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1.
Abstract The natural product cyanobacterin has been shown to be toxic to most cyanobacteria at a concentration of approx. 5 μM. We demonstrate here that cyanobacterin will also inhibit the growth of most eukaryotic algae at a similar concentration. Some algae, such as Euglena gracilis , are resistant because they are able to maintain themselves by heterotrophic nutrition. Others, such as Chlamydomonas reinhardtii , can apparently induce a detoxification mechanism to maintain photosynthesis in the presence of low concentrations of the inhibitor. Non-photosynthetic microorganisms are not affected by cyanobacterin. 相似文献
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Hydrobiologia - In shallow lakes, macrophytes have important effects on food webs, community structure and nutrient dynamics. For this reason they play a significant role in the restoration of... 相似文献
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Dominique Dorin-Semblat Claudia Demarta-Gatsi Romain Hamelin Florence Armand Teresa Gil Carvalho Marc Moniatte Christian Doerig 《PloS one》2015,10(12)
Casein kinase 1 (CK1) is a pleiotropic protein kinase implicated in several fundamental processes of eukaryotic cell biology. Plasmodium falciparum encodes a single CK1 isoform, PfCK1, that is expressed at all stages of the parasite’s life cycle. We have previously shown that the pfck1 gene cannot be disrupted, but that the locus can be modified if no loss-of-function is incurred, suggesting an important role for this kinase in intra-erythrocytic asexual proliferation. Here, we report on the use of parasite lines expressing GFP- or His-tagged PfCK1 from the endogenous locus to investigate (i) the dynamics of PfCK1 localisation during the asexual cycle in red blood cells, and (ii) potential interactors of PfCK1, so as to gain insight into the involvement of the enzyme in specific cellular processes. Immunofluorescence analysis reveals a dynamic localisation of PfCK1, with evidence for a pool of the enzyme being directed to the membrane of the host erythrocyte in the early stages of infection, followed by a predominantly intra-parasite localisation in trophozoites and schizonts and association with micronemes in merozoites. Furthermore, we present strong evidence that a pool of enzymatically active PfCK1 is secreted into the culture supernatant, demonstrating that PfCK1 is an ectokinase. Our interactome experiments and ensuing kinase assays using recombinant PfCK1 to phosphorylate putative interactors in vitro suggest an involvement of PfCK1 in many cellular processes such as mRNA splicing, protein trafficking, ribosomal, and host cell invasion. 相似文献
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We have studied platelet function in 10 patients with severe liver cirrhosis, compared to healthy subjects. Using washed platelets, we have investigated the molecular mechanism underlying the defect in platelet aggregation frequently observed in these patients. We have found that platelets from cirrhotic patients have a reduced responsiveness to thrombin and collagen in terms of aggregation, and receptor-dependent activation of phospholipase C, A2 and cyclooxygenase/thromboxane synthetase. We thus suggest that this impairment in transmembrane signalling is responsible for the defective platelet function observed in cirrhosis. 相似文献
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Florence Levy-Favatier Lydie Tichnonicky Jacques Kruh Marc Delpech 《Biochimie》1989,71(11-12):1157-1161
We have previously described in rat liver two protein kinases tightly bound to DNA, one is serine-specific, the other arginine-specific. In this work we show that both enzymes are present in various rat tissues and in liver from various species. Both kinase specific activities are strongly decreased in methyl-DBA-induced hepatomas and in HTC cells but not in regenerating liver after hepatectomy. This decrease is then not related to cell proliferation. 相似文献
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In this paper we demonstrate that the cytosofic low-Mr acid phosphatase purified from bovine liver has phosphotyrosine protein phosphatase acitivity on 32P-autophosphorylated epidermal growth factor (EGF) receptor. This activity was significantly inhibited by orthovanadate and p-hydroxymercuribenzoate; the latter result indicates that free sulfhydryl groups are required for phosphotyrosine phosphatase activity. The enzyme was active in a broad pH range, with maximum activity between pH 5.5 and 7.5. The apparent Km for 32P-EGF receptor dephosphorylation was 4 nM. The enzyme appeared to be specific for phosphotyrosine in that it dephosphorylated the autophosphorylated EGF receptor and L-phosphotyrosine, but not 32P-Ser-casein, L-phosphoserine or L-phosphothreonine. These data suggest that the cytosolic low-Mr acid phosphatase might play a regulatory role in EGF receptor-dependent transmembrane signalling. 相似文献
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Summary In a mineral salts medium containing yeast extract, NH4Cl and glucose (50g/L), the pH range producing the fastest growth ofZ. mobilis was 5.5–6.5 with an apparent optimum at 6.5. At constant growth rate of 0.15hr–1, the specific rates of glucose utilization (qs) and ethanol production (qp) were relatively unaffected by pH over the range 7.0–5.5 but increased sharply as the pH was further decreased below 5.5 to 4.0. Under these conditions the ethanol yield was unaffected by pH over the range 4.0–6.5 but decreased markedly at pH of 7. 相似文献
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