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At least 937 records · Page 52Linked to original sources
PubMed1997

Energy metabolism in liver of anoxia-tolerant turtle species (Pseudemys scripta): a model for studying hepatic tolerance to cold hypoxia.

We have studied biochemical markers of energy metabolism and glycolysis by enzyme analyses and 1H NMR spectroscopy in livers of the freshwater turtle, Pseudemys scripta, after vascular flush and cold storage. Values for hepatic ATP content and energy charge remained unchanged for 24 h and showed only small declines between 24 and 48 h of cold hypoxia. Lactate and glucose levels increased over the 48-h period, demonstrating, respectively, progressive glycolysis and glycogenolysis. These observations are in contrast to those made in mammalian liver, where ATP levels fall precipitously during the first few hours of cold hypoxia and glycolysis is inhibited. Additional changes suggested by 1H NMR spectroscopy may indicate a role for other metabolic pathways. Isolated organs of species such as Pseudemys may be useful models for studying the biochemical basis of resistance to cold hypoxic damage.

Adenosine Diphosphate↗
PubMed2005

Debaryomyces hansenii, a highly osmo-tolerant and halo-tolerant yeast, maintains activated Dhog1p in the cytoplasm during its growth under severe osmotic stress.

The HOG pathway is an important mitogen-activated protein kinase (MAPK) signal transduction pathway in Saccharomyces cerevisiae that mediates adaptation of cells to hyper-osmotic stress. Activation of this pathway causes rapid but transient, phosphorylation of the MAPK Hog1p. Phosphorylated Hog1p is rapidly transported to the nucleus that results in the transcription of target genes. The HOG pathway appears to be ubiquitous in yeast. Components of HOG pathway have also been identified in Debaryomyces hansenii, a highly osmotolerant and halotolerant yeast. We have studied activation of HOG pathway in D. hansenii under different stress conditions. Our experiments demonstrated that the pathway is activated by high osmolarity, oxidative and UV stress but not by heat stress. We have provided evidence, for the first time, that D. hansenii maintains phosphorylated Dhog1p in the cytoplasm during its growth under severe osmotic stress.

Cytoplasm↗
PubMed2006

Purification, characterization, and molecular cloning of organic-solvent-tolerant cholesterol esterase from cyclohexane-tolerant Burkholderia cepacia strain ST-200.

Extracellular cholesterol esterase of Burkholderia cepacia strain ST-200 was purified from the culture supernatant. Its molecular mass was 37 kDa. The enzyme was stable at pH 5.5-12 and active at pH 5.5-6, showing optimal activity at pH 7.0 at 45 degrees C. Relative to the commercially available cholesterol esterases, the purified enzyme was highly stable in the presence of various water-miscible organic solvents. The enzyme preferentially hydrolyzed long-chain fatty acid esters of cholesterol, except for that of cholesteryl palmitate. The enzyme exhibited lipolytic activity toward various p-nitrophenyl esters. The hydrolysis rate of p-nitrophenyl caprylate was enhanced 3.5- to 7.2-fold in the presence of 5-20% (vol/vol) water-miscible organic solvents relative to that in the absence of organic solvents. The structural gene encoding the cholesterol esterase was cloned and sequenced. The primary translation product was predicted to be 365 amino acid residues. The mature product is composed of 325 amino acid residues. The amino acid sequence of the product showed the highest similarity to the lipase LipA (87%) from B. cepacia DSM3959.

Amino Acid Sequence↗