Biology Reference
In-Depth Information
translocation in the gorilla lineage which is not present in the chimpanzee. Thus,
chromosomes 4 and 19 of the gorilla were derived from a reciprocal translocation
between the ancestral chromosomes homologous to human chromosomes 5 and
17 (
Figure 2.6
). Wienberg
et al
. (1990) used chromosomal
in situ
suppression
hybridization to demonstrate that the centromere of human chromosome 17, the
long arm of the chromosome and a small part of the short arm all contribute to
gorilla chromosome 4 whilst most of the short arm of chromosome 17 contributes
to gorilla chromosome 19.
Probably the best understood human chromosome in terms of its evolution is
chromosome 21 (Richard and Dutrillaux, 1998;
Figure 2.7
). The equivalent of
human chromosome 21 (HSA21) formed a large and unique chromosome
together with chromosome 3 (HSA3) in the eutherian ancestor. This chromosome
was conserved without significant alterations only in lemurs, the civet and the
pig. It underwent inversions in the tree shrew and the cow. Various translocations
involving the portion corresponding to HSA3 occurred in the brown lemur, cat,
rabbit and mouse. In the primates, two independent fissions occurred. In New
World monkeys, a small segment of HSA3 remained attached to HSA21 and this
chromosome then underwent further rearrangements: an inversion in the mar-
moset, the addition of heterochromatin in the capuchin monkey and a transloca-
tion in the saki monkey. HSA21 was formed in the common ancestor of Old
World monkeys and underwent translocations with various equivalents of human
chromosomes in all the Cercopithecidae. HSA21 was conserved without visible
alteration in the black gibbon and the great apes.
One technique which is proving extremely useful in primate cytological studies
is cross-species chromosome painting (CSCP; also known as comparative paint-
ing or ZOO-FISH). CSCP involves the hybridization of a chromosome-specific
paint from one species (usually human) onto metaphase spreads of another
3
32
3
2
1
3
2
1
3
1
2
1
1
.
1
5
4
3
2
1
1
2
3
1
5
2
1
1
12
1
2
1
3
2
1
2
1
2
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1
2
3
1
2
3
1
2
3
5
1
4
5
1
17
3
1
3
2
1
Figure 2.6.
Idiograms of (from
left to right) human
chromosome 5, gorilla
chromosome 19, human
chromosome 17, and gorilla
chromosome 4 (redrawn from
Stanyon
et al.,
1992). The
gorilla chromosomes are
numbered to show their origin
by comparison with the human
chromosomes.
1
2
1
1
2
2
2
1
2
1
2
3
4
4
1
3
2
3
32
33
1
2
3
17
1
2
3
4
5
3
1
2
3
5
17
