Selection Pressure Analysis Research Articles

Identification and Expression Analysis of the SKP1-Like Gene Family under Phytohormone and Abiotic Stresses in Apple (Malus domestica).

Ubiquitination participates in plant hormone signaling and stress response to adversity. SKP1-Like, a core component of the SCF (Skp1-Cullin-F-box) complex, is the final step in catalyzing the ubiquitin-mediated protein degradation pathway. However, the SKP1-Like gene family has not been well characterized in response to apple abiotic stresses and hormonal treatments. This study revealed that 17 MdSKP1-Like gene family members with the conserved domain of SKP1 were identified in apples and were unevenly distributed on eight chromosomes. The MdSKP1-Like genes located on chromosomes 1, 10, and 15 were highly homologous. The MdSKP1-like genes were divided into three subfamilies according to the evolutionary affinities of monocotyledons and dicotyledons. MdSKP1-like members of the same group or subfamily show some similarity in gene structure and conserved motifs. The predicted results of protein interactions showed that members of the MdSKP1-like family have strong interactions with members of the F-Box family of proteins. A selection pressure analysis showed that MdSKP1-Like genes were in purifying selection. A chip data analysis showed that MdSKP1-like14 and MdSKP1-like15 were higher in flowers, whereas MdSKP1-like3 was higher in fruits. The upstream cis-elements of MdSKP1-Like genes contained a variety of elements related to light regulation, drought, low temperature, and many hormone response elements, etc. Meanwhile, qRT-PCR also confirmed that the MdSKP1-Like gene is indeed involved in the response of the apple to hormonal and abiotic stress treatments. This research provides evidence for regulating MdSKP1-Like gene expression in response to hormonal and abiotic stresses to improve apple stress resistance.

Identification of the Maize LEA Gene Family and Its Relationship with Kernel Dehydration

Maize, the most widely planted and highest yielding of the three major crops in the world, requires the development and breeding of new varieties to accommodate the shift towards mechanized harvesting. However, the moisture content of kernels during harvest poses a significant challenge to mechanized harvesting, leading to seed breakage and increased storage costs. Previous studies highlighted the importance of LEA (Late Embryogenesis Abundant) members in regulating kernel dehydration. In this study, we aimed to gain a better understanding of the relationship between the LEA family and grain dehydration in maize. Through expression pattern analysis of maize, we identified 52 LEA genes (ZmLEAs) distributed across 10 chromosomes, organized into seven subgroups based on phylogenetic analysis, gene structure, and conserved motifs. Evolutionary and selective pressure analysis revealed that the amplification of ZmLEA genes primarily resulted from whole-genome or fragment replication events, with strong purifying selection effects during evolution. Furthermore, the transcriptome data of kernels of two maize inbred lines with varying dehydration rates at different developmental stages showed that 14 ZmLEA genes were expressed differentially in the two inbreds. This suggested that the ZmLEA genes might participate in regulating the kernel dehydration rate (KDR) in maize. Overall, this study enhances our understanding of the ZmLEA family and provides a foundation for further research into its role in regulating genes associated with grain dehydration in maize.

Emerging porcine Enterovirus G infections, epidemiological, complete genome sequencing, evolutionary and risk factor analysis in India

The current study reports the in-depth analysis of the epidemiology, risk factors, and molecular characterization of a complete genome of Enterovirus G (EV-G) isolated from Indian pigs. We analysed several genes of EV-G isolates collected from various provinces in India, using phylogenetic analysis, recombination detection, SimPlot, and selection pressure analyses. Our analysis of 534 porcine faecal samples revealed that 11.61% (62/534) of the samples were positive for EV-G. While the G6 genotype was the most predominant, our findings showed that Indian EV-G strains also clustered with EV-G types G1, G6, G8, and G9. Furthermore, Indian EV-G strains exhibited the highest nucleotide similarity with Vietnamese (81.3%) and Chinese EV-G isolates (80.3%). Moreover, we identified a recombinant Indian EV-G strain with a putative origin from a Japanese isolate and South Korean EV-G isolate. In summary, our findings provide significant insights into the epidemiology, genetic diversity, and evolution of EV-G in India.

Phylomitogenomics elucidates the evolution of symbiosis in Thoracotremata (Decapoda: Cryptochiridae, Pinnotheridae, Varunidae).

Thoracotremata belong to the large group of "true" crabs (infraorder Brachyura), and they exhibit a wide range of physiological and morphological adaptations to living in terrestrial, freshwater and marine habitats. Moreover, the clade comprises various symbiotic taxa (Aphanodactylidae, Cryptochiridae, Pinnotheridae, some Varunidae) that are specialised in living with invertebrate hosts, but the evolutionary history of these symbiotic crabs is still partially unresolved. Here we assembled and characterised the complete mitochondrial genomes (hereafter mitogenomes) of three gall crab species (Cryptochiridae): Kroppcarcinus siderastreicola, Opecarcinus hypostegus and Troglocarcinus corallicola. A phylogenetic tree of the Thoracotremata was reconstructed using 13 protein-coding genes and two ribosomal RNA genes retrieved from three new gall crab mitogenomes and a further 72 available thoracotreme mitogenomes. Furthermore, we applied a comparative analysis to characterise mitochondrial gene order arrangement, and performed a selection analysis to test for selective pressure of the protein-coding genes in symbiotic Cryptochiridae, Pinnotheridae, and Varunidae (Asthenognathus inaequipes and Tritodynamia horvathi). The results of the phylogenetic reconstruction confirm the monophyly of Cryptochiridae, which clustered separately from the Pinnotheridae. The latter clustered at the base of the tree with robust branch values. The symbiotic varunids A. inaequipes and T. horvathi clustered together in a clade with free-living Varunidae species, highlighting that symbiosis in the Thoracotremata evolved independently on multiple occasions. Different gene orders were detected in symbionts and free-living species when compared with the ancestral brachyuran gene order. Lastly, the selective pressure analysis detected two positively selected sites in the nad6 gene of Cryptochiridae, but the evidence for positive selection in Pinnotheridae and A. inaequipes and T. horvathi was weak. Adaptive evolution of mitochondrial protein-coding genes is perhaps related to the presumably higher energetic demands of a symbiotic lifestyle.

Analysis of the Complete Mitochondrial Genome of Pteronura brasiliensis and Lontra canadensis.

P. brasiliensis and L. canadensis are two otter species, which successfully occupied semi-aquatic habitats and diverged from other Mustelidae. Herein, the full-length mitochondrial genome sequences were constructed for these two otter species for the first time. Comparative mitochondrial genome, selection pressure, and phylogenetic independent contrasts (PICs) analyses were conducted to determine the structure and evolutionary characteristics of their mitochondrial genomes. Phylogenetic analyses were also conducted to confirm these two otter species' phylogenetic position. The results demonstrated that the mitochondrial genome structure of P. brasiliensis and L. canadensis were consistent across Mustelidae. However, selection pressure analyses demonstrated that the evolutionary rates of mitochondrial genome protein-coding genes (PCGs) ND1, ND4, and ND4L were higher in otters than in terrestrial Mustelidae, whereas the evolutionary rates of ND2, ND6, and COX1 were lower in otters. Additionally, PIC analysis demonstrated that the evolutionary rates of ND2, ND4, and ND4L markedly correlated with a niche type. Phylogenetic analysis showed that P. brasiliensis is situated at the base of the evolutionary tree of otters, and then L. canadensis diverged from it. This study suggests a divergent evolutionary pattern of Mustelidae mitochondrial genome PCGs, prompting the otters' adaptation to semi-aquatic habitats.

Genome-wide analysis of the LAZ1 gene family in Gossypium hirsutum.

As the world's leading fiber crop and a major oil-producing crop, cotton fiber yield and fiber quality are affected by environmental stresses, especially heat, drought and salinity. The LAZ1 (Lazarus 1) family genes are responsive to abscisic acid, drought, and salt treatments. Currently, mining and functional analyses of LAZ1 family genes in cotton have not been reported. In this study, 20 GhLAZ1 genes, designated GhLAZ1-1 - GhLAZ1-20, were identified in the genome of Gossypium hirsutum through the construction of an HMM model, and their molecular properties, chromosomal localization, phylogeny, gene structure, evolutionary selection pressure, promoter cis elements and gene expression under salt stress were analyzed. With the exception of GhLAZ1-17 and GhLAZ1-20, the remaining 18 GhLAZ1 genes were unevenly localized on 13 chromosomes in G. hirsutum; evolutionary analysis showed that these genes could be divided into three subfamilies; and evolutionary selection pressure analysis demonstrated that the GhLAZ1 genes were all under purifying selection. Many elements related to light responses, hormone responses, and abiotic stresses were predicted on the GhLAZ1 family gene promoters, and real-time quantitative PCR results showed that GhLAZ1-2, GhLAZ1-8, and GhLAZ1-18 were upregulated significantly in salt-treated cotton leaves. Our results suggested that GhLAZ1 genes were involved in the salt tolerance mechanism in G. hirsutum and provided a reference for further exploring the function and molecular mechanism of LAZ1 genes.

Epidemiologic and Genomic Characterizations of Porcine Kobuviruses in Diarrheic and Healthy Pigs.

Porcine kobuvirus (PKV) is an enteric virus commonly detected in both diarrheic and healthy pigs. Little is known about the role of PKV in enteric diseases. In this study, an epidemiological investigation based on 324 intestinal samples collected from six provinces of China during the period of 2018 to 2022 was performed, and showed that PKV has an overall 65.43% (212/324) positive rate. Noticeably, 89.47% (17/19) of PKV and porcine epidemic diarrhea virus (PEDV) double-positive pigs were clinically diseased, while 91.71% (177/193) of PKV-positive but PEDV-negative pigs were clinically healthy, suggesting that PKV infection in itself is unlikely to cause enteric diseases. In addition, three PKV genomes were obtained from both diseased and healthy pigs. Phylogenetic analysis showed that Chinese PKV strains could be divided into three groups (SH-W-CHN-like, S-1-HUN-like and JXAT2015-like strains). All three obtained PKV genomes belong to SH-W-CHN-like strains and JSYZ1806-158 was detected as a recombinant virus. Furthermore, multiple comparisons showed that nucleotide similarities are clearly lower than amino acid similarities for PKV polyproteins. Selective pressure analysis indicated that Chinese PKV polyproteins are predominantly under negative selection. Overall, this study provided new insights into the prevalence and evolution of PKV in both diarrheic and healthy pigs in China.

Re-identification and characterization of grass carp Ctenopharyngodon idella TLR20

Toll-like receptors (TLRs) play a crucial role in the recognition of microbial-associated molecular patterns in the innate immune system. Fish TLRs have undergone significant gene expansion to adapt to complex aquatic environments. Among them, TLR20 from the TLR11 family actively responds to viral and bacterial invasions. Previous studies have reported two TLR20s in grass carp (Ctenopharyngodon idella), and in this study, we revised this conclusion. Based on the latest grass carp genome, we identified a new TLR20 member. These three TLR20s are arranged in tandem on chromosome 9, indicating that they are generated by gene duplication events. They were renamed CiTLR20.1 to CiTLR20.3 based on their chromosomal positions. The CiTLR20s in C. idella exhibit higher similarities with those in Danio rerio, Cyprinus carpio, and Megalobrama amblycephala, and lower similarities with those in other distantly related fish species. Selective pressure analysis revealed low conservation and negative evolution of TLR20s during evolution. The 3D structures of the three TLR20s showed significant differences, reflecting functional variations and different downstream adaptor molecule recruitment. Transcriptome data revealed tissue distribution differences of TLR20s, with TLR20.1 showing relatively low expression levels in all the tissues, while TLR20.2 and TLR20.3 showed higher expression in the head kidney, spleen, and gill. Additionally, TLR20.2 and TLR20.3 actively responded to GCRV-II infection, with higher upregulation of TLR20.2 in response to Aeromonas hydrophila challenge. In conclusion, this study corrected the number of grass carp TLR20 members and analyzed TLR20 from an evolutionary and structural perspective, exploring its role in antiviral and antibacterial defense. This study provides reference for future research on fish TLR20.

Evolution, genetic recombination, and phylogeography of goose parvovirus

Goose parvovirus (GPV) has garnered global attention due to its association with severe symptoms in waterfowl. However, the process underlying the global emergence and spread of GPV remains largely elusive. In this study, we illustrated the evolutionary characteristics of GPVs from a global perspective using phylogenetic analysis, recombination analysis, selection pressure analysis, and phylogeographic analysis. Our findings indicate that GPV and muscovy duck parvovirus (MDPV) diverge into two distinct branches. Within GPV, there are two classifications: classical GPV (C-GPV) and novel GPV (N-GPV), each containing three subgroups, underscoring the significant genetic diversity of GPV. Recombination analysis revealed 11 recombination events, suggesting C-GPV, N-GPV, and MDPV co-infections. Further, phylogeographic analysis revealed that China is an important exporter of GPV and that trade might serve as a potential transmission conduit. Nonetheless, a detailed understanding of its geographic transmission dynamics warrants further investigation due to the limited scope of current genomic data in our study. This study offers novel insights into the evolutionary state and spread of GPV, holding promise for informing preventive and containment strategies against GPV infection.

Assembly and comparative analysis of the complete mitochondrial genome of Isopyrum anemonoides (Ranunculaceae).

Ranunculaceae is a large family of angiosperms comprising 2500 known species-a few with medicinal and ornamental values. Despite this, only two mitochondrial genomes (mitogenomes) of the family have been released in GenBank. Isopyrum anemonoides is a medicinal plant belonging to the family Ranunculaceae, and its chloroplast genome has recently been reported; however, its mitogenome remains unexplored. In this study, we assembled and analyzed the complete mitochondrial genome of I. anemonoides and performed a comparative analysis against different Ranunculaceae species, reconstructing the phylogenetic framework of Isopyrum. The circular mitogenome of I. anemonoides has a length of 206,722 bp, with a nucleotide composition of A (26.4%), T (26.4%), C (23.6%), and G (23.6%), and contains 62 genes, comprising 37 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, and three ribosomal RNA (rRNA) genes. Abundantly interspersed repetitive and simple sequence repeat (SSR) loci were detected in the I. anemonoides mitogenome, with tetranucleotide repeats accounting for the highest proportion of SSRs. By detecting gene migration, we observed gene exchange between the chloroplast and mitogenome in I. anemonoides, including six intact tRNA genes, six PCG fragments, and fragments from two rRNA genes. Comparative mitogenome analysis of three Ranunculaceae species indicated that the PCG contents were conserved and the GC contents were similar. Selective pressure analysis revealed that only two genes (nad1 and rpl5) were under positive selection during their evolution in Ranunculales, and two specific RNA editing sites (atp6 and mttB) were detected in the I. anemonoides mitogenome. Moreover, a phylogenetic analysis based on the mitogenomes of I. anemonoides and the other 15 taxa accurately reflected the evolutionary and taxonomic status of I. anemonoides. Overall, this study provides new insights into the genetics, systematics, and evolution of mitochondrial evolution in Ranunculaceae, particularly I. anemonoides.

Characterization and phylogenetic analysis of complete chloroplast genome of cultivated Qinan agarwood

"Tangjie" leaves of cultivated Qinan agarwood were used to obtain the complete chloroplast genome using high-throughput sequencing technology. Combined with 12 chloroplast genomes of Aquilaria species downloaded from NCBI, bioinformatics method was employed to determine the chloroplast genome characteristics and phylogenetic relationships. The results showed that the chloroplast genome sequence length of cultivated Qinan agarwood "Tangjie" leaves was 174 909 bp with a GC content of 36.7%. A total of 136 genes were annotated, including 90 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. Sequence repeat analysis detected 80 simple sequence repeats(SSRs) and 124 long sequence repeats, with most SSRs composed of A and T bases. Codon preference analysis revealed that AUU was the most frequently used codon, and codons with A and U endings were preferred. Comparative analysis of Aquilaria chloroplast genomes showed relative conservation of the IR region boundaries and identified five highly variable regions: trnD-trnY, trnT-trnL, trnF-ndhJ, petA-cemA, and rpl32, which could serve as potential DNA barcodes specific to the Aquilaria genus. Selection pressure analysis indicated positive selection in the rbcL, rps11, and rpl32 genes. Phylogenetic analysis revealed that cultivated Qinan agarwood "Tangjie" and Aquilaria agallocha clustered together(100% support), supporting the Chinese origin of Qinan agarwood from Aquilaria agallocha. The chloroplast genome data obtained in this study provide a foundation for studying the genetic diversity of cultivated Qinan agarwood and molecular identification of the Aquilaria genus.

The evolution of bitter taste receptor gene in primates: Gene duplication and selection.

Bitter taste perception plays an important role in preventing animals from digesting poisonous and harmful substances. In primates, especially the Cercopithecidae species, most species feed on plants; thus, it is reasonable to speculate that most of the bitter taste receptor genes (T2Rs) of primates are under purifying selection to maintain the functional stability of bitter taste perception. Gene duplication has happened in T2Rs frequently, and what will be the fate of T2Rs copies is another question we are concerned about. To answer these questions, we selected the T2Rs of primates reported in another study and conducted corresponding selective pressure analyses to determine what kind of selective pressure was acting on them. Further, we carried out selective pressure analyses on gene copies and their corresponding ancestors by considering several possible situations. The results showed that among the 25 gene groups examined here, 15 groups are subject to purifying selection and others are under relaxed selection, with many positively selected sites detected. Gene copies existed in several groups, but only some groups (clade1_a1-b2, clade1_c-c2, clade1_d1-d3, clade1_f1-f2, T2R10, T2R13, and T2R42) have positively selected sites, inferring that they may have some relation to functional divergence. Taken together, T2Rs in primates are under diverse selective pressures, and most gene copies are subject to the same selective pressures. In such cases, the copies may be just to keep the function conservative, and more copies can increase the quantity of the bitter taste receptor, raise the efficiency of bitter substance recognition, and finally enhance the fitness of feeding during the evolutionary course of primates. This study can improve our understanding of T2Rs evolution in primates.

Complete mitogenome of Nycteribia allotopa Speiser, 1901 (Diptera, Hippoboscoidea, Nycteribiidae) and comparative analysis of mitochondrial genomes of Nycteribiidae.

In recent years, the global pandemic of bat-associated pathogens has led to increasing attention on bat ectoparasites. Numerous studies have identified human-associated pathogens in Nycteribiidae, indicating their potential as vectors. In this study, the first complete sequencing of the mitochondrial genome of Nycteribia allotopa Speiser, 1901 was sequenced and analyzed. We also compared the mitochondrial sequences of N. allotopa with those available in the database for other Nycteribiidae species. The complete mitochondrial genome of N. allotopa was found to be 15,161bp in size with an A+T content of 82.49%. Nucleotide polymorphism analysis of 13 protein-coding genes from five species of Nycteribiidae showed that nad6 exhibited the most significant variation, while cox1 was the most conserved. Furthermore, selection pressure analysis revealed cox1 to exhibit the strongest purifying selection, while atp8, nad2, nad4L, and nad5 showed slightly looser purifying selection. Pairwise genetic distances indicated that cox1 and cox2 were evolving comparatively slowly, whereas atp8, nad2, and nad6 were evolving comparatively quickly. Phylogenetic trees constructed using Bayesian inference and maximum likelihood methods demonstrated that all four families within the superfamily Hippoboscoidea clustered into one branch each, indicating their monophyly. N. allotopa was found to be most closely related to the same genus N. parvula. This study significantly enriches the molecular database for Nycteribiidae and provides invaluable reference data for future species identification, phylogenetic analysis, and exploration of their potential as vectors for human-associated pathogens.

Phylodynamics of dengue virus 2 in Nicaragua leading up to the 2019 epidemic reveals a role for lineage turnover

BackgroundDengue is a mosquito-borne viral disease posing a significant threat to public health. Dengue virus (DENV) evolution is often characterized by lineage turnover, which, along with ecological and immunological factors, has been linked to changes in dengue phenotype affecting epidemic dynamics. Utilizing epidemiologic and virologic data from long-term population-based studies (the Nicaraguan Pediatric Dengue Cohort Study and Nicaraguan Dengue Hospital-based Study), we describe a lineage turnover of DENV serotype 2 (DENV-2) prior to a large dengue epidemic in 2019. Prior to this epidemic, Nicaragua had experienced relatively low levels of DENV transmission from 2014 to 2019, a period dominated by chikungunya in 2014/15 and Zika in 2016.ResultsOur phylogenetic analyses confirmed that all Nicaraguan DENV-2 isolates from 2018 to 2019 formed their own clade within the Nicaraguan lineage of the Asian/American genotype. The emergence of the new DENV-2 lineage reflects a replacement of the formerly dominant clade presiding from 2005 to 2009, a lineage turnover marked by several shared derived amino acid substitutions throughout the genome. To elucidate evolutionary drivers of lineage turnover, we performed selection pressure analysis and reconstructed the demographic history of DENV-2. We found evidence of adaptive evolution by natural selection at the codon level as well as in branch formation.ConclusionsThe timing of its emergence, along with a statistical signal of adaptive evolution and distinctive amino acid substitutions, the latest in the NS5 gene, suggest that this lineage may have increased fitness relative to the prior dominant DENV-2 strains. This may have contributed to the intensity of the 2019 DENV-2 epidemic, in addition to previously identified immunological factors associated with pre-existing Zika virus immunity.

Genetic variation of E6 and E7 genes of human papillomavirus type 16 from central China

BackgroundPersistent high-risk human papillomavirus (HR-HPV) infection is an important factor in the development of cervical cancer, and human papillomavirus type 16 (HPV-16) is the most common HR-HPV type worldwide. The oncogenic potential of HPV-16 is closely related to viral sequence variation.MethodsIn order to clarify the variant characteristics of HPV-16 E6 and E7 genes in central China, E6 and E7 sequences of 205 HPV‐16 positive samples were amplified by polymerase chain reaction. PCR products of E6 and E7 genes were further sequenced and subjected to variation analysis, phylogenetic analysis, selective pressure analysis and B-cell epitope prediction.ResultsTwenty-six single nucleotide variants were observed in E6 sequence, including 21 non-synonymous and 5 synonymous variants. Twelve single nucleotide variants were identified in E7 sequence, including 6 non-synonymous and 6 synonymous variants. Four new variants were found. Furthermore, nucleotide variation A647G (N29S) in E7 was significantly related to the higher risk of HSIL and cervical cancer. Phylogenetic analysis showed that the E6 and E7 sequences were all distributed in A lineage. No positively selected site was found in HPV-16 E6 and E7 sequences. Non-conservative substitutions in E6, H31Y, D32N, D32E, I34M, L35V, E36Q, L45P, N65S and K75T, affected multiple B-cell epitopes. However, the variation of E7 gene had little impact on the corresponding B-cell epitopes (score < 0.85).ConclusionHPV-16 E6 and E7 sequences variation data may contribute to HR-HPV prevention and vaccine development in Jingzhou, central China.

Comparative Mitogenome Analyses Uncover Mitogenome Features and Phylogenetic Implications of the Reef Fish Family Holocentridae (Holocentriformes).

To understand the molecular mechanisms and adaptive strategies of holocentrid fish, we sequenced the mitogenome of eight species within the family Holocentridae and compared them with six other holocentrid species. The mitogenomes were found to be 16,507-16,639 bp in length and to encode 37 typical mitochondrial genes, including 13 PCGs, two ribosomal RNAs, and 22 transfer RNA genes. Structurally, the gene arrangement, base composition, codon usage, tRNA size, and putative secondary structures were comparable between species. Of the 13 PCGs, nad6 was the most specific gene that exhibited negative AT-skews and positive GC-skews. Most of the genes begin with the standard codon ATG, except cox1, which begins with the codon GTG. By examining their phylogeny, Sargocentron and Neoniphon were verified to be closely related and to belong to the same subfamily Holocentrinae, while Myripristis and Ostichthys belong to the other subfamily Myripristinae. The subfamilies were clearly distinguished by high-confidence-supported clades, which provide evidence to explain the differences in morphology and feeding habits between the two subfamilies. Selection pressure analysis indicated that all PCGs were subject to purifying selection. Overall, our study provides valuable insight into the habiting behavior, evolution, and ecological roles of these important marine fish.

Complete genome analysis of echovirus 30 strains isolated from hand-foot-and-mouth disease in Yunnan province, China

BackgroundEchovirus 30 is prone to cause hand-foot-and-mouth disease in infants and children. However, molecular epidemiologic information on the spread of E30 in southwestern China remains limited. In this study, we determined and analyzed the whole genomic sequences of E30 strains isolated from the stools of patients with hand-foot-and-mouth disease in Yunnan Province, China, in 2019.MethodsE30 isolates were obtained from fecal samples of HFMD patients. The whole genomes were sequenced by segmented PCR and analyzed for phylogeny, mutation and recombination. MEGA and DNAStar were used to align the present isolates with the reference strains. The VP1 sequence of the isolates were analyzed for selection pressure using datamonkey server.ResultsThe complete genome sequences of four E30 were obtained from this virus isolation. Significant homologous recombination signals in the P2-3’UTR region were found in all four isolates with other serotypes. Phylogenetic analysis showed that the four E30 isolates belonged to lineage H. Comparison of the VP1 sequences of these four isolates with other E30 reference strains using three selection pressure analysis models FUBAR, FEL, and MEME, revealed a positive selection site at 133rd position.ConclusionsThis study extends the whole genome sequence of E30 in GenBank, in which mutations and recombinations have driven the evolution of E30 and further improved and enriched the genetic characteristics of E30, providing fundamental data for the prevention and control of diseases caused by E30. Furthermore, we demonstrated the value of continuous and extensive surveillance of enterovirus serotypes other than the major HFMD-causing viruses.

The heat shock protein 20 gene family in large yellow croaker (Larimichthys crocea): Identification, phylogenetic relationships, expression analyses

Large yellow croaker (Larimichthys crocea) is an economically important fish in China, but its aquaculture industry has been threatened by both biotic and abiotic stressors such as hypoxia and pathogens. In the current study, hsp20 genes were identified and analyzed systematically for the first time from the genome of large yellow croaker, and their roles in hypoxia response and Aeromonas hydrophila, Pseudomonas plecoglossicida infection were investigated. Herein, 11 hsp20 genes were identified and annotated, phylogenetic analysis and selection pressure analysis showed that the hsp20 genes were evolutionarily-constrained and their function was conserved among fishes. Besides, we observed the expression patterns of the hsp20 genes under hypoxia and two pathogens’ stress. In brief, seven, four, seven genes responded to hypoxia stress, A. hydrophila infection and P. plecoglossicida challenge, respectively, which indicated that they were involved in hypoxia and disease responses. Furthermore, pathogen- and time-specific pattern was observed after A. hydrophila and P. plecoglossicida infection whereas tissue-specific pattern was observed after hypoxia exposure, revealing that hsp20 genes showed differential functions in response to hypoxia and immune stress. Taken together, these results provided preliminary information for future analysis of the roles of hsp20 genes in both biotic and abiotic stress response in fish.

Molecular Evolutionary Analyses of the Spike Protein Gene and Spike Protein in the SARS-CoV-2 Omicron Subvariants.

To better understand the evolution of the SARS-CoV-2 Omicron subvariants, we performed molecular evolutionary analyses of the spike (S) protein gene/S protein using advanced bioinformatics technologies. First, time-scaled phylogenetic analysis estimated that a common ancestor of the Wuhan, Alpha, Beta, Delta variants, and Omicron variants/subvariants diverged in May 2020. After that, a common ancestor of the Omicron variant generated various Omicron subvariants over one year. Furthermore, a chimeric virus between the BM.1.1.1 and BJ.1 subvariants, known as XBB, diverged in July 2021, leading to the emergence of the prevalent subvariants XBB.1.5 and XBB.1.16. Next, similarity plot (SimPlot) data estimated that the recombination point (breakpoint) corresponded to nucleotide position 1373. As a result, XBB.1.5 subvariants had the 5' nucleotide side from the breakpoint as a strain with a BJ.1 sequence and the 3' nucleotide side as a strain with a BM.1.1.1 sequence. Genome network data showed that Omicron subvariants were genetically linked with the common ancestors of the Wuhan and Delta variants, resulting in many amino acid mutations. Selective pressure analysis estimated that the prevalent subvariants, XBB.1.5 and XBB.1.16, had specific amino acid mutations, such as V445P, G446S, N460K, and F486P, located in the RBD when compared with the BA.4 and BA.5 subvariants. Moreover, some representative immunogenicity-associated amino acid mutations, including L452R, F486V, R493Q, and V490S, were also found in these subvariants. These substitutions were involved in the conformational epitopes, implying that these mutations affect immunogenicity and vaccine evasion. Furthermore, these mutations were identified as positive selection sites. These results suggest that the S gene/S protein Omicron subvariants rapidly evolved, and mutations observed in the conformational epitopes may reduce the effectiveness of the current vaccine, including bivalent vaccines such as mRNA vaccines containing the BA.4/BA.5 subvariants.

Genome-informed investigation of the molecular evolution and genetic reassortment of severe fever with thrombocytopenia syndrome virus.

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a viral pathogen causing significant clinical signs from mild fever with thrombocytopenia to severe hemorrhages. World Health Organization has paid special attention to the dramatic increase in human SFTS cases in China, Japan, and South Korea since the 2010s. The present study investigated the molecular evolution and genetic reassortment of SFTSVs using complete genomic sequences. We collected the complete genome sequences of SFTSVs globally isolated until 2019 (L segment, n = 307; M segment, n = 326; and S segment, n = 564) and evaluated the evolutionary profiles of SFTSVs based on phylogenetic and molecular selection pressure analyses. By employing a time-scaled Bayesian inference method, we found the geographical heterogeneity of dominant SFTSV genotypes in China, Japan, and South Korea around several centuries before and locally spread by tick-born spillover with infrequent long-distance transmission. Purifying selection predominated the molecular evolution of SFTSVs with limited gene reassortment and fixed substitution, but almost all three gene segments appeared to harbor at least one amino acid residue under positive selection. Specifically, the nonstructural protein and glycoprotein (Gn/Gc) genes were preferential selective targets, and the Gn region retained the highest number of positively selected residues. Here, the large-scale genomic analyses of SFTSVs improved prior knowledge of how this virus emerged and evolved in China, Japan, and South Korea. Our results highlight the importance of SFTSV surveillance in both human and non-human reservoirs at the molecular level to fight against fatal human infection with the virus.