Rickettsia-like and mycoplasma-like organisms associated with two yellows-type diseases of strawberries in Queensland

1979 ◽  
Vol 30 (6) ◽  
pp. 1101 ◽  
Author(s):  
RS Greber ◽  
DH Gowanlock
Keyword(s):  
Electron Microscopy ◽  
The Other ◽  
Thin Sections ◽  
Flower Production ◽  
Flower Abortion ◽  
Leaf Chlorosis ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Sieve Tubes ◽  
Section Electron Microscopy

Two yellows-type diseases occur in Queensland strawberries. Affected plants show purple or bronze pigmentation of older leaves, followed by the production of small chlorotic leaves. Flower production is inhibited, and some affected plants die. Thin-section electron microscopy showed that there were two diseases, one associated with rickettsia-like organisms (RLO) and the other with mycoplasma-like organisms (MLO), both of which were found only in sieve tubes. The MLO disease caused flower abortion but not green petals, and was not transmitted by Orosius argentatus (Evans), the tomato big bud vector. The RLO disease produced more bronze pigmentation and the young leaf chlorosis was interveinal rather than marginal. This organism was sensitive to penicillin, and soil drenches of 1 mg/ml every 5 days for 7 weeks caused complete remission of symptoms. No organisms were seen in thin sections of leaves after treatment. Although these RLO morphologically resembled those associated with rugose leaf curl (RLC) disease of legumes, experiments with the RLC vector Austroagallia torrida Evans indicated that they were probably distinct.

scholarly journals Toroidal bands in polytene chromosomes of Drosophila

1983 ◽  
Vol 64 (1) ◽  
pp. 255-264
Author(s):  
V. Sorsa
Keyword(s):  
Electron Microscopy ◽  
Drosophila Melanogaster ◽  
Salivary Gland ◽  
Thin Section ◽  
Polytene Chromosomes ◽  
Thin Sections ◽  
Sister Chromatids ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy

Results obtained from the thin-section electron microscopy of salivary gland chromosomes of Drosophila melanogaster mainly support the concept of cable-like organization of polytene chromosomes, with disk-like bands composed of parallel bundles of homologous chromomeres. Outward orientation of loop fibres may generally cause a toroidal bending in the chromomere bundles. Both longitudinal and transverse sections of polytene chromosomes indicate that the bands may contain toroidal subunits. Torus-shaped bands were only found in thin sections of the most distal and most proximal regions, as well as in certain heavy bands at the late-replicating regions of polytenized interphase chromosomes. This suggests that an incomplete duplication of chromomeres may be a reason for torus formation, by preventing the separation of sister chromatids at the earliest phases of the polytenization process. The appearance of more numerous, but smaller, subunits in thin-sectioned faint bands is interpreted as a consequence of more complete segregation of sister chromatids in those bands during polytenization.

scholarly journals Effects of Tetracycline Antibiotics on Plants Affected by Legume Little Leaf Disease

1972 ◽  
Vol 25 (1) ◽  
pp. 43 ◽  
Author(s):  
JW Bowyer ◽  
JG Atherton
Keyword(s):  
Electron Microscopy ◽  
Tetracycline Antibiotics ◽  
Disease Symptoms ◽  
Tomato Plants ◽  
Leaf Disease ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Sieve Tubes ◽  
Hydro Chloride ◽  
Section Electron Microscopy

Nicotiana glutino8a, aster, and tomato plants affected by legume little leaf disease were treated by spraying the foliage with 100 ,..,g/ml aqueous solutions of either Achromycin (tetracycline hydrochloride) or Aureomycin (chlortetracycline hydro-chloride), every 2-3 days for periods of 4-8 weeks. Disease symptoms were sup� pressed in the new growth of all plants during the treatment period, but reappeared 2-4 weeks after the last application of antibiotic. Mycoplasma-like bodies were abundant in the phloem sieve tubes of untreated aster, and in aster which redeveloped symptoms after the antibiotic treatment had been discontinued. In contrast, Mycoplasma�like bodies could not be detected by thin� section electron microscopy in symptomless shoots of Achromycin-treated plants immediately after a period of treatment. In concomitant leafhopper transmission tests with the vector Orosius argentatus, the little leaf agent was not recovered from the symptomless treated shoots, but was readily recovered from diseased shoots which developed after termina-tion of the Achromycin treatment.

The Infection of Cells by Bullet-Shaped Viruses

1969 ◽  
Vol 27 ◽  
pp. 372-373
Author(s):  
Frederick A. Murphy ◽  
Alyne K. Harrison ◽  
Sylvia G. Whitfield
Keyword(s):  
Electron Microscopy ◽  
Physical Properties ◽  
Host Cell ◽  
Thin Section ◽  
Cultured Cells ◽  
Cell Infection ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy

The bullet-shaped viruses are currently classified together on the basis of similarities in virion morphology and physical properties. Biologically and ecologically the member viruses are extremely diverse. In searching for further bases for making comparisons of these agents, the nature of host cell infection, both in vivo and in cultured cells, has been explored by thin-section electron microscopy.

Normal Synaptonemal Complex and Abnormal Recombination Nodules in Two Alleles of the Drosophila Meiotic Mutant mei-W68

Genetics ◽  
2003 ◽  
Vol 163 (4) ◽  
pp. 1337-1356 ◽  
Author(s):  
Adelaide T C Carpenter
Keyword(s):  
Electron Microscopy ◽  
Synaptonemal Complex ◽  
High Frequency ◽  
Serial Section ◽  
The Other ◽  
Wild Type ◽  
Recombination Nodules ◽  
Section Electron ◽  
Serial Section Electron Microscopy ◽  
Section Electron Microscopy

Abstract The meiotic phenotypes of two mutant alleles of the mei-W68 gene, 1 and L1, were studied by genetics and by serial-section electron microscopy. Despite no or reduced exchange, both mutant alleles have normal synaptonemal complex. However, neither has any early recombination nodules; instead, both exhibit high numbers of very long (up to 2 μm) structures here named “noodles.” These are hypothesized to be formed by the unchecked extension of identical but much shorter structures ephemerally seen in wild type, which may be precursors of early recombination nodules. Although the mei-W68L1 allele is identical to the mei-W681 allele in both the absence of early recombination nodules and a high frequency of noodles (i.e., it is amorphic for the noodle phene), it is hypomorphic in its effects on exchange and late recombination nodules. The differential effects of this allele on early and late recombination nodules are consistent with the hypothesis that Drosophila females have two separate recombination pathways—one for simple gene conversion, the other for exchange.

Effect of taxol on the interaction of tubulin with myosin filaments

1984 ◽  
Vol 62 (9) ◽  
pp. 878-884 ◽  
Author(s):  
Toshihiro Fujii ◽  
Tatsuo Suzuki ◽  
Akira Hachimori ◽  
Michiyo Fujii ◽  
Yoshiyuki Kondo ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Skeletal Muscle ◽  
Atpase Activity ◽  
Cross Section ◽  
Molar Ratio ◽  
Tubulin Polymerization ◽  
Myosin Filaments ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy

The interaction between polymerized tubulin from porcine brain and myosin from rabbit skeletal muscle was examined. The addition of myosin to the solution of tubulin polymerized by taxol resulted in a remarkable increase in turbidity within a few minutes at 37 °C, and a dense and stable precipitate was formed. The maximal molar ratio of tubulin bound to myosin was calculated to be about 4, while the value was about 2 when 6S tubulin was used. Both podophyllotoxin and colchicine suppressed the taxol-dependent increase of the binding of tubulin to myosin, but only when they were preincubated with tubulin prior to addition of taxol. 6S tubulin inhibited with aetin-activated Mg2+-ATPase activity of myosin, and polymerized tubulin inhibited the Mg-ATPase more than 6S tubulin. Dense precipitates of tubulin and myosin were observed by thin-section electron microscopy. Microtubules were observed to be entangled in myosin filaments and single microtubules were occasionally surrounded by five myosin filaments in a cross section, similar to actin–myosin arrays in muscle. After incubation of tubulin with myosin, taxol was able to induce tubulin polymerization in the same way as it polymerized microtubules in the absence of myosin.

scholarly journals STUDIES OF THE ULTRASTRUCTURE AND RIBOSOMAL ARRANGEMENTS OF THE PLEUROPNEUMONIA-LIKE ORGANISM A5969

1965 ◽  
Vol 25 (1) ◽  
pp. 139-150 ◽  
Author(s):  
Jack Maniloff ◽  
Harold J. Morowitz ◽  
Russell J. Barrnett
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Chemical Analysis ◽  
Thin Section ◽  
Differential Centrifugation ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy ◽  
Cellular Organelles

Thin-section electron microscopy, together with isolation of cellular organelles by differential centrifugation and chemical analysis, has been used to investigate the ultrastructure of the avian pleuropneumonia-like organism A5969. Each cell (approximate diameter 5500 A) was surrounded by a 150 A plasma membrane. In the center of the cell was an unbounded area, granular in appearance and containing the cell's DNA. The periphery of the cell contained granules of several different sizes and densities. The most dense particles (150 A) corresponded to the 78S ribosomes. These particles exhibited two predominant arrangements: (a) sometimes they showed cubic packing; (b) most arrays, however, were consistent with cylindrical arrangements of approximately 50 particles. Bundles of up to 18 arrays were observed. Structured blebs have been found protruding from the surface of log phase cells.

Mycoplasma-like organisms as causal agents of potato purple top wilt in Queensland

1985 ◽  
Vol 36 (3) ◽  
pp. 443 ◽  
Author(s):  
RM Harding ◽  
DS Teakle
Keyword(s):  
Electron Microscopy ◽  
Thin Section ◽  
Strong Evidence ◽  
Tomato Plant ◽  
Tomato Plants ◽  
Potato Plants ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Potato Purple Top ◽  
Section Electron Microscopy

The eggplant little-leaf agent was graft transmitted to tomato causing big-bud symptoms. Transmission from the big-bud tomato to potato by grafting or the leafhopper Orosius argentatus resulted in the development of purple top wilt symptoms. Thin-section electron microscopy revealed mycoplasma-like organisms present in the phloem sieve elements of a big-bud tomato plant and purple top wilt potato plants infected by grafting or leafhoppers. When tubers from graft-infected potato plants were planted, 73% produced spindly shoots and 44% of these later developed purple top wilt symptoms. When scions from either field-infected or experimentally infected potato plants showing purple top wilt symptoms were grafted onto tomato plants, 24% and 62% respectively developed big-bud symptoms. The results provide strong evidence for the mycoplasmal aetiology of some, if not all, potato purple top wilt in Queensland.

scholarly journals Structural characterization of altered nucleoporin Nup153 expression in human cells by thin-section electron microscopy

Nucleus ◽  
2014 ◽  
Vol 5 (6) ◽  
pp. 601-612 ◽  
Author(s):  
Vincent Duheron ◽  
Guillaume Chatel ◽  
Ursula Sauder ◽  
Vesna Oliveri ◽  
Birthe Fahrenkrog
Keyword(s):  
Electron Microscopy ◽  
Thin Section ◽  
Structural Characterization ◽  
Human Cells ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy
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