Explore the vast range of titles available.

Injury to the adult mammalian central nervous system induces compensatory plasticity of spared axons – referred to as collateral axon sprouting – that can facilitate neural recovery. The contribution of reactive astrocytes to axon sprouting remains elusive. Here, we sought to investigate the role of axon degeneration-reactive astrocytes in the regulation of collateral axon sprouting that occurs in the mouse spinal cord after unilateral photothrombotic stroke of the primary motor cortex. We identified astrocytic leucine zipper-bearing kinase (LZK) as a positive regulator of astrocyte reactivity to corticospinal axon degeneration. Remarkably, genetic stimulation of astrocyte reactivity, via LZK overexpression in adult astrocytes, enhanced corticospinal axon sprouting. LZK promoted the production of astrocyte-derived ciliary neurotrophic factor (CNTF) that likely enhanced axon growth in mice with astrocytic LZK overexpression after injury. Our finding that LZK-dependent stimulation of astrocyte reactivity promotes corticospinal axon sprouting highlights the potential of engineering astrocytes to support injury-induced axon plasticity for neural repair.

When the Great Smoky Mountains National Park (GRSM) was established in 1931, complete fire suppression was the fire management philosophy and goal in all national parks and forests across the country. Debris and undergrowth was cleared, fire breaks and manways were created, and thousands of fire towers were constructed. The young men of the Civilian Conservation Corps (CCC) provided much of the manpower to complete these tasks, and the group's signature rustic style left its mark on structures throughout the park. Ten towers and nine lookout cabins were built in GRSM between 1934 and 1939, and these sites were manned by lookouts during the two annual fire seasons for decades. The lookout jobs were isolated positions that required the patience to watch the forests daily from sunrise to sunset and the agility to be on alert at a moment's notice during a lightning storm. In the 1970s, fire management techniques and approaches to fire patrol changed, and the fire towers in GRSM were abandoned. Over the next decade, all but four of the towers and one of the cabins were removed from the park. This thesis acknowledges the importance of the utilitarian structures themselves and cultural history they represent and takes into consideration the ever-changing preservation ethic of the National Park Service (NPS). NPS has revised their position from removing towers to avoid the stewardship burden of these historic properties to actively pursuing a National Register listing for all extant towers and lookout cabins within its boundaries. This thesis compiles the evidence for such a pursuit while exploring the cultural and architectural significance of these structures.