Effects of Light Quality and Norflurazon on the Formation of Plastid Pigments in Cotyledons of Pinus sylvestris

The effects of different light qualities and a special inhibitor of carotenoid biosynthesis on formation of plastid pigments of cotyledons of Pinus sylvestris were studied. The experimental results indicate: 1. The rate of synthesis of carotenoids in far-red light is relatively higher than that of chlorophylls, on the contrary in red light the rate of chlorophyll synthesis is higher. 2. When biosynthesis of carotenoids is inhibited, in white light the rate of total chlorophyll synthesis reduced with similar proportion. Accumulation of chlorophyll, however, is relatively much more than that of carotenoids. The highest molar ratio of chlorophyll/carotenoids is approximately 10.0. This implicates that chlorophyll and carotenoid synthesis proceed with certain independence. 3. After 4h exposure of strong white light of 9 day-old pine seedlings grown with 10-5 mol 1-1 norflurazon in farred light, contents of carotenoids and total, chlorophyll of cotyledons increase. Chlorophyll a biosynthesis promoted by light is higher than photooxidation of the pigment.     

光质和除草剂norflurazon对欧洲赤松子叶质体色素形成的影响

本文研究了不同光质和类胡萝卜素专一抑制剂 norflurazon 对欧洲赤松(Pinussylvestris)子叶叶绿体色素形成的影响,所得结果如下:1.在远红光下,类胡萝卜素相对合成速率大于叶绿素的合成速率,而在红光下恰恰相反。2.在白光下,当类胡萝卜素合成受抑制时,叶绿素的合成速率也有所降低。但是叶绿素相对积累量比类胡萝卜素大得多,叶绿素与类胡萝卜素的分子比增大到10:1,说明这两种色素的合成与积累有相当大的独立性。3.把连续在远红光下类胡萝卜素合成受抑制(含量为正常幼苗的30%)的松苗,移入强白光下4小时后,其总叶绿素和类胡萝卜素都有增加,表明只要有少量类胡萝卜素存在,光对色素合成的促进仍大于光氧化破坏。     

Effect of Purine and Pyrimidine Analogues on Growth and RNA Metabolism in the Soybean Hypocotyl-the Selective Action of 5-Fluorouracil

The effects of several base analogues and cycloheximide on RNA synthesis, protein synthesis, and cell elongation were studied in excised soybean hypocotyl. None of the pyrimidine analogues tested affected growth or protein synthesis; only 5-fluorouracil appreciably inhibited RNA synthesis. 8-Azaguanine and 6-methylpurine markedly inhibited RNA and protein synthesis and cell elongation. Cycloheximide effectively inhibited both cell elongation and protein synthesis.The results show that 5-fluorouracil selectively inhibited ribosomal and soluble RNA synthesis without affecting the synthesis of D-RNA. These results indicate that the requirement for RNA synthesis to support continued protein synthesis and cell elongation is restricted to the synthesis of D-RNA.5-Fluorouracil was incorporated into all classes of RNA in a form believed to be 5-fluorouridylic acid.Cycloheximide markedly inhibited the accumulation of ribosomal RNA, but the results indicate that CH did not inhibit, per se, the synthesis of ribosomal RNA. The accumulation of newly synthesized D-RNA was only slightly affected by cycloheximide. These results show that the inhibition of cell elongation by cycloheximide correlates with the inhibition of protein synthesis, but not with the effect on RNA metabolism.     

Hormone-induced dispersion or aggregation of carotenoid-containing smooth endoplasmic reticulum in cultured xanthophores from the goldfish, Carrassius auratus L.

A novel organelle movement is described in goldfish xanthophores. Smooth endoplasmic reticulum, containing carotenoids pigments, undergo MSH or c-AMP-induced dispersion. This dispersion is independent of RNA and protein synthesis, not modulated by c-GMP and inhibited by cytochalasin B but only at the relatively high concentration of 10 mug/ml. Epinephrine induces aggregation, a process that is inhibited by colchicine. These results suggest, but do not prove, the involvement of microfilaments in dispersion and microtubules in the aggregation of carotenoid-containing endoplasmic reticulum.     

The Changes of Protein Content and Synthetic Activity in Squash Pollen During Germination

The total protein content of squash (Cucurbita moschata Duch.) pollen decreased gradually during in vitro germination. It was caused by the release of wall proteins and part of the cytoplasmic proteins. The release of the pollen wall proteins was not dependent on germination, it was a passive diffusion process. However, the cytoplasmic proteins did not release until the pollen germinated, a fraction of them was synthesized de novo during germination. The RNA and protein synthetic activities initiated soon after in vitro pollen germination. The RNA synthesis decreased during germination. As about half the activity was inhibited by α-amanitin, mRNA might be the major RNA synthesized de novo. The total protein synthesis increased during germination, almost all of this synthesis was inhibited by cycloheximide, and partially by α-amanitin, but it was not affected significantly by actinomycin D. These results indicated that both stored and de novo synthesized mRNA might play a role in the protein synthesis. The content of stored mRNA of squash pollen was about 11-3 pg/grain as measured by UV absorption after its purification from total RNA (2440 pg/grain) by oligo (dT)-cellulose affinity chromatagraphy. Both cycloheximide and α-amanitin inhibited pollen tube growth in vitro. Actinomycin D and tunicamycin inhibited pollen germination in the first hour, however, no reduction ,of the tube length was observed later. Cyclohex,nide inhibited the pollen germination and tube elongation in vivo, that fitted well with the in vitro results. According to these results, it was suggested that the de novo syntheses of mRNA and protein were neccessary for the maintenance of pollen tube growth.     

Separation and characterization of low-molecular-weight nuclear RNA species that inhibit cell-free protein synthesis

Various RNA fractions were isolated from nuclei of 12-day lactating rat mammary glands and examined for their ability to inhibit cell-free protein synthesis. Although total nuclear RNA was generally inactive, material contained in the poly(A)+ nuclear RNA fraction and the low-molecular-weight RNA derived from total nuclear RNA by sucrose gradient centrifugation, inhibited the translation of several mRNAs but not poly(U) or poly(A). Separation of the small nuclear RNAs by preparative polyacrylamide-urea gel electrophoresis allowed the identification of at least three active inhibitor RNA species. These differed both with respect to their ability to inhibit protein synthesis, and in their mechanism of action. While two of the RNA species inhibited elongation the other inhibited initiation of protein synthesis.     

The effect of antimycin a on carotenogenesis in Verticillium agaricinum

Summary Antimycin A did not induce carotenogenesis in dark grown cultures of V. agaricinum, but total protein was increased. In light, antimycin A did not affect total carotenoids, although protein was slightly increased. The results suggest that antimycin A could not have acted here as an inducer for the synthesis of specific carotenogenic enzymes or by inactivating a repressor as has been suggested for certain bacteria.     

Changes in Average Cell Concentrations of Various Constituents During Synchronous Division of Platymonas striata Butcher (Prasinophyceae)

The changes in the average cell composition of the green algaPlatymonas striata Butcher have been determined during a singlecell cycle in synchronous culture induced by an alternatinglight/dark regime. The cells divided into two at the onset ofdarkness, but remained attached until exposed to light 10 hlater. There appeared to be virtually no net synthesis of constituentsduring the dark period. On exposure to light most components(apart from DNA) showed some continuing net synthesis, but inthe majority of cases there was a short part of this light syntheticperiod in which there was very active net synthesis. The activesynthetic period was frequently immediately prior to the onsetof division. DNA synthesis occurred only in the 6 h precedingdivision. The major period of net protein synthesis occurredwhilst the divided cells were separating, at the commencementof the light period. The other factors studied were RNA, carbohydrate,chlorophyll a, chlorophyll b, carotenoids, phospholipids, acid-solublecompounds, and phosphorus uptake. The results are discussed.     

Separation and characterization of low-molecular-weight nuclear RNA species that inhibit cell-free protein synthesis

Various RNA fractions were isolated from nuclei of 12-day lactating rat mammary glands and examined for their ability to inhibit cell-free protein synthesis. Although total nuclear RNA was generally inactive, material contained in the poly(A)⁺ nuclear RNA fraction and the low-molecular-weight RNA derived from total nuclear RNA by sucrose gradient centrifugation, inhibited the translation of several mRNAs but not poly(U) or poly(A). Separation of the small nuclear RNAs by preparative polyacrylamide-urea gel electrophoresis allowed the identification of at least three active inhibitor RNA species. These differed both with respect to their ability to inhibit protein synthesis, and in their mechanism of action. While two of the RNA species inhibited elongation the other inhibited initiation of protein synthesis.     

Variation in the relative synthesis of immunoglobulin G and non-immunoglobulin G proteins in cultured MPC-11 cells with changes in the overall rate of polypeptide chain initiation and elongation

The synthesis of individual proteins in the mouse plasmacytoma cell MPC-11 is differentially inhibited when the rate of polypeptide chain initiation is reduced by exposure of cells to hypertonic medium. The synthesis of immunoglobulin G light and heavy chain polypeptides is 3.5 to 4-fold and 1.5 to 2-fold more resistant, respectively, than the synthesis of non-immunoglobulin G proteins when total protein synthesis is reduced by ~90%. In contrast, when polypeptide chain elongation is inhibited, the synthesis of the light and heavy chains is not more resistant than the synthesis of non-immunoglobulin G proteins.The results with MPC-11 cells suggests that: (1) under standard growth conditions the relative synthesis of individual proteins is determined mainly, but not exclusively, by the relative amounts of the individual messenger RNA species present in the cell; (2) under conditions where the overall rate of polypeptide chain initiation is reduced the relative synthesis of individual proteins becomes more dependent upon the intrinsic ability of their corresponding mRNAs to form functional mRNA-ribosome initiation complexes.     

The mode of inhibition of the biosynthesis of phenylalanine ammonia lyase by its product cinnamic acid in aging potato parenchyma tissue

Excised potato parenchyma tissue upon aging in air and light, showed synthesis of RNA, as assessed by the incorporation of [₃H]-uridine, reaching a maximum in 18 h. The increase in RNA synthesis was in parallel with the increase in phenylalanine ammonia lyase synthesis. The treatment of the tissue, initially with actinomycin D at 15 μg/g tissue, or with trans-cinnamate at 3·5 mM, caused 65% and 50% inhibition of RNA synthesis, respectively. The inhibition was reduced to 20% by delaying the treatment of trans-cinnamate to the ninth hour. A comparative study on the nuclear fractions, isolated from trans-cinnamate treated and untreated aged parenchyma tissues showed that trans-cinnamate treatment inhibited thein vitro RNA synthesis by 38%. Studies on thein vivo synthesis of PAL and other proteins showed that trans-cinnamate treatment mainly impaired thede novo synthesis of PAL. The total RNA, isolated from trans-cinnamate treated parenchyma, was 66% less efficient in the translation of PAL, in cell free wheat germ protein synthesizing system. The translation product, purified by affinity chroma tography on phenylalanine conjugated sepharose-4B was found to be homogeneous and showed a single radioactive peak corresponding to protein band on polyacrylamide gel electrophoresis.     

A RING-finger photocarotenogenic repressor involved in asexual sporulation in Mucor circinelloides.

Mucor circinelloides responds to blue light by activating the biosynthesis of carotenoids and bending its sporangiophores towards the light source. The CrgA protein product acts as a repressor of carotene biosynthesis, as its inactivation leads to the overaccumulation of carotenoids in both the dark and the light. We show here that asexual sporulation in Mucor is also stimulated by light and that the crgA gene is involved in sporulation, given that lack of crgA function affects both carotenogenesis and the normal production of spores. A small interference RNA (siRNA) gene silencing approach was used to block the biosynthesis of carotenoids and to demonstrate that abnormal sporulation in crgA mutants is not a consequence of a defective production of carotenes. These results reveal an active role for the predicted CrgA product, a RING-finger protein, in the control of cellular light-regulated processes in Mucor.     

Hormonal control of hyaluronic acid production in fibroblasts and its relation to nucleic acid and protein synthesis.

Whole serum and elevated pH previously had been found to stimulate both cell multiplication and hyaluronic acid production by chick embryo fibroblasts in culture. In a study to determine whether cell multiplication and hyaluronic acid production both respond to a single well-defined substance, insulin was found to stimulate, and cortisol to inhibit both processes coordinately. It appears, therefore, that multiplication and differentiated function in fibroblasts respond to a common underlying regulatory signal. Inhibition of ribosomal RNA synthesis by actinomycin D does not prevent serum stimulation of hyaluronic acid production, but inhibition of total RNA synthesis does. If total RNA synthesis is inhibited only after the hyaluronic acid production has reached a new high level, it continues at that level for the next five hours. The stimulatory treatment causes an increase in the activity of the enzyme hyaluronate synthetase. Inhibition of protein synthesis prevents any increase in hyaluronic acid production, and reduces the basal level of production. Reduction of the availability of Mg2+ in the medium coordinately inhibits DNA synthesis and hyaluronic acid production. The results are discussed in the light of a model for coordinate control growth and metabolism based on the availability of Mg2+.     

Einfluss verschiedener Lichtwellenlängen auf die Zusammensetzung von Chlorella in Glucosekultur bei gehemmter Photosynthese

Summary Increasing blue light intensity inhibits the growth of Chlorella pyrenoidosa in glucose culture in which photosynthesis is blocked by DCMU, whereas red light supports growth which is the same as or better than that in dark controls.The action spectrum of light induced protein synthesis from exogenous glucose (photosynthesis inhibited, blue light addition resulting in growth >90% of the dark control) shows only one broad maximum at 450–490 nm which resembles the absorption spectrum of carotenoids.     

Action of phyenethyl alcohol on the synthesis of macromolecules in Escherichia coli

Prevost, C. (University of California, Berkeley), and V. Moses. Action of phenethyl alcohol on the synthesis of macromolecules in Escherichia coli. J. Bacteriol. 91:1446-1452. 1966.-A kinetic study of the effects of various concentrations of phenethyl alcohol on the synthesis of ribonucleic acid (RNA), deoxyribonucleic acid (DNA), protein, and beta-galactosidase in Escherichia coli has confirmed that RNA synthesis, rather than DNA synthesis, is first and most affected by phenethyl alcohol. The presence of inducer did not protect beta-galactosidase synthesis from inhibition by phenethyl alcohol. Little preferential inhibition of beta-galactosidase synthesis was observed; this is in contrast to the severe catabolite repression which results from partial inhibition of total protein synthesis caused by chloramphenicol or starvation for a required amino acid. We found no evidence that messenger RNA synthesis was inhibited to a greater extent than total RNA synthesis.     

The effect of proflavine on HeLa cells

1. The effect of proflavine on the metabolism of RNA, DNA and protein of HeLa cells was studied. 2. The synthesis of RNA, DNA and protein was progressively inhibited by concentrations of proflavine up to 43mum. 3. There was no simple relationship between the degrees of inhibition of synthesis of RNA, DNA and protein by increasing concentrations of proflavine: the synthesis of RNA was most readily inhibited, and the synthesis of protein was relatively insensitive. 4. A concentration of 22mum-proflavine inhibited synthesis of RNA and DNA and caused a progressive loss of RNA from both nucleus and cytoplasm without any accompanying loss of DNA or dry weight from the cells. 5. The rapidly labelled RNA in the nucleus was preferentially degraded and was not transferred in a stable form to the cytoplasm.     

Consequences of chlorophyll deficiency for leaf carotenoid composition in tobacco synthesizing glutamate 1-semialdehyde aminotransferase antisense RNA: dependency on developmental age and growth light

Transgenic tobacco (Nicotiana tabacum), with a reduced chlorophyll content of up to less than 10% of the wild-type level due to a different expression of antisense RNA coding for glutamate 1-semialdehyde aminotransferase, were used to study the relationship between chlorophyll accumulation and changes in carotenoid composition in developing and mature leaves grown either under low (30 mol photons m^-2 s^-1) or high light (300 mol photons m^-2 s^-1). Regardless of the extent to which chlorophyll synthesis was reduced, under low light the ratios of total chlorophyll to carotenoids remained constant. In contrast, under high light the content of carotenoids was elevated relative to chlorophyll and increased further with progressive inhibition in chlorophyll synthesis. The xanthophyll-cycle pigment pool was most strongly increased (up to 18-fold) upon suppression of chlorophyll synthesis. Concurrently to the higher pool sizes a higher extent of violaxanthin was converted into antheraxanthin and zeaxanthin and this was found to be correlated with a decrease in the quantum yield of photosystem II photochemistry. While lutein increased (up to 3-fold) with decreasing chlorophyll contents in high light transformants, neoxanthin remained rather constant in all plants analysed. Based on the present results, two different levels for the regulation of carotenoid synthesis are proposed depending on (I) the chlorophyll synthesizing capacity, and (ii) the photosynthetic light utilization efficiency. The first point suggests a co-regulation between carotenoid and chlorophyll synthesis; the second emphasizes the special role of carotenoids for protection against light stress.     

Retarding effect of inhibitors of protein and RNA synthesis on chlorophyll and protein breakdown

Cycloheximide, ethionine,p-fluorophenylalanine, 6-azauracil, 5-diazouracil and vanillin, applied at relatively high concentrations, retarded the yellowing of kale (Brassica oleracea L. var.acephala) leaf discs in darkness, and stimulated it in light. All the compounds inhibited protein synthesis and retarded protein breakdown. Cycloheximide,p-fluorophenylalanine, diazouracil and vanillin also inhibited the incorporation of uracil-¹⁴C into RNA of senescing discs. Abscisic acid and 2-chloroethylphosphonic acid accelerated yellowing both in darkness and in light and stimulated the protein breakdown in senescing discs. Abscisic acid inhibited the chlorophyll, protein and RNA synthesis in detached, greening cucumber cotyledons. There was no direct correlation between the activity of a given compound as an inhibitor of yellowing in darkness, and the degree of inhibition of RNA synthesis. The arrest of yellowing in darkness is possibly a consequence of the retarded rate of protein breakdown. Yellowing in light, on the contrary, is dependent on the actual rate of protein synthesis.     

Effects of alpha-amanitin, cycloheximide, and thioacetamide on low molecular weight nuclear RNA.

Studies were made on the effects of alpha-amanitin, cycloheximide, and thioacetamide on synthesis and content of low molecular weight nuclear RNA. Cycloheximide, an inhibitor of protein synthesis and the synthesis of 45S pre-rRNA and 5S RNA, also inhibited synthesis of nuclear U1 and U3 RNAs. alpha-Amanitin, an inhibited the synthesis of U1 and U2 low molecular weight nuclear RNA. Thioacetamide, which induces nucleolar hypertrophy and increased nucleolar RNA polymerase activity, markedly increased synthesis of 5.8S RNA and U3 RNA. These results show that syntheses of individual low molecular weight nuclear (LMWN) RNAs are controlled by different regulatory mechanisms. In particular, there appears to be a specific relationship between U3 RNA and functional states of the nucleolus.