The thermotolerant Arabian killifish,Aphanius dispar, as a novel infection model for human fungal pathogens

Abstract<italic>Candida albicans</italic>: a fungal pathogen, can cause superficial and fatal infections in humans. An important virulence factor in<italic>C. albicans</italic>dissemination is the transformation from yeast to an invasive hyphal form, which is favoured at human body temperature. Zebrafish, a useful model for studying<italic>C. albicans</italic>infections, cannot survive at 37°C. Arabian killifish,<italic>Aphanius dispar</italic>, an emerging teleost model can tolerate temperatures up to 40 °C for up to 12 days (independent feeding time) allowing for longer analysis compared to zebrafish. This study introduces<italic>A. dispar</italic>as a thermo-relevant and a more accurate reporter of the virulence mechanisms relevant to<italic>C. albicans</italic>as a human pathogen. Using<italic>A. dispar</italic>, we tested virulence at human skin (30 °C), body temperature (37 °C) and a high fever condition (40°C). Infection by<italic>C. albicans</italic>at 37°C and 40°C significantly increased virulence, reduced survival of AKF embryos and formed invasive hyphal network compared to 30 °C. Two mutant strains of<italic>C. albicans. pmr1Δ</italic>(with aberrant cell surface glycans) exhibited reduced virulence at 37°C, whereas<italic>rsr1</italic>Δ (lacking a cell polarity marker) showed less virulence at 30 °C. Additionally, anti-fungal treatment rescued AKF survival in a dose-dependent manner, indicating AKF’s potential for<italic>in vivo</italic>drug testing. Our data indicates the quantitative and qualitative importance of examining virulence traits at physiologically relevant temperatures and demonstrates an equivalence to findings for systemic infection derived in mouse models. The<italic>A. dispar</italic>embryo therefore provides an excellent<italic>in vivo</italic>model system for assessing virulence, drug-testing, and real-time imaging of host-pathogen interactions.<sec><title>Significance Statement

The virulence of many pathogens is dependent on host temperature. We demonstrate that theA. disparembryo provides an excellent new thermo-relevant alternative to zebrafish and mouse models, which have limitations in terms of the range of temperatures that can be assessed in real-time. In this study, we have assessedC. albicanstemperature-based virulence, focusing on human body and human skin temperatures (37, 40 and 30 °C, respectively) by examining different genetic backgrounds ofC. albicansstrains. The results indicate differentC. albicansstrains with genetic background show varied virulence depending on temperature indicating importance of examination of virulence mechanisms at physiological temperatures.

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Mon Sep 20 2021

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Key Engineering Materials

Effect of Partial Substitution of Sr by Ba on the Structural Properties of Tl0.8Ni0.2Sr2-xBrxCa2Cu3O9-δ System

Mohammed Abdul Nebi

Rihab Nassr

Shatha

Kareem Ali

Auday H.

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In this manuscript, the effect of substituting strontium with barium on the structural properties of Tl_0.8Ni_0.2Sr_2-xBr_xCa₂Cu₃O_9-δcompound with x= 0, 0.2, 0.4, have been studied. Samples were prepared using solid state reaction technique, suitable oxides alternatives of Pb₂O₃, CaO, BaO and CuO with 99.99% purity as raw materials and then mixed. They were prepared in the form of discs with a diameter of 1.5 cm and a thickness of (0.2-0.3) cm under pressures 7 tons / cm², and the samples were sintered at a constant temperature o

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