Functional Groups Of Genes Research Articles

Sarcomere gene variants did not improve cardiac function in pediatric patients with dilated cardiomyopathy from Japanese cohorts

Dilated cardiomyopathy (DCM) is a progressive myocardial disorder characterized by impaired cardiac contraction and ventricular dilation. However, some patients with DCM improve when experiencing left ventricular reverse remodeling (LVRR). Currently, the detailed association between genotypes and clinical outcomes, including LVRR, particularly among children, remains uncertain. Pediatric patients with DCM from multiple Japanese institutions recorded between 2014 and 2023 were enrolled. We identified their DCM-related genes and explored the association between gene variants and clinical outcomes, including LVRR. We included 123 pediatric patients (62 males; median age: 8 [1–51] months) and found 50 pathogenic variants in 45 (35.0%) of them. The most identified gene was MYH7 (14.0%), followed by RYR2 (12.0%) and TPM1 (8.0%). LVRR was achieved in 47.5% of these patients. The left ventricular ejection fraction remained unchanged (31.4% to 39.8%, P = 0.1913) in patients with sarcomere gene variants and in those with non-sarcomere gene variants (33.4% to 47.8%, P = 0.0522) but significantly increased in those without gene variants (33.6% to 54.1%, P < 0.0001). LVRR was not uniform across functional gene groups. Hence, an individualized gene-guided prediction approach may be adopted for children with DCM.

New insights on the phylogeny, evolutionary history, and ecological adaptation mechanism in cycle-cup oaks based on chloroplast genomes.

Cycle-cup oaks (Quercus section Cyclobalanopsis) are one of the principal components of forests in the tropical and subtropical climates of East and Southeast Asia. They have experienced relatively recent increases in the diversification rate, driven by changing climates and the Himalayan orogeny. However, the evolutionary history and adaptive mechanisms at the chloroplast genome level in cycle-cup oaks remain largely unknown. Therefore, we studied this problem by conducting chloroplast genomics on 50 of the ca. 90 species. Comparative genomics and other analyses showed that Quercus section Cyclobalanopsis had a highly conserved chloroplast genome structure. Highly divergent regions, such as the ndhF and ycf1 gene regions and the petN-psbM and rpoB-trnC-GCA intergenic spacer regions, provided potential molecular markers for subsequent analysis.The chloroplast phylogenomic tree indicated that Quercus section Cyclobalanopsis was not monophyletic, which mixed with the other two sections of subgenus Cerris. The reconstruction of ancestral aera inferred that Palaeotropics was the most likely ancestral range of Quercus section Cyclobalanopsis, and then dispersed to Sino-Japan and Sino-Himalaya. Positive selection analysis showed that the photosystem genes had the lowest ω values among the seven functional gene groups. And nine protein-coding genes containing sites for positive selection: ndhA, ndhD, ndhF, ndhH, rbcL, rpl32, accD, ycf1, and ycf2. This series of analyses together revealed the phylogeny, evolutionary history, and ecological adaptation mechanism of the chloroplast genome of Quercus section Cyclobalanopsis in the long river of earth history. These chloroplast genome data provide valuable information for deep insights into phylogenetic relationships and intraspecific diversity in Quercus.

MatK impacts differential chloroplast translation by limiting spliced tRNA-K(UUU) abundance.

The protein levels of chloroplast photosynthetic genes and genes related to the chloroplast genetic apparatus vary to adapt to different conditions. However, the underlying mechanisms governing these variations remain unclear. The chloroplast intron Maturase K is encoded within the trnK intron and has been suggested to be required for splicing several group IIA introns, including the trnK intron. In this study, we used RNA immunoprecipitation followed by high-throughput sequencing (RIP-Seq) to identify MatK's preference for binding to group IIA intron domains I and VI within target transcripts. Importantly, these domains are crucial for splice site selection, and we discovered alternative 5'-splice sites in three MatK target introns. The resulting alternative trnK lariat structure showed increased accumulation during heat acclimation. The cognate codon of tRNA-K(UUU) is highly enriched in mRNAs encoding ribosomal proteins and a trnK-matK over-expressor exhibited elevated levels of the spliced tRNA-K(UUU). Ribosome profiling analysis of the overexpressor revealed a significant up-shift in the translation of ribosomal proteins compared to photosynthetic genes. Our findings suggest the existence of a novel regulatory mechanism linked to the abundance of tRNA-K(UUU), enabling the differential expression of functional chloroplast gene groups.

Rare Genetic Variants in Young Adults Requiring Pacemaker Implantation

BackgroundGenetic disease has recently emerged as a cause of cardiac conduction disorders (CCDs), but the diagnostic yield of genetic testing and the contribution of the different genes to CCD is still unsettled. ObjectivesThis study sought to determine the diagnostic yield of genetic testing in young adults with CCD of unknown etiology requiring pacemaker implantation. We also studied the prevalence of rare protein-altering variants across individual genes and functional gene groups. MethodsWe performed whole exome sequencing in 150 patients with CCD of unknown etiology who had permanent pacemaker implanted at age ≤60 years at 14 Spanish hospitals. Prevalence of rare protein-altering variants in patients with CCD was compared with a reference population of 115,522 individuals from gnomAD database (control subjects). ResultsAmong 39 prioritized genes, patients with CCD had more rare protein-altering variants than control subjects (OR: 2.39; 95% CI: 1.75-3.33). Significant enrichment of rare variants in patients with CCD was observed in all functional gene groups except in the desmosomal genes group. Rare variants in the nuclear envelope genes group exhibited the strongest association with CCD (OR: 6.77; 95% CI: 3.71-13.87). Of note, rare variants in sarcomeric genes were also enriched (OR: 1.73; 95% CI: 1.05-3.10). An actionable genetic variant was detected in 21 patients (14%), with LMNA being the most frequently involved gene (4.6%). ConclusionsUnrecognized rare genetic variants increase the risk of CCD in young adults with CCD of unknown etiology. Genetic testing should be performed in patients age ≤60 years with CCD of unknown etiology. The role of genetic variants in sarcomeric genes as a cause of CCD should be further investigated.

Hypothalamic transcriptome response to simulated diel earthen pond hypoxia cycles in channel catfish (Ictalurus punctatus).

Commercial culture of channel catfish (Ictalurus punctatus) occurs in earthen ponds that are characterized by diel swings in dissolved oxygen concentration that can fall to severe levels of hypoxia, which can suppress appetite and lead to suboptimal growth. Given the significance of the hypothalamus in regulating these processes in other fishes, an investigation into the hypothalamus transcriptome was conducted to identify specific genes and expression patterns responding to hypoxia. Channel catfish in normoxic water were compared with catfish subjected to 12 h of hypoxia (20% oxygen saturation; 1.8 mg O2/L; 27°C) followed by 12 h of recovery in normoxia to mimic 24 h in a catfish aquaculture pond. Fish were sampled at 0-, 6-, 12-, 18-, and 24-h timepoints, with the 6- and 12-h samplings occurring during hypoxia. A total of 190 genes were differentially expressed during the experiment, with most occurring during hypoxia and returning to baseline values within 6 h of normoxia. Differentially expressed genes were sorted by function into Gene Ontology biological processes and revealed that most were categorized as "response to hypoxia," "sprouting angiogenesis," and "cellular response to xenobiotic stimulus." The patterns of gene expression reported here suggest that transcriptome responses to hypoxia are broad and quickly reversibly with the onset of normoxia. Although no genes commonly reported to modulate appetite were found to be differentially expressed in this experiment, several candidates were identified for future studies investigating the interplay between hypoxia and appetite in channel catfish, including adm, igfbp1a, igfbp7, and stc2b.NEW & NOTEWORTHY Channel catfish are an economically important species that experience diel episodic periods of hypoxia that can reduce appetite. This is the first study to investigate their transcriptome from the hypothalamus in a simulated 24-h span in a commercial catfish pond, with 12 h of hypoxia and 12 h of normoxia. The research revealed functional groups of genes relating to hypoxia, angiogenesis, and glycolysis as well as individual target genes possibly involved in appetite regulation.

Impact of functional gene groups on outcomes after ablation of ventricular tachycardia in patients with inherited left ventricular cardiomyopathy: an international multicentre study

Abstract Background Advances in genetic testing has enabled identification of pathogenic variants of different functional gene groups associated with non-dilated left ventricular cardiomyopathy (NDLCM)/dilated cardiomyopathy (DCM) and ventricular tachycardia (VT). However, there is limited data on the impact of functional groups on VT ablation outcome. Aim We aimed to assess the impact of likely pathogenic/pathogenic variants (LP/Pv) of different functional gene groups on heart failure (HF) outcomes and VT recurrence in patients with NDLCM/DCM after VT ablation. Methods Patients with NDLCM/DCM who underwent genetic testing (next-generation sequencing) and were referred for VT ablation were enrolled at 6 participating centers. Patients were followed for VT recurrence, HF-related adverse outcomes (death, left ventricular assist device [LVAD], or heart transplantation due to HF), and all-cause mortality. Results A total of 239 patients (age 55±14yrs; male n=193; LVEF 40±12%; amiodarone at admission n=103; ICD n=180) were included. LP/Pv were identified in 128 patients (54%), predominantly found in genes encoding sarcomeric (n=36/128, [28%]; titin n=20, myosin binding protein C n=12), followed by nuclear membrane (n=27/128, [22%]; lamin A/C; n=26), desmosomal (n=23/128, [18%]; desmoplakin n=11, plakophilin n=9), cytoskeleton (n=12/128, [9%]; filamin C n=8), and sarcoplasmic reticulum proteins (n=12/128, [9%]; phospholamban n=10). Variants of unknown significance (n=32) were grouped with patients who tested negative. Acute complete ablation success, defined as non-VT inducibility of any sustained monomorphic VT, was achieved in 113 patients (47%), 63 (56%) with LP/Pv. During a median follow-up of 32 months, 108 patients (45%) had VT recurrence, 41 (17%) had HF-related adverse outcomes (death with/without LVAD in 34, LVAD in 2, heart transplantation in 5) and 47 (20%) died. Patients with LP/Pv were more likely to have VT recurrence, HF-related adverse outcomes and had a higher mortality compared to those without (VT, 68 [53%] vs. 40 [36%]; HF-related adverse outcomes, 30 [23%] vs. 11 [10%]; mortality, 30 [23%] vs. 17 [15%]; log-rank, P&amp;lt;0.01 for all). As compared to patients without LP/Pv, those with LP/Pv in genes encoding nuclear membrane or sarcomeric proteins had significantly worse (P&amp;lt;0.01 for both) and those with LP/Pv in genes encoding desmosomal proteins had similar HF and VT recurrence outcomes (Figure). Of interest, patients with LP/Pv in genes encoding cytoskeleton proteins had favorable HF-related adverse outcomes, but worse VT recurrence (P=0.02) compared to those without LP/Pv (Figure). Conclusion In patients with NDLCM/DCM and VT, the impact of LP/Pv on HF and VT-recurrence outcomes after ablation differs across functional groups. Integrating genetic testing in the comprehensive evaluation of patients with NDLCM/DCM undergoing VT ablation may facilitate personalized ablation strategies and early consideration of alternative HF treatments.

Deep learning the cis-regulatory code for gene expression in selected model plants

Elucidating the relationship between non-coding regulatory element sequences and gene expression is crucial for understanding gene regulation and genetic variation. We explored this link with the training of interpretable deep learning models predicting gene expression profiles from gene flanking regions of the plant species Arabidopsis thaliana, Solanum lycopersicum, Sorghum bicolor, and Zea mays. With over 80% accuracy, our models enabled predictive feature selection, highlighting e.g. the significant role of UTR regions in determining gene expression levels. The models demonstrated remarkable cross-species performance, effectively identifying both conserved and species-specific regulatory sequence features and their predictive power for gene expression. We illustrated the application of our approach by revealing causal links between genetic variation and gene expression changes across fourteen tomato genomes. Lastly, our models efficiently predicted genotype-specific expression of key functional gene groups, exemplified by underscoring known phenotypic and metabolic differences between Solanum lycopersicum and its wild, drought-resistant relative, Solanum pennellii.

Experimental evolution of extremotolerant and extremophilic fungi under osmotic stress.

Experimental evolution was carried out to investigate the adaptive responses of extremotolerant fungi to a stressful environment. For 12 cultivation cycles, the halotolerant black yeasts Aureobasidium pullulans and Aureobasidium subglaciale were grown at high NaCl or glycerol concentrations, and the halophilic basidiomycete Wallemia ichthyophaga was grown close to its lower NaCl growth limit. All evolved Aureobasidium spp. accelerated their growth at low water activity. Whole genomes of the evolved strains were sequenced. No aneuploidies were detected in any of the genomes, contrary to previous studies on experimental evolution at high salinity with other species. However, several hundred single-nucleotide polymorphisms were identified compared with the genomes of the progenitor strains. Two functional groups of genes were overrepresented among the genes presumably affected by single-nucleotide polymorphisms: voltage-gated potassium channels in A. pullulans at high NaCl concentration, and hydrophobins in W. ichthyophaga at low NaCl concentration. Both groups of genes were previously associated with adaptation to high salinity. Finally, most evolved Aureobasidium spp. strains were found to have increased intracellular and decreased extracellular glycerol concentrations at high salinity, suggesting that the strains have optimised their management of glycerol, their most important compatible solute. Experimental evolution therefore not only confirmed the role of potassium transport, glycerol management, and cell wall in survival at low water activity, but also demonstrated that fungi from extreme environments can further improve their growth rates under constant extreme conditions in a relatively short time and without large scale genomic rearrangements.

Unravel the Supremacy of Klebsiella variicola over Native Microbial Strains for Aroma-Enhancing Compound Production in Reconstituted Tobacco Concentrate through Metagenomic Analysis.

Sensory attributes strongly influence consumers' preferences for products. The inoculation of the Klebsiella variicola H8 strain in a reconstituted tobacco leaf concentrate (RTLC) solution increased neutral aroma-enhancing compound (NAEC) production by 45%, decreased the nicotine level by 25%, decreased the water-soluble total sugar content by ~36%, and improved the sensory quality by 5.71%. The production of NAECs such as dihydrokiwi lactone (DHKL: 192.86%), 1,2,3,4-tetrahydro-1,1,6-trimethylnaphthalene (THTMN: 177.77%), 2,4-di-tert-butylphenol (DTBP: 25%), 4-oxoisofolkone (OIFK: 116.66%,) 1,9-heptadecadiene-4,6-diyn-3-ol (HDD: 116.67%), β-damastrone (BDS: 116.67), and megastigmatrienone A (MSTA: 116.67%) was increased. A metagenomics analysis of the microbial community in the fermented RTLC (FRTLC) was performed to elucidate the mechanism by which NAECs were produced. As a result, 24 groups of functional genes were identified, and among them, five families of carbohydrate-active enzymes, (i) glycoside hydrolase (GH), (ii) glycosyltransferase (GT), (iii) polysaccharide lyase (PL), (iv) carbohydrate esterase (CE), and (v) auxiliary active enzyme (AA), were found to be positively correlated with the production of NAECs. However, among the GHs, the GHs annotated from the H8 strain chromosome displayed the highest relative abundance and a positive correlation with the production of NAECs. Specifically, the GH13-14, GH13-20, GH13-38, GH13-25, GH13-10, GH42, and GH28 genes of the H8 strain were relatively more abundant and were key contributors to the production of NAECs. The correlation analyses revealed that the H8 strain plays a leading role among all the microorganisms in FRTLC in the production of NAECs. Our findings support the application of Klebsiella variicola in NAEC production and a reduction in nicotine content in tobacco products.

AgeMeta: Quantitative Gene Expression Database of Mammalian Aging

AgeMeta is a database that provides systemic and quantitative description of mammalian aging at the level of gene expression. It encompasses transcriptomic changes with age across various tissues of humans, mice, and rats, based on a comprehensive meta-analysis of 122 publicly available gene expression datasets from 26 studies. AgeMeta provides an intuitive visual interface for quantification of aging-associated transcriptomics at the level of individual genes and functional groups of genes, allowing easy comparison among various species and tissues. Additionally, all the data in the database can be downloaded and analyzed independently. Overall, this work contributes to the understanding of the complex network of biological processes underlying mammalian aging and supports future advancements in this field. AgeMeta is freely available at: https://age-meta.com/.Graphic abstract

A de novo long-read genome assembly of the sacred datura plant (Datura wrightii) reveals a role of tandem gene duplications in the evolution of herbivore-defense response

The sacred datura plant (Solanales: Solanaceae: Datura wrightii) has been used to study plant–herbivore interactions for decades. The wealth of information that has resulted leads it to have potential as a model system for studying the ecological and evolutionary genomics of these interactions. We present a de novo Datura wrightii genome assembled using PacBio HiFi long-reads. Our assembly is highly complete and contiguous (N50 = 179Mb, BUSCO Complete = 97.6%). We successfully detected a previously documented ancient whole genome duplication using our assembly and have classified the gene duplication history that generated its coding sequence content. We use it as the basis for a genome-guided differential expression analysis to identify the induced responses of this plant to one of its specialized herbivores (Coleoptera: Chrysomelidae: Lema daturaphila). We find over 3000 differentially expressed genes associated with herbivory and that elevated expression levels of over 200 genes last for several days. We also combined our analyses to determine the role that different gene duplication categories have played in the evolution of Datura-herbivore interactions. We find that tandem duplications have expanded multiple functional groups of herbivore responsive genes with defensive functions, including UGT-glycosyltranserases, oxidoreductase enzymes, and peptidase inhibitors. Overall, our results expand our knowledge of herbivore-induced plant transcriptional responses and the evolutionary history of the underlying herbivore-response genes.

RpoS-Regulated Genes and Phenotypes in the Phytopathogenic Bacterium Pectobacterium atrosepticum.

The alternative sigma factor RpoS is considered to be one of the major regulators providing stress resistance and cross-protection in bacteria. In phytopathogenic bacteria, the effects of RpoS have not been analyzed with regard to cross-protection, and genes whose expression is directly or indirectly controlled by RpoS have not been determined at the whole-transcriptome level. Our study aimed to determine RpoS-regulated genes and phenotypes in the phytopathogenic bacterium Pectobacterium atrosepticum. Knockout of the rpoS gene in P. atrosepticum affected the long-term starvation response, cross-protection, and virulence toward plants with enhanced immune status. The whole-transcriptome profiles of the wild-type P. atrosepticum strain and its ΔrpoS mutant were compared under different experimental conditions, and functional gene groups whose expression was affected by RpoS were determined. The RpoS promoter motif was inferred within the promoter regions of the genes affected by rpoS deletion, and the P. atrosepticum RpoS regulon was predicted. Based on RpoS-controlled phenotypes, transcriptome profiles, and RpoS regulon composition, the regulatory role of RpoS in P. atrosepticum is discussed.

Genomic Insights on the Carbon-Negative Workhorse: Systematical Comparative Genomic Analysis on 56 Synechococcus Strains.

Synechococcus, a type of ancient photosynthetic cyanobacteria, is crucial in modern carbon-negative synthetic biology due to its potential for producing bioenergy and high-value products. With its high biomass, fast growth rate, and established genetic manipulation tools, Synechococcus has become a research focus in recent years. Abundant germplasm resources have been accumulated from various habitats, including temperature and salinity conditions relevant to industrialization. In this study, a comprehensive analysis of complete genomes of the 56 Synechococcus strains currently available in public databases was performed, clarifying genetic relationships, the adaptability of Synechococcus to the environment, and its reflection at the genomic level. This was carried out via pan-genome analysis and a detailed comparison of the functional gene groups. The results revealed an open-genome pattern, with 275 core genes and variable genome sizes within these strains. The KEGG annotation and orthology composition comparisons unveiled that the cold and thermophile strains have 32 and 84 unique KO functional units in their shared core gene functional units, respectively. Each KO functional unit reflects unique gene families and pathways. In terms of salt tolerance and comparative genomics, there are 65 unique KO functional units in freshwater-adapted strains and 154 in strictly marine strains. By delving into these aspects, our understanding of the metabolic potential of Synechococcus was deepened, promoting the development and industrial application of cyanobacterial biotechnology.

Транскрипционные факторы в скелетной мышце человека, ассоциированные с однократным и регулярными силовыми упражнениями

Skeletal muscle plasticity is the ability to change morphofunctional properties in response to changes in contractile activity. Strength training increases the size of muscle fibers and maximum strength with the activation of protein synthesis. Regulation of these changes at the gene level has not been investigated properly. This study aimed to identify transcription factors associated with changes in the transcriptome of the human skeletal muscle in the context of single and regular strength exercises. We assessed changes in the transcriptomic profile of m. vastus lateralis of 10 young men (mean age 23 (20.8 - 25.9) years) before and after 12-week leg extensor muscles strength training course, as well as before, 8 and 24 hours after a single exercise. Transcriptomic profiling involved RNA sequencing, search for binding motifs and the associated transcription factors. Bioinformatic methods of statistics, FastQC, GraphPad Prizm 8, DAVID, R enabled analysis of the data acquired. The strength training course resulted in the enrichment of the functional groups of genes "secreted proteins", "extracellular matrix" and "basal membrane" (p &lt; 0.05). Transcriptomic responses and the associated transcription factors differed 8 and 24 hours after a single session as well as after regular training sessions. Transcription factors involved in adjustment to regular and one-time loads participate in myogenesis, angiogenesis, regulation of fiber phenotype, proteostasis and other processes. Thus, regulation of gene expression during adjustment to the resistance training loads is a complex process that involves many transcription factors with different functions. Investigation of the role played by these factors in the context of adjustment to exercising is a potentially rewarding task.

Ancient roots: A Cambrian explosion of autism susceptibility genes.

Functional gene groups often share unique evolutionary patterns. The present study addresses whether autism susceptibility genes, which frequently share functional overlap, display unusual gene age and conservation patterns compared to other gene groups. Using phylostratigraphically-derived and other genetic data, the investigator explores average gene age, Ohnolog status, evolutionary rate, variation intolerance, and numbers of protein-protein (PPI) interactions across autism susceptibility, nervous system, developmental regulatory, immune, housekeeping, and luxury gene groups. Autism susceptibility genes are unusually old compared to controls, many genes having radiated in the Cambrian period in early vertebrates from whole genome duplication events. They are also tightly conserved across the animal kingdom, are highly variation intolerant, and have more PPI than other genes-all features suggesting extreme dosage sensitivity. The results of the current study indicate that autism susceptibility genes display unique radiation and conservation patterns, which may be a reflection of the major transitions in nervous system evolution that were occurring in early animals and which are still foundational in brain development today.

AMEND: active module identification using experimental data and network diffusion

BackgroundMolecular interaction networks have become an important tool in providing context to the results of various omics experiments. For example, by integrating transcriptomic data and protein–protein interaction (PPI) networks, one can better understand how the altered expression of several genes are related with one another. The challenge then becomes how to determine, in the context of the interaction network, the subset(s) of genes that best captures the main mechanisms underlying the experimental conditions. Different algorithms have been developed to address this challenge, each with specific biological questions in mind. One emerging area of interest is to determine which genes are equivalently or inversely changed between different experiments. The equivalent change index (ECI) is a recently proposed metric that measures the extent to which a gene is equivalently or inversely regulated between two experiments. The goal of this work is to develop an algorithm that makes use of the ECI and powerful network analysis techniques to identify a connected subset of genes that are highly relevant to the experimental conditions.ResultsTo address the above goal, we developed a method called Active Module identification using Experimental data and Network Diffusion (AMEND). The AMEND algorithm is designed to find a subset of connected genes in a PPI network that have large experimental values. It makes use of random walk with restart to create gene weights, and a heuristic solution to the Maximum-weight Connected Subgraph problem using these weights. This is performed iteratively until an optimal subnetwork (i.e., active module) is found. AMEND was compared to two current methods, NetCore and DOMINO, using two gene expression datasets.ConclusionThe AMEND algorithm is an effective, fast, and easy-to-use method for identifying network-based active modules. It returned connected subnetworks with the largest median ECI by magnitude, capturing distinct but related functional groups of genes. Code is freely available at https://github.com/samboyd0/AMEND.

Groundwater table fluctuation: A driving force affecting nitrogen transformation in nitrate-contaminated groundwater

Groundwater table fluctuation alters the biochemical environment and nitrogen transformation, leading to periodic changes in groundwater nitrate concentration. A microcosm experiment of groundwater table fluctuation was designed to explore the underlying mechanism. The dissolved oxygen (DO), bacterial community, functional gene groups and associated nitrogen transformation were investigated based on field scenario. The results showed that groundwater rising reduced the average nitrate concentration, while falling aggravated it. Owing to the variations in groundwater table, the DO concentration underwent periodic changes. Furthermore, the abundance and diversity of soil bacteria were enriched and the structure of the microbial community was altered. Nitrogen transformation biomarkers such as Arthrobacter sp., Bacillus sp., Chloroflexi sp. and Acidobacteriota sp. as well as nitrogen transformation functional genes were identified. A structure equation model was established which demonstrated that groundwater table fluctuation altered DO and the dominant bacterial abundance, which in turn modified the functional gene groups and nitrogen transformation. This study broadens the understanding of how and to what extent groundwater table fluctuation affects nitrogen transformation and is vital for assessing and managing risks associated with groundwater nitrate contamination

Tropical lacustrine sediment microbial community response to an extreme El Niño event

Salinity can influence microbial communities and related functional groups in lacustrine sediments, but few studies have examined temporal variability in salinity and associated changes in lacustrine microbial communities and functional groups. To better understand how microbial communities and functional groups respond to salinity, we examined geochemistry and functional gene amplicon sequence data collected from 13 lakes located in Kiritimati, Republic of Kiribati (2° N, 157° W) in July 2014 and June 2019, dates which bracket the very large El Niño event of 2015–2016 and a period of extremely high precipitation rates. Lake water salinity values in 2019 were significantly reduced and covaried with ecological distances between microbial samples. Specifically, phylum- and family-level results indicate that more halophilic microorganisms occurred in 2014 samples, whereas more mesohaline, marine, or halotolerant microorganisms were detected in 2019 samples. Functional Annotation of Prokaryotic Taxa (FAPROTAX) and functional gene results (nifH, nrfA, aprA) suggest that salinity influences the relative abundance of key functional groups (chemoheterotrophs, phototrophs, nitrogen fixers, denitrifiers, sulfate reducers), as well as the microbial diversity within functional groups. Accordingly, we conclude that microbial community and functional gene groups in the lacustrine sediments of Kiritimati show dynamic changes and adaptations to the fluctuations in salinity driven by the El Niño-Southern Oscillation.

First genome-scale insights into the virulence of the snow mold causal fungus Microdochium nivale

Pink snow mold, caused by a phytopathogenic and psychrotolerant fungus, Microdochium nivale, is a severe disease of winter cereals and grasses that predominantly occurs under snow cover or shortly after its melt. Snow mold has significantly progressed during the past decade, often reaching epiphytotic levels in northern countries and resulting in dramatic yield losses. In addition, M. nivale gradually adapts to a warmer climate, spreading to less snowy territories and causing different types of plant diseases throughout the growing period. Despite its great economic importance, M. nivale is poorly investigated; its genome has not been sequenced and its crucial virulence determinants have not been identified or even predicted. In our study, we applied a hybrid assembly based on Oxford Nanopore and Illumina reads to obtain the first genome sequence of M. nivale. 11,973 genes (including 11,789 protein-encoding genes) have been revealed in the genome assembly. To better understand the genetic potential of M. nivale and to obtain a convenient reference for transcriptomic studies on this species, the identified genes were annotated and split into hierarchical three-level functional categories. A file with functionally classified M. nivale genes is presented in our study for general use. M. nivale gene products that best meet the criteria for virulence factors have been identified. The genetic potential to synthesize human-dangerous mycotoxins (fumonisin, ochratoxin B, aflatoxin, and gliotoxin) has been revealed for M. nivale. The transcriptome analysis combined with the assays for extracellular enzymatic activities (conventional virulence factors of many phytopathogens) was carried out to assess the effect of host plant (rye) metabolites on the M. nivale phenotype. In addition to disclosing plant-metabolite-upregulated M. nivale functional gene groups (including those related to host plant protein destruction and amino acid metabolism, xenobiotic detoxication (including phytoalexins benzoxazinoids), cellulose destruction (cellulose monooxygenases), iron transport, etc.), the performed analysis pointed to a crucial role of host plant lipid destruction and fungal lipid metabolism modulation in plant-M. nivale interactions.

Effect of low temperature on contributions of ammonia oxidizing archaea and bacteria to nitrous oxide in constructed wetlands

Constructed wetlands (CWs) have been widely used for ecological remediation of micro-polluted source water. Nitrous oxide (N2O) from CWs has caused great concern as a greenhouse gas. However, the contribution of ammonia oxidation driven by ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) to N2O emission, especially at low temperature, was unknown. This study aimed to quantify the contributions of AOA and AOB to N2O through lab-scale subsurface CWs. The N2O emission flux of CW at 8 °C was 1.23 mg m−2·h−1, significantly lower than that at 25 °C (1.92 mg m−2·h−1). The contribution of ammonia oxidation to N2O at 8 °C (33.04%) was significantly higher than that at 25 °C (24.17%). The N2O production from AOA increased from 1.91 ng N·g−1 at 25 °C to 4.11 ng N·g−1 soil at 8 °C and its contribution increased from 23.38% to 30.18% (P < 0.05). Low temperature impaired functional gene groups and inhibited the activity of AOB, resulting in its declined contribution. Based on the transcriptional analysis, AOA was less affected by low temperature, thus stably contributing to N2O. Moreover, community diversity and relationships of AOA were enhanced at 8 °C, while AOB declined. The results confirmed the significant contribution of AOA and demonstrated molecular mechanisms (higher activity and community stability) of the increased contribution of AOA to N2O at low temperature.