摘要:

AbstractThe 5′flanking region of the hsp70‐related gene which is specifically expressed in rat and mouse spermatocytes contains the GGTCAnnnCGACC sequence closely resembling the palindromic consensus ERE (estrogen responsive element, GGTCAnnnTGACC). We used a transient expression assay to study whether this ERE‐like sequence can transfer estrogen responsiveness either to heterologous or homologous promoters linked to a reporter CAT gene. We found that the GGTCAnnnCGACC sequence either as an isolated element or in its natural sequence context does not respond to hormone stimulation in MCF‐7 and Fe33 cells. This observation points to the importance of the T‐nucleotide in a right half‐palindrome of ERE for ligand‐dependent activation of

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1061

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe present study was designed to investigate the adherence mechanism(s) and behaviour of cultured chondrocytes under various culturing conditions, co‐culturing with fibroblasts, or growth in the presence of conditioned medium either of fibroblasts or chondrocytes. The findings obtained indicate that chondrocyte time‐adhesion curves and the final percentiles of attached cells to a plastic substrate are much slower and lower respectively than those of anchorage dependent cell types. The poorest adhesion occurs employing chondrocytes originated from suspension cultures, as compared to chondrocytes grown in monolayers. No interference with chondrocyte adhesion was found by inhibiting the production of proteoglycan (PG). Puromycin and to a lesser degree actinomycin but not cytosine arabinoside interfered with chondrocyte adhesion, suggesting the importance of protein synthesis in this process.The nature of proadhesion modifying molecules in synoviocytes conditioned media and antiadhesive agents in chondrocyte conditioned media suggests that both substances are heat labile, non‐dialyzable, protein containing fa

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1062

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractXenopus egg extract was fractionated by gel‐filtration column chromatography and DNA synthetic activity was examined using double‐stranded DNA as a template. The major activity eluted had an apparent molecular mass of about 300 kDa. Product analyses showed that de novo DNA synthesis occurs with formation of replication bubbles, thereby suggesting that this fraction catalyzes the initiation of DNA replication. Activities of DNA polymerase α‐primase and DNA helicase overlapped with the DNA synthetic activity, but the elution profiles of the enzymes differed from that of the DNA synthetic activity. Therefore, this 300‐kDa fraction may contain a component which differs from the above enzymes yet is essential for initiation of DNA rep

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1063

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractBovine lactoferrin in involuting mammary tissue was identified by immunohistochemistry and tissue explant culture. Immunoreactive lactoferrin was associated with mammary epithelial cells. Immunostaining for lactoferrin increased during involution, in contrast to declining immunostaining of epithelia for the milk‐specific protein β‐lactoglobulin. Immunostaining for lactoferrin also was observed at the basal region of alveolar epithelia, perhaps in association with basement membrane components. Lactoferrin was preferentially synthesized in involuting mammary tissue compared with lactating tissue. Synthesis of lactoferrin in the involuting mammary gland occurs despite the apparent decline in synthesis of milk‐specific pr

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1064

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractUsing CHO‐K1, HeLa S3 and two Walker lines (WR and WS) differentially sensitive to cis‐diamminedichloroplatinum(II) (cisplatin), the survival after exposure to cisplatin, mitomycin C, vinblastine, vincristine or cytosine arabinoside has been determined either of clonogens or of cells rendered polyploid by post‐exposure incubation in the presence of cytochalasin B (CB). It is suggested that the inhibition of cytokinesis by CB permits an assessment to be made of the fraction of damage whose expression is cell division‐related, possibly including that resulting from a loss or malsegregation of genetic material. It was found that the response of polykaryons in comparison to clonogens was both agent‐ and cell line‐dependent. After cisplatin exposure, polykaryon survival (defined as the ability to accumulate at least 16C DNA) declined exponentially with dose and was qualitatively, and to some extent quantitatively, similar to that observed previously after irradiation. In HeLa S3, giant cells induced by 10‐20Gy irradiation in the absence of CB exhibited a radiation dose‐dependent reduction in the relative frequency of highly polyploid cells which was similar to that observed in CB‐in

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1065

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractBoth the biochemical profile and the optical and fine structural localization of acid phosphatase activity in the larval salivary glands of developing Drosophila melanogaster is described. Biochemically, acid phosphatase shows peak activity in the glands of feeding larvae, followed by a marked decline. Directly preceding the onset of cell histolysis however, enzyme activity increases 1.5 fold and is maintained at this level. Histochemically, acid phosphatase activity initially appears as discrete point or lysosomal sources. As development proceeds, an intense and diffuse form of enzyme is seen, accompanying an extremely vacuolated cytoplasm. Ultrastructurally, the enzyme is located in lysosomes, Golgi elements, multivesicular bodies and both within, and on the extracisternal surface of the rough endoplasmic reticulum. This extracisternal or cytosolic form appears directly preceding cell lysis and eventually shows a comprehensive cellular distribution. Large numbers of acid phosphatase positive haemocytes are attached to the basal glandular surface at all developmental stages. In morphologically intact gland cells, discrete extracisternal enzyme activity appears associated with local areas of degradation.

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1066

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe possibility that a growth‐related proteinase may act by degrading a negative growth regulatory protein has been investigated. Proteinase inhibitors which inhibit the enzyme also enhance the accumulation of the growth regulator by human fibroblasts. The negative growth regulator shows a similar specificity of inhibition of cellular growth to inhibitors of the growth‐related protein

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1067

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractNorthern blot analysis of TN mRNA from different human tissues shows two major bands of about 6 and 8 kb which correspond to two different mRNAs generated by alternative splicing of the primary transcript. In liver, pancreas and kidney only the 6 kb TN mRNA was detectable. The highest levels of 8 kb TN mRNA were observed in placenta and skin representing 30% and 52% of total TN mRNA, respectively. In all other tissues tested the 8 kb TN mRNA represented less than 20% of total TN mRNA.

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1068

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractOver 80% of the polysomes in corn endosperm sediment along with protein bodies at 30 xg from seeds ground in cytoskeleton‐stabilizing buffer. The cytoskeleton‐disrupting agents, Tris‐HCl, K+, heparin, and sodium deoxycholate cause polysome release, while protease K and the non‐ionic detergent, PTE, are effective only in the presence of these agents, and RNase is almost without effect. We suggest that many of the polysomes in corn endosperm are associated via their ribosomes, but not mRNA or nascent polypeptides with the actin component of the cytoskeleton and only indirectly with membranes. Corn endosperm homogenates examined under the fluorescence microscope show polysomes coating individual protein bodies and co‐localizing with actin, but no

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1069

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractInvestigation of the relative slowness with which trypsin detaches epithelial cells from their adhesions with a substratum suggests that the adherent surface of the cells is normally rather inaccessible to the enzyme. Trypsinisation of cells through a porous filter allowing access of the enzyme to the underside of the cells greatly accelerated detachment: a result consistent with this explanation.

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1070

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY