IAA oxidase activity in relation to adventitious root formation on stem cuttings of some forest tree species

Summary IAA oxixase activity was very high in stem cuttings ofSalix tetrasperma andPopulus robusta, which rooted profusely, less in stem cuttings ofHibiscus rosa sinensis which rooted less, and insignificant in those ofEucalyptus citriodora which did not root at all. Protein(s) extracted from the stem cuttings ofE. citriodora inhibited the activity of IAA oxidase as well as root formation on hypocotyl cuttings ofPhaseolus mungo. The possibility of involvement of IAA oxidase activity in the process of adventitious root formation is discussed.The research has been financed by a grant from U.S. Department of Agriculture.     

Effect of exogenous application of nucleic acids and auxin on the rooting of hypocotyl cuttings ofImpatiens balsamina. Evidence for the uptake of information molecules

Summary Exogenously supplied DNA and RNA hastened root initiation and also increased the formation of roots on hypocotyl cuttings ofImpatients balsamina with intact apex and cotyledons. IAA appreciably increased the nucleic acid-caused enhancement in root formation. In combination with lowe concentrations of nucleic acids, it event stimulated the growth of roots as well as of hypocotyls. Higher concentrations of nucleic acids were, however, toxic.The research has been partly financed by a grant from the United States Department of Agriculture. One of us (SB) is thankful to the Deparmtent of Atomic Engery of the Government of India for financial assistance.     

Presence of auxin protectors inEriophyes inducedZizyphus stem galls

Summary 3 auxin protectors, which were o-dihydroxyphenols of high molecular weight, were isolated fromZizyphus gall tissues. An increase in polyphenol oxidase activity in the gall tissue was observed which probably led to the production of high levels of auxin protectors. This prevented IAA oxidation, resulting in hyperauxinity and auxin-autotrophy.     

Some cellular and molecular properties of abscisic acid: its particular involvement in growing plant roots

Several characteristics of the plant hormone abscisic acid (ABA) are critically discussed, more or less directly, in relation to the extension of root cells. A few topics have been selected some biochemical characteristics of ABA (chemical structure, metabolism), inhibiting-β complex, inhibiting regulators from root caps, endogenous ABA in growing roots (ABA gradients, microsurgical experiments, light effects), applied ABA on elongating roots, ABA and indol-3yl acetic acid (IAA) interactions (root growth, proton extrusion, hormone transport, auxin herbicides), ABA effect on the root cell cycle, ABA and drought cells of elongating roots [water deficit conditions, IAA and jasmonic acid (JA) as ‘stress hormones’ other than ABA, gene expression]. Received 28 January 1998; received after revision 20 April 1998; accepted 21 April 1998     

Isolation of indole-3-acetic acid methyl ester,a metabolite of indole-3-acetic acid fromPseudomonas amygdali

From the culture filtrates ofPseudomonas amygdali the methyl ester of indole-3-acetic acid (IAA), a product of indole-3-acetic acid metabolism which has the same auxin activity as the free acid, has been isolated. This is the first report of its occurrence as a microbial metabolite.     

Isolierung anthocyanhaltiger und anthocyanfreier Gewebestämme vonDaucus carota: Einfluss von Auxinen auf die Anthocyanbildung

Summary The isolation of anthocyanin-producing and non-producing cell lines of tissue cultures ofDaucus carota is described. Those clones which are able to synthesize anthocyanins do this in dark only if there is an auxin like 2,4-D, IAA or NAA present. In light no supplementary auxin is necessary for anthocyanin production. It is assumed that there might be relations between auxin and light-induced anthocyanin biosynthesis.     

Significance of nitrate reductase in nitrate assimilation in free-livingRhizobium cultures

Summary An in situ method for measuring nitrate reductase (NR) in free-livingRhizobium cultures has been developed. Arginine, threonine, valine, glutamic acid, tyrosine and tryptophan were found to promote NR synthesis. In root nodules rhizobial nitrate reductase also converts nitrate into NH₄ ⁺, thus it provides an alternative to the nitrogenase route for the formation of NH₄ ⁺.Acknowledgments: M.H.S. is grateful to the authorities of CSIR, New Delhi and Miss Anjali Mathur to the authorities of SCST, Lucknow (U.P.) for financial assistance.     

Preservation ofBordetella pertussis

Summary Bordetella pertussis has been shown to remain viable for a period of 13 years on freeze-drying. The revived cultures had unaltered antigenic composition and biological activity.Thanks are due to Dr M. Balasubrahmanyan for his guidance and Dr M.S. Zakharova, Gamaleya Institute of Microbiology and Epidemiology, Moscow, USSR for supplyingB. pertussis factor sera. We thank Mr Ram Jas for his technical assistance.     

Effect ofLantana camara L. extract on fern spore germination

Summary Extracts of root, stem, leaf and inflorescence ofLantana camara Linn., (Verbenaceae) inhibited exine bursting, rhizoid initiation and protonemal initiation of spores of the fernCyclosorus dentatus (Forsk.) Ching. The leaf extract was found to be qualitatively and quantitatively most potent in its inhibitory effect. Attention is drawn to the fact that further spread ofLantana camara at Mt. Abu, Rajasthan, India may lead to the complete destruction, of the sizeable pteridophytic component in this locality, the richest vegetationally in Rajasthan.     

Interaction du 2,4-dichlorophénol et de l'eau oxygénée dans la destruction enzymatique de l'acideβ-indolylacétique

Summary DCP increases IAA destruction by bothLens andPhaseolus root breis. H₂O₂ inhibits catabolism byLens extracts but activates it whenPhaseolus is used, mainly when roots are cultivated in the dark and contain inhibitors of IAA destruction. DCP 1·10^–3 M and H₂O₂ 1·10^–4 or 1·10^–3 volume forLens and DCP 1·10^–4 M and H₂O₂ 1·10^–3 volume forPhaseolus nullify auxin catabolism.     

Identification ofTrypanosoma theileri as a contaminant in primary cultures of bovine retina

Summary T. theileri has been isolated from primary cultures of bovine retina and subcultered successfully for 2 passages in sub-confluent cultures. When cultures reached confluency no trypomastigotes or epimastigotes could be detected and attempts to recover trypanosomes from these cultures were unsuccessful. The presence of intracellular forms could not formally be excluded.We wish to thank Dr S. Dershko, Division of Meat Inspection, Health of Animals Branch, Department of Agriculture (Canada) and Intercontinental Packers, Ltd. for their assistance in obtaining the freshest possible specimens. The skillful technical assistance of Mrs J. Graham is also gratefully acknowledged. This investigation was supported by the M. R. C. of Canada.     

Translation initiation: variations in the mechanism can be anticipated

Translation initiation is a critical step in protein synthesis. Previously, two major mechanisms of initiation were considered as essential: prokaryotic, based on SD interaction; and eukaryotic, requiring cap structure and ribosomal scanning. Although discovered decades ago, cap-independent translation has recently been acknowledged as a widely spread mechanism in viruses, which may take place in some cellular mRNA translations. Moreover, it has become evident that translation can be initiated on the leaderless mRNA in all three domains of life. New findings demonstrate that other distinguishable types of initiation exist, including SD-independent in Bacteria and Archaea, and various modifications of 5′ end-dependent and internal initiation mechanisms in Eukarya. Since translation initiation has developed through the loss, acquisition, and modification of functional elements, all of which have been elevated by competition with viral translation in a large number of organisms of different complexity, more variation in initiation mechanisms can be anticipated.     

Functions and transport of silicon in plants

Silicon exerts beneficial effects on plant growth and production by alleviating both biotic and abiotic stresses including diseases, pests, lodging, drought, and nutrient imbalance. Recently, two genes (Lsi1 and Lsi2) encoding Si transporters have been identified from rice. Lsi1 (low silicon 1) belongs to a Nod26-like major intrinsic protein subfamily in aquaporin, while Lsi2 encodes a putative anion transporter. Lsi1 is localized on the distal side of both exodermis and endodermis in rice roots, while Lsi2 is localized on the proximal side of the same cells. Lsi1 shows influx transport activity for Si, while Lsi2 shows efflux transport activity. Therefore, Lsi1 is responsible for transport of Si from the external solution to the root cells, whereas Lsi2 is an efflux transporter responsible for the transport of Si from the root cells to the apoplast. Coupling of Lsi1 with Lsi2 is required for efficient uptake of Si in rice. Received 21 December 2007; received after revision 29 April 2008; accepted 15 May 2008     

Variations de l'activité des auxines-oxydases dans les racines duLens

Summary 2, 4-dichlorophenol (DCP), 2, 4-dinitrophenol (DNP) and 2, 4-dinitro-o-cresol (DNC) applied at a concentration of 1.10^–7 to 1.10^–3 M, produce a dramatic increase in IAA-oxidase activity in young cells ofLens root. IAA destruction by breis from root tissues was inhibited by Mn⁺⁺ ion at low concentrations of DCP (1·10^– to 1.10^–7 M), but was enhanced by Mn⁺⁺ ion at higher (1.10^–5 to 1.10^–3 M) DCP levels.

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Ce travail a pu être entreprise grâce à l'appui duFonds national suisse pour la Recherche scientifique.     

Comparative study of oxalate oxidase in three genotypes ofSorghum vulgare

Summary The presence of an oxalate oxidase (EC 1.2.3.4) has been demonstrated in 15,000×g supernatants prepared from 10-day-old seedlings of three genotypes ofSorghum vulgare: grain sorghum hybrid (CSH-5), grain-cum-forage sorghum (PC-6) and forage sorghum (PC-1). The specific activity of the enzyme in the different tissues of seedlings was found to be present in the order leaves > stems > roots in PC-6 and PC-1, but this order was reversed in CSH-5. A comparison of the different properties of the leaf enzyme of these three genotypes of sorghum revealed that the enzyme has maximum activity in the acidic pH range from 4.0 to 5.0 and in the temperature range from 37°C to 40°C. The enzyme was stimulated by Cu²⁺ and Fe²⁺. The rate of H₂O₂ formation in the enzyme reaction was linear up to 5 min and was stoichiometrically related to oxalate consumption. The enzyme is unaffected by Na⁺ at physiological concentration (0.15 M). The superiority of this enzyme over moss and other plant enzymes for enzymic determination of urinary oxalate is discussed.     

Ethanol metabolizing system inDrosophila melanogaster: subcellular distribution of some main enzymes

Summary The subcellular distribution of some enzymes which play a part in ethanol metabolism have been determined by differential centrifugation of homogenates of adultD. melanogaster flies of various genotypes. Aldehyde dehydrogenase, recently discovered inD. melanogaster, is present in the five genotypes studied. It has been found however to be, in vitro at least, most active in a strain lacking both alcohol dehydrogenase and aldehyde oxidase.     

Regulation and termination of NADPH oxidase activity

NADPH oxidase of phagocytes plays a crucial role in host defense by producing reactive oxygen species (ROS) that are intended to kill invading microbes. Many other cells produce ROS for signaling purposes. The respiratory burst oxidase in human neutrophils is the main but not exclusive subject of this review, because it is archetypical and has been studied most extensively. The activity of this enzyme must be controlled in phagocytes to prevent collateral damage, and in non-phagocytic cells to perform its signaling role. With many stimuli, NADPH oxidase activity is transient. Various forms of evidence indicate that sustained NADPH oxidase activity requires continuous renewal of the enzyme complex, without which rapid deactivation occurs. This review considers mechanisms that have been proposed to terminate the phagocyte respiratory burst. Changes in the phosphorylation state of p47(phox) and in the species of nucleotide bound to Rac seem to be the dominant factors in deactivation.     

Identification of rooting depth and measurements of plant root activity in situ and in toto under field conditions using a gamma probe technique

Summary A technique for measuring root activity of agricultural crops in totality in situ under field conditions has been developed for the first time. The method essentially consists of measuring the activity emanating from roots after plant injection of a gamma radiating isotope using a probe. This also helps continuous monitoring of root growth changes over time.     

Cytokinesis in onion roots: Inhibition by vanadate and caffeine

Summary The effect of vanadate ions on plant cytokinesis has been studied inAllium cepa root meristematic cells. Vanadate induces binucleate cells by inhibiting cell plate formation. Moreover, vanadate and caffeine have additive effects in the induction of binucleate cells.