Transient expression of lacZ in particle bombarded Gracilaria changii (Gracilariales, Rhodophyta)

Using a Biolistic PDS 1000/He system, healthy thalli of Gracilaria changii were bombarded with gold particles coated with plasmid DNA containing the lacZ reporter gene. Transient expression of lacZ was observed in bombarded thalli under the rupture-disc pressures of 4482, 6206, 7584 and 8963 KPa, two days after bombardment. Although G. changii exhibits a slight blue background, positive expression and the background colour can be clearly differentiated. The results indicate that lacZ could be a useful reporter gene and that SV40 promoter could be an effective promoter for Gracilaria transformation.

Transient expression of lacZ in bombarded unicellular green alga Haematococcus pluvialis

This paper reports for the first time the transient expression of a reporter gene, LacZ, in the unicellular green alga Haematococcus pluvialis. By employing the micro-particle bombardment method, motile cells in the exponential phase showed transient expression of lacZ. This was detected in bombarded motile cells under the rupture-disc pressures of 3103 KPa and 4137 KPa. Transient expression of LacZ gene could not be observed in non-motile cells of this alga under the same transformation condition. No LacZ background was found in either the motile cells or the non-motile cells. The study suggests a promising potential of the SV40 promoter and the lacZ reporter gene in genetic engineering of unicellular green algae.

Three-stage transformation of chlorophyll transient fluorescence pattern under sustained dehydration and the discovery of critical water content in seaweeds

The chlorophyll fluorescence kinetics of marine red alga Grateloupia turutunt Yamada, green alga Ulva pertusa Kjellm and brown alga Laminaria japonica Aresch during natural sustained dehydration were monitored and investigated. The pulse amplified modulation (PAM) system was used to analyze the distinct fluorescence parameters during thallus dehydration. Results proved that the fluorescence kinetics of different seaweed all showed three patterns of transformation with sustained water loss. These were: 1) peak kinetic pattern (at the early stage of dehydration fluorescence enhanced and quenched subsequently, representing a normal physiological state). 2) plateau kinetic pattern (with sustained water loss fluorescence enhanced continuously but quenching became slower, finally reaching its maximum). 3) Platform kinetic pattern (fluorescence fell and the shape of kinetic curve was similar to plateau kinetic pattern). A critical water content (CWC) could be found and defined as the percentage of water content just prior to the fluorescence drop and to be a significant physiological index for evaluation of plant drought tolerance. Once thallus water content became lower than this value the normal peak pattern can not be recovered even through rehydration, indicating an irreversible damage to the thylakoid membrane. The CWC value corresponding to different marine species were varied and negatively correlated with their desiccation tolerance, for example. Laminaria japonica had the highest CWC value (around 90%) and the lowest dehydration tolerance of the three. In addition, a fluorescence "burst" was found only in red algae during rehydration. The different fluorescence parameters F-o, F-v and F-v, F-m were measured and compared during water loss. Both F-o and F-v increased in the first stage of dehydration but F-v/F-m. kept almost constant. So the immediate response of in vivo chlorophyll fluorescence to dehydration was an enhancement. Later with sustained dehydration F-o increased continuously while F-v decreased and tended to become smaller and smaller. The major changes in fluorescence (including fluorescence drop during dehydration and the burst during rehydration) were all attributed to the change in F-o instead of F-v This significance of F-o indicates that it is necessary to do more research on F-o as well as on its relationship with the state of thylakoid membrane.

中低纬度变化磁场的暴时特征研究

Magnetic storm is a kind of severe disturbances in the whole solar-earth electromagnetic space. It has significant effects on communication, electric power, oil transport pipe and human activities in space. Therefore, magnetic storms are worth for applications systems, not only being a favorable issue for scientists. In this paper, the spatial and temporal distributions of the magnetic fields produced by the magnetosphere-ionosphere current systems during storms are studied. Four parts are included in this paper decomposion of different disturbances with different origins, topological structure of the ring current, the asymmetric characteristics of the ring current, and the statistic peculiarities of the day-to-day variability (DTD) of Sq. 1 The decomposition of magnetic disturbances at mid-low latitudes and its evolutions during storms Transient variations in the geomagnetic field recorded at mid-low latitudes mainly include the storm-time variation (Dst), solar quiet daily variation (Sq) and disturbance daily variation (SD). With the data of the geomagnetic meridian chain observatories in China, 25 storms during the period of 1997 to 1999 have been analyzed. According to the features of different variations, a method of “three-steps decomposition” is developed by using the method of Natural Orthogonal Components (NOC), Correlation Analysis and Fourier Analysis to separate those three components in turn. The results show that, the first eigenmode by the MNOC clearly describing the special distribution and temporal evolution of storm-time variation, in addition, Correlation Analysis and Fourier Analysis offer a useful method to extract the Sq and SD variations. The latitudinal shift of the Sq current focus seems to be the principal reason of the day-to-day variaitons in the daily range of Sq. The magnitude of SD reaches a maximum during the main phase, and then gradually decreases. 2 The topology structure of the ring current during storms Both the mechanism of the ring current and the geomagnetic data suggest that the central plane of the ring current is declining to the geomagnetic equator plane with a tilt angle δ. Using the H and Z component data at two stations in a meridian chain, we deduce a new parameter describing the invariable peculiarity of different storms. Then the δ angle is calculated by using the data from a meridian chain and tested with the ERC model. Finally the deduced tilt angles are used to modify Dst index. 3 The asymmetric characteristics of the ring current during storms The variations of the geomagnetic field at mid-low latitudes show a significant dawn-dusk asymmetry, resulting from the superposition of the fields from the symmetric ring current and the partial ring current. On the basis of the data from the 20°E, 30°E meridian chains and 30°N latitudinal chain, the dawn-dusk asymmetry is investigated by using three methods, namely, statistic analysis, ring current model calculation and typical event analysis. This characteristic implies the asymmetry of the spatial distribution of the ring current. In addition, during the main phase after the sudden commencement (SC), H field increases and reaches maximum around noontime, implying the effect of the Chapman-Ferraro current. 4 The statistic characteristics of the day-to-day variability and its mechanism The day-to-day variability of the geomagnetic Sq field is studied by using the magnetic data from a meridian chain of magnetometers along 120° E longitude. The method of NOC is applied to separate the Sq variation from complicated disturbances. The first eigenmode with the largest eigenvalue represents fairly well the Sq variation with a conspicuous day-to-day variability in the daily range. For the stations on the same north- or south-side of the Sq current system focus, the day-to-day variations show a positive correlation. In contrast, for the stations on the different sides of the Sq focus, they show a negative correlation, suggesting an important role of latitudinal shift of the Sq current system focus to the day-to-day variability of the Sq daily range. The Sq daily range is correlated with the magnetic indices Ap and Dst in a peculiar way: on some severe disturbed days, noticeably enhancements of the Sq are observed, implying increases of the ionospheric conductivities and/or tidal wind velocities; on other severe disturbed days, however, dramatically reduced Sq variations occur, suggesting dominant effects of the ‘disturbance dynamo’ process.

Pump-dump control and the related transient absorption spectroscopies

We combine theories of optimal pump-dump control and the related transient probe absorption spectroscopy in order to elucidate the relation between these two optical processes and the possibility of experimental realization. In the weak response regime, we identify the globally optimal pair of pump-dump control fields, and further propose a second-order difference detection scheme to monitor the wave packets dynamics that is jointly controlled by both the pump and dump fields. The globally optimal solution serves also as the initial input for the iterative search for the optimal control fields in the strong response regime. We use a model I-2 molecule to demonstrate numerically the pump-dump control and the detection of a highly vibrationally excited wave packet focusing dynamics on the ground X surface in both the weak and strong response regimes. The I2B surface serves as the intermediate to assist the pump-dump control and the optical detection processes. Demonstrated in the strong response regime are the optimal pair of pump-dump molecular-pi pulses that invert nearly total population onto the predefined target region within a half period of vibration motion. (C) 1999 American Institute of Physics. [S0021-9606(99)00115-4].