Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
402
result(s) for
"Morrison, Jessica"
Sort by:
Spatiotemporal analysis of microbial community dynamics during seasonal stratification events in a freshwater lake (Grand Lake, OK, USA)
Many freshwater lakes undergo seasonal stratification, where the formation of phototrophic blooms in the epilimnion and subsequent sedimentation induces hypoxia/anoxia in the thermocline and hypolimnion. This autochthonously produced biomass represents a major seasonal organic input that impacts the entire ecosystem. While the limnological aspects of this process are fairly well documented, relatively little is known regarding the microbial community response to such events, especially in the deeper anoxic layers of the water column. Here, we conducted a spatiotemporal survey of the particle-associated and free-living microbial communities in a warm monomictic freshwater reservoir (Grand Lake O' the Cherokees) in northeastern Oklahoma, USA. Pre-stratification samples (March) harbored a homogeneous community throughout the oxygenated water column dominated by typical oligotrophic aquatic lineages (acl clade within Actinobacteria, and Flavobacterium within the Bacteroidetes). The onset of phototrophic blooming in June induced the progression of this baseline community into two distinct trajectories. Within the oxic epilimnion, samples were characterized by the propagation of phototrophic (Prochlorococcus), and heterotrophic (Planctomycetes, Verrucomicrobia, and Beta-Proteobacteria) lineages. Within the oxygen-deficient thermocline and hypolimnion, the sedimentation of surface biomass induced the development of a highly diverse community, with the enrichment of Chloroflexi, \"Latescibacteria\", Armatimonadetes, and Delta-Proteobacteria in the particle-associated fraction, and Gemmatimonadetes and \"Omnitrophica\" in the free-living fraction. Our work documents the development of multiple spatially and temporally distinct niches during lake stratification, and supports the enrichment of multiple yet-uncultured and poorly characterized lineages in the lake's deeper oxygen-deficient layers, an ecologically relevant microbial niche that is often overlooked in lakes diversity surveys.
Journal Article
Defined enzyme cocktail from the anaerobic fungus Orpinomyces sp. strain C1A effectively releases sugars from pretreated corn stover and switchgrass
The anaerobic fungus
Orpinomyces
strain C1A is capable of growth on various types of lignocellulosic substrates, and harbors an impressive reservoir of carbohydrate active enzymes (CAZymes). Using a minimum enzyme cocktail strategy, we constituted a four-component lignocellulolytic cocktail derived from highly transcribed C1A, and evaluated its efficacy against pretreated corn stover and switchgrass. Hydrolysis yields ranged between 65–77.4%, depending on the lignocellulosic substrate and pretreatment applied. Addition of a highly expressed anaerobic fungal swollenin improved hydrolysis yields by up to 7%. Compared to the commercial cocktail CTec2, these anaerobic fungal cocktails provided comparable or slightly lower hydrolysis yields. Further, the differences in efficacy between commercial and anaerobic cocktails were often only realized after extended (168 hr) incubations. Under certain conditions, the hydrolysis yields of the anaerobic fungal cocktail was slightly superior to that realized by CTec2. We attribute the observed high hydrolysis yields to the high specific activity and affinity of the individual enzymes of the cocktail, as well as the high level of synergy and multi-functionality observed in multiple components. Collectively, this effort provides a novel platform for constructing highly effective enzymes for biofuel production and represents the first lignocellulolytic enzyme cocktail created from anaerobic fungal enzymes.
Journal Article
A multifunctional GH39 glycoside hydrolase from the anaerobic gut fungus Orpinomyces sp. strain C1A
Background. The anaerobic gut fungi (phylum Neocallimastigomycota) represent a promising source of novel lignocellulolytic enzymes. Here, we report on the cloning, expression, and characterization of a glycoside hydrolase family 39 (GH39) enzyme (Bgxg1) that is highly transcribed by the anaerobic fungus Orpinomyces sp. strain C1A under different growth conditions. This represents the first study of a GH39-family enzyme from the anaerobic fungi. Methods. Using enzyme activity assays, we performed a biochemical characterization of Bgxg1 on a variety of substrates over a wide range of pH and temperature values to identify the optimal enzyme conditions and the specificity of the enzyme. In addition, substrate competition studies and comparative modeling efforts were completed. Results. Contrary to the narrow range of activities (β-xylosidase or α-L-iduronidase) observed in previously characterized GH39 enzymes, Bgxg1 is unique in that it is multifunctional, exhibiting strong β-xylosidase, β-glucosidase, β-galactosidase activities (11.5 ± 1.2, 73.4 ± 7.15, and 54.6 ± 2.26 U/mg, respectively) and a weak xylanase activity (10.8 ± 1.25 U/mg), as compared to previously characterized enzymes. Further, Bgxg1 possesses extremely high affinity (as evident by the lowest K m values), compared to all previously characterized β-glucosidases, β-galactosidases, and xylanases. Physiological characterization revealed that Bgxg1 is active over a wide range of pH (3–8, optimum 6) and temperatures (25–60 °C, optimum 39 °C), and possesses excellent temperature and thermal stability. Substrate competition assays suggest that all observed activities occur at a single active site. Using comparative modeling and bioinformatics approaches, we putatively identified ten amino acid differences between Bgxg1 and previously biochemically characterized GH39 β-xylosidases that we speculate could impact active site architecture, size, charge, and/or polarity. Discussion. Collectively, the unique capabilities and multi-functionality of Bgxg1 render it an excellent candidate for inclusion in enzyme cocktails mediating cellulose and hemicellulose saccharification from lignocellulosic biomass.
Journal Article
Repurposing of ivacaftor shows potential to treat ROR1 expressing high-grade serous ovarian cancer
Drug repurposing has emerged as an effective strategy to accelerate drug discovery. Using the pipeline established from a large collaborative drug repurposing project focused on high-grade serous ovarian cancer (HGSOC), we identified ivacaftor, an FDA-approved cystic fibrosis medication, as a drug candidate predicted to interact with the receptor tyrosine kinase-like orphan receptor 1 (ROR1) which we have previously demonstrated as a therapeutic target in ovarian cancer.
This study aimed to provide preclinical evidence supporting the potential repurposing of ivacaftor for HGSOC treatment.
Ivacaftor was tested in 2D and 3D preclinical models as well as patient-derived organoid models in vitro.
Dose-response analysis was undertaken in ROR1 expressing HGSOC cell lines OVCAR4, KURAMOCHI, COV362 and COV318 in both 2D adherent and 3D bioprinted formats. Real-time live/dead and apoptosis cell staining were performed over a 72 h period using the IncuCyte live cell imaging platform. Flow cytometry was used to assess apoptosis, DNA damage and cell proliferation following treatment with either 15 µM ivacaftor or 30 µM carboplatin at 24, 48 and 72 h. Additionally, ROR1-expressing HGSOC patient-derived organoids (OC029, OC043 and OC058) underwent ivacaftor dose-response analysis. Cell apoptosis following 15 µM ivacaftor treatment was measured in real-time using an Annexin V assay in two additional organoid models (OC062 and OC075). Finally, the mechanisms associated with response to ivacaftor were explored in HGSOC cell lines through Western blotting.
The IC50 for ivacaftor ranged from 6.5 to 13.2 µM in 2D cultures and 11.6 to 18.2 µM in 3D cultures. Treatment with 10 and 15 µM ivacaftor resulted in significantly increased cell death and reduced live cell counts compared to the vehicle control over 72 h. Organoids displayed IC50 values between 11.2 and 14.1 µM. Ivacaftor treatment induced apoptosis in organoids, with no significant impact on DNA damage or cell cycle in HGSOC cells. ROR1 signalling associated oncogenic pathways including the BMI-1 and the PI3K/AKT pathways were modulated following ivacaftor treatment.
In summary, ivacaftor demonstrated significant anti-tumour potential in preclinical HGSOC models, supporting its further investigation as a repurposed therapy for ovarian cancer.
Journal Article
Microbial communities mediating algal detritus turnover under anaerobic conditions
Algae encompass a wide array of photosynthetic organisms that are ubiquitously distributed in aquatic and terrestrial habitats. Algal species often bloom in aquatic ecosystems, providing a significant autochthonous carbon input to the deeper anoxic layers in stratified water bodies. In addition, various algal species have been touted as promising candidates for anaerobic biogas production from biomass. Surprisingly, in spite of its ecological and economic relevance, the microbial community involved in algal detritus turnover under anaerobic conditions remains largely unexplored.
Here, we characterized the microbial communities mediating the degradation of
(Chlorophyta),
sp. strain IWP1 (Charophyceae), and kelp
(phylum Phaeophyceae), using sediments from an anaerobic spring (Zodlteone spring, OK; ZDT), sludge from a secondary digester in a local wastewater treatment plant (Stillwater, OK; WWT), and deeper anoxic layers from a seasonally stratified lake (Grand Lake O' the Cherokees, OK; GL) as inoculum sources. Within all enrichments, the majority of algal biomass was metabolized within 13-16 weeks, and the process was accompanied by an increase in cell numbers and a decrease in community diversity. Community surveys based on the V4 region of the 16S rRNA gene identified different lineages belonging to the phyla Bacteroidetes, Proteobacteria (alpha, delta, gamma, and epsilon classes), Spirochaetes, and Firmicutes that were selectively abundant under various substrate and inoculum conditions. Within all kelp enrichments, the microbial communities structures at the conclusion of the experiment were highly similar regardless of the enrichment source, and were dominated by the genus
, or family
within the Firmicutes. In all other enrichments the final microbial community was dependent on the inoculum source, rather than the type of algae utilized as substrate. Lineages enriched included the uncultured groups VadinBC27 and WCHB1-69 within the Bacteroidetes, genus
and the uncultured group SHA-4 within Spirochaetes,
,
,
,
, and
within the Firmicutes, and genera
,
,
and
and
within the Gamma-Proteobaceteria order Enterobacteriales.
Our results represent the first systematic survey of microbial communities mediating turnover of algal biomass under anaerobic conditions, and highlights the diversity of lineages putatively involved in the degradation process.
Journal Article
Incoming NSF director faces challenges in Congress
By all accounts, astrophysicist France Cardova thrives in the face of a challenge. As NASA's chief scientist in the mid-1990s, she helped then-administrator Daniel Goldin to push his 'faster, better, cheaper' vision for space research. Later, as chancellor of the University of California, Riverside, she won approval for a long-sought medical school. And during her 2007-12 tenure as president of Purdue University, she helped to double research funding despite a global recession.
Journal Article