The role of pheromone receptors for communication and mating in Hypocrea jecorina (Trichoderma reesei)

AbstractDiscovery of sexual development in the ascomycete Trichoderma reesei (Hypocrea jecorina) as well as detection of a novel class of peptide pheromone precursors in this fungus indicates promising insights into its physiology and lifestyle. Here we investigated the role of the two pheromone receptors HPR1 and HPR2 in the H. jecorina pheromone-system.We found that these pheromone receptors show an unexpectedly high genetic variability among H. jecorina strains. HPR1 and HPR2 confer female fertility in their cognate mating types (MAT1-1 or MAT1-2, respectively) and mediate induction of fruiting body development. One compatible pheromone precursor–pheromone receptor pair (hpr1–hpp1 or hpr2–ppg1) in mating partners was sufficient for sexual development. Additionally, pheromone receptors were essential for ascospore development, hence indicating their involvement in post-fertilisation events.Neither pheromone precursor genes nor pheromone receptor genes of H. jecorina were transcribed in a strictly mating type dependent manner, but showed enhanced expression levels in the cognate mating type. In the presence of a mating partner under conditions favoring sexual development, transcript levels of pheromone precursors were significantly increased, while those of pheromone receptor genes do not show this trend. In the female sterile T. reesei strain QM6a, transcriptional responses of pheromone precursor and pheromone receptor genes to a mating partner were clearly altered compared to the female fertile wild-type strain CBS999.97. Consequently, a delayed and inappropriate response to the mating partner may be one aspect causing female sterility in QM6a

Light-dependent roles of the G-protein α subunit GNA1 of Hypocrea jecorina (anamorph Trichoderma reesei)

<p>Abstract</p> <p>Background</p> <p>The filamentous ascomycete <it>Hypocrea jecorina </it>(anamorph <it>Trichoderma reesei</it>) is primarily known for its efficient enzymatic machinery that it utilizes to decompose cellulosic substrates. Nevertheless, the nature and transmission of the signals initiating and modulating this machinery are largely unknown. Heterotrimeric G-protein signaling represents one of the best studied signal transduction pathways in fungi.</p> <p>Results</p> <p>Analysis of the regulatory targets of the G-protein α subunit GNA1 in <it>H. jecorina </it>revealed a carbon source and light-dependent role in signal transduction. Deletion of <it>gna1 </it>led to significantly decreased biomass formation in darkness in submersed culture but had only minor effects on morphology and hyphal apical extension rates on solid medium. Cellulase gene transcription was abolished in Δ<it>gna1 </it>on cellulose in light and enhanced in darkness. However, analysis of strains expressing a constitutively activated GNA1 revealed that GNA1 does not transmit the essential inducing signal. Instead, it relates a modulating signal with light-dependent significance, since induction still required the presence of an inducer. We show that regulation of transcription and activity of GNA1 involves a carbon source-dependent feedback cycle. Additionally we found a function of GNA1 in hydrophobin regulation as well as effects on conidiation and tolerance of osmotic and oxidative stress.</p> <p>Conclusion</p> <p>We conclude that GNA1 transmits a signal the physiological relevance of which is dependent on both the carbon source as well as the light status. The widespread consequences of mutations in GNA1 indicate a broad function of this Gα subunit in appropriation of intracellular resources to environmental (especially nutritional) conditions.</p

Click-correlative light and electron microscopy (click-AT-CLEM) for imaging and tracking azido-functionalized sphingolipids in bacteria

Sphingolipids, including ceramides, are a diverse group of structurally related lipids composed of a sphingoid base backbone coupled to a fatty acid side chain and modified terminal hydroxyl group. Recently, it has been shown that sphingolipids show antimicrobial activity against a broad range of pathogenic microorganisms. The antimicrobial mechanism, however, remains so far elusive. Here, we introduce 'click-AT-CLEM', a labeling technique for correlated light and electron microscopy (CLEM) based on the super-resolution array tomography (srAT) approach and bio-orthogonal click chemistry for imaging of azido-tagged sphingolipids to directly visualize their interaction with the model Gram-negative bacterium Neisseria meningitidis at subcellular level. We observed ultrastructural damage of bacteria and disruption of the bacterial outer membrane induced by two azido-modified sphingolipids by scanning electron microscopy and transmission electron microscopy. Click-AT-CLEM imaging and mass spectrometry clearly revealed efficient incorporation of azido-tagged sphingolipids into the outer membrane of Gram-negative bacteria as underlying cause of their antimicrobial activity

Cosegregation of novel mitochondrial 16S rRNA gene mutations with the age-associated T414G variant in human cybrids

Ever increasing evidence has been provided on the accumulation of mutations in the mitochondrial DNA (mtDNA) during the aging process. However, the lack of direct functional consequences of the mutant mtDNA load on the mitochondria-dependent cell metabolism has raised many questions on the physiological importance of the age-related mtDNA variations. In the present work, we have analyzed the bioenergetic properties associated with the age-related T414G mutation of the mtDNA control region in transmitochondrial cybrids. The results show that the T414G mutation does not cause per se any detectable bioenergetic change. Moreover, three mtDNA mutations clustered in the 16S ribosomal RNA gene cosegregated together with the T414G in the same cybrid cell line. Two of them, namely T1843C and A1940G, are novel and associate with a negative bioenergetic phenotype. The results are discussed in the more general context of the complex heterogeneity and the dramatic instability of the mitochondrial genome during cell culture of transmitochondrial cybrids

Synthesis and Characterization of Ceramide-Containing Liposomes as Membrane Models for Different T Cell Subpopulations

A fine balance of regulatory (Treg) and conventional CD4+ T cells (Tconv) is required to prevent harmful immune responses, while at the same time ensuring the development of protective immunity against pathogens. As for many cellular processes, sphingolipid metabolism also crucially modulates the Treg/Tconv balance. However, our understanding of how sphingolipid metabolism is involved in T cell biology is still evolving and a better characterization of the tools at hand is required to advance the field. Therefore, we established a reductionist liposomal membrane model system to imitate the plasma membrane of mouse Treg and Tconv with regards to their ceramide content. We found that the capacity of membranes to incorporate externally added azide-functionalized ceramide positively correlated with the ceramide content of the liposomes. Moreover, we studied the impact of the different liposomal preparations on primary mouse splenocytes in vitro. The addition of liposomes to resting, but not activated, splenocytes maintained viability with liposomes containing high amounts of C16-ceramide being most efficient. Our data thus suggest that differences in ceramide post-incorporation into Treg and Tconv reflect differences in the ceramide content of cellular membranes

Spin-texture inversion in the giant Rashba semiconductor BiTeI

Semiconductors with strong spin-orbit interaction as the underlying mechanism for the generation of spin-polarized electrons are showing potential for applications in spintronic devices. Unveiling the full spin texture in momentum space for such materials and its relation to the microscopic structure of the electronic wave functions is experimentally challenging and yet essential for exploiting spin-orbit effects for spin manipulation. Here we employ a state-of-the-art photoelectron momentum microscope with a multichannel spin filter to directly image the spin texture of the layered polar semiconductor BiTeI within the full two-dimensional momentum plane. Our experimental results, supported by relativistic ab initio calculations, demonstrate that the valence and conduction band electrons in BiTeI have spin textures of opposite chirality and of pronounced orbital dependence beyond the standard Rashba model, the latter giving rise to strong optical selection-rule effects on the photoelectron spin polarization. These observations open avenues for spin-texture manipulation by atomic-layer and charge carrier control in polar semiconductors.This work was supported by DFG (through SFB 1170 'ToCoTronics') and through FOR1162 (P3). We acknowledge the support by the Basque Departamento de Educacion, UPV/EHU (Grant Number IT-756-13), Spanish Ministerio de Economia y Competitividad (MINECO Grant Number FIS2013-48286-C2-2-P), Tomsk State University Academic D.I. Mendeleev Fund Program in 2015 (Research Grant Number 8.1.05.2015), the Russian Foundation for Basic Research (Grant Numbers 15-02-01797 and 15-02-589 02717). Partial support by the Saint Petersburg State University (Grant Number 15.61.202.2015) is also acknowledged

The ITS2 Database III—sequences and structures for phylogeny

The internal transcribed spacer 2 (ITS2) is a widely used phylogenetic marker. In the past, it has mainly been used for species level classifications. Nowadays, a wider applicability becomes apparent. Here, the conserved structure of the RNA molecule plays a vital role. We have developed the ITS2 Database (http://its2.bioapps.biozentrum.uni-wuerzburg.de) which holds information about sequence, structure and taxonomic classification of all ITS2 in GenBank. In the new version, we use Hidden Markov models (HMMs) for the identification and delineation of the ITS2 resulting in a major redesign of the annotation pipeline. This allowed the identification of more than 160 000 correct full length and more than 50 000 partial structures. In the web interface, these can now be searched with a modified BLAST considering both sequence and structure, enabling rapid taxon sampling. Novel sequences can be annotated using the HMM based approach and modelled according to multiple template structures. Sequences can be searched for known and newly identified motifs. Together, the database and the web server build an exhaustive resource for ITS2 based phylogenetic analyses

The Grizzly, February 2, 1993

Cowboys Tame Buffalo, 52-17 • Upsilon Phi Delta Approved • AIDS Quilt • Al Eaton\u27s We Are the Dream • Day For a King • Power Plays • Bernie Bernie Headflap Wins Battle of the Bands • Lorelei at Chateau Granieri • Ice Skating Fun • The Case of the Disappearing Sevs (Or: Why Collegeville\u27s Most Famous Convenient Mart Upped & Left) • Senior Profile: Chris Kakacek • The New Zack\u27s: Why Hike to WaWa? • What\u27s Up in Wellness • Character was an Issue, Again • The Importance of Effort and A Dream • UC Baseball Preview \u2793 • Gymnasts Hoping For Powerful Season • Lady Bears Make Playoffs • Swimmers Working Hard • Football Awards Banquet Held • Wrestlers Continue Excellence • Men\u27s Basketball Split Twohttps://digitalcommons.ursinus.edu/grizzlynews/1308/thumbnail.jp