PHYTOCHROME AND EFFECTS OF SHADING ON GROWTH OF WOODLAND PLANTS

qrowth of Circaea lutetiaim plants was studied in various locations in or near a mixed deciduous woodland. Morphological changes resulting from increased shading included increases in leaf area ratio, specific leaf area and specific water content. Parallel measurements with a spectroradi-ometer confirmed that shading involved a reduction in both light fluence rate and light quality (e.g. red/far-red ratio). Phytochrome P_fr/P status was also studied by spectrophotometric measurements on Avena seedling test material and by biological (Lactuca seed germination) assay. Attempts were made to demonstrate phytochrome controlled changes in plant morphology under controlled environment, using both end-of-day far-red treatment and far-red enrichment of the main light period. Effects of natural shading were most clearly simulated by varying light fluence rate while maintaining a constant but high red/far-red ratio     

ON THE PHYSIOLOGICAL SIGNIFICANCE OF DARK REVERSION OF PHYTOCHROME IN THE MUSTARD SEEDLING

Abstract —We present physiological evidence using the threshold control of lipoxygenase synthesis† by P_fr in the mustard seedling (LOG response) that there is no dark reversion of phytochrome
which would be relevant for this response. Such Ptr which can be detected with the lipoxygenase response disappears exclusively through degradation with a half-life of 45 min at 25°C. De novo synthesis of P*_r in the hypocotylar hook takes place at a constant rate (zero order rate constant) irrespective of the level of P_r or P*_tot, i.e. there is no detectable feedback control of P_r synthesis during the period of experimentation. The data of the present paper are consistent with a quantitative phytochrome model (Scheme 1) which has been advanced and treated quantitatively in the companion paper (Oelze-Karow and Mohr, 1976).     

QUANTITATIVE CORRELATION BETWEEN SPECTROPHOTOMETRIC PHYTOCHROME ASSAY AND PHYSIOLOGICAL RESPONSE

Abstract— Apparent synthesis* of the enzyme lipoxygenase in the cotyledons of the mustard seedling (Sinapis alba L.) is controlled by phytochrome (P_{fr ground state})? through a threshold (all-or-none) mechanism. This response was used to determine physiologically the photostationary states, Λ that is, the [P_fr]/[P_tot] ratios established by different wavelengths in the red and far-red range of the spectrum, including the standard red and far-red sources used in this laboratory (Mohr, 1966). Under the premises (for which justification has been given on previous occasions) that the [P_fr]/[P_tot] ratio for standard red light is 0.8, and that the decay of P_fr is a first-order process with a half-life of 45 min, the [P_fr]/[P_tot] ratios determined physiologically by means of the lipoxygenase response agree with the [P_fr]/[P_tot] ratios determined spectrophotometrically by Hartmann and Spruit (cf. Fig. 9 in Hanke et al., 1969) in hypocotyl hooks of mustard seedlings. In the hook the _fr, that is, the [P_fr]/[P_tot] ratio for standard far-red, is found to be 0.023. In the cotyledons, this ratio is several times higher (Schafer et al., 1972). The conclusion that apparent lipoxygenase synthesis in the cotyledons is controlled by phytochrome located in the hook has been substantiated by further spectrophotometric (Schäfer et al., 1973) and physiological experiments (H. Oelze-Karow and H. Mohr, in preparation). The minimum steepness of the threshold was determined. An increase of the P_fr level from 118 (relative units) to 130 leads to an instantaneous and total suppression of apparent lipoxygenase synthesis; a corresponding decrease from 130 (relative units) to 118 leads to an immediate resumption of apparent LOG synthesis at full speed. It is concluded that an explanation of the experimental facts requires a cooperative effect on the level of P_fr, a high degree of synchrony on the cellular and organismic level and rapid communication between the hypocotyl hook and the cotyledons. *The term ‘apparent synthesis’ is used operationally in the present paper to denote any increase of enzyme activity, although de novo synthesis of lipoxygenase has not so far been rigorously demonstrated. The usual inhibitor experiments (cf. Oelze-Karow et al., 1970) have led to the conclusion that intact RNA and protein synthesis is required for an increase of lipoxygenase activity.     

PHYTOCHROME INTERMEDIATES IN VIVO-I. EFFECTS OF TEMPERATURE, LIGHT INTENSITY, WAVELENGTH AND OXYGEN ON INTERMEDIATE ACCUMULATION

Abstract— Accumulation of weakly absorbing phytochrome intermediates has been demonstrated in Pisum epicotyl tissue under conditions of pigment cycling using a quasi-continuous measuring spectrophotometer. An action spectrum shows 690–700 nm to be the most efficient wavelength range in this process. Difference spectra for the decay of intermediates maintained by 690 nm light show that, if the experiment is done at 0°C, only P_fr is formed. At – 11°C, intermediates decaying to P_r can also be observed. At – 20°C, P_r is produced as well as a pigment with peak absorption at 710nm. Kinetic analysis of intermediate decay at – 11°C reveals that at least two intermediates are maintained by 690 nm light. The level of intermediate maintained by incandescent light at 0°C was 25% higher in air than in nitrogen.     

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.     

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.     

EXTENSION GROWTH AND ANTHOCYANIN RESPONSES OF PHOTOMORPHOGENIC TOMATO MUTANTS TO CHANGES IN THE PHYTOCHROME: PHOTOEQUILIBRIUM DURING THE DAILY PHOTOPERIOD

Four genotypes of tomato (Lycopersicon esculentum Mill.) in the genetic background ‘Aha Craig’ were used: an aurea (au) mutant, deficient in the bulk light-labile phytochrome pool; a high pigment (hp) mutant, showing exaggerated phytochrome responses at the time of de-etiolation; the au,hp double mutant and the isogenic wild type (WT). A dramatic increase in plant height resulting from an increase in the length of all internodes for each of the genotypes studied was observed upon reduction of the red light: far-red light photon ratio (R:FR) from 6.90 to 0.13 by addition of FR for the whole photoperiod. A concomitant increase in leaf length was also observed. Since au and au,hp mutants, deficient in the bulk light-labile phytochrome pool, respond to this reduction in the R:FR these data demonstrate that the phytochrome pool that mediates this response is present and fully functional. Anthocyanin was detectable in the comparably developed young growing leaves of the WT and hp mutant under the high R:FR, but not in the au and au,hp mutants, suggesting that the potential for anthocyanin synthesis is correlated with the presence of the bulk light-labile phytochrome pool. The kinetics of anthocyanin decrease in the young growing leaves were investigated in the hp mutant and the results suggest a very rapid cessation of flavonoid biosynthesis upon reduction of the R:FR. The functions of different phytochrome types are discussed.     

某些噻唑偶氮苯酚类试剂结构与性能关系的理论研究

噻唑偶氮试剂广泛应用于分析化学,近十来年发展较快,迄今已有170余种,但其结构和性能关系的理论研究报导较少。本文选取2-(2-噻唑偶氮)苯酚(简称TAP)及其九种甲基取代衍生物(见表1),用CNDO/2方法研究其结构与碱性关系,讨论这些试剂与金属离子螯合的可能位置,其结果和实验基本一致。计算分子构型所用TAP骨架取由文献,甲基用标准构型。原子编号见图1,计算在IBM PC/AT微机上完成。     

SOME EFFECTS OF LIGHT ON LEAF GROWTH IN PISUM SATIVUM AND TROPAEOLUM MAJUS

Abstract— The effect of wave-length of light on leaf expansion in Tropaeolum majus 'Double Orange Gleam' and Pisurn sativum 'Meteor' has been studied. In both species leaf growth is strongly promoted by light.
Increasing the daily duration of exposure to light increased leaf expansion in Tropueolum in both blue and red wave-bands over a range of light intensities. In Pisum a similar effect of ail increase in duration of irradiation was found over the whole range of intensities used for blue light but only at the highest intensity for red light: at the two lower intensities in red an increase in duration of the light treatment beyond 1 hr did not increase leaf expansion.
In both species a period of 4 hr of blue followed by 4 hr of red promoted leaf growth more than 4 hr of red followed by 4 hr of blue. The effect of a 4 hr period of red light was largely prevented when it was followed by far-red; the effect of 4 hr of blue light, on the other hand, was not affected by subsequent exposure to far-red.
It is concluded that leaf growth in Pisum and Tropaeolum is dependent not only on the 'low-energy' red/far-red reversible reaction but also on one or more 'high-enerFy' photo-reactions.     

拉伸热历史对取向聚对苯二甲酸乙二酯膜在热处理过程中收缩和伸长的影响

The effects of drawing temperature and draw ratio on the contraction and extension of oriented amorphous PET film during thermal treatment has been studied. It has been shown that considerable thermal contraction of the oriented PET film before crystallization is due to relaxation of molecular chains in global sense while the spontaneous extension is related to crystallization of the oriented PET film. The maximum amount of contraction of the oriented PET film during thermal treatment increased with increasing λfor λ>2.3,owing to faster crystallization rate of PET film in highly oriented state. The maximum extension exibits similar behavior as that of maximum contraction with increasing λ and showed a peak at λ≌ 3.3,which isalmost the same draw ratio above which the densityof PET film began to increase during drawing.     

EFFECTS OF N-PHENYLIMIDE S-23142 AND N-METHYL MESOPORPHYRIN IX ON THE SYNTHESIS OF THE PHYTOCHROME CHROMOPHORE IN PEA EMBRYONIC AXES

Abstract Treatment of imbibed embryonic axes taken from seeds of Pisum sativum with N-phenylimide S-23142, a herbicide that has been suggested to inhibit protoporphyrin synthesis, or with N -methyl mesoporphyrin IX, an inhibitor of the iron chelatase for heme, resulted in a significant decrease in the amount of spectrophotometrically detectable phytochromc in the axes in both cases. However, the amount of immunochemically detectable phytochrome was not affected by either treatment. If S-23142 inhibits the synthesis of protoporphyrin IX in pea, it appears that the conversion of protoporphyrinogen IX to protoporphyrin IX is involved in the biosynthesis of the phytochrome chromophore. The conversion of protoporphyrin IX to heme (Fe-protoporpbyrin) also appears to be a step in the biosynthesis of the chromophore, since N -methyl mesoporphyrin IX prevented the synthesis of spectrophotometrically detectable phytochrome but did not affect the magnesium chelatase activity required for the synthesis of chlorophyll in pea embryonic axes. The results suggest that protoporphyrinogen IX, protoporphyrin IX and heme are intermediates in the biogenesis of the phytochromc chromophore. The pathway to phytochromobilin might become fixed after protoporphyrin IX, being directed toward the Fe branch for heme rather than to the Mg branch for chlorophyll.     

拉伸热历史对取向聚对苯二甲酸乙二酯膜在热处理过程中收缩和伸长的影响

弄清取向非晶态聚合物在热处理过程中的收缩和伸长的变化规律,以及所对应的结构变化,有较大的实用意义和科学意义。 对于取向聚对苯二甲酸乙二酯的热收缩和热伸长已有很多研究,但对于拉伸热历史对取向PET在热处理过程中的尺寸变化的影响尚缺乏系统的研究。在热拉伸的过程中发生分子链的取向、热弛豫和结晶三个相互竞争的过程。因此,改变拉伸条件可以得到具有各种不同取向和结晶的PET试样。当非晶态PET膜片在80-105℃以较低     

THE EFFECTS OF FAR ULTRAVIOLET RADIATION ON RESPIRATION AND CATION ACCUMULATION BY ISOLATED MITOCHONDRIA OF PHASEOLUS VULGARIS

Abstract. The respiration rates and respiratory control ratios of isolated bean mitochondria have been measured following exposure to 0, 150, 300 and 900 J/m² of far UV radiation (190–300 nm) from a mercury vapour light source with 90% total radiant intensity at 254 nm. Loss of respiratory control occurred at 150 J/m² and inhibition of respiration was significant at the highest exposure dosage. The uptake of both ⁴⁵Ca and ⁸⁵Sr have been measured following a 10min incubation of isolated mitochondria with 2 m M cation. Significant decreases in cation accumulation were observed following exposure to 900 J/m². The effect seemed to be associated with loss of active transport of the ions as a result of respiratory uncoupling or reduced electron transport. There was no significant effect of storage on respiration or ion transport nor was there any indirect effect of irradiated suspending medium on mitochondria.     

EFFECTS OF STRUCTURE ON GROWTH HABITS AND DEFECTIVE FORMATION IN CRYSTAL OF TRI-HYDROXYMETHYLAMINO-METHANE(TAM)

<正> The effects of structure on the growth habits and defective formation in the crystal of Tri-hydroxymethylaminomethane(TAM) have been studied experimentally and structurally. Dependence of orientations and properties in O - H...O and O - H....N hydrogen bridges on the polar growth and on the face development, and relationship between the structural channels in open structure and defective formation, have been dis cussed briefly.     

COMPARISON OF EFFECTS OF UVA, UVB AND UVC ON GROWTH AND VIABILITY OF MITOGEN-STIMULATED HUMAN PERIPHERAL BLOOD CELLS

Abstract— Peripheral blood mononuclear cells were irradiated with UVA, UVB or UVC. The highest exposure dose used in each waveband reduced the number of viable cells to one-third the control cell population after 3 days in culture. Exposure of these cells to half as much UV from each waveband resulted in an equivalent or greater degree of inhibition of their proliferative response to mitogen as measured by lymphoblast transformation, [³H]-thymidine uptake and viable cell number on day 3 in culture. The pattern of inhibition was distinct for each waveband. UVA interfered with blastogenesis on the first 2 days of culture at doses which had considerably less effect on viable cell number. UVA also depressed the first round of DNA synthesis, which was detectable on the second day of culture. By day 3 in culture, however, the UVA-induced reduction in both the number of lymphoblasts and the uptake of [³H]-thymidine was a direct reflection of reduced numbers of viable cells. UVB did not interfere with blastogenesis in mitogen-stimulated cultures to the same degree as did UVA. Only the highest dose of UVB depressed blast transformation more than viable cell number on day 1; by day 2 lower doses were also inhibitory. In contrast UVC had little effect on blastogenesis at any time; a reduced number of lymphoblasts observed on days 2 and 3 in culture was a direct reflection of a reduced number of viable cells rather than a reduced percent of these cells undergoing blast transformation. As with UVA-irradiated, mitogen-stimulated cells, [³H]-thymidine uptake was also depressed in both UVB and UVC irradiated, mitogen-stimulated cells on day 2. However, only UVB continued to depress DNA synthesis more than viable cell number after 3 days of culture. These results suggest that UVA, UVB and UVC may interfere with any one or more of the signals involved in the response to mitogen, be they the recognition of mitogen by T cells or accessory cells, the transformation of lymphocytes into lymphoblasts or the activation of lymphoblasts to synthesize DNA.     

DIFFERENTIAL EFFECTS OF TRYPTOPHAN PHOTOPRODUCTS AND H2O2 ON THE GROWTH OF MOUSE EMBRYONIC FIBROBLASTS*

Abstract. Exposure of dilute solutions of L-tryptophan in balanced salt mixtures to near-ultraviolet light (ca. 320–390nm) yield several photoproducts capable of inhibiting the growth of cultured mouse embryonic fibroblasts. Recent literature suggested a need to test the possibility that the major toxic photoproduct is hydrogen peroxide, and therefore several lines of experimentation were pursued. On the basis of chemical and morphological studies and an analysis of the uptake of ³H-thymidine by these cells and its incorporation into their DNA, it is concluded that sufficient hydrogen peroxide could not be generated without the addition of high concentrations of oxygen to influence the growth or DNA synthesis of mouse embryonic fibroblasts.     

EFFECTS OF NH4CI ON THE INTERACTION BETWEEN POLY(ETHYLENE OXIDE)AND IONIC SURFACTANTS IN AQUEOUS SOLUTIONS

The interaction of poly(ethylene oxide)(PEO)with the ionic surfactants,sodium dodecylsulfate(SDS)and cetyltrimethylammonium chloride(CTAC)respectively,in aqueous solutions containing a certain concentration of NH4Cl,is studied by the viscosity measurement.It has been found that the ion-dipole interaction between PEO and ionic surfactants is changed considerably by the organic salt.For anionic surfactant of SDS,the addition of NH4Cl into solution strengthens the interaction between PEO and the headgroup of SDS.On the other hand,for cationic surfactant of CTAC,the interaction between PEO and the headgroup of CTAC is screened significantly by NH4Cl dissolved in solution.These findings may potentially be attributed to the negative property of the oxygen group of the PEO chain.In the presence of NH4Cl,the cationic ions of the organic salt bind to the oxygen group of the PEO chain so that PEO can be referred to as a pseudopolyelectrolyte in solution.     

EFFECTS OF NH_4Cl ON THE INTERACTION BETWEEN POLY(ETHYLENE OXIDE) AND IONIC SURFACTANTS IN AQUEOUS SOLUTIONS

The interaction of poly(ethylene oxide)(PEO)with the ionic surfactants,sodium dodecylsulfate(SDS)and cetyltrimethylammonium chloride(CTAC)respectively,in aqueous solutions containing a certain concentration of NH_4Cl, is studied by the viscosity measurement.It has been found that the ion-dipole interaction between PEO and ionic surfactants is changed considerably by the organic salt.For anionic suffactant of SDS,the addition of NH_4Cl into solution strengthens the interaction between PEO and the headgrou...     

INFLUENCE OF THE POOL SIZE OF THE XANTHOPHYLL CYCLE ON THE EFFECTS OF LIGHT STRESS IN A DIATOM: COMPETITION BETWEEN PHOTOPROTECI'ION AND PHOTOINHIBITION

Abstract In a study of the relationship between nonphotochemical quenching of fluorescence and the xanthophyll cycle, we show that the diatom Phaeodactylum tricornutum exhibits several interesting characteristics. This xanthophyll cycle consists of only one reversible epoxidating/deepoxidating step (diadinoxanthiddiatoxanthin). Diadinoxan-thin, which increases from 8 to 17 molecules/100 chlorophyll a (Chl a ) during the ageing of the culture, was present as two separate pools, with a portion (of about 5 molecules/100 Chl a) which was never deepoxidated. Under a defined irradiance, the time necessary to abolish net photosynthesis increases with the pool size of diadinoxanthin available for deepoxidation. A close correlation is found between nonphotochemical quenching and the relative ratio of diatoxanthin until the photosytem II center is inactivated. The photoprotective effect of diadinoxanthin deepoxidation is limited to the phase during which quenching of the minimum fluorescence (F₀) develops.