We previously identified and characterized three mnp genes coding for manganese peroxidase (MnP) in the white rot fungus Ceriporiopsis subvermispora. In this work, we assessed transcript levels of mnp genes in liquid cultures of this fungus grown under various conditions. In the absence of Mn(2+), mnp1 and mnp2 mRNA were detected by Northern hybridization, irrespective of the lack of extracellular MnP activity. Addition of Mn(2+) to the cultures led to a marked increase in both transcripts, the highest titers being observed at 10 micro M Mn(2+). mnp1 mRNA was not detected at Mn(2+ )concentrations above 80 micro M, whereas mnp2 mRNA was still observed at 320 micro M Mn(2+). Differential regulation of these genes was confirmed by the addition of Cu(2+), Zn(2+), Ag(+) and Cd(2+). These metal ions dramatically elevated both transcripts and also allowed the detection of the mnp3 transcript. In most cases, the increase in mRNA levels was partially abolished by the simultaneous presence of Mn(2+), although the latter was strictly required to detect extracellular MnP activity. However, the lignin-related compound syringic acid specifically increased the mnp1 transcript, although only in the absence of Mn(2+). These results indicate that there is no clear correlation between mnp mRNA levels and MnP activity. In addition, they strongly suggest that Mn(2+) plays a post-transcriptional role which is essential for the presence of active MnP in the extracellular fluid.

The authors have previously identified and characterized lcs, a gene encoding laccase in the white-rot basidiomycete Ceriporiopsis subvermispora. In this work, the effect of Mn2+ in the production of extracellular laccase in liquid cultures of this fungus has been assessed. It was observed that at low (0-10 microM) concentrations of Mn2+, high titers of lcs-mRNA were obtained, whereas at high (160-194 microM) concentrations of this metal ion, transcripts levels decreased markedly. This phenomenon was observed at different days of growth. On the other hand, Cu2+ or Ag+, but not Zn2+ or Cd2+, led to an accumulation of lcs transcripts only in cultures grown in the absence of Mn2+. A dramatic increase in lcs transcript levels was also obtained with syringic acid, a lignin-related aromatic compound. This effect was more pronounced in cultures lacking Mn2+. In the course of these studies it was observed that Mn2+ stimulates mycelium growth. Thus, although extracellular laccase activity appeared higher in cultures containing 160 or 194 microM Mn2+, i.e. when lcs transcripts were lower, a correlation between lcs-mRNA levels and enzymatic activity was observed when values of the latter were corrected by the amount of mycelium present in the cultures.

Analysis of genomic clones encoding a putative laccase in homokaryon strains of Ceriporiopsis subvermispora led to the identification of an allelic variant of the previously described lcs-1 gene. A cDNA clone corresponding to this gene was expressed in Aspergillus nidulans and in Aspergillus niger. Enzyme assays and Western blots showed that both hosts secreted active laccase. Relative to the isozymic forms of the native C. subvermispora enzyme, the A. niger-produced laccase had a higher molecular mass and gave a single band on IEF gels. In contrast, A. nidulans transformants secreted several isoforms remarkably similar to those of the native system. Considered together with previously reported Southern blots and protein sequencing, expression in A. nidulans supports the view that C. subvermispora has a single laccase gene and that multiple isoforms result from post-translational processes. In addition, several lines of evidence strongly suggest that under copper limitation, A. nidulans secretes apoprotein which can be reconstituted by a short incubation with Cu(I) and to a lesser extent with Cu(II).

The area of channels and fjords belonging to the Magellan subantarctic has a high diversity of macroalgae, in relation to the temperate areas of South America. Geomorphological changes, the geographical position in a high latitude together with the climate change in this region create a series of coast marine habitats with a significant environmental heterogeneity, where a diverse benthic marine flora take place, which are not still known, that has evolved in an adaptive way to these changes. This research was developed under the 16 fjords CIMAR program in 2010, aboard the scientific research vessel Abate Molina, under the "Marine Benthic macroalgae of the Region of Magallanes and Chilean Antarctica "project. This paper gives information about a total of 57 species of macroalgae in the region, with representatives of the Rhodophyta (51%), Ochrophyta (Class Phaeophyceae) (37%) and Divisions Chlorophyta (12%). Takes into account the floristic affinities of the sectors studied and deals with the flora of the Antarctic continent, and also incorporates 7 novel macroalgal references to the subantarctic Magellan ecoregion.