Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epimastigote cultures of the two cloned Trypanosoma cruzi stocks, CA-I/72 and HO-3/15, grown under identical conditions, differ both qualitatively and quantitatively in their cytochrome content. The CA-I/72 stock has a four-fold higher cytochrome b content (19.2 nM (mg protein)-1) than the HO-3/15 stock (4.9 nM (mg protein)-1). Cytochrome o is present at 29 nM (mg protein)-1 in the CA-I/72 stock but is below detectable limits in the HO-3/15 stock. There is no inter-stock difference in oxygen utilization (12-15 nM O2 min-1 (mg protein)-1) during exponential growth. However, stationary phase CA-I/72 epimastigotes utilize twice as much oxygen as HO-3/15 epimastigotes. Oxygen utilization by HO-3/15 epimastigotes incubated in Dulbecco's phosphate buffer solution (starvation conditions), was stimulated earlier and to higher levels by the addition of glucose than by CA-I/72 epimastigotes under identical conditions. Under starvation conditions and with the cytochrome chain partially inhibited by antimycin A,(anti-A) the addition addition of glucose also increased oxygen utilization by CA-I/72 epimastigotes. In contrast, anti-A did not influence glucose-stimulated oxygen utilization by HO-3/15 epimastigotes. Following partial inhibition with anti-A, salicylhydroxamic acid produced an additional 50% inhibition in oxygen utilization in both stocks irrespective of the growth phase of the organisms. These data indicate that marked intra-specific differences in oxidative metabolism exist within the T. cruzi population and that an alpha-glycerophosphate oxidase or similar salicylhydroxamic acid-inhibitable compound may be present in the organism.
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PMID:Isolate-dependent differences in the oxidative metabolism of Trypanosoma cruzi epimastigotes. 240 95

Higher eukaryotes contain tRNA transglycosylases that incorporate the guanine derivative queuine from the nutritional environment into specific tRNAs by exchange with guanine at position 34. Alterations in the queuosine content of specific tRNAs are suggested to be involved in regulatory mechanisms of major routes of metabolism during differentiation. Dictyostelium discoideum has been applied as a model to investigate the function of queuine or queuine-containing tRNAs. Axenic strains are supplied with queuine by peptone, but they grow equally well in a defined queuine-free medium. Queuine-lacking amoebae, starved in suspension culture for 24 h, lose their ability to differentiate into stalk cells and spores, whereas amoebae sufficiently supplied with queuine will overcome this metabolic stress and undergo further development when plated on agar. The results presented here show that D(-)-lactate occurs in the slime mould in millimolar amounts and that its level is remarkably decreased in queuine-lacking cells after 24 h of starvation in suspension culture. On isoelectric-focusing polyacrylamide gels, nine different forms of NAD-dependent D(-)-lactate dehydrogenase can be separated from extracts of vegetative cells, and six forms from extracts of the starved cells. Under queuine limitation, one form is missing in the starved cells. Low amounts of L(+)-lactate are usually found in vegetative amoebae but significantly less in queuine-lacking cells. Five forms of NAD-dependent L(+)-lactate dehydrogenase are detectable in extracts from vegetative, queuine-treated cells, and slight alterations occur in queuine-deficient amoebae. In the starved cells only one form of L(+)-lactate dehydrogenase is found, irrespective of the supply of queuine to the cells. A cytochrome of type b with an absorption maximum at 559 nm accumulates during starvation only in queuine-lacking cells; it might be a component of an NAD-independent lactic acid oxidoreductase as is cytochrome b 557 in yeast and be responsible for the reduced level of lactate in cells lacking queuine in tRNA.
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PMID:Specific changes in lactate levels, lactate dehydrogenase patterns and cytochrome b559 in Dictyostelium discoideum caused by queuine. 669 26

In the green alga Chlamydomonas reinhardtii, the ClpP protease is encoded by an essential chloroplast gene. Mutating its AUG translation initiation codon to AUU reduced ClpP accumulation to 25 to 45% of that of the wild type. Both the mature protein and the putative precursor containing its insertion sequence were present in reduced amounts. Attenuation of ClpP did not affect growth rates under normal conditions but restricted the ability of the cells to adapt to elevated CO(2) levels. It also affected the rate of degradation of the cytochrome b(6)f complex of the thylakoid membrane in two experimental situations: (1) during nitrogen starvation, and (2) in mutants deficient in the Rieske iron-sulfur protein. The ClpP level also controls the steady state accumulation of a mutated version of the Rieske protein. In contrast, attenuation of ClpP did not rescue the fully unassembled subunits in other cytochrome b(6)f mutants. We conclude that proteolytic disposal of fully or partially assembled cytochrome b(6)f is controlled by the Clp protease.
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PMID:Evidence for a role of ClpP in the degradation of the chloroplast cytochrome b(6)f complex. 1063 13

Microalgae of the genus Nannochloropsis are capable of accumulating triacylglycerols (TAGs) when exposed to nutrient limitation (in particular, nitrogen [N]) and are therefore considered promising organisms for biodiesel production. Here, after nitrogen removal from the medium, Nannochloropsis gaditana cells showed extensive triacylglycerol accumulation (38% TAG on a dry weight basis). Triacylglycerols accumulated during N deprivation harbored signatures, indicating that they mainly stemmed from freshly synthesized fatty acids, with a small proportion originating from a recycling of membrane glycerolipids. The amount of chloroplast galactoglycerolipids, which are essential for the integrity of thylakoids, decreased, while their fatty acid composition appeared to be unaltered. In starved cells, galactolipids were kept at a level sufficient to maintain chloroplast integrity, as confirmed by electron microscopy. Consistently, N-starved Nannochloropsis cells contained less photosynthetic membranes but were still efficiently performing photosynthesis. N starvation led to a modification of the photosynthetic apparatus with a change in pigment composition and a decrease in the content of all the major electron flow complexes, including photosystem II, photosystem I, and the cytochrome b(6)f complex. The photosystem II content was particularly affected, leading to the inhibition of linear electron flow from water to CO(2). Such a reduction, however, was partially compensated for by activation of alternative electron pathways, such as cyclic electron transport. Overall, these changes allowed cells to modify their energetic metabolism in order to maintain photosynthetic growth.
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PMID:The response of Nannochloropsis gaditana to nitrogen starvation includes de novo biosynthesis of triacylglycerols, a decrease of chloroplast galactolipids, and reorganization of the photosynthetic apparatus. 2345 91

The mechanism of excitation energy distribution between the two photosystems (state transitions) is studied in Synechocystis 6714 wild type and in wild type and a mutant lacking phycocyanin of Synechocystis 6803. (i) Measurements of fluorescence transients and spectra demonstrate that state transitions in these cyanobacteria are controlled by changes in the efficiency of energy transfer from PS II to PS I (spillover) rather than by changes in association of the phycobilisomes to PS II (mobile antenna model). (ii) Ultrastructural study (freeze-fracture) shows that in the mutant the alignment of the PS II associated EF particles is prevalent in state 1 while the conversion to state 2 results in randomization of the EF particle distribution, as already observed in the wild type (Olive et al. 1986). In the mutant, the distance between the EF particle rows is smaller than in the wild type, probably because of the reduced size of the phycobilisomes. Since a parallel increase of spillover is not observed we suggest that the probability of excitation transfer between PS II units and between PS II and PS I depends on the mutual orientation of the photosystems rather than on their distance. (iii) Measurements of the redox state of the plastoquinone pool in state 1 obtained by PS I illumination and in state 2 obtained by various treatments (darkness, anaerobiosis and starvation) show that the plastoquinone pool is oxidized in state 1 and reduced in state 2 except in starved cells where it is still oxidized. In the latter case, no important decrease of ATP was observed. Thus, we propose that in Synechocystis the primary control of the state transitions is the redox state of a component of the cytochrome b 6/f complex rather than that of the plastoquinone pool.
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PMID:State 1-state 2 adaptation in the cyanobacteria Synechocystis PCC 6714 wild type and Synechocystis PCC 6803 wild type and phycocyanin-less mutant. 2442 May 85

Trunk girdling can increase carbohydrate content above the girdling site and is an important strategy for inhibiting new shoot growth to promote flowering in cultivated litchi (Litchi chinensis Sonn.). However, girdling inhibits carbohydrate transport to the root in nearly all of the fruit development periods and consequently decreases root absorption. The mechanism through which carbohydrates regulate root development in arbuscular mycorrhiza (AM) remains largely unknown. Carbohydrate content, AM colonization, and transcriptome in the roots were analyzed to elucidate the interaction between host litchi and AM fungi when carbohydrate content decreases. Girdling decreased glucose, fructose, sucrose, quebrachitol, and starch contents in the litchi mycorrhizal roots, thereby reducing AM colonization. RNA-seq achieved approximately 60 million reads of each sample, with an average length of reads reaching 100 bp. Assembly of all the reads of the 30 samples produced 671,316 transcripts and 381,429 unigenes, with average lengths of 780 and 643 bp, respectively. Litchi (54,100 unigenes) and AM fungi unigenes (33,120 unigenes) were achieved through sequence annotation during decreased carbohydrate content. Analysis of differentially expressed genes (DEG) showed that flavonoids, alpha-linolenic acid, and linoleic acid are the main factors that regulate AM colonization in litchi. However, flavonoids may play a role in detecting the stage at which carbohydrate content decreases; alpha-linolenic acid or linoleic acid may affect AM formation under the adaptation process. Litchi trees stimulated the expression of defense-related genes and downregulated symbiosis signal-transduction genes to inhibit new AM colonization. Moreover, transcription factors of the AP2, ERF, Myb, WRKY, bHLH families, and lectin genes altered maintenance of litchi mycorrhizal roots in the post-symbiotic stage for carbohydrate starvation. Similar to those of the litchi host, the E3 ubiquitin ligase complex SCF subunit scon-3 and polyubiquitin of AM fungi were upregulated at the perceived stages. This occurrence suggested that ubiquitination plays an important role in perceiving carbohydrate decrease in AM fungi. The transcription of cytochrome b-245 and leucine-rich repeat was detected in the DEG database, implying that the transcripts were involved in AM fungal adaptation under carbohydrate starvation. The transcriptome data might suggest novel functions of unigenes in carbohydrate shortage of mycorrhizal roots.
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PMID:Transcriptomes of Arbuscular Mycorrhizal Fungi and Litchi Host Interaction after Tree Girdling. 2706 72

Cytochrome P450 enzymes (P450) play essential roles in redox metabolism in all domains of life including detoxification reactions and sterol biosynthesis. The activity of P450s is fuelled by two electron-transferring mechanisms, heme-independent P450 reductase (CPR) and the heme-dependent cytochrome b5 (CYB5)/cytochrome b5 reductase (CB5R) system. In this study, we characterised the role and regulation of the cytochrome b5 CybE in the fungal pathogen Aspergillus fumigatus. Deletion of the CybE encoding gene (cybE) caused a severe growth defect in two different A. fumigatus isolates, emphasising the importance of the CB5R system in this pathogen, while the non-essentiality of cybE indicates the partial redundancy of the CPR and CB5R systems. Interestingly, the growth defect caused by the cybE loss of function was even more drastic in A. fumigatus strain AfS77 compared to strain A1160P+ indicating a strain-dependent degree of compensation, which is supported by azole resistance studies. In agreement with CybE being important for the assistance of the ergosterol biosynthetic P450 Cyp51, deletion of cybE decreased resistance to the Cyp51-targeting antifungal voriconazole and caused accumulation of the ergosterol pathway intermediate eburicol. Northern analysis indicated that CybE deficiency leads to the compensatory transcriptional upregulation of Cyp51-encoding cyp51A and CPR-encoding cprA. Overexpression of cybE did not affect azole resistance suggesting that CybE activity is not rate limiting. Expression of cybE was found to be repressed during iron starvation by the iron-regulatory transcription factor HapX demonstrating iron dependence of CybE not only at the level of enzyme activity but also at the level of gene expression.
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PMID:The cytochrome b5 CybE is regulated by iron availability and is crucial for azole resistance in A. fumigatus. 2907 65

Macroautophagy/autophagy delivers damaged proteins and organelles to lysosomes for degradation, and plays important roles in maintaining tissue homeostasis by reducing tissue damage. The translocation of LC3 to the limiting membrane of the phagophore, the precursor to the autophagosome, during autophagy provides a binding site for autophagy cargoes, and facilitates fusion with lysosomes. An autophagy-related pathway called LC3-associated phagocytosis (LAP) targets LC3 to phagosome and endosome membranes during uptake of bacterial and fungal pathogens, and targets LC3 to swollen endosomes containing particulate material or apoptotic cells. We have investigated the roles played by autophagy and LAP in vivo by exploiting the observation that the WD domain of ATG16L1 is required for LAP, but not autophagy. Mice lacking the linker and WD domains, activate autophagy, but are deficient in LAP. The LAP-/- mice survive postnatal starvation, grow at the same rate as littermate controls, and are fertile. The liver, kidney, brain and muscle of these mice maintain levels of autophagy cargoes such as LC3 and SQSTM1/p62 similar to littermate controls, and prevent accumulation of SQSTM1 inclusions and tissue damage associated with loss of autophagy. The results suggest that autophagy maintains tissue homeostasis in mice independently of LC3-associated phagocytosis. Further deletion of glutamate E230 in the coiled-coil domain required for WIPI2 binding produced mice with defective autophagy that survived neonatal starvation. Analysis of brain lysates suggested that interactions between WIPI2 and ATG16L1 were less critical for autophagy in the brain, which may allow a low level of autophagy to overcome neonatal lethality. Abbreviations: CCD: coiled-coil domain; CYBB/NOX2: cytochrome b-245: beta polypeptide; GPT/ALT: glutamic pyruvic transaminase: soluble; LAP: LC3-associated phagocytosis; LC3: microtubule-associated protein 1 light chain 3; MEF: mouse embryonic fibroblast; NOD: nucleotide-binding oligomerization domain; NADPH: nicotinamide adenine dinucleotide phosphate; RUBCN/Rubicon: RUN domain and cysteine-rich domain containing Beclin 1-interacting protein; SLE: systemic lupus erythematosus; SQSTM1/p62: sequestosome 1; TLR: toll-like receptor; TMEM: transmembrane protein; TRIM: tripartite motif-containing protein; UVRAG: UV radiation resistance associated gene; WD: tryptophan-aspartic acid; WIPI: WD 40 repeat domain: phosphoinositide interacting.
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PMID:The ATG5-binding and coiled coil domains of ATG16L1 maintain autophagy and tissue homeostasis in mice independently of the WD domain required for LC3-associated phagocytosis. 3040 14