Scintillons: The Biochemistry of Dinoflagellate Bioluminescence

Hastings, J. W.; Vergin, Marcia; DeSa, Richard J.

doi:10.1515/9781400875689-021

Cited by 13 publications

(17 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The action potential triggers luminescence that originates in numerous discrete sources (80–83, 220). These microsources have been named “scintillons” (78, 111), and are filled with luciferin, luciferase, and luciferin binding protein (95, 96, 237). Fig.…”

Section: Introductionmentioning

confidence: 99%

Voltage‐Gated Proton Channels

DeCoursey

2012

Comprehensive Physiology

View full text Add to dashboard Cite

Voltage‐gated proton channels, H V 1, have vaulted from the realm of the esoteric into the forefront of a central question facing ion channel biophysicists, namely, the mechanism by which voltage‐dependent gating occurs. This transformation is the result of several factors. Identification of the gene in 2006 revealed that proton channels are homologues of the voltage‐sensing domain of most other voltage‐gated ion channels. Unique, or at least eccentric, properties of proton channels include dimeric architecture with dual conduction pathways, perfect proton selectivity, a single‐channel conductance approximately 10 3 times smaller than most ion channels, voltage‐dependent gating that is strongly modulated by the pH gradient, ΔpH, and potent inhibition by Zn 2+ (in many species) but an absence of other potent inhibitors. The recent identification of H V 1 in three unicellular marine plankton species has dramatically expanded the phylogenetic family tree. Interest in proton channels in their own right has increased as important physiological roles have been identified in many cells. Proton channels trigger the bioluminescent flash of dinoflagellates, facilitate calcification by coccolithophores, regulate pH‐dependent processes in eggs and sperm during fertilization, secrete acid to control the pH of airway fluids, facilitate histamine secretion by basophils, and play a signaling role in facilitating B‐cell receptor mediated responses in B‐lymphocytes. The most elaborate and best‐established functions occur in phagocytes, where proton channels optimize the activity of NADPH oxidase, an important producer of reactive oxygen species. Proton efflux mediated by H V 1 balances the charge translocated across the membrane by electrons through NADPH oxidase, minimizes changes in cytoplasmic and phagosomal pH, limits osmotic swelling of the phagosome, and provides substrate H + for the production of H 2 O 2 and HOCl, reactive oxygen species crucial to killing pathogens. © 2012 American Physiological Society. Compr Physiol 2:1355‐1385, 2012.

show abstract

Section: Introductionmentioning

confidence: 99%

Voltage‐Gated Proton Channels

DeCoursey

2012

Comprehensive Physiology

View full text Add to dashboard Cite

show abstract

“…On the PF face of this membrane (Fig. 7) are many particles, about 4,000/t~mL In the lumen of the peripheral vesicle are found the crystals formerly thought to be the source of bioluminescence in Gonyaulax (13) but now considered to be guanine (9) (Fig. 7).…”

Section: Resultsmentioning

confidence: 99%

Freeze-fracture studies of the thecal membranes of Gonyaulax polyedra: circadian changes in the particles of one membrane face.

Sweeney¹

1976

The Journal of Cell Biology

View full text Add to dashboard Cite

Intramembrane faces were visualized in the marine dinoflagellate Gonyaulax polyedra by the freeze-fracture technique, in order to test a prediction of a membrane model for circadian oscillations--i.e., that membrane particle distribution and size change with time in the circadian cycle. Cells from each of four cell suspensions in continuous light (500 Ix,(20)(21) were frozen, without fixation or cryoprotection, at four circadian times in a cycle. This paper reports findings concerning the membranes associated with the theca, particularly the cytoplasmic membrane and the membrane of the large peripheral vesicle. While the number and size distribution of the particles of the PF face of the cytoplasmic membrane were constant with time, those of the EF face of the peripheral vesicle doubled in number at 18 h circadian time as compared with 06 h. Particles of the 120-A size class, in particular, were more numerous at 12 and 18 h circadian time than at 00 and 06 h. While the finding does not provide definitive confirmation of the membrane hypothesis for circadian rhythms, it is consistent with this model. It is suggested that the peripheral vesicle may be the site of bioluminescence in Gonyaulax.The circadian rhythms of the dinoflagellate Go~ nyaulax polyedra are probably the most thoroughly investigated of any rhythms in unicellular organisms (12,28,31,32). One circadian system controls both stimulated and spontaneous bioluminescence, photosynthetic capacity, and cell division in this organism (20). The manner by which such diverse processes are coordinated within a circadian framework presents a formidable problem. Recently it has been suggested that the common denominator may be membrane localization of key biochemical steps in these processes (4,8,25,30). The pigments and enzymes of photosynthesis are associated with the thylakoid membranes of the chloroplast, and evidence has accumulated that the enzyme and substrate which produce bioluminescence are membrane bound (9). The control of cell division is less well understood, but this process may depend on the electrical properties of the cell membrane (19). These considerations have given rise to a membrane model for the generation of circadian oscillations (21,29).in view of the importance of membranes to the overt rhythmic processes, and possibly to circadian timing itself, an investigation of the ultrastructure of the various membranes of Gonyaulax seemed appropriate. Furthermore, the membrane model for the feedback generation of rhythms predicts that membrane particle number and distribution alter over circadian time. A direct examination of these particles at different circadian times might thus provide a test of this hypothesis.

show abstract

“…The duration of bioluminescent flashes in vivo and in vitro has been measured to be ~ 100 ms (19), whereas the flash duration illustrated in Fig. 5 is -300 ms.…”

Section: Autofluorescent Particles Are the Source Of Bioluminescence mentioning

confidence: 97%

“…Previous work had characterized the scintillon as a selfcontained sedimentable particle that emitted a light flash upon rapid acidification (19). When Gonyaulax extracts were centrifuged into a sucrose gradient, the scintillon activity cosediments with the fluorescent particles (Fig.…”

Section: Autofluorescent Particles In Vitromentioning

confidence: 99%

“…Some portion of luciferase is definitely associated with scintillons (20), but the reported relative proportion of luciferase in the scintillon vs soluble pools varies considerably (19,23,37). This reported variability certainly derives in part from differences in extraction procedures and the time of the circadian cycle chosen for extraction, but it has been difficult to eliminate extraction artifacts when the only assay of the enzyme's localization has been its activity in vitro.…”

Section: Compartmentalization Of Bioluminescence Componentsmentioning

confidence: 99%

See 1 more Smart Citation

Compartmentalization of algal bioluminescence: autofluorescence of bioluminescent particles in the dinoflagellate Gonyaulax as studied with image-intensified video microscopy and flow cytometry.

Johnson¹,

Inoue²,

Flint³

et al. 1985

The Journal of Cell Biology

View full text Add to dashboard Cite

Compartmentalization of specialized functions to discrete locales is a fundamental theme of eucaryotic organization in cells. We report here that bioluminescence of the dinoflagellate alga Gonyaulax originates in vivo from discrete subcellular loci that are intrinsically fluorescent. We demonstrate this localization by comparing the loci of fluorescence and bioluminescence as visualized by image-intensified video microscopy. These fluorescent particles appeared to be the same as the previously described in vitro "scintillons." We attribute the endogenous fluorescence to that of the bioluminescence substrate, luciferin, because (a) the fluorescence excitation and emission characteristics are comparable, (b) the autofluorescence is lost after exhaustive stimulation of bioluminescence, and (c) the fluorescence of discharged particles in vitro can be restored by adding luciferin. The fluorescence in vivo exhibits a standard property of circadian (daily) rhythmicity: under constant environmental conditions, the intensity of the particle fluorescence fluctuates cyclically (it is maximal during the night phase and is low during the day). Thus, luciferin is localized within the cell at discrete loci from which the bioluminescence emanates; the cellular quantity of luciferin is rhythmically modulated by the circadian clock.

show abstract

Scintillons: The Biochemistry of Dinoflagellate Bioluminescence

Cited by 13 publications

References 0 publications

Voltage‐Gated Proton Channels

Voltage‐Gated Proton Channels

Freeze-fracture studies of the thecal membranes of Gonyaulax polyedra: circadian changes in the particles of one membrane face.

Compartmentalization of algal bioluminescence: autofluorescence of bioluminescent particles in the dinoflagellate Gonyaulax as studied with image-intensified video microscopy and flow cytometry.

Contact Info

Product

Resources

About