Non-disjunction and maternal age in D. melanogaster
نویسندگان
چکیده
منابع مشابه
Maternal age and origin of non-disjunction in trisomy 21.
The role of maternal age in chromosomal non-disjunction was investigated by studying 51 families in whom the origin of the meiotic anomaly had been identified. Results of this study were compared with previously published data. This comparison did not show any difference in mean maternal age, nor in distribution of maternal ages when the origin of non-disjunction was maternal, or paternal, or o...
متن کاملGenic control of chromosome loss and non-disjunction in Drosophila melanogaster.
HROMOSOME nondisjunction, the failure of the members of a chromosome ‘pair to separate to the two daughter nuclej, was first described by BRIDGES (1913,1916). Theoretically, nondisjunction of the X chromosomes in XX females should result in the production of equal numbers of nullo-X and diplo-X gametes. Consequently, the two resulting classes of viable exceptional off spring, patroclinous sons ...
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ception to this rule in Drosophila melanogaster has been termed non-random disjunction (NOVITSKI 1951). Here it has been found that homologs are recovered unequally frequently from females when they are heteromorphic, or of unequal size. When this is the case, the smaller of the two homologs is recovered about twice as frequently as the larger. The genetic analysis has suggested, as the basis f...
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although there are studies on pragmatic assessment, to date, literature has been almost silent about native and non-native english raters’ criteria for the assessment of efl learners’ pragmatic performance. focusing on this topic, this study pursued four purposes. the first one was to find criteria for rating the speech acts of apology and refusal in l2 by native and non-native english teachers...
15 صفحه اولNon-disjunction of chromosome 18.
A sample of 100 trisomy 18 conceptuses analysed separately and together with a published sample of 61 conceptuses confirms that an error in maternal meiosis II (MII) is the most frequent cause of non-disjunction for chromosome 18. This is unlike all other human trisomies that have been studied, which show a higher frequency in maternal meiosis I (MI). Maternal MI trisomy 18 shows a low frequenc...
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ژورنال
عنوان ژورنال: Genetical Research
سال: 1963
ISSN: 0016-6723,1469-5073
DOI: 10.1017/s0016672300003633