title: Transcriptomic alterations in Daphnia magna embryos from mothers exposed to hypoxia.
abstract: Hypoxia occurs when dissolved oxygen (DO) falls below 2.8mgL(-1) in aquatic environments. It can cause trans-generational effects not only in fish, but also in the water fleas Daphnia. In this study, transcriptome sequencing analysis was employed to identify transcriptomic alterations induced by hypoxia in embryos of Daphnia magna, with an aim to investigate the mechanism underlying the trans-generational effects caused by hypoxia in Daphnia. The embryos (F1) were collected from adults (F0) that were previously exposed to hypoxia (or normoxia) for their whole life. De novo transcriptome assembly identified 18270 transcripts that were matched to the UniProtKB/Swiss-Prot database and resulted in 7419 genes. Comparative transcriptome analysis showed 124 differentially expressed genes, including 70 up- and 54 down-regulated genes under hypoxia. Gene ontology analysis further highlighted three clusters of genes which revealed acclimatory changes of haemoglobin, suppression in vitellogenin gene family and histone modifications. Specifically, the expressions of histone H2B, H3, H4 and histone deacetylase 4 (HDAC4) were deregulated. This study suggested that trans-generational effects of hypoxia on Daphnia may be mediated through epigenetic regulations of histone modifications.
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong, Hong Kong.
authors.forename: Keng-Po
authors.initials: KP
authors.lastname: Lai
authors.affiliation: School of Life Sciences, Hong Kong Bioinformatics Centre, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Jing-Woei
authors.initials: JW
authors.lastname: Li
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong.
authors.forename: Christine Ying-Shan
authors.initials: CY
authors.lastname: Chan
authors.affiliation: School of Life Sciences, Hong Kong Bioinformatics Centre, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Ting-Fung
authors.initials: TF
authors.lastname: Chan
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Hong Kong.
authors.forename: Karen Wing-Yee
authors.initials: KW
authors.lastname: Yuen
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong. Electronic address: jillchiu@hkbu.edu.hk.
authors.forename: Jill Man-Ying
authors.initials: JM
authors.lastname: Chiu
mesh_terms: D000818:Animals; D016000:Cluster Analysis; D055028:Comparative Genomic Hybridization; D003621:Daphnia / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism; D006655:Histone Deacetylases / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D000860:Hypoxia; D017422:Sequence Analysis, DNA; D059467:Transcriptome; D014819:Vitellogenins / Q000235:genetics / Q000378:metabolism
chemical_list: D006454:Hemoglobins; D006657:Histones; D014819:Vitellogenins; D006655:Histone Deacetylases
keywords: Embryonic development; Haemoglobin; Histone; Trans-generational effect; Vitellogenin