Measurement of the intracellular pH threshold for sperm aster formation in sea urchin eggs

Abstract

In the fertilization of sea urchin eggs, intracellular [Ca2+] (Cai) increases transiently and intracellular pH (pHi) elevates accordingly. Unlinking these two activating factors experimentally, the requirement of the increase in pHi for sperm aster formation in the sea urchin, Clypeaster japonicus, was investigated. When the eggs were injected with an EGTA or BAPTA solution, they incorporated sperm but did not organize the sperm aster. Using these sperm-incorporated eggs under the condition that an increase in Cai was blocked, pHi was regulated by two methods: (i) perfusing ammonium acetate-containing seawater; and (ii) injecting pH buffer solutions of various pH values. By either of the two methods, the sperm aster formed at pHi 7.0 or more and functioned in female pronuclear migration when the sperm aster reached the female pronucleus. Hence, the step of the transient increase in Cai at fertilization can be bypassed. In contrast, a pHi increase is indispensably required for sperm aster formation in sea urchin eggs. Moreover, under the condition that there was the transient increase in Cai, the threshold pHi value for sperm aster formation was pHi 7.0 or more. Consequently, whether a Cai increase on fertilization occurs or not, the threshold pHi value for sperm aster formation is constant in sea urchin eggs.

The soft supersymmetry-breaking Lagrangian: theory and applications

“…[653,654,655] and references therein). The parametric dependence estimate can be written as 42) in which m ν is the neutrino mass scale, M is the right-handed Majorana neutrino mass scale (seesaw scale), v ≈ 246 GeV is the Higgs VEV, T c is the temperature at which Eq.…”

“…There is a large literature on lepton asymmetry computations (see e.g. [653,654,655] and references therein). The parametric dependence estimate can be written as…”

Testing supersymmetric grand unified models of inflation

“…(In general, K is expanded as K = |S| 2 + |φ| 2 + |φ| 2 + α|S| 4 / m 2 P + · · · , and only the |S| 4 term in K generates a mass 2 for S, which would ruin inflation for α ∼ 1 [23,24]. From the requirement σ < m P , one obtains an upper bound on α ( 10 −2 ) [25].) From Eq.…”

Affleck-Dine leptogenesis with varying Peccei-Quinn scale

“…The detailed physical aspects are explained in Ref. [19] and references therein. If m φ = 10 TeV and M * = 7.2 × 10 23 GeV, such early oscillation occurs for T R 10 7 GeV.…”