Rediscovery After Thirty Years Since the Last Capture of the Critically Endangered Okinawa Spiny Rat<i>Tokudaia muenninki</i>in the Northern Part of Okinawa Island

Yamada, Fumio; Kawauchi, Norihiro; Nakata, Katsushi; Abe, Shintaro; Kotaka, Nobuhiko; Takashima, Atsushi; Murata, Chie; Kuroiwa, Asato

doi:10.3106/041.035.0404

Cited by 17 publications

(11 citation statements)

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“…In the forests, evergreen oak (Castanopsis sieboldii) dominates the tree community (Ito, 1997), and endangered native species with ancient lineages, including mammals such as the Okinawan spiny rat (Tokudaia muenninki) and the Ryukyu long-haired rat (Diplothrix legata), can be found (Suzuki et al, 2000;Endo and Tsuchiya, 2006;Suzuki, 2009;Murata et al, 2011). The ecology of the Yambaru forest is threatened by intensive colonization by an introduced animal, the small Indian mongoose (Herpestes auropunctatus), which preys on various native mammals, ground-nesting birds, amphibians, and reptiles (Yamada, 2002;Yamada and Sugimura, 2004;Yamada et al, 2010).…”

Section: Study Area and Samplesmentioning

confidence: 99%

Genetic characterization of Okinawan black rats showing coat color polymorphisms of white spotting and melanism

et al. 2012

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We examined pelage color variation in wild populations of black rats (the Rattus rattus species complex) in the Yambaru forest area, northern Okinawa Island, Ryukyu Archipelago, Japan. Our field study revealed that 8.7% (38/438) and 0.2% (4/2500) of rats exhibited two types of coat color: white spotting and melanism, respectively. Using 34 representative animals, the phylogeography of the population was inferred using a nuclear gene marker, i.e., sequences (954 bp) of the melanocortin-1 receptor (Mc1r) gene responsible for the melanistic form in black rats. Four sequences from Okinawa were characterized as R. tanezumi, the Asian strain of black rat. Notably, neither of the phenotypic characters of white spotting or melanism was associated with the Mc1r haplotypes. Analysis of mitochondrial cytochrome b (Cytb) sequences (1140 bp) revealed that four haplotypes recovered from Okinawa clustered with the clade of R. tanezumi and differed by one or more bases from haplotypes at other localities in Japan and Asian countries. Thus, both variants may have arisen in the native rat population of Okinawa without interaction with the lineage of R. rattus, which exhibits a worldwide distribution and displays such coat color variants. The Yambaru population of black rats has thus experienced its own evolutionary history in allopatry for a substantial period of time (e.g., 10,000 years), which has preserved valuable genetic polymorphisms and will be useful for assessing the ecological consequences of genetic variation in natural populations.

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Section: Study Area and Samplesmentioning

confidence: 99%

Genetic characterization of Okinawan black rats showing coat color polymorphisms of white spotting and melanism

et al. 2012

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“…20 With permission from the Agency for Cultural Affairs and the Ministry of the Environment in Japan, all animals were released at their capture sites after a small piece was cut from the tip of their tail. muenninki is endangered, is included on the IUCN Red List of Threatened Species (http://www.iucnredlist.org/ details/21972/0, accessed 10/10/2018), and has been protected by the Japanese government as a natural monument since 1972.…”

Section: Animals and Ethics Statementmentioning

confidence: 99%

“…muenninki is endangered, is included on the IUCN Red List of Threatened Species (http://www.iucnredlist.org/ details/21972/0, accessed 10/10/2018), and has been protected by the Japanese government as a natural monument since 1972. 20 With permission from the Agency for Cultural Affairs and the Ministry of the Environment in Japan, all animals were released at their capture sites after a small piece was cut from the tip of their tail. DNA was extracted from the tail tissues as reported previously.…”

Section: Animals and Ethics Statementmentioning

confidence: 99%

“…[11][12][13] Although several Y-linked genes have been rescued by translocation or transposition to the X chromosome and/or autosomes, 14 Sry has been completely lost from the genome of these species. 20 Furthermore, experimental samples of embryonic gonads from T. muenninki are not currently available. 15 Cross-species fluorescence in situ hybridization (Zoo-FISH) analysis revealed that a pair of autosomes has fused with the sex chromosomes of T. muenninki to form neo-X and neo-Y, which are homologous to the long arms of chromosome 3 of T. osimensis and chromosome 10 of T. tokunoshimensi.…”

Section: Introductionmentioning

confidence: 99%

“…15 We were unable to determine the expression of Sry in the embryonic gonads of T. muenninki because all species of Tokudai are endangered and protected by the Japanese government. 20 Furthermore, experimental samples of embryonic gonads from T. muenninki are not currently available. Therefore, in our previous study, we performed an in vitro reporter gene assay using a copy of T. muenninki SRY (SRY2, AB548700) that showed the highest identity with the mouse sequence.…”

Section: Introductionmentioning

confidence: 99%

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Spiny rat SRY lacks a long Q‐rich domain and is not stable in transgenic mice

Ogata

Nishikata

Kitada

et al. 2019

Developmental Dynamics

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Background: Although Tokudaia muenninki has multiple extra copies of the Sry gene on the Y chromosome, loss of function of these sequences is indicated. To examine the Sry gene function for sex determining in T. muenninki, we screened a BAC library and identified a clone (SRY26) containing complete SRY coding and promoter sequences. Results: SRY26 showed high identity to mouse and rat SRY. In an in vitro reporter gene assay, SRY26 was unable to activate testis-specific enhancer of Sox9. Four lines of BAC transgenic mice carrying SRY26 were generated. Although the embryonic gonads of XX transgenic mice displayed sufficient expression levels of SRY26 mRNA, these mice exhibited normal female phenotypes in the external and internal genitalia, and up-regulation of Sox9 was not observed. Expression of the SRY26 protein was confirmed in primate-derived COS7 cells transfected with a SRY26 expression vector. However, the SRY26 protein was not expressed in the gonads of BAC transgenic mice. Conclusions: Overall, these results support a previous study demonstrated a long Q-rich domain plays essential roles in protein stabilization in mice. Therefore, the original aim of this study, to examine the function of the Sry gene of this species, was not achieved by creating TG mice. K E Y W O R D SBAC, neo-Y, transgenic mouse, Y chromosome

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The Y chromosome of the Okinawa spiny rat, Tokudaia muenninki, was rescued through fusion with an autosome

Murata

Yamada

Kawauchi³

et al. 2011

Chromosome Res

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The genus Tokudaia comprises three species, two of which have lost their Y chromosome and have an XO/XO sex chromosome constitution. Although Tokudaia muenninki (Okinawa spiny rat) retains the Y chromosome, both sex chromosomes are unusually large. We conducted a molecular cytogenetic analysis to characterize the sex chromosomes of T. muenninki. Using crossspecies fluorescence in situ hybridization (Zoo-FISH), we found that both short arms of the T. muenninki sex chromosomes were painted by probes from mouse chromosomes 11 and 16. Comparative genomic hybridization analysis was unable to detect sex-specific regions in the sex chromosomes because both sex probes highlighted the large heterochromatic blocks on the Y chromosome as well as five autosomal pairs. We then performed comparative FISH mapping using 29 mouse complementary DNA (cDNA) clones of the 22 X-linked genes and the seven genes linked to mouse chromosome 11 (whose homologue had fused to the sex chromosomes), and FISH mapping using two T. muenninki cDNA clones of the Y-linked genes. This analysis revealed that the ancestral gene order on the long arm of the X chromosome and the centromeric region of the short arm of the Y chromosome were conserved. Whereas six of the mouse chromosome 11 genes were also mapped to Xp and Yp, in addition, one gene, CBX2, was also mapped to Xp, Yp, and chromosome 14 in T. muenninki. CBX2 is the candidate gene for the novel sex determination system in the two other species of Tokudaia, which lack a Y chromosome and SRY gene. Overall, these results indicated that the Y chromosome of T. muenninki avoided a loss event, which occurred in an ancestral lineage of T. osimensis and T. tokunoshimensis, through fusion with an autosome. Despite retaining the Y chromosome, sex determination Chromosome Res (2012) 20:111-125

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Rediscovery After Thirty Years Since the Last Capture of the Critically Endangered Okinawa Spiny RatTokudaia muenninkiin the Northern Part of Okinawa Island

Cited by 17 publications

References 17 publications

Genetic characterization of Okinawan black rats showing coat color polymorphisms of white spotting and melanism

Genetic characterization of Okinawan black rats showing coat color polymorphisms of white spotting and melanism

Spiny rat SRY lacks a long Q‐rich domain and is not stable in transgenic mice

The Y chromosome of the Okinawa spiny rat, Tokudaia muenninki, was rescued through fusion with an autosome

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