title: Comparative Developmental Staging of Female and Male Water Fleas Daphnia pulex and Daphnia magna During Embryogenesis.
abstract: The freshwater crustacean genus Daphnia has been used extensively in ecological, developmental and ecotoxicological studies. Daphnids produce only female offspring by parthenogenesis under favorable conditions, but in response to various unfavorable conditions and external stimuli, they produce male offspring. Although we reported that exogenous exposure to juvenile hormones and their analogs can induce male offspring even under female-producing conditions, we recently established a male induction system in the Daphnia pulex WTN6 strain simply by changing day-length. This male and female induction system is suitable for understanding the innate mechanisms of sexual dimorphic development in daphnids. Embryogenesis has been described as a normal plate (developmental staging) in various daphnid species; however, all studies have mainly focused on female development. Here, we describe the developmental staging of both sexes during embryogenesis in two representative daphnids, D. pulex and D. magna, based on microscopic time-course observations. Our findings provide the first detailed insights into male embryogenesis in both species, and contribute to the elucidation of the mechanisms underlying sexual differentiation in daphnids.
authors: 1 Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, and Department of Basic Biology, Faculty of Life Science, SOKENDAI (Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan.
authors: Kenji
authors: K
authors: Toyota
authors: 1 Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, and Department of Basic Biology, Faculty of Life Science, SOKENDAI (Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan.|2 Department of Biology, Center for Liberal Arts and Sciences, Iwate Medical University, 2-1-1, Nishi-Tokuda, Yahaba-cho, Shiwa-gun, Iwate 028-3694, Japan.
authors: Chizue
authors: C
authors: Hiruta
authors: 1 Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, and Department of Basic Biology, Faculty of Life Science, SOKENDAI (Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan.
authors: Yukiko
authors: Y
authors: Ogino
authors: 1 Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, and Department of Basic Biology, Faculty of Life Science, SOKENDAI (Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan.
authors: Shinichi
authors: S
authors: Miyagawa
authors: 3 Institute of Environmental Ecology, IDEA Consultants, Inc., 1334-5 Riemon, Yaizu, Shizuoka 421-0212, Japan.
authors: Tetsuro
authors: T
authors: Okamura
authors: 3 Institute of Environmental Ecology, IDEA Consultants, Inc., 1334-5 Riemon, Yaizu, Shizuoka 421-0212, Japan.
authors: Yuta
authors: Y
authors: Onishi
authors: 4 Environmental Quality Measurement Section, Research Center for Environmental Risk, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
authors: Norihisa
authors: N
authors: Tatarazako
authors: 1 Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, and Department of Basic Biology, Faculty of Life Science, SOKENDAI (Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan.
authors: Taisen
authors: T
authors: Iguchi
mesh_terms: D000818:Animals; D003621:Daphnia / Q000196:embryology*; D047108:Embryonic Development; D005260:Female; D008297:Male; D012737:Sex Factors
keywords: Daphnia magna; Daphnia pulex; developmental staging; normal plate; sexual differentiation