Microbiology @ Massey
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Massey University Microbiology

Massey University Microbiology | Microbiology @ Massey | Scoop.it

Studying Microbiology at Massey University

A brief summary for prospective students, assembled by local members of the New Zealand Microbiological Society
 
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Transcriptomic study on persistence and survival of Listeria monocytogenes following lethal treatment with Nisin | Journal of Global Antimicrobial Resistance

Objectives
The aim of this study was to determine the gene expression associated with the persistence of a Listeria monocytogenes stationary phase population when facing lethal nisin treatment

Methods
RNA Seq analysis was used for gene expression profiling of the persister cells in rich medium (persister TN) compared with untreated cells (non-persister).The results were confirmed using RT PCR.

Results
Functional genes associated with the persister populations were identified in multiple systems, such as heat shock related stress response, cell wall synthesis, ATP-binding cassette (ABC) transport system, phosphotransferase system (PTS system), and SOS/DNA repair.

Conclusions
This study pointed to genetic regulation of persister cells exposed to lethal nisin and provides some insight into possible mechanisms of impeding bacterial persistence.
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MICROBIAL DIAGNOSTICS: THE GERM’S PERSPECTIVE!

MICROBIAL DIAGNOSTICS: THE GERM’S PERSPECTIVE! | Microbiology @ Massey | Scoop.it
Touring Orator Presentation

Presentation Lab (Room Riddet C 2.143), Massey University

Wednesday 29th August 10 am

Stephen L. W. On Associate Professor of Food Microbiology & Associate Dean of Research, Lincoln University

The world is beset with infectious diseases that impact people, plants and animals every minute of every day, bearing an astronomical economic burden. The first step towards proper management, control and treatment of such disease is to answer the question: what is causing it? The second question is often: where is it coming from? These themes have underpinned my life as a microbiologist so far. Humankind has made enormous strides in the technical ability to identify microbes to species and strain level, yet often techniques are challenged by a failure to consider the results from “the germ’s perspective” – leading to incorrect conclusions, inappropriate management and sometimes massive economic consequences. Indeed, researchers from every area of microbiology can be impacted by such errors – as will be discussed! This presentation is an update of that given at the 2017 NZ Microbiological Society’s conference, which concluded with my proud receipt of the “Distinguished orator” award.
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Chromosome architecture constrains horizontal gene transfer in bacteria | PLoS Genetics

Chromosome architecture constrains horizontal gene transfer in bacteria | PLoS Genetics | Microbiology @ Massey | Scoop.it
Despite significant frequencies of lateral gene transfer between species, higher taxonomic groups of bacteria show ecological and phenotypic cohesion. This suggests that barriers prevent panmictic dissemination of genes via lateral gene transfer. We have proposed that most bacterial genomes have a functional architecture imposed by Architecture IMparting Sequences (AIMS). AIMS are defined as 8 base pair sequences preferentially abundant on leading strands, whose abundance and strand-bias are positively correlated with proximity to the replication terminus. We determined that inversions whose endpoints lie within a single chromosome arm, which would reverse the polarity of AIMS in the inverted region, are both shorter and less frequent near the replication terminus. This distribution is consistent with the increased selection on AIMS function in this region, thus constraining DNA rearrangement. To test the hypothesis that AIMS also constrain DNA transfer between genomes, AIMS were identified in genomes while ignoring atypical, potentially laterally-transferred genes. The strand-bias of AIMS within recently acquired genes was negatively correlated with the distance of those genes from their genome’s replication terminus. This suggests that selection for AIMS function prevents the acquisition of genes whose AIMS are not found predominantly in the permissive orientation. This constraint has led to the loss of at least 18% of genes acquired by transfer in the terminus-proximal region. We used completely sequenced genomes to produce a predictive road map of paths of expected horizontal gene transfer between species based on AIMS compatibility between donor and recipient genomes. These results support a model whereby organisms retain introgressed genes only if the benefits conferred by their encoded functions outweigh the detriments incurred by the presence of foreign DNA lacking genome-wide architectural information.
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Multi-Locus Next-Generation Sequence Typing of DNA Extracted From Pooled Colonies Detects Multiple Unrelated Candida albicans Strains in a Significant Proportion of Patient Samples | Frontiers in M...

Multi-Locus Next-Generation Sequence Typing of DNA Extracted From Pooled Colonies Detects Multiple Unrelated Candida albicans Strains in a Significant Proportion of Patient Samples | Frontiers in M... | Microbiology @ Massey | Scoop.it

The yeast Candida albicans is an important opportunistic human pathogen. For C. albicans strain typing or drug susceptibility testing, a single colony recovered from a patient sample is normally used. This is insufficient when multiple strains are present at the site sampled. How often this is the case is unclear. Previous studies, confined to oral, vaginal and vulvar samples, have yielded conflicting results and have assessed too small a number of colonies per sample to reliably detect the presence of multiple strains. We developed a next-generation sequencing (NGS) modification of the highly discriminatory C. albicans MLST (multilocus sequence typing) method, 100+1 NGS-MLST, for detection and typing of multiple strains in clinical samples. In 100+1 NGS-MLST, DNA is extracted from a pool of colonies from a patient sample and also from one of the colonies. MLST amplicons from both DNA preparations are analyzed by high-throughput sequencing. Using base call frequencies, our bespoke DALMATIONS software determines the MLST type of the single colony. If base call frequency differences between pool and single colony indicate the presence of an additional strain, the differences are used to computationally infer the second MLST type without the need for MLST of additional individual colonies. In mixes of previously typed pairs of strains, 100+1 NGS-MLST reliably detected a second strain. Inferred MLST types of second strains were always more similar to their real MLST types than to those of any of 59 other isolates (22 of 31 inferred types were identical to the real type). Using 100+1 NGS-MLST we found that 7/60 human samples, including three superficial candidiasis samples, contained two unrelated strains. In addition, at least one sample contained two highly similar variants of the same strain. The probability of samples containing unrelated strains appears to differ considerably between body sites. Our findings indicate the need for wider surveys to determine if, for some types of samples, routine testing for the presence of multiple strains is warranted. 100+1 NGS-MLST is effective for this purpose.

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Updating the genomic taxonomy and epidemiology of Campylobacter hyointestinalis | Scientific Reports

Updating the genomic taxonomy and epidemiology of Campylobacter hyointestinalis | Scientific Reports | Microbiology @ Massey | Scoop.it

Campylobacter hyointestinalis is a member of an emerging group of zoonotic Campylobacter spp. that are increasingly identified in both gastric and non-gastric disease in humans. Here, we discovered C. hyointestinalis in three separate classes of New Zealand ruminant livestock; cattle, sheep and deer. To investigate the relevance of these findings we performed a systematic literature review on global C. hyointestinalis epidemiology and used comparative genomics to better understand and classify members of the species. We found that C. hyointestinalis subspecies hyointestinalis has an open pangenome, with accessory gene contents involved in many essential processes such as metabolism, virulence and defence. We observed that horizontal gene transfer is likely to have played an overwhelming role in species diversification, favouring a public-goods-like mechanism of gene ‘acquisition and resampling’ over a tree-of-life-like vertical inheritance model of evolution. As a result, simplistic gene-based inferences of taxonomy by similarity are likely to be misleading. Such genomic plasticity will also mean that local evolutionary histories likely influence key species characteristics, such as host-association and virulence. This may help explain geographical differences in reported C. hyointestinalis epidemiology and limits what characteristics may be generalised, requiring further genomic studies of C. hyointestinalis in areas where it causes disease.

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Epichloë hybrida, sp. nov., an emerging model system for investigating fungal allopolyploidy | Mycologia

Epichloë hybrida, sp. nov., an emerging model system for investigating fungal allopolyploidy | Mycologia | Microbiology @ Massey | Scoop.it
Endophytes of the genus Epichloë (Clavicipitaceae, Ascomycota) frequently occur within cool-season grasses and form interactions with their hosts that range from mutualistic to antagonistic. Many Epichloë species have arisen via interspecific hybridization, resulting in species with two or three subgenomes that retain all or nearly all of their original parental genomes, a process termed allopolyploidization. Here, we characterize Epichloë hybrida, sp. nov., a mutualistic species that has increasingly become a model system for investigating allopolyploidy in fungi. The Epichloë species so far identified as the closest known relatives of the two progenitors of E. hybrida are E. festucae var. lolii and E. typhina. We confirm that the nuclear genome of E. hybrida contains two homeologs of most protein-coding genes from E. festucae and E. typhina, with genome-wide gene expression analysis indicating a slight bias in overall gene expression from the E. typhina subgenome. Mitochondrial DNA is detectable only from E. festucae, whereas ribosomal DNA is detectable only from E. typhina. Inheriting ribosomal DNA from just one parent might be expected to preferentially favor interactions with ribosomal proteins from the same parent, but we find that ribosomal protein genes from both parental subgenomes are nearly all expressed equally in E. hybrida. Finally, we provide a comprehensive set of resources for this model system that are intended to facilitate further study of fungal hybridization by other researchers.
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Leptospirosis strain found in alpaca

Leptospirosis strain found in alpaca | Microbiology @ Massey | Scoop.it

A leptospirosis strain has been found in New Zealand alpaca for the first time. The disease is a known dairy cow complaint, which is sometimes passed on to dairy and abattoir workers. New findings that alpacas are also vulnerable to the disease were revealed at the International Leptospirosis Society Conference at Palmerston North. 

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Chromatin‐level regulation of the fragmented dothistromin gene cluster in the forest pathogen Dothistroma septosporum | Molecular Microbiology

Chromatin‐level regulation of the fragmented dothistromin gene cluster in the forest pathogen Dothistroma septosporum | Molecular Microbiology | Microbiology @ Massey | Scoop.it
Genes required for fungal secondary metabolite production are usually clustered, co-regulated and expressed in stationary growth phase. Chromatin modification has an important role in co-regulation of secondary metabolite genes. The virulence factor dothistromin, a relative of aflatoxin, provided a unique opportunity to study chromatin level regulation in a highly fragmented gene cluster that is switched on during early exponential growth phase. We analysed three histone modification marks by ChIP-qPCR and gene deletion in the pine pathogen Dothistroma septosporum to determine their effects on dothistromin gene expression across a time course and at different loci of the dispersed gene cluster. Changes in gene expression and dothistromin production were associated with changes in histone marks, with higher acetylation (H3K9ac) and lower methylation (H3K9me3, H3K27me3) during early exponential phase at the onset of dothistromin production. But while H3K27me3 directly influenced dothistromin genes dispersed across chromosome 12, effects of H3K9 acetylation and methylation were orchestrated mainly through a centrally located pathway regulator gene DsAflR. These results revealed that secondary metabolite production can be controlled at the chromatin-level despite the genes being dispersed. They also suggest that patterns of chromatin modification are important in adaptation of a virulence factor for a specific role in planta.
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Origin and Evolution of the Kiwifruit Canker Pandemic | Genome Biology and Evolution

Origin and Evolution of the Kiwifruit Canker Pandemic | Genome Biology and Evolution | Microbiology @ Massey | Scoop.it

Recurring epidemics of kiwifruit (Actinidia spp.) bleeding canker disease are caused by Pseudomonas syringae pv. actinidiae (Psa). In order to strengthen understanding of population structure, phylogeography, and evolutionary dynamics, we isolated Pseudomonas from cultivated and wild kiwifruit across six provinces in China. Based on the analysis of 80 sequenced Psa genomes, we show that China is the origin of the pandemic lineage but that strain diversity in China is confined to just a single clade. In contrast, Korea and Japan harbor strains from multiple clades. Distinct independent transmission events marked introduction of the pandemic lineage into New Zealand, Chile, Europe, Korea, and Japan. Despite high similarity within the core genome and minimal impact of within-clade recombination, we observed extensive variation even within the single clade from which the global pandemic arose.

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Genomic epidemiology of methicillin-susceptible Staphylococcus aureus across colonisation and skin and soft tissue infection | Journal of Infection

Objectives

Staphylococcus aureus skin and soft tissue infection (Sa-SSTI) places a significant burden on healthcare systems. New Zealand has a high incidence of Sa-SSTI, and here most morbidity is caused by a polyclonal methicillin-susceptible (MSSA) bacterial population. However, MSSA also colonise asymptomatically the cornified epithelia of approximately 20% of the population, and their divide between commensalism and pathogenicity is poorly understood. We aimed to see whether MSSA are genetically differentiated across colonisation and SSTI; and given the close interactions between people and pets, whether strains isolated from pets differ from human strains.


Methods

We compared the genomes of contemporaneous colonisation and clinical MSSA isolates obtained in New Zealand from humans and pets.


Results

Core and accessory genome comparisons revealed a homogeneous bacterial population across colonisation, disease, humans, and pets. The rate of MSSA colonisation in dogs was comparatively low (5.4%).


Conclusions

In New Zealand, most Sa-SSTI morbidity is caused by a random sample of the colonising MSSA population, consistent with the opportunistic infection model rather than the paradigm distinguishing strains according to their pathogenicity. Thus, studies of the factors determining colonisation and immune-escape may be more beneficial than comparative virulence studies. Contact with house-hold pets may pose low zoonotic risk.

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Untreatable gonorrhoea, are we there yet? | The Biochemist - Emerging Diseases

Untreatable gonorrhoea, are we there yet? | The Biochemist - Emerging Diseases | Microbiology @ Massey | Scoop.it
Gonorrhoea is a relatively common and easily spread bacterial sexually transmitted disease that can cause a wide spectrum of symptoms from none to severe outcomes. Through its penchant for modifying its own genetics, Neisseria gonorrhoeae has gradually evolved to become one of modern medicine’s greatest adversaries. In most countries we have only one antibiotic left to treat it with, and even that option is rapidly running out. So how do we stop this train wreck? What do we do when the treatments run out altogether?
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Seasonal changes in the digesta-adherent rumen bacterial communities of dairy cattle grazing pasture | PLoS ONE

Seasonal changes in the digesta-adherent rumen bacterial communities of dairy cattle grazing pasture | PLoS ONE | Microbiology @ Massey | Scoop.it
The complex microbiota that resides within the rumen is responsible for the break-down of plant fibre. The bacteria that attach to ingested plant matter within the rumen are thought to be responsible for initial fibre degradation. Most studies examining the ecology of this important microbiome only offer a ‘snapshot’ in time. We monitored the diversity of rumen bacteria in four New Zealand dairy cows, grazing a rye-grass and clover pasture over five consecutive seasons, using high throughput pyrosequencing of bacterial 16S rRNA genes. We chose to focus on the digesta-adherent bacterial community to learn more about the stability of this community over time. 16S rRNA gene sequencing showed a high level of bacterial diversity, totalling 1539 operational taxonomic units (OTUs, grouped at 96% sequence similarity) across all samples, and ranging from 653 to 926 OTUs per individual sample. The nutritive composition of the pasture changed with the seasons as did the production phase of the animals. Sequence analysis showed that, overall, the bacterial communities were broadly similar between the individual animals. The adherent bacterial community was strongly dominated by members of Firmicutes (82.1%), followed by Bacteroidetes (11.8%). This community differed between the seasons, returning to close to that observed in the same season one year later. These seasonal differences were only small, but were statistically significant (p < 0.001), and were probably due to the seasonal differences in the diet. These results demonstrate a general invariability of the ruminal bacterial community structure in these grazing dairy cattle.
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Institutional gastroenteritis outbreaks and time to notify public health services I New Zealand Medical Journal

Institutional gastroenteritis outbreaks and time to notify public health services I New Zealand Medical Journal | Microbiology @ Massey | Scoop.it
Summary
Gastroenteritis accounts for the majority of all outbreak notifications in New Zealand. Prompt notification to the Public Health Service reduces the outbreak duration and size.

Abstract

Aim
We report a quantification and visualisation of the association between the time to notify public health service (PHS) and the duration and size of institutional gastroenteritis outbreaks, and explore the seasonality and trend of the outbreaks.

Method
Descriptive analysis was performed on institutional gastroenteritis outbreak data from a North Island PHS (1 January 2009–31 December 2014). Time-series analysis was used to explore the seasonality and trend of outbreaks. Multivariate analyses were performed to quantify the association between the time to notify PHS and the duration and size of outbreaks.

Results
One hundred and seventy-five gastroenteritis outbreaks (from 58 facilities) were included in descriptive analyses. A significant increasing trend (p=0.01) without seasonal pattern was confirmed by time-series analysis. Shorter notification time was associated with shorter duration and smaller size of outbreaks, eg, duration of outbreaks when time to notify was ≥7 days, was 3.4 days (p=0.001, 95% CI=3.1–3.7) longer than baseline time to notify (0–1 day).

Conclusion
Prompt notification to the PHS appears to be a factor associated with reduced outbreak duration and size.
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Colonisation of lettuce by Listeria Monocytogenes | International Journal of Food Science & Technology

Colonisation of lettuce by Listeria Monocytogenes | International Journal of Food Science & Technology | Microbiology @ Massey | Scoop.it
Foodborne illnesses involving ready-to-eat vegetables are increasing. Lettuce is the third most consumed fresh vegetable in the United States with worth approximately $1.9 billion, making it the most valuable leafy crop. Previous reviews have described the survival of pathogenic bacteria such as E. coli O157:H7 and Salmonella on different ready-to-eat vegetables, but the colonisation of lettuce by Listeria has received limited attention. Listeria monocytogenes has high mortality compared to other foodborne pathogens such as Salmonella. This review summarises recent studies on the mechanisms of attachment and colonisation of Listeria on lettuce leaves. We discuss various factors that affect colonisation of lettuce by Listeria in terms of the number of bacteria that can be recovered after inoculation, the effect of washing, different radiation treatments and cultivation systems on the recovery of Listeria. We propose strategies that can be used to minimise the colonisation of lettuce by Listeria to enhance food safety.
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New gene transfer rules could help prevent spread of antibiotic resistance | The Conversation

New gene transfer rules could help prevent spread of antibiotic resistance | The Conversation | Microbiology @ Massey | Scoop.it

Unlike other organisms, bacteria can take up genetic material from their environment. This ability to exchange genes enables them to pick up new traits such as different metabolic pathways, virulence genes and antibiotic resistance. Better understanding of the complex mechanisms of gene transfer may be the key for holding the line against the global threat of increasing antibiotic resistance. Our latest findings have taken us step closer to this goal by uncovering a new set of rules.

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Biological Roles of Protein-Coding Tandem Repeats in the Yeast Candida albicans | Journal of Fungi

Biological Roles of Protein-Coding Tandem Repeats in the Yeast Candida albicans | Journal of Fungi | Microbiology @ Massey | Scoop.it
Tandem repeat (TR) DNA mutates faster than other DNA by insertion and deletion of repeats. Large parts of eukaryotic proteomes are encoded by ORFs containing protein-coding TRs (TR-ORFs, pcTRs) with largely unknown biological consequences. We explored these in the yeast Candida albicans, an opportunistic human pathogen. We found that almost half of C. albicans’ proteins are encoded by TR-ORFs. pcTR frequency differed only moderately between different gene (GO) categories. Bioinformatic predictions of genome-wide mutation rates and clade-specific differences in pcTR allele frequencies indicated that pcTRs (i) significantly increase the genome-wide mutation rate; (ii) significantly impact on fitness and (iii) allow the evolution of selectively advantageous clade-specific protein variants. Synonymous mutations reduced the repetitiveness of many amino acid repeat-encoding pcTRs. A survey, in 58 strains, revealed that in some pcTR regions in which repetitiveness was not significantly diminished by synonymous mutations the habitat predicted which alleles were present, suggesting roles of pcTR mutation in short-term adaptation and pathogenesis. In C. albicans pcTR mutation apparently is an important mechanism for mutational advance and possibly also rapid adaptation, with synonymous mutations providing a mechanism for adjusting mutation rates of individual pcTRs. Analyses of Arabidopsis and human pcTRs showed that the latter also occurs in other eukaryotes.
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Genome-by-genome approach for fast bacterial genealogical relationship evaluation | Bioinformatics

Genome-by-genome approach for fast bacterial genealogical relationship evaluation | Bioinformatics | Microbiology @ Massey | Scoop.it

Motivation

Large-scale whole-genome sequencing dataset-based studies are becoming increasingly common in pathogen surveillance and outbreak investigations. A highly discriminative and time-efficient bioinformatics tool is needed to transform large amounts of sequencing data into usable biological information. To replace the intuitive, yet inefficient, way of gene-by-gene allele calling algorithm, a new algorithm using genome-by-genome approach was developed.


Results

Tests showed that the program equipped with the new algorithm achieved significant improvements in allele calling efficiency compared to a conventional gene-by-gene approach. The new program, Fast-GeP, rendered a fast and easy way to infer high-resolution genealogical relationships between bacterial isolates using whole-genome sequencing data.


Availability and implementation

FAST-GeP is freely available from: https://github.com/jizhang-nz/fast-GeP.

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Heterologous Biosynthesis of Nodulisporic Acid F - Journal of the American Chemical Society

Heterologous Biosynthesis of Nodulisporic Acid F - Journal of the American Chemical Society | Microbiology @ Massey | Scoop.it

Nodulisporic acids comprise a group of valuable indole diterpenes that exhibit potent insecticidal activities. We report the identification of a gene cluster in the genome of the filamentous fungus Hypoxylon pulicicidum (Nodulisporium sp.) that contains genes responsible for the biosynthesis of nodulisporic acids. Using Penicillium paxilli as a heterologous host, and through pathway reconstitution experiments, we identified the function of four genes involved in the biosynthesis of the nodulisporic acid core compound, nodulisporic acid F (NAF). Two of these genes (nodM and nodW) are especially significant as they encode enzymes with previously unreported functionality: nodM encodes a 3-geranylgeranylindole epoxidase capable of catalyzing only a single epoxidation step to prime formation of the distinctive ring structure of nodulisporic acids, and nodW encodes the first reported gene product capable of introducing a carboxylic acid moiety to an indole diterpene core structure that acts as a reactive handle for further modification. Here, we present the enzymatic basis for the biosynthetic branch point that gives rise to nodulisporic acids.

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The fine balance between mutualism and antagonism in the Epichloë festucae–grass symbiotic interaction | Current Opinion in Plant Biology

The fine balance between mutualism and antagonism in the Epichloë festucae–grass symbiotic interaction | Current Opinion in Plant Biology | Microbiology @ Massey | Scoop.it
Epichloë endophytes form mutualistic symbiotic associations with aerial tissues of temperate grasses. Intercalary growth of hyphae within the leaves enables fungal growth to be synchronized with host leaf growth, leading to formation of a highly structured and tightly regulated symbiotic network. Mutations in fungal genes that disrupt cell–cell fusion and other key signalling pathways lead to an antagonistic interaction characterized by unregulated growth of endophytic hyphae and detrimental effects on host growth. Transcriptome analysis of these mutant associations provides key insights into the regulation of the symbiosis. In nature a similar switch in growth occurs when hyphae transition into the sexual cycle forming stromata that abort host inflorescences. Endophyte infection of the grass host leads to a major reprogramming of host metabolism and alters host development. Changes in endophyte cell wall structure and the repertoire of effectors secreted into the host apoplast accompany establishment of a mutualistic interaction within the leaves.
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Science Made Simple: Dr Heather Hendrickson

Science Made Simple: Dr Heather Hendrickson | Microbiology @ Massey | Scoop.it

Surveys have shown one third of Kiwis think science is too specialised to understand. In this series, scientists who tackle mind-bogglingly complex problems each day make it simple for us. Today, we talk to Massey University microbiologist Dr Heather Hendrickson

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Evolution of copper resistance in the kiwifruit pathogen Pseudomonas syringae pv. actinidiae through acquisition of integrative conjugative elements and plasmids | Environmental Microbiology

Evolution of copper resistance in the kiwifruit pathogen Pseudomonas syringae pv. actinidiae through acquisition of integrative conjugative elements and plasmids | Environmental Microbiology | Microbiology @ Massey | Scoop.it

Horizontal gene transfer can precipitate rapid evolutionary change. In 2010 the global pandemic of kiwifruit canker disease caused by Pseudomonas syringae pv. actinidiae (Psa) reached New Zealand. At the time of introduction, the single clone responsible for the outbreak was sensitive to copper, however, analysis of a sample of isolates taken in 2015 and 2016 showed that a quarter were copper resistant. Genome sequences of seven strains showed that copper resistance – comprising czc/cusABC and copABCD systems – along with resistance to arsenic and cadmium, was acquired via uptake of integrative conjugative elements (ICEs), but also plasmids. Comparative analysis showed ICEs to have a mosaic structure, with one being a tripartite arrangement of two different ICEs and a plasmid that were isolated in 1921 (USA), 1968 (NZ) and 1988 (Japan), from P. syringae pathogens of millet, wheat and kiwifruit respectively. Two of the Psa ICEs were nearly identical to two ICEs isolated from kiwifruit leaf colonists prior to the introduction of Psa into NZ. Additionally, we show ICE transfer in vitro and in planta, analyze fitness consequences of ICE carriage, capture the de novo formation of novel recombinant ICEs, and explore ICE host-range.

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Local and global genetic diversity of protozoan parasites: Spatial distribution of Cryptosporidium and Giardia genotypes | PLoS Neglected Tropical Diseases

Local and global genetic diversity of protozoan parasites: Spatial distribution of Cryptosporidium and Giardia genotypes | PLoS Neglected Tropical Diseases | Microbiology @ Massey | Scoop.it
Author summary Infectious diseases threaten the health and well-being of wildlife, livestock and human populations and contribute to significant economic impact in agriculture and medical care. Cryptosporidium and Giardia are enteric protozoan pathogens that cause diarrhea and nutritional disorders on a global level. Using molecular analysis and a review framework we showed that species and genetic variants within genera Cryptosporidium and Giardia (including two species recently infecting humans) found in an island system are not different from other parts of the world. This similarity is likely due to high gene flow of historical and current human activity (travel and trade) and persistence of large host population sizes, such as cattle and people. We also show that, although species and genotypes are widely distributed, new variants will arise when sampling effort increase and their dispersal will be facilitated by human activity. These findings suggest that geographical distribution of species and genotypes within Cryptosporidium and Giardia parasites may yield important clues for designing effective surveillance strategies and identification of factors driving within and cross species transmission.
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N2O emissions during microalgae outdoor cultivation in 50 L column photobioreactors | Algal Research

N2O emissions during microalgae outdoor cultivation in 50 L column photobioreactors | Algal Research | Microbiology @ Massey | Scoop.it
This study investigated the potential environmental significance of nitrous oxide (N2O) emissions from outdoor microalgal cultivation. Chlorella vulgaris, Neochloris sp., and Arthrospira platensis were cultivated in 50 L pilot scale photobioreactors (PBRs) operated in fed batch mode and fed with either nitrate (NO3−) or ammonium (NH4+) as the nitrogen (N) source. When NO3− was supplied as N-source, Neochloris sp., and C. vulgaris cultures emitted 50.0–14,200 nmol·N2O·m− 2·h− 1 (36 days of cultivation, n = 136, median = 2220 nmol·N2O·m− 2·h− 1) and 9.60–38,000 nmol·N2O·m− 2·h− 1 (90 days of cultivation, n = 332, median = 4050 nmol·N2O·m− 2·h− 1), respectively. Based on the emissions representing 25–75% of the data recorded from C. vulgaris fed NO3− (1500–8000 nmol·N2O·m− 2·h− 1), N2O emissions factors were estimated as 0.1–0.4% of the N input load of 25 g·N·d− 1. Further monitoring of C. vulgaris cultures showed that N2O emissions were positively correlated to biomass concentration (R2 = 0.77) and light intensity (R2 = 0.57). Nitrous oxide emissions were not detected when C. vulgaris was cultivated using ammonium as N-source (32 days of cultivation, n = 84), or when A. platensis cultures were cultivated with NO3− as N-source (36 days of cultivation, n = 90). The use of ammonium as N-source or the selection of appropriate algae species could therefore provide simple N2O mitigation strategies.
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IDC2 and IDC3, two genes involved in cell non-autonomous signaling of fruiting body development in the model fungus Podospora anserina | Developmental Biology

IDC2 and IDC3, two genes involved in cell non-autonomous signaling of fruiting body development in the model fungus Podospora anserina | Developmental Biology | Microbiology @ Massey | Scoop.it
Filamentous ascomycetes produce complex multicellular structures during sexual reproduction. Little is known about the genetic pathways enabling the construction of such structures. Here, with a combination of classical and reverse genetic methods, as well as genetic mosaic and graft analyses, we identify and provide evidence for key roles for two genes during the formation of perithecia, the sexual fruiting bodies, of the filamentous fungus Podospora anserina. Data indicate that the proteins coded by these two genes function cell-non-autonomously and that their activity depends upon conserved cysteines, making them good candidate for being involved in the transmission of a reactive oxygen species (ROS) signal generated by the PaNox1 NADPH oxidase inside the maturing fruiting body towards the PaMpk1 MAP kinase, which is located inside the underlying mycelium, in which nutrients are stored. These data provide important new insights to our understanding of how fungi build multicellular structures.
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