摘要:

Une plante dePetuniaaux fleurs striées est apparue à la suite d'un traitement de zygotes aux rayons gamma. L'examen cytologique de ce variant a permis de constater qu'un chromosome VI, porteur de deux loci liésA (=An2)et R (=Rt), intervenant dans la synthèse des anthocyanes, était devenu annulaire. L'analyse des comportements cytologiques,—mitotique et méiotique,—et génétique de cette plante striée nous a amenés aux conclusions suivantes:

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796803

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

An investigation ofKrigia cespitosaRaf. (2n=8) revealed an unusually high frequency of non-homologous chromosome associations due to stickiness. Despite this, meiotic behaviour and plant fertility were unaffected.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796804

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

The study on the extent of chromosomal variations in suspension cultures initiated from hypocotyl segments ofPisum sativumvar. Arkel andVigna sinensisvar. black reveals aberrations like inhibition of cell plate formation, spindle abnormalities, chromosomal breakage, polyploidy and aneuploidy. Such aberrations are frequently observed mostly in aneuploid cells and their frequencies increase with the number of passages. Asynchronous behaviour of daughter nuclei resulting in multinucleate cells is observed more frequently in cultured tissues of P.sativumL. than inVigna sinensisvar. black. In progressively older passages ofVigna sinensisvar. black diploid cell populations gradually increase more rapidly than the tetraploid and aneuploid cells, indicating the selective advantage of diploid cells over others. By contrast in progressively old passages ofPisum sativumL. the frequencies of cells with 11 and 12 chromosomes are high. In the resulting cell population a range from 7 to 14 chromosomes could be noticed indicating instability. Anaphase bridges occur in almost the same frequency in both the species. Some other features of the chromosomal variations have been described.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796805

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

The location and activity of the nucleolus organizers (NOs) in a mouse strain (CD) carrying centric fusions have been studied. The chromosomes showing morphologically evident secondary constrictions have been identified by Q-banding as number 16 (t 9/16), 17 (t 5/17) and 19. It has been shown by Ag staining that all the secondary constrictions are the sites of active NO genes and that chromosome number 19, carrier of the longest secondary constriction, is always more heavily Ag-stained and more frequently involved in the organization of the nucleolus.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796806

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

Ultrastructural features of the compatible pollen tube ofPrunus avium(L.) growingin vivoare described. During its growth the tube has four different zones reflecting a functional specialization. The cytoplasm of the apical or growth zone contains two types of secretory vesicles probably involved in the formation of the tube wall. The sub-apical zone, in addition to the secretory vesicles, shows the presence of dilated rough endoplasmic reticulum (RER) cisterns containing electron-dense material which does not react to the test for polysaccharides. In the nuclear zone the vegetative nucleus and the generative cell can be observed; this zone is followed by the vacuolization and callosic plug formation one.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796807

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

The histones/DNA ratio has been calculated in the 2C nuclei from the primary root meristems of young and old caryopses ofTriticum durum.In a first experiment young and old caryopses taken from different crops were considered in one and the same trial, at the same time. In a second experiment young and old caryopses taken from the very same crop were considered in different trials at different times. In both cases 2C meristematic nuclei of old caryopses show a higher amount of DNA bound histones and smaller average nuclear area as compared to 2C meristematic nuclei of young caryopses. The possible significance of this variations in histones/DNA ratio and in nuclear areas detected in the study is discussed.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796808

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

Chromosome analysis was carried out in a family with a history of 7 spontaneous abortions. A balanced translocation involving the terminal parts of chromosomes 7 and 18 was found in a normal female and in her father. The Giemsa-banding pattern suggests that a balanced reciprocal translocation has occurred.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796809

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

A method, similar to BSG method, which seems to stain selectively plant nucleolus organizing regions is described. The critical step is a mild hydrolysis applied to Carnoy fixed root apices after squashing. The method has been tested onVicia fabaand also on individuals ofBellevalia dubiaandOrnithoglum montanum(Liliaceae) selected because of heteromorphic nucleolus organizing regions.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796810

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796811

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

The modifications which accompany the growth ofNostoc punctiformein culture media containing various forms of mineral nitrogen were described by light and electron microscopy. The presence of 0.012M NaN03and 0.04M NH4Cl inhibit heterocyst formation, while lower doses reduce their frequency. Parallel to the disappearance of heterocysts is the disappearance of the aseriate stage, so that the whole culture is made by long filaments formed by vegetative cells and, in particular conditions, by cells similar necridia and discs. When grown in presence of nitrogen compounds, the vegetative cells contain numerous and large cyanophycin granules. The higher large amounts of nitrates induce the formation of particular vegetative cells deprived of cyanophycin and enveloped in abundant mucilage. Some of these particular cells are similar to analogous found in the gonidial zone of coralloid roots of Cycads. The absence of true spores in the different culture media is discussed.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796812

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor