Genetic and morphological variation of butterflies in relict habitats

Habitat fragmentation and loss are leading threats to global biodiversity and can alter patterns of dispersal, population dynamics, and genetics with implications for long-term species persistence. Most habitat fragmentation research has focused on recently fragmented species that historically occupied interconnected habitat patches. We know comparatively little about how naturally fragmented species may respond to habitat loss. For these species, local habitat patch quality may influence the dynamics and genetics of populations more than the structure of the surrounding landscape (e.g., degree of isolation of suitable habitat). I examined aspects of the ecology and evolution of populations inhabiting fragmented landscapes, using two butterfly species representing relict populations that are 1) recently fragmented by anthropogenic activities (Mormon metalmark, Apodemia mormo), and 2) naturally fragmented (bog copper, Lycaena epixanthe). I assessed patterns of genetic (amplified fragment length polymorphism, AFLP) and flight-related morphological variation, and their relationship to measures of surrounding landscape structure and local habitat quality. Population genetic analysis of the anthropogenically fragmented Mormon metalmark revealed a high degree of spatial genetic structure, indicating limited gene flow, despite a small geographic scale (\u3c20 \u3ekm). Management of this endangered population should focus on increasing connectivity among the most isolated sub-populations and through urban areas. For the naturally fragmented bog copper, genetic diversity was explained by variables related to patch quality rather than landscape structure. Movement ability in the bog copper (inferred by flight morphology) appeared to depend on both local habitat conditions and the surrounding landscape. Also, using an AFLP-based genome scan approach, I identified signatures of selection in the bog copper associated with fine-scale landscape heterogeneity. My work on the bog copper highlights the importance of considering the effects of local habitat conditions, in addition to habitat isolation, for conservation of fragmented populations. Finally, I also reviewed the current literature (470 articles) to evaluate the quality of AFLP data used in ecological and evolutionary research. I discovered a pervasive lack of consistency and transparency in both the methods used to assess data reproducibility, and in the details of methodology presented. This work has identified an important publishing gap in molecular ecology research

Understanding the effects of hypoxia on spinal cord early myelinating oligodendrocytes in vitro

In the developing brain, pre-/early myelinating oligodendrocytes (EMOLs) are particularly vulnerable to hypoxia-ischaemia; however, much less is known about how this impacts spinal cord EMOLs. Indeed, in an in vivo mouse model of spinal muscular atrophy, myelinogenesis proceeds normally despite significantly reduced vascularisation of the developing spinal cord. Furthermore, even in the healthy spinal cord, perfusion is up to 60% lower in comparison to the brain. Together, these observations raise the possibility there are anatomically divergent susceptibilities of EMOLs to hypoxia-ischaemia. Thus, this thesis addressed the hypothesis that spinal cord EMOLs are relatively resistant to hypoxia-ischaemia and associated secondary consequences. To test our hypothesis, we used murine spinal cord mixed glial cultures, which we showed contain EMOLs (indicated by BCAS1 expression), astrocytes, and microglia, but lack neuronal cell bodies, making these suitable for modelling spinal cord white matter. The morphology of DAPI-stained nuclei was confirmed to be a useful indicator of cell survival. To examine the response of spinal cord EMOLs to hypoxia, cell cultures were subjected to chemical hypoxia for 5 or 24 hours using azide, or to oxygen deprivation for 24 hours. Five hours chemical hypoxia did not cause death of EMOLs (or astrocytes), whereas they failed to survive 24 hours treatment. Surprisingly, oxygen deprivation had little impact on survival, even when glucose was withdrawn, raising doubts about the efficacy of the method. Together, we conclude that spinal cord EMOLs are tolerant of short-term hypoxia. As neither chemically-induced hypoxia nor oxygen deprivation led to acidosis of the cell culture media, as would occur in the CNS, we next examined the impact of this secondary component of the hypoxic environment. Cells were maintained for 6 days at physiological pH or in increasingly acidic conditions. Reducing pH to 6.8 or lower led to a significant decrease in the densities of EMOLs. Surprisingly, the complete withdrawal of glucose (pyruvate and glutamine) did not compound this and had only a minor effect on cell survival at physiological pH after 6 days. This unexpected observation led us to ask whether our survival assay was sufficiently sensitive. We confirmed this with a lactate dehydrogenase release assay and by further challenging the cells with reintroduction of glucose or complete withdrawal of amino acids and vitamins. The unexpected survival of EMOLs, and also of astrocytes, in the absence of glucose led us to hypothesise that astrocyte energy reserves might sustain both astrocytes and EMOLs under exogenous energy substrate deprivation. To address this, we explored trans-cellular exchange routes and found EMOLs were dye-coupled to astrocytes by nanotube-like structures: a putative conduit for the transfer of energy substrates. Recently, it has been demonstrated that astrocytes can accumulate lipid droplets, the beta-oxidation of which could potentially provide fuel for cell survival in the absence of exogenous energy substrates. Therefore, we next looked for evidence of lipid droplets in these spinal cord-derived cell cultures and found that lipid droplets were abundant in astrocytes. Consistent with this, lipidomic analyses demonstrated a significant reduction in triglycerides (a lipid droplet-associated species) after 6 days of energy substrate deprivation in mixed glial cultures, but not EMOL-enriched cultures, compared to 5 mM glucose controls. In all, these data suggest that spinal cord EMOLs are relatively resilient to hypoxia-ischaemia as demonstrated by their tolerance of short-term hypoxia and exogenous energy substrate deprivation in this in vitro model. The disease-relevant implications remain to be examined and the source of lipid droplet substrates to be determined

The Camden African-American Heritage Project

This report is divided into six sections that present a history of African Americans in Camden, South Carolina from the perspective of historic preservation. The first three sections constitute the historical narrative, organized into three general time periods: the colonial period through the Civil War, emancipation and Reconstruction through the civil rights movement, and a short section on the recent past since about 1970. Within each of these sections, the report assesses political participation, economic life, the impact of war, education, religion, and the built environment. Section four offers a set of recommendations for how the information in this report can be used to encourage public education about black Camden and preservation of the city‘s African-American historic resources. The primary and secondary sources consulted in this study are listed in the bibliography in section five. The appendix in section six contains a map and database of black Camden in 1941, based on the treasure trove of information in the city directory of that year.https://scholarcommons.sc.edu/pubhist_books/1001/thumbnail.jp

Experimental effects of acute exercise in attenuating memory interference: Considerations by biological sex

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. Background and Objectives: The objective of this experiment was to evaluate the effects of acute exercise on memory interference and determine if this potential relationship is moderated by sex. Materials and Methods: A randomized controlled experiment was conducted (N = 40), involving young adult males (n = 20) and females (n = 20) completing two counterbalanced visits (exercise and no exercise). The exercise visit involved an acute (15 min), moderate-intensity bout of treadmill exercise, while the control visit involved a time-matched seated task. Memory interference, including both proactive interference and retroactive interference, involved the completion of a multi-trial memory task. Results: In a factorial ANOVA with the outcome being List B, there was a main effect for condition (F(1,38) = 5.75, P = 0.02, n2p = 0.13), but there was no main effect for sex (F(1,38) = 1.39, P = 0.24, n2p = 0.04) or sex by condition interaction (F(1,38) = 1.44, P = 0.23, n2p = 0.04). Conclusion: In conclusion, acute moderate-intensity exercise was effective in attenuating a proactive memory interference effect. This effect was not moderated by biological sex

Association of physical activity on memory interference: Boston Puerto Rican Health Study

Background: The objective of this study was to evaluate the association between habitual physical activity engagement on memory interference. The present analysis used cross-sectional data from the Boston Puerto Rican Health Study (n=1,241; mean age= 57.2; 72.1% female). Methods: Physical activity was evaluated via self-report. Memory interference was evaluated using a word-list paradigm. The memory task included learning a list of 16 words (List A; 5 trials), followed by a distractor list (List B), and then an immediate recall of List A. Proactive interference occurs when preceding stimuli (e.g., Trial 1 and Trial 5 of List A) interferes with performance on a subsequent stimuli (List B). Retroactive interference occurs when subsequent stimuli (List B) interferes with the recall of previously encoded stimuli (Trial 5). Results: For proactive interference, there was no association between physical activity and the difference between performance on List B and Trial 1 of List A (β=0.00001; P= 0.96). Similarly, for retroactive interference, there was no association between physical activity and the difference between the short delay recall and Trial 5 of List A (β=0.0002; P= 0.50). Conclusion: The present study did not observe an association between habitual physical activity on attenuating memory interference

Hypothesized mechanisms through which exercise may attenuate memory interference

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. In this paper we introduce a mechanistic model through which exercise may enhance episodic memory, specifically via attenuating proactive and retroactive memory interference. We discuss the various types of memory, different stages of memory function, review the mechanisms behind forgetting, and the mechanistic role of exercise in facilitating pattern separation (to attenuate memory interference)

Thermal status for different breeds of dairy cattle exposed to summer heat stress in a grazing environment [abstract]

Abstract only availableA study was conducted to investigate thermal balance of lactating dairy cattle managed in an intensive managed rotational grazing system. The farm was located at the University of Missouri Southwest Research Center in Vernon County, MO. Thirty six lactating dairy cows were blocked by parity, days in milk, milk production and breed. Cows were grouped by breed with 100% Holstein (H, n=8), 75%H:25% Jersey (J) (75H, n=5), 50%H:50%J (50H, n=8), 25%H:75%J (75J, n=7), and 100% J (J, n=8), and maintained on the same pastures from June 15 through August 1, 2006. Cows were rotated to paddocks to maintain ad libitum access to pasture. Ambient variables, including air temperature (Ta) and relative humidity, were measured continuously. Ranges of Ta and calculated THI were 12 to 38C and 55 to 87, respectively. Thermal balance was evaluated prior to morning (0500) and afternoon (1600) milkings by measuring rectal temperature (Tre) and respiration rate (RR) on 16 days throughout the study during periods of maximum and minimum heat stress. Breed groups had different body weights (p < 0.0001) ranging from 530 kg (H) to 378 (J). However, body weight was similar for 75J and 75H (460 kg versus 501 kg, respectively). Although body weights were different across breed, combined change in rectal temperature with Ta (r = 0.89) and THI (r = 0.92) was predictable (p < 0.0001). Change in Tre with increasing Ta and THI was slowest for J and 75J, and highest for H and 75H. Change in Tre was influenced more by breed more than body weight. Respiration rate was correlated with Ta (r = 0.88) and THI (r = 0.89) (p < 0.0001), with 75J being more responsive than 75H. These results suggest that breed selection can be used to improve thermal balance of cows in intensively managed rotational grazing systems.CAFNR On Campus Research Internshi