Prophylactic nicotinamide mononucleotide (NMN) mitigates CSDS-induced depressive-like behaviors in mice via preserving of ATP level in the mPFC.

Depression is a prevalent psychiatric disorder with accumulating evidence implicating dysregulation of extracellular adenosine triphosphate (ATP) levels in the medial prefrontal cortex (mPFC). It remains unclear whether facilitating endogenous ATP production and subsequently increasing extracellular ATP level in the mPFC can exert a prophylactic effect against chronic social defeat stress (CSDS)-induced depressive-like behaviors and enhance stress resilience. Here, we found that nicotinamide mononucleotide (NMN) treatment effectively elevated nicotinamide adenine dinucleotide (NAD+) biosynthesis and extracellular ATP levels in the mPFC. Moreover, both the 2-week intraperitoneal (i.p.) injection and 3-week oral gavage of NMN prior to exposure to CSDS effectively prevented the development of depressive-like behavior in mice. These protective effects were accompanied with the preservation of both NAD+ biosynthesis and extracellular ATP level in the mPFC. Furthermore, catalyzing ATP hydrolysis by mPFC injection of the ATPase apyrase negated the prophylactic effects of NMN on CSDS-induced depressive-like behaviors. Prophylactic NMN treatment also prevented the reduction in GABAergic inhibition and the increase in excitability in mPFC neurons projecting to the lateral habenula (LHb). Collectively, these findings demonstrate that the prophylactic effects of NMN on depressive-like behaviors are mediated by preventing extracellular ATP loss in the mPFC, which highlights the potential of NMN supplementation as a novel approach for protecting and preventing stress-induced depression in susceptible individuals.

Machine Learning-Assisted Optimization of Mixed Carbon Source Compositions for High-Performance Denitrification.

Appropriate mixed carbon sources have great potential to enhance denitrification efficiency and reduce operational costs in municipal wastewater treatment plants (WWTPs). However, traditional methods struggle to efficiently select the optimal mixture due to the variety of compositions. Herein, we developed a machine learning-assisted high-throughput method enabling WWTPs to rapidly identify and optimize mixed carbon sources. Taking a local WWTP as an example, a mixed carbon source denitrification data set was established via a high-throughput method and employed to train a machine learning model. The composition of carbon sources and the types of inoculated sludge served as input variables. The XGBoost algorithm was employed to predict the total nitrogen removal rate and microbial growth, thereby aiding in the assessment of the denitrification potential. The predicted carbon sources exhibited an enhanced denitrification potential over single carbon sources in both kinetic experiments and long-term reactor operations. Model feature analysis shows that the cumulative effect and interaction among individual carbon sources in a mixture significantly enhance the overall denitrification potential. Metagenomic analysis reveals that the mixed carbon sources increased the diversity and complexity of denitrifying bacterial ecological networks in WWTPs. This work offers an efficient method for WWTPs to optimize mixed carbon source compositions and provides new insights into the mechanism behind enhanced denitrification under a supply of multiple carbon sources.

Elevated dorsal medial prefrontal cortex to lateral habenula pathway activity mediates chronic stress-induced depressive and anxiety-like behaviors.

The medial prefrontal cortex (mPFC) sends projections to numerous brain regions and is believed to play a significant role in depression and anxiety. One of the key downstream targets of the mPFC, the lateral habenula (LHb), is essential for chronic stress (CS)-induced depressive and anxiety-like behaviors. Nevertheless, whether the mPFC-LHb pathway mediates the co-occurrence of depression and anxiety and the underlying mechanism remain incompletely understood. Here, using chemogenetics, we first determined that activation of LHb-projecting mPFC neurons is essential for the development of depressive and anxiety-like behaviors induced by CS. Subsequently, we identify the extent and distribution of LHb-projecting neurons originating from the mPFC subregion. Through circuit-specific in vivo fiber photometry, we found that Ca2+ activity in dorsal mPFC (dmPFC) axon terminals within the LHb was increased during exposure to stressful and anxiety-related stimuli, highlighting the potential role of LHb-projecting dmPFC neurons in conveying stressful and anxiety-related information to the LHb. Finally, we observed that activation of both LHb-projecting dmPFC neurons and their postsynaptic counterparts in the LHb was necessary for CS-induced depressive and anxiety-like behaviors. Overall, this study provides multiple lines of evidence demonstrating that activation of the dmPFC-LHb pathway is a crucial neural circuitry for CS-induced depressive and anxiety-like behaviors.

Correction: The Cardiorespiratory fitness of children and adolescents in Tibet at altitudes over 3,500 meters.

[This corrects the article DOI: 10.1371/journal.pone.0256258.].

Unraveling heterogeneity of dissolved organic matter in highly connected natural water bodies at molecular level.

The exploring of molecular-level heterogeneity of dissolved organic matter (DOM) in highly connected water bodies is of great importance for pollution tracing and lake management, and provides new perspectives on the transformations and fate of DOM in aquatic systems. However, the inherent homogeneity of DOM in connected water bodies poses challenges for its heterogeneity analysis. In this work, an innovative method combining fluorescence spectroscopy, high-resolution mass spectrometry (HRMS), and cluster analysis was developed to reveal the heterogeneity of DOM in highly connected water bodies at the molecular level. We detected 4538 molecules across 36 sampling sites in Chaohu Lake using HRMS. Cluster analysis based on excitation-emission matrix (EEM) data effectively divided the sampling sites into four clusters, representing the water bodies from West Chaohu Lake, East Chaohu Lake, agricultural land, and urban areas. Analysis of DOM in the western and eastern parts of the lake revealed that aerobic degradation led to a decrease in CHOS and aliphatic compounds, alongside an increase in CHO and highly unsaturated and phenolic compounds. Furthermore, we unveiled the characteristics and sources of heterogeneity in DOM from agricultural land and urban areas. Our method accurately captured the heterogeneous distribution of DOM in the lake and revealed the heterogeneous composition of DOM at molecular level. This work underscores the importance of integrating complementary spectroscopic analyses with HRMS in DOM research with similar compositions.

Carbon source shaped microbial ecology, metabolism and performance in denitrification systems.

The limited information on microbial interactions and metabolic patterns in denitrification systems, especially those fed with different carbon sources, has hindered the establishment of ecological linkages between microscale connections and macroscopic reactor performance. In this work, denitrification performance, metabolic patterns, and ecological structure were investigated in parallel well-controlled bioreactors with four representative carbon sources, i.e., methanol, glycerol, acetate, and glucose. After long-term acclimation, significant differences were observed among the four bioreactors in terms of denitrification rates, organic utilization, and heterotrophic bacterial yields. Different carbon sources induced the succession of denitrifying microbiota toward different ecological structures and exhibited distinct metabolic patterns. Methanol-fed reactors showed distinctive microbial carbon utilization pathways and a more intricate microbial interaction network, leading to significant variations in organic utilization and metabolite production compared to other carbon sources. Three keystone taxa belonging to the Verrucomicrobiota phylum, SJA-15 order and the Kineosphaera genus appeared as network hubs in the methanol, glycerol, and acetate-fed systems, playing essential roles in their ecological functions. Several highly connected species were also identified within the glucose-fed system. The close relationship between microbial metabolites, ecological structures, and system performances suggests that this complex network relationship may greatly contribute to the efficient operation of bioreactors.

Expression of MSTN/Smad signaling pathway genes and its association with meat quality in Tibetan sheep (Ovis aries).

Tibetan sheep is a unique breed living in Qinghai-Tibet Plateau. Since MSTN/Smad signaling pathway plays a critical role in the regulation of muscle development, we aimed to study the mutton quality, mRNA expression of main transduction genes in the MSTN/Smad signaling pathway, and the effects of those genes on the mutton quality of Tibetan sheep in this study. Six-month-old Qinghai-Tibetan sheep were selected, slaughtered, and their Longissimus lumborum, semitendinosus muscle, arm triceps, and quadriceps femoris muscle were collected. The mutton quality was evaluated, and gene expression and their association with the mutton quality were analyzed using RT-qPCR. The results showed that the indexes of mutton quality were not significantly different between ewes and rams (p > .05) except for Warner-Bratzler shear force (WBSF) (p < .05). A total of 21 different fatty acids were detected in the muscles of Tibetan sheep, including nine types of SFA, four types of MUFA, and eight types of PUFA. The main transduction genes of the MSTN/Smad signaling pathway were found to be widely expressed in muscle tissues, but no significant differences were observed (p > .05). The correlation analysis of the main genes and mutton quality showed that MSTN was significantly correlated with redness and cooking time; Smad2, Smad3, Smad4, and TGFßRI had significant positive correlations with marbling in arm triceps; Smad3 and TGFßRII had strong negative correlations with pH24 h in Longissimus lumborum; Smad2 was negatively correlated with drip loss in Longissimus lumborum. In short, the expression level of MSTN in muscles was positively correlated with Smad2, Smad3, and Smad4 genes and negatively correlated with TGFßRII genes. Thus, the results of this study provide a theoretical basis for the regulation mechanism of the MSTN/Smad pathway on mutton quality.

Molecular characterization and expression of TGFßRI and TGFßRII and its association with litter size in Tibetan sheep.

BACKGROUNDS: Transforming growth factor-ß (TGF-ß) type I receptor (TGFßRI) and type II receptor (TGFßRII) are the members of the TGFß superfamily, which are potent regulators of cell proliferation and differentiation in many organ systems, and they play key roles in multiple aspects of follicle development. OBJECTIVES: We aimed to explore the characterization, expression analysis of TGFßRI and TGFßRII genes, and the association with litter size in Tibetan sheep. METHODS: In this study, we cloned the complete coding sequences of TGFßRI and TGFßRII genes in Tibetan sheep and analyzed their genomic structures. RESULTS: The results showed that percentages of sequences homology of the two proteins in Tibetan sheep were the most similar to Ovis aries (100%), followed by Bos mutus (99%). The RT-qPCR showed that two genes were expressed widely in the different tissues of Tibetan sheep. The TGFßRI expression was the highest in the lung (p < 0.05), followed by the spleen and ovary (p < 0.05). The TGFßRII expression was significantly higher in uterus than that in lung and ovary (p < 0.05). In addition, the χ2 test indicated that all ewes in the population were in Hardy-Weinberg equilibrium, and the population was in medium or low polymorphic information content status. We also found four Single Nucleotide Polymorphism (SNPs), g.9414A > G, g.28881A > G, g.28809T > C, g.10429G > A in sheep TGFßRI gene and g.63940C > T, g.63976C > T, g.64538C > T, g.64504T > A in TGFßRII gene. Three genotypes, except for g.64504T > A, and three haplotypes were identified in each gene. linkage disequilibrium analysis indicated that there was strong linkage disequilibrium in each gene. The association analysis showed that the four SNPs of TGFßRI were associated with litter size (p < 0.05), and g.63940C > T of TGFßRII was confirmed to be associated with litter size (p < 0.05). CONCLUSIONS: Based on these preliminary results, we can assume that TGFß receptors (TGFßRI and TGFßRII) may play an important role in sheep reproduction.

Expression and Polymorphisms of SMAD1, SMAD2 and SMAD3 Genes and Their Association with Litter Size in Tibetan Sheep (Ovis aries).

SMAD1, SMAD2, and SMAD3 are important transcription factors downstream of the TGF-ß/SMAD signaling pathway that mediates several physiological processes. In the current study, we used cloning sequencing, RT-qPCR, bioinformatics methods and iMLDR technology to clone the coding region of Tibetan sheep genes, analyze the protein structure and detect the tissue expression characteristics of Tibetan sheep genes, and detect the polymorphisms of 433 Tibetan sheep and analyze their correlation with litter size. The results showed that the ORFs of the SMAD1, SMAD2 and SMAD3 genes were 1398 bp, 1404 bp and 1278 bp, respectively, and encoded 465, 467 and 425 amino acids, respectively. The SMAD1, SMAD2, and SMAD3 proteins were all unstable hydrophilic mixed proteins. SMAD1, SMAD2 and SMAD3 were widely expressed in Tibetan sheep tissues, and all were highly expressed in the uterus, spleen, ovary and lung tissues. Litter sizes of the genotype CC in the SMAD1 gene g.10729C>T locus were significantly higher than that of CT (p < 0.05). In the SMAD3 gene g.21447C>T locus, the genotype TT individuals showed a higher litter size than the CC and CT genotype individuals (p < 0.05). These results preliminarily demonstrated that SMAD1, SMAD2 and SMAD3 were the major candidate genes that affected litter size traits in Tibetan sheep and could be used as a molecular genetic marker for early auxiliary selection for improving reproductive traits during sheep breeding.

Molecular Characterization, Expression Profiles of SMAD4, SMAD5 and SMAD7 Genes and Lack of Association with Litter Size in Tibetan Sheep.

SMAD4, SMAD5 and SMAD7 belonging to the transforming growth factor ß (TGF-ß) superfamily are indispensable for oocyte formation and development, ovarian organogenesis and folliculogenesis. However, only a few studies have investigated the characteristics of SMAD4, SMAD5 and SMAD7 in Tibetan sheep and the effect of their polymorphism on litter size. In this study, we examined the expression of SMAD4, SMAD5 and SMAD7 in 13 tissues of Tibetan sheep by reverse transcription-quantitative polymerase chain reaction. Further, cDNA of these genes was cloned, sequenced and subjected to bioinformatics analysis. DNA sequencing was also used to detect single nucleotide polymorphisms (SNPs). However, iM-LDRTM technology was used for SNP genotyping. Associations between polymorphisms and litter size were analyzed using data from genotyping of 433 Tibetan sheep. The results showed that the expression of SMAD4, SMAD5 and SMAD7 genes was ubiquitous in the tissues of Tibetan sheep, such as the ovary, uterus and oviduct, hypothalamus, hypophysis, heart, liver, spleen, lung, kidney, rumen, duodenum and longissimus dorsi. However, the expression was unbalanced and upregulated in the spleen, lung, ovary and uterus and downregulated in the longissimus dorsi. The bioinformatics analysis showed that SMAD4, SMAD5 and SMAD7 in Tibetan sheep encoded proteins of 533, 465 and 427 amino acids, respectively. Sequence homology analysis of the three proteins among other animals showed that the sequences of SMAD4, SMAD5 and SMAD7 of Tibetan sheep were similar to those in sheep, yak, cattle, dog, human, pig, chimpanzee, rhesus monkey and house mouse. Two synonymous mutations, g.51537A>G and g.319C>T, were detected in SMAD5 and SMAD7, respectively. The associations of these SNPs and litter size were determined, and it was found that both g.51537A>G and g.319C>T have no significant effect on the litter size of Tibetan sheep. The results provided novel insights into the molecular characterization, expression profiles and polymorphisms of SMAD4, SMAD5 and SMAD7 in Tibetan sheep, but our results do not support associations between these genes and the litter size of Tibetan sheep.

The Cardiorespiratory fitness of children and adolescents in Tibet at altitudes over 3,500 meters.

BACKGROUND: Cardiorespiratory fitness (CRF) is the core element of health-related physical fitness evaluation. High pressure and low oxygen in Tibet (over 3,500 m above sea level) may negatively impact the residents' CRF. The 20-m shuttle run test (20mSRT) is the most popular field-based assessment and estimate of CRF in children and adolescents worldwide. However, normative CRF data for the children and adolescents residing in China's plateau region are unavailable, which prevents comparability among those living at high-altitudes around the world. PURPOSE: To measure the CRF of Chinese children and adolescents aged 9-18 years living in Tibet at altitudes exceeding 3,500 m, and to identify correlations between this metric and demographic characteristics (age, sex, and ethnicity). These data were then compared with those generated in the lowland (Shanghai, China) and various global regions. METHODS: 20mSRT performance (number of completed laps) and predicted peak oxygen consumption (VO2peak) were used as indicators of CRF. We measured the CRF of 1,717 healthy children and adolescents aged 9-18 years living in Tibet. The CRF data from school-age subjects in Shanghai (2,437 boys and 2,396 girls) and worldwide (1,142,026 students from 50 countries/regions in Africa, Asia, Europe, Latin America, North America, and Oceania) were collated from published papers. RESULTS: The average CRF of the participants from Tibet was 39.8 mL/kg/min. The male subjects (n = 876; 41.1 ± 4.42 mL/kg/min) had a higher average CRF than their female counterparts (n = 841; 37.8 ± 5.40 mL/kg/min). CRF decreased with age in both sexes at statistical significance (F = 1249.9, p for trend 0.05). The indigenous Tibetans (n = 1289; 40.1 ± 3.71 mL/kg/min) had a significant higher average CRF than those of Han descent (n = 394; 38.9 ± 4.70 mL/kg/min) (p < 0.05). CONCLUSIONS: Children and adolescents aged 7-18 years residing above 3,500 m in Tibet displayed lower CRF traits compared with their counterparts from the plains area and other high altitude places. CRF varied according to age, sex, and ethnic group. Given the importance of CRF in children and adolescents, effective intervention strategies should be implemented to improve CRF in children and adolescents on the plateau.

Accelerometer-Measured Physical Activity in Children and Adolescents at Altitudes over 3500 Meters: A Cross-Sectional Study in Tibet.

There is a scarcity of studies on the physical activity (PA) of children and adolescents who live at high altitudes. This study aimed to objectively assess PA of children and adolescents living in the Tibet at altitudes over 3500 m and to examine its difference by ethnicity, gender, age/grade, and body weight status groups. A sample of 397 students aged 9⁻18 years were recruited from 7 schools in Lhasa, Tibet. PA was measured using accelerometers (ActiGraph GT3X) for seven consecutive days and moderate to vigorous PA (MVPA) was identified using the Evenson (2008) cut-points. Participant MVPA was 62.3 min/day, with 65.5 min/day during weekdays and 54.1 min/day on weekends. Indigenous Tibetans were more active than Hans, and boys had more MVPA than girls. Age had a significantly weak negative correlation with MVPA. There was no significant difference in MVPA between the non-overweight and overweight/obese groups. Overall, only 9.1% (13.8% in boys and 4.5% in girls) accumulated at least 60 min of MVPA per day. Compared to their counterparts in other regions, the daily MVPA of children and adolescents living on the Tibetan Plateau at altitudes over 3500 m was relatively high. However, the proportion of meeting the WHO's PA recommendations was extremely low.