Effect of soil exchangeable potassium content on cesium absorption and partitioning in buckwheat grown in a radioactive cesium-contaminated field

The effect of soil exchangeable (plant-available) potassium (ExK) content on cesium (Cs) absorption and translocation in buckwheat was evaluated in a field contaminated with radioactive Cs (¹³⁴Cs and ¹³⁷Cs, RCs) in 2013. The RCs concentration in buckwheat was significantly positively correlated with the naturally occurring stable Cs (¹³³Cs, SCs) concentration, and was lower at higher soil ExK content. The RCs and SCs were actively absorbed by buckwheat until the flowering stage. The soil ExK content was significantly negatively correlated with soil exchangeable RCs and SCs (ExRCs and ExSCs) concentrations. Greater RCs and SCs absorption by buckwheat in soils with low ExK contents was mainly due to higher soil ExRCs and ExSCs concentrations. Reproductive organs showed the largest differences in SCs concentration between low-ExK and high-ExK plots. The root–shoot and shoot–reproductive organs translocations of SCs markedly decreased with increasing soil ExK content. In the root–shoot and shoot–reproductive organs translocations, the discrimination of SCs and K decreased with decreasing soil ExK content. Our main findings were as follows: (1) because RCs are mainly taken up at the earlier growth stage, potassium should be applied as a basal fertilizer to decrease the RCs concentration in buckwheat; (2) lower soil ExK content led to higher soil ExRCs concentrations, resulting in greater RCs absorption by buckwheat; (3) the high Cs absorption and translocation and weaker discrimination between Cs and K in low ExK content soil may be due to the expression of K transporter(s) with weak discrimination between Cs and K.     

利用食盐替代物柠檬酸钠制作日本方头鱼盐干品的品质

近年来,随着全球减盐行动的推进,人们对低盐饮食的健康需求日益增长,具备良好风味和外观的低钠盐食品已成为当前的研究热点之一.为适应消费者对健康饮食的需求,本研究利用柠檬酸钠作为食盐替代物制作盐干品,对其品质进行了调查研究.本研究以日本方头鱼为原料,用9％(W/V,质量浓度)食盐(对照组)和柠檬酸钠(实验组)浸渍后风干,制...     

Serological diagnosis of enzootic pneumonia of swine by a double-sandwich enzyme-linked immunosorbent assay using a monoclonal antibody and recombinant antigen (P46) of Mycoplasma hyopneumoniae

To facilitate the control of enzootic pneumonia (EP) of swine caused by Mycoplasma hyopneumoniae, the complement fixation (CF) test has been used for the detection of M. hyopneumoniae antibodies. However, the CF test is a cumbersome and time-consuming technique and cross-reactivity are major drawbacks associated with this method. To circumvent these drawbacks, we have developed a double-sandwich enzyme-linked immunosorbent assay (ELISA), consisting of purified monoclonal antibody (Mab) against the 46 kDa surface antigen (P46) of M. hyopneumoniae and recombinant P46 protein expressed in Escherichia coli, for the detection of antibodies to M. hyopneumoniae in serum samples from pigs experimentally inoculated with M. hyopneumoniae and from naturally infected pigs, and compared the practical usefulness of ELISA using the CF test. In experimentally inoculated pigs, the CF and ELISA antibodies were detected at almost the same time, and a good correlation was demonstrated between the CF test and the ELISA. In a survey conducted on field samples, the seropositivity by ELISA in pigs of age 2-6 months was increased. At the time of slaughter, approximately 80% of the animals were seropositive for ELISA. However, a gradual decrease in the prevalence of ELISA positive samples was observed in sows with increasing parity. No correlation was seen between the results obtained with the two methods in the clinical samples. The CF test appears to have limited value for the diagnosis of EP in conventional herds because nonspecific reactions were frequently observed. Therefore, this ELISA is a useful alternative to the CF test currently used for the diagnosis of EP.     

The effect of feed regimen on chewing time, digesta passage rate and particle size distribution in Holstein non-lactating cows fed pasture ad libitum

The objective of this study was to evaluate the effect of feeding regimen on chewing activity and ruminal passage of digesta in non-lactating cows fed pasture ad libitum. Six ruminally fistulated Holstein dry cows (mean ± SD; parity = 3.7 ± 0.5, length of pregnancy = 28 ± 2 W, BW = 692 ± 75 kg) were assigned randomly to two dietary treatments using a crossover design; three cows were rotationally grazed pasture (treatment G) and the other was fed harvested pasture ad libitum in confinement (treatment C). Passage of digesta was measured by fecal marker excretion using Co-EDTA and Dysprosium (Dy) labeled grass as fluid phase maker or solid phase marker, respectively. Particle size distribution of ruminal digesta and feces was measured by wet sieving method. No significant difference in dry matter intake (DMI) between treatments was observed. Eating time in treatment G (517 min/day or 38.6 min/kg DMI) was longer treatment C (384 min/day or 31.0 min/kg DM). Chewing time per DMI was similar in both treatments (70.0 vs. 66.1 min/kg DMI). Ruminal liquid outflow rate and rumen volume of cows in treatment G were significant higher and lower than treatment C (9.9 vs. 12.2%/h and 111.0 vs. 79.9 L, respectively). The mean retention time in small particle pool to be able to pass through the reticulo-omasum orifice (CMRT₂) in cows of treatment C was longer (P < 0.05) than that for treatment G.. Logarithmic particle distribution and mean particle size of ruminal digesta at 24 h after feeding and feces particles had no significance between treatments. These results indicated that ingestive behavior of dry cow affected on eating time and ruminal volume, and it might have caused the higher ruminal liquid and particulate passage rate in treatment G compare to treatment C, with minimal effect on the particle size of digesta to pass from the rumen.     

High chromosomal variability of mandarins (Citrus spp.) revealed by CMA banding

Fluorochrome staining with chromomycin A₃(CMA) was used to characterize and compare the CMA banding patterns of chromosomes in 17 accessions of mandarins (Citrus spp.). All accessions had 2n = 18 chromosomes. These chromosomes were classified into six types based on the number and position of CMA positive bands; A: two telomeric and one proximal band, B: one telomeric and one proximal band, C: two telomeric bands, D: one telomeric band, E: without bands, F: one proximal band. Each accession possessed two to five types of chromosomes, and showed unique CMA banding patterns. Type D and E chromosomes were predominant in all accessions. Their numbers were generally higher in Chinese and Indian mandarins. Type F chromosome was present only in some mandarins originating in Japan, which could thus be distinguished from mandarins originating in other areas. This study is the first report of type F chromosome in citrus. The Vietnamese mandarins we studied were the only one shaving type A, B, C, D and E chromosomes. This revised version was published online in July 2006 with corrections to the Cover Date.     

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.     

Propagation of a magnetic domain wall in a submicrometer magnetic wire

The motion of a magnetic domain wall in a submicrometer magnetic wire was detected by use of the giant magnetoresistance effect. Magnetization reversal in a submicrometer magnetic wire takes place by the propagation of a magnetic domain wall, which can be treated as a "particle." The propagation velocity of the magnetic domain wall was determined as a function of the applied magnetic field.     

Genetic identification and morphology of naturally spawned eggs of the Japanese eel Anguilla japonica collected in the western North Pacific

Eggs of the Japanese eel Anguilla japonica collected in the western North Pacific were identified by onboard species-specific polymerase chain reaction (PCR) and DNA nucleotide sequencing after the cruise. Fish eggs of various species were collected by large plankton net tows at 12 stations along the southern part of the West Mariana Ridge on 19–25 May 2009. A total of 43 fish eggs were distinguished morphologically as possibly being of A. japonica. Thirty-one of those were analyzed by PCR, which included 15 eggs collected at 12°50–55′N, 141°15–20′E (in 5 tows) that showed positive results. The 16S ribosomal RNA (rRNA) gene sequences of eggs determined after the cruise indicated that 31 A. japonica eggs had been collected. The remaining eggs were of mesopelagic eel species (Serrivomeridae and Derichthyidae), or unidentified species. The morphological characteristics of the A. japonica eggs were consistent with those of artificially spawned eggs, except they had a slightly larger diameter. The egg diameter range did not overlap with those of mesopelagic eels of the Serrivomeridae, which often spawn in the same area as A. japonica. These results suggest that egg diameter and embryo shape can be used to morphologically identify naturally spawned A. japonica eggs.