Liquid chromatographic separation and gas chromatographic—mass spectrometric determination of 17α-methyltestosterone residues extracted from rainbow trout tissues

Current and future assisted reproductive technologies for fish species

The Food and Agriculture Organization of the United Nations (FAO) estimates that in 2012 aquaculture production of fish will meet or exceed that of the capture fisheries for the first time. Thus, we have just turned the corner from a predominantly hunting gathering approach to meeting our nutritional needs from fish, to a farming approach. In 2012, 327 finfish species and five hybrids were covered by FAO aquaculture statistics, although farming of carps, tilapias, salmonids, and catfishes account for most of food-fish production from aquaculture. Although for most major species at least part of production is based on what might be considered domesticated animals, only limited production in most species is based on farming of improved lines of fish or is fully independent of wild seedstock. Consistent with the infancy of most aquaculture industries, much of the development and implementation of reproductive technologies over the past 100 years has been directed at completion of the life cycle in captivity in order to increase seed production and begin the process of domestication. The selection of species to farm and the emphasis of selective breeding must also take into account other ways to modify performance of an animal. Reproductive technologies have also been developed and implemented to affect many performance traits among fishes. Examples include technologies to control gender, alter time of sexual maturation, and induce sterilization. These technologies help take advantage of sexually dimorphic growth, overcome problems with growth performance and flesh quality associated with sexual maturation, and genetic containment. Reproductive technologies developed to advance aquaculture and how these technologies have been implemented to advance various sectors of the aquaculture industry are discussed. Finally, we will present some thoughts regarding future directions for reproductive technologies and their applications in finfish aquaculture.

Optimization and validation of conventional and micellar LC methods for the analysis of methyltestosterone in sugar-coated pills

Two isocratic liquid chromatographic methods (conventional and micellar) for the determination of methyltestosterone in sugar-coated pills using fluoxymesterone as internal standard have been developed and validated. In conventional liquid chromatography a mobile phase 45% water:acetonitrile 55% (v:v), a flow-rate 1 mlmin(-1) and a C(18) Hypersil ODS (250 x 4.6 mm, 5 microm) column (25 degrees C) were used. In micellar liquid chromatography the conditions were: mobile phase 40 mM sodium dodecyl sulfate: 10% propanol, flow-rate 0.5 mlmin(-1) and C(18) Hypersil ODS (150 x 3.0 mm, 5 microm) column (60 degrees C). For both methods, UV absorbance detection at 245 nm was used and a separation up to base line was achieved. Prior to HPLC analysis a simple sample preparation was required.

Biosynthesis of 6beta-hydroxymethyltestosterone using bovine hepatocyte cultures

Usually performed to investigate biotransformations of xenobiotics, in vitro liver models could become useful tools for the synthesis of not commercially available compounds. In this study, bovine hepatocyte cultures were used to biosynthesise, on the laboratory scale, one major metabolite of methyltestosterone: 6beta-hydroxymethyltestosterone. After incubation of bovine hepatocytes with methyltestosterone for 24 h, culture medium was removed and stored at -20 degrees C until analysis. The sample was extracted and purified on a reversed-phase HPLC system. The metabolite of interest was then analysed in LC-MS and GC-MS for structural identification. The purity and the isomery of the 6 and 17 positions were confirmed by NMR analyses. This first success in producing purified 6beta-hydroxymethyltestosterone from bovine hepatocyte cultures allowed us to consider that in vitro liver models could be reliable tools for standard biosynthesis.

Influence of growth hormone on the hepatic mixed function oxidase and transferase systems of rainbow trout

The effect of GH treatment on hepatic cytochrome P450 content, aryl hydrocarbon hydroxylase (AHH), aminopyrine-N-demethylase (AND), testosterone hydroxylase, testosterone 5α- and 5β-reductase, UDP-glucuronyl transferase (UDPGT) and glutathione S-transferase (GST) activities in immature rainbow trout were investigated. Hepatic cytochrome P450 content, AHH and GST activities were measured in both GH implanted and GH injected animals whereas other activities were assayed in GH implanted trout only.GH implants significantly decreased cytochrome P450 content at 15 days compared to the control but no significant effect was observed at 15 or 30 d when GH was injected biweekly. In both cases, AHH activity was significantly decreased by GH treatment compared to the control whereas GST remained unchanged. Compared to the control, GH implanted fish exhibited a pronounced inhibition of AND, a decreased 6β and 16β-testosterone hydroxylation, an inhibition of UDPGT with testosterone as substrate and an enhanced 17β-testosterone oxidation.