The cuticle on Psilotum gametophytes

1995 ◽  
Vol 73 (8) ◽  
pp. 1283-1288 ◽  
Author(s):  
Dean P. Whittier ◽  
R. L. Peterson
Keyword(s):  
Electron Microscopy ◽  
Key Words ◽  
Positive Reaction ◽  
Axenic Culture ◽  
Apical Region ◽  
Lipid Layer ◽  
Outer Area

The surfaces of Psilotum gametophytes from soil and axenic culture were examined with electron microscopy and histochemistry. A lipid layer, which gave a positive reaction for all lipid stains employed, covers the surface of these gametophytes. In apical regions the lipid coating is almost as thick as the wall it coats. The wall was not stained with lipid stains but did stain for polysaccharides, cellulose, pectin, and polyphenols materials. The surface of gemmae from gametophytes grown in axenic culture was examined with electron microscopy. In young areas the lipid was amorphous, but it had a lamellate outer area in older regions of the gemmae. The surface of Psilotum gametophytes range from white in the apical region to dark brown in older areas. The browning of the surface resulted from the incorporation of tanniniferous materials into the surface wall of the older region. The cuticle along with the tanniniferous materials in the wall make the surface of these subterranean gametophytes resistant to decay and may protect them from certain biota in the soil. The cuticle may help these long-lived gametophytes to withstand any periodic drying of the soil. Key words: Psilotum, gametophyte, cuticle.

The surface coating on gametophytes of Ophioglossum engelmannii

1984 ◽  
Vol 62 (2) ◽  
pp. 360-365 ◽  
Author(s):  
Dean P. Whittier ◽  
R. L. Peterson
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Surface Coating ◽  
Periodic Acid ◽  
Axenic Culture ◽  
Apical Region ◽  
Coating Deposition ◽  
Outer Portion ◽  
Tangential Wall ◽  
Pas Staining

The surfaces of gametophytes of Ophioglossum engelmannii from axenic culture were examined with electron microscopy and histochemistry. A thick granular coating covers the surface of mature regions of the gamctophyte. Although the apex of the gametophyte is free of the coating, deposition begins on the surface walls just basipetal to the apical region. The outer tangential wall of surface cells is strongly positive with periodic acid – Schiff's (PAS) staining and the coating is somewhat PAS positive. The outer portion of the outer tangential cell wall and the coating are positive for polyphenols substances. Lipid materials appear to be absent from the coating and the wall. The coating may help to protect these subterranean gametophytes from the biota of the soil.

Limited taxonomic value of palea intercostal characteristics in North American Festuca (Poaceae)

1993 ◽  
Vol 71 (12) ◽  
pp. 1651-1659 ◽  
Author(s):  
L. L. Consaul ◽  
S. G. Aiken
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
North America ◽  
Key Words ◽  
North American ◽  
Apical Region ◽  
Key To Species ◽  
Species Groups ◽  
Epidermal Features ◽  
Scanning Electron

Morphology of the intercostal palea region of 34 Festuca species found in North America was investigated using scanning electron microscopy. Palea epidermal features are most diverse in the palea apical region and fully developed in florets approaching anthesis. The intercostal region has long cells 3–15 times longer than wide, with walls that vary from slightly to prominently thickened, and from almost straight to strongly undulate. This variation was observed among paleas collected from different locations and sometimes even on a single palea. The distribution of short cells, almost square in outline, among the long cells varied with species from solitary to paired and from abundant to sparse. Four forms of trichomes were recorded: papillae, hook trichomes, prickle hairs, and macrohairs, with one form usually predominating per species. Silicon was detected in some short cells and commonly in the tips of trichomes. A key to species groups is presented. Key words: scanning electron microscopy, palea, trichomes, silicon, epidermal features, Festuca.

The development and zoospore ultrastructure of a polycentric chytridiomycete gut fungus, Orpinomyces joyonii comb.nov.

1991 ◽  
Vol 69 (3) ◽  
pp. 580-589 ◽  
Author(s):  
Jinliang Li ◽  
I. Brent Heath ◽  
K.-J. Cheng
Keyword(s):  
Electron Microscopy ◽  
Distribution Pattern ◽  
Key Words ◽  
Light And Electron Microscopy ◽  
General Morphology ◽  
Organelle Distribution ◽  
Central Nuclei

Orpinomyces bovis, a polycentric gut fungus isolated from a steer, was examined with both light and electron microscopy and renamed Orpinomyces joyonii comb.nov. on the basis of its general morphology and zoospore ultrastructure. The multinucleate rhizomycelium is extensively branched, and sporangia form exogenously on branched or unbranched sporangiophores. The organelles in the zoospores have a distribution pattern typical of other gut fungi, i.e., anterior ribosomal aggregates, central nuclei, and posterior presumptive hydrogenosomes. The perikinetosomal apparatus in O. joyonii is comparable to that in monocentric gut fungi but with minor variations. New details of the posterior dome are described. It contains highly ordered specialized lamellae, peripheral granules, and megatubules. Microtubules intersect the dome predominantly at approximately right angles to its surface; this differs from monocentric gut fungi, in which microtubules form a posterior fan running parallel to the dome. We suggest that both monocentric and polycentric gut fungi are monophyletic, since both have a similar, distinctive perikinetosomal apparatus, posterior dome, and organelle distribution pattern. Key words: Orpinomyces joyonii, gut fungi, ultrastructure, posterior dome, perikinetosomal apparatus.

Ultrastructural and cytological observations of apothecial tissues of Geopyxis carbonaria (Pezizales, Ascomycetes)

1990 ◽  
Vol 68 (2) ◽  
pp. 243-257 ◽  
Author(s):  
James W. Kimbrough ◽  
Jack L. Gibson
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Key Words ◽  
Mother Cell ◽  
Secondary Wall ◽  
Cell Stage ◽  
Wall Structures ◽  
Transmission Electron ◽  
Secondary Wall Formation ◽  
Characteristic Features

Cytological observations are made on apothecial tissues of Geopyxis carbonaria, using transmission electron microscopy. Characteristic features of both the medullary and ectal excipula are examined. Changes in ascus apex and wall structures are examined during ascus ontogeny, especially in relation to operculum position and structure. Ultrastructure of septum configuration is observed and compared in the excipulum, ascogenous hyphae, paraphyses, and at the base of young asci. Ascosporogenesis is observed from the ascus mother cell stage and initial spore delimitation until secondary wall formation. The cytological and ultrastructural observations on this species are discussed in relation to their possible taxonomic or phylogenetic value. Key words: ascosporogenesis, Discomycetes, ascospore ultrastructure, septal ultrastructure, cytochemistry.

Electron microscopy of two nematode-destroying fungi, Meristacrum asterospermum and Zygnemomyces echinulatus (Meristacraceae, Entomophthorales)

1997 ◽  
Vol 75 (5) ◽  
pp. 762-768 ◽  
Author(s):  
Masatoshi Saikawa ◽  
Masami Oguchi ◽  
Rafael F. Castañeda Ruiz
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Key Words ◽  
Septal Wall ◽  
Apical Portion ◽  
Key Words Infection ◽  
Ultrathin Sections

Infection of nematodes by Meristacrum asterospermum and Zygnemomyces echinulatus was initiated by conidia adhering to the nematode's cuticle. Each conidium developed an infection peg to penetrate the nematode after adhesion. In M. asterospermum, an infection peg just under the penetration was found in ultrathin sections, in which the peg's cell wall was broken into several lobes that were covered entirely with an amorphous mass of electron-opaque substance. Septa formed in the apical portion of aerial conidiophore under conidiation. The septal wall was nonperforate and often contained electron-opaque inclusions. Vegetative hyphae of Z. echinulatus had typical bifurcate septa, but septa at both ends of the pedicel of conidia were often slightly deformed. Key words: infection of nematodes, Meristacrum asterospermum, septum, Zygnemomyces echinulatus.

Microtubular configurations during endosperm development in Phaseolus vulgaris

1994 ◽  
Vol 72 (10) ◽  
pp. 1489-1495 ◽  
Author(s):  
X. XuHan ◽  
A. A. M. Van Lammeren
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Phaseolus Vulgaris ◽  
Key Words ◽  
Cell Walls ◽  
Endosperm Development ◽  
Initial Cell ◽  
Related Cell ◽  
Cellular Endosperm ◽  
Cell Shaping

Microtubular cytoskeletons in nuclear, alveolar, and cellular endosperm of bean (Phaseolus vulgaris) were analyzed immunocytochemically and by electron microscopy to reveal their function during cellularization. Nuclear endosperm showed a fine network of microtubules between the wide-spaced nuclei observed towards the chalazal pole. Near the embryo, where nuclei were densely packed, bundles of microtubules radiated from nuclei. They were formed just before alveolus formation and functioned in spacing nuclei and in forming internuclear, phragmoplast-like structures that gave rise to nonmitosis-related cell plates. During alveolus formation cell plates extended and fused with other newly formed walls, thus forming the walls of alveoli. Growing wall edges of cell plates exhibited arrays of microtubules perpendicular to the plane of the wall, initially. When two growing walls were about to fuse, microtubules of both walls interacted, and because of the interaction of microtubules, the cell walls changed their position. When a growing wall was about to fuse with an already existing wall, such interactions between microtubules were not observed. It is therefore concluded that interactions of microtubules of fusing walls influence shape and position of walls. Thus microtubules control the dynamics of cell wall positioning and initial cell shaping. Key words: cell wall, cellularization, endosperm, microtubule, Phaseolus vulgaris.

Sporophytes, megaspores, and massulae of Azolla stanleyi from the Paleocene Joffre Bridge locality, Alberta

1994 ◽  
Vol 72 (3) ◽  
pp. 301-308 ◽  
Author(s):  
Georgia L. Hoffman ◽  
Ruth A. Stockey
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Key Words ◽  
Red Deer ◽  
The Other ◽  
Evolutionary Trends ◽  
Reproductive Structures ◽  
Transmission Electron ◽  
New Material

Several hundred vegetative and fertile specimens of Azolla Lam. have been recovered from the Paleocene Paskapoo Formation at the Joffre Bridge locality (Middle Tiffanian (Ti3) age) near Red Deer, Alberta. The spore complexes closely resemble those of the Paleocene A. stanleyi Jain & Hall, and the vegetative material is referred to that species. The specimens are unusually complete in that the remains of the fragile sporophyte are preserved, commonly with reproductive structures in place. Plants reaching up to 2.25 cm in length consist of alternately branched rhizomes bearing alternate, imbricate, sessile leaves. Leaves are ovate with entire margins, papillate surfaces, and a single midvein. Reproductive structures have been examined using light, scanning, and transmission electron microscopy. This new material is compared with the other Paleocene species for which sporophytes are known and discussed in terms of evolutionary trends for the genus. The specimens suggest that most of the vegetative characteristics of modern Azolla species were established by the middle Paleocene. Key words: Azolla, Salviniaceae, megaspore, massula, ultrastructure, Paleocene.

Isoetes × marensis, a new interspecific hybrid from western Canada

1995 ◽  
Vol 73 (9) ◽  
pp. 1345-1353 ◽  
Author(s):  
Donald M. Britton ◽  
Daniel F. Brunton
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
British Columbia ◽  
Key Words ◽  
North American ◽  
Interspecific Hybrid ◽  
Western Canada ◽  
Hybrid Plants ◽  
Surface Ornamentation ◽  
Scanning Electron

A new interspecific hybrid in Isoetes, I. maritima Underw. × I. howellii Engelm., is delineated and described from the Shuswap Highlands region of British Columbia by means of cytology and scanning electron microscopy of spores. Isoetes × marensis D.M. Britton and D.F. Brunton, hyb.nov. is the name proposed for this taxon. It is triploid (3x; 2n = 33) and is believed to produce only sterile and (or) aborted spores. Hybrid plants have polymorphic spores that demonstrate size and surface ornamentation features intermediate between those of the putative parents. Three populations were examined, each growing with both of the putative parents in silt and sand among granite cobble over clay along an emergent lakeshore. Isoetes × marensis is the first described North American hybrid involving an amphibious Isoetes. It is expected to be a rare taxon owing to the restricted sympatric area of the putative parents and their tendency to occupy different habitats. Key words: Isoetes, Isoetes howellii, Isoetes maritima, hybrid, British Columbia.

The genus Bombardioidea

1994 ◽  
Vol 72 (9) ◽  
pp. 1302-1310 ◽  
Author(s):  
John C. Krug ◽  
James A. Scott
Keyword(s):  
Key Words ◽  
Axenic Culture ◽  
Fungal Genus

The taxonomy and ecology of the fungal genus Bombardioidea (Ascomycotina, Lasiosphaeriaceae) are discussed. Descriptions and illustrations are provided for the four accepted species: Bombardioidea anartia n.sp., Bombardioidea bombardioides, Bombardioidea serignanensis, and Bombardioidea stercoris. Observations from axenic culture are provided for B. bombardioides, and an Angulimaya (Phialophora-like) anamorph is reported. The coriaceous and gelatinous aspects of the peridium are considered to be adaptations to xerophytic environments. Key words: Bombardioidea, Angulimaya, Phialophora, coprophilous, ecology, taxonomy.

A comparison of scolex morphology between the plerocercoid and the adult of Calliobothrium verticillatum (Tetraphyllidea: Onchobothriidae)

1991 ◽  
Vol 69 (6) ◽  
pp. 1484-1488 ◽  
Author(s):  
J. N. Caira ◽  
T. R. Ruhnke
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Hermit Crab ◽  
Morphological Changes ◽  
Complex Surface ◽  
Apical Region ◽  
Apical Sucker ◽  
Mustelus Canis ◽  
Scanning Electron ◽  
Surface Changes

The morphological changes associated with the ontogenetic transformation of the scolex from larva to adult were investigated in the tapeworm Calliobothrium verticillatum (Rudolphi, 1819) van Beneden, 1850 by comparing the morphology of plerocercoids collected from the hermit crab Pagurus pollicaris Say, 1817 with that of adult worms collected from the shark Mustelus canis (Mitchell, 1815), using scanning electron microscopy. The apex of the scolex in young plerocercoids bore a conspicuous sucker. Each bothridium was flat and divided into four regions: an anterior oval region with two marginal bumps, and three posterior loculi clearly marked by two costae. The microthrix pattern was not determined for very young plerocercoids. The most conspicuous feature of older plerocercoids was the sucker on the apex of the scolex. The bothridia were concave, and each bore an apical region subdivided into three shallow suckers and three conspicuous loculi. Densely packed blade-like microtriches intermingled with filiform microtriches were visible on all surfaces of the scolex except the surface directly adjacent to the opening of the apical sucker of the scolex, which was entirely devoid of microtriches, and the proximal surfaces of the bothridia, which had only blade-like microtriches. The apical sucker was absent from the scolex adult specimens. The only remnant of this structure was a small knob on the apex of the scolex. The bothridia were concave and bore, from anterior to posterior, three conspicuous apical suckers arranged in a horizontal row adjacent to one another, two pairs of single-pronged hooks, and three conspicuous loculi. Densely packed blade-like microtriches were present on all proximal surfaces of the scolex. Microtriches were not present on the distal surfaces of the apical suckers of the bothridia, on the hooks, or on the distal surfaces of the loculi of the bothridia. The latter regions were covered with very small, round structures. The differences in the microthrix components of the various surfaces of the scolex between the plerocercoid and the adult suggest that complex surface changes occur during this phase of ontogeny. Comparison of the development of this species with that of other onchobothriids suggests that, in general, the number of loculi to be expected in the plerocercoid of an onchobothriid is one plus the number of posthook loculi in the adult.

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