摘要:

The effects of the mutagens hydroxylamine, ethyl methane sulphonate and gamma rays separately and in combination were studied on the meiotic chromosomes in the M1generation of an inbred strain ofPennisetum typkoides.The significant findings were as follows:

ISSN:0008-7114    

DOI:10.1080/00087114.1971.10796406

出版商:Taylor & Francis    

年代:1971

数据来源: Taylor

摘要:

The study of meiosis performed on 53 triploidZea maysplants revealed the occurrence of 1.48 I per cell in metaphase I, an unbalanced disjunction of chromosomes in anaphase I (the 15-15 type being only 32.66% in frequency) and a relatively high frequency of laggards and micronuclei. Consequently, the pollen fertility is low (44.58%) and the offspring 3nplants shows forms with 17-42 chromosomes, with a clear predominance of hyper triploids (81.0%).

ISSN:0008-7114    

DOI:10.1080/00087114.1971.10796407

出版商:Taylor & Francis    

年代:1971

数据来源: Taylor

摘要:

The trispecific hybridP. squamulatumx amphidiploid(P. typhoidesxP. purpureum)bad 2n=48 chromosomes. The pairing of chromosomes in meiosis revealed the existence of homology of chromosomes of the parental species.

ISSN:0008-7114    

DOI:10.1080/00087114.1971.10796408

出版商:Taylor & Francis    

年代:1971

数据来源: Taylor

摘要:

Occurrence of terminal knobs on the chromosomes ofEriantbus elephantinusandErianthus ravennaepossessing twenty somatic chromosomes was observed. This is the first report of chromosome knobs in the genusErianthus.

ISSN:0008-7114    

DOI:10.1080/00087114.1971.10796409

出版商:Taylor & Francis    

年代:1971

数据来源: Taylor

摘要:

According to the morphology and behaviour of chromosomes and to the kinetic of the mitotic events, the embryonic mitosis ofAscidiella aspersahas been divided into 6 well distinguishable phases: prophase, prometaphase, metaphase, anaphase, anatelophase and telophase.

ISSN:0008-7114    

DOI:10.1080/00087114.1971.10796410

出版商:Taylor & Francis    

年代:1971

数据来源: Taylor

摘要:

Experiments were performed to study the protective property of 5 × 10−2M cysteine and 2 × 10−3M glutathione against radiation induced chromosome damage in the root tips ofHordeum vulgare.The protective ability was examined by scorings in anaphase cells 24 hours after 200, 400 and 600r of X-irradiation. It was found that cysteine showed a more significant level of protection against radiation induced chromosome fragments, fragments and bridges or bridges than did glutathione.

ISSN:0008-7114    

DOI:10.1080/00087114.1971.10796411

出版商:Taylor & Francis    

年代:1971

数据来源: Taylor

摘要:

The kinetochores of the first meiotic divisions ofLilium longiflorumappear less electron-dense than the majority of the chromatin, are roughly spherical, and consist of fine fibrils 10–20 nm in diameter. The fine structure observed here appears to be consistent with several previous studies by other workers on higher plants. However, many variations in the observed fine structure of kinetochores of both plants and animals appear in the literature. Possible sources of the discrepancies in the observations are variations in interpretation of electron micrographs, variations in fixation procedures, and variations due to genuine phylogenetic differences of the organisms studied.

ISSN:0008-7114    

DOI:10.1080/00087114.1971.10796412

出版商:Taylor & Francis    

年代:1971

数据来源: Taylor

摘要:

The embryonic mitosis ofClavelina lepadiformisis characterized by the presence of precociously separating daughter kinetochores and by an extreme shortening of chromosomes during prophase and prometaphase. The chromosomes ofClavelina lepadiformisare all metacentric; differentiated sex chromosomes are not present. The same haploid number of chromosomes,n=9, has been found in both populations of the Lagoon of Venice and of the west coasts of Scotland. Both oocyte and spermatocyte bivalents possess chiasmata.

ISSN:0008-7114    

DOI:10.1080/00087114.1971.10796413

出版商:Taylor & Francis    

年代:1971

数据来源: Taylor

摘要:

The course of embryonic mitosis ofPhallusia mammillatacan be characterized by it short duration, the occurrence of precociously separating daughter kinetochores, the somatic association of homologous chromosomes and by the precociously uncoiling of chromosomes at late anaphase.

ISSN:0008-7114    

DOI:10.1080/00087114.1971.10796414

出版商:Taylor & Francis    

年代:1971

数据来源: Taylor

摘要:

The variegated mutant P 17 characterized by the presence of dicentric chromosomes was induced by X-irradiation of pollen with 750 R. This dicentric chromosomes is persistant and transmissible; both centromeres are active and the intercentromeric region is long enough to allow the formation of criss-cross and parallel double bridges. Mitotic behaviour of the dicentric chromosome determines a mixochimeric structure wich causes a mosaic phenotype pattern. Associations of the dicentric with more than two chromosomes at metaphase I shows that the dicentric chromosome is heterodicentric.

ISSN:0008-7114    

DOI:10.1080/00087114.1971.10796415

出版商:Taylor & Francis    

年代:1971

数据来源: Taylor