Differential gene expression indicates modulated responses to chronic and intermittent hypoxia in corallivorous fireworms (Hermodice carunculata).

Climate models predict an increase in extent, frequency, and duration of marine hypoxia events in the twenty first century. A better understanding of organismal responses to hypoxia in individual species is a crucial step for predicting ecosystem responses. We experimentally subjected a common invertebrate, the bearded fireworm (Hermodice carunculata) to two levels of chronic hypoxia and, in a separate experiment, to intermittent hypoxia. We found components of the conserved hypoxia-inducible factor (HIF) pathway and show a modulated response to hypoxia depending on the severity of hypoxic stress: under mild hypoxia, only the HIF-1α subunit is upregulated, while expression of the other subunit, aryl hydrocarbon nuclear translator, only increases significantly at more severe hypoxia levels. The chronic trials revealed down-regulation of genes related to cell adhesion, transport, development and heme-binding, and up-regulation of genes related to glycolysis, oxygen binding, cell differentiation, digestive and reproductive function. The intermittent hypoxia trials revealed an upregulation of heme transporter activity during hypoxia, and our time series analysis characterized nine clusters of genes with similar expression patterns. Our findings suggest that H. carunculata is likely to tolerate, and be resilient to, predicted future hypoxia conditions.

The effect of preoperative total parenteral nutrition on surgery outcomes.

The effect of preoperative total parenteral nutrition (TPN) on morbidity and mortality was studied in medical records of discharged surgical patients. Patients were classified into two groups on the basis of their ability to meet established criteria for malnutrition and the use of preoperative or postoperative TPN. The control group consisted of 44 patients who received TPN only after surgery or for less than 5 days preoperatively. The experimental group consisted of 26 patients who received treatment for at least 5 days before surgery and/or after surgery. Nutrition parameters measured included serum albumin, total lymphocyte count, hemoglobin, weight, and percent weight loss. Major septic complications (MSC) considered were intra-abdominal sepsis, wound dehiscence, septicemia, and pneumonia. Other complications included respiratory failure, congestive heart failure, fistulas, urinary tract infection, shock, and death. The experimental group showed improvements after surgery in the nutritional parameters listed and had a lower incidence of morbidity and mortality. Deficits in serum albumin, total lymphocyte count, and weight losses greater than or equal to 10% have been significantly (p less than .01) linked to the incidence of MSC. MSC also has been more frequently noted among patients who did not have TPN prior to surgery and who died following surgery. Therefore, preoperative TPN does appear to make a difference in the outcome of surgery.

Electron transfer reactions in biological systems: the reduction of ferricytochrome c by chromous ions.

Chromous ion reacts with ferricytochrome c to yield a one-to-one Cr(III)-ferrocytochrome c complex. This material, when hydrolyzed by trypsin and subjected to chromatographic procedures, yielded two fragments containing chromium. The amino-acid compositions and chemical characteristics of each of these fragments indicated that the chromium had crosslinked two segments of polypeptide chain; these were residues 40-53-Cr(III)-residues 61-72 and residues 40-53-Cr(III)-residues 61-73. Examination of a model of the ferricytochrome c molecule indicated that only two residues of the crosslinked peptides were sufficiently close to allow crosslinking to take place. These residues were tyrosine 67 and asparagine 52. Enzymatic hydrolysis of one of those fragments by aminopeptidase M supported this identification. The position of the chromic ion implies what is the path of electron transfer from the chromous ion to the ferric ion in this chemical reduction of cytochrome c, and suggests a possible path of electron transfer in biological oxidation-reduction reactions.