• Investigation of human chromosome polymorphisms by scanning electron microscopy.

      Harrison, Christine J; Jack, E; Allen, Terence D; Harris, R; The Department of Cell Biology and Cytogenetics, and the Department of Ultrastructure, Paterson Laboratories, Christie Hospital and Holt Radium Institute, Manchester M20 9BX (1985-02)
      Human chromosome polymorphisms were investigated by scanning electron microscopy (SEM). Centromeric heterochromatin was of a constricted morphology. The extent of the C banded region was demarcated by a prominent circumferential groove in G banded chromosomes. Circumferential grooves were observed within the heterochromatin of chromosome 9, and the number of grooves present reflected the size of the region. Three dimensional viewing of satellites and short arms of acrocentric chromosomes, from different angles in the SEM, provided the opportunity for accurate assessment of the size of satellites to be made. Also, small morphological variations were defined in the SEM when definition was uncertain in the light microscope (LM).
    • Investigation of three patients with the "ring syndrome", including familial transmission of ring 5, and estimation of reproductive risks.

      MacDermot, K D; Jack, E; Cooke, A; Turleau, C; Lindenbaum, R H; Pearson, J; Patel, C; Barnes, P M; Portch, J; Crawfurd, M D; et al. (1990-10)
      We report three cases of ring chromosome 5 [r(5)], two familial (mother and daughter) and one sporadic. The phenotype resembled that of the "ring syndrome" with prenatal onset of short stature, growth retardation, mild facial dysmorphism and normal psychomotor development. Extended metaphase and prometaphase chromosome preparations using G-, R- and Q-banding and scanning electron microscopy (SEM) failed to demonstrate deletion in the ring 5. Flow karyotype using the FACS cell sorter and peak area analysis showed the r(5) to be in the same position as the normal chromosome 5. The deletion that is presumably associated with ring formation appears to involve less that one megabase of DNA. In the "complex" rings, high resolution SEM showed fragile sites at the 5q34 and 5q35 region with frequent deletions at that site. A literature survey suggests that when a parent carries a ring chromosome about 80% of recognised pregnancies result in live birth. Of these, about half have a normal phenotype and karyotype, and half inherit the parental ring; about half of those acquiring the ring (20%) show significant mental retardation.
    • Light and scanning electron microscopy of the same human metaphase chromosomes.

      Harrison, Christine J; Jack, E; Allen, Terence D; Harris, R; Paterson Laboratories, Christie Hospital & Holt Radium Institute, Manchester, M20 9BX, UK. (1985-08)
      A technique has been developed to examine the same G-banded human metaphase chromosomes, first in the light microscope and then in the scanning electron microscope (SEM). A structural involvement in chromosome banding was confirmed by a positional correlation between the G-positive bands observed in the light microscope and the circumferential grooves between the quaternary coils of the metaphase chromosomes, observed in the SEM. In further support of this the regions between the grooves showed a positional relationship with the G-negative or reverse (R) bands. The examination of slightly extended metaphase chromosomes in the light microscope demonstrated that the G-banding pattern corresponded to that described by the Paris nomenclature for metaphase chromosomes. The arrangement of the circumferential grooves of the same chromosomes, observed in the SEM, was shown to relate to that described by the Paris nomenclature for prometaphase chromosomes. Therefore, using the SEM it is possible to demonstrate the details of prometaphase banding in metaphase chromosomes.