Mutual antagonism of mouse-adaptation mutations in HA and PA proteins on H9N2 virus replication.

Avian H9N2 viruses have wide host range among the influenza A viruses. However, knowledge of H9N2 mammalian adaptation is limited. To explore the molecular basis of the adaptation to mammals, we performed serial lung passaging of the H9N2 strain A/chicken/Hunan/8.27 YYGK3W3-OC/2018 (3W3) in mice and identified six mutations in the hemagglutinin (HA) and polymerase acidic (PA) proteins. Mutations L226Q, T511I, and A528V of HA were responsible for enhanced pathogenicity and viral replication in mice; notably, HA-L226Q was the key determinant. Mutations T97I, I545V, and S594G of PA contributed to enhanced polymerase activity in mammalian cells and increased viral replication levels in vitro and in vivo. PA-T97I increased viral polymerase activity by accelerating the viral polymerase complex assembly. Our findings revealed that the viral replication was affected by the presence of PA-97I and/or PA-545V in combination with a triple-point HA mutation. Furthermore, the double- and triple-point PA mutations demonstrated antagonistic effect on viral replication when combined with HA-226Q. Notably, any combination of PA mutations, along with double-point HA mutations, resulted in antagonistic effect on viral replication. We also observed antagonism in viral replication between PA-545V and PA-97I, as well as between HA-528V and PA-545V. Our findings demonstrated that several antagonistic mutations in HA and PA proteins affect viral replication, which may contribute to the H9N2 virus adaptation to mice and mammalian cells. These findings can potentially contribute to the monitoring of H9N2 field strains for assessing their potential risk in mammals.

Discussion on the ecological theory and technological approaches of ecosystem quality improvement and stability enhancement.

Improving ecosystem quality and stability is one of the urgent tasks of national ecological environment construction. However, the ecological theory of ecosystem quality and stability has not been well clarified. Based on the summary of influencing factors and interaction between ecosystem quality and stability, we discussed the ecolo-gical theory on the evolution of ecosystem quality and stability from the perspectives of self-organization of biological agglomeration and structure nesting, correlation of ecological elements and coupling of ecological processes, ecosystem integrity and function emergence, ecological service spillover and efficiency tradeoff, synergy and interactions between resource supply capacity and environmental suitability, as well as interactions between spontaneous change and human activities. Technologies approaches and management strategies were proposed from the aspects of ecosystem macro-pattern adjustment, protected natural areas system construction, regional complex ecosystem comprehensive management, degraded ecosystem restoration, damaged ecosystem reestablishment, typical ecosystem process management.

Mapping Chinese annual gross primary productivity with eddy covariance measurements and machine learning.

Annual gross primary productivity (AGPP) is the basis for grain production and terrestrial carbon sequestration. Mapping regional AGPP from site measurements provides methodological support for analysing AGPP spatiotemporal variations thereby ensures regional food security and mitigates climate change. Based on 641 site-year eddy covariance measuring AGPP from China, we built an AGPP mapping scheme based on its formation and selected the optimal mapping way, which was conducted through analysing the predicting performances of divergent mapping tools, variable combinations, and mapping approaches in predicting observed AGPP variations. The reasonability of the selected optimal scheme was confirmed by assessing the consistency between its generating AGPP and previous products in spatiotemporal variations and total amount. Random forest regression tree explained 85 % of observed AGPP variations, outperforming other machine learning algorithms and classical statistical methods. Variable combinations containing climate, soil, and biological factors showed superior performance to other variable combinations. Mapping AGPP through predicting AGPP per leaf area (PAGPP) explained 86 % of AGPP variations, which was superior to other approaches. The optimal scheme was thus using a random forest regression tree, combining climate, soil, and biological variables, and predicting PAGPP. The optimal scheme generating AGPP of Chinese terrestrial ecosystems decreased from southeast to northwest, which was highly consistent with previous products. The interannual trend and interannual variation of our generating AGPP showed a decreasing trend from east to west and from southeast to northwest, respectively, which was consistent with data-oriented products. The mean total amount of generated AGPP was 7.03 ± 0.45 PgC yr-1 falling into the range of previous works. Considering the consistency between the generated AGPP and previous products, our optimal mapping way was suitable for mapping AGPP from site measurements. Our results provided a methodological support for mapping regional AGPP and other fluxes.

Genetic basis of the early heading of high-latitude weedy rice.

Japonica rice (Oryza sativa L.) is an important staple food in high-latitude regions and is widely distributed in northern China, Japan, Korea, and Europe. However, the genetic diversity of japonica rice is relatively narrow and poorly adapted. Weedy rice (Oryza sativa f. spontanea) is a semi-domesticated rice. Its headings are earlier than the accompanied japonica rice, making it a potential new genetic resource, which can make up for the defects of wild rice that are difficult to be directly applied to japonica rice improvement caused by reproductive isolation. In this study, we applied a natural population consisting of weedy rice, japonica landrace, and japonica cultivar to conduct a genome-wide association study (GWAS) of the heading date and found four loci that could explain the natural variation of the heading date in this population. At the same time, we developed recombinant inbred lines (RILs) crossed by the early-heading weedy rice WR04-6 and its accompanied japonica cultivar ShenNong 265 (SN265) to carry out a QTL mapping analysis of the heading date and mapped four quantitative trait locus (QTLs) and three epistatic effect gene pairs. The major locus on chromosome 6 overlapped with the GWAS result. Further analysis found that two genes, Hd1 and OsCCT22, on chromosome 6 (Locus 2 and Locus 3) may be the key points of the early-heading character of weedy rice. As minor effect genes, Dth7 and Hd16 also have genetic contributions to the early heading of weedy rice. In the process of developing the RIL population, we introduced fragments of Locus 2 and Locus 3 from the weedy rice into super-high-yielding japonica rice, which successfully promoted its heading date by at least 10 days and expanded the rice suitable cultivation area northward by about 400 km. This study successfully revealed the genetic basis of the early heading of weedy rice and provided a new idea for the genetic improvement of cultivated rice by weedy rice.

Eddy covariance-based differences in net ecosystem productivity values and spatial patterns between naturally regenerating forests and planted forests in China.

Net ecosystem productivity (NEP), the difference between gross primary productivity (GPP) and ecosystem respiration (ER), is the basis of forest carbon sinks. Revealing NEP differences between naturally regenerating forests (NF) and planted forests (PF) can benefit for making carbon neutrality strategies. Based on 35 eddy covariance measurements in China, we analyzed NEP differences in values and spatial patterns between NF and PF. The results showed that NF had slightly lower NEP than PF, resulting from the high stand age (SA) and soil fertilizer, while their differences were not significant (p > 0.05). The increasing latitude decreased mean annual air temperature thus decreased GPP both in NF and PF. However, the higher SA and soil fertilizer in NF made most GPP release as ER thus induced no significant NEP spatial variation, while lower SA and soil fertilizer in PF made NEP spatially couple with GPP thus showed a decreasing latitudinal pattern. Therefore, stand characteristics determined the differences in NEP values but indirectly affected the differences in NEP spatial variations through altering GPP allocation. The decreasing latitudinal pattern of NEP in PF indicates a higher sequestration capacity in the PF of South China. Our results provide a basis for improving the forest carbon sequestration.

Blue light combined with salicylic acid treatment maintained the postharvest quality of strawberry fruit during refrigerated storage.

Strawberry is a high economic and nutritional value fruit, but marketing is limited by a short postharvest life. The objective of this work is to assess the influence of blue light (BL) and salicylic acid (SA, 2 mM) on strawberry postharvest quality during cold storage. The results showed that the combination of BL and SA noticeably delayed weight loss, prevented decay, improved fruit skin brightness, and increased soluble protein. Strawberries treated with BL + SA had lower total soluble solids and titratable acidity contents among treatments but had no significant change during the entire storage. Additionally, contents of total flavonoids, phenolics, anthocyanins and proanthocyanidins, activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) and total antioxidant capacities in BL + SA-treated fruit were kept at stable levels throughout the entire storage. Collectively, these findings suggest that BL + SA treatment exhibits a high potential in maintaining postharvest fruit quality of strawberry fruit.

N6-methyladenosine modification of circ_0003215 suppresses the pentose phosphate pathway and malignancy of colorectal cancer through the miR-663b/DLG4/G6PD axis.

Circular RNAs (circRNAs) are a recently discovered kind of regulatory RNAs that have emerged as critical biomarkers of various types of cancers. Metabolic reprogramming has gradually been identified as a distinct hallmark of cancer cells. The pentose phosphate pathway (PPP) plays an indispensable role in satisfying the bioenergetic and biosynthetic demands of cancer cells. However, little is known about the role of circRNAs and PPP in colorectal cancer (CRC). The novel circ_0003215 was identified at low levels in CRC and was negatively correlated with larger tumor size, higher TNM stage, and lymph node metastasis. The decreased level of circ_0003215 was resulted from the RNA degradation by m6A writer protein YTHDF2. A series of functional assays demonstrated that circ_0003215 inhibited cell proliferation, migration, invasion, and CRC tumor metastasis in vivo and in vitro. Moreover, circ_0003215 regulated the expression of DLG4 via sponging miR-663b, thereby inducing the metabolic reprogramming in CRC. Mechanismly, DLG4 inhibited the PPP through the K48-linked ubiquitination of glucose-6-phosphate dehydrogenase (G6PD). Taken together, we have identified m6A-modified circ_0003215 as a novel regulator of metabolic glucose reprogramming that inhibited the PPP and the malignant phenotype of CRC via the miR-663b/DLG4/G6PD axis.

Regain flood adaptation in rice through a 14-3-3 protein OsGF14h.

Contemporary climatic stress seriously affects rice production. Unfortunately, long-term domestication and improvement modified the phytohormones network to achieve the production needs of cultivated rice, thus leading to a decrease in adaptation. Here, we identify a 14-3-3 protein-coding gene OsGF14h in weedy rice that confers anaerobic germination and anaerobic seedling development tolerance. OsGF14h acts as a signal switch to balance ABA signaling and GA biosynthesis by interacting with the transcription factors OsHOX3 and OsVP1, thereby boosting the seeding rate from 13.5% to 60.5% for anaerobic sensitive variety under flooded direct-seeded conditions. Meanwhile, OsGF14h co-inheritance with the Rc (red pericarp gene) promotes divergence between temperate japonica cultivated rice and temperate japonica weedy rice through artificial and natural selection. Our study retrieves a superior allele that has been lost during modern japonica rice improvement and provides a fine-tuning tool to improve flood adaptation for elite rice varieties.

Genetic and Pathogenic Characterization of Avian Influenza Virus in Migratory Birds between 2015 and 2019 in Central China.

Active surveillance of avian influenza virus (AIV) in wetlands and lakes is important for exploring the gene pool in wild birds. Through active surveillance from 2015 through 2019, 10,900 samples from wild birds in central China were collected, and 89 AIVs were isolated, including 2 subtypes of highly pathogenic AIV and 12 of low-pathogenic AIV; H9N2 and H6Ny were the dominant subtypes. Phylogenetic analysis of the isolates demonstrated that extensive intersubtype reassortments and frequent intercontinental gene exchange occurred in AIVs. AIV gene segments persistently circulated in several migration seasons, but interseasonal persistence of the whole genome was rare. The whole genomes of one H6N6 and polymerase basic 2 (PB2), polymerase acidic (PA), hemagglutinin (HA), neuraminidase (NA), M, and nonstructural (NS) genes of one H9N2 virus were found to be of poultry origin, suggesting a spillover of AIVs from poultry to wild birds. Importantly, one H9N2 virus only bound to human-type receptor, and one H1N1, four H6, and seven H9N2 viruses possessed dual receptor-binding capacity. Nineteen of 20 representative viruses tested could replicate in the lungs of mice without preadaptation, which poses a clear threat of infection in humans. Together, our study highlights the need for intensive AIV surveillance. IMPORTANCE Influenza virus surveillance in wild birds plays an important role in the early recognition and control of the virus. However, the AIV gene pool in wild birds in central China along the East Asian-Australasian flyway has not been well studied. Here, we conducted a 5-year AIV active surveillance in this region. Our data revealed the long-term circulation and prevalence of AIVs in wild birds in central China, and we observed that intercontinental gene exchange of AIVs is more frequent and continuous than previously thought. Spillover events from poultry to wild bird were observed in H6 and H9 viruses. In addition, in 20 representative viruses, 12 viruses could bind human-type receptors, and 19 viruses could replicate in mice without preadaption. Our work highlights the potential threat of wild bird AIVs to public health.

Efficacy of traditional Chinese medicine injections for treating idiopathic pulmonary fibrosis: A systematic review and network meta-analysis.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF), acutely or slowly progressing into irreversible pulmonary disease, causes severe damage to patients' lung functions, as well as death. In China, Chinese medicine injections (CMIs) have been generally combined with Western medicine (WM) to treat IPF, which are safe and effective. This study aimed to systematically compare the efficacy of 14 CMIs combined with WM in the treatment of IPF based on a systematic review and network meta-analysis (NMA). MATERIAL AND METHODS: PubMed, Web of Science, Embase, Cochrane Library, MEDLINE, and Chinese databases, including the China National Knowledge Infrastructure, Wanfang Database, Scientific Journal Database, and China Biology Medicine Database were searched from inception to October 31, 2021. The inclusion criterion was randomized controlled trials (RCTs) on CMIs with WM for treating IPF. Reviewers independently screened the literature, extracted data, and evaluated the risk of bias in the included studies. RevMan 5.4 software and Stata software (version 16.0) were used for the data analysis. NMA were carried out for calculating the odd ratios (ORs) with 95% confidence intervals (CI), the surface under cumulative ranking curve (SUCRA) and the probabilities of being the best. RESULTS: A total of 63 eligible RCTs involving 14 CMIs were included in this NMA. More CMIs can significantly improve the clinical effectiveness rate (CER); Shuxuening injection (SXN)+WM (OR 8.91, 95% CI 3.81-20.83), Shuxuetong injection (SXT)+WM (OR 7.36, 95% CI 3.30-16.00), Shenxiong injection (SX)+WM (OR 5.42, 95% CI 2.90-10.13), Danhong injection (DH)+WM (OR 4.06, 95% CI 2.62-6.29), and Huangqi injection (HQ)+WM (OR 3.47, 95% CI 1.55-7.77) were the top five treatment strategies. Furthermore, DH +WM ranked relatively high in the SUCRA value of the nine outcome indicators, oxygen partial pressure (PaO2) (OR -13.39; 95% CI -14.90,-11.89; SUCRA 83.7%), carbon dioxide partial pressure (PaCO2) (OR -4.77; 95% CI -5.55,-3.99; SUCRA 83.3), orced vital capacity (FVC) (OR -1.42; 95% CI -2.47,-0.36; SUCRA 73.5%), total lung capacity (TLC) (OR 0.93; 95% CI 0.51,1.36; SUCRA 89.0%), forced expiratory volume 1/ forced vital capacity (FEV1/FVC%) (OR -10.30; 95% CI -12.98,-7.62; SUCRA 72.7%), type III collagen (IIIC) (OR 13.08; 95% CI 5.11,21.05; SUCRA 54.9%), and transforming growth factor (TGF) (OR -4.22; 95% CI -6.06,-2.37; SUCRA 85.7%) respectively, which seems to indicate that DH+WM had the highest likelihood of being the best treatment. CONCLUSIONS: This review specified several CMIs combined with WM in the treatment of IPF in China. In contrast to glucocorticoids or antioxidants, CMIs combined with WM delayed the decline in lung function, maintained oxygenation and quality of life in patients with IPF. The combined use of DH, SXN, SX, and safflower yellow sodium chloride injection (HHS) with WM exerted a more positive effect in treating IPF than WM alone. However, there were limitations to the conclusions of this study due to quality control differences in the included trials.

[Ecological economics foundation research on ecological values, ecological asset management, and value realization: Scientific concepts, basic theories, and realization paths]. / è‡ªç„¶ç”Ÿæ€ä»·å€¼ã€ç”Ÿæ€èµ„äº§ç®¡ç†åŠä»·å€¼å®žçŽ°çš„ç”Ÿæ€ç»æµŽå­¦åŸºç¡€ç ”ç©¶­­ç§‘学概念、基础理论及实现途径.

Ecosystems provide various environmental conditions and natural resources for life, production, and human livelihoods. Ecosystem management based on natural laws is the basic way for human society to recognize the value of nature and ecosystems, protect and utilize the natural environment and resources, create and accumulate ecological assets, and sustainably develop. Taking that as one of the core concepts, regional ecological economics or economic ecology is becoming a frontier in scientific research to evaluate the Anthropocene earth system and sustainable development. From the perspective of macro-ecosystem science, based on the multi-functionality and multi-values of ecosystems, this study expounded the concepts of natural ecological value, ecological assets, ecological products, and some related phrases, analyzed the processes and principles of formation and change of ecological assets, production and consumption of ecological products, ecological investment, and profit and loss of ecological assets based on integrated ecology, sociology, and economics, proposed paths of regional ecological asset management and ecological value realization. It would provide theoretical and methodological references for the evaluation of regional ecosystem value and ecological assets, and the development of ecological industries and ecological value realization systems.

G Protein Subunit ß1 Facilitates Influenza A Virus Replication by Promoting the Nuclear Import of PB2.

G protein subunit ß1 (GNB1), the beta subunit of the G protein family, plays an important role in regulating transmembrane signal transduction. Although a recent study has demonstrated that GNB1 can bind the matrix protein 1 (M1) to facilitate M1 transport to budding sites and promote the release of progeny influenza A virus (IAV), whether the GNB1 protein has other functions in IAV replication requires further study. Here, we found that GNB1 promoted IAV replication, as virus yield decreased in GNB1 knockdown or knockout cells. GNB1 interacted with polymerase subunits PB2, PB1, and PA. Overexpressed GNB1 facilitated PB2 binding to importin α3, α5, and α7 promoting the nuclear import of PB2, enhancing viral RNA synthesis and polymerase activity. Altogether, our results demonstrated that GNB1 positively regulates virus replication by interacting with polymerase subunits and facilitating the nuclear import of PB2, which provide novel insights into the molecular mechanism of IAV. IMPORTANCE Until now, there has been only one article on the role of GNB1 in IAV budding. No study has investigated the role of GNB1 in IAV replication. In this study, our research demonstrated that GNB1 could increase the interaction between PB2 and the importin α isoform and mediate the nuclear import of PB2. Therefore, GNB1 could promote viral replication and transcription. Our results provide a better understanding of the molecular mechanisms of viral replication and provide potential antiviral drug targets.

[Discussion on the ecological theory and assessment methods of ecosystem quality and its evolution]. / ç”Ÿæ€ç³»ç»Ÿè´¨é‡åŠå ¶çŠ¶æ€æ¼”å˜çš„ç”Ÿæ€å­¦ç†è®ºå’Œè¯„ä¼°æ–¹æ³•ä¹‹æŽ¢ç´¢.

Ecological civilization construction and ecological environment governance are basic tasks of state gover-nance in China. China has clearly put forward the goal of improving ecosystem quality and stability. However, there are no consensus on the scientific concept of ecosystem quality and the assessment methods of ecosystem quality evolution, which has puzzled the academic community. Based on the summarization of the scientific concept of ecosystem quality and its evolution, we discussed the concept of ecosystem quality and its ecological theory basis by referencing the concept of production quality, quality management and quality assessment of material production. The scientific connotation of ecosystem quality and its evolution was discussed from the perspectives of ecosystem natural attribute-social attribute-economic attribute and the relationships between them, the cascade relations of ecosystem component-structure-process-function-service-efficacy, the feedback of factor-system-environment, and the logic relation of state ecosystem fluctuation-quantity variation-quality alternation. We proposed perspectives and approaches of multi-objective assessment of ecosystem quality alternation from the aspects of natural resource environment system, typical ecosystem, regional macro-ecosystem, and ecological engineering efficacy.

[Discussion on the scientific concepts of regional resources and environmental carrying capacity and its ecological basis.] / åŒºåŸŸèµ„æºçŽ¯å¢ƒæ‰¿è½½åŠ›ç§‘å­¦æ¦‚å¿µåŠå ¶ç”Ÿæ€å­¦åŸºç¡€çš„è®¨è®º.

The carrying capacity of resources and environment is an essential concept in ecology, the theoretical and practical research of which has become an important basis for measuring regional sustainable development. However, the scientific connection between the ecological foundation and the carrying capacity of resources and environment is still unclear. Moreover, it remains unknown which ecological theories played a supporting role in the development of the resources and environment carrying capacity, which makes the scientific concept of carrying capacity very vague. Based on the discussion of the scientific concepts and development of the carrying capacity of resources and environmen, we systematically discussed the basic concepts, such as the niche volume that organisms can occupy, the ecological threshold of ecosystems to withstand environmental stress, the potential resource capacity (supply capacity) of sustainable supply such as climate, water and nutrition, and the environmental capacity of buffering and purifying pollutants. Furthermore, from the biophysical point perspective of foundation pressure bearing capacity, spatial capacity carrying capacity and ecological threshold carrying capacity, the scientific concepts of Natural Resources Supply Carrying Capacity (NRSCC), Nature Environment Carrying Capacity (NECC), Carrying Capacity of Biological Population Development (CCBPD), Carrying Capacity of Social and Economic Development (CCSED) and Carrying Capacity of Environmental Stress in Ecosystems (CCESE) were defined. Finally, three basic issues of ecology were discussed in detail, including the theory of population growth and the ecological capacity of the ecosystem, the theory of ecosystem multi-functionality and resource and environmental effects, and the theory of alternative stable states, self-adaptability, and self-organization. Based on exploring the theory and method of regional resource environmental assessment, this study would provide theoretical basis for regional resource environment utilization, protection and social and economic sustainable development.

[Evaluation theory and method of regional resources and environmental carrying capacity.] / 区域资源环境承载力的评价理论及方法讨论.

Our understanding of resources and environmental carrying capacity is deepened with the comprehensive effects of human needs and external stress. When human survival and development mainly depend on the supply of local resources and environmental conditions, the resources and environmental carrying capacity is largely controled by the dominant limiting factors. With sustainable development and environmental protection, the resources and environmental carrying capacity has gradually changed from supply restriction to demand support. There is an expression of capacity, threshold, intensity, and ability to characterize the resources and environmental carrying capacity. The impact of climate change and human activities on the resource and environmental system is increasing, altering resources and environmental carrying capacity. At present, the interrelationship and internal mechanism among resource and environmental carrying capacity, ecosystem vulnerability, and climate change risk are still unclear, which restricts the further development of theory and method. We preliminarily summarized and discussed the basic theory and method system of the research on carrying capacity of regional resources and environment. Furthermore, we advocated to develop the cascade relations of "carrying capacity of biological population development-carrying capacity of environmental stress in ecosystems-natural resources supply carrying capacity-natural environment carrying capacity-carrying capacity of social and economic development". Moreover, the calculation method and conceptual model of multi-dimensional resource and environmental carrying capacity were put forward under each concept framework. This study provided new ideas for the research on the method of resources and environment carrying capacity.

[Research advances in critical transition and its ecological mechanisms of terrestrial ecosystems.] / é™†åœ°ç”Ÿæ€ç³»ç»Ÿä¸´ç•Œè½¬æ¢ç†è®ºåŠå ¶ç”Ÿæ€å­¦æœºåˆ¶ç ”ç©¶è¿›å±•.

With the exacerbating disturbances of climate changes and human activities to terrestrial ecosystems, more and more studies realize that ecosystems are at the risk of shifts without warning in structural and functional states and recovery from perturbations require more time. Developing an early warning model to identify critical transition and understanding its ecological mechanism of typical ecosystems have become hotspot in ecological researches. At present, based on theoretical and experimental researches across multiple spatiotemporal scales, a variety of theoretical frameworks and indicators of early warning signals (EWSs) were proposed to signal terrestrial ecosystem critical transition. Here, in order to more thoroughly understand and construct theoretical frameworks and indicators of early warning signals, we reviewed advances in critical transitions from aspects of theoretical methods and processing mechanisms. Catastrophe theory and critical slowing down (CSD) are the two basic theories for early-warning ecosystem state transitions. Self-organization and feedback mechanisms are the primary ecological mechanisms to shape alternative stable state. Understanding cascade effects networks (CENet) among biological and environmental elements, and clarifying the equilibrium relationships between input and output of key ecosystem parameters are theoretical foundation of critical transition model. These theoretical cognitions could provide useful references to early warning of ecosystem disasters, ecological environment management and restoration.

[Theories of ecosystem vulnerability, adaptability and catastrophe based on the mechanisms of ecological succession.] / 基于生态系统演变机理的生态系统脆弱性、适应性与突变理论.

With the increases in the breadth and depth of the impacts of climate change, the theories of ecosystem vulnerability, adaptability and catastrophe have gradually been widely applied in the field of ecology to explore and evaluate the sensitivity, vulnerability and adaptation of various ecosystems to climatic change. Based on such research, we can seek better ways to cope with the far-reaching impact of climatic change on ecosystems, and serve the sustainable management of national ecosystems and the construction of ecological security. Although a lot of achievements have been made to distinguish the sensitive regions responding to climatic change and potential tipping points in certain ecosystems, there are still multiple understandings and interpretations of these concepts in the academic community. To some extent, this affects the further development and application of related theories in ecological studies. Therefore, we combed the development history of related concepts, and analyzed the connotation of these concepts from the perspective of ecosystem ecology. Furthermore, we proposed a theoretical framework for ecosystem fragility, adaptability, and catastrophe based on the ecosystem evolution theory and corresponding calculation methods in order to promote the in-depth development of theories of ecosystem fragility, adaptability and catastrophe.

Sperm-Associated Antigen 9 Promotes Influenza A Virus-Induced Cell Death via the c-Jun N-Terminal Kinase Signaling Pathway.

Upon influenza A virus (IAV) infection, the IAV progeny ribonucleoprotein complex, with a defective viral genome, is sensed by DNA-dependent activator of interferon-regulatory factor (DAI). DAI initiates the recruitment of an array of proteins to form a multiprotein platform (PANoptosome), which triggers apoptosis, necroptosis, and pyroptosis during IAV infection. However, the mechanisms mediating the assembly of the PANoptosome are unclear. Here, we identified a scaffold protein, sperm-associated antigen 9 (SPAG9), which could interact with DAI to promote cell death during IAV infection. We further demonstrated that the cell death enhanced by SPAG9 was achieved through the DAI/SPAG9/c-Jun N-terminal kinase (JNK) axis, which could promote IAV-induced DAI-mediated cell death, including apoptosis, necroptosis, and pyroptosis. Our data further showed that the DAI/SPAG9/JNK signaling pathway enhanced the interactions among receptor-interacting serine/threonine kinase 1 (RIPK1), RIPK3, and DAI, thereby promoting IAV-induced PANoptosome formation. Overall, our study for the first time revealed a feed-forward circuit signaling pathway that enhanced IAV-induced DAI-mediated cell death, provided insights into the molecular mechanisms of cell death, and established therapeutic targets to address infectious and inflammatory diseases. IMPORTANCE Upon influenza A virus (IAV) infection, DAI is activated, recruits downstream proteins to assemble a multiprotein platform (PANoptosome), and then triggers cell death. Until now, the protein composition and assembly mechanism of the PANoptosome during IAV infection had not been elucidated. Using proximity labeling and mass spectrometry technology, we identified SPAG9 as a novel component of the PANoptosome and confirmed that SPAG9 promotes IAV-induced cell death by enhancing the interaction among RIPK1, RIPK3, and DAI. Our study will broaden the knowledge of the molecular mechanisms of cell death.