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Follicle-stimulating hormone beta subunit (FSHbeta) and luteinizing hormone beta subunit (LHbeta) have been cloned and characterized from the pituitary of grass carp (Ctenopharyngodon idella). The full length of FSHbeta and LHbeta cDNA was 393 bp and 441 bp, with open reading frame encoding proteins of 130 and 146 amino acids, respectively. Phylogenetic analysis of the proteins of FSHbeta and LHbeta showed a high homology with other fishes. Homology analysis also indicated that LHbeta has higher conservation than FSHbeta. The expression analysis of grass carp FSHbeta and LHbeta by RT-PCR suggested that they were only expressed in the pituitary. Real-time quantitative PCR protocols were developed and validated to measure FSHbeta and LHbeta mRNAs during ovarian development. The FSHbeta and LHbeta mRNA level was very low in the pituitaries of early-pubertal fish and significantly increased during the ovulation period. These results suggested that in grass carp the gonadotropins synthesized synchronously in order for asynchronous oogenesis to take place.

Bioaccumulation of five heavy metals (Cd, Cu, Mn, Pb, and Zn) in six plant organs (panicle, leaf, stem, root, rhizome, and bud) of the emergent and perennial plant species, Miscanthus sacchariflorus, were investigated to estimate the plant's potential for accumulating heavy metals in the wetlands of Dongting Lake. We found the highest Cd concentrations in the panicles and leaves; while the highest Cu and Mn were observed in the roots, the highest Pb in the panicles, and the highest Zn in the panicles and buds. In contrast, the lowest Cd concentrations were detected in the stem, roots, and buds; the lowest Cu concentrations in the leaves and stems; the lowest Mn concentrations in the panicles, rhizomes, and buds; the lowest Pb concentrations in the stems; and the lowest Zn concentrations in the leaves, stems, and rhizomes. Mean Cu concentration in the plant showed a positive regression coefficient with plot elevation, soil organic matter content, and soil Cu concentration, whereas it showed a negative regression coefficient with soil moisture and electrolyte leakage. Mean Mn concentration showed positive and negative regression coefficients with soil organic matter and soil moisture, respectively. Mean Pb concentration exhibited positive regression coefficient with plot elevation and soil total P concentration, and Zn concentration showed a positive regression coefficient with soil available P and total P concentrations. However, there was no significant regression coefficient between mean Cd concentration in the plant and the investigated environmental parameters. Stems and roots were the main organs involved in heavy metal accumulation from the environment. The mean quantities of heavy metals accumulated in the plant tissues were 2.2 mg Cd, 86.7 mg Cu, 290.3 mg Mn, 15.9 mg Pb, and 307 mg Zn per square meter. In the Dongting Lake wetlands, 0.7 × 10 kg Cd, 22.9 × 10 kg Cu, 77.5 × 10 kg Mn, 3.1 × 10 kg Pb, and 95.9 × 10 kg Zn per year were accumulated by aboveground organs and removed from the lake through harvesting for paper manufacture.

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