摘要:

Summry—Numerous studies have been published these last few years on the involvement of MAP kinases in signal transduction reflecting their importance in cell cycle and cell growth controls. The identification and the characterization of their direct upstream activator has considerably enlarged our understanding of the phosphorylation network. The MAP kinase kinases (MAPKKs) are dual‐specificity protein kinases which phosphorylate and activate MAP kinases. To date, MAPKK homologues have been found in yeast, invertebrates, amphibians, and mammals. Moreover, the MAPKK/MAPK phosphorylation switch constitutes a basic module activated in distinct pathways in yeast and in vertebrates. MAPKK regulation studies have led to the discovery of at least four MAPKK convergent pathways in higher organisms. One of these is similar to the yeast pheromone response pathway which includes theste11protein kinase. Two other pathways require the activation of either one or both of the serine/threonine kinase‐encoded oncogenesc‐Raf‐Iandc‐Mos. Additionally, recent studies suggest a possible effect of the cell cycle control regulatory cyclin‐dependent kinase 1 (cdc2) on MAPKK activity. Finally, MAPKKs seem to be essential transducers through which signals must pass before reachin

ISSN:0248-4900    

DOI:10.1016/0248-4900(93)90138-5

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Summry—Endothelial cells from mouse peripheral lymph nodes were immortalized by cationic liposome‐mediate transfection using a plasmid construct containing both the gene coding for the large T antigen of simian virus 40 and a geneticin resistance gene suitable for selection. A cell line (HECal10) was isolated on the basis of its capacity to specifically bind fucoside carrying glycoconjugates; these cells present the main characteristics of endothelial cells: production of angiotensin converting enzyme and of factor VII‐related antigen. Upon stimulation, they express E‐selectin which binds oligosaccharides containing the Lewisxdeterminant (Fucα3[Galβ4 GlcNacβ3Galβ) and the MECA 79 addressin which is characteristics for the peripheral lymph node high endothelium and is a L‐selectin. HECa10 cells, as well as peripheral lymph node high endothelial cells in primary culture, express a second fucoside binding protein which differs from E‐selectin. Indeed, this new fucoside‐binding protein is constitutively expressed on unstimulated cells while E‐selectin is not. Furthermore, HECa10 cells mediate selective lymphoid cells adhesion in a selectin/addressin‐dependent mechanism, mainly inhibited by MECA 79 antibody and, in a fucose‐binding lectin‐dependent manner, mainly inhibited by th

ISSN:0248-4900    

DOI:10.1016/0248-4900(93)90139-6

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Summry—Adherence capacity to tissue substrate, endocytosis capacity for heterologous proteins, and proteolytic activity were determined in intestinal granulocytes (EGCs) isolated from healthy adult rainbow trout. The percentage of cells that could adhere to a smooth plastic surface increased with increasing incubation time. Endocytosis was effective for heterologous (human immunoglobulin G, IgGh; ovine somatotropin, oST) but not homologous proteins (recombinant trout somatotropin, rtST). The activity of cathepsin D increased significantly after the endocytosis of a heterologous protein. Finaly, the analysis of immunoblots of homogenates of granulocytes incubated in the presence of the two different proteins was used to show the endocytosis and degradation of heterologous proteins. These results show that isolated EGCs can endocytose and degrade heterologous protein

ISSN:0248-4900    

DOI:10.1016/0248-4900(93)90140-A

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Summry—The aim of this study was to localise two ionic S‐phase markers in tissue sections using SIMS microscopy: aluminium as a potential endogenous marker and bromine as an exogenous marker afterin vivoinjection of bromodeoxyuridine (BrdU). This study was performed in an experimental model of hyperplastic proliferation after partial hepatectomy in rat. Aluminium was never detected in nuclei which were positive or negative for tritiated thymidine uptake, as determined by autoradiography in tissue prepared by cryotechniques. In contrast, bromine of BrdU was found in hepatocyte nuclei. However, there was a discrepancy between SIMS bromine images and BrdU immunohistochemistry detection which appears more sensitive. This is probably due to problems of stereology intrinsic to the correlation method which requires serial sections for this multi‐instrumental app

ISSN:0248-4900    

DOI:10.1016/0248-4900(93)90141-Z

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Summry—Spermatogenesis in the primitive marine nematodeSphaerolaimus hirsutus(Chromadoria, Sphaerolaimidae) was investigated by examining the ultrastructure and cytochemistry. Spermatozoa are lenticular cells of about 15 μm in diameter and are devoid of flagellum and acrosome as in other nematodes. In spermatocytes, dictyosomes produced transient structures, the fibrous body‐membranous organelle complexes (FB‐MO). In spermatids, the FBs were arranged as cartwheel spokes, with the FBs in the centre and the MOs at the periphery. The FBs were first made up of parallel fibres and surrounded by a membrane, then, in a later stage, showed a dense central structure with a surrounding vermiculate region and were devoid of membrane. The FBs contain actin as shown by immunofluorescence using a monoclonal anti‐actin antibody and by affinity cytochemistry using fluorescent phalloidin. MOs contained mainly F‐actin as shown by their labelling by phalloidin. In spermatozoa, the MOs were no longer peripheral but arranged on a ring in the central region of the cell and the FBs disappeared to form the cytoskeleton of the cell outer region. It was assumed, by analogy with the ultrastructure of other nematodes, that this cytoskeleton was made up of major‐sperm‐protein (MSP). Labelling of spermatids ofCaenorhabditis elegansalso revealed the presence of actin, but cells and actin spots were very can be distinguished. In the few species in which it has been studied (C elegansandAscaris suum), MSP is thought to constitute in spermatozoa a motile cytoskeleton excluding the presence of actin. However, the present study ofSphaerolaimusshows that the actin cytoskeleton is present during nematode

ISSN:0248-4900    

DOI:10.1016/0248-4900(93)90142-2

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Summry—SaOS‐2 cell line presents osteoblastic characteristics which can be modulated by specific agonists involving also phosphoinositide breakdown. In order to determine whether SaOS‐2 cells display a phosphoinositide signalling system not only at the cytosol‐cell membrane level but also, as recently reported for other cell lines, at the nuclear level, a study has been performed to evaluate the phosphoinositidase C (PIC) activity and to localize different isoforms of PIC in nuclear and cytoplasmic compartments. By immunochemicals methods, and by confocal and electron microscope immunocytochemistry, both PIC β1and γ1have been detected in the nucleus, while only PIC γ1was found in the cytoplasm. A specific association with the inner nuclear matrix has been demonstrated for PIC β1and γ1; this latter resulted, on the other hand, in relationship with cytoskeletal filaments after high salt extraction. These findings suggest that these enzymes are not completely soluble but functionally related with cytoskeletal and nucleoskeleta

ISSN:0248-4900    

DOI:10.1016/0248-4900(93)90143-3

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Summry—Polarisation of polymorphonuclear leukocytes (PMN) is suspension was assessed using three techniques: 1) visual classification; 2) computerized morphometry; and 3) flow cytometry. While visual classification detected the formation, polarisation and type of cytoplasmic extensions produced by PMN, morphometry and flow cytometry detected only the formation of extensions. The area, perimeter and ellipticity were, in general, statistically different for each subtype of PMN‐shape identified by visual classification. Furthermore, the magnitude and direction of changes detected by flow cytometry were affected by the use of erythrocyte lysis (during isolation of the cells) and the fixative used prior to analysis. The findings of this study demonstrate that visual classification is a more sensitive, reliable and appropriate assay of PMN polarisation than current morphometric and flow cytometric meth

ISSN:0248-4900    

DOI:10.1016/0248-4900(93)90144-4

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Summry—Hybridoma cell lines were obtained from mouse splenocytes sensitized to granulosa cells collected from rat ovaries after gonadotropin stimulation. A monoclonal antibody (5G5) was obtained which reacted with granulosa cells and showed a positive reaction with serum‐free conditioned medium containing granulosa cell secreted proteins. Immoblotting of the conditioned medium and light‐ and electron‐microscopic immunocytochemistry of rat ovary show that mAb 5G5 is directed against a 59‐kDa protein which is located on the plasma membrane of granulosa cells. Furthermore, the immunoreactivity of the granulosa cells depends both on the degree of follicle development and on the position of the granulosa cells within the follicles. Strong immunoreactivity was observed in the innermost granulosa cell layers, close to the oocyte and the antral cavity. The results obtained show that mAb 5G5 is a useful marker of a 59‐kDa granulosa cell protein which might be of importance for the follicle and the occyte

ISSN:0248-4900    

DOI:10.1016/0248-4900(93)90145-5

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Summry—1‐[4‐(trimethylamino)phenyl]‐6‐phenylhexa‐1,3,5‐triene (TMA‐DPH), a membrane fluorescence probe, interacts with living cells by instantaneous partition between the external medium and the plasma membrane, where it becomes fluorescent. The corresponding fluorescence intensity is then proportional to the cell surface. On the other hand, once incorporated into the plasma membrane, TMA‐DPH follows this membrane in the constitutive intracellular traffic and behaves as a monitor for endocytosis. Using this tool on L929 synchronized cells, we showed that the endocytosis levels after 30 min uptake of the probe increased from G1 to mitosis, when they abruptly decreased. The cell surface remained constant throughout the cell cycle, except at the beginning of mitosis when

ISSN:0248-4900    

DOI:10.1016/0248-4900(93)90146-6

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

ISSN:0248-4900    

DOI:10.1016/0248-4900(93)90149-9

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY