Biomedical Engineering Reference
In-Depth Information
M. leonina, the northern pigtail macaque, than to pigtail
macaques from Borneo. Care should be taken to identify
the countries of origin of pigtail macaques used as animal
models, because they are likely to exhibit levels of
phenotypic differences, including clinical responses to
experimental study at least as great, and probably greater,
than regional populations of rhesus and longtail macaques.
Moreover, further genetic studies of populations of
southern pigtail macaques from known geographical
regions of origin is needed to assess genetic subdivision of
captive members of this species employed in biomedical
research. Malhi et al. (2011) reported that an unexpectedly
high number of rhesus macaque SNPs were shared with
pigtail macaques relative to more closely related species.
As ascertainment bias is undoubtedly at least partially
responsible for this unexpected result, reduced reference
libraries (RRLs) are presently being sequenced to identify
informative pigtail macaque-specific SNPs.
Even less is known about genetic characteristics of
bonnet macaque (M. radiata) and Taiwanese macaque
(M. cyclopis) populations. Socha et al. (1976) reported
ABO blood group phenotypes of a group of bonnet
macaques formerly housed at the California National
Primate Research Center. The A and B alleles, based on
both reverse typing of sera and the saliva inhibition test,
exhibited nearly equal frequencies. Also found were
phenotypes A, B, and AB that conform to equilibrium
conditions and no animals with blood group O. An
unpublished PhD dissertation ( David Randal Risser, 1977 )
reported levels of electrophoretically defined poly-
morphisms for the same group that revealed a relatively low
level of genetic diversity. In addition, Nozawa et al. (1977) ,
who studied the electrophoretically defined genotypes of
seven bonnet macaques, reported a level of gene diversity
that is slightly lower than that they observed in a much
larger number of Indian rhesus macaques, a result consis-
tent with the report by Risser (1977) .
The ABO phenotypes have not been reported in
Taiwanese macaques. A study of a 600 bp sequence of the
control region of mtDNA of 96 Taiwanese macaques from
central Taiwan ( Chu et al., 2005 ) revealed only a single
haplotype, suggesting marked genetic homogeneity that is
presumed to have resulted from habitat destruction leading
to a genetic bottleneck. However, 14 haplotypes were found
in 80 animals from the southwestern region of Taiwan,
suggesting a genetic subdivision probably caused by
interaction with humans. In another study, the DNA of 12
captive Taiwanese macaques was amplified using human
primers for STR loci previously found to be polymorphic
in several other species of cercopithecine primates ( Chu
et al., 1999 ). Twenty-five of the STRs were successfully
amplified but four were monomorphic. The remainder
exhibited between two and 10 alleles and average values of
gene diversity ranging from 0.08 to 1.00. Nine of the
21 polymorphic STRs exhibited more than six alleles with
values of gene diversity ranging from 0.50 to 0.92. These
estimates of diversity may have been underestimates of
their actual values due to ascertainment bias in selecting
loci for analysis known to polymorphic in other species.
In a recent unpublished study of 25 Taiwanese
macaques sampled throughout Taiwan (Smith and Pei,
unpublished study), nearly 5000 SNPs were identified by
highly parallel sequencing on the Illumina HiSeq instru-
ment. Their average minor allele frequencies were
approximately 0.35, more than thrice the value for the same
SNPs in Sumatran longtail macaques, and the distribution
of MAF exhibited the near absence of low frequency SNPs
that predominate in longtail and rhesus macaques. This
strongly suggests that Taiwanese macaques recently expe-
rienced a severe genetic bottleneck that eliminated most
low frequency SNPs and would, therefore, be an optimal
model organism for mapping phenotypes to their genome
using many fewer SNPs than required for association
studies in other nonhuman primate species.
Japanese macaques have been the subjects of extensive
genetic study. The species, which probably evolved from
and/or experienced introgressive hybridization with the
eastern (i.e. Chinese) variety of rhesus macaque and
represents one of the most recent of the approximately 20
Asian species of macaques to emerge, exhibited the lowest
level of genetic heterogeneity in the study of Nozawa et al.
(1977) using protein coding loci. Early studies indicated
that the B allele of the ABO blood group system is fixed in
this species ( Blancher and Socha, 1997 ). Both protein
coding loci ( Nozawa et al., 1991 ) and mitochondrial DNA
haplotypes ( Marmi et al., 2004 ) clearly distinguish the two
subspecies of Japanese macaques, M.f. fuscata and
M. f. yakui, from each other. Nucleotide diversity of
mtDNA is higher in western than in eastern Japanese
macaques, and is especially low in M. f. yakui ( Hayaishi
and Kawamoto, 2006 ). Fu's measure of selective neutrality,
F S , provides evidence of rapid population expansion in
eastern, but not western, Japan ( Kawamoto et al., 2007 ).
Thus, Japanese macaques probably originated in Korea or
southern Honshu, near where the land bridge periodically
connected Japan to Korea, where fossil macaques have
been found ( Delson, 1980 ). They then spread northeast-
ward, eventually experiencing a population expansion in
the northeast during the late Pleistocene or Holocene times.
Japanese macaques more closely resemble rhesus
macaques than longtail or Taiwanese macaques ( Hayasaka
et al., 1988 ). That this similarily to rhesus macaques holds
only for Chinese, not Indian, rhesus macaques suggests that
Japanese macaques either evolved from Chinese rhesus
macaques ( Melnick et al., 1993 ) after Indian and Chinese
rhesus macaques diverged from each other, or, alternatively,
experienced significant introgression from Chinese rhesus
macaques since colonizing Japan. As the earliest fossil
Search WWH ::




Custom Search