Influence of LAS on marine calanoid copepod population dynamics and potential reproduction.

The toxicity of linear alkyl benzene sulfonate (LAS) to marine invertebrates is well documented under laboratory conditions using single-species tests. It is less known how LAS affects natural populations of aquatic organisms. We hypothesised that LAS was more toxic to the calanoid copepod Acartia sp. under natural conditions than Acartia tonsa under cultured conditions in the laboratory. This hypothesis was checked by a direct comparison of LAS toxicity in single-species and model (mesocosm) studies. The acute and sublethal effects of LAS on the survival and egg production of laboratory reared A. tonsa were examined by standard test, i.e. incubation with LAS without food for 24-72 h. The LC(50) and EC(50) values averaged 1.23 and 0.74 mg l(-1) for survival and egg production, respectively. These values are comparable to previous reports. The effects of LAS on a natural copepod community were also investigated under in situ conditions. A series of seven mesocosms (holding approx. 3 m(3) of seawater each) was established with two mesocosms being controls without LAS and five mesocosms with increasing concentrations of LAS ranging from 0.1 to 6.5 mg l(-1) applied as a single dose. The indigenous copepod community, dominated by Acartia sp. and Centropages sp., responded clearly to LAS concentrations above 0.1 mg l(-1). The calculated no effect value was 0.14 mg LAS l(-1) (95% CI=0.08-1.82 mg LAS l(-1)) for the entire copepod community including all development stages after 24 h exposure. The increased sensitivity under in situ conditions was probably promoted by the suboptimal growth conditions, e.g. no saturated food concentration or inadequate nutritive values of the food. The amount of food expressed as chlorophyll concentration was low (around 2 microg chl. a l(-1)) but was not affected by LAS. It appeared that the naupliar stages of Acartia and Centropages were the least affected by LAS and that new cohorts were able to develop 15 days after the dosing with LAS.

Inhibin B predicts oocyte number and the ratio IGF-I/IGFBP-1 may indicate oocyte quality during ovarian hyperstimulation for in vitro fertilization.

PURPOSE: To perform a retrospective analysis of 62 age-matched IVF-treated women in order to investigate whether levels of inhibin B, IGF-I, and IGFBP-1 in serum 2 days before oocyte retrieval and in follicular fluid at the day of oocyte retrieval might be useful as indicators of the ovarian ability to produce oocytes (ovarian reserve). METHODS: Patients were allocated into three groups on the basis of the number of oocytes retrieved. Group 1 ("low responders") had 0-3 oocytes, group 2 ("normal responders") had 6-11 oocytes, and group 3 ("high responders") had 12 oocytes or more. Levels of inhibin B, IGF-I, and IGFBP-1 in follicular fluid and in serum obtained 2 days before oocyte retrieval were analyzed and correlated to clinical parameters including estradiol levels, progesterone levels, follicle size, follicle number, and oocyte number. RESULTS: We found significant differences in inhibin B levels in the three groups. Inhibin B levels in follicular fluid and serum was strongly correlated to the number of oocytes retrieved (p < 0.01). The number of oocytes retrieved were also correlated to total FSH dose (p < 0.05), to estradiol 2 days before and at ovum pick-up (p < 0.05), to progesterone at ovum pick-up (p < 0.0001), to progesterone at embryo transfer (p < 0.05), and to the number of follicles (size 12-15 mm, p < 0.001, size > 15 mm, p < 0.01). Serum inhibin B also correlated to follicular fluid inhibin B (p < 0.01). Inhibin B was not correlated to pregnancy. In contrast, the ratio IGF-I/IGFBP-1 in serum as well as in follicular fluid was significantly higher in women who became pregnant (p < 0.05). CONCLUSIONS: The results show that inhibin B in serum 2 days before oocyte retrieval predicts number of oocytes retrieved. Since inhibin B in serum before oocyte retrieval in ovarian hyperstimulation was strongly predictive of the number of oocytes retrieved, it appears useful as a marker for ovarian response. Inhibin B did not predict treatment outcome, whereas the ratio IGF-I/IGFBP-1 in serum and follicular fluid was significantly higher in women who became pregnant. The ratio IGF-I/IGFBP-1 may thus reflect oocyte quality.