ISSN:1065-6995    

DOI:10.1006/cbir.1996.0001

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe precise location of the SRY gene on the human Y chromosome has been revealed through studies of sex reversal cases involving deletion, cross‐linking and mutations of the SRY gene. Its DNA sequence and mechanism of action are being understood. Similarity of SRY with Sry of mice and its interaction with other genes in male sex determination are discusse

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0002

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractA newly developed method using rat lymph nodes provided us with substantial amounts of high quality monoclonal antibodies. The method has characteristic features, a single injection of an emulsified antigen via the rat's hind footpads is sufficient for immunization. Enlarged medial iliac lymph nodes can be used for cell fusion to produce hybridomas 2 weeks and later after the antigen injection. The production frequency of target hybridomas is about 10 times higher than that of a conventional spleen method. Our current knowledge about the production of monoclonal antipeptide antibodies and monoclonal nephritogenic autoantibodies by the method is described.

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0003

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe different types of fibres of the collagenous and elastic systems can be demonstrated specifically in tissue sections by comparing the typical ultrastructural picture of each of the fibre types with studies using selective staining techniques for light microscopy. A practicalmodus operandi, which includes the recommended staining procedures and interpretation of the results, is presented. Micrographs and tables are provided to summarize the differential procedures. Reticulin fibres display a distinct argyrophilia when studied by means of silver impregnation techniques, and show up as a thin meshwork of weakly birefringent, greenish fibres when examined with the aid of the Picrosirius‐polarization method. In addition, electron‐microscopic studies showed that reticulin fibres are composed of a small number of thin collagen fibrils, contrasting with the very many thicker fibrils that could be localized ultrastructurally to the sites where non‐argyrophilic, coarse collagen fibres had been characterized by the histochemical methods used. The three different fibre types of the elastic system belong to a continuous series: oxytalan—elaunin—elastic (all of the fibre types comprising collections of microfibrils with, in the given sequence, increasing amounts of elastin). The three distinct types of elastic system fibres have different staining characteristics and ultrastructural patterns. Ultrastructurally, a characteristic elastic fibre consists of two morphologically different components: a centrally located solid cylinder of amorphous and homogeneous elastin surrounded by tubular microfibrils. An oxytalan fibre is composed of a bundle of microfibrils, identical to the elastic fibre microfibrils, without amorphous material. In elaunin fibres, dispersed amorphous material (elastin) is intermingled among the mic

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0004

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractSome general molecular mechanisms underlying development are described. Namely: those involved in the differentiation of the R7 receptor inDrosophilaembryonic retina; those involved in the determination of embryonic axes and in polar cell differentiation, inDrosophila; those involved in the determination of the AB and P cell lineage and in vulva differentiation inCaenorhabditisembryos.

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0005

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractMammalian eggs are surrounded by two egg coats: the cumulus oophorus and the zona pellucida, which is an extracellular matrix composed of sulfated glycoproteins. The first association of the spermatozoon with the zona pellucida occurs between the zona glycoprotein, ZP3 and sperm receptors, located at the sperm plasma membrane, such as the 95kDa tyrosine kinase‐protein. This association induces the acrosome reaction and exposes the proacrosin/acrosin system. Proacrosin transforms itself, by autoactivation, into the proteolytical active form: acrosin. This is a serine protease that has been shown to be involved in secondary binding of spermatozoa to the zona pellucida and in the penetration of mammalian spermatozoa through it. The zona pellucida is a specific and natural substrate for acrosin and its hydrolysis and fertilization can be inhibited by antiacrosin monoclonal antibodies. Moreover, inin vitrofertilization experiments, trypsin inhibitors significantly inhibits fertilization. The use of the silver‐enhanced immunogold technique has allowed immunolocalization of the proacrosin/acrosin system in spermatozoa after the occurrence of the acrosome reaction. This system remains associated to the surface of the inner acrosomal membrane for several hours in human, rabbit and guinea‐pig spermatozoa while in the hamster it is rapidly lost. In the hamster, the loss of acrosin parallels the capability of the sperm to cross the zona pellucida. Rabbit perivitelline spermatozoa can fertilize freshly ovulated rabbit eggs and retain acrosin in the equatorial and postacrosomal region. These spermatozoa also show digestion halos on gelatin plates that can be inhibited by trypsin inhibitors. This evidence strongly suggests the involvement of acrosin in sperm penetration through the mammalian zona. Recently it was shown, however, that acrosin would not be essential for fertilization. It is likely, then, that such an important phenomenon in the mammalian reproductive cycle would be ensured though several alternative mecha

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0006

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe histone gene is a paradigm for transcriptional control at the G1/S phase transition point in the cell cycle. The histone gene promoter provides a blueprint for integration of regulatory signals which mediate responsiveness to factors controlling competency for cell cycle progression at the initiation of DNA replication. The downregulation of proliferation at the onset of differentiation is accompanied by and functionally linked to modifications in protein—DNA and protein—protein interactions at histone gene promoter regulatory elements. Chromatin structure, nucleosome organization and gene‐nuclear matrix interactions facilitate crosstalk between regulatory sequences and targeting of transcription factors to cognate binding do

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0007

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractIn recent years, NO, a gas previously considered a potentially toxic chemical, has become established as a diffusible universal messenger mediating cell—cell communication throughout the body. In mammals, NO is a recognized mediator of blood vessel relaxation that helps to maintain blood pressure. In the central nervous system NO acts as a non‐conventional neurotransmitter and participates in the establishment of long‐term plasticity required for memory formation. In addition, NO is responsible for some parts of the host response to sepsis and inflammation and contributes to certain disease states. A number of strategies have emerged with regard to a pharmacological control of pathological NO overproductions. This review will discuss these novel therapeutic approaches that may provide new means for clinical med

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0008

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractMorphogenesis is an old, and one of the latest, fascinating fields in biological science and a huge number of papers on molecular mechanisms underlying it have been published. But most of the works and reviews on these mechanisms pertain to molecules of, as it were, the planning or design of morphogenesis, such as morphogens and homeodomain proteins. In this review, I will describe the function of extracellular matrix (ECM) and other cell adhesion molecules in morphogenesis as that of actual morpho‐creating molecules, morphocreators, and discuss their roles as positional information‐pertaining molecu

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0009

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractDuring the last years we have examined structure—function relationships in the Na+/K+‐ATPase with respect to interactions of the external cations with the pump molecule. We have analysed in voltage‐clamp experiments the influence of extracellular Na+and K+on the current generated by Na+/K+‐pumps expressed inXenopusoocytes. Our results demonstrated that external Na+and K+have to pass an access channel in the electrical field of the membrane to reach their binding sites. This external access, therefore, is voltage‐dependent and is affected by lysine residues within the cytoplasmic N‐terminus, by glutamic acid residues in intramembraneous domains, the ouabain sensitivity and phosphorylation by prot

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0010

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY