Identification of assembly precursors to photosystems emitting fluorescence at 683 nm and 687 nm by cryogenic fluorescence microspectroscopy.

Photosystem I (PSI) and photosystem II (PSII) play key roles in photoinduced electron-transfer reaction in oxygenic photosynthesis. Assemblies of these PSs can be initiated by illumination of the etiolated seedlings (greening). The study aimed to identify specific fluorescence spectral components relevant to PSI and PSII assembly intermediates emerging in greening seedlings of Zea mays, a typical C4 plant. The different PSII contents between the bundle sheath (BS) and mesophyll (M) cells were utilized to spectrally isolate the precursors to PSI and PSII. The greening Zea mays leaf thin sections were observed with the cryogenic microscope combined with a spectrometer. With the aid of the singular-value decomposition analysis, we could identify four independent fluorescent species, SAS677, SAS685, SAS683, and SAS687, named after their fluorescence peak wavelengths. SAS677 and SAS685 are the dominant components after the 30-minute greening, and the distributions of these components showed no clear differences between M and BS cells, indicating immature cell differentiation in this developing stage. On the other hand, the 1-hour greening resulted in reduced distributions of SAS683 in BS cells leading us to assign this species to PSII precursors. The 2-hour greening induced the enrichment of SAS687 in BS cells suggesting its PSI relevance. Similarity in the peak wavelengths of SAS683 and the reported reaction center of PSII implied their connection. SAS687 showed an intense sub-band at around 740 nm, which can be assigned to the emission from the red chlorophylls specific to the mature PSI.

Development of a novel cryogenic microscope with numerical aperture of 0.9 and its application to photosynthesis research.

A novel cryogenic optical-microscope system was developed in which the objective lens is set inside of the cryostat adiabatic vacuum space. Being isolated from the sample when it was cooled, the objective lens was maintained at room temperature during the cryogenic measurement. Therefore, the authors were able to use a color-aberration corrected objective lens with a numerical aperture of 0.9. The lens is equipped with an air vent for compatibility to the vacuum. The theoretically expected spatial resolutions of 0.39µm along the lateral direction and 1.3µm along the axial direction were achieved by the developed system. The system was applied to the observations of non-uniform distributions of the photosystems in the cells of a green alga, Chlamydomonas reinhardtii, at 94K. Gaussian decomposition analysis of the fluorescence spectra at all the pixels clearly demonstrated a non-uniform distribution of the two photosystems, as reflected in the variable ratios of the fluorescence intensities assigned to photosystem II and to those assigned to photosystem I. The system was also applied to the fluorescence spectroscopy of single isolated photosystem I complexes at 90K. The fluorescence, assigned to be emitted from a single photosystem I trimer, showed an intermittent fluctuation called blinking, which is typical for a fluorescence signal from a single molecule. The vibronic fluorescence bands at around 790nm were observed for single photosystem I trimers, suggesting that the color aberration is not serious up to the 800nm spectral region.

[A patient with advanced recurrent breast cancer who firmly resisted hair loss and was then treated by combination therapy with high-dose toremifene and capecitabine].

The patient was a 36-year-old woman, who found a mass in her right breast around April 2002, visited a physician in June, and was referred to our department because of suspected right breast cancer. It was confirmed that the cancer had metastasized to the right axillary lymph nodes and the skin of the right breast. After undergoing an operation on July 11 (Bt+Ax), the patient was placed on tamoxifen (TAM). Then, the course was followed while the patient was treated with CEF and 5'-DFUR. In April 2004, she had a recurrence manifesting itself as bone metastasis, partly because of poor compliance with the hospital-visit and dosing schedules. After chemotherapy with paclitaxel, etc., combination therapy with docetaxel (DOC), capecitabine, and high-dose (120 mg/day) toremifene (TOR) was started on October 15, 2004. Subsequently, because the patient firmly resisted hair loss, chemotherapy was continued with a double-drug regimen with capecitabine and high-dose TOR. Treatment was temporarily discontinued because the patient developed hand-foot syndrome, which was probably attributable to capecitabine, but the symptoms improved after administration of vitamin B(6). Thereafter,the patient complied well with the dosing schedule, and no new metastatic focus has been detected by any examination as of October 2005. These findings suggest that the double-drug regimen with capecitabine and high-dose TOR is an effective treatment for patients who can not be treated with anthracyclines or taxanes.