Protein synthesis during germination of heterothallic yeast ascospores.

Protein synthesis during ascospore germination of the heterothallic Saccharomyces cerevisiae strain AP-3 was investigated. Protein synthesis in the germinating ascospores appeared to begin approximately 20 min following glucose initiation. Since RNA synthesis did not start until approximately 70 min after the onset of germination, strain AP-3 ascospores must contain RNA which is ready for immediate translation. Both trehalase and glyceraldehyde-3-phosphate dehydrogenase activities were found to be affected by the onset of germination. Trehalase activity was found to increase severalfold following 60 min of spore germination but remained relatively constant over the subsequent 120 min examined. Dehydrogenase activity was not detectable in AP-3 ascospores but was measurable in germinating ascospores.     

EGF-induced programmed cell death of human mammary carcinoma MDA-MB-468 cells is preceded by activation of AP-1

MDA-MB-468 is a human mammary adenocarcinoma cell line that overexpresses the epidermal growth factor (EGF) receptor and undergoes programmed cell death (apoptosis) in response to EGF treatment. Programmed cell death was shown to be greatly enhanced when cells were growth-arrested prior to EGF treatment. Apoptosis was characterized by an initial rounding up and detachment of the cells from their substrate starting about 12 h after EGF treatment, followed by chromatin condensation, nuclear fragmentation and oligonucleosomal fragmentation of the DNA at about 24 to 48 h. Cell death was dependent on de novo protein synthesis. We found a rapid induction of c-fos, c-jun and junB at the mRNA level after about 30 min of EGF treatment and a more delayed upregulation of fosB and fra-1. The junD gene was expressed in the absence of EGF, and it was moderately induced within 30 min of growth factor addition. The increase of the different fos and jun mRNAs were paralleled by an increase of activator protein-1 (AP-1) DNA binding activity. A characterization of the AP-1 complex revealed similar levels of several Fos and Jun proteins. Based on the kinetics of AP-1 accumulation and cell death, it seems likely that AP-1 contributes to the apoptotic cell death of EGF receptor-overexpressing MDA-MB-468 cells. Received 21 July 1997; received after revision 6 November 1997; accepted 6 November 1997     

Activation concomitante par l'hétéroauxine de la résorption du corps paranucléaire ribonucléique et de la germination des zygotes chezAllomyces

Summary Heteroauxin (optimal concentration 10^–5) activates the germination of the zygotes and the dissolution of their RNA nuclear cap inAllomyces javanicus.Alkaline phosphatase has been located cytochemically in the cytoplasm surrounding the RNA nuclear cap.These new observations lead the author to postulate a relationship between the stimulating action of heteroauxin, activation of the phosphatases and awakening of the RNA-protein synthesis dynamic system during the germination of the zygotes inAllomyces.     

Inverse regulation of spore germination and growth by cyclic AMP inStreptomyces hygroscopicus

Summary The cyclic AMP level in germinating spores ofStreptomyces hygroscopicus rises to a maximum at outgrowth of germ tubes. Exogenous cyclic AMP results in an inverse effect on germination speed and growth.     

Lokalisation zusätzlicher RNS-Synthese in Trypsin-behandelten Riesenchromosomen vonChironomus thummi

Summary After injection of buffered trypsin into nuclei of salivary gland cells ofChironomus thummi, the existing puffs in the giant chromosomes are enlarged. Autoradiography shows an increase in RNA synthesis of approximately 3-fold in these puffs. It is argued that histones in puffed chromosome segments are in a structural state that renders them unable to prevent RNA synthesis and at the same time causes them to be attacked earlier by trypsin.     

Die Veränderung des Stärke-, Protein- und RNS-Gehaltes vonLemna minor L. unter dem Einfluss von Kinetin (6-Furfurylaminopurin)

Summary Kinetin (6-furfurylaminopurine) is rapidly absorbed byLemna minor L. 3 · 10^–8 M/ml medium cause an immediate but temporary stimulation of RNA and protein synthesis during the first hour of the treatment. The following excessive accumulation of starch is considered to be more or less a direct consequence of a disturbed RNA and protein metabolism.     

Purification and properties of a heat-resistant exotoxin produced byMacrophomina phaseolina (Tassi) Goid in culture

Summary A partially purified preparation of a water-soluble, heat-resistant, nonspecific exotoxin produced by a strain ofMacrophomina phaseolina, isolated fromPhaseolus mungo L. could reduce Cu⁺⁺ ions and produced a red colour with 2,4-dinitrophenyl hydrazine reagent. It caused inhibition of seed germination, wilting of cut seedlings, stunted growth of young seedlings and loss of permeability of the cell membrane. Seedlings ofP. mungo, grown in presence of the toxin showed a slight increase in the contents of protein and total RNA over control, but a significant increase in the specific activities of F-1, 6-BP aldolase and G-6-P isomerase.     

Zum Proliferations-Stoffwechsel der Rattenleber nach Teilhepatektomie. Autoradiographische Untersuchungen mit3H-Cytidin,-Phenylalanin und -Thymidin

Summary During the first wave of parenchymal liver regeneration in adult rats after partial hepatectomy, the cellular synthesis and migration of RNA and the metabolism of protein were studied by autoradiography following an injection of³H-cytidine or³H-l-phenylalanine and double injections of 1 of these precursors +³H-thymidine. The following results were obtained: the synthesis and migration of RNA and the metabolism of protein are enhanced under these conditions of proliferation. In spite of this, the relation of metabolic activity in nucleolus, karyoplasm and cytoplasm remains constant. By double injection techniques it is proved that no differences exist in migration of RNA into the cytoplasm and cytoplasmic protein synthesis between cells with or without DNA synthesizing nuclei.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Phosphate transport inClaviceps sp. strain SD-58

Summary Phosphate uptake inClaviceps sp. strain SD-58 was found to be linear for 20 min, proportional to cell density in mg/ml, energy dependent, and taking place against a concentration gradient with a K_m value of 45.45×10^–5 M. Osmotic shock treatment to the cell caused a reduction in phosphate uptake associated with the release of binding protein. Partial restoration of uptake was observed on incubation of osmotically shocked cells with shock fluid. The results are discussed with reference to the effect of phosphate on alkaloid synthesis inClaviceps sp. strain SD-58.     

Contrasting effects of RNA and protein synthesis blocking on natural and lectin-dependent cell-mediated cytotoxicity against adherent HEp-2 cells

Summary In this study, earlier observations^2,9 concerning the independence of both natural (NCMC) and lectin-dependent cell-mediated cytotoxicity (LDCC) from DNA synthesis have been confirmed. In addition, blocking of RNA synthesis by actinomycin D and of protein synthesis, reversibly by puromycin (PM) and irreversibly by emetine (EM) had different effects on NCMC and LDCC against³H-thymidine-prelabeled HEp-2 target cells. Similarly to the Con A-induced proliferation of lymphocytes, LDCC activity was also inhibited by blocking of RNA and protein synthesis. NCMC to HEp-2 target cells was not affected by blocking of RNA synthesis, while both PM and EM strongly enhanced NCMC activity.     

Contrasting effects of RNA and protein synthesis blocking on natural and lectin-dependent cell-mediated cytotoxicity against adherent HEp-2 cells

In this study, earlier observations concerning the independence of both natural (NCMC) and lectin-dependent cell-mediated cytotoxicity (LDCC) from DNA synthesis have been confirmed. In addition, blocking of RNA synthesis by actinomycin D and of protein synthesis, reversibly by puromycin (PM) and irreversibly by emetine (EM) had different effects on NCMC and LDCC against 3H-thymidine-prelabeled HEp-2 target cells. Similarly to the Con A-induced proliferation of lymphocytes, LDCC activity was also inhibited by blocking of RNA and protein synthesis. NCMC to HEp-2 target cells was not affected by blocking of RNA synthesis, while both PM and EM strongly enhanced NCMC activity.     

Adenosine triphosphatase ofAspergillus nidulans: Stimulation by aminoacids

Summary Ca²⁺-dependent ATPase ofAspergillus nidulans was found to be stimulated by aminoacids in vitro. Both histidine and arginine stimulated the enzyme more effectively than the aromatic aminoacids. Supplementation of the growth medium with basic or aromatic aminoacids increased the enzyme activity in vivo 2–6-fold. The enhanced activity observed in these cultures in vivo was not mediated through the synthesis of new isoenzyme, as observed in proteinenriched cultures, but appeared to be through the activation of enzyme activity.     

thiD locus ofEscherichia coli

Summary A mutant strain ofEscherichia coli K-12 lacking phosphomethylpyrimidine kinase activity was produced from the polyauxotrophic female strain, JC1552. The locus of its lesion, for which we propose the designationthiD, was mapped at about 46 min on the chromosome.     

Influence of adult food on the reproduction of virgin females of anAcanthoscelides obtectus strain originating from Colombian altiplanos

Summary The reproductive activity of virgin females of anAcanthoscelides obtectus strain originating from the high Colombian plateau was variable. Some females did not synthesize vitellogenin during imaginal life while others produced mature oocytes. In the case of virgin females without reproductive activity, the supply of pollen in the adult diet did not stimulate synthesis and incorporation of vitellogenin. On the other hand, the supply of pollen always induced a higher vitellogenin titre in the haemolymph of females which produced oocytes, and stimulated ovarian production.     

Die durch animalische Mucoproteine verursachte Wachstumshemmung

Summary Anti-growth activity of animal mucoproteins on germinating seeds ofLupinus albus was tested; the inhibition with plasma mucoprotein was statistically significant. The inhibition with urine mucoprotein according toAnderson was the most effective.     

Fank1 interacts with Jab1 and regulates cell apoptosis via the AP-1 pathway

Regulation of apoptosis at various stages of differentiation plays an important role in spermatogenesis. Therefore, the identification and characterisation of highly expressed genes in the testis that are involved in apoptosis is of great value to delineate the mechanism of spermatogenesis. Here, we reported that Fank1, a novel gene highly expressed in testis, functioned as an anti-apoptotic protein that activated the activator protein 1 (AP-1) pathway. We found that Jab1 (Jun activation domain-binding protein 1), a co-activator of AP-1, specifically interacted with Fank1. Reporter analyses showed that Fank1 activated AP-1 pathway in a Jab1-dependent manner. Fank1 overexpression also increased the expression and activation of endogenous c-Jun. Further study showed that Fank1 inhibited cell apoptosis by upregulating and activating endogenous c-Jun and its downstream target, Bcl-3. This process was shown to be Jab1 dependent. Taken together, our results indicated that by interacting with Jab1, Fank1 could suppress cell apoptosis by activating the AP-1-induced anti-apoptotic pathway.     

High salt effect on RNA synthesis in Krebs ascites tumor cells

Summary The incubation of Krebs ascites tumor cells in medium with a high salt concentration resulted in a partial inhibition of nuclear RNA synthesis. The residual RNA polymerase activity in such nuclei was only slightly inhibited by low concentrations (50 nM) of -amanitin. This finding suggested an inhibition of RNA polymerase II activity under conditions of medium hypertonicity. Indeed, RNA polymerase II, isolated from the nuclei of cells exposed to hypertonicity, revealed only half of the control activity. On the other hand, RNA polymerase I was not affected by hypertonicity. Moreover, chromatin fractions isolated from cells incubated in hypertonic or isotonic medium were equally template-active in RNA synthesis.This investigation was supported by the Turkish Scientific and Technical Research Council (TÜBITAK), Project No. TAG 339.