The pollination mechanism of Abies amabilis

2004 ◽  
Vol 34 (5) ◽  
pp. 1071-1080 ◽  
Author(s):  
Luke M Chandler ◽  
John N Owens
Keyword(s):  
Electron Microscopy ◽  
Epicuticular Wax ◽  
Pollination Mechanism ◽  
Abies Amabilis ◽  
Cone Axis ◽  
Inner Surface ◽  
Pollination Drop ◽  
And Function ◽  
Scale Surface ◽  
Scanning Electron

The development and function of the pollination mechanism were studied in Abies amabilis (Dougl. ex Loud.) Dougl. ex J. Forbes growing in clonal seed orchards. Two adaxial ovules developed on each scale after dormancy and each ovule formed a funnel-like integument tip with a nucellus at the base of the shallow funnel. At receptivity, the seed cones were erect and the ovules inverted. No pollination drop was observed in fresh specimens but lipid microdrops were secreted on the rim and inner surface of the funnel. Water applied as spray beaded on all cone surfaces except where microdrops were present. Surfaces of the cone were observed using scanning electron microscopy to determine the presence and ultrastructure of the waxy cuticle. All surfaces that were not wettable with water were covered with epicuticular wax. Pollen did not adhere firmly to cone surfaces having epicuticular wax but adhered to the microdrops on the funnel. Drops of water picked up pollen as they moved over the waxy surfaces toward the cone axis. There, the inverted ovules were arranged in a tight helix around the cone axis. Beads of water, often containing pollen, settled on the scale surface just below the funnels and then touched and wetted the inside of the funnels, forming a column of water from the scale surface below to the funnel above. The saccate, buoyant pollen then floated up and into the funnel. Experiments were done to determine the effect of pollen application on pollen uptake into the ovule: without water, with water applied before or after pollen was applied, or as a pollen–water mix. Results support the hypothesis that A. amabilis, and likely other Abies species, lacks a conspicuous pollination drop and water as rain or dew substitutes for a pollination drop.

Scanning electron microscopy of the operculum of Garra lamta (Hamilton) (Cyprinidae:Cypriniformes), an Indian hill stream fish

2010 ◽  
Vol 58 (3) ◽  
pp. 182 ◽  
Author(s):  
Swati Mittal ◽  
Usha Kumari ◽  
Pinky Tripathi ◽  
Ajay Kumar Mittal
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Epithelial Cells ◽  
Goblet Cells ◽  
Stream Fish ◽  
Male And Female ◽  
Fish Breeding ◽  
Inner Surface ◽  
Garra Lamta ◽  
Scanning Electron

The surface architecture of the epidermis on the outer surface of the operculum (OE) and the epithelium on the inner surface of the operculum (EISO) of Garra lamta was examined by scanning electron microscopy. The surface appeared smooth on the OE and wavy on the EISO. A wavy epithelium is considered to facilitate an increase in its stretchability, during the expansion of the branchial chamber. The OE and the EISO were covered by a mosaic pavement of epithelial cells with characteristic patterns of microridges and microbridges. Interspersed between the epithelial cells were mucous goblet cell pores, which were not significantly different in number in the OE and the EISO. Nevertheless, their surface area in the EISO was significantly higher than in the OE. This could be an adaptation to secrete higher amounts of mucus on the EISO for keeping the branchial chamber lining clean, avoiding clogging, the increased slipperiness reducing friction from water flow and increased efficiency in protecting against microbial attachments. Rounded bulges on the OE and the EISO were associated with mucous goblet cells. The absence of the taste buds in the EISO, in contrast to the OE, suggests that their function in the branchial chamber may not be of much significance in this fish. Breeding tubercles on the OE are believed to facilitate better contact between the male and female during breeding.

Surfactant-Induced Phytotoxicity

1994 ◽  
Vol 8 (3) ◽  
pp. 519-525 ◽  
Author(s):  
Richard H. Falk ◽  
Richard Guggenheim ◽  
Gerhard Schulke
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Tissue Damage ◽  
Epicuticular Wax ◽  
Morphological Alteration ◽  
Epicuticular Waxes ◽  
Common Purslane ◽  
Morphology Changes ◽  
Cryo Scanning Electron Microscopy ◽  
Scanning Electron

The leaves of tall morningglory, giant duckweed, and common purslane were treated with nine surfactants at a concentration of 0.1% and examined after 24 hr using cryo-scanning electron microscopy for phytotoxicity as evidenced by tissue damage and epicuticular wax morphology changes. In some instances, tissue damage could be discerned; however, the effects of a particular surfactant were not uniform across the three species. Morphological alteration of epicuticular waxes was not observed. Gas chromatographic analyses of the epicuticular waxes of the species used in the study reveal component differences and may, in part, explain the lack of uniform response across species for a particular surfactant.

Feeding Structures and their Functions in Adult and Preadult Tigriopus Californicus (Copepoda: Harpacticoida)

1998 ◽  
Vol 78 (2) ◽  
pp. 451-466 ◽  
Author(s):  
A.G. Lewis ◽  
L. Chatters ◽  
M. Raudsepp
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Structure And Function ◽  
Energy Dispersive ◽  
Tigriopus Californicus ◽  
X Ray ◽  
Faecal Pellets ◽  
Spinous Processes ◽  
And Function ◽  
Scanning Electron

Tigriopus californicus uses several appendages and processes in the collection and manipulation of food. Their structure and function appear to enable the species to utilize the variety of food materials found in splashpools, including: detritus and organic floes; superficial material on particles; faecal pellets; protists; diatoms; and small crustaceans. From light and scanning electron microscopy and video, the labrum and labium appear to be adapted for biting soft and hard food materials and holding food for trituration by the mandibles. From energy dispersive X-ray spectra, the gnathobase of the mandible is suggested to be sclerotized but not calcified or silicified. It has an array of bilobate and multilobate teeth, clusters of spinous processes, and a heavy, spine-bearing process to move food into the oesophagus. There is also a flange which articulates in a groove in the labrum which appears to provide a guide for the gnathobase as it moves vertically.

Fe-Sem Observations on the Microfibrillar Orientation in the Secondary Wall of Tracheids

IAWA Journal ◽  
1991 ◽  
Vol 12 (4) ◽  
pp. 431-438 ◽  
Author(s):  
Hisashi Abe ◽  
Jun Ohtani ◽  
Kazumi Fukazawa
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Field Emission ◽  
Secondary Wall ◽  
Abies Sachalinensis ◽  
Clockwise Direction ◽  
Inner Surface ◽  
Scanning Electron

Field emission scanning electron microscopy was used to observe the inner surfaces of the developing secondary walls of earlywood tracheids of Abies sachalinensis Masters. Microfibrillar orientation in the secondary wall, as seen from the lumen side, changed in a clockwise direction from the outermost S1 to the middle of the S2 and from there counter-clockwise to the innermost S3. Sometimes microfibrils oriented in a steep S-helix were observed in the S3 layer. Lamellae showing different microfibrillar orientations in wall layers other than the S2 were observed beneath newly deposited microfibrils on the inner surface of the developing wall. Furthermore, on the inner surface of the wall forming the S12, S23 and S3, lamellae with microfibrils closely aligned at the same angle as one another and lacking spaces were not observed. These observations suggest that in layers other than the S2 most lamellae are not composed of closely spaced microfibrils.

Postdormancy seed-cone development and the pollination mechanism in western hemlock (Tsugaheterophylla)

1989 ◽  
Vol 19 (1) ◽  
pp. 44-53 ◽  
Author(s):  
Anna M. Colangeli ◽  
John N. Owens
Keyword(s):  
Pollen Grains ◽  
Pollen Tubes ◽  
Epicuticular Wax ◽  
Western Hemlock ◽  
Bud Burst ◽  
Pollination Mechanism ◽  
Seed Cone ◽  
Cone Development ◽  
And Function

The development and function of the pollination mechanism is described for hemlock (Tsugaheterophylla (Raf.) Sarg.). Controlled pollinations at various stages following bud burst were used to define the period of maximum receptivity. Western hemlock has a pollination mechanism unlike that observed in other native conifers. The pollen grains were not taken into the micropyles; instead, the roughly sculptured pollen grains adhered to the long epicuticular wax covering the bracts. Seed cones became receptive to pollen soon after the bracts emerged from the bud scales and remained receptive until shortly before cone closure. Several days after the cones fully emerged beyond the bud scales, the ovuliferous scales elongated over the bracts, trapping the pollen between the bracts and scales. Several weeks after pollination, pollen germinated on the bracts and formed long pollen tubes which grew towards and into the micropyles.

scholarly journals Histological Variation in Plethodontid Digital Surfaces [University of Findlay]

2019 ◽  
Author(s):  
Megan Pasternak ◽  
Justin Rheubert
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Surface Morphology ◽  
Light Microscopy ◽  
Morphological Evolution ◽  
Ventral Surface ◽  
Cellular Level ◽  
Plethodontid Salamanders ◽  
And Function ◽  
Scanning Electron

Despite numerous investigations into the morphology and function of toe pads in many species, most notably anurans and geckonids, there is relatively little knowledge on salamander digit morphology. To date, toe morphology in salamanders has been limited to Desmognathus fuscus, Ambystoma maculatum, Bolitoglossa sp., and Aneides aeneus. The limited studies to date have shown variation inter- and intra-specifically but have not investigated numerous taxa within a given family which may provide deeper insights into the causes of variation (phylogenetic vs ecological pressures). Therefore, to test hypotheses concerning the presence of variation in the ventral digital surface of plethodontid salamanders, we plan to use various microscopy methodologies to view the ventral surface of the digital tips of three species from three different genera within the Plethodontidae: Desmognathus, Eurycea, and Plethodon. Toe pads will be characterized grossly using scanning electron microscopy, histologically using light microscopy, and ultrastructurally using transmission electron microscopy. Preliminary results suggest that all three species investigated display enlarged surfaces. Surface morphology (assessed via scanning electron microscopy) varies between species at a gross level concerning the shape and overall orientation of the enlarged surface. Surface morphologies include a well-developed circular pad (D. fuscus), a well-developed oval pad (P. cinereus), and a poorly developed circular pad (E. cirrigera). Furthermore, surface morphology appears to vary at the cellular level as well, with Desmognathus having polygonal squamous cells with microprojections and Eurycea having polygonal cells with nanopillars in a honeycomb arrangement. These differences may be attributed to differences in habitat preference as the three species tested include a terrestrial, semi-aquatic, and aquatic dwelling species. However, further investigation including light microscopy and enhanced scanning electron microscopy are needed. Further understanding of the morphological variation will aid in our understanding of ecomorphology and understanding of morphological evolution in amphibians.

Micro- and Nanostructures of Calcareous Foraminiferal Tests: Insight from Representatives of Miliolida, Rotaliida and Lagenida

2018 ◽  
Vol 48 (2) ◽  
pp. 142-155 ◽  
Author(s):  
Zofia Dubicka ◽  
Krzysztof Owocki ◽  
Michał Gloc
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fiber Bundles ◽  
Calcite Crystal ◽  
Crystal Fiber ◽  
Phylogenetic Reconstructions ◽  
Inner Surface ◽  
Molecular Phylogenetic ◽  
Scanning Electron ◽  
Taxonomic System

Abstract The test structures of Lagenida, Rotaliida, and Miliolida (Foraminifera) are described at an unprecedented scale of resolution. Observations using conventional and field-emission scanning electron microscopy revealed distinct micro- and nanoscale differences in the textural compositions of these three main groups of calcifying foraminifers, consistent with recent molecular phylogenetic reconstructions and a higher-level taxonomic system. The rotaliid test is entirely composed of roughly spherical primary carbonate nanograins, up to 100 nm in diameter, which merge into micrometer-sized irregular aggregates. The miliolid test is made up of two morphologically different primary crystallites. Arbitrarily arranged needle-shaped elements (up to 1 µm in length and 200 nm in width) make up the bulk of the test, including the inside of the wall (porcelain) and mineralized inner surface (intrados) (ca. 100 nm in thickness). Roughly spherical nanograins (up to 50 nm in diameter) form more or less regularly arranged polygons of an outer lamina (extrados), which is ca. 200 nm in thickness. By contrast, the lagenid test texture is characterized by much larger crystals than in other calcifying foraminifers. At moderate magnification, lagenid tests display a fibrous texture composed of fiber bundles (tens of μm in length and several μm in width) that are oriented perpendicular to test surfaces and taper towards the ends when in contact with another lamina. At higher magnification, each bundle constitutes a single calcite crystal with an inner pore extending along the entire length of the crystal/fiber. We measured test hardness using the nanoindentation method. This is the first application of this technique in microfossils. We found that Cretaceous Lagenida tests were more resistant to mechanical stress than Rotaliida tests. These comparative strengths may be linked to internal test microstructure and play a role in determining habitats in which these taxa can live.

The pollination mechanism and the optimal time of pollination in Douglas-fir (Pseudotsugamenziesii)

1981 ◽  
Vol 11 (1) ◽  
pp. 36-50 ◽  
Author(s):  
John N. Owens ◽  
Sheila J. Simpson ◽  
Marje Molder
Keyword(s):  
Electron Microscopy ◽  
Seed Set ◽  
Pollen Grains ◽  
Douglas Fir ◽  
Optimal Time ◽  
Pollination Mechanism ◽  
Seed Cone ◽  
Poor Seed ◽  
Micropylar Canal ◽  
Scanning Electron

The development of the pollination mechanism and the engulfment of pollen by the stigmatic tip is described for Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) based on scanning electron microscopy. This information is used to determine and explain the optimal time of pollination and amount of pollen needed for maximum seed set. After dormancy the integument tip of the ovule developed into an unequally two-lobed stigmatic tip covered with long unicellular hairs. Most ovules had fully developed stigmatic tips when the seed cone emerged from the bud scales in early April. The conelets remained open and the stigmatic tip was most receptive for at least 4 days. Pollen freely sifted down between the bracts and ovuliferous scales and adhered to the stigmatic hairs. Six days after the conelets became receptive, stigmatic hairs around the micropyle began to collapse and were ungulfed with the entangled pollen into the micropyle. Also, ovuliferous scales began to thicken, restricting movement of pollen to the stigmatic tips. By 8–10 days after conelets became receptive, the stigmatic tips were completely engulfed, the ovuliferous scales had thickened enough to close the conelet, and the conelet had begun to bend down.Maximum seed set occurred when (1) cones were pollinated within 4 days after seed-cone buds had emerged half of the way out of their bud scales; (2) a minimum of 0.2 g of pollen was used per pollination bag; (3) a minimum of 11 pollen grains adhered to each stigmatic tip; and (4) at least 3 pollen grains were taken into each micropylar canal. The engulfing process occurred at the same rate and in the same manner regardless of whether living or heat-killed pollen was present or absent on the stigmatic surface. Poor seed set as it related to the pollination mechanism is discussed.

The morphology of the pit organs and lateral line canal neuromasts of Mustelus antarcticus (Chondrichthyes: Triakidae)

2000 ◽  
Vol 80 (1) ◽  
pp. 155-162 ◽  
Author(s):  
Meredith B. Peach ◽  
Gregory W. Rouse
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Lateral Line ◽  
Hair Cells ◽  
Sensory System ◽  
Lateral Line Canal ◽  
Sensory Epithelia ◽  
Sensory Hairs ◽  
And Function ◽  
Scanning Electron

The pit organs (free neuromasts) of sharks are part of the lateral line sensory system, but there is still confusion about their exact morphology and function(s). This is partly because of reported physiological differences between the pit organs and the lateral line canal neuromasts, and partly because the morphology of pit organs has not been adequately documented. To compare their morphology, the pit organs and canal neuromasts of the gummy shark Mustelus antarcticus (Chondrichthyes: Triakidae) were examined using transmission and scanning electron microscopy. Both pit organs and canal neuromasts had hair cells with the `staircase' arrangement of sensory hairs (stereovilli) characteristic of vertebrate mechanoreceptors. Stereovilli bundles of different sizes were distributed haphazardly throughout the pit organs and canal neuromasts. The density of hair cells was similar in the pit organs and canal neuromasts, but differences in the overall size and/or shape of the sensory epithelia might account for some of the reported differences in mechanosensitivity.

Microsculpture and phylogenetic significance of the spermatheca of black flies (Diptera: Simuliidae)

2000 ◽  
Vol 78 (8) ◽  
pp. 1468-1482 ◽  
Author(s):  
Christopher L Evans ◽  
Peter H Adler
Keyword(s):  
Electron Microscopy ◽  
Outer Surface ◽  
Phylogenetic Reconstruction ◽  
Black Flies ◽  
Phylogenetic Significance ◽  
Phylogenetic Information ◽  
Character System ◽  
Single Character ◽  
Inner Surface ◽  
Scanning Electron

The highly varied spermatheca of black flies provided an under-studied character system for phylogenetic reconstruction of the Simuliidae. Scanning electron microscopy of the spermatheca of 17 simuliid species elucidated folds and spicules on the inner surface; callosities, anastomosing ridges, and minute tubercles on the outer surface; and an intricately fluted spermathecal duct. The spermatheca of Parasimulium crosskeyi, the most plesiomorphic taxon, had a slightly wrinkled inner surface and an outer surface with acutely raised polygonal ridges. Species hypothesized to be among the basal lineages of the simuliids (e.g., Helodon susanae and Prosimulium magnum) had an irregularly folded inner spermathecal surface, but their relationships were not well resolved on the basis of information about the spermatheca. More evolutionarily derived species, including a number of species in the genus Simulium, had short or filiform spicules on the inner surface of the spermatheca. Although the use of a single character system, the spermatheca, did not fully resolve relationships among Simuliidae, its utility as a rich source of phylogenetic information was demonstrated.

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