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Alpine wetland litter decomposition under wet and dry conditions: A comparative study of native vs. standardized litter

Alpine wetlands, critical ecosystems in high-altitude mountain areas, play essential roles in water conservation, biodiversity protection, and carbon (C) sequestration. These ecosystems are particularly sensitive to climate change, with temperature and precipitation variations significantly impacting their structure and functional processes, such as litter decomposition, a key mechanism for C stabilization. This study focused on the Zoige wetland, a representative alpine wetland located on the eastern edge of the Qinghai-Tibet plateau. An incubation experiment was conducted with soil samples under simulated wet and dry moisture conditions to evaluate the environmental impacts on litter decomposition within this ecosystem. In this study, we employed the Tea Bag Index method, utilizing standardized litter, alongside native litter bags to compare the decomposition processes. This comparison between the uniform composition of standardized litter and the chemically diverse native plant litter aims to provide a comprehensive understanding of litter decomposition dynamics in alpine wetland ecosystems. Our finding showed that both standardized and native litter decomposition significantly decreased under dry conditions, in contrast to wetter condition. The components of both standardized and native litter exhibited a decrease over time, with the easily decomposable fractions breaking down swiftly, in contrast to the slower decomposition of the more resistant components. Furthermore, soil exo-enzyme activities varied significantly with environmental conditions. Wet conditions were observed to enhance soil microbial activity, whereas dry conditions resulted in shifts in microbial biomass C and nitrogen, indicative of drought resilience. The correlation analysis revealed that the composition of native litter is the primary factor influencing its decomposition. In contrast, the decomposition of standardized litter was influenced by both its composition and soil microbial activity. Thus, the distinction between the influences on native and standardized litter decomposition highlights the necessity of considering both litter quality and microbial interaction in ecological studies. This approach offers critical insight into the advantages and limitations of each decomposition methodology within alpine wetland ecosystems.

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Open Access
Spring Viremia of Carp Virus Infection Induces Carp IL-10 Expression, Both In Vitro and In Vivo.

Interleukin-10 (IL-10) is a pleiotropic cytokine with both immune enhancement and immunosuppression activities, but the main role is immunosuppression and anti-inflammatory ability. In order to use the immunosuppressive function of IL-10, many viruses, such as SARS-CoV-2, hepatitis B virus and EB virus, can evade the host's immune surveillance and clearance by increasing the expression of host IL-10. However, it has not been reported whether the aquatic animal infection virus can upregulate the expression of host IL-10 and the mechanisms are still unknown. Spring viremia of carp (SVC) is a fatal viral disease for many fish species and is caused by spring viremia of carp virus (SVCV). This disease has caused significant economic losses in the aquaculture industry worldwide. In this study, the expression of carp IL-10 with or without infection of SVCV in epithelioma papulosum cyprinid (EPC) cells, carp head kidney (cHK) primary cells and common carp tissues were analyzed using RT-PCR and ELISA. The results show that SVCV infection induced carp IL-10 mRNA and protein expression, both in vitro and in vivo. However, the upregulation of carp IL-10 by SVCV was hindered by specific inhibitors of the JAK inhibitor (CP-690550), STAT3 inhibitor (STA-21), NF-κB inhibitor (BAY11-7082) and p38 MAPK (mitogen-activated protein kinase) inhibitor (SB202190), but not JNK inhibitor (SP600125). Furthermore, the results demonstrated that JAK1, JAK2, JAK3, TYK2 and STAT5 played important roles in carp IL-10 production induced by SVCV infection. Taken together, SVCV infection significantly induced carp IL-10 expression and the upregulation trigged in JAK-STAT, NF-κB and p38MAPK pathways. To our knowledge, this is the first time that a fish infection virus upregulated the host IL-10 expression through the JAK-STAT, NF-κB and p38MAPK pathways. Altogether, fish viruses may have a similar mechanism as human or other mammalian viruses to escape host immune surveillance and clearance.

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Open Access
Development of Secondary SSSLs and Analysis of QTL for Grain Size as well as Fine-mapping of qGL3.4 Based on a Rice CSSL-Z668

Abstract Background Grain size is an important factor affecting yield, appearance and processing quality of rice. Therefore, it is of great significance to explore genes controlling grain size in rice. However, its genetic mechanisms are complex and belong to quantitative inheritance controlled by polygenes with minor effects. Chromosome segment substitution lines are ideal materials for natural variation creation, QTL dissection, functional analysis and pyramid breeding of favorable alleles. Results Z668 was identified containing 8 substitution segments from indica restorer line R225 in the genetic background of Nipponbare. Its average substitution length was 3.63 Mb. Compared with Nipponbare, Z668 plants exhibited significant dwarf, and the grain length, ratio of length to width and 1000-grain weight of Z668 was increased by 39.9%, 31% and 25.9%, respectively, and grain width of Z668 was decreased by 3.3%. Then, a total of 7 QTLs for grain size were identified from F2 populations derived from Nipponbare/Z668, including 3 for grain length (qGL3.4, qGL12-1, qGL12-2), 3 for ratio of length to width (qRLW3.4, qRLW12-1, qRLW12-2), and 1 for 1000-grain weight (qGWT7), which were found distributing on chromosomes 3, 7 and 12. Finally, 5 single segment substitution lines were developed and 13 QTLs (qGL1, qGL6, qGL7, qGL12-2, qGW7-1, qGW7-2, qRLW1, qRLW6, qRLW7-1, qRLW7-2, qRLW12-2, qGWT6 and qGWT7) were detected by them. Among them qGL1, qGL3.4, qGL12-1 and qGL12-2 might be new QTLs identified in the study, In addition, qGL3.4 controlling long grain displayed dominant inheritance by analysis of frequency distribution in F3 population developed by recombinant plants of single qGL3.4 locus and Chi-square test. And qGL3.4 was then fine mapped into the 300 kb region between SSR3 and SSR4 on chromosome 3 by 142 recessive plants with short-grains and 5 polymorphic SSR markers designed in the substitution interval RM5864 and RM5626 where qGL3.4 was located. By gene prediction, 7 genes were found to be associated with grain size. And through DNA amplification and sequencing as well as qRT-PCR analysis, the candidate1 and 3 were considered as preferred candidate genes for qGL3.4.

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Meta-Analysis of Organic Fertilization Effects on Soil Bacterial Diversity and Community Composition in Agroecosystems.

Application of organic fertilizers or their combination with chemical fertilizers is a feasible practice for improving soil fertility and reducing soil degradation in agroecosystems, and these regulations are mainly mediated though soil microbial communities. Despite bacteria ranking among the most abundant and diverse groups of soil microorganisms, the effects of long-term organic fertilization (OF) and chemical-organic fertilization (COF) on soil bacterial diversity and community composition remain unclear. In this study, we conducted a meta-analysis and demonstrated that OF had no significant effect on bacterial alpha diversity. Application of chemical fertilizer and crop residue significantly decreased bacterial Richness index. Both OF and COF significantly altered bacterial community structure, with these changes being predominately attributed to shifts in soil pH. For bacterial phyla, both OF and COF significantly increased the relative abundance of Proteobacteria and Bacteroidetes, suggesting that OF and COF may cause the enrichment of copiotrophic taxa. In addition, COF significantly increased the relative abundance of Gammaproteobacteria but decreased the relative abundance of Acidobacteria. Overall, our results suggest that organic and chemical-organic fertilization can effectively maintain bacterial diversity and enhance soil fertility in agroecosystems, and the alteration of soil bacterial community structure is closely intertwined with soil pH.

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Open Access
Positive Effects of Organic Amendments on Soil Microbes and Their Functionality in Agro-Ecosystems.

Soil microbial characteristics are considered to be an index for soil quality evaluation. It is generally believed that organic amendments replacing chemical fertilizers have positive effects on changing microbial activity and community structure. However, their effects on different agro-ecosystems on a global scale and their differences in different environmental conditions and experimental durations are unclear. This study performed a meta-analysis based on 94 studies with 204 observations to evaluate the overall effects and their differences in different experimental conditions and duration. The results indicated that compared to chemical fertilizer, organic amendments significantly increased total microbial biomass, bacterial biomass, fungal biomass, Gram-positive bacterial biomass and Gram-negative bacterial biomass, and had no effect on the ratio of fungi to bacteria and ratio of Gram-positive bacteria to Gram-negative bacteria. Meanwhile, land use type, mean annual precipitation and soil initial pH are essential factors affecting microbial activity response. Organic-amendment-induced shifts in microbial biomass can be predominantly explained by soil C and nutrient availability changes. Additionally, we observed positive relationships between microbial functionality and microbial biomass, suggesting that organic-amendment-induced changes in microbial activities improved soil microbial functionality.

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Open Access