摘要:

Tubulin has been identified as a membrane component of nerve synaptosomes and myelin, plasma membranes of platelets, thyroid, and tissue culture cells, brain and liver coated vesicles, mitochondria, and in cilia but not flagella of certain molluscs. Membrane tubulin can differ from cytoplasmic forms in isoelectric point, non‐polar amino acid substitutions, lack of carboxy‐terminal tyrosine, carbohydrate content, and selective ability to reassociate with lipids. This tubulin may function as an attachment site for binding vesicles or plasma membranes to cytoplasmic microtubules, as a source of precursor tubulin at the growing tips of axonemes, or as a component of signal transduction in sensory ci

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1986.tb00467.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The nuclear lamins are directed from the cytoplasm to chromosomes as part of the maturation pathway of the interphase nucleoskeleton. In mitosis, the three polypeptides lamin A, B and C were found in the cytoplasm from prophase until anaphase and shifted to chromosomal surfaces at telophase (Ely, D'Arcy and Jost, 1978; Gerace, Blum and Blobel, 1978). We show here that early events in nucleoskeleton formation could be regulated by extracellular pH. When exponentially growing tissue culture cells and cells arrested in mitosis were exposed to different extracellular pH values, three patterns of distribution of lamins were observed in mitotic cells: exclusively cytoplasmic distribution of mitotic lamins at low pH (6.8 to 7.3); a premature association of a lamin subfraction with metaphase chromosomes at intermediate pH 7.5; a more prominent relocation of lamins onto chromosomes in metaphase and in disorganized metaphase at pH 8.0. Reassembly of lamins occurred at telomeric ends of mitotic chromosomes followed by a lateral fusion to form a nuclear cage. Using immunogold localization, we show that pH‐induced, premature, partial deposition of lamins onto condensed chromosomes may occur prior to the formation of the bilamellar nuclear envelope. These results suggest that the pH‐induced redistribution of lamins acts to trigger early events of mitosis to interphase transit

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1986.tb00468.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Ovulated alcohol‐activated or inactivated mouse oocytes were fused with mouse thymocytes. Activated oocytes react to the presence of foreign nuclei by forming in the peripheral cytoplasm incorporation cones. In this region the cell membrane is smooth and a cortical layer of thin filaments underlies it. It resembles the fertilization cone. In non‐activated oocytes a layer of thin cortical filaments of the same thickness is formed over the foreign chromatin but the surface protuberance (cone) is absent. These results suggest that the cortical alteration in the oocyte architecture may be a general reaction of the oocyte surface to various chromatins introduced, not only to sperm chromatin. The role of oocyte activation in the evolution of these cortical changes is discus

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1986.tb00469.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Two populations of phagocytic cells from trehalose dimycolate‐elicited mouse peritoneal cells are demonstrated by flow cytofluorometry, using two fluorescent probes excited at the same wavelength (488 nm). Liposomes containing diethylenetriaminepentaacetate daunorubicin conjugate (maximum emission wavelength: 590 nm) allow the discrimination of phagocytes and non‐phagocytic cells. Among the phagocytes, an activated population is revealed by a cell‐associated fluorescence of the oxidation product of dichlorofluorescein diacetate (maximum emission wavelength: 52

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1986.tb00470.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Lysosomal arylsulfatases A and B (aryl‐sulfate sulfohydrolases, EC 3.1.6.1) from horse leukocytes were purified about 680‐fold and 70‐fold, respectively, starting from a crude extract of the azurophil and specific granules of leukocytes, by affinity, ion exchange, and gel filtration chromatography. Purified arylsulfatase A displayed anomalous kinetics, a pH optimum at 5.2, an isoelectric point at 4.3, and a Km value for p‐nitrocatechol sulfate (pNCS) of 0.37 mM. This enzyme was found to exist in two association states depending on pH: a high molecular weight form at pH 5.0 and a low molecular weight form at pH 7.5. Arylsulfatase B displayed normal kinetics, a pH optimum at 5.8, two isoelectric points at pH 8.6 and 8.9, and a Km value for pNCS of 3.38 mM. The thermostability of the two enzymes was different: arylsulfatase B was found to be more stable than arylsulfatase A. Arylsulfatase A was inhibited by sulfate, sulfite, silver, magnesium, manganese and calcium ions and arylsulfatase B by chloride, sulfate, sulfite and silv

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1986.tb00471.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Ultrastructural morphometry (point‐counting method) was used to evaluate stereological parameters of rough endoplasmic reticulum (RER), Golgi complex, secretory granules, mitochondria and lysosomes of Rana ridibunda pituitary corticotropic (ACTH) cells in animals subjected to constant environmental conditions (CEC) in relation to temperature and photoperiod. During this experiment, corticotropic cells are particularly sensitive to the effects of changes in environmental conditions in such a way that they course through a phase of RER and Golgi complex hypertrophy after 7 days on CEC and a phase of enhancement in the amount of secretory granules (the 11th day). After 15 days on CEC, the cells seemingly recuperate almost all the control evaluate parameters. These results strongly suggest that, in frog kept in captivity, ACTH cells play an important role in the acclimation process to new constant environmental condition

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1986.tb00472.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The wound healing process of frog skin fragments in epibolic cultures has provided information on FN localizations during the migration of keratinocytes. Mainly two FN localizations were studied by indirect immunodetections: Epidermal localization around keratinocytes which have acquired a fibroblastic shape. Dermal localizations of the sectioned collagen of the stratum spongiosum and stratum compactum detected at the beginning of the culture. Both localizations were observed in this epibolic wound healing process during 6 hr and 24 hr in culture and showed a differential sensitivity to cycloheximide (CHX). It was worth noting that fibronectin was permanently detected in the subcutaneous tissue of non‐cultured or cultured skin fragments with or without CH

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1986.tb00473.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Calcitonin mRNA was detected in human medullary carcinoma using an in situ hybridization technique. This specific and reproducible method could lead to a better functional characterization of medullary carcinoma and should allow the definition of new prognosis factors in medullary thyroid cancer.

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1986.tb00474.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY