Annette Cashmore

Candida albicans has a cell-associated ferric-reductase activity which is regulated in response to levels of iron and copper

For survival, pathogenic organisms such as Candida albicans must possess an efficient mechanism for acquiring iron in the iron-restricted environment of the human body. C. albicans can use iron from a variety of sources found within the host. However, it is not clear how biologically active ferrous iron is obtained from these sources. One strategy adopted by some organisms is to reduce iron extracellularly and then specifically transport the ferrous iron into the cell. We have shown that clinical isolates of C. albicans do have a cell-associated ferric-reductase activity. The determination of ferric-reductase activity of cells growing exponentially in either low- or high-iron media over a period of time indicated that C. albicans reductase activity is induced when in low-iron conditions. Moreover, we have demonstrated that C. albicans reductase activity is also regulated in response to the growth phase of the culture, with induction occurring upon exit from stationary phase and maximal levels being reached in early exponential stage irrespective of the iron content of the medium. These results suggest that C. albicans reductase activity is regulated in a very similar manner to the Saccharomyces cerevisiae ferric-reductase. Iron reduction and uptake in S. cerevisiae are closely connected to copper reduction, and possibly copper uptake. In this report we show that iron and copper reduction also appear to be linked in C. albicans. The ferric-reductase activity is negatively regulated by copper. Moreover, quantitative cupric-reductase assays indicated that C. albicans is capable of reducing copper and that this cupric-reductase activity is negatively regulated by both iron and copper. This is the first report that C. albicans has an iron- and copper-mediated ferri-reductase activity.

Candida albicans VPS11 Is Required for Vacuole Biogenesis and Germ Tube Formation

ABSTRACT The Candida albicans vacuole has previously been observed to undergo rapid expansion during the emergence of a germ tube from a yeast cell, to occupy the majority of the parent yeast cell. Furthermore, the yeast-to-hypha switch has been implicated in the virulence of this organism. The class C vps (vacuolar protein sorting) mutants of Saccharomyces cerevisiae are defective in multiple protein delivery pathways to the vacuole and prevacuole compartment. In this study C. albicans homologues of the S. cerevisiae class C VPS genes have been identified. Deletion of a C. albicans VPS11 homologue resulted in a number of phenotypes that closely resemble those of the class C vps mutants of S. cerevisiae, including the absence of a vacuolar compartment. The C. albicans vps11Δ mutant also had much-reduced secreted lipase and aspartyl protease activities. Furthermore, vps11Δ strains were defective in yeast-hypha morphogenesis. Upon serum induction of filamentous growth, mutants showed delayed emergence of germ tubes, had a reduced apical extension rate compared to those of control strains, and were unable to form mature hyphae. These results suggest that Vps11p-mediated trafficking steps are necessary to support the rapid emergence and extension of the germ tube from the parent yeast cell.

Candida albicans CFL1 encodes a functional ferric reductase activity that can rescue a Saccharomyces cerevisiae fre1 mutant.

Candida albicans, like other pathogens, has to compete with the host for a limited supply of available iron. Consequently, iron acquisition is likely to be an important factor for the growth, survival and virulence of this organism. It was previously demonstrated that C. albicans has a surface-associated ferric reductase similar to that of Saccharomyces cerevisiae. Therefore, functional rescue of a S. cerevisiae fre1 mutant was used to isolate a C. albicans ferric reductase gene (CFL1). This gene has been previously identified. However, the workers had not observed any functional reductase activity associated with the gene. The discrepancy with the findings in this report appears to be due to the clone previously reported carrying a non-contiguous piece of C. albicans DNA. Results shown in this paper demonstrate that CFL1 transcription is regulated in response to levels of iron and copper. This is the first demonstration of a functional ferric reductase gene from C. albicans.

Ferric reductase genes involved in high-affinity iron uptake are differentially regulated in yeast and hyphae of Candida albicans

The pathogenic yeast Candida albicans possesses a reductive iron uptake system which is active in iron‐restricted conditions. The sequestration of iron by this mechanism initially requires the reduction of free iron to the soluble ferrous form, which is catalysed by ferric reductase proteins. Reduced iron is then taken up into the cell by a complex of a multicopper oxidase protein and an iron transport protein. Multicopper oxidase proteins require copper to function and so reductive iron and copper uptake are inextricably linked. It has previously been established that Fre10 is the major cell surface ferric reductase in C. albicans and that transcription of FRE10 is regulated in response to iron levels. We demonstrate here that Fre10 is also a cupric reductase and that Fre7 also makes a significant contribution to cell surface ferric and cupric reductase activity. It is also shown, for the first time, that transcription of FRE10 and FRE7 is lower in hyphae compared to yeast and that this leads to a corresponding decrease in cell surface ferric, but not cupric, reductase activity. This demonstrates that the regulation of two virulence determinants, the reductive iron uptake system and the morphological form of C. albicans, are linked. Copyright

Copper-dependent transcriptional regulation by Candida albicans Mac1p.

We have previously shown that copper uptake and regulation in the opportunistic pathogen Candida albicans has some similarities to those in Saccharomyces cerevisiae, including the activation of the copper transporter gene CaCTR1 under low-copper conditions by the transcription factor CaMac1p. However, in this study, further analysis has shown that the actual mechanism of regulation by CaMac1p is different from that of its S. cerevisiae homologue. We demonstrate for the first time, to our knowledge, that the CaMAC1 gene is transcriptionally autoregulated in a copper-dependent manner, in contrast to ScMAC1, which is constitutively transcribed. We also demonstrate that the presence of one copper response element in the promoters of CaCTR1, CaMAC1 and the ferric/cupric reductase gene CaFRE7 is sufficient for normal levels of copper-responsive transcription. In contrast, two promoter elements are essential for normal levels of copper-dependent transcriptional activation by ScMac1p. CaMac1p is also involved in the regulation of the iron-responsive transcriptional repressor gene SFU1 and the alternative oxidase gene AOX2. This work describes a key feature of the copper uptake system in C. albicans that distinguishes it from similar processes in the model yeast S. cerevisiae. The importance of copper uptake in the environment of the human host and the implications for the disease process are discussed.

Young people’s perceptions of mental and physical health in the context of general wellbeing

Objectives: Increased recognition of the need for health education in schools has seen advances in health literacy in recent years. Most of these have focussed on physical health, whereas education about mental health is generally lacking and focussed on tackling stigma rather than promoting good mental health. This study evaluated a pilot intervention designed to improve young people’s understanding of good mental health as a key aspect of wellbeing and explored their perceptions of health and wellbeing. Methods: A total of 218 13-year-olds participated in an interactive workshop about healthy eating, physical activity and mental health. Young people’s understanding and perceptions were assessed through anonymous questionnaires at the start and end of the workshop. Common themes were identified and differences pre- and post-workshop and between girls and boys were analysed. Results: Nearly all young people (100% before, 97% after) perceived being healthy to mean being physically healthy. A minority (8%) also considered mental health to be a component of general health, which increased to 12% after the workshop. Understandings of mental health broadened after the workshop. Interestingly, many mentioned physical health when asked to describe mental health, both before and after the workshop. Girls’ and boys’ responses were similar except for more girls including social relationships in their descriptions of mental health. Conclusion: In this study, we have discovered much about how young people perceive health in general and mental health. Such information is useful for targeting future interventions. Students’ understanding of mental health and its importance to wellbeing can be improved through short combined health interventions.

Use of a cis‐acting mutation to study the role of FLP‐mediated recombination in the maintenance of native yeast 2μm plasmids

The 2μm plasmid encodes a mechanism that ensures the partitioning of the plasmid at cell division. Little is known about the detailed mechanism of this partitioning system; for example, is there equal or unequal distribution of the plasmid molecules at mitosis? The plasmid also encodes a site‐specific recombination system that is thought to be involved in plasmid copy‐number amplification, although to date there has been no direct evidence that the recombination process itself is important for maintenance. We have identified a natural 2μm variant that has a cis‐acting mutation in the FLP‐mediated recombination system. We show that this plasmid is unable to amplify in vivo. Our results demonstrate that the average copy number per cell is not affected for the mutant but there is a large clonal variation. This is a direct demonstration that plasmid partitioning results in an unequal distribution of plasmids and that FLP‐mediated amplification compensates for this and therefore has an important role in maintenance.

Bioscience Students’ First Year Perspectives through Video Diaries: Home, Family and Student Transitions

Abstract The first year experiences of students are viewed as important in contributing to retention, overall academic success and student satisfaction. As such there is an increased focus on students’ experiences of their first weeks at university. In this paper we describe some findings from a video-diary project through which bioscience students commented on any aspects of their experiences that were significant during their first year. This paper provides the first reflection specifically on the social transitions experienced by bioscience students, showing that their transition to university is not a step change, or even necessarily a linear process but, as noted by Holdsworth (The Sociological Review, 53, 495–519, 2006) should be considered as a series of fragmented transitions. In their diaries, the bioscience students commented upon the process of becoming integrated as part of the university community including the establishment of friendship groups and their changing relationships with their families. There is also exploration of their changing perspectives as the end of term is approached and some of the difficulties of re-adapting to home life. For the bioscience students there are perceived issues around the scheduling and amount of contact hours compared with their peers from other subjects and also the timing of the first semester examinations. However, the modes of delivery also facilitate integration through the levels of peer-to-peer contact and student–staff contact that typify biological sciences programmes.

Supporting families with Cancer: A patient centred survivorship model of care.

Abstract In 2011, the Leicestershire Clinical Genetics Department in collaboration with Macmillan Cancer Support initiated a project called Supporting Families with Cancer (SFWC). The project aimed to raise awareness of inherited cancers amongst both healthcare professionals and the general public and develop a patient-centred collaborative approach to cancer treatment and support services. This paper describes the project’s development of a range of community outreach events and a training scheme for primary healthcare professionals designed to improve familial cancer referral rates in Leicester. Following consultation with patients and support groups, a series of interactive ‘medical supermarket’ events were held in Leicester. These events focused on providing patients with a forum for sharing research data, information about diagnosis and treatments and access to support groups and other allied healthcare services with additional information being made available digitally via SFWC webpages and a series of short videos available on a YouTube channel. Qualitative and quantitative data presented here indicate that the SFWC medical supermarket model has been well received by patients and offers a patient-centred, holistic approach to cancer treatment.