Abstract Background Beauveria bassiana ( B. bassiana ) is a famous entomopathogenic fungus that could parasitize on hundreds of insect species, which are being used as an environmentally friendly mycoinsecticide. Nevertheless, the possible effect of genetic diversity of these B. bassiana isolates from different hosts on virulence has not been explored before. In order to explore that issue, we compared the genome sequences among seventeen B. bassiana isolates from 17 different insects using whole genome re-sequencing, with B. bassiana strain ARSEF 2860 as the reference genome. Results There were a total of 10,098 missense mutated genes, 720 positively selected genes were identified in 17 strains of B. bassiana . Among these, two genes with high frequency mutations encode the toxin-producing non-ribosomal peptide synthase (NRPS) protein. Seven genes undergoing positive selection were enriched in the two-component signaling pathway that is known to regulate the fungal toxicity. In addition, the domain changes of three positively selected genes are also directly related to the virulence plasticity. Besides, the functional categorization of mutated genes showed that most of them involved in the biological functions of toxic proteins involved in. Conclusions Based on our data, our results indicate that several mutated genes and positively selected genes may underpin virulence of B. bassiana towards hosts during infection process, which provide an insight into the potential effects of natural variation on the virulence of B. bassiana , which will be useful in screening out potential virulence factors in B. bassiana .
Chromosomal replicators in budding yeast contain an autonomously replicating sequence (ARS) that functions in a plasmid, but certain ARSs are silent as replication origins in their natural chromosomal context.In chromosome III, the HML ARS cluster (ARS302-ARS303-ARS320) and ARS301 flank the transcriptionally silent mating-type locus HML, and all of these ARSs are silent as replication origins.ARS301 and ARS302 function in transcriptional silencing mediated by the origin recognition complex (ORC) and a heterochromatin structure, while the functions of ARS303 and ARS320 are not known.In this work, we discovered replication fork pause sites at the HML ARS cluster and ARS301 by analyzing DNA replication intermediates from the chromosome via two-dimensional gel electrophoresis.The replication fork pause at the HML ARS cluster was independent of cis-and trans-acting mutations that abrogate transcriptional silencing at HML. Deletion of the HML ARS cluster led to loss of the pause site.Insertion of a single, heterologous ARS (ARS305) in place of the HML ARS cluster reconstituted the pause site, as did multiple copies of DNA elements (A and B1) that bind ORC.The orc2-1 mutation, known to alter replication timing at origins, did not detectably affect the pause but activated the silent origin at the HML ARS cluster in a minority of cells.Delaying the time of fork arrival at HML led to the elimination of the pause sites at the HML ARS cluster and at the copy of ARS305 inserted in place of the cluster.Loss of the pause sites was accompanied by activation of the silent origins in the majority of cells.Thus, replication fork movement near HML pauses at a silent origin which is competent for replication initiation but kept silent through Orc2p, a component of the replication initiator.Possible functions for replication fork pause sites in checkpoints, S-phase regulation, mating-type switching, and transcriptionally silent heterochromatin are discussed.
ABSTRACT While assays of many antifolate inhibitors for dihydrofolate reductase (DHFR) have been performed using rat DHFR as a target, neither the sequence nor the structure of rat DHFR is known. Here, we report the isolation of the rat DHFR gene through screening of a rat liver cDNA library. The rat liver DHFR gene has an open reading frame of 561 bp encoding a protein of 187 amino acids. Comparisons of the rat enzyme with those from other species indicate a high level of conservation at the primary sequence level and more so for the amino acid residues comprising the active site of the enzyme. Expression of the rat DHFR gene in bacteria produced a recombinant protein with high enzymatic activity. The recombinant protein also paralleled the human enzyme with respect to the inhibition by most of the antifolates tested with PT652 and PT653 showing a reversal in their patterns. Our results indicated that rat DHFR can be used as a model to study antifolate compounds as potential drug candidates. However, variations between rat and human DHFR enzymes, coupled with unique features in the inhibitors, could lead to the observed differences in enzyme sensitivity and selectivity.
Diapause is an adaptive dormancy strategy by which arthropods endure extended periods of adverse climatic conditions. Seasonal variation in larval diapause initiation and duration in the Asian corn borer, Ostrinia furnacalis, influences adult mating generation number (voltinism) across local environmental conditions. Degree of mating period overlap between sympatric voltine ecotypes influence hybridization level, but impact on O. furnacalis population genetic structure and evolution of divergent adaptive phenotypes remains uncertain. Genetic differentiation was estimated between voltine ecotypes collected from 8 locations in Jilin Province, China [3 single generation (univoltine), 3 two generation (bivoltine), and 2 sympatric locations] in 2014. Mitochondrial cytochrome c oxidase subunit I (COI) haplotypes were partitioned into groups corresponding to historically allopatric univoltine or bivoltine population origins using Bayesian and phylogenetic clustering methods. Haplotypes from sympatric locations were clustered more-closely to bivoltine locations, but influenced by local demographics. Despite this COI haplotype divergence between ecotypes, results were confounded by significant adherence to an isolation-by-distance model. Additionally, analyses of single nucleotide polymorphism (SNP) genotype data implicate voltinism, as opposed to geographic distance, as contributing to low but significant levels of variation among locations. Regardless, only 11 of 257 SNP loci were predicted to be under selection, suggesting population genetic homogenization except at loci proximal to factors putatively responsible for locally adaptive or voltinism-specific traits. These findings provide evidence that divergent voltine ecotypes may be maintained in allopatric and sympatric areas despite relatively high rates of nuclear gene flow, yet influence of voltinism on maintaining observed haplotype divergence remains unresolved.
Abstract Molecular techniques are powerful tools that can address many research problems in insect ecology. Mitochondrial DNA (mtDNA) is a widely used molecular marker. It is easy to use and has favorable biological properties, such as near-neutrality, lack of recombination, and a clock-like evolutionary rate. However, there are some issues involved when using mtDNA data in population genetics, species delimitation, and estimating the evolutionary history of populations and species. Exceptions to the simplicity of mitochondrial inheritance and other limitations include small effective population sizes, maternal inheritance, and complex evolutionary processes. Combining mtDNA and nuclear DNA markers can improve the power of molecular data to test phylogenetic and phylogeographic hypotheses. We review the applications of mtDNA in insect ecology and conclude that a better understanding of the properties of mitochondria is essential for the application of mtDNA.
Understanding the variation of rock permeability with temperature and confining pressure is the foundation for projects such as high-level radioactive waste disposal, deep geothermal exploitation, and carbon dioxide storage. This paper presents an experimental study of the permeability evolution of thermally damaged Beishan granite under effective stress. The results show that temperature has a significant impact on the permeability of granite, and there is an obvious threshold temperature (400–500 °C), initial permeability and permeability change rate increased gradually with temperature. The permeability of Beishan granite shows non-linear decreasing trend with the increase of effective stress, ultimately tending towards stability. The microstructure of granite after thermal damage can be observed by scanning electron microscopy and used to assist in explaining the microscopic mechanism of permeability changes. The proposed a new granite permeability prediction model, which integrates permeability with temperature and effective stress, providing an important reference for the safety of high-level radioactive waste disposal.
Objective
To observe the changes of serum clara cell protein-16 (CC-16) and monocyte chemotaxis protein-1 (MCP-1) level in patients with acute respiratory distress syndrome (ARDS) and to explore their relationship with the disease severity and prognosis of ARDS.
Methods
One hundred and fourteen patients with ARDS who were admitted to Changzhi People′s hospital from January 2017 to March 2018 were selected as the subjects.They were divided into mild group (n=37), moderate group (n=41) and severe group (n=36) according to the severity of ARDS.Sixty healthy persons in out-patient examination were selected as control group.The survival situation of patients in 4 weeks were recorded, the patients were divided into survival group (n=65) and death group (n=49) according to their survival situation.The age, gender, body mass index (BMI), smoking history, acute physiology and acute physiology and chronic health evaluation II (APACHE II) score, sequential organ failure assessment (SOFA) score, serum CC-16 and MCP-1 level were analyzed in each group.The relationship between serum CC-16, MCP-1 level and disease and prognosis of patients with ARDS were analyzed.
Results
With the increase of disease severity, APACHE II score, SOFA score and serum CC-16, MCP-1 level in patients with ARDS were significantly increased.The differences were statistically significant (F=1 216.886, 1 339.247, 290.879, 417.262; all P=0.000). The APACHE II score, SOFA score and serum CC-16, MCP-1 levels in the death group were (22.13±2.47) scores, (15.09±1.97) scores, (23.85±4.27) μg/L, (36.64±5.21) ng/L respectively, which were significantly higher than those in the survival group (18.25±2.35) scores, (13.23±2.03) scores, (17.34±4.13) μg/L, (27.93±4.88) ng/L, the differences were statistically significant (t=8.538, 4.905, 8.211, 9.146; all P=0.000). Pearson correlation analysis showed that there was a positive correlation between serum CC-16 level and MCP-1 level in patients with ARDS(r=0.589, P=0.000). Meanwhile, the CC-16, MCP-1 were positive correlation with APACHE II score, SOFA score and mortality (CC-16: r=0.504, 0.549, 0.472; P=0.000, 0.000, 0.012; MCP-1: r=0.493, 0.528, 0.435; P=0.006, 0.000, 0.025). APACHE II score (OR=3.083, 95%CI: 0.025-1.364, P<0.05), CC-16 (OR=5.403, 95%CI: 0.011-6.561, P<0.05) and MCP-1 (OR=2.892, 95%CI: 0.034-1.619, P<0.05) were all closely related to ARDS death.CC-16 independent detection, MCP-1 independent detection and the two combined detection predicted the under-curve area, sensitivity and specificity of ARDS patients with in 4 weeks were 0.830, 82.35% and 72.16%; 0.719, 79.25% and 72.19%; 0.866, 85.06% and 80.72% respectively.
Conclusion
CC-16, MCP-1 are abnormally high expression in serum of patients with ARDS, and its levels are closely related to the severity and prognosis of patients with ARDS.CC-16 combined with MCP-1 detection has high diagnostic value for patients with ARDS, which can be used as an effective index to judge the disease and prognosis of patients with ARDS.
Key words:
Acute respiratory distress syndrome; Clara cell secretory protein-16; Monocyte chemotaxis protein-1; Disease condition; Prognosis
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