Purifying selection is expected to prevent the accumulation of transposable elements within their host, especially when located in and around genes and if affected by epigenetic silencing. However, positive selection may favour the spread of TEs causing genomic imprinting under parental conflict, as genomic imprinting allows parent-specific influence over resource accumulation to the progeny. Concomitantly, the number and frequency of TE insertions in natural populations are conditioned by demographic events. In this study, we aimed to test how demography and selective forces interact to affect the accumulation of TEs around genes, depending on their epigenetic silencing and with a particular focus on imprinted genes. To this aim, we compared the frequency and distribution of TEs in A. lyrata from Europe and North America. Generally, we found that TE insertions showed a lower frequency when they were inserted in or near genes, especially TEs targeted by epigenetic silencing, suggesting purifying selection at work. We also found that many TEs were lost or got fixed in North American populations during the colonization and the postglacial range expansion from refugia of the species in North America, as well as during the transition to selfing, suggesting a potential "TE load'. Finally, we found that silenced TEs increased in frequency and even tended to reach fixation when they were linked to imprinted genes. We conclude that in A. lyrata, genomic imprinting has spread in natural populations through demographic events and positive selection acting on silenced TEs, potentially under a parental conflict scenario.
- Klíčová slova
- Arabidopsis lyrata, Transposable elements, demographic history, genomic imprinting, positive selection, transposon load,
- Publikační typ
- časopisecké články MeSH
The globally distributed genus Zygogonium exhibits a narrow environmental range, with 19 morphologically described species. Its molecular characterization is poor, based on a single accession of the type species Z. ericetorum from Austria. We examined the genetic variability, morphology, and ultrastructure of field-collected Zygogonium material from different sampling sites in Austria, Norway, Ireland, Scotland, and the United States. Phylogenetic analysis based on partial sequences of the psbC gene distinguished three well-supported groups and one subgroup. AtpB gene sequences collected from a subset of samples also support this result, while rbcL gene data provided lower support. Group 1A contained the type species Z. ericetorum from Obergurgl/Austria and samples from Kühtai/Austria, Norway, and Scotland. The morphology was characterized by wide vegetative filaments (15-31 μm) and the occurrence of aplanospores with purple residue. Group 1B contained Z. cf. ericetorum from Ireland and Ellmau/Austria. Filaments were in a similar size range (12-30 μm) as in group 1A. This group had round unusual akinetes with green or purple content, had one or two chloroplasts, and was surrounded by a thick cell wall; no aplanospores were observed. Group 2 collected from Ireland had narrower filaments (8-12 μm), cells up to six times longer than wide, and contained elongated aplanospores. Therefore, we have described a new species Z. angustum sp. nov. Group 3 contained Z. cf. ericetorum from Norway and the United States, represented by vegetative filaments with an intermediate width (13-20 μm), but no other distinct morphological features. The morphological and genetic variability observed in Zygogonium is possibly related to habitat and ecology.
- Klíčová slova
- Charophyta, Conjugatophyceae, atpB, conjugating green algae, phylogeny, plant terrestrialization, psbC, rbcL, streptophyte, ultrastructure,
- Publikační typ
- časopisecké články MeSH
This review provides a comprehensive account of advances in the field of cholinesterase inhibitors isolated from the Buxaceae family. Naturally occurring anticholinesterases derived from plants are considered to be a potential source of new drug candidates for treating Alzheimer's disease (AD). AD is now universally accepted as an irreversible, incurable, and progressive neurological disorder. Initiating with memory impairment, propagating with cognitive deficit, and ultimately leading to death is the general pathway of AD. Lower level of acetylcholine in the brain is characterized as one of the prominent reasons for AD. The cholinergic hypothesis states that elevated levels of acetylcholine in the brain can alleviate symptoms of AD. Steroidal and terpenoidal alkaloids isolated from plants of the Buxaceae family have been reviewed here for their anticholinesterase activity. Most of them have shown in vitro inhibition of horse serum butyrylcholinesterase (BuChE, EC 3.1.1.7) and electric eel acetylcholinesterase (AChE, EC 3.1.1.8). Although the general consensus has concluded that cholinesterase inhibitors may alleviate AD symptoms but cannot cure the disease, new drugs are still being sought to improve the quality of life of AD patients. Steroidal and terpenoidal anticholinesterase alkaloids can prove to be a promising group of AChE inhibitors.
- Klíčová slova
- Alzheimer’s disease, Buxaceae, acetylcholinesterase, butyrylcholinesterase, cholinesterase inhibitors, inhibition,
- Publikační typ
- časopisecké články MeSH
The nuclear ribosomal DNA Internal Transcribed Spacer (ITS) region is used as a universal fungal barcode marker, but often lacks a significant DNA barcoding gap between sister taxa. Here we tested the reliability of protein coding low-copy genes as alternative barcode markers. Mock communities of three unrelated agaric genera (Dermoloma, Hodophilus, and Russula) representing lineages of closely related species were sequenced by the Illumina platform targeting the ITS1, ITS2, the second largest subunit of RNA polymerase II gene (rpb2) and the transcription elongation factor 1-alpha gene (ef1-α) regions. Species representation and their relative abundances were similar across all tested barcode regions, despite a lower copy number in protein coding markers. ITS1 and ITS2 required more sophisticated sequence filtering because they produced a high number of chimeric sequences requiring reference-based chimera removal and had a higher number of sequence variants per species. Although clustering of filtered ITS sequences resulted in an average higher number of correctly clustered units at optimal similarity thresholds, these thresholds varied substantially among genera. Best-fitted thresholds of low-copy markers were more consistent across genera but frequently lacked species resolution due to low intraspecific variability. At some thresholds, we observed multiple species lumped together, and at the same time, species split into multiple partial clusters, which should be taken into consideration when assessing the best clustering thresholds and taxonomic identity of clusters. To achieve the best taxonomic resolution and improve species detection, we recommend combining different markers and applying additional reference-based sorting of clusters. The current availability of rpb2 and ef1-α reference sequences in public databases is far from being complete for all fungal groups, but a combined marker approach can be used for group-specific studies that can build reference data for their own purposes.
- Klíčová slova
- amplicon abundance, chimera, sympatric species, threshold,
- Publikační typ
- časopisecké články MeSH
BACKGROUND: The Trichophyton mentagrophytes complex encompasses common dermatophytes causing superficial mycoses in humans and animals. The taxonomy of the complex is unstable, with conflicting views on the species status of some taxa, particularly T. indotineae and T. interdigitale. Due to the presence of intermediate genotypes, neither MALDI-TOF MS nor ITS rDNA sequencing can accurately distinguish all taxa in the complex, potentially contributing to clinical misdiagnoses. OBJECTIVES: This research resolves phylogenetic relationships within the T. mentagrophytes complex. Based on these data, the taxonomical recommendations are suggested. METHODS: In order to resolve the phylogenetic relationship of the T. mentagrophytes complex, we employed Restriction Site-Associated DNA Sequencing (RADseq) to produce a high-resolution single nucleotide polymorphism (SNP) dataset from 95 isolates. The SNP-based analyses indicated the presence of two major genetic clusters corresponding to T. mentagrophytes (including T. indotineae) and T. interdigitale. RESULTS: Our results challenge the species status of T. indotineae because of insufficient genetic divergence from T. mentagrophytes. Therefore, we propose designating T. indotineae as T. mentagrophytes var. indotineae (or T. mentagrophytes ITS genotype VIII) to avoid further splitting of the complex and taxonomic inflation. Although T. interdigitale shows clearer genetic differentiation, its separation is incomplete and identification of some isolates is ambiguous when using routine methods, leading us to consider it a variety as well: T. mentagrophytes var. interdigitale. CONCLUSIONS: We recommend using T. mentagrophytes as the overarching species name for all complex isolates. Where precise molecular identification is possible, the use of variety ranks is encouraged. Since identical resistance mechanisms are not specific to any genotype or dermatophyte species, identifying antifungal resistance is more important than differentiating closely related genotypes or populations.
- Klíčová slova
- Trichophyton interdigitale, Trichophyton mentagrophytes, anthropophilic dermatophytes, antifungal resistance, dermatophytosis, population structure, taxonomy, zoophilic dermatophytes,
- MeSH
- antifungální látky * farmakologie MeSH
- Arthrodermataceae * genetika klasifikace účinky léků MeSH
- DNA fungální genetika MeSH
- fylogeneze * MeSH
- genomika metody MeSH
- genotyp MeSH
- jednonukleotidový polymorfismus MeSH
- lidé MeSH
- sekvenční analýza DNA MeSH
- tinea mikrobiologie MeSH
- Trichophyton * genetika klasifikace účinky léků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- antifungální látky * MeSH
- DNA fungální MeSH
UNLABELLED: The Aspergillus genus encompasses a diverse array of species, some of which are opportunistic pathogens. Traditionally, human aspergillosis has primarily been linked to a few Aspergillus species, predominantly A. fumigatus. Changes in epidemiology and advancements in molecular techniques have brought attention to less common and previously unrecognized pathogenic cryptic species. Despite the taxonomic recognition of many cryptic species in section Terrei, their virulence potential and clinical implications, compared to A. terreus sensu stricto, remain poorly understood. Hence, the current study utilized the alternative in vivo model Galleria mellonella to evaluate the virulence potential of 19 accepted Aspergillus species in section Terrei, classified into three series (major phylogenetic clades): Terrei, Nivei, and Ambigui. Analyzing the median survival rates of infected larvae of all species in each series revealed that series Ambigui has a significantly lower virulence compared to series Terrei and Nivei. Taking a closer look at series Terrei and Nivei revealed a trend of survival within each clade, dividing the species into two groups: highly virulent (up to 72 h survival) and less virulent (up to 144 h survival). Histological observation, considering fungal distribution and filamentation, further supported this assessment, revealing increased distribution and hyphal formation in virulent species. Additionally, the susceptibility profile of conventional antifungals was determined, revealing an increased azole minimum inhibitory concentration for some tested cryptic species such as A. niveus and A. iranicus. Our results highlight the importance of cryptic species identification, as they can exhibit different levels of virulence and show reduced antifungal susceptibility. IMPORTANCE: With changing fungal epidemiology and an increasingly vulnerable population, cryptic Aspergillus species are emerging as human pathogens. Their diversity and clinical relevance remain underexplored, with some species showing reduced antifungal susceptibility and higher virulence, highlighting the need for better preparedness in clinical practice. Using the Galleria mellonella model, we assessed the virulence of Aspergillus species of section Terrei, including cryptic and non-cryptic species, across three series Terrei, Nivei, and Ambigui. The results revealed significant virulence variation among the series, with some cryptic species displaying high virulence. Histological analysis confirmed increased hyphal formation and fungal spread in the more virulent species. Additionally, elevated azole minimum inhibitory concentrations were also observed in certain cryptic species. This study presents novel insights into the pathogenicity of Aspergillus section Terrei, emphasizing the critical importance of accurately identifying cryptic species due to their diverse virulence potential and antifungal resistance, which may have substantial clinical implications.
- Klíčová slova
- Aspergillus terreus, Galleria mellonella model, antifungal resistance, antifungal susceptibility testing, histopathology, pathogenicity, section Terrei, virulence,
- Publikační typ
- časopisecké články MeSH
Restricted range size brings about noteworthy genetic consequences that may affect the viability of a population and eventually its extinction. Particularly, the question if an increase in inbreeding can avert the accumulation of genetic load via purging is hotly debated in the conservation genetic field. Insular populations with limited range sizes represent an ideal setup for relating range size to these genetic factors. Leveraging a set of eight differently sized populations of Galápagos mockingbirds (Mimus), we investigated how island size shaped effective population size (Ne), inbreeding and genetic load. We assembled a genome of M. melanotis and genotyped three individuals per population by whole-genome resequencing. Demographic inference showed that the Ne of most populations remained high after the colonisation of the archipelago 1-2 Mya. Ne decline in M. parvulus happened only 10-20 Kya, whereas the critically endangered M. trifasciatus showed a longer history of reduced Ne. Despite these historical fluctuations, the current island size determines Ne in a linear fashion. In contrast, significant inbreeding coefficients, derived from runs of homozygosity, were identified only in the four smallest populations. The index of additive genetic load suggested purging in M. parvulus, where the smallest populations showed the lowest load. By contrast, M. trifasciatus carried the highest genetic load, possibly due to a recent rapid bottleneck. Overall, our study demonstrates a complex effect of demography on inbreeding and genetic load, providing implications in conservation genetics in general and in a conservation project of M. trifasciatus in particular.
- Klíčová slova
- conservation genetics, demographic inference, genetic diversity, genetic load,
- MeSH
- genetická zátěž * MeSH
- genom genetika MeSH
- genotyp MeSH
- hustota populace * MeSH
- inbreeding * MeSH
- ostrovy * MeSH
- Passeriformes genetika MeSH
- populační genetika * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Ekvádor MeSH
- ostrovy * MeSH
BACKGROUND AND AIMS: While we know a lot about variation of root traits across large set of species, knowledge on differences in root traits among species with different ecological optima, simultaneously considering species life span and phylogeny, is limited. We also do not know if inter-specific differences in root traits measured in one environment apply in another environment. Such knowledge is crucial to predict species responses to future environments. METHODS: Using 65 species cultivated under uniform conditions, we studied effects of species habitat preference, describing under which conditions the species naturally occur, on root morphological and chemical traits and allocation to roots while also considering species life span, phenology at harvest and phylogeny. In a subset of species, we explored if species rankings in values of different traits depend on specific substrate of growth. KEY RESULTS: Inter-specific trait differences were strongly linked to species habitat preferences. The best predictor was indicator value for soil disturbance with roots of species preferring disturbed habitats having higher specific root length and lower diameter, suggesting low collaboration with mutualists. While life span and phylogeny also determined trait values, their inclusion into models did not change effects of habitat preferences. The patterns are thus not a result of species niche conservatism, but contemporary species adaptations. Species ranking in different substrates was more consistent for root morphology than for root chemistry and root/shoot ratio. CONCLUSIONS: Root trait variation is driven by species habitat preferences indicating that inter-specific root trait variation is a result of species adaptations to different environments. Interestingly, disturbance indicator value was a better predictor of root trait variation than other, more commonly, considered habitat characteristics. Inter-specific differentiation in root morphology is consistent among substrates and can thus be compared across studies, but root chemistry and allocation data have to be used with caution.
Clonal demographic traits play important roles in regulating community dynamics. Yet, it remains unclear how the responses of these clonal traits to drought might depend on previous drought exposure, and how drought responses vary among grasslands. We conducted a repeated drought experiment across four grasslands along an aridity gradient in northern China. We assessed the effects of single (precipitation reduction in 2021-2022) versus recurrent (precipitation reduction in 2015-2018 and 2021-2022) drought on bud density, shoot density, and the ratio of bud to shoot density. Drought reduced bud density at all grasslands and shoot density at most grasslands. Drought reduced the ratio of bud-to-shoot density only in the most arid grasslands. Recurrent drought had larger negative effects than a single drought on bud density and composition of bud and shoot at only one of four grasslands, and on shoot density at two of four grasslands. Our results suggest that previous drought exposure can alter the response of plant clonal demographic traits to subsequent drought in some but not all grasslands, and that responses can vary with mean climate.
- Klíčová slova
- bud limitation, climate change, drought frequency, population regeneration, productivity, shoot density,
- MeSH
- období sucha * MeSH
- pastviny * MeSH
- výhonky rostlin * fyziologie růst a vývoj MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Čína MeSH
BACKGROUND: Trichophyton mentagrophytes ITS genotype VII (TMVII) has recently been identified in France as the causative agent of dermatophyte infections transmitted during sexual activity among men who have sex with men (MSM). OBJECTIVES: Our objective was to provide new insights into the epidemiology, clinical presentation and treatment of TMVII infections based on cases diagnosed from October 2022 to September 2023 in three medical mycology laboratories in Paris. Additionally, we aimed to perform molecular characterization of TMVII strains collected in Paris, as well as in Switzerland. METHODS: We identified all isolates from skin and hair belonging to the T. mentagrophytes complex by sequencing the ITS region. For isolates corresponding to TMVII, clinical data were retrieved from medical records. For all available TMVII strains that we isolated since January 2021, we sequenced tef1α and tubb and determined the MAT locus idiomorph. RESULTS: We identified 32 cases of TMVII Infections. All cases occurred in men, 30 of whom reported having sex with men. Fifteen cases were sporadic cases including four among sex workers. The other 17 cases belonged to a single cluster involving a tantric masseur who infected 15 clients and his roommate. The median time from massage to lesion onset was 16 [2-52] days. Except for one patient, all other patients received systemic antifungal treatment with terbinafine. We observed five patients whose cultures remained positive even after 3-4 weeks of treatment and five patients experienced a relapse of the infection after discontinuing antifungal treatment. All French isolates exhibited identical tef1α and tubb sequences, as well as the same MAT idiomorph locus. They displayed variations in the tef1α sequence compared to isolates from Switzerland and the Czech Republic. CONCLUSIONS: We confirm the active circulation of TMVII among MSM in France, which is associated with challenges in diagnosis, treatment and prevention.
- MeSH
- antifungální látky terapeutické užití MeSH
- Arthrodermataceae * genetika MeSH
- dospělí MeSH
- genotyp MeSH
- homosexualita mužská * MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- tinea * epidemiologie farmakoterapie mikrobiologie MeSH
- Trichophyton * genetika MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Francie epidemiologie MeSH
- Názvy látek
- antifungální látky MeSH
