On the Phospholipid Metabolism of Glial Cell Primary Cultures.

Abstract: Primary cultures were prepared from newborn rat brain. After 16-18 days, they consisted mainly of mature and immature astrocytes and oligodendrocytes, as judged by immunohistochemistry. To study the metabolism of ethanolamine glycerophospholipids, the cells were incubated with 1-[1-³H]alkyl- sn -glycero-3-phosphoethanolamine (1-alkyl-GPE), for 1–20 h. Five main products were formed: 1-alkyl-2-acyl-GPE; 1-alkyl-2-acyksn-glycero-3-phosphocholine (1-alkyl-2-acyl-GPC); 1-alkenyl-2-acyl-GPE (ethanolamine plasmalogen); 1-alkenyl-2-acyl-GPC (choline plasmalogen); and 1-alkyl-glycerol. Acylation of the substrate was the main reaction during the first 3 h of incubation, whereas desaturation to plasmaiogen reached a maximum after 12 h. Greater amounts of radioactivity were observed in the phosphatidylcholine fraction after longer incubation times. Only small amounts of choline plasmalogen were observed. The phosphatidylethanolamine fraction consisted of 26.5% diacyl-, 27.5% alkyl-acyl-, and 46.0% alkenyl-acyl- compounds, whereas the corresponding data for the phosphatidylcholine fraction were 78.5, 16.4, and 5.1%, respectively, after 20 h of incubation. Hydrolysis of the substrate to 1-alkyl-glycerol was a minor reaction.     

Distribution of chlorpromazine and imipramine in adipose and other tissues of rats

Adipose tissue kinetics of chlorpromazine and imipramine, two drugs which are more lipophilic than thiopental, were studied in the rat. After single i.v. doses, the time-course of drug distribution was followed in adipose and various other tissues, until their concentrations in adipose tissues declined. Under these conditions the two drugs behaved almost identically. Among the tissues analyzed, the lowest concentrations were found in adipose tissue, with the exception of plasma. At its maximum concentration after about 30 minutes, total adipose tissue contained only 3 % of the dose of administered drugs. Adipose/plasma and adipose/lung concentration ratios were 2–5 and 0.05, respectively.After maximum tolerated oral doses of imipramine for 3 weeks, similar steady state concentration ratios (plasma:adipose:brain:lung 1:3:12:96) were observed. In adipose tissue the imipramine/desmethylimipramine ratio was about 1, and the desmethylimipramine steady state levels did not increase with time. Literature data indicate that many basic lipophilic drugs are not stored in adipose tissue. This is now clearly shown for chlorpromazine and imipramine, even under extreme, subchronic conditions in the case of imipramine.     

Processing of yeast mitochondrial RNA: involvement of intramolecular hybrids in splicing of cob intron 4 RNA by mutation and reversion

Revertants have been obtained from six mutants of the box9 cluster, which are supposed to be defective in RNA splicing as a result of alterations in a splice signal sequence. This sequence is in the 5' part of intron 4 of the cob gene, 330 to 340 bp downstream from the 5' splice site. Sequencing reveals that reversion to splicing competence is achieved by restoration of the wild-type box9 sequence; by creation of novel box9 sequences; and by introduction of a second site or suppressor mutation (sup-) compensating for the effect of the primary box9- mutation. The sup- mutation alters a sequence in intron 4,293 bp upstream from the box9- primary mutation. The box9 sequence and this upstream sequence can base pair to form an intramolecular hybrid in intron RNA in which box9- and sup- are compensatory base pair exchanges (G----A and C----U, respectively). Thus intramolecular hybrid structures of intron RNA are essential for RNA splicing.     

Isolation and Characterization of Rifampin-Resistant and Streptolydigin-Resistant Mutants of Bacillus subtilis with Altered Sporulation Properties

Mutants of Bacillus subtilis with altered deoxyribonucleic-dependent ribonucleic acid polymerase activity have been isolated and characterized. These mutants, selected as strains resistant to rifampin or streptolydigin, demonstrate drug-resistant in vitro ribonucleic acid synthesis. Sporeforming ability and support of phage infection are altered in many of the mutants. Mutations to rifampin and streptolydigin resistance have been located on the B. subtilis chromosome and ordered relative to the markers cysA14 and str.     

Beiträge zur Ökologie des Aphano-Matricarietum Tüxen 1937

Zusammenfassung 1. An Hand von 101 Aufnahmen wird das Aphano-Matricarietum typicum and scleranthetosum im Unteren Eichsfeld in eine typische, eineRanunculus repens-, eineGnaphalium uliginosum-und eineJuncus bufonius-Variante gegliedert.2. Durch Bestimmungen des Bodenwassergehaltes und des pflanzenverfügbaren Wassers sowie durch Berechnung des W-Wertes nachEllenberg wird die Reihe der Varianten als Reihe zunehmender Feuchtigkeit charakterisiert.3. Bei zunehmender Dichte des Getreidebestandes nehmen die dominierenden Unkräuter stark ab, die schwach deckenden Unkräuter dagegen zu.4. Aus den Deckungswerten der soziologischen Tabelle werden Konkurrenzwirkungen zwischenMatricaria chamomilla, Aphanes arvensis undStellaria media belegt.

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Summary 1. In two subassociations of a weed community (Aphano-Matricarietum typicum and scleranthetosum) 101 relevés are used for distinguish three subunits: a var. ofRanunculus repens, ofGnaphalium uliginosum and ofJuncus bufonius.By estimating the water contents and pF values of the soil and by calculating the water figure afterEllenberg this series of subunits is shown to be a series of increasing humidity.2. With increasing density of the cereal grasses, the stronger dominant weeds decrease, while the weaker ones increase.3. A method is described to calculate competition between the dominant weeds from the figures of the sociological relevés. Interactions have been found betweenMatricaria chamomilla at the one side andAphanes arvensis andStellaria media at the other side and vice versa.

     

The homogenous γG-immunoglobulin produced by mouse plasmacytoma 5563 and its subsequent heterogeneity in serum

The mouse plasma cell tumour 5563 has been shown to synthesize and secrete a single molecular species of gammaG-immunoglobulin, which was identified by labelling with (14)C-labelled amino acids. The heterogeneity of G-myeloma globulin as it is found in serum of tumour-bearing mice is due to subsequent changes in the charge properties of the newly secreted molecules. These changes have been reproduced in vitro. On incubation with sterile serum, the newly formed radioactive myeloma protein changed its chromatographic and electrophoretic properties to coincide with those of myeloma protein isolated from serum. Incubation of purified myeloma protein band a, under a variety of conditions, led to the characteristic pattern of serum myeloma protein showing multiple electrophoretic bands. The chemical nature of the molecular changes is not yet known. It is suggested that seruminduced changes could contribute to the electrophoretic heterogeneity of specific antibodies within the gammaG-class of immunoglobulins. This demonstration of the production of a single molecular species of immunoglobulin by a plasma cell tumour provides support for the concept of ;one-cell-one antibody'.     

Zum Abbau der l-Äpfelsäure durch Milchsäurebakterien

Zusammenfassung Die Abtrennung der OES-Decarboxylase vom Malic-Enzym wird bei Enzymlösung aus Bakterien des Stammes Lactobacillus plantarum L durchgeführt. Die Trennung gelingt wegen der unterschiedlichen Temperatur-und pH-Empfindlichkeit der beiden Enzyme. Das Malic-Enzym ist im Bereich von pH 4,5–5,0 nur dann bei 40° C und darüber vor Denaturierung geschützt, wenn es als Substrat-NAD⁺-Mn⁺⁺-Komplex vorliegt. Die OES-Decarboxylase ist entsprechend temperaturstabiler als das Malic-Enzym, auch wenn keine Oxalessigsäure zugesetzt wird.Die Ammoniumsulfat-Fraktionierung bringt keine befriedigende Trennung der Enzyme mit sich. Wird das Malic-Enzym durch Denaturierung nicht entfernt, so reißt es bei 75% iger Sättigung mit Ammoniumsulfat die OES-Decarboxylase mit in den Niederschlag. Bei dieser Salzkonzentration fällt auch die Malat-Dehydrogenase aus.Mikrobiolosisch und papierchromatographisch durchgeführte Biotinnachweise bestätigen, daß die OES-Decarboxylase des Stammes, L ein Biotinproteid ist.     

Morphological and metabolic characterization of a new species of strictly anaerobic rumen fungus: Neocallimastix joyonii

A new strain of strictly anaerobic fungi was isolated from the rumen of sheep. This strain is characterized by a polycentric thallus, an extensive and polynuclear rhizomycelium, polyflagellated zoospores with gamma particle-like bodies. We propose to assign this strain in a new species: Neocallimastix joyonii.     

Functional analysis of a complex oncogene arrangement in biotype III Agrobacterium tumefaciens strains

The ubiquitous grapevine-associated octopine/cucumopine Ti plasmids of biotype III Agrobacterium tumefaciens strains carry two T regions, TA and TB, with a complex oncogene arrangement. Within the octopine/cucumopine group, two main strain types were identified: large TA strains with a TA region resembling the TL region of the biotype I octopine strain Ach5 and small TA strains with a similar T region organization as the large TA strains but with a large internal TA deletion. Structural and functional studies of the representative large TA strain Tm4 revealed six oncogenes. Each oncogene was inserted in a disarmed vector and tested for biological activity using the corresponding oncogenes of Ach5 as standards. Five Tm4 oncogenes, TA-iaaM, T-ipt, T-6b, TB-iaaH and TB-iaaM, were shown to be active, the IS-interrupted TA-iaaH gene was inactive. To study the role of each gene in the pTiTm4 context, several single and multiple pTiTm4 mutations were constructed. It was shown that whereas TA-iaaM and TB-iaaH are essential for tumour formation on grapevine, T-ipt, T-6b and TB-iaaM are not. The avirulence of the TA-iaaM ^- mutant was shown to be due to an inhibitory effect of the T-ipt gene, since a TA-iaaM ^- /T-ipt ^- double mutant was fully virulent. We conclude that the TA-iaaM gene of large TA strains is specifically required to counteract the tumour growth inhibiting activity of the T-ipt gene. Both TA-iaaM and T-ipt are absent from the small TA strains. A model on the roles and interactions of the different oncogenes in large TA and small TA strains is presented.     

Human HepG2 and Rat Fao Hepatic-Derived Cell Lines Show Different Responses to Ciprofibrate, a Peroxisome Proliferator: Analysis by Flow Cytometry

Peroxisome proliferators, and especially hypolipidemic drugs such as ciprofibrate, are known to be hepatocarcinogens in rodents, but their effect in humans is controversial. In an attempt to investigate the effects of ciprofibrate at a cellular level, the analysis of individual whole cells was performed by flow cytometry on samples from two hepatic-derived cell lines: the rat Fao cell line and the human HepG2 cell line. The increase of light scatter signals in rat Fao cells treated for 3 days with ciprofibrate at 250 μMwas related to modifications of intrinsic cellular parameters, such as size and cytoplasmic granularity. Conversely, no variations appeared in human HepG2-treated cells. Moreover, the study of the cell cycle distribution of asynchronously growing cells showed an increase in the percentage of proliferative cells in Fao-treated cells, but not in HepG2-treated cells. In order to give a simultaneous assessment of changes in cellular parameters and cell metabolism, these flow cytometric experiments were completed with the measurements of the palmitoyl–CoA oxidase activity, used as a marker of peroxisome proliferation. The cellular modifications in the rat Fao cell line were accompanied by a great increase in this enzymatic activity, whereas the human HepG2 cell line, which failed to exhibit changes of cytometric data, presented no, or weak, increase in this oxidase activity. The cellular modifications observed in the rat Fao cell line may be related to the well-known hepatocarcinogenicity of ciprofibrate in rodents, whereas the absence of response of HepG2 cells is in favor of the noncarcinogenicity of this drug in humans. This report validates another methodological approach for the investigation of the safety of peroxisome proliferators in humans.