圆菱叶长柄山蚂蝗一新异名

摘要查阅了澜沧长柄山蚂蝗Hylodesmum lancangense (Y. Y. Qian) X. Y. Zhu & H. Ohashi的模式标本后,确认该种应归并入圆菱叶长柄山蚂蝗H. podocarpum (DC.) H. Ohashi & R. R. Mill ssp. podocarpum。     

New synonymies of some species of Pittosporum (Pittosporaceae)

As part of a revision of Chinese Pittosporum Banks ex Gaertn. for the forthcoming account of Pittosporaceae in “Flora of China”, Volume 9, eight names, all described from China, are reduced to synonymy as follows: P. illicioides Makino var. angustifolium T. C. Huang ex S. Y. Lu, syn. nov. and P. illicioides var. stenophyllum P. L. Chiu ex H. T. Chang & S. Z. Yan, syn. nov., both under P. illicioides; P. densinervatum H. T. Chang & S. Z. Yan, syn. nov. and P. longicarpum S. K. Wu ex C. Y. Wu, syn. nov., both under P. kweichowense Gowda var. kweichowense; P. polycarpum H. T. Chang & S. Z. Yan, syn. nov. under P. paniculiferum H. T. Chang & S. Z. Yan; P. membranifolium S. C. Huang ex C. Y. Wu, syn. nov. under P. perryanum Gowda var. perryanum; P. motanthum C. Y. Wu, syn. nov. under P. podocarpum Gagnep. var. podocarpum; and P. tobira (Thunb.) W. T Aiton var. chinense S. Kobayashi, syn. nov. under P. tobira.     

海桐花属一些种类的新异名

作为对英文版“Flora of China”海桐花科的分类学修订结果,提出了海桐花属6个种的8个新异名,并分别进行了讨论。     

中国马蓝属(爵床科)新组合和新分类群(英文)

采用广义的马蓝属(Strobilanthes Blume)概念,提出3个新组合:匍匐半插花(S.primulifolia(Nees)Y.F.DengJ.R.I.Wood),直立半插花(S.cumingiana(Forst.)Y.F.DengJ.R.I.Wood)和狭叶马蓝(S.atropurpurea var.stenophylla(C.B.Clarke)Y.F.DengJ.R.I.Wood);描述了8新种:南岭马蓝(Strobilanthes austrosinensis Y.F.DengJ.R.I.Wood)、冯氏马蓝(S.fengiana Y.F.DengJ.R.I.Wood)、陶氏马蓝(S.taoana Y.F.DengJ.R.I.Wood)、启无马蓝(S.wangiana Y.F.DengJ.R.I.Wood)、景东马蓝(S.atroviridis Y.F.DengJ.R.I.Wood)、西畴马蓝(S.rostrata Y.F.DengJ.R.I.Wood)、黄连山马蓝(S.spiciformis Y.F.DengJ.R.I.Wood)和匍匐马蓝(S.procumbens Y.F.DengJ.R.I.Wood)。对南岭马蓝、黄连山马蓝、景东马蓝和匍匐马蓝的花粉形态进行了观察。     

Receptor subtype-specific docking of Asp6.59 with C-terminal arginine residues in Y receptor ligands

Y receptors (YRs) are G protein-coupled receptors whose Y(1)R, Y(2)R, and Y(5)R subtypes preferentially bind neuropeptide Y (NPY) and peptide YY, whereas mammalian Y(4)Rs show a higher affinity for pancreatic polypeptide (PP). Comparison of YR orthologs and paralogs revealed Asp(6.59) to be fully conserved throughout all of the YRs reported so far. By replacing this conserved aspartic acid residue with alanine, asparagine, glutamate, and arginine, we now show that this residue plays a crucial role in binding and signal transduction of NPY/PP at all YRs. Sensitivity to distinct replacements is, however, receptor subtype-specific. Next, we performed a complementary mutagenesis approach to identify the contact site of the ligand. Surprisingly, this conserved residue interacts with two different ligand arginine residues by ionic interactions; although in Y(2)R and Y(5)R, Arg(33) is the binding partner of Asp(6.59), in Y(1)R and Y(4)R, Arg(35) of human PP and NPY interacts with Asp(6.59). Furthermore, Arg(25) of PP and NPY is involved in ligand binding only at Y(2)R and Y(5)R. This suggests significant differences in the docking of YR ligands between Y(1/4)R and Y(2/5)R and provides new insights into the molecular binding mode of peptide agonists at GPCRs. Furthermore, the proposed model of a subtype-specific binding mode is in agreement with the evolution of YRs.     

Antiosteoporotic flavonoids from Podocarpium podocarpum

A novel bi-isoflavonoid, podocarnone (1), together with five known flavonoids, namely genistein (2), afzelin (3), astragalin (4), luteolin (5) and pratensein (6), were isolated from the whole plants of Podocarpium podocarpum (DC.) Yang and Huang for the first time. The structure of podocarnone (1) was elucidated by detailed spectroscopic analyses, including 1D and 2D NMR techniques. All the isolated compounds were evaluated for their proliferative effects on osteoblasts derived from neonatal rat calvaria and inhibitory effects on multinucleated osteoclasts from rat marrow cells so as to explore the antiosteoporotic activity of these components. Podocarnone (1) exhibited potent stimulatory effects on osteoblastic proliferation and ALP (alkaline phosphatase) activity, and significantly inhibited the activity of osteoclastic TRAP (tartrate-resistant acid phosphatase) in the low concentration range of 10^?12–10^?14 mol/L, which were equivalent to the activity of genistein (2) in the concentration range of 10^?7–10^?9 mol/L. The other five known flavonoids also showed varied degrees of antiosteoporotic activities, and structure–activity relationship analysis revealed the number of phenolic rings contained in these structures maybe responsible for the antiosteoporosis property.     

Inhibiting neuropeptide Y Y1 receptor modulates melanocortin receptor- and NF-κB-mediated feeding behavior in phenylpropanolamine-treated rats

Neuropeptide Y (NPY) and nuclear factor-kappa B (NF-κB) are involved in regulating anorexia elicited by phenylpropanolamine (PPA), a sympathomimetic drug. This study explored whether NPY Y1 receptor (Y1R) is involved in this process, and a potential role for the proopiomelanocortin system was identified. Rats were given PPA once a day for 4 days. Changes in the hypothalamic expression of the NPY, Y1R, NF-κB, and melanocortin receptor 4 (MC4R) levels were assessed and compared. The results indicated that food intake and NPY expression decreased, with the largest reductions observed on Day 2 (approximately 50% and 45%, respectively), whereas NF-κB, MC4R, and Y1R increased, achieving maximums on Day 2 (160%, 200%, and 280%, respectively). To determine the role of Y1R, rats were pretreated with Y1R antisense or a Y1R antagonist via intracerebroventricular injection 1 h before the daily PPA dose. Y1R knockdown and inhibition reduced PPA anorexia and partially restored the normal expression of NPY, MC4R, and NF-κB. The data suggest that hypothalamic Y1R participates in the appetite-suppression from PPA by regulating MC4R and NF-κB. The results of this study increase our understanding of the molecular mechanisms in PPA-induced anorexia.     

Antiosteoporotic activity and constituents of Podocarpium podocarpum

Our study aimed to investigate the antiosteoporotic properties of the ethanol extract of Podocarpium podocarpum (DC.) Yang et Huang (PE) in ovariectomized (OVX) rats and to characterize the active constituents. As a result, PE significantly inhibited the increased urinary Ca excretion and activity of bone resorption markers including tartrate-resistant acid phosphatase (TRAP), deoxypyridinoline crosslinks and cathepsin K in OVX rats, whereas exhibited little effects on the body, uterus and vagina weight. Detailed micro-CT analysis showed that PE notably enhanced bone quality, with increased bone mineral content (BMC), bone volume fraction (BVF), connectivity density (CD), tissue mineral content (TMC), tissue mineral density (TMD) and trabecular number (Tb. N), and decreased trabecular separation (Tb. Sp), in OVX animal. Those findings implied that PE had notable antiosteoporotic effect, especially effective in preventing bone resorption, with little side-effects on reproductive tissue. Further chemical investigation led to the isolation of 17 flavonoids, most of which showed significantly stimulatory effect on osteoblastic proliferation, ALP activity and mineralized nodes formation as well as inhibitory effect on osteoclastic TRAP activity in osteoblastic and osteoclastic cells. Our results indicated that PE, with abundant flavonoids, had remarkable antiosteoporotic activity and therefore can be a promising candidate for the treatment of postmenopausal osteoporosis induced by estrogen deficiency through herbal remedy.     

Neuropeptide Y Y5-receptor activation on breast cancer cells acts as a paracrine system that stimulates VEGF expression and secretion to promote angiogenesis

Accumulating data implicate a pathological role for sympathetic neurotransmitters like neuropeptide Y (NPY) in breast cancer progression. Our group and others reported that NPY promotes proliferation and migration in breast cancer cells, however the angiogenic potential of NPY in breast cancer is unknown. Herein we sought to determine if NPY promotes angiogenesis in vitro by increasing vascular endothelial growth factor (VEGF) expression and release from 4T1 breast cancer cells. Western blot analysis revealed that NPY treatment caused a 52 ± 14% increase in VEGF expression in the 4T1 cells compared to non-treated controls. Using selective NPY Y-receptor agonists (Y1R, Y2R and Y5R) we observed an increase in VEGF expression only when cells were treated with Y5R agonist. Congruently, using selective Y1R, Y2R, or Y5R antagonists, NPY-induced increases in VEGF expression in 4T1 cells were attenuated only under Y5R antagonism. Endothelial tube formation assays were conducted using conditioned media (CM) from NPY treated 4T1 cells. Concentration-dependent increases in number of branch points and complete endothelial networks were observed in HUVEC exposed to NPY CM. CM from Y5R agonist treated 4T1 cells caused similar increases in number of branch points and complete endothelial networks. VEGF concentration was quantified in CM (ELISA) from agonist experiments; we observed a 2-fold and 2.5-fold increase in VEGF release from NPY and Y5R agonist treated 4T1 cells respectively. Overall these data highlight a novel mechanism by which NPY may promote breast cancer progression, and further implicate a pathological role of the NPY Y5R.     

The hybridization of glyceraldehyde 3-phosphate dehydrogenases from rabbit muscle and yeast. Kinetics and thermodynamics of the reaction and isolation of the hybrid

A kinetic and thermodynamic study was made of the formation of the hybrid (R(2)Y(2)) glyceraldehyde 3-phosphate dehydrogenase from the yeast (Y(4)) and rabbit (R(4)) enzymes. The values of the thermodynamic parameters for the equilibrium between R(4), Y(4) and R(2)Y(2) suggest that the R(2)-R(2) and Y(2)-Y(2) interactions are similar. However, the failure to observe the RY(3) and R(3)Y hybrids is interpreted in terms of differences at the interfaces of the R-R and Y-Y interactions (the glyceraldehyde 3-phosphate dehydrogenase molecule being regarded as a dimer of dimers). The kinetics of formation of the R(2)Y(2) hybrid were studied and a model was proposed to account for the results. Best-fit values for the rate constants of the individual steps were evaluated by computer simulation, and the rate-limiting steps were identified as the dissociation of tetramers to dimers. It is proposed that the cleavage plane for dissociation of the tetramers corresponds to the region of low electron density through the centre of the molecule in the X-ray-crystallographic structure for human glyceraldehyde 3-phosphate dehydrogenase (Watson et al., 1972), which is probably the plane containing the Q and R axes in the lobster enzyme (Buehner et al., 1974). The R(2)Y(2) hybrid was isolated in milligram amounts by ion-exchange chromatography and its rate of reversion to the native enzyme was shown to be consistent with the kinetic model proposed from the hybrid-formation experiments.     

On the Difference Between Elachanthemum Y. Ling et Y. R. Ling and Stilpnolepis Krasch.

It is quite unreasonable reducing Elachanthemum Y. Ling et Y. R. Ling into Stilprolepis Krasch. and it is so wrong idea attributing the achenes and cupuliform corolla (as a matter of fact, the cupuliform corolla is originally from the Stilpnolepis Krasch., not from Elachanthemum Y. Ling et Y. R. Ling) of Elachanthemum Y. Ling et Y. R. Ling to “earlier Development” in the paper published in Act. Phytotax. Sin. 23(6): 470-472. 1985. In Elachanthemum Y. Ling et Y. R. Ling, bracts of capitula herbaceous, obviously floccose on the abaxial surface and membranaceous only on the margin, corolla of bisexual florets tubular, achenes oblique, obovoid, and the exine of pollen grains minutespinulate, but in Stilpnolepis Krasch., on the contrary, whole bracts membranaceous, glabrous, corolla of hermaphrodite florets cupuliform or campanulate, achenes long-clavate or fuciform and the exine of pollen grains remarkably spiny.     

A novel copper(II) coordination at His186 in full-length murine prion protein

To explore Cu(II) ion coordination by His¹⁸⁶ in the C-terminal domain of full-length prion protein (moPrP), we utilized the magnetic dipolar interaction between a paramagnetic metal, Cu(II) ion, and a spin probe introduced in the neighborhood of the postulated binding site by the spin labeling technique (SDSL technique). Six moPrP mutants, moPrP(D143C), moPrP(Y148C), moPrP(E151C), moPrP(Y156C), moPrP(T189C), and moPrP(Y156C,H186A), were reacted with a methane thiosulfonate spin probe and a nitroxide residue (R1) was created in the binding site of each one. Line broadening of the ESR spectra was induced in the presence of Cu(II) ions in moPrP(Y148R1), moPrP(Y151R1), moPrP(Y156R1), and moPrP(T189R1) but not moPrP(D143R1). This line broadening indicated the presence of electron-electron dipolar interaction between Cu(II) and the nitroxide spin probe, suggesting that each interspin distance was within 20 Å. The interspin distance ranges between Cu(II) and the spin probes of moPrP(Y148R1), moPrP(Y151R1), moPrP(Y156R1), and moPrP(T189R1) were estimated to be 12.1 Å, 18.1 Å, 10.7 Å, and 8.4 Å, respectively. In moPrP(Y156R1,H186A), line broadening between Cu(II) and the spin probe was not observed. These results suggest that a novel Cu(II) binding site is involved in His186 in the Helix2 region of the C-terminal domain of moPrP^C.     

Mechanism of the PII-activated phosphatase activity of Escherichia coli NRII (NtrB): how the different domains of NRII collaborate to act as a phosphatase

The phosphatase activity of the homodimeric NRII protein of Escherichia coli is activated by the PII protein and requires all three domains of NRII. Mutations in the N-terminal domain (L16R), central domain (A129T), C-terminal domain PII-binding site (S227R), and C-terminal domain ATP-lid (Y302N) of NRII result in diminished phosphatase activity. Here, we used heterodimers formed in vitro from purified homodimeric proteins to study the phosphatase activity. A129T, S227R, and Y302N mutant subunits and A129T/S227R, A129T/Y302N, and S227R/Y302N double-mutant subunits formed stable heterodimers and were amenable to analysis; heterodimers containing these mutant subunits in various combinations were formed and their activities assessed. Complementation of the PII-activated phosphatase activity was observed in heterodimers containing S227R and Y302N subunits and in heterodimers containing A129T and Y302N subunits, but not in heterodimers containing A129T and S227R subunits. Complementation of the PII-activated phosphatase activity was also observed in heterodimers containing A129T/S227R and Y302N subunits, but not in heterodimers containing A129T/Y302N and S227R subunits. Finally, inclusion of an S227R/Y302N subunit in a heterodimer with a subunit having wild-type phosphatase activity resulted in a dramatic decrease in phosphatase activity, while inclusion of an A129T/S227R subunit did not. These results suggest that the phosphatase activity of NRII requires the collaboration of the PII-binding site from one subunit of the dimer, the central domain from the same subunit, and the ATP-lid from the opposing subunit, in addition to the undefined N-terminal domain requirement(s).     

Up-regulation of neuropeptide Y Y4 receptor mRNA expression in the brainstem of refed rats following 48 h of food deprivation: effect of leptin

Neuropeptide Y (NPY) Y4 receptor (Y4R) in rat brainstem has been implicated in the signaling of satiety. In this study, we investigated the effects of leptin, and refeeding-induced satiety on Y4R mRNA expression in rat brainstem. Y4R receptor-specific primers were used to amplify the mRNA obtained from hypothalamus and brainstem utilizing conventional RT-PCR and quantitative real-time RT-PCR. No PCR product for Y4R was obtained from entire hypothalamic mRNA. Real-time RT-PCR showed a significant two-fold increase in the relative quantity of Y4R mRNA in brainstem of refed rats in comparison to food deprived or ad lib fed rats. Consistently, plasma leptin level was elevated in refed rats in comparison to food deprived rats. Similarly, leptin-treated rats exhibited a significant increase in Y4R mRNA in brainstem as compared to saline-injected rats. Plasma leptin was significantly elevated in leptin-treated rats. These results suggest that refeeding stimulates the expression of Y4R gene in the brainstem and that leptin may be one of the peripheral factors involved in this anorectic signaling mechanism.     

Hybrid formation of rabbit and rat hepatic glutathione S-transferases

1. A reconstitution experiment resulted in the formation of new proteins between limited combinations of rat and rabbit hepatic glutathione S-transferases: AA(subunit composition: YcYc) and R3b(Y3Y3), Lig(YaYa) and R3b(Y3Y3), and A(Yb1Yb1) and R2(Y2Y2). 2. It was demonstrated that the new protein formed between R2 and A had the subunit composition of Y2Yb1, suggesting a hybrid of rabbit (R2) and rat isozyme (A). 3. This hybrid protein showed intermediate spec. acts between those of R2 and A when either 1-chloro-2,4-dinitrobenzene (CDNB) or 1,2-dichloro-4-nitrobenzene (DCNB) was employed as the substrate.     

Generation of the R2 subunit of ribonucleotide reductase by intein chemistry: insertion of 3-nitrotyrosine at residue 356 as a probe of the radical initiation process

Escherichia coli ribonucleotide reductase (RNR) catalyzes the conversion of nucleoside diphosphates to deoxynucleoside diphosphates. The enzyme is composed of two subunits: R1 and R2. R1 contains the active site for nucleotide reduction and the allosteric effector sites that regulate the specificity and turnover rate. R2 contains the diferric-tyrosyl (Y(*)) radical cofactor that initiates nucleotide reduction by a putative long-range proton-coupled electron transfer (PCET) pathway over 35 A. This pathway is thought to involve specific amino acid radical intermediates (Y122 to W48 to Y356 within R2 to Y731 to Y730 to C439 within R1). In an effort to study radical initiation, R2 (375 residues) has been synthesized semisynthetically. R2 (residues 1-353), attached to an intein and a chitin binding domain, was constructed, and the protein was expressed (construct 1). This construct was then incubated with Fe(2+) and O(2) to generate the diferric-Y(*) cofactor, and the resulting protein was purified using a chitin affinity column. Incubation of construct 1 with 2-mercaptoethanesulfonic acid (MESNA) resulted in the MESNA thioester of R2 (1-353) (construct 2). A peptide containing residues 354-375 of R2 was generated using solid-phase peptide synthesis where 354, a serine in the wild-type (wt) R2, was replaced by a cysteine. Construct 2 and this peptide were ligated, and the resulting full-length R2 was separated from truncated R2 by anion-exchange chromatography. The purified protein had a specific activity of 350 nmol min(-1) mg(-1), identical to the same protein generated by site-directed mutagenesis when normalized for Y(*). As a first step in studying the radical initiation by PCET, R2 was synthesized with Y356 replaced by 3-nitrotyrosine (NO(2)Y). The protein is inactive (specific activity 1 x 10(-4) that of wt-R2), which permitted a determination of the pK(a) of the NO(2)Y in the R1/R2 complex in the presence of substrate and effectors. Under all conditions, the pK(a) was minimally perturbed. This has important mechanistic implications for the radical initiation process.     

An RGD sequence in the P2Y(2) receptor interacts with alpha(V)beta(3) integrins and is required for G(o)-mediated signal transduction

The P2Y(2) nucleotide receptor (P2Y(2)R) contains the integrin-binding domain arginine-glycine-aspartic acid (RGD) in its first extracellular loop, raising the possibility that this G protein-coupled receptor interacts directly with an integrin. Binding of a peptide corresponding to the first extracellular loop of the P2Y(2)R to K562 erythroleukemia cells was inhibited by antibodies against alpha(V)beta(3)/beta(5) integrins and the integrin-associated thrombospondin receptor, CD47. Immunofluorescence of cells transfected with epitope-tagged P2Y(2)Rs indicated that alpha(V) integrins colocalized 10-fold better with the wild-type P2Y(2)R than with a mutant P2Y(2)R in which the RGD sequence was replaced with RGE. Compared with the wild-type P2Y(2)R, the RGE mutant required 1,000-fold higher agonist concentrations to phosphorylate focal adhesion kinase, activate extracellular signal-regulated kinases, and initiate the PLC-dependent mobilization of intracellular Ca(2+). Furthermore, an anti-alpha(V) integrin antibody partially inhibited these signaling events mediated by the wild-type P2Y(2)R. Pertussis toxin, an inhibitor of G(i/o) proteins, partially inhibited Ca(2+) mobilization mediated by the wild-type P2Y(2)R, but not by the RGE mutant, suggesting that the RGD sequence is required for P2Y(2)R-mediated activation of G(o), but not G(q). Since CD47 has been shown to associate directly with G(i/o) family proteins, these results suggest that interactions between P2Y(2)Rs, integrins, and CD47 may be important for coupling the P2Y(2)R to G(o).     

Mutations in arrestin-3 differentially affect binding to neuropeptide Y receptor subtypes

Based on the identification of residues that determine receptor selectivity in arrestins and the phylogenetic analysis of the arrestin (arr) family, we introduced fifteen mutations of receptor-discriminator residues in arr-3, which were identified previously using mutagenesis, in vitro binding, and BRET-based recruitment assay in intact cells. The effects of these mutations were tested using neuropeptide Y receptors Y1R and Y2R. NPY-elicited arr-3 recruitment to Y1R was not affected by these mutations, or even alanine substitution of all ten residues (arr-3-NCA), which prevented arr-3 binding to other receptors tested so far. However, NCA and two other mutations prevented agonist-independent arr-3 pre-docking to Y1R. In contrast, eight out of 15 mutations significantly reduced agonist-dependent arr-3 recruitment to Y2R. NCA eliminated arr-3 binding to active Y2R, whereas Tyr239Thr reduced it ~ 7-fold. Thus, manipulation of key residues on the receptor-binding surface generates arr-3 with high preference for Y1R over Y2R. Several mutations differentially affect arr-3 pre-docking and agonist-induced recruitment. Thus, arr-3 recruitment to the receptor involves several mechanistically distinct steps. Targeted mutagenesis can fine-tune arrestins directing them to specific receptors and particular activation states of the same receptor.