Comparison of the human with the sheep genomes by use of human
chromosome-specific painting probes
Leopoldo Iannuzzi, Giulia P. Di Meo, Angela Perucatti, Domenico Incarnato*
National Research Council, I.A.B.B.A.M., Via Argine 1085, 80147-Naples, Italy
Received: 13 October 1998 / Accepted: 18 February 1999
Abstract. Human chromosome specific painting probes were hy-
bridized on sheep (Ovis aries, 2n ס 54) chromosomes by FISH.
The painting results on sequentially stained RBA-banded prepa-
rations demonstrated high degree of conserved regions between
human and sheep genomes. A total of 48 human chromosome
segments were detected in sheep chromosomes. Comparisons with
sheep gene mapping data available and previous Zoo-FISH data
obtained in sheep, cattle, and river buffalo were performed.
The sheep (Ovis aries, 2n ס 54) is one of the most important
bovid species in economic terms. Standard karyotypes at the 250
(Reading Conference 1976), 300 (Long 1988), and 450 (ISCNDA89
1990) band level are available, although discrepancies in the num-
bering of some chromosomes were noticed (Ansari et al. 1993,
1994; Iannuzzi and Di Meo 1995; Iannuzzi et al. 1998), and G-
and R-banding chromosome comparisons between sheep and
cattle were performed (Hayes et al. 1991; Ansari et al. 1993;
Kaftanovskaya and Serov 1994; Iannuzzi and Di Meo 1995). More
recently, the Texas nomenclature (1996) assigned molecular mark-
ers (and corresponding human chromosomes) to each sheep and
cattle chromosome on the basis of available gene mapping data and
the standard karyotypes (Reading Conference 1980; ISDNDA89
1990). However, the 1314 loci currently mapped in sheep includes
only 334 designated genes (SheepBase, December 21, 1998).
Much genetic information can be transferred from well-
mapped genomes, like those of humans and mice, to sparsely
mapped ones like those of bovids. The use of a human chromo-
some-specific painting probe technique, called Zoo-FISH (Scher-
tan et al. 1994), allows regions to be identified in non-related
mammalian chromosomes that are conserved or not conserved.
This is an important step for genetic improvement, especially in
economically important species, allowing more careful genetic
analysis in particular animal chromosome regions where particular
genes, well known in the human genome, can be explored and used
for livestock production or for animal disease resistance.
Zoo-FISH by using human specific chromosome probes has
been applied in cattle (Hayes 1995; Solinas-Toldo et al. 1995;
Chowdhary et al. 1996), pig (Fronicke et al. 1996; Rettenberger et
al. 1995), horse (Raudsepp et al. 1996), cat (O’Brien et al. 1997)
and river buffalo (Iannuzzi et al. 1998), but it is still lacking in
other important domestic species such as sheep. However, in sheep
indirect comparison with human chromosomes was performed by
Burkin and associates (1997). These authors hybridized specific
sheep chromosome painting probes on Indian muntjac (Muntiacus
muntjak vaginalis, 2n ס 6,7) chromosomes and indicated the cor-
responding human chromosome paintings on the basis of a previ-
ous study that painted the Indian muntjac chromosomes with hu-
man probes (Yang et al. 1997).
In the present study, we extend our knowledge of differences
between human and sheep genomes by using direct human chro-
mosome (HSA)-specific painting probes on R-banded sheep chro-
mosomes (OAR), allowing a detailed description of painted re-
gions along the sheep ideogram.
Materials and methods
Commercially available human specific chromosome libraries (Painting kit
1089-KB, Cambio, England) were used for this study. Concavalin A
(Sigma)-stimulated blood lymphocyte cultures were treated for the late
incorporation of both BrdU (10 g/ml) and Hoechst 33258 (20 g/ml) to
obtain enhanced R-banding patterns after in situ hybridization. Slide treat-
ment, in situ hybridization, probe detection, RBH- and RBA-banding, as
well as metaphase image processing, were recently reported (Iannuzzi et al.
1998). At least 10 early-metaphases and prometaphases were studied for
each probe. Sheep chromosome identification followed the RBA-standard
karyotype (ISCNDA89 1990) and the Texas nomenclature (1996), while
the R-banded ideogram previously reported (Iannuzzi et al. 1995) was used
to show the human chromosome paintings and the sheep gene mapping
data (only gene loci mapped by ISH) by using the SheepBase. Comparisons
with previous Zoo-FISH data reported by Burkin and colleagues (1997)
were performed, while comparisons with previous Zoo-FISH made in
cattle (Hayes 1995; Solinas-Toldo et al. 1995; Chowdhary et al. 1996) and
river buffalo (Iannuzzi et al. 1998) were discussed on the basis of the cattle
and sheep standard nomenclatures (Reading Conference 1980; ISDNDA89
1990; Ansari et al. 1994; Texas nomenclature 1996).
Results and discussion
Figure 1 shows some representative partial sheep chromosome
preparations (both early- and prometaphases) sequentially treated
for FISH with human chromosome-specific painting probes and
RBA-banding. The resulting clear banding patterns allowed not
only easy identification of chromosomes, but also of chromosome
regions and bands painted by human probes. Furthermore, for all
the probes we used, paintings appeared much more intense in
positive R-bands than in positive G-bands (Fig. 1). The same was
found in river buffalo (Iannuzzi et al. 1998).
Figure 2 shows the sheep R-banded ideogram with the corre-
sponding painted regions after hybridization with human probes.
The lines indicate which human-specific probes paint sheep chro-
mosome regions. A total of 48 human segments were detected, of
which 42 were in agreement with the total number of segments
reported by Burkin and coworkers (1997). In this figure, we also
report the mapped gene loci in specific chromosome regions or
bands. Essentially, the painting results with HSA probes agree
with the gene mapping data (Fig. 2) and with previous Zoo-FISH
conducted in cattle (Hayes 1995; Solinas-Toldo et al. 1995;
Chowdhary et al. 1996) and in river buffalo (Iannuzzi et al. 1998),
Correspondence to: L. Iannuzzi; firstname.lastname@example.org
* Technical assistance, image processing, and computerized ideogram.
Mammalian Genome 10, 719–723 (1999).
© Springer-Verlag New York Inc. 1999