Chromosomal localization of four HSA2 type I loci in river buffalo
(Bubalus bubalis, 2n = 50) Chromosomes 2q and 12
G.P. Di Meo,
* N. Lopez-Corrales,
National Research Council, IABBAM, Via Argine, 1085, 80147 Naples, Italy
Molecular Biology Department, Roslin Institute, Roslin, Midlothian, Scotland, UK
Received: 16 July 1999 / Accepted: 21 October 1999
Although the river buffalo is one of the most important domestic
bovids (more than 130 million animals raised in all the world), few
loci have been mapped in this species by both ISH and somatic
hybrid cell techniques (reviewed in Iannuzzi 1998). The five two-
armed river buffalo chromosome (BBU) pairs are the result of five
centric fusion events that involved 10 homologous cattle chromo-
somes (CSKBB 1994). In particular, BBU2 was originated by rob
(2;23), and the acrocentric BBU12 is homologous to BTA11. Only
two loci have been FISH-mapped to these two chromosomes: VIL1
(bovine U17/BTA2) to BBU2q33 (Iannuzzi 1998), and GGTA1
(bovine U16/BTA11) to BBU12q36 (Iannuzzi 1998).
In the present study, four type I loci (PRO C, COL3A1, ALPI,
and IL1B) mapping to HSA2q (Fisher et al. 1997; Smith et al.
1997; Sonstegard et al. 1997), and previously FISH-mapped to
both cattle and sheep (Sonstegard et al. 1997; Lopez-Corrales et al.
1998) were FISH-mapped to BBU2q and BBU12, extending the
physical map for these two chromosomes. Our data are also dis-
cussed in light of HSA1 and HSA2 painting probe results.
Results and Discussion
Simultaneous visualizations of RBA-banding and FITC-signals
with the four BAC-clones to river buffalo metaphase preparations
are shown in Fig. 1 a–d. The frequency of signals was very high
(from 60% to 95%), so only 15 metaphases for each probe were
studied. The following localizations were observed: PRO C and
COL3A1 to BBU2q12, ALPI to BBU2q35, and IL1B to
BBU12q25>q26, as indicated in their R-banded ideograms. In Fig.
1, also the ideograms of the homologous cattle chromosomes
BTA2 and BTA11, as well as that of HSA2q with the four FISH-
mapped loci, were reported.
These four loci were assigned to homologous chromosomes
and chromosome bands as previously reported (Sonstegard et al.
1997; Lopez-Corrales et al. 1998; Fig. 1e). Only for ALPI were the
signals clearly located at the telomeric R-band positive BBU2q35
(homologous to both BTA2q45 and OAR2q35), instead of
BTA2q44, as reported by Sonstegard and coworkers (1997). A
FISH-mapping control confirmed the localization of ALPI on
BTA2q45. The localization of ALPI in BBU2q35 is in conflict
with human painting probe results obtained to both BTA2 and
BBU2q. Indeed, BTA2 and BBU2q are almost all painted by
HSA2-painting probe, while their telomeric regions are painted by
HSA1 (Hayes 1995; Iannuzzi et al. 1998b). However, in many
river buffalo metaphase preparations, HSA2 painting probe re-
vealed small FITC-signals in the telomeric region of BBU2q35
(not shown in this study). Thus, it is possible that part of HSA2q-
sequences have been conserved in this region, which is largely
painted by HSA1 (Iannuzzi et al. 1998a). Furthermore, no HSA2-
painting signals were found in the pericentromeric region of
BBU2q (Iannuzzi et al. 1998a), while both PROC and COL3A1
map to this region (BBU2q12).
It is well known that Zoo-FISH underestimates the number of
conserved regions between different genomes. Only detailed com-
parative FISH-mapping between human and bovid genomes can
* Technical assistance, image processing and digitized ideograms
Correspondence to: L. Iannuzzi, e-mail: firstname.lastname@example.org
Fig. 1. Details of river buffalo metaphases showing
simultaneous visualization of RBA-banding and
hybridization FITC-signals of BAC-clones mapping
COL3A1 and PRO C to BBU2q12 (a and b,
respectively), ALPI to BBU2q35 (c), and IL1B to
BBU12q25>q26 (d). Physical maps of BBU2q and
BBU12 (and homologous BTA2 and BTA11), as
well as that of HSA2q with the four mapped loci
are reported in their R- (BBU and BTA) and G-
(HSA) banded ideograms (e). Peripheral blood
lymphocyte cultures, slide treatments, in situ
hybridization, FITC-signal detection, RBA-banding,
and image analyses are as previously reported
(Iannuzzi et al. 1998a). As probes, the bovine BAC
clones BBI_B750K1819, BBI_B750B21299,
BBI_B750G01347, and BBI_B750P22108, which
map protein C (PRO C), collagen, type III, alpha 1
(COL3A1), intestine alkaline phosphatase (ALPI),
and interleukin 1, beta (IL1B), respectively
(Sonstegard et al. 1997; Lopez-Corrales et al.
1998), were used.
Mammalian Genome 11, 241–242 (2000).
© Springer-Verlag New York Inc. 2000