This paper is centered on a new form of adaptive material which functions much in the same way as skeletal muscle tissue, is structurally modeled on plant actuator cells and capable of rapidly expanding or shrinking by as much as an order of magnitude in prescribed directions. Rapid changes of plant cell shape and sizes are often initiated via ion-transport driven fluid migration and resulting turgor pressure variation. Certain plant cellular structures like those in Mimosa pudica (sensitive plant), Albizia julibrissin (Mimosa tree), or Dionaea muscipula (Venus Flytrap) all exhibit actuation physiology which employs such turgor pressure manipulation. The paper begins with dynamic micrographs of a sectioned basal articulation joint from A. julibrissin. These figures show large cellular dimensional changes as the structure undergoes foliage articulation. By mimicking such structures in aircraft flight control mechanisms, extremely lightweight pneumatic control surface actuators can be designed. This paper shows several fundamental layouts of such surfaces with actuator elements made exclusively from FAAcertifiable materials, summarizes their structural mechanics and shows actuator power and energy densities that are higher than nearly all classes of conventional adaptive materials available today. A sample flap structure is shown to possess the ability to change its shape and structural stiffness as its cell pressures are manipulated, which in turn changes the surface liftcurve slope when exposed to airflows. Because the structural stiffness can be altered, it is also shown that the commanded section lift-curve slope can be similarly controlled between 1.2 and 6.2 rad −1 . Several aircraft weight reduction principles are also shown to come into play as the need to concentrate loads to pass through point actuators is eliminated. The paper concludes with a summary of interrelated performance and airframe-level improvements including enhanced gust rejection, load alleviation, ride quality, fatigue life and flight safety.

Quorum sensing networks have been identified in over one hundred bacterial species to date. A subset of these networks regulate group behaviors, such as bioluminescence, virulence, and biofilm formation, by sending and receiving small molecules called homoserine lactones (HSLs). Bioengineers have incorporated quorum sensing pathways into genetic circuits to connect logical operations. However, the development of higher-order genetic circuitry is inhibited by crosstalk, in which one quorum sensing network responds to HSLs produced by a different network. Here, we report the construction and characterization of a library of ten synthases including some that are expected to produce HSLs that are incompatible with the Lux pathway, and therefore show no crosstalk. We demonstrated their function in a common lab chassis, Escherichia coli BL21, and in two contexts, liquid and solid agar cultures, using decoupled Sender and Receiver pathways. We observed weak or strong stimulation of a Lux receiver by longer-chain or shorter-chain HSL-generating Senders, respectively. We also considered the under-investigated risk of unintentional release of incompletely deactivated HSLs in biological waste. We found that HSL-enriched media treated with bleach were still bioactive, while autoclaving deactivates LuxR induction. This work represents the most extensive comparison of quorum signaling synthases to date and greatly expands the bacterial signaling toolkit while recommending practices for disposal based on empirical, quantitative evidence.

Chromatin is a system of nuclear proteins and nucleic acids that plays a pivotal role in gene expression and cell behavior and is therefore the subject of intense study for cell development and cancer research. Biochemistry, crystallography, and reverse genetics have elucidated the macromolecular interactions that drive chromatin regulation. One of the central mechanisms is the recognition of post-translational modifications (PTMs) on histone proteins by a family of nuclear proteins known as "readers". This knowledge has launched a wave of activity around the rational design of proteins that interact with histone PTMs. Useful molecular tools have emerged from this work, enabling researchers to probe and manipulate chromatin states in live cells. Chromatin-based proteins represent a vast design space that remains underexplored. Therefore, we have developed a rapid prototyping platform to identify engineered fusion proteins that bind histone PTMs in vitro and regulate genes near the same histone PTMs in living cells. We have used our system to build gene activators with strong avidity for the gene silencing-associated histone PTM H3K27me3. Here, we describe procedures and data for cell-free production of fluorescently tagged fusion proteins, enzyme-linked immunosorbent assay-based measurement of histone PTM binding, and a live cell assay to demonstrate that the fusion proteins modulate transcriptional activation at a site that carries the target histone PTM. This pipeline will be useful for synthetic biologists who are interested in designing novel histone PTM-binding actuators and probes.

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Quorum sensing networks have been identified in over one hundred bacterial species to date . A subset of these networks regulate group behaviors, such as bioluminescence, virulence, and biofilm formation, by sending and receiving small molecules called homoserine lactones (HSLs). Bioengineers have incorporated quorum sensing pathways into genetic circuits to connect logical operations. However, the development of higher-order genetic circuitry is inhibited by crosstalk, in which one quorum sensing network responds to HSLs produced by a different network. Here, we report the construction and characterization of a library of ten synthases including some that are expected to produce HSLs that are incompatible with the Lux pathway, and therefore show no crosstalk. We demonstrated their function in a common lab chassis, Escherichia coli BL21, and in two contexts, liquid and solid agar cultures, using decoupled Sender and Receiver pathways. We observed weak or strong stimulation of a Lux Receiver by longer-chain or shorter-chain HSL-generating Senders, respectively. We also considered the under-investigated risk of unintentional release of incompletely deactivated HSLs in biological waste. We found that HSL-enriched media treated with bleach is still bioactive, while autoclaving deactivates LuxR induction. This work represents the most extensive comparison of quorum sensing synthases to date and greatly expands the bacterial signaling toolkit while recommending practices for disposal based on empirical, quantitative evidence.