Comprehensive Molecular Characterization of the Mitochondrial Genome of the Takin Lungworm Varestrongylus eleguneniensis (Strongylida: Protostrongylidae).

The takin lungworm Varestrongylus eleguneniensis (Strongylida: Protostrongylidae) causes lethal bronchopneumonia and represents severe threats to captive and wild populations. However, until now there has been very limited information available concerning the molecular epidemiology and evolutionary biology of V. eleguneniensis. Mitochondrial genomes (mtDNAs) can provide resources for investigations in these areas and, therefore, can assist with the surveillance and control of this lungworm. Herein, the complete mtDNA of V. eleguneniensis was sequenced and characterized with Illumina pipeline analyses. This circular genome (13,625 bp) encoded twelve protein-coding genes (PCGs), two rRNAs, and twenty-two tRNAs, with notable levels of AT and GC skews. Comparative genomics revealed a purifying selection among PCGs, with cox1 and nad6 having the lowest and the highest evolutionary rate, respectively. Genome-wide phylogenies showed a close relationship between V. eleguneniensis and Protostrongylus rufescens in Strongylida. Single gene (PCGs or rRNAs)-based phylogenies indicated that cox1 and nad5 genes shared the same family-level topology with that inferred from genomic datasets, suggesting that both genes could be suitable genetic markers for evolutionary and phylogenetic studies of Strongylida species. This was the first mtDNA of any member of the genus Varestrongylus, and its comprehensive molecular characterization represents a new resource for systematic, population genetic and evolutionary biological studies of Varestrongylus lungworms in wildlife.

Molecular Interaction Regulates the Performance and Longevity of Defect Passivation for Metal Halide Perovskite Solar Cells.

Defect passivation constitutes one of the most commonly used strategies to fabricate highly efficient perovskite solar cells (PSCs). However, the durability of the passivation effects under harsh operational conditions has not been extensively studied regardless of the weak and vulnerable secondary bonding between the molecular passivation agents and perovskite crystals. Here, we incorporated strategically designed passivating agents to investigate the effect of their interaction energies on the perovskite crystals and correlated these with the performance and longevity of the passivation effects. We unraveled that the passivation agents with a stronger interaction energy are advantageous not only for effective defect passivation but also to suppress defect migration. The prototypical PSCs treated with the optimal passivation agent exhibited superior performance and operational stability, retaining 81.9 and 85.3% of their initial performance under continuous illumination or nitrogen at 85 °C after 1008 h, respectively, while the reference device completely degraded during that time. This work provides important insights into designing operationally durable defect passivation agents for perovskite optoelectronic devices.

Cation Dynamics Governed Thermal Properties of Lead Halide Perovskite Nanowires.

Metal halide perovskite (MHP) nanowires such as hybrid organic-inorganic CH3NH3PbX3 (X = Cl, Br, I) have drawn significant attention as promising building blocks for high-performance solar cells, light-emitting devices, and semiconductor lasers. However, the physics of thermal transport in MHP nanowires is still elusive even though it is highly relevant to the device thermal stability and optoelectronic performance. Through combined experimental measurements and theoretical analyses, here we disclose the underlying mechanisms governing thermal transport in three different kinds of lead halide perovskite nanowires (CH3NH3PbI3, CH3NH3PbBr3 and CsPbBr3). It is shown that the thermal conductivity of CH3NH3PbBr3 nanowires is significantly suppressed as compared to that of CsPbBr3 nanowires, which is attributed to the cation dynamic disorder. Furthermore, we observed different temperature-dependent thermal conductivities of hybrid perovskites CH3NH3PbBr3 and CH3NH3PbI3, which can be attributed to accelerated cation dynamics in CH3NH3PbBr3 at low temperature and the combined effects of lower phonon group velocity and higher Umklapp scattering rate in CH3NH3PbI3 at high temperature. These data and understanding should shed light on the design of high-performance MHP based thermal and optoelectronic devices.

Direct Conversion of Perovskite Thin Films into Nanowires with Kinetic Control for Flexible Optoelectronic Devices.

With significant progress in the past decade, semiconductor nanowires have demonstrated unique features compared to their thin film counterparts, such as enhanced light absorption, mechanical integrity and reduced therma conductivity, etc. However, technologies of semiconductor thin film still serve as foundations of several major industries, such as electronics, displays, energy, etc. A direct path to convert thin film to nanowires can build a bridge between these two and therefore facilitate the large-scale applications of nanowires. Here, we demonstrate that methylammonium lead iodide (CH3NH3PbI3) nanowires can be synthesized directly from perovskite film by a scalable conversion process. In addition, with fine kinetic control, morphologies, and diameters of these nanowires can be well-controlled. Based on these perovskite nanowires with excellent optical trapping and mechanical properties, flexible photodetectors with good sensitivity are demonstrated.

Toward the Commercialization of Perovskite Solar Modules.

Perovskite (PVSK) photovoltaic (PV) devices are undergoing rapid development and have reached a certified power conversion efficiency (PCE) of 26.1% at the cell level. Tremendous efforts in material and device engineering have also increased moisture, heat, and light-related stability. Moreover, the solution-process nature makes the fabrication process of perovskite photovoltaic devices feasible and compatible with some mature high-volume manufacturing techniques. All these features render perovskite solar modules (PSMs) suitable for terawatt-scale energy production with a low levelized cost of electricity (LCOE). In this review, the current status of perovskite solar cells (PSCs) and modules and their potential applications are first introduced. Then critical challenges are identified in their commercialization and propose the corresponding solutions, including developing strategies to realize high-quality films over a large area to further improve power conversion efficiency and stability to meet the commercial demands. Finally, some potential development directions and issues requiring attention in the future, mainly focusing on further dealing with toxicity and recycling of the whole device, and the attainment of highly efficient perovskite-based tandem modules, which can reduce the environmental impact and accelerate the LCOE reduction are put forwarded.

Complete Mitogenome sequencing of the fish louse Argulus japonicus (Crustacea: Branchiura): Comparative analyses and phylogenetic implications.

The fish louse Argulus japonicus, a branchiuran crustacean of the Argulidae family, is attracting increasing attention because of its parasitic tendencies and significant health threats to global fish farming. The mitogenomes can yield a foundation for studying epidemiology, genetic diversity, and molecular ecology and therefore may be used to assist in the surveillance and control of A. japonicus. In this study, we sequenced and assembled the complete mitogenome of A. japonicus to shed light on its genetic and evolutionary blueprint. Our investigation indicated that the 15,045-bp circular genome of A. japonicus encodes 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), and 2 ribosomal RNAs (rRNAs) with significant AT and GC skews. Comparative genomics provided an evolutionary scenario for the genetic diversity of 13 PCGs: all were under purifying selection, with cox1 and nad6 having the lowest and highest evolutionary rates, respectively. Genome-wide phylogenetic trees established a close relationship between species of the families Argulidae (Arguloida) and Armilliferidae (Porocephalida) within Crustacea, and further, A. japonicus and Argulus americanus were determined to be more closely related to each other than to others within the family Argulidae. Single PCG-based phylogenies supported nad1 and nad6 as the best genetic markers for evolutionary and phylogenetic studies for branchiuran crustaceans due to their similar phylogenetic topologies with those of genome-based phylogenetic analyses. To sum up, these comprehensive mitogenomic data of A. japonicus and related species refine valuable marker resources and should contribute to molecular diagnostic methods, epidemiological investigations, and ecological studies of the fish ectoparasites in Crustacea.

Impacts of Eimeria coinfection on growth performance, intestinal health and immune responses of broiler chickens.

Coccidiosis caused by Eimeria is one of the most severe chicken diseases and imposes huge economic losses to the poultry industry globally. Multi-Eimeria species coinfections are common with the most prevalent combination being mixtures of Eimeria acervulina and Eimeria tenella. Although detrimental impacts of either E. acervulina or E. tenella on chicken health are well recognized, no information is available regarding their coinfection effects so far. This study was designed to investigate the influence of coinfection with E. acervulina and E. tenella on broiler chickens. 144 one-day-old broiler chickens within each of trials (trial I or II) were divided into four groups, namely, control group (CG), E. acervulina infection group (EAIG), E. tenella infection group (ETIG) and dual (E. acervulina and E. tenella) infection group (DIG). Then, chickens were measured for weight loss, lesion scores, oocyst outputs, histological changes and expressions of pro-inflammatory (interleukin [IL]-6, IL-8 and IL-18), regulatory (IL-10 and IL-22) cytokines and Toll-like receptors (TLR; TLR2 and TLR4) as well as intestinal barrier (mucin 2 [MUC2] and fattey acid-bingding proteins 2 and 6 [FABP2 and FABP6])- and tight junction (TJ; zonula occluden-1 [ZO-1], occludin [OCLN], and claudins 1 and 5 [CLDN1 and CLDN5])-related proteins at 3, 5, 7, 10, 14 and 21 days post-infection, respectively. Our results consistently showed that although ETIG and DIG exhibited a higher level of weight loss and a more amount of oocyst excretion than EAIG, DIG had lighter lesions than EAIG in the early phase because of coinfection with E. tenella. A higher (P < 0.05) ratio of duodenal villous height to crypt depth was also observed in DIG than EAIG. Moreover, histological changes in the duodenum and cecum varied by single and dual Eimeria infections. Expressions of the intestinal barrier- and TJ-related genes of EAIG, ETIG and DIG were significantly (P < 0.05) upregulated but their levels exhibited differential changes among infected chickens. Similarly, the infected chickens showed significant (P < 0.05) inflammatory responses and higher (P < 0.05) expressions of TLRs in the intestines in comparison to CG. These results presented a comprehensive physiological, pathological and immunological characterization of E. acervulina and E. tenella coinfection in broiler chickens and also shed insights into pathogenesis of multi-coccidia coinfections.

Eimeria zuernii (Eimeriidae: Coccidia): mitochondrial genome and genetic diversity in the Chinese yak.

BACKGROUND: Coccidiosis caused by Eimeria zuernii (Eimeriidae: Coccidia) represents a significant economic threat to the bovine industry. Understanding the evolutionary and genetic biology of E. zuernii can assist in new interaction developments for the prevention and control of this protozoosis. METHODS: We defined the evolutionary and genetic characteristics of E. zuernii by sequencing the complete mitogenome and analyzing the genetic diversity and population structure of 51 isolates collected from eight yak breeding parks in China. RESULTS: The 6176-bp mitogenome of E. zuernii was linear and encoded typical mitochondrial contents of apicomplexan parasites, including three protein-coding genes [PCGs; cytochrome c oxidase subunits I and III (cox1 and cox3), and cytochrome b (cytb)], seven fragmented small subunit (SSU) and 12 fragmented large subunit (LSU) rRNAs. Genome-wide comparative and evolutionary analyses showed cytb and cox3 to be the most and least conserved Eimeria PCGs, respectively, and placed E. zuernii more closely related to Eimeria mephitidis than other Eimeria species. Furthermore, cox1-based genetic structure defined 24 haplotypes of E. zuernii with high haplotype diversities and low nucleotide diversities across eight geographic populations, supporting a low genetic structure and rapid evolutionary rate as well as a previous expansion event among E. zuernii populations. CONCLUSIONS: To our knowledge, this is the first study presenting the phylogeny, genetic diversity, and population structure of the yak E. zuernii, and such information, together with its mitogenomic data, should contribute to a better understanding of the genetic and evolutionary biological studies of apicomplexan parasites in bovines.

Comprehensive molecular characterization of complete mitogenome assemblies of 33 Eimeria isolates infecting domestic chickens.

BACKGROUND: Coccidiosis caused by Eimeria is one of the most severe chicken diseases and poses a great economic threat to the poultry industry. Understanding the evolutionary biology of chicken Eimeria parasites underpins development of new interactions toward the improved prevention and control of this poultry disease. METHODS: We presented an evolutionary blueprint of chicken coccidia by genetically characterizing complete mitogenome assemblies of 33 isolates representing all seven known Eimeria species infecting chickens in China. Further genome- and gene-level phylogenies were also achieved to better understand the evolutionary relationships of these chicken Eimeria at the species level. RESULTS: 33 mitogenomes of chicken eimerian parasites ranged from 6148 bp to 6480 bp in size and encoded typical mitochondrial compositions of apicomplexan parasites including three protein-coding genes (PCGs), seven fragmented small subunit (SSU) and 12/13 fragmented large subunit (LSU) rRNAs. Comparative genomics provided an evolutionary scenario for the genetic diversity of PCGs-cytochrome c oxidase subunits 1 and 3 (cox1 and cox3) and cytochrome b (cytb); all were under purifying selection with cox1 and cox3 being the lowest and highest evolutionary rates, respectively. Genome-wide phylogenies classified the 33 Eimeria isolates into seven subgroups, and furthermore Eimeria tenella and Eimeria necatrix were determined to be more closely related to each other than to the other eight congenic species. Single/concatenated mitochondrial protein gene-based phylogenies supported cox1 as the genetic marker for evolutionary and phylogenetic studies for avain coccidia. CONCLUSIONS: To our knowledge, these are the first population-level mitogenomic data on the genus Eimeria, and its comprehensive molecular characterization provides valuable resources for systematic, population genetic and evolutionary biological studies of apicomplexan parasites in poultry.

The Complete Mitogenome of Toxocara vitulorum: Novel In-Sights into the Phylogenetics in Toxocaridae.

Toxocara vitulorum (Ascaridida: Nematoda) is one of the most common intestinal nematodes of cattle and buffalos and, therefore, represents a serious threat to their populations worldwide. Despite its significance in veterinary health the epidemiology, population genetics, and molecular ecology of this nematode remain poorly understood. The mitogenome can yield a foundation for studying these areas and assist in the surveillance and control of T. vitulorum. Herein, the first whole mitogenome of T. vitulorum was sequenced utilizing Illumina technology and characterized with bioinformatic pipeline analyses. The entire genome of T. vitulorum was 15,045 bp in length and contained 12 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), and two ribosomal RNAs (rRNAs). The gene arrangement (GA) of T. vitulorum was similar to those of other Toxocara species under GA3. The whole genome showed significant levels of AT and GC skew. Comparative mitogenomics including sequence identities, Ka/Ks, and sliding window analysis, indicated a purifying selection of 12 PCGs with cox1 and nad6 having the lowest and highest evolutionary rate, respectively. Whole amino acid sequence-based phylogenetic analysis supported a novel sister-species relationship of T. vitulorum with the congeneric species Toxocara canis, Toxocara cati, and Toxocara malaysiensis in the family Toxocaridae. Further, 12 (PCGs) single gene-based phylogenies suggested that nad4 and nad6 genes shared same topological trees with that of the whole genome, suggesting that these genes were suitable as novel genetic markers for phylogenetic and evolutionary studies of Ascaridida species. This complete mitogenome of T. vitulorum refined phylogenetic relationships in Toxocaridae and provided the resource of markers for population genetics, systematics, and epidemiology of this bovine nematode.

A Polymerization-Assisted Grain Growth Strategy for Efficient and Stable Perovskite Solar Cells.

Intrinsically, detrimental defects accumulating at the surface and grain boundaries limit both the performance and stability of perovskite solar cells. Small molecules and bulkier polymers with functional groups are utilized to passivate these ionic defects but usually suffer from volatility and precipitation issues, respectively. Here, starting from the addition of small monomers in the PbI2 precursor, a polymerization-assisted grain growth strategy is introduced in the sequential deposition method. With a polymerization process triggered during the PbI2 film annealing, the bulkier polymers formed will be adhered to the grain boundaries, retaining the previously established interactions with PbI2 . After perovskite formation, the polymers anchored on the boundaries can effectively passivate undercoordinated lead ions and reduce the defect density. As a result, a champion power conversion efficiency (PCE) of 23.0% is obtained, together with a prolonged lifetime where 85.7% and 91.8% of the initial PCE remain after 504 h continuous illumination and 2208 h shelf storage, respectively.