Protein synthesis measured in the whole body of chick embryos cultured in vitro

1. Whole body protein synthesis was measured in chick embryos cultured in vitro. On day 7 of incubation chick embryos were cultured for 60 min in synthetic serum‐free medium containing 4‐[³H]phenylalanine. Specific radioactivities in free and protein‐bound phenylaline in the whole embryo were measured, starting 2 min after commencement of the culture process.

2. The values for fractional synthesis rate (FSR) estimated in vitro at 20, 30, 45 and 60 min during the embryo culture agreed well, ranging from 35 to 40%/d, suggesting that the method would serve as a useful model for studying the effect of growth promoters in chick embryos.

3. Bovine insulin in the synthetic medium did not affect FSR of protein in chick embryos cultured in vitro.     

The nitrogen‐sparing effect of methionine in chicks receiving a protein‐free diet supplemented with arginine: Effect of various methionine substituents

1. The nitrogen‐sparing effect of methionine in chicks fed on a protein‐free diet containing arginine was examined in three 10‐d trials. Chicks received either a protein‐free diet, this diet supplemented with arginine and methionine or diets containing arginine in which the methionine was replaced by various methionine‐related compounds.

2. Body‐weight changes, nitrogen retentions and uric acid‐nitrogen excretion indicated that the methyl moiety was unlikely to contribute to nitrogen sparing activity and that cysteine, or possibly glutathione, played an important role. The possible mechanism of the nitrogen‐sparing effect is discussed.     

Establishment of a potency test by ELISA for a rabies vaccine for animal use in Japan

The ELISA we developed was able to determine the antigen content and was suitable for a potency test, and we described a relative potency assay method which determines the potency of test vaccines by comparing the ELISA value of a test vaccine to that of a reference vaccine. In the present study, we standardized the reference vaccine used for determining the potencies of test vaccines, and established a potency test by ELISA. We evaluated the proposed reference vaccine by the neutralizing antibody responses in dogs after vaccination, by the challenge protection test in guinea pigs (GP potency test), which is the earlier official potency test used in Japan, and by the NIH potency test, which is widely used throughout the world. The results showed that a 4-fold dilution of the proposed reference vaccine induced sufficient immunity in dogs. A 3-fold dilution of the proposed reference vaccine passed the GP potency test. The international units (IU) calibrated by the NIH potency test were 3.7 IU/dose. From the results and the WHO recommendation that veterinary rabies vaccines should have a potency of at least 1.0 IU/dose, we determined to dilute the proposed reference vaccine by 3 fold and regarded it as the reference vaccine. Finally, we confirmed that there is a good agreement between the results of the potency test by ELISA and the results of the GP potency test. The establishment of the potency test by ELISA has made it possible to monitor the potency in the production process and has contributed to the stable production of the vaccine.     

Strain differences in whole-body protein turnover in the chicken embryo.

1. Whether or not there is a strain difference in embryonic whole-body protein turnover rates was tested using the chicken embryos of Rhode Island Red carrying a sex-linked dwarf gene (dwarf), White Leghorn (layer), and White Cornish X White Plymouth Rock (broiler) strains on day 12 of incubation. 2. Whole-body protein synthesis was estimated by injecting L-[15N]-phenylalanine either intraperitoneally or intravenously on day 12 of incubation in order to investigate the effect of the route of isotope administration. The results showed that the values for fractional and absolute synthesis rates were approximately 13% higher by intravenous injection than by intraperitoneal injection. 3. Whole-body protein turnover, both in terms of fractional and absolute rates, was significantly faster in dwarf than in broiler embryos, with intermediate values in layer embryos, although no growth differences were observed on day 12. 4. Difference in egg weight, measured before incubation, did not affect protein turnover. 5. It was concluded that the strain difference manifested in whole-body protein turnover of the chicken embryo would probably be a reflection of differences in genetic background.     

不同水分含量对潮土和火山灰土硝化动态的影响

在试验室条件下研究了不同水分含量对取自中国的潮土和日本的火山灰土硝化动态的影响。潮土在土壤硝化过程中的土壤水分含量以田间持水量的60%～90%较为适宜,低于田间持水量的60%引起土壤硝化力降低。火山灰土在土壤硝化中的土壤水分含量以田间持水量的75%～90%较为适宜,低于田间持水量的75%引起土壤硝化力降低。潮土在硝化培养中有亚硝酸盐出现,火山灰土没有亚硝酸盐被检出。土壤亚硝酸盐含量在低水分含量下峰值低,持续时间较长,在高水分含量下峰值高,持续时间较短。     

Variable-timing,fixed-rate application of cattle biogas effluent to rice using a leaf color chart: microcosm experiments in Vietnam

ABSTRACT

Livestock production plays a leading role in agricultural land-use change. Producing biogas from livestock waste and subsequently using the biogas effluent as fertilizer for crops is a promising option to solve environmental problems resulting from expanding livestock production. However, it is difficult to promptly and accurately measure the nitrogen (N) concentration of effluent for farmers in developing countries, making precise N management difficult. The objectives of the current study were (1) to evaluate the feasibility of variable-timing, fixed-rate application of cattle biogas effluent using a leaf color chart (LCC) for rice (Oryza sativa L.) and (2) to determine the optimum LCC threshold for grain yield. We conducted two microcosm experiments in the Mekong Delta of Vietnam in 2018 using eight treatments of N-fertilizer application. In the Zero treatment, we applied no N. In the Estd treatment, we split-applied N as effluent (E) at fixed rate and timing as the standard method. In E2.75, E3.00, E3.25, E3.50, and E3.75, we applied effluent whenever the LCC value went below 2.75, 3.00, 3.25, 3.50, and 3.75, respectively. In U3.25, we applied N as urea (U) whenever the LCC value fell below 3.25. The total effluent-N application rate ranged from 90 to 210 kg N ha^?1 season^?1. Rice growth was normal but there was a substantial yield gap between the two microcosm experiments due to the seasonal difference in solar radiation. Rice yield tended to increase with increasing LCC threshold. There was a positive linear relationship between LCC and chlorophyll content (SPAD) values (R ² = 0.73–0.79). Grain yield was well explained (R ² = 0.70–0.89) by the seasonal mean LCC or SPAD value. Plant total N uptake increased with increasing LCC threshold, but the three calculated indices of N use efficiency (NUE) – apparent N recovery, agronomic NUE, and internal NUE – were not always improved with a higher LCC threshold. Our results showed that the tested variable-timing, fixed-rate strategy for the application of cattle biogas effluent was feasible and the optimum LCC threshold for grain production was 3.75 under the current microcosm conditions.     

Iodine desorption from rice paddy soil

Laboratory experiments on the desorption phenomena of iodine from rice paddy soil under waterlogged conditions, with a special reference to soil redox potential (Eh) and pH, have been conducted. Radioiodine tracer (1251), added to the soil, was readily sorbed on it. At the beginning of the waterlogging, the iodine desorption was low. However, iodine was desorbed into soil solution with time. The iodine desorption was enhanced markedly by the addition of organic substances such as straw pieces and glucose to the soil. Cultivation of rice plants in soil also affected the iodine desorption, suggesting root exudates and/or root autolysis might be participating in the desorption process. Eh dropped considerably after soil was waterlogged due to microbial metabolisms. Particularly low Eh values were observed in soils with plants and also with added organic substances. A negative correlation was seen between the desorption and soil Eh. High desorption was frequently observed when the Eh dropped to about -100 mV or below. Due to the reducing conditions (low Eh) by waterlogging, iodine in soil was leached into the soil solution; consequently total iodine concentration in paddy soil was considerably lower than forest and upland field soils. These iodine desorption phenomena under anaerobic conditions should be considered in assessing transfer of the long-lived radioiodine (129I) in the environment, especially in rice fields and marshland.     

Influence of dietary protein intake on whole-body protein turnover in chicks

1. Experiments were conducted to investigate whether or not varying dietary protein intake affects whole-body protein turnover rates in young chicks. 2. Seven-d-old single comb White Leghorn male chicks were fed on diets with protein concentrations of 0, 100, 200 or 400 g/kg diet under conditions of ad libitum or equalised feeding. At the end of the experiments, the rate of protein synthesis and protein degradation in the whole body were measured in vivo. 3. The results showed that both fractional and absolute rates of protein synthesis increased with increasing dietary protein up to 200 g/kg; above this concentration they remained almost constant when feeding was ad libitum. 4. Similar responses were found with equalized feeding except that a significant reduction in protein synthesis was found when dietary protein was increased from 200 to 400 g/kg diet. 5. Less sensitive and almost parallel changes in protein degradation rates were found. 6. It was concluded that adaptation to varied dietary protein intake occurred primarily through changes in protein synthesis, accompanied by parallel alterations in protein degradation in the whole body.