The control of chiasma distribution in the locust, Schistocerca gregaria (Forsk�l)

Fox, D. P.

doi:10.1007/bf00294277

Cited by 95 publications

(81 citation statements)

References 37 publications

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“…It is less easy to see an effect of the nucleolus organiser band on chromosomes L3 and M6 but in both these cases the posi- tion of the band corresponds with the position of minimum chiasma frequency of these chromosomes (excluding the centric regions). Furthermore, there are other indications of a difference in the pattern of chiasma formation in these two chromosomes since the mean interference distance is greater than in other chromosomes of similar total length (Fox, 1973). The exact comparison between G-band position in mitotic chromosomes and chiasma position in diplotene chromosomes is complicated by two factors.…”

Section: Results and Discij55ionmentioning

confidence: 99%

“…Recently, Fox (1973) has described the detailed pattern of chiasma distribution along the chromosomes of the Desert locust. In fig.…”

Section: Results and Discij55ionmentioning

confidence: 99%

“…The exact comparison between G-band position in mitotic chromosomes and chiasma position in diplotene chromosomes is complicated by two factors. (i) The determination of chiasma position within chromosomes is subject to some error (Fox, 1973). (ii) 'While the mitotic chromosomes are more or less uniformly condensed along their length, the diplotene chromosomes are not, being more condensed in the centric regions which are heterochromatic at this stage (Fox, 1973).…”

Section: Results and Discij55ionmentioning

confidence: 99%

“…vidual chromosomes at diplotene (Fox, 1973) or embryo neuroblast metaphase (Fox, 1966;K. Carter, unpublished work) is complicated by the fact that they differ essentially only in length.…”

mentioning

confidence: 99%

“…In estimating chiasma position the autosomes in each of 541 diplotene cells were ranked in order of decreasing length and each rank position was treated as a homogeneous population. However, in some case several different homologues are known to be present in the population of one rank position (Fox, 1973). Three techniques have proved to be successful in producing banding in locust chromosomes.…”

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confidence: 99%

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Giemsa banding and chiasma distribution in the Desert locust

1973

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Section: Results and Discij55ionmentioning

confidence: 99%

“…Recently, Fox (1973) has described the detailed pattern of chiasma distribution along the chromosomes of the Desert locust. In fig.…”

Section: Results and Discij55ionmentioning

confidence: 99%

Section: Results and Discij55ionmentioning

confidence: 99%

“…vidual chromosomes at diplotene (Fox, 1973) or embryo neuroblast metaphase (Fox, 1966;K. Carter, unpublished work) is complicated by the fact that they differ essentially only in length.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

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Giemsa banding and chiasma distribution in the Desert locust

1973

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The origin of aneuploidy: Bivalent instability and the maternal age effect in trisomy 21 Down syndrome

Hultén

2005

Am. J. Med. Genet.

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The mechanism behind the high rate of maternal first meiotic non-disjunction and the maternal age effect in trisomy 21 is unknown. Much attention has been paid to the causal role of univalence 21 by lack of chiasma formation. Here I suggest that not only achiasmatic bivalents may be susceptible to nondisjunction, but the chiasmatic bivalent shape per se may play an important role. Considering the topology of the chiasmata and the orientation of the bivalent at first meta-and anaphase, some bivalent shapes may have a greater segregational potential than others. For any one chromosome there may at first meta-and anaphase be an optimal balance between chromosome coiling/condensation on the one hand and chiasma frequency distribution on the other. Chromosome coiling/ condensation may play an interesting dual role in both determining bivalent flexibility and dictating chiasma formation. I propose that the higher rate of double-and triple-chiasma bivalents 21 in oocytes contributes to its higher rate of spontaneous first meiotic nondisjunction; and the maternal age effect is associated with chromosome laxity, secondary to an impairment of appropriate chromosome coiling/condensation in oocytes of older women. In spermatocytes of older men some compensatory increase in chiasma frequency with a shift towards double-and triple-chiasma bivalents 21 might take place, i.e., if a general age-related chromosome decondensation is counteracted by an auto-regulatory "length effect" remaining intact in pachytene spermatoeytes.Received for publication June 29, 1990 Hassold and Takaesu, 1989; Mikkelsen, 1989; Hassold, 19901. The mechanism behind this, and in particular the maternal age effect, is unknown. Here I suggest that further consideration should be given to the causal role of bivalent instability at first meiotic meta-and anaphase. I propose 1) that a higher spontaneous rate of chromosome 21 non-disjunction may arise a t female first meiosis in comparison to the male by differences in chiasma frequency distribution in oocytes and spermatocytes, and 2 ) that this difference may be enhanced by an age-related impairment of chromosome condensation, leading to a greater bivalent instability in women than in men.Chromosome length is an important factor behind chiasma frequency with reduced frequency in shorter chromosomes [Mather, 19371, but a t least one chiasma is necessary for normal first anaphase segregation. This so-called obligate chiasma is thought to ensure the correct orientation of the 2 homologues within the metaphase plate and lack of chiasma formation will give rise to non-disjunction by random segregation [Darlington, 1937; Henderson and Edwards, 19681. Less attention has been paid to the relevance ofbivalent shape per se. It seems likely that the single-chiasma bivalent 21 is a considerably more stable structure than the double-and triple-chiasma bivalent, when considering the topology of the interchiasmatic loop configurations and their respective orientation in relation to the spindle and the equatorial plate [ F...

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Meiosis: Recombination and the Control of Cell Division

Jenczewski

Mercier

Macaisne

et al. 2012

Plant Genome Diversity Volume 2

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HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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The control of chiasma distribution in the locust, Schistocerca gregaria (Forsk�l)

Cited by 95 publications

References 37 publications

Giemsa banding and chiasma distribution in the Desert locust

Giemsa banding and chiasma distribution in the Desert locust

The origin of aneuploidy: Bivalent instability and the maternal age effect in trisomy 21 Down syndrome

Meiosis: Recombination and the Control of Cell Division

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