ISSN:0265-9247    

DOI:10.1002/bies.950160502

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

年代:1994

数据来源: WILEY

ISSN:0265-9247    

DOI:10.1002/bies.950160503

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

年代:1994

数据来源: WILEY

ISSN:0265-9247    

DOI:10.1002/bies.950160504

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

年代:1994

数据来源: WILEY

摘要:

AbstractCytokine receptors fall into two basic classes: those with their own intrinsic protein tyrosine kinase (PTK) domain, and those lacking a PTK domain. Nonetheless, PTK activity plays a fundamental role in the signal transduction processes lying downstream of both classes of receptor. It now seems likely that many of those cytokine receptors that lack their own PTK domain use members of the JAK family of PTKs to propagate their intracellular signals. Moreover, the involvement of the JAK kinases in a newly defined pathway which links membrane receptors directly to the activation of nuclear genes, via latent cytoplasmic transcription factors known as STATs (for Signal Transducers and Activators of Transcription), appears to be a theme common to cytokine receptors of both classes.

ISSN:0265-9247    

DOI:10.1002/bies.950160505

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

年代:1994

数据来源: WILEY

摘要:

AbstractOne of the earliest structural changes observed in cells in response to many extracellular factors is membrane ruffling: the formation of motile cell surface protrusions containing a meshwork of newly polymerized actin filaments. It is becoming clear that actin reorganization is an integral part of early signal transduction pathways, and that many signalling molecules interact with the actin cytoskeleton. The small GTP‐binding protein Rac is a key regulator of membrane ruffling, and proteins that can regulate Rac activity, such as Bcr, are likely to act on this signalling pathway. In addition, several previously characterized signal transducing molecules are implicated in the membrane‐ruffling response, including Ras, the adaptor protein Grb2, phosphatidyl inositol 3‐kinase, phospholipase A2and phorbol ester‐responsive proteins. Changes in polyphosphoinositide metabolism and intracellular Ca2+levels may also play a role. A number of actin‐binding and organizing proteins localize to membrane ruffles and are potential targets for these signal transducing

ISSN:0265-9247    

DOI:10.1002/bies.950160506

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

年代:1994

数据来源: WILEY

摘要:

AbstractIn the bracket mushroom,Schizophyllum commune, a recessive genetic alteration,mnd, causes abnormally hyperplastic three‐dimensional mounds of hyphae to rise from the surface of both haploid and dikaryotic mycelia.mnd, although not a genetic block in the fruiting body developmental pathway, is at least partially epistatic to fruiting. Within dikaryons containing both mutant and wild‐type nuclei, [mnd + mnd+], a nonreciprocal somatic recombination event can lead to stable conversion of themnd+region of the wild‐type nucleus tomnd.This transformation to the homoallelic [mnd+mnd] condition involves no genomic areas other than themndregion and permanently prevents any further fruiting. Studies relating to the recombination mechanism have ruled out a diploid intermediate state and other concomitants of orthodox somatic recombination, as well as whole chromosome transfer. Instead, a novel form of internuclear genetic transfer is postulated whereby a nearby locus, mob+, controls the mobilization of themndchromosomal region alone from one nucleus to the other within the binucleate cells of dikaryotic my

ISSN:0265-9247    

DOI:10.1002/bies.950160507

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

年代:1994

数据来源: WILEY

摘要:

AbstractNeuronal signalling involves multiple neuropeptides that are diverse in structure and function. Complex patterns of tissue‐specific expression arise from alternate RNA splicing of neuropeptide‐encoding gene transcripts. The pattern of expression and its role in cell signalling is diffecult to study at the level of single neurons in the complex vertebrate brain. However, in the model molluscan system,Lymnaea, it is possible to show that alternate mRNA expression of the FMRFamide gene is specific to single identified neurons. Two different transcripts are expressed in a mutually exclusive manner in different neurons. Post‐translational processing of the two precursor proteins leads to completely distinct sets of neuropeptide transmitters. The function of these transmitter cocktails, resulting from alternate mRNA splicing, was studied physiologically in identified neurons forming part of a behaviourally important network regulating hear

ISSN:0265-9247    

DOI:10.1002/bies.950160508

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe differentiation of mammalian neurons during development is a highly complex process involving regulation and coordination of gene expression at multiple steps. The P19 mouse embryonal carcinoma cell line is a suitable model system with which to analyze regulation of neuronal differentiation. These multipotential cells can be maintained and propagated in tissue culture in an undifferentiated state. Exposure of aggregated P19 cells to retinoic acid results in the differentiation of cells with many fundamental phenotypes of mammalian neurons. Undifferentiated P19 cells are amenable to genetic manipulations such as transfection and establishment of stable clonal cell lines expressing introduced genes. Proteins that play a key role in the neuronal differentiation of P19 cells are beginning to be identified. These include retinoic acid receptors, the epidermal growth factor receptor and the transcription factors Oct‐3 and Brn‐2. The biological and technical advantages of this system should facilitate deeper analysis of the activities of proteins that play a role in neuronal differentiat

ISSN:0265-9247    

DOI:10.1002/bies.950160509

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

年代:1994

数据来源: WILEY

摘要:

AbstractIntermediate filament (IF) protein tetramers contain two DNA‐ and core‐histone‐binding motifs in rotational symmetry in one and the same structural entity. We propose that IF protein oligomers might displace histone octamers from nucleosomes in the process of transcription initiation and elongation, to deposit them transiently on their α‐helical coiled‐coil domains. We further propose that structurally related proteins of the karyoskeleton, constructed from an α‐helical domain capable of coiled‐coil formation and a basic DNA‐binding region adjacent to it, may be similarly involved in nucleosome activation. These proteins would function as auxiliary factors that disrupt nucleosomal structure to permit transcription and other DNA‐dependent processes to pr

ISSN:0265-9247    

DOI:10.1002/bies.950160510

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe laser scanning confocal microscope (LSCM)LSCM: laser scanning confocal microscope; FISH: fluorescencein situhybridisation; DiO6: 3,3′‐dihexyloxacarbocyanine iodide; NBD‐ceramide: 6‐((N‐(7‐nitrobenz‐2‐oxa‐1,3‐diazol‐4‐yl)amino)‐caproyl)sphingosine; DiO: 3,3′‐dioctadecyloxacarbocyanine perchlorate; DiI: 1,1′‐dioctadecyl‐3,3,3′,3′‐tetramethyl‐indocarbocyanine perchlorate; CCD: charge‐coupled device; DIC: differential interference contrast; FURA2: (‐(2‐(5‐carboxyoxazol‐2‐yl)‐6‐aminobenzofuran‐5‐oxy)‐2‐)2′‐amino‐5′‐methylphenoxy)‐ethane‐N,N,N′,N′‐tetraacetic acid, sodium salt);BCECF: 2′,7′‐bis‐(carboxyethyl)‐5‐(and‐6‐)‐carboxyfluorescein;fluo‐3: 1‐(2‐amino‐5‐(2,7‐dichloro‐6‐hydroxy‐3‐oxo‐3H‐xanthen‐9‐yl)‐2‐(2′amino‐5′‐methylphenoxy)‐ethane‐N,N,N′,N′,‐tetraacetic acid, ammonium salt; DAPI: 4′,6‐diamidino‐2‐phenylindole, dihydrochloride; PET: positron emission tomogrophy; CT: computer‐assisted tomogrophy;CiD: cubitus interruptus dominus; MRC: Medical Research Council; TOTO‐1: benzothiazolium‐4‐quinolinium dimer; YOYO‐1: benzoxazolium‐4‐quinolinium dimer; ex.: excitation wavelength; em.: emission wavelength.is now established as an invaluable tool in developmental biology for improved light microscope imaging of fluorescently labelled eggs, embryos and developing tissues. The universal application of the LSCM in biomedical research has stimulated improvements to the microscopes themselves and the synthesis of novel probes for imaging biological structures and physiological processes.

ISSN:0265-9247    

DOI:10.1002/bies.950160511

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

年代:1994

数据来源: WILEY