Meiosis in diploid and tetraploidPaeonia species

Dark, S. O. S.

doi:10.1007/bf02982520

Cited by 37 publications

(16 citation statements)

References 16 publications

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“…The present findings, though in accord with Darlington (1929Darlington ( , 1937, Sansome (1932), Dark (1936) and Darlington and Gairdner (1937) as regards the lack of chiasmata movement over the non-homologous segments , are different from the conclusions of Marquardt (1948), Hagberg (1954) and Price (1959). The studies of Marquardt (1948) on Oenothera and Price (loc.…”

Section: Discussioncontrasting

confidence: 99%

An Interchange Heterozygote in <i>Lycopersicon esculentum</i> Mill. and the Movement of Chiasmata over the Non-homologous Segments

Khanna

Chaudhary

1970

CYTOLOGIA

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Section: Discussioncontrasting

confidence: 99%

An Interchange Heterozygote in <i>Lycopersicon esculentum</i> Mill. and the Movement of Chiasmata over the Non-homologous Segments

Khanna

Chaudhary

1970

CYTOLOGIA

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“…Moreover, 1 or both synergids may persist at times and remain close to the zygote ( fig. 3 is suggestive of an endosperm nucleus, in that the number of chromosomes depicted is more than the diploid number reported for P. delavayi by Dark (1936). Before the zygote nucleus divides and even after the first few divisions it might appear that an appressed synergid was a cell of the developing zygote.…”

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confidence: 86%

Embryogeny in the California Peonies With Reference to Their Taxonomic Position

Cave

Arnott

Cook

1961

American J of Botany

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Cave, Marion S. (U. California, Berkeley), Howard J. Arnott, and Stanton A. Cook. Embryogeny in the California peonies with reference to their taxonomic position. Amer. Jour. Bot. 48(5): 397–404. Illus. 1961.—The embryogeny of Paeonia californica Nutt. ex T. and G. and P. brownii Dougl. ex Hook. is described. No cell wall is formed at the end of the first division of the zygote nucleus, but instead, a massive coenocytic proembryo is produced. This structure becomes cellular, and numerous embryo primordia form on its surface, one of which gains ascendancy over the others to form the embryo proper, consisting of root, shoot apex, epicotylar leaf primordium, and 2 cotyledons. The embryogeny of the California peonies is essentially similar to that of P. anomala, P. moutan, and P. wittmanniana described by Yakovlev and Yoffe, and does not support the contention of Murgai that in P. albiflora, P. actiflora, P. delavayi, and P. suffruticosa the coenocyte is a suspensor. It is suggested that the coenocytic embryos of gymnosperms and Paeonia represent a case of parallel evolution rather than that there is any implication of phylogenetic relationships between them.

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“…Interlocking has traditionally been considered to be rare in classical cytology, but as pointed out already in 1922 by GELEI (22) and later confirmed by several others (3,4,7,8,15,16,21,50), the congression of fortuitously distributed chromosomes may occasionally lead to interlocking of chromosomes and bivalents or as stated by GELEX: ,... kann daran kein Zweifel sein, dass in sehr seltenen F/illen auch ganz unl6sbare Konjugationsstellungen durch Ineinanderh~agen entstehen k6nnen.<< (22). The commonly accepted notion that interlocking is a rare phenomenon may have its origin in the fact that observations in the light microscope of the entangled late zygotene chromosomes are met with difficulties as the whole nucleus is either included in one thick section or squashed, the latter process being especially fatal for the analysis of the spatial relationship of the chromosome complement of a zygotene nucleus.…”

Section: Chromosome Pairingmentioning

confidence: 99%

Chromosome pairing, recombination nodules and chiasma formation in diploid Bombyx males

Holm

Rasmussen

1980

Carlsberg Res. Commun.

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Serial sectioning and three dimensional reconstruction of 82 nuclei divided into 15 well characterized substages covering the period from early zygotene to metaphase I in diploid Bombyx spermatocytes have permitted the following observations and conclusions: 1) At late zygotene, a mean of four chromosome and bivalent interlockings was found per nucleus. 2) During the transition from zygotene to pachytene, all interlockings resolve by breakage and reunion Of chromosomes or bivalents. 3) Recombination nodules first appear at early zygotene, reach a maximum of 91 per nucleus by late zygotene, decrease to 55 per nucleus at mid pachytene and increase again to 70-75 towards the end of pachytene. 4) At late z~cgotene and pachytene, nodules are essentially distributed at random among bivalents as well as along bivalents. 5) Small, but important deviations from randomness were, however, revealed: Three percent of the bivalents were without nodules at late zygotene, 8 % at early pachytene but at mid and late pachytene, only 2 % were devoid of nodules. 6) From mid pachytene, an increasing fraction of the recombination nodules becomes larger and more irregular in shape. These are termed chromatin nodules and at the pachytene-diplotene transition, nearly all nodules are of this type. 7) During early diplotene, the bulk of the chromatin decondenses leaving only about 60 major condensed domains. These domains originate from chromatin nodules and are frequently associated with a piece of synaptonemal complex which in its central region contains a dense core resembling a recombination nodule. 8) At late diplotene, the condensed domains of the bivalents consist of two dense chromatin segments, one on each of the homologues, and bridged by a complex circular structure giving the regions a characteristic tripartite appearance. 9) At mid diakinesis, the circular structures are located in chromatin bridges -chiasmata -between the homologous chromosomes. 10) The number of chiasmata per nucleus is constant from mid diplotene to mid diakinesis and is distributed among the bivalents similar to the distribution of recombination nodules at mid and late pachytene. 11) The circular chiasma components are eliminated from late diakinesis until metaphase I. 12) Finally, each metaphase I bivalent contains four distinct localized centromeres, two by two facing opposite spindle poles. 485

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Meiosis in diploid and tetraploidPaeonia species

Cited by 37 publications

References 16 publications

An Interchange Heterozygote in <i>Lycopersicon esculentum</i> Mill. and the Movement of Chiasmata over the Non-homologous Segments

An Interchange Heterozygote in <i>Lycopersicon esculentum</i> Mill. and the Movement of Chiasmata over the Non-homologous Segments

Embryogeny in the California Peonies With Reference to Their Taxonomic Position

Chromosome pairing, recombination nodules and chiasma formation in diploid Bombyx males

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