Microbial Speciation

Shapiro, B. Jesse; Polz, Martin F.

doi:10.1101/cshperspect.a018143

Cited by 87 publications

(94 citation statements)

References 92 publications

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“…This suggests that V. cholerae is likely to form transient clonal complexes blooming locally, which are genotypically and phenotypically differentiated, displaying divergent spatial distribution patterns and potentially occupying various ecological niches. It has previously been argued that such spatial separation is a prerequisite for the differentiation of gene pools into what could eventually become recognizably different groups of bacteria (25).…”

Section: Resultsmentioning

confidence: 99%

“…The identification of differential spatial distribution of various strains within V. cholerae would indicate that such ecological differentiation might occur at the subspecies level. Ultimately, differentially adapted lineages within a species might be more meaningful units not only when considering the ecology of organisms but also in tracking potentially harmful pathogens (25).…”

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confidence: 99%

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A Small Number of Phylogenetically Distinct Clonal Complexes Dominate a Coastal Vibrio cholerae Population

Kirchberger

Orata

Barlow

et al. 2016

Appl Environ Microbiol

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Vibrio cholerae is a ubiquitous aquatic microbe in temperate and tropical coastal areas. It is a diverse species, with many isolates that are harmless to humans, while others are highly pathogenic. Most notable among them are strains belonging to the pandemic O1/O139 serogroup lineage, which contains the causative agents of cholera. The environmental selective regimes that led to this diversity are key to understanding how pathogens evolve in environmental reservoirs. A local population of V. cholerae and its close relative Vibrio metoecus from a coastal pond and lagoon system was extensively sampled during two consecutive months across four size fractions (480 isolates). In stark contrast to previous studies, the observed population was highly clonal, with 60% of V. cholerae isolates falling into one of five clonal complexes, which varied in abundance in the short temporal scale sampled. V. cholerae clonal complexes had significantly different distributions across size fractions and the two environments sampled, the pond and the lagoon. Sequencing the genomes of 20 isolates representing these five V. cholerae clonal complexes revealed different evolutionary trajectories, with considerable variations in gene content with potential ecological significance. Showing genotypic differentiation and differential spatial distribution, the dominant clonal complexes are likely ecologically divergent. Temporal variation in the relative abundance of these complexes suggests that transient blooms of specific clones could dominate local diversity. IMPORTANCEVibrio cholerae is commonly found in coastal areas worldwide, with only a single group of this bacterium capable of causing severe cholera outbreaks. However, the potential to evolve the ability to cause disease exists in many strains of this species in its aquatic reservoir. Understanding how pathogenic bacteria evolve requires the study of their natural environments. By extensive sampling in a geographically restricted location in the United States, we found that most cells of a V. cholerae population belong to only a small number of strains. Analysis of their genome composition and spatial distribution indicates differential environmental adaptations between these strains. Other strains exist in smaller numbers, and the population was found to be temporally varied. This suggests frequent bloom and collapse cycles on a time scale of weeks. These population dynamics make it possible that more virulent strains could stochastically rise to large numbers, allowing for infection to occur. W hile long thought of as being specifically adapted to life as a pathogen in the human gut (1), numerous strains of Vibrio cholerae with varied degrees of virulence thrive in the brackish waters of lagoons and estuaries of the world (2), from the coast of Australia (3) to Iceland (4). The bacterium is believed to form close associations with aquatic invertebrates, preferentially living a life attached to the chitinous surfaces of those animals (5, 6). It is also regularly isolated f...

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

A Small Number of Phylogenetically Distinct Clonal Complexes Dominate a Coastal Vibrio cholerae Population

Kirchberger

Orata

Barlow

et al. 2016

Appl Environ Microbiol

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“…The ten cadherin domains analysed share considerable sequence and structural homology. They have nominally different isoelectric point (pI) values varying over two units of pH, owing to differences in their individual contents of negativelycharged (NC) residues [5]. We studied these domains to examine whether they display any anomalous mobility, and also whether they can also provide any insights into how and why highly acidic proteins display anomalous mobility during denaturing and reducing electrophoresis (AM-DRE) unlike most other proteins which display normal mobility during denaturing and reducing electrophoresis (NM-DRE).…”

Section: Introductionmentioning

confidence: 99%

Understanding anomalous mobility of proteins on SDS‐PAGE with special reference to the highly acidic extracellular domains of human E‐ and N‐cadherins

2019

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During SDS‐PAGE experiments, proteins generally display electrophoretic mobility in keeping with their molecular weights; however, some proteins display anomalies in mobility. Here, we focus attention on the anomalies displayed by the highly acidic ∼110 residues‐long, sequence‐homologous, structurally‐analogous, extracellular domains of human E‐ and N‐cadherin. We report that there is a strong correlation between the acidity of each domain and the degree of the anomaly that it displays. The anomaly is only seen if the ratio of the numbers of negatively‐charged and positively‐charged residues is equal to or greater than the value of 1.50. The degree of the anomaly rises in proportion with this NC:PC ratio. Greater‐than‐expected anomalies are observed for domains containing dense clusters of negatively charged residues. A simple explanation for these observations is that highly acidic domains electrostatically repel SDS. This results in insufficient SDS binding, insufficient electromotive incentive and (consequently) lowered electrophoretic mobility. This explanation is in consonance with the current view that initial stages of SDS‐protein engagement tend to be dominated by electrostatics. We discuss the current anomalies within the broader context of all conceivable explanations for such anomalies.

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“…Such potential target genes can be manipulated by RNA interference [86], thus offering population genomic resources to functionally characterize host-pathogen interactions. [25,26]. Because vibrios have served as major models in this effort, we can apply this population framework to the ecology and evolution of virulence.…”

Section: Population Structure As a Framework For Analysis Of Disease mentioning

confidence: 99%

Oysters and Vibrios as a Model for Disease Dynamics in Wild Animals

Roux

Wegner

Polz

2016

Trends in Microbiology

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121

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Disease dynamics in the wild are influenced by a number of ecological and evolutionary factors not addressed by traditional laboratory-based characterization of pathogens. Here we propose the oyster, Crassostrea gigas, as a model for studying the interaction of the environment, bacterial pathogens, and the host in disease dynamics. We show that an important first step is to ask whether the functional unit of pathogenesis is a bacterial clone, a population, or a consortium in order to assess triggers of disease outbreaks and devise appropriate monitoring tools. Moreover, the development of specific-pathogen-free (SPF) oysters has enabled assessment of the infection process under natural conditions. Finally, recent results show the importance of microbial interactions and host genetics in determining oyster health and disease. Involvement of Vibrios in Oyster DiseaseVibrios are ubiquitous marine bacteria that are ecologically and metabolically diverse members of planktonic and animal-associated microbial communities [1,2]. They have been called 'opportuni-trophs ' [3] due to their high metabolic versatility and genetic variability coupled with chemotaxis and quorum sensing (see Glossary), all of which allow high colonization potential [4,5]. Vibrios encompass the ancient and well-studied human pathogen, Vibrio cholerae, as well as some less thoroughly characterized opportunistic pathogens capable of infecting humans, including Vibrio parahaemolyticus and Vibrio vulnificus [2]. Even less well understood are the consequences of Vibrio infections in other animals, including fish, coral, shrimp, and mollusks; however, infections in these organisms can have important environmental and economic consequences [6]. In particular, vibrios have been suggested to be responsible for repeated mortality outbreaks in oyster beds (Crassostrea gigas) in France that have resulted in losses of up to 80-100% of production (Box 1). However the onset and progression of disease in the wild has been difficult to follow in the past. Hence, it is often not clear whether vibrios isolated from diseased oysters are the causative agent, secondary opportunistic colonizers, or commensals [7].Vibrios appear to employ a diversity of molecular mechanisms to infect oysters, albeit our knowledge is based mainly on very few model strains. For example, infection with Vibrio tasmaniensis LGP32 [8] involves an intracellular phase in hemocytes, which are the oyster's immune-competent cells, and resistance to (i) antimicrobial peptides (AMPs), (ii) reactive oxygen species (ROS) and (iii) copper [9][10][11][12]. Vibrio aestuarianus, by [ 1 5 _ T D $ D I F F ] contrast, interacts with hemocytes extracellularly and inhibits their phagocytotic abilities [13,14]. A common theme, however, is that metalloproteases have been linked to toxicity in V. tasmaniensis, V. aestuarianus, Vibrio corallilyticus, and Vibrio tubiashi [13,15,16]. Nonetheless, the disruption of TrendsKnowledge of the genetic structure of the Vibrio population provides a framework for mapping d...

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Microbial Speciation

Cited by 87 publications

References 92 publications

A Small Number of Phylogenetically Distinct Clonal Complexes Dominate a Coastal Vibrio cholerae Population

A Small Number of Phylogenetically Distinct Clonal Complexes Dominate a Coastal Vibrio cholerae Population

Understanding anomalous mobility of proteins on SDS‐PAGE with special reference to the highly acidic extracellular domains of human E‐ and N‐cadherins

Oysters and Vibrios as a Model for Disease Dynamics in Wild Animals

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