Mark A. Johnson’s research while affiliated with Brown University and other places

... 3 These interactions are prevalent in many important chemical systems, guiding the bulk behavior of water, 4,5 determining the secondary structure of proteins, [6][7][8][9][10][11] pairing nucleotides in DNA, [12][13][14][15] forming self-healing polymers, [16][17][18] contributing to the stability and catalytic properties in metal-organic frameworks, 19,20 and diversifying the interactions in ionic liquids. 21,22 The important structural properties and functionality in the aforementioned chemical systems can be attributed to the properties of their constituent hydrogen bonds. For that reason, understanding the nature of the hydrogen bonds in these systems is important for understanding their macroscopic physical properties and for developing the next-generation materials that exploit the properties of hydrogen bonds. ...

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Extending Badger's rule. I. The relationship between energy and structure in hydrogen bonds

... Because each fertilized ovule develops into one seed, the number of seeds is directly proportional to pollen performance, which is defined as the ability of pollen grains to germinate a pollen tube that successfully extends to and ruptures in an ovule. Pollen performance can also influence fruit biomass, as we have shown that for cultivated tomato (Solanum lycopersicum, hereafter referred to as tomato), the number of seeds produced in a fruit is directly proportional to the fruit's biomass [2]. Furthermore, some cultivars that maintain fruit and seed production at high temperature also maintain high pollen tube performance in the pistil [2]. ...

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Semi-Automated High Content Analysis of Pollen Performance Using TubeTracker

... The VN is large, highly lobbed and contains numerous nuclear pores ( Fig. 3A-I, Fig. S2). The male gametes are separated from each other by their plasma membranes and are enclosed within the plasma endomembrane of the VC called peri-germ cell membrane (PGCM) (Sugi et al. 2024) (Fig. 3I-M, arrows, Fig. S2). The area connecting the SCs exhibits an interlocking cell border filled with electron-dense material (Fig. 3M, asterisk). ...

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Bioimaging insights into structural pathways of cell-to-cell communication within the male (MGU) and female (FGU) germ units of Arabidopsis thaliana

... These indicate that the resistant cultivars have the capacity to maintain pollen hydration even in water stress condition. The pollen hydration and dehydration are controlled by several transcription factors which directly affects the pollen germination and the double fertilization process [24,21,22]. The pollen radius and pollen surface area affect the sporopollenin deposition and also the fertilization [25]. ...

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Correlation Studies on Pollen Attributes and Grain Yield under Drought Stress in a Wild Multiparental Population of Rice (Oryza sativa L.)

... molecule involved in plant growth and development and in the tolerance of plants to biotic and abiotic stresses(Khan et al., 2014). ROS, are key players in biotic and abiotic stress tolerance, also act as signals in petals, pollen tubes, and gametophyte developments, in germination(Althiab-Almasaud et al., 2023), in auxin metabolism and in other hormonal pathways(Mhamdi and Van Breusegem, 2018). ROS modulate the mechanisms for propagation of Ca 2+ by activating Ca 2+ -dependent channels and transporters(Gilroy et al., 2016). ...

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Glycomolecules: from "sweet immunity" to "sweet biostimulation"?

... We need to add to this scenario that, when a second (or more) non-Previous studies using laser action spectroscopy, such as Infrared Multiphoton Dissociation (IRMPD) and cold ion trap Ultraviolet Photodissociation (UVPD), have reported the observation of only one of the possible isomers in the case of benzaldehyde and orthoand para-hydroxybenzaldehyde, and two isomeric forms of meta-hydroxybenzaldehyde 21,24 . The individual use of these techniques have been shown to be very suitable for the study of protonated species, especially when the ions are prepared at cryogenic temperatures [25][26][27][28] . However, the combined utilisation of IRMPD and UVPD is less commonly found in the literature, although very interesting works have been published 11,[29][30][31] . ...

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Vibrational and electronic spectra of protonated vanillin: Exploring protonation sites and isomerisation

... The mammalian CN is divided into three subnuclei-anteroventral cochlear nucleus (AVCN), posteroventral cochlear nucleus (PVCN), and dorsal cochlear nucleus (DCN)-based on cellular organization, synaptic circuitry, output projections, and functional properties (Rubio, 2018;Trussell and Oertel, 2018). Three CN subnuclei have been identified also in several species of echolocating bats, sharing anatomical, physiological, and molecular properties with those of non-echolocating mammals (Accomando et al., 2023;Covey, 2005;Hall, 1969;Haplea et al., 1994;Horowitz et al., 2008;K€ ossl and Vater, 1990;Marsh et al., 2006;Vater, 1982). ...

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Representation of frequency-modulated sweeps in the cochlear nucleus of the big brown bat

... The presence of even relatively small amounts of organic material on sea spray aerosol is also potentially important for oxidation chemistry over the oceans. Organics may be both a source and sink of radical species in aerosol, and hydrophobic compounds present in sea spray may in particular influence heterogeneous uptake and reactions involving gas phase molecules (Lawler et al., 2011;Stropoli et al., 2023;Wang et al., 2018;Zhou et al., 2008). ...

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Sea Spray Aerosol Over the Remote Oceans Has Low Organic Content

... Observed action spectra are thus the kinetic outcome of the competing complex formation and photodissociation processes. Related continuous wave irradiation schemes 20 have been employed for tagged species in cryogenic (∼5 K) ion traps where the role of competing processes, including the laser-induced inhibition of complex growth, have been discussed in detail. 21,22 Amino acid test cases are used for demonstrations as they are a prime target for future planetary science missions, 23,24 with observed spectra compared to those taken with much more complex instrument sets. ...

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Infrared Photodissociation Spectroscopy of Water-Tagged Ions with a Widely Tunable Quantum Cascade Laser for Planetary Science Applications

... Recently, reaction products of N2O5 with halides in small water clusters were analyzed via vibrational spectra using a cryogenic photofragmentation mass spectrometry, indicating that N2O5 preferentially under-goes halide substitution over hydrolysis in these model systems (122). Later theoretical studies identified key features of the potential energy surface in clusters of N2O5 and Cl − with one to five water molecules using coupled cluster calculations and density functional theory based ab initio molecular dynamics (123,124,125). It was found that there is almost no barrier for the Cl − substitution reaction of N2O5 to form ClNO2 when only one water molecule is present. ...

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Molecular Insights into Chemical Reactions at Aqueous Aerosol Interfaces