Seasonal diet partition among top predators of a small island, Iriomote Island in the Ryukyu Archipelago, Japan.

Small islands tend to lack predators because species at higher trophic levels often cannot survive. However, two exceptional top predators-the Iriomote cat Prionailurus bengalensis iriomotensis, and the Crested Serpent Eagle Spilornis cheela perplexus-live on the small Iriomote Island in the Ryukyu Archipelago. To understand how these predators coexist with limited resources, we focused on their seasonal diets between which conflicts are considered to occur. To compare the diets, we used DNA metabarcoding analysis of faecal samples. In the summer, we identified 16 unique prey items from Iriomote cat faecal samples and 15 unique prey items from Crested Serpent Eagle faecal samples. In the winter, we identified 37 and 14, respectively. Using a non-metric multidimensional scaling and a permutational multivariate analysis of variance, our study reveals significant differences in the diet composition at the order level between the predators during both seasons. Furthermore, although some prey items at the species-to-order level overlapped between them, the frequency of occurrence of most prey items differed in both seasons. These results suggest that this difference in diets is one of the reasons why the Iriomote cat and the Crested Serpent Eagle are able to coexist on such a small island.

Effects of DNA lesions on the transcription reaction of mitochondrial RNA polymerase: implications for bypass RNA synthesis on oxidative DNA lesions.

Oxidative DNA lesions inhibit the transcription of RNA polymerase II, but in the presence of transcription elongation factors, the transcription can bypass the lesions. Single-subunit mitochondrial RNA polymerase (mtRNAP) catalyses the synthesis of essential transcripts in mitochondria where reactive oxidative species (ROS) are generated as by-products. The occurrence of RNA synthesis by mtRNAP at oxidative DNA lesions remains unknown. Purified mtRNAP and a complex of RNA primer/DNA template containing a single DNA lesion, such as ROS-induced 8-oxoguanine (8-oxoG), two isomeric thymine glycols (5R-Tg or 5S-Tg), the UV-induced cis-syn cyclobutane pyrimidine dimer (CPD) and the pyrimidine(6-4)pyrimidone photoproduct (6-4pp), or a spontaneous common DNA lesion, a base-loss-induced apurinic/apyrimidinic (AP) site, were used for in vitro RNA synthesis assays. In this report, we show that mtRNAP bypassed the oxidative DNA lesions of non-bulky 8-oxoG and 5R-Tg and 5S-Tg with pausing sites but did not bypass the UV-induced DNA lesions and the AP site. The bacteriophage T7 phage RNA polymerase, which is homologous to mtRNAP, bypassed 8-oxoG but stalled at 5R-Tg and 5S-Tg. As expected, although translesion RNA synthesis in 8-oxoG on the DNA templates generated incorrect transcripts with a G:C to T:A transversion, the synthesis in Tg could lead to the correct transcripts with no transcriptional mutagenesis. Collectively, these data suggest that mtRNAP may tolerate the mitochondrial genome containing oxidative DNA lesions induced by ROS from the side effects of an ATP generation reaction.

Molecular survey of arthropod-borne pathogens in ticks obtained from Japanese wildcats.

The Iriomote cat (IC), Prionailurus bengalensis iriomotensis, and the Tsushima leopard cat (TLC), Prionailurus bengalensis euptilurus, are endangered subspecies of leopard cats in Japan. In addition to habitat destruction and road kills, infectious diseases may threaten their populations, and infection with arthropod-borne pathogens has been reported in both subspecies. Infestations with ectoparasites, especially ticks, have frequently been observed in ICs and TLCs. In the present study, ticks collected from captured ICs and TLCs between November 2011 and January 2012 were morphologically identified and the prevalence of the pathogens Bartonella sp., Babesia sp., Ehrlichia sp., Anaplasma sp., Hepatozoon sp., and hemoplasmas in the ticks was molecularly evaluated. The ticks Haemaphysalis longicornis, H. hystricis, and Amblyomma testudinarium were obtained from ICs, and H. megaspinosa, Ixodes tanuki, H. campanulata, and A. testudinarium were collected from TLCs. The pathogens Hepatozoon felis, Babesia sp., and Anaplasma bovis were detected in ticks obtained from ICs, while H. felis. Babesia sp., Ehrlichia sp., E. muris, 'Candidatus Mycoplasma haemominutum', and Bartonella henselae were found in ticks from TLCs. To protect and conserve these endangered animals, continuous monitoring and additional surveys will be necessary to understand the role of ticks as disease vectors in Japanese wildcats.

Human endonuclease V is a ribonuclease specific for inosine-containing RNA.

Deamination of DNA bases can create missense mutations predisposing humans to cancer and also interfere with other basic molecular genetic processes; this deamination generates deoxyinosine from deoxyadenosine. In Escherichia coli, the highly conserved endonuclease V is involved in alternative excision repair that removes deoxyinosine from DNA. However, its exact activities and roles in humans are unknown. Here we characterize the FLJ35220 protein, the human homologue of E. coli endonuclease V, hEndoV as a ribonuclease specific for inosine-containing RNA. hEndoV preferentially binds to RNA and efficiently hydrolyses the second phosphodiester bond located 3' to the inosine in unpaired inosine-containing ssRNA regions in dsRNA. It localizes to the cytoplasm in cells. The ribonuclease activity is promoted by Tudor staphylococcal nuclease and detected on inosine-containing dsRNA created by the action of adenosine deaminases acting on RNA. These results demonstrate that hEndoV controls the fate of inosine-containing RNA in humans.

Epidemiological survey of tick-borne protozoal infection in iriomote cats and tsushima leopard cats in Japan.

This epidemiological survey was conducted to determine the prevalence of Hepatozoon, Babesia and Theileria infection in the Iriomote cat (IC) and the Tsushima leopard cat (TLC). Blood samples from 43 ICs and 14 TLCs were collected between November 2002 and January 2012. Polymerase chain reaction and DNA sequencing analyses detected a Hepatozoon felis infection prevalence of 72.0% (31/43 cats) and 100% (14/14 cats) in ICs and TLCs, respectively. The degree of Hepatozoon parasitemia observed on blood smears ranged from 0.1 to 4.7%. However, no cases had obvious clinical signs of hepatozoonosis. Neither Babesia- nor Theileria-infected wildcats were detected in this study.

Molecular epidemiologic survey of Bartonella, Ehrlichia, and Anaplasma infections in Japanese Iriomote and Tsushima leopard cats.

The Iriomote cat (IC; Prionailurus iriomotensis) and the Tsushima leopard cat (TLC; Prionailurus bengalensis euptilura) are endangered wild felids in Japan. As a part of ongoing conservation activities, we conducted a molecular, epidemiologic survey of Bartonella, Ehrlichia, and Anaplasma infections in wild IC and TLC populations. Blood samples (47 from 33 individual IC; 22 from 13 TLC) were collected between August 2002 and January 2011. Using PCR analysis, we confirmed the presence of Bartonella henselae in ICs and Bartonella clarridgeiae in TLCs, with prevalences of 6% and 8%, respectively. Using PCR and basic local alignment search tool analyses, we identified Ehrlichia canis in both cats and Anaplasma bovis in TLCs. The prevalence of E. canis was 12% in ICs and 8% in TLCs, and the prevalence of A. bovis was 15% in TLCs. This is the first report, to our knowledge, of B. henselae, B. clarridgeiae, E. canis, and A. bovis infections in these two endangered species. Continuous monitoring of these pathogens is needed for their conservation.

An epidemiological survey of hemoplasma infection in Iriomote cats (Prionailurus bengalensis iriomotensis).

An epidemiological survey of Iriomote cats (Prionailurus bengalensis iriomotensis) was conducted to understand the prevalence and molecular characteristics of hemotropic mycoplasma (hemoplasma). A series of ecological surveys of Iriomote cats were performed between November 2003 and September 2010. During this period, 31 Iriomote cats were captured or found, and 39 blood samples were collected. Polymerase chain reaction screening for hemoplasmas and BLAST searches revealed that 4 of the 31 cats were positive for hemoplasma infection (n=3, Mycoplasma haemofelis [Mhf]; n=1, 'Candidatus M. turicensis' [CMt]). The 4 infected cats were captured or found in the northern area of the island of Iriomote. Phylogenetic analyses revealed close relationships between Mhf and CMt isolated from Iriomote cats compared with those from domestic cats and other wild felids. In our study, we identified two species of hemoplasma in Iriomote cats. The number and location of the hemoplasma-positive cats appeared to be limited; however, continuous surveillance of hemoplasma infection in Iriomote cats is necessary.

A case of Iriomote cat (Prionailurus bengalensis iriomotensis) with Hepatozoon felis parasitemia.

We herein present clinical findings of an Iriomote cat with Hepatozoon felis parasitemia. A male Iriomote cat was captured for ecological analyses three times from January 2010 to January 2011. Although this cat did not show any hematological abnormalities at the time of the first capture, H. felis parasitemia and increased serum creatine kinase levels were detected at the second and third captures. H. felis infection was confirmed by polymerase chain reaction, and amplified 18S ribosomal RNA gene fragments were 100% identical to those of H. felis in leopard cats in Korea. Although the virulence of H. felis in this cat was suggested to be low, this is the first report of an H. felis-infected Iriomote cat with parasitemia.