ISSN:1065-6995    

DOI:10.1006/cbir.1994.1120

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThis paper explores the idea that mRNAs are transported between their transcription and processing sites in the nucleus, and their translation and degradation sites in the cytoplasm, by a ‘solid‐state’ process. The underlying assumption is that negligible quantities of mRNA and of mRNA precursors are in solution in vivo. Therefore, mRNA transport cannot be considered as movement in the aqueous phase of the cell. The main lines of experimental evidence supporting this ‘solid‐state’ concept are summarized and related controversies are outlined. Three possible models for a solid‐state transport mechanism are discussed: a direct transfer model, with receptors organized analogously to the components of a multienzyme complex; a motor‐driven model, analogous to synaptic vesicle transport in axons; and an assembly‐driven model which assumes net movement along a fibril resulting from differential activities at the poles. Qualitative evaluation indicates that each of these models has characteristic advantages and disadvantages. The possibility that other nucleocytoplasmic transport processes might operate by solid‐state mechanisms i

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1121

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTA confluent endothelial monolayer can be induced to form vascular tubes in response to collagen. We investigated possible mechanisms of collagen‐induced tube formation by using antibodies to the VLA‐2 integrin receptor and protein kinase C inhibitors. Pre‐incubation of cells with anti‐VLA‐2 (which recognises both the α2 and β1 chains) and AK7 (which recognises only the α2 chain) showed a dose‐dependent inhibition of tube formation. At 50 μg/ml, anti‐VLA‐2 completely inhibited collagen‐induced tube formation, whereas AK7 caused only partial inhibition. Both chlorpromazine and trifluoperazine, at concentrations of 10μM, prevented tube formation (>40% inhibition), In summary, the VLA‐2 integrin receptor plays a role in the induction of tube formation by type I collagen. Protein kinase C may be activ

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1122

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTCell proliferation rates of diagnostic marrow aspirate cells of 21 children with Acute Lymphoblastic Leukaemia and 16 controls were compared using immunocytochemical labelling of PCNA and Ki‐67 antigen as assessed by Confocal Laser Scanning Microscopy.The results showed an unexpected, highly significant degree of dissociation between PCNA and Ki‐67 expression in ALL blasts. The PCNA labelling indices of ALL patients were significantly increased (mean 44, range 24‐77) compared with normal reactive marrow cells (mean 13.8, range 4‐26) (p<0.000001, Mann Whitney U two tailed test), suggesting an abnormal commitment to proliferation. Ki‐67 expression was raised to a lesser extent in ALL cells (mean 14.8, range 1.2‐35) when compared to non‐malignant proliferations (mean 6.6, range 1.7‐25) (p<0.02). PCNA/Ki‐67 LI ratios in ALL (mean 7, range 1.1‐35) were higher than in controls (mean 2.7, range 1.04‐6.5, p<0.09).As cell proliferation rates actually achieved in the bone marrow do not differ as strongly as suggested by the extreme difference in PCNA labelling, a pathological dissociation of PCNA / Ki‐67 expression exists, sug

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1123

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTWe have demonstrated the localization of ecto‐Ca‐ATPase and 5′‐nucleotidase activity in the caveolae of smooth muscle cells of guinea pig vas deferens and the ileum longitudinal muscle strips with a cerium‐precipitation enzyme‐cytochemical method. The activities seemed to be strongest in the caveolae. Since the simultaneous presence of the 5′‐nucleotidase activity supports the hypothesis that this ecto‐Ca‐ATPase activity does not have a pump function, but, together with 5′‐nucleotidase, may play a role in neurotransmission, these specific membrane invaginations, the caveolae, have a functional relationship with transverse tub

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1124

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTDense populations of Urceolaria mitra (Cilophora, Peritrichid) were observed on the surface of the planarian Polycelis tenuis (Platyhelminthes Turbellaria). Although the epizoite was primarily confined to the anterior dorsal surface of the planarian, heavily infested individuals had peritrichs attached to the posterior, lateral and ciliated ventral surfaces. Unique profiles of the skeletal ring (aboral disc) in relation to the host surface showed that some local erosion of planarian epithelium occurs. Outer and inner rows of cilia extended anti‐clockwise around the peristomal disc. The cilia ran for one and one‐eighth turns around the disc and overlapped in the form of a spiral when the protist was extended and feeding. The cilia appeared to beat in metachronal rhythm and exhibited a wavelength and amplitude of approximately 10μm. Regular striations having a periodicity of 1μm were observed in the periostimal membrane. A posterior or basal circlet of locomotor cilia was also observed and freeze fracture revealed an internal arrangement of microvilli, cilia and reticular memb

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1125

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTA specific protein with an estimated molecular weight of 260 kDa was found to be synthesized and secreted into the incubation medium by rat uterus only during the estrus stage of the cycle. This secreted uterine protein was designated as estrus stage‐specific protein (ESP). ESP was not produced by pregnant, lactating or immature pup rat uteri. Estradiol administered to ovariectomized rats induced production of ESP which was blocked by the antiestrogen, ICI 182, 780. The present results show that the synthesis and secretion of ESP is regulated by estradiol and this protein maybe involved in blastocyst implantatio

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1126

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThe dependence of blastocyst development on the extracellular Na+/K+ratio was investigated in an in vitro system. Hatching and outgrowth of mouse blastocysts was enhanced at Na+/K+ratios between 3 and 10 compared to the ratio of about 25 typical for most culture media and serum. At a Na+/K+ratio of 2, blastocyst hatching and outgrowth were inhibited. The requirement of blastocyst development for relatively high extracellular K+concentrations agrees with the fact that K+concentrations in oviduct and uterine secretions are higher than in serum. The findings can also be relevant in optimizing in vitro culturing techniques for blastocysts.

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1127

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1128

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1129

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY