Geochemical indicators to constrain weathering, provenance and tectonic setting of the Pisha Sandstone (Early-Middle Triassic) in Northeast Ordos Basin, China.

The Pisha Sandstone is widely exposed in the northeastern margin of the Ordos basin. Since the Mesozoic the basin was subjected to uneven uplift several times, strong weathering and erosion have been occurring and a large amount of sediments derived from these erosional strata are input into the lower Yellow River, posing a fragile ecological environment along the river. However, the geochemical characteristics of the Pisha Sandstone have remained poorly understood. In this study, we focus on the Pisha Sandstone from Early-Middle Triassic Liujiagou, Heshanggou and Ermaying Formation, present a very first petrographic and geochemical data together with detailed field geological characteristics, aiming to place geochemical indicators on weathering, provenance and tectonic setting of the Pisha Sandstone. The results show that sandstones in Pisha Sandstone are classified as arkose, litharenite and wacke. The geochemical proxies including Chemical Index of Alteration (CIA = 67.2), Chemical Index of Weathering (CIW = 80.1), Plagioclase Index of Alteration (PIA = 75.6) and Index of Compositional Variability (ICV = 1.6) indicate Pisha Sandstone experienced first-cycle deposit and moderate to strong chemical weathering. Trace element and rare earth element concentrations together with their ratios (La/Sc, La/Co, Th/Sc, Th/Co, Cr/Th) reveal a felsic provenance, and source rock compositions are predominantly granodiorite and granite from the north margin of the Inner Mongolia Paleo-Uplift (IMPU), with a small amount of mafic or intermediate components. The geochemical signatures and tectonic discrimination diagrams display a collision setting for the Pisha Sandstone and further reveal the sediments had been deposited in a continental island arc setting. The results of this work may provide new theoretical basis for environmental protection in the Pisha Sandstone area.

Structural Analyses of a Dominant Cryptosporidium parvum Epitope Presented by H-2Kb Offer New Options To Combat Cryptosporidiosis.

Cryptosporidium parvum has gained much attention as a major cause of diarrhea in the world, particularly in those with compromised immune systems. The data currently available on how the immune system recognizes C. parvum are growing rapidly, but we lack data on the interactions among host major histocompatibility complex (MHC) diversity and parasitic T-cell epitopes. To identify antigenic epitopes in a murine model, we performed systematic profiling of H-2Kb-restricted peptides by screening the dominant Cryptosporidium antigens. The results revealed that the glycoprotein-derived epitope Gp40/15-SVF9 induced an immunodominant response in C. parvum-recovered C57BL/6 mice, and injection of the cytotoxic-T-lymphocyte (CTL) peptide with the adjuvant activated peptide-specific CD8+ T cells. Notably, the SVF9 epitope was highly conserved across Cryptosporidium hominis, C. parvum, and many other Cryptosporidium species. SVF9 also formed stable peptide-MHC class I (MHC I) complexes with HLA-A*0201, suggesting cross-reactivity between H-2Kb and human MHC I specificities. Crystal structure analyses revealed that the interactions of peptide-MHC surface residues of H-2Kb and HLA-A*0201 are highly conserved. The hydrogen bonds of H-2Kb-SVF9 are similar to those of a dominant epitope presented by HLA-A*0201, which can be recognized by a public human T-cell receptor (TCR). Notably, we found double conformations in position 4 (P4), 5 (P5) of the SVF9 peptide, which showed high flexibility, and multiple peptide conformations generated more molecular surfaces that can potentially be recognized by TCRs. Our findings demonstrate that an immunodominant C. parvum epitope and its homologs from different Cryptosporidium species and subtypes can benefit vaccine development to combat cryptosporidiosis. IMPORTANCE Adaptive immune responses and T lymphocytes have been implicated as important mechanisms of parasite-induced protection. However, the role of CD8+ T lymphocytes in the resolution of C. parvum infection is largely unresolved. Our results revealed that the glycoprotein-derived epitope Gp40/15-SVF9 induced an immunodominant CD8+ T-cell response in C57BL/6 mice. Crystal structure analyses revealed that the interactions of the H-2Kb-SVF9 peptide are similar to those of a dominant epitope presented by HLA-A*0201, which can be recognized by human TCRs. In addition, we found double conformations of the SVF9 peptide, which showed high flexibility and multiple peptide conformations that can potentially be recognized by TCRs.

Multi-pathway inducing ferroptosis by MnO2-based nanodrugs for targeted cancer therapy.

A multifunctional nanodrug (Tf-DHA-ASO-MnO2) based on manganese dioxide nanosheets was constructed by triple-dressing with transferrin, dihydroartemisinin, and antisense oligonucleotide sequences. Tf-DHA-ASO-MnO2 shows an effective targeted cancer therapy ability through the ferroptosis caused by the production of excessive lipid peroxides resulting from the combined effect of glutathione exhaustion, reactive oxygen species generation and down-regulation of glutathione peroxidase 4.

The effect of lactoferrin in aging: role and potential.

Aging is frequently accompanied by various types of physiological deterioration, which increases the risk of human pathologies. Global public health efforts to increase human lifespan have increasingly focused on lowering the risk of aging-related diseases, such as diabetes, neurodegenerative diseases, cardiovascular disease, and cancers. Dietary intervention is a promising approach to maintaining human health during aging. Lactoferrin (LF) is known for its physiologically pleiotropic properties. Anti-aging interventions of LF have proven to be safe and effective for various pharmacological activities, such as anti-oxidation, anti-cellular senescence, anti-inflammation, and anti-carcinogenic. Moreover, LF has a pivotal role in modulating the major signaling pathways that influence the longevity of organisms. Thus, LF is expected to be able to attenuate the process of aging and greatly ameliorate its effects.

First Report of Didymella americana causing corn stalk rot in China.

Corn (Zea mays L.) is an important food crop and feedstuff worldwide. However, Corn stalk rot, caused by multiple pathogens, is globally an economic soil-borne disease worldwide. In September 2019, a survey was carried out to characterize pathogenic fungi in corn stalks in Nehe city (48.48°N 124.88°E), Heilongjiang Province, China. Stalk rot incidence was approximately 5% in three of the fields sampled (5 ha/per field). Symptoms included wilting of whole plants, drooping ears or rapid death of the upper leaves or whole plant from blister stage to physiological maturity (growth stages R2- R6) stage with drooping ears or rapid death of the upper leaves or whole plant. A brown to black dry rot or necrosis was observed throughout the central pith and internal tissues of the stalk and crown were observed, which resulted in hollow and soft stalks. Fifteen tissue samples (0.25 cm2) from 15 individual diseased plants were surface disinfested with 75% ethanol for 2 s, followed by 0.5% NaOCl for 5 min, rinsed three times in sterile distilled water and cultured on potato dextrose agar (PDA) with 50 µg/mL streptomycin at 26°C in darkness. After 3 days, a total of eight fungal isolates with consistent characteristics were obtained from three sampling points and subcultured by transferring hyphal tips onto a new PDA plate. Single-conidium isolates were generated with methods reported previously (Leslie and Summerell 2006). Cultures on PDA were honey to olivaceous buff in the center with dense aerial mycelia and wide buff colored margins. The dimensions of conidia from 30-day-old PDA cultures were 4.5 to 15.3 µm × 1.5 to 4.3 µm (n = 50). Often, one to two oil bodies were present within the conidia. Based on these morphological features, the isolates were identified as Didymella americana (Aveskamp et al. 2010; Gorny et al. 2016). Genomic DNA was extracted from a representative isolate YJDA8 and the internal transcribed spacer regions (ITS) and translation elongation factor 1-alpha gene (TEF-1ɑ) were amplified and sequenced using the primers ITS1/ITS4 (Yin et al. 2012) and EF1-728F/EF1-986R (Carbone and Kohn 1999), respectively. The sequences of YJDA8 (accession nos. MT995077 for ITS and MW003707 for TEF-1a ) showed 99.6% (529/531 bp) and 97.6% (283/290 bp), identity to the sequences of D. americana isolate YSGYE6 (accession no. MK945663.1) and isolate K_INSO2_6_10 (MN554764.1) respectively. Pathogenicity tests were conducted by root injection of corn plants at the blister stage in the field. Conidia were obtained from 30-day-old PDA cultures grown at 20°C with a 12 h photoperiod. A conidial suspension (1.5 ml of 1×105 conidia/mL) was injected into the base of the maize stems using a 5 ml syringe. For each treatment, 5 plants were inoculated. Plants injected with 1.5 ml distilled sterile water served as the control. After inoculation, the plants were managed using conventional methods. All inoculated plants showed symptoms 25 days after inoculation that were similar to those observed in the field, while no symptoms were observed on the control plants. The fungus was re-isolated and confirmed to be D. americana. D. americana has previously been reported on corn roots and soybean pods in the USA (Aveskamp et al. 2009 as Peyronellaea americana), on lima bean in Delaware and Maryland (Everts et al. 2020). To our knowledge, this is the first report of D. americana causing stalk rot on corn in China. Therefore, its distribution needs to be investigated, monitored and managed with effective disease management strategies to protect corn.

Palladium/Copper Cocatalyzed C-H Activation and C-C Bond Regioselective Cleavage Reaction for the Synthesis of Fused Chromeno Quinolines.

A method for the synthesis of fused chromeno quinolines by the palladium/copper cocatalyzed C-H bond activation and C-C bond cleavage reaction has been developed. A variety of fused chromeno quinoline derivatives could be synthesized by coumarin derivatives and anilines through the C-C bond cleavage/C-H functionalization/C-C bond formation process. The MTT assay was used to evaluate the chromeno quinolines against the human cervix tumor cells (HeLa), 3c and 9c without coordination metals showed good inhibition effect.

Analysis of the affinity of influenza A virus protein epitopes for swine MHC I by a modified in vitro refolding method indicated cross-reactivity between swine and human MHC I specificities.

In vitro refolding assays can be used to investigate the affinity and stability of the binding of epitope peptides to major histocompatibility complex (MHC) class I molecules, which are key factors in the presentation of peptides to cytotoxic T lymphocytes (CTLs). The recognition of peptide epitopes by CTLs is crucial for protection against influenza A virus (IAV) infection. The peptide-binding motif of the swine SLA-3*hs0202 molecule has been previously reported and partly overlaps with the binding motif of the most abundant human MHC allele, HLA-A*0201. In this study, we screened all the protein sequences of the swine-origin epidemic IAV strain A/Beijing/01/2009 (H1N1), and a total of 73 9-mer epitope peptides were predicted to fit the consensus motif of the swine SLA-3*hs0202 or HLA-A*0201 molecule. Then, 14 peptides were selected, and their affinities to SLA-3*hs0202 were tested by a modified in vitro refolding assay. Our results show that ten epitopes could tolerate gel filtration, indicating that these epitopes formed stable or partly stable complexes with SLA-3*hs0202. Eight out of the ten epitopes have been previously reported as HLA-A2-restricted epitopes, which implied cross-reactivity between swine and human MHC I specificities. Furthermore, the modified mini-system refolding method could be applied for the screening of peptides because the refolding efficiency remained almost unchanged with the positive peptide (HA-KMN9) subjected to size-exclusion chromatography and Resource Q anion-exchange chromatography. The results presented here provide new insight into the development of epitope-based vaccines to control IAV and increase our understanding of swine molecular immunology.

Polymorphism and peptide-binding specificities of porcine major histocompatibility complex (MHC) class I molecules.

The swine lymphocyte antigen class I (SLA I) is a highly polymorphic gene superfamily that plays an important role in swine anti-viral immune responses. However, an understanding of the highly variable sites and peptide-binding specificities of SLA I molecule is limited. In this study, a total of 27 SLA I alleles were identified from 3 Tibetan wild boars and 3 Heishan pigs. The phylogenetic relationship between the Tibetan wild boar and other breeds was analyzed using bioinformatics methods, and the highly variable sites were noted in the three dimensional structures of SLA I. Peptides from the porcine reproductive and respiratory syndrome virus (PRRSV) and influenza A virus (IAV) were screened with a bioinformatic method and refolding assay in vitro. The superior SLA I molecules, which have the ability to combine with more peptides, were selected from the Tibetan wild boars and Heishan pigs. The results showed that the SLA I of the Tibetan wild boars was not divergent from other pig breeds and that high-variation sites were mostly located in the peptide binding groove (PBG), suggesting that high variation sites could determines the peptide-binding characteristics and would possibly influences peptide-specific CD8+ T cell recognition. The SLA I allele SLA-1*0302 (known as KY113114) of the Tibetan wild boar formed stable complexes with three PRRSV peptides, and the SLA-3*hs0202 (KJ555032) from Heishan pigs was able to bind with four IAV peptides. The results from this study may benefit vaccine development and may help control IAV and PRRSV in swine.

Structural Definition of Duck Major Histocompatibility Complex Class I Molecules That Might Explain Efficient Cytotoxic T Lymphocyte Immunity to Influenza A Virus.

A single dominantly expressed allele of major histocompatibility complex class I (MHC I) may be responsible for the duck's high tolerance to highly pathogenic influenza A virus (HP-IAV) compared to the chicken's lower tolerance. In this study, the crystal structures of duck MHC I (Anpl-UAA*01) and duck ß2-microglobulin (ß2m) with two peptides from the H5N1 strains were determined. Two remarkable features were found to distinguish the Anpl-UAA*01 complex from other known MHC I structures. A disulfide bond formed by Cys95 and Cys112 and connecting the ß5 and ß6 sheets at the bottom of peptide binding groove (PBG) in Anpl-UAA*01 complex, which can enhance IAV peptide binding, was identified. Moreover, the interface area between duck MHC I and ß2m was found to be larger than in other species. In addition, the two IAV peptides that display distinctive conformations in the PBG, B, and F pockets act as the primary anchor sites. Thirty-one IAV peptides were used to verify the peptide binding motif of Anpl-UAA*01, and the results confirmed that the peptide binding motif is similar to that of HLA-A*0201. Based on this motif, approximately 600 peptides from the IAV strains were partially verified as the candidate epitope peptides for Anpl-UAA*01, which is a far greater number than those for chicken BF2*2101 and BF2*0401 molecules. Extensive IAV peptide binding should allow for ducks with this Anpl-UAA*01 haplotype to resist IAV infection.IMPORTANCE Ducks are natural reservoirs of influenza A virus (IAV) and are more resistant to the IAV than chickens. Both ducks and chickens express only one dominant MHC I locus providing resistance to the virus. To investigate how MHC I provides IAV resistance, crystal structures of the dominantly expressed duck MHC class I (pAnpl-UAA*01) with two IAV peptides were determined. A disulfide bond was identified in the peptide binding groove that can facilitate Anpl-UAA*01 binding to IAV peptides. Anpl-UAA*01 has a much wider recognition spectrum of IAV epitope peptides than do chickens. The IAV peptides bound by Anpl-UAA*01 display distinctive conformations that can help induce an extensive cytotoxic T lymphocyte (CTL) response. In addition, the interface area between the duck MHC I and ß2m is larger than in other species. These results indicate that HP-IAV resistance in ducks is due to extensive CTL responses induced by MHC I.

Structural and Biochemical Analyses of Swine Major Histocompatibility Complex Class I Complexes and Prediction of the Epitope Map of Important Influenza A Virus Strains.

UNLABELLED: The lack of a peptide-swine leukocyte antigen class I (pSLA I) complex structure presents difficulties for the study of swine cytotoxic T lymphocyte (CTL) immunity and molecule vaccine development to eliminate important swine viral diseases, such as influenza A virus (IAV). Here, after cloning and comparing 28 SLA I allelic genes from Chinese Heishan pigs, pSLA-3*hs0202 was crystalized and solved. SLA-3*hs0202 binding with sß2m and a KMNTQFTAV (hemagglutinin [HA]-KMN9) peptide from the 2009 pandemic swine H1N1 strain clearly displayed two distinct conformations with HA-KMN9 peptides in the structures, which are believed to be beneficial to stimulate a broad spectrum of CTL immune responses. Notably, we found that different HA-KMN9 conformations are caused, not only by the flexibility of the side chains of residues in the peptide-binding groove (PBG), but also by the skewing of α1 and α2 helixes forming the PBG. In addition, alanine scanning and circular-dichroism (CD) spectra confirmed that the B, D, and F pockets play critical biochemical roles in determining the peptide-binding motif of SLA-3*hs0202. Based on biochemical parameters and comparisons to similar pockets in other known major histocompatibility complex class I (MHC-I) structures, the fundamental motif for SLA-3*hs0202 was determined to be X-(M/A/R)-(N/Q/R/F)-X-X-X-X-X-(V/I) by refolding in vitro and multiple mutant peptides. Finally, 28 SLA-3*hs0202-restricted epitope candidates were identified from important IAV strains, and two of them have been found in humans as HLA-A*0201-specific IAV epitopes. Structural and biochemical illumination of pSLA-3*hs0202 can benefit vaccine development to control IAV in swine. IMPORTANCE: We crystalized and solved the first SLA-3 structure, SLA-3*hs0202, and found that it could present the same IAV peptide with two distinct conformations. Unlike previous findings showing that variable peptide conformations are caused only by the flexibility of the side chains in the groove, the skewing of the α1 and α2 helixes is important in the different peptide conformations in SLA-3*hs0202. We also determined the fundamental motif for SLA-3*hs0202 to be X-(M/A/R)-(N/Q/R/F)-X-X-X-X-X-(V/I) based on a series of structural and biochemical analyses, and 28 SLA-3*hs0202-restricted epitope candidates were identified from important IAV strains. We believe our structure and analyses of pSLA-3*hs0202 can benefit vaccine development to control IAV in swine.