Biology subjects

Robinson, K. A.

Publications and source records attributed to Robinson, K. A..

7 recordsLinked to original sources

bioRxiv2024

ALPHA: A High Throughput System for Quantifying Growth In Aquatic Plants

The need for more sustainable agricultural systems is becoming increasingly apparent. The global demand for agricultural products -- food, feed, fuel and fiber -- will continue to increase as the global population continues to grow. This challenge is compounded by climate change. Not only does a changing climate make it difficult to maintain stable yields but current agricultural systems are a major source of greenhouse gas emissions and continue to drive the problem further. Therefore, future agricultural systems must not only increase production but also significantly decrease negative environmental impacts. One approach to addressing this is to begin breeding and cultivating new plant species that have fundamental sustainability advantages over our existing crops. The Lemnaceae, a.k.a duckweeds, are one such species that have potential to increase output and reduce the negative environmental impacts of agricultural production. Herein we describe the Automated Lab-scale PHenotyping Apparatus, ALPHA, for high-throughput phenotyping of Lemnaceae. ALPHA is being used for selective breeding of one species, Lemna gibba, toward the goal of creating a new crop for use in sustainable agricultural systems. ALPHA can be used on many small aquatic plant species to assess growth rates in different environmental conditions. A proof of principle use case is demonstrated where ALPHA is used to determine saltwater tolerance of 6 different varieties of L. gibba.

plant biology↗

bioRxiv2022

Amphibian mucus triggers a developmental transition in the frog-killing chytrid fungus

The frog-killing fungus Batrachochytrium dendrobatidis (Bd) grows within the mucus-coated skin of amphibians. Each lifecycle, Bd transitions from its motile, dispersal form to its sessile growth form in a complex process called encystation. Although encystation is critical to Bd growth, whether and how this developmental transition is triggered by external signals was previously unknown. We discovered that exposure to amphibian mucus triggers rapid and reproducible encystation within minutes. This response can be recapitulated with purified mucin, the bulk component of mucus, but not by similarly-viscous methylcellulose or simple sugars. Mucin-induced encystation does not require gene expression, but does require surface adhesion, calcium signaling, and modulation of the actin cytoskeleton. Mucus-induced encystation may represent a key mechanism for synchronizing Bd development with arrival at the host.

cell biology↗

bioRxiv2020

Establishment and characterisation of primary skeletal muscle cell cultures from patients with advanced Chronic Kidney Disease

Skeletal muscle wasting and dysfunction is a common characteristic of non-dialysis dependent chronic kidney disease (NDD-CKD). The mechanisms by which this occurs are not clearly understood and one reason for this is a lack of well controlled in-vitro methodologies to simulate NDD-CKD induced muscle wasting for mechanistic investigation at the cellular level. Here we sought to conduct the initial investigations into developing a CKD-induced skeletal muscle model for use as a mechanistic analysis tool as well as a test bed for potential novel therapeutics in this population. Human derived muscle cells (HDMCs) were isolated from n=5 NDD-CKD patients and n=3 matched healthy controls (HC) and taken through proliferation and differentiation phases in cell culture. Upon comparison of the 2 donor types, significantly greater mRNA expression of myogenic markers was noted in the NDD-CKD cultures in comparison to HC cultures, which was carried through to greater mRNA expression of myosin heavy chains (MyHCs) post differentiation. However, this was not carried over to protein expression where Pax7 and MyoD were seen to be expressed to a greater extent in HC cultures. mRNA expression markers of protein degradation were noted to be elevated in NDD-CKD cultures in comparison to HC cultures. In light of our findings, future work should seek to investigate the role of the CKD environment as well as mechanisms implicated in transcription regulation to further advance the current model development as well as the mechanistic understanding of skeletal muscle wasting in CKD.

cell biology↗

bioRxiv2020

Identification of antibiotics for use in selection of the chytrid fungi Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans

ABSTRACTGlobal amphibian populations are being decimated by chytridiomycosis, a deadly skin infection caused by the fungal pathogens Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal). Although ongoing efforts are attempting to limit the spread of these infections, targeted treatments are necessary to manage the disease. Currently, no tools for genetic manipulation are available to identify and test specific drug targets in these fungi. To facilitate the development of genetic tools in Bd and Bsal, we have tested five commonly used antibiotics with available resistance genes: Hygromycin, Blasticidin, Puromycin, Zeocin, and Neomycin. We have identified effective concentrations of each for selection in both liquid culture and on solid media. These concentrations are within the range of concentrations used for selecting genetically modified cells from a variety of other eukaryotic species.Competing Interest StatementThe authors have declared no competing interest.View Full Text

cell biology↗

bioRxiv2020

The actin networks of chytrid fungi reveal evolutionary loss of cytoskeletal complexity in the fungal kingdom

Cells from across the eukaryotic tree use actin polymers and a number of conserved regulators for a wide variety of functions including endocytosis, cytokinesis, and cell migration. Despite this conservation, the actin cytoskeleton has undergone significant evolution and diversification, highlighted by the differences in the actin cytoskeletal networks of mammalian cells and yeast. Chytrid fungi diverged before the emergence of the Dikarya (multicellular fungi and yeast), and therefore provide a unique opportunity to study the evolution of the actin cytoskeleton. Chytrids have two life stages: zoospore cells that can swim with a flagellum, and sessile sporangial cells that, like multicellular fungi, are encased in a chitinous cell wall. Here we show that zoospores of the amphibian-killing chytrid Batrachochytrium dendrobatidis (Bd) build dynamic actin structures that resemble those of animal cells, including pseudopods, an actin cortex, and filopodia-like actin spikes. In contrast, Bd sporangia assemble actin patches similar to those of yeast, as well as perinuclear actin shells. Our identification of actin cytoskeletal elements in the genomes of five species of chytrid fungi indicate that these actin structures are controlled by both fungal-specific components as well as actin regulators and myosin motors found in animals but not other fungal lineages. The use of specific small molecule inhibitors indicate that nearly all of Bds actin structures are dynamic and use distinct nucleators: while pseudopods and actin patches are Arp2/3-dependent, the actin cortex appears formin-dependent, and actin spikes require both nucleators. The presence of animal- and yeast-like actin cytoskeletal components in the genome combined with the intermediate actin phenotypes in Bd suggests that the simplicity of the yeast cytoskeleton may be due to evolutionary loss.

cell biology↗

bioRxiv2019

Isolation and maintenance of Batrachochytrium salamandrivorans cultures

Discovered in 2013, Batrachochytrium salamandrivorans (Bsal) is an emerging amphibian pathogen that causes ulcerative skin lesions and multifocal erosion. A closely related pathogen, Batrachochytrium dendrobatidis (Bd), has devastated amphibian populations worldwide, suggesting that Bsal poses a significant threat to global salamander biodiversity. To expedite research into this emerging threat, we seek to standardize protocols across the field so that results of laboratory studies are reproducible and comparable. We have collated data and experience from multiple labs to standardize culturing practices of Bsal. Here we outline common culture practices including a media for optimal Bsal growth, standard culture protocols, and a method for isolating Bsal from infected tissue.

microbiology↗

bioRxiv2019

Genetic transformation and live-cell nuclear and actin dynamics during the life cycle of a chytrid

Chytrids are early-diverging fungi that share ancestral features of animals, including cells that crawl and swim. At later stages, chytrid cells resemble fungi with a chitin-based cell wall and hyphal-like structures known as rhizoids. Chytrids are important evolutionary transitional forms, but much remains unknown about their cell biology because we lack genetic tools for the live-cell imaging of their nuclear and cytoskeletal dynamics. Here, we generated stable transgenic lines of the soil chytrid Spizellomyces punctatus, and coupled live-cell microscopy and fluorescent tagging to measure the timing and coordination of growth, the cell cycle, and the actin cytoskeleton. We show that Spizellomyces zoospores rapidly encyst, develop rhizoids, and undergo multiple rounds of synchronous nuclear division in a sporangium, followed by cellularization, to create and release hundreds of zoospores. The life cycle is complete in less than 30 hours. We further demonstrate that crawling zoospores, akin to animal cells, display polymerized actin at the leading edge of amoeboid fronts. After encystment, polymerized actin reorganizes into fungal-like cortical patches and cables that extend into the rhizoid. Actin remains highly dynamic during sporo-genesis with the formation of actin perinuclear shells each cell cycle and the emergence of polygonal territories during cellularization. Spizellomyces is a fast-growing and genetically-tractable organism that should be useful for comparative cell biology and understanding the evolution of fungi and early eukaryotes.

cell biology↗