In the yeast Saccharomyces cerevisiae, environmental stress conditions that damage the cell wall lead to activation of the so-called "compensatory mechanism," aimed at preserving cell integrity through a remodeling of this extracellular matrix. Here we used DNA microarrays to investigate the molecular basis of this response to two agents that induce transient cell wall damage; namely Congo Red and Zymolyase. Treatment of the cells with these two agents elicited the up-regulation of 132 and 101 genes respectively, the main functional groups among them being involved in cell wall construction and metabolism. The main response does not occur until hours after exposure to the cell wall-perturbing agent. In some cases, this response was transient, but more sustained in others, especially in the case of the genes involved in cell wall remodeling. Clustering of these data together with those from the response to constitutive cell wall damage, revealed the existence of a cluster of co-regulated genes that was strongly induced under all conditions assayed. Those genes induced by cell wall damage showed an enrichment in DNA binding motifs for Rlm1p, Crz1p, SBF (Swi4p/ Swi6p), Msn2p/Msn4p, Ste12p, and Tec1p transcription factors, suggesting a complex regulation of this response together with the possible involvement of several signaling pathways. With the exception of PHO89 and FKS2, none of the genes induced by Congo Red was up-regulated in a slt2 strain. Moreover, characterization of the transcriptional response to Congo Red in a rlm1 mutant strain revealed that only a few genes (i.e. PHO89, FKS2, YLR042C, and CHA1) were induced at least partially independently of the transcription factor Rlm1p, the rest being totally dependent on this transcription factor for their activation. Our findings consistently demonstrate that the cell integrity signaling pathway regulates the cell wall damage compensatory response, mainly through transcriptional activation mediated by Rlm1p.

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h i g h l i g h t sORP measurement can be used for nitrate supply control. Biogas desulphurization was achieved without a reduction in methane concentration. A high EC CRIT of 120 g S m À3 h À1 can be achieved using polypropylene Pall rings.a r t i c l e i n f o b s t r a c tHydrogen sulphide (H 2 S) is one of the most problematic contaminants in biogas. In this study, a biotrickling filter with a working volume of 2.4 L and packed with polypropylene Pall rings was tested for its ability to remove H 2 S from biogas under anoxic conditions. The influence of the H 2 S inlet concentration, nitrate feeding regime (manual and controlled) and liquid flow rate on the elimination capacity of the biotrickling filter was studied. The results indicate that 99% of the H 2 S was removed for H 2 S inlet loads lower than 120 g S m À3 h À1 when using controlled nitrate feeding by ORP.

The objective of this work was to determine the frequency and clinical associations of anti-ribosomal P protein antibodies (Anti-P) in a cohort of Chilean patients with systemic lupus erythematosus (SLE). Between 1996 and 1998, 141 consecutive patients with SLE were examined prospectively according with a standard protocol. Disease activity was measured by MEX-SLEDAI in 138 patients. Anti-P positivity was determined by double immune diffusion or Western blot and ELISA. Anti-P was found in 21 (15%) patients. In the Anti-P positive patients recent onset SLE (disease duration of 1 year or less) was more frequent (P = 0.018). Anti-P was found in 23% of 83 patients with active SLE vs 4% of the 55 patients with inactive SLE (Yates corrected P = 0.00479). An association with anti-dsDNA antibodies by Farr assay was observed. Anti-P positive patients had a median Farr of 65 IU/ml (1.4-1240) and Anti-P negative of 12 IU/ml (1.4-992; P-value = 0.0084). During the study only two patients had lupus psychosis and they were Anti-P positive. No association was found with liver disease (six patients, two with Anti-P antibodies) or active glomerulonephritis (22 patients four with Anti-P). Our data shows that the presence of Anti-P antibodies supports the clinical diagnosis of lupus psychosis.

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