Search for: All records

The fungus Candida albicans is the most common cause of yeast infections in humans. Like many other disease-causing microbes, it releases several virulent proteins that invade and damage human cells. This includes the peptide candidalysin which has been shown to be crucial for infection. Human cells are surrounded by a protective membrane that separates their interior from their external environment. Previous work showed that candidalysin damages the cell membrane to promote infection. However, how candidalysin does this remained unclear. Similar peptides and proteins cause harm by inserting themselves into the membrane and then grouping together to form a ring. This creates a hole, or ‘pore’, that weakens the membrane and allows other molecules into the cell’s interior. Here, Russell, Schaefer et al. show that candidalysin uses a unique pore forming mechanism to impair the membrane of human cells. A combination of biophysical and cell biology techniques revealed that the peptide groups together to form a chain. This chain of candidalysin proteins then closes in on itself to create a loop structure that can insert into the membrane to form a pore. Once embedded within the membrane, the proteins within the loops rearrange again to make the pores more stable so they can cause greater damage. This type of pore formation has not been observed before, and may open up new avenues of research. For instance, researchers could use this information to develop inhibitors that stop candidalysin from forming chains and harming the membranes of cells. This could help treat the infections caused by C. albicans. 

Red mineral pigment use is recognized as a fundamental component of a series of traits associated with human evolutionary development, social interaction, and behavioral complexity. Iron-enriched mineral deposits have been collected and prepared as pigment for use in rock art, personal adornment, and mortuary practices for millennia, yet little is known about early developments in mineral processing techniques in North America. Microanalysis of rock art pigments from the North American Pacific Northwest reveals a sophisticated use of iron oxide produced by the biomineralizing bacteriumLeptothrix ochracea;a keystone species of chemolithotroph recognized in recent advances in the development of thermostable, colorfast biomaterial pigments. Here we show evidence for human engagement with this bacterium, including nanostructural and magnetic properties evident of thermal enhancement, indicating that controlled use of pyrotechnology was a key feature of how biogenic iron oxides were prepared into paint. Our results demonstrate that hunter-gatherers in this area of study prepared pigments by harvesting aquatic microbial iron mats dominated by iron-oxidizing bacteria, which were subsequently heated in large open hearths at a controlled range of 750 °C to 850 °C. This technical gesture was performed to enhance color properties, and increase colorfastness and resistance to degradation. This skilled production of highly thermostable and long-lasting rock art paint represents a specialized technological innovation. Our results contribute to a growing body of knowledge on historical-ecological resource use practices in the Pacific Northwest during the Late Holocene.

Figshare link to figures:https://figshare.com/s/9392a0081632c20e9484.