Differences in the rDNA-bearing chromosome divide the Asian-Pacific and Atlantic species of Crassostrea (Bivalvia, Mollusca)

Karyotype and chromosomal location of the major ribosomal RNA genes (rDNA) were studied using fluorescence in situ hybridization (FISH) in five species of Crassostrea: three Asian-Pacific species (C. gigas, C. plicatula, and C. ariakensis) and two Atlantic species (C. virginica and C. rhizophorae). FISH probes were made by PCR amplification of the intergenic transcribed spacer between the 18S and 5.8S rRNA genes, and labeled with digoxigenin-11-dUTP. All five species had a haploid number of 10 chromosomes. The Atlantic species had 1-2 submetacentric chromosomes, while the three Pacific species had none. FISH with metaphase chromosomes detected a single telomeric locus for rDNA in all five species without any variation. In all three Pacific species, rDNA was located on the long arm of Chromosome 10 (10q)-the smallest chromosome. In the two Atlantic species, rDNA was located on the short arm of Chromosome 2 (2p)-the second longest chromosome. A review of other studies reveals the same distribution of NOR sites (putative rDNA loci) in three other species: on 10q in C. sikamea and C. angulata from the Pacific Ocean and on 2p in C. gasar from the western Atlantic. All data support the conclusion that differences in size and shape of the rDNA-bearing chromosome represent a major divide between Asian-Pacific and Atlantic species of Crassostrea. This finding suggests that chromosomal divergence can occur under seemingly conserved karyotypes and may play a role in reproductive isolation and speciation.

The preparation and stability of the inclusion complex of astaxanthin with beta-cyclodextrin

Inclusion complex of astaxanthin with beta-cyclodextrin was prepared. The water solubility of the inclusion complex was < 0.5 mg/ml, which is better than that of astaxanthin. Large aggregates were observed in the aqueous solution of the inclusion complex. Furthermore, the stability of the inclusion complex against temperature and light was greatly enhanced compared to that of astaxanthin. (c) 2006 Elsevier Ltd. All rights reserved.

敏捷制造策略原理及关键技术

本文研究了敏捷制造策略的基本原理和关键技术.敏捷制造策略被认为是全面提高企业竞争能力的21世纪的制造策略,敏捷制造策略是在CIMS和并行工程的基础上,更大范围内企业之间的集成.其研究与发展对未来的企业文化、先进制造技术和世界市场竞争格局变化将具有主导作用。

鄂尔多斯盆地三叠系延长组特低渗透储层分类评价

On the basis of the character of sedimentation and reservoir researching as well as diagenesis, using conventional and update testing measures, classificati-on and evaluation of the tesla low permeability reservoir in Ordos Basin is pr-esented. From Chang 8 to Chang 4+5 oil formations, four facies developed, includi-ng alluvial fan facies, delta facies, lake facies as well as density current. They were controlled by the northeastern, the southwest, the southern and the northwestern provenances. Distributary channel underwater and mouth bar of delta fr-ont are the main reservoirs. Detrital component has the different character in s-outh and in north. Sedimentary system in the northeastern part has more felds-par and less quartz. Sedimentary system in the southern part has more quartz and less feldspar. Because of sedimentation and diagenesis, the oil formations in region of interest formed the different features of pore array of the tesla l-ow permeability reservoirs. After researching, it is found that the active porosity and the main throat radius of Chang 4+5 are the highest, and they are positive correlation with per-meability. The exponent of flowing interval falls in the sortorder: Chang 8, Chang 4+5, Chang 6, Chang 7. Using clustering procedure and quaternion, the reservoirs of Yanchang for-mation in Ordos Basin are divided into five types. Ⅰ-good reservoirs and Ⅱ-appreciably good reservoirs occur in distributary channel and mouth bar. Ⅲ-poor reservoirs and Ⅳ-poorer reservoirs exist in natural levee, crevasse splay under-water and turbidity fan. It is forecasted that the oil area in Ⅰ-good reservoirs is about 4336.68 square kilometers, and the oil area in Ⅱ-appreciably good reservoirs is 28013.28 square kilometers or so, and the oil area in Ⅲ-poor rese-rvoirs is 28538.05 square kilometers more or less.

贵州岩溶荒漠化成因及其防治

岩溶荒漠化是贵州岩溶地区的主要生态环境问题之一。对土地生产力的破坏作用巨大。它是碳酸盐岩的侵蚀过程与人类活动共同作用的结果。分析了贵州碳酸盐岩区域侵蚀的地质背景，认为岩溶地区的碳酸盐岩侵蚀及地貌和生态环境特点、被侵蚀土粒的物质输送规律构成了岩溶荒漠化的自然基础。指出碳酸盐岩的化学侵蚀并非风化成土过程，以及一般的土壤侵蚀指标不能代表岩溶地区土壤侵蚀的真实情况。还分析了岩溶荒漠化产生和发展过程中的不合理人为活动的主要表现形式及其产生根源。在此基础上本文提出了相应的综合防治措施。