Showing 5491 - 5500 of 5709 Items
De novo assembly of a transcriptome for the cricket Gryllus bimaculatus prothoracic ganglion: An invertebrate model for investigating adult central nervous system compensatory plasticity
Date: 2018-07-01
Creator: Harrison P. Fisher, Micah G. Pascual, Sylvia I. Jimenez, David A. Michaelson, Colby T., Joncas, Eleanor D. Quenzer, Andrew E. Christie, Hadley W. Horch
Access: Open access
- The auditory system of the cricket, Gryllus bimaculatus, demonstrates an unusual amount of anatomical plasticity in response to injury, even in adults. Unilateral removal of the ear causes deafferented auditory neurons in the prothoracic ganglion to sprout dendrites across the midline, a boundary they typically respect, and become synaptically connected to the auditory afferents of the contralateral ear. The molecular basis of this sprouting and novel synaptogenesis in the adult is not understood. We hypothesize that well-conserved developmental guidance cues may recapitulate their guidance functions in the adult in order to facilitate this compensatory growth. As a first step in testing this hypothesis, we have generated a de novo assembly of a prothoracic ganglion transcriptome derived from control and deafferented adult individuals. We have mined this transcriptome for orthologues of guidance molecules from four well-conserved signaling families: Slit, Netrin, Ephrin, and Semaphorin. Here we report that transcripts encoding putative orthologues of most of the candidate developmental ligands and receptors from these signaling families were present in the assembly, indicating expression in the adult G. bimaculatus prothoracic ganglion.
Albert Camus: An Ethical Politics in the Absurd World Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2015-05-01
Creator: Stephanie Lane
Access: Access restricted to the Bowdoin Community
Distinct or shared actions of peptide family isoforms: I. Peptidespecific actions of pyrokinins in the lobster cardiac neuromuscular system
Date: 2015-09-01
Creator: Patsy S. Dickinson, Anirudh Sreekrishnan, Molly A. Kwiatkowski, Andrew E. Christie
Access: Open access
- Although the crustacean heart is modulated by a large number of peptides and amines, few of these molecules have been localized to the cardiac ganglion itself; most appear to reach the cardiac ganglion only by hormonal routes. Immunohistochemistry in the American lobster Homarus americanus indicates that pyrokinins are present not only in neuroendocrine organs ( pericardial organ and sinus gland), but also in the cardiac ganglion itself, where pyrokinin-positive terminals were found in the pacemaker cell region, as well as surrounding the motor neurons. Surprisingly, the single pyrokinin peptide identified from H. americanus, FSPRLamide, which consists solely of the conserved FXPRLamide residues that characterize pyrokinins, did not alter the activity of the cardiac neuromuscular system. However, a pyrokinin from the shrimp Litopenaeus vannamei [ADFAFNPRLamide, also known as Penaeus vannamei pyrokinin 2 (PevPK2)] increased both the frequency and amplitude of heart contractions when perfused through the isolated whole heart. None of the other crustacean pyrokinins tested (another from L. vannamei and two from the crab Cancer borealis) had any effect on the lobster heart. Similarly, altering the PevPK2 sequence either by truncation or by the substitution of single amino acids resulted in much lower or no activity in all cases; only the conservative substitution of serine for alanine at position 1 resulted in any activity on the heart. Thus, in contrast to other systems (cockroach and crab) in which all tested pyrokinins elicit similar bioactivities, activation of the pyrokinin receptor in the lobster heart appears to be highly isoform specific.
Maximally rotating supermassive stars at the onset of collapse: Effects of gas pressure
Date: 2019-09-21
Creator: Kenneth A. Dennison, Thomas W. Baumgarte, Stuart L. Shapiro
Access: Open access
- The ‘direct collapse’ scenario has emerged as a promising evolutionary track for the formation of supermassive black holes early in the Universe. In an idealized version of such a scenario, a uniformly rotating supermassive star spinning at the mass-shedding (Keplerian) limit collapses gravitationally after it reaches a critical configuration. Under the assumption that the gas is dominated by radiation pressure, this critical configuration is characterized by unique values of the dimensionless parameters J/M2 and Rp/M, where J is the angular momentum, Rp the polar radius, and M the mass. Motivated by a previous perturbative treatment, we adopt a fully non-linear approach to evaluate the effects of gas pressure on these dimensionless parameters for a large range of masses. We find that gas pressure has a significant effect on the critical configuration even for stellar masses as large as M ~ 106 MO. We also calibrate two approximate treatments of the gas pressure perturbation in a comparison with the exact treatment, and find that one commonly used approximation in particular results in increasing deviations from the exact treatment as the mass decreases, and the effects of gas pressure increase. The other approximation, however, proves to be quite robust for all masses M >~ 104 MO.
Metabolic glycan inhibitors interfere with glycoprotein biosynthesis in the human pathogen Ralstonia pickettii Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2021-01-01
Creator: Melissa G. Demczak
Access: Access restricted to the Bowdoin Community
Localizing Resistance: How Southern Women Locate Sexual and Bodily Autonomy and Strategically Resist the Institutions Aiming to Shape Them
Date: 2021-01-01
Creator: Gillian Raley
Access: Open access
- This paper analyzes the methods of resistance enacted by women-identifying people in Mississippi against the institutions seeking to police how they understand their own sexuality and bodily autonomy. This analysis draws upon a series of in-depth, semi-structured interviews conducted in the summer of 2020 focused on construction of community, intersectional identity, relationship with the body, and what inputs frame how women in Mississippi understand sex. This project puts these interviews in conversation with literature from a variety of subfields, including resistance studies, the Sociology of the South, and the Sociology of sexuality, all of which help bring the argument behind these data to light. Resistance looks different in different eras, and generally scholars like to analyze resistance as collective action, collective voice, collective struggle. These data instead argue that strategic, individualized resistance is just as vital to marginalized bodies, particularly when explosive action is not possible. Studying strategies of resistance that lurk beneath the surface not only expands what we now see as “radical,” but it also lends insight into where lasting change can begin.