The book of Lambda does not tell us that naturally occurring lysogens of Escherichia coli are likely to be resistant as well as immune.

The most significant difference between bacteriophages functionally and ecologically is whether they are purely lytic (virulent) or temperate. Virulent phages can only be transmitted horizontally by infection, most commonly with the death of their hosts. Temperate phages can also be transmitted horizontally, but upon infection of susceptible bacteria, their genomes can be incorporated into that of their host's as a prophage and be transmitted vertically in the course of cell division by their lysogenic hosts. From what we know from studies with the temperate phage Lambda and other temperate phages, in laboratory culture, lysogenic bacteria are protected from killing by the phage coded for by their prophage by immunity; where upon infecting lysogens, the free temperate phage coded by their prophage is lost. Why are lysogens not only resistant but also immune to the phage coded by their prophage since immunity does not confer protection against virulent phages? To address this question, we used a mathematical model and performed experiments with temperate and virulent mutants of the phage Lambda in laboratory culture. Our models predict and experiments confirm that selection would favor the evolution of resistant and immune lysogens, particularly if the environment includes virulent phage that shares the same receptors as the temperate. To explore the validity and generality of this prediction, we examined 10 lysogenic Escherichia coli from natural populations. All 10 were capable of forming immune lysogens, but their original hosts were resistant to the phage coded by their prophage.

Ancient Darwinian replicators nested within eubacterial genomes.

Integrative mobile genetic elements (MGEs), such as transposons and insertion sequences, propagate within bacterial genomes, but persistence times in individual lineages are short. For long-term survival, MGEs must continuously invade new hosts by horizontal transfer. Theoretically, MGEs that persist for millions of years in single lineages, and are thus subject to vertical inheritance, should not exist. Here we draw attention to an exception - a class of MGE termed REPIN. REPINs are non-autonomous MGEs whose duplication depends on non-jumping RAYT transposases. Comparisons of REPINs and typical MGEs show that replication rates of REPINs are orders of magnitude lower, REPIN population size fluctuations correlate with changes in available genome space, REPIN conservation depends on RAYT function, and REPIN diversity accumulates within host lineages. These data lead to the hypothesis that REPINs form enduring, beneficial associations with eubacterial chromosomes. Given replicative nesting, our hypothesis predicts conflicts arising from the diverging effects of selection acting simultaneously on REPINs and host genomes. Evidence in support comes from patterns of REPIN abundance and diversity in two distantly related bacterial species. Together this bolsters the conclusion that REPINs are the genetic counterpart of mutualistic endosymbiotic bacteria.

High genetic diversity and limited regional population differentiation in populations of Calonectria pseudoreteaudii from Eucalyptus plantations.

Calonectria pseudoreteaudii causes a serious and widespread disease known as Calonectria leaf blight in Eucalyptus plantations of southern China. Little is known regarding the population biology or reproductive biology of this pathogen in the affected areas. The aims of this study were to investigate the genetic diversity, population structure and the reproductive mode of C. pseudoreteaudii from affected Eucalyptus plantations of southern China. Ten polymorphic SSR markers were developed for the species, and were used to genotype 311 isolates from eight populations. The mating types of all isolates were identified using the MAT gene primers. The results revealed a high level of genetic diversity of the pathogen in all investigated populations. Of the 90 multilocus genotypes detected, ten were shared between at least two populations. With the exception of one population from HuiZhou, GuangDong (7HZ), the most dominant genotype was shared in seven remaining populations. DAPC and population differentiation analyses showed that the 7HZ population was well differentiated from the others and that there was no significant differentiation between the remaining populations. AMOVA suggested that most molecular variation was within populations (86%). Index of association analysis was consistent with a predominantly asexual life cycle for C. pseudoreteaudii in the studied regions. Although both mating types were detected in seven of the eight populations, the MAT1-1/MAT1-2 ratios in these populations deviated significantly from the 1:1 ratio expected in a randomly mating population.

Genotyping-by-Sequencing Reveals Population Differentiation and Linkage Disequilibrium in Alternaria linariae from Tomato.

Alternaria linariae is an economically important foliar pathogen that causes early blight disease in tomatoes. Understanding genetic diversity, population genetic structure, and evolutionary potential is crucial to contemplating effective disease management strategies. We leveraged genotyping-by-sequencing (GBS) technology to compare genome-wide variation in 124 isolates of Alternaria spp. (A. alternata, A. linariae, and A. solani) for comparative genome analysis and to test the hypotheses of genetic differentiation and linkage disequilibrium (LD) in A. linariae collected from tomatoes in western North Carolina. We performed a pangenome-aware variant calling and filtering with GBSapp and identified 53,238 variants conserved across the reference genomes of three Alternaria spp. The highest marker density was observed on chromosome 1 (7 Mb). Both discriminant analysis of principal components and Bayesian model-based STRUCTURE analysis of A. linariae isolates revealed three subpopulations with minimal admixture. The genetic differentiation coefficients (FST) within A. linariae subpopulations were similar and high (0.86), indicating that alleles in the subpopulations are fixed and the genetic structure is likely due to restricted recombination. Analysis of molecular variance indicated higher variation among populations (89%) than within the population (11%). We found long-range LD between pairs of loci in A. linariae, supporting the hypothesis of low recombination expected for a fungal pathogen with limited sexual reproduction. Our findings provide evidence of a high level of population genetic differentiation in A. linariae, which reinforces the importance of developing tomato varieties with broad-spectrum resistance to various isolates of A. linariae.

Whole genome resequencing reveals significant genetic differentiation between Exserohilum turcicum populations from maize and sorghum and candidate effector genes related to host specificity (Retracted).

After the manuscript was accepted, inconsistencies in the analyses were detected. These inconsistencies affected the general conclusion of the manuscript. This article was retracted on 27 March 2024. A peer-reviewed revised version was subsequently accepted: https://doi.org/10.1094/PHYTO-05-24-0172-R. Exserohilum turcicum is a devastating fungal pathogen that infects both maize and sorghum, leading to severe leaf diseases of the two crops. According to host specificity, pathogenic isolates of E. turcicum are divided into two formae speciales, namely E. turcicum f. sp. zeae and E. turcicum f. sp. sorghi. To date, the molecular mechanism underlying the host specificity of E. turcicum is marginally known. In this study, the whole genomes of 60 E. turcicum isolates collected from both maize and sorghum were resequenced, which enabled identification of 147,847 high-quality SNPs in total. Based on the SNPs, all isolates were clustered into four genetic groups that had a close relationship with host source. This observation was validated by the result of principal component analysis. The analysis of population structure revealed that there was obvious genetic differentiation between maize and sorghum host populations. Further analysis showed that 5,431 SNPs, including 612 nonsynonymous SNPs, were completely co-segregated with host source. These nonsynonymous SNPs were located in 539 genes in which 18 genes were predicted to encode secretory proteins, including six putative effector genes. The sequence polymorphism analysis of the six effector genes in 60 isolates indicated that these genes were perfectly co-segregated with host source. All SNVs in the coding regions of these genes were non-synonymous substitutions, suggesting that these genes were subject to strong positive selection pressure. These findings provide new insights into the molecular basis of host specificity in E. turcicum.

Open Access and Reproducibility in Plant Pathology Research: Guidelines and Best Practices.

The landscape of scientific publishing is experiencing a transformative shift toward open access, a paradigm that mandates the availability of research outputs such as data, code, materials, and publications. Open access provides increased reproducibility and allows for reuse of these resources. This article provides guidance for best publishing practices of scientific research, data, and associated resources, including code, in The American Phytopathological Society journals. Key areas such as diagnostic assays, experimental design, data sharing, and code deposition are explored in detail. This guidance aligns with that observed by other leading journals. We hope the information assembled in this paper will raise awareness of best practices and enable greater appraisal of the true effects of biological phenomena in plant pathology.

Field-scale gene flow of fungicide resistance in Pyrenophora teres f. teres and the effect of selection pressure on the population structure.

The effectiveness of fungicides to control foliar fungal crop diseases is being diminished by the increasing spread of resistances to fungicides. One approach that may help to maintain efficacy is remediation of resistant populations by sensitive ones. However, the success of such approaches can be compromised by re-incursion of resistance through aerial spore dispersal; although, knowledge of localized gene flow is lacking. Here, we report on a replicated mark-release-recapture field experiment with several treatments set up to study spore-dispersal-mediated gene flow of a mutated allele that confers demethylase inhibitor resistance in Pyrenophora teres f. teres (Ptt). Artificial inoculation of the host, barley (Hordeum vulgare), was successful across the 12-ha trial, where the introduced sensitive- and resistant-populations were, respectively, 6- and 13-fold the DNA concentration of the native Ptt population. Subsequent disease pressure remained low which hampered spread of the epidemic to such extent that gene flow was not detected at, or beyond 2.5 m from source points. In the absence of gene flow, plots were assessed for treatment effects; fungicide applied to populations that contained 14.3% of allele mutation increased in frequency to 24.5%, whereas sensitive populations had no change in structure. Untreated controls of native Ptt population remained genetically stable, yet untreated controls that were inoculated with sensitive Ptt had half the resistance frequency of the native population structure. The trial demonstrates the potential for management to remediate fungicide resistant pathogen populations, where localized gene flow is minimal; to safeguard chemical crop protection into the future.

New Genotypes of Phytophthora nicotianae Found on Strawberry in Florida.

Phytophthora cactorum is the most common causal agent of Phytophthora crown rot and leather rot of strawberry, but P. nicotianae is also responsible for the disease in Florida. Studies of P. nicotianae populations have suggested that different groups of genotypes are associated with different hosts; however, it is not yet clear how many lineages exist globally and how they are related to different production systems. The aim of this study was to determine the genetic relationships of P. nicotianae isolates from Florida strawberry with genotypes reported from other hosts, quantify the genetic variation on strawberry, and test for an association with nursery source. A total of 49 isolates of P. nicotianae were collected from strawberry plants originating from multiple nursery sources during six seasons of commercial fruit production in Florida. Microsatellite genotyping identified 28 multilocus genotypes on strawberry that were distinct among 208 isolates originating from various hosts and locations. Based on STRUCTURE analysis, two genetic groups were identified: one consisting of isolates from strawberry, and the other comprising samples from different hosts. Multilocus genotypes were shared among nursery sources, and populations defined by nursery were not differentiated. Both mating types were found among the isolates from North Carolina- and California-origin plants and in most strawberry seasons; however, a predominance of A1 was observed, and regular sexual reproduction was not supported by the data. This study reveals a unique genetic population of P. nicotianae associated with strawberry and emphasizes the vital role of nursery monitoring in mitigating disease spread.

Population Structure and Reproductive Biology of Monilinia vaccinii-corymbosi in Vaccinium angustifolium in Maine.

The fungus Monilinia vaccinii-corymbosi (Mvc) causes mummy berry disease in blueberries including lowbush blueberry, Vaccinium angustifolium, and is a significant pathogen of concern for Maine lowbush blueberry growers. This disease is typically managed with fungicides or by burning of plant debris containing overwintering pseudosclerotia. The population structure of Mvc in various fields in Maine was investigated using microsatellites and isolates collected from three stages in the Mvc lifecycle. The impacts of management strategies were also examined. A high level of genetic diversity was observed in Mvc from 12 lowbush blueberry fields with 199 unique multilocus haplotypes (MLHs) occurring in an original sample of 232 isolates. Twelve private alleles, including six private alleles with frequencies above 0.05, which indicated gene flow, were observed in six out of 12 fields. The population of Mvc in Maine as a whole is mostly a sexual, outcrossing population, as was seen in the diversity of MLHs and low amounts of linkage disequilibrium, although some apothecia appear to result from selfing. Three fields appear to have some clonal reproduction but were not strictly clonal, as multiple MLHs were noted in these fields. Management does not appear to affect population structure, and Mvc may be one large statewide population in Maine.

Patterns, sources, and consequences of variation in age-specific vital rates: Insights from a long-term study of Weddell seals.

Variations in the reproductive and survival abilities of individuals within a population are ubiquitous in nature, key to individual fitness, and affect population dynamics, which leads to strong interest in understanding causes and consequences of vital-rate variation. For long-lived species, long-term studies of large samples of known-age individuals are ideal for evaluating vital-rate variation. A population of Weddell seals in Erebus Bay, Antarctica, has been studied each Austral spring since the 1960s. Since 1982, all newborns have been tagged each year and multiple capture-mark-recapture (CMR) surveys have been conducted annually. Over the past 20 years, a series of analyses have built on results of earlier research by taking advantage of steady improvements in the project's long-term CMR data and available analytical methods. Here, I summarize progress made on four major topics related to variation in age-specific vital rates for females: early-life survival and age at first reproduction, costs of reproduction, demographic buffering, and demographic senescence. Multistate modelling found that age at first reproduction varies widely (4-14 years of age) and identified contrasting influences of maternal age on survival and recruitment rates of offspring. Subsequent analyses of data for females after recruitment revealed costs of reproduction to both survival and future reproduction and provided strong evidence of demographic buffering. Recent results indicated that important levels of among-individual variation exist in vital rates and revealed contrasting patterns for senescence in reproduction and survival. Sources of variation in vital rates include age, reproductive state, year, and individual. The combination of luck and individual quality results in strong variation in individual fitness outcomes: ~80% of females born in the population produce no offspring, and the remaining 20% vary strongly in lifetime reproductive output (range: 1-23 pups). Further research is needed to identify the specific environmental conditions that lead to annual variation in vital rates and to better understand the origins of individual heterogeneity. Work is also needed to better quantify the relative roles of luck, maternal effects, and environmental conditions on variation in vital rates and to learn the importance of such variation to demographic performance of offspring and on overall population dynamics.

Same species, different population dynamics: Spatio-temporal differences of Undaria pinnatifida (Ochrophyta, Phaeophyceae) in the intertidal of North Patagonia, Argentina.

Population dynamics can be influenced by physical and biological factors, particularly in stressful environments. Introduced species usually have great physiological plasticity, resulting in populations with different traits. Undaria pinnatifida, a macroalga originally described from northeast Asia, was introduced in Northern Patagonia, Argentina (San Matías Gulf) around 2010. To describe the spatio-temporal variability in population structure and morphometry of U. pinnatifida, we conducted monthly field samplings for 2 years at the intertidal area of two contrasting sites in the San Matías Gulf. Individuals of U. pinnatifida were classified by developmental stage, and their morpho-gravimetric variables were measured. In both intertidal sites juveniles were found in higher proportion during austral autumn and grew and matured during the autumn-winter months (from May onwards), and individuals senesced during early austral summer (December and January). Conversely, density and biomass were largely different between sites, and individuals showed slight morphological variability between sites. Environmental (e.g., nutrient concentration, available substrate) and biological factors (e.g., facilitation, competition) may explain the observed differences. Since there is not a macroalga with U. pinnatifida morphometrical characteristics in the intertidal environments of San Matías Gulf, studying this recent introduction gives us a better understanding of its potential ecological effects.

A Compartmental Model for Xylella fastidiosa Diseases with Explicit Vector Seasonal Dynamics.

The bacterium Xylella fastidiosa is mainly transmitted by the meadow spittlebug Philaenus spumarius in Europe, where it has caused significant economic damage to olive and almond trees. Understanding the factors that determine disease dynamics in pathosystems that share similarities can help to design control strategies focused on minimizing transmission chains. Here, we introduce a compartmental model for X. fastidiosa-caused diseases in Europe that accounts for the main relevant epidemiological processes, including the seasonal dynamics of P. spumarius. The model was confronted with epidemiological data from the two major outbreaks of X. fastidiosa in Europe, the olive quick disease syndrome in Apulia, Italy, caused by the subspecies pauca, and the almond leaf scorch disease in Mallorca, Spain, caused by subspecies multiplex and fastidiosa. Using a Bayesian inference framework, we show how the model successfully reproduces the general field data in both diseases. In a global sensitivity analysis, the vector-to-plant and plant-to-vector transmission rates, together with the vector removal rate, were the most influential parameters in determining the time of the infectious host population peak, the incidence peak, and the final number of dead hosts. We also used our model to check different vector-based control strategies, showing that a joint strategy focused on increasing the rate of vector removal while lowering the number of annual newborn vectors is optimal for disease control. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Genome Sequence Data Reveal at Least Two Distinct Incursions of the Tropical Race 4 Variant of Fusarium Wilt into South America.

The global banana industry is threatened by one of the most devastating diseases: Fusarium wilt of banana. Fusarium wilt of banana is caused by the soilborne fungus Fusarium oxysporum f. sp. cubense (Foc), which almost annihilated the banana production in the late 1950s. A new strain of Foc, known as tropical race 4 (TR4), attacks a wide range of banana varieties, including Cavendish clones, which are the source of 99% of banana exports. In 2019, Foc TR4 was reported in Colombia, and more recently (2021) in Peru. In this study, we sequenced three fungal isolates identified as Foc TR4 from La Guajira (Colombia) and compared them against 19 whole-genome sequences of Foc TR4 publicly available, including four genome sequences recently released from Peru. To understand the genetic relatedness of the Colombian Foc TR4 isolates and those from Peru, we conducted a phylogenetic analysis based on a genome-wide set of single nucleotide polymorphisms (SNPs). Additionally, we compared the genomes of the 22 available Foc TR4 isolates, looking for the presence-absence of gene polymorphisms and genomic regions. Our results reveal that (i) the Colombian and Peruvian isolates are genetically distant, which could be better explained by independent incursions of the pathogen to the continent, and (ii) there is a high correspondence between the genetic relatedness and geographic origin of Foc TR4. The profile of present/absent genes and the distribution of missing genomic regions showed a high correspondence to the clades recovered in the phylogenetic analysis, supporting the results obtained by SNP-based phylogeny.

Complete Circularized Genome Resources of Seven Strains of Xylella fastidiosa subsp. fastidiosa Using Hybrid Assembly Reveals Unknown Plasmids.

Xylella fastidiosa is a vascular plant pathogenic bacterium native to the Americas that is causing significant epidemics and economic losses in olive and almonds in Europe, where it is a quarantine pathogen. Since its first detection in 2013 in Italy, mandatory surveys across Europe revealed the presence of the bacterium also in France, Spain, and Portugal. Combining Oxford Nanopore Technologies and Illumina sequencing data, we assembled high-quality complete genomes of seven X. fastidiosa subsp. fastidiosa strains isolated from different plants in Spain, the United States, and Mexico. Comparative genomic analyses discovered differences in plasmid content among strains, including plasmids that had been overlooked previously when using the Illumina sequencing platform alone. Interestingly, in strain CFBP8073, intercepted in France from plants imported from Mexico, three plasmids were identified, including two (plasmids pXF-P1.CFBP8073 and pXF-P2.CFBP8073) not previously described in X. fastidiosa and one (pXF5823.CFBP8073) almost identical to a plasmid described in a X. fastidiosa strain from citrus. Plasmids found in the Spanish strains here were similar to those described previously in other strains from the same subspecies and ST1 isolated in the Balearic Islands and the United States. The genome resources from this work will assist in further studies on the role of plasmids in the epidemiology, ecology, and evolution of this plant pathogen.

Genome-wide association study of fungicide sensitivity in a Fusarium graminearum population collected from North Dakota.

Fusarium head blight (FHB) is a destructive disease of small grains. The disease is predominantly caused by the haploid ascomycete fungus Fusarium graminearum in North America. To understand the genetics of quantitative traits for sensitivity to fungicides in this fungal pathogen, we conducted a genome-wide association study (GWAS) of sensitivity to two demethylation inhibition (DMI) class fungicides, tebuconazole and prothioconazole, using a F. graminearum population of 183 isolates collected between 1981 and 2013 from North Dakota. Baseline sensitivity to tebuconazole and prothioconazole was established using 21 isolates collected between 1981 and 1994. Most fungal isolates were sensitive to both tebuconazole and prothioconazole, however, five isolates showed significantly reduced sensitivity to prothioconazole. GWAS identified one significant marker-trait association (MTA) on chromosome 3 for tebuconazole resistance while six significant MTAs, one on chromosome 1, three on chromosome 2, and two on chromosome 4, were detected for prothioconazole resistance. Functional annotation of the MTA for tebuconazole revealed a candidate gene encoding a basic helix loop helix (bHLH) domain containing protein that reinforces sterol in the fungal membrane. Putative genes for prothioconazole resistance were also identified, which are involved in RNAi, detoxification by ubiquitin-proteasome pathway, and membrane integrity reinforcement. Considering the potential of the pathogen towards overcoming chemical control, continued monitoring of fungal sensitivities to commercially applied fungicides, especially those containing prothioconazole, is warranted to reduce risks of fungicide resistance in the pathogen populations.

Optimal Resistance Management for Mixtures of High-Risk Fungicides: Robustness to the Initial Frequency of Resistance and Pathogen Sexual Reproduction.

There is a strong consensus that selection for fungicide resistant pathogen strains can be most effectively limited by using applications of mixtures of fungicides designed to balance disease control against selection. However, how to do this in practice is not entirely characterized. Previous work indicates optimal mixtures of pairs of fungicides which are both at a high risk of resistance can be constructed using pairs of doses that select equally for both single resistant strains in the first year of application. What has not been addressed thus far is the important real-world case in which the initial levels of resistance to each fungicide differ, for example because the chemicals have been available for different lengths of time. We show how recommendations based on equal selection in the first year can be suboptimal in this case. We introduce a simple alternative approach, based on equalizing the frequencies of single resistant strains in the year that achieving acceptable levels of control is predicted to become impossible. We show that this strategy is robust to changes in parameters controlling pathogen epidemiology and fungicide efficacy. We develop our recommendation using a preexisting, parameterized model of Zymoseptoria tritici (the pathogen causing Septoria leaf blotch on wheat), which exemplifies the range of plant pathogens that predominantly spread clonally, but for which sexual reproduction forms an important component of the life cycle. We show that pathogen sexual reproduction can influence the rate at which fungicide resistance develops but does not qualitatively affect our optimal resistance management recommendation. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Surnames in south-eastern France: structure of the rural population during the 19th century through isonymy.

An analysis of the distribution of surnames through time and space allows us to understand the structure of human groups, their exchanges or even their possible isolation. The French population has already been studied through surnames and it has been shown that the Sud-Provence-Alpes-Côte d'Azur region differed from the rest of France in both the 20th and 21st centuries (Mourrieras et al., ; Scapoli et al., ). The objective of this study was to understand the population evolution and particularities of the Sud-Provence-Alpes-Côte d'Azur region through an analysis of the distribution of surnames over an earlier period: the 19th century. For this work, 806,069 birth records from 521 communes between 1810 and 1890 were recorded and a total of 23,340 surnames were collected. The estimation of various isonymic parameters has allowed a description of this corpus never exploited before. In order to appreciate the population evolution, the data set was divided into three periods of 25 years. The canton was the geographical unit of this study, and similarities and differences between each of them were evaluated using Lasker distances, which allow the construction of dendrograms. A positive and significant correlation (p<0.0001) was found between Lasker distances and geographical distances using the Mantel test. The lowest inbreeding estimates were found in the Durance Valley. Migration, estimated from the v-index of Karlin and McGregor (), showed higher values in the south-western quarter of the region. The decrease in Rst values across the three periods is consistent with a homogenization of the patronymic between the cantons. This three-period approach showed a population evolution influenced by linguistic, cultural, historical and migratory phenomena since the Middle Ages, disrupted by the socioeconomic changes of the 19th century.

Parental background and daughters' and sons' educational outcomes - application of the Trivers-Willard hypothesis.

This study uses Trivers-Willard hypothesis to explain the differences in daughters' and sons' educational outcomes by parental background. According to the Trivers-Willard hypothesis (TWH), parental support and investments for sons and daughters display an asymmetrical relationship according to parental status because of the different reproductive advantage of the sexes. It predicts that high-status parents support sons more than daughters, and low-status parents support daughters more than sons. In modern societies, where education is the most important mediator of status, the TW hypothesis predicts that sons from high-status families will achieve higher educational outcomes than daughters. Using cohorts born between 1987 and 1997 from the reliable full population Finnish register data that contain the data of over 600.000 individuals, children's educational outcomes were measured using data on school dropout rate, academic grade point average (GPA), and general secondary enrollment in their adolescence. OLS and sibling fixed-effect regression that permitted an examination of opposite-sex siblings' educational outcomes within the same family were applied. Sons with high family income and parental education, compared to daughters of the same family, have lower probability of dropping out of school and are more likely to enroll into academic secondary school track. In families with low parental education or income daughters have lower probability for school dropout and enroll more likely to academic school track related to sons of the same family. The effect of family background by sex can be interpreted to support TWH in dropout and academic school track enrollment but not in GPA.

An Improved Assembly of the Albugo candida Ac2V Genome Reveals the Expansion of the "CCG" Class of Effectors.

Albugo candida is an obligate oomycete pathogen that infects many plants in the Brassicaceae family. We resequenced the genome of isolate Ac2V using PacBio long reads and constructed an assembly augmented by Illumina reads. The Ac2VPB genome assembly is 10% larger and more contiguous compared with a previous version. Our annotation of the new assembly, aided by RNA-sequencing information, revealed a 175% expansion (40 to 110) in the CHxC effector class, which we redefined as "CCG" based on motif analysis. This class of effectors consist of arrays of phylogenetically related paralogs residing in gene sparse regions, and shows signatures of positive selection and presence/absence polymorphism. This work provides a resource that allows the dissection of the genomic components underlying A. candida adaptation and, particularly, the role of CCG effectors in virulence and avirulence on different hosts.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Modeling the Dynamics of Heroin and Illicit Opioid Use Disorder, Treatment, and Recovery.

Opioid use disorder (OUD) has become a serious leading health issue in the USA leading to addiction, disability, or death by overdose. Research has shown that OUD can lead to a chronic lifelong disorder with greater risk for relapse and accidental overdose deaths. While the prescription opioid epidemic is a relatively new phenomenon, illicit opioid use via heroin has been around for decades. Recently, additional illicit opioids such as fentanyl have become increasingly available and problematic. We propose a mathematical model that focuses on illicit OUD and includes a class for recovered users but allows for individuals to either remain in or relapse back to the illicit OUD class. Therefore, in our model, individuals may cycle in and out of three different classes: illicit OUD, treatment, and recovered. We additionally include a treatment function with saturation, as it has been shown there is limited accessibility to specialty treatment facilities. We used 2002-2019 SAMHSA and CDC data for the US population, scaled to a medium-sized city, to obtain parameter estimates for the specific case of heroin. We found that the overdose death rate has been increasing linearly since around 2011, likely due to the increased presence of fentanyl in the heroin supply. Extrapolation of this overdose death rate, together with the obtained parameter estimates, predict that by 2038 no endemic equilibrium will exist and the only stable equilibrium will correspond to the absence of heroin use disorder in the population. There is a range of parameter values that will give rise to a backward bifurcation above a critical saturation of treatment availability. We show this for a range of overdose death rate values, thus illustrating the critical role played by the availability of specialty treatment facilities. Sensitivity analysis consistently shows the significant role of people entering treatment on their own accord, which suggests the importance of removing two of the most prevalent SAMHSA-determined reasons that individuals do not enter treatment: financial constraints and the stigma of seeking treatment for heroin use disorder.