摘要:

Summary—The synthesis of a new benzoxazinone derivative suitable to detect early infection of cultured cells with mycoplasmas is described.p‐[β—(7 — dimethylamino 1,4 — benzoxazin 2 — one 3yl) — vinyl] — phenylpropenoic acid was coupled to kanamycin A, an aminoglycoside leading to a cationic fluorescent probe which fluoresces at 600 nm upon excitation at 490 nm. This fluorescent probe is shown to heavily label the glycocallix of all the mycoplasma strains tested which are found to be associated with contaminated cultured cells and to allow an easy and rapid detection of contamination by fluorescence microscopy an

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90365-A

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—The complex organization of the interphase nucleus can be analyzed, by way of thin sectioning and also freeze‐fracture. This approach has previously been utilized in association with image analysis to quantitatively describe the organization of isolated rat liver nuclei and nuclear matrices. The main nuclear domains which, in section, present marked differences due to their electron‐density, can be identified in replicas with more complex procedures, based on the quantitative evaluation of the number of particles per unit area and mainly by using image analysis. A quantitative analysis of the nuclear substructures has been performed by way of image analysis onin situnuclei of freeze‐fractured cells presenting marked differences in the heterochromatin quantity, such as hepatocytes and lymphocytes. The replicated nuclear particles have been classified according to their diameter and the obtained histograms have been quantitatively evaluated. The nuclear domains, heterochromatin, interchromatin, nucleolus, present characteristic ratios among the three main classes of particles; that is, ribonucleoproteins, solenoid filaments and solenoid fibre aggregates. The typical patterns of the nuclear domains can be further stressed by selecting a single class of particles and by examining its topographic localization. While interchromatin and nucleolar domains present a similar quantitative pattern in hepatocytes and lymphocytes, the heterochromatin of lymphocytes contains a significative higher percentage of solenoid aggregates than that of hepa

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90366-B

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—A simple procedure which provides a large yield of isolated ferret ventricular myocytes is described. The enzymatic dissociation was performed by perfusion of the whole heart with the “Langendorff method” at 37°C, without an incubation period. Special attention was given to the period of perfusion with Ca‐free or low‐calcium containing solutions and to the proportion of both collagenase and elastase used. The viability and calcium tolerance of the isolated cells were tested by ultrastructural and electrophysiological studies. Photo‐microscopy showed that 60 to 80% of the isolated cells had an elongated shape (18 μm in diameter, 150 μm in length) and did not beat spontaneously in normal Tyrode solution. The morphological and ultrastructural integrity of these cells was shown in SEM by their smooth surface with regularly spaced T‐tubule openings and in TEM by the regular distribution of the transverse tubular system, mitochondrium and sarcomeres. Using the whole‐cell patch‐clamp technique, they had a resting membrane potential of −72 mV, two types (“Purkinje like” and “ventricular like”) of action potentials could be elicited and they were correctly affected by well‐known modulators of calcium channels. This technique was successfully applied to the rat heart and could be used for heart dissociation of small mammals. It can simultaneously provide isolated cells of different regions of the heart and can be easily and ro

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90367-C

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—The fungicides used intensively in agriculture may affect non‐target organisms. The concentrations of copper sulfate‐based fungicide, Bordeaux mixture, normally used in agriculture, can significantly reduce both the life span and breeding rate ofDrosophila melanogaster. The present study examines the distribution of copper in organ sections of fruit flies intoxicated with Bordeaux mixture, by secondary ion mass spectrometry. The organs of most control flies contained no copper. In contrast, copper accumulated in the cytoplasm of all the mesenteron and Malpighian tubule epithelial cells of the treated flies. There were also copper deposits in the fat body and the epithelia of the seminal receptacle and accessory glands of some flies, but there was little or no copper in the ovaries. The mesenteron and Malpighian tubules are generally responsible for detoxification by accumulation of ingested metal salts in insects. The high concentration of Bordeaux mixture used saturated these organs and resulted in excess copper being deposited in other sites, such as the fat body and the reproductive s

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90368-D

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—The first step of polyamine uptake is the binding of polyamines to the cell membrane. In order to characterize the specificity of the putrescine binding sites at the surface of the glioblastoma cells (U251), we have carried out competition experiments between putrescine bound to latex microspheres and vizualized by scanning electron microscopy and a series ofN,N'‐tetramethyl‐α, ω‐diaminoalkanes.N,N'‐tetramethyl‐1,4‐butanediamine (N,N'‐tetramethylputrescine) and higher homologs inhibit the latex putrescine binding to the cell surface and concomitantly cell proliferation. [14C] putrescine uptake was mainly inhibited by the lower homologs, which were devoid of antiproliferative effects. Our results suggest that putrescine uptake by the human glioblastoma cell line U251, and putrescine binding to the surface of these cells are independent processes. The potential relationship between antitumor effect ofN,N'‐tetramethyl‐α,ω‐diaminoalkanes and its binding to a specific putrescine a

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90369-E

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—Heat production by leukemia cells Molt 4, growing in suspensions with 1 and 3 × 105cells/ml for 4 days, was studied by microcalorimetry. Heat production rates were related to cell growth, glucose consumption, lactate production and cellular ATP‐content. The results show that the time course of heat dissipation is dependent on initial cell number. However, observed thermal power maxima were fairly identical in all experiments. Heat production rates per cell were similar during the initial phase of the study independently of initial cell number, while higher cell densities resulted in significantly lower rate of heat production. Glycolytic conversion of glucose into lactate is nearly stoichiometric. Our results indicate a relationship between heat production and amounts of glucose and lactate in the medium. ATP concentration in cells decreased after 24 hours of cul

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90370-I

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—We report an isolation procedure of trans‐Golgi vesicles (GVs) from rat parotid glands. Various organelle markers were used, particularly galactosyl transferase as a trans‐Golgi marker, to test the purity of the GV fraction. A quantitativein vitrobinding assay between microtubules and GVs is described. The vesicles were incubated with taxol‐induced microtubules, layered between 50% and 43% sucrose cushions and subjected to centrifugation. Unlike free microtubules which were sedimented, the GV‐bound microtubules co‐migrated upward with GVs. Quantification of these bound microtubules was carried out by densitometric scanning of Coomassie blue‐stained gels. The association between microtubules and GVs followed a saturation curve, with a plateau value of 20 μg of microtubule protein bound to 500 μg of GV fraction. The half‐saturation of the GV sites was obtained with a microtubule concentration of 20 μg/ml. Electron microscopy of negatively stained re‐floated material showed numerous microtubule‐vesicle complexes. Coating of microtubules with an excess of brain microtubule‐associated proteins (MAPs) abolished binding. In the absence of exogenous microtubules, we showed that the GV fraction was already interacting with a class of endogenous rat parotid microtubules. This class of colcemid and cold‐stable microtubules represents 10–20% of the total tubulin

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90371-9

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—Paracentrotus lividuscirculating coelomocytes could be separated by a discontinuous sodium‐metrizoate gradient. Amoebocytes and red spherule cells were separated in an almost pure population, whereas colourless spherule cells were distributed at different density levels suggesting that several morphological or functional types constitute this cellular category. Vibratile cells co‐occur with amoebocytes, colourless and red spherule cells in a single heterogeneous fraction. Studies with the separated bands indicate that antibacterial activity against gram negative marine bacteria is present in each cellular fraction. However, the highest degree of bacterial growth inhibition was produced by amoebocytes from band A and red spherule cells from band F. Amoebocytes most probably exerted their antibacterial function by lysozyme‐like molecules, while red spherule cells do not possess this

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90372-A

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—We have studied the expression of the fibronectin gene in 7 day‐old chick embryo (stage 32) byin situhybridization at the light and electron microscope levels, using a 397 base‐pairs chicken cDNA, labeled by radioisotope or biotin‐11dUTP. Cryostat sections of whole chick embryos displayed a selective label on the upper layer of the dermis, fibrous sclera and mesenchymal cells but not on cartilagenous sclera cells. These results show that the expression of the fibronectin gene varies in relation to the morphogenetic events. Hybridization at the ultrastructural level on thin sections of sclera embedded in Lowicryl K4M showed a selective labeling on various cell compartments. Biotin‐11dUTP and radiolabeled probes were compared. The labeling was found precisely on the membrane of the rough endoplasmic reticulum and on the nuclear envelope. A few silver grains were located on the nucleus and in the perinucleolar region. This study shows that the postembeddingin situhybridization is a powerful procedure to study the expression of the extracellular protein genes and gives further information on the localizatio

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90373-B

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Summary—TwelvePhytomonasisolates were obtained from different plants originating from several countries and culturedin vitroin complex media. The kinetoplast DNA (kDNA) was purified and observed by electron microscopy. The structure of kDNA from all isolates appeared as a large network of interlocked minicircles with some maxicircles extruding from the network, as has often been shown forTrypanosomatidae. Topoisomerase II resolved the kDNA network into free minicircles which were then analyzed by electron microscopy and by electrophoresis in agarose gel. The minicircle sizes varied from 1.3 to 2.8 kilobase pairs according to thePhytomonasisolate. The analysis by restriction endonucleases revealed a base sequence heterogeneity in the minicircles of 10 of thesePhytomonasisolates. By contrast, in 2Phytomonasisolates, more than 90% of their minicircle content was found to be homogeneous. Most interestingly, the minicircle cleavage patterns were found to be different betweenPhytomonasisolates and thus could be used to distinguish the

ISSN:0248-4900    

DOI:10.1016/0248-4900(90)90374-C

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY