Phylogenetic Clustering Research Articles

Genetic diversity assessment and genome-wide association study reveal candidate genes associated with component traits in sweet potato (Ipomoea batatas (L.) Lam)

The Korean sweet potatoes were bred by various cultivars introduced from Japanese, American, Porto Rico, China, and Burundi. This issue enriched their genetic diversity but also resulted in a mixture of cultivars. For genotyping, we collected and sequenced 66 sweet potato germplasms from different localities around Korea, including 36 modern cultivars, 5 local cultivars, and 25 foreign cultivars. This identified 447.6 million trimmed reads and 324.8 million mapping reads and provided 39,424 single nucleotide polymorphisms (SNPs) markers. Phylogenetic clustering and population structure analysis distinctly classified these germplasms into 5 genetic groups, group 1, group 2, group 3, group 4, and group 5, containing 20, 15, 10, 7, and 14 accessions, respectively. Sixty-three significant SNPs were selected by genome-wide association for sugar composition-related traits (fructose, glucose, and total sugars), total starch, amylose content, and total carotenoid of the storage root. A total of 37 candidate genes encompassing these significant SNPs were identified, among which, 7 genes were annotated to involve in sugar and starch metabolism, including galactose metabolism (itf04g30630), starch and sucrose metabolism (itf03g13270, itf15g09320), carbohydrate metabolism (itf14g10250), carbohydrate and amino acid metabolism (itf12g19270), and amino sugar and nucleotide sugar metabolism (itf03g21950, itf15g04880). This results indicated that sugar and starch are important characteristics to determine the genetic diversity of sweet potatoes. These findings not only illustrate the importance of component traits to genotyping sweet potatoes but also explain an important reason resulting in genetic diversity of sweet potato.

Characterization of Shigella flexneri Serotype 6 Strains Isolated from Bangladesh and Identification of a New Phylogenetic Cluster.

A significant cause of shigellosis in Bangladesh and other developing countries is Shigella flexneri serotype 6. This serotype has been subtyped, on the basis of the absence or presence of a group-specific antigen, E1037, into S. flexneri 6a and 6b, respectively. Here, we provided rationales for the subclassification, using several phenotypic and molecular tools. A set of S. flexneri 6a and 6b strains isolated between 1997 and 2015 were characterized by analyzing their biochemical properties, plasmid profiles, virulence markers, pulsed-field gel electrophoresis (PFGE) results, and ribotype. Additionally, the genomic relatedness of these subserotypes was investigated with global isolates of serotype 6 using publicly available genomes. Both subserotypes of S. flexneri 6 agglutinated with monoclonal antiserum against S. flexneri (MASF) B and type VI-specific antiserum (MASF VI) and were PCR positive for O-antigen flippase-specific genes and virulence markers (ipaH, ial, sen, and sigA). Unlike S. flexneri 6a strains, S. flexneri 6b strains seroagglutinated with anti-E1037 antibodies, MASF IV-I. Notably, these two antigenically distinct subserotypes were clonally diverse, showing two distinct PFGE patterns following the digestion of chromosomal DNA with either XbaI or IceuI. In addition, hybridization of a 16S rRNA gene probe with HindIII-digested genomic DNA yielded two distinguishing ribotypes. Genomic comparison of S. flexneri subserotype 6a and 6b strains from Bangladesh indicated that, although these strains were in genomic synteny, the majority of them formed a unique phylogroup (PG-4) that was missing for the global isolates. This study supports the subserotyping and emphasizes the need for global monitoring of the S. flexneri subserotypes 6a and 6b. IMPORTANCE Shigella flexneri serotype 6 is one of the predominant serotypes among shigellosis cases in Bangladesh. Characterization of a novel subserotype of S. flexneri 6 (VI:E1037), agglutinated with type 6-specific antibody and anti-E1037, indicates a unique evolutionary ancestry. PFGE genotyping supports the finding that these two antigenically distinct subserotypes are clonally diverse. A phylogenetic study based on single-nucleotide polymorphism (SNP) data revealed that these two subserotypes were in genomic synteny, although their genomes were reduced. Interestingly, a majority of the S. flexneri 6 strains isolated from Bangladesh form a novel phylogenetic cluster. Therefore, this report underpins the global monitoring and tracking of the novel subserotype.

A food poisoning caused by ST7 Staphylococcal aureus harboring sea gene in Hainan province, China.

ST7 Staphylococcus aureus is highly prevalent in humans, pigs, as well as food in China; however, staphylococcal food poisoning (SFP) caused by this ST type has rarely been reported. On May 13, 2017, an SFP outbreak caused by ST7 S. aureus strains occurred in two campuses of a kindergarten in Hainan Province, China. We investigated the genomic characteristics and phylogenetic analysis of ST7 SFP strains combined with the 91 ST7 food-borne strains from 12 provinces in China by performing whole-genome sequencing (WGS). There was clear phylogenetic clustering of seven SFP isolates. Six antibiotic genes including blaZ, ANT (4')-Ib, tetK, lnuA, norA, and lmrS were present in all SFP strains and also showed a higher prevalence rate in 91 food-borne strains. A multiple resistance plasmid pDC53285 was present in SFP strain DC53285. Among 27 enterotoxin genes, only sea and selx were found in all SFP strains. A ФSa3int prophage containing type A immune evasion cluster (sea, scn, sak, and chp) was identified in SFP strain. In conclusion, we concluded that this SFP event was caused by the contamination of cakes with ST7 S. aureus. This study indicated the potential risk of new emergencing ST7 clone for SFP.

What drives phylogenetic and trait clustering on islands?

Environmental filtering is an important assembly process that structures plant communities and is commonly inferred from taxonomic, functional trait and phylogenetic patterns. However, while these approaches can be informative, the influence of other co-occurring processes on community diversity, such as competitive exclusion, remains poorly understood. By combing functional traits and a phylogeny of woody plants across anthropogenically created islands, we aim to explore the ways in which environmental filtering and competitive exclusion can simultaneously influence community assembly processes. We expect that communities on smaller islands, where competition for limited space and resources is more intense, should be functionally and phylogenetically less clustered than those on larger islands because this more intense competition should reduce the coexistence of the most closely related or functionally similar species. We used ten functional traits and a phylogeny of 76 woody plant species to assess species diversity and similarity within communities across an island area gradient. We combed functional traits and phylogeny into a functional–phylogenetic distance matrix and calculated the communities’ mean functional-phylogenetic distance (MFPD) and its standardized effect size (SES.MFPD) as measures of ecological similarity. As expected, species were more phylo-functionally similar to one another than expected by chance within islands and this underdispersion grew stronger with island area, indicating that while islands generally contained clustered communities, environmental filtering and competitive exclusion were both likely occurring. By integrating species abundance distributions with community similarity, we found that the most abundant species were phylo-functionally similar to the least abundant species. Species richness increased with island area, as expected, but the additional species found only on larger islands tended to have low abundances, providing opportunities for rare species to persist. With environmental filtering narrowing the number of species that can persist, the loss of phylo-functionally closely related rare species on smaller islands was likely caused by competition or stochastic removals, leading to greater species dissimilarity than on larger islands. On larger islands, the clustered patterns are likely to be the result of a combination of competitive exclusion caused by resource limitation and environmental filtering.

Historical and contemporary processes drive global phylogenetic structure across geographical scales: Insights from bat communities

AbstractAimPatterns of evolutionary relatedness among co‐occurring species are driven by scale‐dependent contemporary and historical processes. Yet, we still lack a detailed understanding of how these drivers impact the phylogenetic structure of biological communities. Here, we focused on bats (one of the most species‐rich and vagile groups of mammals) and tested the predictions of three general biogeographical hypotheses that are particularly relevant to understanding how palaeoclimatic stability, local diversification rates and geographical scales shaped their present‐day phylogenetic community structure.LocationWorld‐wide, across restrictive geographical extents: global, east–west hemispheres, biogeographical realms, tectonic plates, biomes and ecoregions.Time periodLast Glacial Maximum (~22,000 years ago) to the present.Major taxa studiedBats (Chiroptera).MethodsWe estimated bat phylogenetic community structure across restrictive geographical extents and modelled it as a function of palaeoclimatic stability andin situnet diversification rates.ResultsLimiting geographical extents from larger to smaller scales greatly changed the phylogenetic structure of bat communities. The magnitude of these effects is less noticeable in the western hemisphere, where frequent among‐realm biota interchange could have been maintained through the adaptive traits of bats. Bat communities with high phylogenetic relatedness are generally more common in regions that have changed less in climate since the Last Glacial Maximum, supporting the expectation that stable climates allow for increased phylogenetic clustering. Finally, increasedin situnet diversification rates are associated with greater phylogenetic clustering in bat communities.Main conclusionsWe show that the world‐wide phylogenetic structure of bat assemblages varies as a function of geographical extents, dispersal barriers, palaeoclimatic stability andin situdiversification. The integrative framework used in our study, which can be applied to other taxonomic groups, has not only proved useful to explain the evolutionary dynamics of community assembly, but could also help to tackle questions related to scale dependence in community ecology and biogeography.

Mutational analysis of catalytic site domain of CCHFV L RNA segment

Crimean-Congo haemorrhagic fever virus (CCHFV) has tripartite RNA genome and is endemic in various countries of Asia, Africa and Europe. The present study is focused on mutation profiling of CCHFV L segment and phylogenetic clustering of protein dataset into six CCHFV genotypes. Phylogenetic tree rooted with NCBI reference sequence (YP_325663.1) indicated less divergence from genotype III and the sequences belonging to same genotypes have shown less divergence among each other. Mutation frequency at 729 mutated positions was calculated and 563, 49, 33, 46 and 38 amino acid positions were found to be mutated at mutation frequency intervals of 0-0.2, 0.21-0.4, 0.41-0.6, 0.61-0.8 and 0.81-1.0 respectively. Thirty-eight highly frequent mutations (0.81-1.0 interval) were found in all genotypes and mapping in L segment (encoded for RdRp) revealed four mutations (V2074I, I2134T/A, V2148A and Q2695H/R) in catalytic site domain and no mutation in OTU domain. Molecular dynamic simulation and in silico analysis showed that catalytic site domain displayed large deviation and fluctuation upon introduction of these point mutations. Overall study provides strong evidence that OTU domain is highly conserved and less prone to mutation whereas point mutations recorded in catalytic domain have affected the stability of protein and were found to be persistent in the large population.

Assessment of the Diversity, Distinctiveness and Conservation of Australia’s Central Queensland Coastal Rainforests Using DNA Barcoding

Globally threatened dry rainforests are poorly studied and conserved when compared to mesic rainforests. Investigations of dry rainforest communities within Australia are no exception. We assessed the community diversity, distinctiveness and level of conservation in Central Queensland coastal dry rainforest communities. Our three-marker DNA barcode-based phylogeny, based on rainforest species from the Central Queensland Coast, was combined with the phylogeny from Southeast Queensland. The phylogenetic tree and Central Queensland Coast (CQC) community species lists were used to evaluate phylogenetic diversity (PD) estimates and species composition to pinpoint regions of significant rainforest biodiversity. We evaluated the patterns and relationships between rainforest communities of the biogeographical areas of Central Queensland Coast and Southeast Queensland, and within and between Subregions. Subsequently, we identified areas of the highest distinctiveness and diversity in phylogenetically even rainforest communities, consistent with refugia, and areas significantly more related than random, consistent with expansion into disturbed or harsher areas. We found clear patterns of phylogenetic clustering that suggest that selection pressures for moisture and geology were strong drivers of rainforest distribution and species diversity. These results showed that smaller dry rainforests in Central Queensland Coast (CQC) represented areas of regional plant migration but were inadequately protected. To sustain species diversity and distribution under intense selection pressures of moisture availability and substrate type throughout this dry and geologically complex region, the future conservation of smaller patches is essential.

Local environment drives rapid shifts in composition and phylogenetic clustering of seagrass microbiomes

Plant microbiomes depend on environmental conditions, stochasticity, host species, and genotype identity. Eelgrass (Zostera marina) is a unique system for plant–microbe interactions as a marine angiosperm growing in a physiologically-challenging environment with anoxic sediment, periodic exposure to air at low tide, and fluctuations in water clarity and flow. We tested the influence of host origin versus environment on eelgrass microbiome composition by transplanting 768 plants among four sites within Bodega Harbor, CA. Over three months following transplantation, we sampled microbial communities monthly on leaves and roots and sequenced the V4–V5 region of the 16S rRNA gene to assess community composition. The main driver of leaf and root microbiome composition was destination site; more modest effects of host origin site did not last longer than one month. Community phylogenetic analyses suggested that environmental filtering structures these communities, but the strength and nature of this filtering varies among sites and over time and roots and leaves show opposing gradients in clustering along a temperature gradient. We demonstrate that local environmental differences create rapid shifts in associated microbial community composition with potential functional implications for rapid host acclimation under shifting environmental conditions.

The structure of associations: Method insights from analyzing 28 clinical isolates of Cryptococcus neoformans.

Clinical isolates of a fungal pathogen from a single region or country often exhibit structural clonality or phylogenetic clustering at the sequence or MLST level; such population structure can persist also in larger samples. In efforts to improve causal understanding of pathogenesis at the molecular level, genome-wide association screening methods initially designed for other kingdoms have been applied to fungi. The example of a Colombian dataset of 28 clinical Cryptococcus neoformans VNI isolates indicates where the output from standard pipelines may need to be analyzed in new ways in order to efficiently extract hypotheses for experiments from fungal genotype-phenotype data.

Stronger linkage of diversity-carbon decomposition for rare rather than abundant bacteria in woodland soils

Soil microbial diversity is important for maintaining ecosystem functions. However, the linkage between microbial diversity, especially rare and abundant bacterial diversity, and carbon decomposition remains largely unknown. In this study, we assessed the establishment and maintenance of rare and abundant bacterial α-diversities at the taxonomic and phylogenetic levels and their linkages with soil carbon decomposition separately in four Chinese woodlands. Compared to abundant bacteria, rare bacteria showed higher community diversity, tighter phylogenetic clustering, wider environmental breadth, stronger phylogenetic signals, and higher functional redundancy. The assembly of the abundant bacterial subcommunity was governed by stochastic (59.2%) and deterministic (41.8%) processes, whereas the assembly of the rare bacterial subcommunity was mainly dominated by deterministic processes (85.8%). Furthermore, total phosphorus, soil pH, and ammonium nitrogen balanced stochastic and deterministic processes in both rare and abundant bacterial subcommunities. Our results reveal that rare bacteria displayed stronger environmental adaptability and environmental constraint. Importantly, the α-diversities of rare taxa, rather than abundant taxa, were significantly related to carbon decomposition. This study provides a holistic understanding of biogeographic patterns of abundant and rare bacteria and their α-diversities in relation to carbon decomposition, thus helping us better predict and regulate carbon dynamics under the background of global climate change.

Origin and evolution of subtype B variants in the former Soviet Union countries.

Contrary to the global trend, between 2010 and 2020, an increase of 43% new HIV infections was recorded in Eastern Europe and Central Asia. Analyses of phylogenetic relationship, and routes and modes of transmission of the HIV-1 subtype B across the former Soviet Union (FSU) region are currently lacking. The objective of this analysis was to investigate the origin and transmission routes of HIV subtype B in FSU countries. We performed phylogenetic and phylodynamic analyses using 21,007 publicly available subtype B sequences from Europe and Asia, including thirteen FSU countries. Our study suggests that BFSU strain evolved more recently in FSU countries (Russia, Kyrgyzstan, Uzbekistan, Tajikistan, Belarus, Ukraine, Lithuania, Latvia, Georgia, Armenia, Azerbaijan) compared to the Western B variant in Western Europe (Austria, Belgium, Germany, Luxembourg, Netherlands, Switzerland). The primary high-risk group responsible for the transmission of subtype B was found to be MSM/homosexual. Intermixing of phylogenetic clusters among high-risk groups and bridging with the general population indicated that the HIV epidemic is no longer confined to distinct key populations - emphasizing an urgent need to improve the HIV harm-reduction efforts among high risk as well as general populations.

Imprints of historical and ecological factors in the phylogenetic structure of Australian Meliphagides assemblages

AbstractAimsUnderstanding how historical and ecological (species interactions) factors affect species and shape community structure is a fundamental goal in ecology. However, these two components are difficult to disentangle and are often confounded. We address the influence of these factors in governing the structure of bird assemblages.LocationSoutheastern Australia.TaxonThe Meliphagoidea superfamily.MethodsBy adopting a semi‐experimental approach (i.e. high vs low interference competition), we examine the influence of a genus (Manorina) of honeyeater species that is well known for its hyper‐aggressiveness and strong competitive capacity on the phylogenetic and functional structure of local assemblages across three different habitats (eucalypt woodlands, mallee and cleared habitat). We applied a model that explicitly incorporates the effects of neutral colonization and local extinction in shaping community structure and estimated the contributions of niche‐based and neutral processes to community assembly using the STEPCAM technique.ResultsCommunities with the presence of Manorina species were characterized by faster rates of colonization and local extinction and exhibited a higher degree of phylogenetic clustering than communities without these despotic species, which suggests that this model not only mirrors habitat preferences, but also unintendedly accounts for the effect of biotic interactions. Stochastic processes had a lower contribution in the presence of Manorina species, whereas the role of filtering tended to be higher. We observed habitat differences in terms of functional (but not phylogenetic) structure, with more functionally clustered assemblages in the cleared habitat.Main ConclusionsAlthough recent studies have suggested that neutral‐species processes are sufficient to explain local assemblage phylogenetic structure, our capacity to isolate them from contemporary ecological processes is still limited. This study also reinforces the idea that biotic interactions can also lead to patterns of underdispersion and thus, assumptions behind null model approaches for community assembly should be carefully considered in each case.

A new hypercarnivorous hyaenodont from the Eocene of South China

A new hyaenodont Maocyon peregrinus, gen. et sp. nov., is described based on a partial skull and associated mandible from the upper Eocene Youganwo Formation at Maoming locality in Guangdong Province, China. It shows certain similarities with the Hyainailouroidea in the skull structure, including anteroposteriorly extended jugal/squamosal suture, presence of a preglenoid crest, a lateral expansion of the squamosal posterior to the zygomatic arch, a transversally expanded mastoid process, a nuchal crest that does not extend laterally to mastoid process, and large occipital condyles. The phylogenetic analysis clusters the new taxon with Orienspterodon dahkoensis from the late middle Eocene of China and Myanmar and places this clade within the Hyainailouridae in a polytomy with the Apternodontinae and the Hyainailourinae.

Evolutionary History of the Poecilia picta Sex Chromosomes.

The degree of divergence between the sex chromosomes is not always proportional to their age. In poeciliids, four closely related species all exhibit a male heterogametic sex chromosome system on the same linkage group, yet show a remarkable diversity in X and Y divergence. In Poecilia reticulata and P. wingei, the sex chromosomes remain homomorphic, yet P. picta and P. parae have a highly degraded Y chromosome. To test alternative theories about the origin of their sex chromosomes, we used a combination of pedigrees and RNA-seq data from P. picta families in conjunction with DNA-seq data collected from P. reticulata, P. wingei, P. parae, and P. picta. Phylogenetic clustering analysis of X and Y orthologs, identified through segregation patterns, and their orthologous sequences in closely related species demonstrates a similar time of origin for both the P. picta and P. reticulata sex chromosomes. We next used k-mer analysis to identify shared ancestral Y sequence across all four species, suggesting a single origin to the sex chromosome system in this group. Together, our results provide key insights into the origin and evolution of the poeciliid Y chromosome and illustrate that the rate of sex chromosome divergence is often highly heterogenous, even over relatively short evolutionary time frames.

Expanding epidemic of recently acquired HCV in HIV-coinfected patients over a period of 10 years

Ongoing transmission of HCV infections is associated with risk factors such as drug injection, needlestick injuries, and men who have sex with men (MSM). Ways of transmission, the course of acute infection, changes of virologic features, and incidence over time are not well known. Over a period of 10 years, n= 161 patients with recently acquired HCV infection (RAHC) (median follow-up 6.8 years) were prospectively enrolled. NS5B sequencing was performed to re-evaluate the HCV genotype (GT) and for phylogenetic analyses. Patients with RAHC were mainly male (92.5%), MSM (90.1%), and HIV-coinfected (86.3%). Transmission risk factors for MSM and non-MSM were sexual risk behaviour (100 and 6.3%, respectively), injection drug use (9.7 and 37.5%, respectively), and nasal drug use (15.2 and 0%, respectively). Spontaneous and interferon- or direct-acting antiviral-based clearance rates were 13.6, 84.3 and 93.4%, respectively. Mean RAHC declined from 19.8 in the first to 13.2 in the past five study years. Although the majority of infections was caused by HCV GT1a, the frequency of HCV GT4d and slightly HCV GT3a increased over time. No relevant clustering of HCV isolates was observed in non-MSM. However, 45% of HCV GT1a and 100% of HCV GT4d MSM cases clustered with MSM isolates from other countries. Travel-associated infections were supported by personal data in an MSM subgroup. No international clustering was detected in MSM with HCV GT1b or HCV GT3a. RAHCs were mainly diagnosed in HIV-coinfected MSM patients and were associated with sexual risk behaviour. Spontaneous clearance rates were low, and phylogenetic clusters were observed in the majority of patients. We evaluated the occurrence and transmission of recently acquired HCV infections (RAHCs) over a period of 10 years. Our data demonstrate that the presence of RAHC was mainly found in HIV-coinfected MSM, with internationally connected transmission networks being observed in the majority of patients. Spontaneous clearance rates were low, and reinfection rates increased mainly driven by a small subset of MSM patients with high-risk behaviour.

Assessment of genetic diversity of the fat-tailed Dumba sheep of India by mitochondrial and microsatellite markers

India has a centuries-old tradition of sheep production and breeding that accomplish economic, agricultural, and religious roles. In addition to the 44 registered sheep breeds, there is a fat-tailed sheep population referred to as Dumba. This study evaluated genetic variation in Dumba sheep and its differentiation from other Indian sheep breeds using mitochondrial DNA and genomic microsatellite loci. Haplotype and nucleotide diversity based on mitochondrial DNA analysis revealed substantially high maternal genetic diversity in Dumba sheep. Major ovine haplogroups A and B observed in sheep populations across the globe registered their presence in the Dumba sheep. The molecular genetic analysis using microsatellite markers also showed high measures of allele (10.125 ± 0.762) and gene diversity (0.749 ± 0.029). Results correspond to the non-bottleneck population that is near mutation-drift equilibrium despite some deficiency in the number of heterozygotes (FIS = 0.043 ± 0.059). Phylogenetic clustering confirmed Dumba to be a distinct population. Results of this study endow authorities with critical information imperative for sustainable utilization and conservation of Indian fat-tailed sheep, which is considered to be an untapped genetic resource contributing to the food security, livelihood, and economic sustainability of rural households in marginal areas of the country.

Cloacal microbiota are biogeographically structured in larks from desert, tropical and temperate areas

BackgroundIn contrast with macroorganisms, that show well-documented biogeographical patterns in distribution associated with local adaptation of physiology, behavior and life history, strong biogeographical patterns have not been found for microorganisms, raising questions about what determines their biogeography. Thus far, large-scale biogeographical studies have focused on free-living microbes, paying little attention to host-associated microbes, which play essential roles in physiology, behavior and life history of their hosts. Investigating cloacal gut microbiota of closely-related, ecologically similar free-living songbird species (Alaudidae, larks) inhabiting desert, temperate and tropical regions, we explored influences of geographical location and host species on α-diversity, co-occurrence of amplicon sequence variants (ASVs) and genera, differentially abundant and dominant bacterial taxa, and community composition. We also investigated how geographical distance explained differences in gut microbial community composition among larks.ResultsGeographic location did not explain variation in richness and Shannon diversity of cloacal microbiota in larks. Out of 3798 ASVs and 799 bacterial genera identified, 17 ASVs (< 0.5%) and 43 genera (5%) were shared by larks from all locations. Desert larks held fewer unique ASVs (25%) than temperate zone (31%) and tropical larks (34%). Five out of 33 detected bacterial phyla dominated lark cloacal gut microbiomes. In tropical larks three bacterial classes were overrepresented. Highlighting the distinctiveness of desert lark microbiota, the relative abundances of 52 ASVs differed among locations, which classified within three dominant and 11 low-abundance phyla. Clear and significant phylogenetic clustering in cloacal microbiota community composition (unweighted UniFrac) showed segregation with geography and host species, where microbiota of desert larks were distinct from those of tropical and temperate regions. Geographic distance was nonlinearly associated with pairwise unweighted UniFrac distances.ConclusionsWe conclude that host-associated microbiota are geographically structured in a group of widespread but closely-related bird species, following large-scale macro-ecological patterns and contrasting with previous findings for free-living microbes. Future work should further explore if and to what extent geographic variation in host-associated microbiota can be explained as result of co-evolution between gut microbes and host adaptive traits, and if and how acquisition from the environmental pool of bacteria contributes to explaining host-associated communities.

The gut microbiome–Does stool represent right?

Many stool-based gut microbiome studies have highlighted the importance of the microbiome. However, we hypothesized that stool is a poor proxy for the inner-colonic microbiome and that studying stool samples may be inadequate to capture the true inner-colonic microbiome. To test this hypothesis, we conducted prospective clinical studies with up to 20 patients undergoing an FDA-cleared gravity-fed colonic lavage without oral purgative pre-consumption. The objective of this study was to present the analysis of inner-colonic microbiota obtained non-invasively during the lavage and how these results differ from stool samples. The inner-colonic samples represented the descending, transverse, and ascending colon. All samples were analyzed for 16S rRNA and shotgun metagenomic sequences. The taxonomic, phylogenetic, and biosynthetic gene cluster analyses showed a distinctive biogeographic gradient and revealed differences between the sample types, especially in the proximal colon. The high percentage of unique information found only in the inner-colonic effluent highlights the importance of these samples and likewise the importance of collecting them using a method that can preserve these distinctive signatures. We proposed that these samples are imperative for developing future biomarkers, targeted therapeutics, and personalized medicine.

Identification of genes influencing the evolution of Escherichia coli ST372 in dogs and humans.

ST372 are widely reported as the major Escherichia coli sequence type in dogs globally. They are also a sporadic cause of extraintestinal infections in humans. Despite this, it is unknown whether ST372 strains from dogs and humans represent shared or distinct populations. Furthermore, little is known about genomic traits that might explain the prominence of ST372 in dogs or presence in humans. To address this, we applied a variety of bioinformatics analyses to a global collection of 407 ST372 E. coli whole-genome sequences to characterize their epidemiological features, population structure and associated accessory genomes. We confirm that dogs are the dominant host of ST372 and that clusters within the population structure exhibit distinctive O:H types. One phylogenetic cluster, 'cluster M', comprised almost half of the sequences and showed the divergence of two human-restricted clades that carried different O:H types to the remainder of the cluster. We also present evidence supporting transmission between dogs and humans within different clusters of the phylogeny, including M. We show that multiple acquisitions of the pdu propanediol utilization operon have occurred in clusters dominated by isolates of canine source, possibly linked to diet, whereas loss of the pdu operon and acquisition of K antigen virulence genes characterize human-restricted lineages.

Soil factors rather than stand age drive tree phylogenetic diversity along Amazon Forest succession

Understanding the phylogenetic diversity and structure of woody communities can explain how deterministic or stochastic processes drive a forest community assembly. This study assessed the tree community's phylogenetic diversity and structure during secondary succession after shifting cultivation (SC) in the Northern Amazon Forest. We hypothesized that soil-mediated filtering, rather than habitat filtering based on stand age and neutrality-based stochastic processes, determines phylogenetic diversity and structure of woody community along Amazon Forest succession after SC. We used forest inventory data from 45 plots across three sites representing second-growth forests (SG) having stand ages after shifting cultivation (e.g., 5, 10, 15, and 20 years old) and an old-growth reference forest (> 100 years old, OG). We tested different linear mixed-effects models to determine the main effects of soil-mediated filtering (i.e., nutrients and soil texture) and stand age on phylogenetic metrics. Phylogenetic diversity (PD) showed a significant difference between SG and OG: the highest PD was found in OG, whereas the lowest PD was found during the initial successional stage. We found a trend of phylogenetic structure promoted by soil attributes; the variability of soil texture mainly explained most of the variation of phylogenetic diversity and structure. Stand age did not demonstrate a significant influence on phylogenetic metrics across any of the tested models. Higher soil fertility may favor the growth of species from multiple distant clades, increasing phylogenetic diversity and reducing phylogenetic clustering. However, SC may affect the fertility content in silt soils of OG and generate soils with a high proportion of sand and low fertility in SG. Thus, our study demonstrates that soil-mediated abiotic filtering shapes the phylogenetic structure and diversity of tree communities along Amazon forest succession due to deterministic processes rather than stand age and neutrality-based stochastic processes.