A murine model of aging-related neurodegeneration caused by a defect in DNA repair

Thesis (M.A.)--Boston UniversityERCC1 is a DNA repair protein that forms a heterodimer with XPF. The resultant dimer is active in multiple systems of DNA repair. Mutations in this repair mechanism result in progeroid syndromes, such as Xeroderma Pigmentosum. These syndromes present with progressive neurodegeneration and are modeled by deletion or transgenic knock down of the ERCC1 gene in mice. Global knockouts and Ercc1-/Δ mice, in which only 5% of the normal compliment of ERCC1 is expressed, have been studied in order to elucidate the cause of the neural pathology. These models, similar to patients, often show neurodegeneration, but it was unclear whether this loss was due to a primary neuronal dysfunction or that of supporting glial cells. L7Cre;Ercc1-/cond mice, in which Ercc1-XPF is deleted only in the neurons of the forebrain, are used in this study to determine the cell autonomous impact of DNA repair deficiency on neurons. Oxidative damage is thought to contribute to the progression of aging- related neurodenerative disease, such as AD and PD, and DNA could be a prominent target. The hypothesis that pathology in L7Ercc1-/cond mice is similar to that of neurodegenerative disease states was supported in many instances. The decrease in weight seen in mutant mice is also seen in patients with both AD and PD. The degeneration in the hippocampus and alteration in DG proliferation is consistent with that often seen in AD, as is cortical degeneration and thinning of the corpus callosum. Gliosis in the striatum is seen in many PD patients and could be contributing to the ambulation impairment seen in the mutant mice. These data suggest a link between DNA repair deficiency and neurodegeneration stemming from multiple origins. Elucidating the impact of unrepaired endogenous DNA damage on neurons using this genetic tool may allow for the development of future interventions to slow aging-related neurodegeneration, as well as the progression of AD and PD

Partner Control and Environmental Fouling in the Crayfish-Branchiobdellid Symbiosis

Previous research found that crayfish (Cambarus chasmodactylus) may be engaged in a cleaning mutualism with ectosymbiotic worms (Annelida: Branchiobdellidae), yet mechanisms for symbiosis establishment and maintenance remain unknown. In addition, it is unclear why a co-occurring crayfish species (Orconectes cristavarius) hosts almost no worms. The research in this thesis seeks to answer some of these questions by incorporating field surveys with laboratory and field experiments to assess the influence of both partner control behaviors and environmental fouling on the interaction between crayfish and branchiobdellid worms

Texas Journal on Civil Liberties & Civil Rights

Biannual journal containing articles, notes, and other analyses of law and legal cases related to civil liberties and rights in the United States. This issue covers disability rights advocacy, new international politics of disability, keeping stalkers at bay in Texas, and school district policies restricting educationally disruptive student speech

A Practical Guide for Managing Interdisciplinary Teams: Lessons Learned from Coupled Natural and Human Systems Research

Interdisciplinary team science is essential to address complex socio-environmental questions, but it also presents unique challenges. The scientific literature identifies best practices for high-level processes in team science, e.g., leadership and team building, but provides less guidance about practical, day-to-day strategies to support teamwork, e.g., translating jargon across disciplines, sharing and transforming data, and coordinating diverse and geographically distributed researchers. This article offers a case study of an interdisciplinary socio-environmental research project to derive insight to support team science implementation. We evaluate the project’s inner workings using a framework derived from the growing body of literature for team science best practices, and derive insights into how best to apply team science principles to interdisciplinary research. We find that two of the most useful areas for proactive planning and coordinated leadership are data management and co-authorship. By providing guidance for project implementation focused on these areas, we contribute a pragmatic, detail-oriented perspective on team science in an effort to support similar projects

Training macrosystems scientists requires both interpersonal and technical skills

Macrosystems science strives to integrate patterns and processes that span regional to continental scales. The scope of such research often necessitates the involvement of large interdisciplinary and/or multi-institutional teams composed of scientists across a range of career stages, a diversity that requires researchers to hone both technical and interpersonal skills. We surveyed participants in macrosystems projects funded by the US National Science Foundation to assess the perceived importance of different skills needed in their research, as well as the types of training they received. Survey results revealed a mismatch between the skills participants perceive as important and the training they received, particularly for interpersonal and management skills. We highlight lessons learned from macrosystems training case studies, explore avenues for further improvement of undergraduate and graduate education, and discuss other training opportunities for macrosystems scientists. Given the trend toward interdisciplinary research beyond the macrosystems community, these insights are broadly applicable for scientists involved in diverse, collaborative projects.https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/fee.228

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Neuroinflammation and circuitry changes in the dorsal raphe nucleus with depressive phenotype after spinal cord injury

Major Depressive Disorder (MDD) is attributed to an imbalance of the serotonin system that includes neurons of the dorsal raphe nucleus (DRN) involved in modulation of affective features such as attention, working memory and emotional control. In addition to motor, sensory, and autonomic dysfunction, patients with spinal cord injury (SCI) are at three-times the risk for MDD compared to the general population. Inflammation is implicated in MDD pathology as elevated levels of pro-inflammatory cytokines (TNF[alpha] and Il-6) frequently are detected in the serum of MDD patients and intracerebral adminstration of TNF[alpha] can elicit depressive-like behaviors in rodents. In a rat model of thoracic-contusion injury we correlated elevated DRN levels of TNF[alpha] with depressive phenotype at 5 weeks post-SCI. Chronic peripheral inhibition of soluble TNF[alpha] by administration of XPro1595 (a dominant-negative inhibitor) resulted in increase in the incidence of depression, yet central intracerebroventricular (i.c.v.) administration had no effect on incidence. These results suggest that modulation of additional components of neuroinflammation may be necessary to offset depressive phenotype after SCI. Whole cell patch clamp electrophysiology revealed an increase in excitability of DRN serotonergic neurons of post-SCI non-depressed vs. depressed mice, based on intrinsic membrane properties. No significant alterations in excitatory/inhibitory input to GABAergic or serotonergic neurons were found, though both cell types demonstrated an increase in action potential bursting after depolarizing current injection, suggesting a potential role for ion channel dysregulation in multiple neuronal types with post-SCI depression. Our findings suggest that intrinsic neuronal changes in excitability may contribute to decreased serotonergic output and the subsequent development of SCI-depression, providing beneficial insight in identifying future therapeutic targets.Ph.D., Neuroscience -- Drexel University, 201

Dynamic Changes in Local Protein Synthetic Machinery in Regenerating Central Nervous System Axons after Spinal Cord Injury

Intra-axonal localization of mRNAs and protein synthesis machinery (PSM) endows neurons with the capacity to generate proteins locally, allowing precise spatiotemporal regulation of the axonal response to extracellular stimuli. A number of studies suggest that this local translation is a promising target to enhance the regenerative capacity of damaged axons. Using a model of central nervous system (CNS) axons regenerating into intraspinal peripheral nerve grafts (PNGs) we established that adult regenerating CNS axons contain several different mRNAs and protein synthetic machinery (PSM) components in vivo. After lower thoracic level spinal cord transection, ascending sensory axons regenerate into intraspinal PNGs but axon growth is stalled when they reach the distal end of the PNG (3 versus 7 weeks after grafting, resp.). By immunofluorescence with optical sectioning of axons by confocal microscopy, the total and phosphorylated forms of PSMs are significantly lower in stalled compared with actively regenerating axons. Reinjury of these stalled axons increased axonal localization of the PSM proteins, indicative of possible priming for a subcellular response to axotomy. These results suggest that axons downregulate protein synthetic capacity as they cease growing, yet they retain the ability to upregulate PSM after a second injury

Why Has Breast Cancer Screening Failed to Decrease the Incidence of de Novo Stage IV Disease?

Background: Despite screening mammography, the incidence of Stage IV breast cancer (BC) at diagnosis has not decreased over the past four decades. We previously found that many BCs are small due to favorable biology rather than early detection. This study compared the biology of Stage IV cancers with that of small cancers typically found by screening. Methods: Trends in the incidence of localized, regional, and distant female BC were compared using SEER*Stat. The National Cancer Database (NCDB) was then queried for invasive cancers from 2010 to 2015, and patient/disease variables were compared across stages. Biological variables including estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (Her2), grade, and lymphovascular invasion were sorted into 48 combinations, from which three biological subtypes emerged: indolent, intermediate, and aggressive. The distributions of the subtypes were compared across disease stages. Multivariable regression assessed the association between Stage IV disease and biology. Results: SEER*Stat confirmed that the incidence of distant BC increased between 1973 and 2015 (annual percent change [APC] = 0.46). NCDB data on roughly 993,000 individuals showed that Stage IV disease at presentation is more common in young, black, uninsured women with low income/education and large, biologically aggressive tumors. The distribution of tumor biology varied by stage, with Stage IV disease including 37.6% aggressive and 6.0% indolent tumors, versus sub-centimeter Stage I disease that included 5.1% aggressive and 40.6% indolent tumors (p < 0.001). The odds of Stage IV disease presentation more than tripled for patients with aggressive tumors (OR3.2, 95% CI 3.0–3.5). Conclusions: Stage I and Stage IV breast cancers represent very different populations of biologic tumor types. This may explain why the incidence of Stage IV cancer has not decreased with screening