Integrative omics analysis reveals differentially distributed proteins in dimorphic euspermatozoa of the squid, Loligo bleekeri.
In the coastal squid Loligo bleekeri, each male produces one of two types of fertilization-competent spermatozoa (eusperm) that exhibit morphological and behavioral differences. Large "consort" males produce short-tailed spermatozoa that display free-swimming behavior when ejaculated into seawater. Small "sneaker" males, on the other hand, produce long-tailed spermatozoa that exhibit a self-swarming trait after ejaculation. To understand the molecular basis for adaptive traits employed by alternative male mating tactics, we performed the transcriptome deep sequencing (RNA-seq) and proteome analyses to search for differences in testicular mRNAs and sperm proteins, respectively. From mature male testes we identified a total of 236,455 contigs (FPKM ≧1) where 3789 and 2789 were preferentially (≧10-fold) expressed in consort and sneaker testes, respectively. A proteomic analysis detected 4302 proteins in the mature sperm as post-translational products. A strongly biased (≧10-fold) distribution occurred in 55 consort proteins and 61 sneaker proteins. There was no clear mRNA-protein correlation, making a ballpark estimate impossible for not only overall protein abundance but also the degree of biased sperm type expressed in the spermatozoa. A family encoding dynein heavy chain gene, however, was found to be biased towards sneakers, whereas many enzymes involving energy metabolism were heavily biased towards consort spermatozoa. The difference in flagellar length matched exactly the different amount of tubulins. From these results we hypothesize that discrete differential traits in dimorphic eusperm arose from a series of innovative alterations in the intracellular components of spermatozoa.
National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan; Research Fellow of the Japan Society for the Promotion of Science, Japan.
Masa-aki
MA
Yoshida
Sugashima Marine Biological Laboratory Graduate School of Science, Nagoya University, 429-63 Sugashima, Toba 517-0004, Japan.
Lixy
L
Yamada
Department of Biological Sciences, Ochanomizu University, 2-1-1 Ohtsuka, Bunkyo-ku, Tokyo 112-8610, Japan.
Hiroe
H
Ochi
Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Japan.
Yoko
Y
Iwata
Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan.
Miwa
M
Tamura-Nakano
Sugashima Marine Biological Laboratory Graduate School of Science, Nagoya University, 429-63 Sugashima, Toba 517-0004, Japan.
Hitoshi
H
Sawada
Department Ichthyology and Fisheries Science, Rhodes University, Grahamstown, South Africa.
Warwick H H
WH
Sauer
Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama 526-0829, Japan.
Atsushi
A
Ogura
Oki Marine Biological Station, Shimane University, 194 Kamo, Okinoshima-cho, Oki, Shimane 685-0024, Japan. Electronic address: hiro@life.shimane-u.ac.jp.
Noritaka
N
Hirohashi
D000818:Animals; D004398:Dyneins / Q000235:genetics / Q000378:metabolism; D049834:Loligo / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D008297:Male; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D020543:Proteome; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013094:Spermatozoa / Q000145:classification / Q000166:cytology* / Q000378:metabolism*; D059467:Transcriptome
D011506:Proteins; D020543:Proteome; D012333:RNA, Messenger; D004398:Dyneins
Alternative reproductive tactics; Male dimorphism; Proteomics; RNA-seq; Sperm evolution; Transcriptome