title: Comparison of Egg Envelope Thickness in Teleosts and its Relationship to the Sites of ZP Protein Synthesis.
abstract: Teleost egg envelope generally consists of a thin outer layer and a thick inner layer. The inner layer of the Pacific herring egg envelope is further divided into distinct inner layers I and II. In our previous study, we cloned four zona pellucida (ZP) proteins (HgZPBa, HgZPBb, HgZPCa, and HgZPCb) from Pacific herring, two of which (HgZPBa and HgZPCa) were synthesized in the liver and two (HgZPBb and HgZPCb) in the ovary. In this study, we raised antibodies against these four proteins to identify their locations using immunohistochemistry. Our results suggest that inner layer I is constructed primarily of HgZPBa and Ca, whereas inner layer II consists primarily of HgZPBa. HgZPBb and Cb were minor components of the envelope. Therefore, the egg envelope of Pacific herring is primarily composed of liver-synthesized ZP proteins. A comparison of the thickness of the fertilized egg envelopes of 55 species suggested that egg envelopes derived from liver-synthesized ZP proteins tended to be thicker in demersal eggs than those in pelagic eggs, whereas egg envelopes derived from ovarian-synthesized ZP proteins had no such tendency. Our comparison suggests that the prehatching period of an egg with a thick egg envelope is longer than that of an egg with a thin egg envelope. We hypothesized that acquisition of liver-synthesized ZP proteins during evolution conferred the ability to develop a thick egg envelope, which allowed species with demersal eggs to adapt to mechanical stress in the prehatching environment by thickening the egg envelope, while pelagic egg envelopes have remained thin.
authors.affiliation: Department of Chemistry, Faculty of Science, Josai University, Sakado, Saitama, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Sano
authors.affiliation: Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Chiyoda-ku, Tokyo, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Kawaguchi
authors.affiliation: Department of Chemistry, Faculty of Science, Josai University, Sakado, Saitama, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Katano
authors.affiliation: Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Tomita
authors.affiliation: Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Mayu
authors.initials: M
authors.lastname: Inokuchi
authors.affiliation: Department of Anatomy, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan.
authors.forename: Tatsuki
authors.initials: T
authors.lastname: Nagasawa
authors.affiliation: Department of Anatomy, St. Marianna University School of Medicine, Miyamae-ku, Kawasaki, Japan.
authors.forename: Junya
authors.initials: J
authors.lastname: Hiroi
authors.affiliation: Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Toyoji
authors.initials: T
authors.lastname: Kaneko
authors.affiliation: Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kitagawa
authors.affiliation: Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Fujimoto
authors.affiliation: Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan.
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Arai
authors.affiliation: International Institute for Advanced Studies, Kizugawa-shi, Kyoto, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Tanaka
authors.affiliation: Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Chiyoda-ku, Tokyo, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Yasumasu
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D005075:Biological Evolution; D003001:Cloning, Molecular; D004527:Egg Proteins / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D005399:Fishes / Q000235:genetics / Q000254:growth & development; D010053:Ovary / Q000254:growth & development / Q000378:metabolism; D010063:Ovum / Q000254:growth & development / Q000378:metabolism*; D015044:Zona Pellucida / Q000378:metabolism*; D000072216:Zona Pellucida Glycoproteins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D004527:Egg Proteins; D000072216:Zona Pellucida Glycoproteins