SREB, a GATA Transcription Factor That Directs Disparate Fates in Blastomyces dermatitidis Including Morphogenesis and Siderophore Biosynthesis

Blastomyces dermatitidis belongs to a group of human pathogenic fungi that exhibit thermal dimorphism. At 22°C, these fungi grow as mold that produce conidia or infectious particles, whereas at 37°C they convert to budding yeast. The ability to switch between these forms is essential for virulence in mammals and may enable these organisms to survive in the soil. To identify genes that regulate this phase transition, we used Agrobacterium tumefaciens to mutagenize B. dermatitidis conidia and screened transformants for defects in morphogenesis. We found that the GATA transcription factor SREB governs multiple fates in B. dermatitidis: phase transition from yeast to mold, cell growth at 22°C, and biosynthesis of siderophores under iron-replete conditions. Insertional and null mutants fail to convert to mold, do not accumulate significant biomass at 22°C, and are unable to suppress siderophore biosynthesis under iron-replete conditions. The defect in morphogenesis in the SREB mutant was independent of exogenous iron concentration, suggesting that SREB promotes the phase transition by altering the expression of genes that are unrelated to siderophore biosynthesis. Using bioinformatic and gene expression analyses, we identified candidate genes with upstream GATA sites whose expression is altered in the null mutant that may be direct or indirect targets of SREB and promote the phase transition. We conclude that SREB functions as a transcription factor that promotes morphogenesis and regulates siderophore biosynthesis. To our knowledge, this is the first gene identified that promotes the conversion from yeast to mold in the dimorphic fungi, and may shed light on environmental persistence of these pathogens

Cellulose-Enriched Microbial Communities from Leaf-Cutter Ant (Atta colombica) Refuse Dumps Vary in Taxonomic Composition and Degradation Ability

Deconstruction of the cellulose in plant cell walls is critical for carbon flow through ecosystems and for the production of sustainable cellulosic biofuels. Our understanding of cellulose deconstruction is largely limited to the study of microbes in isolation, but in nature, this process is driven by microbes within complex communities. In Neotropical forests, microbes in leaf-cutter ant refuse dumps are important for carbon turnover. These dumps consist of decaying plant material and a diverse bacterial community, as shown here by electron microscopy. To study the portion of the community capable of cellulose degradation, we performed enrichments on cellulose using material from five Atta colombica refuse dumps. The ability of enriched communities to degrade cellulose varied significantly across refuse dumps. 16S rRNA gene amplicon sequencing of enriched samples identified that the community structure correlated with refuse dump and with degradation ability. Overall, samples were dominated by Bacteroidetes, Gammaproteobacteria, and Betaproteobacteria. Half of abundant operational taxonomic units (OTUs) across samples were classified within genera containing known cellulose degraders, including Acidovorax, the most abundant OTU detected across samples, which was positively correlated with cellulolytic ability. A representative Acidovorax strain was isolated, but did not grow on cellulose alone. Phenotypic and compositional analyses of enrichment cultures, such as those presented here, help link community composition with cellulolytic ability and provide insight into the complexity of community-based cellulose degradation.Biological and Environmental Research/[DE-FC02-07ER64494]/BER/Estados UnidosNational Science Foundation/[DGE-1256259]/NSF/Estados UnidosNational Science Foundation/[DEB-0747002]/NSF/Estados UnidosNational Science Foundation/[MCB-0702025]/NSF/Estados UnidosNational Institutes of Health/[T32 GM07215]/NIH/Estados UnidosUniversidad de Costa Rica/[]/UCR/Costa RicaMinisterio de Ciencia, Tecnología y Telecomunicaciones/[]/MICITT/Costa RicaUniversity of Wisconsin-Madison's Hilldale Undergraduate Faculty Research Fellowship/[]//Estados UnidosUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Biología Celular y Molecular (CIBCM

Multi-level resistive switching in SnSe/SrTiO3 heterostructure based memristor device

202302 bckwVersion of RecordOthersHong Kong GRF grant; Guangdong–Hong Kong–Macao Joint Laboratory for Photonic-Thermal-Electrical Energy Materials and Devices; Hong Kong Polytechnic University; National Natural Science Foundation of China (NSFC); Fundamental Research Funds for the Central Universities; Hong Kong fellowship schemePublishe

Feasibility and effects of virtual reality motor-cognitive training in community-dwelling older people with cognitive frailty : pilot randomized controlled trial

202202 bcvcVersion of RecordOthersThe authors wish to thank Ms Claire Chan and Ms Abigail Kam for their assistance with the intervention implementation. This study would not have been possible without the support of the Innovation and Technology Fund for Better Living (application number ITB/FBL/4015/19/P); School of Nursing, The Hong Kong Polytechnic University for providing financial support; and Pok Oi Hospital for providing logistic and administrative support.Publishe

Profile of mood states and quality of life of Chinese postmastectomy women in Hong Kong: Integrating variable- and person-centered approaches.

Understanding the mood state and its relationship with quality of life (QOL) of mastectomy recipients can serve as baseline within which a sound rehabilitation program can be developed. This study therefore was conducted to facilitate a better understanding of participants' postmastectomy mood states, identify their potential predictors, identify clusters of mood profiles, and clarify between-cluster differences in terms of QOL. Hong Kong mastectomy patients completed the Profile of Mood States and Ferrans and Powers Quality of Life Index. We extended the complementary strengths of the application of both variable- and person-centered approaches to clarify relationships and to identify profiles of mood states in relation to QOL in a sample of 200 women who had undergone a mastectomy in Hong Kong. Simultaneous regression identified age and educational attainment as predictors of mood states, and cluster analysis identified three distinct mood profiles that are able to explain differences in various measures of QOL after mastectomy. Implications for future research and practice are discussed

A protocol for simulated experimentation of automated grading systems

Educational systems providing Automated Grading can be very useful for both learner and teacher. After their design and implementation, systems providing automated grading have to be tested and validated, which let the need for real world experiments arise. In this paper we describe an approach to “simulated experiments” that we hope can ease the task of the researchers developing the above mentioned systems. The concept of our proposal is in defining a simulated class by means of statistical distributions of the features that model the student and her/his work in the system. Since such features can be very different from a system to another, we try and keep the description of our framework as general as possible, and define a simulated class by the distribution of the grades that the learners should get (and the system should infer, if correctly working). We show the use of our approach with two systems, that do grading and model the students quite differently. We conclude that our simulation framework can be beneficial in validating an automated grading system, and in allowing to reflect on possible updates of the system, to make its grading more correct