Biological Properties of d-Amino Acid Conjugates of 2,4-D

Some d-amino acid (glutamic acid, valine, or leucine) conjugates of 2,4-dichlorophenoxyacetic acid (2,4-D) at 10⁻⁵ molar, stimulated elongation of Avena sativa L. var Mariner coleoptile sections and growth of soybean (Glycine max. L. var Amsoy) tissue as much as did the l-amino acid conjugates at 10⁻⁶ molar. The d-methionine conjugate did not stimulate growth of soybean root callus tissue but did stimulate Avena elongation. The d-aspartic acid conjugate did not stimulate elongation of Avena coleoptiles but did stimulate growth of root callus tissue.     

Chemotaxis toward amino acids in Escherichia coli

Escherichia coli cells are shown to be attracted to the l-amino acids alanine, asparagine, aspartate, cysteine, glutamate, glycine, methionine, serine, and threonine, but not to arginine, cystine, glutamine, histidine, isoleucine, leucine, lysine, phenylalanine, tryptophan, tyrosine, or valine. Bacteria grown in a proline-containing medium were, in addition, attracted to proline. Chemotaxis toward amino acids is shown to be mediated by at least two detection systems, the aspartate and serine chemoreceptors. The aspartate chemoreceptor was nonfunctional in the aspartate taxis mutant, which showed virtually no chemotaxis toward aspartate, glutamate, or methionine, and reduced taxis toward alanine, asparagine, cysteine, glycine, and serine. The serine chemoreceptor was nonfunctional in the serine taxis mutant, which was defective in taxis toward alanine, asparagine, cysteine, glycine, and serine, and which showed no chemotaxis toward threonine. Additional data concerning the specificities of the amino acid chemoreceptors with regard to amino acid analogues are also presented. Finally, two essentially nonoxidizable amino acid analogues, alpha-aminoisobutyrate and alpha-methylaspartate, are shown to be attractants for E. coli, demonstrating that extensive metabolism of attractants is not required for amino acid taxis.     

Evidence for Two Indoleacetic Acid-Induced Growth Responses in the Avena Straight-Growth Indoleacetic Acid Assay

Floating Avena sativa L. cv Victory coleoptile segments were used to determine whether the straight-growth indoleacetic acid (IAA) assay can be reconciled with the Avena curvature assay and the Cholodny-Went theory of photo- and gravitropism. Measurements of segment length after 5 h yield sigmoid-shaped IAA dose-response curves with the growth rate leveling off at 1 [mu]M. However, measurements made at 24 h generate bell-shaped curves with maximal growth being induced by 10 [mu]M IAA. The difference between short- and long-term IAA dose-response curves is not due to IAA degradation; instead, it is the result of two growth responses to IAA. The initial one is rapid, responds to low concentrations of IAA, and lasts for 12 h. The second response is less sensitive to IAA than the first one. It appears after 6 h but is not obvious until the last 12 h of a 24-h incubation. The profile of short-term IAA dose-response curves reflects the initial growth response, whereas that of the 24-h curve is the sum of both growth responses. Linear-linear plots of 5- and 24-h dose-response curves show that coleoptile segment growth rate is proportional to IAA concentration up to 0.3 [mu]M. When the efficiency of IAA action is taken into account, it is found that the most effective IAA concentration for short and long incubations is 0.4 [mu]M. It is concluded that the Avena straight-growth IAA assay is as sensitive as the Avena coleoptile curvature assay, and that it is consistent with the Cholodny-Went theory.     

不同晶型、旋光型氨基酸原料药的红外图谱分析

分析比较了 33种不同来源的氨基酸产品红外图谱的差异 ,其中丝氨酸、门冬氨酸、醋酸赖氨酸、谷氨酸 (白色结晶性粉末 )、苏氨酸、缬氨酸、丙氨酸、亮氨酸、脯氨酸、盐酸组氨酸、盐酸精氨酸、酪氨酸、胱氨酸等 13种与标准图谱完全一致 ;甲硫氨酸、盐酸赖氨酸、甘氨酸、谷氨酸 (白色结晶 )等 4种与标准图谱不一致 ,其原因是 :甘氨酸和谷氨酸由晶型不同造成 ,甲硫氨酸因旋光性不同而造成 ,盐酸赖氨酸与相应的生化试剂图谱一致。     

烧伤狗浆血游离氨基酸的动态变化

烧伤狗浆血游离氨基酸的动态变化黎君友,周幼勤,赖业馥,赵有,伊少杰ＳｅｑｕｅｎｔｉａｌＣｈａｎｇｅｓｉｎＰｌａｓｍａＦｒｅｅＡｍｉｎｏＡｃｉｄＣｏｎｃｅｎｔｒａｔｉｏｎｉｎＢｕｒｎｅｄＤｏｇｓ￥Ｌｉｊｕｎｙｏｎ;Ｚｈｏｕｙｏｕｑｉｎ;Ｌａｉｙｅｆｕ;...     

Variation in the free amino acid content of skeletal muscle of Ophicephalus punctatus (Bloch)

The skeletal muscle of Ophicephalus punctatus contains nine essential free amino acids, arginine, histidine, isoleucine, leucine, methionine, phenylalanine, threonine, valine and lysine, and eight non-essential amino acids, alanine, aspartic acid, cystine, glutamic acid, glycine, tyrosine, proline and serine. Histidine and lysine dominated the free amino acids pool. Seasonal variation was detected in the levels of histidine, arginine, leucine, phenylalanine, glycine, cystine and serine with highest values occurring in April and again in November. Changes were also detected in the concentrations of certain amino acids as the fish grew in size. Levels of free amino acids did not significantly differ between sexes. Factors effecting variation are discussed.     

Amino Acids as Nitrogen Sources for the Growth of Euglena gracilis and Astasia longa

SYNOPSIS. Euglena gracilis (bacillaris variety, strain SM-L1, streptomycin-bleached) used the following amino adds (10⁻³ M) as sole nitrogen source for growth on a defined medium: glycine, alanine, valine, leucine, isoleucine, serine, threonine, and glutamic acid. Aspartic acid was used at 10⁻² M. Glutamine and asparagine were used at 10⁻³ M and were better N sources than their parent dicarboxylic amino acids. Not used as sole N source for growth were phenylalanine, tyrosine, tryptophan, cysteine, cystine, methionine, proline, hydroxyproline, histidine, arginine, lysine, and taurine. Astasia longa (Jahn strain) was more restricted than Euglena and used only asparagine and glutamine as N sources for growth.     

Effect of cycloheximide on IAA-induced proton excretion and IAA-induced growth in abraded Avena coleoptiles

IAA-induced proton excretion in peeled or abraded oat ( Avena saliva L. cv. Victory) coleoptiles is closely associated with IAA-induced growth. It was attempted to separate these two processes by using cycloheximide to inhibit them differentially. Growth of abraded coleoptile segments was measured by a shadow graphic method, and their IAA-induced acidification of the external solution was monitored with a pH meter. IAA stimulated proton excretion in abraded Avena coleoptile segments after a 13 min lag. IAA-induced proton excretion was inhibited within 5 min by cycloheximide at concentrations of 1.8 × 10⁻⁶, 3.6 × 10 or 3.6 × 10⁻⁵ M. Cycloheximide at these concentrations, added within 4 min of IAA, prevented IAA-induced acidification of the medium for at least 60 min. However, it did not prevent IAA-induced growth during this time. It is concluded that some of the initial IAA-induced growth seen in Avena coleoptiles is independent of detectable IAA-induced proton excretion.     

Growth Regulator Interactions in the Growth of the Shoot System of Avena sativa Seedling: II. THE GROWTH OF THE FIRST LEAF AND THE COLEOPTILE1

1. Studies have been made of the growth in culture medium of thecomponent parts of compositesegments excised from 3 to 7-day-oldAvena sativa seedlings and comprising portions of coleoptileand first leaf bases and various lengths of first internodetissue.
2. The effects of various concentrations of gibberellicacid (GA)and indole-3- acetic acid (IAA) alone and in combinationhavebeen studied on the growth of these organs.
3. Both GA andIAA stimulate the growth of coleoptile base tissuebut in combinationtheir joint effects are less than additive.No synergism occurs.
4. The growth of the first-leaf base is greatly stimulated byGAbut is inhibited by IAA. In combination, the stimulatoryeffectof GA (up to 1 0 p.p.m.) may be virtually eliminatedby evenlow concentrations of IAA (0.01 p.p.m.).
5. The inclusionof first internode tissue in the segments considerablyincreasesthe growth of first leaf base tissue but has no consistenteffecton the growth of coleoptile base tissue. The presenceof firstinternode tissue also greatly increases the degreeof growthstimulation invoked by GA but does not influence thedegreeof IAA inhibition. It is postulated that the first internodetissue is the source of an unknown growth factor necessary forGA action in the first leaf and potentiating the action of endogenousgibberellin.
6. Kinetin, adenine sulphate, glutarnine, glutarnicacid, asparagine,glycine, arginine, histidine, lysine, aneurin,and pyridoxinewill not simulate the effects of this unknowngrowth factorin the growth of leaf tissue. Like IAA, kinetinvirtually eliminatesthe GA stimulation of leaf growth.
7. Astudy of extracts of internode tissue in various solvents,analysedby paper partition chromatography and assayed by thegrowthof the first leaf base, has indicated the presence ofgrowthinhibitors and gibberellin-like substances but has failedtoisolate the postulated endogenous GA-synergist.
8. The implicationsof these results for growth correlations andthe hormone controlof shoot growth in Avena sativa seedlingsis discussed.

     

Distribution of Endogenous Indole-3-acetic Acid and Growth Inhibitor(s) in Phototropically Responding Oat Coleoptiles

The relationship between the flank growth of oat (Avena sativaL. cv. Victory) coleoptiles and the distribution of endogenousindole-3-acetic acid (IAA) and growth inhibitor(s) in the coleoptileswas studied for the second positive phototropic curvature inducedby a continuous unilateral illumination with white light (0.1W.m^–2). The phototropic curvature was caused by growthinhibition at the lighted side and growth promotion at the shadedside. Using electron capture detection gas chromatography, weanalyzed the distribution of endogenous IAA in phototropicallyresponding oat coleoptiles and found that the IAA was evenlydistributed over the lighted and shaded sides during the phototropicresponse; there was also no detectable difference in the amountsof IAA between phototropically stimulated and non-irradiatedcoleoptiles. By contrast, oat coleoptile straight-growth testresults showed that the amount of unknown acidic growth inhibitor(s),different from abscisic acid, increased in the lighted halfof the coleoptiles and decreased in the shaded half, as comparedto the amount in the non-irradiated half. These data suggestthat the phototropic curvature of oat coleoptile is inducedby a difference in lateral flank growth through a lateral gradientof endogenous growth inhibitor(s) rather than of IAA. (Received February 10, 1988; Accepted July 29, 1988)     

Bound indoleacetic Acid in Avena coleoptiles

When C¹⁴ carboxyl indoleacetic acid (IAA) is transported through Avena coleoptile sections a fraction of the activity becomes bound. The nature of this bound IAA has been investigated. Upon extraction with solvents and chromatography a substance having the R_F of IAA in 4 solvents was detected. No evidence could be found for the formation of indoleacetyl conjugates. In pea stem sections subjected to a similar experimental regime good evidence was obtained for the occurrence of conjugates. When IAA was supplied exogenously to coleoptile sections floating in solutions the occurrence of conjugates was shown to be dependent on the presence of the primary leaf. In its absence no conjugates could be detected.

On grinding coleoptile sections and subsequent centrifugation at 240 × g the radioactivity was found to be in the tissue fraction as opposed to the supernatant. The radioactivity cannot be removed from the tissue by extraction with water, buffer solution or treatment with ribonuclease. It is readily removed by 10% urea, crystalline trypsin and chymotrypsin. It is therefore concluded that IAA becomes bound to a protein. Bound IAA does not appear to be able to cause growth in Avena coleoptile sections.

     

Hexacyanoferrate (III) stimulation of elongation in coleoptile segments fromZea mays L.

Summary The influence of exogenous potassium hexacyanoferrate (III) (HCF III) on elongation of maize (Zea mays L.) coleoptile segments was investigated. Addition of HCF III led to a strong stimulation of growth both in the presence and absence of indole-3-acetic acid (IAA). The magnitude of growth stimulation was dependent on the presence of IAA, HCF III concentration, incubation time, and phase growth. The reduced form, potassium hexacyanoferrate (II), was without effect on growth. In the presence of HCF III, elongation was suppressed when coleoptile segments were treated with N,N-dicyclohexylcarbodiimide, cycloheximide or atebrine (quinacrine). The addition of HCF III stimulated the IAA-induced proton extrusion, and the e^–/H⁺ ratio decreased with incubation time. HCF III also strongly stimulated elongation ofAvena saliva L. coleoptile segments andGlycine max L. hypocotyl segments. These results suggested that a plasma membrane redox system (NADH oxidase type I) may be involved in the regulation of growth through the activity of the plasma membrane-bound ATPase.Abbreviations CH cycloheximide - DCCD N,N-dicyclohexylcarbodiimide - HCF III potassium hexacyanoferrate (III) (potassium ferricyanide) - HCF II potassium hexacyanoferrate (II) (potassium ferrocyanide) - IAA indole-3-acetic acid     

Inhibition of IAA-Induced Growth of Wheat Coleoptile Fragments by Chitin-Chitosan Oligomers

We studied the comparative effects of the phytohormone indolylacetic acid (IAA) and chitooligosaccharides (5–10 kDa, degree of deacetylation 35%) on the growth of coleoptile fragments of 3-day wheat germlings. IAA (10mg/l) stimulated elongation of coleoptile fragments by 80%, as compared to the control (water). Chitooligosaccharides at 0.01–1500 mg/l or higher did not exert auxin-like effects, but at 100 mg/l or higher, suppressed elongation of the coleoptile fragments, as compared to the control (water). Incubation of coleoptile fragments in solutions containing both IAA and chitooligosaccharides (100 mg/l or higher) suppressed their IAA-induced elongation, which correlated with the inhibition of growth of 3-day wheat germlings after wetting seeds in solutions of chitooligosaccharides. It has been proposed that the phytohormone-like properties of chitooligosaccharides can be related to changes in the endogenous balance of phytohormones in plants.     

Cysteine and Cystine Transport at the Blood-Brain Barrier

Abstract: The nature of cysteine and cystine uptake from the cerebral capillary lumen was studied in the rat using the carotid injection technique. [³⁵S]-Cysteine uptake was readily inhibited by the synthetic amino acid 2-amino-bicyclo(2,2,1)heptane-2-carboxylic acid (BCH), the defining substrate for the leucine-preferring (L) system in the Ehrlich ascites cell. The addition of non-radioactive alanine or serine, representatives of the alanine, serine, and cysteine-preferring (ASC) system, produced no significant decrease in the uptake of cysteine after cysteine transport by the L system was blocked with BCH. This indicated that the major component of cysteine's transport from the brain capillary lumen was by the L system with no detectable uptake of cysteine by the ASC system. No carrier-mediated transport of cystine, the disulfide form of the amino acid, was detected, nor was there any inhibition by cystine of the transport of the neutral amino acid methionine or the basic amino acid arginine. These results suggest that the ASC system, if present, is not quantitatively important for the transport of neutral amino acids from the brain capillary lumen.     

Growth and Geotropic Responses of Avena Coleoptiles to 4-Amino-3,5,6-Trichloropicolinic Acid

The elongation and geotropic responses of coleoptile sections of Avena sativa L. to various concentrations of 4-amino-3,5,6-trichloropicolinic acid (Tordon) proved to be qualitatively similar to those previously reported for 2,3,6-trichlorobenzoic acid (TCBA). Tordon stimulated growth in a range of concentrations from 1 × 10^?6 to 1 × 10^?4M but higher concentrations were inhibitory. Geotropic curvature was extensively depressed by 1 × 10^?5 and 1 × 10^?4M Tordon, concentrations which accelerated elongation. A similar differential effect has been reported for TCBA and other auxins. Several other picolinic acids and related compounds were tested, but only very slight responses were noted.     

The amino acid requirements of rabbit fibroblasts,strain RM3-56

Strain RM3-56 of rabbit fibroblasts was found to require arginine, cystine, glutamine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, serine, threonine, tryptophan, tyrosine, and valine for growth in a medium containing 2 per cent dialyzed serum as the only undefined component. The requirement for serine is less specific than that of the other 13 amino acids and it is partially replaced by glycine, or alanine, or by several combinations of so called accessory amino acids. The concentrations of essential amino acids which permit maximal proliferation range from 0.005 to 0.3 mM. Cystine, glutamine, lysine, tryptophan, tyrosine, valine are toxic at concentrations of 5 mM. The rate of proliferation of RM3-56 in a medium containing all 14 essential amino acids is increased significantly by the addition of alanine and to a lesser extent by the addition of aspartic and glutamic acids and glycine. A deficiency of cystine or glutamine results in cellular degeneration within 3 to 5 days, whereas the cells remain in good condition for 2 to 3 weeks in the absence of each of the remaining 12 essential amino acids. The results obtained with RM3-56 are compared with strains HeLa, L, and U12, whose amino acid requirements have been investigated under similar conditions.     

Opposite effects of fusicoccin and IAA on putrescine synthesis of rice coleop tiles

Changes in polyamine biosynthesis and elongation of etiolated rice coleoptiles ( Oryza sativa L. cv. Taichung Native 1) in response to fusicoccin (FC) and indoleacetic acid (IAA) were investigated. FC stimulated coleoptile elongation at concentrations higher than 1 μ M but caused a decrease in the levels of free putrescine, spermidine and sper-mine, as well as in the activities of arginine decarboxylase (ADC, EC 4.1.1.19) and S -adenosylmethionine decarboxylase (SAMDC, EC 4.1.1.50). The extent to which FC caused these effects was dependent on its concentration. Treatment with 100 μ M IAA also induced coleoptile elongation and resulted in a decrease in free spermidine/sper-mine and SAMDC activity. However, treatment with IAA resulted in an increase in free putrescine levels and ADC activity. The extent of coleoptile elongation and putrescine accumulation also depended on IAA concentration. α-Difluoromethylarginine (DFMA), an irreversible inhibitor of ADC. but not α-difluoromethylornithine (DFMO). an irreversible inhibitor of ODC (EC 4.1.1.17), inhibited the LAA-stimulated coleoptile elongation and putrescine accumulation. Addition of putrescine could not reverse the effect of DFMA.     

Epidermal Growth Factor Interacts with Indole-3-Acetic Acid and Promotes Coleoptile Growth

We used coleoptile sections of Avena sativa, Sorghum bicolor,and Zea mays seedlings to examine interactions between epidermalgrowth factor (EGF) and indole-3-acetic acid (IAA) that mayaffect plant growth and development. Our 24-h bioassays employedthree controls ranging in dilution from 10^–4 to 10^–8g ml^–1: (1) 50 mM potassium-phosphate buffer solution(pH=6.0), (2) bovine serum albumin, a nonspecific protein; and(3) IAA; plus two treatments: (1) mouse epidermal growth factor(EGF) ranging from 10^–6 to 10^–10gml^–1, and(2) EGF + IAA. In all three species growth in IAA, EGF, andEGF + IAA treatments showed significant increases over controls;EGF+IAA showed significant increases in growth over IAA alone.As the concentrations of IAA decreased, the EGF and IAA interactionbecame more pronounced. At the highest IAA concentrations, EGF+ IAA increased growth rates ca. 2% to 39%, whereas at lowerIAA concentrations EGF + IAA promoted growth as much as 121%,thereby lowering the normal IAA physiological set point up tothree or four orders of magnitude. Our data suggest that aninteraction between EGF and IAA may allow plants to recognizeand respond to animal biochemical messengers, resulting in changesin plant cell elongation that ultimately may alter plant growthpatterns. (Received April 27, 1994; Accepted September 5, 1994)     

Jasmonic Acid Inhibits the IAA-Induced Elongation of Oat Coleoptile Segments: a Possible Mechanism Involving the Metabolism of Cell Wall Polysaccharides

The effects of jasmonic acid (JA) on the IAA-induced elongationof segments of etiolated oat (Avena sativa L. cv. Victory) coleoptileswere studied. Exogenously applied JA substantially inhibitedIAA-induced elongation of oat coleoptile segments. The inhibitionof the growth of oat coleoptile segments due to JA appeared2 h after the application of JA with IAA. JA did not affectthe consumption of oxygen by the segments, the osmolarity ofthe cell sap or the IAA-induced loosening of cell walls, whichwas recognized as a decrease in the minimum stress-relaxationtime (T₀). JA was extremely effective in preventing increasesin the amount of the cell wall polysaccharides in both the non-cellulosicfraction and the cellulosic fraction during coleoptile growthin the presence and in the absence of IAA. Inhibition of thegrowth of oat coleoptile segments induced by JA was partiallyreversed by the simultaneous addition of sucrose to the testsolution. From these results, it appears that JA inhibits IAA-inducedelongation of oat coleoptile segments by interfering with someaspects of sugar metabolism that are related to the degradationand/or the synthesis of cell wall polysaccharides. (Received March 15, 1994; Accepted August 2, 1994)     

Free Amino Acid and Storage Protein Composition of Soybean Fruit Explants and Isolated Cotyledons Cultured with and without Methionine

Thein vitroculture of immature soybean cotyledons (in direct contact with the medium) and immature fruit explants (stem dipping into the medium) on a defined medium containing glutamine and sulphate as sole sources of N and S for 7 d led to rates of growth and reserve protein accumulation close to, or greater than, those occurringin situ. Supplementation of the medium with 8.4 mMmethionine had little effect on growth and protein accumulation of the cotyledons in the explant system, but did result in significant increases in the isolated cotyledon system. Methionine suppressed the synthesis of the 7S β-subunit in both systems. The free amino pool of the cotyledons increased more than three-fold when methionine was present in the explant medium. In the isolated cotyledon system, the basal medium alone caused a large increase (over 30-fold) in the free amino acid fraction, but methionine resulted in an even greater increase (over 50-fold). In both systems the expansion involved a very large increase in the methionine pool, but many other amino acids also showed large increases. Specific effects of methionine on individual amino acids were more clear in the explant system, where its presence resulted in marked increases in serine, alanine and asparagine. The data show that an abnormal situation arises on feeding with methionine, a fact to be considered before attributing effects on growth and protein synthesis directly to methionine.