危险中的美丽笔走南极(一)

警告——B-22事件 南极非同寻常的恶劣环境,不时从那里爆出新闻。2002年3月18日,美联社从华盛顿发出一条新闻,引起全世界的关注。消息称,一座相当于新加坡国土面积9倍多的冰山从南极冰架断裂开来。一天后,即3月20日,电视上又反复播放这一画面。只见一座座平面大冰山相互间已经拉开很大的间距,向宽阔的陆缘冰区散去。 南极冰山出现特大松动是美国国家     

Microalgal cultivation and hydrodynamic characterization using a novel tubular photobioreactor with helical blade rotors

Bioprocess and Biosystems Engineering - Industrial-scale microalgal cultivation for food, feedstocks and biofuel production is limited by several engineering factors, such as cultivation systems....     

Immobilization of rice (Oryza sativa L.) callus in polyurethane foam using a turbine blade reactor

A turbine blade reactor (TBR) was employed to cultivate rice calli immobilized in polyurethane foam as a support. In the bioreactor, rice callus could be immobilized quickly in a 3 mm cube of the support, and then attached to the stainless mesh cylinder set at the center of the bioreactor. For improving the immobilization ratio of rice callus in the bioreactor, the optimum support volume and bioreactor operation and modification were investigated. The support volume had a pronounced effect on the immobilization ratio of rice callus, and the maximum volume was found to be 60 ml. By repeating a periodic operation three times (agitating at 300 rpm for 5 min and then 50 rpm for 2 min, and then 200 rpm of constant agitation speed during the remaining time), rice calli were uniformly entrapped in almost all supports and the immobilization ratio was improved as compared with that using a constant bioreactor operation at 200 rpm. When the inoculum concentration of rice callus was increased, the callus concentration after 7-day culture increased, but the immobilization ratio decreased. To improve the immobilization efficiency further at high cell concentration, the TBR was modified by setting an air sparger inside the stainless mesh cylinder. In the modified TBR, floating of the support by attached air bubbles was avoided, and the immobilization ratio increased further and reached 86.3% when we increased the support volume to 90 ml under the periodic bioreactor operation on a daily basis. The regeneration frequency of immobilized callus was increased by periodic operation and modification of the bioreactor.     

桃树叶片的角质蒸腾实验

折枝处理降低了叶片下表皮蒸腾速率，提高了上表皮角质蒸腾占叶总蒸腾的比值，使角质蒸腾的上下振幅增大。２ ｍ 高度叶片低于１ ｍ 高度叶片的上表皮角质蒸腾。位于黑纸套内及阴处的叶片上表皮角质蒸腾占叶总蒸腾的比值均增大，而全日上表皮角质蒸腾的振幅却减少。     

The Knotted leaf blade is a mosaic of blade,sheath, and auricle identities

The dominant Knotted-1 mutations in maize alter development of the leaf blade. Sporadic patches of localized growth, or knots, and fringes of ectopic ligule occur along lateral veins of mutant leaf blades. In addition, bundle sheaths do not completely encircle lateral veins on mutant leaf blades. We have compared mutant leaf blades with wild-type leaves to determine the precise nature of the perturbed regions. Our analysis includes characterization of epidermal cell shapes, localization of photosynthetic proteins and histology of the leaf. We show that mutant leaf blades are a mosaic of leaf organ components. Affected regions of mutant leaf blades resemble either sheath or auricle tissue in both external and internal features. This conversion of blade cells represents an acropetal shift of more basal parts of the leaf blade region and correlates with previously identified ectopic expression of the Knotted-1 protein in the leaf blade. We propose that inappropriate expression of Kn1 interferes with the process of establishment of cell identities, resulting in early termination of the normal blade development program or precocious expression of the sheath and auricle development programs. © 1994 Wiley-Liss, Inc.     

抗原识别中的危险模式

Matzinger提出的危险模式摆脱了自我与非我模式(SNS)和感染的非我模式(INS)的束缚,认为免疫应答的启动是由损伤的细胞发出的危险信号所决定的,又组织细胞决定了免疫应答效应的类型。并运用危险信号模式对肿瘤、移植、母胎耐受、自身免疫性疾病、先天性淋巴细胞(NKIT细胞、YδT细胞)的作用等作了新的解释。     

Operational optimization of a turbine blade reactor using macroporous support and its application to rice callus regeneration

Optimal operation condition was investigated for immobilized rice callus culture using a turbine blade reactor (TBR²) with polyurethane foam supports. By using polyurethane foam block as immobilization support, the inhibition of cell growth at a high agitation speed was avoided because the hydrodynamic stress against immobilized cell was probably reduced. Experimental results in each operational condition were assessed by means of rice callus growth, immobilization ratio in TBR and those regeneration frequencies in regeneration culture using solid medium. Concerning with pore size of polyurethane foam and support size, three-millimeter cube support of polyurethane foam with an average pore size of 1.3 mm was the most suitable support. The maximum immobilization ratio was 50% under 5% support volume by volume of growth medium. For improving the immobilization ratio of rice callus in the TBR, the optimum TBR operation and modification were investigated further. By repeating a periodic operation 3 times (agitating at 300 rpm for 5 min and then 50 rpm for 2 min, and then 200 rpm of constant agitation speed during the remaining time), almost all supports could entrap rice callus and homogeneous immobilization was attained. The immobilization ratio was improved as compared with that using a constant operation at 200 rpm. Next, the TBR was modified by setting an air sparger inside the stainless mesh cylinder. In the modified TBR, the floating support by air bubbles was reduced, and the immobilization ratio increased further and reached 86.3% when we increased the support volume to 15% under periodic operation on a daily basis. The regeneration frequency of immobilized callus was also slightly increased by periodic operation and modification of the TBR.