ISSN:0265-9247    

DOI:10.1002/bies.950080402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractMouse embryo cells, primed to differentiate with the hypomethylating agent 5‐azacytidine (5‐aza‐CR), provide an excellent model system in which cellular differentiation can be studied at the molecular level. An inherent advantage of this system is the availability of clonal populations of cells representative of the non‐differentiated precursor, those whose determinative state is that of a specific lineage, and the end stage, phenotypically mature cell. Analysis of these cultures at the cellular and molecular level will advance our understanding of requirements for and the mechanism of action of growth modulators as well as the necessity for controlled expression of certain proto‐oncogenes. At a more fundamental level, the system can be used to identify, isolate and characterize genes whose expression alters the phenotypic fate

ISSN:0265-9247    

DOI:10.1002/bies.950080403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractEnhancer elements are short stretches of nucleotides operationally defined by their cis‐acting ability to increase the transcription of nearby genes. They function relatively independently of position, orientation, and distance. Some show narrow tissue specificity while others permit constitutive expression in many different cell types. Although the first enhancer was described for simian virus 40 (SV40) more than five years ago, its mechanism of action has remained unclear. This review describes some of the models proposed to explain the physical role of enhancers in eukaryotic transcriptio

ISSN:0265-9247    

DOI:10.1002/bies.950080404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractIron delivered by transferrin to the interior of the cell is in part utilized in biosynthetic processes and in part incorporated into ferritin, the major iron storage protein. The intracellular ferritin concentration is directly correlated to and determined by the extent of iron supply to the cell. Intracellular partitioning of iron to ferritin is suggested as forming the basis of cellular iron homeostasis.

ISSN:0265-9247    

DOI:10.1002/bies.950080405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractA large number of cellular proteins bind ATP, frequently utilizing the free energy of ATP hydrolysis to drive specific biological reactions. Recently, a family of closely related ATP‐binding proteins has been identified, the members of which share considerable sequence identity. These proteins, from both prokaryotic and eukaryotic sources, presumably had a common evolutionary origin and include the product of thewhitelocus ofDrosophila, the P‐glycoprotein which confers multidrug resistance on mammalian tumours, and prokaryotic proteins associated with such diverse processes as membrane transport, cell division, nodulation and DNA repair. A comparison of these various proteins provides valuable insights into the function and evolution of the multicomponent systems with which they are associa

ISSN:0265-9247    

DOI:10.1002/bies.950080406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractTwo general features of metameric patterning inDrosophilaare considered: (1) maintenance of a constant number of metameres (segments or parasegments) in the face of variation in length of the embryo; (2) expression of pattern by on‐off switchings of particular genes, with only three or four rows of cells to each element of pattern. For each of these features, the general strategic question is raised: could reaction‐diffusion theory account for this? In both cases, it is answered affirmatively. For the second feature, this review contains some hitherto unpublished computer simulations by one of us (K. Y. T.), illustrating that a reaction‐diffusion mechanism can be transformed into a patterned switching mechanism by nothing more than compartmenting of the diffusion region. For the scale of three compartments to one pattern repeat unit (representing three rows of cells to a segment) the switching pattern predicted by computation is two‐off to one‐on. This resembles the pattern of expression of the engrailed gene, posteriorly localized in eac

ISSN:0265-9247    

DOI:10.1002/bies.950080407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0265-9247    

DOI:10.1002/bies.950080408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0265-9247    

DOI:10.1002/bies.950080409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0265-9247    

DOI:10.1002/bies.950080410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0265-9247    

DOI:10.1002/bies.950080411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY