Cryptosporidium infection in dogs in Osaka,Japan

Cryptosporidium parvum is a zoonotic pathogen composed of genetically distinct but morphologically identical genotypes. Recent molecular study indicates that dogs may transmit the cattle genotype, which is known to be pathogenic to humans. Although large-scale studies of Cryptosporidium infection in dogs have been performed in several countries, the isolates were not accurately identified because of the lack of a method for molecular analysis. It is important to identify the isolates harbored in dogs, which come in close contact with humans, in order to control human cryptosporidiosis. The aim of the present study was to calculate the prevalence of Cryptosporidium infection in dogs in Osaka city, Japan, and to characterize the isolates molecularly. The prevalence was determined to be 9.3% (13/140) by PCR. All isolates were found to be Cryptosporidium canis (previously known as the dog genotype), which is thought to be non-pathogenic in humans, based on the sequencing of diagnostic fragments. These results indicate that PCR-based diagnostic methods are a useful tool for the diagnosis and molecular epidemiology of Cryptosporidium infection in dogs, and that dogs living in Osaka are not a significant reservoir for human cryptosporidiosis. It is unclear why C. canis is dominant in dogs. Further study is required to understand this partial parasitism.     

Effect of dietary vitamin E on broiler meat qualities,color, water‐holding capacity and shear force value,under heat stress conditions

This study was conducted to evaluate the effect of dietary vitamin E (VE) on broiler meat quality, especially focused on PSE (pale color, soft and exudative), under chronic heat stress (HS) conditions. Twenty‐eight‐day‐old female Ross broilers were kept in independent cages with a controlled temperature of 24°C (normal temperature: NT) or 30°C (high temperature: HT). The NT chickens were fed basal feed. The HT chickens were fed basal feed (HT) or VE (200 mg/kg) added feed (HT + E). Broilers were weighed and slaughtered at 38 days old. The breast muscle was removed immediately and then the samples were used for determination of meat color, pH, water holding capacity (WHC) and shear force value (SFV). Body weight gain and feed intake were significantly decreased in the HT and HT + E groups compared to the NT group. VE supplementation did not affect the growth performance. Chronic HS at 30°C for 10 days may cause deterioration of meat quality such as PSE. The effects of chronic HS on meat quality were most significant in the toughness of broiler breast meat. Supplementation of VE in broiler feed would be effective to prevent the extent of PSE on broiler meat by chronic HS.     

Gross nitrification rates in four Japanese forest soils: heterotrophic versus autotrophic and the regulation factors for the nitrification

Measurements of gross NH ₄ ⁺ and NO ₃ ^? production in forest soils were conducted using the ¹⁵N pool dilution method. Mineral topsoils (0?C10?cm depth) were collected from four forests from northern to southern Japan with a natural climate gradient to elucidate the mechanisms regulating gross nitrification rates in forest soils. Additionally, we attempted to evaluate the relative importance of heterotrophic nitrification in gross total nitrification using acetylene as a specific inhibitor of autotrophic nitrification. Distinct differences were found among sites in the gross rates of NH ₄ ⁺ production (3.1?C11.4?mg?N?kg^?1?day^?1) and gross total nitrification (0.0?C6.1?mg?N?kg^?1?day^?1). The rates of gross heterotrophic nitrification were low in this study, indicating that heterotrophic nitrification is of minor importance in most forest mineral topsoils in Japan. Significant relations were found between gross autotrophic nitrification and gross NH ₄ ⁺ production, soil N, and soil C concentrations, but none was found between gross autotrophic nitrification and soil pH. We determined the critical value of the gross NH ₄ ⁺ production rates for gross autotrophic nitrification under which no gross autotrophic nitrification occurred, as well as the critical soil C/N ratio above which gross autotrophic nitrification ceased. Results show that tight coupling of production and consumption of NH ₄ ⁺ prevents autotrophic nitrifiers from utilizing NH ₄ ⁺ as long as NH ₄ ⁺ availability is low.     

Mapping and use of QTLs controlling pod dehiscence in soybean

While the cultivated soybean, Glycine max (L.) Merr., is more recalcitrant to pod dehiscence (shattering-resistant) than wild soybean, Glycine soja Sieb. & Zucc., there is also significant genetic variation in shattering resistance among cultivated soybean cultivars. To reveal the genetic basis and develop DNA markers for pod dehiscence, several research groups have conducted quantitative trait locus (QTL) analysis using segregated populations derived from crosses between G. max accessions or between a G. max and G. soja accession. In the populations of G. max, a major QTL was repeatedly identified near SSR marker Sat_366 on linkage group J (chromosome 16). Minor QTLs were also detected in several studies, although less commonality was found for the magnitudes of effect and location. In G. max × G. soja populations, only QTLs with a relatively small effect were detected. The major QTL found in G. max was further fine-mapped, leading to the development of specific markers for the shattering resistance allele at this locus. The markers were used in a breeding program, resulting in the production of near-isogenic lines with shattering resistance and genetic backgrounds of Japanese elite cultivars. The markers and lines developed will hopefully contribute to the rapid production of a variety of shattering-resistant soybean cultivars.     

Improvement of penetrability of sugi wood by impregnation of bacteria using sap-flow method

The sap flow method of wood impregnation was conducted to aid the movement of bacteria through the living tree, thereby accelerating their distribution through wood within a short time. When log-pond water containing mixed species of bacteria were introduced in the living trees by butt-end dipping and then laid horizontally for 6 months, bacteria could be delivered by sap flow vertically through the sapwood tracheids up to the high portions from the butt-end of trees; they could be detected in the ray parenchymal cells. The sap-flow method was assumed to deliver the bacteria to sapwood and heartwood at high levels of standing sugi (Cryptomeria japonica D. Don) trees. Degradation of the pit membranes was observed even at more than 3 m upward from the butt-end after the treatment in sapwood, as well as around the butt-end of the trees. The uptake of the aqueous dye solutions in sapwood of the treated logs were about eight times more than those of control specimens after 8h.Part of this report was presented at the 40^th annual meeting of the Japan Wood Research Society, Tsukuba, April 1990; the 41^st annual meeting of Japan Wood Research Society, Matsue, April 1991; and the IUFRO 4^th international conference on wood drying, Rotorua, New Zealand, August 1994     

Stand-scale transpiration estimates in a Moso bamboo forest: II. Comparison with coniferous forests

In western Japan, Moso bamboo (Phyllostachys pubescens) forests have been expanding by replacing surrounding vegetation such as coniferous plantation forests and natural broadleaved forests. It has been speculated that the replacement of surrounding vegetation by bamboo forests could alter the vegetation water cycle and available water resources. We quantified stand-scale transpiration (E) in a bamboo forest on the basis of sap-flux measurements and compared the E value with values for coniferous forests. The annual E was estimated to be 567 mm. Seasonal trends in E primarily corresponded to seasonal trends in the vapor pressure deficit. Annual E for the bamboo forest was higher than that for the coniferous forests by 12% of annual precipitation (P). This difference in annual E is comparable with the difference in annual interception evaporation (I) relative to P between bamboo and coniferous forests; previous studies reported lower I for bamboo forests by ∼10% of P. Thus, the sum of E and I was comparable for bamboo and coniferous forests. As this study is the first measuring E of bamboo forests, further studies are required to examine the generality of our results.     

Chemical constituents of the Vietnamese liverwort Porella densifolia

From the ether extract of Porella densifolia, the first liverwort collected and chemically investigated in Vietnam, a kaurane diterpenoid, ent-kauren-15-one (1) and two sesquiterpene norpinguisone (2) and norpinguisone methyl ester (3) have been purified. Their structures were elucidated by spectroscopic analysis. In addition, an X-ray crystal structure of norpinguisone was obtained, allowing to determine its stereochemistry. Furthermore, the inhibitory activity of nitric oxide (NO) production in RAW 264.7 cells stimulated by lipopolysaccharide (LPS) of compounds 1–3 was examined with their IC₅₀ values of 69.4, 45.5 and 1.68 μM, respectively.     

Evaluation of the wave attenuation function of a coastal black pine Pinus thunbergii forest using the individual-based dynamic vegetation model SEIB-DGVM

The wave attenuation function of a Japanese black pine forest was evaluated based on its growth at different initial planting densities (P _ini) using the spatially explicit, individual-based, dynamic global vegetation model. The forest dynamics were simulated for 150 years utilizing datasets for tree density and stem diameter at different stand ages obtained in the field. To elucidate the ability of the forest to reduce the wave height $ \eta_{t} $ (m), a long linear wave that propagates on dry ground was assumed. The attenuation of $ \eta_{t} $ (m) was expressed as follows: $ \eta_{t} = \eta_{t0} \exp ( - k_{\text{i}} x) $ , where $ \eta_{t0} $ , x, and k _i are the initial wave height (m), the distance (m), and the wave attenuation coefficient (m^?1), respectively. The tree destruction caused by the waves was considered in order to estimate k _i. The model suggested that there was a peak age that maximized k _i and was dependent on $ \eta_{t} $ , and that the maximum k _i attained decreased with increasing $ \eta_{t} $ . When P _ini was varied widely from 0.5 to 4 m^?2, the maximum k _i for a relatively low wave height (≤3 m) changed dramatically. For example, when $ \eta_{t} = 2{\text{ m}},$ the maximum k _i ranged from 0.008 to 0.031 m^?1, depending on P _ini. Thus, utilizing a relatively low P _ini would be an efficient way of quickly creating a forest capable of sufficient wave attenuation in areas where a relatively high wave height (≥4 m) is expected. It was concluded that regular harvesting and planting would be required to realize the full potential of the coastal forests to attenuate waves, and that tailoring P _ini is one of the management options that could be used to establish a wave prevention forest.     

Accumulation mechanism of γ-aminobutyric acid in tomatoes (Solanum lycopersicum L.) under low O2 with and without CO2

The storage of ripe tomatoes in low-O(2) conditions with and without CO(2) promotes γ-aminobutyric acid (GABA) accumulation. The activities of glutamate decarboxylase (GAD) and α-ketoglutarate-dependent GABA transaminase (GABA-TK) were higher and lower, respectively, following storage under hypoxic (2.4 or 3.5% O(2)) or adjusted aerobic (11% O(2)) conditions compared to the activities in air for 7 days at 25 °C. GAD activity was consistent with the expression level of mRNA for GAD. The GABA concentration in tomatoes stored under hypoxic conditions and adjusted aerobic conditions was 60-90% higher than that when they are stored in air on the same day. These results demonstrate that upregulation of GAD activity and downregulation of GABA-TK activity cause GABA accumulation in tomatoes stored under low-O(2) conditions. Meanwhile, the effect of CO(2) on GABA accumulation is probably minimal.