Recruitment of older adult-caregiver dyads during the COVID-19 pandemic: an example from a study to evaluate a novel activities of daily living (ADL) sensor system.

Under ideal circumstances, recruitment of older adult-caregiver dyads to dementia research is challenging. The COVID-19 pandemic introduced additional barriers to recruitment, necessitating swift adjustments to pre-pandemic recruitment strategies and schedules. This brief research report describes the challenges, yield, and cost of recruiting older adult-caregiver dyads to an 18-month observational research study during COVID-19.

SGRN: A Cas12a-driven Synthetic Gene Regulatory Network System.

Gene regulatory networks, which control gene expression patterns in development and in response to stimuli, use regulatory logic modules to coordinate inputs and outputs. One example of a regulatory logic module is the gene regulatory cascade (GRC), where a series of transcription factor genes turn on in order. Synthetic biologists have derived artificial systems that encode regulatory rules, including GRCs.

Tyrosine triad at the interface between the Rieske iron-sulfur protein, cytochrome c1 and cytochrome c2 in the bc1 complex of Rhodobacter capsulatus.

A triad of tyrosine residues (Y152-154) in the cytochrome c(1) subunit (C1) of the Rhodobacter capsulatus cytochrome bc(1) complex (BC1) is ideally positioned to interact with cytochrome c(2) (C2). Mutational analysis of these three tyrosines showed that, of the three, Y154 is the most important, since its mutation to alanine resulted in significantly reduced levels, destabilization, and inactivation of BC1. A second-site revertant of this mutant that regained photosynthetic capacity was found to have acquired two further mutations-A181T and A200V.

Can experiential-didactic training improve clinical STD practices?

Background: High rates of sexually transmitted diseases (STDs) present an ongoing costly public health challenge. One approach to reduce STD transmission is to increase the number of clinicians adopting the Centers for Disease Control and Prevention's STD Treatment Guidelines. This evaluation assesses the effectiveness of a 3-day experiential and didactic training to translate recommendations into practice by increasing clinician knowledge and skills and helping participants anticipate and overcome barriers to implementation.

Regulation of the Ppr histidine kinase by light-induced interactions between its photoactive yellow protein and bacteriophytochrome domains.

Ppr is a unique bacteriophytochrome that bleaches rather than forming a far-red-shifted Pfr state upon red light activation. Ppr is also unusual in that it has a blue light photoreceptor domain, PYP, which is N-terminally fused to the bacteriophytochrome domain (Bph). When both photoreceptors are activated by light, the fast phase of Bph recovery (1 min lifetime) corresponds to the formation of an intramolecular long-lived complex between the activated PYP domain and the Bph domain (lifetime of 2-3 days).

Plasmon-waveguide resonance studies of ligand binding to integral proteins in membrane fragments derived from bacterial and mammalian cells.

A procedure has been developed for directly depositing membrane fragments derived from bacterial cells (chromatophores from Rhodopseudomonas sphaeroides) and mammalian cells (mu-opioid receptor- and MC4 receptor-transfected human embryonic kidney (HEK) cells and rat trigeminal ganglion cells) on the silica surface of a plasmon-waveguide resonance (PWR) spectrometer. Binding of ligands (cytochrome c(2) for the chromatophores, the peptide agonists DAMGO and melanotan-II that are specific for the mu-opioid and MC4 receptors, and two nonpeptide agonists that are specific for the CB1 receptor) to these membrane fragments has been observed and characterized with high sensitivity using PWR spectral shifts. The K(D) values obtained are in excellent agreement with conventional pharmacological assays and with prior PWR studies using purified receptors inserted into deposited lipid bilayer membranes.

The photoactivated PYP domain of Rhodospirillum centenum Ppr accelerates the recovery of the bacteriophytochrome domain after white light illumination.

Ppr from the purple phototrophic bacterium, Rhodospirillum centenum (also known as Rhodocista centenaria), is a hybrid of photoactive yellow protein (PYP), bacteriophytochrome (Bph), and histidine kinase (HK) domains. The holo-Ppr (containing both chromophores) exhibits characteristic absorption maxima at 435 nm due to the PYP domain and at 400, 642, and 701 nm due to the Bph domain. Illumination of the Ppr with white light causes a bleach of both PYP and Bph absorbance; weak blue light primarily bleaches the PYP, and red light activates only the Bph.

Structural role of tyrosine 98 in photoactive yellow protein: effects on fluorescence, gateway, and photocycle recovery.

We have recently shown that the Y98Q mutant of PYP has a major effect on the photocycle kinetics ( approximately 40 times slower recovery). We have now determined the crystal structure of Y98Q at 2.2 A resolution to reveal the role of residue Y98 in the PYP photocycle.

GHP, a new c-type green heme protein from Halochromatium salexigens and other proteobacteria.

We have isolated a minor soluble green-colored heme protein (GHP) from the purple sulfur bacterium, Halochromatium salexigens, which contains a c-type heme. A similar protein has also been observed in the purple bacteria Allochromatium vinosum and Rhodopseudomonas cryptolactis. This protein has wavelength maxima at 355, 420, and 540 nm and remains unchanged upon addition of sodium dithionite or potassium ferricyanide, indicating either an unusually low or high redox potential, respectively.

Thermochromatium tepidum photoactive yellow protein/bacteriophytochrome/diguanylate cyclase: characterization of the PYP domain.

The purple phototrophic bacterium, Thermochromatium tepidum, contains a gene for a chimeric photoactive yellow protein/bacteriophytochrome/diguanylate cyclase (Ppd). We produced the Tc. tepidum PYP domain (Tt PYP) in Escherichia coli, and found that it has a wavelength maximum at 358 nm due to a Leu46 substitution of the color-tuning Glu46 found in the prototypic Halorhodospira halophila PYP (Hh PYP).

Nuclear ferritin in corneal epithelial cells: tissue-specific nuclear transport and protection from UV-damage.

We have identified the heavy chain of ferritin as a developmentally regulated nuclear protein of embryonic chicken corneal epithelial cells. The nuclear ferritin is assembled into a supramolecular form that is indistinguishable from the cytoplasmic form of ferritin found in other cell types. Thus it most likely has iron-sequestering capabilities.

Cellular invasion of the chicken corneal stroma during development: regulation by multiple matrix metalloproteases and the lens.

Avian corneal development requires cellular invasion into the acellular matrix of the primary stroma. Previous results show that this invasion is preceded by the removal of the fibril-associated type IX collagen, which possibly stabilizes matrices through interfibrillar cross-bridges secured by covalent crosslinks. In the present study, we provide evidence for the expression of three matrix metalloproteinases (MMPs) in early corneas, two of which act cooperatively to selectively remove type IX collagen in situ.

Ultra-high-throughput microarray generation and liquid dispensing using multiple disposable piezoelectric ejectors.

The authors have constructed an array of 12 piezoelectric ejectors for printing biological materials. A single-ejector footprint is 8 mm in diameter, standing 4 mm high with 2 reservoirs totaling 76 micro L. These ejectors have been tested by dispensing various fluids in several environmental conditions.

Ferritoid, a tissue-specific nuclear transport protein for ferritin in corneal epithelial cells.

Previously we reported that ferritin in corneal epithelial (CE) cells is a nuclear protein that protects DNA from UV damage. Since ferritin is normally cytoplasmic, in CE cells, a mechanism must exist that effects its nuclear localization. We have now determined that this involves a nuclear transport molecule we have termed ferritoid.

Heterologous production of Halorhodospira halophila holo-photoactive yellow protein through tandem expression of the postulated biosynthetic genes.

The photoactive yellow protein (PYP) is a bacterial photoreceptor which is the structural prototype for the PAS domain superfamily of regulators and receptors. PYP is known to have a unique p-hydroxycinnamic acid chromophore, covalently attached to a cysteine. To date, it has not been shown how holo-PYP is formed in vivo.

Protein dynamics: imidazole and 2-mercaptoethanol binding to the Rhodobacter capsulatus cytochrome c(2) mutant, glycine 95 proline.

The Class I c-type cytochromes can bind exogenous ligands in the oxidized state, with the kinetics of ligand binding providing information on naturally occurring intramolecular dynamics. Typically, nitrogenous bases are used as ligands; however, it is less well known that 2-mercaptoethanol (BME), a commonly used cytochrome reducing agent, can form a complex with the heme. To better understand the cytochrome-mercaptan interaction, we have investigated the kinetics of binding of BME to wild type and mutants of Rhodobacter capsulatus cytochrome c(2) and to horse cytochrome c.