title: Bicarbonate enhances synchronous division of the giant nuclei of sporophytes in Bryopsis plumosa.
abstract: A mature sporophyte of Bryopsis plumosa (Hudson) C. Agardh forms a huge number of zoospores in its cell continuum. Zoospore formation starts with the division of a single giant nucleus and subsequent repeated mitosis. We found that an elevation of photosynthetic activity triggered the division of a mature giant nucleus. Transfer to short-day conditions was not necessary. Giant nuclei did not divide in darkness or in the presence of 1 micro M DCMU. Giant nuclei of as many as 90% of sporophtyes started to divide following the addition of 5 microM NaHCO3 to the growth medium under continuous white light (6-12 W m(-2)). Frequency of nuclear division increased with increased light intensity. By combining those parameters that promoted the division of giant nuclei, we developed the "two-step culture method" which is composed of preliminary and main cultures. This new method guarantees that giant nuclei of more than 90% of all sporophytes synchronously divide between 72 and 96 h after the transfer to the main culture (continuous white light of 12 W m(-2) in PES medium supplemented with 5 mM NaHCO3).
authors.affiliation: Department of Biology, Faculty of Biology, Yamagata University, Kojirakawa, Yamagata 990-8560, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamagishi
authors.forename: Tasuku
authors.initials: T
authors.lastname: Hishinuma
authors.forename: Hironao
authors.initials: H
authors.lastname: Kataoka
mesh_terms: D002455:Cell Division / Q000187:drug effects* / Q000502:physiology; D002467:Cell Nucleus / Q000187:drug effects* / Q000502:physiology; D000460:Chlorophyta / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology; D004396:Coloring Agents; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology; D008027:Light; D017440:Photoperiod; D017693:Sodium Bicarbonate / Q000494:pharmacology*; D013172:Spores, Fungal / Q000187:drug effects*
chemical_list: D004396:Coloring Agents; D003470:Culture Media; D017693:Sodium Bicarbonate