摘要:

AbstractImmortalization of rodent cells by oncogenes is a complex biological process which involves the abnormal regulation of genes who control cellular proliferation. The role of the cell cycle control genes cdc2, cdc25 and cyclin A in the maintenance of immortalization and in growth arrest was examined in the tsa14, a SV40 T antigen rat embryonic fibroblast conditional for growth cell line. Analysis of RNA expression showed minimal levels of cdc2 mRNA in both proliferating and growth‐arrested tsa14 cells. In contrast, cyclin A mRNA was found downregulated in growth‐arrested tsa14 cells, as well as in senescent primary rat embryonic fibroblasts (REFS). The ability of cdc2, or cdc25, or cyclin A genes to maintain the tsa14 immortal phenotype was also examined by electroporations of these genes into the tsa14 cells. Clones over‐expressing the electroporated cdc2, or cdc25, or cyclin A, or combinations of these genes growth arrested at the non‐permissive conditions similar to controls, thereby suggesting that the expression of these genes alone is insufficient for tsa14 maintenance of immortal

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0020

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractAside from the well known role of angiotensin II (Ang II) in blood pressure regulation and fluid homeostasis, accumulating evidence suggests that the octapeptide hormone also plays a role in growth and development. There are two major classes of Ang II receptors (AT1and AT2) which mediate Ang II action. Both classes are members of the large superfamily of seven transmembrane domain spanning receptors. Fetal tissue express high levels of AT receptors. Throughout fetal and postpartum life, the AT1and AT2tissue distribution changes dramatically. The evolution of each receptor type is distinct and varies according to the organ. Thus, the different patterns of temporal expression of each receptor class could be related to various roles that Ang II may play during development.

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0021

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractCulturing of chick embryo fibroblasts in the presence of colchicine or cytochalasin B with and without concanavalin A (Con A) demonstrated that colchicine induces greater neosynthesis of endocellular type I collagen, whereas cytochalasin B boosts secretion. The effects are modified by the addition of Con A, which increases α2more than a1 chain production.3H‐thymidine incorporation is unaffected by cytochalasin B, but stimulated by colchicine. Con A neutralizes the stimulatory action of colchicine. It would therefore seem that Con A exerts transmembrane control of effects induced by colchicine and cytochalasin B by binding to cell surface receptors and so triggering rearrangement of the cytoskelet

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0022

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe expression of the five muscarinic acetylcholine receptor (mAChR) subtypes (m1–m5) in the vestibular end‐organs and in the primary afferent vestibular ganglia of the human and rat was studied using RT‐PCR from the two tissue populations from both species. In the human, although all five mAChR subtypes were expressed in brain, only the m1, m2, and m5 mAChR subtypes were amplified from both the vestibular ganglia and the vestibular end‐organs, while in the rat, all five mAChR subtypes were expressed. These data suggest that the efferent cholinergic axo‐dendritic and axo‐somatic synapses have a muscarinic component and that there are pharmacologic implications for patients with vestibular

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0023

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractAnnexin I is an abundant protein in U937 cells differentiated towards a macrophagic phenotype. These cells become able to killEscherichia coli, however, the intracellular pathogenBrucella suis, known to interfere with phagosome maturation, multiply in these differentiated cells. We have analysed by confocal and electron microscopy the cellular localization of annexin I during phagocytosis of yeast, non‐pathogenicE. coliand the intracellular pathogenB. suis. Using immunocytochemical detections annexin I was found mainly as patches in the cytoplasm of uninfected cells. Upon phagocytosis of yeast orE. coliorganisms, annexin I rapidly translocated and concentrated around phagosomes. On the other hand, annexin I was never detected around liveB. suis‐containing phagosomes. However, when dead brucellae were used, annexin I did translocate to the periphagosomal region. Our results suggest that annexin I could play a role in the molecular mechanism of phagosome maturation, which is impaired by some intracellular pathog

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0024

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractMCF‐7 cells were co‐transfected with the human HSP27 antisense cDNA and the neomycin resistance gene, included in the constitutive expression vector pSVL, and the phenotypical changes associated with decreased expression of the HSP27 protein were analysed. Three out of 10 neomycin‐resistant clones obtained proliferated normally and showed a normal HSP27 content (Western blot). The seven other clones (designated as αHSP27 clones) were characterized by a dramatic growth inhibition associated with alterations in cellular morphology. Cells became progressively hypertrophied, exhibited lamellar protrusions and tended to lose contact with each other. They also acquired characteristics of secretory cells, namely the presence of numerous refractile granules and secretory canaliculi. Among the αHSP27 clones, two were immunocytochemically analysed for HSP27 content. Both clones were immunonegative for HSP27, contrary to parental cells and neo transfectants. Actin immunostaining in one of these HSP27 negative clones revealed that microfilament organization changed from diffuse to punctate distribution. Our data support the current concept of a role for HSP27 in cell growth and differentiation and further suggests that this might occur through a control on actin polymerization‐depolym

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0025

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractRestriction Endonucleases (REs) may recognize, cleave and remove DNA from fixed chromatin producing specific chromosome banding patterns. However, the modifications produced in the chromatin fibre are not easy to evaluate and compare. The aim of the present investigation was to visualize differences resulting in the texture of the chromatin fibre from metaphase chromosomes after each digestion using digital image analysis (DIA) facilities. To this purpose, metaphase chromosomes derived from a L‐929 mouse cell line were digested with different REs (AluI,HpaII andHaeIII).Since light microscopy does not permit the observation of the chromatin fibre, DIA was performed on digitalized images of metaphase chromosomes under electron microscopy. The application of a LUT (Look Up Table) within the DIA software assigns a colour to each grey level of a digital image. The results obtained using a particular LUT, which permits the discrimination of specific chromatin fibre phenotypes resulting from each digestion, are reported and compared with those obtained under the light microscop

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0026

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0027

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY