bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phylogeny of the families of Scarabaeoidea (Coleoptera) based on characters of the hindwing articulation, hindwing base and wing venation
Authors: BROWNE D. J. , SCHOLTZ C. H. 
Published: January 2008

AbstractA study is made of the articulation and base of the hindwings of Scarabaeoidea. The survey is based on an examination of over 250 genera from thirteen scarabaeoid families. Relationships among all families of Scarabaeoidea are examined here for the first time. The reconstructed phylogeny shows that the Scarabaeoidea is comprised of three major lineages: a glaresid, passalid and scarabaeid lineage. The glaresid lineage consists only of the Glaresidae. The passalid lineage is comprised of two major lines: a passalid line (containing Passalidae, Lucanidae, Diphyllostomatidae, Glaphyridae, Trogidae, Bolboceratidae and Pleocomidae) and a geotrupid line (containing Geotrupidae, Ochodaeidae, Ceratocanthidae and Hybosoridae). The scarabaeid lineage contains those taxa traditionally included within the Scarabaeidae (Aegialiinae, Aulonocneminae, Aphodiinae, Scarabaeinae, Orphninae, Melolonthinae,Acoma, Chasmatopterinae, Hopliinae, Oncerinae, Rutelinae, Dynastinae, Trichiinae, Cetoniinae and Valginae). Additional evidence, from other character suites, supporting this breakdown of the Scarabaeoidea is given.
XANTHOPHYLLS AND THE HILL REACTION*
Authors: Yamamoto H. Y. , Chichester C. O. , Nakayama T. O. M. 
Published: January 2008

SummaryThe incorporation of oxygen from water enriched in H218O into the leaf xanthophylls during the Hill reaction was investigated. No enrichment was detectable in violaxanthin and neoxanthin. A low incorporation into lutein, which was not dependent on the Hill reaction, was observed.The results indicate that the epoxy pigments do not function as an oxygen transport system in photosynthesis under the conditions of these experiments.
PATTERNS OF NUCLEIC ACID AND PROTEIN SYNTHESIS DURING MODIFICATION OF LETHAL ULTRAVIOLET LESION
Authors: Kos E. , Drakulić M. , Brdar B. 
Published: January 2008

Abstract— We have shown previously that the viability of E. coli B.U.‐ and E. coli B. try‐could be restored after u.v.‐irradiation if post‐irradiation incubation took place in the presence of chloramphenicol or in the absence of an essential metabolite. By way of contrast, the viability of the u.v.‐irradiated E. coli K.12 meth‐ decreased rapidly during post‐irradiation incubation in the presence of chloramphenicol or in the absence of methionine. During the study of the biosynthesis of nucleic acids and protein in the above strains we made the following observations.Protein synthesis was permanently inhibited in both amino acid requiring strains during post‐irradiation incubation in the absence of the respective essential metabolite. In E. coli B.U.‐ a slow synthesis of protein could be observed even if post‐irradiation incubation took place in the absence of uracil.DNA synthesis was completely and permanently inhibited in both E. coli B. try‐ and E. coli K.12 meth‐ during post‐irradiation incubation in the absence of the respective essential amino acid. In E. coli B.U.‐, however, DNA synthesis resumed after a prolonged lag even if the bacteria were incubated after u.v.‐irradiation in the absence of uracil.RNA synthesis was completely and permanently inhibited in both E. coli B. mutants, the uracil requiring and the tryptophan requiring, if they were incubated after irradiation in the absence of uracil and tryptophan respectively. In E. coli K.12 meth‐ a small amount of RNA is synthesized during post‐irradiation incubation in the absence of the essential amino acid.
A STUDY OF PHOTOCHEMISTRY OF FLAVINS IN PYRIDINE AND WITH A DONOR*
Authors: Kurtin William E. , Latino Michael A. , Song Pill‐Soon 
Published: January 2008

Abstract— Both anaerobic and aerobic photolysis of riboflavin in pyridine yielded several photoproducts, analogous to the photochemical reaction in aqueous solution. Lumiflavin was also photoreduced in pyridine (an electron donor) without decomposition of the isoall‐oxazine ring Differences in the reactivity of excited singlet and triplet states with respect to formation of photoproducts have been confirmed in pyridine. In the photoreduction of riboflavin by N, N'‐dimethyl‐N‐benzylethylene diamine, an initial rate with a higher relative quantum yield than that of the reaction at a later stage was observed both in water and pyridine. Photolysis in D2O with the donor showed no significant solvent isotope effect. These results strongly suggest that the photolysis of riboflavin in water does not involve the water molecule in the primary photochemical act. A detailed mechanism of flavin photoreaction in water to account for solvent oxygen incorporation into a photoproduct (benzaldehyde) from N, N'‐dimethyl‐N‐benzylethylene diamine has been proposed without involving photochemical splitting of water based on our results and molecular orbital computations.Preliminary results on the kinetics of free radical decay were obtained using an ESR spectrometer and the significance of the results are discussed.
EFFECTS OF HIGH PRESSURE ON PHOTOCHEMICAL REACTION CENTERS FROM RHODOPSEUDOMONAS SPHEROIDES*
Authors: CLAYTON R. K. , DEVAULT D. 
Published: January 2008

Abstract— Photochemical reaction centers from Rhodopseudomonas spheroides were subjected to pressures ranging from 1 to 6000 atm. Optical absorption, fluorescence and photochemical activities were studied under these conditions.Absorption spectra showed bathychromic shifts of the long‐wave bands attributed to bacteriopheophytin and bacteriochlorophyll (the latter as P800 and P870).The quantum efficiency of photochemical oxidation of P870 was diminished at high pressure. The quantum yield of P870 fluorescence showed a parallel decline, as if high pressure introduced a quenching process that competed with both photochemistry and fluorescence. The original efficiencies were largely restored when the pressure was returned to 1 atm.The efficiency of oxidation of mammalian cytochrome c, coupled to the photochemical oxidation of P870 in reaction centers, was lowered by high pressure. This effect was more pronounced than the effect on P870 oxidation, and was irreversible.The kinetics of recovery of P870 following its photochemical oxidation showed effects of high pressure. The main effect was the appearance, at high pressure, of slow recovery suggesting the trapping of electrons. This effect was partly irreversible.
THE SUNBURNING ULTRAVIOLET METER: DESIGN AND PERFORMANCE
Authors: Berger D. S. 
Published: January 2008

Abstract— A meter for measuring the skin sunburn effectiveness of a light source is being used in an extensive network to provide solar data for correlation to skin cancer incidence. The solar radiation measured also affects a wide variety of organisms. The intensity of this band of radiation is also strongly affected by ozone concentration so that the output correlates with ozone thickness.The meter spectral response is essentially the excitation spectrum of magnesium tungstate phosphor which is similar to the erythema action spectrum (EAS). In addition to the waterproofed, dose reading embodiment, a cheaper, easily transportable, batteryless, intensity reading meter with the same spectral response has been developed.The deviation of any sunburn meter from the ideal erythema action spectrum can be calculated by convolution of a series of solar spectra against each of the two response spectra. Plotting the change in output against the change in input results in straight lines. Either log‐log coordinates are required, or, as is done here, decibels can be used on linear coordinates. The angle between the straight lines is taken as the error. An error angle of 6.5° is calculated for the present meter.
THE FUNCTION OF PHYTOCHROME IN THE NATURAL ENVIRONMENT—II. THE INFLUENCE OF VEGETATION CANOPIES ON THE SPECTRAL ENERGY DISTRIBUTION OF NATURAL DAYLIGHT
Authors: Holmes M. G. , Smith Harry 
Published: January 2008

Abstract— Qualitative changes in the spectral energy distribution (SED) of natural daylight within the 400–800 nm wavelength band have been followed within a wheat canopy. Selective attenuation of radiation by the canopy caused large decreases in the blue and red wavebands and, to a lesser extent, the green; far‐red was largely transmitted. This resulted in a decrease in the red:far‐red ratio from the values observed in natural daylight.The spectral energy distribution below the canopy was found to be partially dependent on solar elevation and sky condition; it was also dependent on the age, height, leaf area index and chlorophyll content of the crop. The possible ecological significance of the wide variety of spectral energy distributions which have been observed are discussed in relation to phytochrome function.
REACTIONS OF O‐2, H2O2 AND OTHER OXIDANTS WITH SULFHYDRYL ENZYMES‡
Authors: Armstrong David A. , Buchanan John D. 
Published: January 2008

Abstract— The inactivation of a number of sulfhydryl enzymes by H2O2. OH and O‐2 is discussed. and the efficiencies of inactivation for the free radicals are compared with those of halide radicals. The enzymes with essential acyl‐binding SH groups (papain and GAPDH) exhibit a higher sensitivity to inactivation by O‐2 and H2O2 than those with “unactivated” SH groups (LDH and ADH). The sulfenic acid derivatives from the reactions of papain and GAPDH with H2O2 are repairable by RSH molecules, the rates of repair depending on the nature of the R group.Comparisons of rate constants show that competitive scavenging by RSH must be a very important mechanism for the protection of sensitive SH‐containing proteins against OH, and for papain in oxygen‐free solutions the efficiency of this protection increased in the order GSH < PenSH < CysSH < dithiothreitol. On the other hand, catalase and superoxide dismutase are more effective than RSH compounds in rendering protection against H2O2 and O‐2. In fact in oxygen‐containing systems the effects of RSH are highly complex, because the OH‐ and/or O‐2‐initiated chain oxidation of these molecules produces reactive species, which may inactivate essential SH groups. Experiments with papain showed that the yields and nature of the RSH‐derived species depended on the structure of the R group. Also, very large yields of papain Cys25SSR were produced from the reactions of the radicals and H2O2. In effect, it is apparent that under certain conditions the oxidation of “activated” SH groups of important target molecules could become coupled to the OH or O‐2 ‐initiated oxidation of RSH molecules. This should be taken into account in assessing the overall effectiveness of RSH compounds as cellular protectors.
STUDIES ON THE PHOTOTOXICITY OF COUMARIN DERIVATIVES — I. PHOTOCYCLODIMERIZATION OF 5,7‐DIMETHOXYCOUMARIN
Authors: Shim Sang Chul , Choi Kwan Yong , Song Pill‐Soon 
Published: January 2008

Abstract— 5,7‐DimethoxJtcoumarin (DMC) dimerizes through the C4‐photo‐cycloaddition of 3,4‐double bonds to form a syn head‐to‐tail dimer on direct irradiation (Λ≥ 300 nm) in acetonitrile or benzene solution. The quantum yield of the photocyclodimerization in acetonitrile is 0.068 which is greater than that of coumarin.In the presence of triplet sensitizers such as benzophenone, 5,7‐dimethoxycoumarin forms an anti dimer with the quantum yield greater than 0.08. The structure of the photodimers has been elucidated by IR, UV, NMR, and mass spectrometry. The results of luminescence studies, triplet quenching and sensitization revealed that the syn head‐to‐tail dimer was formed via an excited singlet precursor, while the anti dimer was formed via the excited triplet state.
REGULATION OF CHLOROPLAST DEVELOPMENT BY RED AND BLUE LIGHT
Authors: Buschmann C. , Meier D. , Kleudgen H. K. , Lichtenthaler H. K. 
Published: January 2008

AbstractThere are specific differences between red and blue light greening of etiolated seedlings of Hordevm vulgare L. Blue light results in a different prenyl lipid composition of chloroplast as compared to red light of equal quanta density. This is documented by a much higher prenylquinone content, higher chlorophyll a/b ratios, and lower values for the ratio xanthophylls to carotenes (x/c). The photosynthetic activity of “blue light” chloroplasts (Hill reaction) is higher than that of “red light” chloroplasts. These differences in prenylquinone composition and Hill‐activity are associated with a different ultrastructure of chloroplasts. “Red light” chloroplasts exhibit a much higher grana content than “blue light” chloroplasts. The difference in thylakoid composition, photosynthetic activity and chloroplast structure found between blue and red light greening are similar to those found between sun and shade leaves and those between plants grown under high and low light intensities.
ACID‐BASE EQUILIBRIA OF THE EXCITED SINGLET AND TRIPLET STATES AND THE SEMI‐REDUCED FORM OF ACRIDINE ORANGE
Authors: Kellmann Arlette , Lion Yves 
Published: January 2008

Abstract— The acid‐base equilibria of the excited singlet and triplet states of acridine orange (AO) were studied by flash‐photolysis and fluorometric methods. The dye is a stronger base in the first excited singlet state (pKs= 13.3) than in the triplet and ground states (pKr= 10.3: pKc, = 10.2); acridine orange follows the trend observed with some other heterocyclic compounds, viz. pKs >pKr= pK,c. At room temperature, an anomalous fluorescence occurs from the dye in basic media: the assignment of this emission is discussed.The semi‐reduced dye was studied as a function of pH. In a large pH range (3–14), only the protolytic equilibrium between the cationic (AOH2+) and the neutral (AOH) radicals was observed; the pK value corresponding to this equilibrium was found to be in the range of pH 5–6.
RHODOPSIN: ITS MOLECULAR SUBSTRUCTURE AND PHOSPHOLIPID INTERACTIONS*
Authors: Litman Burton J. 
Published: January 2008

Abstract—Rhodopsin in retinal rod outer segment disc membranes, was proteolyzed by treatment with papain. This treatment left three fragments of apparent mol wt of 26,000, 19,000 and 10,000 in the membrane. The circular dichroism (CD) of solubilized, proteolyzed rhodopsin, in both the UV and visible spectral regions, was essentially identical to that of native rhodopsin. This indicates that the retinal binding site configuration is essentially unchanged by proteolysis and that the proteolyzed form of rhodopsin retained the helical content of native rhodopsin. Far UV CD measurements on the fragments indicate that the secondary structural features of the proteolyzed complex were largely maintained when the complex was dissociated. This finding suggests that the proteolytic fragments represent independently stabilized domains within rhodopsin.Measurements of the dependence of the activation free energy of the unfolding of opsin (as determined by the rate of loss of regenerability of opsin) and the meta I to meta II transition on the level of phospholipid associated with opsin and rhodopsin. respectively, have allowed for a determination of the mode of stabilization of these proteins by phospholipid. This dependence has been shown to have a linear form for opsin and rhodopsin. Hence, it appears that the stabilization of the tertiary structure of both solubilized opsin and rhodopsin is attributable to the sum of their interactions with individual phospholipid molecules, interacting with the protein in a non‐cooperative manner.
CELL CYCLE MAPPING BY IRRADIATING CELLS WITH BROMOSUBSTITUTED DNA SEGMENTS
Authors: Torre C. de la , Gonzalez‐Fernandez A. 
Published: January 2008

Abstract—The role of chromatin replicated at restricted S intervals in further interphase progression has been analyzed by bromosubstitution followed by black light irradiation (313 nm peak) in a naturally synchronous population rendered binucleate by a caffeine pulse in Allium cepa L. root meristems.Interphase completion is preferentially halted when irradiating cells with bromosubstituted chromatin which is replicated at the 3rd and 4th interval of an S period artificially divided into 5 portions. The treatment apparently inhibits transcription of the bromosubstituted DNA segments. The failure in the transcription of these segments may be related to the transition point located at early G2 in these cells. where protein synthesis is needed in order to reach mitosis.
MIGRATION OF SINGLET EXCITATION ENERGY FROM ACRIDINE ORANGE‐10‐DODECYL BROMIDE TO METHYLENE BLUE IN MICELLES
Authors: Usui Yoshiharu , Gotou Akie 
Published: January 2008

Abstract—The efficient energy transfer occurred from photoexcited singlet stale of acridine orange‐10‐dodecyl bromide dissolved in SDS micelles to methylene blue absorbed on the micelle surface. The sensitized fluorescence of methylene blue was effectively quenched by the addition of a small amount of ethanol and with the increase in temperature.
PHOTOCHEMISTRY OF THE REACTION CENTERS OF SYSTEM II UNDER REPETITIVE FLASH GROUP EXCITATION IN ISOLATED CHLOROPLASTS
Authors: Eckert H. J. , Renger G. 
Published: January 2008

Abstract— Absorption changes induced in isolated chloroplasts by excitation with repetitive flash groups have been measured at 690 nm, indicating the photochemical turnover of chlorophyll‐aII (Chl‐αn), and at 480 nm and 513 nm respectively, reflecting via electrochromic effect the formation of a transmembrane electric field. The data are compared with measurements of oxygen evolution. In chloroplasts with practically fully intact oxygen evolving capacity it was found:1. The initial amplitude of the 690 nm absorption change induced by the second flash as a function of the time tv between the first and second flash of a group increases with a half life of about 35 µs. On the other hand, the average oxygen yield due to the second flash as a function of the time tv rises with a half life of about 600 µs (and a kinetics in the ms‐range of minor extent), confirming the data of Vater et al. (1968).2. Under far red background illumination, where contributions due to PS I in the µs‐range can be excluded, the difference spectrum in the red of the absorption changes induced by the first flash corresponds with that of the absorption changes induced by the second flash fired 200 µ after the first flash.3. The pattern of the absorption changes at 690 nm induced by repetitive double flash groups at tv= 200 µs does not markedly change in normal chloroplasts by the presence of DBMIB†. Similar 690 nm absorption changes occur in trypsin treated chloroplasts, independent of the presence of DCMU.4. The fast regeneration in the µs‐range of Chl‐an is also observed in the third flash of a triple flash group at a time tv= 200 µs between the flashes of the group.5. The initial amplitudes of the absorption changes with a decay kinetics slower than 100 µs induced by the second flash at 480 nm and 513 nm, respectively, as a function of the time t, between the first and second flash of a group, are characterized by a recovery half‐time of about 600 µs, confirming earlier measurements at 520 nm (Witt and Zickler, 1974).On the basis of these results it is inferred that there does exist a photoreaction of Chl‐αn., with an electron acceptor, referred to as Xa, other than the ‘primary’ plastoquinone acceptor X320, if X320 persists in its reduced state. Under conditions of X320 being in the reduced state, this photochemical reaction was shown to be highly dissipative with respect to charging up the watersplitting enzyme system Y. Furthermore, this Chl‐an‐photoreaction with Xa does not lead to a vectorial transmembrane charge separation, which is stable for more than a few microseconds. Different models for the functional and structural organization of PS II are discussed.
A SHORT‐LIVED INTERMEDIATE IN THE PHOTO‐ENZYMATIC REDUCTION OF PROTOCHLOROPHYLL(IDE) INTO CHLOROPHYLL(IDE) AT A PHYSIOLOGICAL TEMPERATURE
Authors: Franck Fabrics , Mathis Paul 
Published: January 2008

Abstract—The reduction of protochlorophyll(ide) into chlorophyll(ide) has been studied by flash absorption spectroscopy at 21°C, with a time resolution of 0.5 µs. The absorption changes have been recorded in the range 670–720 nm after the first and subsequent flashes given to an extract of etiolated bean leaves.At 695 nm the flash‐induced absorption increase has its maximum value immediately after the flash and then partly decays with a half‐time of about 7–10 µs. A complementary behaviour is observed at 675 nm where the absorption change is very small at time zero and then increases to a stationary value with a half‐time of about 6–9 µs. From measurements at several wavelengths it is concluded that a species with an absorption peak around 695 nm is formed immediately after the flash and is then transformed into a stable species with an absorption peak around 675 nm. Measurements at lower temperatures, down to—50°C, show that the transformation is much slowed down at decreased temperatures. The species absorbing at 695 nm (P695) is attributed to an intermediate in the photoreduction of protochlorophyll(ide) P639,650 into chlorophyll(ide) P676.When the protochlorophyll(ide) is photoreduced before the flash illumination, the newly formed chlorophyll(ide) gets to a triplet state, which decays with a half‐time of 15 µs at 21°C. This result shows that carotenoid molecules do not exert their protective role at this stage of chlorophyll (Chi) formation.
PHOTOSENSITIVITY IN CAROTENOIDLESS MUTANTS OF MICROCOCCUS LUTEUS (SARCINA LUTE A): NON‐PHOTODYNAMIC MENAQUINONE DESTRUCTION IN WHITE LIGHT
Authors: Prebble John N. 
Published: January 2008

Abstract–The photosensitivity of a carotenoidless mutant strain has been examined in terms of its loss of viability and loss of menaquinone when subjected to high intensity visible light. Cell viability and menaquinone are protected by cyanide (an inhibitor of cytochrome oxidation), by malate (a substrate for the respiratory chain) and by nitrogen although the protection of menaquinone is less in nitrogen. Evidence is presented in support of the view that oxidised membrane‐bound menaquinone is more photolabile in visible light than the reduced form. Loss of menaquinone is seen as the primary cause of death in these obligately aerobic carotenoidless cells and the role of oxygen as indirect by converting reduced menaquinone to the oxidised form. Evidence is also presented that the cause of cell death in red light in the presence of an exogenous photosensitizer, toluidine blue, is different from that in white light.
PHOTOOXIDATION AND SINGLET OXYGEN SENSITIZATION BY PROTOPORPHYRIN IX AND ITS PHOTOOXIDATION PRODUCTS
Authors: Cox G. Sidney , Bobillier Christiane , Whitten David G. 
Published: January 2008

AbstractProtoporphyrin IX and its various ester derivatives have been previously shown to undergo self‐sensitized photooxygenation to yield hydroxyaldehydes (photoprotoporphyrin) and mono‐ and diformyl deuteroporphyrin derivatives. In the present study the photoreactions of these products in the presence of oxygen have been investigated. All of the photooxidation products are themselves good sensitizers of singlet oxygen. In addition spin trapping experiments indicate these products can produce superoxide in low‐to‐moderate efficiency by an excited state electron transfer process. The photo‐products themselves are somewhat more stable to photooxidation than protoporphyrin IX itself. The two monoformyl‐monovinyl deuteroporphyrins have been found to undergo further photooxidation at the vinyl groups to yield primarily monoformyl hydroxyaldehydes in a reaction mainly involving singlet oxygen analogous to the initial reaction of protoporphyrin IX.