Full life-cycle assessment of gene flow consistent with fitness differences in transgenic and wild-type Japanese medaka fish (Oryzias latipes).

Transgenic fish in development for aquaculture could escape from farms and interbreed with wild relatives in the nearby environment. Predicting whether escapes would result in transgene introgression is a major challenge in assessing environmental risks of transgenic fish. Previous studies have simulated gene flow from transgenic fish using mathematical modeling of fitness traits to predict the relative selective value of transgenic genotypes. Here, we present the first study of gene flow over the full life cycle in openly-breeding populations of transgenic animals, along with measurement of fitness traits. We conducted two invasion experiments in which we released two lines of growth-enhanced transgenic fish (T67 and T400), Japanese medaka (Oryzias latipes), into populations of wild-type (W) medaka in structured mesocosms. After several generations, the frequency of transgenic fish varied across replicates in the first invasion experiment (6 months), but the frequency of transgenic fish decreased in the second experiment (19 months). We also measured selected fitness traits in transgenic and wild-type medaka because these traits could be used to predict the relative selective value of a genotype. We found that: T400 males were more fertile than W males; offspring of W females lived longer than those with transgenic mothers; and W and T67 females reached sexual maturity sooner than T400 females. In contrast with other research that reported larger transgenic males had a mating advantage, we found that W males obtained more matings with females than T males; genetic background effects may account for our differing results as we compared W and T fish derived from different strains. The decreasing frequency of transgenic fish in the second invasion experiment suggests that transgenic fish had a selective disadvantage in the experimental environment. Our finding of transgenic advantage of some fitness traits and wild-type advantage in others is consistent with our invasion experiment results.

A newly constructed and validated isoflavone database for the assessment of total genistein and daidzein intake.

The principal phyto-oestrogens (PO) in food are isoflavones, lignans, coumestans and prenylated flavonoids, with isoflavones and lignans being the most commonly found in UK diets. Until recently obtaining accurate data on the PO content of foods was hampered by lack of suitable analytical methods and validation techniques. Furthermore, although PO data exist for some foods, these foods may not be available in the UK. The aim of the present study was to construct a new, comprehensive isoflavone (total genistein + daidzein) database. Using data, mainly from recent GC-MS analysis, for approximately 300 foods available in the UK, and extensive recipe calculations, a new database was constructed containing approximately 6000 foods allocated an isoflavone value. By analysing 7 d weighed food diaries, the database was subsequently used to estimate isoflavone intake in two groups of healthy volunteers, omnivores (n 9) and vegetarians (n 10). Mean isoflavone intake in the vegetarian and omnivorous group was 7.4 (sem 3.05) and 1.2 (sem 0.43) mg/d, respectively. Mean intake for the total group was 4.5 (sem 1.89) mg/d. Main food sources of isoflavones for the vegetarian group were soya milk (plain), meat-substitute foods containing textured vegetable protein and soya protein isolate, soya mince, wholemeal bread and rolls, white bread and rolls, croissants and pitta breads, beans, raisins and soya sauce. Main food sources of isoflavones for the omnivorous group were soya yogurts, wholemeal bread and rolls, white bread and rolls, garlic bread, nan bread and brown bread, sultanas and scones.

Short-term phytoestrogen supplementation alters insulin-like growth factor profile but not lipid or antioxidant status.

Phytoestrogens are plant compounds that have been proposed to have a variety of health benefits. The aim of this study was to assess the effects of these compounds on a number of physiological endpoints. Subjects were given a single intake of a phytoestrogen-rich (80 mg total phytoestrogens) supplement containing soy, rye and linseed (Phase 1), followed by a week-long intervention using the same supplement (Phase 2) (80 mg total phytoestrogens daily). A number of biochemical endpoints were assessed including urinary phytoestrogen metabolites, lipids, antioxidant status, DNA damage and insulin-like growth factor-1 (IGF-1) and IGF binding protein-1 (IGFBP-1) and -3 (IGFBP-3). Ten healthy female subjects took part in the study. Excretion of the isoflavones genistein, daidzein and equol in urine increased in both phases of the study. No other endpoint was altered in Phase 1. However, in Phase 2, concentrations of IGF-1 and IGFBP-3 were increased by phytoestrogen supplementation [IGF-1, median (IQ range), baseline 155 (123, 258), postweek 265 (228, 360) ng/ml, P<.05; IGFBP-3, baseline 3725 (3631, 4196), postweek 4420 (4192, 4935) ng/ml, P<.05]. There was no effect of supplementation on lipids or markers of antioxidant status. Short-term phytoestrogen supplementation increases urinary phytoestrogen excretion and increases IGF-1 and IGFBP-3. These results require elucidation in further controlled studies.

Plasma and urinary phyto-oestrogens as biomarkers of intake: validation by duplicate diet analysis.

Estimating intake of phyto-oestrogens (PO) is difficult because there is inadequate information on the PO content of foods. Development of a biomarker of intake is therefore necessary for carrying out epidemiological studies. We aimed to validate a newly constructed PO database, containing more than 600 values assigned to foods by using duplicate diet analysis, and to investigate the relationships between measured PO intake, urinary excretion and plasma concentrations of PO. Fourteen subjects with estimated dietary intakes of PO ranging from 0 to 44 mg/d, measured by 7 d weighed intake, completed a duplicate diet collection over 24 h. Concurrently, a 24 h urine collection, validated using p-aminobenzoic acid, was obtained and one timed spot plasma sample taken. Duplicate diets, complete urine collections and plasma samples were analysed for total genistein and daidzein using liquid chromatography-MS to determine PO intake. The potential for 24 h urinary excretion and plasma PO concentrations to reflect dietary intake was investigated. Mean estimated and measured dietary PO intakes were 12.3 and 11.0 mg/d respectively. The correlation between estimated intake and measured intake of PO was highly significant (r 0.98, P<0.001). Urinary excretion (24 h) and plasma concentrations of PO were significantly related to measured dietary PO intake (r 0.97, P<0.001 and r 0.92, P<0.001 respectively). The relationship between 24 h urinary PO excretion and timed plasma concentrations was also significant (r 0.99, P<0.001). These findings validate the PO database and indicate that 24 h urinary excretion and timed plasma concentrations can be used as biomarkers of PO intake.

Phytoestrogen concentrations in serum from Japanese men and women over forty years of age.

Asian individuals have much lower incidences of prostate and breast cancer than populations from Western developed countries. They also consume a lower fat, higher fiber diet, with a large intake of phytoestrogens. These phytoestrogens may protect against hormone-dependent cancers and other diseases. Our study used established gas chromatography-mass spectrometry (GC-MS) methodologies to measure the concentrations of four phytoestrogens (daidzein, genistein, equol and enterolactone) in serum samples obtained from Japanese men (n = 102) and women (n = 125) > 40 y old. The results were compared with those obtained with samples from the UK. The Japanese men and women had higher (P < 0.001) concentrations of circulating daidzein, genistein and equol than individuals from the UK. The mean concentration of genistein in Japanese men, for example, was 492.7 nmol/L, compared with 33.2 nmol/L in men from the UK. The two populations, however, had similar serum concentrations of enterolactone. Furthermore, 58% of the Japanese men and 38% of the Japanese women had equol concentrations > 20 nmol/L, compared with none of the UK men and 2.2% of the UK women. These results support previously published GC-MS results from studies with low numbers of samples.