Photoreception of Paramecium cilia: localization of photosensitivity and binding with anti-frog-rhodopsin IgG

1991 ◽  
Vol 99 (1) ◽  
pp. 67-72
Author(s):  
Y. Nakaoka ◽  
R. Tokioka ◽  
T. Shinozawa ◽  
J. Fujita ◽  
J. Usukura
Keyword(s):  
Membrane Potential ◽  
Polyclonal Antibody ◽  
The Other ◽  
Paramecium Bursaria ◽  
Potential Response ◽  
Light Stimulation ◽  
Intact Cells ◽  
Other Hand ◽  
Immunocytochemical Studies ◽  
Antibody Labeling

Paramecium bursaria is photosensitive and accumulates in a lighted area. The cells can be deciliated by a brief suspension in dilute ethanol. Both intact and deciliated cells showed depolarization in response to light stimulation by a step-increase from dark to above 0.7 mW cm-2 (550 nm). On the other hand, after a step-increase to below 0.4 mW cm-1, intact cells showed hyperpolarization, while the deciliated cells showed no change in membrane potential. This difference in membrane potential response between ciliated and deciliated cells suggests that both somatic and ciliary structures are photosensitive. In our search for the photoreceptive molecules, a polyclonal antibody induced in rabbits against frog rhodopsin was found to cross-react with a 63x10(3) Mr protein of P. bursaria, by immunoelectrophoresis. Immunocytochemical studies showed that the antibody labeling was localized on both the ciliary and the somatic membranes. These results raise the possibility that P. bursaria may contain a rhodopsin-like protein as a photoreceptor molecule.

scholarly journals Distribution of Aldoxime Dehydratase in Microorganisms

2000 ◽  
Vol 66 (6) ◽  
pp. 2290-2296 ◽  
Author(s):  
Yasuo Kato ◽  
Ryoko Ooi ◽  
Yasuhisa Asano
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
The Other ◽  
Intact Cells ◽  
Other Hand ◽  
Aldoxime Dehydratase

ABSTRACT The distribution of phenylacetaldoxime-degrading and pyridine-3-aldoxime-degrading ability was examined with intact cells of 975 microorganisms, including 45 genera of bacteria, 11 genera of actinomyces, 22 genera of yeasts, and 37 genera of fungi, by monitoring the decrease of the aldoximes by high-pressure liquid chromatography. The abilities were found to be widely distributed in bacteria, actinomyces, fungi, and some yeasts: 98 and 107 strains degraded phenylacetaldoxime and pyridine-3-aldoxime, respectively. All of the active strains exhibited not only the aldoxime-dehydration activity to form nitrile but also nitrile-hydrolyzing activity. On the other hand, all of 19 nitrile-degrading microorganisms (13 species, 7 genera) were found to exhibit aldoxime dehydration activity. It is shown that aldoxime dehydratase and nitrile-hydrolyzing activities are widely distributed among 188 aldoxime and 19 nitrile degraders and that the enzymes were induced by aldoximes or nitriles.

Cytochrome c, an ideal antioxidant

2003 ◽  
Vol 31 (6) ◽  
pp. 1312-1315 ◽  
Author(s):  
M.O. Pereverzev ◽  
T.V. Vygodina ◽  
A.A. Konstantinov ◽  
V.P. Skulachev
Keyword(s):  
Superoxide Dismutase ◽  
Membrane Potential ◽  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Cytochrome Oxidase ◽  
The Other ◽  
Other Hand ◽  
O2 Reduction

Generation of Δψ (membrane potential) by cytochrome oxidase proteoliposomes oxidizing superoxide-reduced cytochrome c has been demonstrated. XO+HX (xanthine oxidase and hypoxanthine) were used to produce superoxide. It was found that the generation of Δψ is completely abolished by cyanide (an uncoupler) or by superoxide dismutase, and is enhanced by nigericin. Addition of ascorbate after XO+HX causes a further increase in Δψ. On the other hand, XO+HX added after ascorbate do not affect Δψ, indicating that superoxide does not have measurable protonophorous activity. The half-maximal cytochrome c concentration for Δψ generation supported by XO+HX was found to be approx. 1 μM. These data and the results of some other researchers can be rationalized as follows: (1) O2 accepts an electron to form superoxide; (2) cytochrome c oxidizes superoxide back to O2; (3) an electron removed from the reduced cytochrome c is transferred to O2 by cytochrome oxidase in a manner that generates ΔμH+ (transmembrane difference in electrochemical H+ potential). Thus cytochrome c mediates a process of superoxide removal, resulting in regeneration of O2 and utilization of the electron involved previously in the O2 reduction. It is important that cytochrome c is not damaged during the antioxidant reaction, in contrast with many other antioxidants.

Platelets contain a 210K microtubule-associated protein related to a similar protein in HeLa cells

1988 ◽  
Vol 90 (2) ◽  
pp. 317-324
Author(s):  
F. Tablin ◽  
M.J. Reeber ◽  
V.T. Nachmias
Keyword(s):  
Western Blotting ◽  
Indirect Immunofluorescence ◽  
Polyclonal Antibody ◽  
Hela Cells ◽  
Blood Platelets ◽  
The Other ◽  
Similar Protein ◽  
Other Hand ◽  
Protein Map ◽  
Tubulin Immunofluorescence

We have demonstrated the presence of a 210K (K = 10(3) Mr) microtubule-associated protein (MAP) in blood platelets and have studied its relationship to tubulin and to the cytoskeleton, using a well-characterized polyclonal antibody for the analysis. When platelet lysates were enriched for tubulin by an assembly cycle at 37 degrees C, the 210K MAP was also enriched, as detected by Western blotting, while the antigen was not detected in pellets from cold-treated samples that lacked stabilized tubulin. Immunofluorescence of resting platelets showed that the 210K antigen colocalized with the microtubule coil in ring-like structures. On the other hand, in preparations of platelet cytoskeletons, the 210K antigen was present in samples from platelets in which the coil was disassembled (cold-treated without taxol pretreatment) as well as from platelets in which the coil was preserved (at 37 degrees C without taxol, or 4 degrees C with taxol pretreatment). In chilled platelets with disassembled microtubule coils, indirect immunofluorescence using antibodies to 210K or tubulin gave a diffuse signal throughout the platelet cytoplasm. However, immunofluorescence of the 210K antigen in both resting and cold-treated platelets displayed discrete or patchy staining as compared to the continuous staining with antitubulin. We conclude that 210K MAP is present in platelets, that it copurifies with tubulin and that it is localized along the microtubule coil. Our results also suggest that the 210K MAP may interact with some other element(s) of the cytoskeleton, and hence that it might serve as a linking protein.

The effect of some salts on Thiobacillus thioparus

1969 ◽  
Vol 15 (3) ◽  
pp. 314-318 ◽  
Author(s):  
Paulina Keller
Keyword(s):  
Sodium Chloride ◽  
Oxygen Uptake ◽  
Growth Medium ◽  
Dead Sea ◽  
The Other ◽  
Endogenous Respiration ◽  
Cell Free Extract ◽  
Intact Cells ◽  
Thiobacillus Thioparus ◽  
Other Hand

The effect of NaCl on Thiobacillus thioparus ATCC 8158 and on a strain of T. thioparus isolated from salt-rich Ein Bokek spring, near the Dead Sea, was investigated. Whereas the growth of T. thioparus ATCC 8158 was completely arrested by NaCl, KCl, or NaNO3 at a concentration of 0.3 M, the Ein Bokek strain tolerated 1.4 M of NaCl in the growth medium. Other salts (KCl, KNO3, CaCl2, MgCl2, and NaNO3) were significantly more toxic than NaCl. On the other hand, their effect on oxygen uptake by both strains was similar to that of NaCl.The thiosulfate-oxidizing system in cell-free extract was less affected by NaCl than that in the intact cells. Most of the effect of NaCl on this system could be attributed to inhibition of endogenous respiration. It was concluded that sodium chloride did not inhibit growth of T. thioparus through blocking its respiratory processes.

scholarly journals Inhibition of Bacillus anthracis Spore Outgrowth by Nisin

2008 ◽  
Vol 52 (12) ◽  
pp. 4281-4288 ◽  
Author(s):  
Ian M. Gut ◽  
Angela M. Prouty ◽  
Jimmy D. Ballard ◽  
Wilfred A. van der Donk ◽  
Steven R. Blanke
Keyword(s):  
Membrane Potential ◽  
Heat Resistance ◽  
Bacillus Anthracis ◽  
Oxidative Metabolism ◽  
Mode Of Action ◽  
Inhibitory Concentration ◽  
The Other ◽  
Other Hand ◽  
Mechanism Of Inhibition ◽  
Spore Outgrowth

ABSTRACT The lantibiotic nisin has previously been reported to inhibit the outgrowth of spores from several Bacillus species. However, the mode of action of nisin responsible for outgrowth inhibition is poorly understood. By using B. anthracis Sterne 7702 as a model, nisin acted against spores with a 50% inhibitory concentration (IC50) and an IC90 of 0.57 μM and 0.90 μM, respectively. Viable B. anthracis organisms were not recoverable from cultures containing concentrations of nisin greater than the IC90. These studies demonstrated that spores lose heat resistance and become hydrated in the presence of nisin, thereby ruling out a possible mechanism of inhibition in which nisin acts to block germination initiation. Rather, germination initiation is requisite for the action of nisin. This study also revealed that nisin rapidly and irreversibly inhibits growth by preventing the establishment of oxidative metabolism and the membrane potential in germinating spores. On the other hand, nisin had no detectable effects on the typical changes associated with the dissolution of the outer spore structures (e.g., the spore coats, cortex, and exosporium). Thus, the action of nisin results in the uncoupling of two critical sequences of events necessary for the outgrowth of spores: the establishment of metabolism and the shedding of the external spore structures.

III. The Plays: General Considerations

1986 ◽  
Vol 18 ◽  
pp. 8-13
Keyword(s):  
Wide Spectrum ◽  
The Other ◽  
Individual Experience ◽  
Subjective Response ◽  
Human Beings ◽  
Potential Response ◽  
Modern Reader ◽  
Other Hand ◽  
The Creation ◽  
Opposite Extreme

On the level of purely subjective response there is no inherently incorrect or unjustifiable approach to the interpretation of character within the plays: the modern reader, like the ancient audience, is free to interpret according to individual experience or personal prejudice, and like all great writers Aeschylus has injected sufficient ambiguity into his creations to appeal to a wide spectrum of potential response. Of more objective concern on the other hand is the response Aeschylus aimed to produce, and the degree of importance he attached to the creation of character within the actual plays. In recent times the once popular exaltation of character, which viewed the figures on the stage as rounded and consistent wholes, has given way to a more Aristotelian assertion of economy in character portrayal, and its function of giving credibility to the more important element of plot. Thus Lucas states ‘most of the figures in Aeschylean tragedy are presented with the minimum of characterization; they are what the plot requires them to be and no more’. The earlier view, however, continues to be advanced, often in the more extreme guise of psychoanalysis, but while one cannot deny the useful insights the method sometimes produces, the exaggerated and wholly unrealistic claims advanced for it have proven totally counter-productive. At the opposite extreme is the insistence that portrayal of character lies totally at the mercy of transient dramatic necessity, making any quest for consistency doomed to failure from the start. It is a view that was first propounded for Sophocles by Tycho Wilamowitz and later applied to Aeschylus by Roger Dawe. Certainly in terms of logic Dawe’s proposition is hard to fault, and its very forthright expression serves as a welcome touchstone for others, but as P. E. Easterling observes, dramatic necessity is in many respects a sterile criterion of literary judgement. Somewhat similar in its final result if not in approach is the importance at times attributed to the divine factor in determining the actions of characters - the onset of Ate or an unspecified daimon that leads a man like Agamemnon to his doom. Again we cannot deny a role for the divine in the action of the plays, but to emphasize it to the exclusion of intelligibility in human terms risks negating belief that the characters portrayed are human beings at all rather than playthings of the gods.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

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