bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photodamage to Pigment in the Photosystem II Reaction Center D1/D2/Cytochrome b559 Complex
Authors: Liu Shuang , Dong Feng‐Qin , Tang Chong‐Qin , Kuang Ting‐Yun , Li Liang‐Bi , Liu Yu‐Long 
Published: July 2006

AbstractStrong light (800 μmol photons/m2 per s)‐induced bleaching of the pigment in the isolated photosystem II reaction center (PSII RC) under aerobic conditions (in the absence of electron donors or acceptors) was studied using high‐pressure liquid chromatography (HPLC), absorption spectra, 77K fluorescence spectra and resonance Raman spectra. Changes in pigment composition of the PSII RC as determined by HPLC after light treatment were as follows: with increasing illumination time chlorophyll (Chl) a and β‐carotene (β‐car) content decreased. However, decreases in pheophytin (Pheo) could not be observed because of the mixture of the Pheo formed by degraded chlorophyll possibly. On the basis of absorption spectra, it was determined that, with a short time of illumination, the initial bleaching occurred maximally at 680 nm but that with increasing illumination time there was a blue shift to 678 nm. It was suggested that P680 was destroyed initially, followed by the accessory chlorophyll. The activity of P680 was almost lost after 10 min light treatment. Moreover, the bleaching of Pheo and β‐car was observed at the beginning of illumination. After illumination, the fluorescence emission intensity changed and the fluorescence maximum blue shifted, showing that energy transfer was disturbed. Resonance Raman spectra of the PSII RC excited at 488.0 and 514.5 nm showed four main bands, peaking at 1 527 cm‐1 (v1), 1 159 cm‐1 (v2), 1 006 cm‐1 (v3), 966 cm‐1 (v4) for 488.0 nm excitation and 1 525 cm‐1 (v1), 1 159 cm‐1 (v2), 1 007 cm‐1 (v3), 968 cm‐1 (v4) for 514.5 nm excitation. It was confirmed that two spectroscopically different β‐car molecules exist in the PSII RC. After light treatment for 20 min, band positions and bandwidths were unchanged. This indicates that carotenoid configuration is not the parameter that regulates photoprotection in the PSII RC.(Managing editor: Ping He)
Climatic Control on Forests and Tree Species Distribution in the Forest Region of Northeast China
Authors: Wang Xiang‐Ping , Tang Zhi‐Yao , Fang Jing‐Yun 
Published: July 2006

AbstractNorth‐east (NE) China covers considerable climatic gradients and all major forests types of NE Asia. In the present study, 10 major forest types across the forest region of NE China were sampled to investigate forest distribution in relation to climate. Canonical correspondence analysis (CCA) revealed that growing season precipitation and energy availability were primary climatic factors for the overall forest pattern of NE China, accounting for 66% of the explanatory power of CCA. Conversely, annual precipitation and winter coldness had minor effects. Generalized additive models revealed that tree species responded to climatic gradients differently and showed three types of response curve: (i) monotonous decline; (ii) monotonous increase; and (iii) a unimodal pattern. Furthermore, tree species showed remarkable differences in limiting climatic factors for their distribution. The power of climate in explaining species distribution declined significantly with decreasing species dominance, suggesting that the distribution of dominant species was primarily controlled by climate, whereas that of subordinate species was more affected by competition from other species.(Managing editor: Ya‐Qin Han)
Variation of Soil Nutrition in a Fagus engleriana Seem.‐ Cyclobalanopsis oxyodon Oerst. Community Over a Small Scale in the Shennongjia Area, China
Authors: Zhang Mi , Xie Zong‐Qiang , Xiong Gao‐Ming , Zhang Jin‐Tun 
Published: July 2006

AbstractSoil nutrition is a key factor influencing species composition in a community, but it has clearly scale‐dependent heterogeneity. In the present study, geostatistics methods and canonical correspondence analysis (CCA) were used to detect: (i) the variation range of soil spatial heterogeneity; (ii) the influence of topographic factors on the distribution of soil nutrition; and (iii) the relationships between soil chemical properties and species in the community. In all, 23 soil variables were measured, including total N and organic C, Al, Ba, Ca, Cr, Cu, Fe, Ga, Li, Mg, Mn, Na, NH4‐N, Ni, NO3‐N, Pb, pH, P, Sr, Ti, V, and Zn. Semi‐variograms of these variables were calculated and mapped. All indices showed autocorrelations, with ranges between 29 and 200 m. When the sample method was larger than these distances, spatial autocorrelations were avoided. The distribution patterns of Ca, Cr, Ga, K, Mg, organic C, P, Pb, and pH, and total N were related to the microtopography and the distribution of these compounds was clumped in water catchments area. The CCA method was used to investigate the relationship between plant species and soil properties in this community. Fagus engleriana Seem., Lindera obtusiloba Bl. Mus., and Acer griseum (Franch.) Pax were correlated with organic C, available N, and P.(Managing editor: Ya‐Qin Han)
Effect of Osmotic Stress in Early Stages of Ontogenesis on Root Respiration, Growth, Sugar Content, and Cell Injury in Maize Seedlings Differing in Drought Sensitivity
Authors: Kolarovič Lukáš , Luxová Miroslava , Valentovič Peter 
Published: July 2006

AbstractCultivars of maize (Zea mays L.) with different sensitivity to drought were exposed to 0.3 mol/L sorbitol (‐1.4 MPa water potential) for 24 h. Exposure to water deficiency significantly reduced the growth of both shoots (coleoptile and hypocotyl) and roots. Shoot growth was inhibited more than the growth of roots. Osmotic stress enhanced accumulation of soluble sugars. Electrolyte leakage, a cell injury index, was slightly increased after 0.3 mol/L sorbitol. Respiration was measured in the presence and absence of 2,6‐dichlorophenol indophenol. 2, 6‐Dichlorophenol indophenol did not influence respiration rates, because statistically equal results were observed under both conditions. Total respiration (vT) decreased after osmoticum treatment. There were no significant differences in the vT among the cultivars analysed. The decrease in vT was caused by a decline in the activities and capacities of both cytochrome (vcyt, Vcyt) and alternative pathway (valt, Valt) of respiration. A high residual respiration (vres) was observed, up to 27% of total uninhibited respiration. The result of uncoupler use clearly indicated that coupling was maintained after 24 h of osmotic stress. The recovery of the respiration rate was comparable with that of non‐stressed control rates. According to these observations, no possible mitochondrial damage is expected. Water deficiency did not induce a stimulation of the alternative oxidase, so we assume that the stimulation of the alternative pathway is not related to drought stress resistance; rather, the function of the alternative pathway is to balance carbon metabolism and electron transport in a response to a changing environment.(Managing editor: Ping He)
Epidemiology of Human Metapneumovirus
Authors: Kahn Jeffrey S. 
Published: July 2006

SUMMARY
Since the discovery of human metapneumovirus (hMPV) in 2001, the virus has been identified worldwide. hMPV is a common respiratory pathogen, particularly in infants and young children. The virus is associated with both upper and lower respiratory tract infections and may be a trigger for asthma. At least two major genotypes of hMPV circulate during community outbreaks. Whether these genotypes represent distinct serotypes remains controversial. The major challenges faced by the medical and scientific communities are the understanding of the pathogenesis of hMPV disease and the development of a safe and effective vaccine to protect against infection and disease caused by this newly recognized respiratory virus.
Bats: Important Reservoir Hosts of Emerging Viruses
Authors: Calisher Charles H. , Childs James E. , Field Hume E. , Holmes Kathryn V. , Schountz Tony 
Published: July 2006

SUMMARYBats (order Chiroptera, suborders Megachiroptera [“flying foxes”] and Microchiroptera) are abundant, diverse, and geographically widespread. These mammals provide us with resources, but their importance is minimized and many of their populations and species are at risk, even threatened or endangered. Some of their characteristics (food choices, colonial or solitary nature, population structure, ability to fly, seasonal migration and daily movement patterns, torpor and hibernation, life span, roosting behaviors, ability to echolocate, virus susceptibility) make them exquisitely suitable hosts of viruses and other disease agents. Bats of certain species are well recognized as being capable of transmitting rabies virus, but recent observations of outbreaks and epidemics of newly recognized human and livestock diseases caused by viruses transmitted by various megachiropteran and microchiropteran bats have drawn attention anew to these remarkable mammals. This paper summarizes information regarding chiropteran characteristics and information regarding 66 viruses that have been isolated from bats. From these summaries, it is clear that we do not know enough about bat biology; we are doing too little in terms of bat conservation; and there remain a multitude of questions regarding the role of bats in disease emergence.
Application of Molecular Techniques to the Study of Hospital Infection
Authors: Singh Aparajita , Goering Richard V. , Simjee Shabbir , Foley Steven L. , Zervos Marcus J. 
Published: July 2006

SUMMARY
Nosocomial infections are an important source of morbidity and mortality in hospital settings, afflicting an estimated 2 million patients in United States each year. This number represents up to 5% of hospitalized patients and results in an estimated 88,000 deaths and 4.5 billion dollars in excess health care costs. Increasingly, hospital-acquired infections with multidrug-resistant pathogens represent a major problem in patients. Understanding pathogen relatedness is essential for determining the epidemiology of nosocomial infections and aiding in the design of rational pathogen control methods. The role of pathogen typing is to determine whether epidemiologically related isolates are also genetically related. To determine molecular relatedness of isolates for epidemiologic investigation, new technologies based on DNA, or molecular analysis, are methods of choice. These DNA-based molecular methodologies include pulsed-field gel electrophoresis (PFGE), PCR-based typing methods, and multilocus sequence analysis. Establishing clonality of pathogens can aid in the identification of the source (environmental or personnel) of organisms, distinguish infectious from noninfectious strains, and distinguish relapse from reinfection. The integration of molecular typing with conventional hospital epidemiologic surveillance has been proven to be cost-effective due to the associated reduction in the number of nosocomial infections. Cost-effectiveness is maximized through the collaboration of the laboratory, through epidemiologic typing, and the infection control department during epidemiologic investigations.
Pathogenesis ofHelicobacter pyloriInfection
Authors: Kusters Johannes G. , van Vliet Arnoud H. M. , Kuipers Ernst J. 
Published: July 2006

SUMMARYHelicobacter pyloriis the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong.H. pyloriinfection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis ofH. pylori.
Tuberculosis Chemotherapy: the Influence of Bacillary Stress and Damage Response Pathways on Drug Efficacy
Authors: Warner Digby F. , Mizrahi Valerie 
Published: July 2006

SUMMARY

The global tuberculosis (TB) control effort is focused on interrupting transmission of the causative agent,
Mycobacterium tuberculosis
, through chemotherapeutic intervention in active infectious disease. The insufficiency of this approach is manifest in the inexorable annual increase in TB infection and mortality rates and the emergence of multidrug-resistant isolates. Critically, the limited efficacy of the current frontline anti-TB drug combination suggests that heterogeneity of host and bacillary physiologies might impair drug activity. This review explores the possibility that strategies enabling adaptation of
M. tuberculosis
to hostile in vivo conditions might contribute to the subversion of anti-TB chemotherapy. In particular, evidence that infecting bacilli are exposed to environmental and host immune-mediated DNA-damaging insults suggests a role for error-prone DNA repair synthesis in the generation of chromosomally encoded antibiotic resistance mutations. The failure of frontline anti-TB drugs to sterilize a population of susceptible bacilli is independent of genetic resistance, however, and instead implies the operation of alternative tolerance mechanisms. Specifically, it is proposed that the emergence of persister subpopulations might depend on the switch to an altered metabolic state mediated by the stringent response alarmone, (p)ppGpp, possibly involving some or all of the many toxin-antitoxin modules identified in the
M. tuberculosis
genome.
Optical Resolution of Amino Acid Esters by N-Protected Aspartylphenylalanine Esters
Authors: Oyama Kiyotaka , Itoh Mikio , Nonaka Yuji 
Published: July 2006

Abstract
A new method was studied for optical resolution of racemic amino acid esters by using, as resolving agents, N-protected l-α-aspartyl-l-phenylalanine alkyl esters, typically, N-benzyloxycarbonyl-l-α-aspartyl-l-phenylalanine methyl ester, the precursor to the synthetic sweetener aspartame. Thus, when the dipeptide and racemic amino acid ester were mixed in solvents, precipitation took place by formation of salt preferentially with d-amino acid ester to effect the optical resolution.
Multiple Electrostatic Interaction of Polycationic Chitosan Oilgomers with Nucleic Acids: Polyamine Promoted Stabilization of the A-Form of RNA and DNA in Aqueous Solutions
Authors: Motomura Tadahiro , Aoyama Yasuhiro 
Published: July 2006

Abstract
Polycationic chitosan oligomers 1n (n = 2–6), i.e., β-1,4-linked glucosamine oligomers, were found to bind to nucleic acids in aqueous solutions at pH 7.2 via multiple electrostatic interaction. The binding of trimer and higher homologues (1n, n ≥ 3) is especially efficient owing to an (at least) three-point simultaneous ammonio phosphate formation. Upon binding of 1n (n ≥ 3), the double-helical structure in the A-form of poly(A)·poly(U), a synthetic RNA, is significantly stabilized as revealed by enhancement of its helix-to-coil transition (melting) temperatures. Upon binding of 1n (n ≥ 3), calf thymus DNA in the B-form undergoes a drastic conformational change to the A-form, as revealed by circular dichrosim spectroscopy. In marked contrast, chitosan dimer (12) and diamine and monoamine references only induce the B-to-C transition within the B-family. The significance of the multiple electrostatic interaction and the cooperativity of the glucosamine residues in 1n are discussed.
Abnormal Diels–Alder Reaction of 5-Alkoxyoxazoles with Tetracyanoethylene and X-Ray Crystal Structure of an Adduct
Authors: Ibata Toshikazu , Isogami Yasushi , Nakawa Hiroyuki , Tamura Hatsue , Suga Hiroyuki , Shi Xiaolan , Fujieda Hiroki 
Published: July 2006

Abstract
The reaction of 2-alkyl- or 2-aryl-substituted 5-methoxy-4-(p-nitrophenyl)oxazoles with tetracyanoethylene gave methyl esters of 5-substituted 3,3,4,4-tetracyano-2-(p-nitrophenyl)-3,4-dihydro-2H-pyrrole-2-carboxylic acids as formal [3 + 2] cycloadducts through oxazole ring opening. Zwitterionic mechanisms were proposed on the basis of the solvent effect on the reaction. The molecular structure of 2-isopropyl-substituted product was determined by means of X-ray crystallography. Crystals of the cycloadduct are orthorhombic with space group Pcab having unit-cell dimensions of a = 17.998 (2), b = 27.188 (6), c = 15.833 (3) Å, and Z = 16, which contains two crystallographically independent molecules. The final R value is 0.070 for 4629 observed reflections.
Tetrakis(thiolato)nickelate(II), [Ni(RS)4]2−; Ligand Dissociation and Electronic Spectra
Authors: Yamamura Takeshi , Arai Hiroki 
Published: July 2006

Abstract
The dissociation feature of nickel complexes of arenethiolates, [Ni(RS)4]2− (RSH = p-CH3C6H4SH, m-CH3C6H4SH, C6H5SH, p-ClC6H4SH, p-NO2C6H4SH) in DMSO was studied by spectrophotometric method. 1H NMR experiment on [Ni(RS)4]2− (RSH = 2,4,6-trideuteriobenzenethiol) in DMSO-d6 revealed that this system obeys the following equilibrium scheme generating the diamagnetic nickel species, [Ni(RS)3(solv)]− and [Ni(RS)2(solv)2] (solv = solvent ligand). Dissociation constants Kd, Ke, and Kd′ were calculated from the NMR data.

Intrinsic UV-vis. absorption spectra of [Ni(RS)n(solv)4−n](n−2)− (RS− = C6H5S−, n = 2, 3, 4) were derived from the least squares fitting analyses of the absorption change data obtained under different concentrations of RS−. The absorption spectrum of [Ni(t-C4H9S)4]2− was also measured in solid state. Crystal field calculations for both [Ni(C6H5S)4]2− and [Ni(t-C4H9S)4]2− were examined. The results were compared with those of [NiX4]2− (X− = Cl−, Br−, I−), as well as the nickel exchanged aspartate transcarbamoylase. The structures of [Ni(RS)n(solv)4−n](n−2)− were discussed.
Preparation and Characterization of trans- and cis-Halogenobis(vicinal-dioximato)nitrosylruthenium(III) Complexes
Authors: Fukuchi Takashi 
Published: July 2006

Abstract
The complexes of nitrosylruthenium(III) with vicinal-dioximato ligands, [Ru(vic-dioximato)2X(NO)] (vic-dioximato = 2,3-butanedione dioximato (Hdmo), 1,2-diphenylethanedione dioximato (Hdpo), or 1,2-cyclohexanedione dioximato (Hcho); X = Cl, Br, or I), and the complexes of carbonylruthenium(II) with Hdpo, [Ru(Hdpo)2(CO)L] (L = H2O or pyridine), were synthesized. The results of the 1H, 13C NMR, and IR spectra showed that the trans and cis isomers were present in some of the nitrosylruthenium(III) complexes.
Kinetics and Mechanisms of Photo-Induced Reduction of Iodine by Monoamine-N-polycarboxylate Ions in an Aqueous Solution
Authors: Kimura Masaru , Nakazawa Fumiko , Tsukahara Keiichi 
Published: July 2006

Abstract
The photo-induced reduction kinetics of iodine by monoamine-N-polycarboxylate ions, such as nitrilotriacetic acid (H3nta), iminodiacetic acid (H2ida), 2-hydroxyethyliminodiacetic acid (H2hida), as well as o-, m-, and p-isomers of N-(carboxyphenyl)iminodiacetic acid (H3cpida), were made in an aqueous solution containing iodide ions in excess over the pH range 1.6–7.6; the photo-induced reductions of iodine by triethylamine (TEA) and tris(2-hydroxyethyl)amine (TEOA) were also studied. The reactive species are a I2−• radical anion, produced in the primary photoreaction, and a fully deprotonated species of monoamine-N-polycarboxylate, TEOA, or TEA. Both hydrogen ion and complex-forming metal ions, such as copper(II) and zinc(II), were strong inhibitors for all of the reactions investigated. The role of the lone electron pair on the amine nitrogen is discussed.
Molecular Structures of HT-[MM′Cl2(μ-Me2Ppy)2] (MM′ = Pd2, PdPt, and Pt2; Me2Ppy = 2-(Dimethylphosphino)pyridine) and HT-[Pd2Cl2(μ-Ph2Ppy)2] (Ph2Ppy = 2-(Diphenylphosphino)pyridine)
Authors: Suzuki Takayoshi , Iitaka Naoyuki , Kurachi Saeko , Kita Masakazu , Kashiwabara Kazuo , Ohba Shigeru , Fujita Junnosuke 
Published: July 2006

Abstract
Crystal structures of Pd(I) and Pt(I) dinuclear complexes, [MM′Cl2(μ-Me2Ppy)2] (MM′ = Pd2 (1), PdPt (2), and Pt2 (3)) and [Pd2Cl2(μ-Ph2Ppy)2] (4), were determined by the single crystal X-ray diffraction method. Crystal data and final R values are: 1, triclinic, , a = 10.019(2), b = 10.902(2), c = 9.062(1) Å, α = 97.75(2), β = 102.45(2), γ = 82.64(2)°, V = 952.7(3) Å3, Z = 2, and R = 0.047; 2, monoclinic, P21/n, a = 16.532(2), b = 19.205(3), c = 13.260(2) Å, β = 93.86(2)°, V = 4200(1) Å3, Z = 8, and R = 0.043; 3, monoclinic, P21/n, a = 16.515(5), b = 19.095(10), c = 13.233(4) Å, β = 93.15(3)°, V = 4167(3) Å3, Z = 8, and R = 0.047; 4, monoclinic, C2/c, a = 30.505(4), b = 17.896(2), c = 12.983(1) Å, β = 98.52(1)°, V = 7009(1) Å3, Z = 8, and R = 0.041. All of the complexes were found to be the head-to-tail isomer of a side-by-side type dinuclear structure. The metal–metal bond distances of 2.584(1) Å in 1, 2.561(1) Å in 2, 2.573(1) Å in 3, and 2.594(1) Å in 4 are relatively short compared with those in the analogous dinuclear complexes bridged by diphosphine ligands. All of the M–P, M–N, and M–Cl distances in Me2Ppy complexes become shortened in the order of the Pd2 &gt; PdPt &gt; Pt2 complexes.
57Fe Mössbauer Spectra, Crystal Structure, and Spin-Crossover Behavior of [Fe(mbpN)(lut)]BPh4
Authors: Maeda Yonezo , Noda Yosuke , Oshio Hiroki , Takashima Yoshimasa 
Published: July 2006

Abstract
A new spin-crossover complex [Fe(mbpN)(lut)]BPh4 (H2mbpN; N,N′-bis[(2-hydroxy-5-methylphenyl)phenylmethylene]-4-azaheptane-1,7-diamine and lut; 3,4-dimethylpyridine) is reported. The structure of this complex was determined at 293 K, and the temperature dependence of the 57Fe Mössbauer spectra and magnetic susceptibilities was examined. The complex undergoes a faster spin-state interconversion than the lifetime of the 57Fe excited state (1 × 10−7 s). More importantly, it has been found that the quadrupole splittings of the complex show the lowest value at intermediate spin-state transformations. This behavior is illustrated by a model in which the electric field gradient of the high-spin state has the opposite sign with that of the low-spin state. The monoclinic crystal of [Fe(mbpN)(lut)]BPh4 is of space group P21/a, with a = 14.664(5), b = 37.269(4), c = 10.061(5) Å, β = 90.97(3)°, Z = 4, and refinement to R = 0.079 and Rw = 0.084. The bond distances of Fe–Oav (1.912(5) Å), Fe–Nimineav (2.080(6) Å), Fe–Namine (2.141(6) Å), and Fe–Npyridine (2.145(6) Å) are close to the expected values for the high-spin species.
Oxidation of Phosphatidylcholine Liposomes in Aqueous Dispersions Induced by Copper and Iron
Authors: Yoshida Yasukazu , Niki Etsuo 
Published: July 2006

Abstract
The oxidations of phosphatidylcholine liposomes in aqueous dispersions induced by copper and iron have been studied aiming specifically at elucidating the action of copper ion in the chain initiation of the oxidation of liposomal membranes. Both copper(II) and iron(III) ions induced steady oxidations and the addition of t-butyl hydroperoxide enhanced the rate of oxidation. The reduction of hydroperoxides present initially in the liposomes by triphenylphosphine markedly reduced the rate of oxidation. The rate of oxidation induced by copper(II) ion was proportional to the first power of phosphatidylcholine concentration and to the half power of both copper(II) ion and t-butyl hydroperoxide concentrations, suggesting that the oxidation was initiated by the oxygen radicals formed in the decomposition of hydroperoxide by copper(II) and copper(I) ions. The anionic dipalmitoylphosphatidic acid added into the liposomes enhanced the rate of oxidation induced by metal ions, whereas the addition of cationic octadecylamine showed little effect on the rate of oxidation.