Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 11 of 11
Full-Text Articles in Entire DC Network
Attracting Antagonists: Does Floral Nectar Increase Leaf Herbivory?, Lynn Adler, Judith L. Bronstein
Attracting Antagonists: Does Floral Nectar Increase Leaf Herbivory?, Lynn Adler, Judith L. Bronstein
Lynn Adler
Traits that are attractive to mutualists may also attract antagonists, resulting in conflicting selection pressures. Here we develop the idea that increased floral nectar production can, in some cases, increase herbivory. In these situations, selection for increased nectar production to attract pollinators may be constrained by a linked cost of herbivore attraction. In support of this hypothesis, we report that experimentally supplementing nectar rewards in Datura stramonium led to increased oviposition by Manduca sexta, a sphingid moth that pollinates flowers, but whose larvae feed on leaf tissue. We speculate that nectar composition may provide information about plant nutritional status or …
Synergistic And Antagonistic Roles Of The Sonic Hedgehog N- And C-Terminal Lipids, Jianchi Feng, Bryan White, Oksana V. Tyurina, Burcu Guner, Theresa Larson, Hae Young Lee, Rolf O. Karlstrom, Jhumku D. Kohtz
Synergistic And Antagonistic Roles Of The Sonic Hedgehog N- And C-Terminal Lipids, Jianchi Feng, Bryan White, Oksana V. Tyurina, Burcu Guner, Theresa Larson, Hae Young Lee, Rolf O. Karlstrom, Jhumku D. Kohtz
Rolf O Karlstrom
The Shh protein contains both N-terminal and C-terminal lipids. The functional redundancy of these lipid moieties is presently unclear. Here, we compare the relative roles of the N- and C-terminal lipids in early rat striatal neuronal differentiation, membrane association and multimerization, and ventralizing activity in the zebrafish forebrain. We show that these lipid act synergistically in cell tethering and the formation of a large (L) multimer (669 kDa). However, the C-terminal lipid antagonizes the rat striatal neuronal differentiation-inducing activity of the N-terminal lipid. In addition, multimerization is required but not sufficient for the differentiation-inducing activity. Based on the presence of …
A Regulatory Code For Neurogenic Gene Expression In The Drosophila Embryo, Michele Markstein, Robert Zinzen, Peter Markstein, Ka Ping Yee, Albert Erives, Angela Stathopoulos, Michael Levine
A Regulatory Code For Neurogenic Gene Expression In The Drosophila Embryo, Michele Markstein, Robert Zinzen, Peter Markstein, Ka Ping Yee, Albert Erives, Angela Stathopoulos, Michael Levine
Michele Markstein
Bioinformatics methods have identified enhancers that mediate restricted expression in the Drosophila embryo. However, only a small fraction of the predicted enhancers actually work when tested in vivo. In the present study, co-regulated neurogenic enhancers that are activated by intermediate levels of the Dorsal regulatory gradient are shown to contain several shared sequence motifs. These motifs permitted the identification of new neurogenic enhancers with high precision: five out of seven predicted enhancers direct restricted expression within ventral regions of the neurogenic ectoderm. Mutations in some of the shared motifs disrupt enhancer function, and evidence is presented that the Twist and …
Expression Of Haper1 And Habmal1 In Syrian Hamsters: Heterogeneity Of Transcripts And Oscillations In The Periphery, Eric L. Bittman, Yanhong Tong, Hongnian Guo, Judy Mckinley Brewer, Alexamder S. Bois
Expression Of Haper1 And Habmal1 In Syrian Hamsters: Heterogeneity Of Transcripts And Oscillations In The Periphery, Eric L. Bittman, Yanhong Tong, Hongnian Guo, Judy Mckinley Brewer, Alexamder S. Bois
Eric L. Bittman
The molecular biology of circadian rhythms has been extensively studied in mice, and the widespread expression of canonical circadian clock genes in peripheral organs is well established in this species. In contrast, much less information about the peripheral expression of haPer1, haPer2, and haBmal1 is available in Syrian hamsters despite the fact that this species is widely used for studies of circadian organization and photoperiodic responses. Furthermore, examination of oscillating expression of these genes in mouse testis has generated discrepant results, and little is known about gonadal expression of haPer1 and haBmal1 or their environmental control. To address these questions, …
Immunity Regulatory Dnas Share Common Organizational Features In Drosophila, Kate Senger, Grant W. Armstrong, William J. Rowell, Jennifer M. Kwan, Michele Markstein, Michael Levine
Immunity Regulatory Dnas Share Common Organizational Features In Drosophila, Kate Senger, Grant W. Armstrong, William J. Rowell, Jennifer M. Kwan, Michele Markstein, Michael Levine
Michele Markstein
Infection results in the rapid activation of immunity genes in the Drosophila fat body. Two classes of transcription factors have been implicated in this process: the REL-containing proteins, Dorsal, Dif, and Relish, and the GATA factor Serpent. Here we present evidence that REL-GATA synergy plays a pervasive role in the immune response. SELEX assays identified consensus binding sites that permitted the characterization of several immunity regulatory DNAs. The distribution of REL and GATA sites within these DNAs suggests that most or all fat-specific immunity genes contain a common organization of regulatory elements: closely linked REL and GATA binding sites positioned …
Disorganization Of Cortical Microtubules Stimulates Tangential Expansion And Reduces The Uniformity Of Cellulose Microfibril Alignment Among Cells In The Root Of Arabidopsis Thaliana, Tobias Baskin, G.T.S. Beemster, J.E. Judy-March, F. Marga
Disorganization Of Cortical Microtubules Stimulates Tangential Expansion And Reduces The Uniformity Of Cellulose Microfibril Alignment Among Cells In The Root Of Arabidopsis Thaliana, Tobias Baskin, G.T.S. Beemster, J.E. Judy-March, F. Marga
Tobias Baskin
To test the role of cortical microtubules in aligning cellulose microfibrils and controlling anisotropic expansion, we exposed Arabidopsis thaliana roots to moderate levels of the microtubule inhibitor, oryzalin. After 2 d of treatment, roots grow at approximately steady state. At that time, the spatial profiles of relative expansion rate in length and diameter were quantified, and roots were cryofixed, freeze-substituted, embedded in plastic, and sectioned. The angular distribution of microtubules as a function of distance from the tip was quantified from antitubulin immunofluorescence images. In alternate sections, the overall amount of alignment among microfibrils and their mean orientation as a …
Yellow Stripe1. Expanded Roles For The Maize Iron-Phytosiderophore Transporter, Elsbeth Walker, L. A. Roberts, A. J. Pierson, Z Panaviene
Yellow Stripe1. Expanded Roles For The Maize Iron-Phytosiderophore Transporter, Elsbeth Walker, L. A. Roberts, A. J. Pierson, Z Panaviene
Elsbeth Walker
Graminaceous monocots, including most of the world's staple grains (i.e. rice, corn, and wheat) use a chelation strategy (Strategy II) for primary acquisition of iron from the soil. Strategy II plants secrete phytosiderophores (PS), compounds of the mugineic acid family that form stable Fe(III) chelates in soil. Uptake of iron-PS chelates, which occurs through specific transporters at the root surface, thus represents the primary route of iron entry into Strategy II plants. The gene Yellow stripe1 (Ys1) encodes the Fe(III)-PS transporter of maize (Zea mays). Here the physiological functions performed by maize YS1 were further defined by examining the pattern …
Managing The Wild: Should Stewards Be Pilots?, Peter Alpert
Managing The Wild: Should Stewards Be Pilots?, Peter Alpert
Peter Alpert
No abstract provided.
Extrapair Paternity Increases Variability In Male Reproductive Success In The Chestnut-Sided Warbler (Dendroica Pensylvanica), A Socially Monogamous Songbirds, Bruce Byers
Bruce Byers
A monogamous mating system that includes extrapair fertilization can potentially generate higher variability in male reproductive success than monogamy without extrapair fertilization. That increased variability could provide a correspondingly higher opportunity for sexual selection and, thus, for the origin and persistence of sexual dimorphism in monogamous species. To determine whether extrapair fertilization enhanced the opportunity for sexual selection in a sexually dimorphic, monogamous bird species, we used microsatellite DNA typing to assess the prevalence of extrapair fertilization and its effect on variation in male reproductive success in a population of Chestnut-sided Warblers (Dendroica pensylvanica). We found that the level of …
Heterogeneous Evolutionary Processes Affect R Gene Diversity In Natural Populations Of Solanum Pimpinellifolium, Ana Lucia Caicedo, B. A. Schaal
Heterogeneous Evolutionary Processes Affect R Gene Diversity In Natural Populations Of Solanum Pimpinellifolium, Ana Lucia Caicedo, B. A. Schaal
Ana Lucia Caicedo
Resistance (R) genes of plants are responsible for pathogen recognition and encode proteins that trigger a cascade of responses when a pathogen invades a plant. R genes are assumed to be under strong selection, but there is limited knowledge of the processes affecting R gene diversity in the wild. In this study, DNA sequence variation of Cf-2 homologs was surveyed in populations of Solanum pimpinellifolium, a wild relative of the cultivated tomato. The Cf-2 locus is involved in resistance to strains of the fungus Cladosporium fulvum. At least 26 different Cf-2 homologs were detected in natural populations of S. pimpinellifolium. …
Epistatic Interaction Between The Arabidopsis Fri And Flc Flowering Time Genes Generates A Latitudinal Cline In A Life History Trait, Ana Lucia Caicedo, J. R. Stinchcombe, K. M. Olsen, J Schmitt, M. D. Purugganan
Epistatic Interaction Between The Arabidopsis Fri And Flc Flowering Time Genes Generates A Latitudinal Cline In A Life History Trait, Ana Lucia Caicedo, J. R. Stinchcombe, K. M. Olsen, J Schmitt, M. D. Purugganan
Ana Lucia Caicedo
Epistatic gene interactions are believed to be a major factor in the genetic architecture of evolutionary diversification. In Arabidopsis thaliana, the FRI and FLC genes mechanistically interact to control flowering time, and here we show that this epistatic interaction also contributes to a latitudinal cline in this life history trait within the species. Two major FLC haplogroups (FLCA and FLCB ) are associated with flowering time variation in A. thaliana in field conditions, but only in the presence of putatively functional FRI alleles. Significant differences in latitudinal distribution of FLC haplogroups in Eurasia and North Africa also depend on the …