Phosphate fixation by bentonite

Introduction

The relative ability of soils, clay minerals, and hydrous oxides to fix phosphorus has been determined by a variety of methods. In order to study phosphate fixation, it is necessary to rigidly control such factors as concentration of phosphorus added, time of reaction, temperature, and pH.     

Diversity and vertical distribution of indigenous arbuscular mycorrhizal fungi under two soybean rotational systems

To evaluate the importance of arbuscular mycorrhizal fungi (AMF) to crop production, it is imperative to move beyond the plow layer to include the full soil profile impacted by plant roots. To illustrate this, we investigated the vertical distribution of AMF biomass and community structure within the top 100 cm of soil in soybean (Glycine max (L.) Merr., cv: Enrei) rotational systems cropped to wheat (Triticuma estivum L. cv: Bandowase) or left fallow using fatty acid methyl ester (FAME) biomarkers and molecular analysis, respectively. AMF biomass, as measured by concentration of C16:1cis11, declined during fallow and with increasing soil depth. Greater than 50 % of the stored AMF biomass was found at depths below 35 cm. Phylogenetic analysis revealed 16 AMF phylotypes, including nine Glomus, two Gigaspora, two Scutellospora, and one each of Diversispora, Paraglomus, and an unknown glomeromycete, at different sampling depths in this study. Cluster analysis based on the number and abundance of each AMF phylotype formed two distinct clusters separating wheat from fallow rotations. There was no distinct relationship with soil depth beyond clustering AMF communities above and below 20 cm under wheat. Redundancy analysis (RDA) and hierarchical cluster analysis demonstrated that AMF communities by soil depth within each rotation were not significantly different. However, AMF communities were clearly influenced by crop rotation, where the distribution of specific AMF phylotypes responded to the presence of the wheat crop.     

Fructokinase,Fructans, Intestinal Permeability,and Metabolic Syndrome: An Equine Connection?

Fructose is a simple sugar present in honey and fruits, but can also exist as a polymer (fructans) in pasture grasses. Mammals are unable to metabolize fructans, but certain gram-positive bacteria contain fructanases and can convert fructans to fructose in the gut. Recent studies suggest that fructose generated from bacteria or directly obtained from the diet can induce both increased intestinal permeability and features of metabolic syndrome, especially the development of insulin resistance. The development of insulin resistance is driven in part by the metabolism of fructose by fructokinase C in the liver, which results in oxidative stress in the hepatocyte. Similarly, the metabolism of fructose in the small bowel by intestinal fructokinase may lead to increased intestinal permeability and endotoxemia. Although speculative, these observations raise the possibility that the mechanism by which fructans induce laminitis could involve intestinal and hepatic fructokinase. Further studies are indicated to determine the role of fructanases, fructose, and fructokinase in equine metabolic syndrome and laminitis.     

孟加拉国Bhanugach西部保育林用地类型变化(英文)

应用遥感和地理信息系统调查了孟加拉国Sylhet林业分局所辖的Bhanugach西部保育林从1988年到2006年间用地类型的变化。应用了监督和非监督两种方法,用全球定位系统搜集了地面控制点。地理信息系统软件制成地图。结果表明,植被覆盖从1988年的1826hm2大幅地降低到1996年的1714.85hm2,随着协同管理措施的实施,植被覆盖自1996年后逐年增长到2006年的1847.83hm2。在没有其他类型的用地转变成裸地的情况下,裸地变化与植被覆盖间成反比。18年间水体面积从1988年的307.67hm2增加到1996年379.53hm2,96-97年间略有下降,1997年以后直到2006年基本保持不变。本文还提出了将遥感技术和地理信息系统应用于用地类型变化及地理信息系统数据库创建的一些建议。     

No abomasal curd formation in pre-ruminant calves after ingestion of a clotting milk replacer

The aim of this study was to ultrasonographically evaluate curd formation in 29 pre-ruminant calves that were fed a clotting milk replacer. Abomasal curd was absent in 8/29 calves at 2 h after feeding. In these eight calves, abomasal contents were observed as an anechoic image with small echogenic spots (five calves), or as an echogenic image with an unclear outline (three calves), but there was no echogenic image with a clear outline corresponding to curd that was visualised in the other 21 calves. The curd was not observed until 7 h after feeding in the eight calves. Our analysis also indicated that the absence of curd formation in the pre-ruminant calves did not have a significant impact on the appearance, appetite and vigour of pre-ruminant calves or on their blood parameters, including serum triglyceride, blood urea nitrogen and glucose concentrations. The study provided the first evidence that the abomasum of some calves does not form curd despite ingestion of a clotting milk replacer.     

Optimal sample size for composite sampling with subsampling, when estimating the proportion of pecky rice grains in a field

The proportion of pecky rice grains has been estimated empirically using composite sampling with subsampling. The procedure can be summarized as follows: (1) A fixed number of rice plants, n ₁, are drawn at random in the paddy field; (2) all of the rice grains in the collected rice plants are mixed well to form a composite; (3) a portion of the grains, n ₂, is drawn at random from the composite; and (4) the collected grains are examined by eye to estimate the proportion of pecky rice grains. We propose a method for determining the optimal sample size in estimating the proportion of defective items by this type of composite sampling with subsampling. Spatial heterogeneity in the proportion of defective items is included in the estimation. We use Taylor’s power law to describe the density-dependent change of spatial heterogeneity. In controlling the precision of the estimate, we use the relative precision, D, which is defined by the coefficient of variation of the estimated proportion. We propose a rejection procedure in which the product is rejected if the estimate of proportion with D=0.25 is larger than a predetermined tolerable threshold of proportion. We also consider another control criterion in which the consumer’s risk, \, is controlled by a zero-tolerance method. Finally, we examine the relationship between the two control criteria.     

Studies on the properties of organic matter in buried humic horizon derived from volcanic ash

Abstract

Humic acids were extracted from the surface horizon Yu 1 and buried humic horizons (Yu 2, 800-864 AD; Yu 4, ca. 4,000 years B.P.; Yu 6, 7,000 years B.P.; Yu 7, ca. 10,000 years B.P.). The humic acids were filtered with ultramembranes with 20, 10, 5, 1 or 0.1 × 10' M.W. in this order and separated into five fractions; (>20), (20-10), (10-5), (5-1) and (1-0.1) × 10⁴ M.W. fractions. The elementary composition, functional groups, optical properties, and hydrolyzable total- and sugar-carbon contents of each humic acid fraction were determined, and the changes in properties of the humic acid with age after burial were discussed.

In horizons Yu 1 to Yu 6, the patterns of M.W. distribution of the >20 × 10⁴ to (1- 0.1) × 10⁴ fractions were rather similar. In contrast, Yu 7 was characterized by the predominance of (1-0.1) x 10' M.W. fraction and the presence of a small amount of <0.1 × 10⁴ M.W. fraction.

The chemical properties of humic acid (HA) fractions of each humic horizon and their changes with age after burial were as folIows:

1) Elementary composition of HA fractions of each humic horizon was rather similar to each other. The C% and C/N ratio increased, and the H%, N% and H/C ratio decreased in all HA fractions with age.

2) Total acidity and carboxyl contents of HA fractions of Yu 1 were higher in the lower M.W. fractions. These values increased with age up to Yu 4 or Yu 6 horizons, then decreased in the Yu 6 or Yu 7 horizon. The contents of carbonyl groups in all the HA fractions which were very low in Yu 1, showed a wide range of variations in Yu 2, intermediate values from Yu 4 to Yu 6 horizons then decreased in the HA fractions of Yu 7, except for the (>20) fraction.

3) The degree of humification of the HA fractions of Yu 1 judging from the RF and \sDlogK values, tended to be higher in higher M.W. fractions, and increased in all the HA fractions with age after burial.

4) Hydrolyzable total- and sugar-carbon contents were high in the HA fractions of Yu 1 and decreased with age.

5) Changes of elementary composition, degree of humification and hydrolyzable total- and sugar-carbon contents were conspicuous from the Yu 1 to Yu 2 horizons, and less significant afterwards.

6) The 0%, C/O ratio and phenolic OH content did not show any consistent change with age after burial.     

A latex agglutination test for the detection of Echinococcus multilocularis coproantigen in the definitive hosts

A latex agglutination test for detecting Echinococcus multilocularis coproantigen in definitive hosts was developed using latex beads sensitized with EmA9 monoclonal antibody raised against somatic antigens of adult E. multilocularis. A primary test (LA 1) was performed on 82 fecal samples of necropsied foxes, of which 46 were infected, and resulted in 61% sensitivity and 86% specificity. To increase the sensitivity, 4 ng/mL of excretory/secretory antigens of adult worms was added to the samples in a secondary test (LA 2), resulting in 91% sensitivity and 61% specificity. The positive predictive value of the LA 1 test and the negative predictive value of the LA 2 test were both 85%. The combination of the LA 1 and LA 2 tests is applicable and practical for use in situations that require quick diagnosis or screening based on the following interpretation: the samples that are positive in the LA 1 test are positive; the samples that are negative in the LA 2 test are negative; and the samples that are negative in the LA 1 test and positive in the LA 2 test are classified as suspicious.     

Similarity between Copper Resistance Genes from Pseudomonas syringae pv. actinidiae and P. syringae pv. tomato

Twenty-eight strains of Pseudomonas syringae pv. actinidiae isolated in 1984, 1987 and 1988 from kiwifruit orchards in Japan were tested for their resistance to copper sulfate. All strains isolated in 1984 were copper sensitive with a minimum inhibitory concentration (MIC) of cupric sulfate of 0.75 mM. However, some strains isolated in 1987 and 1988 were resistant, with the MIC ranging from 2.25 to 3.0 mM. All copper-resistant strains contained at least one of two plasmids, pPaCul (about 70.5 kb) or pPaCu2 (about 280 kb), or both. In a copper-resistant strain Pa429, the location of the copper-resistance gene(s) was examined by insertional inactivation with Tn5. The MIC of copper sulfate in the copper-sensitive mutant obtained by Tn5 tagging decreased from 2.75 to 0.75 mM. The 14.5 kb BamHI fragment, designated pPaCuB14, containing the same locus mutagenized with Tn5 was cloned from pPaCu1. However, pPaCuB14 did not confer copper resistance in the transformant of copper-sensitive strain Pa21R, suggesting that this clone did not contain a full set of copper-resistance gene(s). Then a cosmid library of pPaCu1 was constructed and six cosmid clones hybridized with pPaCuB14 were selected. One of the six cosmids, designated pPaCuC1, conferred a near wild-type level of copper resistance in the transformant of the copper-sensitive strain. pPaCuC1 had a homologous region that hybridized with all of the PCR-amplifled fragments of copA, copB, copR, and copS genes of P. syringae pv. tomato. DNA sequence analysis of the homologous region revealed the existence of four open reading frames (ORF A, B, R and S) oriented in the same direction. The predicted amino acid sequences of ORF A, B, R and S had 80, 70, 97 and 95% identity with CopA, B, R and S of P. syringae pv. tomato, respectively. Received 5 July 2001/ Accepted in revised form 27 September 2001     

Comparative observation of skeletal-dental abnormalities in wild, domestic, and laboratory rabbits

Dietary habits must be considered as one of the major potential factors resulting in acquired malocclusions in rabbits. Although the dentition of the wild rabbit and the domesticated laboratory rabbit are basically identical, dietary habits are noticeably different. Therefore, the prevalence of tooth problems between these lagomorph species were investigated anatomically and radiographically. Mean measurements of the skull and dental arches suggested that wild rabbits have slightly shorter and wider skulls and dental arches compared with domestic laboratory rabbits. Root elongation of incisors and check teeth, and periodontal disease were more frequently observed in domestic laboratory rabbits. Diagnostic radiographs from domestic pet rabbits showed relatively higher crowns, severe root elongation, and advanced periodontitis. These results do not provide definitive evidence that dietary habits cause malocclusions, however they suggest that diet is a major factor in the initiation of malocclusions in rabbits.