An Antifungal Constituent in Enkianthus perulatus

A new cinnamate was isolated as an antifungal constituent from young leaves and shoots of Enkianthus perulatus. The structure was shown to be 1 on the basis of the chemical and spectroscopic studies.     

Characterization of male meiotic germ cell-specific antigen (Meg 1) by monoclonal antibody TRA 369 in mice.

We have identified a male meiotic germ cell-specific antigen (Meg 1) with monoclonal antibody (mAb) TRA 369 in mice. The Meg 1 antigen was strongly expressed in specific steps of meiotic germ cells from pachytene spermatocyte to early spermatid, and not in other germ cells or somatic cells. Immunohistochemical examination revealed that the antigen was localized to the cytoplasm and was not distributed in the nucleus or on the cell surface. This antigen was demonstrated to have a molecular weight of 93 kDa and an isoelectric point of 5.2 by Western blotting. This molecule was first detected in the testis of 13-day-old mouse when pachytene spermatocytes first appeared. Thus this is a differentiation-specific antigen in male meiotic germ cells, and mAb TRA 369 is a useful tool to study the regulation of germ cell differentiation and to define germ cell development in a molecular level.     

Light induced structural changes of a full-length protein and its BLUF domain in YcgF(Blrp), a blue-light sensing protein that uses FAD (BLUF)

Blue-light sensing proteins that use FAD (BLUF) are members of a blue-light receptor family that is widely distributed among microorganisms. The Escherichia coli YcgF protein is a BLUF protein consisting of the N-terminal FAD-binding hold (BLUF domain) and the C-terminal EAL domain. The EAL domain of YcgF is predicted to have cyclic-di-GMP phosphodiesterase activity. Light-induced structural changes for the signaling state formation were studied using the light-induced Fourier transform infrared (FTIR) difference spectroscopy of both the full-length YcgF protein (YcgF-Full) and its BLUF domain (YcgF-BLUF). YcgF-Full and YcgF-BLUF showed identical UV-visible absorption spectra of flavin in the dark state and a light-induced absorption red shift for the signaling state, which relaxed to the dark state showing identical kinetics. The light-induced FTIR difference spectrum of YcgF-Full, however, was markedly different from that of YcgF-BLUF. The spectrum of YcgF-BLUF lacked most of the IR bands that were induced in the YcgF-Full spectrum. These bands were assigned to the light-induced structural changes of the protein. However, the bands for the C4=O stretching of a FAD isoalloxazine ring were induced at the same frequency with the same band intensity in the spectra for YcgF-Full and YcgF-BLUF. Furthermore, the YcgF-Full spectrum resembled that of the YcgF-BLUF when illuminated at medium-low temperatures because of the selective suppression of protein bands. The possibility that full-length-specific protein bands are predominantly ascribed to structural changes of the C-terminal EAL domain in the signaling state as a consequence of light excitation of the N-terminal BLUF domain is discussed.     

Quantitative Analysis of β-Amyloid Peptides Expressed in Human Cerebrospinal Fluid by an Improved Method of Antibody-Assisted Time-of-Flight Mass Spectrometry

Establishment of diagnostic measures for early stage Alzheimer’s disease (AD) and mild cognitive impairment (MCI) is of crucial importance. Using surface enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS), antibody-assisted MS of cerebrospinal fluid (CSF) has enabled quantitative analysis of the ratio of β-amyloid (Aβ) peptides, Aβ1-42/Aβ1-40, which has a diagnostic value for AD/MCI. To apply the MS analysis to a far wider range of CSF samples, we have established a method to analyze Aβ peptides expressed in 100 μl CSF samples quantitatively. Pretreatment of CSF samples by limit-filtration to condense peptides, and modified washing procedure using urea as denaturant, Aβ peptides of interest can be assessed with higher sensitivity by five to tenfolds to the original method. This improvement enables quantitative analysis of Aβ species from a residual amount of CSF samples, which will be occasionally obtained in case of lumbar anesthesia prior to operation and spinal tap performed for routine diagnostic purposes. Prevalence of the new procedure as laboratory test, especially among the elderly consulting for neurological clinic, will enhance the number of subjects diagnosed at early stage of AD/MCI.     

Construction of a Genetic Map and Development of DNA Markers Linked to the Sex-Determining Locus in the Patagonian Pejerrey (Odontesthes hatcheri)

The process of sex differentiation in fishes is regulated by genetic and environmental factors. The sex of Patagonian pejerrey (Odontesthes hatcheri) appears to be under strong genotypic control (GSD) because the sex ratios are balanced (1:1) between 17°C and 23°C. However, sex ratios become female-biased at <15°C and male-biased at 25°C, which shows that this species also possesses some degree of temperature-dependent sex determination (TSD). Identification of the genetic sex of an individual will help elucidate the molecular basis of sex differentiation in this species. In this study, we used amplified fragment length polymorphism (AFLP) analysis to develop a genetic linkage map for both sexes and a sex-linked DNA marker for Patagonian pejerrey. The AFLP analysis of 23 male and 23 female progeny via 64 primer combinations produced a total of 153 bands. The genetic linkage map consisted of 79 markers in 20 linkage groups and 48 markers in 15 linkage groups for males and females, respectively. One AFLP marker tightly linked to the sex-determining locus was identified: the marker, ACG/CAA-217, amplified to the male-specific DNA fragment. Sequence analysis of this region revealed a single nucleotide polymorphism (SNP) between males and females, which was converted into a SNP marker. This marker provides genetic confirmation that the sex of Patagonian pejerrey is determined genetically and would be useful for the analysis of the molecular basis of GSD and TSD in this species.     

Light-induced structural changes in a putative blue-light receptor with a novel FAD binding fold sensor of blue-light using FAD (BLUF); Slr1694 of synechocystis sp. PCC6803

The sensor of blue-light using FAD (BLUF) domain is the flavin-binding fold categorized to a new class of blue-light sensing domain found in AppA from Rhodobacter sphaeroides and PAC from Euglena gracilis, but little is known concerning the mechanism of blue-light perception. An open reading frame slr1694 in a cyanobacterium Synechocystis sp. PCC6803 encodes a protein possessing the BLUF domain. Here, a full-length Slr1694 protein retaining FAD was expressed and purified and found to be present as an oligomeric form (trimer or tetramer). Using the purified Slr1694, spectroscopic properties of Slr1694 were characterized. Slr1694 was found to show the same red-shift of flavin absorption and quenching of flavin fluorescence by illumination as those of AppA. These changes reversed in the dark although the rate of dark state regeneration was much faster in Slr1694 than AppA, indicating that Slr1694 is a blue-light receptor based on BLUF with the similar photocycle to that of AppA. The dark decay in D(2)O was nearly four times slower than in H(2)O. Light-induced Fourier transform infrared (FTIR) difference spectroscopy was applied to examine the light-induced structure change of a chromophore and apo-protein with deuteration and universal (13)C and (15)N isotope labeling. The FTIR results indicate that light excitation induced distinct changes in the amide I modes of peptide backbone but relatively limited changes in flavin chromophore. Light excitation predominantly weakened the C(4)=O and C(2)=O bonding and strengthened the N1C10a and/or C4aN5 bonding, indicating formational changes of the isoalloxazine ring II and III of FAD but little formational change in the isoalloxazine ring I. The photocycle of the BLUF is unique in the sense that light excitation leads to the structural rearrangements of the protein moieties coupled with a minimum formational change of the chromophore.     

Comparison of the subunit compositions of the PSI-LHCI supercomplex and the LHCI in the green alga Chlamydomonas reinhardtii

Although the light-harvesting chlorophyll protein complex I (LHCI) of photosystem I (PSI) is intimately associated with the PSI core complex and forms the PSI-LHCI supercomplex, the LHCI is normally synthesized in PSI-deficient mutants. In this paper, we compared the subunit compositions of the PSI-LHCI supercomplex and the LHCI by immunoblot analysis and two-dimensional gel electrophoresis combined with mass spectrometry. The PSI-LHCI supercomplex and the LHCI were purified by sucrose density gradient centrifugation and (diethylamino)ethyl column chromatography from n-dodecyl-beta-D-maltoside-solubilized thylakoids of the wild-type and DeltapsaB mutant of the green alga Chlamydomonas reinhardtii. The PSI-LHCI supercomplex contained all of the nine Lhca polypeptides (Lhca1-9) that are detected in wild-type thylakoids. In contrast, the LHCI retained only six Lhca polypeptides, whereas Lhca3 and two minor polypeptides, Lhca2 and Lhca9, were lost during the purification procedure. Sucrose density gradient centrifugation showed that the purified LHCI retains an oligomeric structure with an apparent molecular mass of 300-400 kDa. We therefore concluded that Lhca2, Lhca3, and Lhca9 are not required for the stable oligomeric structure of the LHCI and that the association of these polypeptides in the LHCI is stabilized by the presence of the PSI core complex. Finally, we discuss the possible localization and function of Lhca polypeptides in the LHCI.     

Oxidation of the Mn cluster induces structural changes of NO3- functionally bound to the Cl- site in the oxygen-evolving complex of photosystem II

Cl(-) is an indispensable cofactor for photosynthetic O(2) evolution and is functionally replaced by NO(3)(-). Structural changes of an isotopically labeled NO(3)(-) ion, induced by the oxidation of the Mn cluster (S(1)-to-S(2)), were detected by FTIR spectroscopy. NO(3)(-)-substituted photosystem II core particles showed (14)N(16)O(3)(-)/(15)N(16)O(3)(-) and (14)N(16)O(3)(-)/(14)N(18)O(3)(-) isotopic bands in the S(2)/S(1) spectra with markedly high signal/noise ratio. These bands appeared only in the region from 1415 to 1284 cm(-1), indicating that the bands do not arise from a metal-bound NO(3)(-) but from an ionic NO(3)(-). The intensity of the bands exhibited a quantitatively proportional relationship with the O(2) activity. These results demonstrate that the NO(3)(-) functionally bound to the Cl(-) site couples to the Mn cluster structurally, but is not associated with the cluster as a direct ligand. Comparison of the bands for two isotopes ((15)N and (18)O) and their simulations enable us to assign each band to the S(1) and S(2) states. The results indicate that the NO(3)(-) ion bound to the Cl(-) site is highly asymmetric in S(1) but rather symmetric in S(2). Since NO(3)(-) functionally replaces Cl(-), most of the conclusions drawn from this study will be also applicable to Cl(-).