title: Flagellar quiescence and transience of inactivation induced by rapid pH drop.
abstract: The effects of rapid pH drop on the flagellar movement of reactivated sea urchin sperm were studied by video microscopy and by a newly developed pH jump method. Triton-demembranated sperm were reactivated in a thin layer of the reactivation medium containing ATP and potassium acetate and supported by a ring-shaped Millipore filter stuck to the lower surface of a supported coverslip. The pH of the medium was lowered rapidly by dissolving acetic acid vapor abruptly introduced into a gap between the cover and slide. Flagellar beating ceased immediately when the pH of the reactivation medium was lowered. At least two types of cessation were distinguished: 1) "instantaneous" cessation in a bent form closely resembling those characteristic of steady-state beating before pH drop (waveform freeze), and 2) flagellar quiescence in a cane-shaped form resembling those characteristic of Ca-induced quiescence (cane-shaped quiescence). The flagellum again began beating if the pH was raised to normal but eventually was disintegrated by tubule sliding if the pH was left lowered. Field-by-field analysis of the transient movement of flagella becoming quiescent upon pH drop demonstrated that the proximal bend of the cane-shaped form corresponded to the principal bend of the steady-state beating in some flagella, but in others, to the reverse bend. These observations indicate that low pHs affect flagellar beating by interfering with sliding-bending conversion by a mechanism different from that previously reported.
authors.affiliation: Department of Biology, Ochanomizu University, Tokyo, Japan.
authors.forename: F
authors.initials: F
authors.lastname: Sato
authors.forename: Y
authors.initials: Y
authors.lastname: Mogami
authors.forename: S A
authors.initials: SA
authors.lastname: Baba
mesh_terms: D000818:Animals; D005407:Flagella; D006863:Hydrogen-Ion Concentration; D008297:Male; D012617:Sea Urchins; D013081:Sperm Motility; D014741:Video Recording