The structure and chemistry of plastid differentiation during male meiosis in Lilium henryi

1981 ◽  
Vol 52 (1) ◽  
pp. 223-241
Author(s):  
H.G. Dickinson
Keyword(s):  
Electron Microscopy ◽  
Particulate Material ◽  
Male Meiosis ◽  
Plastid Differentiation ◽  
Enzymic Digestion ◽  
New Information ◽  
Particle Association ◽  
Membrane Particle

The unusual content of the plastids characteristic of male meiosis and microsporogenesis in Lilium henryi has been investigated using enzymic digestion of material prepared for electron microscopy. Apart from membranous tubules and osmiophilic droplets, commonly regarded as normal constituents of the stroma of undifferentiated plastids, these organelles contained a single conspicuous association between membrane and particulate material and wefts of filaments. Enzymic digestion revealed the membrane-particle association (MPA) to contain RNA and some protein, and the filaments to be entirely proteinaceous. The use of DNase on this material proved both unreliable and, on occasions, unspecific, so no new information has emerged as to the disposition of DNA within these organelles. Many of the plastids divide immediately after meiosis and the MPAs normally divide in step with the organelles. The activities of the MPA and those of the filaments are discussed in terms of changes in the organelle population as a whole, and also in consideration of the fundamental events occurring elsewhere in the cells during the alternation from the diploid sporophyte to the haploid gametophyte.

Stereo Electron Microscopy Applied to High Resolution Freeze-Etch Replicas

1970 ◽  
Vol 28 ◽  
pp. 306-307
Author(s):  
L. Andrew Staehelin
Keyword(s):  
Electron Microscopy ◽  
Plastic Deformation ◽  
High Resolution ◽  
Smooth Surfaces ◽  
Small Particles ◽  
Membrane Surfaces ◽  
Wide Acceptance ◽  
New Information ◽  
Number Of Particles ◽  
Small Holes

Freeze-etched membranes usually appear as relatively smooth surfaces covered with numerous small particles and a few small holes (Fig. 1). In 1966 Branton (1“) suggested that these surfaces represent split inner mem¬brane faces and not true external membrane surfaces. His theory has now gained wide acceptance partly due to new information obtained from double replicas of freeze-cleaved specimens (2,3) and from freeze-etch experi¬ments with surface labeled membranes (4). While theses studies have fur¬ther substantiated the basic idea of membrane splitting and have shown clearly which membrane faces are complementary to each other, they have left the question open, why the replicated membrane faces usually exhibit con¬siderably fewer holes than particles. According to Branton's theory the number of holes should on the average equal the number of particles. The absence of these holes can be explained in either of two ways: a) it is possible that no holes are formed during the cleaving process e.g. due to plastic deformation (5); b) holes may arise during the cleaving process but remain undetected because of inadequate replication and microscope techniques.

scholarly journals Serial Block-Face Scanning Electron Microscopy Reveals That Intercellular Nuclear Migration Occurs in Most Normal Tobacco Male Meiocytes

2021 ◽  
Vol 12 ◽  
Author(s):  
Sergey Mursalimov ◽  
Nobuhiko Ohno ◽  
Mami Matsumoto ◽  
Sergey Bayborodin ◽  
Elena Deineko
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cell Wall ◽  
Three Dimensional ◽  
Nuclear Migration ◽  
Male Meiosis ◽  
Face Scanning ◽  
Block Face ◽  
Plant Meiosis ◽  
Scanning Electron

Serial block-face scanning electron microscopy (SBF-SEM) was used here to study tobacco male meiosis. Three-dimensional ultrastructural analyses revealed that intercellular nuclear migration (INM) occurs in 90–100% of tobacco meiocytes. At the very beginning of meiosis, every meiocyte connected with neighboring cells by more than 100 channels was capable of INM. At leptotene and zygotene, the nucleus in most tobacco meiocytes approached the cell wall and formed nuclear protuberances (NPs) that crossed the cell wall through the channels and extended into the cytoplasm of a neighboring cell. The separation of NPs from the migrating nuclei and micronuclei formation were not observed. In some cases, the NPs and nuclei of neighboring cells appeared apposed to each other, and the gap between their nuclear membranes became invisible. At pachytene, NPs retracted into their own cells. After that, the INM stopped. We consider INM a normal part of tobacco meiosis, but the reason for such behavior of nuclei is unclear. The results obtained by SBF-SEM suggest that there are still many unexplored features of plant meiosis hidden by limitations of common types of microscopy and that SBF-SEM can turn over a new leaf in plant meiosis research.

scholarly journals A FIBER APPARATUS IN THE NUCLEUS OF THE YEAST CELL

1966 ◽  
Vol 29 (1) ◽  
pp. 129-151 ◽  
Author(s):  
C. F. Robinow ◽  
J. Marak
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Dense Matter ◽  
Short Fiber ◽  
Yeast Cells ◽  
Acid Fuchsin ◽  
Fine Grained ◽  
New Information ◽  
Thin Electron ◽  
Iron Alum

The structure and mode of division of the nucleus of budding yeast cells have been studied by phase-contrast microscopy during life and by ordinary microscopy after Helly fixation. The components of the nucleus were differentially stained by the Feulgen procedure, with Giemsa solution after hydrolysis, and with iron alum haematoxylin. New information was obtained in cells fixed in Helly's by directly staining them with 0.005% acid fuchsin in 1% acetic acid in water. Electron micrographs have been made of sections of cells that were first fixed with 3% glutaraldehyde, then divested of their walls with snail juice, and postfixed with osmium tetroxide. Light and electron microscopy have given concordant information about the organization of the yeast nucleus. A peripheral segment of the nucleus is occupied by relatively dense matter (the "peripheral cluster" of Mundkur) which is Feulgen negative. The greater part of the nucleus is filled with fine-grained Feulgen-positive matter of low density in which chromosomes could not be identified. Chromosomes become visible in this region under the light microscope at meiosis. In the chromatin lies a short fiber with strong affinity for acid fuchsin. The nucleus divides by elongation and constriction, and during this process the fiber becomes long and thin. Electron microscopy has resolved it into a bundle of dark-edged 150 to 180 A filaments which extends between "centriolar plaques" that are attached to the nuclear envelope.

On Luticola Mann (Bacillariophyceae) in southeastern Brazil: taxonomy, ecology and description of two new species

Phytotaxa ◽  
2019 ◽  
Vol 402 (4) ◽  
pp. 165 ◽  
Author(s):  
ANGELA MARIA DA SILVA-LEHMKUHL ◽  
THELMA ALVIM VEIGA LUDWIG ◽  
PRISCILA IZABEL TREMARIN ◽  
DENISE DE CAMPOS BICUDO
Keyword(s):  
Electron Microscopy ◽  
New Species ◽  
Southeastern Brazil ◽  
Similar Species ◽  
Diatom Species ◽  
Sem Images ◽  
New Information ◽  
Two New Species ◽  
First Time ◽  
Scanning Electron

In the present study, we analyzed the taxonomy and ecology of fourteen species of Luticola registered in oligo- to hypereutrophic reservoirs of southeastern Brazil. Two new species were described using light and scanning electron microscopy. Luticola bartolomeii sp. nov. and Luticola iporangensis sp. nov. are distinguished from morphologically similar species by a combination of valve outline and dimensions. In addition, L. bartolomeii showed occluded isolated areolae that have a different shape and location, hitherto not observed in other Luticola species. We also compared the morphology of the new species with similar taxa and provided information on their ecological preferences. Luticola panamaensis is first recorded in Brazil, and another eight species are recorded for the first time for the state of São Paulo. This study expanded the distribution of species and added new information to the ecology of Luticola, as well as provided the first SEM images for some already known species. Information on the co-occurrence of other diatom species in the samples is also included.

Scale structure and taxonomy of some species of Raphidocystis, Raphidiophrys, and Pompholyxophrys (Heliozoea) including descriptions of six new taxa

1985 ◽  
Vol 63 (8) ◽  
pp. 1944-1961 ◽  
Author(s):  
K. H. Nicholls ◽  
M. Dürrschmidt
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
New Zealand ◽  
Light Microscopy ◽  
Light And Electron Microscopy ◽  
Scale Structure ◽  
Taxonomic Descriptions ◽  
Transmission Electron ◽  
New Information ◽  
Freshwater Habitats

Sixteen taxa of the genera Raphidocystis, Raphidiophrys, and Pompholyxophrys from freshwater habitats in Canada, Chile, and New Zealand were studied by light and electron microscopy. Six taxa are described as new: Raphidocystis glabra, Raphidiophrys minuta, Raphidiophrys orbicularis ssp. orbicularis, R. orbicularis ssp. ovalis, Pompholyxophrys stellata, and P. ossea. New information on scale structure and arrangement based on scanning and transmission electron microscopy amplifies the taxonomic descriptions of Raphidiophrys ambigua, R. pallida, R. elegans, R. intermedia, R. marginata, R. symmetrica, Pompholyxophrys punicea, P. exigua, and P. ovuligera, which were previously imperfectly known by light microscopy only.

The diatom genus Oricymba in Vietnam and Laos with description of one new species, and a consideration of its systematic placement

Phytotaxa ◽  
2015 ◽  
Vol 227 (2) ◽  
pp. 120 ◽  
Author(s):  
Maxim Sergeevich Kulikovskiy ◽  
Anton Glushchenko ◽  
John Patrick Kociolek
Keyword(s):  
Electron Microscopy ◽  
New Species ◽  
Systematic Position ◽  
Freshwater Ecosystems ◽  
Diatom Flora ◽  
New Information ◽  
Diatom Genus ◽  
One New Species ◽  
A New Species ◽  
Scanning Electron

Species from the genus Oricymba are studied from freshwater ecosystems of Vietnam and Laos. Three species were found in Vietnam, namely O. japonica, O. subovalis and O. perjaponica comb. nov. The two last species are new taxa for the diatom flora of Vietnam. A new species is described from Laos, O. voronkinae sp. nov., and its morphology is documented with light and scanning electron microscopy. Oricymba voronkinae sp. nov. represents the first documented occurrence of the genus Oricymba in Laos. Our findings provide new information about the morphology and species distribution of the genus Oricymba in Indochina. We discuss the systematic position of Oricymba within the Cymbellales.

Applications of Soft X-Ray and other Microscopy Techniques to Elucidate the Structure of Parasitic Metazoa

1998 ◽  
Vol 4 (S2) ◽  
pp. 1156-1157
Author(s):  
W. J. Kozek ◽  
J. Brown ◽  
W. Meyer-Ilse ◽  
C. Larabell ◽  
M. Moronne
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Trichinella Spiralis ◽  
National Laboratory ◽  
Confocal Laser ◽  
X Ray ◽  
New Information ◽  
Microscopy Techniques ◽  
Scanning Electron

The small size of many parasitic organisms requires the use of election microscopy for adequate elucidation of their structure. While both transmission and scanning electron microscopy can provide complementary results which allow considerable degree of structural correlation, each technique has its inherent limitations. Since previous studies have demonstrated that soft X-ray microscopy could be used to study parasitic protozoa and provide new information, the objective of this study was to determine whether soft X-ray microscopy could also be used to elucidate the morphology of small metazoa to complement the data obtained by other microscopy techniques.Newborn larvae, approximately 7 μm × 110 μm in size, of parasitic nematode Trichinella spiralis were used as a model system. Some of the larvae, deposited by adult females maintained in vitro, were isolated and processed for examination by transmission and scanning electron microscopy as described in our previous studies, others were fixed in 4% glutaraldehyde (Millonig's buffer) and examined in the X-ray microscope XM-1, and in the BioRad MRC 1024 confocal laser (krypton/argon) microscope of the Advanced Light Source, Berkeley National Laboratory.

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.

Lamella-particle complexes

1978 ◽  
Vol 36 (2) ◽  
pp. 238-239
Author(s):  
William G. Banfield ◽  
Cecil W. Lee
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Distinct Group ◽  
Northern Pike ◽  
Uranyl Acetate ◽  
Lymphoma Cell ◽  
Standard Methods ◽  
New Information ◽  
Degree Of Similarity ◽  
Different Origin

Lamella-particle complexes are a distinct group of morphologic structures. They have been reported in a growing number of papers often without detailed description. This could be accounted for because of the paucity of occurrence in the tissue or cells examined, the limitations inherent in preparing the tissue for electron microscopy, or because the photographs were not at a high enough magnification. We will take a closer look at these complexes, adding new information on their morphology, make correlations overlooked or not possible when initial observations were published and dispel some erroneous impressions as to the degree of similarity between complexes of different origin. Standard methods of fixation, dehydration and epon embedding were used. Staining was with lead and uranyl acetate.The lamella-particle complex is well illustrated in a lymphoma cell of the northern pike (Fig. 1). In cross section its wall is made up of a striated lamella associated with ribosome-like particles.

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