Biology subjects

Pfeifer, M. A.

Publications and source records attributed to Pfeifer, M. A..

3 recordsLinked to original sources

bioRxiv2021

Promising or problematic? Perceptions of active learning from STEM students with ADHD and specific learning disabilities

STEM instructors are encouraged to adopt active learning in their courses, yet our understanding of how active learning affects different groups of students is still developing. One group often overlooked in higher education research is students with disabilities. Two of the most commonly occurring disabilities on college campuses are attention-deficit/hyperactivity disorder (ADHD) and specific learning disorders (SLD). We investigated how the incorporation of active-learning practices influences the learning and self-advocacy experiences of students with ADHD and/or SLD (ADHD/SLD) in undergraduate STEM courses. Semi-structured interviews with 25 STEM majors with ADHD/SLD were conducted and data were analyzed using qualitative methods. Most participants perceived themselves to learn best in a STEM course with at least some elements of active learning. Participants described how they perceived active learning to support or hinder their learning and how active learning affected their self-advocacy. Active-learning barriers could be attributed to a combination of instructional factors. These factors included how a particular active-learning practice was implemented within a STEM course and limited awareness of universal design for learning. Defining the supports and barriers perceived by students with ADHD/SLD is a crucial first step in developing more inclusive active-learning STEM courses. Suggestions for research and teaching are provided.

scientific communication and education↗

bioRxiv2021

The mitotic spindle mediates nuclear migration through an extremely narrow infection structure of the rice blast fungus Magnaporthe oryzae

The blast fungus, Magnaporthe oryzae, causes severe destruction to rice and other crops worldwide. As the fungus infects rice, it develops unique cellular structures, such as an appressorium and a narrow penetration peg, to permit successful invasion of host rice cells. Fundamental knowledge about these cellular structures and how organelles, such as the nucleus, are positioned within them is still emerging. Previous studies show that a single nucleus becomes highly stretched during movement through the narrow penetration peg in an extreme nuclear migration event. Yet, the mechanism permitting this nuclear migration event remains elusive. Here, we investigate the role of the mitotic spindle in mediating nuclear migration through the penetration peg. We find that disruption of spindle function during nuclear migration through the penetration peg prevents development of invasive hyphae and virulence on rice. Furthermore, regulated expression of conserved kinesin motor proteins, MoKin5 and MoKin14, is essential to form and maintain the spindle, as well as, properly nucleate the primary hypha. Overexpression of MoKin5 leads to formation of aberrant microtubule protrusions, which contributes to formation of nuclear fragments within the appressorium and primary hypha. Conversely, overexpression of MoKin14 causes the spindle to collapse leading to the formation of monopolar spindles. These results establish a mechanistic model towards understanding the intricate subcellular dynamics of extreme nuclear migration through the penetration peg, a critical step in the development of rice blast disease. ImportanceMagnaporthe oryzae, also known as the blast fungus, is a formidable hinderance to global food production, including rice. The destructive fungal pathogen develops highly-specialized cells and structures, such as appressoria and penetration pegs, to permit successful invasion of rice cells. Our understanding of M. oryzaes fundamental biology during host cell invasion and colonization is still developing. For instance, it is not yet known how organelles, such as the nucleus, migrate through the narrow penetration peg. Moreover, few previous studies examine the role of motor proteins in M. oryzae. In this study, we determined that the mitotic spindle propels a single nucleus through the penetration peg to permit successful development of fungal hyphae inside the first-invaded rice cell. We also identified two conserved kinesin motor proteins, MoKin5 and MoKin14. Our analyses suggested that MoKin5 and MoKin14 exhibit canonical functions in M. oryzae during rice infection. This study addressed long-standing questions in rice blast biology, and our results offer opportunities for future research.

cell biology↗

bioRxiv2020

Role of two metacaspases in development and pathogenicity of the Rice Blast fungus, Magnaporthe oryzae

Rice blast disease caused by Magnaporthe oryzae is a devastating disease of cultivated rice worldwide. Infections by this fungus lead to a significant reduction in rice yields and threats to food security. To gain better insight into growth and cell death in M. oryzae during infection, we characterized two predicted M. oryzae metacaspase proteins, MoMca1 and MoMca2. These proteins appear to be functionally redundant and are able to complement the yeast Yca1 homologue. Biochemical analysis revealed that M. oryzae metacaspases exhibited Ca2+ dependent caspase activity in vitro. Deletion of both MoMca1 and MoMca2 in M. oryzae resulted in reduced sporulation, delay in conidial germination and attenuation of disease severity. In addition, the double {Delta}Momca1mca2 mutant strain showed increased radial growth in the presence of oxidative stress. Interestingly, the {Delta}Momca1mca2 strain showed an increase accumulation of insoluble aggregates compared to the wild-type strain during vegetative growth. Our findings suggest that MoMca1 and MoMca2 promote the clearance of insoluble aggregates in M. oryzae, demonstrating the important role these metacaspases have in fungal protein homeostasis. Furthermore, these metacaspase proteins may play additional roles, like in regulating stress responses, that would help maintain the fitness of fungal cells required for host infection. IMPORTANCEMagnaporthe oryzae causes rice blast disease that threatens global food security by resulting in the severe loss of rice production every year. A tightly regulated life cycle allows M. oryzae to disarm the host plant immune system during its biotrophic stage before triggering plant cell death in its necrotrophic stage. The ways M. oryzae navigates its complex life cycle remains unclear. This work characterizes two metacaspase proteins with peptidase activity in M. oryzae that are shown to be involved in the regulation of fungal growth and development prior to infection by potentially helping maintain fungal fitness. This study provides new insight into the role of metacaspase proteins in filamentous fungi by illustrating the delays in M. oryzae morphogenesis in the absence of these proteins. Understanding the mechanisms by which M. oryzae morphology and development promote its devastating pathogenicity may lead to the emergence of proper methods for disease control.

microbiology↗