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671.
Lucia Taja-Chayeb Alma Chavez-Blanco Jorge Martínez-Tlahuel Aurora González-Fierro Myrna Candelaria Jose Chanona-Vilchis Elizabeth Robles Alfonso Dueñas-Gonzalez 《Cancer cell international》2006,6(1):22-11
Background
Despite significant achievements in the treatment of cervical cancer, it is still a deadly disease; hence newer therapeutical modalities are needed. Preliminary investigations suggest that platelet-derived growth factor (PDGF) might have a role in the development of cervical cancer, therefore it is important to determine whether this growth factor pathway is functional and its targeting with imatinib mesylate leads to growth inhibition of cervical cancer cells. 相似文献672.
Butterflies show different functional and species diversity in relationship to vegetation structure and land use
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673.
Katrin Koehler Meera Malik Saqib Mahmood Sebastian Gießelmann Christian Beetz J. Christopher Hennings Antje K. Huebner Ammi Grahn Janine Reunert Gudrun Nürnberg Holger Thiele Janine Altmüller Peter Nürnberg Rizwan Mumtaz Dusica Babovic-Vuksanovic Lina Basel-Vanagaite Guntram Borck Jürgen Brämswig Reinhard Mühlenberg Pierre Sarda Alma Sikiric Kwame Anyane-Yeboa Avraham Zeharia Arsalan Ahmad Christine Coubes Yoshinao Wada Thorsten Marquardt Dieter Vanderschaeghe Emile Van Schaftingen Ingo Kurth Angela Huebner Christian A. Hübner 《American journal of human genetics》2013
674.
Production of Tumor-Inhibitory L-Asparaginase by Submerged Growth of Serratia marcescens 总被引:2,自引:5,他引:2
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Production of a tumor-inhibitory asparaginase by submerged fermentation with Serratia marcescens ATCC 60 was studied to ascertain optimal nutritional conditions for large-scale production leading to enzyme purification studies. Five strains of S. marcescens were screened in shake-flask studies and were found to produce 0.8 to 3.7 IU/ml 48 hr after inoculation. The requirements for asparaginase production with S. marcescens ATCC 60, the high producing strain, included the following: 4% autolyzed yeast extract medium (initial pH 5.0), an incubation temperature of 26 C, and limited aeration for a zero level of dissolved oxygen during the fermentation. Addition of various carbohydrates to the fermentation medium did not enhance yields. The peak cell population in the fermentation medium and the maximal asparaginase yields occurred simultaneously. Highest enzyme yields were found when the pH of the fermentation cycle rose to approximately 8.5. Yields of 4 IU of asparaginase/ml of cell suspension have been obtained consistently in 40 to 42 hr from 10-liter volumes (500 ml/4-liter bottle) produced on a reciprocating shaker. Scale-up to a 60-liter fermentor yielded 3.1 IU/ml in 35 hr. 相似文献
675.
Ulf Bntgen Andrew Liebhold Daniel Nievergelt Beat Wermelinger Alain Roques Frederick Reinig Paul J. Krusic Alma Piermattei Simon Egli Paolo Cherubini Jan Esper 《Oecologia》2020,192(2):543-552
The sudden interruption of recurring larch budmoth (LBM; Zeiraphera diniana or griseana Gn.) outbreaks across the European Alps after 1982 was surprising, because populations had regularly oscillated every 8–9 years for the past 1200 years or more. Although ecophysiological evidence was limited and underlying processes remained uncertain, climate change has been indicated as a possible driver of this disruption. An unexpected, recent return of LBM population peaks in 2017 and 2018 provides insight into this insect’s climate sensitivity. Here, we combine meteorological and dendrochronological data to explore the influence of temperature variation and atmospheric circulation on cyclic LBM outbreaks since the early 1950s. Anomalous cold European winters, associated with a persistent negative phase of the North Atlantic Oscillation, coincide with four consecutive epidemics between 1953 and 1982, and any of three warming-induced mechanisms could explain the system’s failure thereafter: (1) high egg mortality, (2) asynchrony between egg hatch and foliage growth, and (3) upward shifts of outbreak epicentres. In demonstrating that LBM populations continued to oscillate every 8–9 years at sub-outbreak levels, this study emphasizes the relevance of winter temperatures on trophic interactions between insects and their host trees, as well as the importance of separating natural from anthropogenic climate forcing on population behaviour. 相似文献
676.
Roots of Vicia faba seedlings were grown for periods of 2 to 48 hours in solutions of P32 in the form of NaH2PO4. Stripping-film autoradiographs were made of squashes and sectioned material from the meristem and from proximal segments where cell divison is rare. It is concluded (a) that P32 enters into organically bound form (probably desoxyribonucleic acid) in the nucleus during the resting stage, but not during the actual division of the cell; (b) that P32 is incorporated in this form only in nuclei which are preparing for division; (c) that P32 in this form is inherited by the daughter cells. 相似文献
677.
Many biological wastewater treatment processes are based on bacterial biofilms, i.e. layered aggregates of microbial populations deposited on surfaces. Detachment and (re-)attachment leads to an exchange of biomass between the biofilm and the surrounding aqueous phase. Traditionally, mathematical models of biofilm processes do not take the contribution of the suspended, non-attached bacteria into account, implicitly assuming that these are negligible due to the relatively small amount of suspended biomass compared to biofilm biomass. In this paper, we present a model for a nitrifying biofilm reactor that explicitly includes both types of biomass. The model is derived by coupling a reactor mass balance for suspended populations and substrates with a full one-dimensional Wanner–Gujer type biofilm model. The complexity of this model, both with respect to mathematical structure and number of parameters, prevents a rigorous analysis of its dynamics, wherefore we study the model numerically. Our investigations show that suspended biomass needs to be considered explicitly in the model if the interests of the study are the details of the nitrification process and its intermediate steps and compounds. However, suspended biomass may be neglected if the primary interests are the overall reactor performance criteria, such as removal rates. Furthermore, it can be expected that changes in the biofilm area, attachment, detachment, and dilution rates are more likely to affect the variables primarily associated with the second step of nitrification, while the variables associated with the first step tend to be more robust. 相似文献
678.
679.
Taxonomy by Carbon Replication: I. An Examination of Streptomyces hygroscopicus 总被引:9,自引:5,他引:4
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Pre-shadowed carbon replication of spore surfaces (carbon repligraphy) provides a new technique for the characterization of streptomycetes. Carbon repligraphs of five members of the Streptomyces hygroscopicus complex show two distinct types. Type I shows a nonsegmented spore structure with an extremely wrinkled surface. Type II has a segmented spore chain with detailed surface structure resembling a basket weave. 相似文献
680.