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One or more proteinaceous factors with insecticidal activities in the locust pathogen Serratia marcescens HR-3 culture filtrates were found to cause the death of grassland locusts. A novel insecticidal protein was purified to homogeneity. It was a monomer of 61 kDa. The purified protein showed a strong insecticidal effect with a median lethal dosage of 12.1 microg locust(-1) and contained a high level of protease activity (101 U ml(-1)). Insecticidal activity was significantly decreased when the protein was pretreated with ethylene diamine tetraacetic acid and 1-10-phenanthroline, and it was restored when the treated protein was incubated with Zn(2+). The N-terminal amino acid sequence of insecticidal protein showed sequence similarity with metalloprotease from S. marcescens SM6 and Serratia spp. E15. Our results suggested that the factor primarily responsible for insecticidal activity toward locusts was a zinc-dependent 61-kDa metalloprotease.

Porous silicon samples were prepared for optical studies by using the photoluminescence (PL), Raman scattering (RS), as well as the absolute reflectance and ellipsometry methods. Results show that the porous Si has low optic constants, and can trap the visible photons of more than 95%, but give no evidence of a strong interband transition existing in the visible region. The Bruggeman effective-medium-approximation (EMA) and Lorentz oscillator models were used in data analyses. Calculations show that the layer dispersion effect may result in a red shift of the PL peak. The possible mechanism for the PL and Raman enhancement as well as the photon trap phenomenon was discussed, and was attributed mainly to the random multiple micro-reflections in the porous-Si layer having extremely large internal micro-surfaces.

It is demonstrated in this paper that the infrared-up-conversion luminescence generation from porous silicon, considered as an enhanced third-order nonlinear optical effect by the recent work, is anisotropic as the polarization vector of normally incident fundamental light is rotated. A new method has been used to determine the anisotropy parameter σ of the third-order nonlinear optical tensor χ(3). Due to the sensitivity of σ to the crystal structure and microscopic electronic properties, the difference in σ's between porous and crystalline silicon, particularly in their phases, demonstrates that the nanometer structure of porous silicon induces a dramatic change of the electronic band structure, but the strongly anisotropic crystal property remains unchanged.

AIM: To investigate the effect of detachment of esophageal cancer cells from extracellular matrix on the localization of death receptor 5 (DR5) and apoptosis. METHODS: Anchorage-dependent EC9706 cells of esophageal squamous cell carcinoma were pretreated or not treated with brefeldin A. Detached cells were harvested by ethylenediaminetetraacetic acid digestion. Expression and localization of DR5 in these cells were determined by immunocytochemical and immunofluorescence assays, as well as flow cytometry analysis. Apoptosis of EC9706 cells was detected by flow cytometry after stained with fluorescein isothiocyanate-labeled annexin V/propidium iodide. Activation of caspase 8 was detected by Western blot analysis. RESULTS: Immunocytochemical assay indicated that DR5 was predominantly perinuclear in adherent cells but was mainly localized in cell membrane in detached cells. In addition, immunofluorescence assay also confirmed the above-mentioned results, and further demonstrated that DR5 was present in the form of coarse granules in detached cells, but in the form of fine granules in adherent cells. Cytometry analysis revealed higher levels of DR5 expression on the surfaces of brefeldin-A-untreated cells than on the surfaces of brefeldin-A-treated cells, but brefeldin A treatment did not affect the total DR5 expression levels. Moreover, nocodazole did not influence the extracelluar DR5 expression levels in EC9706 cells. Apoptosis assay revealed that detached cells were more sensitive to DR5 antibody-induced apoptosis than adherent cells. Western blotting showed that caspase 8 was activated in temporarily detached cells 4 h earlier than in adherent cells. CONCLUSION: Progress from adhesion to detachment of EC9706 cells causes DR5 relocalization, and promotes cytoplasmic translocation of DR5 to cell surfaces via a Golgi-dependent pathway. Moreover, it might also result in DR5 aggregation to render apoptosis of detached cells.

The red-spotted grouper, Epinephelus akaara, is a protogynous hermaphroditic fish that shows the characteristic of natural sex change. In this study, 2-year-old female groupers were successfully reversed to functional males by oral administration of 17alpha-methyltestosterone (MT) for 42 days. The protein inhibitor of the neuronal nitric oxide synthase (PIN) gene was cloned from sex-reversed male gonads using modern suppression subtractive hybridization (SSH), cDNA synthesis and rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR). The full-length cDNA of PIN is 499bp containing a 270bp open reading frame (ORF) that encodes 89 amino acids. Virtual Northern blotting and reverse transcription-PCR (RT-PCR) analysis revealed that PIN was specifically transcribed in sex-reversed male gonads. Tissue-specific expression analysis showed that PIN gene was expressed in the brain, heart, liver, spleen, and kidney but not in the muscle tissue. Analyses of the expression pattern by RT-PCR and Western blotting indicated that transcription and the level of expression of PIN in the gonads increased gradually during the transformation from female to male. The results showed that PIN is strongly expressed in the sex-reversed male gonad but scarcely in the female gonad, and that its expression is upregulated as the change of sex proceeds. Taken together, these findings demonstrate that PIN is associated with the MT-induced sex transition of the red-spotted grouper, but the precise role of the gene in this process remains to be further investigated.

After the treatment of porous Si by "amine immersion and rapid thermal oxidation", the peak position of the photoluminescence spectra has a blue shift to 500nm. Only a little change in photoluminescence was observed after 160d storing in dry air. FTIR spectra indicate that the compositions of such treated sample are mainly silicon and oxygen. ESR signal shows that the blue/green light-emitting sample has rather low density of dangling bonds. These results demonstrete that the quantum confinement effect and surface states play a key role in blue/green light emitting. This method is simple and practicable, to make blue/green light-emitting samples and its success ratio can achieve 70%.

Porous silicon is treated in NH3 gas by rapid thermal annealing. FTIR spectra indicate that the surface of the sample is covered with Si(NH)2 and Si3N4 species. ESR signal shows that the sample has rather low density of dangling bonds. The photoluminescence intensity of the treated sample de-creases slightly compared to the sample without the treatment and is very stable while storing in at-mosphere. These results show that nitride can be an excellent passivation film on porous silicon and may be important to the practical applications.

The bright and stable porous silicon have been obtained by using damp oxidation at moderate temperature. EPR measurements showed that the density of Si dangling bonds in the sample is lower than that by dry oxidation. We also took FTIR measurements and concluded that the stabilization of the photoluminescence from porous silicon is due to the formation of SiH(O3), SiH(SiO2) and SiH(O2) structure.

Porous silicon of low porosity was oxidized in boiling HNO3 solution. Photo-luminescence, microluminescence and SEM studies show that the stability and the uniformity of the sample were greatly improved by such a treatment. This is a new method much easier to control than rapid thermal oxidation.

The typical Raman spectrum from light-emitting porous silicon shows a sharp peak near 520cm －１ . The peak wavenumber decreases with the increase of porosity. The lineshape analysis shows that both phonon confinment and strain effects in nanocrystal silicon must be taken into account for the measured Raman spectra. The strain in porous silicon film is estimated and the result is consistent with that given by X-ray diffraction studies. No light scattering from amorphous phase is observed.