Kimberly A. Finnegan

Impaired axonal transport has been postulated to play a role in the pathophysiology of multiple neurodegenerative disorders. In this report, we describe the results of clinical and neuropathological studies in a family with an inherited form of motor neuron disease caused by mutation in the p150Glued subunit of dynactin, a microtubule motor protein essential for retrograde axonal transport. Affected family members had a distinct clinical phenotype characterized by early bilateral vocal fold paralysis affecting the adductor and abductor laryngeal muscles. They later experienced weakness and atrophy in the face, hands, and distal legs. The extremity involvement was greater in the hands than in the legs, and it had a particular predilection for the thenar muscles. No clinical or electrophysiological sensory abnormality existed; however, skin biopsy results showed morphological abnormalities of epidermal nerve fibers. An autopsy study of one patient showed motor neuron degeneration and axonal loss in the ventral horn of the spinal cord and hypoglossal nucleus of the medulla. Immunohistochemistry showed abnormal inclusions of dynactin and dynein in motor neurons. This mutation of dynactin, a ubiquitously expressed protein, causes a unique pattern of motor neuron degeneration that is associated with the accumulation of dynein and dynactin in neuronal inclusions.

Understanding the population dynamics of highly mobile, widely distributed, oceanic sharks, many of which are overexploited, is necessary to aid their conservation management. We investigated the global population genomics of tiger sharks (Galeocerdo cuvier), a circumglobally distributed, apex predator displaying remarkable behavioral versatility in its diet, habitat use (near coastal, coral reef, pelagic), and individual movement patterns (spatially resident to long-distance migrations). We genotyped 242 tiger sharks from 10 globally distributed locations at more than 2000 single nucleotide polymorphisms. Although this species often conducts massive distance migrations, the data show strong genetic differentiation at both neutral (FST = 0.125-0.144) and candidate outlier loci (FST = 0.570-0.761) between western Atlantic and Indo-Pacific sharks, suggesting the potential for adaptation to the environments specific to these oceanic regions. Within these regions, there was mixed support for population differentiation between northern and southern hemispheres in the western Atlantic, and none for structure within the Indian Ocean. Notably, the results demonstrate a low level of population differentiation of tiger sharks from the remote Hawaiian archipelago compared with sharks from the Indian Ocean (FST = 0.003-0.005, P < 0.01). Given concerns about biodiversity loss and marine ecosystem impacts caused by overfishing of oceanic sharks in the midst of rapid environmental change, our results suggest it imperative that international fishery management prioritize conservation of the evolutionary potential of the highly genetically differentiated Atlantic and Indo-Pacific populations of this unique apex predator. Furthermore, we suggest targeted management attention to tiger sharks in the Hawaiian archipelago based on a precautionary biodiversity conservation perspective.

Resolving the genetic connectivity of coral reef taxa is necessary to understand the community dynamics of these increasingly threatened ecosystems. Herein, we assess the fine scale genetic connectivity of six populations of the Atlantic giant barrel sponge, Xestospongia muta (Schmidt, 1870), using microsatellite markers. This survey included populations from across the Florida Reef Tract and the Gulf of Mexico, including sponges from the Pulley Ridge Habitat Area of Particular Concern, a mesophotic coral reef located approximately 250 km from Florida's (USA) southwestern coast, and the Flower Garden Banks National Marine Sanctuary, the northernmost western Atlantic coral reef ecosystem. Overall, significant population structure was found (FST = 0.020, 95% CI: 0.011-0.031), with X. muta individuals from the Flower Garden Banks showing the highest levels of genetic differentiation relative to all other surveyed populations (FST > 0.048). Despite the high levels of population structuring observed, some horizontal and/ or vertical connectivity was found between neighboring reef systems, including evidence of gene flow between mesophotic (Pulley Ridge Habitat of Particular Concern) and photic (Dry Tortugas) reef tracts. Furthermore, largely negligible levels of first-generation migration among discrete genetic populations was observed, suggesting that the persistence of most populations of X. muta is highly dependent on selfrecruitment. Thus, while the Pulley Ridge mesophotic reef may provide sponge recruits to shallow photic reefs, its role as a potential refuge and propagule source appears limited to only small geographic scales.

Abstract The deep waters of the open ocean represent a major frontier in exploration and scientific understanding. However, modern technological and computational tools are making the deep ocean more accessible than ever before by facilitating increasingly sophisticated studies of deep ocean ecosystems. Here, we describe some of the cutting-edge technologies that have been employed by the Deep Pelagic Nekton Dynamics of the Gulf of Mexico (DEEPEND; &lt;ext-link ext-link-type="uri" href="http://www.deependconsortium.org"&gt;www.deependconsortium.org&lt;/ext-link&gt;) Consortium to study the biodiverse fauna and dynamic physical-chemical environment of the offshore Gulf of Mexico (GoM) from 0 to 1,500 m.