Showing 31 - 40 of 106 Items
Differential gene expression during compensatory plasticity in the prothoracic ganglion of the cricket, Gryllus bimaculatus Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2020-01-01
Creator: Felicia F. Wang
Access: Access restricted to the Bowdoin Community
Interaction of stretch feedback and beat regularity in response to AMGSEFLamide in the heart of Homarus americanus
Date: 2020-01-01
Creator: William Allen
Access: Open access
- Central pattern generators (CPGs) are neural circuits whose component neurons possess intrinsic properties and synaptic connections that allow them to generate rhythmic motor outputs in the absence of descending inputs. The cardiac ganglion (CG) is a nine-cell CPG located in the American lobster, Homarus americanus. Stretch of the myocardium feeds back to the CG through mechano-sensitive dendrites and is thought to play a role in maintaining regularity in the beating pattern of the heart. The novel peptide AMGSEFLamide has been observed to induce irregular beating patterns when applied at high concentrations. This study investigated the interaction between stretch-related feedback and AMGSEFLamide modulation in generating irregular beating patterns in the whole heart of Homarus americanus. It was hypothesized that greater longitudinal stretch of the heart would result in greater regularity in the instantaneous beat frequency, based on previous findings that stretch-sensitive dendrites play a role in the regulation of the heartbeat. Furthermore, it was predicted that the elimination of stretch feedback via deafferentation of the heart would augment the irregularity induced by AMGSEFLamide. Data showed significantly increased irregularity in beating in response to 10-6 M AMGSEFLamide application. Longitudinal stretch did not reliably alter baseline variability in frequency, nor did it influence the modulatory effect of AMGSEFLamide. Deafferentation did not significantly alter baseline irregularity. Deafferented preparations did exhibit a trend of responding to AMGSEFLamide with a greater percent increase in irregularity compared to when afferents were intact, suggesting a potential role of stretch-stabilization in response to modulatory perturbations in the Homarus heart.
The role of behavioral diversity in determining the extent to which central pattern generators are modulated
Date: 2020-01-01
Creator: Jacob Salman Kazmi
Access: Open access
- Neuromodulation may be a substrate for the evolution of behavioral diversity. The extent to which a central pattern generator is modulated could serve as a mechanism that enables variability in motor output dependent on an organism’s need for behavioral flexibility. The pyloric circuit, a central pattern generator in the crustacean stomatogastric nervous system (STNS), stimulates contractions of foregut muscles in digestion. Since neuromodulation enables variation in the movements of pyloric muscles, more diverse feeding patterns should be correlated with a higher degree of STNS neuromodulation. Previous data have shown that Cancer borealis, an opportunistic feeder, is sensitive to a wider array of neuromodulators than Pugettia producta, a specialist feeder. The observed difference in modulatory capacity may be coincidental since these species are separated by phylogeny. We predict that the difference in modulatory capacity is a product of a differential need for variety in foregut muscle movements. This study examined two members of the same superfamily as P. producta, the opportunistically feeding snow crab (Chionoecetes opilio) and portly spider crab (Libinia emarginata). Using extracellular recording methods, the responses of isolated STNS preparations to various neuromodulators were measured. Initial qualitative results indicate that the STNS of C. opilio is sensitive to all of these neuromodulators. Additionally, previous data on the neuromodulatory capacity of L. emarginata was supported through similar electrophysiological analysis of the isolated STNS. As a first step in determining the mechanism of differential sensitivity between species, tissue-specific transcriptomes were generated and mined for neuromodulators.
The Role of the Nitric Oxide Negative Feedback Loop in the Stability of the Lobster Cardiac Ganglion Homarus americanus Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2020-01-01
Creator: Marie Marjorie Bergsund
Access: Access restricted to the Bowdoin Community
The effect of early life adversity on basolateral amygdala projections to the prefrontal cortex in male and female rats during development Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2023-01-01
Creator: Khushali N Patel
Access: Access restricted to the Bowdoin Community
Early life adversity induces sex-specific behavioral changes and does not alter precocial neural recruitment in response to basolateral amygdala stimulation Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2024-01-01
Creator: Zackery D. Reynolds
Access: Access restricted to the Bowdoin Community
Modulation of Responses to Phasic stretches by Neuromodulators GYS and SGRN in the Cardiac Central Pattern Generator of the American Lobster, H. americanus Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2016-05-01
Creator: Michael M Kang
Access: Access restricted to the Bowdoin Community
An unbiased glimpse into the sex-specific effects of ketamine treatment on rats who have experienced early life adversity. Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2023-01-01
Creator: Lucia Marie O'Sullivan
Access: Access restricted to the Bowdoin Community
Genetic variation in the serotonin transporter gene influences ERP old/new effects during recognition memory
Date: 2015-11-01
Creator: Robert S. Ross, Paolo Medrano, Kaitlin Boyle, Andrew Smolen, Tim Curran, Erika Nyhus
Access: Open access
- Recognition memory is defined as the ability to recognize a previously encountered stimulus and has been associated with spatially and temporally distinct event-related potentials (ERPs). Allelic variations of the serotonin transporter gene (SLC6A4) have recently been shown to impact memory performance. Common variants of the serotonin transporter-linked polymorphic region (5HTTLPR) of the SLC6A4 gene result in long (l) and short (s) allelic variants with carriers of the s allele having lowered transcriptional efficiency. Thus, the current study examines the effects polymorphisms of the SLC6A4 gene have on performance and ERP amplitudes commonly associated with recognition memory. Electroencephalogram (EEG), genetic, and behavioral data were collected from sixty participants as they performed an item and source memory recognition task. In both tasks, participants studied and encoded 200 words, which were then mixed with 200 new words during retrieval. Participants were monitored with EEG during the retrieval portion of each memory task. EEG electrodes were grouped into four ROIs, left anterior superior, right anterior superior, left posterior superior, and right posterior superior. ERP mean amplitudes during hits in the item and source memory task were compared to correctly recognizing new items (correct rejections). Results show that s-carriers have decreased mean hit amplitudes in both the right anterior superior ROI 1000-1500. ms post stimulus during the source memory task and the left anterior superior ROI 300-500. ms post stimulus during the item memory task. These results suggest that individual differences due to genetic variation of the serotonin transporter gene influences recognition memory. © 2015 Elsevier Ltd.
An isochromosome confers drug resistance in vivo by amplification of two genes, ERG11 and TAC1
Date: 2008-05-01
Creator: Anna Selmecki, Maryam Gerami-Nejad, Carsten Paulson, Anja Forche, Judith, Berman
Access: Open access
- Acquired azole resistance is a serious clinical problem that is often associated with the appearance of aneuploidy and, in particular, with the formation of an isochromosome [i(5L)] in the fungal opportunist Candida albicans. Here we exploited a series of isolates from an individual patient during the rapid acquisition of fluconazole resistance (FluR). Comparative genome hybridization arrays revealed that the presence of two extra copies of Chr5L, on the isochromosome, conferred increased FluR and that partial truncation of Chr5L reduced FluR. In vitro analysis of the strains by telomere-mediated truncations and by gene deletion assessed the contribution of all Chr5L genes and of four specific genes. Importantly, ERG11 (encoding the drug target) and a hyperactive allele of TAC1 (encoding a transcriptional regulator of drug efflux pumps) made independent, additive contributions to FluR in a gene copy number-dependent manner that was not different from the contributions of the entire Chr5L arm. Thus, the major mechanism by which i(5L) formation causes increased azole resistance is by amplifying two genes: ERG11 and TAC1. © 2008 The Authors.