Showing 151 - 160 of 257 Items
The identification and visualization of candidate early embryonic patterning genes in Bradysia coprophila This record is embargoed.
- Embargo End Date: 2027-05-16
Date: 2024-01-01
Creator: Sarah Conant
Access: Embargoed
C-terminal methylation of truncated neuropeptides: An enzyme- assistedextraction artifact involving methanol
Date: 2013-01-01
Creator: Elizabeth A. Stemmler, Elizabeth E. Barton, Onyinyechi K. Esonu, Daniel A. Polasky, Laura L., Onderko, Audrey B. Bergeron, Andrew E. Christie, Patsy S. Dickinson
Access: Open access
- Neuropeptides are the largest class of signaling molecules used by nervous systems. Today, neuropeptidediscovery commonly involves chemical extraction from a tissue source followed by mass spectrometriccharacterization. Ideally, the extraction procedure accurately preserves the sequence and any inher-ent modifications of the native peptides. Here, we present data showing that this is not always true.Specifically, we present evidence showing that, in the lobster Homarus americanus, the orcokinin fam-ily members, NFDEIDRSGFG-OMe and SSEDMDRLGFG-OMe, are non-native peptides generated fromfull-length orcokinin precursors as the result of a highly selective peptide modification (peptide trun-cation with C-terminal methylation) that occurs during extraction. These peptides were observed byMALDI-FTMS and LC-Q-TOFMS analyses when eyestalk ganglia were extracted in a methanolic solvent,but not when tissues were dissected, co-crystallized with matrix, and analyzed directly with methanolexcluded from the sample preparation. The identity of NFDEIDRSGFG-OMe was established using MALDI-FTMS/SORI-CID, LC-Q-TOFMS/MS, and comparison with a peptide standard. Extraction substitutingdeuterated methanol for methanol confirmed that the latter is the source of the C-terminal methyl group,and MS/MS confirmed the C-terminal localization of the added CD3. Surprisingly, NFDEIDRSGFG-OMe isnot produced via a chemical acid-catalyzed esterification. Instead, the methylated peptide appears toresult from proteolytic truncation in the presence of methanol, as evidenced by a reduction in conver-sion with the addition of a protease-inhibitor cocktail; heat effectively eliminated the conversion. Thisunusual and highly specific extraction-derived peptide conversion exemplifies the need to consider bothchemical and biochemical processes that may modify the structure of endogenous neuropeptides. © 2013 The Authors. Published by Elsevier Inc. All rights reserved.
Characterization of Yellow Family Proteins in Gryllus bimaculatus
Date: 2021-01-01
Creator: Alexandra W. Rubenstein
Access: Open access
- Neuronal plasticity occurs in developing nervous systems, with adult organisms rarely able to recover from neurological damage. The cricket, Gryllus bimaculatus, is useful to study neuronal plasticity due to its reorganization of the auditory system in response to injury beyond development. When a cricket ear is removed and auditory afferents severed, a rare phenomenon occurs: the dendrites of interneurons on the deafferented side cross the typically-respected midline of the prothoracic ganglion to form functional synapses with auditory afferents from the opposite side. To find proteins involved in this phenomenon, the Horch Lab assembled a de novo transcriptome from neurons in the prothoracic ganglion of G. bimaculatus. Differential gene expression analysis revealed upregulated protein yellows post-deafferentation, indicating these proteins could influence neuronal plasticity in the adult cricket CNS. I focused on characterizing the protein yellow family in the cricket. By relating protein yellows evolutionarily, mapping them onto the genome, and analyzing their sequences, I discovered the cricket has 10 yellow genes, including a newly identified yellow-r* and a block of yellows showing synteny with insect genomes. Additionally, yellow-e and -x in crickets are closely related to bacterial yellow, perhaps indicating a role for horizontal gene transfer in yellow gene evolution. The protein upregulated in the cricket CNS is closely related with yellow-f’s in other insects, indicating yellow-f is likely a secreted protein, highly expressed in the CNS, multifunctional, and conserved across insects. Characterizing yellow-f can give insight into how these upregulated proteins might be related to neuronal plasticity in G. bimaculatus.
Photosynthetic phenology of a boreal spruce forest observed at stand and needle scales This record is embargoed.
- Embargo End Date: 2025-05-19
Date: 2022-01-01
Creator: Jeremy A. Hoyne Grosvenor
Access: Embargoed
Manipulation of Fgf and Bmp signaling in teleost fishes suggests potential pathways for the evolutionary origin of multicuspid teeth
Date: 2013-03-01
Creator: William R. Jackman, Shelby H. Davies, David B. Lyons, Caitlin K. Stauder, Benjamin R., Denton-Schneider, Andrea Jowdry, Sharon R. Aigler, Scott A. Vogel, David W. Stock
Access: Open access
- Teeth with two or more cusps have arisen independently from an ancestral unicuspid condition in a variety of vertebrate lineages, including sharks, teleost fishes, amphibians, lizards, and mammals. One potential explanation for the repeated origins of multicuspid teeth is the existence of multiple adaptive pathways leading to them, as suggested by their different uses in these lineages. Another is that the addition of cusps required only minor changes in genetic pathways regulating tooth development. Here we provide support for the latter hypothesis by demonstrating that manipulation of the levels of Fibroblast growth factor (Fgf) or Bone morphogenetic protein (Bmp) signaling produces bicuspid teeth in the zebrafish (Danio rerio), a species lacking multicuspid teeth in its ancestry. The generality of these results for teleosts is suggested by the conversion of unicuspid pharyngeal teeth into bicuspid teeth by similar manipulations of the Mexican Tetra (Astyanax mexicanus). That these manipulations also produced supernumerary teeth in both species supports previous suggestions of similarities in the molecular control of tooth and cusp number. We conclude that despite their apparent complexity, the evolutionary origin of multicuspid teeth is positively constrained, likely requiring only slight modifications of a pre-existing mechanism for patterning the number and spacing of individual teeth. © 2013 Wiley Periodicals, Inc.
Pleiotropic functions of embryonic sonic hedgehog expression link jaw and taste bud amplification with eye loss during cavefish evolution
Date: 2009-06-01
Creator: Yoshiyuki Yamamoto, Mardi S. Byerly, William R. Jackman, William R. Jeffery
Access: Open access
- This study addresses the role of sonic hedgehog (shh) in increasing oral-pharyngeal constructive traits (jaws and taste buds) at the expense of eyes in the blind cavefish Astyanax mexicanus. In cavefish embryos, eye primordia degenerate under the influence of hyperactive Shh signaling. In concert, cavefish show amplified jaw size and taste bud numbers as part of a change in feeding behavior. To determine whether pleiotropic effects of hyperactive Shh signaling link these regressive and constructive traits, shh expression was compared during late development of the surface-dwelling (surface fish) and cave-dwelling (cavefish) forms of Astyanax. After an initial expansion along the midline of early embryos, shh was elevated in the oral-pharyngeal region in cavefish and later was confined to taste buds. The results of shh inhibition and overexpression experiments indicate that Shh signaling has an important role in oral and taste bud development. Conditional overexpression of an injected shh transgene at specific times in development showed that taste bud amplification and eye degeneration are sensitive to shh overexpression during the same early developmental period, although taste buds are not formed until much later. Genetic crosses between cavefish and surface fish revealed an inverse relationship between eye size and jaw size/taste bud number, supporting a link between oral-pharyngeal constructive traits and eye degeneration. The results suggest that hyperactive Shh signaling increases oral and taste bud amplification in cavefish at the expense of eyes. Therefore, selection for constructive oral-pharyngeal traits may be responsible for eye loss during cavefish evolution via pleiotropic function of the Shh signaling pathway. © 2009 Elsevier Inc. All rights reserved.
Analysis of the yeast arginine methyltransferase Hmt1p/Rmt1p and its in vivo function. Cofactor binding and substrate interactions
Date: 2000-02-04
Creator: Anne E. McBride, Valerie H. Weiss, Heidi K. Kim, James M. Hogle, Pamela A., Silver
Access: Open access
- Many eukaryotic RNA-binding proteins are modified by methylation of arginine residues. The yeast Saccharomyces cerevisiae contains one major arginine methyltransferase, Hmt1p/Rmt1p, which is not essential for normal cell growth. However, cells missing HMT1 and also bearing mutations in the mRNA-binding proteins Np13p or Cbp80p can no longer survive, providing genetic backgrounds in which to study Hmt1p function. We now demonstrate that the catalytically active form of Hmt1p is required for its activity in vivo. Amino acid changes in the putative Hmt1p S-adenosyl-L-methionine-binding site were generated and shown to be unable to catalyze methylation of Np13p in vitro and in vivo or to restore growth to strains that require HMT1. In addition these mutations affect nucleocytoplasmic transport of Np13p. A cold- sensitive mutant of Hmt1p was generated and showed reduced methylation of Np13p, but not of other substrates, at 14 °C. These results define new aspects of Hmt1 and reveal the importance of its activity in vivo.
Does differential receptor distribution underlie variable responses to a neuropeptide in the lobster cardiac system?
Date: 2021-08-02
Creator: Audrey J. Muscato, Patrick Walsh, Sovannarath Pong, Alixander Pupo, Roni J., Gross, Andrew E. Christie, J. Joe Hull, Patsy S. Dickinson
Access: Open access
- Central pattern generators produce rhythmic behaviors independently of sensory input; however, their outputs can be modulated by neuropeptides, thereby allowing for functional flexibility. We investigated the effects of C-type allatostatins (AST-C) on the cardiac ganglion (CG), which is the central pattern generator that controls the heart of the American lobster, Homarus americanus, to identify the biological mechanism underlying the significant variability in individual responses to AST-C. We proposed that the presence of multiple receptors, and thus differential receptor distribution, was at least partly responsible for this observed variability. Using transcriptome mining and PCR-based cloning, we identified four AST-C receptors (ASTCRs) in the CG; we then characterized their cellular localization, binding potential, and functional activation. Only two of the four receptors, ASTCR1 and ASTCR2, were fully functional GPCRs that targeted to the cell surface and were activated by AST-C peptides in our insect cell expression system. All four, however, were amplified from CG cDNAs. Following the confirmation of ASTCR expression, we used physiological and bioinformatic techniques to correlate receptor expression with cardiac responses to AST-C across individuals. Expression of ASTCR1 in the CG showed a negative correlation with increasing contraction amplitude in response to AST-C perfusion through the lobster heart, suggesting that the differential expression of ASTCRs within the CG is partly responsible for the specific physiological response to AST-C exhibited by a given individual lobster.
The capacity to act in trans varies among drosophila enhancers
Date: 2016-05-01
Creator: Amanda J. Blick, Ilana Mayer-Hirshfeld, Beatriz R. Malibiran, Matthew A. Cooper, Pieter A., Martino, Justine E. Johnson, Jack R. Bateman
Access: Open access
- The interphase nucleus is organized such that genomic segments interact in cis, on the same chromosome, and in trans, between different chromosomes. In Drosophila and other Dipterans, extensive interactions are observed between homologous chromosomes, which can permit enhancers and promoters to communicate in trans. Enhancer action in trans has been observed for a handful of genes in Drosophila, but it is as yet unclear whether this is a general property of all enhancers or specific to a few. Here, we test a collection of well-characterized enhancers for the capacity to act in trans. Specifically, we tested 18 enhancers that are active in either the eye or wing disc of third instar Drosophila larvae and, using two different assays, found evidence that each enhancer can act in trans. However, the degree to which trans-action was supported varied greatly between enhancers. Quantitative analysis of enhancer activity supports a model wherein an enhancer’s strength of transcriptional activation is a major determinant of its ability to act in trans, but that additional factors may also contribute to an enhancer’s trans-activity. In sum, our data suggest that a capacity to activate a promoter on a paired chromosome is common among Drosophila enhancers.
Three members of a peptide family are differentially distributed and elicit differential state-dependent responses in a pattern generator-effector system
Date: 2018-05-01
Creator: Patsy S. Dickinson, Matthew K. Armstrong, Evyn S. Dickinson, Rebecca Fernandez, Alexandra, Miller, Sovannarath Pong, Brian W. Powers, Alixander Pupo-Wiss, Meredith E. Stanhope, Patrick J. Walsh, Teerawat Wiwatpanit, Andrew E. Christie
Access: Open access
- C-type allatostatins (AST-Cs) are pleiotropic neuropeptides that are broadly conserved within arthropods; the presence of three AST-C isoforms, encoded by paralog genes, is common. However, these peptides are hypothesized to act through a single receptor, thereby exerting similar bioactivities within each species. We investigated this hypothesis in the American lobster, Homarus americanus, mapping the distributions of AST-C isoforms within relevant regions of the nervous system and digestive tract, and comparing their modulatory influences on the cardiac neuromuscular system. Immunohistochemistry showed that in the pericardial organ, a neuroendocrine release site, AST-C I and/or III and AST-C II are contained within distinct populations of release terminals. Moreover, AST-C I/III-like immunoreactivity was seen in midgut epithelial endocrine cells and the cardiac ganglion (CG), whereas AST-C II-like immunoreactivity was not seen in these tissues. These data suggest that AST-C I and/or III can modulate the CG both locally and hormonally; AST-C II likely acts on the CG solely as a hormonal modulator. Physiological studies demonstrated that all three AST-C isoforms can exert differential effects, including both increases and decreases, on contraction amplitude and frequency when perfused through the heart. However, in contrast to many state-dependent modulatory changes, the changes in contraction amplitude and frequency elicited by the AST-Cs were not functions of the baseline parameters. The responses to AST-C I and III, neither of which is COOH-terminally amidated, are more similar to one another than they are to the responses elicited by AST-C II, which is COOH-terminally amidated. These results suggest that the three AST-C isoforms are differentially distributed in the lobster nervous system/midgut and can elicit distinct behaviors from the cardiac neuromuscular system, with particular structural features, e.g., COOH-terminal amidation, likely important in determining the effects of the peptides. NEW & NOTEWORTHY Multiple isoforms of many peptides exert similar effects on neural circuits. In this study we show that each of the three isoforms of C-type allatostatin (AST-C) can exert differential effects, including both increases and decreases in contraction amplitude and frequency, on the lobster cardiac neuromuscular system. The distribution of effects elicited by the nonamidated isoforms AST-C I and III are more similar to one another than to the effects of the amidated AST-C II.