神农架拐棍竹林的初步研究

拐棍竹(Fargesia spathacea Franch.)是中国特有分布种类,主要分布川、滇、陕、甘等省。是极有开发价值的植物资源,又是大熊猫取食主要竹种之一。本文研究了神农架拐棍竹林的生态生物学特点,客观地估算了其蕴藏量,进行了营养成分分析。现报道如下:     

Transformation of trichloroethylene by sulfate-reducing cultures enriched from a contaminated subsurface soil

Summary Trichloroethylene (TCE) was reductively dechlorinated to cis-1,2-dichloroethylene (cDCE) by sulfate-reducing cultures enriched from a contaminated subsurface soil. The highest observed transformation rate of TCE was 213 mol l^–1 per day at 35° C. The predominant biotransformation product was cDCE. However, further dechlorination of cDCE was not observed in most of the cultures. Methane production was insignificant and active sulfate reduction was achieved by maintaining excess sulfate. A comparison of sodium sulfide and sodium dithionite for their effect on the transformation of TCE revealed that the latter is a better reducing agent. The extent of TCE transformation in 25 days was ca. 20% higher in the dithionite-amended cultures. A decrease in the rate and extent of TCE transformation was observed with an increase in the concentration of bromoethanesulfonate up to 50 mabetm. Offprint requests to: S. G. Pavlostathis     

在AppleⅡ型微机上实现核酸数据处理的工作程序

本文报道了在AppleⅡ型微机上实现核酸数据处理的一系列工作程序。应用这些程序,可进行核酸数据的贮存、对指定的核酸数据结构的改造、限制性内切酶识别位点的检索、核酸序列至蛋白序列的翻译、相关核酸序列及蛋白序列的同源性比较、氨基酸密码使用频率的统计和基因的启动子结构的初步探索等方面的工作。     

Sister chromatid differential staining and NOR activity of BrdU-resistant sublines

Summary Two 30 g/ml BrdU-resistant sublines and two 60 g/ml BrdU-resistant sublines are induced from a Chinese hamster cell line Wg3h (HGPRT^–) by one-step and two-step selections, respectively. By inoculating the cells into BrdU-free medium or by adding more BrdU into the culture medium for 26–27 h, it was found that the two BrdU-resistant sublines analysed have very clear sister chromatid differential (SCD) staining patterns. This indicates that some of the nuclear DNA of the BrdU-resistant cells incorporate with BrdU to reach a kinetic balance. Frequencies of sister chromatid exchange (SCE) of the resistant cells are twice to four times as high as those of the Wg3h cells, depending on which BrdU-resistant subline is analysed. The SCE frequencies of the resistant cells also increase with the BrdU concentration in the medium. Analysis of silver-stained nucleolar organizer regions (NORs) indicates that the NOR activity of three out of the four BrdU-resistant sublines is significantly suppressed, i.e., averages of the Ag-NOR number and number of the chromosomes bearing Ag-NORs per cell decrease significantly. The degree of suppression for different BrdU-resistant sublines may be quite different. The suppressed NOR activity of the resistant cells can gradually be restored when the cells are inoculated into BrdU-free medium, but the recovery speed is far lower than that of the Wg3h cells. The suppression of the NOR activity of the BrdU-resistant sublines should be due to BrdU toxicity.     

Role of actin binding protein phosphorylation in platelet cytoskeleton assembly

Actin binding protein from human blood platelets is shown to exist in the resting platelet as a phosphorylated protein and contains two residues of phosphate per 260,000 kd. Removal of one-half of these residues with E. coli alkaline phosphatase results in the loss of its ability to crosslink F-actin into a low speed sedimentable complex (its cytoskeleton) and to bind to an F-actin affinity column. Thus, phosphorylation-dephosphorylation of ABP may be an important regulatory mechanism by which the platelet regulates its shape via its cytoskeletal structure.     

Effect of gossypol on testicular blood flow and testosterone production in rats

Rats were treated with highly purified gossypol acetic acid at doses of 15 or 30 mg/kg day-1 for 6 weeks to produce an effect on spermatogenesis as shown by reduced sperm motility and increased sperm malformation rates. The treated rats did not differ from the controls in the body weight growth curves and reproductive organ weights. When stimulated with hCG, testicular blood flow was increased in the low dose group; the testosterone concentrations in peripheral and testicular venous blood were also increased to a greater extent than those of the control group. No difference was found between the high dose and control groups in testicular blood flow or testosterone concentrations. The morphology of the Leydig cells was apparently normal, although some degenerative changes in the germinal epithelium were observed in the high dose group. Therefore, there is no evidence in our experiment to show any anti-androgenic effect following 6-week treatment of gossypol in rats, even at the dose of 30 mg/kg day-1.     

An analysis of the sluicing gate in pulmonary blood flow

For pulmonary blood flow in zone 2 condition, in which the blood pressure in the venule (pven) is lower than the alveolar gas pressure (pA), the blood exiting from the capillary sheet and entering a venule must go through a sluicing gate. The sluicing gate exists because the venule remains patent while the capillaries will collapse when the static pressure of blood falls below the alveolar gas pressure. In the original theory of sheet flow the effect of the tension in the interalveolar septa on the flow through the sluicing gate was ignored. Since the tension multiplied by the curvature of the membrane is equivalent to a lateral pressure tending to open the gate, and since the curvature of the capillary wall is high in the gate region, this effect may be important. The present analysis improves the original theory and demonstrates that the effect of membrane tension is to cause flow to increase when the venous pressure continues to decrease. The shape of the sluicing gate resembles that of a venturi tube, and can be determined by an iterative integration of the differential equations. The result forms an important link in the theory of pulmonary blood flow in zone 2 condition.     

红皮树胚胎发育

本文报道红皮树(Styrax suberifoltus Hook.et Arn.)大小孢子发育和早期胚胎发生。子房具胚珠20—23枚,胚珠横生,珠被二层,薄珠心,孢原细胞直接起大孢子母细胞作用。合点端大孢子具功能。胚囊发育为正常型。成熟胚囊具大量淀粉粒。小孢子形成为同时型,成熟花粉为二细胞型。传粉后、受精前两个助细胞在形状和对苏木精着色程度上有显著区别。胚乳发育为细胞型。在合子分裂前,胚乳细胞增至约26个时,暂时停止分裂。苏木精对细胞质不易着色,似解体细胞。有胚乳吸器。