An Analysis of the Role of Electromagnetic Radiations in the Mating Reaction of Paramecium bursaria

1953 ◽  
Vol 26 (3) ◽  
pp. 274-300 ◽  
Author(s):  
Charles F. Ehret
Keyword(s):  
Paramecium Bursaria ◽  
Mating Reaction ◽  
Electromagnetic Radiations

The role of endosymbiotic algae in photoaccumulation of green Paramecium bursaria

Planta ◽  
1981 ◽  
Vol 152 (3) ◽  
pp. 268-271 ◽  
Author(s):  
D�rte Niess ◽  
Werner Reisser ◽  
Wolfgang Wiessner
Keyword(s):  
Paramecium Bursaria ◽  
Endosymbiotic Algae

scholarly journals The role of calcium in the Chlamydomonas reinhardtii mating reaction.

1993 ◽  
Vol 121 (2) ◽  
pp. 365-374 ◽  
Author(s):  
U W Goodenough ◽  
B Shames ◽  
L Small ◽  
T Saito ◽  
R C Crain ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Sharp Increase ◽  
Intracellular Camp ◽  
Dibutyryl Camp ◽  
Mating Reaction ◽  
Flagellar Membrane ◽  
Camp Levels ◽  
Signal Transduction Systems ◽  
Related Increase

The mating reaction of Chlamydomonas reinhardtii entails a rapid series of cell-cell interactions leading to cell fusion. We have demonstrated (Pasquale, S. M., and U. Goodenough. 1987. J. Cell Biol. 105:2279-2293) that cAMP plays a key role in this process: gametic flagellar adhesion elicits a sharp increase in intracellular cAMP, and presentation of dibutyryl-cAMP to unmated gametes elicits all known mating responses. The present study evaluates the role of Ca2+ in this system. We document that the mating-induced increase in cAMP, and hence the mating responses themselves, are blocked by a variety of drugs known to interfere with Ca(2+)-sensitive processes. These data suggest that Ca(2+)-mediated events may couple adhesion to the generation of cAMP. Such events, however, appear to be localized to the flagellar membrane; we find no evidence for the mating-related increase in cytosolic free Ca2+ that has been postulated by others. Indeed, by monitoring the length of the Ca(2+)-sensitive centrin-containing nucleus-basal body connector, we show that cytosolic free Ca2+ levels, if anything, decrease in response to cAMP signaling. We confirm a previous report that Ca2+ levels increase in the mating medium, but document that this represents a response to augmented cAMP levels and not a prelude. Finally, we show that IP3 levels remain constant throughout the mating reaction. These results are discussed in terms of the various signal transduction systems that have now been identified in Chlamydomonas.

scholarly journals The Role of Radiation in Photodynamic Action

1951 ◽  
Vol 28 (4) ◽  
pp. 537-540
Author(s):  
G. CALCUTT
Keyword(s):  
Normal Condition ◽  
Paramecium Bursaria ◽  
Photodynamic Action

It has been demonstrated that, within certain limits, the radiation of cultures of Paramecium bursaria, which had been kept in the dark, with wave-lengths greater than 3300 A., facilitates a subsequently elicited photodynamic response. A period of darkness following the pre-irradiation allows of a return to the normal condition. The role of radiation in the mechanism of photodynamic action is discussed.

The green hydra symbiosis. VI. What is the role of maltose transfer from alga to animal?

1982 ◽  
Vol 216 (1205) ◽  
pp. 397-413 ◽  
Keyword(s):  
Organic Carbon ◽  
Population Size ◽  
Paramecium Bursaria ◽  
Green Hydra ◽  
Successful Infection ◽  
Population Sizes ◽  
Host Tissues

Maltose is the principal form in which organic carbon is transferred from symbiont to host in green hydra. Associations can be established between aposymbiotic 'European' hydra and certain strains of Chlorella originally isolated from Paramecium bursaria which vary in the amount of maltose that they release in culture. These strains were characterized as either ‘high releasers’ (40-170 ng of maltose released per 10 6 cells per 10 min) or ‘low releasers’ (0.3-2 ng of maltose per 10 6 cells per 10 min). After establishment of stable associations which had remained constant through several host generations, high releasers were estimated to transfer at least ten times as much maltose to their hosts as low releasers. Both types of Chlorella established similar population sizes in hydra, suggesting that, although maltose release is known to be essential for successful infection, the amount released is of little importance in determining eventual symbiont population size. There were no marked and consistent differences in budding rate in the light between hydra infected with high or low releasers. Hydra infected with their own native symbionts sometimes grew more slowly in the light than those infected with foreign Chlorella , and, in the dark, the slower growth become more marked under conditions of starvation. These results were interpreted in terms of the possibility that native symbionts are more efficient at exploiting their habitats than foreign. Thus, the level of glycogen in host tissues in hydra grown in the dark was less if native symbionts were present than if low releasers were present.

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor

Role of the allergist in diagnosis and management of patients with uveitis

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre
Keyword(s):  
Diagnosis And Management

The power of norms to sway fused group members

2018 ◽  
Vol 41 ◽  
Author(s):  
Winnifred R. Louis ◽  
Craig McGarty ◽  
Emma F. Thomas ◽  
Catherine E. Amiot ◽  
Fathali M. Moghaddam
Keyword(s):  
Evolutionary Anthropology ◽  
Normative Systems ◽  
Violent Extremism ◽  
Identity Fusion ◽  
Group Members

AbstractWhitehouse adapts insights from evolutionary anthropology to interpret extreme self-sacrifice through the concept of identity fusion. The model neglects the role of normative systems in shaping behaviors, especially in relation to violent extremism. In peaceful groups, increasing fusion will actually decrease extremism. Groups collectively appraise threats and opportunities, actively debate action options, and rarely choose violence toward self or others.

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