Sex ratios of nigorobuna Carassius auratus grandoculis reared in paddy fields with fluctuating temperatures during larval and juvenile growth stages

The sex ratios of the nigorobuna Carassius auratus grandoculis reared in paddy fields during the sex differentiation periods of larval and juvenile stages were examined, since the phenotypic expression of sex in the fish is thermolabile, so that sex determination is under the control of genetic factors and temperature. After 2 days from hatching, the larvae were introduced into five paddy fields at five different densities in late May. After 37 or 41 days from hatching the juveniles were collected when the water was drained from the paddy fields, and reared in laboratory tanks supplied with running freshwater pumped from the lake shore until the age of 144–164 days. The mean water temperatures in the paddy fields were 22.4–24.1 ºC, and the maximum water temperature during the day frequently exceeded 30 ºC during the supposed critical period of sex determination of the fish. The sex ratios in the five paddy fields did not show a male-bias. Instead, all fields produced either balanced or slightly female-bias sex ratios. These results suggest that temporary high and fluctuating temperatures in paddy fields with low mean temperatures have hardly any masculinization effects on genotypic females of C. auratus grandoculis during sex differentiation stages.     

Safety of alternate-day treatment with TS-1TM (tegafur/gimeracil/oteracil) in tumor-bearing dogs: a pilot study

Tegafur is a prodrug of fluoropyrimidine 5-fluorouracil (5-FU), while TS-1^TM is an oral fixed-dose combination of three active drugs, tegafur, gimeracil, and oteracil. This pilot study evaluated the safety of tegafur/gimeracil/oteracil in the treatment of cancers in dogs. Tegafur/gimeracil/oteracil was administered orally at a mean dose of 1.1 mg/kg twice daily on alternate days, Monday-Wednesday-Friday, every week to 11 dogs with tumors. Partial response and stable disease were observed in one dog each, whereas six exhibited progressive disease. Three dogs were not assessed. Adverse events, the most serious being grade 2, were noted in seven dogs. Adverse events were acceptable, and the drug was effective in some dogs. Therefore, tegafur/gimeracil/oteracil may be useful for treating malignant solid tumors in canines.     

Biological control of bacterial spot on peach by nonpathogenic Xanthomonas campestris strains AZ98101 and AZ98106

A suspension of nonpathogenic Xanthomonas campestris (nXc) strain AZ98101 or AZ98106 was sprayed on peach trees in biological control tests against bacterial spot caused by Xanthomonas arboricola pv. pruni. Treatment with each strain reduced the number of leaves with spots. Meta-analysis of the results from seven field trials showed an integrated risk ratio (the ratio of leaf spot incidence on inoculated leaves to incidence on control leaves) of 0.46 by treatment with AZ98101 and 0.54 by AZ98106, indicating that leaf spot incidence was significantly reduced by each strain. Each also significantly reduced the incidence of fruit spot. The risk ratio with AZ98101 was significantly lower than that with AZ98106. The population of AZ98101R-1, a rifampicin-resistant mutant of AZ98101, was 6.3 × 10³ CFU/g (fresh mass) on leaves and 8.0 × 10³ CFU/g on fruit at 12 days after inoculation, but was undetectable (<10² CFU/g) by 24 days. This is the first report that nXc strains AZ98101 and AZ98106 effectively control bacterial spot on peach.     

Prevalence and risk factors associated with Cryptosporidium oocysts shedding in pigs in Central Vietnam

We investigated the prevalence and risk factors associated with Cryptosporidium oocysts shedding in pigs in Central Vietnam. A total of 740 single fecal samples collected from diarrheic and non-diarrheic pigs on 89 farms were screened by the modified Ziehl-Neelsen staining method. Prevalence at the animal and the farm levels were 18.1% (134/740) and 71.9% (64/89), respectively. Risk factors for the infection were identified using univariate and multivariate logistic regression analysis. The results revealed that age, sanitary condition and topography were significantly associated with oocyst shedding (P<0.05). Pre-weaned piglets were at the highest risk for infection, followed by post-weaners, sows and finishing pigs. Good sanitary conditions showed positive effects in decreasing oocysts shedding. Topographically, Cryptosporidium was more common in mountainous zone than that in coastal delta zone. There was an association between the occurrence of diarrhea and the level of Cryptosporidium oocyst excretion within infected pigs. This is the first epidemiological investigation of prevalence and risk factors of Cryptosporidium in pigs in Vietnam.     

Prevalence of Fasciola in cattle and of its intermediate host Lymnaea snails in central Vietnam

The aims of this study were to investigate the prevalence of natural Fasciola infections in both the definitive hosts (cattle) and the intermediate hosts (Lymnaea snails) in central Vietnam. A total of 1,075 fecal samples, randomly collected from cattle in Binh Dinh, Khanh Hoa, and Phu Yen provinces, were examined for Fasciola eggs by a sedimentation method. The overall prevalence of Fasciola was 45.3?%. A subset of the animals (235) was also screened for antibodies against Fasciola by an enzyme-linked immunosorbent assay. Overall, 46.3?% of these animals were shedding Fasciola eggs while 87.2?% were Fasciola seropositive. A lower prevalence of Fasciola was observed in calves ??2?years of age (37.6?%) compared to that in cattle >2?years of age (53.7?%) (p?<?0.05). The prevalence in the rainy season (50.8?%) was significantly different to that in the dry season (38.1?%) (p?<?0.05). Of the 3.269 Lymnaea viridis and 1.128 Lymnaea swinhoei examined, 31 (0.95?%) and seven (0.62?%), respectively, were found to be infected with Fasciola. This appears to be the first epidemiological survey of the prevalence of Fasciola in cattle and snails in these three provinces in central Vietnam.     

Resilience of stand structure and tree species diversity in subtropical forest degraded by clear logging

Subtropical forests in the Ryukyu Islands have been degraded by silvicultural practices, and thus their structural attributes are being shifted to other states dominated by a few tree species. This study clarified the mechanisms of the change, and examined the effect of clear logging on the resilience of a subtropical forest. Sprouting regeneration and typhoon disturbance were introduced into an individual-based model, SEIB-DGVM, for describing stand development and succession. The regeneration dynamics from young secondary to old-growth stands were reproduced fairly well with the model. Sprouting recruitment produced high stem density at the beginning of stand development, which caused a self-thinning trajectory following the −3/2 power law. In the late development stage after 70 years, tree species diversity fluctuated because of the regenerative response of sprouting species and the facilitatory effect of typhoon disturbance on the coexistence of subordinate species. The death of canopy trees because of typhoon disturbances reduced the dominance of Castanopsis sieboldii, and depressed its dominance in the understory. Consequently, the understory species could establish by virtue of fallen canopy trees, and tree species diversity increased at the stand level. Clear logging experiments in the model revealed that species diversity deteriorated, especially in the stand dominated by sprouting species. Resilience of subtropical forests was determined by initial species composition before clear logging. Our simulation results suggest that repeated logging drives subtropical forests with high species diversity to a stand monopolized by C. sieboldii.     

Recent races of spinach downy mildew pathogen <Emphasis Type="Italic">Peronospora farinosa</Emphasis> f. sp. <Emphasis Type="Italic">spinaciae</Emphasis> in Japan

Isolates of spinach downy mildew fungus, Peronospora farinosa f. sp. spinaciae, collected at seven sites in Japan from December 2013 to March 2016, were identified as belonging to races 8, 10, 12 and 13, and one was unauthorized. Races 10, 12, 13 and the unauthorized were first found in Japan.     

Cryopreservation of male and female gonial cells by vitrification in the critically endangered cyprinid honmoroko <Emphasis Type="Italic">Gnathopogon caerulescens</Emphasis>

We investigated the feasibility of cryopreservation of spermatogonia and oogonia in the critically endangered cyprinid honmoroko Gnathopogon caerulescens using slow-cooling (freezing) and rapid-cooling (vitrification) methods. Initially, we examined the testicular cell toxicities and glass-forming properties of the five cryoprotectants: ethylene glycol (EG), glycerol (GC), dimethyl sulfoxide (DMSO), propylene glycol (PG), and 1,3-butylene glycol (BG), and we determined cryoprotectant concentrations that are suitable for freezing and vitrification solutions, respectively. Subsequently, we prepared the freezing solutions of EG, GC, DMSO, PG, and BG at 3, 2, 3, 2, and 2 M and vitrification solutions at 7, 6, 5, 5, and 4 M, respectively. Following the cryopreservation of the testicular cells mainly containing early-stage spermatogenic cells (e.g., spermatogonia and primary spermatocytes), cells were cultured for 7 days and immunochemically stained against germ cell marker protein Vasa. Areas occupied by Vasa-positive cells indicated that vitrification led to better survival of germ cells than the freezing method, and the best result was obtained with 5 M PG, about 50% recovery of germ cells following vitrification. In the case of ovarian cells containing oogonia and stage I, II, and IIIa oocytes, vitrification with 5 M DMSO resulted the best survival of oogonia, with equivalent cell numbers to those cultured without vitrification. The present data suggest that male and female gonial cells of the endangered species G. caerulescens can be efficiently cryopreserved using suitable cryoprotectants for spermatogonia and oogonia, respectively.     

Long-term ecological impacts of clear-fell logging on tree species diversity in a subtropical forest,southern Japan

Defining the spatial arrangement and length of the cutting cycle in a logged area is crucial for reconciling potential conflicts between timber yields and maintenance of ecosystem services in natural forests. In this study, we investigated long-term impacts of clear-fell logging on timber production and tree species diversity in a subtropical forest on the Ryukyu Islands, using an individual-based simulation model. We assumed six logging scenarios defined by combinations of forest type and regeneration processes, which acted as surrogates for spatial scales of clear-fell logging. These scenarios were simulated under cutting cycles ranging from 20 to 150 years. Short-cutting cycles resulted in dominance by the sprouting species Castanopsis sieboldii. The compositional shift was accelerated by the lack of seed dispersal from surrounding forest areas. The simulations demonstrated that a sustainable logging regime maintaining both yield and tree species diversity requires a cutting cycle longer than 50 years. The simulation results also suggest that the trade-off between the recovery of tree species diversity and timber production is favored more in stands surrounded by mature forest than in isolated stands or stands surrounded by immature forest. Ecological risk assessments based on model simulations provide an alternative to current forest management practices that rely on empirical knowledge.