Sensitivity and specificity of a commercial BSE kit for the detection of ovine scrapie

To examine the sensitivity of a commercially available bovine spongiform encephalopathy (BSE) kit (NippIBL) for the detection of ovine scrapie, 50 scrapie‐positive ovine samples from the UK, and 54 scrapie‐negative ovine samples from Japan were obtain and tested using this kit. The sensitivity and specificity of NippIBL for ovine samples were 96% and 100%, respectively. The detection limit of the abnormal isoform of prion protein (PrP^Sc) of NippIBL was examined using diluted scrapie‐positive samples. The sensitivity of NippIBL to ovine scrapie was 3–10 times superior to that of another commercial BSE diagnosis kit. Thus, the NippIBL kit proved more effective for the detection of ovine scrapie.     

Wide genetic variation in phenolic compound content of seed coats among black soybean cultivars

Black soybeans have been used as a food source and also in traditional medicine because their seed coats contain natural phenolic compounds such as proanthocyanidin and anthocyanin. The objective of this research is to reveal the genetic variation in the phenolic compound contents (PCCs) of seed coats in 227 black soybean cultivars, most of which were Japanese landraces and cultivars. Total phenolics were extracted from seed coats using an acidic acetone reagent and the proanthocyanidin content, monomeric anthocyanin content, total flavonoids content, total phenolics content, and radical scavenging activity were measured. The cultivars showed wide genetic variation in PCCs. Each of the contents was highly correlated with one another, and was closely associated with radical scavenging activity. PCCs were also moderately associated by flowering date but not associated by seed weight. Cultivars with purple flowers had a tendency to produce higher PCCs compared with cultivars with white flowers, suggesting that the W1 locus for flower color can affect phenolic compound composition and content. Our results suggest that developing black soybean cultivars with high functional phenolic compounds activity is feasible.     

The effects of various lignocelluloses and lignins on physiological responses of a lower termite, <Emphasis Type="Italic">Coptotermes formosanus</Emphasis>

We investigated the physiological responses of a lower termite, Coptotermes formosanus, fed on various lignocelluloses and purified lignins (milled-wood lignins, MWLs) from Japanese cedar (softwood), Japanese beech (hardwood), and rice (grass). Termite survival, body mass, and the changes of the symbiotic protists in the hindgut of workers were observed for 4 weeks. The survival, body mass and presence of both Pseudotrichonympha grassii and Holomastigotoides hartmanni in the hindgut of workers fed on rice lignocellulose at the 4th week of observation were significantly lower than those of the workers fed on Japanese cedar and Japanese beech lignocellulose samples, whereas there was no significant difference in Spirotrichonympha leidyi among all the diets. The three purified MWLs, regardless of their structural differences, did not show any significant differences for the termites’ survival or body mass or the survival of all the three protists. The three MWL diets resulted in significantly lower termite survival compared to starvation, although these diets showed no significant effects on body mass or the protist profiles. Overall, lignins are hardly utilized as a nutrient source by C. formosanus workers and are even rather detrimental to termites when fed on solely.     

Uptake and translocation of nitrogen in patumma (Curcuma alismatifolia) by leaves or root

An adequate supply of nitrogen (N) is important for patumma growth and flower quality. This study aimed to compare the uptake and translocation of N by foliar and root application. Fertilization with ¹⁵ nitrate (NO₃)-N via roots or leaves was carried out at four stages, at the 1st to 4th fully expanded leaf (FEL) stages, and the plants were sampled at each successive stage. The uptake and translocation of ¹⁵N from foliar or root applications showed relatively similar patterns at all stages. Although the N fertilizer utilization rate by roots was higher than that via leaves, the foliar application stimulated reproductive growth by earlier flowering. The N supplied at the 1st FEL and the 2nd FEL was utilized mainly in leaves, whereas supplying N at the 3rd and 4th FEL promoted flower quality. Fertilizer application method and stage of application influence the utilization rate and translocation of N to the sink organs.     

Molecular and Evolutionary Analysis of the Hd6 Photoperiod Sensitivity Gene Within Genus Oryza

Heading date determines rice’s adaptation to its area and cropping season. We analyzed the molecular evolution of the Hd6 quantitative trait locus for photoperiod sensitivity in a total of 20 cultivated varieties and wild rice species and found 74 polymorphic sites within its coding region (1,002 bp), of which five were nonsynonymous substitutions. Thus, natural mutations and modifications of the coding region of Hd6 within the genus Oryza have been suppressed during its evolution; this is supported by low Ka (≤0.003) and Ka/Ks (≤0.576) values between species, indicating purifying selection for a protein-coding gene. A nonsynonymous substitution detected in the japonica variety “Nipponbare” (a premature stop codon and nonfunctional allele) was found within only some local Japanese japonica varieties, which suggests that this point mutation happened recently, probably after the introduction of Chinese rice to Japan, and is likely involved in rice adaptation to high latitudes. Phylogenetic analysis and genome divergence using the entire Hd6 genomic region confirmed the current taxonomic sections of Oryza and supported the hypothesis of independent domestication of indica and japonica rice.     

An SNP caused loss of seed shattering during rice domestication

Loss of seed shattering was a key event in the domestication of major cereals. We revealed that the qSH1 gene, a major quantitative trait locus of seed shattering in rice, encodes a BEL1-type homeobox gene and demonstrated that a single-nucleotide polymorphism (SNP) in the 5' regulatory region of the qSH1 gene caused loss of seed shattering owing to the absence of abscission layer formation. Haplotype analysis and association analysis in various rice collections revealed that the SNP was highly associated with shattering among japonica subspecies of rice, implying that it was a target of artificial selection during rice domestication.     

Lime-nitrogen application reduces N2O emission from a vegetable field with imperfectly-drained sandy clay-loam soil

Abstract

We studied the effect of lime-nitrogen (calcium cyanamide, CaCN₂) application on the emission of nitrous oxide (N₂O) from a vegetable field with imperfectly-drained sandy clay-loam soil. Lime-nitrogen acts as both a pesticide and a fertilizer. During the decomposition of lime-nitrogen in the soil, dicyandiamide (DCD), a nitrification inhibitor, is formed, and as a result lime-nitrogen application may mitigate N₂O emission from the soil. The study design consisted of three different nitrogen-application treatments in field plots with a randomized block design. The nitrogen application treatments were: CF (chemical fertilizer), LN (all nitrogen fertilizer applied as lime-nitrogen), and CFD (chemical fertilizer containing DCD). Soil nitrification activity was lower in the LN and CFD plots than in the CF plots, and nitrification was inhibited for a longer period in the LN plots than in the CFD plots. In the LN plots, N₂O emission was lower than those of other treatments from 20 to 40 days after fertilization, a period when large peaks of N₂O emission were observed after rainfall in the CF and CFD plots. Cumulative N₂O emission over 63 days in the CF plots (mean ± standard deviation: 30.2 ± 14.4 mg N₂O m^?2) and CFD plots (24.3 ± 10.8 mg N₂O m^?2) was significantly higher than that in the LN plots (10.7 ± 1.2 mg N₂O m^?2; P < 0.05). Our results suggested that lime-nitrogen application decreased N₂O emission by inhibiting both nitrification and denitrification.     

Effect of CO2 enrichment on carbon and nitrogen interaction in wheat and soybean

Effect of CO₂ enrichment on the carbon-nitrogen balance in whole plant and the acclimation of photosynthesis was studied in wheat (spring wheat) and soybean (A62-1 [nodulated] and A62-2 [non-nodulated]) with a combination of two nitrogen application rates (0 g N land area m^-2 and 30 g N land area m^-2) and two temperature treatments (30/20°C (day/night) and 26/16°C). Results were as follows.

1. Carbon (dry matter)-nitrogen balance of whole plant throughout growth was remarkably different between wheat and soybean, as follows: 1) in wheat, the relationship between the amount of dry matter (DMt) and amount of nitrogen absorbed (Nt) in whole plant was expressed by an exponential regression, in which the regression coefficient was affected by only the nitrogen application rate, and not by CO₂ and temperature treatments, and 2) in soybean the DMt-Nt relationship was basically expressed by a linear regression, in which the regression coefficient was only slightly affected by the nitrogen treatment (at 0N, DMt-Nt balance finally converged to a linear regression). Thus, carbon-nitrogen interaction in wheat was strongly affected by the underground environment (nitrogen nutrition), but not by the above ground environment (CO₂ enrichment and temperature), while that in soybean was less affected by both under and above ground environments.

2. The photosynthetic response curve to CO₂ concentration in wheat and soybean was less affected by the CO₂ enrichment treatment, while that in wheat and soybean (A62-2) was affected by the nitrogen treatment, indicating that nitrogen nutrition is a more important factor for the regulation of photosynthesis regardless of the CO₂ enrichment.

3. Carbon isotope discrimination (..:1) in soybean was similar to that in wheat under ambient CO₂, while lower than that in wheat under CO₂ enrichment, suggesting that the carbon metabolism is considerably different between wheat and soybean under the CO₂ enrichment conditions.