bluuebunny/crossref_metadata_2025 huggingface dataset:
The leaf‐beetle genusMicrodonaciaBlackburn (Coleoptera: Chrysomelidae: Galerucinae): revision and systematic placement
Authors: REID C. A. M.
Published: January 2008

Abstract.The genusMicrodonaciaBlackburn is revised and its systematic position considered. Ten species are treated, seven of which are new (bidentata, eucryphiae, grevitteae, incurva, octodentata, pilosa, pomaderris), and lectotypes are designated for two species. Four of the new species are placed inTantawangalosubgen.n.Microdonaciais compared with the generaCassenaWeise,LicyllusJacoby andOrthalticaCrotch. The sister‐group forMicrodonaciais identified asOrthalticaand these genera are placedincertae sedisin the Galerucinae, as used in the sense of Crowson (1967). The proposed phylogeny of the species is illustrated on a cladogram.
The phylogenetic relationships between virus vector and other genera of macrosteline leafhoppers, including descriptions of new taxa (Homoptera: Cicadellidae: Deltocephalinae)
Authors: KNIGHT W. J. , WEBB M. D.
Published: January 2008

Abstract. Analysis of thirty‐four macrosteline and twenty‐eight non‐macrosteline leafhopper genera (Homoptera: Cicadellidae: Deltocephalinae) suggests that the ability to transmit plant viruses has arisen on at least three separate occasions within the Macrostelini. The tribe, including the Coryphaelini syn.n. and Balcluthini, is shown to be monophyletic. A revised diagnosis of the Macrostelini is presented, together with a key to genera. Five new genera and eight new species are described: Adergannagen.n., Cicadabaragen.n.Kadrabolinagen.n., Masafueragen.n. and Scaphostelesgen.n., Yamatotettix remaneisp.n., Masafuera oceanicasp.n., Aderganna aethiopicasp.n., A.nigrasp.n., Scaphosteles nukahivasp.n., Kadrabolina elongatasp.n., K.sinuatasp.n. and K.bispinosasp.n. Four new combinations and five new synonymies are established: Cicadabara dorsalis (Osborn) comb.n., C.minuta (Osborn) comb.n., C.tintorella (Osborn) comb.n., Balclutha thea (Distant) comb.n., B.smaragdula Matsumura as a junior synonym of B.thea (Distant) syn.n., B.modesta Ahmed, Murtaza & Malik as a junior synonym of B.incisa (Matsumura) syn.n., B.karachiensis Ahmed, Murtaza & Malik as a junior synonym of B.rubrostriata (Melichar) syn.n., B.versicoloroides Ghauri as a junior synonym of B.sternalis (Distant) syn.n. and B.knighti Rao & Ramakrishnan as a junior synonym of B.sujawalensis Ahmed syn.n.
Description of a new genus of scale insect with a discussion of relationships among families related to the Kermesidae (Homoptera: Coccoidea)
Authors: MILLER DOUGLASS R. , MILLER GARY L.
Published: January 2008

Abstract. A new kermesid genus, Eriokermes, is described for three species previously placed in the Eriococcidae: Eriokermes gillettei (Tinsley) comb.n.; E.juniperi (Goux) comb.n.; and E.juniperinus (De Lotto) comb.n. Keys to Nearctic kermesid genera, Eriokermes species, and immatures and adults of E.gillettei are provided. Four female and five male instars of E.gillettei are described. Eriokermes is placed in Kermesidae based on a cladistic estimate of its phylogenetic position.

Kermesids can be distinguished from eriococcids by: adult males with 5 pairs of simple eyes, presence of a postocciput, prescutal ridge extending into scutum, and scutum with central clear area; adult females with dorsal simple disc pores, without microtubular ducts, usually without protruding anal lobes, and usually with a submarginal band of tubular ducts on the tergum; and first instars with dorsal simple disc pores, with 4 dorsal rows of setae on abdominal segments excluding the posterior one, and without microtubular ducts. Conversely, eriococcids can be distinguished from kermesids by: adult males with 2 pairs of simple eyes, absence of a postocciput, presuctal ridge not extending into scutum, and scutum without central clear area; adult females without dorsal simple disc pores, with microtubular ducts, usually with protruding anal lobes, and usually with tubular ducts scattered over the venter; and first instars with microtubular ducts, with 6 dorsal rows of setae on abdominal segments excluding the posterior one, and without dorsal simple disc pores.

The present cladistic analysis provides evidence that the Eriococcidae constitute the sister group of the Pseudococcidae (Boratynski & Davies, 1971) and is contrary to the conclusions of Miller & Kosztarab (1979), Danzig (1980) and Kosztarab & Bullington (1986).

The importance of including characters from adult male and first instars in phylogenetic analyses of coccoids has been emphasized previously (Ferris, 1957; Miller & Kosztarab, 1979). The current study confirms their value for the resolution of higher level relationships within the Coccoidea.
Three sympatric species of Blepharoneura (Diptera: Tephritidae) on a single species of host (Gurania spinulosa, Cucurbitaceae): new species and new taxonomic methods
Authors: CONDON MARTY A. , NORRBOM ALLEN L.
Published: January 2008

Abstract. We describe two new species of Blepharoneura (Diptera: Tephritidae) from Venezuela and Trinidad and redescribe Blepharoneura atomaria (Fabricius), comb.n. Each of the morphologically similar sympatric species feeds on a different tissue of Gurania spinulosa Cogn. (Cucurbitaceae): seeds (B.manchesteri, sp.n.), male flowers (B.atomaria), and female flowers (B.perkinsi, sp.n.). With the help of elementary school children and teachers we developed new methods for detecting and describing wing patterns. We present frequency distributions of character states and describe a denticulate area within the distiphallus that may function as a holdfast. For each species we provide notes on the ecology and behaviour of larvae and adults.
Phylogeny and early evolution of the Cynipoidea (Hymenoptera)
Authors: RONQUIST FREDRIK
Published: January 2008

Based on several structural and biological characteristics, the Cynipoidea can be divided into two groups, ‘macrocynipoids’ and ‘microcynipoids’. The macrocynipoids (i.e. the family Liopteridae and the genera Austrocynips, Eileenella, Heteribalia and Ibalia) are generally large insects that parasitize wood‐ or cone‐boring insect larvae. The microcynipoids are smaller insects that are either phytophagous gall inducers and inquilines (Cynipidae) or parasitoids of larvae of Hymenoptera, Neuroptera or Diptera (Figitidae sensu lato, including the families Eucoilidae, Charipidae and Anacharitidae). The phylogenetic relationships among genera of macrocynipoids and between these and a sample of four genera representing the Figitidae and Cynipidae were examined by parsimony analysis of 110 external morphological characters of adults. Within the macrocynipoids, three monophyletic lineages emerged, classified here as different families: the Austrocynipidae, with a single species, Austrocynips mirabilis, the only cynipoid with a true pterostigma; the Ibaliidae, including the genera Eileenella, Ibalia and Heteribalia; and the Liopteridae, comprising the remaining genera of macrocynipoids. The analysis further supported the monophyly of the microcynipoids and indicated that the macrocynipoids form a paraphyletic group relative to the microcynipoids, with the shortest tree suggesting the relationship (Austrocynipidae, (Ibaliidae, (Liopteridae, microcynipoids))). These results imply that cynipoids were originally parasitoids of wood‐boring insect larvae and that the other modes of life evolved secondarily within the group.
THE QUANTUM YIELD OF THE CHEMILUMINESCENCE OF DIMETHYLBIACRIDYLIUM NITRATE AND THE MECHANISM OF ITS ENZYMICALLY INDUCED CHEMILUMINESCENCE*
Authors: Totter John R.
Published: January 2008

Abstract— Quantum yields for dimethylbiacridylium ion chemiluminescence based on the amount of methyl acridone formed by treatment with either H2O2 or with xanthine oxidasehypoxanthine in 0.01 M Na2CO3 at pH 10.4 and at 25°C were found to lie between 0.011 and 0.020 with an average of about 0.016.In mixed solvents containing pyridine and water or alcohol and water the emission spectrum of chemiluminescence of dimethylbiacridylium ions as well as those of diniethylbiacridene and its oxide were found to be identical with or very similar to the fluorescence of methyl acridone in the same solvent.A mechanism involving two successive two equivalent reductions of the diniethylbiacridylium ion to dimethylbiacridan followed by a radical attack and auto‐oxidation leading to a compound which can undergo a reverse aldol type reaction to yield one (or two) molecule of methylacridone and one of a somewhat more reduced form is suggested.The kinetic equation relating maximum intensity of chemiluminescence to dimethylbiacridylium ion, hypoxanthine, xanthine oxidase, H+ and O2 concentrations was derived from the scheme suggested and found to fit satisfactorily the data obtained from a series of experiments in which the quantum yield was also obtained.
ELECTRON SPIN RESONANCE STUDIES OF ULTRAVIOLET IRRADIATED KERATIN AND RELATED PROTEINS
Authors: Dunlop J. I. , Nicholls C. H.
Published: January 2008

Abstract— The formation of free radicals in keratin and related proteins by exposure to u.v. light has been examined by electron spin resonance spectroscopy. From a comparison of the spectra obtained and the effects of different wavelengths and the stabilities of the radicals produced, it has been shown that several species of free radicals are produced by the u.v. irradiation of keratin. However it has been possible to identify only those free radicals associated with the cystine residues. The free radicals produced in keratin by exposure to shorter wavelength irradiation (below 3250 Å) were found to be quite different to those produced at longer wavelengths.
CHEMICAL CHANGES LEADING TO CHEMILUMINESCENCE OF LUCIGENINE (DIMETHYLBIACRIDYLIUM NITRATE) AND OF SOME PHTHALAZINEDIONE DERIVATIVES
Authors: Totter John R. , Philbrook George E.
Published: January 2008

Abstract— Measurements of the redox potential of the chemiluminescent compound 10,10′ dimethyl‐9,9′ biacridylium nitrate (‐0.093 V) show that it is thermodynamically possible to reduce it with hydrogen peroxide or with ammonium hydroxide in alkaline solutions at equilibrium concentrations sufficiently high to account for the observed chemiluminescence. Reduction of the compound with ammonium hydroxide takes place much more slowly than the corresponding reaction with hydrogen peroxide so that when both redox couples (O2/H2O2 and N2H4/NH4OH) are present the hydrogen peroxide couple predominates if oxygen is supplied. It was shown that interference with the oxygen supply or its partial removal with nitrogen brings about an increase in chemiluminescence intensity in NH4OH while increasing the concentration of oxygen diminished the intensity.

5‐amino 2,3 phthalazine 1,4 dione (luminol) also appears to undergo a reduction following a two step oxidation. This is shown by the fact that when oxygen was supplied the chemiluminescence intensity was found to be directly proportional to the OH‐ concentration while a typical titration curve with pK 11.7 is exhibited by the intensity when the oxygen supply is limited in mixtures of luminol and peroxydisulfate. The peroxide presumably arises in the first oxidation step. Amino peroxyphthalic anhydride is suggested as an intermediate which is reduced to the aminophthalate ion, the presumed emitter in the chemiluminescence.
STUDIES ON THE INACTIVATION OF TOBACCO MOSAIC VIRUS BY ULTRAVIOLET LIGHT*,‡,§
Authors: Goddard Judy , Streeter David , Weber Celia , Gordon Milton P.
Published: January 2008

Abstract— The irradiation of TMV with u.v. light of 2537 Å wavelength results in the binding of protein subunits to the RNA. These bound subunits are stable towards warm sodium dodecyl‐sulfate; however, the binding is not covalent since the subunits are removed by 66% acetic acid, guanidine hydrochloride, or phenol. Approximately one protein subunit is bound per lethal biological ‘hit’. The virus and the nucleic acid extracted from irradiated virus show virtually identical rates of inactivation.
ACTION SPECTRA FOR LIGHT‐INDUCED SPORULATION OF THE FUNGI PLEOSPORA HERBARUM AND ALTERNARIA DAUCI*,†
Authors: Leach Charles M. , Trione E. J.
Published: January 2008

Abstract— Action spectra for light induced sporulation were determined for conidia of Alternaria dauci, and conidia and perithecia of Pleospora herbarum (Imperfect stage is Stemphylium botryosum). Only radiation less than 370 mμ induced formation of conidia, and less than 390 mμ formation of perithecia. The action spectra showed increased effectiveness in the 230 and 290 mμ regions, and possibly in the 260–270 mμ regions. Below 280 mμ these action spectra may not be representative of the “true” absorption spectra of the photoreceptors involved because of possible superimposed effects caused by nucleic acid absorption. Though the action spectra were not identical, the number of characters in common were suggestive of a similar photoreceptor. Similarities between action spectra for sexual and asexual reproduction of P. herbarum indicate the possibility of a single photoreceptor for both processes.
THE ROLE OF PEROXIDES IN THE INHIBITION OF DNA SYNTHESIS IN CELLS FOLLOWING IRRIDIATION WITH A U.V. MICROBEAM
Authors: Dendy P.P. , Smith C.L. , Aebi H. E.
Published: January 2008

Abstract Previous work had shown that the rate of DNA syntheses in mammalian cells could be reduced when a microbeam of ultraviolet light was directed into the medium surrounding the cells. The present work was designed to gather informtion on the mechanism of this effect.

Results show that catalase does protect the cellualar DNA synthesis under the following conditions.

(1) The microbeam must be directed into the surrounding medium—there is no protection if it strikes any part of the cell.

(2) The catalase must have been in contact with the cells for at least 4 hr before irradiation.

(3) At high closes of radiation the protection is only partial.

The catalase was labelled with fluorescent dye to demonstrate that it was able to penetrate the cell cytoplasm but not nucleus. Morphological studies on cell exposed to medium containing hydrogen pereoxide showed that protection was provided by intracellular and not extracellular catalasse and supported the idea that the toxic product produced by ultraviolet radiation of the medium was ultimately a peroxide.
ÉTUDE EN SPECTROSCOPIE PAR ÉCLAIR DES COLORANTS THIAZINIQUES EN SOLUTION AQUEUSE
Authors: Faure Jean , Bonneau Roland , Joussot‐Dubien Jacques
Published: January 2008

Abstract— pK values of ionisation equilibrium of thiazines dyes in their triplet state have been measured in aqueous solutions by spectroscopy. The triplet‐triplet absorption bands, in the red part of the spectrum, are given for thionine, azurs and methylene blue. It is shown that, in the pH range 4–9, the equilibria investigated correspond to a second protonation of thiazines dyes that occurs in the triplet state:

3TH++ H+→3TH22+

designating by 3TH+ the thiazine cation similar to the species stable in neutral aqueous solutions.
ULTRAVIOLET PHOTOINACTIVATION STUDIES ON HYBRID VIRUSES OBTAINED BY THE CROSS‐RECONSTITUTION OF THE PROTEIN AND RNA COMPONENTS OF U(1) AND U(2) STRAINS OF TMV*
Authors: Streeter David G. , Gordon Milton P.
Published: January 2008

The sensitivities of U(1) and U(2) TMV strains to inactivation by ultraviolet light at 253.7 nm were compared with those of hybrid viruses obtained by reconstituting the protein of either native strain with the RNA of the other. In each case, the hybrid virus was found to be virtually identical in sensitivity to the native strain which supplied the protein coat, indicating that the relative sensitivities of the two native strains to ultraviolet light are solely a function of their respective protein coats. Amino acid analysis of the U (2) protein reveals about thirteen or fourteen amino acid replacements compared with the U (1) strain, which is in agreement with earlier studies indicating that there are considerable differences in the protein subunits of the two proteins. Some of the ways in which the observed differences in proteins of the two strains may determine their respective ultraviolet sensitivities are discussed.
THE NATURAL PHOSPHORESCENCE LIFETIME OF BIACETYL AND BENZIL IN FLUID SOLUTION
Authors: Almgren Mats
Published: January 2008

Abstract— The quantum yields of phosphorescence and fluorescence and the phosphorescence lifetime have been determined for biacetyl in benzene, p‐xylene, n‐heptane, and water, and for benzil in n‐heptane at 22d̀C. The following values for the fluorescence quantum yield and natural phosphorescence lifetime were obtained: For biacetyl in benzene, 2.7 times 10‐3 and 7.8 msec, in p‐xylene, 2.5 times 10‐3 and 10.8 msec, in n‐heptane, 2.9 times 10‐3 and 10.8 msec, in water, 1.1 times 10‐3 and 10.0 msec, and for benzil in n‐heptane, 1.1 times 10‐3 and 10.4 msec.
MULTIPLE CHROMOPHORE SPECIES IN PHYTOCHROME*,†,‡
Authors: Correll David L. , Edwards John L. , Shropshire W.
Published: January 2008

Abstract— Buffered aqueous solutions of pure phytochrome, when irradiated at 730 nm, had a main absorption band at about 660 nm and a shoulder or secondary band at 580–600 nm. When irradiated at 660 nm, these absorption bands bleached and a pair of bands at 670 and 725–730 nm appeared. When 660 nm irradiated samples were placed in the dark the 730 nm absorption slowly bleached and the 670 nm absorption band shifted to 660 nm. The kinetics of the bleaching indicated that two populations of PFR existed initially. These two populations decayed by first order kinetics with k's of 4.8 × 10‐4 sec‐1 and 3.1 × 10‐‐5 sec‐1at 25°. While the bleaching of PFR was occumng, the appearance of the 660 nm and 580–600 nm absorption bands characteristic of PR took place. The kinetics of the increase in the 580 and 660 nm absorption bands indicated that it was arising from two populations of reactants by two first order reactions with k's of 6.4 × 10‐4 sec‐1 and 3.1 × 10‐5sec‐1 at 25°. When the sodium chloride concentration of the solvent was changed the proportions of the kinetically different populations were altered. In some conditions, especially in the presence of air. reversible but non‐reciprocal changes in the four absorption bands were observed. These effects were evident after the lapse of many hours in the dark. When native phytochrome was treated with sodium dodecyl sulfate all absorption bands but the 580–600 nm absorption band were bleached and photoreversibility was lost. When native phytochrome was treated with glutaraldehyde, the 730 nm absorption band was bleached but photoreversibility was retained. It was concluded that at least four species of chromophore exist in phytochrome with absorption maxima at 580, 660, 670 and 730 nm. Each chromophore is capable of being bleached by appropriate irradiation or in the dark by chemical reactions rather than photochemical reactions. The reactions are probably coupled redox reactions between the 580–660 nm pair and the 670–730 pair of chromophores. Discrepancies observed in the reciprocity of the absorption changes in these paired bands are probably due to various degrees of uncoupling and secondarily to the redox potential of the solvent when such uncoupling occurs.
UN NOUVEAU MODELE DES CENTRES PHOTOCHIMIQUES DU SYSTEME II*
Authors: Joliot P. , Barbieri G. , Chabaud R.
Published: January 2008

Abstract— The amount of oxygen evolved by Chlorella cells or by isolated chloroplasts has been measured after illumination by short saturating flashes. In all conditions, the amount of oxygen evolved by one flash is proportional to the fraction of the photochemical centers susceptible to produce oxygen.

If dark adapted algae or chloroplasts are illuminated by a sene of flashes, no oxygen is produced by the first flash. This phenomenon is related to the activation process.

If yn is the amount of oxygen evolved by the nth flash of the sequence, it appears that the sene yn shows large oscillations with a period 4. These oscillations are completely damped after 4–6 periods and the amount of oxygen evolved by a flash reaches a stationary value. For any value of n. the quantities yn and yn+2 are linked by a recurrent relation which is the same for Chlorella cells and spinach chloroplasts. No relation can be found between the terms yn and y(n+1).

The mathematical properties of the series yn can be understood if one admits that a two memory process is involved in the photochemical reaction.

The results have been interpreted in terms of a new model of the System II photochemical centers. The main characteristics of this model are:

(1) Each photochemical center includes two electron donors (Z) and one electron acceptor (Q).

(2) The formation of one atom of oxygen requires a two quantum process corresponding to the transfer of two electrons from the same electron donor (first memory).

(3) The photochemical center acts as a switch which connects alternately each donor to the acceptor (second memory). The switch process occurs after each photoact with an efficiency of about 85 per cent.

Other arguments in favor of this model are obtained from studies of the rate of oxygen production at the onset of a weak illumination.
LIGHT‐INTENSITY DEPENDENCE OF THE IN VIVO FLUORESCENCE LIFETIME OF CHLOROPHYLL*
Authors: Müller Alexander , Lumry Rufus , Walker Michael S.
Published: January 2008

Abstract— Phase‐fluorometer measurements of the fluorescence lifetime, τ, from chlorophyll in Chlorella, Bishop's 8 and 11 Scenedesmus mutants, sugarbeet leaf and chloroplast fragments demonstrate that: τ is independent of modulation frequency at 27 and 14 mc. in the experimental‐wavelength range from 650 to 735 nm (with blue or blue‐green excitation); with Chlorelfa and chloroplast fragments τ rises hyperbolically with intensity to τmax about 2 nsec and 0·7 nsec respectively; DCMU poisoned Chlorella and sugarbeet leaf as well as the mutants have τ values near 2 nsec; the lifetime‐incident intensity relationship for Chlorella and chloroplast fragments is quantitatively similar to the incident‐intensity dependence of fluorescence yield and oxygen evolution and thus supports the hypothesis that these three measuring variables are controlled by the concentration of ‘open’ trapping systems; τ is independent of emission wave‐length to suggest that fluorescence is dominated by a single chlorophyll species. The reaction velocity‐lifetime correlation indicates that fluorescence behavior is directly controlled by system II.
CALORIMETRIC, PHOTOMETRIC AND LIFETIME DETERMINATIONS OF FLUORESCENCE YIELDS OF FLUORESCEIN DYES*
Authors: SEYBOLD PAUL G. , GOUTERMAN MARTIN , CALLIS JAMES
Published: January 2008

Abstract— The fluorescence yields and lifetimes of fluorescein and nine brominated derivatives in basic ethanol are reported. Calorimetric. photometric, and lifetime methods are used independently to measure the yields. A new and simple calorimetric method is presented for this purpose, and the accuracy of the techniques is assessed. There is good agreement between the calorimetric and photometric results. The importance of parameters such as purity, pH, and fluoresence reabsorption is illustrated. The theoretical determination of the natural radiative lifetime from the absorption spectrum is shown to have inherent ambiguities, so that only calorimetric methods provide a reliable, independent check for photometric yield measurements.
SPECTRAL CHARACTERISTICS OF THE EXCITED STATES OF THE PRODUCT OF THE CHEMILUMINESCENCE OF LUMINOL*
Authors: LEE JOHN , SELIGER H. H.
Published: January 2008

Abstract— In dimethylsulfoxide the emission spectrum of luminol chemiluminescence is red‐shifted by 300 cm‐1 from the photoexcited fluorescence of the product 3‐aminophthalate dianion, while in aqueous solvent the two spectra are identical. The spectral properties of the product dianion have been measured in aqueous solvent and in a number of aprotic solvents, both at room temperature and at 77°K. The ground states and the excited states from which emissions are observed are characterized. Two alternatives are presented to explain the aprotic emission spectra.
COOPERATION OF CHARGES IN PHOTOSYNTHETIC O2 EVOLUTION–I. A LINEAR FOUR STEP MECHANISM
Authors: KOK BESSEL , FORBUSH BLISS , McGLOIN MARION
Published: January 2008

Abstract— Using isolated chloroplasts and techniques as described by Joliot and Joliot[6] we studied the evolution of O2 in weak light and light flashes to analyze the interactions between light induced O2 precursors and their decay in darkness. The following observations and conclusions are reported: 1. Light flashes always produce the same number of oxidizing equivalents either as precursor or as O2. 2. The number of unstable precursor equivalents present during steady state photosynthesis is ∼ 1.2 per photochemical trapping center. 3. The cooperation of the four photochemically formed oxidizing equivalents occurs essentially in the individual reaction centers and the final O2 evolution step is a one quantum process. 4. The data are compatible with a linear four step mechanism in which a trapping center, or an associated catalyst, (S) successively accumulates four + charges. The S4+ state produces O2 and returns to the ground state S0. 5. Besides S0 also the first oxidized state S+ is stable in the dark, the two higher states, S2+ and S3+ are not. 6. The relaxation times of some of the photooxidation steps were estimated. The fastest reaction, presumably S*1←S2, has a (first) half time ≤ 200 μsec. The S*2 state and probably also the S*0 state are processed somewhat more slowly (˜ 300–400 μsec).
DEUTERIUM‐ISOTOPE EFFECT ON THE FLUORESCENCE YIELDS AND LIFETIMES OF INDOLE DERIVATIVES–INCLUDING TRYPTOPHAN AND TRYPTAMINE
Authors: RICCI ROBERT W.
Published: January 2008

Abstract— The fluorescence yields and lifetimes of indole, five of its alkyl detivatives, tryptophan, and tryptamine have been determined in degassed, heavy and light water at room temperature. All of the compounds have radiative lifetimes nearly identical to the parent compound indole, and a comparison of these results with recently reported data on tryptophyl derivatives disclosed a striking uniformity in radiative lifetimes between indole and many amino acids and peptides which contain the indole group as the fluorescence unit. The fluorescence rate kf in H2O, was found to be 4.5 × 107 sec‐1. The nonradiative decay rates were found to vary between 5.1 and 46 × 107 sec‐1 and from a study of the deuterium‐solvent isotope effect and the deuterium‐substituent effect a mechanism for nonradiative deactivation is proposed which includes an isotopically dependent proton transfer and a pathway involving energy loss via the ring carbon hydrogen vibrations. Tryptophan at pH 7 was found to have a unique nonradiative decay scheme not evidenced at a pH 1 or pH 10.
CONFORMATIONAL CHANGES OF LYSOZYME DURING PHOTODYNAMIC IN ACTIVATION*
Authors: HOPKINS T. R. , SPIKES JOHN D.
Published: January 2008

Abstract— Egg white lysozyme was inactivated by photodynamic treatment in sodium phosphate buffer at pH8 using methylene blue, eosin Y and FMN as sensitizers. Measurements sensitive to changes in protein conformation, in particular, tryptophyl fluorescence and protease digestibility, were made during the course of inactivation. The rate of change of lysozyme tertiary structure as measured in these ways correlated closely with the rate of loss of enzyme activity during photodynamic treatment. Further, forms of lysozyme which were enzymatically active, but which were more sensitive to high temperature than native enzyme were produced by photodynamic treatment. It is concluded that the photodynamic inactivation of lysozyme under the conditions used results largely from the photooxidation of amino acid residues essential for the maintenance of the catalytically active conformation of the enzyme.
DETERMINATION OF THE QUANTUM YIELD OF REVERSAL IN CRYSTALLINE DIMETHYL THYMINE DIMER, SYN HEAD TO HEAD
Authors: WEINBLUM D.
Published: January 2008

Recently we reported the splitting of crystalline dimethylthymine dimers to dimethylthymine by ‐γ‐irradiation[1]. The syn and the anti head to head isomers are split very efficiently with initial G‐values of 6300 and 1700 respectively. These high G‐values can only be explained by a chain reaction. However, the chain initiation event and the mechanism of energy propagation to sustain the reaction chain have still to be elucidated.
THE PHOTOSENSITIZED OXIDATION OF β‐CAROTENE
Authors: SEELY G. R. , MEYER T. H.
Published: January 2008

Abstract—–Products of oxidation of β‐carotene, photosensitized by hypericin in acetone, appear to include mutatochrome, aurochrome, and a number of other compounds absorbing in the violet and near u.v. regions of the spectrum. The 5, 6‐monoepoxide is not formed in appreciable quantity, though it is the principal product of oxidation of carotene by perphthalate. Mutatochrome, lutein, and zeaxanthin are photooxidized more slowly than β‐carotene, and the products do not appear to include 5, 6‐epoxides. β‐carotene‐5, 6‐monoepoxide is oxidized to what is probably luteochrome. Quantum yields appear to be low. We found no evidence to support a photochemical contribution to the oxidation of zeaxanthin to violaxanthin, a process known to accompany photosynthesis.
OXIDATION‐REDUCTION REACTIONS OF P700 AND CYTOCHROME f IN FRACTION 1 PARTICLES PREPARED FROM SPINACH CHLOROPLASTS BY FRENCH PRESS TREATMENT
Authors: FORK DAVID C. , MURATA NORIO
Published: January 2008

Abstract— –Fraction‐1 particles were prepared by passing spinach chloroplasts three times through the French pressure cell and centrifuging in a sucrose gradient.

With the electron donor DAD (diaminodurol or 2,3,5,6‐tetramethyl‐p‐phenylenediamine) and ascorbate, a light‐induced difference spectrum revealed the oxidation of both cytochrome f and P700 upon illumination of these particles. The oxidation of cytochrome f was completed in less than 0.5 msec. P700 and cytochrome f thus seem to be tightly bound to each other in these particles. Addition of Triton X‐100 abolished the fast oxidation of cytochrome f but not that of P700.

Artificial electron donors such as DAD, DCIP (2,6‐dichlorophenol indophenol), and PMS (N‐methylphenazonium methosulfate) were good electron donors for photoreaction 1 in these particles, while neither plastocyanin, Porphyra cytochrome 553, nor Euglena cytochrome‐552 reduced P700 efficiently. However, after treatment of fraction 1 particles with Triton X‐100 reduced DAD, DCIP and PMS were no longer efficient electron donors, while plastocyanin and the algal cytochromes were highly active in reducing P700. Mammalian cytochrome c was not a good electron donor either before or after Triton treatment.

Measurements of the effectiveness of P700 reduction as a function of concentration in Triton‐treated particles showed plastocyanin to be about four times more active than Porphyra or Euglena cytochromes which in turn were about fourteen times more active than mammalian cytochrome c.

Recent studies by Murata and Brown have shown that plastocyanin is not required for the reduction of NADP in these particles with DCIP and isoascorbate as electron donors. The present investigation and that of Murata and Brown indicate that disintegration of chloroplasts with the French pressure cell and centrifugation in a sucrose gradient is the best method to separate system‐1 particles having an electron‐transport system in almost the native state as in chloroplasts.
THE INFLUENCE OF THE NITRO GROUP ON THE DISSOCIATIONS OF SOME AROMATIC ACIDS AND BASES IN THEIR LOWEST EXCITED TRIPLET STATES*
Authors: SCHULMAN S. G. , SANDERS L. B. , WINEFORDNER J. D.
Published: January 2008

Abstract— –Estimation of lowest excited triplet and singlet state dissociation constants of some nitro‐aromatic acids and bases, from shifts in their phosphorescence and absorption spectra, respectively, indicate that intramolecular charge transfer to the nitro group is much more important in the lowest excited singlet state than in the ground or lowest excited triplet states. As a result, the effect of a nitro group on the acidity of the lowest excited singlet state of an acid or base is more exaggerated than that on the ground or lowest excited triplet state of the same compound. Furthermore, the basicity of the nitro group is greatly enhanced in the lowest excited singlet state. On this basis the increased rate of photoreduction of nitrobenzene in acidic solutions is found to be thermodynamically unfeasible in the lowest excited triplet state. Although the reaction is thermodynamically feasible in the lowest excited singlet state, the short lifetime of that state may make the reaction kinetically unfeasible. Rate‐Hammett acidity profiles are therefore inadequate to alone establish the mechanism of photoreduction of nitrobenzene.
THE FLUORESCENCE OF NATIVE, DENATURED AND REDUCED‐DENATURED PROTEINS*
Authors: KRONMAN M. J. , HOLMES L. G.
Published: January 2008

Abstract— (1) By excitation at 295 nm tryptophan fluorescence from 17 proteins was examined free of contributions from tyrosine. The tryptophan quantum yields for native proteins were both higher and lower than that of the free amino acid and spanned a 5‐fold range. No simple relationship was apparent between ‘exposure’ of tryptophyl side chains in proteins and the magnitude of the quantum yield or of the position of the emission maximum. (2) Denaturation of these proteins in 6 M guanidine hydrochloride considerably narrowed the range of values of yields (ca 0.1 to 0.17). While reduction of the disulfide bridges altered the yield of several proteins, it appeared to have no general effect on narrowing the range observed with a group of proteins, suggesting that either: (a) the amino acid sequence around a tryptophan in a disrupted peptide chain influences the yield, or (b) ‘residual’ three dimensional structure persists in reduced denatured proteins. (3) It was possible to demonstrate using both 280 and 295 nm excited spectra that tyrosine fluorescence, while weak, is generally present in proteins. These data also showed that transfer of the excited state from tyrosine to tryptophan is a common occurrence in native proteins and occurs with very high efficiency in a number of cases.
ESR STUDIES OF THE LOW TEMPERATURE IRRADIATION OF KERATIN AND ITS COMPONENT AMINO ACIDS
Authors: PAILTHORPE M. T. , NICHOLLS C. H.
Published: January 2008

Abstract— The photoejection of electrons from the aromatic amino acids at 77°K by 290–340 nm radiation was found to involve both monophotonic and biphotonic processes. However, only monophotonic processes are involved when electrons are photoejected from cystine or cysteine. These electrons prefer to attach themselves to adjacent sulphur groups rather than the dielectric traps in the matrix, so that both anionic and cationic radicals are formed.

In keratin at 77°K, the disulphide anion radicals are produced by both monophotonic and biphotonic mechanisms, indicating that the electrons captured by the disulphides are photo‐ejected from the aromatic amino acids. At room temperature the thiyl and aromatic radicals are produced only by monophotonic reactions.
ULTRAVIOLET AND GAMMA‐RAY INDUCED REPRODUCTIVE DEATH AND PHOTOREACTIVATION IN A XENOPUS TISSUE CULTURE CELL LINE*
Authors: GRIGGS H. G. , BENDER M. A.
Published: January 2008

Abstract— A clone having a plating efficiency of about 60–70 per cent has been isolated from the A8 Xenopus laevis tissue culture cell line. We have used it to test for photoreactivation of ultraviolet induced loss of colony‐forming ability. Photoreactivation produces a dramatic increase in survival. Time and temperature dependence experiments suggest that this is a true enzymatic process. Photoreactivation affects mainly the extrapolation number of the survival curves, rather than their slope. The cells lack a adein‐sensitive dark repair mechanism and photoreactivation is caffein‐independent. Parallel gamma‐ray experiments showed no photoreactivation, and cells were remarkably resistant to gamma‐ray killing, In marked contrast to their ultraviolet sensitivity.
ABSENCE OF OXYGEN‐EVOLVING CAPACITY IN DARK‐GROWN CHLORELLA: THE PHOTO ACTIVATION OF OXYGEN‐EVOLVING CENTERS*
Authors: CHENIAE G. M. , MARTIN I. F.
Published: January 2008

Abstract— Chlorella cells were cultured in darkness on glucose and examined for pigment composition, capacity to evolve oxygen, and capacity to photo‐oxidize artificial electron donors to Photosystems II and I. Evidence was obtained which indicated that such cells lack oxygen‐evolving centers and the Mn pool associated with such centers but possess fully active System II and I trapping centers. Brief illumination (t1/2˜ 2–3 min) of dark‐grown cells resulted in incorporation of Mn into the O2‐evolving centers and the capacity to evolve O2 (photo‐activation). Kinetic data from flashing or continuous light showed that the photoactivation is a multi‐quantum process involving several rate limitations and a photosensitive state of limited stability. Measurements of oxygen‐yield oscillations indicated that throughout the photoactivation process each newly formed oxygen‐yielding center was independent of its neighbors. It is concluded that photoactivation of the Mn‐containing oxygen‐yielding catalyst is a fundamental process in all photosynthetic oxygen‐evolving tissue.
ULTRAVIOLET‐RADIATION‐ACCELERATED LEAF CHLOROSIS: PREVENTION OF CHLOROSIS BY REMOVAL OF EPIDERMIS OR BY FLOATING LEAF DISCS ON WATER*
Authors: Wu J. H. , Skokut T. , Hartman M.
Published: January 2008

Abstract— Low doses (1800–7200 ergs/mm2) of ultraviolet (U V) radiation accelerated chlorosis in the mesophyll of Nicotiana glutinosa leaves when the lower epidermis of the leaves was irradiated. This occurred in either a subsequent light or dark incubation. However, within 12 h after irradiation, peeling of the lower epidermis prevented this accelerated chlorosis. The accelerated chlorosis was also prevented by floating irradiated leaf discs on water during the incubation period without removal of the epidermis. These results suggest that accelerated chlorosis in mesophyll tissue caused by low doses of UV is due to an indirect effect of the UV‐damaged epidermis, possibly mediated by some toxic substance released from the epidermal cells. High UV doses (36,000–108,000 ergs/mm2) prevented normal yellowing of the leaf. The irradiated portion of the leaf remained green, while the nonirradiated area turned yellow upon dark incubation. However, if the irradiated leaf was incubated in continuous light, bleaching of the irradiated area took place, and the irradiated area became yellow faster than the nonirradiated area. Peeling of the epidermis did not affect the outcome of these experiments. These results suggest that high UV doses directly damage the mesophyll tissue.
PHOTOCHEMICAL LABELING OF YEAST ALCOHOL DEHYDROGENASE WITH AN AZIDE ANALOG OF NAD +
Authors: Hixson Stephen S. , Hixson Susan H.
Published: January 2008

Abstract— 3‐Azidopyridine adenine dinucleotide, an azide analog of NAD+, has been synthesized as a potentially general photochemical labeling reagent for the active sites of NAD‐dependent dehydrogenases. The analog is a competitive inhibitor of NAD reduction by yeast alcohol dehydrogenase (YADH). Upon photolysis of the 3H‐analog in the presence of YADH, 7% of the label becomes covalently bound. The results are discussed in terms of desired properties of a photochemical labeling reagent.
ACTION SPECTRA FOR BIOSYNTHESIS OF CHLOROPHYLLS a AND b AND β‐CAROTENE
Authors: Ogawa Teruo , Inoue Yorinao , Kitajima Masao , Shibata Kazuo
Published: January 2008

Abstract— Action spectra for the formation of chlorophyll b and β‐carotene were determined with etiolated wheat leaves and compared with the action spectrum for the formation of chlorophyll a determined for the same samples. The action spectra were measured with etiolated leaves which had been pre‐illuminated for 10 min and incubated in the dark for 4 h to eliminate induction of pigments. The action spectra for chlorophyll b and for β‐carotene accorded with the action spectrum for chlorophyll a and with the absorption spectrum of protochlorophyllide in intact etiolated leaves. It is postulated from this result with chlorophyll b that this pigment is formed from protochlorophyllide through chlorophyll a or some intermediates to chlorophyll a. Complexing between chlorophylls and β‐carotene and proteins is postulated to interpret the action spectrum for β‐carotene. It is assumed that the low concentration of chlorophylls formed photochemically limits the rate of complexing, and that consumption of β‐carotene for the complexing induces formation of new β‐carotene.
FLUORESCENCE AND THE LOCATION OF TRYPTOPHAN RESIDUES IN PROTEIN MOLECULES
Authors: Burstein E. A. , Vedenkina N. S. , Ivkova M. N.
Published: January 2008

Abstract— Fluorescence spectra of a number of native and denaturated proteins have been analysed, using spectral band width (ΔΛ), spectral maximum position (Λm), fluorescence quenching by external ionic quenchers, lifetime (b), and quantum yield (q) and its changes upon denaturation. The results enabled a model of fluorescence properties of tryptophan residues in the proteins to be substantiated by considering the existence of three discrete spectral classes, one buried in nonpolar regions of the protein (Λm 330–332 nm, ΔΛ= 48–49nm, q 0.11, τ= 2.1 ns) and two on the surface. One of the latter is completely exposed to water (Λm# 350–353 nm, ΔΛ= 59–61 nm, q# 0.2, τ= 5.4 ns); the other is in limited contact with water which is probably immobilized by bonding at the macromolecular surface (Λm# 340–342 nm, ΔΛ= 53–55 nm, q# 0.3, = 4.4 ns). Some quantitative predictions from the model, for (a) the fraction of fluorescence that is quenched by ionic quenchers, (b) the mean values of quantum yield, and (c) the mean values of fluorescence lifetime for various proteins, show good concordance with independent experimentally determined values.
ACTION SPECTRA FOR UV INDUCTION AND PHOTOREVERSAL OF A SWITCH IN THE DEVELOPMENTAL PROGRAM OF THE EGG OF AN INSECT (SMITTIA)*
Authors: Kalthoff Klaus
Published: January 2008

Abstract— An action spectrum was established for the induction by ultraviolet (UV) radiation of the aberrant body segment pattern ‘double abdomen’ in the egg of the Chironomid midge Smittia. The action spectrum shows a peak at 285 nm wavelength, a shoulder at 265 nm, a slight increase from 245 to 240 nm, and a steep decline towards 300 nm. Corrections for wavelength‐dependent shielding within the egg result in transformation of the shoulder at 265 nm into a minor peak. These results are compatible with the assumption that a nucleic acid‐protein complex is involved in the initial photoreaction. This assumption is supported by the fact that the UV induction of the aberrant body segment pattern ‘double abdomen’ in the egg of Smittia is photoreversible. Wavelengths effective in this photoreversal range from 310 to 460 nm, with a peak at 440 nm. These spectral characteristics agree with action spectra for photoreactivation in other systems. Indirect photoreactivation does not occur in the egg of Smittia under the conditions of the experiments. Photoreversal with 440 nm radiation at high dose rate is temperature‐dependent. The results support the assumption that the molecular basis for photoreversal in the egg of Smittia is similar to the predominant molecular mechanism of direct photoreactivation in other systems. Targets possibly involved in the UV induction of the ‘double abdomen’ are discussed.
ON THE MECHANISM OF QUENCHING OF SINGLET OXYGEN IN SOLUTION
Authors: Farmilo A. , Wilkinson F.
Published: January 2008

Abstract— Bimolecular rate constants for the quenching of singlet oxygen O*2(1Δg), have been obtained for several transition‐metal complexes and for β‐carotene. Laser photolysis experiments of aerated solutions, in which triplet anthracene is produced and quenched by oxygen, yielding singlet oxygen which then sensitizes absorption due to triplet carotene, firmly establishes diffusion‐controlled energy transfer from singlet oxygen as the quenching mechanism in the case of β‐carotene. The efficient quenching of singlet oxygen by two trans‐planar Schiff‐base Ni(II) complexes, which have low‐lying triplet ligand‐field states, most probably also occurs as a result of electronic energy transfer, since an analogous Pd(II) complex and ferrocene, which both have lowest‐lying triplet states at higher energies than the O*2(1Δg), state, quench much less effectively.
PHOTOCHEMISTRY OF FLAVINS—I. CONVENTIONAL AND LASER FLASH PHOTOLYSIS STUDY OF ALLOXAZINE
Authors: Dekker R. H. , Srinivasan B. N. , Huber J. R. , Weiss K.
Published: January 2008

Abstract— The photobleaching of alloxazine in buffered aqueous solution has been studied by means of flash photolysis using conventional and laser excitation sources. Several transient species have been characterized. The alloxazine triplet state (Λmax 420 nm and 550 nm, times; = 9 μs) was identified with the aid of low‐temperature comparison experiments in ethanol. Transient absorption with Λmax 440 nm, which appears after decay of the triplet state, and whose second‐order decay is pH‐dependent, is postulated to be due to the semiquinone radical (AH2*) and a radical derived from alloxazine by addition of water and loss of a hydrogen atom (HAOH*), which are in equilibrium with their conjugate cation radicals. The results of experiments in the presence of oxygen indicate that these species are not primarily formed from the triplet state. The enhanced second‐order decay of the flavin radicals in oxygen‐containing solutions is interpreted in terms of their reaction with the peroxy radicals. The proposed mechanisms account for the production of hydroxylated alloxazines.
THE BEHAVIOR OF DYE‐MUCOPOLYSACCHARIDE COMPLEXES—I. SPECTROSCOPIC STUDIES OF THE SYSTEM CHONDROITIN SULFATE A‐ACRIDINE ORANGE
Authors: Salter M. , Gentilcore P. , Fager R. S. , Kuntz G. P. P. , Abrahamson E. W. , Menter J. M. , West S. S.
Published: January 2008

Abstract—Absorption, fluorescence, and circular dichroism (CD) spectra have been obtained for a mucopolysaccharide—cationic dye complex. The dye acridine orange exhibits a blue shift in its absorption maximum and a red shift in its fluorescence maximum when mixed with chondroitin sulfate A in aqueous solution. The spectral shifts of the dye appear to be reversed by addition of salt, divalent cations being more effective than monovalent cations. The complex exhibits induced optical activity in the visible absorption spectrum of acridine orange. The biphasic nature of the CD curve is compatible with interpretations involving chromophore coupling.
DOSIMETRIC CONCEPTS IN PHOTOBIOLOGY*
Authors: Rupert Claud S.
Published: January 2008

Abstract—The effectiveness of an irradiation at non‐ionizing wavelengths for producing photochemical changes in a transparent sample can be characterized by any one of four different quantities. The utility of each depends on the information available about the sample and the kind of analysis intended. Nomenclature for these quantities is troubled. All four have been called “dose” in the literature, with or without modifying adjectives. In addition, incompatibility between the terminology for ionizing and non‐ionizing radiations leaves the concept of “dose” ambiguous in the vacuum ultraviolet. Rather than abandon the term altogether, nomenclature restricting its use is suggested here, together with measurement units and symbols for the quantities. The use of dosimetric quantities implies certain assumptions about the system being irradiated which are not always fulfilled.