Transformation of Platymonas (Tetraselmis) subcordiformis (Prasinophyceae, Chlorophyta) by agitation with glass beads

A transient transformation system for the unicellular marine green alga, Platymonas subcordiformis, was established in this study. We introduced the pEGFP-N1 vector into P. subcordiformis with a glass bead method. P. subcordiformis was incubated in cell wall lytic enzymes (abalone acetone powder and cellulase solutions) to degrade the cell wall. The applicable conditions for production of viable protoplasts were pH 6.5, 25 degrees C, and 3 h of enzyme treatment. The protoplast yield was 61.2% when P. subcordiformis cells were added to the enzyme solution at a concentration of 10(7) cell ml(-1). The protoplasts were immediately transformed with the pEGFP-N1 vector using glass-bead method. The transformation frequency was about 10(-5), and there was no GFP activity observed in either the negative or the blank controls. This study indicated that GFP was a sensitively transgenic reporter for P. subcordiformis, and the method of cell wall enzymolysis followed by glass bead agitation was applicable for the transformation of P. subcordiformis.

A Scheduling Algorithm for Flexible Manufacturing Cell

In this paper, a new scheduling algorithm for the flexible manufacturing cell is presented, which is a discrete time control method with fixed length control period combining with event interruption. At the flow control level we determine simultaneously the production mix and the proportion of parts to be processed through each route. The simulation results for a hypothetical manufacturing cell are presented.

太湖表层沉积物中多磷酸盐检出的环境意义

在氮限制型富营养化湖泊中，沉积多磷酸盐（Poly-P）可以用来示踪营养盐磷的输入和湖泊的富营养化过程。太湖是一个典型的磷限制型富营养化湖泊，通过对太湖表层沉积物中总有机碳（TOC）、总氮（TN）、总磷（TP）、氢氧化钠可提取磷（NaOH-P）以及Poly-P 的提取分析，初步探讨了太湖营养盐磷输入的历史记录，并揭示了该湖Poly-P 的主要来源和保存机制。太湖Poly-P 的质量浓度较低，变化范围为0.004~0.065 mg·g-1。NaOH-P 占TP 组成的22%，是太湖沉积物总磷的主要组成部分之一。结果显示，在湖泊水体藻类生物量较大和NaOH-P 是沉积物TP 重要组成部分的磷限制型湖泊中，Poly-P 也是沉积物磷汇组成的一个重要部分，同时还是一个可以反映由人为磷输入增大导致湖泊富营养化程度加剧的敏感指标。

西南岩溶山区生态危机与反贫困的可持续发展文化反思

西南岩溶山区生态环境退化严重、贫困人口集中。文章探讨民族传统文化观念在岩溶山区经济活动中的作用,力图寻找岩溶山区生态恶化和贫困的深层次原因,指出岩溶山区存在的山地文化封闭性和典型的贫困文化特性及不合理的现代性转换导致区域生态恶化和可持续发展的滞后。岩溶山区应通过生态恢复模式示范建设、开展参与式社区资源管理、改善居民聚居点环境来实现文化创新和文化整合,实现传统性与现代性的深层次互动与接纳,拓宽现代性生长的内在精神空间,变外源性的“输血”机制为内源性的“造血”机制,从而使岩溶山区实现可持续发展。

Characteristic infrared spectroscopic patterns in the protein bands of human breast cancer tissue

Infrared (IR) spectra of normal, hyperplasia, fibroadenoma and carcinoma tissues of human breast obtained from 96 patients have been determined and analyzed statistically. Several spectral differences were detected in the frequency regions of N-H stretching, amide I, II and III bands: (1) the bands in the region 3000-3600cm-1 shifted to lower frequencies for the carcinomatous tissue; (2) the A(3300)/A(3075) absorbance ratio was significantly higher for the fibroadenoma than for the other types of tissues; (3) the frequency of the a-helix amide I band decreased for the malignant tissue, while the corresponding beta -sheet amide I band frequency increased; (4) the A(1657)/A(1635) and A(1553)/A(1540) absorbance ratios were the highest for fibroadenoma and carcinoma tissues; (5) the A(1680)/A(1657) absorbance ratio decreased significantly in the order of normal > hyperplasia > fibroadenoma > carcinoma; (6) the A(1651)/A(1545) absorbance ratio increased slightly for the fibroadenoma and the carcinoma tissues; (7) the bands at 1204 and 1278 cm(-1), assigned to the vibrational modes of the collagen, did not appear in the original spectra as resolved peaks and were distinctly stronger in the deconvoluted spectra of the carcinoma tissue and (8) the A(1657)/A(1204) and A(1657)/A(1278) absorbance ratios, both yielding information on the relative content of collagen, increased in the order of normal < hyperplasia < carcinoma < fibroadenoma. The said differences imply that the information is useful for the diagnosis of breast cancer and malignant breast abnormalities, and may serve as a basis for further studies on conformational changes in tissue proteins during carcinogenesis. (C) 2001 Elsevier Science B.V. All rights reserved.