A non-destructive approach for assessing decay in preservative treated wood

This study investigated the suitability of the non-destructive vibration-impulse excitation technique to assess the attack of preservative-treated wood in contact with the ground. Small stakes (10×5×100 mm³) of treated and untreated Scots pine sapwood were exposed to decay in laboratory-scale terrestrial ecosystems. Different soils were used to prove the influence of different types of wood destroying micro-organisms. Wood decay was monitored periodically for one year by determining mass losses and changes in dynamic modulus of elasticity. The results show a large variability in resistance against attacking fungi, depending on wood preservative and soil type. The non-destructive approach using the dynamic modulus of elasticity proved to be a good and sensitive tool for assessing the attack of stakes in laboratory soil testing.     

Production of Wild Buffalo (Bubalus arnee) Embryos by Interspecies Somatic Cell Nuclear Transfer Using Domestic Buffalo (Bubalus bubalis) Oocytes

The objective of this study was to explore the possibility of producing wild buffalo embryos by interspecies somatic cell nuclear transfer (iSCNT) through handmade cloning using wild buffalo somatic cells and domestic buffalo (Bubalus bubalis) oocytes. Somatic cells derived from the ear skin of wild buffalo were found to express vimentin but not keratin and cytokeratin‐18, indicating that they were of fibroblast origin. The population doubling time of skin fibroblasts from wild buffalo was significantly (p < 0.05) higher, and the cell proliferation rate was significantly (p < 0.05) lower compared with that of skin fibroblasts from domestic buffalo. Neither the cleavage (92.6 ± 2.0% vs 92.8 ± 2.0%) nor the blastocyst rate (42.4 ± 2.4% vs 38.7 ± 2.8%) was significantly different between the intraspecies cloned embryos produced using skin fibroblasts from domestic buffalo and interspecies cloned embryos produced using skin fibroblasts from wild buffalo. However, the total cell number (TCN) was significantly (p < 0.05) lower (192.0 ± 25.6 vs 345.7 ± 42.2), and the apoptotic index was significantly (p < 0.05) higher (15.1 ± 3.1 vs 8.0 ± 1.4) for interspecies than that for intraspecies cloned embryos. Following vitrification in open‐pulled straws (OPS) and warming, although the cryosurvival rate of both types of cloned embryos, as indicated by their re‐expansion rate, was not significantly different (34.8 ± 1.5% vs 47.8 ± 7.8), the apoptotic index was significantly (p < 0.05) higher for vitrified–warmed interspecies than that for corresponding intraspecies cloned embryos (48.9 ± 7.2 vs 23.9 ± 2.8). The global level of H3K18ac was significantly (p < 0.05) lower in interspecies cloned embryos than that in intraspecies cloned embryos. The expression level of HDAC1, DNMT3a and CASPASE3 was significantly (p < 0.05) higher, that of P53 was significantly (p < 0.05) lower in interspecies than in intraspecies embryos, whereas that of DNMT1 was similar between the two types of embryos. In conclusion, these results demonstrate that wild buffalo embryos can be produced by iSCNT.     

Mating and dispersal behaviour of Scirpophaga incertulas and Chilo suppressalis (Lepidoptera; Pyralidae) in relation to resistance management for rice transformed with Bacillus thuringiensis toxin genes

Information on the mating and dispersal behaviour of the rice stem borers Scirpophaga incertulas and Chilo suppressalis is necessary for the design of resistance management strategies for rice varieties genetically engineered with toxin genes from Bacillus thuringiensis (Bt). We investigated whether S. incertulas and C. suppressalis move from the site of adult eclosion before mating to determine the likelihood that random mating will occur between adults eclosing in fields of Bt rice and refuge fields of non-Bt rice. Observations were made under laboratory, screenhouse and field conditions. Almost all S. incertulas males and females flew out of sight after cuticle expansion and hardening, as did most C. suppressalis. Approximately 15% of C. suppressalis females called and mated within 3?m of the site of eclosion, and approximately 5% of C. suppressalis males mated within 5?m of the site of eclosion. These results suggest that random mating is likely to occur between S. incertulas eclosing in Bt rice fields and nearby refuge fields. Although a small proportion of C. suppressalis did not move far before mating, random mating of moths from Bt and nearby refuge fields is also likely to occur in this species if Bt-resistant moths are rare.     

Enhancement of cation diffusion rates across the 410-kilometer discontinuity in Earth's mantle

Rates of cation diffusion (magnesium, iron, and nickel) have been determined in olivine and its high-pressure polymorph, wadsleyite, at 9 to 15 gigapascals and 1100 degrees to 1400 degreesC for compositions that are relevant to Earth's mantle. Diffusion in olivine becomes strongly dependent on composition at high pressure. In wadsleyite, diffusion is one to two orders of magnitude faster than in olivine, depending on temperature. Homogenization of mantle heterogeneities (chemical mixing) and mineral transformations involving a magnesium-iron exchange will therefore occur considerably faster in the transition zone than at depths of less than 410 kilometers.     

天津市种植业现代化的对策研究

经济体制改革以来,天津农业、农村经济社会有了长足发展,提前完成了党中央提出的第二步战略发展目标,基本实现小康,为农业、农村现代化建设提供了良好的经济社会环境、物质基础和物质技术条件。为落实党的十五届三中全会 决定 和江泽民同志关于 沿海发达地区要率先基本实现农业现代化"的指示精神,本文仅就天津种植业现代化的对策谈点粗浅看法。基本思路是:在加大政府组织推动和扶持力度的同时,采取 一个稳定、二个加大、三个完善、四个提高"的综合对策措施,整体推进种植业现代化进程     

Functional human corneal equivalents constructed from cell lines

Human corneal equivalents comprising the three main layers of the cornea (epithelium, stroma, and endothelium) were constructed. Each cellular layer was fabricated from immortalized human corneal cells that were screened for use on the basis of morphological, biochemical, and electrophysiological similarity to their natural counterparts. The resulting corneal equivalents mimicked human corneas in key physical and physiological functions, including morphology, biochemical marker expression, transparency, ion and fluid transport, and gene expression. Morphological and functional equivalents to human corneas that can be produced in vitro have immediate applications in toxicity and drug efficacy testing, and form the basis for future development of implantable tissues.     

Cryopreservation of Zona‐Free Cloned Buffalo (Bubalus Bubalis) Embryos: Slow Freezing vs Open‐Pulled Straw Vitrification

This study was carried out to compare the post‐thaw cryosurvival rate and the level of apoptosis in vitro produced zona‐free cloned buffalo blastocysts subjected to slow freezing or vitrification in open‐pulled straws (OPS). Zona‐free cloned embryos produced by handmade cloning were divided into two groups and were cryopreserved either by slow freezing or by vitrification in OPS. Cryosurvival of blastocysts was determined by their re‐expansion rate following post‐thaw culture for 22–24 h. The post‐thaw re‐expansion rate was significantly (p < 0.05) higher following vitrification in OPS (71.2 ± 2.3%) compared with that after slow freezing (41.6 ± 4.8%). For examining embryo quality, the level of apoptosis in day 8 frozen‐thawed blastocysts was determined by TUNEL staining. The total cell number was not significantly different among the control non‐cryopreserved cloned embryos (422.6 ± 67.8) and those cryopreserved by slow freezing (376.4 ± 29.3) or vitrification in OPS (422.8 ± 36.2). However, the apoptotic index, which was similar for embryos subjected to slow freezing (14.8 ± 2.0) or OPS vitrification (13.3 ± 1.8), was significantly (p < 0.05) higher than that for the control non‐cryopreserved cloned embryos (3.4 ± 0.6). In conclusion, the results of this study demonstrate that vitrification in OPS is better than slow freezing for the cryopreservation of zona‐free cloned buffalo blastocysts because it offers a much higher cryosurvival rate.     

Zinc from oyster tissue as causative factor in mouse deaths in official bioassay for paralytic shellfish poison

Toxicity (extreme weakness, body temperature drop, cyanosis, some slow deaths) in test mice, upon intraperitoneal injection of standard-method paralytic shellfish poison (PSP) extracts of some PSP-free oysters, is consistent with the relatively high levels of zinc in these extracts. As a rough guideline, the threshold for a toxic response corresponds to a drained tissue zinc level of over 900 micrograms/g. The identification of zinc as the substance responsible has been supported by inducing toxicity in control extracts by spiking with nontoxic levels of zinc, and by eliminating toxicity from toxic extracts by chemical removal (precipitation, ion exchange) of metals.