摘要:

Summary—Among protein serine/threonine kinases, the CDC2 proteins are both well characterized as protein serine/threonine kinases and are functionally involved in the control of cell division. Protein serine/threonine kinase sequences were analysed using Fourier transform of the coded sequences. Characteristic code/frequency pairs were extracted from a set of well defined protein serine/threonine kinases. The characteristic frequencies 0.179, 0.250 and 0.408 distinguished protein serine/threonine kinases from proteins which did not have the biological activity. Pertinent patterns in the sequence, responsible for the code/frequency pairs detection were searched and found to be correlated with the putative catalytic domain of the proteins.Protein serine/threonine kinases involved in cell division control, CDC2 protein kinases, were compared to the other protein serine/threonine kinases. Specific code/frequency pairs were extracted from the sequences and could be related to the function or regulation of the kinases in cell division. Two CDC2 related proteins CDC2(Mm) from mice and CDC2(Gg) from chicken were shown to fit well with the CDC2 proteins, whereas KIN28, PHO85 and PSKJ3, which skare sequence homology but not functional activity with the CDC2 proteins, were clearly excluded from the CDC2 proteins by the characteristic code/frequency pairs. Pertinent patterns in the CDC2 proteins were analysed and mapped on the CDC2 related protein sequences. Four patterns were correlated with the code/frequency detection and therefore, could be associated to the regulation of the CDC2‐related prote

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90354-6

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—Dog embryo kidney cells transformed by the human cytomegalovirus (HCMV) were obtained after non‐permissive infection or transfection with viral DNA digested by restriction endonucleaseEcoR I. The transformed cells, growing rapidly and showing an unlimited division potential, could use medium with only 2% serum for growth, contained nuclear virus antigens, and formed small colonies (<0.2 mm) in agarose. From 40 mice inoculated with transformed canine cells, only one eventually developed a tumor. Results indicate that dog cells are immortalized but not tumorigenically transformed by the human cytomegalovi

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90355-7

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—The mole‐cricket spermatozoon(Gryllotalpa gryllotalpa)has a motile anterior tail region and an immotile posterior region. The posterior portion appears stiff and its microtubular doublets and central singlet microtubules are swollen, apparently due to an excess of material within them. In particular, doublet number 6 is of an unusually large size. The general organization of the axoneme is also modified by a loss of dynein arms and spokes in the posterior portion. When studied by a fixation technique that involves tannic acid to outline the protein molecules and PA‐TCH‐Ag method for staining polysaccharides it could be seen that the microtubular doublets and accessory microtubules contain rounded globules surrounded by polysaccharides. The arrangement of protofilaments within the microtubular walls is visible both in the anterior tail region with normal doublets and in the posterior region with degenerated d

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90356-8

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—This paper reports the observation of intermitochondrial junctions (IMJ) with a periodicity of 15.4 ± 0.65 nm in peripheral blood lymphocytes of healthy subjects. The percentage of IMJ‐containing cells appears constant (about 10% of examined lymphocytes) and is independent of the delay of fixation. Immunogold staining reveals that lymphocytes with IMJ exhibit a T‐phenotype. IMJ have been reported in other types of tissues but, to our knowledge, have not been previously described in the blood cell. The signification of these structures is dis

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90357-9

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—The mitogenic response of human lymphocytes was found to be markedly reduced in weightlessness conditions as compared to normal gravity. One possible explanation is that due to the non‐existent sedimentation in space the lymphocytes could not adhere and spread on a substratum. Thus, we investigated the effect of substratum adhesiveness on lymphocyte responsiveness by reducing and blocking cell adhesion with poly‐HEMA in a simple on‐ground system. Lymphocyte adhesiveness was assessed by measuring the proportion of non‐adhesive, slightly, and strongly adhesive51Cr‐radiolabelled cells on uncoated and poly‐HEMA coated plastic. The amount of cell spreading on surfaces with varying adhesiveness was determined by measuring the area of cells. Cells grown on medium and thick poly‐HEMA films were rounded in shape. By contrast, on tissue culture plastic, they showed clear signs of spreading. The mitogenic response of lymphocytes grown on thick poly‐HEMA films was reduced by up to 68% of the control (tissue culture plastic). Interferon‐γ production was virtually nil when the cells were grown on the least adhesive substratum. These results show that activated lymphocytes need to anchor and spread prior to achieving an optimal proliferation response. We conclude that decreased lymphocyte adhesion could contribute to the depressedin vitrolymphocyte responsiveness found in the microgravity condit

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90358-A

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—The ultrastructure of theDrosophila subobscurachromosome regions around the breakpoints of the complex E1 + 2 + 9 + 12gene arrangement was analyzed. This overlapping inversion is formed by the association of the E1, E2, E9, and E12simple inversions. Ultrastructure of sections involving 58D/59A, 61C/D, 62D/63A, 64B/C, 67A/B, and 68B/C breakpoints on Estchromosomes were compared with the ultrastructure of sections involving 58D/68B, 62D/64C, 59A/63A, 64B/68C, 67B/61C, and 67A/61B breakpoints on E1 + 2 + 9 + 12chromosomes. No detectable changes of structural organization on banding patterns induced by the E1 + 2 + 9 + 12inversion were found. Ultrastructural analysis of the two E12breakpoints has, however, facilitated the analysis of the left boundary of E12inversion. Accordingly, we propose 61B/C as a new breakpoint instead of 61C/

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90359-B

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—The occurrence of candidiasis in cancer patients who undergo chemotherapy requires the interrelation ofCandida albicansand the antimitotic drug Adriamycin (ADM) which is well known as an intercalating agent. The whole yeasts were not affected by 2 h of contact with the drug at 10−4M neither for their growth curve nor for their ultrastructure, despite the presence of free ADM on their surface. Spheroplasts displayed a delay in their growth and exhibited altered nucleoli with segregation of their granular and fibrillar components. The modified emission spectrum of ADM, determined by spectrofluorometry, corresponded neither to the free ADM nor to the DNA‐bound drug, but it could be related to a metabolite of the drug. The cell wall appeared to be one of the main sites for ADM resistance ofCandida albicansin

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90360-F

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—A novel method has been developed using ferric particles to label endosomes, and to achieve magnetic sorting of the various endocytic compartments involved in lipoprotein uptake into cells. Ferric particles conjugated to a receptor‐recognized ligand are bound to coated membrane pits and become internalized into the cytoplasm inside coated vesicles. After apparent fusion of the vesicles to tubular endosomes, the conjugates accumulate and finally discharge into multivesicular endosomes. Pulse‐chase experiments elucidate the pathway of internalized conjugates and allow both early compartments (pinosomes and tubular endosomes) and late compartments (multivesicular endosomes and storage organelles) to be selectively labelled. After ferroloading of the various transport compartments, the cells are homogenized and subcellularly fractionated. Sorting of labelled endosomes is performed by a specially designed “free‐flow” magnetic chamber.Prophase I‐arrested oocytes of the toadXenopus laevisare used as a model system for studying the transport pathway and the conversion of the yolk precursor vitellogenin. It is possible to follow the route of internalization of vitellogenin‐iron conjugatesviacoated pits, coated vesicles, uncoated vesicles, tubular endosomes, multivesicular endosomes, and light primordial yolk platelets. These endosomes shuttle the ferric particles together with the vitellogenin from oolemma to preformed heavy yolk organelles which are still growing. In addition, these various compartments can be isolated according to their function and subjected to electron microscopy and to gel electrophoresis for detailed characterization of their limiting membranes as well as

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90361-6

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—The ultrastructural morphology ofPneumocystis cariniiobtained from nonimmunosuppressed rabbit is described in details. Golgi complex and primary lysosomes ofP cariniiare described here for the first time. They are easily revealed by the zinc iodide‐osmium tetroxide cytochemical reagent. Thiamine pyrophosphatase and β‐glycerophosphatase activities are found in the parasite but cytidine 5′ monophosphatase activity is not observed. A weak thiamine pyrophosphatase activity is detected in Golgi vesicles. An endomembranous saccular structure, present from the intracystic body stage to the precystic stage, apparently plays the role of secondary lysosome. A second type of endomembranous saccular structure, only present in the well developed trophozoitic and precystic forms is also described. The presence of carbohydrates in the cell wall of the parasite was demonstrated by periodic acid‐thiosemicarbazide‐silver proteinate staining and lectin concanavalin A labeling. The development of Golgi vesicles preceded the transition from double‐layered to three‐layered

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90362-7

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—The processes of tubulin paracrystal induction in Chinese hamster ovary cells treated with a Vinca alkaloid,ie, vinblastine or vincristine, and treated simultaneously with one of the Vinca alkaloids and colcemid or colchicine were followed by four different microscopic techniques, in particular by tubulin‐immunofluorescence. Vinca alkaloid alone, in lower concentrations, induced basically tactoid or needle‐shaped (N‐shaped) paracrystals. However, the formation of crystalloid was greatly enhanced by increasing the concentration of Vinca alkaloid. Square or barrel‐shaped (S‐shaped) and hexagonal paracrystals were also commonly induced by simultaneous treatment with a Vinca alkaloid and colcemid or colchicine. Large rectangular paracrystals often displayed fibrillar or lamellar fine structures which ran perpendicular to the long axis but tended to cleave into fragments by spontaneous splitting. Electron micrographs revealed the fine structure of crystalloids to be aggregates of numerous filaments. The growth of paracrystals, particularly N‐shaped crystals, was markedly inhibited when cells were exposed to drug(s) at a low temperature (4°C). We confirmed that both N‐ and S‐shaped paracrystals dissociated rapidly after the culture medium was replaced with fresh, drug‐free medium. Glutaraldehyde‐fixed paracrystals treated with RNase solution were stained with acridine orange, showing a weak orange color. Possible factors involved in the assembly and disassembly of tubulin para

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90363-8

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY