Detection and partial sequence of phytochrome genes in the ferns Anemia phyllitidis (L.)Sw (Schizaeaceae) and Dryopteris filix-mas L. (Polypodiaceae) by using polymerase-chain reaction technology.

Phytochrome controls several developmental steps during formation and differentiation of the fern gametophyte, including spore germination, morphogenesis of the gametophyte or differentiation of the sexual cells. To obtain information about the amino acid sequence and the regulation of phytochrome expression at the gene level, two degenerated oligonucleotides against well conserved amino acid regions were designed after an optimal alignment of the known phytochrome sequences. These primers were tested against DNA isolated from Arabidopsis thaliana, and the polymerase-chain reaction (PCR) products were cloned and sequenced. The DNA fragment produced with this method proved to be identical with a phytochrome-A-gene fragment from A. thaliana, and hence this fragment was used in further experiments to prove whether amplified DNA from fern species contains phytochrome-like DNA. With this procedure we successfully detected and cloned gene fragments both from gametophytes of Anemia phyllitidis and Dryopteris filix-mas, cultured for 7 days under vegetative conditions. In addition, poly(A)+ RNA was prepared from 7-day-old gametophytes of A. phyllitidis, induced to differentiate antheridia under generative conditions. This poly(A)+ RNA was transcribed into complementary DNA and used together with both phytochrome specific primers in a PCR experiment. We thereby obtained another DNA fragment. These data strongly suggest that A. phyllitidis has at least two phytochrome genes, and that at least one of them is expressed in light-grown gametophytes.     

INDEPENDENT EFFECTS OF PHYTOCHROME AND NITRATE ON NITRATE REDUCTASE AND NITRITE REDUCTASE ACTIVITIES IN MAIZE

Abstract— Involvement of phytochrome in the regulation of nitrate reductase (NR) and nitrite reductase (NIR) activities in excised, etiolated leaves of Zea mays (L.) variety 'Ganga-5' is demonstrated using low energy and high irradiance responses of phytochrome action. Photoreversibility by far-red light of red light stimulated increases in NR and NIR activities was lost by 2 h. Red light given to the leaves, when induction by NO^-₃, was saturated, further increased both enzyme activities. Even if red light was given 4–8 h before NO^-₃, it still increased both NR and NIR activities.     

PHOTOREGULATION OF NITRATE UTILIZATION IN GREEN ALGAE AND HIGHER PLANTS*

Abstract— Nitrate reductase from eukaryotes can be reversibly inactivated, blue light being an effective activating agent both in vitro and in vivo. Hydroxylamine proved to be a powerful inactivating agent of Ankistrodesmus braunii nitrate reductase. Irradiation with blue light of NH₂OH-inactivated nitrate reductase, specially in the presence of μM amounts of FAD, promoted the recovery of the enzyme activity. Similarly, photoexcited methylene blue reactivated spinach nitrate reductase. On the other hand, in vitro nitrate reductase is highly susceptible to photodynamic inactivation caused by singlet O₂. Aerobic incubation of the active spinach enzyme with either FMN or methylene blue under either blue or red light respectively led to its irreversible inactivation. Irradiation of frozen and thawed spinach leaf discs also promoted, in situ, an irreversible inactivation of nitrate reductase, provided that 6₂ was present in the incubation mixture. Thus, either in vitro or in situ, light can cause two quite different responses of nitrate reductase, its blue light-dependent photoactivation in a flavin sensitized reaction and its photodynamic inactivation in a singlet O₂-dependent process.     

PHOTOPHYSIOLOGY OF TURION GERMINATION IN Spirodela polyrhiza (L.) SCHLEIDEN–V. DEMONSTRATION OF A CALCIUM-REQUIRING PHASE DURING PHYTOCHROME-MEDIATED GERMINATION

Abstract— Etiolated turions of Spirodela polyrhiza are positively photoblastic and show a phytochrome-mediated low fiuence germination response. The far-red light (FR) reversibility decreased with the delay of FR irradiation (lag phase 1.06 ± 0.03 days after red light irradiation; half-maximal response 1.9 days). The action of the far-red-absorbing form of phytochrome (Pfr) was only realized by a germination response if exogenously applied Ca²+ was present. Calcium step-down (from 1 mM to 0.9 μ M Ca²+) and Ca²+ step-up (from 0.9 μ M to 1 m M Ca²+) experiments were carried out to determine the Ca²+-sensitive phase. There was no time gap between the two phases determined by the step-down and step-up experiments but a clear coincidence of both curves. Pulse treatments (24 h) with Ca²+ (1 m M ) showed the upper part of this common curve to represent the most Ca²+-sensitive phase. The Ca²+-sensitive phase was within the Pfr-requiring phase. After reversion of Pfr by FR pulses there was only a negligible response to the high Ca²+-concentration, independent of the delay between the red light (R) and FR pulses. These results are compatible with the assumption of Ca²+ acting as a second messenger of Pfr. However, the Ca²+-insensitivity in the first 12 h after the R pulse points against this hypothesis.     

EFFECT OF UVA AND BLUE LIGHT ON PORPHYRIN BIOSYNTHESIS IN EPIDERMAL CELLS*

Abstract— To study porphyrin biosynthesis in normal human keratinocytes and A431 cells derived from human epidermoid carcinoma, cultured cells were incubated with delta-aminolevulinic acid (ALA), the precursor of porphyrin synthesis, and accumulation of porphyrins was measured spectrofluorometrically. Both human keratinocytes and A431 cells accumulated porphyrins in a time-dependent and a dose-dependent fashion. Protoporphyrin was the predominant porphyrin accumulated by both cell types. Porphyrin accumulation was enhanced by Ca Mg ethylene-diaminetetraacetic acid, a ferrochelatase inhibitor, and the enhancement was reversed by the addition of iron, suggesting the utilization of iron by ferrochelatase. The effect of light on porphyrin accumulation was evaluated by exposing the ALA-loaded A431 cells to ultraviolet-A (UVA) and blue light radiation, followed by continued incubation with ALA for 2–48 h. There was an enhancement of porphyrin accumulation 2–48 h after the radiation as compared with nonirradiated controls. Consistent with this finding, ferrochelatase activity decreased in these cells at 24 h and 48 h. These data demonstrate that human keratinocytes and A431 cells are capable of porphyrin biosynthesis, and that exposure of porphyrin-containing A431 cells to light, which includes the Soret band spectrum, decreases the ferrochelatase activity, which is responsible, at least in part, for the further increase in porphyrin level.     

石墨炉原子吸收光谱法测定锡和锗时基体改进剂硝酸钙的作用

石墨炉原子吸收光谱法测定低温易挥发元素锡和锗时灵敏度较低。本文以硝酸钙为基体改进剂,使锡和锗的灵敏度分别比不加基体改进剂时提高9倍和50倍,同时也显著提高灰化温度,并降低原子化温度。本文也探讨了基体改进剂硝酸钙对锡和锗的增感机理。锡的增感是由于固相和气相中钙的作用,而锗的增感仅是气相钙的作用。     

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.     

RELATIVE IMPORTANCE OF BLUE LIGHT AND LIGHT ABSORBED BY PHYTOCHROME IN GROWTH OF MUSTARD (Sinapis alba L.) SEEDLINGS*

Abstract— Hypocotyl straight growth in mustard (Sinapis alba L.) responds very strongly and in precisely the same way to low fluence rate red (RL) and white light (WL). The effect of weak light can be attributed fully to light absorption by phytochrome. Only with increasing fluence rate an effect of blue light (BL) comes into play which cannot be explained by the action of phytochrome. However, this specific action of BL can be demonstrated in hypocotyl growth of mustard seedlings only up to 5 days after sowing (25°C). With older seedlings control of hypocotyl growth seems to be exerted exclusively via phytochrome. Regarding the far-red light dependent “high irradiance reaction” (FR-HIR) it was found that it plays a dominant role in growth of mustard only during a relatively short period. It tends to disappear in favor of a RL-HIR between 3 and 4 days after sowing. It is concluded that the seedling exhibits a largely endogenous temporal pattern of responsiveness to light. Phototropism of the mustard seedling can be elicited by low fluence rates (< 1 mW m^?2) of unilateral BL. This same light has no effect on straight growth. It is concluded that BL-dependent phototropic growth response of a hypocotyl and the effect of BL on longitudinal growth of the hypocotyl are unrelated phenomena.     

硝酸脲中酰胺态氮及总氮含量测定的研究

对硝酸脲中酰胺态氮及总氮含量进行测定。以甲醛－硫酸法分析硝酸脲中酰胺态氮时，发现酰胺态氮的含量总是与理论值相关差将近1倍。文中解释了造成这一结果的原因。并找到了导致这种结果的定量关系。从反应温度，时间等方面进行多次试验，找到了适宜的分析条件。     

EFFECT OF CHRONIC UV EXPOSURE ON EPIDERMAL TRANSMISSION IN MICE*

In connection with an investigation on UV-tumorigenesis in hairless mice, the question arose in what way the epidermal transmission changes under chronic UV exposure. At regular time intervals, epidermal sheets of these mice were optically probed, i.e. the specimen was irradiated perpendicularly to its surface with a collimated monochromatic beam of 313, 302 or 297 nm and the transmission was measured in forward direction and a small angle around it. The optical probe measurement was sensitive to epidermal changes and easy to perform; it correlated well with thickness and total transmission of the epidermal sheet. As a result it was found that over the dose range investigated the logarithm of the epidermal transmission at 297 nm was a simple linear function of the daily UV dose and the time of treatment. Calculations, in which this result is combined with data on UV-tumorigenesis over the same dose range, show that the change in epidermal transmission is sufficiently large to have an important bearing on the dose-response relationship for tumorigenesis by chronic UV exposure.     

Sm~(3 )在硼酸盐玻璃中的发光及Bi~(3 )对Sm~(3 )的敏化作用

早在六十年代,人们为了寻找较好的激光玻璃,曾对Sm~(3 )离子掺杂的玻璃中的光谱进行过研究。为了探寻新型的激光,发光玻璃,又进一步研究了Sm~(3 )在玻璃中的发光和敏化。我们以寻找一种高亮度,低成本的发光玻璃为目的,研究了基质玻璃组成,敏化离子及其浓度对Sm~(3 )发光性质的影响。 选择B_2O_3-BaO-M_mO_n(M_mO_n=Li_2O,Na_2O,K_2O,MgO,CaO,SrO)玻璃体系,所用原料的纯度皆为分析纯以上,用陶瓷坩埚在1250℃掺杂氧化钐(纯度均大于99％),玻璃的荧光谱和激发光谱,用MPF-4型荧光分光光度计测定。     

DIFFERENTIAL EFFECTS OF A DNA-SYNTHESIS MUTATION ON UV-INDUCED MUTATION YIELDS IN VEGETATIVE CELLS AND SPORES OF BACILLUS SUBTILIS

Abstract— The absorption and emission properties of the photochemically produced dipyrimidine adducts are analyzed at 300 and 77K. Those adducts which have a saturated C(5)—C(6) bond in the pyrimidin-2,4-dione (Pyr) ring and a pyrimidin-2-one (Pyo) ring behave spectroscopically as a substituted Pyo. However, those consisting of one Pyr and one Pyo moiety can be considered as bichromophoric molecules and their spectral properties can be understood in terms of the relative torsional angle between the two rings. The adduct with the most bulky substituents ortho to the torsional bond bears the largest torsional angle and exhibits relatively independent absorption and emission phenomenon. At the other extreme, those adducts with no substituents at this position exist as almost planar molecules and exhibit considerable overlap of absorption bands as well as room temperature fluorescence which, in certain cases, is characteristic of intramolecular exciplex interaction. Using inter-ring torsional angles of ortho-substituted biphenyl molecules as a basis for comparative calculation, quantitative estimates of the torsional angles in dipyrimidine adducts at 300K have been made.     

THE EFFECT OF DEUTERIUM OXIDE ON THE FLUORESCENCE AND PHOTOTRANSFORMATION OF 124 kDALTON PHYTOCHROME*

Abstract— To probe the nature of primary photoprocess and the mechanism of the phototransformation of undegraded 124 kDa oat phytochrome, solvent deuterium isotope effects on the fluorescence and phototransformation of phytochrome have been investigated. The fluorescence intensity and lifetime of phytochrome (P_r form) are greater in D₂0-buffer than in H₂O-buffer, suggesting a possible involvement of proton transfer in the primary photoprocess of phytochrome. Although the photostationary equilibrium (P_r to P_fr ratio) was not altered by deuterium oxide, in contrast to degraded phytochrome, the rate constants of both transformations, P_r→ P_fr and P_fr→ P_r were enhanced by up to 24%. The P_r to P_fr phototransformation of degraded phytochrome, however, was retarded by about the same percentage in D₂O. These opposite effects of D₂O with degraded and undegraded phytochromes underscore the fact that the P_r form from the former reverts to the P_r form in the dark, apparently catalyzed by deuterated general and/or conjugate acidic group(s). With the degraded phytochrome the deuterium oxide enhancement of the rate of dark reversion was approximately 2-fold (Sarkar and Song, 1981). Both the fluorescence intensity and the rates of phototransformation of phytochrome were enhanced in D₂O with successive photocyclings (P_r→ P_fr→ P_r→ P_fr→ P_r etc.) with alternating red and far-red irradiation. It has been proposed that successive photocycling of phytochrome in D₂O results in proton-deuteron exchange in the partially exposed P_tr chromophore and/or its surrounding amino acid residues.     

THE EFFECT OF LEVULINIC ACID ON THE LIGHT INDUCED DEVELOPMENT OF PHOTOSYSTEM I AND II ACTIVITIES IN GREENING MAIZE LEAVES*

Photosystem I and Photosystem II activities were measured in chloroplasts isolated after 0–20 h illumination from etiolated maize leaves in which chlorophyll synthesis was specifically inhibited by levulinic acid. In control leaves not treated with levulinic acid, Photosystem I activity/chlorophyll developed rapidly during the first 2h in light, then fell off, and reached a constant level after 6h of illumination. In levulinic acid treated leaves, in which chlorophyll accumulation was inhibited up to 60%, a similar initial rise in Photosystem I activity was observed. However, the decrease in activity was much slower and continued for at least 20 h. The development of Photosystem I activity calculated on a leaf fresh weight basis was similar for control leaves or leaves treated with levulinic acid. This indicates that development of Photosystem I activity may not be related to chlorophyll accumulation during greening. Photosystem II activity/chlorophyll in leaves treated with or without levulinic acid increased similarly during the first 6h and then remained constant. Activity of Photosystem II per leaf fresh weight increased linearly, after the first h, for 20 h in the control leaves; in levulinic acid treated leaves this development was reduced by about 60%. Thus, development of Photosystem II activity can be related to chlorophyll accumulation. SDS gel electrophoresis of plastid membranes from control leaves illuminated for 12 h showed the presence of chlorophyll-protein complex I as well as Chl-protein 11; in the case of levulinic acid treated leaves only Chl-protein complex I was detectable, while Chl-protein complex II was markedly reduced.     

EFFECT OF POLYMORPHISM ON THE LUMINESCENT PROPERTIES ON SILVER(I) NITRATE COMPLEXES WITH 2-AMINO-5-PHENYLPYRAZINE

Journal of Structural Chemistry - The reaction between AgNO3 and 2-amino-5-phenylpyrazine (L) at a molar ratio Ag:L&nbsp;=&nbsp;1.5:1 (synthesis time 3-4&nbsp;h) in the acetonitrile...     

β-(2,3-环氧丙氧基)-硝酸乙酯的合成及聚合

<正> 作者曾报道了2-硝基乙基缩水甘油醚的合成及其聚合,制得距主链较远的侧链带单硝基的端羟基聚醚。上述单体与四氢呋喃的共聚物用甲苯二异氰酸酯和甘油交联后所得胶片玻璃化温度-32℃。为了进一步改进低温性能,本文研究了一种新的带硝酸酯基的三元环醚单体β-(2,3-环氧丙氧基)-硝酸乙酯的合成及其聚合。单体的合成路线如下:     

PHOTOOXIDATIVE DESTRUCTION OF CHLOROPLASTS AND ITS EFFECT ON NUCLEAR GENE EXPRESSION AND EXTRAPLASTIDIC ENZYME LEVELS *

Abstract The cooperation between the nuclear and plastidic genome has been investigated extensively and it is generally accepted that plastidic development is controlled by the genetic information encoded in the nucleus (Ellis, 1981). It was discovered only recently that plastids are also involved in controlling extraplastidic events. If carotenoid-free plastids are destroyed by photooxidation. expression of plastidic proteins which are encoded in the nucleus is reduced or prevented. Thus is has been postulated that a signal which derives from the plastids controls the expression of these genes in the nucleus. Moreover, extraplastidic enzymes with functions related to intact plastids (such as nitrate reductase and peroxisomal enzymes) are also affected by this treatment, while (photo)morphogenesis and extraplastidic compounds not directly related to plastidic functions seem to be unaffected. Since the damage is restricted exclusively to the plastids and even the outer envelope membrane appears to be unimpaired, photooxidative destruction of carotenoid-free plastids is often used as a tool to investigate nuclear plastid interaction. This review briefly describes the events occurring during photodamage, analyzes the consequences for extraplastidic events, and discusses the implication of a plastidic signal(s) in controlling the expression of nuclear genes which code for plastidic proteins.