title: Impact of TBT on the vitellogenesis and sex hormones in freshwater prawn Macrobrachium rosenbergii (De Man, 1879).
abstract: BACKGROUND
  Tributyltin (TBT) is a ubiquitous persistent xenobiotic that can be found in freshwater, estuarine and marine ecosystem. TBT is a strong endocrine disrupting compound (EDC) that can cause toxic threat to aquatic organisms. Imposex, sexual deformities and endocrine dysfunctions are the causes of TBT to most of the aquatic organisms. Effect of TBT on the vitellogenesis and sex hormonal changes in Macrobrachium rosenbergii has never been reported. Hence, the present investigation was undertaken to find out the impact of TBT on histological changes in the different reproductive tissues, sex hormonal alterations and level of biomarkers like vitellogenin and vitellin in M. rosenbergii.
  
  
  RESULTS
  The present investigation documents the possible impact of tributyltin (TBT) on the vitellogenesis in freshwater female prawn M. rosenbergii. TBT at 10 ng/l, 100 ng/l and 1000 ng/l concentrations were exposed individually to prawns for a period of three months. At higher concentration of 1000 ng/l, the ovarian development was arrested and ovary remained at spent stage. At lower concentration of TBT (10 ng/l), the development proceeded up to early vitellogenic stage. At intermediate concentration of 100 ng/l TBT, the ovary remained at pre vitellogenic stage and thereafter no development was noticed. Histological results indicated the normal ovarian development with vitellogenic oocytes, filled with yolk globules in control prawn. On the other hand, the TBT treated groups showed reduction in yolk globules, fusion of developing oocytes and abundance of immature oocytes. Immunofluorescence staining denoted the remarkable reduction in vitellin content in ovary of TBT treated prawn. Hence, TBT had conspicuously inhibited the vitellogenesis by causing hormonal imbalance in M. rosenbergii.
  
  
  CONCLUSIONS
  TBT had notably inhibited the vitellogenesis due to hormonal imbalance. This endocrine dysfunction ultimately impaired the oogenesis in the freshwater female prawn M. rosenbergii.
authors: Department of Environmental Biotechnology, Bharathidasan University, Trichy 620 024, Tamil nadu, India.
authors: Peranandam
authors: P
authors: Revathi
authors: CAS in Marine Biology, Faculty of Marine Sciences, Annamalai University, Parangipettai 608 502, Tamil nadu, India.
authors: Palanisamy
authors: P
authors: Iyapparaj
authors: Department of Zoology, University of Madras, Guindy Campus, Chennai 600 025, Tamil nadu, India.
authors: Lourduraj Arockia
authors: LA
authors: Vasanthi
authors: Department of Zoology, University of Madras, Guindy Campus, Chennai 600 025, Tamil nadu, India.
authors: Natesan
authors: N
authors: Munuswamy
authors: Department of Environmental Biotechnology, Bharathidasan University, Trichy 620 024, Tamil nadu, India.
authors: Muthukalingan
authors: M
authors: Krishnan
keywords: Macrobrachium rosenbergii; Ovarian development; Sex hormones; Tributyltin; Vitellogenesis
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