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  1. Abstract Background and Aims

    Few studies of angiosperms have focused on androecial evolution in conjunction with evolutionary shifts in corolla morphology and pollinator relationships. The Western Hemisphere clade of Justiciinae (Acanthaceae) presents the rare opportunity to examine remarkable diversity in staminal morphology. We took a phylogenetically informed approach to examine staminal diversity in this hypervariable group and asked whether differences in anther thecae separation is associated with phylogenetically informed patterns of variation in corolla morphology. We further discuss evidence for associations between anther diversity and pollinators in this lineage.


    For the Dianthera/Sarotheca/Plagiacanthus (DSP) clade of Western Hemisphere Justiciinae, we characterized floral diversity based on a series of corolla measurements and using a model-based clustering approach. We then tested for correlations between anther thecae separation and corolla traits, and for shifts in trait evolution, including evidence for convergence.

    Key Results

    There is evolutionary vagility in corolla and anther traits across the DSP clade with little signal of phylogenetic constraint. Floral morphology clusters into four distinct groups that are, in turn, strongly associated with anther thecae separation, a novel result in Acanthaceae and, to our knowledge, across flowering plants. These cluster groups are marked by floral traits that strongly point to associations with pollinating animals. Specifically, species that are known or likely to be hummingbird pollinated have stamens with parallel thecae, whereas those that are likely bee or fly pollinated have stamens with offset, divergent thecae.


    Our results suggest that anther thecae separation is likely under selection in concert with other corolla characters. Significant morphological shifts detected by our analyses corresponded to putative shifts from insect to hummingbird pollination. Results from this study support the hypothesis that floral structures function in an integrated manner and are likely subject to selection as a suite. Further, these changes can be hypothesized to represent adaptive evolution.

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  2. null (Ed.)
    In this work, a proteolytic digest of cytochrome c (microperoxidase 11, MP-11) was used as a model to study the structural aspects of heme protein interactions and porphyrin networks. The MP-11 structural heterogeneity was studied as a function of the starting pH ( e.g. , pH 3.1–6.1) and concentration ( e.g. , 1–50 μM) conditions and adduct coordination. Trapped ion mobility spectrometry coupled to mass spectrometry (TIMS-MS) showed the MP-11 structural dependence of the charge state distribution and molecular ion forms with the starting pH conditions. The singly charged ( e.g. , [M] + , [M − 2H + NH 4 ] + , [M − H + Na] + and [M − H + K] + ) and doubly charged ( e.g. , [M + H] 2+ , [M − H + NH 4 ] 2+ , [M + Na] 2+ and [M + K] 2+ ) molecular ion forms were observed for all solvent conditions, although the structural heterogeneity ( e.g. , number of mobility bands) significantly varied with the pH value and ion form. The MP-11 dimer formation as a model for heme-protein protein interactions showed that dimer formation is favored toward more neutral pH and favored when assisted by salt bridges ( e.g. , NH 4 + , Na + and K + vs. H + ). Inspection of the dimer mobility profiles (2+ and 3+ charge states) showed a high degree of structural heterogeneity as a function of the solution pH and ion form; the observation of common mobility bands suggest that the different salt bridges can stabilize similar structural motifs. In addition, the salt bridge influence on the MP-11 dimer formations was measured using collision induced dissociation and showed a strong dependence with the type of salt bridge ( i.e. , a CE 50 of 10.0, 11.5, 11.8 and 13.0 eV was observed for [2M + H] 3+ , [2M − H + NH 4 ] 3+ , [2M + Na] 3+ and [2M + K] 3+ , respectively). Measurements of the dimer equilibrium constant showed that the salt bridge interactions increase the binding strength of the dimeric species. 
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  3. Since the release of the Oculus Rift CV1 in 2016, millionsof VR headsets have found their way into consumer homes.In this paper, we sought to understand what shifts have takenplace within the two years since consumer VR became avail-able. In this paper, we consider what can be learned aboutlong-term use of consumer VR through an analysis of dis-cussions in online forums devoted to VR. We gathered postsmade on the /r/Vive subreddit from the first two years after theHTC Vive’s release. We present the results from an in-depthqualitative analysis concerning immersion, presence, and sim-ulator sickness. Over time, as users moved from passive toactive, their attitudes and expectations towards immersion andsimulator sickness matured. Major trends of interest foundwere game design implementation and locomotion techniques. 
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  4. Free, publicly-accessible full text available March 1, 2024
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