摘要:

The functional and structural changes induced by apical wheat germ agglutinin (WGA) 100 μg/ml exposure on frog urinary bladder have been investigated and the possible correlation between these effects discussed. Bladders, apically exposed to WGA for 30 min to 3 hr exhibit a marked reduction of their response to antidiuretic hormone (ADH) challenge and of their hydrosmotic reactivity. Structural changes triggered by WGA trreatmentare: 1. apical invaginations of the plasma membrane, interpreted as endocytotic in nature, taking into account the results of carbohydrate cytochemical detection and horseradish peroxidase (HRP) exposure: 2. cytoskeleton disorganization and microvilli collapse. These phenomena do not interfere with cortical granule traffic and are independent of ADH challenge: they occur in ADH‐stimulated bladders as well as in bladders at rest. These findings could be interpreted as follows: binding of the divalent lectin WGA to its coat specific receptors would induce changes in the apical membrane structure which in turn could provoke disorganization and disruption of apical cytoskeletal elements associated with plasma membrane. Reduction of bladder response to ADH challenge could result from a reduced recyling of aggrephores, as they are associated with cytoskeletal elements in the subapical cytoplasm. Collapse of microvilli and endocytotic events also could result from apical cytoskeleton disruption, as microvilli are sustained by bundles of actin filaments interconnected with apical cytoskeleton filaments and as plasma membrane is associated with apical cytoskeleton. However, these two last events evidently occur in ADH‐challenged or non‐challenged bl

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1989.tb00852.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Sulfhydryl (SH) reactive reagents, such as cosin derivatives, have been found to be useful in labelling water pathways in red cells. In the present study we used an impermeable SH‐reagent, a fluorescent maleimide analogue EMA (eosin‐5′‐maleimide), in order to identify proteins involved in water permeability response to antidiuretic hormone (ADH).We observed that: 1) EMA (1 mM) mucosal pretreatment did not modify either the basal water flux or the subsequent ADH‐induced hydrosmotic response; 2) EMA added to the mucosal bath at the maximum response to ADH, significantly decreased net water flux by about 40%; similar results were obtained when 10−5M forskolin was used as a hydrosmotic agent. These results suggest that the inhibitory effect of EMA occurs at a post cAMP step, possibly at the level of the sulfhydryl groups of the water channels themselves.Fluorescence distribution in SDS‐PAGE of Triton X‐100 extracted proteins from bladder labeled with EMA in both control conditions and under ADH stimulation allowed us to identify apical membrane proteins, labeled during ADH stimulation and not labeled in water impermeable controls. Of particular importance are four proteins of 52, 32–35, 26, 17, kDa. These polypeptides are probably involved in ADH‐stimulated water transport and may be components of

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1989.tb00853.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Quail oviduct development is controlled by sex steroid hormones. Estrogens (E) induce cell proliferation, formation of tubular glands by epithelial cell evagination and cell differentiation. Progesterone (P) strongly increases the secretory process in E‐treated quails, but inhibits cell proliferation, cell evagination and differentiation of ciliated cells. The balance between E and P is critical for harmonious development of the oviduct.After 6 daily injections of two doses of estradiol benzoate (10 or 20 μg/d) and high doses of P (4 mg/d), tubular gland formation by epithelial cell evagination was inhibited, while epithelial cell proliferation occurred, as shown by the height of the villi and the increase in DNA.Secretory processes were strongly stimulated. Ovalbumin, a tubular gland cell marker and avidin, a mucous cell marker, were localized by immunofluorescence and immunogold labeling. Ovalbumin was localized only in the rudimentary tubular glands, whereas avidin was dispersed throughout the secretory cells.High doses of progesterone inhibited tubular gland cell proliferation, disturbed the distribution of avidin and inhibited differentiation of ciliated cells. Ovalbumin synthesis occured only in epithelial cells which were evaginated despite the hyperstimulation. Ovalbumin gene expression appeared highly dependent upon the cell positi

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1989.tb00854.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The localization of progesterone receptor (PR) in the quail oviduct was investigated before and after the onset of sexual maturation using an immunohistochemical technique. PR was revealed exclusively in nuclei of target cells whatever the hormonal state of the tissue (immature or not, pretreated or not with progesterone).In the immature or ovariectomized quail oviduct, PR was principally localized in the undifferentiated epithelial cells; some mesothelial cells and a very few stromal cells expressed the PR. Only 40–45% of the epithelial cells were immunoreactive. These positive cells were mainly localized in the furrows of the villi where further evagination of the epithelium will occur to form the tubular glands.The onset of sexual maturation was accompanied by an increase of the proportion of positive epithelial cells and stromal cells. In estradiol‐treated animals, more than 90% of the tubular gland cells were strongly stained while only 40% of the luminal epithelial cells were immunoreactive.Our results show that there are two subpopulations of epithelial cells: those expressing the PR before the onset of sexual maturation even in ovariectomized quails (constitutive expression) and those expressing the PR during sexual maturation or after estrogen injection (inductive expression). These results, associated with previously published studies dealing with the cytodifferentiation of epithelial cells during natural development or after various hormonal treatments in ovarectomized animals, suggest that the first are the progenitors of tubular gland cells, and the second the progenitors of ciliated and goblet cells. In stromal cells, PR expression is also inducui

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1989.tb00855.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Farnesylacetone (C18 H30 0) is a male hormone extracted from the androgenic gland of crab,Carcinus maenas. Appropriate enzymatic assays, as well as spectrophotometric studies, indicate that micromolar concentrations of farnesylacetone interact with the electron transport pathway of rat liver mitochondria. By the use of artificial electron donors and electron acceptors, it is shown that farnesylacetone immediately inhibits the electron transfer within complex I (NADH ubiquinone reductase activity) and complex II (succinate ubiquinone reductase activity). It is proposed that farnesylacetone could interact with these two complexes of the respiratory chain at the level of the iron‐sulfur centers implicated in the dehydrogenase activities. These observations are compared with the results obtained with terpenic molecules which interact with mitochondrial respiratio

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1989.tb00856.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

During prolonged intoxication with beryllium sulphate, intranuclear beryllium‐rich structures (IBRS) develop mainly in the cells of the convoluted tubules of the kidney. These structures are constituted by the accumulation of dense granules approximately 20 nm in diameter. The present work shows: 1) by electron probe microanalysis that IBRS are rich in phosphorus and calcium, and 2) by high resolution ion microanalysis that the granules are rich in beryllium and proteins. Staining with thallium alcoholate and regressive staining with ethylenediaminetetraacetate (EDTA) seem to demonstrate the presence of ribonucleoproteins in the granules. But the richness in calcium and phosphorus makes it difficult to interprete cytochemical reactions based on thallium and lead because complexes can be formed between calcium and thallium or lead, and between phosphorus and lead. Extraction with EDTA and digestion with RNase carried out on floating slices fixed with glutaraldehyde and embedded in glycol methacrylate show that: 1) the positive response of IBRS to cytochemical techniques used seems due solely to calcium; 2) the RNase forms a stable complex with a constituent of the granules that could be the highly phosphorylated acidic protein that binds preferentially to beryllium described by Parker and Steven

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1989.tb00857.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The microvessels of the rat subfornical organ (SFO) are heterogeneous: those of the caudal part lack a blood‐brain barrier (BBB) unlike those of the rostral part. The astroglial environment of these microvessels has been studied by combining an immunocytochemical technique employing an anti‐GFAP (glial fibrillary acidic protein) antiserum with the morphological detection of a barrier to the protein‐silver complex.All the SFO microvessels are surrounded by astrocytes characterized by a tumescent aspect; however, the relative proximity between the astrocytic feet and the endothelial cells varies considerably. The capillaries provided with a barrier (rostral SFO) are contiguous with the astrocytes from which they are only separated by a basement membrane. The capillaries devoid of BBB (caudal SFO) are surrounded by a pericapillary space that keeps the astrocytes at a short distance (capillaries with a very rich vesicular entothelium) or at a long distance (capillaries with a fenestrated endothelium).The astrocytes are absent in the choroid plexus where all microvessels are fenestrated and lack a barrier.These data suggest that the astrocytes release one or more signals which in their vicinity inhibit the expression of endothelial morphological characteristics (fenestrations, vesicles) responsible for the leakage of plasmatic proteins from the blood to the cerebral parenchyma of the circumventricular o

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1989.tb00858.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The presence in the marine wormNereis diversicolorof a low molecular mass protein with the capacity to bind cadmium has been previously demonstrated [5].Poly(A)+‐mRNA were extracted from coelomocytes ofNereis diversicolorand were translated eitherin vitro, using a rabbit reticulocyte lysate, orin vivointoXenopuslaevis oocytes. Analysis of synthesized polypeptides by enzyme‐linked immunosorbent assay (ELISA) and by Western blotting, using a specific monoclonal anti‐MP II antibody, showed that this metalloprotein was translated both inin vitroandin vivotranslation systems, with an apparent molecular mass of 11–13 kDa. Two other products, with 26.5 and 28 kDa molecular mass, cross‐reacted with the monoclonal anti‐MP II antibodies. The present work confirms that coelomocytes are sites of important synthesis of

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1989.tb00859.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

InGregarina blaberaeaMr= 47 000 and aMr= 260–240 000 doublet polypeptides reacted in immunoblotting: i) with a polyclonal monospecific rabbit antibody to frog muscular actin, a monoclonal anti‐actin antibody against chicken gizzard; and ii) with polyclonal and monoclonal antibodies to human erythrocyte β‐spectrin, respectively. TheMr= 47 000 actin‐like protein is associated with the ghost and a contractille cytoplasmic extract. The presence of an actin‐like protein inGregarinaandLecudinaand its cellular distribution in the cortex indicated that the gliding movement might involve an actin‐myosin system in contrast to previous studies. Immunofluorescence showed clear differences between the anterior part ofGregarinaandLecudinawhich illustrated the high cell polarity of these protozoa. TheMr= 260–240 000 doublet was detected in SDS‐PAGE fromG. blaberaetrophozoite ghosts but not in the cytoplasmic extracts or in extracts from sexual stages, indicating that the presence of these spectrin‐like proteins is stage‐dependent. Visualization of theMr= 260–240 000 by immunofluorescence showed clear species differences, with rings arranged perpendicular to the longitudinal narrow folds ofG. blaberae, with longitudinal lines underlying the folds ofL. pellucidaand with lines separating the large folds ofSelenidium pendula. The cellular distribution is consistent with a stabilizer function of the spectrin‐like proteins in the scaffolding of the cortex of gregarines according to the high diversity of the cell‐shape and the cell motility systems in gregarines. The presence of spectrin‐like proteins in protozoa and particularly in parasites from primitive arthropods indicated that ancestral spectrin genes c

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1989.tb00860.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The first aflagellate and immotile Coleopteran spermatozoon is described in a group of species belonging to the family Ptiliidae. The mature spermatozoon is devoid of flagellum, centrioles and mitochondria, includes a three‐layered acrosomal complex (extraacrosomal layer, acrosome and perforatorium) and a long nucleus made up of two regions of different densities. A compact submembranary capsule and a thick glycocalyx are also present. Motility organelles are absent during the whole spermiogenesis, which is not regressive. The new structures peculiar for this type of sperma are designed for protection. No other sperm models with these characteristics have been described so fa

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1989.tb00861.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY