ISSN:0265-9247    

DOI:10.1002/bies.950050502

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe immune system can generate an almost infinite number of different antibody specificities, the sum of which is the antibody repertoire. This article considers aspects of the mechanism and control of immunoglobulin variable (V) region gene assembly with a focus on how these factors may affect generation of the antibody repertoire in normal and disease states. New model systems to study the mechanism and control of V gene assembly are described, in particular the introduction of V gene recombination substrates into Abelson murine leukemia virus‐transformed pre‐B cells. Finally, a model is presented which suggests that control of V gene assembly is mediated by regulating accessibility of substrate gene segments to recombinational machin

ISSN:0265-9247    

DOI:10.1002/bies.950050503

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

年代:1986

数据来源: WILEY

摘要:

AbstractTheDrosophila position‐specific antigens are a family of cell‐surface glycoprotein complexes showing spatially restricted patterns of expression. Changes in these distributions correlate with morphogenetic events like compartment‐alization and the formation of grooves and folds during tissue organization. The complexes each contain a common component associated with different variable components. Different tissues, organs and regions of the body express complexes containing different subsets of variable components. The structure of the complexes resembles that of the family of vertebrate receptors for fibronectin, molecules which function in morphogenetic processes involving cell migration and attachment. It is possible that the position‐specific antigens have a similar role in fly deve

ISSN:0265-9247    

DOI:10.1002/bies.950050504

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

年代:1986

数据来源: WILEY

摘要:

AbstractA very rapid cellular event that follows chemotactic stimulation of leucocyte and cellular slime mould amoebae is a massive polymerization of G to F actin and its association with the cytoskeleton. In the cellular slime moulds this event occurs within 3–5 sec of cell surface binding of chemoattractants. It is correlated with rapid pseudopodium extension and may be a cell orientation mechanism. Curiously, before an amoebae moves away in the direction of its new pseudopodium it rounds up or “cringes” for 10–20 sec, an event correlated with a massive actin depolymerization. Transduction of the chemotactic signal involves Ca2+release from internal stores by inositol trisph

ISSN:0265-9247    

DOI:10.1002/bies.950050505

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

年代:1986

数据来源: WILEY

摘要:

AbstractIn many mammalian cell types, increases in the level of nonpolymerized tubulin cause an inhibition in tubulin synthesis which is accompanied by a decrease in tubulin mRNA levels. To see whether inhibition is caused by nuclear or cytoplasmic events, two groups have recently examined the ability of enucleated cells to autoregulate tubulin synthesis.1,2These experiments have demonstrated that transcription, processing, and transport of tubulin mRNAs from the nucleus to the cytoplasm are not major sites of autoregulation. Instead, monomeric tubulin must reduce, either directly or indirectly, the translatability of its own message.

ISSN:0265-9247    

DOI:10.1002/bies.950050506

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe immune system has evolved to detect and remove foreign or non‐self molecules from the body. To perform this task, the system has coupled together specific recognition with non‐specific effector mechanisms in at least two distinct fashions, as outlined in this rev

ISSN:0265-9247    

DOI:10.1002/bies.950050507

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

年代:1986

数据来源: WILEY

摘要:

AbstractBinding of antigen or lectin to the surface of a T lymphocyte initiates a complex sequence of events which result in both T cell proliferation and the acquisition of immunologic functions. This complex sequence of events is most likely programmed and precisely timed by a series of contingent gene activations in which one member of this series activates the next. The two most obvious examples of these stages are the set of genes activated when antigen interacts with the antigen receptor and the set of genes activated when IL‐2 interacts with its receptor. However, it is likely that several other parallel pathways of gene activation are necessary to bring about T‐cell division. An example would be the antigen‐induced activation of the c‐myc gene, which in turn is likely to be involved in regulating an additional group of genes not directly controlled by either IL‐2 or antigen. A fundamental understanding of T‐lymphocyte activation necessitates identification of the factors involved in initiating each of these contingent levels of gene

ISSN:0265-9247    

DOI:10.1002/bies.950050508

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

年代:1986

数据来源: WILEY

摘要:

AbstractIn eukaryotic cells intron sequences are usually spliced out with a high degree of precision from heterogenous nuclear RNA (hnRNA) to give functional mRNA with exons in their right order. Provided with the right substrates, cell extracts can achieve the same. With exotic substrates, on the other hand, the same extracts can cut exons from one RNA and join them to exons from another RNA, a process termed trans‐splicing.In vivo,RNA trans‐splicing could lead to faulty, but also to novel proteins and, through reverse transcription, to genomic rearrangements. So far, in living cells trans‐splicing has only been invoked to occur in trypanosomes. In these unicellular organisms most if not all mRNAs are made discontinuously, so that the mature mRNAs carry, at their5′ end, a common 35‐nucleotide sequence, called a miniexon, encoded separately in the genome. The miniexon is most likely joined to the body of the mRNA by trans

ISSN:0265-9247    

DOI:10.1002/bies.950050509

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

年代:1986

数据来源: WILEY

ISSN:0265-9247    

DOI:10.1002/bies.950050510

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

年代:1986

数据来源: WILEY

摘要:

AbstractLeydig cells, traditionally known as the steroidogenic workhorses of the testis, are now known to synthesize significant amounts of non‐steroid products including some potent bioactive proteins and peptides. These products are currently being investigated for their potential role in the paracrine regulation of spermatogenesis in the nearby seminiferous tubules and in the autocrine regulation of Leydig cell functio

ISSN:0265-9247    

DOI:10.1002/bies.950050511

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

年代:1986

数据来源: WILEY