Actions of neomycin on electrical light responses, Ca 2+ release, and intracellular Ca 2+ changes in photoreceptors of the honeybee drone

2000 ◽  
Vol 186 (11) ◽  
pp. 1019-1029 ◽  
Author(s):  
Bernd Walz ◽  
Kyrill Ukhanov ◽  
Bernhard Zimmermann
Keyword(s):  
Light Responses ◽  
Intracellular Ca ◽  
Honeybee Drone

scholarly journals An Electrogenic Sodium Pump in Limulus Ventral Photoreceptor Cells

1972 ◽  
Vol 59 (6) ◽  
pp. 720-733 ◽  
Author(s):  
J. E. Brown ◽  
J. E. Lisman
Keyword(s):  
Sodium Pump ◽  
Light Stimulus ◽  
Bright Light ◽  
Receptor Potential ◽  
Photoreceptor Cells ◽  
Intracellular Accumulation ◽  
Light Responses ◽  
Electrogenic Sodium Pump ◽  
Electrogenic Na Pump ◽  
Intracellular Ca

A hyperpolarization can be recorded intracellularly following either a single bright light stimulus or the intracellular injection of Na+. This after-hyperpolarization is abolished by bathing in 5 x 10-6 M strophanthidin or removal of extracellular K+. Both treatments also lead to a small, rapid depolarization of the dark-adapted cell. When either treatment is prolonged, light responses can still be elicited, although with repetitive stimuli the responses are slowly and progressively diminished in size. The rate of diminution is greater for higher values of [Ca++]out; with [Ca++]out = 0.1 mM, there is almost no progressive diminution of repetitive responses produced by either K+-free seawater or strophanthidin. We propose that an electrogenic Na+ pump contributes directly to dark-adapted membrane voltage and also generates the after-hyperpolarizations, but does not directly generate the receptor potential. Inhibition of this pump leads to intracellular accumulation of sodium ions, which in turn leads to an increase in intracellular Ca++ (provided there is sufficient extracellular Ca++). This increase in intracellular calcium probably accounts for the progressive decrease in the size of the receptor potential seen when the pump is inhibited.

Ca-Histochemistry in slime mold plasmodia

1978 ◽  
Vol 36 (2) ◽  
pp. 130-131
Author(s):  
Ulrich Dierkes
Keyword(s):  
Physarum Polycephalum ◽  
Carbon Coating ◽  
Freeze Drying ◽  
Freeze Fracture ◽  
Freeze Substitution ◽  
Uranyl Acetate ◽  
Slime Mold ◽  
Staining Procedure ◽  
Protoplasmic Streaming ◽  
Intracellular Ca

Calcium is supposed to play an important role in the control of protoplasmic streaming in slime mold plasmodia. The motive force for protoplasmic streaming is generated by the interaction of actin and myosin. This contraction is supposed to be controlled by intracellular Ca-fluxes similar to the triggering system in skeleton muscle. The histochemical localisation of calcium however is problematic because of the possible diffusion artifacts especially in aquous media.To evaluate this problem calcium localisation was studied in small pieces of shock frozen (liquid propane at -189°C) plasmodial strands of Physarum polycephalum, which were further processed with 3 different methods: 1) freeze substitution in ethanol at -75°C, staining in 100% ethanol with 1% uranyl acetate, and embedding in styrene-methacrylate. For comparison the staining procedure was omitted in some preparations. 2)Freeze drying at about -95°C, followed by immersion with 100% ethanol containing 1% uranyl acetate, and embedding. 3) Freeze fracture, carbon coating and SEM investigation at temperatures below -100° C.

Nitrogen and Light Responses of Cotton Photosynthesis and Implications for Crop Growth

Crop Science ◽  
2003 ◽  
Vol 43 (3) ◽  
pp. 904 ◽  
Author(s):  
Stephen P. Milroy ◽  
Michael P. Bange
Keyword(s):  
Crop Growth ◽  
Light Responses

scholarly journals Genome communication in plants mediated by organelle–n­ucleus-located proteins

2020 ◽  
Vol 375 (1801) ◽  
pp. 20190397 ◽  
Author(s):  
Karin Krupinska ◽  
Nicolás E. Blanco ◽  
Svenja Oetke ◽  
Michela Zottini
Keyword(s):  
Chloroplast Development ◽  
Cell Cycle Control ◽  
Plastid Transformation ◽  
Light Responses ◽  
Dual Targeting ◽  
Dual Localization ◽  
Retrograde Signalling ◽  
Eukaryotic Proteins ◽  
Plastid Proteins ◽  
Associated Proteins

An increasing number of eukaryotic proteins have been shown to have a dual localization in the DNA-containing organelles, mitochondria and plastids, and/or the nucleus. Regulation of dual targeting and relocation of proteins from organelles to the nucleus offer the most direct means for communication between organelles as well as organelles and nucleus. Most of the mitochondrial proteins of animals have functions in DNA repair and gene expression by modelling of nucleoid architecture and/or chromatin. In plants, such proteins can affect replication and early development. Most plastid proteins with a confirmed or predicted second location in the nucleus are associated with the prokaryotic core RNA polymerase and are required for chloroplast development and light responses. Few plastid–nucleus-located proteins are involved in pathogen defence and cell cycle control. For three proteins, it has been clearly shown that they are first targeted to the organelle and then relocated to the nucleus, i.e. the nucleoid-associated proteins HEMERA and Whirly1 and the stroma-located defence protein NRIP1. Relocation to the nucleus can be experimentally demonstrated by plastid transformation leading to the synthesis of proteins with a tag that enables their detection in the nucleus or by fusions with fluoroproteins in different experimental set-ups. This article is part of the theme issue ‘Retrograde signalling from endosymbiotic organelles’.

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