title: SEXUALITY AND UNIPARENTAL INHERITANCE OF CHLOROPLAST DNA IN THE ISOGAMOUS GREEN ALGA ULVA COMPRESSA (ULVOPHYCEAE)(1).
abstract: Ulva compressa L. is a heterothallic macroalga considered to be in the early evolutionary stage between isogamy and anisogamy. Two genetic lines of this species, each consisting of gametophytes with opposite mating types, were collected on the coasts of Ehime and Iwate prefectures: MGEC-1 (mt(+) ) and MGEC-2 (mt(-) ) from Ehime, and MGEC-5 (mt(+) ) and MGEC-6 (mt(-) ) from Iwate. Their relative gamete sizes (i.e., cell volumes) do not correspond to their mating types: MGEC-6 (19.8 μm(3) ) > MGEC-1 (18.6 μm(3) ) > MGEC-5 (17.0 μm(3) ) > MGEC-2 (10.1 μm(3) ). The pattern of organelle inheritance is an important sexual characteristic in many eukaryotes. We therefore investigated the relationship between gamete size and the inheritance of chloroplast DNA (cpDNA). Polymorphisms between the cpDNA of the two lines were used as markers. We found a 24 bp insertion between psbF and psbL, and the substitution of a StyI site (from CCAAGG to TCAAGG) in the intergenic region between petD and accD. Two interline crosses (MGEC-1 × MGEC-6 and MGEC-2 × MGEC-5) produced 42 and 38 zygotes, respectively. PCR and PCR-RFLP analyses showed that the cpDNA of the mt(+) gametes was consistently inherited in both crosses. The cpDNA is inherited from one parent only, and it depends not on gamete size but on being mt(+) . The cpDNA was observed during crossing and in the zygotes 6 h after mating. In 6% of the zygotes, the cpDNA derived from the mt(-) gametes disappeared 3-4 h after mating. Preferential digestion of the cpDNA in the zygote's mt(-) gamete may form the basis for uniparental inheritance of cpDNA.
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, JapanDepartment of Marine Science and Technology, Graduate School of Science and Technology, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, JapanDepartment of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Yayoi
authors.initials: Y
authors.lastname: Kagami
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, JapanDepartment of Marine Science and Technology, Graduate School of Science and Technology, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, JapanDepartment of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Mogi
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, JapanDepartment of Marine Science and Technology, Graduate School of Science and Technology, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, JapanDepartment of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Tatsushi
authors.initials: T
authors.lastname: Arai
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, JapanDepartment of Marine Science and Technology, Graduate School of Science and Technology, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, JapanDepartment of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Manami
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, JapanDepartment of Marine Science and Technology, Graduate School of Science and Technology, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, JapanDepartment of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Kuwano
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, JapanDepartment of Marine Science and Technology, Graduate School of Science and Technology, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, JapanDepartment of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Kawano
keywords: DNA marker; Ulva compressa; chloroplast DNA; chloroplast genome; heterothallic; isogamy; sexuality; uniparental inheritance