Investigating the Role of FGF8 Signaling in Neurogenesis of the Developing Zebrafish Eye

In the embryonic zebrafish, the fibroblast growth factor 8a (FGF8) signaling network is essential for proper development and maintenance of retinal ganglion cells (RGCs) as well as the hyaloid vasculature, the vessels that supply the eye with nutrients during development. Disruption of FGF8 signaling via knock down of FGF8 or pharmacologic inhibition of FGF receptors (FGFRs) results in extensive abnormalities throughout the developing eye. Our preliminary data indicated that in developing zebrafish, mRNA expression of fgf8a is present exclusively in the RGCs, while the fibroblast growth factor receptor 1 (fgfr1b) is expressed exclusively in the area of the hyaloid vasculature. These results led us to hypothesize that FGF8 signals from the RGCs to the vasculature of the developing eye, and that this signaling network is essential for proper eye development. In order to test this hypothesis, we demonstrated the ability to detect downstream phosphorylation events in response to acute FGF8 stimulation in cells that expressed FGFR1 using Western blot and immunofluorescence (IF). Next, we established a zebrafish eye explant culture system to treat the cells of the developing zebrafish eye in vitro. Using transgenic zebrafish lines expressing green fluorescent protein (GFP) tags in either the differentiating RGCs or the vascular cells of the eye, we attempted to identify the specific cells capable of responding to FGF8. Our data indicate that recombinant FGF8 is capable of activating detectable intracellular signaling cascades, such as ERK phosphorylation, in cultured endothelial cells. Furthermore, FGF8 is capable of inducing signaling in some of the cells from the developing zebrafish eye, but not in the RGCs. These findings support our proposed model in which FGF8 signals from the RGCs to the hyaloid vasculature, resulting in the activation of signaling pathways that are necessary for proper development of the hyaloid vasculature and RGCs

Sensing the Spin State of Room-Temperature Switchable Cyanometallate Frameworks with Nitrogen-Vacancy Centers in Nanodiamonds

Room-temperature magnetically switchable materials play a vital role in current and upcoming quantum technologies, such as spintronics, molecular switches, and data storage devices. The increasing miniaturization of device architectures produces a need to develop analytical tools capable of precisely probing spin information at the single-particle level. In this work, we demonstrate a methodology using negatively charged nitrogen vacancies (NV–) in fluorescent nanodiamond (FND) particles to probe the magnetic switching of a spin crossover (SCO) metal–organic framework (MOF), [Fe(1,6-naphthyridine)2(Ag(CN)2)2] material (1), and a single-molecule photomagnet [X(18-crown-6)(H2O)3]Fe(CN)6·2H2O, where X = Eu and Dy (materials 2a and 2b, respectively), in response to heat, light, and electron beam exposure. We employ correlative light–electron microscopy using transmission electron microscopy (TEM) finder grids to accurately image and sense spin–spin interacting particles down to the single-particle level. We used surface-sensitive optically detected magnetic resonance (ODMR) and magnetic modulation (MM) of FND photoluminescence (PL) to sense spins to a distance of ca. 10–30 nm. We show that ODMR and MM sensing was not sensitive to the temperature-induced SCO of FeII in 1 as formation of paramagnetic FeIII through surface oxidation (detected by X-ray photoelectron spectroscopy) on heating obscured the signal of bulk SCO switching. We found that proximal FNDs could effectively sense the chemical transformations induced by the 200 keV electron beam in 1, namely, AgI → Ag0 and FeII → FeIII. However, transformations induced by the electron beam are irreversible as they substantially disrupt the structure of MOF particles. Finally, we demonstrate NV– sensing of reversible photomagnetic switching, FeIII + (18-crown-6) ⇆ FeII + (18-crown-6)+ •, triggered in 2a and 2b by 405 nm light. The photoredox process of 2a and 2b proved to be the best candidate for room-temperature single-particle magnetic switching utilizing FNDs as a sensor, which could have applications into next-generation quantum technologies

Simulating Secondary Organic Aerosol Activation by Condensation of Multiple Organics on Seed Particles

The conditions under which semivolatile organic gases condense were studied in a Teflon particle chamber by scanning mobility particle sizing (SMPS) of the resultant particles. Benzaldehyde, maleic and citraconic anhydrides, n-decane, trans-cinnamaldehyde, and citral were introduced in various combinations into a particle chamber containing either particle-free nitrogen or nitrogen with dry seed particles made out of sodium chloride, d-tartartic acid, ammonium sulfate, or 1,10-decanediol. No organic gas was allowed to reach its saturation point relative to the vapor pressure of its pure liquid in any experiment. In the absence of seed particles, organic aerosol particles formed by ternary nucleation when the sum of the individual organic saturation levels reached a threshold between 1.17 and 1.86. With seed particles present, particle sizes began to increase when the sum of organic saturation levels reached 1.0. This size increase corresponds to the establishment and activation of ternary organic layers on the “clean” seed particles, as predicted by absorption partitioning theory. The observed increases in particle volume depended on initial seed particle volume, indicating that either gas diffusion rates or chemical reactions were controlling the rate of uptake

The geographies of community history digital archives in rural Scotland

The CURIOS (Cultural Repositories and Information Systems) project has been working with community heritage groups to co-produce sustainable solutions for the production of heritage archives in digital form. This process has produced an opportunity for fascinating geographical research into the ways in which community heritage groups produce history from their own perspective. This paper will therefore begin to open up these ongoing processes to consider, through case study examples, the ways in which the production of digital archives alters the geography of community heritage production. A number of community heritage groups have been converting their ‘analogue’ collections into ‘digital’ forms and the paper will argue how this significantly alters the positionality of the archive. This will be shown by detailing the ways in which the processes of collection and preservation, conducted by community volunteers, take place. The paper will then move to consider the ways in which this historical material, representative of place, is presented back to a wider audience. In doing this, it will discuss the rationales and processes involved in these practices and how this relates to broader themes of research within geography. Whether for historical research or for theoretical positioning, geographers have, on a number of levels, engaged with archives. Yet, the digital archive has seen little attention especially in terms of thinking through the ways in which digital mediums alter perceptions of space and place