摘要:

Germinated and hydrated ungerminated pollen grains ofTradescantia virginianawere examined by light and electron microscopy. Contrary to previous generalisations these binucleate grains were found to possess highly organised cytoplasmic structures. They were able to germinate within a few minutes and achieve maximum rates of tube extension immediately. Quantitative studies showed that the secretory vesicle population in the grain cytoplasm was substantial (5.3 × 105vesicles per grain), though not as large as reported for trinucleate grains. It is concluded that these binucleate grains are intermediate in their characteristics between slow germinating binucleate pollen grains and rapidly germinating trinucleate grains.

ISSN:0008-7114    

DOI:10.1080/00087114.1983.10797670

出版商:Taylor & Francis    

年代:1983

数据来源: Taylor

摘要:

Both males and females of the fishProchilodus scrofahave a diploid number of 2n= 54. However, with the exception of a single female, all 59 specimens (25 ♀, 34 ♂) studied had 1–5 minutes accessory chromosomes. The unstable behavior of these chromosomes during mitosis and meiosis as well as their heterochromatic nature, as detected by C-banding, are characteristics that emphasize their supernumerary nature. This is the first report of chromosomes of this type in the Osteichthyes (Pisces).

ISSN:0008-7114    

DOI:10.1080/00087114.1983.10797671

出版商:Taylor & Francis    

年代:1983

数据来源: Taylor

摘要:

A method is described for obtaining complete, well-spread synaptonemal complexes of human oocytes for light and electron microscopic examination. Preliminary karyotypes from each technique are presented. Examination of a cell from an aborted XXX fetal ovary revealed trivalent pairing of the X chromatids.

ISSN:0008-7114    

DOI:10.1080/00087114.1983.10797672

出版商:Taylor & Francis    

年代:1983

数据来源: Taylor

摘要:

By resorting toin vitrotechnique in inducing apogamy and apospory, diploid (polyhaploid, 2n= 58) and octoploid (2n= 232) plants have been produced from the natural tetraploid (2n= 116)Pteris vittataL. The ameiotic behaviour of the apogamously induced diploid (polyhaploid) establishes this species to be a genomic allopolyploid. Four kinds of sporangia, 16-, 32-, and 64-spored and sporangia with unequal spores and sporads were produced on the same individual. This analysis has revealed how in one step the tetraploid could have been formed in nature from hybrid diploid. It is suggested that this approach could be useful in analyzing the true nature of other sexually reproducing polyploid fern taxa.

ISSN:0008-7114    

DOI:10.1080/00087114.1983.10797673

出版商:Taylor & Francis    

年代:1983

数据来源: Taylor

摘要:

The chromosomal analysis of various wild laboratory strains ofDrosophila ananassae, a cosmopolitan domestic species, has shown that there is quantitative variation in the frequencies of different gene sequences occurring due to the cosmopolitan inversions. In some strains the chromosomes with inverted gene orders occur at frequencies higher than those of standard. The heterogeneity observed in the frequencies of a given gene arrangement among different strains seems to be due to the differences in allelic contents of the chromosomes. The results also reveal that there is an excess of inversion heterozygotes which in some strains reaches statistical significance. This indicates that the degree of heterosis may vary depending on the gene contents of the chromosomal variants. These results combined with those previously obtained clearly indicate that the pattern of chromosomal polymorphism in D.ananassaedoes not resemble that of other cosmopolitan species such asD. melanogaster,D. busckiiand others.

ISSN:0008-7114    

DOI:10.1080/00087114.1983.10797674

出版商:Taylor & Francis    

年代:1983

数据来源: Taylor

摘要:

Results of a preliminary karyological study of bulgarian populations ofVicia hirsutaandV. meyeriare reported. Diploid chromosome number 2n= 2x=14 was observed in all populations studied. The karyotypes of the two species are characterized by quite similar chromosome types and a high level of symmetry. Along with that, certain differences are evident. The karyotype ofV. meyericonsists of slightly longer chromosomes. Most obvious difference is observed in the SAT-chromosome pair morphology; inV. hirsutait possesses a smaller satellite attached to the short arm; inV. meyerithe satellite is considerably larger than that inV. hirsuta.It is equal in length to the shorter arm, from which it is separated by a secondary constriction.

ISSN:0008-7114    

DOI:10.1080/00087114.1983.10797675

出版商:Taylor & Francis    

年代:1983

数据来源: Taylor

摘要:

Karyotypic analyses of 41 specimens ofForpus xanlhopterygius(Psittaciformes: Aves) reveal a diploid number of 86 and three different karyotypes were observed. A chromosomal polymorphism is present which involves two pairs of chromosomes. It is suggested that the observed polymorphism resulted from a translocation involving pairs 1 and 5. The significance of this intrapopulation variation is discussed.

ISSN:0008-7114    

DOI:10.1080/00087114.1983.10797676

出版商:Taylor & Francis    

年代:1983

数据来源: Taylor

摘要:

The karyotypes of thirteen species of Uruguayan ants belonging to three different subfamilies (Myrmicinae, Dolichoderinae and Formicinae) are reported. Among eight myrmicines studied, the chromosome numbers of four species ofPheidole (P. cornutula, P. fallax, P. spinninodisandP. strobeli)were all 2n= 20 (orn= 10). A count of 2n= 32 (orn=16) was obtained forSolenopsis saevissima, while 2n= 38 occurred in three leaf-cutter ants of the genusAcromyrmex [A. (Acromyrmex) ambiguus, A. (A.) hispidusandA. (Moellerius) heyeri]. The one dolichoderinae ant examined,Conomyrma pyramica, had 2n= 18 and three species ofCamponotus, C. bonariensis, C. punctulatusandC. rufipes(Formicinae), showed a relatively high number 2n= 40 (orn=20) compared to that inC. mus(2n= 26).

ISSN:0008-7114    

DOI:10.1080/00087114.1983.10797677

出版商:Taylor & Francis    

年代:1983

数据来源: Taylor

摘要:

Studies on the correlations between the length of the pericentromeric heterochromatin block and the internal structural complexity of chromosomes showed significance for some chromosomes both in Psittaciformes and Columbiformes. In Columbiformes, internal rearrangements resulting in translocation of portion of pericentromeric heterochromatin to interstitial chromosome regions seem to have occurred in the interspecific homologous chromosomes for which negative regression was obtained. In Psittaciformes, it is possible that in the homologues for which positive regression was obtained, part of the heterochromatin that was added by fusion and translocation processes from microchromosomes and macrochromosomes may have been transferred to the pericentromeric region.

ISSN:0008-7114    

DOI:10.1080/00087114.1983.10797678

出版商:Taylor & Francis    

年代:1983

数据来源: Taylor

摘要:

The cytogenetic effects of an analgesic antipyretic agent, metamizole, on bone marrow cells of Swiss albino male mice were studied. Animals were administered orally with 3.9, 7.8 and 15.6 mg of the drug in 0.5 ml quantities for only once (single dose series) and thrice at 24 hr intervals (cumulative dose series) and cytological preparations were made from bone marrow cells 24, 48 and 72 hr after treatment. Mitotic indices and chromosome anomalies including gaps, breaks, fragments, terminal deletions and polyploid nuclei were analysed statistically. A strong inhibition of mitotic frequency was observed with the highest doses in the cumulative dose series while it was apparently transient in the single dose series. Gaps were seen frequently. The drug appears to possess an extremely mild clastogenic but no perceivable c-mitotic potency.

ISSN:0008-7114    

DOI:10.1080/00087114.1983.10797679

出版商:Taylor & Francis    

年代:1983

数据来源: Taylor