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from article Circadian clock (plants)
Three-module circadian clock system.
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from article Circadian clock (plants)
Model of the Arabidopsis circadian clock, showing light input (bold arrow), the central oscillator (large box), and output/response (tinted arrows). Light signals synchronize the clock via the cryptochromes (cry) and phytochromes (phy). These are…
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from article Gibberellins
ent-Gibberellane carbon skeleton showing the carbon numbering system and ring designations.
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from article Gibberellins
The GA-biosynthetic pathway in higher plants via 2-methylerythritol-4-phosphate (MEP). The biologically active end products of the pathway are GA1, GA3, and GA4. The general diterpene precursor trans-geranylgeranyldiphosphate (GGPP) is formed in…
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from article Gibberellins
Mechanisms for GA inactivation. C19-GAs and C20-GAs may be oxidized on C-2 by different classes of GA 2-oxidases (GA2ox). In rice, the enzyme ELONGATED UPPER INTERNODE (EUI) oxidizes the 16,17-double bond of non–13-hydroxylated GAs, such as GA4, to…
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from article Gibberellins
DELLA protein showing conserved domains, and a model for DELLA degradation via the SCF E3 ubiquitin ligase, which consists of a DELLA-specific F-box, Skp1, Cullin1 (CUL), and Rbx1 subunits. Binding of the GID1-GA complex to DELLAs promotes…
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from article Gibberellins
Model for GA-induced production of α-amylase in the aleurone of germinating cereal grains. GAs produced in the scutellum diffuse to the aleurone cells, where they stimulate transcription, processing, and secretion of α-amylase and other hydrolytic…
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from article Thirst and sodium appetite
Regulation of cellular water. ADH = antidiuretic hormone.
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from article Thirst and sodium appetite
Hypovolemic thirst and sodium appetite are caused by altered sensory information from an underfilled circulation, reinforced by increases in circulating angiotensin II and mineralocorticoids. Angiotensin peptides generated from components of a…
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from article Chlorophyceae
Chlorococcales. (a) Chlorococcum (Chlorococcaceae), vegetative cell; (b) cell with zoospores; (c) zoospores; (d) Hydrodictyon (Hydrodictyaceae), portion of coenobium; (e) portion enlarged; (f) Dictyosphaerium (Dictyosphaeriaceae), colony in…
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from article Chlorophyceae
Filamentous green algae with chlorophycean ultrastructure. (a) Microspora (Microsporales), showing H-shaped wall segments; (b) Sphaeroplea (Sphaeropleales); (c) Chaetophora (Chaetophorales), heterotrichous thallus (erect and prostrate systems).
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from article Chlorophyceae
Ulothrix (Ulotrichales).
Image
from article Chicxulub impact crater
Bouguer gravity anomaly map over the Chicxulub impact crater. The coastline is designated by a thin white line, cenotes (natural pits) and sinkholes are designated by black dots, and the city of Mérida and the town of Chicxulub Puerto are designated…
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from article Chicxulub impact crater
Seismic line imaging of what lies beneath the seafloor, showing the Chicxulub impact crater. The crater includes many faults that can be grouped into an exterior ring fault, a series of outer ring faults, and a series of inner ring faults. Within…
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from article Osage orange
Fruit and foliage of osage orange (Maclura pomifera). (Photo copyright © Karren Wcisel)
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from article Bryopsidales
Anatomical structures of selected members of Bryopsidales. (a) Dichotomosiphon, filament with oogonia and antheridia. (b) Ostreobium, filaments. (c) Caulerpa, section of filament showing trabeculae. (d) Codium, group of utricles with gametangia and…
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from article Bryopsidales
Representative members of Bryopsidales. (a) Bryopsis; (b) Caulerpa; (c) Penicillus; (d) Halimeda; (e) Codium.
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from article Graptolithina
Sketches of portions of pterobranch and graptolite colonies showing the dwelling tubes and the constructional units of the graptolite skeleton. (a) Young Rhabdopleura compacta colony with founder zooid and first asexual bud (Recent). Benthic…
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from article Graptolithina
Scanning electron micrograph of a graptolite (Pseudoclimacograptus scharengergi) showing the fuselli (horizontal ridges) that compose graptolite thecae, and the cortical bandages (oblique strips) that were deposited on top of the fuselli (Middle…
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from article Graptolithina
Hypothetical form of zooids that inhabited colony tubes, based on a planktic graptolite. Large zooids are shown with possible oarlike swimming organs used to move the colony through the ocean water and tentacles for feeding. Also shown are two…
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from article Graptolithina
Examples of some planktic graptolites, reconstructed to show three-dimensional form.
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from article Plant vulnerability to climate change
Subarctic tundra and vegetation of the Denali National Park and Preserve in Alaska. As a result of climate change and the resultant poleward and upward shift of plant ranges, plants and their ecosystems may become particularly vulnerable. (Credit:…
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from article Plant vulnerability to climate change
Blue grama (Bouteloua gracilis) growing in Montana. As a result of warming temperatures, this type of grass could face decreased productivity, allowing forbs to increase and making the ecosystem less tolerant of drought and grazing. (Credit: Matt…
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from article Plant vulnerability to climate change
Modeled distribution of suitable climate space in Europe for stiff sedge (Carex bigelowii), which is an Arctic-Alpine plant: (a) during the period 1961–1990 (green color = suitable climate space during the 1961–1990 period); (b) climate model…
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from article Plant vulnerability to climate change
The endangered western prairie fringed orchid (Platanthera praeclara) is declining across much of its range in North America. (Credit: U.S. Fish and Wildlife Service)
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from article Plant juvenility
The basic miRNA, siRNA, and ta-siRNA pathways in plants. The enzymes that carry out the different steps are written to the right of the downward arrows. The miRNA pathway schematic shows processing of the hairpin into an miRNA:miRNA* duplex by the…
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from article Plant juvenility
The developmental expression patterns of genes that regulate vegetative phase change. This graph is meant to show only the changes in expression for each gene during development rather than actual expression levels or relative levels between genes.
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from article Rosemary
Leaves of rosemary (Rosmarinus officinalis). (Photograph courtesy of Forest and Kim Starr)
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from article Palaeonisciformes
Mimia toombsi (Gardiner & Bartram, 1977), Late Devonian, Gogo, Australia. One of the earliest palaeonisciforms, reaching 15 cm (6 in.) long, and known by complete fossils. (Reprinted with permission from B. G. Gardiner, The relationships of the…
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from article Palaeonisciformes
Chirodus granulosus (Young, 1866) was a deep-bodied palaeonisciform that grew to 10 cm (4 in.) and lived in Carboniferous coal swamps of Britain. The teeth formed cutting blades that may have been used to crop vegetation. This reconstruction is…
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from article Squash
Zucchini (Cucurbita pepo), a type of summer squash, with flowers. (Credit: Howard F. Schwartz, Colorado State University/www.Bugwood.org)
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from article Squash
Crookneck squash (Cucurbita moschata). (Credit: Howard F. Schwartz, Colorado State University/www.Bugwood.org)
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from article Squash
Delicata squash (Cucurbita pepo), a variety of winter squash. (Credit: Shaun Case)
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from article Squash
Leaves of Cucurbita pepo infected by a squash mosaic virus. (Credit: William M. Brown, Jr./www.Bugwood.org)
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from article Speech
Human head and thorax. (Courtesy of G. E. Peterson)
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from article Speech
Action of the glottis during speech. (a) Six successive positions of the vocal folds in one vibration cycle at 120 Hz. (b) Relation between pitch and vocal fold tension. (Courtesy of D. W. Farnsworth)
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from article Speech
Sound spectrograms of the utterance “speech production.” (a) Energy patterns: A, pulse; B, periodic; C, aperiodic; and D, silence. (b) The dotted lines represent the pitch pattern of the utterance.
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from article Speech
Computer-generated three-dimensional spectral display of the spoken syllable “yah.”
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from article Speech
Speech flakes of vowels in the words (a) “far,” (b) “food,” and (c) “fee.” (Courtesy of Charles Wooters)
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from article Speech
Regions of the brain involved in speech. (a) Left hemisphere, usually more involved in speech functions than the right hemisphere. (b) A model for the neural processes involved in speaking a heard word. Arrows indicate the path of the relayed signal…
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from article Dormancy
Viviparous seeds of maize (Zea mays) germinating on the cob because of a mutation (vp14) preventing abscisic acid synthesis. (From S. H. Schwartz and J. A. D. Zeevaart, Abscisic acid biosynthesis and metabolism, pp. 137–155, in P. J. Davies, ed.,…
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from article Phaeophyceae
Embryonic sporophyte of Desmarestia anceps, showing trichothallic growth resulting in an embryonic stipe and several pairs of embryonic branches.
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from article Cladoselache
Cladoselache fyleri, from the Upper Devonian of Cleveland. (After S. E. Bendix-Algreen, 1975)
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from article Paleocopa
Paleocopa. (a) Ogmoopsis nodulifera, left valve; from the Ordovician of Sweden. (b) Eurychilina subradiata, right valve showing wide complete frill; Ordovician of Minnesota. (c) Sulcicuneus porrectinatium, male and female carapaces; Devonian of…
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from article Mental disorders
X-ray of a human brain (side view) against a black background. The image is transparent and detailed with soft blue swaps. (Credit: Brainmaster/Getty Images)
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from article Mental disorders
Colorized CT (computerizd tomography) scan of a healthy brain (view from above). The axial (horizontal) scan has revealed the head and brain in cross section. The front of the head is at the top. The ventricles (dark areas, center), which lie…
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from article Coriander
Coriander seeds (Coriandrum sativum). (Photograph courtesy of Steve Hurst, USDA–NRCS PLANTS Database)
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from article Strawberry
June-bearing strawberries (Fragaria × ananassa), which are produced in early summer. (Photo courtesy of Kimberly Lewers, Agricultural Research Service, United States Department of Agriculture)
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from article Strawberry
Botrytis cinerea fungal sporulation on a ripe strawberry. (Photo courtesy of Scott Bauer, Agricultural Research Service, United States Department of Agriculture)
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from article Scrophulariales
Flowers of the common snapdragon (Antirrhinum majus), a typical member of the family Scrophulariaceae in the order Scrophulariales (Lamiales). (Photo by Ondřej Zicha, BioLib, Czech Republic)
