摘要:

Zamia chigua, an arborescent cycad of the Pacific coast of Colombia, South America, has been found to have chromosome numbers of 2n= 22, 24, 25 and 26. Specimens collected from two adjacent populations displayed this range of numbers with karyotypes differing principally in the numbers of telocentric and metacentric chromosomes present in each; 2n= 22, 24, 25, 26 plants were found to have 4, 2, 1 and 0 metacentrics and 12, 16, 18, and 20 telocentric chromosomes, respectively. Because all plants examined in the field demonstrated high fertility, it is inferred that meiosis and fertilization are essentially normal despite differences in chromosome numbers.

ISSN:0008-7114    

DOI:10.1080/00087114.1981.10796889

出版商:Taylor & Francis    

年代:1981

数据来源: Taylor

摘要:

Sister chromatid exchange (SCE) frequencies in « in vitro » cultures of human lymphocytes were analysed after exposure to non toxic concentrations of epichlorohydrin (1×10−5M, 1×10−8, 1×10−11M). High sensitivity of SCE test allowed to point out a gradual increase of SCE frequency. In particular, 1× 10−8MECHH, which had proved unable to increase the frequency of structural chromosome aberrations, was indeed able to induce a significant increase of SCE.

ISSN:0008-7114    

DOI:10.1080/00087114.1981.10796890

出版商:Taylor & Francis    

年代:1981

数据来源: Taylor

ISSN:0008-7114    

DOI:10.1080/00087114.1981.10796891

出版商:Taylor & Francis    

年代:1981

数据来源: Taylor

摘要:

Melanagromyza obtusais a serious pest ofCajanus indicusin the Oriental region, particularly noticed in India, Java and Malaya. The mitotic and salivary gland chromosomes were studied for the first time. A map of its salivary gland chromosomes has been constructed and some identifiable land-marks in each arm of the chromosome are recognized. Analysis of population samples from three different geographical localities has yielded two overlapping paracentric inversions in the X-chromosome.

ISSN:0008-7114    

DOI:10.1080/00087114.1981.10796892

出版商:Taylor & Francis    

年代:1981

数据来源: Taylor

摘要:

A castor plant trisomic for chromosome 2 (2n+ 1 =21) was identified by pachytene analysis. Chromosomes 2 and 7 contained nucleolar organizers in or adjacent to the terminal heterochromatic segment of their respective short arms and, in both, this segment was heteromorphic. The trisomic plant was vigorous, had 92% pollen stainability, and was partially female fertile.

ISSN:0008-7114    

DOI:10.1080/00087114.1981.10796893

出版商:Taylor & Francis    

年代:1981

数据来源: Taylor

摘要:

Leaves of two varieties ofWeigelia floridaDC., the one with green leaves and the other with variegated leaves, showing green center and white-yellowish margin, have been studied by light and electron microscope. From light microscope observations, the variegated variety ofWeigelia floridaDC., seems to be a periclinal chimaera of green-white-green type. The epidermis of the variegated leaves appears to be both phenotypically and genotypically « green », whereas the epidermis of the green leaves does not contain developed plastids. In the variegated leaves, the plastids of cells, originated from L II layer, show great alterations.

ISSN:0008-7114    

DOI:10.1080/00087114.1981.10796894

出版商:Taylor & Francis    

年代:1981

数据来源: Taylor

摘要:

Without any elaborate post-fixation treatment, dot-like kinetochores in the somatic metaphase chromosomes ofAllium cepawere stained differentially with 2% aceto-orcein after storage of the air dried squashes of colchicine treated and acetic-ethanol fixed root meristems for an optimum period of 3–4 weeks. Similar results were obtained also forAloe vera, Rhoeo spathaceaandTradescantia virginianachromosomes. The probable mechanism of this differential stainability has been discussed.

ISSN:0008-7114    

DOI:10.1080/00087114.1981.10796895

出版商:Taylor & Francis    

年代:1981

数据来源: Taylor

摘要:

Cytogenetic studies in the diploid and polyploid species and cytotypes of the genusThemeda, collected from India have been undertaken. Diploid species had 2n= 20 chromosomes and they wereT. anathera, T. tremula, T. strigosa, T. hookeriandT. mooneyii.The last three indicated the existance of 0 to 3 supernumerary chromosomes during meiosis. Their behaviour has been discussed. T.villosa, T. caudata, T. quadrivalvisand a cytotype ofT. triandrawere found to be tetraploids with 2n= 40 chromosomes. From the pairing behaviour it was considered that the first two were either autopolyploids with gene controlling their pairing behaviour or may be genomic allotetraploids. The other two were categorised as segmental allopolyploids. T.longispathawith 2n= 50 is a pentaploid and possibly an auto-allo-pentaploid as seen from its chromosomal behaviour and hybrid nature. The two hexaploids with 2n= 60 areT. arundinaceaandT. dacruzii.The former appeared to be a segmental allohexaploid while the latter from its cyto-morphological behaviour seems to have evolved from diploid species of T.anathera.The octaploid (2n= 80) nonaploid (2n= 90) and endecaploid (2n= 110) are cytotypes ofT. triandra.The first one has been categorised as segmental allo-octaploid while the other two have been considered as auto-alloploids. The nature of polyploidy in the species ofThemedathat were collected from different parts of India has been discussed.

ISSN:0008-7114    

DOI:10.1080/00087114.1981.10796896

出版商:Taylor & Francis    

年代:1981

数据来源: Taylor

摘要:

A single male individual ofTryxalis indicaexhibited a reversion of normal XO sex-chromosome mechanism to XY. The change also resulted in a decrease of diploid chromosome number from normal 23 to 22. A comparison of the karyotype and behaviour of neo-XY during first meiotic division related this change to the fusion of original acrocentric X chromosome, with one of the Li autosomes to give rise to the submetacentric neo-X while the homologous autosome transformed into the neo-Y.

ISSN:0008-7114    

DOI:10.1080/00087114.1981.10796897

出版商:Taylor & Francis    

年代:1981

数据来源: Taylor

摘要:

The occurrence of two plastid types (« normal » chloroplasts and abnormal plastids) in leaves of variegated mutants of Eurya, Cape pittosporum and star jasmine has been verified by light and electron microscopy. These mutants are interpreted as periclinal chimaeras (mesochimaeras of the GWG-type). In all the three plants examined abnormal plastids are irregularly shaped and devoid of any definite lamellar system, although a large number of vesicles and plastoglobuli occupy the electron-dense stroma.

ISSN:0008-7114    

DOI:10.1080/00087114.1981.10796898

出版商:Taylor & Francis    

年代:1981

数据来源: Taylor