Deriving a reduction factor for woody part of culm for bamboo Phyllostachys pubescens

We determined the reduction factor for the woody part of culm for one of the largest bamboo species, Phyllostachys pubescens Mazel ex Houz. The determined reduction factor enables us to convert the cross-sectional area of the whole culm into that of the culm wall. We collected 650 cross-cutting sample culms from a stand of P. pubescens in Mt. Toshima, Kumamoto Prefecture, western Japan. For the cut-end surface, the external culm diameter and culm wall thickness were measured, and then the cross-sectional area of the whole culm and the culm wall were computed. The cross-sectional area of the culm wall was strongly correlated with that of the whole culm. The regression analysis between these cross-sectional area indicated that the reduction factor for P. pubescens was 0.311, independent of the magnitude of the cross-sectional area. The independence implied that the determined reduction factor could be directly applied to convert the apparent culm volume into wood volume. Implications of the reduction factor for estimating transpiration and carbon stock of P. pubescens stands were discussed. The Monte Carlo simulation revealed that at least, but not more than, 60–70 cross-cutting culms collected from 20 culms are necessary for the reduction factor when estimating the stand level transpiration and carbon stock.     

Presynaptic Selectivity of a Ligand for Serotonin 1A Receptors Revealed by In Vivo PET Assays of Rat Brain

A novel investigational antidepressant with high affinity for the serotonin transporter and the serotonin 1A (5-HT(1A)) receptor, called Wf-516 (structural formula: (2S)-1-[4-(3,4-dichlorophenyl)piperidin-1-yl]-3-[2-(5-methyl-1,3,4-oxadiazol-2-yl)benzo[b]furan-4-yloxy]propan-2-ol monohydrochloride), has been found to exert a rapid therapeutic effect, although the mechanistic basis for this potential advantage remains undetermined. We comparatively investigated the pharmacokinetics and pharmacodynamics of Wf-516 and pindolol by positron emission tomographic (PET) and autoradiographic assays of rat brains in order to elucidate their molecular interactions with presynaptic and postsynaptic 5-HT(1A) receptors. In contrast to the full receptor occupancy by pindolol in PET measurements, the binding of Wf-516 to 5-HT(1A) receptors displayed limited capacity, with relatively high receptor occupancy being achieved in regions predominantly containing presynaptic receptors. This selectivity was further proven by PET scans of neurotoxicant-treated rats deficient in presynaptic 5-HT(1A) receptors. In addition, [(35)S]guanosine 5'-O-[γ-thio]triphosphate autoradiography indicated a partial agonistic ability of Wf-516 for 5-HT(1A) receptors. This finding has lent support to reports that diverse partial agonists for 5-HT(1A) receptors exert high sensitivity for presynaptic components. Thus, the present PET data suggest a relatively high capacity of presynaptic binding sites for partial agonists. Since our in vitro and ex vivo autoradiographies failed to illustrate these distinct features of Wf-516, in vivo PET imaging is considered to be, thus far, the sole method capable of pharmacokinetically demonstrating the unique actions of Wf-516 and similar new-generation antidepressants.     

Fluorescent probes for imaging endogenous β-actin mRNA in living cells using fluorescent protein-tagged pumilio

Subcellular localization and dynamics of mRNAs control various physiological functions in living cells. A novel technique for visualizing endogenous mRNAs in living cells is necessary for investigation of the spatiotemporal movement of mRNAs. A pumilio homology domain of human pumilio 1 (PUM-HD) is a useful RNA binding protein as a tool for mRNA recognition because the domain can be modified to bind a specific 8-base sequence of target mRNA. In this study, we designed PUM-HD to match the sequence of β-actin mRNA and developed an mRNA probe consisting of two PUM-HD mutants flanking full-length enhanced green fluorescent protein (EGFP). Fluorescence microscopy with the probe in living cells revealed that the probe was labeled precisely with the β-actin mRNA in cytosol. Fluorescent spots from the probe were colocalized with microtubules and moved directionally in living cells. The PUM-HD mutants conjugated with full-length EGFP can enable visualization of β-actin mRNA localization and dynamics in living cells.     

Taxonomic revision of the genus Cutleria proposing a new genus Mutimo to accommodate M. cylindricus (Cutleriaceae,Phaeophyceae)

Molecular phylogenetic analyses of representative Cutleria species using mitochondrial cox3, chloroplast psaA, psbA and rbcL gene sequences showed that C. cylindrica Okamura was not included in the clade composed of other Cutleria species including the generitype C. multifida (Turner) Greville and the related taxon Zanardinia typus (Nardo) P.C. Silva. Instead, C. cylindrica was sister to the clade composed of the two genera excluding C. cylindrica. Cutleria spp. have heteromophic life histories and their gametophytes are rather diverse in gross morphology, from compressed or cylindrical‐branched to fan‐shaped, whereas the sporophytes are rather similar. In contrast, the monotypic species Z. typus has an isomorphic life history and resembles fan‐shaped Cutleria in morphology. Morphological comparisons of these taxa revealed that C. cylindrica is morphologically distinct from other Cutleria spp. and Z. typus in having cylindrical gametophytes with multiseriate trichothallic filaments instead of uniseriate filaments (hairs) characteristic of Cutleriales (or Cutleriaceae, Tilopteridales), and in lacking rhizoidal filaments in the crustose sporophytes. Therefore, based on the molecular and morphological data, the establishment of a new genus Mutimo to accommodate C. cylindrica, and the new combination of M. cylindricus, is proposed.     

Identification of two homologous genes, chlAI and chlAII, that are differentially involved in isocyclic ring formation of chlorophyll a in the cyanobacterium Synechocystis sp. PCC 6803

The isocyclic ring (E-ring) is a common structural feature of chlorophylls. The E-ring is formed by two structurally unrelated Mg-protoporphyrin IX monomethylester (MPE) cyclase systems, oxygen-dependent (AcsF), and oxygen-independent (BchE) systems, which involve incorporation of an oxygen atom from molecular oxygen and water into the C-13(1) position of MPE, respectively. Which system operates in cyanobacteria that can thrive in a variety of anaerobic environments remains an open question. The cyanobacterium Synechocystis sp. PCC 6803 has two acsF-like genes, sll1214 (chlA(I)) and sll1874 (chlA(II)), and three bchE-like genes, slr0905, sll1242, and slr0309. Five mutants lacking one of these genes were isolated. The DeltachlA(I) mutant failed to grow under aerobic conditions with anomalous accumulation of a pigment with fluorescence emission peak at 595 nm, which was identified 3,8-divinyl MPE by high-performance liquid chromatography-mass spectrometry analysis. The growth defect of DeltachlA(I) was restored by the cultivation under oxygen-limited (micro-oxic) conditions. MPE accumulation was also detected in DeltachlA(II) grown under microoxic conditions, but not in any of the bchE mutants. The phenotype was consistent with the expression pattern of two chlA genes: chlA(II) was induced under micro-oxic conditions in contrast to the constitutive expression of chlA(I). These findings suggested that ChlA(I) is the sole MPE cyclase system under aerobic conditions and that the induced ChlA(II) operates together with ChlA(I) under micro-oxic conditions. In addition, the accumulation of 3,8-divinyl MPE in the DeltachlA mutants suggested that the reduction of 8-vinyl group occurs after the formation of E-ring in Synechocystis sp. PCC 6803.     

TRPM2-mediated Ca2+influx induces chemokine production in monocytes that aggravates inflammatory neutrophil infiltration

Reactive oxygen species (ROS) induce chemokines responsible for the recruitment of inflammatory cells to sites of injury or infection. Here we show that the plasma membrane Ca(2+)-permeable channel TRPM2 controls ROS-induced chemokine production in monocytes. In human U937 monocytes, hydrogen peroxide (H(2)O(2)) evokes Ca(2+) influx through TRPM2 to activate Ca(2+)-dependent tyrosine kinase Pyk2 and amplify Erk signaling via Ras GTPase. This elicits nuclear translocation of nuclear factor-kappaB essential for the production of the chemokine interleukin-8 (CXCL8). In monocytes from Trpm2-deficient mice, H(2)O(2)-induced Ca(2+) influx and production of the macrophage inflammatory protein-2 (CXCL2), the mouse CXCL8 functional homolog, were impaired. In the dextran sulfate sodium-induced colitis inflammation model, CXCL2 expression, neutrophil infiltration and ulceration were attenuated by Trpm2 disruption. Thus, TRPM2 Ca(2+) influx controls the ROS-induced signaling cascade responsible for chemokine production, which aggravates inflammation. We propose functional inhibition of TRPM2 channels as a new therapeutic strategy for treating inflammatory diseases.