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At least 559 records · Page 31

Interdisciplinary Research Collaborative Trains Students to See Through Turbulent Systems

Despite the availability of interdisciplinary academic training programs, the practice of environmental science is often hampered by a lack of convergence across diverse disciplines. This gap is particularly salient in settings characterized by complex environmental issues, such as multiple-use coastal ecosystems. In response, we developed and implemented a training, research, and communication framework to provide undergraduates with an authentic operative experience working at the interface of interdisciplinary science and public decision-making within a case study of marine renewable energy. In our program, students gained hands-on experience with the scientific process and learned how to make information relevant, useful, and accessible to diverse stakeholder groups. Application of this framework demonstrates that the process of integrating data from biological (visual and acoustic monitoring of fish and marine mammals), physical (hydrodynamics), and social (local ecological knowledge) sciences can provide a more complete understanding of complex and turbulent ecosystems for better informed decision-making. We offer several recommendations to facilitate the adaptation and implementation of our interdisciplinary framework to diverse research contexts, with a focus on interdisciplinary training for the next generation of marine scientists.

54 ENVIRONMENTAL SCIENCES↗

Structural characterization of ligand binding and pH-specific enzymatic activity of mouse Acidic Mammalian Chitinase

Chitin is an abundant biopolymer and pathogen-associated molecular pattern that stimulates a host innate immune response. Mammals express chitin-binding and chitin-degrading proteins to remove chitin from the body. One of these proteins, Acidic Mammalian Chitinase (AMCase), is an enzyme known for its ability to function under acidic conditions in the stomach but is also active in tissues with more neutral pHs, such as the lung. Here, we used a combination of biochemical, structural, and computational modeling approaches to examine how the mouse homolog (mAMCase) can act in both acidic and neutral environments. We measured kinetic properties of mAMCase activity across a broad pH range, quantifying its unusual dual activity optima at pH 2 and 7. We also solved high-resolution crystal structures of mAMCase in complex with oligomeric GlcNAcn, the building block of chitin, where we identified extensive conformational ligand heterogeneity. Leveraging these data, we conducted molecular dynamics simulations that suggest how a key catalytic residue could be protonated via distinct mechanisms in each of the two environmental pH ranges. These results integrate structural, biochemical, and computational approaches to deliver a more complete understanding of the catalytic mechanism governing mAMCase activity at different pH. Engineering proteins with tunable pH optima may provide new opportunities to develop improved enzyme variants, including AMCase, for therapeutic purposes in chitin degradation.

59 BASIC BIOLOGICAL SCIENCES↗

Comments on cross-adaptation

Cross adaptation criteria and modifications in physiologic and biochemical processes in man and mammals, demonstrating positive cross acclimation between hypertension and hypoxia exposure

Fregly, M. J.↗

Neurophysiological findings relevant to echolocation in marine animals

A review of echolocation mechanisms in marine mammals, chiefly porpoises, is given. Data cover peripheral auditory and central neurophysiological specializations favorable to the analysis of echolocating clicks and their echoes. Conclusions show (1) signals are received from 50 up to at least 135 kHz, (2) sound is received through the mandible skin, and (3) the midbrain sites are insensitive to low frequencies (below 6 kHz).

Bullock, T. H.↗

RBE for late somatic effects in mice irradiated with 60 MeV protons relative to X-rays.

Investigation of the relative biological effectiveness of energetic protons for the induction of somatic effects in a mammal (mice) following whole body irradiation. The proton energy used approximates the mean energy for proton spectra accompanying solar events. The effects on longevity and the incidence of major neoplastic diseases are summarized. The results obtained suggest that medium energy proton irradiation is no more effective, and on the whole, probably less effective, than conventional X radiation for the induction of late radiation effects in the mouse.

Darden, E. B., Jr.↗