Energy transfer and trapping in photosystem I reaction centers from cyanobacteria

A mutant strain of the cyanobacterium Synechocystis 6803, TolE4B, was constructed by genetic deletion of the protein that links phycobilisomes to thylakoid membranes and of the CP43 and CP47 proteins of photosystem II (PSII), leaving the photosystem I (PSI) center as the sole chromophore in the photosynthetic membranes. Both intact membrane and detergent-isolated samples of PSI were characterized by time-resolved and steady-state fluorescence methods. A decay component of approximately 25 ps dominates (99% of the amplitude) the fluorescence of the membrane sample. This result indicates that an intermediate lifetime is not associated with the intact membrane preparation and the charge separation in PSI is irreversible. The decay time of the detergent-isolated sample is similar. The 600-nm excited steady-state fluorescence spectrum displays a red fluorescence peak at approximately 703 nm at room temperature. The 450-nm excited steady-state fluorescence spectrum is dominated by a single peak around 700 nm without 680-nm "bulk" fluorescence. The experimental results were compared with several computer simulations. Assuming an antenna size of 130 chlorophyll molecules, an apparent charge separation time of approximately 1 ps is estimated. Alternatively, the kinetics could be modeled on the basis of a two-domain antenna for PSI, consistent with the available structural data, each containing approximately 65 chlorophyll a molecules. If excitation can migrate freely within each domain and communication between domains occurs only close to the reaction center, a charge separation time of 3-4 ps is obtained instead.

[Determination of primaquine and hepatic targeting neoglycoalbumin-primaquine in whole blood and liver of mouse by normalphase high-performance liquid chromatography]

We have developed a method to estimate primaquine (PQ) and hepatic targeting antimalarial agent neoglycoalbumin-primaquine (NGA PQ) in whole blood and liver of mice by sensitive and selective high-performance liquid chromatography. The primaquine was extracted out with ether from the basified biological samples in the PQ diphosphate group or from the samples which were acidic hydrolyzed then basified in NGA-PQ group. The extracts were evaporated under N2 then dissolved in the mobile phase. A linear chain analogue of primaquine was used as the internal standard. The samples were injected into the normal phase silica column with chloroform: methanol:ammonia solution (86.8:12.5:0.7,V/V/V) as mobile phase and detected at 254 nm. The average recovery of the method was 100.09 +/- 3.46 (mean +/- s)%; the CV of within-day and between-day were 2.7%-6.13% (n = 5) and 8.32%-13.56% (n = 9) respectively; in PQ group and NGA-PQ group, the PQ concentrations ranged from 10-20,000 ng/ml blood or 1g. liver respectively, and they all yielded a good linear relationship with the peak height ratios. No endogeneous interference was found in chromatograms of biological samples.

Clinical observation on needling extrachannel points in treating mental depression

Totally 20 cases of mental depression were treated by needling extrachannel points with an effective rate of 90%; comparison of these cases with 21 controls treated with amitriptyline, showed no significant difference in effect (P > 0.05). Measured with Hamilton's scale, factors of anxiety somatization, cognitive disturbance, retardation, sleep disturbance and feeling of despair in both the needling and control groups showed obvious decrease in the mean value, and the change in anxiety somatization was markedly significant in the needling group as compared with that in the controls (P < 0.01). Our studies revealed that after 6 weeks of needling the power of slow wave delta decreased while that of the fast wave alpha increased, all significantly different as compared with that before and during the treatment (P < 0.05).

MHC-independent presentation of mycobacteria to human gamma delta T cells

The majority of human peripheral gamma delta T cells express antigen receptors using the V gamma 9 and V delta 2 gene products. Cells of this subset have been previously shown to uniformly recognize mycobacteria regardless of their V-(D)-J junctional sequences in an MHC-unrestricted manner. This reactivity superficially resembles activation of alpha beta cells by bacterial superantigens, which are thought to be presented by monomorphic regions of MHC class II molecules. It is not known whether presentation of the mycobacterial antigen to V gamma 9/V delta 2 T cells is also mediated by class II MHC molecules. In order to examine the similarity between presentation of bacterial superantigens to alpha beta T cells and the presentation of mycobacteria to gamma delta T cells we have studied the role of class II MHC molecules in presentation of the mycobacterial antigen AP-MT to V gamma 9/V delta 2 clones. Activation of gamma delta T cells by AP-MT required direct contact with antigen presenting cells, indicating that an interaction with cell surface molecules on antigen presenting cells is required. Class II MHC molecules were neither sufficient nor necessary for effective presentation of AP-MT to the gamma delta T cells, as transfectants expressing class II MHC molecules were unable to present, whereas cell lines lacking expression of MHC class II molecules could present this mycobacterial antigen.(ABSTRACT TRUNCATED AT 250 WORDS)

Antimicrobial compounds from Petalostemum purpureum

EtOH extracts of Petalostemum purpureum demonstrated antimicrobial activity against bacteria and fungi. Bioassay-directed fractionation led to the isolation of petalostemumol [1] as the active constituent. Its structure was determined by a single crystal X-ray diffraction analysis. A minor component designated petalostemumol G [3] is believed to be an artifact of the isolation procedure. Its structure was confirmed by a single crystal X-ray analysis of its pentamethylether 2. A number of derivatives of 1 and 3, including the Me- and benzylethers and acetates, were prepared.

[Thin layer chromatography for identification of 9 species of traditional Chinese medicine in baihe gujin tang granules]

Baihe Gujin Tang granules are mainly composed of nine species of traditional Chinese medicine and other admixtures, so the composition is very complex. In order to confirm the presence of each traditional Chinese medicine in the preparation, a thin layer chromatographic method was developed successfully for analysis of Scrophulariae, Platycodon, Paeoniae and Glycyrrhizae.

Simulations of the temperature dependence of energy transfer in the PSI core antenna

In order to understand the organization of the PSI core antenna and to interpret results obtained from studies of the temperature and wavelength dependence of energy transfer and trapping in the PSI particles, we have constructed a model for PSI in which spectral heterogeneity is considered via a self-consistent approach based on Forster transport. The temperature dependence of the absorption and emission spectra of the individual Chl molecules in the protein matrix is calculated based on a model Hamiltonian which includes a phonon contribution. Time and wavelength resolved kinetics of PSI at different temperatures are investigated by means of two-dimensional lattice models. We conclude that wavelength-dependent fluorescence decay kinetics result only when two or more bottlenecks exist in the energy transfer and trapping process. A single trap or several pseudo-traps with spectrally identical environments do not lead to wavelength dependent decays. Simple funnel arrangements of the spectral types can be ruled out. At least one pigment with energy lower than the photochemical trap located close to the reaction center is required to produce the trends of the fluorescence lifetimes observed experimentally. The remainder of the core antenna is consistent with a random arrangement of spectral types.

Energy transfer and trapping in the photosystem I core antenna. A temperature study

The fluorescence decay kinetics of the photosystem I-only mutant strain of Chlamydomonas reinhardtii, A4d, are used to study energy transfer and structural organization in photosystem I (PSI). Time-resolved measurements over a wide temperature range (36-295 K) have been made both on cells containing approximately 65 core chl a/P700 and an additional 60-70 chl a + b from LHC proteins and on PSI particles containing 40-50 chl a/P700. In each case, the fluorescence decay kinetics is dominated by a short component, tau 1 which is largely attributed to the lifetime of the excitations in the core complex. The results are discussed in terms of simulations of the temperature dependence of tau 1 in model systems. Spectral inhomogeneity and the temperature dependence of the spectral lineshapes are included explicitly in the simulations. Various kinds of antenna arrangements are modeled with and without the inclusion of pigments with lower absorption energies than the trap (red pigments). We conclude that funnel arrangements are not consistent with our measurements. A random model that includes one or two red pigments placed close to the trap shows temperature and wavelength dependence similar to that observed experimentally. A comparison of the temperature dependence of tau 1 for cells and PSI particles is included.

[Inhibitory effects of the extract of pilose antler on monoamine oxidase in aged mice]

It was demonstrated that the water extract of Pilose Antler (WEPA) showed a higher inhibitory effect on MAO-B activities in the liver and brain tissues of aged mice, but nearly no effect on NAO-A. WEPA could significantly increase the contents of 5-HT, NE and DA in the brain tissues of aged mice. In vitro experiments revealed that the inhibition of WEPA on MAO-B was competitive, but on MAO-A was of mixed-type.

Secondary prevention of myocardial reinfarction with low dose aspirin

A clinical trial of secondary prevention of reinfarction with low dose aspirin is reported. 50 mg aspirin per day was administered in 216 case. 211 cases did not take aspirin or any other antiplatelet agents as a control group. The follow-up periods in the two groups were 19.4 +/- 12.6 mon and 20.7 +/- 13.0 mon, respectively. There were 175 males in the aspirin group and 137 males in the control group. The incidence of reinfarction was reduced by 65% and platelet aggregation was inhibited obviously in the aspirin group as compared to the control group in men, whereas no significant trends were observed in women.

The complete sequence of the unit YCR59, situated between CRY1 and MAT, reveals two long open reading frames, which cover 91% of the 10.1 kb segment

We have entirely sequenced YCR59, which is a 10.1 kb segment of the right arm of chromosome III, and is part of the clone E5F from the Newlon collection. The segment contains two long open reading frames (ORFs): YCR591 which starts in the adjacent fragment H9G (situated towards CRY1 and the centromere), and continues with 1833 codons in YCR59. The second ORFYCR592 is 1226 codons long and encoded entirely within YCR59. The two ORFs represent 91% of the total length of the segment. Excellent agreement in both location and length is found between the ORFs YCR591 and YCR592 and the transcripts 86 and 87 respectively in the Yoshikawa and Isono (1990) map of chromosome III. The two ORFs correspond to new genes and show no significant similarity with any known genes.

Further eudesmane derivatives from verbesina species

The aerial parts of VERBESINA PERSICIFOLIA DC afforded a new eudesmane derivative in addition to known compounds. The roots of V. SUBCORDATA gave also new eudesmane cinnamates in addition to several known ones as well as a 5alpha-hydroxybicyclogermacra-1 (10) E, 4 (15)-diene. A reinvestigation of V. VIRGINICA L. gave two new ( Z)-configurated coumarates. Furthermore the structures of some sesquiterpenes are revised. The structures were elucidated by highfield NMR spectroscopy and a few chemical reactions.

Bisabolone derivatives and sesquiterpene lactones from centaurea species

The investigation of three CENTAUREA species collected in Argentina afforded, in addition to several known sesquiterpene lactones, a new guaianolide, a germacranolide, and two bisabolone derivatives. The structures were elucidated by highfield (1)H-NMR spectroscopy.