Biosynthesis and composition of histones in Novikoff hepatoma nuclei and nucleoli

Histones were prepared from isolated nuclei and nucleoli of the Novikoff ascitic hepatoma at several time points after the injection of L-lysine uniformly labeled with C(14) into tumor-bearing rats. Amino acid analysis and starch-gel electrophoresis failed to reveal any differences between the nuclear and nucleolar histones, although both fractions were more acidic in composition than calf thymus histones. However, the nucleolar histones were a metabolically distinct fraction, and their rate of synthesis was approximately twice that of the total nuclear histones.     

Assessment of hygroscopic conditioning performance of interior decorative materials IV: Sorption characteristics of wood under high relative humidity condition

The equilibrium moisture content (EMC) of six wood species under desorption conditions of 20°C and 100% 0% relative humidity (RH), and the rate of adsorption at various depths of three wood species blocks under 98% RH at 22.5°C were studied. There were no significant differences among the EMC values for these six wood species over the RH range 40% 0%, but there were highly significant differences over the RH range 100% 50% at constant 20°C. The amount of moisture absorbed in the wood decreased curvilinearly with the increase of depth in the specimens as sorption time increased, and their relation could be represented by a semilogarithmic equation. Time-dependent adsorption behavior at various depths of the wood specimens could be represented by an exponential equation as a function of the product of the difference between moisture contents at equilibrium and initial conditions and the term (1 – e^–t/). The value of of various wood species was found to increase linearly with the increased depth of the specimen and showed the following trend: hard maple (Acer sp.) > China fir (Cunninghamia lanceolata) > Japanese cedar (Cryptomeria japonica D. Don).Part of this report was presented at the 47th annual meeting of the Japan Wood Research Society, Kochi, April 1997.     

Characterization of soil heavy metal pools in paddy fields in Taiwan: chemical extraction and solid-solution partitioning

Background, aim, and scope  Ongoing industrialization has resulted in an accumulation of metals like Cd, Cu, Cr, Ni, Zn, and Pb in paddy fields across Southeast Asia. Risks of metals in soils depend on soil properties and the availability of metals in soil. At present, however, limited information is available on how to measure or predict the directly available fraction of metals in paddy soils. Here, the distribution of Cd, Cu, Cr, Ni, Zn, and Pb in 19 paddy fields among the total, reactive, and directly available pools was measured using recently developed concepts for aerated soils. Solid-solution partitioning models have been derived to predict the directly available metal pool. Such models are proven to be useful for risk assessment and to derive soil quality standards for aerated soils. Material and methods  Soil samples (0–25 cm) were taken from 19 paddy fields from five different communities in Taiwan in 2005 and 2006. Each field was subdivided into 60 to 108 plots resulting in a database of approximately 3,200 individual soil samples. Total (Aqua Regia (AR)), reactive (0.43 M HNO₃, 0.1 M HCl, and 0.05 M EDTA), and directly available metal pools (0.01 M CaCl₂) were determined. Solid-solution partitioning models were derived by multiple linear regressions using an extended Freundlich equation using the reactive metal pool, pH, and the cation exchange capacity (CEC). The influence of Zn on metal partitioning and differences between both sampling events (May/November) were evaluated. Results  Total metals contents range from background levels to levels in excess of current soil quality standards for arable land. Between 3% (Cr) and 30% (Cd) of all samples exceed present soil quality standards based on extraction with AR. Total metal levels decreased with an increasing distance from the irrigation water inlet. The reactive metal pool relative to the total metal content is increased in the order Cr << Ni = Zn < Pb < Cu < Cd and ranged from less than 10% for Cr to more than 70% for Cd. Despite frequent redox cycles, Cd, Pb, and Cu appear to remain rather reactive. The methods to determine the reactive metal pool in soils yield comparable results, although the 0.43 M HNO₃ extraction is slightly stronger than HCl and EDTA. The close correlation between these methods suggests that they release similar fractions from soils, probably those reversibly sorbed to soil organic matter (SOM) and clay. The average directly available pool ranged from less than 1% for Cu, Pb, and Cr to 10% for Ni, Zn, and Cd when compared to the reactive metal pool. For Cd, Ni, Zn, and to a lesser extent for Cu and Pb, solid-solution partitioning models were able to explain up to 93% (Cd) of the observed variation in the directly available metal pool. CaCl₂ extractable Zn increased the directly available pool for Ni, Cd, and Cu but not that of Pb and Cr. In the polluted soils, the directly available pool was higher in November compared to that in May. Differences in temperature, rainfall, and changes in soil properties such as pH are likely to contribute to the differences observed within the year. The solid-solution partitioning model failed to explain the variation in the directly available Cr pool, probably because Cr is present in precipitates rather than being adsorbed onto SOM and clay. Despite obvious differences in parent material, source of pollution, climate, and land use, solid-solution partitioning of Cd in paddy fields studied here was similar to that in soils from Belgium and the Netherlands. Discussion  To assess risks of metals in soils, both analytical procedures as well as models are needed. The three methods tested here to determine the reactive metal pool are highly correlated and either of these can be used. The directly available pool was predicted most accurately by the 0.43 M HNO₃ method. The similarity of metal partitioning in paddy soils compared to well-drained soils suggests that changing redox conditions in paddy fields have a limited effect on the geochemical behavior of metals like Cd, Ni, and Zn. Small but significant differences in the directly available metal pool during the year suggest that redox cycles as well as differences in rainfall and temperature affect the size of the directly available metal pool. The large observed spatial heterogeneity of contaminant levels requires ample attention in the setup of soil monitoring programs. Conclusions  The directly available pool (0.01 M CaCl₂) of Cd, Zn, and Ni in paddy fields can be described well by an extended Freundlich model. For Cu and Pb, more information on dissolved organic carbon is needed to obtain a more accurate estimate of the directly available pool. Recommendations and perspectives  Soil testing protocols and models used in risk assessment consider the availability of pollutants rather than the total metal content. Results from extensive testing indicate that approaches developed for nontropical regions can be applied in paddy fields as well for metals like Cd, Ni, and Zn. This study shows that the chemical behavior under drained conditions in paddy fields is comparable to that observed in soils across the European Union, which allows regions with large scale soil pollution including Taiwan to apply such concepts to derive meaningful experimental protocols and models to assess risks of metals in soils.     

Detection of gliadin in foods using a quartz crystal microbalance biosensor that incorporates gold nanoparticles

This work develops a label-free gliadin immunosensor that is based on changes in the frequency of a quartz crystal microbalance (QCM) chip. A higher sensitivity was obtained by applying 25 nm gold nanoparticles (AuNPs) to the surface of a bare QCM electrode. Subsequently, chicken anti-gliadin antibodies (IgY) were immobilized directly on the AuNP-modified surface by cross-linking amine groups in IgY with glutaraldehyde. Experimental results revealed that the change in frequency exhibited when 2 ppm gliadin was bound to the AuNP-modified electrode was 35 Hz (48%) greater than that of the bare gold electrode. The linear dynamic range in 60% ethanol was from 1 × 10(1) to 2 × 10(5) ppb gliadin, and the calculated limit of detection (LOD) was 8 ppb. The entire detection process was completed in 40 min and was highly repeatable. Additionally, the AuNP-modified QCM system generated results in the detection of gliadin in 10 commercial food products that were consistent with those obtained using an AOAC-approved gliadin kit. In conclusion, the QCM platform provides a potential alternative means of ensuring that people with wheat allergies and celiac patients have access to gliadin-free food.     

Assessment of ex-situ chemical washing of heavy metals from estuarine sediments around an industrial harbor in Southern Taiwan

Journal of Soils and Sediments - Harbor sediments normally accumulate the pollutants from municipal and industrial activities in the estuarine zone. This work aimed to characterize the...