Superovulatory response to a low dose single-daily treatment of rhFSH dissolved in polyvinylpyrrolidone in rhesus monkeys

To simplify the procedure for superovulation in the rhesus monkey, this study was designed using polyvinylpyrrolidone (PVP) solution as a solvent for gonadotropins. Thirty-five cycling females (aged 5-8 years old) were divided into six groups during the b

Forecasting Daily Chlorophyll a Concentration during the Spring Phytoplankton Bloom Period in Xiangxi Bay of the Three-Gorges Reservoir by Means of a Recurrent Artificial Neural Network

A recurrent artificial neural network was used for 0-and 7-days-ahead forecasting of daily spring phytoplankton bloom dynamics in Xiangxi Bay of Three-Gorges Reservoir with meteorological, hydrological, and limnological parameters as input variables. Daily data from the depth of 0.5 m was used to train the model, and data from the depth of 2.0 m was used to validate the calibrated model. The trained model achieved reasonable accuracy in predicting the daily dynamics of chlorophyll a both in 0-and 7-days-ahead forecasting. In 0-day-ahead forecasting, the R-2 values of observed and predicted data were 0.85 for training and 0.89 for validating. In 7-days-ahead forecasting, the R-2 values of training and validating were 0.68 and 0.66, respectively. Sensitivity analysis indicated that most ecological relationships between chlorophyll a and input environmental variables in 0-and 7-days-ahead models were reasonable. In the 0-day model, Secchi depth, water temperature, and dissolved silicate were the most important factors influencing the daily dynamics of chlorophyll a. And in 7-days-ahead predicting model, chlorophyll a was sensitive to most environmental variables except water level, DO, and NH3N.

Daily timing of emersion and elevated atmospheric CO2 concentration affect photosynthetic performance of the intertidal macroalga Ulva lactuca (Chlorophyta) in sunlight

The lunar day differs in length from the solar day so that times of low tide vary from day to day. Thus, aerial exposure of intertidal seaweeds may be during the day or during the night. We measured photosynthetic CO, assimilation rates of the intertidal green macroalga Ulva lactuca during exposures of varied daily timings during sunny days of summer to establish how photosynthetic performance responds to emersion timing under varied CO2 levels [at ambient (360 ppmv) and 2x ambient (720 ppmv) atmospheric CO2 concentrations]. There was an increase in net photosynthetic rates following some duration of exposure when the initial timing of exposure occurred during early morning (06.30 h) and late afternoon (17.15 h). In contrast, net rates exhibited a sharp decline with exposure duration when the initial timing of exposure occurred at 09.30 h, 15.30 h and especially at noon (12.30 h), implying the occurrence of a severe photoinhibition resulting from mid-day insolation. Doubled atmospheric CO2 concentration significantly enhanced the emersed photosynthetic rates, indicating that the emersed photosynthesis is CO2-limited at ambient CO2 levels. However, increasing CO2 barely stimulates the emersed photosynthetic rates during mid-day insolation.

Daily dynamics of nutrients and chlorophyll a during a spring phytoplankton bloom in Xiangxi Bay of the Three Gorges Reservoir

We studied the daily dynamics of nutrients (total phosphorus [TP], total nitrogen [TN], and dissolved silicate [SiO2]) and chlorophyll a (chl a) during a spring bloom in Xiangxi Bay of the Three Gorges Reservoir in year 2005. According to the daily dynamics of chl a, the bloom occurred in two stages (23 February-25 March and 26 March-28 April). The concentration of SiO2 decreased at different layers of the water column with the development of the bloom. However, the decrease of SiO2 in the layers with high concentration of chl a was more dramatic than in the layers with low concentration of chl a. The concentration of TP was lowest value a few days after the peak of chl a during the first bloom period, and the lowest value of TN was found a few days after the peak of chl a during the second bloom period. Correlative analyses indicated that SiO2 and TP were limiting factors in the first bloom period, and SiO2 and TN were limiting factors in the second bloom period.

Characterization of diurnal photosynthetic rhythms in the marine diatom Skeletonema costatum grown in synchronous culture under ambient and elevated CO2

Photosynthetic performance was examined in Skeletonema costatum (Greville) Cleve. under 12: 12-h light: dark (LD) cycle at ambient CO2 (350 muL L-1) and elevated CO2 (1000 muL L-1). At ambient CO2, the cellular chlorophyll a content, the light-saturated photosynthetic rate (P-m), the initial slope of the light saturation curves ( a), the photochemical efficiency of PSII (F-v/F-m), the apparent carboxylating efficiency (ACE) and the photosynthetic affinity for CO2 [1/K-m (CO2)] all showed rhythmical changes with different amplitudes during the light period. The P-m had similar changing pattern in the light period with the ACE and 1/K-m (CO2) rather than with the alpha and F-v/F-m, indicating that rhythmical changes of photosynthetic capacity may be mainly controlled by the activity of C- reduction associated with CO2 uptake during the light period. The CO2 enrichment reduced the ACE and the affinity to CO2, and increased the a, cellular chlorophyll a content and P m based on cell number. By contrast, the changing patterns of all photosynthetic parameters examined here during the light period had almost the same for cells grown at ambient CO2 and elevated CO2, suggesting that the photosynthetic rhythms of S. costatum are not affected by CO2 enrichment.

Daily production and photosynthetic characteristics of Nostoc flagelliforme grown under ambient and elevated CO2 conditions

Diurnal photosynthesis of Nostoc flagelliforme was investigated at varied levels of CO2 concentrations and desiccation in order to estimate the effects of enriched CO2 and watering on its daily production. Photosynthetic activity was closely correlated with the desiccated status of the algal mats, increased immediately after watering, reached a maximum at moderate water loss, and then declined with further desiccation. Increased CO2 concentration enhanced the diurnal photosynthesis and raised the daily production. Watering twice per day enhanced the daily production due to prolonged period of active photosynthesis. The values of daily net production were 1321280 mumol CO2 g (d. wt)(-1) d(-1), corresponding to about 0.6-6.1% daily increase in dry weight. High-CO2-grown mats required higher levels of photon flux density to saturate the alga's photosynthesis in air. Air-grown mats showed higher photosynthetic affinity for CO2 and higher levels of dark respiration compared with high-CO2-grown samples.

Calculation of the hourly and daily radiation incident on three step tracking planes

Mathematical formulas for estimating the hourly and daily radiation incident on planes of azimuth three step tracking and hour angle three step tracking have been derived in this paper. Based on the hourly solar radiation data of an average day in each month at Er-Lian-Hao-Te city, the hourly and monthly radiation received by planes of these two kinds of tracking have been calculated. The results show that in this district, one axis azimuth three step tracking and hour angle three step tracking could, respectively, obtain 66.5% and 63.3% higher radiation than that on the horizontal surface all year. Moreover, a two axis azimuth three step tracking plane could receive 72% more radiation than the horizontal surface. (C) 2002 Elsevier Science Ltd. All rights reserved.

Circadian rhythms in the growth and reproduction of the brown alga Undaria pinnatifida and gametogenesis under different photoperiods

Circadian growth rhythm of the juvenile sporophyte of the brown alga Undaria pirznatifida was measured with the computer-aided image analysis system in constant florescent white light under constant temperature (10 degrees C). The growth rhythm persisted for 4 d in constant light with a free-running period of 25. 6 h. Egg release from filamentous gametophytes pre-cultured in the light - dark regime was evaluated for six consecutive days at fixed time intervals in constant white light and 12 h light per day. Egg release rhythm persisted for 3 d in both regimes, indicating the endogenous nature. Temporal scale of egg release and gametogenesis in 18, 16, 12 and 8 h light per day were evaluated respectively using vegetatively propagated filamentous gametophytes. Egg release occurred 2 h after the onset of dark phase and peaked at midnight. Evaluation of the rates of oogonium formation, egg release or fertilization revealed no significant differences in four light-dark regimes, indicating; the great plasticity of sexual reproduction. No photoperiodic effect in gametogenesis in terms of oogonium formation and egg release was found, but fertilization in short days was significantly higher than in long days. Results of this investigation further confirmed the general occurrence of circadian rhythms in inter-tidal seaweed species.

Feeding activities of zooplankton in the Bohai Sea

The Bohai Sea was the site of the Chinese national GLOBEC programme. During the June 1997 cruises of R/V Science No.1, observations and experiments on zooplankton feeding were conducted. At five 48 h time-series stations the following observations and measurements on zooplankton were carried out: (1) diurnal vertical migration, by collecting samples at different layers every 3 h with a closing net; (2) diurnal feeding rhythms, by gut pigment analysis; and (3) ingestion rate, by both gut pigment analysis and the dilution method. A classification by body size was used to deal with the diversity of species and developmental stages of zooplankton assemblages. Samples were separated into three size groups: small (200-500 mu m), medium (500-1000 mu m) and large (> 1000 mu m). The results showed that the copepods (Calanus sinicus, Paracalanus parvus, Acartia bifilosa and Centropages mcmurrichi) performed clear diurnal vertical migrations. However, their behaviour was different at different stations. The variation in gut pigment content over the 24 h cycle showed strong diurnal feeding rhythms, particularly for the large size group. Gut pigment contents reached their daily maximum during the time from dusk to midnight (18:00-24:00). The peak value was about 10 times the minimum observed in the daytime. The in situ daily grazing rate, based on gut pigment contents and evacuation experiments, was 4.00-12.65 ng chla ind(-1) day(-1) for the small size group, 5.99-66.58 ng chla ind(-1) day(-1) for the medium size group and 31.31-237.13 ng chla ind(-1) day(-1) for the large size group. The copepods consumed only a small part (2.90-13.52%) of the phytoplankton biomass hut about 77% of the daily production. The grazing mortality rate of phytoplankton by microzooplankton (<200 mu m) measured by the dilution method ranged from 0.43 to 0.69 day(-1) The calculated daily consumption of phytoplankton biomass was 35-50%, and 85-319% of the potential production.