Increase in soil pH due to Ca-rich organic matter application causes suppression of the clubroot disease of crucifers

Clubroot disease of cruciferous plants caused by the soil-borne pathogen Plasmodiophora brassicae is difficult to control because the pathogen survives for a long time in soil as resting spores. Disease-suppressive and conducive soils were found during the long-term experiment on the impact of organic matter application to arable fields and have been studied to clarify the biotic and abiotic factors involved in the disease suppression. The fact that a large amount of organic matter, 400 t ha⁻¹ yr⁻¹ farmyard manure (FYM) or 100 t ha⁻¹ yr⁻¹ food factory sludge compost (FSC), had been incorporated for more than 15 yr in the suppressive soils and these soils showed higher pH and Ca concentration than the disease conducive soil led us to hypothesize that an increase in soil pH due to the long-term incorporation of Ca-rich organic matter might be the primary cause of the disease suppression. We have designed a highly reproducible bioassay system to examine this hypothesis. The suppressive and conducive soils were mixed with the resting spores of P. brassicae at a rate of 10⁶ spore g⁻¹ soil, and Brassica campestris was grown in a growth chamber for 8 d. The number of root hair infections was assessed on a microscope. It was found that the incorporation of FYM and FSC at 2.5% (w/w) to the conducive soil suppressed the infection and that the finer particles (?5 mm) of FSC inhibited the infection and increased soil pH more effectively. Neutralization of the conducive soil by Ca(OH)₂, CaCO₃ and KOH suppressed the infection, but the effectiveness of KOH was less than those of Ca(OH)₂ and CaCO₃. Acidification of the suppressive soils by H₂SO₄, promoted the infection. The involvement of soil biota in the disease suppression was investigated using the sterilized (γ-ray irradiation) suppressive soils with respect to soil pH. The γ-ray irradiation promoted the infection at pH 5.5, but no infection was observed at pH 7.4 irrespective of the sterilization status. All these observations suggest that soil pH is a major factor in disease suppression by organic matter application and that Ca and soil biota play certain roles in the suppression under the influence of soil pH.     

Purification and characterization of phytase induced in tomato roots under phosphorus-deficient conditions

Phytase (myo-inositol hexakisphosphate phosphohydrolase; EC 3.1.3.8) was purified from roots of tomato plants grown under phosphorus-deficient conditions using five purification schemes. The phytase was successfully separated from the major acid phosphatase to an electrophoretic homogeneity. The native molecular weight of this enzyme was estimated to be about 164 kD by Bio-Gel P-200 gel filtration. The molecular weight of the subunit on SDS-PAGE was approximately 82 kD, indicating that the native form of the enzyme was a homodimer. The isoelectric point of tomato phytase was about 5.5. The enzyme exhibited a high affinity for phytic acid (K _m = 38 μM), and was strongly inhibited by phosphate, molybdate and fluoride. Among other characteristics of tomato phytase, the pH and temperature optima were 4.3 and 45°C, respectively. Tomato phytase contained a fairly high concentration of aspartic, glutamic acid and glycine residues.     

Isolation and characterization of a cDNA from Catharanthus roseus which is highly homologous with phosphate transporter

The PIT1 gene which is highly homologous with phosphate transporter was isolated from Catharanthus roseus and analyzed. The cBNA PIT1 contained an open reading frame of 542 amino acids and its sequence showed a 31, 30, and 34% identity with the phosphate transporter of Saccharomyces cerevisiae (PBO84), Neurospora crassa (PHO-5), and Glomus versiforme (GvPT), respectively. Furthermore, the cDNA PIT1 encoded a highly hydrophobic protein with 12 putative membrane-spanning regions and contained a conserved amino acid sequence reported in the human glucose transporter super-family* S. cerevisiae strain DpU (pho84 knockout strain) was unable to grow on low phosphate (55 μM) medium (LP medium). Expression of the PIT1 cDNA enabled DpU to grow on LP medium. Northern hybridization analysis revealed that the PIT1 gene was expressed in roots, stems, and young whole plant of C. roseus, but not in leaves.     

Functional Analysis of Lysosomes During Mouse Preimplantation Embryo Development

Lysosomes are acidic and highly dynamic organelles that are essential for macromolecule degradation and many other cellular functions. However, little is known about lysosomal function during early embryogenesis. Here, we found that the number of lysosomes increased after fertilization. Lysosomes were abundant during mouse preimplantation development until the morula stage, but their numbers decreased slightly in blastocysts. Consistently, the protein expression level of mature cathepsins B and D was high from the one-cell to morula stages but low in the blastocyst stage. One-cell embryos injected with siRNAs targeted to both lysosome-associated membrane protein 1 and 2 (LAMP1 and LAMP2) were developmentally arrested at the two-cell stage. Pharmacological inhibition of lysosomes also caused developmental retardation, resulting in accumulation of lipofuscin. Our findings highlight the functional changes in lysosomes in mouse preimplantation embryos.     

An efficient molecular technique for sexing tiger pufferfish (fugu) and the occurrence of sex reversal in a hatchery population

The tiger pufferfish (fugu) is one of the most important food fishes in East Asia. Since its testes are regarded as a delicacy, sex determination is economically relevant. Previous studies have identified a missense single-nucleotide polymorphism (SNP) in the Amhr2 (anti-Müllerian hormone receptor type II) gene as a strong candidate for a master sex-determining polymorphism. To distinguish genotypic sex efficiently, we developed a high-resolution melting (HRM) assay for this SNP site. By screening 396 fish from two independent crosses reared under controlled conditions, we observed perfect concordance between the SNP genotype and phenotypic sex. Thus, this method holds great potential for use in high-throughput sexing. When analyzing 293 progeny from a third cross reared under unknown conditions, we unexpectedly found that 25 % of phenotypic males exhibited female genotype. These results suggest that environmental factors such as rearing conditions could influence the sex-determination pathway in pufferfish. Alternatively, genetic modifiers might override the signals from Amhr2. This finding raises a concern regarding enhanced stock management of this species, because sex-reversed fish could compromise the sex ratio in subsequent generations. The HRM assay will also be useful for monitoring the degree of sex reversal before release.     

Pathology of cutaneous fowlpox with amyloidosis in layer hens inoculated with fowlpox vaccine

Cutaneous fowlpox occurring in vaccinated layer hens was investigated pathologically and microbiologically. Anorexia, decrease of egg production, increased mortality, yellow scabs on faces, and alopecia of feathered skins with yellow scabs were observed in affected hens. Histologically, proliferative and necrotic dermatitis with eosinophilic ring-shaped cytoplasmic inclusions (Bollinger bodies) and clumps of gram-positive cocci (Staphylococcus hyicus) were noted in the affected birds. Fowlpox lesions were primarily observed in the feathered skins. Proliferation of feather follicle epidermal cells, with cytoplasmic inclusions and degeneration of the feather, and bacterial clumps in the feather follicles were noted in the affected skins. Ultrastructurally, characteristic fowlpox viral particles were observed in the cytoplasmic inclusions of hyperplastic epidermal cells. Amyloid deposition was observed in the Disse space of the liver, splenic sinus, and lamina propria of the bronchiolar, bronchial, and tracheal areas. Amyloidosis could be one factor inducing the fowlpox infection in vaccinated chickens.     

Analysis of forest structural complexity using airborne LiDAR data and aerial photography in a mixed conifer–broadleaf forest in northern Japan

Determining forest structural complexity,i.e.,a measure of the number of different attributes of a forest and the relative abundance of each attribute,is important for forest management and conservation.In this study,we examined the structural complexity of mixed conifer–broadleaf forests by integrating multiple forest structural attributes derived from airborne Li DAR data and aerial photography.We sampled 76 plots from an unmanaged mixed conifer–broadleaf forest reserve in northern Japan.Plot-level metrics were computed for all plots using both field and remote sensing data to assess their ability to capture the vertical and horizontal variations of forest structure.A multivariate set of forest structural attributes that included three Li DAR metrics(95 th percentile canopy height,canopy density and surface area ratio) and one image metric(proportion of broadleaf cover),was used to classify forest structure into structural complexity classes.Our results revealed significant correlation between field and remote sensing metrics,indicating that these two sets of measurements captured similar patterns of structure in mixed conifer–broadleaf forests.Further,cluster analysis identified six forest structural complexity classes includingtwo low-complexity classes and four high-complexity classes that were distributed in different elevation ranges.In this study,we could reliably analyze the structural complexity of mixed conifer–broadleaf forests using a simple and easy to calculate set of forest structural attributes derived from airborne Li DAR data and high-resolution aerial photography.This study provides a good example of the use of airborne Li DAR data sets for wider purposes in forest ecology as well as in forest management.     

Fast‐to‐slow shift of muscle fiber‐type composition by dietary apple polyphenols in rats: Impact of the low‐dose supplementation

Our previous studies demonstrated that an 8‐week intake of 5% (w/w) apple polyphenol (APP) in the diet improves muscle endurance of young‐adult rats. In order to identify a lower limit of the dietary contribution of APP to the effect, the experiments were designed for lower‐dose supplementation (8‐week feeding of 0.5% APP in AIN‐93G diet) to 12‐week‐old male Sprague‐Dawley rats. Results clearly showed that the 0.5% APP diet significantly up‐regulates slower myosin‐heavy‐chain (MyHC) isoform ratios (IIx and IIa relative to total MyHC) and myoglobin expression in lower hind‐limb muscles examined (P < 0.05). There was a trend to increased fatigue resistance detected from measurements of relative isometric plantar‐flexion force torque generated by a stimulus train delivered to the tibial nerve (F(98, 1372) = 1.246, P = 0.0574). Importantly, there was no significant difference in the animal body‐phenotypes or locomotor activity shown as total moving distance in light and dark periods. Therefore, the present study encourages the notion that even low APP‐intake may increase the proportions of fatigue‐resistant myofibers, and has promise as a strategy for modifying performance in human sports and improving function in age‐related muscle atrophy.     

三种常用药物对黑鲷幼鱼的急性毒性试验

试验研究水产常用药物敌百虫、硫酸铜+硫酸亚铁合剂、高锰酸钾对黑鲷幼鱼的急性毒性。结果发现,黑鲷幼鱼对敌百虫24、48、96h的半数致死浓度分别为1.13、0.85、0.54mg/l,敌百虫对黑鲷幼鱼的安全浓度为0.14mg/l;黑鲷幼鱼对硫酸铜+硫酸亚铁合剂(5:2)24、48、96h的半数致死浓度分别为7.07、6.43、6.25mg/l,硫酸铜+硫酸亚铁合剂对黑鲷幼鱼的安全浓度为1.60mg/l;1mg/l和2mg/l的高锰酸钾在30min内对黑鲷幼鱼的行为等无明显影响。