New insights into the evolution of subtilisin-like serine protease genes in Pezizomycotina

<p>Abstract</p> <p>Background</p> <p>Subtilisin-like serine proteases play an important role in pathogenic fungi during the penetration and colonization of their hosts. In this study, we perform an evolutionary analysis of the subtilisin-like serine protease genes of subphylum Pezizomycotina to find if there are similar pathogenic mechanisms among the pathogenic fungi with different life styles, which utilize subtilisin-like serine proteases as virulence factors. Within Pezizomycotina, nematode-trapping fungi are unique because they capture soil nematodes using specialized trapping devices. Increasing evidence suggests subtilisin-like serine proteases from nematode-trapping fungi are involved in the penetration and digestion of nematode cuticles. Here we also conduct positive selection analysis on the subtilisin-like serine protease genes from nematode-trapping fungi.</p> <p>Results</p> <p>Phylogenetic analysis of 189 subtilisin-like serine protease genes from Pezizomycotina suggests five strongly-supported monophyletic clades. The subtilisin-like serine protease genes previously identified or presumed as endocellular proteases were clustered into one clade and diverged the earliest in the phylogeny. In addition, the cuticle-degrading protease genes from entomopathogenic and nematode-parasitic fungi were clustered together, indicating that they might have overlapping pathogenic mechanisms against insects and nematodes. Our experimental bioassays supported this conclusion. Interestingly, although they both function as cuticle-degrading proteases, the subtilisin-like serine protease genes from nematode-trapping fungi and nematode-parasitic fungi were not grouped together in the phylogenetic tree. Our evolutionary analysis revealed evidence for positive selection on the subtilisin-like serine protease genes of the nematode-trapping fungi.</p> <p>Conclusions</p> <p>Our study provides new insights into the evolution of subtilisin-like serine protease genes in Pezizomycotina. Pezizomycotina subtilisins most likely evolved from endocellular to extracellular proteases. The entomopathogenic and nematode-parasitic fungi likely share similar properties in parasitism. In addition, our data provided better understanding about the duplications and subsequent functional divergence of subtilisin-like serine protease genes in Pezizomycotina. The evidence of positive selection detected in the subtilisin-like serine protease genes of nematode-trapping fungi in the present study suggests that the subtilisin-like serine proteases may have played important roles during the evolution of pathogenicity of nematode-trapping fungi against nematodes.</p

Experimental investigation of insect deposition in lentic environments and implications for formation of Konservat Lagerstätten

Terrestrial insects are often remarkably well preserved in lacustrine Konservat Lagerstätten. However, the assumption that carcasses should sink fast through the water column seems contradictory as this scenario is unlikely due to excessive buoyancy and surface tension. The mechanisms that promote rapid and permanent emplacement onto the sediment surface (RPESS) of such terrestrial animal remains are not fully understood. Here we use taphonomic experiments to show that floating in water, growth of microbial biofilms and reception of rapid sediment load promote RPESS of terrestrial insect remains in lentic water bodies. Our results show that the optimum conditions for RPESS occur when terrestrial insects enter a lentic water body in articulation, experience brief decay in association with growth of microbes, then are buried rapidly by airborne volcanic ash. These results provide a model for preservation of articulated terrestrial insects and emphasize the importance of microbial activity and volcanism for insect preservation in lacustrine Konservat Lagerstätten

Palaeoenvironmental reconstruction and biostratinomic analysis of the Jurassic Yanliao Lagerstätte in northeastern China

The Middle-Upper Jurassic Yanliao Lagerstätte contains numerous exceptionally preserved fossils of aquatic and land organisms, including insects, salamanders, dinosaurs, pterosaurs and mammaliaforms. Despite extensive study of the diversity and evolutionary implications of the biota, the palaeoenvironmental setting and taphonomy of the fossils remain poorly understood. We reconstruct both the palaeoenvironment of the Daohugou area (one of the most famous Yanliao fossil areas), and the biostratinomy of the fossils. We use high-resolution stratigraphic data from field investigation and excavations to document in detail the stratigraphic succession, lithofacies, facies associations, and biostratinomic features of the Lagerstätte. Our results show that frequent volcanic eruptions generated an extensive volcaniclastic apron and lake(s) in the studied area. The frequent alternation of thin lacustrine deposits and thick volcaniclastic apron deposits indicates either that the studied area was located in the marginal regions of a single lake, where the frequent influx of volcaniclastic apron material caused substantial fluctuations in lake area and thus the frequent lateral alternation of the two facies, or that many short-lived lakes developed on the volcaniclastic apron. Most terrestrial insects were preserved in the laminated, normally graded siltstone, claystone and tuff facies that form many thin intervals with deposits of graded sandstone, siltstone and tuff in between. Within each interval the terrestrial insects occur in many laminae associated with abundant aquatic organisms, but are particularly abundant in some laminae that directly underlie tuff of fallout origin. Most of these terrestrial insects are interpreted to have been killed in the area adjacent to the studied palaeolake(s) during volcanic eruptions. Their carcasses were transported by influxes of fresh volcaniclastic material, primarily meteoric runoff and possibly minor distal pyroclastic flow into the palaeolake(s), and were buried in palaeolake deposits prior to extended decay probably due to a combination of rapid vertical settling, ash fall and water turbulence

The enhanced adsorption of layered double hydroxides modification from single to ternary metal for fluoride by TEA-assisted hydrothermal method

Layered double hydroxides (LDHs) have attracted increasing attention as promising candidates by anion exchanges and selective adsorption in the fluoride treatment field. In this study, three new ternary Zn-Co-Cr-LDHs were synthesized by primarily a one-step TEA-assisted hydrothermal process at various times. They were characterized by X-ray powder diffraction, thermogravimetric analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, N2 gas adsorption and desorption curves and zeta potential. The effects of dosage amount, reaction duration, initial solution pH, temperature, and co-existing ions were evaluated systematically for the Zn-Co-Cr-LDHs in fluoride removal process. Compared to Zn-LDHs and Zn-Co-LDHs, three Zn-Co-Cr-LDHs showed excellent adsorption performance for F- with maximum adsorption amounts of 108.87 mg/g, 97.27 mg/g, and 97.62 mg/g, respectively. The coexisting anions have less effect on the adsorption of F-. The introduction Cr3+ ion modulation in the Zn-Co-LDHs greatly improved the adsorption of fluoride ions. The kinetic process of fluoride ion adsorption is in accordance with the quasi-secondary kinetic model and the Elovich model, and the adsorption isotherm is in accordance with the Langmuir model. The quasi-secondary kinetic and Elovich models suggest that the process is chemisorption-controlled ion exchange adsorption. Zn-Co-Cr-LDHs are expected to have potential applications in fluoride removal process

Synergistic removal of mixed methyl orange/sunset yellow solution by the graded ZnCrNi-LDHs porous material

Layered bimetallic hydroxide (LDHs) nanomaterials have shown excellent potential in the field of recovery of pollutants from wastewater through anion exchange and surface electrostatic interaction. In this paper, three new ternary ZnCrNi-LDHs with the different graded porous were successfully prepared by controlling the morphology of the layer stacking using triethanolamine as the soft-template, and characterized by SEM, TEM, XPS, TG, BET and XRD. The ZnCrNi-LDHs exhibited higher adsorption capacity for pollutants such as methyl orange, sunset yellow and their mixed solutions. The results showed that there was a good synergistic adsorption effect in the adsorption process of mixed solutions. The maximum adsorption amounts of single methyl orange, sunset yellow, and mixed solutions of methyl orange and sunset yellow were 1834.63 mg·g−1, 1259.79 mg·g−1, 3270.59 mg·g−1 and 3294.38 mg·g−1, which shows that the adsorption amounts about synergistic adsorption effect for mixed solutions is much higher than those of single methyl orange and sunset yellow; Meanwhile, the maximum adsorption capacity is higher than most adsorbents. The pseudo-second-order kinetic model fitted the kinetic data of adsorption, while the equilibrium adsorption isotherm data followed the Freundlich model. The adsorption process contains both surface adsorption and interlayer anion exchange as determined by SEM, XRD, IR and zeta potential analysis. The research not only demonstrates that three ZnCrNi-LDHs materials showed excellent adsorption performance and practical interest as an efficient adsorbent for the removal of methyl orange, sunset yellow, and mixed solutions but also provides a strategy for the removal of mixed dye solutions

Molecular characterization of China rabies virus vaccine strain

Abstract Background Rabies virus (RV), the agent of rabies, can cause a severe encephalomyelitis in several species of mammals, including humans. As a human rabies vaccine strain employed in China, the genetic knowledge of the aG strain has not been fully studied. The main goal of the present study is to amplify the whole genome of aG strain, and genetic relationships between other vaccine strains and wild strains were analyzed. Results The entire genome of human rabies virus vaccine strain aG employed in China was sequenced; this is the second rabies virus vaccine strain from China to be fully characterized. The overall organization and the length of the genome were similar to that of other lyssaviruses. The length of aG strain was 11925nt, comprising a leader sequence of 58nt, nucleoprotein (N) gene of 1353nt, phosphoprotein (P) gene of 894 nt, matrix protein (M) gene of 609nt, glycoprotein (G) gene of 1575nt, RNA-dependent RNA polymerase (RdRp,L) gene of 6384nt, and a trailer region of 70 nt. There was TGAAAAAAA (TGA7) consensus sequence in the end of each gene, except AGA7 at the end of G gene. There was AACAYYYCT consensus start signal at the beginning of each gene. Conclusions In this report, we analyzed the full genome of China human rabies vaccine strain aG. Our studies indicated that the genome of aG retained the basic characteristics of RV. At gene level, N was the most conserved among the five coding genes, indicating this gene is the most appropriate for quantitative genotype definition. The phylogenetic analysis of the N indicated the aG strain clustered most closely with Japanese and Russian rabies vaccine strains, suggesting that they may share the same ancestor; also, the aG strain did not share high homology with wild strains isolated from China, making it may not be the best vaccine strain, more research is needed to elucidate the genetic relationship among the RV circulating in China.</p

Community Structure and Succession Regulation of Fungal Consortia in the Lignocellulose-Degrading Process on Natural Biomass

The study aims to investigate fungal community structures and dynamic changes in forest soil lignocellulose-degrading process. rRNA gene clone libraries for the samples collected in different stages of lignocellulose degradation process were constructed and analyzed. A total of 26 representative RFLP types were obtained from original soil clone library, including Mucoromycotina (29.5%), unclassified Zygomycetes (33.5%), Ascomycota (32.4%), and Basidiomycota (4.6%). When soil accumulated with natural lignocellulose, 16 RFLP types were identified from 8-day clone library, including Basidiomycota (62.5%), Ascomycota (36.1%), and Fungi incertae sedis (1.4%). After enrichment for 15 days, identified 11 RFLP types were placed in 3 fungal groups: Basidiomycota (86.9%), Ascomycota (11.5%), and Fungi incertae sedis (1.6%). The results showed richer, more diversity and abundance fungal groups in original forest soil. With the degradation of lignocellulose, fungal groups Mucoromycotina and Ascomycota decreased gradually, and wood-rotting fungi Basidiomycota increased and replaced the opportunist fungi to become predominant group. Most of the fungal clones identified in sample were related to the reported lignocellulose-decomposing strains. Understanding of the microbial community structure and dynamic change during natural lignocellulose-degrading process will provide us with an idea and a basis to construct available commercial lignocellulosic enzymes or microbial complex