The Cch1-Mid1 High-Affinity Calcium Channel Contributes to the Virulence of Cryptococcus neoformans by Mitigating Oxidative Stress.

Pathogenic fungi have developed mechanisms to cope with stresses imposed by hosts. For Cryptococcus spp., this implies active defense mechanisms that attenuate and ultimately overcome the onslaught of oxidative stresses in macrophages. Among cellular pathways within Cryptococcus neoformans' arsenal is the plasma membrane high-affinity Cch1-Mid1 calcium (Ca(2+)) channel (CMC). Here we show that CMC has an unexpectedly complex and disparate role in mitigating oxidative stress. Upon inhibiting the Ccp1-mediated oxidative response pathway with antimycin, strains of C. neoformans expressing only Mid1 displayed enhanced growth, but this was significantly attenuated upon H2O2 exposure in the absence of Mid1, suggesting a regulatory role for Mid1 acting through the Ccp1-mediated oxidative stress response. This notion is further supported by the interaction detected between Mid1 and Ccp1 (cytochrome c peroxidase). In contrast, Cch1 appears to have a more general role in promoting cryptococci survival during oxidative stress. A strain lacking Cch1 displayed a growth defect in the presence of H2O2 without BAPTA [(1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, cesium salt] or additional stressors such as antimycin. Consistent with a greater contribution of Cch1 to oxidative stress tolerance, an intracellular growth defect was observed for the cch1Δ strain in the macrophage cell line J774A.1. Interestingly, while the absence of either Mid1 or Cch1 significantly compromises the ability of C. neoformans to tolerate oxidative stress, the absence of both Mid1 and Cch1 has a negligible effect on C. neoformans growth during H2O2 stress, suggesting the existence of a compensatory mechanism that becomes active in the absence of CMC

Sterols from stems of Momordica cochinchinesis (Lour.) Spreng.

Three known sterols, polypodine B (1), (22E,24R)-24-methylcholesta-2,22-diene-3β,5α,6β-triol (2) and chondrillasterol (3) were isolated from the stems of Momordica cochinchinesis (Lour.) Spreng. Their chemical structures were successfully determined using NMR and ESI-MS analysis as well as in comparison with the reported data. All compounds were reported from Momordica genus for the first time. Keywords. Momordica cochinchinesis, Cucurbitaceae, steroid

Impact of biological clogging and pretreatments on the operation of soil aquifer treatments for wastewater reclamation

Globally, sustainable water management is required to minimize water security, and soil aquifer treatments (SATs) are widely applied in wastewater reclamation. Clogging problems limit the sustainable operation of SATs (i.e., the decrease of infiltration rate), and Physical clogging has been widely studied. However, the effect of biological clogging on the operation of SATs is still unclear. Thus, this study focuses on the effects of biological clogging in an SAT system and demonstrates that the clogging process in an SAT column. In this study, the infiltration rate in the A2O ​+ ​NaN3 water column decreased slightly, to 6–7 ​cm/h with an average rate of 0.01 ​cm/h per month after 240 ​d, compared with an average rate of 0.3 ​cm/h per month in the columns fed by filtered A2O water. The fastest reduction in infiltration rate, caused by biological clogging, occurred in the first 60 ​d and corresponded to the highest reduction in hydraulic conductivity of 0–2.5 ​cm layer. For alleviating clogging, this study illustrated that removing suspended solids from A2O water by filtration helped reduce approximately 25% of polysaccharides and heterotrophic bacteria. In comparison, pre-ozonation of A2O water helped to reduce approximately 70% of the biomass in the surface layer of the A2O ​+ ​O3 column. Thus, ozonation of wastewater effluent helps control biological clogging in SAT

Invasion of the central nervous system by Cryptococcus neoformans requires a secreted fungal metalloprotease.

UnlabelledCryptococcus spp. cause life-threatening fungal infection of the central nervous system (CNS), predominantly in patients with a compromised immune system. Why Cryptococcus neoformans has this remarkable tropism for the CNS is not clear. Recent research on cerebral pathogenesis of C. neoformans revealed a predominantly transcellular migration of cryptococci across the brain endothelium; however, the identities of key fungal virulence factors that function specifically to invade the CNS remain unresolved. Here we found that a novel, secreted metalloprotease (Mpr1) that we identified in the extracellular proteome of C. neoformans (CnMpr1) is required for establishing fungal disease in the CNS. Mpr1 belongs to a poorly characterized M36 class of fungalysins that are expressed in only some fungal species. A strain of C. neoformans lacking the gene encoding Mpr1 (mpr1Δ) failed to breach the endothelium in an in vitro model of the human blood-brain barrier (BBB). A mammalian host infected with the mpr1Δ null strain demonstrated significant improvement in survival due to a reduced brain fungal burden and lacked the brain pathology commonly associated with cryptococcal disease. The in vivo studies further indicate that Mpr1 is not required for fungal dissemination and Mpr1 likely targets the brain endothelium specifically. Remarkably, the sole expression of CnMPR1 in Saccharomyces cerevisiae resulted in a robust migration of yeast cells across the brain endothelium, demonstrating Mpr1's specific activity in breaching the BBB and suggesting that Mpr1 may function independently of the hyaluronic acid-CD44 pathway. This distinct role for Mpr1 may develop into innovative treatment options and facilitate a brain-specific drug delivery platform.ImportanceCryptococcus neoformans is a medically relevant fungal pathogen causing significant morbidity and mortality, particularly in immunocompromised individuals. An intriguing feature is its strong neurotropism, and consequently the hallmark of cryptococcal disease is a brain infection, cryptococcal meningoencephalitis. For C. neoformans to penetrate the central nervous system (CNS), it first breaches the blood-brain barrier via a transcellular pathway; however, the identities of fungal factors required for this transmigration remain largely unknown. In an effort to identify extracellular fungal proteins that could mediate interactions with the brain endothelium, we undertook a proteomic analysis of the extracellular proteome and identified a secreted metalloprotease (Mpr1) belonging to the M36 class of fungalysins. Here we found that Mpr1 promotes migration of C. neoformans across the brain endothelium and into the CNS by facilitating attachment of cryptococci to the endothelium surface, thus underscoring the critical role of M36 proteases in fungal pathogenesis

Cryptococcal Meningitis and Anti-virulence Therapeutic Strategies

Fungal infections of the central nervous system are responsible for significant morbidity and mortality. Cryptococcus neoformans (Cn) is the primary cause of fungal meningitis. Infection begins in the lung after inhalation of fungal spores but often spreads to other organs, particularly the brain in immunosuppressed individuals. Cn’s ability to survive phagocytosis and endure the onslaught of oxidative attack imposed by the innate immune response facilitates dissemination to the central nervous system (CNS). Despite the success of Cn at bypassing innate immunity, entry into the heavily protected brain requires that Cn overwhelm the highly restricted blood-brain barrier (BBB). This is a formidable task but mounting evidence suggests that Cn expresses surface-bound and secreted virulence factors including urease, metalloprotease, and hyaluronic acid that can undermine the BBB. In addition, Cn can exploit multiple routes of entry to gain access to the CNS. In this review, we discuss the cellular and molecular interface of Cn and the BBB, and we propose that the virulence factors mediating BBB crossing could be targeted for the development of anti-virulence drugs aimed at preventing fungal colonization of the CNS

Flavonoid glycosides from Viscum album

Using combined chromatographic methods, four flavonoid glycosides, (2S)-homoeriodictyol-7-O-β-D-apiofuranosyl-(1→2)-O-β-D-glucopyranoside (1), (2S)-5-hydroxy-7,3′-dimethoxyflavanone-4′-O-β-D-apiofuranosyl-(1→2)-O-β-D-glucopyranoside (2), homoflavoyadorinin-B (3), and 3′-methoxyapiin (4) were isolated from the methanol extract of the leaves and twigs of Viscum album. Their structures were elucidated by 1D- and 2D-NMR spectra and in comparison with those reported in the literature. Keywords. Viscum album, flavonoid glycoside

Macropinocytosis as a potential mechanism driving neurotropism of Cryptococcus neoformans

Cryptococcus neoformans can invade the central nervous system by crossing the blood-brain barrier via a transcellular mechanism that relies on multiple host factors. In this narrative, we review the evidence that a direct interplay between C. neoformans and brain endothelial cells forms the basis for invasion and transmigration across the brain endothelium. Adherence and internalization of C. neoformans is dependent on transmembrane proteins, including a hyaluronic acid receptor and an ephrin receptor tyrosine kinase. We consider the role of EphA2 in facilitating the invasion of the central nervous system by C. neoformans and highlight experimental evidence supporting macropinocytosis as a potential mechanism of internalization and transcytosis. How macropinocytosis might be conclusively demonstrated in the context of C. neoformans is also discussed

A Survey on Reconfigurable System-on-Chips

The requirements for high performance and low power consumption are becoming more and more inevitable when designing modern embedded systems, especially for the next generation multi-mode multimedia or communication standards. Ultra large-scale integration reconfigurable System-on-Chips (SoCs) have been proposed to achieve not only better performance and lower energy consumption but also higher flexibility and versatility in comparison with the conventional architectures. The unique characteristic of such systems is integration of many types of heterogeneous reconfigurable processing fabrics based on a Network-on-Chip. This paper analyzes and emphasizes the key research trends of the reconfigurable System-on-Chips (SoCs). Firstly, the emerging hardware architecture of SoCs is highlighted. Afterwards, the key issues of designing the reconfigurable SoCs are discussed, with the focus on the challenges when designing reconfigurable hardware fabrics and reconfigurable Network-on-Chips. Finally, some state-of-the-art reconfigurable SoCs are briefly discussed