Plasticity-mediated persistence and subsequent local adaptation in a global agricultural weed.

Phenotypic plasticity can alter traits that are crucial to population establishment in a new environment, before adaptation can occur. How often phenotypic plasticity enables subsequent adaptive evolution is unknown, and examples of the phenomenon are limited. We investigated the hypothesis of plasticity-mediated persistence as a means of colonization of agricultural fields in one of the world's worst weeds, Raphanus raphanistrum ssp. raphanistrum. Using non-weedy native populations of the same species and subspecies as a comparison, we tested for plasticity-mediated persistence in a growth chamber reciprocal transplant experiment. We identified traits with genetic differentiation between the weedy and native ecotypes as well as phenotypic plasticity between growth chamber environments. We found that most traits were both plastic and differentiated between ecotypes, with the majority plastic and differentiated in the same direction. This suggests that phenotypic plasticity may have enabled radish populations to colonize and then adapt to novel agricultural environments.

An updated phylogeny and adaptive evolution within Amaranthaceae s.l. inferred from multiple phylogenomic datasets.

Amaranthaceae s.l. is a widely distributed family consisting of over 170 genera and 2000 species. Previous molecular phylogenetic studies have shown that Amaranthaceae s.s. and traditional Chenopodiaceae form a monophyletic group (Amaranthaceae s.l.), however, the relationships within this evolutionary branch have yet to be fully resolved. In this study, we assembled the complete plastomes and full-length ITS of 21 Amaranthaceae s.l. individuals and compared them with 38 species of Amaranthaceae s.l. Through plastome structure and sequence alignment analysis, we identified a reverse complementary region approximately 5200 bp long in the genera Atriplex and Chenopodium. Adaptive evolution analysis revealed significant positive selection in eight genes, which likely played a driving role in the evolution of Amaranthaceae s.l., as demonstrated by partitioned evolutionary analysis. Furthermore, we found that about two-thirds of the examined species lack the ycf15 gene, potentially associated with natural selection pressures from their adapted habitats. The phylogenetic tree indicated that some genera (Chenopodium, Halogeton, and Subtr. Salsolinae) are paraphyletic lineages. Our results strongly support the clustering of Amaranthaceae s.l. with monophyletic traditional Chenopodiaceae (Clades I and II) and Amaranthaceae s.s. After a comprehensive analysis, we determined that cytonuclear conflict, gene selection by adapted habitats, and incomplete lineage sorting (ILS) events were the primary reasons for the inconsistent phylogeny of Amaranthaceae s.l. During the last glacial period, certain species within Amaranthaceae s.l. underwent adaptations to different environments and began to differentiate rapidly. Since then, these species may have experienced morphological and genetic changes distinct from those of other genera due to intense selection pressure.

Effects of thermophilic and acidophilic microbial consortia on maize wet-milling steeping.

To understand the ecology of species and promote biotechnology through beneficial strain selection for improving starch yield in maize wet-milling steeping, bacterial diversity and community structure during the counter-current steeping process in a commercial steeping system were characterized and investigated. The microbial diversity in the steeping liquor, which consisted of 16 phyla, 131 families, and 290 genera, was more abundant compared to those present on the surface of unsteeped maize. As the counter-current steeping progressed, exposing newer maize to the older steepwater, Lactobacillus dominated, replacing Rahnella, Pseudomonas, Pantoea, and Serratia. The thermophilic and acidophilic microbial consortia were enriched through adaptive evolution engineering and employed to improve starch yield. Several steeping strategies were evaluated, including water alone, SO2 alone, mono-culture of B. coagulans, microbial consortia, and a combination of consortium and SO2. Combining the microbial consortium with SO2 significantly increased the starch yield to, about 66.4 ± 0.5%, a 22% and 46% increase over SO2 alone and the consortium alone, respectively. Scanning electron microscope (SEM) of steeped maize structure indicated that the combination of consortium and SO2 disrupted the protein matrix and widened gaps between starch granules in maize endosperm. This released proteins into the steepwater and left starch granules in the aleurone layer. The steeping strategy of using thermophilic and acidophilic microbial consortium as additives shows potential application as an environmentally friendly alternative to conventional maize steeping procedures.

GPCR-MAPK signaling pathways underpin fitness trade-offs in whitefly.

Trade-offs between evolutionary gain and loss are prevalent in nature, yet their genetic basis is not well resolved. The evolution of insect resistance to insecticide is often associated with strong fitness costs; however, how the fitness trade-offs operates remains poorly understood. Here, we show that the mitogen-activated protein kinase (MAPK) pathway and its upstream and downstream actors underlie the fitness trade-offs associated with insecticide resistance in the whitefly Bemisia tabaci. Specifically, we find a key cytochrome P450 gene CYP6CM1, that confers neonicotinoids resistance to in B. tabaci, is regulated by the MAPKs p38 and ERK through their activation of the transcription factor cAMP-response element binding protein. However, phosphorylation of p38 and ERK also leads to the activation of the transcription repressor Cap "n" collar isoform C (CncC) that negatively regulates exuperantia (Ex), vasa (Va), and benign gonial cell neoplasm (Bg), key genes involved in oogenesis, leading to abnormal ovary growth and a reduction in female fecundity. We further demonstrate that the transmembrane G protein-coupled receptor (GPCR) neuropeptide FF receptor 2 (NPFF2) triggers the p38 and ERK pathways via phosphorylation. Additionally, a positive feedback loop between p38 and NPFF2 leads to the continuous activation of the MAPK pathways, thereby constitutively promoting neonicotinoids resistance but with a significant reproductive cost. Collectively, these findings provide fundamental insights into the role of cis-trans regulatory networks incurred by GPCR-MAPK signaling pathways in evolutionary trade-offs and applied knowledge that can inform the development of strategies for the sustainable pest control.

The Performance and Evolutionary Mechanism of Ganoderma lucidum in Enhancing Selenite Tolerance and Bioaccumulation.

BACKGROUND: Selenium (Se) pollution poses serious threats to terrestrial ecosystems. Mushrooms are important sources of Se with the potential for bioremediation. Pre-eminent Se resources must possess the ability to tolerate high levels of Se. To obtain Se-accumulating fungi, we isolated selenite-tolerance-enhanced Ganoderma lucidum JNUSE-200 through adaptive evolution. METHODS: The molecular mechanism responsible for selenite tolerance and accumulation was explored in G. lucidum JNUSE-200 by comparing it with the original strain, G. lucidum CGMCC 5.26, using a combination of physiological and transcriptomic approaches. RESULTS: G. lucidum JNUSE-200 demonstrated tolerance to 200 mg/kg selenite in liquid culture and exhibited normal growth, whereas G. lucidum CGMCC 5.26 experienced reduced growth, red coloration, and an unpleasant odor as a result of exposure to selenite at the same concentration. In this study, G. lucidum JNUSE-200 developed a triple defense mechanism against high-level selenite toxicity, and the key genes responsible for improved selenite tolerance were identified. CONCLUSIONS: The present study offers novel insights into the molecular responses of fungi towards selenite, providing theoretical guidance for the breeding and cultivation of Se-accumulating varieties. Moreover, it significantly enhances the capacity of the bio-manufacturing industry and contributes to the development of beneficial applications in environmental biotechnology through fungal selenite transformation bioprocesses.

Systems metabolic engineering of Escherichia coli for high-yield production of Para-hydroxybenzoic acid.

Para-hydroxybenzoic acid (PHBA) is extensively used as an additive in the food and cosmetics industries, significantly enhancing product shelf life and stability. While microbial fermentation offers an environment-friendly and sustainable method for producing PHBA, the titer and productivity are limited due to product toxicity and complex metabolic flux distributions. Here, we initially redesigned a L-phenylalanine-producing Escherichia coli by employing rational metabolic engineering strategies, resulting in the production of PHBA reached the highest reported level of 14.17 g/L. Subsequently, a novel accelerated evolution system was devised comprising deaminase, the alpha subunit of RNA polymerase, an uracil-DNA glycosylase inhibitor, and the PHBA-responsive promoter PyhcN. This system enabled us to obtain a mutant strain exhibiting a 47% increase in the half-inhibitory concentration (IC50) for PHBA within 15 days. Finally, the evolved strain achieved a production of 21.35 g/L PHBA in a 5-L fermenter, with a yield of 0.19 g/g glucose and a productivity rate of 0.44 g/L/h. This engineered strain emerges as a promising candidate for industrial production of PHBA through an eco-friendly approach.

Rapid phenotypic differentiation in the iconic Japanese knotweed s.l. invading novel habitats.

Understanding the mechanisms that underlie plant invasions is critical for management and conservation of biodiversity. At the same time, invasive species also provide a unique opportunity to study rapid adaptation to complex environmental conditions. Using four replicate reciprocal transplant experiments across three habitats, we described patterns of phenotypic response and assessed the degree of local adaptation in knotweed populations. We found plants from beach habitats were generally smaller than plants from marsh and roadside habitats when grown in their home habitat. In the marsh habitat, marsh plants were generally larger than beach plants, but not different from roadside plants. There were no differences among plants grown in the roadside habitat. We found mixed evidence for local adaptation: plants from the marsh habitat had greater biomass in their "home" sites, while plants from beaches and roadsides had greater survival in their "home" sites compared to other plants. In sum, we found phenotypic differentiation and some support for the hypothesis of rapid local adaptation of plants from beach, marsh and roadside habitats. Identifying whether these patterns of differentiation result from genetic or heritable non-genetic mechanisms will require further work.

Genomic insights into adaptation to bipedal saltation and desert-like habitats of jerboas.

Jerboas is a lineage of small rodents displaying atypical mouse-like morphology with elongated strong hindlimbs and short forelimbs. They have evolved obligate bipedal saltation and acute senses, and been well-adapted to vast desert-like habitats. Using a newly sequenced chromosome-scale genome of the Mongolian five-toed jerboa (Orientallactaga sibirica), our comparative genomic analyses and in vitro functional assays showed that the genetic innovations in both protein-coding and non-coding regions played an important role in jerboa morphological and physiological adaptation. Jerboa-specific amino acid substitutions, and segment insertions/deletions (indels) in conserved non-coding elements (CNEs) were found in components of proteoglycan biosynthesis pathway (XYLT1 and CHSY1), which plays an important role in limb development. Meanwhile, we found specific evolutionary changes functionally associated with energy or water metabolism (e.g., specific amino acid substitutions in ND5 and indels in CNEs physically near ROR2) and senses (e.g., expansion of vomeronasal receptors and the FAM136A gene family) in jerboas. Further dual-luciferase reporter assay verified that some of the CNEs with jerboa-specific segment indels exerted a significantly different influence on luciferase activity, suggesting changes in their regulatory function in jerboas. Our results revealed the potential molecular mechanisms underlying jerboa adaptation since the divergence from the Eocene-Oligocene transition, and provided more resources and new insights to enhance our understanding of the molecular basis underlying the phenotypic diversity and the environmental adaptation of mammals.

Comparative transcriptome and methylome of polar bears, giant and red pandas reveal diet-driven adaptive evolution.

Epigenetic regulation plays an important role in the evolution of species adaptations, yet little information is available on the epigenetic mechanisms underlying the adaptive evolution of bamboo-eating in both giant pandas (Ailuropoda melanoleuca) and red pandas (Ailurus fulgens). To investigate the potential contribution of epigenetic to the adaptive evolution of bamboo-eating in giant and red pandas, we performed hepatic comparative transcriptome and methylome analyses between bamboo-eating pandas and carnivorous polar bears (Ursus maritimus). We found that genes involved in carbohydrate, lipid, amino acid, and protein metabolism showed significant differences in methylation and expression levels between the two panda species and polar bears. Clustering analysis of gene expression revealed that giant pandas did not form a sister group with the more closely related polar bears, suggesting that the expression pattern of genes in livers of giant pandas and red pandas have evolved convergently driven by their similar diets. Compared to polar bears, some key genes involved in carbohydrate metabolism and biological oxidation and cholesterol synthesis showed hypomethylation and higher expression in giant and red pandas, while genes involved in fat digestion and absorption, fatty acid metabolism, lysine degradation, resistance to lipid peroxidation and detoxification showed hypermethylation and low expression. Our study elucidates the special nutrient utilization mechanism of giant pandas and red pandas and provides some insights into the molecular mechanism of their adaptive evolution of bamboo feeding. This has important implications for the breeding and conservation of giant pandas and red pandas.

Gene protein sequence evolution can predict the rapid divergence of ovariole numbers in the Drosophila melanogaster subgroup.

Ovaries play key roles in fitness and evolution: they are essential female reproductive structures that develop and house the eggs in sexually reproducing animals. In Drosophila, the mature ovary contains multiple tubular egg-producing structures known as ovarioles. Ovarioles arise from somatic cellular structures in the larval ovary called terminal filaments, formed by terminal filament cells and subsequently enclosed by sheath cells. As in many other insects, ovariole number per female varies extensively in Drosophila. At present however, there is a striking gap of information on genetic mechanisms and evolutionary forces that shape the well-documented rapid interspecies divergence of ovariole numbers. To address this gap, here we studied genes associated with D. melanogaster ovariole number or functions based on recent experimental and transcriptional datasets from larval ovaries, including terminal filaments and sheath cells, and assessed their rates and patterns of molecular evolution in five closely related species of the melanogaster subgroup that exhibit species-specific differences in ovariole numbers. From comprehensive analyses of protein sequence evolution (dN/dS), branch-site positive selection, expression specificity (tau) and phylogenetic regressions (PGLS), we report evidence of 42 genes that showed signs of playing roles in the genetic basis of interspecies evolutionary change of Drosophila ovariole number. These included the signalling genes upd2 and Ilp5 and extracellular matrix genes vkg and Col4a1, whose dN/dS predicted ovariole numbers among species. Together, we propose a model whereby a set of ovariole-involved gene proteins have an enhanced evolvability, including adaptive evolution, facilitating rapid shifts in ovariole number among Drosophila species.

Adaptive Evolution for the Efficient Production of High-Quality d-Lactic Acid Using Engineered Klebsiella pneumoniae.

d-Lactic acid serves as a pivotal platform chemical in the production of poly d-lactic acid (PDLA) and other value-added products. This compound can be synthesized by certain bacteria, including Klebsiella pneumoniae. However, industrial-scale lactic acid production in Klebsiella pneumoniae faces challenges due to growth inhibition caused by lactic acid stress, which acts as a bottleneck in commercial microbial fermentation processes. To address this, we employed a combination of evolutionary and genetic engineering approaches to create an improved Klebsiella pneumoniae strain with enhanced lactic acid tolerance and production. In flask fermentation experiments, the engineered strain achieved an impressive accumulation of 19.56 g/L d-lactic acid, representing the highest production yield observed in Klebsiella pneumoniae to date. Consequently, this strain holds significant promise for applications in industrial bioprocessing. Notably, our genome sequencing and experimental analyses revealed a novel correlation between UTP-glucose-1-phosphate uridylyltransferase GalU and lactic acid resistance in Klebsiella pneumoniae. Further research is warranted to explore the potential of targeting GalU for enhancing d-lactic acid production.

Ecological Niche Differentiation and Response to Climate Change of the African Endemic Family Myrothamnaceae.

Studying the ecological niches of species and their responses to climate change can provide better conservation strategies for these species. Myrothamnaceae is endemic to Africa, comprising only two species that belong to Myrothamnus (M. flabellifolius and M. moschatus). These closely related species exhibit allopatric distributions, positioning them as ideal materials for studying the species ecological adaptation. This study explores the ecological niche differentiation between M. flabellifolius and M. moschatus and their response capabilities to future climate change. The results indicate that M. flabellifolius and M. moschatus have undergone niche differentiation. The main drivers of niche differences are the minimum temperature of the coldest month (Bio6) for M. flabellifolius, precipitation of the driest month (Bio14), and precipitation of the coldest quarter (Bio19) for M. moschatus. M. flabellifolius demonstrated a stronger adaptation to environments characterized by lower precipitation, relatively lower temperatures, and greater annual temperature variations compared to M. moschatus. Under future climate scenarios (SSP5-8.5, 2081-2100 years), the results show that approximately 85% of the total suitable habitat for M. flabellifolius will be lost, with an 85% reduction in high-suitability areas and almost complete loss of the original mid-low suitability areas. Concurrently, about 29% of the total suitable habitat for M. moschatus will be lost, with a 34% reduction in high suitability areas and roughly 60% of the original mid-low suitability areas becoming unsuitable. This suggests that M. flabellifolius will face greater threats under future climate change. This study contributes novel insight into niche differentiation in Myrothamnaceae and provides useful information for the conservation of this distinctive African lineage.

The genome assembly of Carex breviculmis provides evidence for its phylogenetic localization and environmental adaptation.

Carex breviculmis is a perennial herb with good resistance and is widely used for forage production and turf management. We assembled the genome of 469.01 Mb, revealing 37,372 genes with a BUSCO completeness score of 99.0%. The genome comprises 52.03% repetitive sequences, primarily influenced by recent LTR insertions that have contributed to its expansion. Phylogenetic analysis suggested that C. breviculmis diverged from C. littledalei approximately 6.61 Mya. Investigation into repetitive sequences and expanded gene families (EGFs) highlighted a rapid expansion of tandem duplicate (TD) genes, particularly in areas related to sugar metabolism, various amino acid synthesis, and phenylpropanoid biosynthesis. Additionally, our analysis identified crucial genes involved in secondary metabolic pathways such as glycolysis, phenylpropanoid biosynthesis, and amino acid metabolism, which have undergone positive selection. We reconstructed the sucrose metabolic pathway and identified significant gene expansions, included 16 INV, 9 SPS, and 12 SuSy genes associated with sucrose metabolism, showed varying levels of expansion. In summary, the expansion of these genes, coupled with subsequent positive selection, contributed to C. breviculmis' ability to adapt to environmental stressors. This study lays the foundation for future research on the evolution of Carex plants, their environmental adaptations, and potential genetic breeding.

Dispersal evolution alters evolution-mediated priority effects in a metacommunity.

Biologists have long sought to predict the distribution of species across landscapes to understand biodiversity patterns and dynamics. These efforts usually integrate ecological niche and dispersal dynamics, but evolution can also mediate these ecological dynamics. Species that disperse well and arrive early might adapt to local conditions, which creates an evolution-mediated priority effect that alters biodiversity patterns. Yet, dispersal is also a trait that can evolve and affect evolution-mediated priority effects. We developed an individual-based model where populations of competing species can adapt not only to local environments but also to different dispersal probabilities. We found that lower regional species diversity selects for populations with higher dispersal probabilities and stronger evolution-mediated priority effects. When all species evolved dispersal, they monopolized fewer patches and did so at the same rates. When only one of the species evolved dispersal, it evolved lower dispersal than highly dispersive species and monopolized habitats once freed from maladaptive gene flow. Overall, we demonstrate that dispersal evolution can shape evolution-mediated priority effects when provided with a greater ecological opportunity in species-poor communities. Dispersal- and evolution-mediated priority effects probably play greater roles in species-poor regions like the upper latitudes, isolated islands and in changing environments. This article is part of the theme issue 'Diversity-dependence of dispersal: interspecific interactions determine spatial dynamics'.

Pleiotropy of positive selection in ancient ACE2 suggests an alternative hypothesis for bat-specific adaptations to host coronaviruses.

Angiotensin-convertingenzyme 2 (ACE2) has dual functions, regulating cardiovascular physiology and serving as the receptor for coronaviruses. Bats, the only true flying mammals and natural viral reservoirs, have evolved positive alterations in traits related to both functions of ACE2. This suggests significant evolutionary changes in ACE2 during bat evolution. To test this hypothesis, we examine the selection pressure in ACE2 along the ancestral branch of all bats (AncBat-ACE2), where powered flight and bat-coronavirus coevolution occurred, and detect a positive selection signature. To assess the functional effects of positive selection, we resurrect AncBat-ACE2 and its mutant (AncBat-ACE2-mut) created by replacing the positively selected sites. Compared to AncBat-ACE2-mut, AncBat-ACE2 exhibits stronger enzymatic activity, enhances mice's performance in exercise fatigue, and shows lower affinity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Our findings indicate the functional pleiotropy of positive selection in the ancient ACE2 of bats, providing an alternative hypothesis for the evolutionary origin of bats' defense against coronaviruses.

Exploring the role of polymorphic interspecies structural variants in reproductive isolation and adaptive divergence in Eucalyptus.

Structural variations (SVs) play a significant role in speciation and adaptation in many species, yet few studies have explored the prevalence and impact of different categories of SVs. We conducted a comparative analysis of long-read assembled reference genomes of closely related Eucalyptus species to identify candidate SVs potentially influencing speciation and adaptation. Interspecies SVs can be either fixed differences or polymorphic in one or both species. To describe SV patterns, we employed short-read whole-genome sequencing on over 600 individuals of Eucalyptus melliodora and Eucalyptus sideroxylon, along with recent high-quality genome assemblies. We aligned reads and genotyped interspecies SVs predicted between species reference genomes. Our results revealed that 49,756 of 58,025 and 39,536 of 47,064 interspecies SVs could be typed with short reads in E. melliodora and E. sideroxylon, respectively. Focusing on inversions and translocations, symmetric SVs that are readily genotyped within both populations, 24 were found to be structural divergences, 2,623 structural polymorphisms, and 928 shared structural polymorphisms. We assessed the functional significance of fixed interspecies SVs by examining differences in estimated recombination rates and genetic differentiation between species, revealing a complex history of natural selection. Shared structural polymorphisms displayed enrichment of potentially adaptive genes. Understanding how different classes of genetic mutations contribute to genetic diversity and reproductive barriers is essential for understanding how organisms enhance fitness, adapt to changing environments, and diversify. Our findings reveal the prevalence of interspecies SVs and elucidate their role in genetic differentiation, adaptive evolution, and species divergence within and between populations.

Adaptive evolution of Clostridium thermocellum ATCC 27405 on alternate carbon sources leads to altered fermentation profiles.

Consolidated bioprocessing candidate, Clostridium thermocellum, is a cellulose hydrolysis specialist, with the ability to ferment the released sugars to produce bioethanol. C. thermocellum is generally studied with model substrates Avicel and cellobiose to understand the metabolic pathway leading to ethanol. In the present study, adaptive laboratory evolution, allowing C. thermocellum DSM 1237 to adapt to growth on glucose, fructose, and sorbitol, with the prospect that some strains will adapt their metabolism to yield more ethanol. Adaptive growth on glucose and sorbitol resulted in an approximately 1 mM and 2 mM increase in ethanol yield per millimolar glucose equivalent, respectively, accompanied by a shift in the production of the other expected fermentation end products. The increase in ethanol yield observed for sorbitol adapted cells was due to the carbon source being more reduced compared to cellobiose. Glucose and cellobiose have similar oxidation states thus the increase in ethanol yield is due to the rerouting of electrons from other reduced metabolic products excluding H2 which did not decrease in yield. There was no increase in ethanol yield observed for fructose adapted cells, but there was an unanticipated elimination of formate production, also observed in sorbitol adapted cells suggesting that fructose has regulatory implications on formate production either at the transcription or protein level.

Plastome structure, phylogeny and evolution of plastid genes in Reevesia (Helicteroideae, Malvaceae).

Reevesia is an eastern Asian-eastern North American disjunction genus in the family Malvaceae s.l. and comprises approximately 25 species. The relationships within the genus are not well understood. Here, 15 plastomes representing 12 Reevesia species were compared, with the aim of better understanding the species circumscription and phylogenetic relationships within the genus and among genera in the family Malvaceae s.l. The 11 newly sequenced plastomes range between 161,532 and 161, 945 bp in length. The genomes contain 114 unique genes, 18 of which are duplicated in the inverted repeats (IRs). Gene content of these plastomes is nearly identical. All the protein-coding genes are under purifying selection in the Reevesia plastomes compared. The top ten hypervariable regions, SSRs, and the long repeats identified are potential molecular markers for future population genetic and phylogenetic studies. Phylogenetic analysis based on the whole plastomes confirmed the monophyly of Reevesia and a close relationship with Durio (traditional Bombacaceae) in subfamily Helicteroideae, but not with the morphologically similar genera Pterospermum and Sterculia (both of traditional Sterculiaceae). Phylogenetic relationships within Reevesia suggested that two species, R. pubescens and R. thyrsoidea, as newly defined, are not monophyletic. Six taxa, R. membranacea, R. xuefengensis, R. botingensis, R. lofouensis, R. longipetiolata and R. pycnantha, are suggested to be recognized.

Repeated Exposure of Vancomycin to Vancomycin-Susceptible Staphylococcus aureus (VSSA) Parent Emerged VISA and VRSA Strains with Enhanced Virulence Potentials.

The emergence of resistance against the last-resort antibiotic vancomycin in staphylococcal infections is a serious concern for human health. Although various drug-resistant pathogens of diverse genetic backgrounds show higher virulence potential, the underlying mechanism behind this is not yet clear due to variability in their genetic dispositions. In this study, we investigated the correlation between resistance and virulence in adaptively evolved isogenic strains. The vancomycin-susceptible Staphylococcus aureus USA300 was exposed to various concentrations of vancomycin repeatedly as a mimic of the clinical regimen to obtain mutation(s)-accrued-clonally-selected (MACS) strains. The phenotypic analyses followed by expression of the representative genes responsible for virulence and resistance of MACS strains were investigated. MACS strains obtained under 2 and 8 µg/ml vancomycin, named Van2 and Van8, respectively; showed enhanced vancomycin minimal inhibitory concentrations (MIC) to 4 and 16 µg/ml, respectively. The cell adhesion and invasion of MACS strains increased in proportion to their MICs. The correlation between resistance and virulence potential was partially explained by the differential expression of genes known to be involved in both virulence and resistance in MACS strains compared to parent S. aureus USA300. Repeated treatment of vancomycin against vancomycin-susceptible S. aureus (VSSA) leads to the emergence of vancomycin-resistant strains with variable levels of enhanced virulence potentials.

Lamprey--an excellent model for iron metabolism.

After 500 million years of evolution, lamprey is in a natural environment characterized by low temperature and high iron content, and its unique adaptive evolution mode has developed its organizational structure and life mechanism in the process of metamorphosis, which provides a new direction for people to further study the origin and evolution of life. Iron is one of the essential nutrients for the human body and plays an important role in metabolic processes, but when exceeded, it can lead to iron toxicity. For example, the serum iron concentration of pre-metamorphosis larvae is 149 times that of normal males, and the iron content in the liver of juveniles is about 2-3 times that of normal humans. Lamprey has a complete biochemical system to tolerate high concentrations of free iron in the body, and high expression of important genes for iron homeostasis, such as transferrin, ferritin heavy chain, superoxide dismutase, etc., improves iron transport, iron storage and antioxidant capacity. Lamprey has an IRE/IRP regulatory system, which is an important protection mechanism for lamprey to adapt to the high iron content environment in the organization. In addition, lampreys gradually form oral glands during metamorphosis and development, which become the unique iron metabolism organs of lampreys. In this review, we mainly summarize the distribution of iron in various tissues of lamprey and the potential mechanism of adapting to the content of iron in the body, so as to provide a theoretical basis for the subsequent search for the molecular mechanism of iron metabolism.