Control of reproduction rhythmicity by environmental and endogenous signals in Ulva pseudocurvata (Chlorophyta)

A field population of Ulva pseudocurvata Koeman et C. Hoek (hereafter termed Ulva) at Sylt Island (North Sea, Germany) exhibited biweekly peaks of gametophytic reproduction during the colder seasons and approximately weekly peaks during summer. The reproductive events lasted 1-5 d and were separated from each other by purely vegetative phases. Under constant conditions in the laboratory, a free-running rhythm was observed with reproductive peaks occurring approximately every 7 d. When artificial moonlight was provided every 4 weeks, fewer reproductive events occurred, and the reproductive rhythm became synchronized to the environmental artificial moonlight rhythm. In the laboratory, apical disks were entirely converted into reproductive tissue after 8 d cultivation, while almost all basal disks stayed vegetative, which prevented the entire loss of the vegetative thallus during reproductive events. Seasonal size reduction of the thallus occurred from late autumn onward and was determined to be controlled by a genuine photoperiodic response, since size reduction could be induced from May onward by experimental short-day (SD) treatment but was prevented in a long-day (LD) or night-break regime (NB). A daily fine-tuning occurred with gamete release early in the morning at the first sign of daylight, following an obligatory dark ("night") period of at least 1 h duration. No release took place if the overnight dark phase was replaced by continuous light. Blue, green, or red light all triggered gamete release after a dark phase at an irradiance of 0.1 mu mol photons . m(-2) .s(-1), while 0.001 mu mol photons . m(-2) . s(-1) was equivalent to a dark control.

Development and application of a sol-gel immunosorbent-based method for the determination of isoproturon in surface water

An immunosorbent was fabricated by encapsulation Of monoclonal anti-isoproturon antibodies in sol-gel matrix. The immunosorbent-based loading, rinsing and eluting processes were optimized. Based on these optimizations, the sol-gel immunosorbent (SG-IS) selectively extracted isoproturon from an artificial mixture of 68 pesticides. In addition to this high selectivity, the SG-IS proved to be reusable. The SG-IS was combined with liquid chromatography-tandem mass spectrometry (LC-MS-MS) to determine isoproturon in surface water, and the linear range was up to 2.2 mu g/l with correlation coefficient higher than 0.99 and relative standard deviation (RSD) lower than 5% (n = 8). The limit of quantitation (LOQ) for 25-ml surface water sample was 5 ng/l. (c) 2006 Elsevier B.V. All rights reserved.