Search

Phanerochaete chrysosporium has been thoroughly studied as a microbial model for lignin degradation. The enzymes lignin peroxidase (LiP) and manganese peroxidase (MnP), both encoded by several genes, play the main role in the cleavage of different lignin substructures. In this work, the expression of specific LiP and MnP transcripts in liquid medium and in a wood-containing soil system was studied by reverse transcription-PCR and subsequent cloning and sequencing of the products obtained. Splice variants of different LiP and MnP transcripts were observed in wood-containing soil incubations and in liquid cultures. The processed transcripts contained different numbers of complete introns. Since the presence of stop codons in several of these introns would prevent the synthesis of active enzyme, we propose that these transcripts arise as a result of incomplete processing rather than alternative splicing. Interestingly, analysis of splice variants from mnp genes led to the identification of a fourth actively transcribed gene coding for MnP in P. chrysosporium.

The comprehensive study of microorganisms that evolved in the Atacama Desert, the driest and oldest on earth, may help to understand the key role of water for life. In this context, we previously characterized the microenvironment that allows colonization of the underside of quartzes in the Coastal Range of this desert by hypolithic microorganisms (Azua-Bustos et al. Microb Ecol 58:568-581, 2011). Now, we describe the biodiversity composition of these biofilms and the isolation from it of a new cyanobacterial strain. Based on morphologic and phylogenetic analyses, this isolate (AAB1) was classified as a new member of the Gloeocapsopsis genus. Physiological, morphological and molecular responses by isolate AAB1 show that this strain is extremely tolerant to desiccation. Our results also indicate that the isolate biosynthesizes sucrose and trehalose in response to this stressful condition. We identified two candidate genes involved in sucrose synthesis, namely sucrose 6-phosphate synthase and sucrose 6-phosphate phosphatase. Thus, the Gloeocapsopsis isolate AAB1 may represent a suitable model for understanding tolerance to low water availability.

Caves represent an interesting habitat for searching life in extreme environments, since they offer a stable protected environment from harsh and changing outside prevailing conditions. Here we report that in a coastal cave of the hyperarid Atacama Desert, a member of the ancient eukaryote red algae Cyanidium group was found forming a seemingly monospecific biofilm growing under extremely low photon flux levels. Our work suggests that this species, Cyanidium sp. Atacama, is a new member of a recently proposed novel monophyletic lineage of mesophilic “cave” Cyanidium sp., distinct from the remaining three other lineages which are all thermo-acidophilic. The cave described here may be acting as an evolutionary island for life in the midst of the Atacama.

Presentamos un caso raro de comunicación ventrículo izquierdo-aurícula derecha (defecto tipo Gerbode) asociado a traumatismo torácico cerrado, que incluye los hallazgos ecocardiográficos e intraoperatorios. El paciente fue operado exitosamente. Ocasionalmente, se encuentra las comunicaciones ventrículo izquierdo-aurícula derecha adquiridas en la población adulta que pueden suceder como resultado de endocarditis o en el reemplazo de la válvula aórtica. We present a rare case of left ventricular-to-right atrial communication (Gerbode type defect) associated with blunt thoracic trauma, including echocardiogram and surgical findings. The patient had a successful intervention. Acquired left ventricular-to-right atrial shunts are encountered occasionally in the adult population as a result of aortic valve replacement endocarditis.

In this report we describe the isolation and characterization of a gene encoding the transcription factor Acel (Activation protein of cup 1 Expression) in the white rot fungus Phanerochaete chrysosporium. Pc-acel encodes a predicted protein of 633 amino acids containing the copper-fist DNA binding domain typically found in fungal transcription factors such as Acel, Macl and Haal from Saccharomyces cerevisiae. The Pc-acel gene is localized in Scaffold 5, between coordinates 220841 and 222983. A S. cerevisiae acel null mutant strain unable to grow in high-copper medium was fully complemented by transformation with the cDNA of Pc-acel. Moreover, Northern blot hybridization studies indicated that Pc-acel cDNA restores copper inducibility of the yeast cup 1 gene, which encodes the metal-binding protein metallothionein implicated in copper resistance. To our knowledge, this is first report describing an Acel transcription factor in basidiomycetes

Ceriporiopsis subvermispora is a white-rot basidiomycete that produces several isoenzymes of manganese peroxidase (MnP· ). A cDNA of one of them (MnP13-1) has been isolated and sequenced. The deduced aminoacid sequence shows about 60% similarity with the MnPs from Phanerochaete chrysosporium. Based on the crystal structures of MnP and lignin peroxidase (LiP) from P. chrysosporium, and of a peroxidase from Arthromyces ramosus (ARP), we have modeled by homology the three dimensional structure of MnP13-1 using standard modeling procedures. Local molecular mechanics optimization performed in the region corresponding to the binding sites of Ca2+ and Mn2+ in MnP13-1 demonstrated that the stereochemistry and the geometry of binding are conserved in both MnPs. A putative aromatic binding site in MnP13-1 is described. We also report structural differences between the two MnPs, arising from the insertion in MnP13-1 of the sequences TGGN between residues S230 and D231 and TDSP at the C-terminal, both of which may have functional significance.