Research and Publications

Sphaerodactyl geckos comprise five genera distributed across Central and South America and the Caribbean. We estimated phylogenetic relationships among sphaerodactyl genera using both separate and combined analyses of seven nuclear genes. Relationships among genera were incongruent at different loci and phylogenies were characterized by short, in some cases zero-length, internal branches and poor phylogenetic support at most nodes. We recovered a polyphyletic Coleodactylus, with Coleodactylus amazonicus being deeply divergent from the remaining Coleodactylus species sampled. The C. amazonicus lineage possessed unique codon deletions in the genes PTPN₁₂ and RBMX while the remaining Coleodactylus species had unique codon …

Identifying Polyglutamine Protein Species In Situ That Best Predict Neurodegeneration, Jason Miller, Montserrat Arrasate, Elizabeth Brooks, Clare Peter Libeu, Justin Legleiter, Danny Hatters, Jessica Curtis, Kenneth Cheung, Preethi Krishnan, Siddhartha Mitra, Kartika Widjaja, Benjamin A. Shaby, Gregor P. Lotz, Yvonne Newhouse, Emily M. Sontag, Alex Osmand, Michelle Gray, Vanitha Thulasiramin, Frederic Saudou, Mark Segal, X William Yang, Eliezer Masliah, Leslie M. Thompson, Paul J. Muchowski, Karl H. Weisgraber, Steven Finkbeiner

Biological Sciences Faculty Research and Publications

Polyglutamine (polyQ) stretches exceeding a threshold length confer a toxic function to proteins that contain them and cause at least nine neurological disorders. The basis for this toxicity threshold is unclear. Although polyQ expansions render proteins prone to aggregate into inclusion bodies, this may be a neuronal coping response to more toxic forms of polyQ. The exact structure of these more toxic forms is unknown. Here we show that the monoclonal antibody 3B5H10 recognizes a species of polyQ protein in situ that strongly predicts neuronal death. The epitope selectively appears among some of the many low-molecular-weight conformational states assumed by …

Spinal Locomotor Inputs To Individually Identified Reticulospinal Neurons In The Lamprey, James T. Buchanan

Biological Sciences Faculty Research and Publications

Locomotor feedback signals from the spinal cord to descending brain stem neurons were examined in the lamprey using the uniquely identifiable reticulospinal neurons, the Müller and Mauthner cells. The same identified reticulospinal neurons were recorded in several preparations, under reduced conditions, to address whether an identified reticulospinal neuron shows similar locomotor-related oscillation timing from animal to animal and whether these timing signals can differ significantly from other identified reticulospinal neurons. Intracellular recordings of membrane potential in identified neurons were made in an isolated brain stem-spinal cord preparation with a high-divalent cation solution on the brain stem to suppress indirect neural …

Minimizing Bias In Biomass Allometry: Model Selection And Log‐Transformation Of Data, Joseph Mascaro, Creighton M. Litton, R. Flint Hughes, Amanda Uowolo, Stefan A. Schnitzer

Biological Sciences Faculty Research and Publications

Nonlinear regression is increasingly used to develop allometric equations for forest biomass estimation (i.e., as opposed to the traditional approach of log‐transformation followed by linear regression). Most statistical software packages, however, assume additive errors by default, violating a key assumption of allometric theory and possibly producing spurious models. Here, we show that such models may bias stand‐level biomass estimates by up to 100 percent in young forests, and we present an alternative nonlinear fitting approach that conforms with allometric theory.

Mouse Versus Rat: Profound Differences In Meiotic Regulation At The Level Of The Isolated Oocyte, Stephen Downs

Biological Sciences Faculty Research and Publications

Cumulus cell-enclosed oocytes (CEO), denuded oocytes (DO), or dissected follicles were obtained 44–48 hr after priming immature mice (20–23 days old) with 5 IU or immature rats (25–27 days old) with 12.5 IU of equine chorionic gonadotropin, and exposed to a variety of culture conditions. Mouse oocytes were more effectively maintained in meiotic arrest by hypoxanthine, dbcAMP, IBMX, milrinone, and 8-Br-cGMP. Atrial natriuretic peptide, a guanylate cyclase activator, suppressed maturation in CEO from both species, but mycophenolic acid reversed IBMX-maintained meiotic arrest in mouse CEO with little activity in rat CEO. IBMX-arrested mouse, but not rat, CEO were induced to …

A Tight Coupling Between Β2Y97 And Β2F200 Of The GabaA Receptor Mediates Gaba Binding, Phu N. Tran, Kurt T. Laha, David A. Wagner

Biological Sciences Faculty Research and Publications

The GABA_A receptor is an oligopentameric chloride channel that is activated via conformation changes induced upon the binding of the endogenous ligand, GABA, to the extracellular inter-subunit interfaces. Although dozens of amino acid residues at the α/β interface have been implicated in ligand binding, the structural elements that mediate ligand binding and receptor activation are not yet fully described. In this study, double-mutant cycle analysis was employed to test for possible interactions between several arginines (α₁R67, α₁R120, α₁R132, and β₂R207) and two aromatic residues (β₂Y97 and β₂F200) …

Rhythmic Leptin Is Required For Weight Gain From Circadian Desynchronized Feeding In The Mouse, Deanna M. Arble, Martha H. Vitaterna, Fred W. Turek

Biological Sciences Faculty Research and Publications

The neuroendocrine and metabolic effects of leptin have been extensively researched since the discovery, and the later identification, of the leptin gene mutated within the ob/ob mouse. Leptin is required for optimal health in a number of physiological systems (e.g. fertility, bone density, body weight regulation). Despite the extensive leptin literature and many observations of leptin’s cyclical pattern over the 24-hour day, few studies have specifically examined how the circadian rhythm of leptin may be essential to leptin signaling and health. Here we present data indicating that a rhythmic leptin profile (e.g. 1 peak every 24 hours) leads to excessive …

Uncovering New Functions For Micrornas In Caenorhabditis Elegans, Allison L. Abbott

Biological Sciences Faculty Research and Publications

In the race to understand microRNA (miRNA) functions in development and physiology, Caenorhabditis elegans investigators were the first out of the gate with the cloning and analysis of the lin-4 and let-7 miRNAs [1,2]. The starting point of strong, penetrant loss of function phenotypes facilitated these advancements. However, subsequent functional analysis of miRNAs in C. elegans was hampered by the lack of easily observable loss-of-function phenotypes [3]. There are several possible models to account for this observation. First, redundancy between related miRNAs can account for the absence of phenotypes in mutants missing individual miRNA genes [4,5]. Second, miRNAs may also …

Influence Of Earli1‐Like Genes On Flowering Time And Lignin Synthesis Of Arabidopsis Thaliana, Y. Shi, X. Zhang, Z.-Y. Xu, C. Zhang, Michael Schläppi, Z.-Q. Xu

Biological Sciences Faculty Research and Publications

EARLI1 encodes a 14.7 kDa protein in the cell wall, is a member of the PRP (proline‐rich protein) family and has multiple functions, including resistance to low temperature and fungal infection. RNA gel blot analyses in the present work indicated that expression of EARLI1‐like genes, EARLI1, At4G12470 and At4G12490, was down‐regulated in Col‐FRI‐Sf2 RNAi plants derived from transformation with Agrobacteriumstrain ABI, which contains a construct encoding a double‐strand RNA targeting 8CM of EARLI1. Phenotype analyses revealed that Col‐FRI‐Sf2 RNAi plants of EARLI1 flowered earlier than Col‐FRI‐Sf2 wild‐type plants. The average …

Truncation Of The Mrp20 Protein Reveals New Ribosome‐Assembly Subcomplex In Mitochondria, Jasvinder Kaur, Rosemary A. Stuart

Biological Sciences Faculty Research and Publications

Mitochondrial ribosomal protein 20 (Mrp20) is a component of the yeast mitochondrial large (54S) ribosomal subunit and is homologous to the bacterial L23 protein, located at the ribosomal tunnel exit site. The carboxy‐terminal mitochondrial‐specific domain of Mrp20 was found to have a crucial role in the assembly of the ribosomes. A new, membrane‐bound, ribosomal‐assembly subcomplex composed of known tunnel‐exit‐site proteins, an uncharacterized ribosomal protein, MrpL25, and the mitochondrial peroxiredoxin (Prx), Prx1, accumulates in an mrp20ΔC yeast mutant. Finally, data supporting the idea that the inner mitochondrial membrane acts as a platform for the ribosome assembly process are discussed.

Self-Assembly Of Escherichia Coli Mutl And Its Complexes With Dna, Anita Niedziela-Majka, Nasib K. Maluf, Edwin Antony, Timothy M. Lohman

Biological Sciences Faculty Research and Publications

The Escherichia coli MutL protein regulates the activity of several enzymes, including MutS, MutH, and UvrD, during methyl-directed mismatch repair of DNA. We have investigated the self-association properties of MutL and its binding to DNA using analytical sedimentation velocity and equilibrium. Self-association of MutL is quite sensitive to solution conditions. At 25 °C in Tris at pH 8.3, MutL assembles into a heterogeneous mixture of large multimers. In the presence of potassium phosphate at pH 7.4, MutL forms primarily stable dimers, with the higher-order assembly states suppressed. The weight-average sedimentation coefficient of the MutL dimer in this buffer (s̅ …

New Insights On Sarcoplasmic Reticulum Calcium Regulation In Muscle Fatigue, Robert H. Fitts

Biological Sciences Faculty Research and Publications

A consistent observation with fatigue in skeletal muscle is a decline in the amplitude of the myoplasmic Ca²⁺ transient, which is thought to result primarily from a reduced Ca²⁺ flux through the ryanodine receptor (RyR1) of the sarcoplasmic reticulum (SR) (Fig. 1). This in turn is thought to contribute to the loss in muscle force and power (2). In the past 20 years, the important proteins at the t-tubule SR junction have been identified (Fig. 1), and considerable progress has been made in understanding the molecular mechanism by which t-tubular charge induces SR Ca²⁺ release. However, the …

Soil Microbes Regulate Ecosystem Productivity And Maintain Species Diversity, Stefan A. Schnitzer, John Klironomos

Biological Sciences Faculty Research and Publications

One of the major goals in ecology is to determine the mechanisms that drive the asymptotic increase in ecosystem productivity with plant species diversity. Niche complementarity, the current paradigm for the asymptotic diversity-productivity pattern, posits that the addition of species to a community increases productivity because each species specializes on different resources and thus can more thoroughly utilize the available resources. At higher diversity the increase in productivity decreases because resources become limiting, resulting in the classic asymptotic diversity-productivity pattern. An alternative but less tested explanation is that density-dependent disease from species-specific soil microbes drive the diversity-productivity relationship by increasing …

A Rice Plastidial Nucleotide Sugar Epimerase Is Involved In Galactolipid Biosynthesis And Improves Photosynthetic Efficiency, Chunlai Li, Yiqin Wang, Linchuan Liu, Yingchun Hu, Fengxia Zhang, Sod Mergen, Guodong Wang, Michael Schläppi, Chengcai Chu

Biological Sciences Faculty Research and Publications

Photosynthesis is the final determinator for crop yield. To gain insight into genes controlling photosynthetic capacity, we selected from our large T-DNA mutant population a rice stunted growth mutant with decreased carbon assimilate and yield production named photoassimilate defective1 (phd1). Molecular and biochemical analyses revealed that PHD1 encodes a novel chloroplast-localized UDP-glucose epimerase (UGE), which is conserved in the plant kingdom. The chloroplast localization of PHD1 was confirmed by immunoblots, immunocytochemistry, and UGE activity in isolated chloroplasts, which was approximately 50% lower in the phd1-1 mutant than in the wild type. In addition, the amounts of …

Sequential Assembly Of Flagellar Radial Spokes, Dennis R. Diener, Pinfen Yang, Stefan Geimer, Douglas G. Cole, Winfield S. Sale, Joel L. Rosenbaum

Biological Sciences Faculty Research and Publications

The unicellular alga Chlamydomonas can assemble two 10 μm flagella in 1 h from proteins synthesized in the cell body. Targeting and transporting these proteins to the flagella are simplified by preassembly of macromolecular complexes in the cell body. Radial spokes are flagellar complexes that are partially assembled in the cell body before entering the flagella. On the axoneme, radial spokes are “T” shaped structures with a head of five proteins and a stalk of 18 proteins that sediment together at 20S. In the cell body, radial spokes are partially assembled; about half of the radial spoke proteins (RSPs) form …

The Rna Helicase Mtr4p Modulates Polyadenylation In The Tramp Complex, Huijue Jia, Xuying Wang, Fei Liu, Ulf-Peter Guenther, Sukanya Srinivasan, James T. Anderson, Eckhard Jankowsky

Biological Sciences Faculty Research and Publications

Many steps in nuclear RNA processing, surveillance, and degradation require TRAMP, a complex containing the poly(A) polymerase Trf4p, the Zn-knuckle protein Air2p, and the RNA helicase Mtr4p. TRAMP polyadenylates RNAs designated for decay or trimming by the nuclear exosome. It has been unclear how polyadenylation by TRAMP differs from polyadenylation by conventional poly(A) polymerase, which produces poly(A) tails that stabilize RNAs. Using reconstituted S. cerevisiae TRAMP, we show that TRAMP inherently suppresses poly(A) addition after only 3–4 adenosines. This poly(A) tail length restriction is controlled by Mtr4p. The helicase detects the number of 3′-terminal adenosines and, over several adenylation steps, …

Unexpected Accumulation Of Ncm5U And Ncm5S2U In A Trm9 Mutant Suggests An Additional Step In The Synthesis Of Mcm5U And Mcm5S2U, Changchun Chen, Bo Huang, James T. Anderson, Anders S. Byström

Biological Sciences Faculty Research and Publications

Background

Transfer RNAs are synthesized as a primary transcript that is processed to produce a mature tRNA. As part of the maturation process, a subset of the nucleosides are modified. Modifications in the anticodon region often modulate the decoding ability of the tRNA. At position 34, the majority of yeast cytosolic tRNA species that have a uridine are modified to 5-carbamoylmethyluridine (ncm⁵U), 5-carbamoylmethyl-2′-O-methyluridine (ncm⁵Um), 5-methoxycarbonylmethyl-uridine (mcm⁵U) or 5-methoxycarbonylmethyl-2-thiouridine (mcm⁵s²U). The formation of mcm⁵ and ncm⁵ side chains involves a complex pathway, where the last step in formation of …

To Duckweeds (Landoltia Punctata), Nanoparticulate Copper Oxide Is More Inhibitory Than The Soluble Copper In The Bulk Solution, Jiyan Shi, Aamir D. Abid, Ian M. Kennedy, Krassimira R. Hristova, Wendy K. Silk

Biological Sciences Faculty Research and Publications

CuO nanoparticles (CuO-NP) were synthesized in a hydrogen diffusion flame. Particle size and morphology were characterized using scanning mobility particle sizing, Brunauer–Emmett–Teller analysis, dynamic light scattering, and transmission electron microscopy. The solubility of CuO-NP varied with both pH and presence of other ions. CuO-NP and comparable doses of soluble Cu were applied to duckweeds, Landoltia punctata. Growth was inhibited 50% by either 0.6 mg L⁻¹ soluble copper or by 1.0 mg L⁻¹ CuO-NP that released only 0.16 mg L⁻¹ soluble Cu into growth medium. A significant decrease of chlorophyll was observed in plants stressed by 1.0 …

Effect Of Nitrate, Acetate And Hydrogen On Native Perchlorate-Reducing Microbial Communities And Their Activity In Vadose Soil, Mamie Nozawa-Inoue, Mercy Jien, Kun Yang, Dennis E. Rolston, Krassimira R. Hristova, Kate M. Scow

Biological Sciences Faculty Research and Publications

The effect of nitrate, acetate, and hydrogen on native perchlorate-reducing bacteria (PRB) was examined by conducting microcosm tests using vadose soil collected from a perchlorate-contaminated site. The rate of perchlorate reduction was enhanced by hydrogen amendment and inhibited by acetate amendment, compared with unamendment. Nitrate was reduced before perchlorate in all amendments. In hydrogen-amended and unamended soils, nitrate delayed perchlorate reduction, suggesting that the PRB preferentially use nitrate as an electron acceptor. In contrast, nitrate eliminated the inhibitory effect of acetate amendment on perchlorate reduction and increased the rate and the extent, possibly because the preceding nitrate reduction/denitrification decreased the …

Probing The Allosteric Activation Of Pyruvate Carboxylase Using 2′,3′-O-(2,4,6-Trinitrophenyl) Adenosine 5′-Triphosphate As A Fluorescent Mimic Of The Allosteric Activator Acetyl Coa, Abdussalam Adina-Zada, Rasmani Hazra, Chutima Sereerukb, Sarawut Jitrapakdee, Tonya N. Zeczycki, Martin St. Maurice, W Wallace Cleland, John C. Wallace, Paul V. Attwood

Biological Sciences Faculty Research and Publications

2′,3′-O-(2,4,6-Trinitrophenyl) adenosine 5′-triphosphate (TNP-ATP) is a fluorescent analogue of ATP. MgTNP-ATP was found to be an allosteric activator of pyruvate carboxylase that exhibits competition with acetyl CoA in activating the enzyme. There is no evidence that MgTNP-ATP binds to the MgATP substrate binding site of the enzyme. At concentrations above saturating, MgATP activates bicarbonate-dependent ATP cleavage, but inhibits the overall reaction. The fluorescence of MgTNP-ATP increases by about 2.5-fold upon binding to the enzyme and decreases on addition of saturating acetyl CoA. However, not all the MgTNP-ATP is displaced by acetyl CoA, or with a combination of saturating concentrations of …

Role Of Baca In Lipopolysaccharide Synthesis, Peptide Transport, And Nodulation By Rhizobium Sp. Strain Ngr234, Silvia Ardissone, Hajime Kobayashi, Kumiko Kambara, Coralie Rummel, K. Dale Noel, Graham C. Walker, William J. Broughton, William J. Deakin

Biological Sciences Faculty Research and Publications

BacA of Sinorhizobium meliloti plays an essential role in the establishment of nitrogen-fixing symbioses with Medicago plants, where it is involved in peptide import and in the addition of very-long-chain fatty acids (VLCFA) to lipid A of lipopolysaccharide (LPS). We investigated the role of BacA in Rhizobium species strain NGR234 by mutating the bacA gene. In the NGR234 bacA mutant, peptide import was impaired, but no effect on VLCFA addition was observed. More importantly, the symbiotic ability of the mutant was comparable to that of the wild type for a variety of legume species. Concurrently, an acpXL mutant of NGR234 …

Prion Formation And Polyglutamine Aggregation Are Controlled By Two Classes Of Genes, Anita L. Manogaran, Joo Y. Hong, Joan Hufana, Jens Tyedmers, Susan Lindquist, Susan W. Liebman

Biological Sciences Faculty Research and Publications

Prions are self-perpetuating aggregated proteins that are not limited to mammalian systems but also exist in lower eukaryotes including yeast. While much work has focused around chaperones involved in prion maintenance, including Hsp104, little is known about factors involved in the appearance of prions. De novo appearance of the [PSI+] prion, which is the aggregated form of the Sup35 protein, is dramatically enhanced by transient overexpression of SUP35 in the presence of the prion form of the Rnq1 protein, [PIN+]. When fused to GFP and overexpressed in [ps2] [PIN+] cells, Sup35 forms fluorescent rings, and cells with these rings bud …

Involvement Of Protein Kinase C And Protein Kinase A In The Enhancement Of L-Type Calcium Current By GabaB Receptor Activation In Neonatal Hippocampus, Jennifer Grace Bray, Michelle Mynlieff

Biological Sciences Faculty Research and Publications

In the early neonatal period activation of GABA_B receptors attenuates calcium current through N-type calcium channels while enhancing current through L-type calcium channels in rat hippocampal neurons. The attenuation of N-type calcium current has been previously demonstrated to occur through direct interactions of the βγ subunits of G_i/o G-proteins, but the signal transduction pathway for the enhancement of L-type calcium channels in mammalian neurons remains unknown. In the present study, calcium currents were elicited in acute cultures from postnatal day 6–8 rat hippocampi in the presence of various modulators of protein kinase A (PKA) and protein kinase C …

Community And Ecosystem Ramifications Of Increasing Lianas In Neotropical Forests, Stefan A. Schnitzer, Frans Bongers, S. Joseph Wright

Biological Sciences Faculty Research and Publications

Lianas (woody vines) are increasing in neotropical forests, representing one of the first large-scale structural changes documented for these important ecosystems. The potential ramifications of increasing lianas are huge, as lianas alter both tropical forest diversity and ecosystem functioning. At the community level, lianas affect tree species co-existence and diversity by competing more intensely with some tree species than others, and thus will likely alter tree species composition. At the ecosystem level, lianas affect forest carbon and nutrient storage and fluxes. A decrease in forest carbon storage and sequestration may be the most important ramification of liana increases. Lianas reduce …

Increasing Liana Abundance And Biomass In Tropical Forests: Emerging Patterns And Putative Mechanisms, Stefan A. Schnitzer, Frans Bongers

Biological Sciences Faculty Research and Publications

Tropical forests are experiencing large‐scale structural changes, the most apparent of which may be the increase in liana (woody vine) abundance and biomass. Lianas permeate most lowland tropical forests, where they can have a huge effect on tree diversity, recruitment, growth and survival, which, in turn, can alter tree community composition, carbon storage and carbon, nutrient and water fluxes. Consequently, increasing liana abundance and biomass have potentially profound ramifications for tropical forest composition and functioning. Currently, eight studies support the pattern of increasing liana abundance and biomass in American tropical and subtropical forests, whereas two studies, both from Africa, do …

Coming To America: Multiple Origins Of New World Geckos, Tony Gamble, A. M. Bauer, G. R. Colli, E. Greenbaum, T. R. Jackman, Laurie J. Vitt, Andrew M. Simons

Biological Sciences Faculty Research and Publications

Geckos in the Western Hemisphere provide an excellent model to study faunal assembly at a continental scale. We generated a time-calibrated phylogeny, including exemplars of all New World gecko genera, to produce a biogeographic scenario for the New World geckos. Patterns of New World gecko origins are consistent with almost every biogeographic scenario utilized by a terrestrial vertebrate with different New World lineages showing evidence of vicariance, dispersal via temporary land bridge, overseas dispersal, or anthropogenic introductions. We also recovered a strong relationship between clade age and species diversity, with older New World lineages having more species than more recently …

Neuronal Control Of Swimming Behavior: Comparison Of Vertebrate And Invertebrate Model Systems, Olivia Mullins, John Hackett, James T. Buchanan, W. Otto Friesen

Biological Sciences Faculty Research and Publications

Swimming movements in the leech and lamprey are highly analogous, and lack homology. Thus, similarities in mechanisms must arise from convergent evolution rather than from common ancestry. Despite over 40 years of parallel investigations into this annelid and primitive vertebrate, a close comparison of the approaches and results of this research is lacking. The present review evaluates the neural mechanisms underlying swimming in these two animals and describes the many similarities that provide intriguing examples of convergent evolution. Specifically, we discuss swim initiation, maintenance and termination, isolated nervous system preparations, neural-circuitry, central oscillators, intersegmental coupling, phase lags, cycle periods and …

Mathematical Model Of Chlorella Minutissima Utex2341 Growth And Lipid Production Under Photoheterotrophic Fermentation Conditions, Jinshui Yang, Ehsan Rasa, Prapakorn Tantayotai, Kate M. Scow, Hong Li Yuan, Krassimira R. Hristova

Biological Sciences Faculty Research and Publications

To reduce the cost of algal biomass production, mathematical model was developed for the first time to describe microalgae growth, lipid production and glycerin consumption under photoheterotrophic conditions based on logistic, Luedeking–Piret and Luedeking–Piret-like equations. All experiments were conducted in a 2 L batch reactor without considering CO₂ effect on algae’s growth and lipid production. Biomass and lipid production increased with glycerin as carbon source and were well described by the logistic and Luedeking–Piret equations respectively. Model predictions were in satisfactory agreement with measured data and the mode of lipid production was growth-associated. Sensitivity analysis was applied to examine …

Soil Microbes Drive The Classic Plant Diversity–Productivity Pattern, Stefan A. Schnitzer, John Klironomos, Janneke Hillerislambers, Linda L. Kinkel, Peter B. Reich, Kun Xiao, Matthias C. Rillig, Benjamin A. Sikes, Ragan M. Callaway, Scott A. Mangan, Egbert H. Van Nes, Marten Scheffer

Biological Sciences Faculty Research and Publications

Ecosystem productivity commonly increases asymptotically with plant species diversity, and determining the mechanisms responsible for this well‐known pattern is essential to predict potential changes in ecosystem productivity with ongoing species loss. Previous studies attributed the asymptotic diversity–productivity pattern to plant competition and differential resource use (e.g., niche complementarity). Using an analytical model and a series of experiments, we demonstrate theoretically and empirically that host‐specific soil microbes can be major determinants of the diversity–productivity relationship in grasslands. In the presence of soil microbes, plant disease decreased with increasing diversity, and productivity increased nearly 500%, primarily because of the strong effect of …