Invasion of the body snatchers: the role of parasite introduction in host distribution and response to salinity in invaded estuaries.

In dynamic systems, organisms are faced with variable selective forces that may impose trade-offs. In estuaries, salinity is a strong driver of organismal diversity, while parasites shape species distributions and demography. We tested for trade-offs between low-salinity stress and parasitism in an invasive castrating parasite and its mud crab host along salinity gradients of two North Carolina rivers. We performed field surveys every six to eight weeks over 3 years to determine factors influencing parasite prevalence, host abundance, and associated taxa diversity. We also looked for signatures of low-salinity stress in the host by examining its response (time-to-right and gene expression) to salinity. We found salinity and temperature significantly affected parasite prevalence, with low-salinity sites (less than 10 practical salinity units (PSU)) lacking infection, and populations in moderate salinities at warmer temperatures reaching prevalence as high as 60%. Host abundance was negatively associated with parasite prevalence. Host gene expression was plastic to acclimation salinity, but several osmoregulatory and immune-related genes demonstrated source-dependent salinity response. We identified a genetic marker that was strongly associated with salinity against a backdrop of no neutral genetic structure, suggesting possible selection on standing variation. Our study illuminates how selective trade-offs in naturally dynamic systems may shape host evolutionary ecology.

Efficient actuation design for optomechanical sensors.

For any nanomechanical device intended for sensing applications, actuation is an important consideration. Many different actuation mechanisms have been used, including self-oscillation, piezoelectric shakers, capacitive excitation, and optically pumping via the optical gradient force. Despite the relatively frequent use of optical pumping, the limits of optical actuation with a pump laser have not been fully explored. We provide a practical framework for designing optical cavities and optomechanical systems to maximize the efficiency of the optical pumping technique. The effects of coherent backscattering on detection and actuation are included. We verify our results experimentally and show good agreement between the model and experiment. Our model for efficient actuation will be a useful resource for the future design of optomechanical cavities for sensor and other high-amplitude applications.

Quantifying the effectiveness of shoreline armoring removal on coastal biota of Puget Sound.

Shoreline armoring is prevalent around the world with unprecedented human population growth and urbanization along coastal habitats. Armoring structures, such as riprap and bulkheads, that are built to prevent beach erosion and protect coastal infrastructure from storms and flooding can cause deterioration of habitats for migratory fish species, disrupt aquatic-terrestrial connectivity, and reduce overall coastal ecosystem health. Relative to armored shorelines, natural shorelines retain valuable habitats for macroinvertebrates and other coastal biota. One question is whether the impacts of armoring are reversible, allowing restoration via armoring removal and related actions of sediment nourishment and replanting of native riparian vegetation. Armoring removal is targeted as a viable option for restoring some habitat functions, but few assessments of coastal biota response exist. Here, we use opportunistic sampling of pre- and post-restoration data for five biotic measures (wrack % cover, saltmarsh % cover, number of logs, and macroinvertebrate abundance and richness) from a set of six restored sites in Puget Sound, WA, USA. This broad suite of ecosystem metrics responded strongly and positively to armor removal, and these results were evident after less than one year. Restoration responses remained positive and statistically significant across different shoreline elevations and temporal trajectories. This analysis shows that removing shoreline armoring is effective for restoration projects aimed at improving the health and productivity of coastal ecosystems, and these results may be widely applicable.

A methodological approach to scaling up fermentation and primary recovery processes to the manufacturing scale for vaccine production.

As the fermentation process is scaled up, the mass-transfer and nutritional requirements are to be maintained in improving antigen yields upon scale-up. A methodology is adopted to scale-down the processes at the laboratory level in order to further optimize the hydrodynamic and nutritional requirements of the bacteria prior to scaling up. For recovery of bacterial proteins, several micro-filtration techniques are discussed. An optimized process consisting of cross-flow micro-filtration, homogenization and batch clarification using ion-exchange resins is used.

Mechanical stability of immobilized biocatalysts (CLECs) in dilute agitated suspensions.

Cross-linked enzyme crystals (CLECs) are a novel form of immobilized biocatalyst designed for application in industrial biotransformation processes. In this work we have investigated the mechanical stability of agitated CLEC suspensions in relation to the design and scale-up of bioconversions carried out in stirred-tank reactors. By careful control of the crystallization conditions yeast alcohol dehydrogenase I (YADHI) microcrystals of different size were first prepared having either an hexagonal (approximately 12 microm) or rod-shaped (approximately 4.6 microm) morphology. These were then cross-linked with glutaraldehyde to form CLECs. The rate of breakage of the CLEC suspensions was subsequently measured in a rotating disk shear device (total volume, 11 mL) by monitoring the change in crystal size distribution with time. This device is designed to mimic the shear and energy dissipation rates found in a range of process scale equipment and may be used to study the mechanical stability of any immobilized biocatalyst preparation. Experiments were performed as a function of the speed and duration of disk rotation, CLEC concentration (0.26-2.5 mg.mL(-1)) and energy dissipation rate (2.2 x 10(3) to 6.8 x 10(5) W.kg(-1)). No breakage of the rod-shaped CLECs was observed over the entire range of experimental conditions investigated. Breakage of the larger hexagonal-shaped CLECs did occur, however, at energy dissipation rates, epsilon(max), above 1.0 x 10(5) W.kg(-1), where the calculated length scale of turbulence was around 2.0 microm. Based on visual observation of the sheared CLEC suspensions and models of crystal breakage, it was concluded that breakage of the hexagonal-shaped CLECs occurred due to shear induced attrition. Measurement of the catalytic activity of both the hexagonal and rod-shaped CLECs showed no significant change in activity before and after shearing.