Chromosomes Of Vicia Faba Research Articles

On the induction of segment extension and chromatid structural changes in Vicia faba chromosomes after treatment with 5-azacytidine and 5-azadeoxycytidine

When root tips of Vicia faba were treated with 5-azacytidine (5-ACR) or 5-azadeoxycytidine (5-ACD) local uncoiling (segment extension) of specific chromosome segments and chromatid aberrations was produced. The peak of cells with segment extension was observed 2–8 h after treatment (non-delayed effect); cells with chromatid aberrations appeared after recovery times of more than 20 h (delayed effect). Colchicine labelling of cells after 5-ACR treatment showed that chromatid aberrations were present in 4n cells, i.e., they became induced during the interphase preceding the second mitosis. 5-ACR post-treatment after X-raying increased the frequency of X-ray-induced chromatid aberrations, and pretreatment was without influence on the aberration yield induced by X-rays alone. The preliminary conclusion drawn from the experimental results is that segment extension is due to the inhibition of RNA and, concomitantly, protein synthesis or the failure of complex formation between DNA and specific proteins. The incorporation of the analogues into DNA is presumed to be responsible for the induction of chromatid aberrations.

The production of chromosomal aberrations by propanesultone in Vicia faba

Some effects of 1,3-propanesultone, a bifunctional alkylating agent, on the chromosomes of Vicia faba were studied. Treatment with 8·10 −3M for 1 2 h at 30° induced a significant number of chromosomal aberrations. The spectrum of aberrations included chromatid and isolocus breaks, deletion-duplications and chromatid exchages. The total number of exchanges increased linearly with the dose up to 12·10 −3 M, but higher concentrations proved lethal. Aberrations began to appear around 24 h and reached a peak value at 48 h after treatment. Whereas a significantly increase in the number of aberrations was observed with increase in temperature, the effects of 1,3-propanesultone were independent of pH. A pre-treatment with 2,4-dinitrophenol increased the rate of aberration. Like many other chemical mutagens, 1,3-propanesultone induced breaks in a nonrandom fashion. It preferentially attacked S chromosomes. As the breaks were mainly of the chromatid type and delayed it seems that 1,3-propanesultone is effective at the early synthetic phase of the cell cycle. The results are described and discussed in relation to the effects of other known radiomimetic agents.

Non-random distribution of X-ray-induced achromatic lesions (“gaps”) in the chromosomes of Vicia faba

Non-random distribution of X-ray-induced achromatic lesions (“gaps”) in the chromosomes of Vicia faba

Влияние извне поданной ДНК разного происхождения на митоз и хромосомы облученных меристематических клеток Vicia faba

In this paper we compare the influence of heterologous and isologous DNA on the radiation damage repair of primary root meristematic cells ofVicia faba. Roots, irradiated by exposure of 150 r were cultivated at different time intervals either in tap water, or in a solution of heterologous or isologous DNA. In comparing mitotic activity of meristematic cells it was found that both types of DNA studied enhance the recovery of irradiated cells. The frequency of postmetaphase chromosomal aberrations of irradiated cells was influenced also by post-irradiation action of exogenous DNA. While heterologous DNA exhibited synergical effect with radiation in the sense that it increased the post-irradiation incidence of aberrations in all time intervals studied, isologous DNA had a strong repair effect—the application caused a significant decrease of the percentage of post-metaphase aberrations. Both kinds of DNA caused changes in the relation of chromosome to chromatid aberrations; a higher percentage of chromatid aberrations was registered. The study of the distribution of aberrations between large and small chromosomes ofVicia faba showed that the post-irradiation application of heterologous DNA increases damage of small chromosomes while isologous DNA caused an increased repair ability in this chromosomal group.

The effect of diepoxybutane on chromosomes of Vicia faba.

The frequency of aberrations induced by DEB depends on the temperature and concentration of the agent. The effect of DEB is delayed. Pretreatment with EDTA increased the frequency of aberrations. The frequency of aberrations was also increased after simultaneous treatment with DEB and chloramphenicol or streptomycin. Pre- and posttreatment with protein synthesis inhibitors had a reverse effect, the frequency of aberrations was decreased.

Strandedness of Chromosomes From Two Species of Vicia

Recent experiments (1) have revealed subchromatid structure in chromosomes of Vicia faba after trypsin digestion. Although the chromosome number is the same in V. faba and another member of this genus, V. sativa. V. faba has been found to have approximately 5 times the amount of DNA per nucleus as V. sativa (2). Because it is unlikely that V. faba has genetic loci not represented in sativa in numbers sufficient to account for the noted differences in DNA content, it seems probable that the differences are a reflection of redundancy of the DNA in V. faba, either laterally, to produce true multistrandedness, or linearly, to produce a longer singlestranded chromosome. In an effort to investigate this possibility, chromosomes from the two species were studied with both light and electron microscopy to compare the apparent strandedness of the two species both untreated and after trypsin digestion.

Chromosome breakage induced in vicia faba by a monofunctional alkylating derivative of acridine

Abstract 1. (1) The chromosome-breaking ability of the monofunctional nitrogen mustard derivative of acridine, 2-methoxy-6-chloro-9-[3-(ethyl-2-chloroethyl) aminopropylamine]acridine dihydrochloride (ICR-170), on chromosomes of Vicia faba has been demonstrated. 2. (2) It is concluded that chromatid-type aberrations are induced in cells in G1, S and G2 and subchromatid type of aberrations in cells in prophase in the first mitosis (T1) after treatment, and that chromosome-type aberrations recovered after ICR-170 treatment are not from G1 cells of T1 mitosis but are products in T2 mitosis of duplication of chromatid-type aberrations of T1 mitosis. 3. (3) The action of the monofunctional alkylating component of the ICR-170 molecule seems to play a predominant role in aberration induction.

Induction of Mitotic Abnormalities in Certain Genera of Tribe Vicieae by Paradichlorobenzene

Effect of paradichlorobenzene on somatic chromosomes of Vicia faba, V. narbonensis, V. hirsuta, Pisum arvense and Lathyrus sativus was studied after giving a prolonged treatment. Various mitotic anomalies were encountered. These included shortening and thickening of chromosomes, precocious separation of chromatids, tetraploid cells, binucleate cells, chromosome bridges and chromosome breakage. The potentiality of PDB as a mutagenic substance had been emphasised and terms like PDB-treatment, PDB-mitosis and PDB-metaphase were suggested for convenient use. Chromosome breaks generally took place at the heterochromatic regions.

Strandedness of Vicia faba chromosomes as revealed by enzyme digestion studies.

Chromosomes and nuclei isolated from neutral formalin-fixed Vicia faba lateral roots were treated with trypsin, pepsin, RNase, or DNase. Only trypsin affected the morphology of the chromosomes and nuclei. The appearance of the chromosomes after trypsin digestion indicated that each chromatid contained four strands that could be seen with an ordinary light microscope. The experiments are interpreted as indicating that mitotic chromosomes of Vicia faba are multistranded and that the linear continuity of the chromosome is dependent on protein.

Chromosome breakage induced by fluorinated thymidine in secondary roots of Vicia faba

The effect of 5-trifluoro-methyl-2-deoxyuridine was studied on Vicia faba chromosomes with a view to compare its effect with that of 5-fluorodeoxyuridine. Gaps and breaks started to appear even after one hour treatment and their frequency increased in treatments of longer duration. Chromosomal regions which were late in their replication were found to break more than the other chromosome regions. No rejoining of broken chromosomes was observed. The effects produced resembled those of 5-fluorodeoxyuridine. It is suggested that breaks are probably produced both in G 2 and S period of interphase.

Radiation effect on incorporation of tritiated valine in chromosomes of Vicia faba.

RECENT work on radiation-induced structural changes in chromosomes has suggested that protein synthesis is a major process involved in the restitution of chromosomal fragments1,2. The work recorded here was undertaken to investigate by means of autoradiography the incorporation of tritiated valine into the structural chromosomal protein of Vicia faba during the post-irradiation period in which chromosomal restitution occurs.

Radiation-induced increase in H 3-valine incorporation by the chromosomes of Vicia faba

Germinating seeds of Vicia faba were divided into three groups. Group 1 was irradiated with 1000 R of X-rays while immersed in an H 3-valine solution and remained in the isotopic solution during the post-irradiation period in which chromosomal restitution is known to occur. Group 2 was irradiated with an equal dose while immersed in water and transferred to an H 3-valine solution after the restitution period. Group 3 served as a control and was immersed in tritiated valine for a period of time equal to the restitution period but was not irradiated. Grain counts were made over interphase nuclei before the initiation of cell divisions in the primary root tip and compared between irradiated and non-irradiated cells. Grain counts over the chromosomes and over the cytoplasm were scored at the first mitotic divisions ( X1) of the cells of the primary root and compared among the three treatments. Germinating seeds were also irradiated with X-ray doses ranging from 300 to 1000 R while immersed in H 3-valine and remained in the isotopic solution during the restitution period. Grain counts over X1 metaphase chromosomes were scored and a dose response curve was constructed. Chromosomes from tissue irradiated with 1000 R while immersed in the tritiated valine solution and which remained immersed during the restitution period (Group 1) showed an approximately 2·5 times greater labelling than those from non-irradiated controls (Group 3). Grain counts over chromosomes from tissue irradiated with 1000 R and transferred to the H 3-valine solution after the restitution period (Group 2) were not significantly different from the non-irradiated controls. The level of cytoplasmic labelling did not change significantly after irradiation with 1000 r of X-rays. Grain counts over chromosomes from tissue exposed to doses ranging from 300 to 1000 R increased exponentially with dose.

Uptake of 3H-thymidine and patterns of DNA replication in nuclei and chromosomes of Vicia faba

1. 1. A significant incorporation of 3H-thymidine into the DNA of root tip cells of Vicia faba is shown to occur within 5 min of exposure to the labelled precursor. 2. 2. When roots are exposed to water after a 30 min 3H-thymidine treatment, all the labelled compound is used up or washed out within 10 min of removal from the active solution. However, post-treatment of roots with a high concentration of inactive thymidine, following a water wash, results in a slow depletion of the “hot” pool, labelled thymidine being available for incorporation into DNA for up to 40 min after the removal of the roots from the “hot” solution. 3. 3. The distribution of grain counts between nuclei exposed for short periods to 3H-thymidine does not conform to a Poisson distribution, the data suggesting a basic exponential rate of incorporation by the cell nuclei. 4. 4. Observations on interphase nuclei and metaphase chromosomes of cells exposed to 3H-thymidine at various periods during the S phase show ( a) that DNA replication is initiated at a large number of sites over the chromosome complement, there being no sequential progression from the distal to proximal chromosome regions, and ( b) that replication in the heterochromatic chromosome zones is confined to late S. 5. 5. The available information on the time of DNA replication in eu- and heterochromatin in a variety of species is reviewed, the evidence indicating that positive heteropycnotic regions, whether in sex chromosomes or in autosomes, always undergo a late replication. The possibility that this delayed replication of heterochromatin is associated with genetic inactivity and the presence of arginine-rich histone is discussed.

Incorporation of 3H-arginine in chromosomes of Vicia faba

3H-arginine was used in an effort to label the nuclear protein of Vicia faba root meristem cells. Prior to labeling, the root tips were treated for 24 hr with 5-aminouracil in order to synchronize cell divisions and obtain a large proportion of mitolic figures. Autoradiographs of chromosomes from the first and second division after labeling were examined. Almost 100 per cent of the chromosomes in the first division were labeled. The marked absence of label in metaphase chromosomes at second division suggests turnover of a major fraction of nuclear protein during one cell division cycle.

Effect of mitomycin C on lateral root-tip chromosomes of Vicia faba.

Lateral root-tip chromosomes of Vicia faba were treated with mitomycin C. Chromatid aberrations were observed from 24 through 96 hours after treatment. The effect of mitomycin C was not altered appreciably by changes in p H, temperature, oxygen tension, or lack of adenosine triphosphate. The relationship of mitomycin C to other radiomimetic compounds is discussed.

Strukturheterozygotie beiVicia faba

The karyotypes and the meiotic behaviour of two spontaneous reciprocal translocations and one pericentric inversion are described. One of these translocations was characterized by chiasma-formation in the interstitial-segments, the other was not. The types of orientation and distribution of the chromosomes from the chain-configurations in meta-anaphase I are specified, compared mutually and with those of translocation rings and chains in maize and the similarities and differences are pointed out. In the range of the heterozygous pericentric inversion there was no pairing in meiotic prophase and therefore no chiasma formation and sterility. It will be tried to cross especially one of the translocations with the inversion-type in order to rebuild the karyotype ofVicia faba. In this case it would be possible to distinguish between all five pairs of small chromosomes according to their morphological structure, a possibility very important in localizing chromosome aberrations on the chromosomes ofVicia faba.

Comparative studies on the distribution of breakage induced by various mutagens in chromosomes of Vicia faba L

1. The distribution of X-ray and chemically induced breaks over the 4 groups of morphologically distinguishable chromosomes of Vicia faba (2n=12) was compared. X-ray induced breaks were distributed nearly at random with statistically significant minima at the ends and small maxima in the middle of the long arms of the small chromosomes, whereas there was a random break-distribution in the large SAT-chromosome. Concerning the distribution of breaks induced by an automutagenic, as yet chemically unidentified substance produced by anaerobiosis during soaking of seeds, there were statistically significant maxima in the middle of the long arms of the m-chromosomes and on both sides of the centromere of the SAT-chromosome when the breaks induced by the two mutagenic agents were compared. 2. The theoretical expectation of break-distribution between SAT- and m-chromosomes according to their length is approximately 2∶5. We could not verify this relation for X-rayinduced breaks, finding proportions of 1,2∶5,0 and 1,44∶5,0 respectively. We therefore feel inclined to emphasize an important role of indirect action in case of X-rays. Possibly SAT- and m-chromosomes differ in structure and therefore react in different ways with the X-ray induced modified products of the chemical cell constituents. 3. Chromatid translocations induced by the automutagenic substance were more abundant in special regions. This crowding-effect did not appear after X-raying.

Respiration and Radiosensitivity of Broad Bean Roots

IN the root-tips of the broad bean, Vicia faba, potassium cyanide, hydrogen sulphide and cupferron (the ammonium salt of nitrosophenylhydroxylamine) increase the frequency of chromosome aberrations produced by a given dose of X-rays at very low oxygen pressures1–3. In the case of cupferron at least, the effect on radiosensitivity seems to be a result of its inhibitory action on the respiration of bean root tips3. The fact that oxygen enhances the radiosensitivity of the root-tip chromosomes of Vicia faba has been known since the studies of Thoday and Read4. When the roots are respiring normally an oxygen effect does not become evident until the concentration of oxygen in the gas phase exceeds 3 per cent, apparently because at lower concentrations oxygen is removed by respiration in the outer cells of the root, so that completely anaerobic conditions prevail in the central parts. When respiration is inhibited, oxygen is able to diffuse into the cells of the whole meristem, even in cases when the oxygen concentration outside the root is very low. That this is the correct explanation of the increased frequency of aberrations obtained in the presence of cupferron is indicated by the fact that cupferron has no marked influence on radiosensitivity in the complete absence of oxygen3.

Distribution of fragmentation and achromatic spots on chromosomes of Vicia faba after treatment with heavy metal salts

1. Die Anzahl der Fragmentationen und achromatischen Stellen auf den beiden Chromosomengruppen der Wurzelspitzenmitose vonVicia faba (2 grose = SAT-Chromosomen und 5 kleine = m-Chromosomen) wurde in Abhangigkeit von verschiedenen Konzentrationen (10−2 bis 10−5 mol.) von Eisen-, Kobalt-, Nickel-, Kupfer-, Chrom-, Kadmium-, Mangan-, Zinknitraten bestimmt. 2. Die spontanen Fragmentationen sind auf die SAT-Zone und Insertionsregion der grosen Chromosomen beschrankt sowie auf die 3 mittleren Regionen der kleinen Chromosomen. Nach Schwermetalleinwirkung finden sich auf dem SAT-Chromosom 5, auf den kleinen Chromosomen 3 weitere bruchempfindliche Stellen. 3. Die Bruche verteilen sich ungleichmasig uber das Genom, wobei eine spezifische Reihenfolge in der Bevorzugung der SAT-Chromosomen zu erkennen ist. Die Extreme sind Mangan mit einem Verhaltnis m: SAT-Chromosom = 5∶145,0 und Kupfer mit 5∶3,8 (normal 5∶2,0). Die Kontrolle (Einwirkung des Nahrmediums) besitzt ein Verhaltnis von 5∶28,7. 4. Kupfer ruft unabhangig vom Nahrmedium (rechnerisch ermittelt) allein auf den kleinen Chromosomen eine grosere Anzahl von Fragmentationen hervor als auf den grosen, wobei die Wirkung im Bereich der Insertionsstelle liegt. 5. Die verwendeten Schwermetalle greifen in allen Konzentrationen die SAT-Chromosomen bevorzugt an; doch findet in Abhangigkeit von der Konzentration eine statistisch gesicherte Verschiebung der Bruchhaufigkeit auf diesen Chromosomen statt, wobei zwischen der SAT Zone und der Insertionsregion ein Empfindlichkeitswechsel stattfinden kann. 6. Die achromatischen Stellen treten bevorzugt auf den kleinen m-Chromosomen auf. Wie bei den Bruchen findet sich auch hier eine Verschiebung der Empfindlichkeit bestimmer Chromosomenorte in Abhangigkeit von der Konzentration. 7. Die Lage der heterochromatischen Bezirke vonVicia faba wird im Hinblick auf die Fragmentationsbereitschaft untersucht. Es konnte gezeigt werden, das Bruche und achromatische Stellen an eben diesen Chromosomenorten bevorzugt auftreten.

A Comparison of the Sensitivity of Mitotic and Meiotic Chromosomes of Vicia Faba and Its Bearing on Theories of Crossing-Over

A Comparison of the Sensitivity of Mitotic and Meiotic Chromosomes of Vicia Faba and Its Bearing on Theories of Crossing-Over