Growth response ofMelaleuca cajuputi to flooding in a tropical peat swamp

We investigated the growth response ofMelaleuca cajuputi Powell to flooding at 3 sites in a tropical swamp in southern Thailand. The relative growth rate (RGR) in height tended to be higher where the water level was higher. The maximumRGR in height was achieved during the flood period at the 2 sites where water levels were higher than at the other site. The height growth ofM. cajuputi was not reduced by flooding, but enhanced. No decline in growth due to post-anoxic injury was observed after flooding.Melaleuca cajuputi may have mechanisms to tolerate rhizospheric oxygen deficiency and to avoid post-anoxic injury. This study was supported by a Grant-in-Aid for Basic Research (No. 09NP0901) from the Ministry of Education, Science, Sports, and Culture of Japan.     

固沙植被多功能高分子复合材料对沙土物理性状的影响

采用饱和透水系数法和加压板法研究了固沙植被多功能高分子复合材料混入沙土后沙土的透水系数与保水能力的变化,用扫描电子显微镜及万能光学显微镜表征了改良土壤的微观及细观形态.结果表明:将0.5%的固沙植被多功能高分子复合材料混入沙土后,其沙土物理性状发生明显变化,有利于形成人工团粒结构,大大提高了沙土的含水量及植物用有效水的含量,对固沙植被多功能高分子复合材料改良沙土的机理进行了探讨,为固沙植被多功能高分子复合材料应用于沙土种植提供了新的依据.     

Autonomous xenogenic cell fusion of murine and chick skeletal muscle myoblasts

Cell‐cell fusion has been a great technology to generate valuable hybrid cells and organisms such as hybridomas. In this study, skeletal muscle myoblasts were utilized to establish a novel method for autonomous xenogenic cell fusion. Myoblasts are mononuclear myogenic precursor cells and fuse mutually to form multinuclear myotubes. We generated murine myoblasts (mMBs) expressing green fluorescent protein (GFP) termed mMB‐GFP, and the chick myoblasts (chMBs) expressing Discosoma red fluorescent protein (DsRed) termed chMB‐DsRed. mMB‐GFP and chMB‐DsRed were cocultured and induced to differentiate. After 24 h, the multinuclear myotubes expressing both GFP and DsRed were observed, indicating that mMBs and chMBs interspecifically fuse. These GFP⁺/DsRed⁺ hybrid myotubes were able to survive and grew to hyper‐multinucleated mature form. We also found that undifferentiated mMB‐GFP efficiently fuse to the chMB‐DsRed‐derived myotubes. This is the first evidence for the autonomous xenogenic fusion of mammalian and avian cells. Myoblast‐based fusogenic technique will open up an alternative direction to create novel hybrid products.     

Effects of weaning and syndyphalin-33 on expression of melanocortinergic appetite-regulating genes in swine

Syndyphalin-33 (SD-33) increases feed intake in sheep and recently weaned pigs. To assess the effects of SD-33 on hypothalamic gene expression, hypothalami were collected from unweaned pigs (n=19; 21±3 d of age) on day 0. Remaining pigs received an intramuscular injection of 0.5 μmole/kg SD-33 (SD) or saline (VEH) and weaned into individual pens. On days 1, 4, and 7 after weaning, hypothalami were collected from subsets of pigs (n=8 or 9) within each treatment group. Expression of μ-opioid receptor (MOR) was less in SD pigs than in VEH pigs on day 1 and day 4, suggesting down-regulation of the receptor by SD-33. Expression of hypothalamic melanocortin 4 receptor (MC4R) at 1 d after weaning was increased in VEH pigs (but not SD pigs) relative to levels before weaning. Expression of AGRP was not significantly altered by weaning or treatment at 1 d after weaning. At 4 d after weaning, expression of AGRP was greater in SD pigs than in VEH pigs, but at day 7 expression was less in SD pigs than in VEH pigs. A strong positive correlation was noted between expression levels of MOR and MC4R across treatment and time. Treatment with SD-33 appeared to partially abrogate the effects of weaning on expression of two key appetite-regulating genes within 24 h. Effects of SD-33 appear to be mediated at least in part by the μ-opioid receptor and include actions on the melanocortinergic pathway.     

Antimicrobial susceptibility of Escherichia coli isolates from wild mice in a forest of a natural park in Hokkaido, Japan

To reveal the antimicrobial susceptibilities of Escherichia coli isolates from wild mice, 81 E. coli isolates were obtained from 109 voles (Clethrionomys spp.), 52 large Japanese field mice (Apodemus speciosus) and 19 small Japanese field mice (A. argenteus) captured in a forest of a natural park in Hokkaido, Japan. Seventy-eight of the 81 E. coli isolates were susceptible to all 10 antimicrobial agents tested. One E. coli isolate was resistant to ampicillin, dihydrostreptomycin, kanamycin, chloramphenicol and oxytetracycline. Two isolates were resistant to oxytetracycline. A low prevalence of antimicrobial resistance was maintained among wild mice that inhabited the forest.     

Antimicrobial resistance in Salmonella isolates from apparently healthy food-producing animal from 2000 to 2003: the first stage of Japanese veterinary antimicrobial resistance monitoring (JVARM)

Antimicrobial susceptibility of 183 Salmonella isolates from apparently healthy food-producing animals obtained during the period from 2000 to 2003 throughout Japan was examined. Of 29 serovars identified, Salmonella Infantis (37.7%) was the most prevalent, followed by S. Typhimurium (19.7%). Salmonella bacteria resistant to dihydrostreptomycin (77.6%) were about 10% more prevalent than those resistant to oxytetracycline (67.8%), though the nation-level veterinary use of tetracycline antibiotics is much greater than that of streptomycin in Japan. In seventeen isolates (9.3%) resistant to nalidixic acid, single point mutations were detected at 84 or 87 in the quinolone resistance-determining region of the gyrA gene.     

Depletion of stored nutrients during fasting in Nile tilapia (Oreochromis niloticus) juveniles

We evaluated growth performance and metabolic responses in Nile tilapia (Oreochromic niloticus) juveniles (30.2 ± 0.9 g) subjected to 1 (F1), 2 (F2), or 3 weeks (F3) of fasting and then refed for 10 weeks (10WR) compared to controls (FC), which were fed for the full 13-week trial. Weight gain and specific growth rate (SGR) during fasting were lower in all treatments compared to the FC. However, during refeeding, feed intake/body mass and SGR increased in F1, F2, and F3, inducing partial compensatory growth. The hepatosomatic index (HSI), visceral fat index (VFI), liver glycogen (LG), and carcass lipid levels dropped in all fasted fish compared to FC (P < 0.05), showing a depletion of stored nutrients such as fat and LG. Along with LG, fat reserves were mobilized during fasting to maintain basal metabolism and survival, but these energy constituents returned to control levels at 10WR, at which time HSI was higher in all refed fish compared to FC. Additionally, the variables VFI, LG, and lipid in carcass increased in all refed fish, equaling those of FC at 10WR. The results showed that, in contrast with other protocols that used smaller tilapia juveniles, the feeding strategies utilized for Nile tilapia juveniles in this study (1 to 3 weeks of fasting and 10WR) were able to induce only partial compensatory growth. It can be concluded that in situations that require complete food restriction in juvenile Nile tilapia (30 g), an acceptable strategy is to limit the period of fasting to 1 week or less to minimize losses and to achieve partial compensatory growth.     

Effect of furnish type and high-density raw material from mill residues on properties of particleboard panels

The purposes of this study were to examine the use of furniture mill residues containing high-density raw materials in particleboard production and to evaluate the effect of mixing several types of furnish on board performance. Wood wastes collected from the furniture industry in Japan containing matoa (Pometia pinnata), Douglas-fir (Pseudotsuga menziesii), and sugi (Cryptomeria japonica) with different particle shapes were prepared as raw materials for use in the manufacture of experimental particleboards. Seven board types and three mixed boards were manufactured with three replications. Methylene diphenyl diisocyanate (MDI) resin was applied at 6 % content in mat preparation. The pressing conditions were temperature of 180 °C, initial pressure of 3 MPa, and pressing time of 5 min. The target density was 0.72 g/cm³. This study showed that matoa particleboard had properties suitable for use in interior applications, although its properties were considered inferior compared with other particleboards. Improvement of matoa particleboard could be achieved by mixing with higher quality wood particles such as those from sugi or Douglas-fir. The furnish type used in this study affected board performance. All residues from furniture mills have the potential to be used for particleboard production, even when they contain different furnish types and wood species.