Viral metacommunities associated to bats and rodents at different spatial scales

One of the main goals of community ecology is to measure the relative importance of environmental filters to understand patterns of species distribution at different temporal and spatial scales. Likewise, the identification of factors that shape symbiont metacommunity structures is important in disease ecology because resulting structures drive disease transmission. We tested the hypothesis that distributions of virus species and viral families from rodents and bats are defined by shared responses to host phylogeny and host functional characteristics, shaping the viral metacommunity structures at four spatial scales (Continental, Biogeographical, Zoogeographical, and Regional). The contribution of host phylogeny and host traits to the metacommunity of viruses at each spatial scale was calculated using a redundant analysis of canonical ordering (RDA). For rodents, at American Continental scale the coherence of viral species metacommunity increased while the spatial scale decreased and Quasi-Clementsian structures were observed. This pattern suggests a restricted distribution of viruses through their hosts, while in the Big Mass (Europe, Africa, and Asia), the coherence decreased as spatial scale decreased. Viral species metacommunities associated with bats was dominated by random structures along all spatial scales. We suggest that this random pattern is a result of the presence of viruses with high occupancy range such as rabies (73%) and coronavirus (27%), that disrupt such structures. At viral family scale, viral metacommunities associated with bats showed coherent structures, with the emergence of Quasi- Clementsian and Checkerboard structures. RDA analysis indicates that the assemblage of viral diversity associated with rodents and bats responds to phylogenetic and functional characteristics, which alternate between spatial scales. Several of these variations could be subject to the spatial scale, in spite of this, we could identify patterns at macro ecological scale. The application of metacommunity theory at symbiont scales is particularly useful for large-scale ecological analysis. Understanding the rules of host-virus association can be useful to take better decisions in epidemiological surveillance, control and even predictions of viral distribution and dissemination

Effect of a heterotrimeric G protein α subunit on conidia germination, stress response, and roquefortine C production in Penicillium roqueforti

Summary. Heterotrimeric G protein signaling regulates many processes in fungi, such as development, pathogenicity, and secondary metabolite biosynthesis. For example, the Gα subunit Pga1 from Penicillium chrysogenum regulates conidiation and secondary metabolite production in this fungus. The dominant activating allele, pga1G42R, encoding a constitutively active Pga1 Gα subunit, was introduced in Penicillium roqueforti by transformation, resulting in a phenotype characterized by low sporulation and slow growth. In this work, the effect of the constitutively active Pga1G42R Gα subunit on conidial germination, stress tolerance, and roquefortine C production of P. roqueforti was studied. Pga1G42R triggered germination in the absence of a carbon source, in addition to negatively regulating thermal and osmotic stress tolerance. The presence of the Pga1G42R Gα subunit also had an important effect on roquefortine C biosynthesis, increasing production and maintaining high levels of the mycotoxin throughout a culture period of 30 days. Together, the results suggest that G protein-mediated signaling participates in the regulation of these three processes in P. roqueforti. [Int Microbiol 2009; 12(2):123-129

Filamentous fungi from extreme environments as a promising source of novel bioactive secondary metabolites

Natural product search is undergoing resurgence upon the discovery of a huge previously unknown potential for secondary metabolite (SM) production hidden in microbial genomes. This is also the case for filamentous fungi, since their genomes contain a high number of orphan SM gene clusters. Recent estimates indicate that only 5% of existing fungal species have been described, thus the potential for the discovery of novel metabolites in fungi is huge. In this context, fungi thriving in harsh environments are of particular interest since they are outstanding producers of unusual chemical structures. At present, there are around 16 genomes from extreme environment-isolated fungi in databases. In a preliminary analysis of three of these genomes we found that several of the predicted SM gene clusters are probably involved in the biosynthesis of compounds not yet described. Genome mining strategies allow the exploitation of the information in genome sequences for the discovery of new natural compounds. The synergy between genome mining strategies and the expected abundance of secondary metabolites in fungi from extreme environments is a promising path to discover new natural compounds as a source of medically useful drugs

Coronaviruses in bats from Mexico

Bats are reservoirs for a wide range of human pathogens including Nipah, Hendra, rabies, Ebola, Marburg and severe acute respiratory syndrome coronavirus (CoV). The recent implication of a novel beta (β)-CoV as the cause of fatal respiratory disease in the Middle East emphasizes the importance of surveillance for CoVs that have potential to move from bats into the human population. In a screen of 606 bats from 42 different species in Campeche, Chiapas and Mexico City we identified 13 distinct CoVs. Nine were alpha (α)-CoVs, four were β-CoVs. Twelve were novel. Analyses of these viruses in the context of their hosts and ecological habitat indicated that host species is a strong selective driver in CoV evolution, even in allopatric populations separated by significant geographical distance, and that a single species/genus of bat can contain multiple CoVs. A β-CoV with 96.5 % amino acid identity to the β-CoV associated with human disease in the Middle East was found in a Nyctinomops laticaudatus bat, suggesting that efforts to identify the viral reservoir should include surveillance of the bat families Molossidae/Vespertilionidae, or the closely related Nycteridae/Emballonuridae. While it is important to investigate unknown viral diversity in bats, it is also important to remember that the majority of viruses they carry will not pose any clinical risk, and bats should not be stigmatized ubiquitously as significant threats to public health

Identification and Functional Analysis of the Mycophenolic Acid Gene Cluster of Penicillium roqueforti.

The filamentous fungus Penicillium roqueforti is widely known as the ripening agent of blue-veined cheeses. Additionally, this fungus is able to produce several secondary metabolites, including the meroterpenoid compound mycophenolic acid (MPA). Cheeses ripened with P. roqueforti are usually contaminated with MPA. On the other hand, MPA is a commercially valuable immunosuppressant. However, to date the molecular basis of the production of MPA by P. roqueforti is still unknown. Using a bioinformatic approach, we have identified a genomic region of approximately 24.4 kbp containing a seven-gene cluster that may be involved in the MPA biosynthesis in P. roqueforti. Gene silencing of each of these seven genes (named mpaA, mpaB, mpaC, mpaDE, mpaF, mpaG and mpaH) resulted in dramatic reductions in MPA production, confirming that all of these genes are involved in the biosynthesis of the compound. Interestingly, the mpaF gene, originally described in P. brevicompactum as a MPA self-resistance gene, also exerts the same function in P. roqueforti, suggesting that this gene has a dual function in MPA metabolism. The knowledge of the biosynthetic pathway of MPA in P. roqueforti will be important for the future control of MPA contamination in cheeses and the improvement of MPA production for commercial purposes

The pcz1 gene, which encodes a Zn(II)2Cys6 protein, is involved in the control of growth, conidiation, and conidial germination in the filamentous fungus Penicillium roqueforti.

Proteins containing Zn(II)(2)Cys(6) domains are exclusively found in fungi and yeasts. Genes encoding this class of proteins are broadly distributed in fungi, but few of them have been functionally characterized. In this work, we have characterized a gene from the filamentous fungus Penicillium roqueforti that encodes a Zn(II)(2)Cys(6) protein, whose function to date remains unknown. We have named this gene pcz1. We showed that the expression of pcz1 is negatively regulated in a P. roqueforti strain containing a dominant active Gαi protein, suggesting that pcz1 encodes a downstream effector that is negatively controlled by Gαi. More interestingly, the silencing of pcz1 in P. roqueforti using RNAi-silencing technology resulted in decreased apical growth, the promotion of conidial germination (even in the absence of a carbon source), and the strong repression of conidiation, concomitant with the downregulation of the genes of the central conidiation pathway brlA, abaA and wetA. A model for the participation of pcz1 in these physiological processes in P. roqueforti is proposed

The biosynthetic gene cluster for andrastin A in Penicillium roqueforti

© 2017 Rojas-Aedo, Gil-Durán, Del-Cid, Valdés, álamos, Vaca, García-Rico, Levicán, Tello and Chávez. Penicillium roqueforti is a filamentous fungus involved in the ripening of several kinds of blue cheeses. In addition, this fungus produces several secondary metabolites, including the meroterpenoid compound andrastin A, a promising antitumoral compound. However, to date the genomic cluster responsible for the biosynthesis of this compound in P. roqueforti has not been described. In this work, we have sequenced and annotated a genomic region of approximately 29.4 kbp (named the adr gene cluster) that is involved in the biosynthesis of andrastin A in P. roqueforti. This region contains ten genes, named adrA, adrC, adrD, adrE, adrF, adrG, adrH, adrI, adrJ and adrK. Interestingly, the adrB gene previously found in the adr cluster from P. chrysogenum, was found as a residual pseudogene in the adr cluster from P. roqueforti. RNA-mediated gene silencing of each of the ten genes resulted in s

Role of sfk1 gene in the filamentous fungus Penicillium roqueforti

© 2017 Torrent, Gil-Durán, Rojas-Aedo, Medina, Vaca, Castro, García-Rico, Cotoras, Mendoza, Levicán and Chávez. The sfk1 (suppressor of four kinase) gene has been mainly studied in Saccharomyces cerevisiae, where it was shown to be involved in growth and thermal stress resistance. This gene is widely conserved within the phylum Ascomycota. Despite this, to date sfk1 has not been studied in any filamentous fungus. Previously, we found that the orthologous of sfk1 was differentially expressed in a strain of Penicillium roqueforti with an altered phenotype. In this work, we have performed a functional characterization of this gene by using RNAi-silencing technology. The silencing of sfk1 in P. roqueforti resulted in decreased apical growth and the promotion of conidial germination, but interesting, it had no effect on conidiation. In addition, the attenuation of the sfk1 expression sensitized the fungus to osmotic stress, but not to thermal stress. RNA-mediated gene-silencing of sfk1 als

qRT-PCR analysis of the expression of <i>mpa</i> genes in RNAi-silenced transformants of <i>P</i>. <i>roqueforti</i>.

<p>The RNAi-silenced transformants selected were T4 and T7 for <i>mpaA</i>, T1 and T7 for <i>mpaB</i>, T5 and T6 for <i>mpaC</i>, T1 and T2 for <i>mpaDE</i>, T4 and T6 for <i>mpaF</i>, T2 and T3 for <i>mpaG</i>, and T5 and T6 for <i>mpaH</i>. Total RNA extractions and qRT-PCR experiments were conducted as described in Materials and Methods. Wild-type <i>P</i>. <i>roqueforti</i> CECT 2905 (WT) and <i>P</i>. <i>roqueforti</i> CECT 2905 containing empty pJL43-RNAi vector (E) were used as controls. Error bars represent the standard deviation of three replicates in three different experiments. The differences were considered statistically significant at <i>P</i> < 0.05 (*) using Student’s <i>t</i>-test.</p