The Reactions of Normal and Mutant Types of Gammarus Chevreuxi to Light

1932 ◽  
Vol 9 (4) ◽  
pp. 427-440
Author(s):  
A. WOLSKY ◽  
J. S. HUXLEY
Keyword(s):  
Acetic Acid ◽  
Moderate Degree ◽  
Negative Phototaxis ◽  
Wild Type ◽  
Type Specimens ◽  
Optic Nerves ◽  
Positive Phototaxis ◽  
Statistical Results

1. A method is described for obtaining statistical results on the phototaxis of G. chevreuxi. A long tube is illuminated from one end and the numbers of animals in two arbitrarily delimited end-sections counted at regular intervals. 2. Wild-type specimens in normal conditions show a moderate degree of negative phototaxis. 3. Animals with one eye varnished show circus movements; hence the phototaxis is true tropotaxis (Fränkel, 1931 4. The sense of reaction can be reversed and the animals made to show a moderate positive phototaxis by the addition of acetic acid. Caffein has no effect. 5. Red-eyed mutants, which lack most of the melanin eye pigment, behave similarly to the wild type, though there are indications that they are often rather more sensitive to light, as shown by stronger negative phototaxis in normal conditions, weaker positive phototaxis after addition of acid. The variability of the results, however, is too great to permit of definitive conclusions being drawn. 6. Albino and colourless mutants, which possess neither retinulae nor optic nerves, show no phototaxis.

scholarly journals Characterization of Chlamydomonas reinhardtii Mutants That Exhibit Strong Positive Phototaxis

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1483
Author(s):  
Jun Morishita ◽  
Ryutaro Tokutsu ◽  
Jun Minagawa ◽  
Toru Hisabori ◽  
Ken-ichi Wakabayashi
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Regulatory Mechanism ◽  
Model Organism ◽  
Negative Phototaxis ◽  
Light Conditions ◽  
Wild Type ◽  
Positive Phototaxis ◽  
Unicellular Green Alga ◽  
Cellular Factors

The most motile phototrophic organisms exhibit photo-induced behavioral responses (photobehavior) to inhabit better light conditions for photosynthesis. The unicellular green alga Chlamydomonas reinhardtii is an excellent model organism to study photobehavior. Several years ago, we found that C. reinhardtii cells reverse their phototactic signs (i.e., positive and negative phototaxis) depending on the amount of reactive oxygen species (ROS) accumulated in the cell. However, its molecular mechanism is unclear. In this study, we isolated seven mutants showing positive phototaxis, even after the induction of negative phototaxis (ap1~7: always positive) to understand the ROS-dependent regulatory mechanism for the phototactic sign. We found no common feature in the mutants regarding their growth, high-light tolerance, and photosynthetic phenotypes. Interestingly, five of them grew faster than the wild type. These data suggest that the ROS-dependent regulation of the phototactic sign is not a single pathway and is affected by various cellular factors. Additionally, the isolation and analyses of mutants with defects in phototactic-sign regulation may provide clues for their application to the efficient cultivation of algae.

scholarly journals Multiple Light Inputs Control Phototaxis in Synechocystis sp. Strain PCC6803

2003 ◽  
Vol 185 (5) ◽  
pp. 1599-1607 ◽  
Author(s):  
Wing-On Ng ◽  
Arthur R. Grossman ◽  
Devaki Bhaya
Keyword(s):  
Blue Light ◽  
Red Light ◽  
Infrared Light ◽  
Negative Phototaxis ◽  
Wild Type ◽  
Response Curves ◽  
Similar Action ◽  
Positive Phototaxis ◽  
Phototactic Behavior ◽  
Phototactic Response

ABSTRACT The phototactic behavior of individual cells of the cyanobacterium Synechocystis sp. strain PCC6803 was studied with a glass slide-based phototaxis assay. Data from fluence rate-response curves and action spectra suggested that there were at least two light input pathways regulating phototaxis. We observed that positive phototaxis in wild-type cells was a low fluence response, with peak spectral sensitivity at 645 and 704 nm. This red-light-induced phototaxis was inhibited or photoreversible by infrared light (760 nm). Previous work demonstrated that a taxD1 mutant (Cyanobase accession no. sll0041 ; also called pisJ1) lacked positive but maintained negative phototaxis. Therefore, the TaxD1 protein, which has domains that are similar to sequences found in both bacteriophytochrome and the methyl-accepting chemoreceptor protein, is likely to be the photoreceptor that mediates positive phototaxis. Wild-type cells exhibited negative phototaxis under high-intensity broad-spectrum light. This phenomenon is predominantly blue light responsive, with a maximum sensitivity at approximately 470 nm. A weakly negative phototactic response was also observed in the spectral region between 600 and 700 nm. A ΔtaxD1 mutant, which exhibits negative phototaxis even under low-fluence light, has a similar action maximum in the blue region of the spectrum, with minor peaks from green to infrared (500 to 740 nm). These results suggest that while positive phototaxis is controlled by the red light photoreceptor TaxD1, negative phototaxis in Synechocystis sp. strain PCC6803 is mediated by one or more (as yet) unidentified blue light photoreceptors.

Proteome and metabolome profiling of wild-type and YCA1 -knock-out yeast cells during acetic acid-induced programmed cell death

2015 ◽  
Vol 128 ◽  
pp. 173-188 ◽  
Author(s):  
Valentina Longo ◽  
Maša Ždralević ◽  
Nicoletta Guaragnella ◽  
Sergio Giannattasio ◽  
Lello Zolla ◽  
...  
Keyword(s):  
Cell Death ◽  
Acetic Acid ◽  
Programmed Cell Death ◽  
Yeast Cells ◽  
Wild Type ◽  
Knock Out ◽  
Metabolome Profiling

scholarly journals Deletion of arginase 2 attenuates neuroinflammation in an experimental model of optic neuritis

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0247901
Author(s):  
Amritha A. Candadai ◽  
Fang Liu ◽  
Abdelrahman Y. Fouda ◽  
Moaddey Alfarhan ◽  
Chithra D. Palani ◽  
...  
Keyword(s):  
Optic Neuritis ◽  
Experimental Model ◽  
Axonal Degeneration ◽  
Wild Type ◽  
Autoimmune Encephalomyelitis ◽  
Optic Nerves ◽  
Clinical Presentations ◽  
Retinal Neurodegeneration ◽  
The Impact ◽  
Experimental Autoimmune

Vision impairment due to optic neuritis (ON) is one of the major clinical presentations in Multiple Sclerosis (MS) and is characterized by inflammation and degeneration of the optic nerve and retina. Currently available treatments are only partially effective and have a limited impact on the neuroinflammatory pathology of the disease. A recent study from our laboratory highlighted the beneficial effect of arginase 2 (A2) deletion in suppressing retinal neurodegeneration and inflammation in an experimental model of MS. Utilizing the same model, the present study investigated the impact of A2 deficiency on MS-induced optic neuritis. Experimental autoimmune encephalomyelitis (EAE) was induced in wild-type (WT) and A2 knockout (A2-/-) mice. EAE-induced cellular infiltration, as well as activation of microglia and macrophages, were reduced in A2-/- optic nerves. Axonal degeneration and demyelination seen in EAE optic nerves were observed to be reduced with A2 deletion. Further, the lack of A2 significantly ameliorated astrogliosis induced by EAE. In conclusion, our findings demonstrate a critical involvement of arginase 2 in mediating neuroinflammation in optic neuritis and suggest the potential of A2 blockade as a targeted therapy for MS-induced optic neuritis.

Effect of chlorpromazine on phototactic behavior in Chlamydomonas

1980 ◽  
Vol 26 (2) ◽  
pp. 265-267 ◽  
Author(s):  
Rona Hirschberg ◽  
William Hutchinson
Keyword(s):  
Control System ◽  
Light Intensity ◽  
Antipsychotic Drug ◽  
Green Alga ◽  
Negative Phototaxis ◽  
Low Light ◽  
Positive Phototaxis ◽  
Phototactic Behavior ◽  
Common Control

Chlorpromazine, an antipsychotic drug, causes a light intensity dependent reversal of phototaxis in the green alga Chlamydomonas reinhardi. At moderate light intensity, drug-treated cells swim away from the light (negative phototaxis) while untreated cells swim toward it (positive phototaxis). At low light, both treated and untreated cells exhibit normal positive phototactic responses. It appears that light and chlorpromazine may affect a common control system for phototaxis.

Phototaxis of adult brine shrimp, Artemia salina

1984 ◽  
Vol 62 (12) ◽  
pp. 2357-2359 ◽  
Author(s):  
David J. Bradley ◽  
Richard B. Forward Jr.
Keyword(s):  
Spectral Sensitivity ◽  
Brine Shrimp ◽  
Artemia Salina ◽  
Threshold Sensitivity ◽  
Behavioral Measure ◽  
Negative Phototaxis ◽  
Light Perception ◽  
Positive Phototaxis ◽  
Low Intensity

Using phototaxis as a behavioral measure of light perception, spectral and intensity sensitivity were determined for adult brine shrimp, Artemia salina. Spectral sensitivity was characterized by a well-defined maximum at 520 nm light, with perhaps a smaller maximum at 400 nm light. Dark-adapted animals showed a strong negative phototaxis at high intensities between 5.0 × 1012 quanta∙m−2∙s−1 and 3.6 × 1016 quanta∙m−2∙s−1 at 520 nm light. Positive phototaxis was greatest at the low intensity of 2.8 × 1012 quanta∙m−2∙s−1. Threshold sensitivity for both positive and negative phototaxis was approximately 2 × 1012 quanta∙m−2∙s−1.

scholarly journals Key wheat GRF genes constraining wheat tillering of mutant dmc

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11235
Author(s):  
Jing Zhang ◽  
Junchang Li ◽  
Yongjing Ni ◽  
Yumei Jiang ◽  
Zhixin Jiao ◽  
...  
Keyword(s):  
Triticum Aestivum ◽  
Acetic Acid ◽  
Indole Acetic Acid ◽  
Expression Profiles ◽  
Functional Characterization ◽  
Tissue Expression ◽  
Wild Type ◽  
Gene Structures ◽  
Wheat Mutant

Tillering is a key agronomy trait for wheat (Triticum aestivum L.) production. Previously, we have reported a dwarf-monoculm wheat mutant (dmc) obtained from cultivar Guomai 301 (wild type, WT), and found growth regulating factors (GRFs) playing important roles in regulating wheat tillering. This study is to systematically investigate the roles of all the wheat GRFs (T. aestivum GRFs, TaGRFs) in regulating tillering, and screen out the key regulators. A total of 30 TaGRFs were identified and their physicochemical properties, gene structures, conserved domains, phylogenetic relationships and tissue expression profiles were analyzed. The expression levels of all the TaGRFs were significantly lower in dmc than those in WT at early tillering stage, and the abnormal expressions of TaGRF2-7(A, B, D), TaGRF5-7D, TaGRF10-6(A, B, D) and TaGRF11-2A were major causes constraining the tillering of dmc. The transcriptions of TaGRFs were significantly affected by exogenous indole acetic acid (IAA) and gibberellin acid (GA3) applications, which suggested that TaGRFs as well as IAA, GA signaling were involved in controlling wheat tillering. This study provided valuable clues for functional characterization of GRF genes in wheat.

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