Earth and Life Institute ELI

Louvain-la-Neuve, Belgium

Earth and Life Institute ELI

Louvain-la-Neuve, Belgium
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Teets N.M.,Ohio State University | Peyton J.T.,Ohio State University | Ragland G.J.,University of Notre Dame | Ragland G.J.,Catholic University of Leuven | And 5 more authors.
Physiological Genomics | Year: 2012

The ability to respond rapidly to changes in temperature is critical for insects and other ectotherms living in variable environments. In a physiological process termed rapid cold-hardening (RCH), exposure to nonlethal low temperature allows many insects to significantly increase their cold tolerance in a matter of minutes to hours. Additionally, there are rapid changes in gene expression and cell physiology during recovery from cold injury, and we hypothesize that RCH may modulate some of these processes during recovery. In this study, we used a combination of transcriptomics and metabolomics to examine the molecular mechanisms of RCH and cold shock recovery in the flesh fly, Sarcophaga bullata. Surprisingly, out of ~15,000 expressed sequence tags (ESTs) measured, no transcripts were upregulated during RCH, and likewise RCH had a minimal effect on the transcript signature during recovery from cold shock. However, during recovery from cold shock, we observed differential expression of ~1,400 ESTs, including a number of heat shock proteins, cytoskeletal components, and genes from several cell signaling pathways. In the metabolome, RCH had a slight yet significant effect on several metabolic pathways, while cold shock resulted in dramatic increases in gluconeogenesis, amino acid synthesis, and cryoprotective polyol synthesis. Several biochemical pathways showed congruence at both the transcript and metabolite levels, indicating that coordinated changes in gene expression and metabolism contribute to recovery from cold shock. Thus, while RCH had very minor effects on gene expression, recovery from cold shock elicits sweeping changes in gene expression and metabolism along numerous cell signaling and biochemical pathways. © 2012 the American Physiological Society.

Michiels J.-F.,Institute Des Science Of La Vie | Sart S.,Institute Des Science Of La Vie | Schneider Y.-J.,Institute Des Science Of La Vie | Agathos S.N.,Institute Des Science Of La Vie | Agathos S.N.,Earth and Life Institute ELI
Process Biochemistry | Year: 2011

High quality (glyco)proteins are needed for biopharmaceutical applications. They are generally expressed as recombinant proteins in bacteria, yeast, plant and/or animal cells in culture. Growth media are increasingly supplemented with peptones to improve either the cell growth or protein expression or both. To further enhance protein production, it is important to understand the effects of peptones at the cellular and molecular levels. Upon addition of a soy peptone to a cultivation medium of CHO cells, an increased specific productivity was observed. This work aimed at elucidating which main cellular functions are affected by the presence of the peptone. Therefore, hypotheses about putative effects on recombinant protein production steps have been postulated and tested. Although the effects emerge to be multiple, it was found that the peptone increased overall protein translation and recombinant protein secretion. Nonetheless, when other cellular functions (e.g. transcription, glycosylation, proteolytic degradation) were examined, no specific effects were observed. Further experiments are needed to probe the mechanisms related to the influence of the soy peptone on these cellular functions. © 2011 Elsevier Ltd. All rights reserved.

Maris M.N.A.,University Utrecht | De Boer B.,University Utrecht | Ligtenberg S.R.M.,University Utrecht | Crucifix M.,Earth and Life Institute ELI | And 2 more authors.
Cryosphere | Year: 2014

We present the effects of changing two sliding parameters, a deformational velocity parameter and two bedrock deflection parameters on the evolution of the Antarctic ice sheet over the period from the last interglacial until the present. These sensitivity experiments have been conducted by running the dynamic ice model ANICE forward in time. The temporal climatological forcing is established by interpolating between two temporal climate states created with a regional climate model. The interpolation is done in such a way that both temperature and surface mass balance follow the European Project for Ice Coring in Antarctica (EPICA) Dome C ice-core proxy record for temperature. We have determined an optimal set of parameter values, for which a realistic grounding-line retreat history and present-day ice sheet can be simulated; the simulation with this set of parameter values is defined as the reference simulation. An increase of sliding with respect to this reference simulation leads to a decrease of the Antarctic ice volume due to enhanced ice velocities on mainly the West Antarctic ice sheet. The effect of changing the deformational velocity parameter mainly yields a change in east Antarctic ice volume. Furthermore, we have found a minimum in the Antarctic ice volume during the mid-Holocene, in accordance with observations. This is a robust feature in our model results, where the strength and the timing of this minimum are both dependent on the investigated parameters. More sliding and a slower responding bedrock lead to a stronger minimum which emerges at an earlier time. From the model results, we conclude that the Antarctic ice sheet has contributed 10.7 ± 1.3 m of eustatic sea level to the global ocean from the last glacial maximum (about 16 ka for the Antarctic ice sheet) until the present. © 2014 Author(s).

Vanzieleghem T.,Earth and Life Institute ELI | Herman-Bausier P.,Catholic University of Louvain | Dufrene Y.F.,Catholic University of Louvain | Mahillon J.,Earth and Life Institute ELI
Langmuir | Year: 2015

Staphylococcus epidermidis is a world-leading pathogen in healthcare facilities, mainly causing medical device-associated infections. These nosocomial diseases often result in complications such as bacteremia, fibrosis, or peritonitis. The virulence of S. epidermidis relies on its ability to colonize surfaces and develop thereupon in the form of biofilms. Bacterial adherence on biomaterials, usually covered with plasma proteins after implantation, is a critical step leading to biofilm infections. The cell surface protein SdrG mediates adhesion of S. epidermidis to fibrinogen (Fg) through a specific "dock, lock, and latch" mechanism, which results in greatly stabilized protein-ligand complexes. Here, we combine single-molecule, single-cell, and whole population assays to investigate the extent to which the surface density of SdrG determines the ability of S. epidermidis clinical strains HB, ATCC 35984, and ATCC 12228 to bind to Fg-coated surfaces. Strains that showed enhanced adhesion on Fg-coated polydimethylsiloxane (PDMS) were characterized by increased amounts of SdrG proteins on the cell surface, as observed by single-molecule analysis. Consistent with previous reports showing increased expression of SdrG following in vivo exposure, this work provides direct evidence that abundance of SdrG on the cell surface of S. epidermidis strains dramatically improves their ability to bind to Fg-coated implanted medical devices. © 2015 American Chemical Society.

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