Rong‐Ching Wu

A method is described in which DNA or RNA is delivered into plant cells using small tungsten particles (microprojectiles; 4 µm diameter) at high velocity. After acceleration, the particles pierce the cell walls and membranes and enter the intact cells without killing them. Using this method, 1 cm² sections of Allium cepa epidermis were bombarded with tungsten particles coated with plasmid p35S-CAT, containing a gene that encodes chloramphenicol acetyltransferase (CAT). Extracts subsequently obtained from the tissue revealed expression of the gene, in the form of very high levels of CAT activity; controls showed negligible activity. It is suggested that the method can be used to study the transient expression of foreign genes in intact tissue and can possibly provide a broadly applicable means of transformation capable of circumventing the host range restrictions of Agrobacterium tumefaciens and the regeneration problems associated with protoplasts

A rice (Oryza sativa) seed plasma-membrane calcium-dependent serine/threonine protein kinase (CDPK) has been partially purified. Comparing results in seeds that were treated with and without the plant hormone gibberellin (GA) for 10 min showed that rice CDPK was highly induced by GA. After separating solubilized membrane proteins by sodium dodecyl sulfate-gel electrophoresis, followed by renaturation, a radiolabeled phosphoprotein band of approximately 58 kD was detected, and it was apparently produced by autophosphorylation. There are five aspects of the rice CDPK that show similarity to mammalian protein kinase C (PKC) and to other plant CDPKs: (a) Histone IIIS and PKC peptide-ser25 (19-31) are phosphorylated by rice CDPK. (b) The phosphorylation reaction is strictly dependent on calcium. (c) The activity of the rice CDPK is inhibited by either staurosporine or the PKC inhibitory peptide (19-36). (d) Addition of calmodulin has no effect on the activity of the enzyme; however, the CDPK is inhibited by the calmodulin antagonists trifluoperazine and W-7. (e) The rice CDPK reacts with a mammalian anti-PKC antibody in immunoblotting analysis. However, there is one major difference between the rice CDPK and other CDPKs: the rice CDPK is induced by GA, whereas no mammalian PKC or other plant CDPKs are known to be induced by any hormone.

This paper proposes the use of a steady-state model to identify the parameters of an induction motor. A time-varying impedance can be found with the time-varying voltages and currents under a starting no-load low-voltage test, where time-varying slip rates were also recorded. With a proper conversion, the variations of impedance versus slip rates could be acquired as sampled data for identification, and both electrical and mechanical parameters can be found. A least mean square (LMS) method was used with a particle swarm optimization method to solve the aforementioned problem. The method to find a good set of initial values for LMS is also described in this paper. Many tests were conducted to simulate the starting phases of an induction machine to compare with the existing data. From various tests, the practicability and accuracy of this method can be proven.

In this paper, exponential signals in the frequency domain are accurately analyzed by an algorithm, and the peaks of the discrete Fourier transform (DFT) result are adopted to obtain parameters that include amplitudes, frequencies, dampings, and phases. There are two steps for this algorithm: interpolated DFT and leakage elimination. Interpolated DFT refers to the three neighboring spectral lines at the peak of each mode used to calculate an approximate result, with the purpose of leakage elimination being to eliminate the influence of leakage on these data. After some iteration, this algorithm will obtain accurate parameters of the exponential components that are derived from their DFT results. The comparison of different algorithms is also discussed in this paper.