title: Identification and Expression Analysis of Upregulated Genes in the Resting Egg-Producing Water Flea (Daphnia pulex).
abstract: Water fleas (Daphnia pulex) normally produce subitaneous eggs that initiate development immediately after oviposition. However, in response to habitat degradation, resting eggs are produced, which are enclosed in a sturdy outer envelope (ephippium) and can survive in harsh environments for an extended time. To understand the molecular mechanism underlying resting egg production in D. pulex, we investigated the genes whose expression patterns played a role in the production and identified the following six candidate genes: Dpfa-1, Dpfa-2, Dpep-1, Dpep-2, Dpep-3, and Dpep-4. These six genes displayed > 40-fold higher expression levels in resting egg-producing animals compared with those in subitaneous egg-producing animals at the period when the ovaries were mature. Dpfa-1 and Dpfa-2 were expressed in the fat cells, and their expression patterns were synchronized with the development of resting egg oocytes in the ovary. In contrast, Dpep-1-4 were expressed in the morphologically altered epidermal cells of the brood chamber with the formation of the ephippium, and their expression patterns were also related to ephippium formation. Our results suggest that the former two genes encode the resting egg-specific components produced by fat cells and that the latter four genes encode the components related to the ephippium formation synthesized by epidermal cells.
authors: Department of Biology, School of Medicine, Kurume University, Fukuoka 830-0011, Japan.
authors: Tomoko
authors: T
authors: Takahashi
authors: Department of Biology, School of Medicine, Kurume University, Fukuoka 830-0011, Japan.
authors: Masaaki
authors: M
authors: Ohnuma
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003621:Daphnia / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D055554:Hemoglobin Subunits / Q000235:genetics / Q000378:metabolism; D010063:Ovum / Q000502:physiology*; D015854:Up-Regulation
chemical_list: D055554:Hemoglobin Subunits
keywords: Daphnia reproduction; ephippium formation; epidermal cell; fat cell; resting egg