Life Sciences Commons^™

Two Leucine-Rich Repeat Receptor Kinases Mediate Signaling, Linking Cell Wall Biosynthesis And Acc Synthase In Arabidopsis, Shou-Ling Xu, Abidur Rahman, Tobias Baskin, Joseph J. Kieber

Tobias Baskin

The plant cell wall is a dynamic structure that changes in response to developmental and environmental cues through poorly understood signaling pathways. We identified two Leu-rich repeat receptor-like kinases in Arabidopsis thaliana that play a role in regulating cell wall function. Mutations in these FEI1 and FEI2 genes (named for the Chinese word for fat) disrupt anisotropic expansion and the synthesis of cell wall polymers and act additively with inhibitors or mutations disrupting cellulose biosynthesis. While FEI1 is an active protein kinase, a kinase-inactive version of FEI1 was able to fully complement the fei1 fei2 mutant. The expansion defect in …

Intercourse Between Cell Wall And Cytoplasm Exemplified By Arabinogalactan Proteins And Cortical Microtubules, Azeddine Driouich, Tobias Baskin

Tobias Baskin

How does a plant cell sense and respond to the status of its cell wall? Intercourse between cell wall and cytoplasm has long been supposed to involve arabinogalactan proteins, in part because many of them are anchored to the plasma membrane. Disrupting arabinogalactan proteins has recently been shown to disrupt the array of cortical microtubules present just inside the plasma membrane, implying that microtubules and arabinogalactan proteins interact. In this article, we assess possibilities for how this interaction might be mediated. First, we consider microdomains in the plasma membrane (lipid rafts), which have been alleged to link internal and external …

Graded Hedgehog And Fibroblast Growth Factor Signaling Independently Regulate Pituitary Cell Fates And Help Establish The Pars Distalis And Pars Intermedia Of The Zebrafish Adenohypophysis, Burcu Guner, A. Tuba Ozacar, Jeanne E. Thomas, Rolf O. Karlstrom

Rolf O Karlstrom

The vertebrate adenohypophysis forms as a placode at the anterior margin of the neural plate, requiring both hedgehog (Hh) and fibroblast growth factor (Fgf) mediated cell-cell signaling for induction and survival of endocrine cell types. Using small molecule inhibitors to modulate signaling levels during zebrafish development we show that graded Hh and Fgf signaling independently help establish the two subdomains of the adenohypophysis, the anteriorly located pars distalis (PD) and the posterior pars intermedia (PI). High levels of Hh signaling are required for formation of the PD and differentiation of anterior endocrine cell types, whereas lower levels of Hh signaling …

Development Of Genetic And Genomic Research Resources For Brachypodium Distachyon, A New Model System For Grass Crop Research, David F. Garvin, Yonb-Qiang Gu, Robert Hasterok, Samuel P. Hazen, Glyn Jenkins, Todd C. Mockler, Luis A J Mur, John P. Vogel

Samuel P Hazen

Grass crop genomics research frequently is hindered by large genome sizes and polyploidy. While rice is an attractive system for grass genomics due to its small genome size and available genome sequence, it is not particularly well-suited as a robust model system for all grass crops. The wild grass species Brachypodium distachyon (L.) P. Beauv. (Brachypodium) has recently gained favor as a new model system for grass crop genomics research because it possesses a suite of biological traits desired in a model system. Further, it is more closely related to the large and diverse group of cool season grass crops …

Differential Effects Of Methyl Jasmonate On Growth And Division Of Etiolated Zucchini Cotyledons, E Stoynova-Bakalova, Pi Petrov, L Gigova, Ti Baskin

Biology Department Faculty Publication Series

No abstract provided.

Intercourse Between Cell Wall And Cytoplasm Exemplified By Arabinogalactan Proteins And Cortical Microtubules, A Driouich, Ti Baskin

Biology Department Faculty Publication Series

No abstract provided.

Morphological Convergence As A Consequence Of Extreme Functional Demands: Examples From The Feeding System Of Natricine Snakes, A Herrel, Se Vincent, Me Alfaro, S Van Wassenbergh, B Vanhooydonck, Dj Irschick

Biology Department Faculty Publication Series

Despite repeated acquisitions of aquatic or semi-aquatic lifestyles revolving around piscivory, snakes have not evolved suction feeding. Instead, snakes use frontally or laterally directed strikes to capture prey under water. If the aquatic medium constrains strike performance because of its physical properties, we predict morphological and functional convergence in snakes that use similar strike behaviours. Here we use natricine snakes to test for such patterns of convergence in morphology and function. Our data show that frontal strikers have converged on a similar morphology characterized by narrow elongate heads with a reduced projected frontal surface area. Moreover, simple computational fluid dynamics …

Expression Profiling Identifies Novel Hh/Gli-Regulated Genes In Developing Zebrafish Embryos, Sadie A. Bergeron, Luis A. Milla, Rosario Villegas, Meng-Chieh Shen, Shawn M. Burgess, Miguel L. Allende, Rolf O. Karlstrom, Verónica Palma

Biology Department Faculty Publication Series

The Hedgehog (Hh) signaling pathway plays critical instructional roles during embryonic development. Misregulation of Hh/Gli signaling is a major causative factor in human congenital disorders and in a variety of cancers. The zebrafish is a powerful genetic model for the study of Hh signaling during embryogenesis, as a large number of mutants that affect different components of the Hh/Gli signaling system have been identified. By performing global profiling of gene expression in different Hh/Gli gain- and loss-of-function scenarios we identified known (e.g., ptc1 and nkx2.2a) and novel Hh-regulated genes that are differentially expressed in embryos with altered Hh/Gli signaling …

Actin Depolymerizing Factor Is Essential For Viability In Plants, And Its Phosphoregulation Is Important For Tip Growth, Rc Augustine, L Vidali, Kp Kleinman, M Bezanilla

Biology Department Faculty Publication Series

No abstract provided.

Rapid Large-Scale Evolutionary Divergence In Morphology And Performance Associated With Exploitation Of A Different Dietary Resource, Anthony Herrel, Katleen Huyghe, Bieke Vanhooydonck, Thierry Backeljau, Karin Breugelmans, Irena Grbac, Raoul Van Damme, Duncan J. Irschick

Biology Department Faculty Publication Series

Although rapid adaptive changes in morphology on ecological time scales are now well documented in natural populations, the effects of such changes on whole-organism performance capacity and the consequences on ecological dynamics at the population level are often unclear. Here we show how lizards have rapidly evolved differences in head morphology, bite strength, and digestive tract structure after experimental introduction into a novel environment. Despite the short time scale (≈36 years) since this introduction, these changes in morphology and performance parallel those typically documented among species and even families of lizards in both the type and extent of their specialization. …

Tissue-Specific Requirements For Specific Domains In The Ferm Protein Moe/Epb4.1i5 During Early Zebrafish Development, Arne K. Christensen, Abbie M. Jensen

Biology Department Faculty Publication Series

Background

The FERM domain containing protein Mosaic Eyes (Moe) interacts with Crumbs proteins, which are important regulators of apical identity and size. In zebrafish, loss-of-function mutations in moe result in defects in brain ventricle formation, retinal pigmented epithelium and neural retinal development, pericardial edema, and tail curvature. In humans and mice, there are two major alternately spliced isoforms of the Moe orthologue, Erythrocyte Protein Band 4.1-Like 5 (Epb4.1l5), which we have named Epb4.1l5long and Epb4.1l5short, that differ after the FERM domain. Interestingly, Moe and both Epb4.1l5 isoforms have a putative C' terminal Type-I PDZ-Binding Domain (PBD). We previously showed that …

Meeting Report: Moving Upstream—Evaluating Adverse Upstream End Points For Improved Risk Assessment And Decision-Making, R. Thomas Zoeller, T. J. Woodruff, L. Zeise, D. A. Axelrad, K. Z. Guyton, S. Janssen, M. Miller, G. G. Miller, J. M. Schwartz, G. Alexeeff, H. Anderson, L. Birnbaum, F. Bois, V. J. Cogliano, K. Crofton, S. Y. Euling, P. M. Foster, D. R. Germolec, E. Gray, D. B. Hattis, A. D. Kyle, R. W. Luebke, M. I. Luster, C. Portier, D. C. Rice, G Solomon, J. Vandenberg, R. Thomas Zoeller

R. Thomas Zoeller

Background Assessing adverse effects from environmental chemical exposure is integral to public health policies. Toxicology assays identifying early biological changes from chemical exposure are increasing our ability to evaluate links between early biological disturbances and subsequent overt downstream effects. A workshop was held to consider how the resulting data inform consideration of an “adverse effect” in the context of hazard identification and risk assessment. Objectives Our objective here is to review what is known about the relationships between chemical exposure, early biological effects (upstream events), and later overt effects (downstream events) through three case studies (thyroid hormone disruption, antiandrogen effects, …

Tissue-Specific Requirements For Specific Domains In The Ferm Protein Moe/Epb4.1l5 During Early Zebrafish Development, Abigail Jensen, A. K. Christensen

Abigail Jensen

Background The FERM domain containing protein Mosaic Eyes (Moe) interacts with Crumbs proteins, which are important regulators of apical identity and size. In zebrafish, loss-of-function mutations in moe result in defects in brain ventricle formation, retinal pigmented epithelium and neural retinal development, pericardial edema, and tail curvature. In humans and mice, there are two major alternately spliced isoforms of the Moe orthologue, Erythrocyte Protein Band 4.1-Like 5 (Epb4.1l5), which we have named Epb4.1l5long and Epb4.1l5short, that differ after the FERM domain. Interestingly, Moe and both Epb4.1l5 isoforms have a putative C' terminal Type-I PDZ-Binding Domain (PBD). We previously showed that …

Network Discovery Pipeline Elucidates Conserved Time Of Day Specific Cis-Regulatory Modules, Samuel P. Hazen, T. P. Michael, T. C. Mocker, G. Brenton, C. Mcentee, A Byer, J. D. Trout, H. D. Priest, C. M. Sullivan, R. Shen, S. A. Givan, M. Yanovsky, F. Hong, S. A. Kay, J. A. Chory

Samuel P Hazen

Correct daily phasing of transcription confers an adaptive advantage to almost all organisms, including higher plants. In this study, we describe a hypothesis-driven network discovery pipeline that identifies biologically relevant patterns in genome-scale data. To demonstrate its utility, we analyzed a comprehensive matrix of time courses interrogating the nuclear transcriptome of Arabidopsis thaliana plants grown under different thermocycles, photocycles, and circadian conditions. We show that 89% of Arabidopsis transcripts cycle in at least one condition and that most genes have peak expression at a particular time of day, which shifts depending on the environment. Thermocycles alone can drive at least …

Morning-Specific Phytohormone Gene Expression Program Underlying Rhythmic Plant Growth, Samuel P. Hazen, T. P. Michael, G. Breton, H. D. Priest, T. C. Mockler, S. A. Kay, J. A. Chory

Samuel P Hazen

Most organisms use daily light/dark cycles as timing cues to control many essential physiological processes. In plants, growth rates of the embryonic stem (hypocotyl) are maximal at different times of day, depending on external photoperiod and the internal circadian clock. However, the interactions between light signaling, the circadian clock, and growth-promoting hormone pathways in growth control remain poorly understood. At the molecular level, such growth rhythms could be attributed to several different layers of time-specific control such as phasing of transcription, signaling, or protein abundance. To determine the transcriptional component associated with the rhythmic control of growth, we applied temporal …

Rapid Large-Scale Evolutionary Divergence In Morphology And Performance Associated With Exploitation Of A Different Dietary Resource, Duncan J. Irschick, A. Herrel, K. Huyghe, B. Vanhooydonck, T. Backeljau, K. Breugelmans, I. Grbac, R. Vandamme

Duncan J. Irschick

Although rapid adaptive changes in morphology on ecological time scales are now well documented in natural populations, the effects of such changes on whole-organism performance capacity and the consequences on ecological dynamics at the population level are often unclear. Here we show how lizards have rapidly evolved differences in head morphology, bite strength, and digestive tract structure after experimental introduction into a novel environment. Despite the short time scale (≈36 years) since this introduction, these changes in morphology and performance parallel those typically documented among species and even families of lizards in both the type and extent of their specialization. …

Dual Role For Microtubules In Regulating Cortical Contractility During Cytokinesis, Patricia Wadsworth, K. Murphy

Patricia Wadsworth

Microtubules stimulate contractile-ring formation in the equatorial cortex and simultaneously suppress contractility in the polar cortex; how they accomplish these differing activities is incompletely understood. We measured the behavior of GFP-actin in mammalian cells treated with nocodazole under conditions that either completely eliminate microtubules or selectively disassemble astral microtubules. Selective disassembly of astral microtubules resulted in functional contractile rings that were wider than controls and had altered dynamic activity, as measured by FRAP. Complete microtubule disassembly or selective loss of astral microtubules resulted in wave-like contractile behavior of actin in the non-equatorial cortex, and mislocalization of myosin II and Rho. …

Geographic Diversity Cline Of R Gene Homologs In Wild Populations Of Solanum Pimpinellifolium (Solanaceae), Ana Lucia Caicedo

Ana Lucia Caicedo

Plant resistance (R) genes tend to be highly variable within plant species and are thought to be under natural selection; however, little is known about the geographic distribution of R gene diversity within and among plant populations. To determine the possible roles of demography and selection on R gene evolution, patterns of diversity at the multigenic Cf-2 R gene family were studied in Solanum pimpinellifolium populations along the northern coast of Peru. Population diversity levels of Cf-2 homologs follow a latitudinal cline, consistent with the species's history of gradual colonization of the Peruvian coast and population variation in outcrossing levels. …

The Role Of Sos Boxes In Enteric Bacteriocin Regulation, Margaret Riley, Osnat Gillor, Jan A.C. Vriezen

Margaret Riley

Bacteriocins are a large and functionally diverse family of toxins found in all major lineages of Bacteria. Colicins, those bacteriocins produced by Escherichia coli, serve as a model system for investigations of bacteriocin structure–function relationships, genetic organization, and their ecological role and evolutionary history. Colicin expression is often dependent on host regulatory pathways (such as the SOS system), is usually confined to times of stress, and results in death of the producing cells. This study investigates the role of the SOS system in mediating this unique form of toxin expression. A comparison of all the sequenced enteric bacteriocin promoters reveals …

Deciphering Evolutionary Mechanisms Between Mutualistic And Pathogenic Symbioses, Margaret Riley, M. K. Nishiguchi, A. M. Hirsch, R. Devinney, G. Vedantam, L. M. Mansky

Margaret Riley

The continuum between mutualistic and pathogenic symbioses has been an underlying theme for understanding the evolution of infection and disease in a number of eukaryotic-microbe associations. The ability to monitor and then predict the spread of infectious diseases may depend upon our knowledge and capabilities of anticipating the behavior of virulent pathogens by studying related, benign symbioses. For instance, the ability of a symbiotic species to infect, colonize, and proliferate efficiently in a susceptible host will depend on a number of factors that influence both partners during the infection. Levels of virulence are not only affected by the genetic and …

Two Leucine-Rich Repeat Receptor Kinases Mediate Signaling, Linking Cell Wall Biosynthesis And Acc Synthase In Arabidopsis, Sl Xu, A Rahman, Ti Baskin, Jj Kieber

Biology Department Faculty Publication Series

No abstract provided.

Tissue-Specific Requirements For Specific Domains In The Ferm Protein Moe/Epb4.1l5 During Early Zebrafish Development, Arne K. Christensen, Abigail Jensen

Biochemistry & Molecular Biology Department Faculty Publication Series

Background The FERM domain containing protein Mosaic Eyes (Moe) interacts with Crumbs proteins, which are important regulators of apical identity and size. In zebrafish, loss-of-function mutations in moe result in defects in brain ventricle formation, retinal pigmented epithelium and neural retinal development, pericardial edema, and tail curvature. In humans and mice, there are two major alternately spliced isoforms of the Moe orthologue, Erythrocyte Protein Band 4.1-Like 5 (Epb4.1l5), which we have named Epb4.1l5long and Epb4.1l5short, that differ after the FERM domain. Interestingly, Moe and both Epb4.1l5 isoforms have a putative C' terminal Type-I PDZ-Binding Domain (PBD). We previously showed that …

Geographic Diversity Cline Of R Gene Homologs In Wild Populations Of Solanum Pimpinellifolium (Solanaceae), Ana L. Caicedo

Biology Department Faculty Publication Series

Plant resistance (R) genes tend to be highly variable within plant species and are thought to be under natural selection; however, little is known about the geographic distribution of R gene diversity within and among plant populations. To determine the possible roles of demography and selection on R gene evolution, patterns of diversity at the multigenic Cf-2 R gene family were studied in Solanum pimpinellifolium populations along the northern coast of Peru. Population diversity levels of Cf-2 homologs follow a latitudinal cline, consistent with the species's history of gradual colonization of the Peruvian coast and population variation in …

Of Arcs And Vaults: The Biomechanics Of Bone-Cracking In Spotted Hyenas (Crocuta Crocuta), Jaime B. Tanner, Elizabeth R. Dumont, Sharleen T. Sakai, Barbara L. Lundrigan, Kay E. Holekamp

Biology Department Faculty Publication Series

The ability to break open large bones has evolved independently in only three groups of carnivorous mammals, all of which have robust teeth, vaulted foreheads, and pronounced sagittal crests. One unusual skull feature, present in bone-cracking members of the family Hyaenidae, is a caudally elongated frontal sinus, hypothesized to function in resistance to bending and stress dissipation during bone-cracking. In the present study, we used finite element (FE) analysis to examine patterns of stress distribution in the spotted hyena (Crocuta crocuta) skull during unilateral biting, and inquire about the functional role of the fronto-parietal sinus in stress dissipation. …

Graded Hedgehog And Fibroblast Growth Factor Signaling Independently Regulate Pituitary Cell Fates And Help Establish The Pars Distalis And Pars Intermedia Of The Zebrafish Adenohypophysis, Burcu Guner, A. Tuba Ozacar, Jeanne E. Thomas, Rolf O. Karlstrom

Biology Department Faculty Publication Series

The vertebrate adenohypophysis forms as a placode at the anterior margin of the neural plate, requiring both hedgehog (Hh) and fibroblast growth factor (Fgf) mediated cell-cell signaling for induction and survival of endocrine cell types. Using small molecule inhibitors to modulate signaling levels during zebrafish development we show that graded Hh and Fgf signaling independently help establish the two subdomains of the adenohypophysis, the anteriorly located pars distalis (PD) and the posterior pars intermedia (PI). High levels of Hh signaling are required for formation of the PD and differentiation of anterior endocrine cell types, whereas lower levels of Hh signaling …