Simultaneous detection by multiplex PCR of the high-temperature-growing Pythium species: P. aphanidermatum, P. helicoides and P. myriotylum

The objective of this study was to develop a multiplex PCR detection method for the high-temperature-growing pathogens Pythium aphanidermatum, P. helicoides and P. myriotylum. Species-specific primer pairs were designed that targeted the rDNA ITS regions. The multiplex PCR was constructed with a universal primer pair for eukaryotes directed at the 18S rDNA as a positive control, in addition to the three species-specific primer pairs. When the multiplex PCR was applied to naturally infested soils, the expected species were reliably identified, suggesting that the method is suitable for the detection of the three Pythium pathogens in environmental samples.     

Pathogenic characters of Japanese potato strains of Ralstonia solanacearum

Ralstonia solanacearum (Rs) strains in phylotypes I and IV isolated from potato in Japan were investigated for pathogenicity on potato, tomato, eggplant, Solanum integrifolium, tobacco, groundnut, and pumpkin. The strains were divided into 17 types based on differences in their pathogenicity on the tested plants. Particularly, the pathogenicity of most phylotype I strains on eggplant was distinctly different from that of the phylotype IV strains. When nine potato varieties (included two breeding lines) were inoculated with several Rs strains, phylotype IV strains were highly virulent on the breeding lines that are regarded as resistant to phylotype I strains.     

Development of a docosahexaenoic acid (DHA)-rich yellowtail <Emphasis Type="Italic">Seriola quinqueradiata</Emphasis> using tuna by-product oil

Because a diet rich in docosahexaenoic acid (DHA) is beneficial to human health, it is desirable for yellowtail Seriola quinqueradiata intended for human consumption to contain a high amount of DHA. We investigated the effects on the growth and fatty acid composition of yellowtail of replacing some of the pollack liver oil (PO) in the yellowtail diet with a DHA-rich tuna oil (TO). Experimental diets were prepared in which PO was replaced with 0, 15, 30, and 60% TO. Replacement of PO with TO did not negatively affect growth in a 16-week trial. In contrast, the feed efficiency of the group that received 60% TO was significantly higher than that of the control group after 6 weeks. The DHA level in the whole fish body increased with increasing dietary TO level. The groups that received 30 and 60% TO replacement diets showed significantly higher DHA levels than those of the control group. DHA level in the fillet was significantly higher in the group that received 60% TO than in the control group. DHA retention tended to increase with increasing TO level. These results show that utilizing TO as a fat source can increase DHA accumulation without incurring any adverse effects on the growth of yellowtail.     

Effects of dietary phosphorus level on non-faecal phosphorus excretion from yellowtail (Seriola quinqueradiata Temminck & Schlegel) fed purified and practical diets

Non-faecal phosphorus (P) was determined for large yellowtail to estimate a minimum available P requirement (Experiment  1) and to justify inorganic P supplementation in a fish meal-based diet (Experiment 2). In Experiment 1, purified diets with incremental P concentrations were fed to yellowtail (mean weight 917 g) at a feeding rate of 1.5% of body weight. The peaks of non-faecal P excretion appeared 5–6 h after feeding in fish fed more than 4.5 g available P kg⁻¹ dry diet. Broken-line analysis indicated that the minimum available P requirement was 4.4 g kg⁻¹ dry diet. In Experiment 2, a purified diet (PR) containing 6.5 g available P kg⁻¹ and a fish meal-based diet with (F1) and without (F0) additional phosphorus were fed to yellowtail (mean weight 1.1 kg) at 1.5% (PR) and 2% (F0 and F1) feeding rates respectively. There was no significant difference in P excretion between fish fed the F0 (5.5 g soluble P kg⁻¹ dry diet) and the PR diet. However, significantly higher (34.5%) amounts of non-faecal P excretions (7.4 g soluble P kg⁻¹ dry diet) were found in fish fed F1 compared with the F0 diet. This suggested that there was an excess of dietary P in the F1 diet and that supplementation is not needed in fish meal-based diets for large yellowtail.     

Effects of natural feeding stimulants and glutamic acid supplementation on the feed intake,growth performance and digestive enzyme activities of red sea bream (Pagrus major) fed fish meal‐free soy protein concentrate (SPC)‐based diet

Two experiments were conducted for red sea bream (Pagrus major). In experiment 1, the optimum level of glutamic acid and natural feeding stimulants to enhance feed intake were determined and found that glutamic acid level of 0.5% and fish meat hydrolysate (FMH) were effective. In experiment 2, fish were fed with soy protein concentrate (SPC)‐based diet with synthetic feeding stimulants (Basal diet), the Basal diet with FMH (FMH diet), the FMH diet with glutamic acid (FMHG diet) and with fish meal diet (FM diet) as a control until satiation for 8 weeks. Feed intake of FMHG‐fed fish was significantly higher than others (p < 0.05). Specific growth rate and the feed conversion ratio of FMHG were comparable to those of FM‐fed fish (p > 0.05). Relative visceral fat ratio and crude lipid content of any SPC‐based diet‐fed fish tended to be lower than those of FM diet‐fed fish. There were no significant differences in trypsin and lipase activities hepatopancreas among treatments. SPC can be utilized as a sole protein source in a diet for red sea bream. The lower growth performance in SPC‐based diet‐ fed fish was not due to poor digestive enzyme secretion but could be associated with lipid utilization disorder.     

Comparison of the effectiveness of high and low LET radiations for the proportion of survivals with liver tumors at every age in (C57BL/6N x C3H/HeN) F1 mice

To investigate the late effects of neutrons at the energy below 1 MeV on the liver carcinogenesis as a function of age, one-week old mice were exposed to 1.0 Gy monoenergetic neutrons (0.317, 0.525 and 1.026 MeV) or 137Cs gamma rays. Survival and carcinogenesis were examined by 18 months of age. Following radiation, tumor incidences in liver, Harderian gland, lung, ovary and pituitary gland were compared. The proportion of the lifespan with liver tumors exposed to neutrons to that exposed to gamma rays was calculated as a function of age. Survival rates among the three groups exposed to neutrons of different energies were not significantly different from one another but shorter than those treated with gamma rays for both sexes. With regard to liver tumor incidence evaluated at 18 months of age, the effectiveness of neutrons to gamma rays was 2.54 for females, and 2.08 for males by the factor. Levels of estrogen in the serum were similar between mice bearing liver tumors and those devoid of tumors. In conclusion, all three energies of neutrons induced similar effectiveness with respect to liver carcinogenicity. Proportions of the lifespan with liver tumors of neutron-exposed to gamma-exposed were shorter in females than males along with ages over 12 months. To obtain this factor at every age contributed for the evaluation of the biological effectiveness of radiations with the parameter of tumor incidence and latency simultaneously.     

Derivation of two-way volume equation for bamboo, <Emphasis Type="Italic">Phyllostachys pubescens</Emphasis>

We derive a two-way volume equation for estimating the apparent culm volume of one of the largest bamboo species, Phyllostachys pubescens Mazel ex Houz. The volume equation was derived from the assumptions that (1) the relative culm form can be expressed by Kunze’s equation and (2) normal form-factors at two different relative heights are steady at constants independent of culm sizes. A total number of 200 sample culms were collected from a stand of P. pubescens in Mt. Toshima, Kumamoto Prefecture, western Japan, and were randomly bisected into two sets of data, i.e. modeling and test data. For the modeling data, normal form-factors at 0.6 and 0.9 in relative height were steady at 0.908 and 0.448, respectively. The coefficients of the volume equation were determined based on these steady values of the normal form-factors. For the test data, the apparent culm volume was estimated from diameter at breast height and culm height with the determined volume equation. The mean error and root mean square error of the estimated culm volume were, respectively, 8.120 × 10⁻⁵ and 3.291 × 10⁻³ m³, and there was no significant difference between estimated and actual volume. In conclusion, the two-way volume equation presented here appears to be convenient for predicting the apparent culm volume for P. pubescens.     

Evidence of global chlorophyll d

Although analyses of chlorophyll d (Chl d)-dominated oxygenic photosystems have been conducted since their discovery 12 years ago, Chl d distribution in the environment and quantitative importance for aquatic photosynthesis remain to be investigated. We analyzed the pigment compositions of surface sediments and detected Chl d and its derivatives from diverse aquatic environments. Our data show that the viable habitat for Chl d-producing phototrophs extends across salinities of 0 to 50 practical salinity units and temperatures of 1 degrees to 40 degrees C, suggesting that Chl d production can be ubiquitously observed in aquatic environments that receive near-infrared light. The relative abundances of Chl d derivatives over that of Chl a derivatives in the studied samples are up to 4%, further suggesting that Chl d-based photosynthesis plays a quantitatively important role in the aquatic photosynthesis.     

Abstracts of Nippon Dojohiryogaku Zasshi

Abstract

The humus composition was analyzed and the humic acid characterized by UV and visible absorption spectroscopy in order to investigate the rotting and maturing process of city refuse compost according to the method of Kumada et al. During the composting process, the following findings were obtained: (1) the HT value was almost constant, but the HE/HT ratio varied somewhat, (2) HA increased with decrease in FA, and the PQ value so increased clearly, (3) the shoulder-like absorption at a wavelength near 270 nm weakened, and (4) the RF value of humic acid increased, whereas the Δ log K value seldom varied.

The IR spectrum of humic acid gradually changed as follows: (1) the absorption band in the 1700-1600 cm^-1 region and in the 1550-1500 cm^-1 region increased slightly, (2) the band in the 1100-1000 cm^-1 region decreased, and (3) the bands at 835 and 710 cm^-1 com pletely disappeared. On the whole, the shape of the IR spectrum of the city refuse compost became featureless. These changes were probably due to the oxidation which occurred in the composting process.