The larval endoparasitoid, Neochrysocharis formosa (Westwood), is an important natural enemy of the leafminer Liriomyza trifolii (Burgess) in Japan. The thelytokous strain of N. formosa mostly produces female progeny. Male progeny were produced by females treated with tetracycline, suggesting that microorganisms induce thelytoky in N. formosa. The result of nucleotide sequencing of the 16S rRNA gene indicated that the parasitoid is infected with a Rickettsia bacterium, which appears to be causative of the thelytoky. Although Rickettsia-bellii-like bacteria have been found to be associated with various reproductive disorders, this is the first finding of a parthenogenesis-inducing Rickettsia among insects.

In this work, an optimization algorithm was proposed for plasma diagnostic modeling based on a statistical analysis of reduced population density distribution. The algorithm generates a diagnostic equation, whose input parameters are the radiant flux of the multi-optical emission lines, and output parameters are electron temperature T e, electron density N e, and electron energy distribution function (EEDF), based on the dependence of reduced population density onT e, N e, and EEDF. The argon collisional-radiative model and the generalized EEDF were applied for the analysis of the excitation-kinetics. In this study, the diagnostic error for the low-pressure inductively coupled plasma, the low-pressure microwave discharge surface wave plasma, and the atmospheric dielectric barrier discharge plasma were simulated. The simulated diagnostic errors were smaller than those of the previously reported model.

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Vacuolar collapse plays a direct role in the cell death of the interspecific hybrid of Nicotiana gossei Domin xN. tabacum L. which exhibits hybrid lethality at the seedling stage. We have previously reported that cell death in these seedlings began at the base of hypocotyls and spread throughout the plant (Mino et al. 2002). A light microscopic analysis revealed that the process involved disruption of the intra-cellular membranes, plasmolysis, and retraction of the wall of the cell in hypocotyls. A transmission electron microscopic analysis showed that there were several abnormal structures, i.e. knob-like bodies on the tonoplast and small vesicles in the cytoplasm, and the disintegration of the tonoplast, in the cells of seedlings grown at 26 degrees C. However, no such cytological defects were observed in the seedlings grown at 37 degrees C, at which temperature the expression of lethality was suppressed. The activity levels of vacuolar processing enzyme (VPE), which might be involved in the vacuolar collapse of plant cells, temporarily increased in the seedlings grown at 26 degrees C before apparent cell death proceeded, but it remained unchanged in the seedlings grown at 37 degrees C. Applications of acetyl-L: -tyrosyl-L: -valyl-L: -alanyl-L: -aspart-1-aldehyde, an inhibitor for VPE, and cycloheximide to the seedlings suppressed VPE's activities, the formation of knob-like bodies on the tonoplast, and cell death. VPE might be involved in the structural anomalies on the tonoplast which lead to cell death triggered by vacuolar collapse in hybrid seedlings.

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