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Abstract
ABSTRACT
The F, hybrids of Nicotiana suaveolen (subgenus Petunioides, 2n = 32) and N. glutinosa (subgenus Tabacum, 2n = 24), were examined during their development, from seedlings to mature plants. It was observed that in the hybrids, there was a progressive change of dominant N. glutinosa morphological characteristics towards those of N. suaveolens, in leaf shape, stem, flower color and branching pattern. A study of mitotic chromosomes in the root-tips and in very young anthers of the mature plants indicated a significantly high average frequency of aberrant mitotic anaphases (bridges and fragments, 12% and 11 % respectively). As a consequence of this phenomenon, variability in the number and size of chromosomes was observed in the PMC's and in mitotic metaphases (29-24 chromosomes). In order to establish whether the N. glufinosa chromosomes were preferentially last, a karyological study of the parents and their F, hybrids was carried out and it was established that the F, hybrids were losing N. glutinosa chromosomes preferentially. A mechanism was suggested for the loss of these chromosomes by means of a chromatid type of breakage-fusion-bridge cycle (b-f-b cycle) and initiation of the b-f-b cycle in the hybrid due to an interaction of the regulatory mechanism of DNA replication in the haploid genomes of the parental species. However, loss of these chromosomes owing to interaction of certain genes from the two parental species cannot be ruled out.
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Affiliation(s)
- S B Gupta
- Department of Biology, Kenyon College, Gambier, Ohio 43022
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Affiliation(s)
- S B Gupta
- Department of Genetics, University of Alberta, Edmonton, Canada
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Gupta SD, Gupta JS, Gupta SB, Mahajan BG. Steroid induced glaucoma (experimental study). J All India Ophthalmol Soc 1969; 17:14-6. [PMID: 5371045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Gupta SD, Gupta JS, Gupta SB. Effect of topical and systemic steroids on intra-ocular tension and aqueous outflow facility. J All India Ophthalmol Soc 1969; 17:17-23. [PMID: 5371046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Dhir SP, Agarwal LP, Gupta SB, Detels R, Wang SP, Grayston JT. Trachoma vaccine trial in India: results of two-year follow-up. Indian J Med Res 1968; 56:1289-94. [PMID: 5711608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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Gupta SB. THE UNSTABLE BEHAVIOR OF A CHROMOSOMAL FRAGMENT OF NICOTIANA PLUMBAGINIFOLIA RESPONSIBLE FOR CHLOROPHYLL VARIEGATION IN N. TABACUM. Genetics 1968; 59:453-63. [PMID: 17248414 PMCID: PMC1212015 DOI: 10.1093/genetics/59.4.453] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- S B Gupta
- Department of Genetics, University of California, Berkeley
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Rastogi SK, Sethi SK, Gupta SB. Ventricular aneurysm: a case report. Indian Heart J 1968; 20:332-7. [PMID: 5705274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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