The bacterial strain Collimonas fungivorans Ter331 (CfTer331) inhibits mycelial growth and spore germination in Aspergillus niger N402 (AnN402). The mechanisms underlying this antagonistic bacterial-fungal interaction have been extensively studied, but knowledge on the long-term outcome of this interaction is currently lacking. Here, we used experimental evolution to explore the dynamics of fungal adaptation to recurrent exposure to CfTer331. Specifically, five single-spore isolates (SSIs) of AnN402 were evolved under three selection scenarios in liquid culture, i.e., (i) in the presence of CfTer331 for 80 growth cycles, (ii) in the absence of the bacterium for 80 cycles, and (iii) in the presence of CfTer331 for 40 cycles and then in its absence for 40 cycles. The evolved SSI lineages were then evaluated for phenotypic changes from the founder fungal strain, such as germinability with or without CfTer331. The analysis showed that recurrent exposure to CfTer331 selected for fungal lineages with reduced germinability and slower germination, even in the absence of CfTer331. In contrast, when AnN402 evolved in the absence of the bacteria, lineages with increased germinability and faster germination were favored. SSIs that were first evolved in the presence of CfTer331 and then in its absence showed intermediate phenotypes but overall were more similar to SSIs that evolved in the absence of CfTer331 for 80 cycles. This suggests that traits acquired from exposure to CfTer331 were reversible upon removal of the selection pressure. Overall, our study provides insights into the effects on fungi from the long-term coculture with bacteria. IMPORTANCE The use of antagonistic bacteria for managing fungal diseases is becoming increasingly popular, and thus there is a need to understand the implications of their long-term use against fungi. Most efforts have so far focused on characterizing the antifungal properties and mode of action of the bacterial antagonists, but the possible outcomes of the persisting interaction between antagonistic bacteria and fungi are not well understood. In this study, we used experimental evolution in order to explore the evolutionary aspects of an antagonistic bacterial-fungal interaction, using the antifungal bacterium Collimonas fungivorans and the fungus Aspergillus niger as a model system. We show that evolution in the presence or absence of the bacteria selects for fungal lineages with opposing and conditionally beneficial traits, such as slow and fast spore germination, respectively. Overall, our studies reveal that fungal responses to biotic factors related to antagonism could be to some extent predictable and reversible.

Exploiting RNA interference (RNAi) in disease control through non-transformative methods that overcome the hurdle of producing transgenic plants has attracted much attention over the last years. Here, we explored such a method and used non-pathogenic bacteria as a versatile system for delivering RNAi to fungi. Specifically, the RNaseIII-null mutant strain of Escherichia coli HT115(DE3) was transformed with two plasmid vectors that enabled the constitutive or IPTG-inducible production of double-stranded RNAs (dsRNAs) against genes involved in aflatoxins production in Aspergillus flavus (AflC) or virulence of Botrytis cinerea (BcSAS1). To facilitate the release of the dsRNAs, the bacterial cells were further genetically engineered to undergo a bacteriophage endolysin R-mediated autolysis, following a freeze-thaw cycle. Exposure under in vitro conditions of A. flavus or B. cinerea to living bacteria or their whole-cell autolysates induced silencing of AflC and BcSAS1 in a bacteria concentration-dependent manner, and instigated a reduction in aflatoxins production and mycelial growth, respectively. In planta applications of the living bacteria or their crude whole-cell autolysates produced similar results, thus creating a basis for translational research. These results demonstrate that bacteria can produce biologically active dsRNA against target genes in fungi and that bacteria-mediated RNAi can be used to control fungal pathogens.

Layered BC₃, a metastable phase within the binary boron-carbon system that is composed of graphite-like sheets with hexagonally symmetric C₆B₆ units, has never been successfully crystallized. Instead, poorly-crystalline BC₃-like materials with significant stacking disorder have been isolated, based on the co-pyrolysis of a boron trihalide precursor with benzene at around 800 °C. The halide leaving group (-X) is a significant driving force of these reactions, but the subsequent evolution of gaseous HX species at such high temperatures hampers their scaling up and also prohibits their further use in the presence of hard-casting templates such as ordered silicates. Herein, we report a novel halide-free synthesis route to turbostratic BC₃ with long-range in-plane ordering, as evidenced by multi-wavelength Raman spectroscopy. Judicious pairing of the two molecular precursors is crucial to achieving B-C bond formation and preventing phase-segregation into the thermodynamically favored products. A simple computational method used herein to evaluate the compatibility of bottom-up molecular precursors can be generalized to guide the future synthesis of other metastable materials beyond the boron-carbon system.

Leveillula taurica is a major pathogen of tomato and several other crops that can cause substantial yield losses in favorable conditions for the fungus. Quinone outside inhibitor fungicides (Q_oIs) are routinely used for the control of the pathogen in tomato fields across California, but their recurrent use could lead to the emergence of resistance against these compounds. Here, we partially cloned the cytochrome b gene from L. taurica (Lt cytb) and searched within populations of the fungus collected from tomato fields across California for mutations that confer resistance to Q_oIs. A total of 21 single nucleotide polymorphisms (SNPs) were identified within a 704 bp fragment of the Lt cytb gene analyzed, of which five were non-synonymous substitutions. Among the most frequent SNPs encountered within field populations of the pathogen was the G143A substitution that confers high levels of resistance against Q_oIs in several fungi. The other four amino acid substitutions were novel mutations, whose effect on Q_oI resistance is currently unknown. Sequencing of the Lt cytb gene from individual single-cell conidia of the fungus further revealed that most SNPs, including the one leading to the G143A substitution, were present in a heteroplasmic state, indicating the co-existence of multiple mitotypes in single cells. Analysis of the field samples showed that the G143A substitution is predominantly heteroplasmic also within field populations of L. taurica in California, suggesting that Q_oI resistance in this fungus is likely to be quantitative rather than qualitative.

Abnormal polyglutamine (polyQ) tracts are the only common feature in nine proteins that each cause a dominant neurodegenerative disorder. In Huntington's disease, tracts longer than 36 glutamines in the protein huntingtin (htt) cause degeneration. In situ, monoclonal antibody 3B5H10 binds to different htt fragments in neurons in proportion to their toxicity. Here, we determined the structure of 3B5H10 Fab to 1.9 Å resolution by X-ray crystallography. Modeling demonstrates that the paratope forms a groove suitable for binding two β-rich polyQ strands. Using small-angle X-ray scattering, we confirmed that the polyQ epitope recognized by 3B5H10 is a compact two-stranded hairpin within monomeric htt and is abundant in htt fragments unbound to antibody. Thus, disease-associated polyQ stretches preferentially adopt compact conformations. Since 3B5H10 binding predicts degeneration, this compact polyQ structure may be neurotoxic.

Medullary carcinoma of the thyroid gland accounts foronly 5-10% of thyroid carcinomas. Also, metastases tothe skin of malignant tumors are infrequently (2-9%of patients). In the case herein reported in a 64-yearoldwoman, a metastatic nodule on the scalp wasthe presenting clinical manifestation of a medullarythyroid carcinoma. A comprehensive review of theliterature was conducted for similar cases usingPubMed. Only 18 cases of cutaneous metastases ofmedullary thyroid carcinoma have been previouslyreported in the literature, but skin lesions were thepresenting complaint of the thyroid neoplasm in onlythree.

Background

The effect of HIV pre-exposure prophylaxis (PrEP) depends on uptake, adherence, and sexual practices. We aimed to assess these factors in a cohort of HIV-negative people at risk of infection.

Methods

In our cohort study, men and transgender women who have sex with men previously enrolled in PrEP trials (ATN 082, iPrEx, and US Safety Study) were enrolled in a 72 week open-label extension. We measured drug concentrations in plasma and dried blood spots in seroconverters and a random sample of seronegative participants. We assessed PrEP uptake, adherence, sexual practices, and HIV incidence. Statistical methods included Poisson models, comparison of proportions, and generalised estimating equations.

Findings

We enrolled 1603 HIV-negative people, of whom 1225 (76%) received PrEP. Uptake was higher among those reporting condomless receptive anal intercourse (416/519 [81%] vs 809/1084 [75%], p=0·003) and having serological evidence of herpes (612/791 [77%] vs 613/812 [75%] p=0·03). Of those receiving PrEP, HIV incidence was 1·8 infections per 100 person-years, compared with 2·6 infections per 100 person-years in those who concurrently did not choose PrEP (HR 0·51, 95% CI 0·26-1·01, adjusted for sexual behaviours), and 3·9 infections per 100 person-years in the placebo group of the previous randomised phase (HR 0·49, 95% CI 0·31-0·77). Among those receiving PrEP, HIV incidence was 4·7 infections per 100 person-years if drug was not detected in dried blood spots, 2·3 infections per 100 person-years if drug concentrations suggested use of fewer than two tablets per week, 0·6 per 100 person-years for use of two to three tablets per week, and 0·0 per 100 person-years for use of four or more tablets per week (p<0·0001). PrEP drug concentrations were higher among people of older age, with more schooling, who reported non-condom receptive anal intercourse, who had more sexual partners, and who had a history of syphilis or herpes.

Interpretation

PrEP uptake was high when made available free of charge by experienced providers. The effect of PrEP is increased by greater uptake and adherence during periods of higher risk. Drug concentrations in dried blood spots are strongly correlated with protective benefit.

Funding

US National Institutes of Health.

African-American men have the highest incidence of and mortality from prostate cancer. Whether a biological basis exists for this disparity remains unclear. Exome sequencing (n = 102) and targeted validation (n = 90) of localized primary hormone-naïve prostate cancer in African-American men identified several gene mutations not previously observed in this context, including recurrent loss-of-function mutations in ERF, an ETS transcriptional repressor, in 5% of cases. Analysis of existing prostate cancer cohorts revealed ERF deletions in 3% of primary prostate cancers and mutations or deletions in ERF in 3% to 5% of lethal castration-resistant prostate cancers. Knockdown of ERF confers increased anchorage-independent growth and generates a gene expression signature associated with oncogenic ETS activation and androgen signaling. Together, these results suggest that ERF is a prostate cancer tumor-suppressor gene. More generally, our findings support the application of systematic cancer genomic characterization in settings of broader ancestral diversity to enhance discovery and, eventually, therapeutic applications.Significance: Systematic genomic sequencing of prostate cancer in African-American men revealed new insights into prostate cancer, including the identification of ERF as a prostate cancer gene; somatic copy-number alteration differences; and uncommon PIK3CA and PTEN alterations. This study highlights the importance of inclusion of underrepresented minorities in cancer sequencing studies. Cancer Discov; 7(9); 973-83. ©2017 AACR.This article is highlighted in the In This Issue feature, p. 920.