High impact information on In(X)1H

• About 12-17% of the embryos obtained by mating mice carrying the In(X)1H or Paf mutations are of the 39,X (X0) genotype [1].
• X-chromosome activity in early mouse development has been studied by a gene dosage method that involves measuring the activity level of the X-linked enzyme hypoxanthine phosphoribosyl transferase (HPRT) in single eggs and embryos from XO females and from females heterozygous for In(X)1H, a paracentric inversion of the X chromosome [2].
• Chromosome pairing has been examined in foetal oocytes of mice heterozygous either for an X-linked inversion, In(X)1H, or an autosomal inversion, In(2)2H [3].
• Firstly, in In(X)1H heterozygotes, the presence of an inversion loop and the occurrence of partial pairing of long/long-medium bivalents at pachytene were independent of each other only on day 19 [3].
• To examine the effects of X-chromosome imprinting during early mouse embryogenesis, we attempted to produce XM0, XP0, XMXMY, XMXPY and XMXMXP (where XM and XP stand for the maternally and the paternally derived X chromosome, respectively) making use of mouse strains bearing the translocation Rb(X.2)2Ad and the inversion In(X)1H [4].

Biological context of In(X)1H

• Nonhomologous synapsis of the XY during early pachynema in In(X)1H male mice [5].

Anatomical context of In(X)1H

• The synaptic behavior of an inverted X chromosome, In(X)1H as reflected in the synaptonemal complexes of the sex chromosomes has been examined in microspread spermatocytes by electron microscopy and evidence of extensive nonhomologous synapsis between the X and Y during early pachynema has been obtained [5].

References