An electron microscope study of the karyotypes of two wolf spiders

1983 ◽  
Vol 25 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Dwayne Wise
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Gradual Increase ◽  
Light And Electron Microscopy ◽  
Genome Length ◽  
Wolf Spiders ◽  
X Chromosomes ◽  
Autosomal Pair

Meiosis in two species of wolf spiders, Lycosa georgicola Walckenaer and Lycosa rabida Walckenaer, has been analyzed by light and electron microscopy. Both karyotypes comprise 13 autosomal pairs + X1X2, all except one pair of which are telocentric. The autosomes show a gradual increase in size ranging from 5.6 to 9.9% of the total genome length. The two X chromosomes of L. rabida are not significantly different in length. In both species, the two X chromosomes are loosely aligned at prophase, but never synapse in the true sense; they do not form synaptonemal complexes. This supports the evidence that X1 and X2 are not homologous. In L. georgicola, one of the X's is associated at prophase with one autosomal pair, but this association does not persist to prometaphase.

scholarly journals An Electron Microscope Study of Basophile Substances of Frozen-Dried Rat Liver

1958 ◽  
Vol 4 (3) ◽  
pp. 291-300 ◽  
Author(s):  
Henry Finck
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Rat Liver ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Freeze Drying ◽  
Light And Electron Microscopy ◽  
Enzyme Treatment ◽  
Dense Granules ◽  
Homogeneous Matrix

Small pieces of liver from rats subjected to different dietary regimes were fixed by freeze-drying, and postfixed by in vacuo heating and denaturation with alcohol. Specimens were digested with ribo- or deoxyribonuclease, and stained with gallocyanin-chromalum, azure II, the Feulgen procedure or alcoholic platinic tetrabromide. Some specimens were reserved as controls of the effects of enzyme treatment. Stained and unstained specimens were embedded in methacrylate and examined by light and electron microscopy. Basophilic and Feulgen-positive substances, after contact with watery reagents, were found by electron microscopy to exist as small dense granules embedded in a less dense homogeneous matrix, forming the walls of submicroscopic vacuoles. These granules were absent after digestion with nucleodepolymerases. In specimens (unstained, or stained with platinic tetrabromide) which had not passed through water, the dense (basophile) substances in nuclei and cytoplasm were found to exist, not as granules, but as ill defined submicroscopic concentrates which blended imperceptibly into the homogeneous matrix of the vacuolar walls. Objections to the use of stains for improving contrast conditions in electron microscopy of tissues are discussed, and it is concluded that the reagents do not necessarily produce the observed increases in contrast by selectively stabilizing certain structures. The concept of microsomes as pre-existing distinct morphological entities in intact (unhomogenized) cells is thought to be inconsistent with the distribution of basophile substances in frozen-dried liver.

scholarly journals ELECTRON MICROSCOPY OF THE NUCLEAR MEMBRANE OF AMOEBA PROTEUS

1956 ◽  
Vol 2 (4) ◽  
pp. 445-448 ◽  
Author(s):  
Marie H. Greider ◽  
Wencel J. Kostir ◽  
Walter J. Frajola
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Nuclear Membrane ◽  
Outer Layer ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Cell Types ◽  
Amoeba Proteus ◽  
Nuclear Membranes ◽  
Thin Sectioning

An electron microscope study of the nuclear membrane of Amoeba proteus by thin sectioning techniques has revealed an ultrastructure in the outer layer of the membrane that is homologous to the pores and annuli observed in the nuclear membranes of many other cell types studied by these techniques. An inner honeycombed layer apparently unique to Amoeba proteus is also described.

scholarly journals AN ELECTRON MICROSCOPE STUDY OF THE EMBRYOLOGY OF THE INTERCALATED DISC IN THE HEART OF THE RABBIT

1957 ◽  
Vol 3 (2) ◽  
pp. 193-202 ◽  
Author(s):  
Alan R. Muir
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Cardiac Muscle ◽  
Microscope Study ◽  
Light Microscope ◽  
Electron Microscope Study ◽  
Muscle Cells ◽  
Intercalated Disc ◽  
Adult Cell ◽  
Embryonic Muscle

Prenatal and postnatal cardiac muscle from rabbits has been studied by electron microscopy, after osmium fixation and methacrylate embedding. The observations showed that 1. Cell membranes divide the muscle into cellular units from the youngest embryo which was studied (9½ days after coitus) until the adult state. 2. The embryonic muscle cells contain only one nucleus, whereas the adult cell may be multinucleated. 3. At all stages of development, wherever a myofibrillar axis crosses a cellular boundary, the myofilaments are interrupted by an intercalated disc. 4. With age, increase in size and complexity of the discs render them recognisable by the light microscope.

An electron-microscope study of peristerite plagioclases

1965 ◽  
Vol 35 (269) ◽  
pp. 165-176 ◽  
Author(s):  
S. G. Fleet ◽  
P. H. Ribbe
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Electron Diffraction ◽  
Microscope Study ◽  
Lamellar Structure ◽  
Electron Microscope Study ◽  
Transmission Electron

SummaryPlagioclase feldspars in the peristerite range An2-An17 have been investigated by transmission electron-microscopy and electron diffraction. All except the more anorthite-rich specimens were found to be unmixed into albite and oligoclase lamellae, between a few hundred and several thousand Å thick and approximately parallel to . A discussion is given of the part played by these lamellae when optical schiller is exhibited; and the effect of heat treatment on the lamellar structure and optical schiller is described.

scholarly journals AN ELECTRON MICROSCOPE STUDY OF SALIVARY GLAND CHROMOSOMES BY THE REPLICA METHOD

1949 ◽  
Vol 89 (4) ◽  
pp. 431-438 ◽  
Author(s):  
Sanford L. Palay ◽  
Albert Claude
Keyword(s):  
Electron Microscopy ◽  
Salivary Gland ◽  
Electron Microscope ◽  
Nucleic Acid ◽  
Electron Micrographs ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Amorphous Material ◽  
Desoxyribonucleic Acid ◽  
Linear Network

A method for preparing replicas of salivary gland chromosomes for electron microscopy is described. Electron micrographs of these replicas show that the giant chromosomes are composed of a series of small granules of approximately equal size arranged transversely across the chromosome. In stretched preparations a linear network of filaments appears between the rows of granules. These fibers cannot be traced between corresponding granules of more than two consecutive rows. When the chromosomes are digested by desoxyribonuclease, these fibers disappear and only amorphous material remains between the bands. The characteristics of the strands suggest that they are artifacts produced when the chromosomes are stretched. The small granules are composed of desoxyribonucleic acid and at least one other component, probably a protein. The nucleic acid seems to lie at least in part on the surface of each granule.

Scanning electron microscope study of brochosomes of cercopidae

1994 ◽  
Vol 52 ◽  
pp. 358-359
Author(s):  
A. S. Frost ◽  
J. S. Gardner ◽  
M. Nielson
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Scanning Electron Microscope Study ◽  
The Family ◽  
Scanning Electron

Brochosomes are minute granules secreted by specialized cells lining the lumen of Malphigian tubules in homopteran insects. They have been reported on two different homopteran families, the Cicadellidae (leaf-hoppers) and Membracidae (tree-hoppers), but they have never been reported on members of the family Cercopidae (froghoppers), although they have been suspected to be produced by other homopteran families. These three families all belong to the subgroup Auchenorryncha, and often coexist in the same habitat. Many theories have been proposed regarding brochosome function, but no conclusive results have ever been reported.Scanning electron microscopy was used to study legs of five species of Cercopidae. Brochosomes were observed on legs of Lepyronid batrachoidea (Fig. 1), Clastoptera brunnea (Fig. 2), Philaronia bilineata (Fig. 3), and Aphozphoza media (Fig. 4). None was found on Clastoptera juniperina. The shape of the brochosomes remained fairly consistent on all species except Clastoptera brunnea. Normally the structure was a polyhedron consisting of 12 pentagons and 20 hexagons, appearing hollow and nearly spherical. However, on Clastoptera brunnea, the brochosomes were larger and appeared to be more faceted.

scholarly journals ELECTRON MICROSCOPY OF LYSOSOME-RICH FRACTIONS FROM RAT LIVER

1956 ◽  
Vol 2 (4) ◽  
pp. 179-184 ◽  
Author(s):  
Alex B. Novikoff ◽  
H. Beaufay ◽  
C. de Duve
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Rat Liver ◽  
Electron Micrographs ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Internal Cavity ◽  
Dense Granules ◽  
Dense Bodies

A preliminary electron microscope study has revealed the presence in lysosome-rich fractions, isolated from rat liver, of hitherto undescribed cytoplasmic particles, called "dense bodies." Approximately 0.37 µ in length, the dense bodies often possess an internal cavity and external membrane. They contain many electron-dense granules 55 to 77 A, or less, in diameter. Such dense bodies are also visible in electron micrographs of parenchymatous cells in liver sections. The correlations between dense bodies and lysosomes are listed, but until pure preparations are available it is not possible to assert that dense bodies and lysosomes are identical.

An electron microscope study of Meria coniospora, an endozoic nematophagous Hyphomycete

1982 ◽  
Vol 60 (10) ◽  
pp. 2019-2023 ◽  
Author(s):  
Masatoshi Saikawa
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Germ Tube ◽  
Nematophagous Fungus ◽  
Mucous Layer ◽  
Ultrathin Sections

Conidia of Meria coniospora Drechsler, an endozoic nematophagous fungus, were examined by electron microscopy at various stages of infection. The conidia are almost conical in shape and develop a knoblike structure at the apical end. Ultrathin sections show that the knob is always covered with a mucous layer, which is composed of a number of radiating fibrils. Attachment to the nematode's integument is by means of this fibrillose layer. The germ tube from the bud grows between the conidium and nematode and forms a tiny infection bladder in the integument.

Electron Microscope Study of Revolving Crystal Growth of Ý–Type Vanadium Oxide Hydrate Under Hydrothermal Conditions

1994 ◽  
Vol 346 ◽  
Author(s):  
S. Kittaka ◽  
H. Miyahara ◽  
Y. Yokota
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Crystal Growth ◽  
Vanadium Oxide ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Hydrothermal Conditions ◽  
Oxide Hydrate ◽  
Transmission Electron

ABSTRACTAnomalous revolving stacking crystal growth of β-type vanadium oxide hydrate formed by hydrothermal treatment was studied by transmission electron microscopy.

Ultrastructure of Plant Leaf Tissue Infected with Mite-Borne Viral-Like Pathogens

1970 ◽  
Vol 28 ◽  
pp. 178-179 ◽  
Author(s):  
O. E. Bradfute ◽  
R. E. Whitmoyer ◽  
L. R. Nault
Keyword(s):  
Triticum Aestivum ◽  
Zea Mays ◽  
Electron Microscope ◽  
Hordeum Vulgare ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Leaf Tissue ◽  
Leaf Ultrastructure ◽  
Double Membrane ◽  
Aceria Tulipae

A pathogen transmitted by the eriophyid mite, Aceria tulipae, infects a number of Gramineae producing symptoms similar to wheat spot mosaic virus (1). An electron microscope study of leaf ultrastructure from systemically infected Zea mays, Hordeum vulgare, and Triticum aestivum showed the presence of ovoid, double membrane bodies (0.1 - 0.2 microns) in the cytoplasm of parenchyma, phloem and epidermis cells (Fig. 1 ).

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