Developmental Biology In fertilization how is the calcium wa

Developmental Biology:

In fertilization, how is the calcium wave initiated in amphibians? Compare and contrast the amphibian situation with mammals and sea urchins.

I was given this paper to help, however I\'m having a difficult time following it.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3922219/

Solution

In development of a body, for calcium stimulation, IP3 (inositol 1,4,5-trisphosphate ) is required for releasing of calcium as it acts as the precursor for the same.

In the case of Xenopus laevis , an src tyrosine kinase has been found to be activated which increases the IP3 concentratin, by activating Phospholipase C gamma or (Plc gamma), as a result, increasing the total amount of inorganic calcium that is being generated. Thus, simulating and increasing calcium concentration. Here, it has been noted, that sperms activate phospholipase D, which increases or doubles the amount of plc gamma thus increasing inorganic calcium. Adverse effects of inactivating PA has also been seen which inhibited the activation of Src thus reduction in Ca formation.

During mammalian egg development, intracellular signalling of Ca ions is done by mitochondria and endoplasmic reticulum. The ER contains Ca2+ pumps, intraluminal Ca2+ storage proteins, and specific Ca2+ - releasing channels, which together regulate Ca2+ signaling while maintaining cellular Ca2+homeostasis.

Mitochondria regulate the concentration as being a buffer for the calcium channels. Ca2+ enters mitochondria when the Ca2+ concentration in the cytoplasm is over a certain threshold, and once the cytoplasmic Ca2+ has returned to its resting level, Ca2+ is pumped back into cytoplasm by the Na+/Ca2+ exchanger.

Unlike Xenopus, where the calcium levels are maintained by an enzyme, here, the calcium levels are maintained by the cell organelles and also regulated by the same.