Showing 401 - 410 of 681 Items

Mitochondrial adaptation in the green crab hybrid zone of the Gulf of Maine

Date: 2024-01-01

Creator: Jared Lynch

Access: Open access

The mitochondrial genome has historically been relegated to a neutral genetic marker, but new evidence suggests mitochondrial DNA to be a target for adaptation to environmental stress. The invasive European green crab (Carcinus maenas) exemplifies this in the Gulf of Maine’s hybrid zone, where interbreeding populations exhibit thermal tolerances influenced by mitochondrial genotype. To better understand the mechanism behind this phenomenon, the effect of mitochondrial genotype on mitochondrial activity was tested by measuring mtDNA copy number (mtCN) and the activity of complex I, II, and IV of the electron transport system via high-resolution respirometry. Mitochondria isolated from frozen heart tissue were measured at three temperature points—5°C, 25°C, and 37°C—to represent thermal stresses and a control. It was predicted that cold-adapted haplogroups would exhibit both higher mtCN and increased activity for each complex, either across all temperatures or exclusively at 5°C compared to a warm-adapted haplogroup. Initial comparisons of mitochondria from fresh and frozen tissue at 25°C found lower activity for complex II and IV in frozen extracts, but they continued to be used for convenience. No differences were observed across haplogroups for mtCN or high-resolution respirometry, suggesting that mitochondrial activity does not underlie differences in thermal tolerance. However, temperature greatly influenced activity measurements with complex II and IV exhibiting the highest rates at 37°C while complex I exhibited optimal activity at 25°C. This study represents the first of its kind for C. maenas, providing a foundation for future experiments to continue exploring mitochondria in the context of adaptive evolution.


Miniature of Prescriptions of Identity: Jewish identities defined, questioned, and remembered in Early Modern Spain and early colonial America
Prescriptions of Identity: Jewish identities defined, questioned, and remembered in Early Modern Spain and early colonial America
This record is embargoed.
    • Embargo End Date: 2029-05-16

    Date: 2024-01-01

    Creator: Juliana Keyes Vandermark

    Access: Embargoed



      Miniature of Ionic Liquids as Additives for Metal-Organic Framework Crystallization
      Ionic Liquids as Additives for Metal-Organic Framework Crystallization
      Access to this record is restricted to members of the Bowdoin community. Log in here to view.
      • Restriction End Date: 2027-06-01

        Date: 2024-01-01

        Creator: Oliver Wang

        Access: Access restricted to the Bowdoin Community



          Miniature of Distance Based Pre-clustering for Deep Time-Series Forecasting: A Data Selection Approach
          Distance Based Pre-clustering for Deep Time-Series Forecasting: A Data Selection Approach
          This record is embargoed.
            • Embargo End Date: 2025-05-16

            Date: 2024-01-01

            Creator: Leopold Felix Spieler

            Access: Embargoed



              Virtual Reality Accessibility with Predictive Trails

              Date: 2020-01-01

              Creator: Dani Paul Hove

              Access: Open access

              Comfortable locomotion in VR is an evolving problem. Given the high probability of vestibular-visual disconnect, and subsequent simulator sickness, new users face an uphill battle in adjusting to the technology. While natural locomotion offers the least chance of simulator sickness, the space, economic and accessibility barriers to it limit its effectiveness for a wider audience. Software-enabled locomotion circumvents much of these barriers, but has the greatest need for simulator sickness mitigation. This is especially true for standing VR experiences, where sex-biased differences in mitigation effectiveness are amplified (postural instability due to vection disproportionately affects women). Predictive trails were developed as a shareable Unity module in order to combat some of the gaps in current mitigation methods. Predictive trails use navigation meshes and path finding to plot the user’s available path according to their direction of vection. Some of the more prominent software methods each face distinct problems. Vignetting, while largely effective, restricts user field-of-vision (FoV), which in prolonged scenarios, has been shown to disproportionately lower women’s navigational ability. Virtual noses, while effective without introducing FoV restrictions, requires commercial licensing for use. Early testing of predictive trails proved effective on the principal investigator, but a wider user study - while approved - was unable to be carried out due to circumstances of the global health crisis. While the user study was planned around a seated experience, further study is required into the respective sex-biased effect on a standing VR experience. Additional investigation into performance is also required.


              Miniature of The Conspiracy of Balkis: Translating Monique Wittig's Feminist Novel "Les Guérillères"
              The Conspiracy of Balkis: Translating Monique Wittig's Feminist Novel "Les Guérillères"
              Access to this record is restricted to members of the Bowdoin community. Log in here to view.

                  Date: 2025-01-01

                  Creator: Alyssa Nicole Bommer

                  Access: Access restricted to the Bowdoin Community



                    Miniature of Freezing temperatures drive functional trait clustering more than habitat structure in eelgrass communities in the Gulf of Maine
                    Freezing temperatures drive functional trait clustering more than habitat structure in eelgrass communities in the Gulf of Maine
                    This record is embargoed.
                      • Embargo End Date: 2026-05-18

                      Date: 2023-01-01

                      Creator: Bridget Marjorie Patterson

                      Access: Embargoed



                        Miniature of Shining a Light on ‘Like Dissolves Like’: Effects of Cocrystals and Excipients on the Dissolution Performance of Mefenamic Acid
                        Shining a Light on ‘Like Dissolves Like’: Effects of Cocrystals and Excipients on the Dissolution Performance of Mefenamic Acid
                        Access to this record is restricted to members of the Bowdoin community. Log in here to view.

                            Date: 2025-01-01

                            Creator: Runqin Chen

                            Access: Access restricted to the Bowdoin Community



                              Co-modulation of the Pyloric Circuit in the Stomatogastric Nervous System of the Cancer Borealis

                              Date: 2025-01-01

                              Creator: Margaret Broaddus

                              Access: Open access

                              ABSTRACT CHAPTER I: All nervous systems are influenced by circulating hormones, which can modulate neural circuits to produce different outputs from the same set of neurons. Invertebrate models, particularly crustaceans, serve as excellent models for studying neuromodulation because they contain neural circuits that continue to generate fictive activity when dissected out of the animal. The stomatogastric nervous system (STNS) of the Jonah Crab (Cancer borealis) has long been used to study neuromodulation due to its well-characterized circuits. Even in such a compact neural network, little is known about how these circuits are modulated, and this remains a question in all animals, particularly in humans. Here we investigated the modulation of the pyloric circuit by applying bulk hemolymph to the dissected STNS preparation. The hemolymph contains all of the circulating modulators, some of which have known effects on the pyloric rhythm (though many are still unknown). Interestingly, when hemolymph is applied to the isolated STNS, the pyloric rhythm is suppressed. This is surprising given that in vivo the STNS is continually exposed to hemolymph (the STG is situated within an artery, and thus, exposed to circulating hemolymph) and the pyloric rhythm is constitutively active. Therefore, I hypothesized that there are synaptically released neurotransmitters that excite the pyloric rhythm. To test this hypothesis, we applied three different excitatory modulators – proctolin, serotonin, and oxotremorine – separately in the presence of hemolymph. I found that proctolin and oxotremorine restore the pyloric rhythm in the presence of hemolymph. However, serotonin did not consistently overcome the inhibition of hemolymph. ABSTRACT CHAPTER II: A plethora of work has begun to identify how endogenous neural and hormonal modulators interact to influence the pyloric network. Here we examined the modulation of the stomatogastric nervous system (STNS) via two excitatory endogenous modulators CabTRP Ia and corazonin. CabTRP Ia and corazonin both excite the pyloric rhythm, but in distinct ways. Preliminary data by Nusbaum and Christie from 2003 suggested that an initial corazonin application gated a stronger response to subsequent CabTRP Ia when compared the inverse application of these neuromodulators. We sought to validate this gating phenomenon, but found no significant difference between the effects of the first and second applications of CabTRP Ia. Given that these animals are wild caught and surviving in a changing oceanic environment, it is possible that this modulatory effect in the Jonah Crab has changed over the last few decades due to environmentally driven shifts in receptor expression and channel conductances.


                              Miniature of Redefining Warfare: The Role of International Humanitarian Law in Governing Cyber Conflict
                              Redefining Warfare: The Role of International Humanitarian Law in Governing Cyber Conflict
                              Access to this record is restricted to members of the Bowdoin community. Log in here to view.

                                  Date: 2025-01-01

                                  Creator: Carina Lim-Huang

                                  Access: Access restricted to the Bowdoin Community