title: Haemocyanin is essential for embryonic development and survival in the migratory locust.
abstract: Haemocyanins are commonly known as copper-containing oxygen carriers within the haemolymph of arthropods, and have been found in many orders of insects. However, it remains unresolved why haemocyanins persist in insects that possess elaborate tracheal systems for oxygen diffusion to cells. Here we identified haemocyanins in the migratory locust Locusta migratoria that consists of two distinct subunits, Hc1 and Hc2. Genomic sequence analysis indicated that Hc1 and Hc2 have four and three gene copies, respectively, which may have evolved via gene duplication followed by divergent evolution of introns. The two subunits exhibit abundant and embryonic-specific expression at the mRNA and protein level; their expression peaks in the mid-term embryo and is not detectable in the late nymphal and adult stages. A larger proportion of the haemocyanins is present in the yolk compared with that in the embryo. Immunostaining shows that haemocyanins in the embryo are mainly expressed in the epidermis. Knockdown of Hc1 and Hc2 results in significant embryonic developmental delay and abnormality as well as reduced egg hatchability, ie the proportion of hatched eggs. These results reveal a previously unappreciated and fundamental role for haemocyanins in embryonic development and survival in insects, probably involving the exchange of molecules (eg O2 ) between the embryo and its environment.
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
authors.forename: B
authors.initials: B
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
authors.forename: R
authors.initials: R
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.|Department of Plant Protection, Yunnan Agricultural University, Kunming, China.
authors.forename: G
authors.initials: G
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
authors.forename: X
authors.initials: X
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
authors.forename: X
authors.initials: X
authors.lastname: Tong
authors.affiliation: Department of Plant Protection, Yunnan Agricultural University, Kunming, China.
authors.forename: G
authors.initials: G
authors.lastname: Tang
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
authors.forename: L
authors.initials: L
authors.lastname: Kang
mesh_terms: D000818:Animals; D001483:Base Sequence; D020440:Gene Duplication; D018507:Gene Expression Regulation, Developmental; D006433:Hemocyanins / Q000235:genetics*; D048188:Locusta migratoria / Q000196:embryology* / Q000235:genetics; D008969:Molecular Sequence Data; D010063:Ovum / Q000378:metabolism; D010802:Phylogeny; D034622:RNA Interference
chemical_list: D006433:Hemocyanins
keywords: developmental delay; embryonic development; haemocyanin; locust; respiratory protein