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1,418 results for “Grasses”
Grass veins are leaky pipes: Vessel widening in grass leaves explain variation in stomatal conductance and vessel diameter among species
<p>The widening of xylem vessels from tip-to-base of trees is an adaptation to minimize the hydraulic resistance of a long pathway. Given that parallel veins of monocot leaves do not branch hierarchically, vessels should also widen basipetally but, in addition to minimizing resistance, should also account for water volume lost to transpiration since they supply water to the lamina along their lengths, i.e. "leakiness".</p> <p>We measured photosynthesis, stomatal conductance, and vessel diameter at 5 locations along each leaf of 5 perennial grass species.</p> <p>We found that the rate of conduit widening in grass leaves was larger than the widening exponent required to minimize pathlength resistance (0.35 vs. ~0.22). Furthermore, variation in the widening exponent among species was positively correlated with maximal stomatal conductance (r<sup>2 </sup>= 0.20) and net CO<sub>2</sub> assimilation (r<sup>2</sup> = 0.45).</p> <p>These results suggest that faster rates of conduit widening (>0.22) were associated with higher rates of water loss. Taken together, our results show that the widening exponent is linked to plant function in grass leaves and that natural selection has favored parallel vein networks that are constructed to meet transpiration requirements while minimizing hydraulic resistance within grass blades.</p>
Fig. 7 in Comparative spermatozoa ultrastructure of neotropical grass frogs (genus Leptodactylus) with comments on anuran reproductive modes and phylogeny
Fig. 7. Optimization of ultrastructural characters (characters 6 to 8, and 11 to 13) of the spermatozoa on a pruned phylogenetic hypothesis for Leptodactylidae. See list of characters and bibliographic sources in Table 3. Colors correspond to: gray, ambiguity; blue, state 0; red, state 1.
Fig. 8 in Comparative spermatozoa ultrastructure of neotropical grass frogs (genus Leptodactylus) with comments on anuran reproductive modes and phylogeny
Fig. 8. Taxonomic distribution and optimization of 11 selected ultrastructural characters of the spermatozoa on the phylogenetic hypothesis of Leptodactylus proposed by de S´a et al. (2014) and subsequent modifications (see materials and methods section). Numbers refer to characters described in Results section.
Fig. 6 in Comparative spermatozoa ultrastructure of neotropical grass frogs (genus Leptodactylus) with comments on anuran reproductive modes and phylogeny
Fig. 6. Optimization of reproductive modes and ultrastructural characters (characters 1 to 5) of the spermatozoa on a pruned phylogenetic hypothesis for Leptodactylidae (see section "Optimization" in Materials and Methods). See list of characters and bibliographic sources in Tables 1 and 3 Colors correspond to: gray, ambiguity; blue, state 0; red, state 1; green, state 2; orange, state 3; black, state 4.
Fig. 4 in Comparative spermatozoa ultrastructure of neotropical grass frogs (genus Leptodactylus) with comments on anuran reproductive modes and phylogeny
Fig. 4. Transmission electron microscopy of spermatozoa of species of the Leptodactylus melanonotus group. A: L. melanonotus. LS of the acrosomal vesicle and nuclei (n). Note the long and thick acrosomal vesicle (av) and the reduced sub-acrosomal space (ss). B: L. validus. TS showing acrosomal vesicle (ac) and nuclei (n) at different levels. Note the thickness of the acrosomal vesicle and of the acrosomal space. The conical shape of the nucleus is observed in the different cross-sections. C: L. podicipinus. LS of the acrosomal complex-nuclei (n), with the organelle-free cytoplasmic region (black arrowhead) present. D. L. wagneri. LS of the posterior region of the nucleus (n), showing the asymmetrical nuclear fossa (nf) and the transverse striations (ts). E: L.validus. LS of the posterior nuclear region. Note the symmetrical fossa with the proximal (pc) and distal (dc) centrioles. F: L. wagneri. TS of the axoneme (a) and paraxonemal rod (pr) separated from the mitochondrial collar (mc) by the cytoplasmic canal (cc). G-H: L. wagneri, L. melanonotus. TSs of the tail showing the axoneme (a) associated to the juxtaxonemal fiber (jf), and the axial fiber (af) attached to the other components of the tail by the undulating membrane (o). I: L. leptodactyloides. Terminal region of the tail where the axoneme (a) is the only element of the tail. Scales bars: C, D, H, I = 0.5 µm; A, E-G = 0.2 µm; B = 1 µm.
Fig. 1. A-B in Comparative spermatozoa ultrastructure of neotropical grass frogs (genus Leptodactylus) with comments on anuran reproductive modes and phylogeny
Fig. 1. A-B: Schematic reconstruction of the morphology of the two types of spermatozoa observed in the genus Leptodactylus. Note that the main difference between the two morpho-types is the presence of the organelle-free cytoplasmic region between the acrosomal vesicle and the other end of the nucleus. Dashed lines indicate the cross-section represented on the right-hand side of the image.
Cathedral Notre-Dame-du-Puy of Grasse
A kathedral i build for a leveldesign conception for university. The model should be as close to the original as possible. Created with Autodesk Maya Source: Objaverse 1.0 / Sketchfab
Annotated Mature Black-grass dataset
<p>Data collected in Bozeat, Wellingborough. W3W co-ordinates table below. Not all available images were annotated so some co-ordinates may not be represented.</p> <table> <tbody> <tr> <td> <p>W3W</p> </td> <td> <p>loc</p> </td> </tr> <tr> <td> <p>workbook.legs.universe</p> </td> <td> <p>Bozeat</p> </td> </tr> <tr> <td> <p>requires.boating.nerves</p> </td> <td> <p>Bozeat</p> </td> </tr> <tr> <td> <p>rekindle.cheaper.clumped</p> </td> <td> <p>Bozeat</p> </td> </tr> <tr> <td> <p>worksheet.flannel.scarf</p> </td> <td> <p>Bozeat</p> </td> </tr> <tr> <td> <p>horn.wooden.presuming</p> </td> <td> <p>Bozeat</p> </td> </tr> <tr> <td> <p>spinning.footpath.cowering</p> </td> <td> <p>Bozeat</p> </td> </tr> <tr> <td> <p>wasps.untruth.lifestyle</p> </td> <td> <p>Bozeat</p> </td> </tr> <tr> <td> <p>spacing.refilled.deduced</p> </td> <td> <p>Bozeat</p> </td> </tr> <tr> <td> <p>worth.plankton.relay</p> </td> <td> <p>Bozeat</p> </td> </tr> <tr> <td> <p>magically.crypt.amending</p> </td> <td> <p>Bozeat</p> </td> </tr> <tr> <td> <p>briskly.selection.opera</p> </td> <td> <p>Bozeat</p> </td> </tr> </tbody> </table>
Annotated Black-grass Seedling Dataset
<p>Images taken from Kaggle dataset: https://www.kaggle.com/datasets/vbookshelf/v2-plant-seedlings-dataset</p> <p>Relevant paper discussing creation of Kaggle dataset: https://arxiv.org/abs/1711.05458</p> <p> </p>
Native ants help to spread an invasive African grass in the Cerrado
<p><span>Plant-animal interactions may facilitate biological invasions. The African grass </span><i>Urochloa decumbens</i> is an aggressive invader in the Cerrado. We demonstrate that native ants are dispersing the seeds to short distances, allowing the gradual spread of the invasive to sites without the need of great anthropogenic soil disturbances.</p>
Interactions between silicon and alkaloid defences in endophyte-infected grasses and the consequences for a folivore
<p>1. Grasses have developed a wide range of morphological and physiological mechanisms to resist herbivory. For instance, they accumulate silicon (Si) in tissue, as physical defence, and associate symbiotically with foliar <i>Epichloë</i>-endophytes that provide chemical defence <i>via</i> antiherbivore alkaloids. Recent evidence showed that some <i>Epichloë</i>-endophytes increase foliar Si in forage grasses; however, it is unknown whether this impacts insect herbivores. Furthermore, while Si is primarily a physical defence, it also affects production of plant defensive secondary metabolites; Si supply might therefore affect <i>Epichloë</i>-alkaloids, although this remains untested.</p> <p>2. We grew endophyte-free (Nil) and <i>Epichloë</i>-infected tall fescue and perennial ryegrass in a factorial combination with or without Si supplementation, in the absence or presence of <i>Helicoverpa armigera</i>. <i>Epichloë</i>-endophyte strains were AR584 for tall fescue, and AR37, AR1 or Wild-type (WT) for perennial ryegrass. We assessed how Si supply and <i>Epichloë</i>-endophytes in interaction with herbivory affected foliar Si and mutualist-derived alkaloid concentrations. Subsequently, their effects on <i>H. armigera</i> relative growth rates (RGR) were evaluated. </p> <p>3. Endophytes generally increased Si concentrations in Si supplied plants.<b> </b>In tall fescue-AR584 and perennial ryegrass-AR37, endophytes increased constitutive (herbivore-free) and induced (herbivore-inoculated) Si concentrations by at least 25%; in contrast, in perennial ryegrass the AR1 endophyte only increased constitutive levels. Si supply did not affect alkaloids produced by AR584- or AR1/WT-endophytes; however, in the presence of herbivory, Si supply decreased the induction of alkaloids produced by AR37 endophytes by 33%. For tall fescue, Si supply reduced <i>H. armigera</i> RGR by at least 76%, regardless of endophytic status, whereas, endophyte-alkaloids played a secondary role only reducing herbivore growth in the absence of Si supply. Conversely, in perennial ryegrass both Si and endophyte-alkaloids (regardless of Si supply) reduced herbivore RGR although not synergised. </p> <p>4. Novel interactions between constitutive and induced Si- and alkaloid-based antiherbivore defences in grasses were observed. Overall, Si had a greater effect on the folivore than endophytes in both grasses. Endophyte-defences contributed more to herbivore resistance in perennial ryegrass than tall fescue. We demonstrate that Si and endophytes were not antagonistic and highlight that the protective nature of their interaction varies with the grass-endophyte species tested.</p>
Fig. 5. Combined ITSand trnT-F phylogenybasedonmaximum parsimonyand Bayesian inference. Shadedsectionof thetree highlightsspecies with x in Canary grasses (Phalaris, Poaceae): Molecular phylogenetics, polyploidy and floret evolution
Fig. 5. Combined ITSand trnT-F phylogenybasedonmaximum parsimonyand Bayesian inference. Shadedsectionof thetree highlightsspecies with x = 6, and names shown in bold denote polyploid species. * = nodes collapsed in the strictconsensus maximum parsimony tree. • = unknown chromosome number. Floret types follow the structure defined in Fig. 2. A = annual and P = perennial habit.
Fig. 4. trnT-F in Canary grasses (Phalaris, Poaceae): Molecular phylogenetics, polyploidy and floret evolution
Fig. 4. trnT-F phylogram generated from Bayesian inference. Parsimony bootstrap results are above branches and Bayesian posterior probabilities are below. Shaded section of the tree highlights species with x = 6, and names shown in bold denote polyploid species. * = clade collapsed in the strict consensus maximum parsimony tree. • = unknown chromosome number. Floret types follow Fig. 2. A = annual and P = perennial habit.
Fig. 2 in Canary grasses (Phalaris, Poaceae): Molecular phylogenetics, polyploidy and floret evolution
Fig. 2. Adiagrammatic illustrationof sixfloret typesrecognizablein speciesof Phalaris following Anderson (1961) and Baldini (1995). Notethe central fertile floret and the two lateral sterile lemmas that display successive reduction in size.
FIGURE 2 in Agrostis barikii (Poaceae: Agrostidinae), a new grass species from Western Himalaya, India
FIGURE 2. Agrostis barikii; A. Base of the plant showing the habit caespitose. B. Ligule. C. Panicle. D. Spikelet with floret separated from the glumes, lateral view. E. Floret, lateral view. F. Palea, ventral view. G. Anthers. H. Caryopsis in dorsal (left) and ventral (right) views. [Illustration from P. Agnihotri et al. 326659 (LWG); drawn by Mr. Akash Verma].
FIGURE 1. Agrostis barikii. A. Ligule. B–C. Spikelets, lateral view. D–E. Spikelet with floret separated from the glumes. F in Agrostis barikii (Poaceae: Agrostidinae), a new grass species from Western Himalaya, India
FIGURE 1. Agrostis barikii. A. Ligule. B–C. Spikelets, lateral view. D–E. Spikelet with floret separated from the glumes. F. Floret in dorsal view showing the well-developed awn, G. Floret in lateral view showing the awn, the lemma glabrous at the apex, and the palea. H. Palea, ventral view. I. Anthers. J–K. Caryopsis, dorsal (left) and ventral (right) views. [Photographs from P. Agnihotri et al. 326659 (LWG)].
Hybridisation boosts dispersal of two contrasted ecotypes in a grass species
<p>Genetic exchanges between closely related groups of organisms with different adaptations have well-documented beneficial and detrimental consequences. In plants, pollen-mediated exchanges affect the sorting of alleles across physical landscapes, and influence rates of hybridisation. How these dynamics affect the emergence and spread of novel ecological strategies remains only partially understood. Here, we use phylogenomics and population genomics to retrace the origin and spread of two geographically overlapping ecotypes of the African grass <i>Alloteropsis angusta</i>. Besides an ecotype inhabiting wetlands, we report the existence of a previously undescribed ecotype inhabiting miombo woodlands and grasslands. The two ecotypes are consistently associated with different nuclear groups, which represent an advanced stage of divergence with secondary low-level gene flow. However, the seed-transported chloroplast genomes are consistently shared by distinct ecotypes inhabiting the same region. These patterns suggest that the nuclear genome of one ecotype can reach the seeds of the other via occasional pollen movements with sorting of nuclear groups in subsequent generations. The contrasting ecotypes of <i>A. angusta</i> can thus use each other as a gateway to new locations across a large part of Africa, showing that hybridisation can facilitate the geographical dispersal of distinct ecotypes of the same grass species.</p>
Data from: Loss of fungal symbionts at the arid limit of the distribution range in a native Patagonian grass – resource ecophysiological relations
<p>1. Crucial to our understanding of plant ecology is the consideration of the eco-physiological responses and constraints of plant-fungal symbioses throughout the native distribution range of their host.</p> <p>2. We examined key eco-physiological roles of two co-occurring fungal symbionts [Epichloë endophytes and arbuscular mycorrhizal fungi (AMF)] in the endemic grass Hordeum comosum across a wide bioclimatic gradient and contrasting grazing severity. We sampled H. comosum plants along four humid-to-arid transects in Patagonia, Argentina, covering its entire distribution range and determined Epichloë presence, AMF root colonization, nitrogen and phosphorus concentration, intrinsic water use-efficiency (iWUE, the ratio of photosynthesis to stomatal conductance) and 18O-enrichment of cellulose in shoots.</p> <p>3. Root colonization by AMF increased with Epichloë-presence. All plants hosted Epichloë in the humid range of the gradient, but symbioses occurrence decreased towards arid sites which also displayed severe grazing symptoms at site level.</p> <p>4. Symbiosis with Epichloë correlated positively with shoot nitrogen concentration in the centre of the distribution range, and with shoot phosphorus concentration across the entire distribution range.</p> <p>5. The site-level relationship of AMF colonization with 18O-enrichment and iWUE suggested that mycorrhiza boosted stomatal conductance in humid environments but curbed it in arid environments.</p> <p>6. While the interpretation of interactions and potential causalities from observational studies should be done with caution, this study demonstrates distinct correlations between plant-fungal symbiont associations and key resource parameters (phosphorus, nitrogen, and iWUE vs 18O-enrichment). Such correlations may suggest particular functional roles for these symbionts in the ecology of their host plant.</p>
Traits explain sorting of C4 grasses along a global precipitation gradient
<p>Species distributions are closely associated with moisture availability, but the underlying mechanisms remain unresolved. Drought relations are especially important for plants such as C<sub>4</sub> grasses that dominate seasonally dry ecosystems. Here, we test the hypothesis that C<sub>4</sub> grass species sampled across global precipitation gradients show variation in survival under drought that can be explained by their traits. Our experiment subjected 18 C<sub>4</sub> grass species to a lethal drought under controlled environmental conditions. The number of days until death was measured, along with root traits, senescence and aspects of hydraulic function. <span><span>We identified two strategies; Drought avoiding species that stayed green as the water potential declined, and drought tolerating species that senesced more quickly but could extend survival via drought tolerant meristems. </span></span><span><span>Plants that stay-green for longer occupied drier habitats and had the longest survival under drought, facilitated by narrow root diameter and isohydric stomatal behaviour. Plants that senesced quickly had thicker roots, an anisohydric strategy, and occupied wetter habitats.</span></span> Global distributions of C<sub>4</sub> grasses can be predicted by variation in rates of senescence, meristem survival, root traits and stomatal strategy, showing the value of these traits for understanding plant distributions in relation to climate.</p>
Tracking the ancestry of known and 'ghost' homeologous subgenomes in model grass Brachypodium polyploids
<p>Unraveling the evolution of plant polyploids is a challenge when their diploid progenitor species are extinct or unknown or when genome sequences of known progenitors are unavailable. Existing subgenome identification methods cannot adequately infer the homeologous genomes that are present in the allopolyploids if they do not take into account the potential existence of unknown progenitors. We addressed this challenge in the widely distributed dysploid grass genus <i>Brachypodium,</i> which is a model genus for temperate cereals and biofuel grasses. We used a transcriptome-based phylogeny and newly designed subgenome detection algorithms coupled with a comparative chromosome barcoding analysis. Our phylogenomic subgenome detection pipeline was validated in <i>Triticum</i> allopolyploids, which have known progenitor genomes, and was used to infer the identities of three subgenomes derived from extant diploid species and four subgenomes derived from unknown diploid progenitors (ghost subgenomes) in six <i>Brachypodium</i> polyploids (<i>B. mexicanum, B. boissieri, B. retusum, B. phoenicoides, B. rupestre, and B. hybridum</i>), of which five contain undescribed homeologous subgenomes. The existence of the seven <i>Brachypodium</i> progenitor genomes in the polyploids was confirmed by their karyotypic barcode profiles. Comparative phylogenomics of nuclear vs plastid trees allowed us to formulate hypothetical homoploid hybridizations and allo- and autopolyploidization scenarios that could have generated the six <i>Brachypodium</i> polyploids.</p>
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.