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Journal of Applied Phycology

, Volume 16, Issue 6, pp 519–521 | Cite as

Effect of light period on egg-discharge of gametophyte clones of Undaria pinnatifida (Phaeophyta)

  • Jianxin Liu
  • Liangfeng Dong
  • Yaoqing Shen
  • Chaoyuan Wu
Article

Abstract

A sporeling culture method using gametophyte clones developed in the early 1990s led to egg discharge occurring in the dark 5 min after the start of the dark period under growth under a 11:13 L-D photoperiod. The course of egg discharge could be disturbed by light, with irradiance as low as 5–6 μmol photon m−2 s−1 causing 75–80% of the discharged eggs to detach from the oogonia and consequently to die within several hours. In order to enhance outgrowth rate of young sporophytes, a study was conducted to test the effect of controlling darkness in the period 2–3 h after dusk. When the slides were transferred from the standard 11:13 L-D regime to continuous light, eggs were discharged 5 min after the end of the light phase and peaked 5–l5 min later on first day after transfer, indicating that the female gametes “remember” the light-dark regime. This suggests the existence of an endogenous circadian rhythm. During the second and third days, very few eggs were discharged throughout the 11 h of the normal light phase of the L-D regime, indicating the inhibitory effect of continuous light and that the rhtyhm is easily damped by light.

Key Words

circadian rhythm egg discharge gametophyte clone sporeling culture Undaria pinnatifida 

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Copyright information

© Springer Science + Business Media, Inc. 2004

Authors and Affiliations

  • Jianxin Liu
    • 1
  • Liangfeng Dong
    • 1
  • Yaoqing Shen
    • 1
  • Chaoyuan Wu
    • 1
  1. 1.Institute of OceanologyChinese Academy of SciencesQingdaoP. R. China

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