A PHOTOLABILE PIGMENT FROM THE OCELLI OF SPIROCODON AN ANTHOMEDUSA

Abstract— The ocellar pigment of Spirocodon sdtatrix was extracted with 2% mildly alkaline cetyltrimethylammonium bromide (CTAB). The pigment is thermally unstable at pH values of higher than 5 and is a pH-indicator, Λ max being 480 mµ in strong acid, 430–50 mµ in neutral and mildly acid and alkaline, and 370–90 mµ in strongly alkaline solution. The pigment undergoes changes upon illumination, the maximum loss in density occurring at 490 mµ and the maximini gain, at 300–10 mµ. Formalin-treated samples become chloroform soluble, in which the pigment is still photosensitive. The Λ max of the maximum gain upon iIlumination is 310–20 mµ. The properties of the ocellar pigment resemble those of known visual pigments in some respects.     

THE EFFECT OF LIGHT ON HALOGENATED SALICYLANILIDE IONS

Abstract— Irradiation of the anions of halogenated salicylanilides with near ultraviolet light causes the halogen atoms substituted in the 3– or 5– positions to be replaced by hydrogen. With 3, 5 substituted salicylanilides the halogen substituted on the 3 position is lost; 5-substituted bromosalicylanilides lose the 5-bromo substituent. 5-substituted chlorosali-cylanilides do not lose the 5-chloro substituent. A free radical mechanism for the reaction is suggested.     

GENETIC AND PHYSIOLOGICAL STUDIES OF THE EFFECT OF LIGHT ON THE DEVELOPMENT OF THE MOSS, PHYSCOMITRELLA PATENS

The germination of Physcomitrella patens spores only occurs when wet spores are exposed to light. Depending on their ripeness, spores require from 44 to 64 h illumination to bring about maximum germination. There is a lag period of about 15 h between the reception of sufficient light to elicit germination before germination can be observed. Wavelengths in the range 640–64080 nm are much more effective in inducing germination than longer or shorter wavelengths, but far-red reversal of red light induction of germination has not been demonstrated. Light also has very marked effects on protonemal and gametophore development. In darkness, only caulonemata are produced, and these grow negatively geotropically. No new gametophores develop but existing gametophores grow negatively geotropically, etiolate and bear only scale leaves. In light, chloronemata, as well as caulonemata are produced, the former grow positively phototropically, while the latter grow at right angles to the direction of light, and neither cell type is sensitive to gravity. In the light, gametophores grow positively phototropically, are indifferent to gravity, produce large leaves and do not etiolate. All these responses to light by protonemata and gametophores are shown by cultures growing in a 23 h dark/l h red light cycle, but if this red light treatment is followed by 15min far-red light, the effect of the red light is reversed, indicating an involvement of phytochrome in the mediation of these responses. Mutants showing abnormal growth in the dark have been isolated, as well as mutants having abnormal phototropic responses. The latter type has lost the phototropic response of both the protonemal cell types, as well as of gametophores, indicating that these different responses may share a common component.     

THE EFFECT OF ULTRAVIOLET LIGHT ON THE CYCLIC NUCLEOTIDE SYSTEM OF HUMAN FIBROBLASTS

Abstract— The concentrations of cyclic AMP and cyclic GMP in human skin fibroblasts in culture were determined after exposing the cells to varying fluences of UV (254 nm) light. The cyclic nucleotide concentrations of cells irradiated in the log phase of growth were unchanged relative to controls. In contrast, there was a rise in the concentration of cyclic AMP in cells irradiated after they reached confluency. The increase in concentration was observed as early as 30 min after irradiation, reached a maximum of about 200% of control at 4 to 6 h after exposure, and returned to control values by 24 h after irradiation. The effect was proportional to a UV fluence from 5 to 20 J/m², and was blocked by the addition of the UV absorbing agent para-aminobenzoic acid. In contrast, our results indicated that UV light had no effect on the concentration of cyclic GMP in human fibroblast cell cultures. Because of the importance of cyclic nucleotides in the regulation of cellular function, it is reasonable to hypothesize that changes in cyclic AMP induced by UV light may affect the extranuclear functions of irradiated cells.     

THE EFFECT OF ENVIRONMENTAL LIGHT EXPOSURE ON DRUG-INDUCED PORPHYRIA IN THE RAT

Abstract— The porphyrinogenic drug, 3,5-diethoxycarbonyl 1,4-dihydrocollidine (DDC) when administered orally to rats evoked large increases in hepatic δ-aminolevulinic acid synthetase (ALAS) activity and hepatic protoporphyrin levels. These increases varied markedly according to light exposure patterns of the animals. DDC-treated animals continuously exposed for one week to fluorescent Blacklight lamps (Westinghouse FS-40) demonstrated a greater than two-fold increase in hepatic ALAS and a greater than threefold increase in liver protoporphyrin levels as compared to DDC-treated animals exposed to ambient light-dark cycling. Furthermore, the skin of porphyric animals continuously exposed to light showed larger increases in porphyrin content as compared to rats exposed to ambient light. These studies indicate that light exposure patterns can profoundly alter the activity of the hepatic heme pathway in the rat and suggest that light exposure could play a role in the production of drug-induced porphyria in man.     

INVESTIGATIONS ON BIOLOGICAL EFFECT OF POLARIZED LIGHT

Abstract— The biological effects of single and 4-time irradiation of primary human embryo fibroblasts with 4 J/cm² polarized light emitted by a halogen light source were investigated. The functional state of the plasma membrane was examined by means of lectin-binding and polycationized ferritin-binding techniques. It was established that the Con A binding of the cells did not change, whereas the number of negatively charged binding sites increased to a significant degree in relation to the untreated (control) samples and cell cultures exposed to diffuse (non-polarized) light. The micromorphological examinations showed no ultrastructural deviations. The quantitative increase of negative surface charges may be regarded as an indication of the biological effect of polarized light exerted on the cell membrane. The modifying effect of polarized light on the survival of E. coli exposed to the ionizing radiation was manifested in decreased anoxic radiation response.     

STUDIES ON LYSOZYME: EFFECT OF VISIBLE LIGHT ON THE CONFORMATION OF THE ENZYME IN THE PRESENCE OF METHYLENE BLUE

Abstract— Lysozyme undergoes conformational changes when exposed to visible light in the presence of methylene blue. Ultracentrifugation, gel filtration and end group analysis showed that no peptide bond was cleaved. About 30 per cent of the tryptophan residues were, however, modified. The enzymic activity decreased by 50 per cent. The sedimentation coefficient and helical content decreased; the extinction in the u.v. region between 185 to 210 nm increased. The photooxidized enzyme was more susceptible to trypsinolysis than the native enzyme.     

THE VISUAL PIGMENT CYANIDE EFFECT

The visual pigment of the Tokay gecko (Gekko gekko) with its in situ absorption maximum at 521 nm has its spectral position at 500 to 505 nm when chloride-deficient digitonin is used for the extraction. In this case the addition of chloride or bromide to the extract restores the maximum to 521 nm. This property, characteristic of gecko pigments in general, does not occur with any of the rhodopsins that have been tested. Simple salts of cyanide, a pseudohalogenoid with an ionic radius close to those of chloride and bromide and/or its hydrolysis product attacks both this gecko pigment and rhodopsins in the dark. This is seen as a slow thermal loss of photopigment if (sodium) cyanide is present at concentrations above 40 mM for the gecko pigment and 150 mM for the rhodopsins of the midshipman (Porichthys notatus) and of the frog (Rana pipiens). In all cases the loss of the photopigment is accompanied by the appearance of a spectral product with maximum absorption at about 340 nm. Cyanide addition has no effect on the photosensitivity of the native pigments and neither does it alter, as do chloride, bromide and other anions, the spectral absorbance curve. The spectral product at 340 nm also appears when the visual pigments are photolyzed in the presence of cyanide salts below the threshold concentrations given above. Incubation of digitonin-solubilized all-trans-retinal with (sodium) cyanide leads to a reaction product with absorption spectrum similar to that obtained with visual pigments under comparable conditions.(ABSTRACT TRUNCATED AT 250 WORDS)     

EFFECT OF DIETARY LIPID ON UV LIGHT CARCINOGENESIS IN THE HAIRLESS MOUSE

Abstract— Isocaloric feeding of diets varying in lipid content to albino hairless mice has shown that their susceptibility to skin tumorigenesis induced by simulated solar UV light was not affected by the level of polyunsaturated fat, 5% or 20%. However a qualitative effect of dietary lipid was demonstrated. Mice fed 20% saturated fat were almost completely protected from UV tumorigenesis when compared with mice fed 20% polyunsaturated fat. Multiple latent tumours were detected in the saturated fat-fed mice by subsequent dietary replenishment, suggesting that a requirement for dietary unsaturated fat exists for the promotion stage of UV-induced skin carcinogenesis.     

紫外光对邻菲罗啉亚铁离子为催化剂的B—Z反应影响的研究

1　引言在化学振荡研究领域,以多价态金属离子或其络合离子为催化剂的BZ反应的研究具有特殊的、重要的意义[1]。以[Fe(Phen)3]2 [Fe(Phen)3]3 (Phen代表邻菲罗啉)为催化剂的BZ反应的研究已有过一些报道[2-3],其中较详细的是文献[3]所做的工作,该研究在室内散射光条件下进...     

金属盐对轻质油品氧化脱硫效果的影响

过氧化氢与低分子醛的氧化体系可以氧化脱除轻质油品中的部分硫,金属盐作为助剂有利于提高油品的脱硫率,尤其对硫醇硫和硫醚硫的脱除。以氧化法分别对三种类型硫-硫醇硫、硫醚硫和噻吩硫的模拟轻质油品进行脱硫实验,并考察四种不同金属盐的助脱硫效果,研究发现助剂SnCl4的作用最为显著。本文还考察了助剂的不同加入比例对脱硫率的影响,结果表明,硫醚硫的脱硫率与SnCl4加入量的大小正比关系比较明显;硫醇硫仅表现于脱臭率的增加;噻吩的硫原子参与芳香环共轭,与金属离子较难络合,因此助剂的加入对其脱除并没有明显效果。     

激光散射研究单价盐对C8-卵磷脂胶团形成的影响

用激光散射测量确定C_8-卵磷脂临界胶团浓度及其随温度、盐离子的变化。从中导出了胶团分子量, 形成因子, 能量梯级间隔以及标准焓等反映该溶液内分子相互作用的重要参量, 从而导出单价盐调控胶团大小以至形成和解体的规律和方法。     

THE EFFECT OF INHIBITORS AND UNCOUPLERS OF PHOTOSYNTHETIC PHOSPHORYLATION ON THE DELAYED LIGHT EMISSION OF CHLOROPLASTS*

Abstract— Measurements were made of the 3.7 msec delayed light emission of chloroplasts treated with a variety of agents which affect the rate of electron transport (Hill reaction) or photosynthetic phosphorylation. The presence of the electron acceptors ferricyanide or pyocyanine increased delayed light emission. Inhibitors of electron transport (3-(3,4-dichlorophenyl)-1, -1-dimethylurea or 1,10(ortho)-penanthroline) inhibited delayed light emission. The addition of a phosphate acceptor system inhibited delayed light emission. This inhibition was reversed by inhibitors of the phosphorylation reaction, e.g. Dio-9 or phlorizin. From these results it was concluded that the 3.7 msec delayed light emission probably occurs as a result of back reactions of intermediates in the coupled electron transport and photosynthetic phosphorylation systems.     

THE EFFECT OF CYTOKININS ON GROWTH and PIGMENT ACCUMULATION OF RADISH SEEDLINGS (RAPHANUS SATIVUS L.) GROWN IN THE DARK and AT DIFFERENT LIGHT QUANTA FLUENCE RATES*

Abstract— The dependency of cytokinin effects upon irradiance was studied with radish seedlings ( Raphanus sativus L. cv. Saxa Treib). Kinetin (6-furfurylamino-purine) or BAP (6-benzylamino-purine) were applied via the roots of plants growing either in continuous darkness or under high (90 Wm^-2) or low intensity white light (10Wm^-2). Apart from the different development of plants at low and high fluence rates, the following cytokinin effects were found:
(1) Both cytokinins acted in a similar manner on growth characteristics and pigment accumulation at high and low light conditions, BAP being in many cases more effective than kinetin.
(2) When compared with the control, the cytokinins suppressed hypocotyl and root lengthening in the dark and light-grown plants. In darkness they led to increased cotyledon areas, whereas in the light the leaf expansion was suppressed.
(3) In the etiolated and low light grown plants, the anthocyanin content of the hypocotyls was enhanced due to the action of cytokinins, whereas under high light the anthocyanin accumulation was decreased.
(4) In the cotyledons of etiolated plants, more phototransformable protochlorophyll(ide) and more carotenoids were formed when cytokinins were present. In green leaves the carotenoid content was diminished due to the action of cytokinins, particularly in plants grown in strong light. The chlorophyll a/b ratio was increased in the cytokinin-treated plants in most cases.
The results suggest a light dependency of the cytokinin effects. It is believed that the response of a plant towards exogenously applied cytokinins is similar to that with high intensity light.