A critical assessment of criteria used in the taxonomy of the genus Rhizopus

1983 ◽  
Vol 61 (9) ◽  
pp. 2374-2383 ◽  
Author(s):  
R. J. Seviour ◽  
D. E. Pitt ◽  
S. McClure ◽  
J. Pyle
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Growth Rate ◽  
Radial Growth ◽  
Critical Assessment ◽  
Radial Growth Rate ◽  
Diagnostic Usefulness ◽  
Taxonomic Studies ◽  
Scanning Electron ◽  
Interspecific Diversity

Scanning electron microscopy (SEM) and cultural physiology data have been used to assess their taxonomic applicability in delimiting species of the genus Rhizopus. SEM of the sporangiospores of a variety of isolates indicates that there is a continuum of patterns ranging from almost featureless surfaces to verruculose and deeply ridged or striated topologies. The degree of interspecific diversity was sufficient to reduce the diagnostic usefulness of this feature for interspecies delineation. Cultural characteristics, radial growth rate, sporulation pattern, and growth and viability at raised temperatures were also too variable for use in taxonomic studies.

Preparation of Alcohol-Preserved Larvae of Culicidae (Diptera) for Scanning Electron Microscopy

1972 ◽  
Vol 3 (3) ◽  
pp. 181-188 ◽  
Author(s):  
Christine Dahl
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
The Body ◽  
Taxonomic Studies ◽  
Scanning Electron ◽  
Sem Studies

AbstractA method for preparation of alcohol-preserved culicid larvae for Scanning Electron Microscope (SEM) studies is described. It is based on dehydration by ethanol-xylol and fast evaporation of xylol in +8o° C. for ten minutes. For taxonomic studies such as examination of pecten teeth, comb scales and microtrichiae in magnifications up to 6oooX the method is suitable. For studies of receptor structures on hair-tufts and microstructures of the body integument alcohol preserved material is less satisfactory. The microstructure of the comb scales is figured and their function discussed. Differences in the ultrastructure of the abdominal hair-tufts are pointed out.

Scanning Electron Microscopy Coupled with Energy Dispersive Spectrometric Analysis Reveals for the First Time Weddellite and Sylvite Crystals on the Surface of Involucral Bracts and Petals of two Xeranthemum L. (Compositae) Species

2017 ◽  
Vol 23 (3) ◽  
pp. 679-686 ◽  
Author(s):  
Milan Gavrilović ◽  
Suzana Erić ◽  
Petar D. Marin ◽  
Núria Garcia-Jacas ◽  
Alfonso Susanna ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Glandular Trichomes ◽  
Energy Dispersive ◽  
Spectrometric Analysis ◽  
Eds Analysis ◽  
Taxonomic Studies ◽  
First Time ◽  
Tetragonal Bipyramid ◽  
Scanning Electron

AbstractIn this work, weddellite and sylvite crystals are identified for the first time on the involucral bracts and petals of Xeranthemum annuum and Xeranthemum cylindraceum using scanning electron microscopy coupled with energy dispersive spectrometric (SEM-EDS) analysis. Well-developed crystals of weddellite (CaC2O4·2H2O) occur in the form of a tetragonal bipyramid (hhl), rarely in combination of a bipyramid and tetragonal prism (h00). Indumentum of involucral bracts of X. cylindraceum consists of nonglandular and glandular trichomes. Sylvite (KCl) crystals are observed only on the petal surface of X. cylindraceum. The crystals of sylvite occur in the form of perfect cubes (hexahedrons), but some crystals are deformed, i.e., partially elongated. Taxonomic significance of investigated microcharacters as well as the use of SEM-EDS analysis in taxonomic studies of plants are discussed.

New diagnostic characters for Amphiodia and Ophiophragmus (Amphiuridae, Ophiuroidea, Echinodermata)

2020 ◽  
Vol 100 (5) ◽  
pp. 759-781
Author(s):  
Gisella C.S. Chagas ◽  
Renata A.S. Alitto ◽  
Helena Serrano ◽  
Gabriela Granadier ◽  
Pablo D.B. Guilherme ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
New Records ◽  
External Morphology ◽  
Diagnostic Characters ◽  
Comparative Analyses ◽  
Phylogenetic Studies ◽  
New Information ◽  
Taxonomic Studies ◽  
Scanning Electron

AbstractThe genera Ophiophragmus and Amphiodia are amphiurids that are considered taxonomically difficult due to their great resemblance, few diagnostic characters and synonymy problems. Our aim is to redescribe the species using scanning electron microscopy and morphometry of diagnostic structures, and to provide new information for the identification of these Ophiuroidea. Five Amphiodia spp. and six Ophiophragmus spp. recorded in Brazil were rigorously redescribed. The descriptions include new diagnostic characters derived from external morphology, arm microstructures and morphometry. We also provided comparative analyses of species with shared characters such as Amphiodia riisei and Amphiodia trychna. The geographic and bathymetric distributions of the studied species were updated, and new records are provided. All the information presented may be used in taxonomic, ecological and phylogenetic studies, helping to fill gaps in the knowledge of the biodiversity, ecology and evolution of these Ophiuroidea. Conclusively, all the tools applied here assisted in the identification of genera and species and could be useful in other taxonomic studies of Echinodermata.

scholarly journals Microstructure Evolution and Coarsening of θ′-Al2Cu Precipitates in a Creep Aged Al-Cu-Mn Alloy

2021 ◽  
Vol 2101 (1) ◽  
pp. 012071
Author(s):  
Soban Muddassir Dar ◽  
Yutao Zhao ◽  
Hengcheng Liao ◽  
Xizhou Kai
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Growth Rate ◽  
Microstructure Evolution ◽  
Average Length ◽  
Transmission Electron ◽  
Creep Exposure ◽  
Creep Temperature ◽  
Scanning Electron

Abstract This paper describes the microstructure evolution in a creep aged Al-Cu-Mn alloy using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results show the sub-grains formation and accelerated coarsening of θ′ precipitates in creep aged samples. It is observed that at an applied stress of 50MPa, as the creep temperature increases the average length of θ′ precipitates increases and their aspect ratio first increases then decreases. It is also found that after 100h of creep exposure at 200°C/50MPa, θ′ precipitates have grown to an average length of 279nm; at 225°C/50MPa to an average length of 425nm and at 250°C/50MPa they have grown to an average length of 844nm. Coarsening/growth rate of the precipitates is described by Lifshitz-Slyozov-Wagner (LSW) model.

New mechanisms in demosponge spicule formation

2001 ◽  
Vol 81 (2) ◽  
pp. 345-346 ◽  
Author(s):  
C.H.L. Schönberg
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Organic Matrix ◽  
Silica Deposition ◽  
Spicule Formation ◽  
Taxonomic Studies ◽  
Surface Silica ◽  
Scanning Electron

A new mechanism of demosponge spicule formation was recognized during taxonomic studies of bioeroding sponges (Porifera: Demospongiae: Clionidae). To date different spicule types have been explained by matching structures to their organic matrix, the axial thread. Bulbous structures, however, do not have an organic counterpart. Immature spicules of Cliona tinctoria and Pione caesia have irregular, rough heads. Higher magnification during scanning electron microscopy shows that silica granules are deposited regionally to form bulbs. Later silica secretion smoothens the bulb surface. Silica deposition in form of granules rather than in layers appears to be a structuring tool in tylostyles.

scholarly journals Enhancement of Growth and Flowering of Triteleia laxa by Ethylene

1990 ◽  
Vol 115 (3) ◽  
pp. 482-486 ◽  
Author(s):  
Susan S. Han ◽  
Abraham H. Halevy ◽  
Roy M. Sachs ◽  
Michael S. Reid
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Growth Rate ◽  
Respiration Rate ◽  
Apical Meristem ◽  
Day Treatment ◽  
Fresh Weight ◽  
Final Size ◽  
Meristem Size ◽  
Scanning Electron

Exposure of dormant corms of Triteleia laxa `Queen Fabiola' to 20 ppm C2H4 for 7 days promoted flowering of small corms and resulted in increased apical meristem size, early sprouting, early flowering, more flowers per Inflorescence, and increased fresh weight of daughter corms and cormels. The respiration rate of the C&treated corms increased to four to five times that of the controls during the 7-day treatment, declined markedly after termination of the C2H4 treatment, but remained higher than that of the controls. The C2H4 effects were associated with increased growth rate and consequently a greater final size of the apical meristem (determined by scanning electron microscopy). Leaves produced by C2H4-treated corms were wider, longer, and weighed more than those of the controls.

Morphological comparison and identification of metacercariae in the ‘pygmaeus’ group of microphallids, parasites of seabirds in western palaearctic regions

1997 ◽  
Vol 71 (2) ◽  
pp. 167-174 ◽  
Author(s):  
D.H. Saville ◽  
K.V. Galaktionov ◽  
S.W.B. Irwin ◽  
I.I. Malkova
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Northern Ireland ◽  
Critical Assessment ◽  
Littorina Saxatilis ◽  
Morphological Comparison ◽  
Gastropod Mollusc ◽  
Western Palaearctic ◽  
Arctic Russia ◽  
Scanning Electron

AbstractThis study compares the metacercariae of a ‘pygmaeus’ microphallid discovered in Littorina saxatilis from the coast of Northern Ireland with the metacercariae of Microphallus piriformes and M. pygmaeus from the same species of gastropod mollusc from Arctic Russia. Light and scanning electron microscopy were used to provide morphometric and surface details for descriptions of the organisms concerned. Comparison and statistical analysis of the results established that the species from Northern Ireland was M. piriformes and not M. pygmaeus as had previously been assumed. It dearly indicates the need for critical assessment of the accuracy of literature dealing with the occurrence of ‘M. pygmaeus’ in both intermediate and final hosts.

The Role of Scanning Electron Microscopy in Taxonomic Studies of Freshwater Bryozoans (Ectoprocta: Phylactolaemata)

1997 ◽  
Vol 3 (S2) ◽  
pp. 109-110
Author(s):  
T. S. Wood ◽  
C. A. Taylor
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Surface Topography ◽  
New World ◽  
Laboratory Rearing ◽  
Food Particles ◽  
Taxonomic Studies ◽  
Surface Figure ◽  
Scanning Electron

Bryozoans are among the most common multicellular animals that attach to submerged surfaces in fresh waters. Zooids of the colony capture and digest suspended food particles; they also produce distinctive asexual buds called statoblasts. Measuring 0.35 to nearly 1 mm in diameter, statoblasts have a chitinous exterior and are the only truly hard parts of the bryozoan colony. Like the mastax of rotifers or mouthparts of midge larvae, statoblasts show a variety of taxonomically significant features. Scanning electron microscopy reveals clear patterns in statoblast surface topography that suggest many more species than the 60 or so normally recognized.Statoblast surface features were first used to distinguish species of the genus Fredericella. The European F. sultana, with a smooth statoblast surface, had been assumed to occur worldwide. SEM micrographs showed the statoblast surface of New World Fredericella to be finely pitted, identical to that of F. indica in India (Figure 1). Another Fredericella species, not yet named, is distinguished only by its highly rugose statoblast surface (Figure 2). Such features are retained through generations of laboratory rearing under various controlled conditions.

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