A long-term field study on mosquito vectors of avian malaria parasites in Japan

Avian malaria is a mosquito-borne disease of birds caused by avian Plasmodium spp. in worldwide scale. Some naïve birds show serious symptoms which can result in death. Surveillance of vectors and parasites are important to understand and control this disease. Although avian malaria has been found in Japan, detailed prevalence and dynamics remained understudied. We aimed to observe annual changes in the abundance of mosquitoes and the prevalence of avian Plasmodium parasites in Japan. Mosquitoes were collected using dry ice traps over a 10-year period, at a fixed research area located in Kanagawa prefecture. Collected mosquitoes were investigated for the species composition, population size and prevalence of avian Plasmodium by PCR. Mosquitoes belonging to 13 species in 7 genera were collected (n=8,965). The dominant species were Aedes (Ae.) albopictus and Culex (Cx.) pipiens group (gr.). Seven avian Plasmodium lineages, all of which were previously known, were detected from Cx. pipiens gr., Ae. albopictus, and Tripteroides bambusa. Three genetic lineages were dominant and were probably transmitted by Cx. pipiens gr. whose could be the primary vector of these parasites. Annual variations in the seasonal prevalence of mosquitoes and avian Plasmodium were revealed for the first time during recent 10 years in Japan. Namely, avian Plasmodium occurrence in the vector population peaked often in June to July and September to October when the density of the vector population was presumably high enough for the transmission of avian Plasmodium upon appearance of infected birds.     

Cecal bacterial communities in wild Japanese rock ptarmigans and captive Svalbard rock ptarmigans

Preservation of indigenous gastrointestinal microbiota is deemed to be critical for successful captivebreeding of endangered wild animals, yet its biology is poorly understood. Here, we investigated cecalbacterial communities in wild Japanese rock ptarmigans (Lagopus muta japonica) and comparedthem with those in Svalbard rock ptarmigans (L. m. hyperborea) in captivity. Ultra-deepsequencing of 16S rRNA gene indicated that the community structure of cecal microbiota in wild rock ptarmiganswas remarkably different from that in captive Svalbard rock ptarmigans. Fundamental differences betweenbacterial communities in the two groups of birds were detected at the phylum level. Firmicutes,Actinobacteria, Bacteroidetes and Synergistetes were the major phyla detected in wild Japanese rockptarmigans, whereas Firmicutes alone occupied more than 80% of abundance in captive Svalbard rock ptarmigans.Furthermore, unclassified genera of Coriobacteriaceae, Synergistaceae, Bacteroidaceae, Actinomycetaceae,Veillonellaceae and Clostridiales were the major taxa detected in wild individuals, whereas in zoo-rearedbirds, major genera were Ruminococcus, Blautia, Faecalibacterium andAkkermansia. Zoo-reared birds seemed to lack almost all rock ptarmigan-specific bacteria intheir intestine, which may explain the relatively high rate of pathogenic infections affecting them. We showevidence that preservation and reconstitution of indigenous cecal microflora are critical for successfulex situ conservation and future re-introduction plan for the Japanese rock ptarmigan.     

Temperature sensing by an olfactory neuron in a circuit controlling behavior of C. elegans

Temperature is an unavoidable environmental cue that affects the metabolism and behavior of any creature on Earth, yet how animals perceive temperature is poorly understood. The nematode Caenorhabditis elegans "memorizes" temperatures, and this stored information modifies its subsequent migration along a temperature gradient. We show that the olfactory neuron designated AWC senses temperature. Calcium imaging revealed that AWC responds to temperature changes and that response thresholds differ depending on the temperature to which the animal was previously exposed. In the mutant with impaired heterotrimeric guanine nucleotide-binding protein (G protein)-mediated signaling, AWC was hyperresponsive to temperature, whereas the AIY interneuron (which is postsynaptic to AWC) was hyporesponsive to temperature. Thus, temperature sensation exhibits a robust influence on a neural circuit controlling a memory-regulated behavior.     

Effects of dapagliflozin in combination with insulin on cytochrome P450 activities in a diabetes type 1 rat model

Previous studies reported that diabetes alters the activities of hepatic cytochrome P450 (CYP) enzymes, which, in turn, affects the disposition of some drugs. We herein examined and compared the effects of the combination of dapagliflozin with a low insulin dose, a full dose of insulin alone, and dapagliflozin alone for 3 and 8 weeks on CYP activities in a diabetes type 1 rat model. We induced type 1 diabetes in rats using a single intraperitoneal injection of 60 mg/kg streptozotocin (STZ). Daily treatment with the full dose of insulin alone, dapagliflozin alone, or dapagliflozin in combination with a low dose of insulin was then initiated. STZ-induced rats developed marked hyperglycemia and altered CYP2E activities. Dapagliflozin in combination with a low dose of insulin stabilized hyperglycemia and CYP1A, 2D, 2E and 3A activities. However, dapagliflozin alone did not improve blood glucose levels or CYP activities. These results suggest that the effects of dapagliflozin in combination with a low dose of insulin are similar to those of a full dose of insulin, and stabilize CYP activities in type 1 diabetes.     

Regional Distribution of Two Races of <Emphasis Type="Italic">Phialophora gregata </Emphasis>f. sp. <Emphasis Type="Italic">adzukicola, </Emphasis>Causal Agent of Brown Stem Rot of Adzuki Bean,and Their Genetic Diversity on Hokkaido,Northernmost Island of Japan

The distribution of two races (1 and 2) of Phialophora gregata f. sp. adzukicola, the causal agent of brown stem rot of adzuki bean, was examined using a total of 483 isolates obtained from 39 fields in 19 locations on Hokkaido, Japan between 1997 and 1999. Race 1 was predominant (416 isolates or 86.1%) in the commercial fields tested. Race 2 was found in 25 fields (64.1%), including two fields of cultivar Kita-no-otome (resistant to race 1, but susceptible to race 2), indicating that race 2 was widely distributed in most of the production areas in Hokkaido. Using amplified fragment length polymorphisms (AFLP), a total of 67 polymorphic AFLP markers was recorded among 72 representative isolates (37 and 35 isolates of races 1 and 2, respectively), and 57 distinct haplotypes were detected. Cluster analysis revealed no close correlation between races and AFLP groups. Thus, no difference was observed between values of gene diversity in each race (0.253 and 0.284 in races 1 and 2, respectively), and the coefficient of gene differentiation was very low (G _ST =0.015). Gene differentiation between both races by analysis of molecular variance was not significantly different from zero (Φ=−0.001; p=0.403). However, the results of gene differentiation among regional populations (G _ST =0.290, Φ=0.292; p<0.001) are not necessarily consistent with the result that isolates from the same district were generally not tightly clustered. Received 15 April 2002/ Accepted in revised form 6 September 2002     

The effects of long-term superphosphate application on soil organic matter content and composition from an intensively managed New Zealand pasture

Changes in quantity and composition of soil organic matter (SOM) in pasture receiving annual superphosphate (SP) applications for 41 years at 0 (control), 188 and 376 kg SP ha^?1a^?1 were investigated in soil samples collected from 0–75 and 75–150 mm depths by determining total carbon (TC), total nitrogen (TN), biomass C (BC), biomass N (BN) and subjecting the soils to sequential extraction using cold water, hot water, a mixture of hydrochloric (0.1 M HC1) and hydrofluoric (0.3 M HF) acids (HCl/HF), and sodium pyrophosphate (Na₄P₂O₇) followed by sodium hydroxide (NaOH) for extracting labile and stable SOM fractions. There were significant differences in some SOM fractions between control (0) and SP treatments (188 and 376), especially in the topsoil (0–75 mm) but these were not observed between the two SP treatments. Soil TN (0–75 mm), BN and BN: TN ratio (0–75 and 75–150 mm depths) and the proportion of hot–water–extractable C (HC) in soil TC (HC:TC) (0–75 mm) were significantly greater in the SP treatments than in the control. HC1/HF extractable C and the proportions of soil TC as HC1/HF extractable C (HC1/HF extractable C: TC) were smaller in the topsoil of SP treatments than in the control. Similar results were observed in humin N: TN ratio and the proportions of soil TC as cold–water–extractable carbohydrate (CWcC: TC) and of soil HC as hot–water–extractable carbohydrate (HWcC : HC). Increases in the proportion of labile fraction in SOM were reflected in values of BN, BC: BN, BN: TN, HWcC : HC and HC: TC whereas decreases in the proportion of stable fraction in SOM were found in humin N: TN and HCl/HF–extractable C: TC ratios. Increases in labile SOM (BN and N–containing compounds such as amino acids and amino sugars, which were extractable by hot water but were not present as carbohydrate) and decreases in stable SOM (HC1/ HF–extractable C and humin fraction) in soils under pastures treated with annual SP applications compared with the control were attributed to pasture improvement and the amelioration of P and S deficiency, resulting in a greater return of plant residues and animal excreta and also an increase in clover growth and associated biological N₂ fixation. The additional labile SOM in SP treatments compared with that of the control was not associated with the soil mineral Al and Fe components.     

Expression of regulatory dendritic cell-related cytokines in cattle experimentally infected with Trypanosoma evansi

Trypanosoma evansi causes wasting disease in many livestock. T. evansi infection gives rise to inflammatory immune responses, which contribute to the development of inflammation-associated tissue injury. We previously reported that regulatory dendritic cells (DCs), which act as potential regulators of inflammation, were activated in infected mice and transfer of regulatory DCs to infected mice prolonged their survival. However, the kinetics of regulatory DCs in cattle, which are natural hosts of T. evansi, remained unclear. In this study, we report that the expressions of CCL8 and IL-10, which promote the development of regulatory DCs, were up-regulated in cattle experimentally infected with T. evansi. This finding is potentially useful for studying the control strategy of T. evansi infection in cattle.     

Seed production in white clover (Trifolium repens L.). II. Effect of autumn defoliation on potential seed yield and seed yield components

A field experiment was conducted to assess the effect of autumn defoliation treatments on inflorescence production, potential seed yield and yield components of white clover cv Makibashiro. Between 10 July and 10 October 1992, white clover swards were subjected to one of three treatments: monthly cutting to 3–4 cm (4DEF), cutting to 3–4 cm on 10 August and 10 October (2DEF), and no cutting (control). The total numbers of inflorescences and the proportion of inflorescences in different development categories were counted throughout the period of seed crop development to determine the pattern of inflorescence development and optimum harvest date. There were consistent significant differences in inflorescence density between treatments. Plots which received the 2DEF treatment produced significantly more inflorescences than did the no-defoliation (control) and 4DEF-treatment plots. In this particular year the optimum harvest date (date at which the proportion of ripe inflorescences and potential seed yield was highest) was 26 July, approximately 30 d after peak flowering. Defoliation treatments had no effect on optimum harvest date. However, treatments differed in potential seed yield and ripe inflorescences on this date. The 2DEF treatment gave the highest potential seed yield because there were significantly more ripe inflorescences than either the contol or 4DEF plots. Control plots produced inflorescences with more florets than the other two defoliation treatments, but the differences were not always significant. Seed number per pod was higher in inflorescences obtained from previously defoliated plots than from control plots. The 1000-seed weight was significantly lower in inflorescences developed in 4DEF plots than those developed in 2DEF and control plots. The results are discussed in relation to the management of white clover seed crops and the importance of canopy structure and light intensity for seed production.