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Patterns of Richness and Endemism in the Gypsicolous Flora of Mexico
No full textGypsum soils occur around the world, mainly in arid regions. These harsh environments promote unusual flora with high degrees of endemism. Mexico has extensive gypsum outcrops, but their flora has been poorly studied. However, the highest species richness and endemism are expected to be concentrated in Mexico\u27s northern dry regions. To promote the study of this flora and its conservation, we estimate how well sampled it is, quantify species richness, identify centers of endemism, and detect which gypsum outcrops lie within federal protected natural areas (PNA). We conducted exhaustive literature and herbaria reviews to generate a database of botanical records on gypsum soils. The total species and gypsophyte richness were calculated using cell grids. Centers of endemism were identified using the corrected weighted endemism index (CWE). We mapped the gypsum outcrops within PNA polygons. The most collected sites are Cuatro Cienegas (Coahuila) and Santo Domingo Tonala (Oaxaca), which also had the highest total species richness. Nevertheless, gypsophyte richness was higher in Cuatro Cienegas and Nuevo Leon. The CWE identified seven gypsophyte centers of endemism. Mexico hosts the most diverse gypsophile flora in the world, despite having been only partially studied and collected. The regions with the highest species richness and endemism are unprotected
The genome of the glasshouse plant noble rhubarb (Rheum nobile) provides a window into alpine adaptation
No full textGlasshouse plants are species that trap warmth via specialized morphology and physiology, mimicking a human glasshouse. In the Himalayan alpine region, the highly specialized glasshouse morphology has independently evolved in distinct lineages to adapt to intensive UV radiation and low temperature. Here we demonstrate that the glasshouse structure - specialized cauline leaves - is highly effective in absorbing UV light but transmitting visible and infrared light, creating an optimal microclimate for the development of reproductive organs. We reveal that this glasshouse syndrome has evolved at least three times independently in the rhubarb genus Rheum. We report the genome sequence of the flagship glasshouse plant Rheum nobile and identify key genetic network modules in association with the morphological transition to specialized glasshouse leaves, including active secondary cell wall biogenesis, upregulated cuticular cutin biosynthesis, and suppression of photosynthesis and terpenoid biosynthesis. The distinct cell wall organization and cuticle development might be important for the specialized optical property of glasshouse leaves. We also find that the expansion of LTRs has likely played an important role in noble rhubarb adaptation to high elevation environments. Our study will enable additional comparative analyses to identify the genetic basis underlying the convergent occurrence of glasshouse syndrome.
A high-quality genome assembly and phylogenetic analysis for the glasshouse plant, Rheum nobile, shed light on its evolutionary history and ability to adapt to intensive UV radiation in a low-temperature, alpine environment
To Fluoresce or Not to Fluoresce: Investigation of Structural and Fluorescence Characteristics of CBI-Dopamine, CBI-Serotonin, and Their Structural Analogs
No full textDopamine (DA) and serotonin (5-HT) are neurotransmitters that are vital for proper brain function and are implicated in a wide variety of diseases and disorders. Unfortunately, quantitative analysis of DA and 5-HT is difficult, as they are present at low concentrations in complex biological matrices. The fluorogenic reaction of napththalene-2,3-dicarboxaldehyde (NDA) with a primary amine in the presence of cyanide (CN) creates an N-substituted 1-cyanobenz[f]isoindole (CBI) derivative, whose fluorescence can be sensitively monitored in biological matrices. Given their biological importance, there are surprisingly few reports showing fluorescence of CBI-DA and no prior publications concerning CBI-5-HT. In this work, nuclear magnetic resonance spectroscopy (NMR) was employed to determine the atom connectivity of over 10 CBI-products, including CBI-DA and CBI-5-HT. NMR and fluorescence spectroscopy were applied to CBI-DA, CBI-5-HT, and select structural analogs to determine structural correlations with the observed lack of fluorescence. Experiments with CBI-DA and structural analogs indicated fluorescence was rapidly quenched due to both complexation with the historically employed buffer and oxidation in solution. Fluorescence of CBI-DA was recovered by modifying the derivatization background to prevent complexation and oxidation. In contrast, fluorescence characterization of CBI-5-HT and its structural analogs indicated that 5-HT was acting as a quencher of the CBI-ring. The addition of acid to protonate 5-HT was found to disrupt this interaction and enable the first reported fluorescence detection of CBI-5-HT. In the future, this work will be applied to detect DA and 5-HT in biological systems to gain insight into neurobiological disease states and disorders
A self-dual complete resolution
No full textIn this paper, we construct a self-dual complete resolution of a module defined by a pair of embedded complete intersection ideals in a local ring. Our construction is based on a gluing construction of Herzog and Martsinkovsky and exploits the structure of Koszul homology in the embedded complete intersection case. As a consequence of our construction, we produce an isomorphism between certain stable homology and cohomology modules
Neural Mechanisms of Multisensory Attention: Impacts on Speech Perception
No full textVisual information plays a crucial role in audiovisual speech perception as demonstrated by the McGurk illusion. Previous research has shown that audiovisual speech integration is lessened under high attentional demands. Additionally, secondary visual versus auditory tasks have disparate effects on the likelihood of perceiving the McGurk illusion and may impact speech integration through separate mechanisms. However, differences in gaze patterns or the type of attention engaged may explain these differential effects. The current study seeks to determine whether the differential impact of auditory and visual distractors can be replicated for featural attention, specifically, and whether differences in gaze patterns are evident across secondary tasks. Participants completed a psychophysical task modeled after the McGurk effect in one of three conditions: 1) distractor-free, 2) secondary auditory task, 3) and secondary visual task. For the secondary task, participants were presented with a series of gray boxes (visual) or white noise bursts (auditory) and were asked to determine whether one of the gray boxes/white noise bursts was a higher or lower intensity. Thresholds for intensity judgments were determined for each participant using a psychophysical staircase procedure. Participants’ gaze was measured during distractor-free and high-load blocks. Preliminary results suggest that differences in gaze patterns are minimal between auditory and visual secondary tasks suggesting that modality effects on audiovisual speech integration are independent of looking behavior. This line of research has implications for understanding the differences in multisensory processing in developmental disorders which are commonly characterized by disruptions in attentional regulation