Publications by authors named "Frank Gleason"

37 Publications

Commentary: In with the new: three-dimensional surface imaging for pectus excavatum.

Semin Thorac Cardiovasc Surg 2021 Sep 1. Epub 2021 Sep 1.

Department of Surgery, General Surgery Residency Program, University of Alabama at Birmingham, Birmingham, AL, 35233.

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http://dx.doi.org/10.1053/j.semtcvs.2021.08.025DOI Listing
September 2021

Relationship between burnout and mistreatment: Who plays a role?

Am J Surg 2021 Jul 22. Epub 2021 Jul 22.

Department of Surgery, University of Alabama Birmingham, Birmingham, AL, USA.

Introduction: Surgery residents have high burnout rates and mistreatment occurs during training. We hypothesized that residents who reported mistreatment would be more likely to experience burnout.

Methods: A multi-institutional observational study asked residents to complete the Maslach Burnout Inventory and to rate how often they experienced mistreatment. Scores in the high-risk range for emotional exhaustion or depersonalization were classified as burnout. Associations between mistreatment behaviors, program, sex, post graduate year(PGY), and clinical status were measured by Spearman's correlation, linear regression, and logistic regression.

Results: We invited 398 residents to participate; 180 responded(45%). 52%(n = 93) were female, there was an even distribution among PGY, and seven programs were represented. Almost half of the cohort (48%) reported high risk for burnout and 68% reported experiencing mistreatment. Mistreatment by senior physician team members were correlated with EE(rho = 0.184,p = 0.016) and DP(rho = 0.181,p = 0.016).

Conclusion: While overall burnout was not significantly associated with mistreatment behaviors, both burnout and mistreatment were commonly reported.
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http://dx.doi.org/10.1016/j.amjsurg.2021.06.009DOI Listing
July 2021

Patient, Nurse, Medical Assistant, and Surgeon Perspectives Inform the Development of a Decision Support Tool for Inguinal Hernia Surgery: A Qualitative Analysis.

Am J Surg 2021 08 13;222(2):272-280. Epub 2021 Jan 13.

Division of Gastrointestinal Surgery, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA. Electronic address:

Background: Critical perspectives on the informed consent process for inguinal hernia surgery are lacking.

Methods: We conducted focus group interviews of patients who have undergone inguinal hernia surgery and nurses/medical assistants. Individual phone interviews were also conducted with surgeons sampled from the International Hernia Collaboration. Interviews were transcribed for coding and qualitative thematic analysis performed using NVivo 12 Plus. Themes were compiled to develop a decision aid.

Results: Sixteen patients, 6 support staff members, and 12 surgeons participated. Multiple themes were identified. Patients, nurses, and medical assistants identified barriers to asking questions in the current clinic setup, patient stress, and time constraints, while surgeons identified strategies to implement decision aids. All participants agreed that decision aids improve the informed consent process.

Conclusion: Key stakeholders identified barriers to the informed consent process and provided input on necessary components of a decision aid. Opportunities exist to address these barriers and improve the consent process.
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http://dx.doi.org/10.1016/j.amjsurg.2021.01.009DOI Listing
August 2021

First Genome of Labyrinthula sp., an Opportunistic Seagrass Pathogen, Reveals Novel Insight into Marine Protist Phylogeny, Ecology and CAZyme Cell-Wall Degradation.

Microb Ecol 2021 Aug 7;82(2):498-511. Epub 2021 Jan 7.

Centre of Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong, Victoria, Australia.

Labyrinthula spp. are saprobic, marine protists that also act as opportunistic pathogens and are the causative agents of seagrass wasting disease (SWD). Despite the threat of local- and large-scale SWD outbreaks, there are currently gaps in our understanding of the drivers of SWD, particularly surrounding Labyrinthula spp. virulence and ecology. Given these uncertainties, we investigated the Labyrinthula genus from a novel genomic perspective by presenting the first draft genome and predicted proteome of a pathogenic isolate Labyrinthula SR_Ha_C, generated from a hybrid assembly of Nanopore and Illumina sequences. Phylogenetic and cross-phyla comparisons revealed insights into the evolutionary history of Stramenopiles. Genome annotation showed evidence of glideosome-type machinery and an apicoplast protein typically found in protist pathogens and parasites. Proteins involved in Labyrinthula SR_Ha_C's actin-myosin mode of transport, as well as carbohydrate degradation were also prevalent. Further, CAZyme functional predictions revealed a repertoire of enzymes involved in breakdown of cell-wall and carbohydrate storage compounds common to seagrasses. The relatively low number of CAZymes annotated from the genome of Labyrinthula SR_Ha_C compared to other Labyrinthulea species may reflect the conservative annotation parameters, a specialized substrate affinity and the scarcity of characterized protist enzymes. Inherently, there is high probability for finding both unique and novel enzymes from Labyrinthula spp. This study provides resources for further exploration of Labyrinthula spp. ecology and evolution, and will hopefully be the catalyst for new hypothesis-driven SWD research revealing more details of molecular interactions between the Labyrinthula genus and its host substrate.
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http://dx.doi.org/10.1007/s00248-020-01647-xDOI Listing
August 2021

Early Elective Surgery After Colon Cancer Diagnosis has Higher Risk of Readmission and Death.

Ann Surg 2021 02;273(2):188-194

Division of Hematology and Oncology, University of Alabama at Birmingham, Birmingham, Alabama.

Objective: We hypothesized colon resection within 30 days of diagnosis of cancer would have higher rates of readmission and cancer specific mortality, unless there was demonstrated evidence of preoperative workup.

Summary Background Data: Few studies have examined if negative consequences exist with expedited elective surgery after diagnosis of colon cancer. Surgery in a shorter time frame may result in a lack of appropriate preoperative care.

Methods: Retrospective analysis of 25,407 patients in the Surveillance Epidemiology and End Results registry who underwent elective surgical resection for colon cancer from 2010 to 2015. Cohort stratified by age (66-75 vs >75 years). Primary outcomes of interest were 30-day readmission and 5-year colon cancer specific mortality. Relationships between timing of surgery and outcomes were assessed.

Results: On unadjusted analysis, surgery before 20 days of diagnosis was associated with higher risk of 30-day readmission and colon cancer specific mortality in both age groups. Among those age 66 to 75 years old, adjusting for patient factors and preoperative workup eliminated the risk of 30-day readmission (risk ratio 1.5-0.9 for 0-10 days, risk ratio 1.3-0.9 for 11-20 days). However, the risk for colon cancer specific mortality, although reduced, persisted (hazard ratio 2.2-1.3 for 0-10 days, hazard ratio 2.0-1.2 for 11-20 days). In the cohort older than 75 years, adjusting for patient level factors and preoperative workup eliminated risk of surgery 20 days postop or sooner.

Conclusions: The risk associated with short time to surgery (within 30 days) may be mitigated if full oncologic workups are provided.
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http://dx.doi.org/10.1097/SLA.0000000000004431DOI Listing
February 2021

Do Internal or External Characteristics More Reliably Predict Burnout in Resident Physicians: A Multi-institutional Study.

J Surg Educ 2020 Nov - Dec;77(6):e86-e93. Epub 2020 Oct 17.

Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama. Electronic address:

Introduction: Surgical residents have been shown to experience high rates of burnout. Whether this is influenced predominately by intrinsic characteristics, external factors, or is multifactorial has not been well studied. The aim of this study was to explore the relationship between these elements and burnout. We hypothesized that residents with higher emotional intelligence scores, greater resilience and mindfulness, and better work environments would experience lower rates of burnout.

Methods: General surgery residents at 7 sites in the US were invited to complete an electronic survey in 2019 that included the 2-item Maslach Burnout Inventory, Brief Emotional Intelligence Scale, Revised Cognitive and Affective Mindfulness Scale, 2-Item Connor-Davidson Resilience Scale, Utrecht Work Engagement Scale, and Job Resources scale of the Job Demands-Resources Questionnaire. Individual constructs were assessed for association with burnout, using multivariable logistic regression models. Residents' scores were evaluated in aggregate, in groups according to demographic characteristics, and by site.

Results: Of 284 residents, 164 completed the survey (response rate 58%). A total of 71% of respondents were at high risk for burnout, with sites ranging from 57% to 85% (p = 0.49). Burnout rates demonstrated no significant difference across gender, PGY level, and respondent age. On bivariate model, no demographic variables were found to be associated with burnout, but the internal characteristics of emotional intelligence, resilience and mindfulness, and the external characteristics of work engagement and job resources were each found to be protective against burnout (p < 0.001 for all). However, multivariable models examining internal and external characteristics found that no internal characteristics were associated with burnout, while job resources (coeff. -1.0, p-value <0.001) and work engagement (coeff. -0.76, p-value 0.032) were significantly protective factors. Rates of engagement overall were high, particularly with respect to work "dedication."

Conclusions: A majority of residents at multiple institutions were at high risk for burnout during the study period. Improved work engagement and job resources were found to be more strongly associated with decreased burnout rates when compared to internal characteristics. Although surgical residents appear to already be highly engaged in their work, programs should continue to explore ways to increase job resources, and further research should be aimed at elucidating the mediating effect of internal characteristics on these external factors.
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http://dx.doi.org/10.1016/j.jsurg.2020.09.024DOI Listing
June 2021

Newly emerging diseases of marine turtles, especially sea turtle egg fusariosis (SEFT), caused by species in the complex (FSSC).

Mycology 2020 Jan 7;11(3):184-194. Epub 2020 Jan 7.

School of Life and Environmental Sciences, University of Sydney, Sydney, Australia.

Sea turtles are presently considered severely endangered species that are historically threatened by many environmental factors. Recently, additional threats to sea turtles from two pathogenic species of fungi in the species complex ( and ) have been identified. These species infect marine turtle eggs, causing sea turtle egg fusariosis, and kill their embryos, with recent reports of hatch-failure in seven globally distributed species of endangered sea turtles (, Dermochelys and ). Mycelia and spores of pathogenic species of are produced in disturbed terrestrial soils and are transported to the ocean in coastal run off. We propose that these fungi grow on floating particles of plant tissues (leaves and wood), animal tissues, silt and plastics, which are carried by wind and currents and the turtles themselves to the beaches where the turtles lay their eggs.
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http://dx.doi.org/10.1080/21501203.2019.1710303DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7534349PMC
January 2020

Emotional Intelligence and Burnout in Surgical Residents: A 5-Year Study.

J Surg Educ 2020 Nov - Dec;77(6):e63-e70. Epub 2020 Aug 18.

University of Alabama at Birmingham, Birmingham, Alabama. Electronic address:

Objective: We sought to characterize the interactions of burnout with internal and external factors over the past 5 years for surgery residents at our institution. We hypothesized that burnout levels would be consistent among years, inversely related to emotional intelligence (EI) and job resources, and directly related to disruptive behaviors.

Design: General surgery residents at a single institution were invited to complete a survey each year from 2015 to 2019 that included a combination of the 22-item Maslach-Burnout Inventory, 30-item trait EI questionnaire, as well as focused questions assessing disruptive behaviors (8 items), job resources (8 items), and demographic characteristics. Burnout was defined as scoring high in depersonalization (≥ 10 points) or emotional exhaustion (≥ 27 points). Student's t tests and Wilcoxon tests were used to compare continuous variables; chi-square and Fisher's exact tests were used to compare categorical variables, as appropriate. Spearman's rho was used to calculate correlation. A logistic regression and separate linear regression model were constructed to assess relation of variables to burnout.

Setting: The general surgery residency program at the University of Alabama at Birmingham, Birmingham, Alabama, a large tertiary care academic center.

Results: An average of 47 surveys were completed each year, for a total of 236 (response rate 81%). One hundred seventeen (58.5%) met criteria for burnout. Burnout rates each year ranged from 68% to 53%, with the lowest value occurring in 2019. Incidence of burnout was lowest among the postgraduate year (PGY) 1 class and highest among the PGY5 class (38% versus 64%, p = 0.02). Individuals without burnout had higher scores for EI overall (5.7 versus 5.3, p < 0.001) as well as in each of its 4 subcomponents (p < 0.001). Individuals who were subjected to disruptive behaviors, particularly others taking credit for work and public humiliation, were more likely to experience burnout (p = 0.02). Those with burnout also had significantly lower scores in each of the 4 domains of the Job Resources model (p < 0.01). On multivariate logistic regression, increasing PGY level remained a significant predictor of burnout risk. Each of the sub-domains of EI and jobs resources inversely corelated with burnout, while disruptive behaviors directly correlated with burnout. ON subsequent multivariable linear regression, resident well-being and professional development remained independent predictors of lower burnout scores.

Conclusions: Burnout is prevalent among trainees at our institution, but a trend toward improvement has been shown over 5 years. Burnout rates increase each year of surgical training beyond PGY2. Factors that mitigate burnout include resident well-being and professional development. Disruptive behaviors lead to increase burnout rates.
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http://dx.doi.org/10.1016/j.jsurg.2020.07.044DOI Listing
June 2021

The Job Demands-Resources Model as a Framework to Identify Factors Associated With Burnout in Surgical Residents.

J Surg Res 2020 03 27;247:121-127. Epub 2019 Nov 27.

Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama. Electronic address:

Background: Surgical residents are a population at high risk for burnout. We hypothesized that surgical residents' burnout would be inversely related to emotional intelligence (EI) and job resources and directly related to experiences of disruptive behavior.

Materials And Methods: All general surgery residents at a single institution were invited to complete a survey in 2018 that included the Maslach Burnout Inventory, Trait EI Questionnaire Short Form, focused questions assessing disruptive behaviors, job resources, and demographic characteristics. Burnout was defined as scoring high in depersonalization (≥10 points) or emotional exhaustion (≥27 points). Student's t-tests and Wilcoxon tests were used to compare continuous variables; chi-square and Fisher's exact tests were used to compare categorical variables.

Results: The survey response rate was 87%. The median respondent age was 30, 51.7% were female, and 48.3% were single. Thirty-five met criteria for burnout (58%). Residents with burnout had lower scores for job resources than residents without burnout (19 versus 26, P < 0.01). Job resources subdomain scores for meaningful feedback and professional development had an inverse association with burnout (P < 0.01 for both). Having experienced any disruptive behavior was associated with burnout (68% versus 32%, P = 0.01). Mean EI scores were also lower for those with burnout (5.18 versus 5.64, P < 0.01). Among EI subcategories, burnout was associated with lower well-being and emotionality (P < 0.01 and P = 0.02, respectively).

Conclusions: Burnout is prevalent among surgery residents, including those at our institution. Experiencing disruptive behaviors and lower perceptions of job resources were associated with higher burnout scores, along with lower scores in EI, and may inform future efforts toward interventions.
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http://dx.doi.org/10.1016/j.jss.2019.10.034DOI Listing
March 2020

Enzymes of early-diverging, zoosporic fungi.

Appl Microbiol Biotechnol 2019 Sep 15;103(17):6885-6902. Epub 2019 Jul 15.

Centre for Structural and Functional Genomics, Concordia University, Montreal, QC, H4B1R6, Canada.

The secretome, the complement of extracellular proteins, is a reflection of the interaction of an organism with its host or substrate, thus a determining factor for the organism's fitness and competitiveness. Hence, the secretome impacts speciation and organismal evolution. The zoosporic Chytridiomycota, Blastocladiomycota, Neocallimastigomycota, and Cryptomycota represent the earliest diverging lineages of the Fungal Kingdom. The review describes the enzyme compositions of these zoosporic fungi, underscoring the enzymes involved in biomass degradation. The review connects the lifestyle and substrate affinities of the zoosporic fungi to the secretome composition by examining both classical phenotypic investigations and molecular/genomic-based studies. The carbohydrate-active enzyme profiles of 19 genome-sequenced species are summarized. Emphasis is given to recent advances in understanding the functional role of rumen fungi, the basis for the devastating chytridiomycosis, and the structure of fungal cellulosome. The approach taken by the review enables comparison of the secretome enzyme composition of anaerobic versus aerobic early-diverging fungi and comparison of enzyme portfolio of specialized parasites, pathogens, and saprotrophs. Early-diverging fungi digest most major types of biopolymers: cellulose, hemicellulose, pectin, chitin, and keratin. It is thus to be expected that early-diverging fungi in its entirety represents a rich and diverse pool of secreted, metabolic enzymes. The review presents the methods used for enzyme discovery, the diversity of enzymes found, the status and outlook for recombinant production, and the potential for applications. Comparative studies on the composition of secretome enzymes of early-diverging fungi would contribute to unraveling the basal lineages of fungi.
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http://dx.doi.org/10.1007/s00253-019-09983-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6690862PMC
September 2019

Impact of initial temporary abdominal closure in damage control surgery: a retrospective analysis.

World J Emerg Surg 2018 15;13:43. Epub 2018 Sep 15.

1Division of Acute Care Surgery, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL USA.

Background: Damage control surgery has revolutionized trauma surgery. Use of damage control surgery allows for resuscitation and reversal of coagulopathy at the risk of loss of abdominal domain and intra-abdominal complications. Temporary abdominal closure is possible with multiple techniques, the choice of which may affect ability to achieve primary fascial closure and further complication.

Methods: A retrospective analysis of all trauma patients requiring damage control laparotomy upon admission to an ACS-verified level one trauma center from 2011 to 2016 was performed. Demographic and clinical data including ability and time to attain primary fascial closure, as well as complication rates, were recorded. The primary outcome measure was ability to achieve primary fascial closure during initial hospitalization.

Results: Two hundred and thirty-nine patients met criteria for inclusion. Primary skin closure (57.7%), ABThera™ VAC system (ABT) (15.1%), Bogota bag (BB) (25.1%), or a modified Barker's vacuum-packing (BVP) (2.1%) were used in the initial laparotomy. Patients receiving skin-only closure had significantly higher rates of primary fascial closure and lower hospital mortality, but also significantly lower mean lactate, base deficit, and requirement for massive transfusion. Between ABT or BB, use of ABT was associated with increased rates of fascial closure. Multivariate regression revealed primary skin closure to be significantly associated with primary fascial closure while BB was associated with failure to achieve fascial closure.

Conclusions: Primary skin closure is a viable option in the initial management of the open abdomen, although these patients demonstrated less injury burden in our study. Use of vacuum-assisted dressings continues to be the preferred method for temporary abdominal closure in damage control surgery for trauma.
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http://dx.doi.org/10.1186/s13017-018-0204-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6139137PMC
January 2019

Cryopreservation methods are effective for long-term storage of Labyrinthula cultures.

Dis Aquat Organ 2018 08;130(1):65-70

Deakin University, Geelong, School of Life and Environmental Sciences, Burwood, VIC 3125, Australia.

Marine heterotrophic protists of the Labyrinthulomycota are of interest for their biotechnological (e.g. thraustochytrid production of lipids) and ecological (e.g. wasting disease and rapid blight by pathogens of the genus Labyrinthula) applications; culture-based laboratory studies are a central technique of this research. However, maintaining such microorganism cultures can be labour- and cost-intensive, with a high risk of culture contamination and die-off over time. Deep-freeze storage, or cryopreservation, can be used to maintain culture back-ups, as well as to preserve the genetic and phenotypic properties of the microorganisms; however, this method has not been tested for the ubiquitous marine protists Labyrinthula spp. In this study, we trialled 12 cryopreservation protocols on 3 Labyrinthula sp. isolates of varying colony morphological traits. After 6 mo at -80°C storage, the DMSO and glycerol protocols were the most effective cryoprotectants compared to methanol (up to 90% success vs. 50% success, respectively). The addition of 30% horse serum to the cryoprotectant solution increased Labyrinthula sp. growth success by 20-30%. We expect that these protocols will provide extra security for culture-based studies, as well as opportunities for long-term research on key Labyrinthula sp. isolates.
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http://dx.doi.org/10.3354/dao03266DOI Listing
August 2018

The roles of endolithic fungi in bioerosion and disease in marine ecosystems. II. Potential facultatively parasitic anamorphic ascomycetes can cause disease in corals and molluscs.

Mycology 2017 31;8(3):216-227. Epub 2017 Aug 31.

School of Life and Environmental Sciences, University of Sydney, Sydney, Australia.

Anamorphic ascomycetes have been implicated as causative agents of diseases in tissues and skeletons of hard corals, in tissues of soft corals (sea fans) and in tissues and shells of molluscs. Opportunist marine fungal pathogens, such as , are important components of marine mycoplankton and are ubiquitous in the open oceans, intertidal zones and marine sediments. These fungi can cause infection in or at least can be associated with animals which live in these ecosystems. can produce toxins which inhibit photosynthesis in and the growth of coral zooxanthellae. The prevalence of many documented infections has increased in frequency and severity in recent decades with the changing impacts of physical and chemical factors, such as temperature, acidity and eutrophication. Changes in these factors are thought to cause significant loss of biodiversity in marine ecosystems on a global scale in general, and especially in coral reefs and shallow bays.
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http://dx.doi.org/10.1080/21501203.2017.1371802DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6059078PMC
August 2017

The roles of endolithic fungi in bioerosion and disease in marine ecosystems. I. General concepts.

Mycology 2017 27;8(3):205-215. Epub 2017 Jul 27.

School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia.

Endolithic true fungi and fungus-like microorganisms penetrate calcareous substrates formed by living organisms, cause significant bioerosion and are involved in diseases of many host animals in marine ecosystems. A theoretical interactive model for the ecology of reef-building corals is proposed in this review. This model includes five principle partners that exist in a dynamic equilibrium: polyps of a colonial coelenterate, endosymbiotic zooxanthellae, endolithic algae (that penetrate coral skeletons), endolithic fungi (that attack the endolithic algae, the zooxanthellae and the polyps) and prokaryotic and eukaryotic microorganisms (which live in the coral mucus). Endolithic fungi and fungus-like boring microorganisms are important components of the marine calcium carbonate cycle because they actively contribute to the biodegradation of shells of animals composed of calcium carbonate and calcareous geological substrates.
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http://dx.doi.org/10.1080/21501203.2017.1352049DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6059151PMC
July 2017

Pathogenic Labyrinthula associated with Australian seagrasses: Considerations for seagrass wasting disease in the southern hemisphere.

Microbiol Res 2018 Jan 9;206:74-81. Epub 2017 Oct 9.

School of Life and Environmental Sciences, University of Sydney, Sydney, 2006, New South Wales, Australia.

Marine disease ecology is a growing field of research, particularly for host organisms negatively impacted by a changing climate and anthropogenic activities. A decrease in health and increase in susceptibility to disease has been hypothesised as the mechanism behind wide-spread seagrass die-offs related to wasting disease in the past. However, seagrass wasting disease and the causative pathogen, Labyrinthula, have been vastly understudied in the southern hemisphere. Our aim was to build on the current knowledge of Australian Labyrinthula descriptions and phylogeny, while also providing a first look at wasting disease ecology in Australia. Five seagrass species along a 750km stretch of coastline in southeastern Australia were sampled. The resulting 38 Labyrinthula isolates represented a diversity of morphotypes and five haplotypes of varying phylogenetic clade positions and virulence. The haplotypes clustered with previously-described phylogenetic clades containing isolates from Asia, USA and Europe. Pathogenicity tests confirmed, for the first time, the presence of at least two pathogenic haplotypes in Australia. While historically there have been no reports of wasting disease-related seagrass habitat loss, the presence of pathogenic Labyrinthula highlights the need for disease monitoring and research to understand seagrass wasting disease ecology in Australia.
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http://dx.doi.org/10.1016/j.micres.2017.10.003DOI Listing
January 2018

Key Ecological Roles for Zoosporic True Fungi in Aquatic Habitats.

Microbiol Spectr 2017 03;5(2)

School of Science, Faculty of Health Sciences, Australian Catholic University, NSW 2059, Australia.

The diversity and abundance of zoosporic true fungi have been analyzed recently using fungal sequence libraries and advances in molecular methods, such as high-throughput sequencing. This review focuses on four evolutionary primitive true fungal phyla: the Aphelidea, Chytridiomycota, Neocallimastigomycota, and Rosellida (Cryptomycota), most species of which are not polycentric or mycelial (filamentous), rather they tend to be primarily monocentric (unicellular). Zoosporic fungi appear to be both abundant and diverse in many aquatic habitats around the world, with abundance often exceeding other fungal phyla in these habitats, and numerous novel genetic sequences identified. Zoosporic fungi are able to survive extreme conditions, such as high and extremely low pH; however, more work remains to be done. They appear to have important ecological roles as saprobes in decomposition of particulate organic substrates, pollen, plant litter, and dead animals; as parasites of zooplankton and algae; as parasites of vertebrate animals (such as frogs); and as symbionts in the digestive tracts of mammals. Some chytrids cause economically important diseases of plants and animals. They regulate sizes of phytoplankton populations. Further metagenomics surveys of aquatic ecosystems are expected to enlarge our knowledge of the diversity of true zoosporic fungi. Coupled with studies on their functional ecology, we are moving closer to unraveling the role of zoosporic fungi in carbon cycling and the impact of climate change on zoosporic fungal populations.
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http://dx.doi.org/10.1128/microbiolspec.FUNK-0038-2016DOI Listing
March 2017

Zoosporic parasites infecting marine diatoms - A black box that needs to be opened.

Fungal Ecol 2016 Feb;19:59-76

School of Biological Sciences FO7, University of Sydney, Sydney, NSW 2006, Australia.

Living organisms in aquatic ecosystems are almost constantly confronted by pathogens. Nevertheless, very little is known about diseases of marine diatoms, the main primary producers of the oceans. Only a few examples of marine diatoms infected by zoosporic parasites are published, yet these studies suggest that diseases may have significant impacts on the ecology of individual diatom hosts and the composition of communities at both the producer and consumer trophic levels of food webs. Here we summarize available ecological and morphological data on chytrids, aphelids, stramenopiles (including oomycetes, labyrinthuloids, and hyphochytrids), parasitic dinoflagellates, cercozoans and phytomyxids, all of which are known zoosporic parasites of marine diatoms. Difficulties in identification of host and pathogen species and possible effects of environmental parameters on the prevalence of zoosporic parasites are discussed. Based on published data, we conclude that zoosporic parasites are much more abundant in marine ecosystems than the available literature reports, and that, at present, both the diversity and the prevalence of such pathogens are underestimated.
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http://dx.doi.org/10.1016/j.funeco.2015.09.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5221735PMC
February 2016

The First Isolation and Characterisation of the Protist Labyrinthula sp. in Southeastern Australia.

J Eukaryot Microbiol 2017 07 20;64(4):504-513. Epub 2017 Feb 20.

School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia.

As a result of anthropogenic influences and global climate change, emerging infectious marine diseases are thought to be increasingly more common and more severe than in the past. The aim of our investigation was to confirm the presence of Labyrinthula, the aetiological agent of the seagrass wasting disease, in Southeastern Australia and provide the first isolation and characterisation of this protist, in Australia. Colonies and individual cells were positively identified as Labyrinthula using published descriptions, diagrams, and photographs. Their identity was then confirmed using DNA barcoding of a region of the 18S rRNA gene. Species level identification of isolates was not possible as the taxonomy of the Labyrinthula is still poorly resolved. Still, a diversity of Labyrinthula was isolated from small sections of the southeast coast of Australia. The isolates were grouped into three haplotypes that are biogeographically restricted. These haplotypes are closely related to previously identified saprotrophic clades. The study highlights the need for further investigation into the global distribution of Labyrinthula, including phylogenetic pathogenicity and analysis of host-parasite interactions in response to stressors. Given the results of our analyses, it is prudent to continue research into disease and epidemic agents to better prepare researchers for potential future outbreaks.
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http://dx.doi.org/10.1111/jeu.12387DOI Listing
July 2017

Copper (II) lead (II), and zinc (II) reduce growth and zoospore release in four zoosporic true fungi from soils of NSW, Australia.

Fungal Biol 2015 Jul 15;119(7):648-55. Epub 2015 Apr 15.

School of Biological Sciences, Macleay Building A12, University of Sydney, New South Wales 2006, Australia.

This study examined the responses of a group of four zoosporic true fungi isolated from soils in NSW Australia, to concentrations of toxic metals in the laboratory that may be found in polluted soils. All isolates showed greatest sensitivity to Cu and least sensitivity to Pb. All isolates showed significant reduction in growth at 60 ppm (0.94 mmol m(-3)) for Cu, while three declined significantly at 60 ppm (0.92 mmol m(-3)) Zn. The growth of two isolates declined significantly at 100 ppm (0.48 mmol m(-3)) Pb and one at 200 ppm (0.96 mmol m(-3)) Pb. The rate of production of zoospores for all isolates was reduced when sporangia were grown in solid PYG media with 60 ppm Cu. Three isolates significantly declined in production at 60 ppm Zn and three at 100 ppm Pb. All isolates recovered growth after incubation in solid media with 60 ppm Zn or 100 ppm Pb. Two isolates did not recover growth after incubation in 60 ppm Cu. If these metals cause similar effects in the field, Cu, Pb, and Zn contamination of NSW soils is likely to reduce biomass of zoosporic true fungi. Loss of the fungi may reduce the rate of mineralisation of soil organic matter.
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http://dx.doi.org/10.1016/j.funbio.2015.04.002DOI Listing
July 2015

Microbial players involved in the decline of filamentous and colonial cyanobacterial blooms with a focus on fungal parasitism.

Environ Microbiol 2015 Aug 11;17(8):2573-87. Epub 2015 Jun 11.

LMGE, Laboratoire Microorganismes: Génome et Environnement, UMR CNRS 6023, Clermont Université, Université Blaise Pascal, BP 80026, Aubière CEDEX, 63171, France.

In the forthcoming decades, it is widely believed that the dominance of colonial and filamentous bloom-forming cyanobacteria (e.g. Microcystis, Planktothrix, Anabaena and Cylindrospermopsis) will increase in freshwater systems as a combined result of anthropogenic nutrient input into freshwater bodies and climate change. While the physicochemical parameters controlling bloom dynamics are well known, the role of biotic factors remains comparatively poorly studied. Morphology and toxicity often - but not always - limit the availability of cyanobacteria to filter feeding zooplankton (e.g. cladocerans). Filamentous and colonial cyanobacteria are widely regarded as trophic dead-ends mostly inedible for zooplankton, but substantial evidence shows that some grazers (e.g. copepods) can bypass this size constraint by breaking down filaments, making the bloom biomass available to other zooplankton species. A wide range of algicidal bacteria (mostly from the Alcaligenes, Flavobacterium/Cytophaga group and Pseudomonas) and viruses (Podoviridae, Siphoviridae and Myoviridae) may also contribute to bloom control, via their lytic activity underpinned by a diverse array of mechanisms. Fungal parasitism by the Chytridiomycota remains the least studied. While each of these biotic factors has traditionally been studied in isolation, emerging research consistently point to complex interwoven interactions between biotic and environmental factors.
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http://dx.doi.org/10.1111/1462-2920.12860DOI Listing
August 2015

Ecological functions of zoosporic hyperparasites.

Front Microbiol 2014 28;5:244. Epub 2014 May 28.

Institute of Microbiology, Leopold Franzens University Innsbruck Innsbruck, Austria ; Microbial Diversity and Genomics, Department of Life Sciences, Natural History Museum London, UK.

Zoosporic parasites have received increased attention during the last years, but it is still largely unnoted that these parasites can themselves be infected by hyperparasites. Some members of the Chytridiomycota, Blastocladiomycota, Cryptomycota, Hyphochytriomycota, Labyrinthulomycota, Oomycota, and Phytomyxea are hyperparasites of zoosporic hosts. Because of sometimes complex tripartite interactions between hyperparasite, their parasite-host, and the primary host, hyperparasites can be difficult to detect and monitor. Some of these hyperparasites use similar mechanisms as their parasite-hosts to find and infect their target and to access food resources. The life cycle of zoosporic hyperparasites is usually shorter than the life cycle of their hosts, so hyperparasites may accelerate the turnaround times of nutrients within the ecosystem. Hyperparasites may increase the complexity of food webs and play significant roles in regulating population sizes and population dynamics of their hosts. We suggest that hyperparasites lengthen food chains but can also play a role in conducting or suppressing diseases of animals, plants, or algae. Hyperparasites can significantly impact ecosystems in various ways, therefore it is important to increase our understanding about these cryptic and diverse organisms.
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http://dx.doi.org/10.3389/fmicb.2014.00244DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4035849PMC
June 2014

Morphology, phylogeny, and ecology of the aphelids (Aphelidea, Opisthokonta) and proposal for the new superphylum Opisthosporidia.

Front Microbiol 2014 28;5:112. Epub 2014 Mar 28.

School of Biological Sciences F07, University of Sydney Sydney, NSW, Australia.

The aphelids are a small group of intracellular parasitoids of common species of eukaryotic phytoplankton with three known genera Aphelidium, Amoeboaphelidium, and Pseudaphelidium, and 10 valid species, which form along with related environmental sequences a very diversified group. The phyla Microsporidia and Cryptomycota, and the class Aphelidea have recently been considered to be a deep branch of the Holomycota lineage forming the so called the ARM-clade which is sister to the fungi. In this review we reorganize the taxonomy of ARM-clade, and establish a new superphylum the Opisthosporidia with three phyla: Aphelida phyl. nov., Cryptomycota and Microsporidia. We discuss here all aspects of aphelid investigations: history of our knowledge, life cycle peculiarities, the morphology (including the ultrastructure), molecular phylogeny, ecology, and provide a taxonomic revision of the phylum supplied with a list of species. We compare the aphelids with their nearest relatives, the species of Rozella, and improve the diagnosis of the phylum Cryptomycota.
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http://dx.doi.org/10.3389/fmicb.2014.00112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3975115PMC
June 2014

Current ecological understanding of fungal-like pathogens of fish: what lies beneath?

Front Microbiol 2014 19;5:62. Epub 2014 Feb 19.

Centre for Conservation Ecology and Environmental Sciences, School of Applied Sciences, Bournemouth University Poole, Dorset, UK.

Despite increasingly sophisticated microbiological techniques, and long after the first discovery of microbes, basic knowledge is still lacking to fully appreciate the ecological importance of microbial parasites in fish. This is likely due to the nature of their habitats as many species of fish suffer from living beneath turbid water away from easy recording. However, fishes represent key ecosystem services for millions of people around the world and the absence of a functional ecological understanding of viruses, prokaryotes, and small eukaryotes in the maintenance of fish populations and of their diversity represents an inherent barrier to aquatic conservation and food security. Among recent emerging infectious diseases responsible for severe population declines in plant and animal taxa, fungal and fungal-like microbes have emerged as significant contributors. Here, we review the current knowledge gaps of fungal and fungal-like parasites and pathogens in fish and put them into an ecological perspective with direct implications for the monitoring of fungal fish pathogens in the wild, their phylogeography as well as their associated ecological impact on fish populations. With increasing fish movement around the world for farming, releases into the wild for sport fishing and human-driven habitat changes, it is expected, along with improved environmental monitoring of fungal and fungal-like infections, that the full extent of the impact of these pathogens on wild fish populations will soon emerge as a major threat to freshwater biodiversity.
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http://dx.doi.org/10.3389/fmicb.2014.00062DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3928546PMC
June 2014

Three dimensional quantification of biological samples using micro-computer aided tomography (microCT).

J Microbiol Methods 2013 Jan 22;92(1):33-41. Epub 2012 Oct 22.

School of Biological Sciences, University of Sydney, Sydney, NSW 2006, Australia.

MicroCT is increasingly being used to observe soft animal and plant tissues. Conventional electron and light microscope staining protocols used to enhance the contrast of soft tissues have the potential to be adapted for use in microCT. This would increase the versatility of the microCT beyond improving qualitative observations to facilitating quantitative analysis of soft tissues. This paper describes the development of a culture system and staining protocol which has successfully been used to obtain three dimensional (3-D) quantitative data of filamentous and zoosporic soil fungi. The fungi were grown in an artificial matrix that was developed to simulate the particulate nature of soil. The combination of high contrast staining protocol and use of an X-ray translucent matrix allowed for 3-D qualitative and quantitative analysis of fungal growth. A salient point raised by this study is that the effectiveness of a protocol is reliant on the tissue or cell culture system which includes the composition of the sample, the sampling vessel, the depth of a sample and the combination of stains used. The potential use of this method extends to other fields where distribution and growth patterns in 3-D need to be quantified.
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http://dx.doi.org/10.1016/j.mimet.2012.10.006DOI Listing
January 2013

Quantitative methods for the analysis of zoosporic fungi.

J Microbiol Methods 2012 Apr 16;89(1):22-32. Epub 2012 Feb 16.

Instituto de Botánica Spegazzini, calle 53 N 477, La Plata, 1900, Buenos Aires, Argentina.

Quantitative estimations of zoosporic fungi in the environment have historically received little attention, primarily due to methodological challenges and their complex life cycles. Conventional methods for quantitative analysis of zoosporic fungi to date have mainly relied on direct observation and baiting techniques, with subsequent fungal identification in the laboratory using morphological characteristics. Although these methods are still fundamentally useful, there has been an increasing preference for quantitative microscopic methods based on staining with fluorescent dyes, as well as the use of hybridization probes. More recently however PCR based methods for profiling and quantification (semi- and absolute) have proven to be rapid and accurate diagnostic tools for assessing zoosporic fungal assemblages in environmental samples. Further application of next generation sequencing technologies will however not only advance our quantitative understanding of zoosporic fungal ecology, but also their function through the analysis of their genomes and gene expression as resources and databases expand in the future. Nevertheless, it is still necessary to complement these molecular-based approaches with cultivation-based methods in order to gain a fuller quantitative understanding of the ecological and physiological roles of zoosporic fungi.
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http://dx.doi.org/10.1016/j.mimet.2012.02.003DOI Listing
April 2012

Ecological roles of the parasitic phytomyxids (plasmodiophorids) in marine ecosystems - a review.

Mar Freshw Res 2011 Apr;62(4):365-371

Institute of Microbiology, Leopold Franzens-University Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria.

Phytomyxea (plasmodiophorids) is an enigmatic group of obligate biotrophic parasites. Most of the known 41 species are associated with terrestrial and freshwater ecosystems. However, the potential of phytomyxean species to influence marine ecosystems either directly by causing diseases of their hosts or indirectly as vectors of viruses is enormous, although still unexplored. In all, 20% of the currently described phytomyxean species are parasites of some of the key primary producers in the ocean, such as seagrasses, brown algae and diatoms; however, information on their distribution, abundance and biodiversity is either incomplete or lacking. Phytomyxean species influence fitness by altering the metabolism and/or the reproductive success of their hosts. The resulting changes can (1) have an impact on the biodiversity within host populations, and (2) influence microbial food webs because of altered availability of nutrients (e.g. changed metabolic status of host, transfer of organic matter). Also, phytomyxean species may affect their host populations indirectly by transmitting viruses. The majority of the currently known single-stranded RNA marine viruses structurally resemble the viruses transmitted by phytomyxean species to crops in agricultural environments. Here, we explore possible ecological roles of these parasites in marine habitats; however, only the inclusion of Phytomyxea in marine biodiversity studies will allow estimation of the true impact of these species on global primary production in the oceans.
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http://dx.doi.org/10.1071/MF10282DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3272469PMC
April 2011

Resource seeking strategies of zoosporic true fungi in heterogeneous soil habitats at the microscale level.

Soil Biol Biochem 2012 Feb;45(2):79-88

School of Biological Sciences, University of Sydney, Sydney, NSW 2006, Australia.

Zoosporic true fungi have frequently been identified in samples from soil and freshwater ecosystems using baiting and molecular techniques. In fact some species can be components of the dominant groups of microorganisms in particular soil habitats. Yet these microorganisms have not yet been directly observed growing in soil ecosystems. Significant physical characteristics and features of the three-dimensional structures of soils which impact microorganisms at the microscale level are discussed. A thorough knowledge of soil structures is important for studying the distribution of assemblages of these fungi and understanding their ecological roles along spatial and temporal gradients. A number of specific adaptations and resource seeking strategies possibly give these fungi advantages over other groups of microorganisms in soil ecosystems. These include chemotactic zoospores, mechanisms for adhesion to substrates, rhizoids which can penetrate substrates in small spaces, structures which are resistant to environmental extremes, rapid growth rates and simple nutritional requirements. These adaptations are discussed in the context of the characteristics of soils ecosystems. Recent advances in instrumentation have led to the development of new and more precise methods for studying microorganisms in three-dimensional space. New molecular techniques have made identification of microbes possible in environmental samples.
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http://dx.doi.org/10.1016/j.soilbio.2011.10.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3261367PMC
February 2012

Molecular phylogeny of the Blastocladiomycota (Fungi) based on nuclear ribosomal DNA.

Fungal Biol 2011 Apr-May;115(4-5):381-92. Epub 2011 Feb 13.

Duke University, Biology Department, Campus Box 90338, Durham, NC 27708, USA.

The Blastocladiomycota is a recently described phylum of ecologically diverse zoosporic fungi whose species have not been thoroughly sampled and placed within a molecular phylogeny. In this study, we investigated the phylogeny of the Blastocladiomycota based on ribosomal DNA sequences from strains identified by traditional morphological and ultrastructural characters. Our results support the monophyly of the Coelomomycetaceae and Physodermataceae but the Blastocladiaceae and Catenariaceae are paraphyletic or polyphyletic. The data support two clades within Allomyces with strains identified as Allomyces arbusculus in both clades, suggesting that species concepts in Allomyces are in need of revision. A clade of Catenaria species isolated from midge larvae group separately from other Catenaria species, suggesting that this genus may need revision. In the Physodermataceae, Urophlyctis species cluster with a clade of Physoderma species. The algal parasite Paraphysoderma sedebokerensis nom. prov. clusters sister to other taxa in the Physodermataceae. Catenomyces persicinus, which has been classified in the Catenariaceae, groups with the Chytridiomycota rather than Blastocladiomycota. The rDNA operon seems to be suitable for classification within the Blastocladiomycota and distinguishes among genera; however, this region alone is not suitable to determine the position of the Blastocladiomycota among other basal fungal phyla with statistical support. A focused effort to find and isolate, or directly amplify DNA from additional taxa will be necessary to evaluate diversity in this phylum. We provide this rDNA phylogeny as a preliminary framework to guide further taxon and gene sampling and to facilitate future ecological, morphological, and systematic studies.
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http://dx.doi.org/10.1016/j.funbio.2011.02.004DOI Listing
July 2011

The ecological potentials of Phytomyxea ("plasmodiophorids") in aquatic food webs.

Hydrobiologia 2011 Jan;659(1):23-35

Institute of Microbiology, Leopold Franzens-University Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria.

The Phytomyxea ("plasmodiophorids") including both Plasmodiophorida and Phagomyxida is a monophyletic group of Eukaryotes composed of obligate biotrophic parasites of green plants, brown algae, diatoms and stramenopiles commonly found in many freshwater, soil and marine environments. However, most research on Phytomyxea has been restricted to plant pathogenic species with agricultural importance, thereby missing the huge ecological potential of this enigmatic group of parasites. Members of the Phytomyxea can induce changes in biomass in their hosts (e.g. hypertrophies of the host tissue) under suitable environmental conditions. Upon infection they alter the metabolism of their hosts, consequently changing the metabolic status of their host. This results in an altered chemical composition of the host tissue, which impacts the diversity of species which feed on the tissues of the infected host and on the zoospores produced by the parasites. Furthermore, significant amounts of nutrients derived from the hosts, both primary producers (plants and algae) and primary consumers (litter decomposers and plant parasites [Oomycetes]), can enter the food web at different trophic levels in form of zoospores and resting spores. Large numbers of zoospores and resting spores are produced which can be eaten by secondary and tertiary consumers, such as grazing zooplankton and metazoan filter-feeders. Therefore, these microbes can act as energy-rich nutrient resources which may significantly alter the trophic relationships in fresh water, soil and marine habitats. Based on the presented data, Phytomyxea can significantly contribute to the complexity and energy transfer within food webs.
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http://dx.doi.org/10.1007/s10750-010-0508-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3040567PMC
January 2011
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