Molecular cloning of cDNA of mammalian and chicken II gonadotropin-releasing hormones (mGnRHs and cGnRH-II) in the beluga (Huso huso) and the disruptive effect of methylmercury on gene expression.
Two gonadotropin-releasing hormone (GnRH) isoforms were identified in the beluga (Huso huso) brain by cDNA sequencing: prepro-mammalian GnRH (mGnRH) and prepro-chicken GnRH-II (cGnRH-II). The nucleotide sequences of the beluga mGnRH and cGnRH-II precursors are 273 and 258 base pairs (bp) long, encoding peptides of 91 and 86 amino acids, respectively. To investigate the effect of methylmercury (MeHg) on GnRH gene expression, animals were fed with four diets containing increasing levels of MeHg (0 mg kg(-1) [control]; 0.76 mg kg(-1) [low]; 7.8 mg kg(-1) [medium]; 16.22 mg kg(-1) [high]) for 32 days. The effects of MeHg on brain GnRH mRNA levels were evaluated by real-time PCR. A significant decrease in brain mGnRH and cGnRH-II mRNA levels were detected in fish receiving high dietary MeHg dose compared to controls on day 11 (P < 0.05). On day 18 and 32, all treatment groups had significantly lower brain mGnRH and cGnRH-II mRNA levels compared to the control group (P < 0.05). These findings demonstrate a disruptive role of MeHg on the level of brain mGnRH and cGnRH-II mRNAs in immature beluga.
Gharaei
Ahmad
A
Department of Fisheries, Faculty of Natural Resources, Universityof Zabol, P.O.Box 98615-538, Zabol, Sistan & Blouchestan, Iran. agharaei551@gmail.com.
Mahboudi
Fereidoun
F
Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran.
Esmaili-Sari
Abbas
A
Department of Environment, Faculty of Natural Resources and Marine Science, Tarbiat Modares University, Noor, Mazandaran, Iran.
Edalat
Rozita
R
Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran.
Adeli
Ahmad
A
Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran.
Keyvanshokooh
Saeed
S
Department of Fisheries, Faculty of Marine Natural Resources, Khorramshahr University of Marine Science and Technology, Khorramshahr, Khouzestan, Iran.
D000595:Amino Acid Sequence; D000704:Analysis of Variance; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism*; D002645:Chickens; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D005399:Fishes / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics* / Q000378:metabolism; D008767:Methylmercury Compounds / Q000008:administration & dosage / Q000633:toxicity*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
D017931:DNA Primers; D018076:DNA, Complementary; D008767:Methylmercury Compounds; D012333:RNA, Messenger; D007987:Gonadotropin-Releasing Hormone; C004925:methylmercuric chloride