The thick loess-palaeosol sequences of the Chinese Loess Plateau (CLP) are valuable continental archives of paleoclimatic and paleoenvironmental changes since at least the mid-Miocene. The magnetic ...susceptibility record of loess sequences is frequently used for palaeoclimatic reconstruction. However, the two magnetoclimatological models for the magnetic enhancement of loess-palaeosol sequences—the wind vigour model and the pedogenic model—are still debated, and neither model alone is sufficient to explain the magnetic susceptibility stratigraphy of loess deposits in diverse environments. Loess can be substantially altered by its environment of deposition and the macroscopic characteristics of loess may differ substantially from the well-documented sequences of the CLP, which complicates loess identification and its palaeoclimatic interpretation. In the present study, we summarize the attributes of loess deposits in different environments and review possible approaches for identifying aeolian accumulation. Loess-palaeosol sequences in various climatic contexts, from arid to subhumid, are summarized and categorized and the relationship between the magnetic susceptibility and effective precipitation is evaluated. A model comprising three cases is proposed to interpret the magnetic susceptibility of loess-palaeosol sequences in a variety of different environments. In case A (e.g., the Xinjiang loess, NW China), where physical weathering dominates and pedogenesis is weak, there is no relationship between the magnetic susceptibility and pedogenesis, and here the wind vigour model is applicable. In case B (e.g., the CLP), where, under predominantly oxidizing conditions, the magnetic susceptibility increases with pedogenic intensity, and an oxidizing-pedogenic model is applicable. In case C (e.g., Alaskan and Siberian loess), there is a negative relationship between magnetic susceptibility and pedogenesis due to the dissolution of detrital iron oxides under reducing conditions, and a reduction-pedogenesis model is applicable. In Case C, pedogenesis (or chemical weathering/dissolution) acts to largely obliterate the detrital magnetic susceptibility signal. Hence, contrary to the original interpretation of the magnetic susceptibility of Alaskan and Siberian loess, the wind vigour model is not applicable. Two thresholds of mean annual precipitation between the three cases are proposed, which enable the paleoclimatic interpretation of loess magnetic susceptibility records in different environments.
•Approaches of identifying aeolian accumulation are reviewed.•Loess-palaeosol in 5 diverse environments are summarized.•A new mode of magnetic susceptibility for diverse loess-palaeosol.
Paleosols are useful evidence of paleoclimates and paleoenvironments independent of fossils. Zhangye Danxia National Geopark of Gansu Province (northwestern China) has been protected for its stunning ...varicolored badlands of Early Cretaceous (Aptian-Albian) claystones. However, the paleoclimates and paleoenvironments forming such unique succession are currently not well understood. The widespread pedogenic features, for example root traces and soil horizons, indicate different paleosols, which provides clues of associated paleoclimates and paleoenvironments. In the present study, combining field work and soil micromorphology, we recognized, classified, and interpreted 155 sequential paleosol profiles of 14 different pedotypes (soil types) in the 755-m-thick section. These pedotypes have modern analogues in South Asia, indicating hotter and more humid paleoclimate than at present in Zhangye. Systematic analysis of soil units based on comparison to their modern analogues allows reconstruction of paleoenvironments in eleven humidity stages. Variation in waterlogging of the paleosols based on the ratio of Hm / Gt agreed well with regional and global paleoclimatic records, confirming its utility in paleoclimate reconstruction during Aptian and Albian. The identification and characterization of the paleosol succession provides a significant base for detailed paleoclimatic reconstruction during this period.
•155 paleosol profiles of 14 pedotypes were identified, characterized.•Several humidity stages during Aptian-Albian were deduced from paleosol units•Humidity variation indicated a regional and global significance.
Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. Accumulating investigations have identified the aberrant expression of miRNAs (microRNAs) in UM, such as miR‐181, ...miR‐20a, miR‐144, miR‐146a. The purpose of this study is to investigate the biological function of miR‐224‐5p in UM. The expression of miR‐224‐5p, PIK3R3, and AKT3 in 30 tumor tissues and paired adjacent noncancerous tissues were analyzed using Western blot analysis and quantitative real‐time polymerase chain reaction (qRT‐PCR) assays. Cell proliferation assay, transwell assay, and wound healing assay were used to measure the effects of miR‐224‐5p on the motility of UM in vitro. Western blot analysis and luciferase assays were used to detect the expression of PIK3R3 and AKT3 as miR‐224‐5p downstream targets. The results of Western blot analysis and qRT‐PCR assays indicated that the expression of miR‐224‐5p was lower in UM tissues compared to normal tissue, while the expression of PIK3R3 and AKT3 were simultaneously increased. Upregulation of miR‐224‐5p significantly inhibited capacities of proliferation, invasion, and migration of OCM‐1A cells and decreased expression of PIK3R3 and AKT3. Luciferase assay demonstrated PIK3R3 and AKT3 as downstream targets of miR‐224‐5p. Moreover, upregulating PIK3R3 and AKT3 restrained miR‐224‐5p‐induced inhibition of the motility of OCM‐1A cells. Thus, our study proved that miR‐224‐5p was involved in proliferation, invasion, and migration of UM cells via regulation the expression of PIK3R3 and AKT3. And the results also established a miR‐224‐5p/PIK3R3/PI3K/AKT axis in the regulation of UM progression, providing an experimental basis for further exploring the miR‐224‐5p as a therapeutic and diagnosis target for patients with UM.
1. Upregulation of miR‐224‐5p significantly inhibited capacities of proliferation, invasion, and migration of OCM‐1A cells. 2. Upregulation of miR‐224‐5p decreased expression of PIK3R3 and AKT3. 3. Established a miR‐224‐5p/PIK3R3/PI3K/AKT axis in the regulation of uveal melanoma progression.
The MYB transcription factors comprise one of the largest superfamilies in plants that have been implicated in the regulation of plant-specific metabolites and responses to biotic and abiotic ...stresses. Here, we present the first comprehensive genome-wide analysis and functional characterization of the CtMYB family in
Carthamus tinctorius
. A total of 272 CtMYBs were identified and classified into 12 subgroups using comparative phylogenetic analysis with
Arabidopsis
and rice orthologs. The overview of conserved motifs, gene structures, and cis elements as well as the expression pattern of
CtMYB
genes indicated the diverse roles of these transcription factors during plant growth, regulation of secondary metabolites, and various abiotic stress responses. The subcellular localization and transactivation analysis of four CtMYB proteins indicated predominant localization in the nuclei with enhanced transcriptional activation in yeast. The expression of
CtMYB63
induced with various abiotic stress conditions showed upregulation in its transcription level. In addition, the expression analysis of the core structural genes of anthocyanin biosynthetic pathway under drought and cold stress in
CtMYB63
overexpressed transgenic lines also supports the notion of
CtMYB63
transcriptional reprogramming in response to abiotic stress by upregulating the anthocyanin biosynthesis. Together, our findings revealed the underlying regulatory mechanism of CtMYB TF network involving enhanced cold and drought stress tolerance through activating the rapid biosynthesis of anthocyanin in
C. tinctorius
. This study also presents useful insights towards the establishment of new strategies for crop improvements.
Main conclusion
We performed genome-wide and heterologous expression analysis of the safflower cysteine protease family and found that inhibition of
CtCP1
expression enhanced plant cold resistance.
...Cysteine protease (CP) is mainly involved in plant senescence and stress responses. However, the molecular mechanism of endogenous cysteine protease inhibition in plant stress tolerance is yet unknown. Here, we report the discovery and functional characterization of a candidate CP1 gene from safflower. The conserved structural topology of
CtCP
s revealed important insights into their possible roles in plant growth and stress responses. The qRT-PCR results implied that most of
CtCP
genes were highly expressed at fading stage suggesting that they are most likely involved in senescence process. The
CtCP1
expression was significantly induced at different time points under cold, NaCl, H
2
O
2
and PEG stress, respectively. The in-vitro activity of heterologously expressed
CtCP1
protein showed highest protease activity for casein and azocasein substrates. The expression and phenotypic data together with antioxidant activity and physiological indicators revealed that transgenic plants inhibited by
CtCP1
-anti showed higher tolerance to low temperature than WT and
CtCP1
-OE plants. Our findings demonstrated the discovery of a new
Cysteine protease 1
gene that exerted a detrimental effect on transgenic
Arabidopsis
under low-temperature stress.
Magnetotactic bacteria (MTB) rely on magnetotaxis to effectively reach their preferred living habitats, whereas experimental investigation of magnetotactic advantage in stable sediment is currently ...lacking. We studied two wild type MTB (cocci and rod-shaped M. bavaricum) in sedimentary environment under exposure to geomagnetic field in the laboratory, zero field and an alternating field whose polarity was switched every 24 hours. The mean concentration of M. bavaricum dropped by ~50% during 6 months in zero field, with no clear temporal trend suggesting an extinction. Cell numbers recovered to initial values within ~1.5 months after the Earth's field was reset. Cocci displayed a larger temporal variability with no evident population changes in zero field. The alternating field experiment produced a moderate decrease of M. bavaricum concentrations and nearby extinction of cocci, confirming the active role of magnetotaxis in sediment and might point to a different magnetotactic mechanism for M. bavaricum which possibly benefited them to survive field reversals in geological periods. Our findings provide a first quantification of magnetotaxis advantage in sedimentary environment.
Heavy metal pollution poses a serious hazard to the soil bacterial community. The purpose of this study is to understand the characteristics of soil heavy metal pollution in lead-zinc mines in karst ...areas and the response of Pb, Zn, Cd, and As-induced composite pollution to soil microorganisms. This paper selected soil samples from the lead-zinc mining area of Xiangrong Mining Co., Ltd., Puding County, Guizhou Province, China. The soil in the mining area is contaminated by multiple heavy metals such as Pb, Zn, Cd and As. The average levels of Pb, Zn, Cd and As in the Pb-Zn mining soil were 14.5, 7.8, 5.5 and 4.4 times higher than the soil background in this area, respectively. Bacterial community structures and functions were analyzed using 16 S rRNA high-throughput sequencing technology and the PICRUSt method. A total of 19 bacterial phyla, 34 classes and 76 orders were detected in the tested soil. At the phylum level, the Proteobacteria are the dominant flora of the soil in the tailings reservoir area of the lead-zinc mine, respectively GWK1 (49.64%), GWK2 (81.89%), GWK3 (95.16%); and for the surrounding farmland soil, the Proteobacteria, Actinobacteriota, Acidobacteriota, Chloroflexi and Firmicutes are the most abundant in five bacterial groups. RDA analyses revealed that the heavy metal pollution of the lead-zinc mining area has a significant impact on the diversity of soil microorganisms. As the distance from the mining area increased, the heavy metal comprehensive pollution and potential risk value decreased, and the bacterial diversity increased. Additionally, various types of heavy metals have different effects on bacterial communities, and soil heavy metal content will also change the bacterial community structure. Proteobacteria positively related to Pb, Cd, and Zn, therefore, Proteobacteria were highly resistant to heavy metals. PICRUSt analysis suggested that heavy metals significantly affect the metabolic function of microorganisms. Microorganisms might generate resistance and enable themselves to survive by increasing the transport of metal ions and excreting metal ions. These results can be used as a basis for the microbial remediation of heavy metal-contaminated farmland in mining areas.
•Heavy metal pollution of the karst mining area has a significant impact on the diversity of soil microorganisms.•Different types of heavy metals have different effects on bacterial communities.•Heavy metal content will change the bacterial community structure.•Heavy metals significantly affect the metabolic function of microorganisms.
The basic helix-loop-helix (bHLH) family is the second largest superfamily of transcription factors that belongs to all three eukaryotic kingdoms. The key function of this superfamily is the ...regulation of growth and developmental mechanisms in plants. However, the bHLH gene family in
has not yet been studied. Here, we identified 41 bHLH genes in
that were classified into 23 subgroups. Further, we conducted a phylogenetic analysis and identified 10 conserved protein motifs found in the safflower bHLH family. We comprehensively analyzed a group of bHLH genes that could be associated with flavonoid biosynthesis in safflower by gene expression analysis, gene ontology annotation, protein interaction network prediction, subcellular localization of the candidate CtbHLH40 gene, and real-time quantitative expression analysis. This study provides genome-wide identification of the genes related to biochemical and physiological processes in safflower.
The extinction of non‐avian dinosaurs and its cause(s) have been a matter of debate for several decades. Here we measured Hg and its isotopic composition, heavy metals, and magnetic parameter in a ...terrestrial basin in southeastern China. Hg exhibited anomalies from 66.4 to 65.6 Ma, with near‐zero to positive Δ199Hg values, which reflected the eruption of Deccan Traps (DT) magma. In addition, Hg anomalies coincided with the gradual extinction of non‐avian dinosaurs, thereby consistent with the hypothesis that DT played a key role in the mass extinction. Analysis of paleoclimatic records showed that both the Late Maastrichtian warming event (LMWE) and Dan‐C2 event occurred at the maxima of the 405‐kyr long eccentricity cycle, and the onset of the dinosaur decline was earlier than the LMWE, suggesting that the LMWE played an ancillary role in the mass extinction. The mechanism of how DT caused the mass extinction requires further investigation.
Plain Language Summary
The debate concerning the relative importance of the Chicxulub bolide impact and/or Deccan Traps (DT) volcanism as the cause of the extinction of non‐avian dinosaurs at the end of the Cretaceous has lasted for several decades. There is lack of direct geological evidence linking the DT eruption with the non‐avian dinosaur fossil record, so the Chicxulub bolide impact is regarded by many as the dominant—if not the sole—cause of the mass extinction. Therefore, it is necessary to find new geological evidence to clarify this issue. In this study, the concentration of Hg and its isotope systematics were carefully investigated, combined with palaeontology data and palaeoclimate records, we suggest that DT played a key role in the extinction of non‐avian dinosaurs.
Key Points
Hg combined with its isotopic composition indicate the record of Deccan Traps (DT) volcanism
DT volcanism played an important role in the extinction of non‐avian dinosaurs
The inherent mechanism of how DT caused the mass extinction requires further investigation
•Complete magnetic enhancement and reduction was recorded in the studied profile.•Magnetic enhancement occurred in the aerobic layer.•Magnetic reduction occurred under water-logged ...conditions.•Water-logged condition was caused by agriculture with a history of about 200 years.•The time required for a dissolution of iron oxides was shorter than 200 years.
Previous studies have revealed that magnetic enhancement caused by the pedogenic process often occurs in aerobic soils experiencing low to moderate rainfall, while magnetic reduction caused by iron oxide dissolution often occurs in anaerobic soils experiencing high rainfall. To explore the time required for iron oxide dissolution when the soil conditions transform from aerobic to anaerobic, a typical weathering crust profile was selected. The results show the complete process of magnetic enhancement and reduction, and that the former occurred in aerobic soil due to the newborn magnetic minerals during the pedogenic process, while the latter occurred under water-logged conditions caused by rice cultivation with a history of approximately 200 years. Therefore, it can be inferred that the time required for the significant dissolution of iron oxides is probably shorter than 200 years, which is longer than that determined by indoor experiments, but much shorter than the theoretical weathering model.
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