ISSN:0265-9247    

DOI:10.1002/bies.950050302

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe chromosomes undergo a condensation‐decondensation cycle within the life cycle of mammalian cells. Chromosome condensation is a complex and critical event that is necessary for the equal distribution of genetic material between the two daughter cells. Although chromosome condensation‐decondensation and segregation is mechanistically complex, it proceeds with high fidelity during the eukaryotic cell division cycle. Cell fusion studies have indicated the presence of chromosome condensation factors in mammalian cells during mitosis. If extracts from mitotic cells are injected into immature oocytes of Xenopus laevis, they induce meiotic maturation (i.e. germinal vesicle breakdown and chromosome condensation) within 2–3 hours. Recently, we showed that the maturation‐promoting activity of the mitotic cell extracts is inactivated by certain protein factors present in cells during the G1period. The activity of the G1factors coincides with the process of chromosome decondensation that begins at telophase and continues throughout the G1period. These studies have revealed that the mitotic factors and the G1factors play a pivotal role in the regulation of condensation and decondensation of chromosomes. Furthermore, our studies strongly suggest that nonhistone protein phosphorylation and dephosphorylation may mediate chromosome condensation and decondensation, respe

ISSN:0265-9247    

DOI:10.1002/bies.950050303

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe genomes of the slime moulds are relatively small when compared with those of higher eukaryotes. They also contain far fewer families of repetitive sequences. Nevertheless, the general patterns of organization of their repetitive DNA are similar. The slime moulds can therefore help us to investigate the structure and evolution of repetitive DNA in “simple” eukaryotes and to understand how these sequences contribute to the architecture and function of the eukaryotic genome. Several questions remain, including perhaps the most important: do repetitive sequences perform some definable functi

ISSN:0265-9247    

DOI:10.1002/bies.950050304

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

年代:1986

数据来源: WILEY

摘要:

AbstractAn important aspect of the developmental maturation of lymphocytes is their capacity to locate and enter lymphoid organs with great rapidity and specificity and to follow certain routes within these organs for the attainment of particular immunological capabilities. It is now known that this “homing response” to lymphoid organs involves specific glycoprotein receptors on the lymphocyte cell surface. The biochemistry of these receptors and their significance in normal and pathological immune responses are discus

ISSN:0265-9247    

DOI:10.1002/bies.950050305

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe export of processed RNA molecules from the nucleus is an intricately regulated process, subject to various developmental and physiological controls. The structural and biochemical properties of the nuclear envelope that are involved in this process are described here.

ISSN:0265-9247    

DOI:10.1002/bies.950050306

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

年代:1986

数据来源: WILEY

摘要:

AbstractPurified nuclei are being used as a test system to study the regulation of nuclear enzymes in plants. Regulatory agents such as light, hormones and polyamines can stimulate kinases or phosphatases that control nuclear protein phosphorylation and they can modulate the activity of as yet unidentified enzymes required for transcript synthesis and/or stabilization. This essay summarizes current findings and discusses the advantages and pitfalls of using isolated nuclei to investigate how nuclear functions are controlled.

ISSN:0265-9247    

DOI:10.1002/bies.950050307

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

年代:1986

数据来源: WILEY

摘要:

AbstractTheamdS gene ofA. nidulanshas proved extremely favourable for the isolation of mutations affecting gene regulation. Trans‐acting regulatory genes involved inamdS induction by small molecular weight effectors have been identified– amdR (ω‐amino acids)facB (acetate) and amdA (acetate). Another gene, the areA gene, has properties expected of a major activator gene involved in nitrogen metabolite repression ofamdS. All of these regulatory genes are also involved in the control of various other functions encoded by structural genes unlinked toamdS. Mutations in the 5′‐region adjacent toamdShave been isolated and allow the identification of independent cis‐acting sequences which are the target sites for the regulatory genes. The involvement of these sequences in regulatory product binding has been deduced from titration studies using transformants containing multiple copies of the 5′ sequences. A combination of genetics and molecular analysis is allowing a detailed characterization

ISSN:0265-9247    

DOI:10.1002/bies.950050308

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe extracellular matrix does more than just blanket cells; it also provides informational cues which affect a variety of developmental and cellular maintenance activities. The constituents of the matrix provide the fabric for cell motility and cell shape as well as anchorage sites for bioactive factors which directly affect the cell's developmental pattern or mitotic activity. The influence of the extracellular matrix is controlled by the cell's responsiveness to these complex signals. The same matrix component, for example hyaluronic acid, can have completely different effects depending on the cell's lineage and developmental history. The functional interaction between the extracellular matrix and specific cell surface receptors provides cues which affect the control of development and the maintenance and aging events that affect specific cells and tissues.

ISSN:0265-9247    

DOI:10.1002/bies.950050309

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.950050310

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.950050311

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

年代:1986

数据来源: WILEY