Biology subjects

Roth, C.

Publications and source records attributed to Roth, C..

24 records · Page 2Linked to original sources

bioRxiv2021

Epistatic genetic interactions govern morphogenesis during sexual reproduction and infection in a global human fungal pathogen

Cellular development is orchestrated by evolutionarily conserved signaling pathways, which are often pleiotropic and involve intra- and inter-pathway epistatic interactions that form intricate, complex regulatory networks. Cryptococcus species are a group of closely-related human fungal pathogens that grow as yeasts yet transition to hyphae during sexual reproduction. Additionally, during infection they can form large, polyploid titan cells that evade immunity and develop drug resistance. Multiple known signaling pathways regulate cellular development, yet how these are coordinated and interact with genetic variation is less well understood. Here, we conducted quantitative trait locus (QTL) analyses of a mapping population generated by sexual reproduction of two parents, only one of which is unisexually fertile. We observed transgressive segregation of the unisexual phenotype among progeny, as well as a novel large-cell phenotype under mating-inducing conditions. These large-cell progeny were found to produce titan cells both in vitro and in infected animals. Two major QTLs and corresponding quantitative trait genes (QTGs) were identified: RIC8 (encoding a guanine-exchange factor) and CNC06490 (encoding a putative Rho-GTPase activator), both involved in G-protein signaling. The two QTGs interact epistatically with each other and with the mating-type locus in phenotypic determination. These findings provide insights into the complex genetics of morphogenesis during unisexual reproduction and pathogenic titan cell formation and illustrate how QTL analysis can be applied to identify epistasis between genes. This study shows that phenotypic outcomes are influenced by the genetic background upon which mutations arise, implicating dynamic, complex genotype-to-phenotype landscapes in fungal pathogens and beyond. Significance statementCellular development is regulated by a complex web of signaling pathways that respond to both intracellular and extracellular cues. Morphological transitions in pathogenic fungi, such as those observed during sexual reproduction or in response to the host environment, offer tractable models for understanding the principles that govern eukaryotic cell development and morphogenesis. Using the human fungal pathogen Cryptococcus deneoformans as a model and applying QTL analysis, we defined novel genes and gene-gene interactions involved in the yeast-hyphal transition and titanization, two morphological developments that are important for adaptation, pathogenesis, and evolution of this fungal pathogen. Our study provides new insights into the conservation and complexity of key signaling pathways in regulating cell development in fungi, as well as other eukaryotes.

genetics↗

bioRxiv2021

Rampant transposition following RNAi loss causes hypermutation and antifungal drug resistance in clinical isolates of a human fungal pathogen

Microorganisms survive and compete by stochastically acquiring mutations that enhance fitness. Although increased mutation rates are often deleterious in multicellular organisms, hypermutation can be beneficial for microbes experiencing strong selective pressures. Infections caused by Cryptococcus neoformans are responsible for [~]15% of AIDS-related deaths and associated with high mortality rates, attributable to a dearth of antifungal drugs and drug resistance. We identified two hypermutator C. neoformans clinical isolates in which Cnl1 transposon insertions were responsible for drug resistance. Whole-genome sequencing revealed both hypermutator genomes harbor a nonsense mutation in the RNAi component ZNF3 and hundreds of Cnl1 elements organized into massive subtelomeric arrays on every chromosome. QTL mapping identified a significant locus associated with hypermutation that included znf3. CRISPR-mediated editing of the znf3 nonsense mutation abolished hypermutation and restored siRNA production. In sum, hypermutation and drug resistance in these isolates results from RNAi loss and a significant burden of Cnl1 elements.

microbiology↗

bioRxiv2020

Functional requirement of the Arabidopsis importin-α nuclear transport receptor family in autoimmunity mediated by the NLR protein SNC1

IMPORTIN-3/MOS6 (MODIFIER OF SNC1, 6) is one of nine importin- isoforms in Arabidopsis that recruit nuclear localization signal (NLS)-containing cargo proteins to the nuclear import machinery. IMP-3/MOS6 is required genetically for full autoimmunity of the nucleotide-binding leucine-rich repeat (NLR) immune receptor mutant snc1 (suppressor of npr1-1, constitutive 1) and MOS6 also contributes to basal disease resistance. Here, we investigated the contribution of the other importin- genes to both types of immune responses, and we analyzed potential interactions of all importin- isoforms with SNC1. By using reverse-genetic analyses in Arabidopsis and protein-protein interaction assays in N. benthamiana we provide evidence that among the nine -importins in Arabidopsis, IMP-3/MOS6 is the main nuclear transport receptor of SNC1, and that IMP-3/MOS6 is required selectively for autoimmunity of snc1 and basal resistance to mildly virulent Pseudomonas syringae in Arabidopsis. SIGNIFICANCE STATEMENTSpecific requirement for the Arabidopsis -importin MOS6 in snc1-mediated autoimmunity is explained by selective formation of MOS6-SNC1 nuclear import complexes.

plant biology↗

bioRxiv2018

Targeting neuronal and glial cell types with synthetic promoter AAVs in mice, non-human primates, and humans

Targeting genes to specific neuronal or glial cell types is valuable both for understanding and for repairing brain circuits. Adeno-associated viral vectors (AAVs) are frequently used for gene delivery, but targeting expression to specific cell types is a challenge. We created a library of 230 AAVs, each with a different synthetic promoter designed using four independent strategies. We show that ~11% of these AAVs specifically target expression to neuronal and glial cell types in the mouse retina, mouse brain, non-human primate retina in vivo, and in the human retina in vitro. We demonstrate applications for recording, stimulation, and molecular characterization, as well as the intersectional and combinatorial labeling of cell types. These resources and approaches allow economic, fast, and efficient cell-type targeting in a variety of species, both for fundamental science and for gene therapy.

neuroscience↗

bioRxiv2017

A High Resolution Map of Meiotic Recombination in Cryptococcus Demonstrates Decreased Recombination in Unisexual Reproduction

Multiple species within the basidiomycete genus, Cryptococcus, cause cryptococcal disease. These species are estimated to affect nearly a quarter of a million people leading to approximately 180,000 mortalities, annually. Sexual repro-duction, which can occur between haploid yeasts of the same or opposite mating type, is a potentially important contributor to pathogenesis as recombination can generate novel genotypes and transgressive phenotypes. However, our quantitative understanding of recombination in this clinically important yeast is limited. Here we describe genome-wide estimates of recombination rates in Cryptococcus deneoformans and compare recombination between progeny from - unisexual and a- bisexual crosses. We find that offspring from bisexual crosses have modestly higher average rates of recombination than those derived from unisexual crosses. Recombination hot and cold spots across the C. deneoformans genome are also identified and are associated with increased GC content. Finally, we observed regions genome-wide with allele frequencies deviating from the expected parental ratio. These findings and observations advance our quantitative understanding of the genetic events that occur during sexual reproduction in C. deneoformans, and the impact that different forms of sexual reproduction are likely to have on genetic diversity in this important fungal pathogen.

genetics↗

bioRxiv2017

The maternal genetic make-up of the Iberian Peninsula between the Neolithic and the Early Bronze Age

Agriculture first reached the Iberian Peninsula around 5700 BCE. However, little is known about the genetic structure and changes of prehistoric populations in different geographic areas of Iberia. In our study, we focused on the maternal genetic makeup of the Neolithic ([~] 5500-3000 BCE), Chalcolithic ([~] 3000-2200 BCE) and Early Bronze Age ([~] 2200-1500 BCE). We report ancient mitochondrial DNA results of 213 individuals (151 HVS-I sequences) from the northeast, central, southeast and southwest regions and thus on the largest archaeogenetic dataset from the Peninsula to date. Similar to other parts of Europe, we observe a discontinuity between hunter-gatherers and the first farmers of the Neolithic. During the subsequent periods, we detect regional continuity of Early Neolithic lineages across Iberia, however the genetic contribution of hunter-gatherers is generally higher than in other parts of Europe and varies regionally. In contrast to ancient DNA findings from Central Europe, we do not observe a major turnover in the mtDNA record of the Iberian Late Chalcolithic and Early Bronze Age, suggesting that the population history of the Iberian Peninsula is distinct in character.

genetics↗