Long‐term changes in recruitment of age‐0 Pacific bluefin tuna (Thunnus orientalis) and environmental conditions around Japan

Recruitment of age‐0 Pacific bluefin tuna (Thunnus orientalis) from 1952 to 2014 was examined by a sequential regime shift detection method. The regime shifts in recruitment were detected in 1957, 1972, 1980, 1994 and 2009. The durations of regime shift ranged from 8–15 years and averaged 13.0 years. In both the total (1952–2014) and data rich (1980–2014) periods, negative relationships were found between recruitment and the Pacific Decadal Oscillation in autumn, and positive relationships were found between recruitment and sea surface temperature (SST) anomalies in the northern part of the East China Sea, in the southwestern part of the Sea of Japan, and in the waters off Shikoku and Tokai in summer and autumn. The 1994 and 2009 regime shifts in recruitment occurred in the same years as shifts in SST anomalies in the northern part of the East China Sea in summer. These results suggest that the ocean conditions in the northern part of the East China Sea are closely related to recruitment of Pacific bluefin tuna, and that the warmer conditions result in higher recruitment of the species.     

First report of ‘<Emphasis Type="Italic">Candidatus</Emphasis> Phytoplasma malaysianum’ associated with <Emphasis Type="Italic">Elaeocarpus</Emphasis> yellows of <Emphasis Type="Italic">Elaeocarpus zollingeri</Emphasis>

“Elaeocarpus yellows” (ELY) is a widely reported phytoplasma disease of Elaeocarpus zollingeri trees in Japan. The phytoplasma associated with ELY (ELY phytoplasma) had not been identified at the species level because its 16S rRNA sequence had yet to be reported. Here, we report the results of a sequence analysis based on 16S rRNA and secA gene sequences, which showed that the ELY phytoplasma is related to ‘Candidatus Phytoplasma malaysianum’. To our knowledge, this is the first report showing the occurrence of ‘Ca. P. malaysianum’ outside Malaysia and the infection of E. zollingeri by the phytoplasma.     

Establishment of a new cell line susceptible to Cyprinid herpesvirus 3 (CyHV‐3) and possible latency of CyHV‐3 by temperature shift in the cells

A new cell line named CCF‐K104 predominantly consisting of fibroblastic cells showed optimal growth at temperatures from 25 °C to 30 °C. Serial morphological changes in the cells induced by Cyprinid herpesvirus 3 (CyHV‐3) included cytoplasmic vacuolar formation, cell rounding and detachment. Mature virions were purified from CyHV‐3‐infected CCF‐K104 cells by sucrose gradient ultracentrifugation and had a typical herpesvirus structure on electron microscopy. Infectious CyHV‐3 was produced stably in CCF‐K104 cells over 30 viral passages. Our findings showed that CCF‐K104 is a useful cell line for isolation and productive replication of CyHV‐3. A temperature shift from 25 °C to 15 °C or 35 °C did not allow serial morphological changes as observed at 25 °C for 14 days. Under the same conditions, real‐time PCR showed that CyHV‐3 was present with low viral DNA loads, suggesting that CyHV‐3 may establish latent infection in CCF‐K104 cells. Amplification of the left and right terminal repeat sequences of the CyHV‐3 genome arranged in a head‐to‐tail manner was detected by nested PCR following an upshift in temperature from 25 °C to 35 °C. The PCR results suggested that the circular genome may represent a latent form of CyHV‐3.     

First application of PCR-Luminex system for molecular diagnosis of fungicide resistance and species identification of fungal pathogens

Fungicide resistance in plant pathogens is often caused by a single point mutation in a gene encoding fungicide target proteins. Such is the case for resistance to MBI-D (inhibitors of scytalone dehydratase in melanin biosynthesis) fungicides in rice blast fungus (Magnaporthe oryzae), which is caused by a mutation in the scytalone dehydratase gene that results in a replacement of valine with methionine at codon 75 of the fungicide target protein. PCR-Luminex, a novel system developed for high-throughput analysis of single nucleotide polymorphisms (SNPs) was successfully introduced to diagnose MBI-D resistance using specific oligonucleotide probes coupled with fluorescent beads. The PCR-Luminex system was further tested for its potential in identifying species causing Fusarium head blight on wheat. Four major pathogens, Fusarium graminearum (=F. asiaticum), F. culmorum, F. avenaceum, and Microdochium nivale, known to cause the disease, were tested, and the species were identified using the PCR-Luminex method. So far, this report is the first on the application of the DNA-based PCR-Luminex system in the area of crop protection and/or agricultural sciences.     

Time-course comparison of pulmonary inflammation induced by intratracheal instillation of four different nickel oxide nanoparticles in male Fischer rats

Occupational exposure to nickel oxide (NiO) is an important cause of respiratory tract cancer. Toxicity is known to be associated with the dissociated component, i.e. nickel (II) ions. To address the relationship between physicochemical properties, including solubility in artificial lysosomal fluid, of NiO and time-course changes in the pulmonary response, we conducted an intratracheal instillation study in male Fischer rats using four different well-characterized NiO products, US3352 (NiO A), NovaWireNi01 (NiO B), I small particle (NiO C), and 637130 (NiO D). The NiOs were suspended in purified water and instilled once intratracheally into male F344 rats (12 weeks old) at 0 (vehicle control), 0.67, 2, and 6 mg/kg body weight. The animals were euthanized on days 3, 28, or 91 after instillation, and blood analysis, bronchoalveolar lavage fluid (BALF) testing, and histopathological examination were performed. The most soluble product, NiO B, caused the most severe systemic toxicity, leading to a high mortality rate, but the response was transient and surviving animals recovered. The second-most-soluble material, NiO D, and the third, NiO A, caused evident pulmonary inflammation, and the responses persisted for at least 91 days with collagen proliferation. In contrast, NiO C induced barely detectable inflammation in the BALF examination, and no marked changes were noted on histopathology. These results indicate that the early phase toxic potential of NiO products, but not the persistence of pulmonary inflammation, is associated with their solubility.     

Concentration of macrophage colony-stimulating factor (M-CSF) in bovine peripheral blood during pregnancy

Macrophage colony-stimulating factor (M-CSF) is a hemopoietic cytokine with a primary role in placental physiology. Gene expression of M-CSF in the bovine endometrium shows a temporal upward trend during early and mid pregnancy. This study determined the plasma M-CSF levels during pregnancy using ELISA. In experiment 1, to investigate the relationship between the concentration of M-CSF in peripheral blood and pregnancy, the plasma M-CSF levels were determined in 125 pregnant and 21 non-pregnant Japanese Black cows. The pregnant animals were divided into nine groups based on the month of pregnancy. An ELISA for bovine M-CSF established previously was used according to the authors' instructions. In experiment 2, the plasma M-CSF level was determined to investigate the temporal changes in its concentration in the peripheral blood during pregnancy. In experiment 1, the plasma M-CSF level varied from month to month during pregnancy; the mean level in the first-month of pregnancy was significantly higher than those in the third and last months of pregnancy and non-pregnancy (P<0.05). In experiment 2, the plasma M-CSF level varied with the day of pregnancy (P<0.05). The mean level of plasma M-CSF decreased gradually until 6 weeks of pregnancy; it appeared to increase during weeks 7-9, then varied with several small peaks until 27 weeks of pregnancy and finally decreased gradually until parturition. These results suggest that the plasma M-CSF level may be related to changes in the uterus and placenta as pregnancy progresses.