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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

Osmotically induced swelling of the mature oocyte results in an increase in Ca2+ and lysis.(A,B) Time series of a mature oocyte expressing UAS-myrGCaMP5 following the addition of 10 mM CaCl2 (A) or water (B). (A) Addition of 10 mM CaCl2 results in a rapid cortical increase in intracellular Ca2+, accelerated swelling and lysis (n = 8). (B) Addition of water causes a rapid increase in intracellular Ca2+ around the circumference of the cell (n = 10). The cell recovers to pre-activation levels before showing second increase in intracellular Ca2+ before lysis. Corresponding bright-field images show a continued swelling of the mature oocyte until lysis. Scale bars A,B = 100 µm. Max projection A = 27.7 µm, B = 41 µm.
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f03: Osmotically induced swelling of the mature oocyte results in an increase in Ca2+ and lysis.(A,B) Time series of a mature oocyte expressing UAS-myrGCaMP5 following the addition of 10 mM CaCl2 (A) or water (B). (A) Addition of 10 mM CaCl2 results in a rapid cortical increase in intracellular Ca2+, accelerated swelling and lysis (n = 8). (B) Addition of water causes a rapid increase in intracellular Ca2+ around the circumference of the cell (n = 10). The cell recovers to pre-activation levels before showing second increase in intracellular Ca2+ before lysis. Corresponding bright-field images show a continued swelling of the mature oocyte until lysis. Scale bars A,B = 100 µm. Max projection A = 27.7 µm, B = 41 µm.

Mentions: In order to better understand the basis of the Ca2+ wave during activation by standard hypotonic activation buffer, we tested if the application of solutions with different properties had an effect on intracellular Ca2+ in the egg. We already showed that Schneider's Insect medium (5.4 mM CaCl2, 2.7× more CaCl2 than in activation buffer) did not trigger a Ca2+ transient or activation. However, addition of 10 mM CaCl2, which is five times more concentrated than the CaCl2 in activation buffer, caused a rapid increase in intracellular Ca2+ from all regions of the cortex, accelerated swelling and lysis within minutes (Fig. 3A). Next, we demonstrated that altering the membrane potential, through the application of a high potassium medium (Ataman et al., 2008), caused no swelling or intracellular Ca2+ change (data not shown). Finally, we showed that hypo-osmotic shock by addition of dH2O promotes accelerated swelling as well as an increase in Ca2+ in the egg (Fig. 3B). Interestingly, with the addition of water we often observe a recovery of intracellular Ca2+ to normal levels and occasionally a second increase in Ca2+ (Fig. 3B). Together, this data suggests that mechanical pressure from hypo-osmotically induced swelling is a likely mechanism for initiation of the Ca2+ wave, possibly initially triggered by entry of external Ca2+. The data also shows that while the egg chamber is clearly capable of multiple transients, activation involves only a single propagating wave.


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)

Osmotically induced swelling of the mature oocyte results in an increase in Ca2+ and lysis.(A,B) Time series of a mature oocyte expressing UAS-myrGCaMP5 following the addition of 10 mM CaCl2 (A) or water (B). (A) Addition of 10 mM CaCl2 results in a rapid cortical increase in intracellular Ca2+, accelerated swelling and lysis (n = 8). (B) Addition of water causes a rapid increase in intracellular Ca2+ around the circumference of the cell (n = 10). The cell recovers to pre-activation levels before showing second increase in intracellular Ca2+ before lysis. Corresponding bright-field images show a continued swelling of the mature oocyte until lysis. Scale bars A,B = 100 µm. Max projection A = 27.7 µm, B = 41 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4400597&req=5

f03: Osmotically induced swelling of the mature oocyte results in an increase in Ca2+ and lysis.(A,B) Time series of a mature oocyte expressing UAS-myrGCaMP5 following the addition of 10 mM CaCl2 (A) or water (B). (A) Addition of 10 mM CaCl2 results in a rapid cortical increase in intracellular Ca2+, accelerated swelling and lysis (n = 8). (B) Addition of water causes a rapid increase in intracellular Ca2+ around the circumference of the cell (n = 10). The cell recovers to pre-activation levels before showing second increase in intracellular Ca2+ before lysis. Corresponding bright-field images show a continued swelling of the mature oocyte until lysis. Scale bars A,B = 100 µm. Max projection A = 27.7 µm, B = 41 µm.
Mentions: In order to better understand the basis of the Ca2+ wave during activation by standard hypotonic activation buffer, we tested if the application of solutions with different properties had an effect on intracellular Ca2+ in the egg. We already showed that Schneider's Insect medium (5.4 mM CaCl2, 2.7× more CaCl2 than in activation buffer) did not trigger a Ca2+ transient or activation. However, addition of 10 mM CaCl2, which is five times more concentrated than the CaCl2 in activation buffer, caused a rapid increase in intracellular Ca2+ from all regions of the cortex, accelerated swelling and lysis within minutes (Fig. 3A). Next, we demonstrated that altering the membrane potential, through the application of a high potassium medium (Ataman et al., 2008), caused no swelling or intracellular Ca2+ change (data not shown). Finally, we showed that hypo-osmotic shock by addition of dH2O promotes accelerated swelling as well as an increase in Ca2+ in the egg (Fig. 3B). Interestingly, with the addition of water we often observe a recovery of intracellular Ca2+ to normal levels and occasionally a second increase in Ca2+ (Fig. 3B). Together, this data suggests that mechanical pressure from hypo-osmotically induced swelling is a likely mechanism for initiation of the Ca2+ wave, possibly initially triggered by entry of external Ca2+. The data also shows that while the egg chamber is clearly capable of multiple transients, activation involves only a single propagating wave.

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