Heterochromatin variation and sex chromosome polymorphism in &lt;i&gt;Nesokia indica: &lt;/i&gt;a population study

Rao, Satyawada Rama; Vasantha, K; Thelma, B.K.; Juyal, Ramesh C.; Jhanwar, Suresh C.

doi:10.1159/000131873

Cited by 17 publications

(14 citation statements)

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“…The control cultures of all 14 individuals had a diploid chromosome complement (2n = 42; Rao et al, 1983). The metacentric X and Y chromosomes are, respectively, the largest and second largest chro mosomes in the complement.…”

Section: Resultsmentioning

confidence: 99%

Folate-sensitive fragile sites on the X-chromosome heterochromatin of the Indian mole rat, Nesokia indica

Tewari

Juyal

Thelma

et al. 1987

Cytogenet Genome Res

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Folate-sensitive fragile sites have been demonstrated on the X chromosome of the Indian mole rat, Nesokia indica (subfamily Murinae), utilizing peripheral blood lymphocyte cultures. All normal female individuals expressed fragile sites on the constitutive heterochromatic long arm of one of their two X chromosomes (heterozygous expression); in contrast, no fragile sites were found on the single X chromosome of normal males. Preferential transmission of the maternal fragile X to the daughters is therefore suggested. Four sites have been detected so far: fra Xq1, fra Xq2, fra Xq3, and fra Xc (centromeric). It is significant that their location corresponds to the regions where constitutive heterochromatic deletions occur that result in a variety of polymorphic X chromosomes in natural populations of Nesokia. Thus there is a correlation between fragile sites, deletion sites, and karyotypic changes. In individuals that did not reproduce in the laboratory, there were more fragile sites on both X chromosomes of the females (homozygous/double heterozygous expression) and also on the X of the males (hemizygous expression). This difference in fragile site expression from the normal situation could be attributed to one or more new mutations. However, the mechanism by which fragile sites influence reproductive performance is unclear.

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Section: Resultsmentioning

confidence: 99%

Folate-sensitive fragile sites on the X-chromosome heterochromatin of the Indian mole rat, Nesokia indica

Tewari

Juyal

Thelma

et al. 1987

Cytogenet Genome Res

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“…Akodon azarae (Lizarralde et al. 1982) , and Nesokia indica (Rao et al. 1983), and a variety of ex planations have been given by the authors.…”

Section: Origin O F Heterochromatic Segments Anil O F Their Variable mentioning

confidence: 98%

Heterogeneous heterochromatin and size variation in the sex chromosomes of Micvotus cabrerae

Burgos¹,

Jiménez²,

Olmos³

et al. 1988

Cytogenet Genome Res

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The sex chromosomes of Microtus cabrerae are characterized by large segments of constitutive heterochromatin in both the X and Y. Alkali treatment, enzymatic digestion (trypsin), and fluorochrome staining reveal considerable heterogeneity within these heterochromatic blocks and allow us to distinguish several regions. In addition, variation in the length of these segments is also present, probably as a result of deletions. A possible explanation for the origin of these heterochromatic blocks is discussed.

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“…Highly-heterochromatic sex-chromosomes exhibit hypervariability in many groups of organisms and this is normally quantitative in character (Hamerton, 1971;Mengden 1981;Vorontsov eta!., 1980). In the human Y, for example, the long arm varies more or less continuously with respect to its C-band content while a single population of the rodent Nesokia indica contained three distinct Ymorphs in equilibrium proportions (Rao et a!., 1983).…”

Section: Introductionmentioning

confidence: 99%

Continuous variation in Y-chromosome structure of Rumex acetosa

Wilby

Parker

1986

Heredity

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The dioecious angiosperm Rumex acetosa has an XXIXY1Y2 sex-chromosome system. Each V-chromosome is heterochromatic except for a minute terminal euchromatic pairing segment. The Vs are constant in size but have a variable centromere position. The centromeres can be located anywhere within the central 40 per cent of the chromosome but are excluded from the two distal 30 per cent regions. In a sample of 270 males from 18 different populations 68 distinct variants have been identified on the basis of V-morphology. All populations are highly polymorphic with a minimum of four variants in a sample of ten males. The origin and significance of this massive variability is considered in this paper. Increased mutation rate of the Ys may be implicated in maintenance of this variation.

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Heterochromatin variation and sex chromosome polymorphism in <i>Nesokia indica: </i>a population study

Cited by 17 publications

References 4 publications

Folate-sensitive fragile sites on the X-chromosome heterochromatin of the Indian mole rat, <i>Nesokia indic</i><i>a</i>

Folate-sensitive fragile sites on the X-chromosome heterochromatin of the Indian mole rat, <i>Nesokia indic</i><i>a</i>

Heterogeneous heterochromatin and size variation in the sex chromosomes of <i>Micvotus cabrera</i><i>e</i>

Continuous variation in Y-chromosome structure of Rumex acetosa

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