Comparison of chromosome damage induced by three zinc compounds using human leukocyte culture

The degree of chromosome damage induced by three compounds of zinc (zinc chloride, zinc sulfate, zinc acetate) was compared in human leucocytes in vitro. Three concentrations of each salt, 3.0×10⁻⁵ M, 3.0×10⁻⁴ M, and 1.5×10⁻³ M, were added to leukocyte cultures. The cells were harvested after 48 and 72 h and chromosome spreads were prepared following a colchicine-hypotonic-fixation-air drying-Giemsa staining schedule. The end point screened was chromosome aberrations. All three salts were lethal at the highest concentration. The degree of chromosome damage was directly proportional to the concentrations used for zinc sulfate and zinc acetate but not for zinc chloride.     

Stimulation of Growth of Peppermint (Mentha piperita) by Phosfon, a Growth Retardant

The shoot growth and fresh weight of Mentha piperita grown in soil were stimulated at concentrations of 1.26 × 10^?5M to 7.77 × 10^?4M phosfon (2,4-dichlorobenzyl tributyl phosphonium chloride) while higher concentrations resulted in retardation of growth. Concentrations of 6.30 × 10^?7M to 3.78 × 10^?5M caused retardation of growth in mineral nutrient solution, and even death at the highest concentrations. However, when the M. piperita plants were grown in mineral nutrient solutions at concentrations of phosfon which had been sequentially lowered from 2.52 × 10^?8M to 2.52 × 10^?12M, the shoot growth and fresh weight were stimulated as in the case of plants grown in phosfon treated soil.     

Nutrition of eidamella deflexa V. effect of varying the concentrations of certain inorganic compounds on growth and pigment elaboration

Summary The effect of addition of varying concentrations of certain inorganic compounds in selected media upon growth and pigment elaboration ofEidamella deflexa (Berk.)Benjamin was studied in submerged culture. Preliminary experiments were performed to establish approximate optimum ranges of certain inorganic compounds. Further investigations in a glycine-sucrose basal medium indicated that the following range of concentrations stimulated growth to the greatest extent: 0.2% MgSO₄·7H₂O, 0.2% K₂HPO₄, 0.25 mg% CuSO₄·5H₂O, 0,0% ZnSO₄·7H₂O and 10.0 mg % FeSO₄·7H₂O. The degree of pigment production did not seem to be affected by different concentrations of these compounds.The effects of additional molybdenum and zinc upon growth and pigmentation were studied in the following media: lactose-peptone, lactose-glycine, maltose-peptone and maltose-glycine. Molybdenum increased pigmentation slightly in maltose-glycine and maltose-peptone media, but inhibited the amount of growth. Molybdenum decreased both growth and pigmentation in the two lactose media. Zinc had little affect on either growth or pigment elaboration in the two maltose media. However, in the lactose-glycine medium, zinc decreased both growth and pigmentation while in lactose-peptone media zinc slightly increased growth and pigmentation.     

The influence of zinc and light conditions on the cadmium-repressed growth of the green alga Coelastrum proboscideum

The growth response of Coelastrum proboscideum Bohlin to cadmiun (3 × 10^?9M to 2.4 × 10^?7M) was studied. The inorganic media used varied in zinc concentration (1.3 × 10^?7M to 3.6 × 10^?6M). The data were evaluated by factorial analyses. The influence of zine on the growth depression by cadmium depended on the light conditions (16:8 h light:dark cycles or 24 h continuous illumination periods). Intermittent illumination caused a negative interaction of zinc and cadmium in contrast to a positive interaction or additive effects of these elements during continuous illumination.     

Effects of H2O2 on the growth, secretion, and metabolism of hybridoma cells in culture

Summary The effect of low concentrations of hydrogen peroxide (H₂O₂) (5 × 10⁻⁷−9.5 × 10⁻⁷ M) on cell growth and antibody production was investigated with murine hybridoma cells (Mark 3 and anti-hPL) in culture. Cell growth, measured by flow cytometry with morphological parameters, was significantly stimulated by H₂O₂ (8 × 10⁻⁷ M) but H₂O₂ concentration of 7 × 10⁻⁶ M and above increased cell death. H₂O₂ stimulation of antibody production was nonsignificant. The metabolism of cells treated with 8 × 10⁻⁷ or 1 × 10⁻⁵ M H₂O₂ was similar to that of the control in terms of glucose and glutamine consumption, lactate and ammonia production, and amino acid concentrations in the medium. The concentrations of lactate dehydrogenase, a marker of cell death, in test and control cells were similar. However, concentrations of intracellular free radicals measured by flow cytometry with dihydrorhodamine 123 (DHR 123) and dichlorofluorescein diacetate (DCFH-DA) as fluorochromes were different. The reactive oxygen species content of cells in 8 × 10⁻⁷ M H₂O₂ was similar to that of the controls, but there was a sudden, marked production of superoxide anions (detected with DHR 123) and H₂O₂ or peroxides (detected with DCFH-DA) by cells incubated with 1 × 10⁻⁵ M H₂O₂ which increased with increasing H₂O₂ until cell death.     

Activity of Various Growth Substances in the Avena First Internode Test

The elongation growth of the Avena first internode segments was studied in the presence of one or several of the following growth substances: indoleacetic acid (IAA), 6-fur-furylamino purine (FAP, kinetin), 6-benzylamino purine (BAP), gibberellin A₃ (GA₃) and A₄₊₇ (GA₄₊₇), and abscisic acid (ABA). The cytokinins at concentrations of 10^?7 to 10^?6M stimulated growth with 4 to 6 per cent but this effect was not statistically significant. Concentrations higher than 5 × 10^?6M inhibited growth. FAP and BAP (from 10^?8M to 10^?6M) had no significant interaction with any other growth substance used. The two-factor interactions of IAA × ABA, IAA × GA₃, and GA₃× ABA, as well as the three-factor interaction IAA × ABA × GA₃ were significant. However, the IAA × ABA interaction was significant only when high concentration (10^?6M) of ABA was used. The growth inhibition produced by 10^?7 and 10^?6M ABA was overcome by about equimolar concentrations of IAA. The stimulation of growth by GA₃ and GA₄₊₇ (10^?9 to 10^?7M) was prevented by simultaneous application of ABA, and it was reduced significantly by application of IAA (10^?7 to 10^?8M). GA3 at 10^?8M combined with different concentrations of IAA gave slightly higher elongation than IAA alone but the observed values were significantly lower than expected assuming independent additive action.     

Effects of Organic Nutrients and Hormones on Growth and Development of Tissue Explants from Coconut (Cocos nucifera) and Date (Phoenix dactylifera) Palms Cultured in vitro

The growth response (increase in weight) of cultured explants from seedling date (Phoenix dactylifera L.) and mature coconut (Cocos nucifera L. cv. Malayan Dwarf) palms to source and concentration of organic nitrogen. carbohydrate, auxins, cytokinins and gibberellins was examined. Growth was strongly stimulated by the presence of auxins (10^?7 to 10^?6M), cytokinins (10^?6 to 10^?5M), high concentrations of sucrose (0.2 M), and in the absence of NH₄Cl, by organic sources of reduced nitrogen. Higher concentrations of auxin (2,4-D or NAA at 10^?6 to 10^?5M) which still stimulated growth of Phoenix tissue, proved inhibitory to growth of freshly excised Cocos tissues. Explants from both palms initiated roots when subcultured on a medium with increased levels of auxin (NAA, 2.5 × 10^?6 to 2.5 × 10^?5M) and reduced levels of cytokinin (6-BAP, 5 × 10^?8M). Isolated roots excised from these explants continued growth and produced new laterals when subcultured on media with GA₃ (5 × 10^?7M) and reduced levels of auxin, cytokinin, and either minerals or sucrose.     

Analysis of developmentally homogeneous neural crest cell populations in vitro: II. A tumor-promoter (TPA) delays differentiation and promotes cell proliferation

The tumor-promoting agent 12-O-tetradecanoylphorbol-13-acetate (TPA) delayed pigmentation in developmentally homogeneous quail neural crest cell populations in vitro. Doses below 5 × 10^?8M resulted only in a delay in pigmentation for up to 2 days without changing the rate of pigmentation, whereas intermediate doses (5 × 10^?8–10^?7M) delayed the initiation and decreased the rate of pigmentation but had no effect on the ultimate fate. Doses of TPA above 2 × 10^?7M irreversibly prevented pigmentation in some of the cells. TPA did not influence growth of the undifferentiated cell population. Since TPA delayed the decline in the cell proliferation rate that normally occurred with pigmentation, however, the final number of pigmented cells could be increased up to 10-fold in TPA-treated cultures without changing the homogeneity of the cultures. A part from the effects on cell differentiation, TPA caused an immediate change in cellular association within the clusters.     

Interaction of Kinetin and Indoleacetic Acid in the Avena Straight-Growth Test

Kinetin has a stimulating effect in the Avena straight-growth test. The action of different concentrations of kinetin, 2.5 × 10^?7, 2.5 × 10^?6 and 2.5 × 10^?5M, in combination with different concentrations of IAA was studied in this test. It was shown that the effect of low IAA concentrations, 0.25 × 10^?7 and 1 × 10^?7M, was strongly enhanced by the addition of all the kinetin concentrations investigated. The effect of the highest IAA concentrations, 25 × 10^?7 and 100 × 10^?7M, on the other hand, was inhibited relatively strongly by the highest employed concentration of kinetin. The results are explained as due to a kinetin-produced increase of auxin in the coleoptile segment, which in combination with low IAA concentrations can lead to a growth stimulation and with high IAA concentrations to a growth inhibition. Since kinetin in purification and chromatography of auxin can partly follow IAA, thereby affecting the quantitative yield, it is emphasized that, prior to the test, auxin extracts containing cytokinins should be freed from the latter by, for example, gel filtration or paper electrophoresis.     

The relationship between pathogenic fungal metabolities (fusaric and picolinic acid), endogenous ethylene evolution and the development of ethylene-like symptoms

Summary The effects of fusaric acid (5-n-butylpicolinic acid), picolinic acid (2-pyridine carboxylic acid), and picloram (4-amino-3, 5, 6-trichloropicolinic acid) on endogenous ethylene production by tomato cuttings and elongation growth of oat coleoptile sections were measured. Ethylene production by tomato cuttings was substantially stimulated by treatment with 1×10⁻³ and 1×10⁻⁵ M picoloram and to a lesser extent by 1×10⁻³ M fusaric acid; picolinic acid had little effect. The ethylene levels produced in response to fusaric acid are not high enough to account for the ethylene injury observed in Fusarium wilt. Fusaric acid inhibited oat coleoptile extension, picolinic acid had little effect, and picloram promoted growth.     

Tryptophansynthase in Phycomyces blakesleeanus Teil I: Eigenschaften des Enzyms

Tryptophan synthase in Phycomyces blakesleeanus. Part I: Characterization of the enzyme. Tryptophan synthase was tested in light grown 5 days old cultures of Phycomyces blakesleeanus. The test was carried out only by reaction 3 (indole + serine → tryptophan + water) of the tryptophan synthase. The K_m values for the substrates indole and serine were found to be 1.3 × 10^-4M and 1.0 × 10^-2M. Two K_m values (1.5 × 10^-8M and 1.0 × 10^-6M) for pyridoxal 5′-phosphate could be calculated from a Lineweaver-Burk plot. The transformation of the Lineweaver-Burk plot into the Hill plot resulted in a straight line with a rise of 0.35 for pyridoxal 5′-phosphate. At higher concentrations the end product tryptophan and indole-3-acetic acid inhibit the tryptophan synthase in vitro.     

The Influence of pH on the Cadmium-Repressed Growth of the Alga Coelastrum proboscideum

The inhibition of growth by different concentrations of CdCl₂ in the range 4,5 × 10^?7 to 5.6 × 10^?7M was studied in the green alga Coelastrum proboscideum Bohlin in inorganic media at pH 4.3, 5.3 and 6.2. The factorial destgn of the experiments was evaluated as an analysis of 2² factors. Below pH 4.0 and above pH 6.5 growth was depressed without adding Cd. Cd concentrations exceeding 5.6 × 10^?8M reduced algal growth significantly with a 50% inhibition at 5.6 × 10^?7M Cd. The Cd concentration of 5.6 × 10^?7M was less toxic at pH 6.2 than at pH 5.3 and 4.3, thus revealing a negative interaction between protons and Cd.     

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.     

Kinetics of N-substituted phenothiazines and N-substituted phenoxazines oxidation catalyzed by fungal laccases

Laccase-catalyzed oxidation of N-substituted phenothiazines and N-substituted phenoxazines was investigated at pH 5.5 and 25°C. The recombinant laccase from Polyporus pinsitus (rPpL) and the laccase from Myceliophthora thermophila (rMtL) were used. The dependence of initial reaction rate on substrate concentration was analyzed by applying the laccase action scheme in which the laccase native intermediate (NI) reacts with a substrate forming reduced enzyme. The reduced laccase produces peroxide intermediate (PI) which in turn decays to the NI. The calculated constant (k_ox) values of the PI formation are (6.1±3.1)×10⁵ M⁻¹s⁻¹ for rPpL and (2.5±0.9)×10⁴ M⁻¹s⁻¹ for rMtL. The bimolecular constants of the reaction of the native intermediate with electron donor (kred) vary in the interval from 2.2×10⁵ to 2.1×10⁷ M⁻¹s⁻¹ for rPpL and from 1.3×10² to 1.8×10⁵ M^-1s⁻¹ for rMtL. The larger reactivity of rPpL in comparison to rMtL is associated with the higher redox potential of type I Cu of rPpL. The variation of k_red values for both laccases correlates with the change of the redox potential of substrates. Following outer sphere (Marcus) electron transfer mechanism the calculated activationless electron transfer rate and the apparent reorganization energy are 5.0×107 M⁻¹s⁻¹ and 0.29 eV, respectively.     

Excitatory neuromuscular transmission in crayfish: Calcium dependence is unaffected by picrotoxin

Picrotoxin, 1 × 10^?5M to 1.6 × 10^?3M, had little or no effect on the amplitude of intracellularly recorded excitatory junctional potentials (EJPs) at extracellular calcium concentrations [Ca²⁺]₀ ranging from 0.5 to 15 mM. The slope of the log EJP vs. log[Ca²⁺]₀ relationship was approximately 1 with or without picrotoxin. The reduction of EJP amplitude resulting from the addition of 5 × 10^?5M GABA was largely reversed by 10^?5M picrotoxin.     

Isolation of Possible Intermediate of Chlorogenic Acid Biosynthesis in Sweet Potato Root Tissue

Thienodolin, a new plant growth-regulating substance, was isolated from the fermentation broth of a streptomycete strain identified as Streptomyces albogriseolus.

The active principle was extracted with ethyl acetate and purified by silica gel column chromatography and preparative HPLC. The substance showed growth promoting activity with 1.2 × 10^?6–1.2 × 10^?5 M treatment to rice seedlings, and inhibitory activity with 4.0 × 10^?5 M treatment.     

Inhibition of Lettuce Seed Germination and Root Elongation by Derivatives of Auxin and Reversal by Derivatives of Cycocel

Lettuce seed germination or lettuce root elongation after germination in water was inhibited by 5.7 × 10^-6M indoleacetic acid (IAA) and designated other IAA derivatives. These IAA-inhibited growth responses were reversed by 10^-5 to 10^-6M Cycocel, (2-chloroethyl) trimethylammonium chloride, which alone was without effect. Only those Cycocel analogs, which have previously been shown to be active as plant growth retardants, were effective in reversing IAA inhibition of germination or root elongation. These results are consistent with the concept that Cycocel at low concentrations acts as an auxin antagonist. However. Cycocel did not reverse the inhibitory effects from indole-3-propionic acid or indole-3-butyric acid.     

Cytokinin Reversal of Abscisic Acid Inhibition of Growth and α-Amylase Synthesis in Barley Seed

The effect of cytokinin, kinetin, on abscisic acid (dormin) inhibition of α-amylase synthesis and growth in intact barley seed was investigated. Abscisic acid at 5 × 10^?5M nearly completely inhibited growth response and α-amylase synthesis in barley seed. Kinetin reversed to a large extent abscisic acid inhibition of α-aniylase synthesis and coleoptile growth. The response curves of α-amylase synthesis and coleoptile growth in presence of a fixed amount of abscisic acid (6 × l0^?6M) and increasing concentrations of kinetin (from 5 × l0^?7M to 5 × 10^?5 M) showed remarkable similarity. Kinetin and abscisic acid caused synergistic inhibition of root growth. Gibberellic acid was far less effective than kinetin in reversing abscisic acid inhibition of α-amylase synthesis and coleoptile growth. A combination of kinetin and gibberellic acid caused nearly complete reversal of abscisic acid inhibition of α-amylase synthesis but not the abscisic acid inhibition of growth. The results suggest that factors controlling α-amylase synthesis may not have a dominant role in all growth responses of the seed. Kinetin possibly acts by removing the abscisic acid inhibition of enzyme specific sites thereby allowing gibberellic acid to function to produce α-amylase.     

Effects of nitrogen nutrition and root medium water potential on growth, nitrogen uptake and osmotic adjustment of rice

The effects of nitrogen (N) nutrition on growth, N uptake and leaf osmotic potential of rice plants (Oryza sativa L. ev. IR 36) during simulated water stress were determined. Twenty-one-day-old seedlings in high (28.6 × 10 ^?4M) and low (7.14 × 10 ⁴M) N levels were exposed to decreased nutrient solution water potentials by addition of polyethylene glycol 6000. The roots were separated from the solution by a semi-permeable membrane. Nutrient solution water potential was ?0.6 × 10⁵ Pa and was lowered stepwise to ?1 × 10⁵, ?2 × 10⁵, ?4 × 10⁵ and ?6 × 10⁵ Pa at 2-day intervals. Plant height, leaf area and shoot dry weight of high and low nitrogen plants were reduced by lower osmotic potentials of the root medium. Osmotic stress caused greater shoot growth reduction in high N than in low N plants. Stressed and unstressed plants in 7.14 × 10⁴M N had more root dry matter than the corresponding plants in 28.6 × 10⁴M N. Dawn leaf water potential of stressed plants was 1 × 10⁵ to 5.5 × 10⁵ Pa lower than nutrient solution water potential. Nitrogen-deficient water-stressed plants, however, maintained higher dawn leaf water potential than high nitrogen water-stressed plants. It is suggested that this was due to higher root-to-shoot ratios of N deficient plants. The osmotic potentials of leaves at full turgor for control plants were about 1.3 × 10⁵ Pa higher in 7.14 × 10^?4M than in 28.6 × 10^?4M N and osmotic adjustment of 2.6 × 10⁵ and 4.3 × 10⁵ Pa was obtained in low and high N plants, respectively. The nitrogen status of plants, therefore, affected the ability of the rice plant to adjust osmotically during water stress. Plant water stress decreased transpiration and total N content in shoots of both N treatments. Reduced shoot growth as a result of water stress caused the decrease in amount of water transpired. Transpiration and N uptake were significantly correlated. Our results show that nitrogen content is reduced in water-stressed plants by the integrated effects of plant water stress per se on accumulation of dry matter and transpiring leaf area as well as the often cited changes in soil physical properties of a drying root medium.