Fed-batch operation of an industrial cell culture process in shaken microwells

Recently we have demonstrated batch suspension culture of mammalian cells in microwell plates. Here we describe a method for fed-batch culture of an industrially relevant GS-CHO (Glutamine Synthetase-Chinese Hamster Ovary) cell line in shaken 24-standard round well (24-SRW) plates. Use of a commercially available ‘sandwich lid’ and appropriate dilution of the bolus feeds counteracted liquid evaporation from the wells resulting in similar cell growth and antibody formation kinetics in both 24-SRW plates (800 μl) and shaken flasks (50 ml). Peak viable cell densities obtained were 8 ± 0.5 × 10⁶ and 9 ± 1.3 × 10⁶ ml⁻¹, respectively, while comparable final titres of a whole IgG of approximately 1.5 g l⁻¹ were recorded. Use of microwells provides at least a 50-fold reduction in medium requirements compared to shake-flask and other culture devices currently used in early stage cell culture process development. The ability to run multiple wells in parallel and to automate culture operation also offers considerable enhancements in experimental throughput.     

A comparison of the LH-releasing activities of LH-RH and its agonistic analogue buserelin in the ovariectomized rat

LH-RH and the potent agonistic analogue (D-Ser(But)6-des-Gly10)-LH-RH(1-9)-ethylamide (HOE-766 or buserelin) were at several doses either infused or injected intravenously in 5-weeks-ovariectomized rats, which had been treated with either 3 micrograms estradiol-benzoate (EB) or with oil, 24 h previously. Blood samples for assay of LH were taken during the subsequent 24 h. Pituitary glands were removed at the end of the experiments. Buserelin, when infused, was slightly more effective than LH-RH on releasing LH. When injected, however, buserelin was at the higher dose ranges increasingly more effective as an LH-releasing agent than LH-RH. EB-treatment increased the LH response of the pituitary gland to both peptides in an identical way. It was concluded that buserelin derives its high potency not from its intrinsic LH-releasing activity, which is only slightly greater than that of LH-RH, but from a longer duration of action.     

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Organization of visual axes in the compound eye of the flyMusca domestica L. and behavioural consequences

Summary The previously derived optical demands for the neural superposition eye are experimentally tested in the compound eye ofMusca domestica L. The optical requirements are fulfilled except in the marginal regions.Taking into account the gradient in spatial packing density of ommatidial axes in a horizontal direction the expected torque response of the fly is calculated and compared with results obtained by Reichardt (1973). The similarity of the curves suggests that existing gradients in the part of the neural network serving this orientation behaviour may be negligible with respect to the studied geometrical gradient.     

Flow-through viscometer for use in the automated determination of hydrolytic enzyme activities: Application in protease,amylase, and pectinase assays

A flow-through viscometer is described, developed for application as a sensor in automated analysis. Its essential part is a glass capillary connected to the sample flow circuit with thin-walled rubber tubes at both ends. These tubes separate the fluid to be tested from a hydraulic liquid. This construction ensures the absence of dead space and a minimal test volume The usefulness of the apparatus is demonstrated in the automated assay of protease, amylase, and pectinase activity. Development of a mathematical model describing the enzymic degradation of macromolecules resulted in a reciprocal equation allowing rectilinear presentation of the calibration data. The feasibility of this model was tested by linear regression analysis of the data.     

Palatability and feeding preferences of Uresiphita maorialis (Lepidoptera: Crambidae) for three Sophora species

In a three-hour bioassay, we tested the palatability and feeding preferences of Uresiphita maorialis (kōwhai moth) for Sophora tetraptera, Sophora microphylla and Sophora prostrata. Palatability tests showed no differences among the Sophora species. Feeding preferences, on the other hand, showed that S. tetraptera and S. microphylla leaves are preferred over S. prostrata leaves. Our results support our field observations in Wellington city parks and gardens showing that S. tetraptera and S. microphylla plants frequently have higher densities of larvae than S. prostrata.     

Biodeterioration of Mayan buildings at uxmal and tulum,Mexico

Uxmal and Tulum are two important Mayan sites in the Yucatan peninsula. The buildings are mainly composed of limestone and grey/black discoloration is seen on exposed walls and copious greenish biofilms on inner walls. The principal microorganisms detected on interior walls at both Uxmal and Tulum were cyanobacteria; heterotrophic bacteria and filamentous fungi were also present. A dark‐pigmented mitosporic fungus and Bacillus cereus, both isolated from Uxmal, were shown to be acidogenic in laboratory cultures. Cyanobacteria belonging to rock‐degrading genera Synechocystis and Gloeocapsa were identified at both sites. Surface analysis previously showed that calcium ions were present in the biofilms on buildings at Uxmal and Tulum, suggesting the deposition of biosolubilized stone. Apart from their potential to degrade the substrate, the coccoid cyanobacteria supply organic nutrients for bacteria and fungi, which can produce organic acids, further increasing stone degradation.     

毛乌素沙地南缘沙丘生物结皮对凝结水形成和蒸发的影响

在水分极度匮乏的荒漠生态系统,凝结水是除降雨之外最重要的水分来源之一,它对荒漠生态系统结构、功能和过程的维持产生重要的影响。为探明半干旱沙区生物结皮表面的凝结水形成和蒸发特征,采用自制的微型蒸渗计(直径7 cm、高5 cm的PVC管)实验观测了不同类型地表(裸沙、浅灰色藻类结皮、黑褐色藻类结皮和苔藓结皮)对凝结水形成和蒸发的影响。结果表明:(1)观测期间共有20次凝结水形成记录,除降雨天气外,几乎每天都能观测到水分凝结现象;(2)不同类型地表凝结水总量依次为(1.998±0.075),(2.326±0.083),(2.790±0.058)和(3.416±0.068) mm,生物结皮表面的凝结水总量显著大于裸沙(P < 0.05);随生物结皮的发育,不同类型生物结皮表面的凝结水总量呈增加的趋势,凝结水总量之间差异显著(P < 0.05);观测期间不同类型地表日平均凝结水量依次为(0.100±0.003),(0.116±0.004),(0.140±0.002)和(0.171± 0.003) mm,不同类型地表日平均凝结水量之间差异极显著(P < 0.01);(3)凝结水形成过程的观测结果显示,凝结水19:00开始形成,23:00-凌晨1:00形成不明显,1:00-7:00继续形成,除浅灰色藻类结皮外,太阳升出后在黑褐色藻类结皮和苔藓结皮表面继续形成少量的凝结水;凝结水7:30开始蒸发,10:30到11:00之间结束蒸发,凝结水在裸沙和浅灰色藻类结皮中的保持时间显著大于黑褐色藻类结皮和苔藓结皮中的保持时间(P < 0.05);(4)凝结水的形成受大气温度、地表温度、空气相对湿度和大气地表温度差等气象因素的影响,但其形成过程不与某一个气象因素呈简单的线性关系。