摘要:

AbstractIn a recent publication, d'Alençonet al.(1)presented evidence that a form of non‐homologous DNA recombination involving direct repeats is dependent upon the replication of the DNA. In addition, density‐labeling experiments showed that after recombination was stimulated, progenies were present only in molecules that had undergone complete replication. These observations are consistent with a replicative and not a breakage‐and‐rejoining model for the DNA recombination events. These two models had of course been contrasted many years ago in mechanistic studies of homologous DNA recombination. It is therefore interesting to place the latest findings of d'Alençonet al.in this historica

ISSN:0265-9247    

DOI:10.1002/bies.950161102

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe particular fascination of butterfly wings for developmental biologists (and others) lies in their spectacular array of colour patterns. The evolutionary and developmental relationships between these patterns have been analysed and we know something of the cell interactions involved in their formation(1). Now butterfly homologues ofDrosophilawing‐patterning genes have been identified, and their expression patterns offer the first clues to the molecular mechanisms which specify wing colour patterns(2

ISSN:0265-9247    

DOI:10.1002/bies.950161103

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe Alu sequence is a SINE (Short INterspersed Element) that is abundant in the human genome. A new analysis(1)reveals an unexpected conservation of some bases in the DNA sequence of the element. The bases involved include those forming an RNA polymerase III promoter. An unresolved question is whether this conservation results from selection for transposability. This, in turn, is related to the larger question of the evolutionary relationship between members of the Alu sequence family.

ISSN:0265-9247    

DOI:10.1002/bies.950161104

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

年代:1994

数据来源: WILEY

摘要:

AbstractAlthough retroviral integration requires specific viral DNA sequences, factors which govern the choice of a chromosomal target site within an infected celi are less clear. For example, certain chromosomal regions may be inaccessible to the viral integration machinery, while others may favor integration. A recent paper by Withers‐Wardet al.(1)addresses this issue using a polymerase chain reaction‐based assay capable of identifying single integration events within a large population of infected cells. Their results show that integration can occur into many different chromosomal regions, and that local DNA structure can influence the site of integration within a given reg

ISSN:0265-9247    

DOI:10.1002/bies.950161105

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

年代:1994

数据来源: WILEY

摘要:

AbstractA variety of leech homeobox genes have been identified by homology with genes that are known to bring about the regionalization and segmentation of the anteroposterior body axis in other organisms. Embryonic expression patterns suggest a number of interphyletic similarities in the way that these genes are utilized. However, several interesting differences have also been observed. In particular, transplantation experiments in the leech embryo have shown that axially aligned patterns of homeobox gene expression are not specified by a global pattern of positional cues. Rather, the leech independently establishes anteroposterior patterns of gene expression in each of five discrete stem cell lineages, and these patterns are brought into their final alignment through a process of morphogenetic assembly.

ISSN:0265-9247    

DOI:10.1002/bies.950161106

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

年代:1994

数据来源: WILEY

摘要:

AbstractIt has been known for 20 years that the ribosomal protein S6 is rapidly phosphorylated when cells are stimulated to grow or divide. Furthermore, numerous studies have documented that there is a strong correlation between increases in S6 phosphorylation and protein synthesis, leading to the idea that S6 phosphorylation is involved in up‐regulating translation. In an attempt to define a mechanism by which S6 phosphorylation exerts translational control, other studies have focused on characterizing the sites of phosphorylation of this protein and its location within the ribosome. Recent data show that S6 is a protein which may have diverse cellular functions and is essential for normal development, and that it may be involved in the translational regulation of a specific class of message

ISSN:0265-9247    

DOI:10.1002/bies.950161107

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

年代:1994

数据来源: WILEY

摘要:

AbstractCytoskeletal proteins provide the structural foundation that allows cells to exist in a highly organized manner. Recent evidence suggests that certain cytoskeletal proteins not only maintain structural integrity, but might also be associated with signal transduction and suppression of tumorigenesis. Since the time of the discovery of tensin, a fair amount of data has been gathered which supports the notion that tensin is one such protein possessing these characteristics. In this review, we discuss recent studies that: (1) elucidate a role for tensin in maintenance of cellular structure and signal transduction; (2) implicate tensin as the anchor for actin filaments at the focal adhesion; (3) describe the phosphorylation of tensin; (4) describe potential targets for its Src homology region 2 domain; (5) describe the association between tensin and the nuclear protein p130; and (6) demonstrate that increased tensin expression in a cell line appears to reduce its transformation potential.

ISSN:0265-9247    

DOI:10.1002/bies.950161108

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

年代:1994

数据来源: WILEY

摘要:

AbstractNew possibilities to modify function and direct repair in the central nervous system (CNS) have been established by the merger of gene transfer technology with neural transplantation. Rapid advances in viral‐mediated DNA‐delivery procedures permit the study of novel gene expression in neurons and glial cells. Foreign genes, transferred by a virus vector, can be used to generate new cell lines, identify transplanted cells, and express growth factors or enzymes for neurotransmitter synthesis. In addition to CNS cell types, non‐neural cells are also being studied with transgene technology in the nervous system. Functional effects have been obtained with grafts of genetically modified cells in animal models of several nervous system disorders, and the recent results set the stage for potential application of these techniques to human CNS gene th

ISSN:0265-9247    

DOI:10.1002/bies.950161109

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

年代:1994

数据来源: WILEY

摘要:

AbstractDNA mismatch repair is an important pathway of mutation avoidance. It also contributes to the cytotoxic effects of some kinds of DNA damage, and cells defective in mismatch repair are resistant, or tolerant, to the presence of some normally cytotoxic base analogues in their DNA. The absence of a particular mismatch binding function from some mammalian cells confers resistance to the base analogues O6‐methylguanine and 6‐thioguanine in DNA. Cells also acquire a spontaneous mutator phenotype as a consequence of this defect. Impaired mismatch binding can cause an instability in DNA microsatellite regions that comprise repeated dinucleotides. Microsatellite DNA instability is common in familial and sporadic colon carcinomas as well as in a number of other tumours. Several independent lines of investigation have identified defects in mismatch repair proteins that are causally related to these canc

ISSN:0265-9247    

DOI:10.1002/bies.950161110

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

年代:1994

数据来源: WILEY

摘要:

AbstractWheat is an allopolyploid containing three distinct but genetically related (homoeologous) genomes, A, B and D. Because of polyploid inheritance and large genome size (16×1012bp), the wheat genome is thought to be intractable to map‐based cloning of agronomic and other genes of interest. We propose a targeted geneti mapping strategy that combines linkage and physical mapping and may facilitate map‐based cloning. High‐density linkage maps are either generated in wheat or in diploidTriticum tauschii, the donor of the D genome to wheat. Molecular marker‐based chromosome maps are constructed, using an array of deletion lines in wheat. The conventional genetic linkage maps are aligned with chromosome maps to construct cytogenetic ladder maps (CLMs). The CLMs allow region‐specific mapping and convert genetic distances into physical distances. The information from CLMs suggests that many genes in wheat are present in clusters that are highly recombiogenic, small, and may be amenable to cloning by chromosome walking. Therefore, the effective genome size of wheat is relatively small in comparison to the whole genome. The utility of using the smaller genome of rice for mapping and homologous gene cloning is

ISSN:0265-9247    

DOI:10.1002/bies.950161111

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

年代:1994

数据来源: WILEY