bluuebunny/crossref_metadata_2025_split huggingface dataset:
Convergent evolution between Echidnophora and Termitoxeniinae (Diptera: Phoridae)
Authors: DISNEY R. H. L. 
Published: January 2008

Abstract Echidnophora dondroi sp.nov. is described from females collected in the fungus gardens of a nest of the termite Odontotermes takensis in North Sumatra. Resemblances between Echidnophora and Termitoxeniinae are discussed and interpreted as examples of convergence. The peculiarly modified basal sockets of some major abdominal bristles in many Termitoxeniinae are illustrated and discussed. The hypothesis is advanced that these modified sockets are the sites from which exudates attractive to termite workers are discharged. It is further postulated that these exudates are primarily lipid material. Furthermore, the abdominal bristles of the Termitoxeniinae examined are smooth, in contrast to the fluted bristles characteristic of Echidnophora, other Phoridae, and those of workers of termite hosts of the Termitoxeniinae. This is probably an adaptation that renders the bristles more pliant, and thus less liable to being broken off when stroked by a termite worker. Enlarged collars, arising from the basal sockets and embracing the bases of the bristles, probably serve as an additional protection.
Phylogeny and distribution of the phoracanthine genus Atesta (Coleoptera: Cerambycidae) from Australia
Authors: WANG QIAO , NEW TIM R. , THORNTON IAN W. B. 
Published: January 2008

AbstractThe phylogeny of the phoracanthine genus Atesta (thirty‐four species) is analysed using cladistic methods. The monophyly of Atesta is confirmed. Three major monophyletic species groups are recognized: (1) the thorntoni‐group including twelve species: A.thorntoni, A.balteata, A.latifasciata, A.mediana, A.patula, A.newi, A.angasi, A.bifasciata, A.besti, A.ciliata, A.paratasmanica and A.tasmanica; (2) the sisyrioides‐group consisting of seventeen species: A.ibidionoides, A.carteri, A.longoelytrata, A.pubescens, A.stigmosa, A.sita, A.vittata, A.sparsa, A.minuta, A.tropicalis, A.unifasciata, A.sisyrioides, A.nigrihumerus, A.apicalis, A.brittoni, A.antennalis and A.brooksi, and (3) the houstoni‐group containing five species: A.mapida, A.houstoni, A.tripartita, A.dixoni and A.centroaustralica. The distribution patterns of Atesta are described and discussed. Five distinct areas of endemism are found for Atesta: the Torresian, Timorian, Kosciuskan, Western and Eyrean Subregions. The Torresian Subregion has nine species, three of which are endemic to the subregion; the Timorian has four species, two of which are endemic; the Kosciuskan has twenty‐three species, sixteen of which are endemic, the Western has five species, four of which are endemic, and the Eyrean has three species, one of which is endemic. Two kinds of distribution patterns for Atesta are identified: the wet adapted (peripherial), including the thorntoni‐group and sisyrioides‐group, and the wide‐adapted, consisting of the houstoni‐group. The thorntoni‐group is typically a southern Australian species group, distributed in south‐eastern and south‐western Australian continent and Tasmania. The sisyrioides‐group is mainly distributed in southeastern, eastern and northern Australian continent and Tasmania. The distribution of the houstoni‐group includes central and peripherial Australian continent.
PHOTOCHEMISTRY OF MODEL OLIGO‐ AND POLYNUCLEOTIDES—IV. HETERO‐OLIGONUCLEOTIDES AND HIGH MOLECULAR WEIGHT SINGLE AND TWIN‐STRANDED POLYMER CHATNS.*†
Authors: Wierzchowski K. L. , Shugar D. 
Published: January 2008

SummaryA study has been made of the photochemical transformations undergone by pyrimidine residues in a number of di‐, tri‐ and tetra‐nucleotides, and in high molecular weight single and twin‐stranded model polynucleotides. The results confirm and extend previous conclusions as to resistance of purines and indicate that one of the predominant reactions exhibited by uridylic and cytidylic acid residues is the reversible nucleophilic addition of water to the 5, 6 double bond of the pyrimidine rings. Results for poly‐A‐poly‐U provide an explanation for the apparent resistance of DNA to U.V. irradiation (as measured by changes in U.V. absorption spectra), due to the fact that photolysis of a uracil residue is accompanied by dissociation of the hydrogen bonds to the adenine of the A‐U base pair and the resultant reduction in hypochromicity partially compensates for loss of absorption of the uracil residue. Quantum yield calculations have been made for the various polymers. A tabulation is presented of data hitherto accumulated with regard to the photochemical behaviour of pyrimidines in nucleotide chains, as well as the kinetic constants for the reverse thermal reaction. Attention is drawn to the significance of the results with reference to models for biological thermal and photoreactivation. From a consideration of the quantum yields for pyrimidine residues in various types of nucleotide chains, it is concluded that energy transfer in nucleic acids, insofar as it exists, is not of primary importance in the production of photochemical lesions.
PRIMARY REACTIONS IN BACTERIAL PHOTOSYNTHESIS—II. THE QUANTUM REQUIREMENT FOR BACTERIOCHLOROPHYLL CONVERSION IN THE CHROMATOPHORE
Authors: Clayton R. K. 
Published: January 2008

SummaryReversible light‐induced alteration of a special component of bacteriochlorophyll (BChl,) is observed in bacterial chromatophores. The alteration involves bleaching of the long‐wave absorption band at 870–890 mp and a blue shift of the band at 800 mp. Assuming that the altered BChl, molecule loses all of its long‐wave absorption, and that the extinction coefficient of this band is equal to that of the corresponding band in the major component of BChl, a quantum requirement could be computed for the light‐induced change. It was found with most preparations that two to four quanta suffice for the alteration of one BChl, molecule, even in dried chromatophores at 1° K.This result is taken as supporting evidence for the importance of light‐induced BChl, conversion in photosynthesis. It also shows that BChl, is effective as an energy sink in the chromatophore.
RADIATION MEASUREMENT IN PHOTOBIOLOGY — CHOICE OF UNITS
Authors: Craig R.E. 
Published: January 2008

Abstract— The physical units most commonly used in photometry have limited value outside the field of illumination engineering. They tend also to conceal rather than display the physical concept of radiation as understood at present.Only by making the concepts of quantum theory accessible by a fundamental change of units, can those concepts make their full contribution to photobiology.The paper suggests adoption of the quantum as the unit of intensity and the electron volt as the specification of spectral quality, thus bringing the nomenclature of photometry into line with other branches of radiation physics. A start is made with definition of some of the essential derived units, source intensity, irradiation, and flux.
STUDIES ON FLAVINS IN ORGANIC SOLVENTS‐I*. SPECTRAL CHARACTERISTICS OF RIBOFLAVIN, RIBOFLAVIN TETRABUTYRATE AND LUMICHROME
Authors: Koziol Jacek 
Published: January 2008

Abstract— The absorption and fluorescence spectra of riboflavin, riboflavin tetrabutyrate and lumichrome have been studied in organic solvents of different polarity including ethanol, acetone, dioxane, pyridine, acetic acid and in cyclohexane‐dioxane mixtures. The molar extinction coefficients of the compounds were measured and the character of solvent sensitive changes observed in the absorption spectra are discussed. The effect of hydrogen bonding and/or intramolecular charge transfer complex are proposed as possible explanation.Changes in the shape of fluorescence emission spectra are less evident; in the case of riboflavin tetrabutyrate, mirror symmetry to the shape of the longest wavelength maximum was observed in low‐polar solvents. Quantum yields of fluorescence are higher the lower the polarity of the solvent used; the value for riboflavin tetrabutyrate is greater than for riboflavin. Changes were also observed in the fluorescence emission spectra of lumichrome in solvents of different polarity.Fairly good agreement was demonstrated for positions of the observed absorption maxima of riboflavin in 98% dioxane, riboflavin tetrabutyrate and lumichrome in 80% cyclohexane in mixture with dioxane and the values calculated from energies of molecular orbitals of flavins computed by B. Pullman and A. Pullman.
SPECTROSCOPIC ANALYSIS OF BACTERIOCHLOROPHYLLS IN VITRO AND IN VIVO*
Authors: Clayton Roderick K. 
Published: January 2008

Abstract— Chromatophores from Rhodopseudonionas spheroides were treated with potassium iridic chloride so as to destroy the major complement of bacteriochlorophyll (BChl) without harming the photochemically active P870. A band at 802 mμ, attributed to a pigment P800, survived this treatment along with P870. Extraction of such chromatophores with a mixture of acetone and methanol removed the absorption bands of P800 and P870; a corresponding amount of BChl was found in the extract. The yield of BChl was too great to have been derived from either P800 or P870 alone; analysis of extinction cofficients and band areas of these pigments indicates that they are both specialized fornis of BChl, in a molecular ratio of 2P800:1P870.Bleaching of P870, without attenuation of the absorption band of P800, could be effected by adding potassium ferricyanide to the iridic chloride‐treated chromatophores. Extraction of chromatophores in this condition gave a reduced yield of BChl, consistent with a 2:1 ratio of P800 to P870 under the assumption that the BChl in the extract was derived in this case from P800 alone.An absorption band at 600 mμ in iridic chloride‐treated chromatophores, characteristic of BChl and ascribed to P800 and P870, is partly bleached and shifted to shoiter wavelengths upon illumination. This reversible effect, and a similar one near 375 mμ (corresponding to the Soret band maximum of BChl), has the combined attributes of the blue‐shift of P800 and the bleaching of P870 seen in a spectrally resolved form near 800 and 865 mμ respectively. The 600 mμ band is bleached by about 30 per cent, again consistent with a ratio of 2P800:1P870.These data, in conjunction with information published elsewhere, support the view that two molecules of P800 and one of P870 are associated jointly with a photosynthetic reaction center.It was observed that the long wave absorption bands of BChl in vivo are sometimes narrower than the narrowest bands that have been observed for BChl in dilute organic solutions. Sharpness of these bands is most conspicuous in some forms absorbing near 800 mμ.
FLUORESCENCE FROM MAJOR AND MINOR BACTERIOCHLOROPHYLL COMPONENTS IN VIVO*
Authors: Clayton Roderick K. 
Published: January 2008

Abstract— In the photosynthetic bacteria Chromatium, Rhoahpirillum rubrum, and Rhodopseudomonus spheroides the fluorescence of bacteriochlorophyll is probably free of contamination by a “fast” component of delayed emission, judging from the characteristics of the delayed light measured 3 msec after excitation.In Rps. spheroides the pigment P870, associated with photochemical reaction centers, is non‐fluorescent in its photochemically active state. Fluorescence of P870 can be induced by either of two agencies that suppress its photochemical activity: exposure to Na2S2O4 and (in a dry chromatophore film) dessication.The yield of fluorescence from the major (light harvesting) component of bacteriochlorophyll in vivo is brought to a common maximum value by conditions that suppress the photochemical activity of P870. In addition to dessication and exposure to Na2S2O4 these conditions include saturating illumination and exposure to K3Fe(CN)6. Of these four treatments only the last two bleach the long wave absorption band of P870.These experiments support the following assertions:(1) P870 traps singlet excitation energy absorbed by the light harvesting BChl; the trapping function of P870 depends on its ability to initiate and participate in photochemistry.(2) Both dessication and exposure to Na2S2O4 suppress the photochemical activity of P870 by blocking an event that proceeds directly from the excited singlet state in P870.(3) The fluoresecence of BChl in vivo is emitted almost entirely by a major (light harvesting) component.
THE SPECTRUM OF BACTERIOCHLOROPHYLL IN VIVO: OBSERVATIONS ON MUTANTS OF RHODOPSEUDOMONAS SPHEROIDES UNABLE TO GROW PHOTOSYNTHETICALLY
Authors: Sistrom W. R. 
Published: January 2008

Abstract— The major blue pigment from a mutant of Rhodopseudomonas spheroides that is unable to grow photosynthetically has been compared with authentic bacteriochlorophyll. By the following criteria the pigments are identical: chromatographic behavior; visible and i.r. epectra of the pigments and of their Mg‐free derivatives in a varity of solvents; reaction in the Molisch phase test; isolation of phytol.The spectra in vivo in the region of bacteriochlorophyll absorption of the following strains grown under a variety of conditions have been compared:(a) wild‐type (strain Ga), (b) photosynthetically deficient mutant (strain PM‐8), (c) secondary mutants derived from PM‐8 lacking colored carotenoid pigments, and (d) carotenoid‐less, photosynthetically competent revertants from strains of type (c). It is concluded (1) that the spectrum of reaction center bacteriochlorophyll (P870) includes an absorption band at 805 mμ as well as at 870 mμ and (2) that the relative heights of the three absorption bands of bulk bacteriochlorophyll (at 805, 850 and 875 mp) are strongly influenced by the presence of P870.
LIGHT‐INDUCED ELECTRON TRANSFER BETWEEN CHLOROPHYLL AND HYDROQUINONE AND THE EFFECT OF OXYGEN AND β‐CAROTENE
Authors: Fujimori Eeji , Tavla Maria 
Published: January 2008

Abstract— Light‐induced electron spin resonance (ESR) absorption is not observed in degassed benzene solutions of chlorophyll a with hydroquinone. In the presence of methanol, however, the characteristic hyperfine pattern of p‐benzosemiquinone ion radical is formed. This photo‐reduction of chlorophyll a by hydroquinone is enhanced apparently by a small amount of triethylamine and inhibited by β‐carotene.Chlorophyll excited in the presence of oxygen produces a single broad ESR signal in benzene solutions which is enhanced by hydroquinone and quenched by β‐carotene, alcohol, and a mine. Their quenching effect is in parallel with their inhibition of the photoauto‐oxidation of chlorophyll. The high quenching capacity of triethylamine for this ESR signal is reduced by the addition of β‐carotene. In methanol solutions, the initial production of the single broad signal is followed by gradual development of the hypertine structure of p‐benzo‐semiquinone ion radical. This development can be accelerated by triethylamine. The mechanism of these changes is discussed on the primary interaction of excited chlorophyll with oxygen.
THE EFFECT OF ULTRAVIOLET RADIATION UPON OSMOREGULATION IN PARAMECIUM*
Authors: Saier F. L. , Giese A. C. 
Published: January 2008

Abstract Paramecium multimicronucleatum was irradiated with U.V. in solutions of differing osmotic pressures and ionic content. The rates of contraction and the diameters of the anterior contractile vacuoles were measured and changes in the volumes of solution entering the contractile vacuoles upon U.V. irradiation for paramecia maintained in solutions of differing ionic content were calculated. The volume of fluid entering the contractile vacuoles of paramecia irradiated (1) in standard balanced salt solution (SBSS) was regulated by a compensatory mechanism at lower U.V. doses but increased after relatively large U.V. doses; (2) in distilled water, increased after much smaller U.V. doses; (3) in isotonic balanced salt solution, showed little change upon irradiation.Increased osmotic pressure (with added sucrose) was found to reduce u.v.‐induced blistering of the pellicle, but in general U.V. damage was similar to that of paramecia in solutions of identical ionic content but lacking sucrose. Paramecia in SBSS with added sucrose to make it isomotic to the interior of the cell ruptured only after doses larger than for paramecia in SBSS lacking sucrose. Cell rupture of paramecia in solutions containing high CaCl2 concentrations generally occurred later than for those in SBSS. High KCI concentration (unbalanced salt solution) in the presence of high CaCl2 concentration provided some protection from U.V. irradiation to the paramecia. High NaCl concentration (unbalanced salt solution) in the presence of high CaCl2 concentration appeared to increase u.v. damage to paramecia. Paramecia were most resistant to u.v. irradiation, as judged by the above criteria, when present in balanced salt solution enriched with calcium, thus simulating pond water.
QUANTITATIVE SPECTROFLUORIMETRY‐THE FLUORESCENCE QUANTUM YIELD OF QUININE SULFATE
Authors: Eastman J. W. 
Published: January 2008

Abstract— By idealizing the design of a typical spectrofluorimeter that measures fluorescence from dilute solutions, we are able to derive an equation that predicts the dependence of the observable amplitude on the concentration of the solute and on several instrumental parameters. The result of the derivation, the fluorescence function, is used together with measurements of rhodamine B fluorescence and colloidal silica scattering to calibrate a spectrofluorimeter.The fluorescence function and the calibration data are used to determine the absolute fluorescence quantum yield of quinine sulfate in 0–1 N H2 So4. The results, Ø250=0.582 with excitation at 250 mμ, adn Ø350=0.577 with excitation at 350mμ. agree well with the previous evaluation of Melhuish, Ø345=0.546.
LA PHOTOOXYDATION DU GROUPE PEPTIDE—II. PEPTIDES ET POLYAMINOACIDES A L‘ÉTAT SOLIDE*
Authors: Meybeck A. , Meybeck J. 
Published: January 2008

Abstract— The determination of glyoxylic and pyruvic acids in oligo‐and poly‐, glycine and alanine shows that the peptide group is photooxydized, probably with the radical ‐NH‐CR‐CO‐ as an intermediate.The characterisation of pyruvic acid in glutathione and oxydized glutathione confirms the photolysis of the C‐S bond in combined cysteine and cystine.Finally, a comparison of the photoreactivity of peptides of the types aliphatic amino acid‐aromatic amino acid and aromatic amino acid‐aliphatic amino acid allows us to propose a selective mechanism for the transfer of excitation energy from the phenyl group to the preceding amino acid residue in the polypeptide chain.
EXCITATION TRANSFER BY CHLOROPHYLL a IN MONOLAYERS AND THE INTERACTION WITH CHLOROPLAST GLYCOLIPIDS*
Authors: TROSPER T. , PARK R. B. , SAUER K. 
Published: January 2008

AbstractIn mixed monolayers with purified chloroplast glycolipids and other colorless lipids, chlorophyll a fluorescence exhibits a decrease in quantum efficiency with increasing chlorophyll concentration. The fluorescence, which is strongly polarized in dilute films, becomes progressively depolarized as the area fraction of chlorophyll increases, and it is completely depolarized in a pure chlorophyll a monolayer. The observed behavior is consistent with an inductive resonance mechanism of energy transfer among the chlorophyll molecules with a critical transfer distance of 20–90 Å, depending on the model chosen for the energy transfer mechanism.The purified glycolipids–mono‐and digalactosyl diglycerides and sulfoquinovodiglyceride–separately form stable, compressible monolayers of the liquid‐expanded type on an aqueous subphase and in an atompshere of nitrogen. At maximum compression the three glycolipids occupy areas of 55, 80 and 47 A2‐molecule‐1, respectively, in the monolayer. Mixed monolayers of chlorophyll a with, separately, the monogalactolipid and the sulfolipid behave upon compression as two‐dimensional solutions. The fluorescence polarization at high chlorophyll concentrations in mixed monolayers indicates that several of the lipid diluents facilitate local ordering of the pigment molecules.
LIGHT‐INDUCED CHANGES IN CYTOCHROME b‐559 IN SPINACH CHLOROPLASTS
Authors: HIND G. 
Published: January 2008

Abstract— In isolated spinach chloroplasts, the reduction of cytochrome b‐559 by System II and its oxidation by System I can be observed when electron acceptor concentration limits System I activity and when one of a particular class of uncoupling agents is present. This class includes CCCP, desaspidin, Triton X‐100 and antimycinA; but not simple amines or atebrin.The effect of the uncoupler is to speed the cytochrome b‐559 oxidation rate. In addition, the rate of the off‐response of the light‐induced P518 absorbance change is increased. To explain these findings, an electron transfer scheme is proposed having two distinct pathways between System II and System I.
AN IDENTIFICATION OF THE RADICAL GIVING RISE TO THE LIGHT‐INDUCED ELECTRON SPIN RESONANCE SIGNAL IN PHOTOSYNTHETIC BACTERIA
Authors: BOLTON JAMES R. , CLAYTON RODERlCK K. , REED DAN W. 
Published: January 2008

Abstract— A reaction‐center fraction isolated from Rhodopseudomonas spheroides chromatophores exhibits light‐induced changes in its optical and electron spin‐resonance (ESR) spectra. In particular, a bleaching at 870nm (P870) has been found to be closely correlated with the appearance of an ESR signal with a g factor of 2.0025 and a peak‐to‐peak line width of 10 G. The ESR signal is indistinguishable from light‐induced signals found in chromatophores or whole cells.A careful measurement of the spin concentration showed that the ratio of the light‐induced spins to bleached P870 molecules is 1.1 ± 0.1. In addition the formation and decay kinetics are identical within experimental error under a variety of experimental conditions.Previous work has shown that P870 is a bacteriochlorophyll molecule in a specialized environment and that the bleaching signifies oxidation. The present work provides strong evidence that the photo‐bleaching of P870 produces the radical cation of bacteriochlorophyll, P870+, and that this radical is the source of the ESR signal in whole cells.The quantum yield for the bleaching of P870 in reaction centers has been measured, using actinic light of wavelengths 880, 800, 760 and 680 nm. For light absorbed at 880 or 800 nm the efficiency is close to 100 per cent. In a coupled reaction, the oxidation of mammalian cytochrome c by P870+ proceeds with nearly the same efficiency.The above results place definite limits on the possibilities for the identity of the primary acceptor. These possibilities are discussed.
FAR‐RED INDUCED, LONG‐LIVED AFTERGLOW FROM PHOTOSYNTHETIC CELLS. SIZE OF AFTERGLOW UNIT AND PATHS OF ENERGY ACCUMULATION AND DISSIPATION
Authors: BJÖRN L. O. 
Published: January 2008

Abstract— –Small amounts of N‐methyl phenazonium methosulphate (PMS) added to a suspension of Chlorella pyrenoidosa accelerate the emission of the long‐lived far‐red induced afterglow without greatly changing the amount of light emitted. The effect is noticeable in dilute suspensions at a PMS concentration of 10‐9M. The concept of afterglow unit is introduced and defined as that part of the sample in which the rate of energy reemission can be controlled by a single molecule of PMS. The number of chlorophyll molecules per afterglow unit is about 105. It is possible that the afterglow unit is identical to the thylakoid.The rate constant for the final first order decay phase of afterglow at room temperature is about 0.7 min‐1 without PMS and about 3 times larger for a unit with one PMS molecule.Diuron (DCMU) lowers the rate of afterglow decay. Desaspidin on the other hand decreases the amount of light emitted without affecting the decay rate. Carbonylcyanide‐m‐chlorophenyl hydrazone (CCCP) decreases the afterglow over the whole time‐range and increases the decay rate. A kinetic model is developed to account for the results.