Vicia Faba Seedlings Research Articles

Über die Abhängigkeit der relativen biologischen Wirksamkeit hochenergetischer Bremsstrahlen von der durchstrahlten Materieschicht / Dependence of the Relative Biological Efficiency of High Energy Bremssstrahlen on the Depth in a Phantom

The Relative Biological Efficiency (RBE) of 6-GeV-bremsstrahlung on 3-days-old seedlings of Vicia faba was investigated with the Deutsches ElektronenSynchrotron. Dosimetry was carried out by means of the butanol-sensitized FeII/FeIII-reaction. In a Lucite-phantom we observed an increase of the RBE from 0,65 at the surface to values of about 2 at a depth of 40 cm. As changes of that order of magnitude are doubtless beyond the limits of the maximum experimental error we suppose that production of heavy particles by nuclear reactions such as (γ, n) or (γ, p) in deeper layers of matter might cause an increase of the linear energy transfer of the beam.

The rôle of the host plant in the production of winged forms by two strains of the pea aphid, Acyrthosiphon pisum

Aphids of both strains of Acyrthosiphon pisum can produce alate daughters after experiencing a controlled period of contact with other aphids. This response is maternal, embryos being irrevocably determined as apterae or alatae very shortly before birth. Females of the green strain crowded soon after the onset of parturition did not produce many alate offspring when reared exclusively on seedlings of the bean Vicia faba. When the insects fed on mature bean leaves after the 24 hr crowding treatment the proportion of alatae in their progenies was more than doubled. Besides being influenced by the diet imbibed after the crowding experience, the maternal response was conditioned by the host plant offered the test insects during their larval development. Bean seedling host plants decreased the proportion of alatae subsequently produced, while mature bean leaves had the reverse effect. The production of numerous alatae in response to the combined influence of crowding and a mature leaf host was rapidly halted when the parent aphids were transferred to bean seedlings. Often all larvae subsequently deposited became apterae. Aphids of the pink strain studied here were particularly sensitive to contact with other aphids, and readily produced large numbers of alatae even when feeding on bean seedlings. Nevertheless, more alatae appeared in the progenies of crowded females caged on mature bean leaves. Females of both strains reared singly on bean seedlings prior to the onset of parturition started to deposit alate daughters within 72 hr of being transferred without crowding to mature leaves. Progressively greater numbers of these forms were produced as larviposition continued. This response appeared earlier in the case of females reared singly on mature leaves from birth onwards. Two varieties of the pea Pisum sativum had a particularly pronounced effect on alata-production by females of the green strain. Regardless of whether the aphids imbibed sap from pea seedlings before or after a crowding treatment, the majority produced no alate progeny whatsoever. The response of the pink aphids was not as easily influenced by this factor. When previously crowded apterae of the green strain reproduced on mature pea leaves, a response developed of comparable intensity to that of insects confined on bean seedlings. Fewer alatae were produced by females caged on excised mature pea leaves fed with glucose and amino acids than on leaves fed with a pure glucose solution.

Effect of protracted ultrasonic irradiation on the growth of seedlings of Vicia faba.

ULTRASOUND is being used increasingly in medicine—both for diagnostic techniques and for therapy—and in industrial processes1,2. The nature and extent of the biological effects of such radiations are, however, still uncertain. Certainly at high intensity damage results from a rise in temperature in the organism, but it seems likely that other, non-thermal effects may occur. Breakdown of DNA in solution has been observed3, and the streaming of fluids which has been demonstrated within cells may produce damage4. Lethal effects in Daphnae have also been reported5 in conditions where the possibility of any fatal temperature rise could be excluded. This preliminary communication reports an effect of irradiation in a small ultrasonic cleaning bath on the growth of the main tap root in Vicia faba seedlings.

The effect of hypoxia on recovery of sublethal radiation damage in Vicia seedlings.

Abstract Seedlings of Vicia faba were used as a test system to investigate the recovery of sub-lethal radiation damage. Groups of seedlings were exposed to single and fractionated doses under four treatment regimes; air present during the irradiations and during the interval between dose fractions; air present during the irradiations but hypoxic conditions between the doses; hypoxia during the doses but air available between doses; hypoxia maintained both during and between the irradiations. It was found that some degree of recovery of sub-lethal damage took place under all conditions, but the amount of recovery was substantially reduced if a state of hypoxia was maintained between the dose fractions. The state ofoxygenation during the X-ray exposures was relatively unimportant.

The isolation and properties of a fungicidal compound present in seedlings of Vicia faba

The isolation of a fungicidal compound in 0.001% yield from healthy broad bean seedlings by extraction with benzene is described. After column chromatography, purification was achieved by low temperature recrystallisation from hexane, using ultra-violet light absorption, inhibition of spore germination ofAlternaria brassicicola and thin layer chromatography as criteria of purity. The compound has been given the name wyerone. Its in vitro activity against phytopathogens and dermatophytes and its protectant and eradicant activity against certain fungal pathogens of plants are reported.

Nucleic Acid Metabolism of Vicia faba during Germination and Growth

AbstractDuring the growth of Vicia faba seedlings in the absence of an external nitrogen supply, the cotyledons decreased rapidly in dry weight and nucleic acid content. In the developing shoot the dry weight increased rapidly for four weeks and then very slowly over the next two weeks growth; the nucleic acid content of the shoot increased to a maximum after 4 weeks growth and decreased in amount during the next 2 weeks. On the other hand the roots increased in both dry weight and nucleic acid content throughout the growth period, although they only accounted for a small proportion of the total dry weight and nucleic acid content of the plant. These changes during germination and growth are discussed in relation to those occurring during these developmental stages in other plants.

Study of the Dependence of Photosynthetic Yields on the Water and Mineral Supply

The dependence of photosynthetic yields on both sodium adsorption ratio and osmotic pressure of irrigation water in Vicia faba seedlings is discussed. Bean seedlings were exposed to C14O2 in closed photosynthetic chambers for 24 h, in the same way described in Part 1 of this series. The chromatographic study of aqueous and alcoholic extracts as well as the acid hydrolysed tissue is described in a collective manner. Data concerning soluble sugars and mineral contents are being represented. The respiration rates of three-week seedlings are compared with their photosynthetic metabolites.

Correspondence

Mr. W. E. Liversage was kind enough to show us in advance a copy of his letter which appears in this issue of the journal so that we may make a few comments. We would like to place on record that we think he has quoted our results fairly and accurately, and we would agree with his overall conclusion that in a situation where our experimental findings are applicable, then one would expect to find a lowered O.E.R. for a high dose-rate fractionated regime as well as for a low dose-rate continuous exposure treatment. There are, however, two areas where we disagree: the first is a philosophical point and is a question of how far one should go in applying radiobiological data to radiotherapy, and the second is that we consider the pooling of data in Figs. 1 and 2 of his letter to be misleading. Firstly the whole basis of the reasoning of Liversage is the statement in the first paragraph of his letter that the findings of Hall and Cavanagh (1967) “are of considerable significance to clinical radiotherapists”. This we believe to be an overstatement of the case. Our results were obtained with a simple basic radiobiological test system (seedlings of Vicia faba) in which extreme hypoxia was precisely defined to be the presence of less than 10 p.p.m. of oxygen.

The oxygen effect for acute and protracted radiation exposures measured with seedlings of Vicia faba.

Seedlings of Vicia faba have been used to measure the oxygen enhancement ratio (O.E.R.) for acute X-ray and protracted γ-ray exposures at 3°C and 19°C. At 3°C there was no significant difference between the O.E.R. for acute or protracted exposures (2·67 and 2·70 respectively). At 19°C the O.E.R. was significantly lower for protracted than for acute exposures (2·06 compared with 2·58). There was found to be no recovery between splitdoses delivered under hypoxic conditions in contrast to the marked recovery which takes place when the irradiation is carried out under conditions of normal aeration.

On the Population Kinetics of the Root Meristem of Vicia faba Exposed to Continuous Irradiation

The significance of cell cycle time in relation to radiation sensitivity under continuous exposure is a subject of considerable interest in radiobiology. Lamerton and Lord (1) have reported that for rats the epithelium of the small intestine, which has a short cell cycle, showed a much greater tolerance to continuous irradiation than the bone marrow, for which the intermitotic period is longer. These same workers have also described preliminary results with two transplantable mouse tumors, which indicate that the tumor with the shorter cell cycle was the more resistant to continuous irradiation (1). Lamerton pointed out that these results were consistent with the attractive theory that the shorter the cell cycle, the less is the effect of a given dose rate. The present communication reports an inverse relationship between sensitivity to continuous exposure and length of cell cycle in seedlings of Vicia faba. Seedlings of Vicia faba offer, in many ways, a unique opportunity to study the effects of irradiation on a relatively simple organized system. The patterns of root growth at 19?C during continuous exposure at dose rates between 0.32 and 11.4 rads/hour have been described in detail by Hall (2). Mathematical models have been suggested for the relationship between division and differentiation in the normal and irradiated meristem (3, 4), and computer calculations, based on these models, of the cell population kinetics under continuous irradiation have produced theoretical curves of root growth very similar to those observed experimentally (5). These theoretical calculations have predicted the same growth pattern for a given dose per cell cycle independent of cycle time, in keeping with the relationship suggested by Lamerton. Evans and Savage (6) have reported that the average intermitotic period of the root meristem cells of Vicia cultured at 12?C is about twice that for roots grown at 19?C. Thus, by the use of the two culture temperatures, the dose response could be

The effect of sulphoguanidine and p-nitrobenzoic acid on the chromosome breakage-reunion process by gamma-, x- and beta-irradiation in Vicia faba.

SummaryPrimary roots of Vicia faba seedlings were irradiated with gamma-, x- and beta-rays in a sulphoguanidine solution. Analysis of anaphase aberrations showed that the breakage-reunion index (which is the number of anaphase fragments per bridges) in the middle of the first mitosis after irradiation, is constant, and at low doses is independent of the intensity and quality of ionizing radiation.The breakage-reunion index indicates that after irradiation in the presence of sulphoguanidine, twice as many breaks enter into reunion as in distilled water. This cytological effect of the sulphoguanidine was suspended by p-aminobenzoic acid, folic acid, arginine and guanine, as well as by 2,4-dinitrophenol and chloramphenicol. Therefore, the sulphoguanidine effect seems to be connected with the chromosomal histone and DNA-synthesis. p-nitrobenzoic acid has the same effect as the sulphoguanidine. The cytological effect of these compounds was linked with a radiosensitizing effect, manifested in root-growth inhibition.

Effect of Gibberellic Acid on the Phosphate Availability in Vicia faba Seedlings using P32

Gibberellic acid when sprayed to the tops of Vicia faba seedlings even in lower concentration, causes significant changes in the physiology of the plant. Simultaneous spray of gibberellic acid and Knop solution brings about an increase in the rate of P32-uptake. Gibberellic acid shows some inhibitory effects on the absorption and/or translocation of radioactive phosphorus from the roots to the leaves. Delayed treatments with Knop solution shows similar results to those of the direct treatments except at the highest concentration.

Isoenzymatic nature of L-glutamic dehydrogenase of higher plants.

ELECTROPHORESIS of albumins of mature seeds of Vicia faba on polyacrylamide gel, with subsequent location of L-glutamic acid dehydrogenase (L-glutamate: NAD oxidoreductase (deaminating) EC 1.4.1.2) (GDH), using a tetrazolium procedure, revealed that this enzyme could be separated into a number of isoenzymes. A preliminary investigation has been made of these isoenzymes together with an examination of their distribution within the seeds and seedlings of Vicia faba (broad bean) and Pisum sativum (pea).

ORGANELLE DISTRIBUTION IN THE STATOCYTE CELLS OF THE ROOT‐TIP OF VICIA FABA IN RELATION TO GEOTROPIC STIMULATION

SummaryBy means of the electron microscope a study has been made of the changes in organelle distribution in the cells of the root cap of Vicia faba seedlings resulting from a 20 minute geotropic stimulation in the horizontal position. From photographs of whole cells at constant magnification, counts were made of the numbers of amyloplasts, mitochondria and dictyosomes in each of four equal quarters of the cell divided along, and transverse to, the main root axis. The volumes of the characteristic endoplasmic reticulum masses per cell quarter were also measured.The only bodies showing marked sedimentation to the lower side of the cell were the amyloplasts. The dictyosomes showed a small but statistically significant displacement into the quarter not occupied by the amyloplasts but since their concentration per unit of cytoplasm did not change, it was inferred that they moved passively in the cytoplasm displaced by the sedi‐menting amyloplasts. Similar trends were shown by the mitochondria but these did not reach 5% significance levels. There also appeared to be significant displacement of the endoplasmic reticulum masses into the upper halves of the cells.The implications of these findings are discussed in the context of current theories of gravi‐perception in plants.

A COMPARISON OF THE EFFECTS OF ACUTE AND PROTRACTED GAMMA-RADIATION ON THE GROWTH OF SEEDLINGS OF VICIA FABA. II. THEORETICAL CALCULATIONS.

SummaryObservations with Vicia faba on the reduction of root ‘growth in ten days’ with increase of time-interval between two exposures, are analysed and indicate an approximately exponential recovery in the dose equivalent of sub-lethal damage with time after the first exposure, half-times of about 0·7 and two hours applying at 19° and 3·5°c respectively.Calculations are made of the theoretical dose response curves which are derived for exposure at 8·4, 1·52 and 0·89 rads/hour based on a survival curve for acute exposure of the form consistent with those results of previous experiments.Theoretical values of acute exposures equivalent to various protracted exposures agree well with the experimental results for 3·5°c where there is no significant cell-division during the exposure.

The Recovery of Vicia faba Meristem Cells from X-Radiation

With the roots of Vicia faba seedlings used as a test system, the effect of two doses of x rays separated by a variable time interval is described. The results are used to infer the rate of recovery of radiation damage in Vicia meristem celis, a rate shown to vary with the temperature at which the roots are stored between doses. (auth)

Argininosuccinic Acid in Germinating Seeds of Vicia faba L.

THE ornithine cycle amino-acids have been determined in ungerminated seeds and 6- and 14-day-old seedlings of Vicia faba L. grown without an external source of nitrogen.

Radioactive Oxygen in the Study of Gas Transport down the Root ofVicia faba

SUMMARY The movement of labelled oxygen down the main root of Vicia faba seedlings was studied. The rise of radioactivity in the roots at 15 and 18 cm. below the cotyledons follows the same kinetics as the transport of radioactive gas down a thin polythene tube open at one end. It is therefore consistent with diffusion of oxygen through continuous gas spaces in the roots. Loss of oxygen to the sur rounding tissue is small in the upper parts of the roots. The volume of the gas spaces was estimated from the equilibrium radioactivity and compared with data obtained by filling the spaces with paraffin oil.

Effect of colchicine on the utilization of thymidine labelled with tritium during chromosomal reproduction.

EXPERIMENTS1 designed to verify the findings of Taylor, Woods and Hughes2 on the incorporation of thymidine labelled with tritium in the deoxyribonucleic acid in chromosomes of growing root meristems of seedlings of Vicia faba have produced evidence that colchicine influences either the synthesis of the acid or its subsequent distribution among sister chromatids at metaphase. This evidence was derived from two types of experiment.

The nucleic acid content of cells in the meristematic elongating and fully elongated segments of roots of Vicia faba

By combined cell counting and biochemical assay, the mean DNA and RNA content of the cells in the root tip of Vicia faba seedlings has been measured. The values for segments 0–2, 2–4, 4–8 and 12–20 mm behind the root cap were found to be, for DNAP, 3.5 7 ± 0.2 0, 4.00 ± 0.20, 4.5 5 ± 0.3 7 and 4.7 0 ± 0.3 2, 10 −12 grams, and for RNAP, 14.2 ± 0.54, 16.1 ± 0.63, 18.0 ± 0.99, and 16.5 ± 0.86, 10 −12 grams. The approximate amounts of phosphorus per cell in other forms were also estimated. The nucleic acid determinations show that the mean DNA content per cell steadily increases with distance from the root apex, being 30 per cent greater in the proximal segment, which is composed mainly of fully differentiated cells, than in the terminal segment, which is entirely meristematic. Thus, if the average meristematic cell at the commencement of interphase is assumed to have a diploid content of DNA, then the mean DNA content of the differentiated cells is approximately tetraploid.