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A single and rapid calcium wave at egg activation in Drosophila.

York-Andersen AH, Parton RM, Bi CJ, Bromley CL, Davis I, Weil TT - Biol Open (2015)

Bottom Line: Here, we utilise ratiometric imaging of Ca(2+) indicator dyes and genetically encoded Ca(2+) indicator proteins to identify and characterise a single, rapid, transient wave of Ca(2+) in the Drosophila egg at activation.We further show that mechanical pressure alone is not sufficient to initiate a Ca(2+) wave.We also find that processing bodies, sites of mRNA decay and translational regulation, become dispersed following the Ca(2+) transient.

View Article: PubMed Central - PubMed

Affiliation: Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.

No MeSH data available.


Related in: MedlinePlus

Ca2+ wave is compromised in sra mutant and by actin disruption.(A) sarah mutant mature oocyte expressing UAS-myrGCamp-5. Addition of activation buffer (t = 0′) does not show a change in intracellular Ca2+, while swelling and showing physical changes associated with egg activation (n = 13/14). (B) Mature oocyte microinjected with Calcium Green-1 and Texas Red Dextrans and left for dyes to diffuse for 45 minutes. A low volume injection of 10 mM CaCl2 (t = 10″, white arrowhead) shows a slight local increase in the Ca2+ concentration. Higher volume injection of 10 mM CaCl2 (t = 175″, white arrowhead) shows a clear local rise in the intracellular concentration of Ca2+ detected. Continued observation shows that the local increase in Ca2+ does not cause a wave to propagate in the mature oocyte. (C) Wild-type mature oocyte expressing UAS-myrGCamp-5 cultured in activation buffer with 10 µg/ml cytochalasin-D (n = 21/24 show a complete loss or compromised wave). Intracellular Ca2+ increases from the posterior pole as in wild-type (t = 2′, white arrowhead). This posterior wave fails to move across the entire cell (t = 3′32″, white arrowhead), retracting to the posterior prematurely. A similarly compromised anterior wave fails to propagate fully (t = 7′04″, white arrowhead). Corresponding bright-field images show that swelling and separation of dorsal appendages occur as expected with egg activation. Scale bars A–C = 100 µm. Max projection A =  40 µm, C = 41.5 µm.
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f06: Ca2+ wave is compromised in sra mutant and by actin disruption.(A) sarah mutant mature oocyte expressing UAS-myrGCamp-5. Addition of activation buffer (t = 0′) does not show a change in intracellular Ca2+, while swelling and showing physical changes associated with egg activation (n = 13/14). (B) Mature oocyte microinjected with Calcium Green-1 and Texas Red Dextrans and left for dyes to diffuse for 45 minutes. A low volume injection of 10 mM CaCl2 (t = 10″, white arrowhead) shows a slight local increase in the Ca2+ concentration. Higher volume injection of 10 mM CaCl2 (t = 175″, white arrowhead) shows a clear local rise in the intracellular concentration of Ca2+ detected. Continued observation shows that the local increase in Ca2+ does not cause a wave to propagate in the mature oocyte. (C) Wild-type mature oocyte expressing UAS-myrGCamp-5 cultured in activation buffer with 10 µg/ml cytochalasin-D (n = 21/24 show a complete loss or compromised wave). Intracellular Ca2+ increases from the posterior pole as in wild-type (t = 2′, white arrowhead). This posterior wave fails to move across the entire cell (t = 3′32″, white arrowhead), retracting to the posterior prematurely. A similarly compromised anterior wave fails to propagate fully (t = 7′04″, white arrowhead). Corresponding bright-field images show that swelling and separation of dorsal appendages occur as expected with egg activation. Scale bars A–C = 100 µm. Max projection A =  40 µm, C = 41.5 µm.

Mentions: To explore the relationship between the Ca2+ wave and other aspects of egg activation, we tested mature oocytes mutant for the Drosophila calcipressin, sra, which has previously been shown to block release of the cell cycle (Horner et al., 2006; Takeo et al., 2006). We find that in a sra mutant background ex vivo activated mature oocytes swell normally but no Ca2+wave is detected in 13 of 14 samples (Fig. 6A). The fact that swelling and the initiation and propagation of the Ca2+ wave can be uncoupled in this way shows that swelling is not dependent upon the Ca2+wave and furthermore, swelling alone is not sufficient to initiate and drive the Ca2+ wave. Other factors must be required to couple the two events.


A single and rapid calcium wave at egg activation in Drosophila.

York-Andersen AH, Parton RM, Bi CJ, Bromley CL, Davis I, Weil TT - Biol Open (2015)

Ca2+ wave is compromised in sra mutant and by actin disruption.(A) sarah mutant mature oocyte expressing UAS-myrGCamp-5. Addition of activation buffer (t = 0′) does not show a change in intracellular Ca2+, while swelling and showing physical changes associated with egg activation (n = 13/14). (B) Mature oocyte microinjected with Calcium Green-1 and Texas Red Dextrans and left for dyes to diffuse for 45 minutes. A low volume injection of 10 mM CaCl2 (t = 10″, white arrowhead) shows a slight local increase in the Ca2+ concentration. Higher volume injection of 10 mM CaCl2 (t = 175″, white arrowhead) shows a clear local rise in the intracellular concentration of Ca2+ detected. Continued observation shows that the local increase in Ca2+ does not cause a wave to propagate in the mature oocyte. (C) Wild-type mature oocyte expressing UAS-myrGCamp-5 cultured in activation buffer with 10 µg/ml cytochalasin-D (n = 21/24 show a complete loss or compromised wave). Intracellular Ca2+ increases from the posterior pole as in wild-type (t = 2′, white arrowhead). This posterior wave fails to move across the entire cell (t = 3′32″, white arrowhead), retracting to the posterior prematurely. A similarly compromised anterior wave fails to propagate fully (t = 7′04″, white arrowhead). Corresponding bright-field images show that swelling and separation of dorsal appendages occur as expected with egg activation. Scale bars A–C = 100 µm. Max projection A =  40 µm, C = 41.5 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4400597&req=5

f06: Ca2+ wave is compromised in sra mutant and by actin disruption.(A) sarah mutant mature oocyte expressing UAS-myrGCamp-5. Addition of activation buffer (t = 0′) does not show a change in intracellular Ca2+, while swelling and showing physical changes associated with egg activation (n = 13/14). (B) Mature oocyte microinjected with Calcium Green-1 and Texas Red Dextrans and left for dyes to diffuse for 45 minutes. A low volume injection of 10 mM CaCl2 (t = 10″, white arrowhead) shows a slight local increase in the Ca2+ concentration. Higher volume injection of 10 mM CaCl2 (t = 175″, white arrowhead) shows a clear local rise in the intracellular concentration of Ca2+ detected. Continued observation shows that the local increase in Ca2+ does not cause a wave to propagate in the mature oocyte. (C) Wild-type mature oocyte expressing UAS-myrGCamp-5 cultured in activation buffer with 10 µg/ml cytochalasin-D (n = 21/24 show a complete loss or compromised wave). Intracellular Ca2+ increases from the posterior pole as in wild-type (t = 2′, white arrowhead). This posterior wave fails to move across the entire cell (t = 3′32″, white arrowhead), retracting to the posterior prematurely. A similarly compromised anterior wave fails to propagate fully (t = 7′04″, white arrowhead). Corresponding bright-field images show that swelling and separation of dorsal appendages occur as expected with egg activation. Scale bars A–C = 100 µm. Max projection A =  40 µm, C = 41.5 µm.
Mentions: To explore the relationship between the Ca2+ wave and other aspects of egg activation, we tested mature oocytes mutant for the Drosophila calcipressin, sra, which has previously been shown to block release of the cell cycle (Horner et al., 2006; Takeo et al., 2006). We find that in a sra mutant background ex vivo activated mature oocytes swell normally but no Ca2+wave is detected in 13 of 14 samples (Fig. 6A). The fact that swelling and the initiation and propagation of the Ca2+ wave can be uncoupled in this way shows that swelling is not dependent upon the Ca2+wave and furthermore, swelling alone is not sufficient to initiate and drive the Ca2+ wave. Other factors must be required to couple the two events.

Bottom Line: Here, we utilise ratiometric imaging of Ca(2+) indicator dyes and genetically encoded Ca(2+) indicator proteins to identify and characterise a single, rapid, transient wave of Ca(2+) in the Drosophila egg at activation.We further show that mechanical pressure alone is not sufficient to initiate a Ca(2+) wave.We also find that processing bodies, sites of mRNA decay and translational regulation, become dispersed following the Ca(2+) transient.

View Article: PubMed Central - PubMed

Affiliation: Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.

No MeSH data available.


Related in: MedlinePlus